Case study-Rihand- Erection strategy

ERECTION STRATEGY FOR BOILER –
NTPC RIHAND STPP STAGE - 2
BASIC STRATEGY:
Basic strategy shall be to go in for cycle time reduction in every area by
taking up erection of all possible fronts Parallelly , system completion at first
go itself and by applying innovative ideas and modern erection practices. To
achieve this we shall have highly experienced and effective execution team
posted at site with back up of strong infrastructural support made available
to them. They shall be always aiming for achieving the project milestones as
planned by changing the intermediate course of direction depending on
availability of inputs. The infrastructural support and basic erection
sequences / strategy are explained below.
SUBCONTRACTING STRATEGY:
Subcontractors shall be finalized from the list of vendors duly approved by
NTPC (as applicable as per agreement) for following packages,
1) Main boiler and Rotating equipments
2) ESP and Flue gas duct beyond boiler
3) Power Cycle piping
4) Lining and insulation
INSPECTION & QUALITY:
An exclusive ‘Quality group’ at site ensures all installation checks and stage
protocols with respect to approved quality plans for individual system,
involving Consultant/ Customer representatives.
In addition to this, to ensure system completion, before execution of a
defined Mile Stone activity during installation, an audit team from PS-WR HQ
visits the site before Construction Manager is permitted to execute the Mile
Stone activity.
SAFETY:
An exclusive officer shall be deployed at job site to guide, monitor and
control all HSE related activities as per company’s HSE instructions. He shall
directly report to Construction Manager. Also our erection agencies shall
nominate exclusive safety supervisor to assist us.
MATERIAL MANAGEMENT:
Unique identification system for components is utilized by all BHEL units. A
strong team of officers and supervisors shall keep intensive track records of
dispatches, receipt, storage and issues of components using modern
electronic media.
Page 118 of 175
On receipt, components shall be inspected and verified before storage.
Exclusive Material Receipt cum Inspection Reports shall be prepared along
with Consultant/Customer representative.
Components shall be stored in Open, Semi-closed, closed or special
environment conditions as applicable. They shall be preserved during storage
and installation stages as per the instruction given in our preservation
manual.
A comprehensive tracking system, with appropriate records shall be
maintained for all issues.
DOCUMENTATION AT SITE:
A totally computerized documentation system shall be adopted at site to
keep track of total drawings and manuals required to complete installation to
ensure proper monitoring of receipt, issue and revisions.
FACILITY ENGINEERING AT SITE:
An exclusive executive shall be deployed to supervise and monitor the
availability of T&P’s being provided by BHEL.
TOOLS AND PLANTS:
Sufficient numbers of T&P s shall be deployed either by BHEL or by their
erection agencies.
MANPOWER DEPLOYMENT:
Sufficient number of BHEL staff shall be posted for installation of this
package.
Following shall be tentative manpower (main category) deployment plan per
unit by erection agencies;
Boiler erection agency: Engineer- 7 , supervisors- 15 ,Rigger foreman- 2 ,
Fitters- 27 , Structural welder – 30 , HP welder – 12 , Gas cutter - 4 ,
Grinder – 10 , SR technician – 4 , Radiographic Technician- 4
ESP erection agency: Engineer- 1 , supervisors- 4 ,Rigger foreman- 1 ,
Fitters- 12 , Structural welder – 15 , Gas cutter- 2 , Grinder-2
Piping erection agency: Engineer- 3 , supervisors- 6 ,Rigger foreman- 2 ,
Fitters- 12 , Structural welder – 10 , HP welder – 10 , Gas cutter - 2 ,
Grinder- 6 , SR technician – 4 , Radiographic Technician- 4
Page 119 of 175
ERECTION SEQUENCE:
BOILER SUPPORTING STRUCTURE:
Main supporting structure columns (Nos. S1to S6 L&R, S7 to S12 L&R,
S13L&R, shall be erected in following combinations:
Bottom tier - single piece
2nd & 3rd tier combined with Tata 75 MT and Link Belt LS 248H
4th & 5th tier combined
6th & 7th tier combined ---------------- with FMC LS 718 HLA 330 ft boom
+ Jib
All connected horizontal beams, MBL members, and vertical diagonal
bracings as required to maintain verticality of the columns shall be erected
before proceeding to next level. All MBL members between box of four
columns shall be judiciously pre assembled on ground to ensure better
workmanship and speedy erection. Erection of all balance items of such
components shall precede parallels and shall be completed prior to ceiling
girder lifting.
It may be noted that all columns for Rihand shall be trial assembled in full
length at Trichy, hence pre assembly and joint matching at site shall not be
required.
Once the structure as mentioned above are erected and verticality of
columns are ensured Ceiling girder erection shall start. Ceiling Girder
Erection shall be done in following sequence:
With 1st rigged position of FMC - Girder '0', Girder-A, Girder-'B'
With 2nd rigged position of FMC -Girder-'C', Girder-'D'
With 3rd rigged position of FMC - Girder-'E'
Ceiling girders will be supplied in three pieces and shall be pre assembled on
ground before lifting. It may be noted that casting of foundation
pedestal of FD fan-B to be hold till ceiling girder C&D is shifted to
boiler cavity after pre assembly. Also it may be noted that the bottom
most vertical diagonal bracing between columns S10 R&S11R will not
be erected for this purpose. Designer clearance towards this is already
obtained.
For erection of structure as mentioned above the basic sequence of erection
will be from front to rear i.e. from Row-D to L keeping the crane inside boiler
cavity. Entries of cranes are envisaged from right side of boiler through rear
of boiler i.e. from between boiler rear and mill bay col. i.e between Row-L&M.
For movement of crane inside boiler cavity it will be necessary to hold
erection of middle /air pre heater columns namely Columns Nos.
S15L&R , S16L&R, S17, S18, S19L&R, S20L&R, S21, S24R, S25R,
Page 120 of 175
S29R,FH-11R,FH-12R, Mill bay M & N row columns. Also it should be
ensured that the foundation pedestals of columns S15L&R, S16L&R,
S17, S18, S19L&R, S20L&R, S21, Mill bay M row cols 2nos at center
do not project above ground.
Columns nos. S15L&R, S16L&R and its connecting bracings will be erected
as soon as FMC moves out to clear the area after Ceiling girder A&B is
erected, but necessarily have to be erected before Ceiling girder –C erection.
Columns nos. S17 , S18 and its connecting bracings will be erected as
soon as FMC moves out to clear the area after Ceiling girder C & D is
erected , but necessarily have to be erected before Ceiling girder –E
erection.
Columns Nos S14L&R and its connecting bracings shall be erected
immediately after boiler drum is erected.
Erection of balance columns Nos. S19L&R , S20L&R , S21, S22L&R , S24L&R
, S25L&R , S26L&R , S27L&R , S28L&R , S29L&R and its connecting bracings
shall be erected independently after ceiling girder erection is completed and
FMC crane is moved out.
BOILER DRUM UNLOADING AND ERECTION:
In case of unit-3 the boiler drum will be received by rail near to boiler LHS
i.e. co-ordinate approx 2075N, 2250E. Boiler drum will be unloaded with the
help of two cranes namely LS248H 180MT and Manotowoc 250MT by the
boiler erection agency. The drum then shall be dragged onto temporary rails
to boiler cavity.
In case of unit-4 the boiler drum will be unloaded at the same location and
the drum shall be dragged on to temporary rails to unit-4.
Boiler drum will be lifted in single stage with help of two nos 15MT electric
winches and pulleys suspended from temporary structure (will be either
fabricated at site or will be diverted from other site) at top. Winches will be
placed in front of ESP and will be anchored with the help of concrete
counterweights of FMC crane placed in pit. After the drum is aligned the
lifting arrangement will be removed and pressure part erection will follow.
PRESSURE PART ERECTION AND HYDRAULIC TEST:
Being top suspended type of boiler, general sequence of erection of
pressure part will be from top to bottom and from outside to in side . Actual
sequence of erection will be decided at site depending on the sequence of
material receipt at site. However our aim shall be to go for maximum
possible pre assembly of pressure part components on ground or
optimization at works , so that to reduce numbers of lifts and to achieve
better quality which will effectively reduce erection cycle time.
Page 121 of 175
Following pre assemblies / optimization at works are envisaged:
a) All headers above roof will be assembled in single piece
b) All possible assemblies to handle able sizes in lines and links above
roof
c) All crown plates with end bars for coil suspension above roof
d) Furnace radiant roof – Front - in seven assemblies (each block of
suspension arrangement), Inlet header shall be lifted separately in
single piece and joining with tubes shall be done in position. Rear – in
two assemblies (each block with piece of out let header )
e) Back pass furnace roof with all hanger tubes above it along with inlet
header in single assy.
f) Back pass front wall hanger tubes with suspension end bars.
g) Back pass front wall upper with lower panels
h) Back pass side wall upper panels to inter panels
i) Back pass rear wall upper panels to inter panels
j) Back pass rear lower walls with two headers(complete assy)
k) Extended water wall upper panel with lower(individual)
l) Furnace rear wall upper panels with hanger tubes and arch tubes(
individual panel)
m) Burner panels with lower inter panels ( individual panels)
n) Furnace side Lower inter walls with lower walls ( individual panels)
o) Furnace front and rear lower panels with floor panels( individual
panels)
p) LTSH upper coils to lower coils. ( individual coils)
q) Economizer upper with intermediate coils( individual coils)
r) Sh. Divisional panels front assy to rear assy (individual panels)
s) Furnace bottom Z panels with floor panels and loose tubes
t) All buck stays with stirrups and key buck stays
u) Super heater and Re heater spray control stations
However a judicious re look into above assemblies will be essential after
detailed engineering of pressure part is completed.
Material feeding for first pass will mostly be done from RHS of boiler
between columns S8&9 on temporary rail. For back pass material shall be
fed from rear side. Also modern erection practices like use of omega lugs,
anti deformation frame for handling of Eco , Super heater and Re heater coils
, special lifting tackle for coil lifting will be inducted for safe and quicker
erection of pressure part.
Hydraulic test of boiler will be done in three parts. Drainable part includes
the circulation system and drainable portion of the super heater. During this
the link connecting the non drainable portion of super heater shall be
dummied. This will facilitate early clearance for insulation of water walls
and back pass walls required for light up. Non drainable part, which
includes the non drainable portion of the super heater system also, will be
done just prior to boiler light up so that preservation and rusting of super
Page 122 of 175
heater system can be avoided. Re heater hydraulic test shall be done along
with reheat system piping before steam blowing operation.
AIR AND FLUE GAS DUCTING ERECTION:
Air and flue gas ducting erection shall be taken up parallelly with boiler
pressure part so as to reduce the gap between boiler hydro test and light up.
Almost all duct (excepting duct like below back pass U-headers etc. ) shall be
pre assembled on ground and shall be kerosene tested to reduce ,number
of lifts and work in position which will in turn reduce erection cycle time.
The assembled duct will mostly be fed with help of crane from sides of
boilers. However the inter connecting hot secondary air duct will be
assembled below boiler, for straight lift.
AIR PRE HEATER ERECTION:
Air pre heater erection shall be taken up immediately after the structure is
getting ready after ceiling girders lifting. Most of components will be lifted
with crane (Monitowoc-250MT and FMC –350 MT one on either side)
depending on accessibility which will help in reducing erection cycle time.
FANS ERECTION:
This being independent parallel activity it will be taken up as early as possible
depending on availability of foundations. There is fixed sequence of erection
of fans as specified in erection manual, the same shall be followed strictly.
MILLS ERECTION :
Shall be taken up after availability of foundations. There is fixed sequence of
erection of mills as specified in erection manual, the same shall be followed
strictly. Major components like mill base, air compartment, separator body,
mill top / classifier assy, MDV assy will be placed with crane KH500. NTPC to
coordinate with mill bay structure erection agency regarding hold in
structural bracings etc. for crane approach.
ESP ERECTION:
This is altogether an independent island. ESP erection shall be started as
soon as column foundations and material is available. It has an almost fixed
sequence of erection. In ESP also we shall go for all possible pre assembly
like casing walls, hopper walls etc. Collecting electrode will be inserted from
bottom.
POWER CYCLE PIPING ERECTION:
This will be treated as a highly specialized work, especially in case of P-91
(High Crome alloy steel). The erection can start from any side terminal point,
however normal sequence shall be from boiler end to turbine building as the
boiler side terminal point will be ready earlier. Utmost care shall be taken by
highly experienced engineers / supervisors w.r.t. welding , preheat / post
heat treatment of welds , NDT , free floating of lines before connecting to
equipments.
Page 123 of 175
SPECIAL ERECTION PRACTICES:
Following special erection practices will be followed,
1. Permanent flooring of boiler cavity prior to BES: NTPC to
provide permanent flooring in boiler cavity (leaving the area for
foundations under hold), around boilers and below ESP before start of
erection. This will create a very convenient work atmosphere which will
help us in maintaining good house keeping also it will avoid
unnecessary re handling of material / temporary installations to
facilitate flooring at later stage.
It may be noted that the flooring should have load bearing capacity of
2.5 Kg/Cm2
2. Usage of passenger cum goods erection elevator: BHEL shall
provide one no. of passenger cum goods elevator in each boiler which
will be installed by our erection agency. This will transport people and
gas cylinders to higher location which will help in effective supervision
and higher productivity.
3. Usage of waste disposal chute: BHEL shall provide and erection
agency will install one no. waste disposal chute in each boiler running
vertically with branch in each floor.
4. Construction Power distribution system : BHEL shall ensure that
erection agencies follows a standard construction power distribution
system as explained below,
a) Agency for Main Boiler package:
They will lay individual construction power cable from main Sub Station
to DBs for individual welding generators booth at 5 locations as follows .
These DBs will be provided with ELCB’s and the cables will be run
underground before reaching boiler island and within the boiler island the
cable will be run on cable trays (vertical run will be along column no.
S12L&R)
o On ground floor between column box S11L-12L-6L-5L – will
have provision for 10 welding m/cs - 200 Amps – from SS- 9
for U-3 from SS – 10 for U-4
o On boiler floor at 18M elevation between column box S11R-12R-
6R-5R- will have provision for 10 welding m/cs – 200 amps –
from SS –8 for U-3 from SS – 13 for U-4
o On boiler floor at 31M elevation between column box S11R-12R-
6R-5R- will have provision for 10 welding m/cs – 200 amps –
from SS-9 for U-3 from SS – 10 for U-4
o On boiler floor at 62 M elevation between column box S9L-10L-
4L-3L- will have provision for 10 welding m/cs – 200amps –
from SS-8 for U-3 from SS – 13 for U-4
o In pre assy yard – for 10 m/cs –200 amps – from SS-6
Tentative quantity of Cable 240sq.mm, three core, Al. cable – 2000 M
and cable tray 8” – 500M, DB (200amps) – 5 per boiler will be
required.
All such DB’s will cater the need of power supply for Post Weld Heat
Treatment also.
Page 124 of 175
Above locations of DB and booth installation and routing of Power
cable for above are indicative, exact location shall be decided at site in
consultation with NTPC.
Other than welding booth they will provide a power distribution board
every after two floors with at least ten points, with standard industrial
socket arrangement for miscellaneous use of hand tools and hand lamps.
These boards will be connected with nearest DB of welding booth
b) Agency for ESP and ducting:
They shall lay construction power cable from main Sub station to DB
for welding booth as follows
At ground floor on LHS of ESP – 10 welding m/cs – 200 amps –
from SS-9 for U-3 from SS – 10 for U-4
At ground floor on RHS of ESP – 10 welding m/cs – 200 amps–
from SS-8 for U-3 from SS – 13 for U-4
DBs will be provided with ELCBs. The cables will be run underground
before reaching ESP island and within the ESP island the cable will be run
on cable trays.
Tentative quantity of Cable 240sq.mm,three core ,Al. cable – 600 M
and cable tray 8” – 150M No. of DB (200 amps )-2 per ESP will be
required.
Above locations of DB and booth installation and routing of Power
cable for above are indicative, exact location shall be decided at site in
consultation with NTPC.
Other than welding booth they shall provide a power distribution board
at least ten points one casing manhole door platform and one in pent
house of each pass, with standard industrial socket arrangement for
miscellaneous use of hand tools and hand lamps. These boards will be
connected with nearest DB of welding booth.
c) Piping erection agency: They shall lay construction power cable
from main Sub station (No. to DB for welding booth as follows:
At 4.5 M in B- C bay near column 48- 10 welding m/cs - 200
amps + 1 induction heating m/c – 200 amps from SS-7 for
both units.
On boiler floor At 31 M near col. S7L will have provision for 10
welding m/cs – 200 amps. Induction Heating m/c will later be
shifted from 62M along with power cable to 31M from SS-7 in U-
3 and from SS-11 in unit-4
On boiler floor at 62 M elevation between column box S9L-10L-
4L-3L- will have provision for 10 welding m/cs - 200 amps -
from SS-11 in both units + 1 induction heating m/cs – 200amps
from SS-7 in both units.
The cables will be run underground before reaching boiler island and
within the boiler island and in power house the cable will be run on cable
trays . Vertical run in boiler will along cable-S7L
Page 125 of 175
It may be noted that Sub Station (SS) -7 shall be provided with back
up DG set power supply to avert power failure to Induction Heating M/c.
Tentative quantity of Cable 200sq.mm three core al. cable – 2000 M
and cable tray 8” – 500M, DB (200apms) - 5 per boiler will be required.
Other than welding booth they shall provide a power distribution board
at least ten points at least in five suitable locations, with standard
industrial socket arrangement for miscellaneous use of hand tools and
hand lamps. These boards will be connected with nearest DB of welding
booth.
Above locations of DB and booth installation and routing of Power
cable for above are indicative, exact location shall be decided at site in
consultation with NTPC.
Location of substation and tentative routing of construction power
cables is shown in Annexure-8
.
5. Winch locations : selected number of winch will be positioned as
follows by our erection agencies,
Boiler Area:
a. 2 nos of 5MT winch on ground floor near S5L and near S5R
b. 1no of 3 MT winch on boiler floor at 50M near column S4R
c. 2 nos of 2MT winch on boiler floor at 75 M near column S4R and
S4L
ESP area:
No winch is envisaged for ESP erection
Piping area;
a) One 3MT winch on LHS near column no. S7L
b) One 3MT winch on LHS near column no. S7R
Operation of all these winches shall be controlled by Walkie Talkies
from remote. Locations of the winches are indicative. Actual location
can be decided at site.
6. Gas cutting sets: Our erection agencies shall use a set of one DA
cylinder and three oxygen cylinders mounted on trolley to be operated
on ground floor. Also for transportation of such gas cylinders they shall
use hand trolley.
7. Small Workshop: Our erection agencies shall install small workshop
containing drill m/c and bench grinder.
8. Erection Techniques: Following erection fixtures will be used for
pressure part erection. this will ensure safe and faster erection of
pressure part coils / panels,
a) Omega lugs: An attachment made of tubes and flat will
be welded to pressure part tubes will be used to hang
and align pressure part headers to panel, panels to
panels, panels to headers , hanger tube to coils , coils to
coils etc. BHEL Trichy shall supply the lugs along with a
load table. PSWR shall arrange for bolts. Location at
winch the lugs to be welded shall be decided by
engineers at site and shall be welded accordingly prior
to lifting of components. This will help in quick erection
of pressure part components and will facilitate easy
alignment.
b) Lifting Tool for pressure part Coils: This is a hinged
type clamp which develops grip due to self weight of the
component being lifted.. This will be fabricated at site
by our erection agency. This will be used to lift pressure
part vertical coils of super heaters and re heaters.
c) Anti deformation frame for coils: The anti
deformation frame will be fabricated ( considering
actual size of coil ) at site and used for handling longer
and heavy pressure part coils like Platen super heater ,
re heater front , super heater division panel , assembled
LTSH / ECO coils , to avoid permanent distortion while
lifting..
d) Floating Pulley system for LTSH and economizer
coil erection: An arrangement of a ropeway and a
floating pulley will be used for erection of LTSH and
Economizer coils. This will reduce erection cycle time to
great extent otherwise we would have lost lot of time in
changing lifting arrangement after every few coils.
e) Erection method of Super heater hanger tubes: a
very simple method of lifting SH Hanger tube will be
used which will facilitate faster erection.
f) Temporary Rail for material feeding: A temporary
rail line will be laid between boiler column no. S8-S9
through and through both boilers. Boiler pressure part
materials like water wall panels and SH/RH Coils will be
transported on to this rail with help of dip trolley. The
rail will be laid on sleepers at 1m spacing. For
transportation / dragging of boiler drum over the same
rail continuous sleepers will be laid for two lengths of
drum and rolled on. Requirement of material for this
purpose will be as follows,
Rail - 350 RMS
Sleeper – 400 nos. (200 for normal material feeding +
200 will be used for drum dragging)
Rail coupler / fish plate with fastener – suitable for 350
RMS rail
Rail fixing clips – suitable for 350 RMS rail
The portion of rail between two boilers will be made
removable type ( in panel form ), so that the same can
be temporarily removed to give access to other agency’s
T&P movement.
g) Temporary Urinal System : A header of 4”PVC pipe
shall be run on column S7R with urinal pan connected to
10 floors minimum on boiler and with suitable
underground pit arrangement.

Page 127 of 175
MATERIAL FEEDING AND CRANE PARKING DURING BOILER
ERECTION (major portion):
i) For main boiler supporting structure erection up to drum lifting
:
Crane movement / Parking: within boiler cavity.
Crane: FMC LS 248H 180MT from 1st to 3rd month, FMC LS 718 with
ringer and 330’ boom and jib thereafter.
Tentative Duration: from 1st to 5th month from BES of each unit.
Material feeding:
Unit-3-
From Storage yard / pre assembly area by road though Unit-4
(either between mill bay-M row and boiler rear or between mill bay N row
and ESP)
Unit-4 –
From Storage yard / pre assembly area on road
ii) Pressure part erection:
Crane: All erection will be done with help of winches. For unloading of
material 75 MT crane will be located on RHS of each boiler.
Tentative Duration: from 6th to 18th month from BES of each unit
Material feeding:
Unit-3-
From Storage yard / pre assembly area by road though Unit-4 (either
between mill bay-M row and boiler rear) then on rail to boiler cavity in
case of first pass and through boiler rear in case of second pass. After
drum lifting of unit- 4 is over the materials can be fed on temporary rail
through boiler-4
Unit-4 –
From Storage yard / pre assembly area on road then on rail to boiler
cavity in case of first pass and through boiler rear in case of second pass.
iii) For balance component like roof structure, silencer, duct, air
pre heaters, fans (FD and PA) erection:
Unit-3 LHS –
Crane: Manitowoc –250MT (6th to 10th month ) , LS 248H (10th to 18th
month)
Tentative Duration: from 6th to 18th month from BES of unit-3
Material feeding:
From Storage yard/ pre assembly area by road though Unit-4 (between
mill bay-M row and boiler rear or between mill bay N row and ESP)
Unit-3 RHS –
Crane: FMC LS718 –350MT ( 6th to 12th month ) , Manitowoc –250MT (
12 th to 18th month )
Tentative Duration: from 6th to 18th month from BES of unit-3
Page 128 of 175
Material feeding:
From Storage yard/ pre assembly area by road though Unit-4
(between mill bay-M row and boiler rear or between mill bay N row and
ESP)
Unit-4 LHS –
Crane: Manitowoc –250MT (6th to 18th month from BES of Unit-4)
Material feeding:
From Storage yard/ pre assembly area on road though Unit-4
(between mill bay-M row and boiler rear or between mill bay N row and
ESP)
Unit-4 RHS –
Crane: FMC LS 718 – 350 MT (6th to 18th month BES of Unit-4)
Material feeding:
From Storage yard/ pre assembly area by road.
iv)Mill erection:
Unit-3
Crane: KH-500
Tentative Duration: 14th to 20th month from BES of unit-3
Material feeding:
From Storage yard / pre assembly area on road though Unit-4 (
between mill bay-M row and boiler rear or between mill bay N row and
ESP)
unit-4
Crane : KH-500
Tentative Duration: 14th to 20th month from BES of unit-4
Material feeding :
From Storage yard / pre assembly area on road
v) ESP erection:
Crane movement / Parking: all around ESP island
Crane: 75MT , KH500
Tentative Duration: 1st to 18th month from ESP erection start of each
unit
Material feeding :
Unit-3 –
From Storage yard/ pre assembly area on road though Unit-4
(between mill bay N row and ESP & between ESP and ID fan)
Unit-4
From Storage yard/ pre assembly area on road
HOLDS ON CIVIL FOUNDATIONS / OTHER CONSTRUCTION :
a) Civil Foundations: S15L&R, S16L&R, S17, S18, S19L&R, S20L&R,
S21, Mill bay M row columns 2nos at center and FD fan –B (RHS) in
each boiler
This is required for erection crane movement / parking inside boiler
cavity and for ceiling girder pre assembly as explained in erection
sequence.
Page 129 of 175
Hold lift – Hold shall be lifted as soon as crane is moved out after
ceiling girders erection i.e. 5th month from boiler erection start.
Agency to act: NTPC
b) Other Construction:
i) Mill bay ‘M’ & ‘N’ – row structure in each unit
This will be required for FMC entry / exit and parking during boiler
structure erection in each unit.
Hold Lift: Hold shall be lifted as soon as crane is moved out
after ceiling girders erection i.e. around 5th month from boiler
erection start.
Agency to act : NTPC
ii) Inter Connecting Duct / platform between boiler and mill
bay in each unit :
This is required for moving out erection crane parked on LHS of
boiler for erection of roof structure / fans / APH
Hold Lift: the hold is planned to be lifted in 12 th to 14 th
month from BES.
Agency to act: BHEL
iii) Duct support structure between mill bay and ESP in each
unit:
This will be required to facilitate crane movement for Mill
heavier components and ESP erection.
Hold lift: the hold is planned to be lifted progressively from 18th
month from BES
Agency to act: BHEL
iv) Duct support structure between ESP and ID fan:
This is required to facilitate crane movement for ESP erection
and ID fan heavier component erection.
Hold Lift: Hold is planned to be lifted progressively from 14th
month from Boiler erection start.
Agency to act: BHEL
v) Mill bay N row bracings :
This will be required to facilitate crane approach for erecting mill
heavier components. The particular bracing items need to be
hold will be decided at site in consultation with NTPC.
Hold Lift: hold is planned to be lifted progressively from 14th
month of BES
Agency to act : NTPC
ADDITIONAL INPUTS (Not Envisaged Originally ) TO BE TIED UP :
By NTPC :
a) Hold on foundations / structure as mentioned above
b) Finished flooring in / around boiler island and below ESP
c) Finished flooring / consolidated area for laying temporary rail
By BHEL :
a) Temporary rail / sleepers etc.
b) Bolt for omega lugs
c) Temporary structure for drum lifting
d) DESH Link temporary Dummy plates for non drainable HT
e) DG set 500KVA for Induction Heating m/c
By erection agencies:
a) Construction Power Distribution board
b) Construction power cables
c) Cable trays for above
d) Portable Cutting Gas cylinder skid
e) Cutting gas cylinder transportation trolley
f) Small workshop
g) Walkie talkies for winch control
h) Urinal arrangement on boiler
TENTATIVE ERECTION PLAN : With all above we shall complete
erection of boiler package as per the plan enclosed .
ERECTION STRATEGY IS A BASIC DOCUMENT TO BE FOLLOWED
HOWEVER FOLLOWING CHANGES ARE MADE BASED ON
ERECTION FEEDBACKS AND SITE CONDITIONS:
1. Proposed temporary rail track between boiler columns no. S8-S9
through and through both boilers and up to pre assembly yard
(refer annexure 6) was restricted to cover the boiler cavity of
each boiler between column S8 & S9, since inter connection
between two boilers and boiler 4 to pre assembly yard was
obstructing the erection work of civil agencies.
2. For unloading of boiler drum for unit#3, 2 nos 75MT and 1 no
150MT (KH700) cranes were used instead of 1 no 150MT
(LS248) and 250MT ( Manitovoc) cranes.

Case study-Rihand 3-Major problems

HOT AIR SHUT OFF GATE:
MECHANICAL:
1. In one of hot air gate, Blade was having bow at middle and the
blade is seating over the retainer plate of bonnet side in open
condition towards up stream side.
2. Misalignment between of power cylinder & gate, which promote
sticking with sides.
3. The blade protection cover prohibits inspection of the piston gate
connection and limit switch lever adjustment. Some times the
removal of cover is very expensive & tedious job as about 150
nos of nut & bolts connection are to be handled. It is to be
reviewed for elimination of the cover and if the cover is
necessary, provision of inspection opening cover with swing
arrangement shall be thought off.
Page 64 of 175
4. The side transition box connection for seal air to the seal
chamber done at works invariably leaks and after connecting the
seal air pipe, attending the leak difficult requires extensive re
work and only temporary measures like application of M-SEAL is
solution, which is not acceptable and becomes permanent
pending point.
5. The bore of gaskets used for fixing the flanged butterfly valve in
all the assembly was found less and hence prevent valve
opening. Site has to remove the valve assembly and correct
which consumes time and effort.
6. The out side seal box cover fixing with the seal box frame, the
bolting system at present, makes removal of bolts difficult as the
whole bolt rotates as the head tack welding with frame gives
way and rotates.
POWER CYLINDER OF HOT AIR GATES:
1. The rubber seals of power cylinders in 7 out of 10 in unit#3 and
3 out 10 in unit#4 were to be replaced after erection due to
piston seal passing. The piston seal should be good viton quality
having high temp withstand characteristics and reliable lip
reversal. To open the power cylinder weighing more than 250 kg
at 45 mtr elevation, specially where no platform / beam is
available above power cylinder, and bring down at ground level
is a very risky & tedious job. We have to call the supplier’s
technicians for the replacement of seals.
2. The requirement of lubricator shall be eliminated.
3. The Air filter regulator shall be of metallic than plastic which is
prone for damage.
ELECTRICAL
1. The junction boxes location is the top of the frame and hence
approach is difficult for any checking and maintenance. The
location of JB was changed at site.
2. The limit switches assembly is provided in the up stream side of
the gate makes it difficult for attending any defect due to heat
while boiler is in service. At site, modification was carried out to
suit the O&M requirements.
PNEUMATIC CONNECTIONS
1. The copper tubing is prone for theft and it is to be reviewed for
switch over to flexible hoses/ SS tubing with hoses at ends.
2. The requirement of lubricator shall be eliminated with usage of
seals which operate on dry air.
3. The Air filter regulator body shall be of metallic and not plastic
one as presently supplied which is prone for damage and it
happens during erection and no spares are supplied. We have to
procure 5 nos from the party.
CONTROLLED CIRCULATION PUMP (CC PUMP):
M/s KSB Germany make.
In one of three CC pumps installed in Boiler#4, 4 nos studs were
struck up in the casing at the time of removing the dummy after the
hydro test of boiler. These were removed forcibly by heating and
hammering causing the damages of all the four studs/ nuts and thread
damage of the casing.
The new studs (4 nos), nuts (7 nos) & jointing ring (1 no) were
procured from M/s KSB Germany and the threads of the casing were
rectified at site with the help of M75X2 tap sets.
This last pump was commissioned without the help of vendor’s
representative.
It is recommended to follow strictly the Erection and O&M manual
while heat tightening the studs with the casing, using lubricants &
torque wrench supplied with equipments.
FEED WATER SYSTEM – INPUT SHAFT OF GEAR BOX
TDBFP-3B commissioned on 05.06.2005 was in continuous in operation
for the last 5 months. On 23.11.2005, it was noticed that the drive
turbine rear bearing vibration increased from 22 micron to 40 micron.
The gear box vibration (located between drive turbine & booster
pump) also increased alarmingly.
The gear box was decoupled from drive turbine to check the
alignment between turbine & gear box. During this process, it was
noticed that input drive shaft of the gear box is damaged ie shaft
material is chipped off in triangular shape along the length of the input
shaft for a length of 40mm near the coupling hub & keys are
dislocated from their position.
The gear box was removed from its position. The defective input shaft
got sheared off while removing it from gear box by puller. The input
shaft already got cracked along the cross section of the shaft.
Page 78 of 175
It was suspected that the parent material of the input shaft was
defective.
The supplier’s representative was called to supervise the assembly of
the new shaft & investigation of the failure. The machine was made
ready in the second week of January 2006.
BOILER HOISTS – CABLE TROLLEYS:
The cable trolleys units associated with mill handling system DSL are
breaking down quite frequently which were supplied by M/s Consolidated
Hoists. The fabrication of these trolleys is under sized, perhaps suitable for
short length tracks where cable pulling load is less.
The observations on these cable trolley problems as below:
a) The two side cover plate thickness is about 2.5mm,
b) The two long distance screw size is about dia 6mm.
c) Welding of stud bolt with the power cable holding clamp is inadequate.
The total distance of the mill service crane DSL track beam is about 110 m
(Rihand is having rear mill combination) and the entire cable-pulling load
acts on the nearest trolley to the service crane. Due to less thickness, the
cover plates of trolley as well as the distance screws easily get bent, the
alignment of the trolley thus get disturbed, open up and disengage from the
track beam.
As the first one fails, subsequently the supply cable-pulling load comes on
the next trolley and one by one they fall down along with the power cable.
Since proper reinforcement is not provided on the cable clamp with the stud,
the joint fails and the power cable along with cable clamps get detached from
the trolley.
The commissioning of whole mill handling system could not be done and
during initial trials itself a lot of break downs occurred with the DSL trolleys.
For ESP transformers handling system (PGMA 78-773), much heavier trolleys
were supplied by M/s Power build hoist maker. This is made of channel with
5mm thick plates. Here the track length is almost half (50m long) and that
too for pulling much lesser cable size compared to Mill service crane DSL
cable.
The similar problem may be faced in ECO coil handling system also, long
track with same trolleys. At a high elevation (+72m level), repair & frequent
maintenance of trolleys in the mid air is very difficult and simply
unimaginable. The DSL lengths of ID Fan, APH elements handling system are
also more and these are also not at lower elevations for easy maintenance.
The matter has been referred to Trichy engineering for review of design with
the supplier M/s Consolidated Hoists and replacement of all such trolleys and
track beams with improved design. The trolleys for ESP & TG side are more
rigid & steady, supplied by M/s Herculous & M/s Power Build.
The photos of trolleys (both assembly and in knocked down condition) of mill,
ESP handling system and other typical system as below:

Case Study- Rihand-2CONTINGENCY ARRANGEMENT

CONTINGENCY ARRANGEMENT DURING COMMISSIONING
INITIAL DM WATER & AIR REQUIREMENT
Temporary line of 200 Nb pipe with valves about 200 meters was laid
from stage I at a location in between unit 2&3 for HYDRO TEST of
boiler#3 initially and kept in use till the completion of both units acid
cleaning.
COMPRESSOR:
The compressor cooling water requirement for initial trial run of the
compressor was met by temporary open cooling water with the use of
DM water teed off from the line laid for boiler hydro test purpose. This
arrangement was retained till regular ECW system was made ready.
MAIN CONTROL ROOM AC PLANT:
AC plant make up water was not ready due to the pipe trestle erection
problem, as the same could not be erected by virtue of lay out and
pending building completion clearance.
The cooling water and chilled water initial filling and make up
requirement was met by laying a 3 inch line from the unit-2 fire
hydrant system and the same was maintained for a long time as the
trestle erection clearance was given very late.
FIRE FIGHTING SYSTEM:
The stand-alone fire fighting system for stage two was not ready
during the initial commissioning of start up transformer and unit
auxiliary transformers.
From the existing stage – I, a tapping was taken and laid temporary 4
inch line and connected to the transformer emulsi fire system line and
subsequently connected to stage II mains.
NEUTRALIZATION OF ACID:
The neutralization of spent acid was piped to the stage I , DM effluent
tank ( about 1.5 km away ) for treatment with NaOH & final discharge
to the regular drainage after ensuring the discharge water is fit for use
so that water contamination is minimized. Based on unit#3
experience, NaOH was procured in tankers & unloaded in Stage-I DM
plant tanks to send NaOH through pipe lines connected to effluent
tank, unlike unloading by the drum. The spilled acid on the floor /
equipment is neutralized with lime and washed with water.
Page 15 of 175
BENCH MARKS AT RIHAND SITE
THE DRUM LIFTING OF UNIT#3 ACHIEVED ON 29.03.2003 i.e.
WITHIN 9 MONTHS AND 26 DAYS OF THE CONFIRMATION OF ORDER,
WHICH IS SHORTEST TIME TAKEN SO FAR FROM THE DATE OF
CONFIRMATION OF ORDER TO DRUM LIFTING.
THE DRUM LIFTING OF UNIT#4 ACHIEVED ON 11.07.2003 WITHIN 3
MONTHS & 13 DAYS AFTER FIRST DRUM LIFTING, 94 DAYS IN
ADVANCE w.r.t. L2 SCHEDULE.
SITE HAS ACHIEVED MORE THAN 3000MT PHYSICAL ERECTION IN
BOILER PACKAGE 2X500MW CONSECUTIVELY FOR THREE MONTHS.
(NOV’03 – 3714MT, DEC’03 – 3412MT & JAN’04 – 3174MT).
HIGHEST TONNAGE IN 500MW BOILER IN A SINGLE MONTH –2071
MT (NOV’03)
HIGHEST HP JOINTS (EQ.) IN 500MW BOILER IN A SINGLE MONTH –
6310 NOS (NOV’03).
HIGHEST TONNAGE IN 2X500MW BOILER IN A SINGLE MONTH –
3714MT (NOV’03)
HIGHEST TONNAGE IN ESP#4 500MW IN A SINGLE MONTH – 874MT
(DEC 03).
THE ENTIRE CONDENSER TUBE INSERTION (24398 NOS)
COMPLETED IN A RECORD TIME OF 26 DAYS AND ALSO HIGHEST
3350 NOS TUBE INSERTION IN A SINGLE DAY ACHIEVED ON
27.12.2003.
BOILER # 3 & 4 HYDRAULIC TEST OF DRAINABLE PORTION
COMPLETED ON 30.01.2004 AND 19.06.2004 –
•IN A FIRST FILL ITSELF i.e.IN A SINGLE FILL OF BOILER.
•PRESSURE DROP OF MERE 2 KG/CM2 FOR A PERIOD OF HALF AN
HOUR (AGAINST PERMITTED NORMS OF 15 KG/CM2 ) AT THE FULL
TEST PRESSURE OF 310.50 KG/CM2
•TEST SUCCESSFULLY COMPLETED IN LESS THAN 24 HRS.
BEST SAFETY AWARD FOR BHEL SITE BY NTPC FOR THE YEAR
2003-04.
BOTH 500MW UNITS GENERATED AT A PLF MORE THAN 90%
DURING THE FIRST YEAR OF OPERATION. THE UNITS WERE
STABILISED IN A MINIMUM TIME.

Case study-Rihand-1

EQUIPMENTS/ SYSTEMS – INSTALLED FOR RIHAND - STAGE-II.

STEAM GENERATORS :
Two combustion engineering design BHEL steam generators are of
controlled circulation single reheat, balanced draft with fusion welded
war wall panel units having a primary steam flow 1675 tonnes/hour,
Super heater out let pressure is 179 kg/ sq-cm at a temp. of 540°C
with an inlet feed water temp of 254°C .
The reheat steam flow of 1394 TPH will be raised to an outlet temp. of
540 from inlet condition of 45.8 Kg/sqcm and 336°C .
The furnace is having overall dimension width 19.177 meter and depth
15.797 meter and height 62 meter effective and the furnace walls are
fusion welded panel are large in size to minimize erection weld at site.
Each unit is having one steam drum and connected to that down take
system are suspended. There are six down takes evenly spaced along
the drum length connected to suction manifold & 3 submerged motor
boiler water circulation pumps with two outlet each forms the
circulation system.
Super Heater, Reheater and Economizer :
The super heater consist furnace roof tubes to the rear of the unit
where it cools walls of rear pass. The steam from here enters into 3
loop pendent low temp. super-heater located above economizer., with
spray facility at the out let before entering divisional panel and finally
to super heater.
The Re-heater is one stage: located in between divisional panel and
super heater exit panel.
Furnace wall is having 88-wall blower and 32 Nos. of long retract for
plates, re-heater & convective super heater heating surfaces.
TURBO-GENERATOR:
Two turbo generators of BHEL HARIDWAR Make (KWU Design) is
tandem compounds 3 cylinder machine with single flow HPT & double
Page 7 of 175
flow IPT & LPT with 6 extractions inclusive of feed water heating and
steam to feed pump drive turbine.
Each generator is water-cooled stator & hydrogen cooled rotor rated
588 KWA at 21KV with 0.85 power factor with short circuit ratio of 0.5.
Generator is having alkaliser, end winding vibration monitor, partial
discharge monitoring etc.
Excitation is direct shaft driven.
FUEL - COAL, HFO & LDO:
The primary fuel is Bitumen coal from SLC (LT) Amlori mines of NCL.
Transportation of coal is through MGR system constructed for stage-I,
with provision of doubling of track.
The coal handling plant (CHP) for stage-II is constructed by BHEL ISG
Bangalore. With a separate railway siding to track hopper (RCC)
receives coal from hopper & convey to crusher House with transfer
points (six) through conveyor reaches the silo/bunker of mills with by
pass facility for diverting the crushed coal excess of the requirement to
coal storage area. The capacity of plant is 2200 TPH with 100% stand
by, with 16 hours spread operation.
Stacked/re-claimer facility is also provided for feeding coal from coal
yard to conveying the coal to steam generator.
HFO fuel oil storage is common for with stage-I & II constructed during
stage-I. The pump house for forwarding is separate for stage –2 and
common for both 3&4 units. BHEL (Agency – M/s Techno Fab Pvt Ltd)
has constructed the LDO unloading facility for stage-II, required for
the start-up of the boiler.
ELECTRICAL SYSTEM:
The electrical transmission from the plant is by 400 KV from
Transformer (21 KV from Gen side). Each unit is having three single
phase Transformers with an individual rating of 214MVA, 21/400 KV,
cooled with off load tap changer.
AUXILIARY ELECTRICAL SYSTEMS:
The Aux. Electrical system for each unit is served with connected Unit
Transformer of 21KV/11KV - 45MVA with 2 nos Unit Auxiliary
Transformer 11KV/3.3KV – 16MVA. In addition to this, one no station
transformer & station auxiliary transformer (start up) for each unit,
having rating 80/40/40MVA-132/11/11KV & 16MVA – 11/3.3KV, are
installed with interconnection facility. One no colony service
Page 8 of 175
transformer of rating 12.5MVA – 132/11KV is installed in 132KV switch
yard. All these transformer are supplied by BHEL – Bhopal/ Jhansi.
The LT supply arrangements are as under:
Dry type service transformer 2000KVA-3.3KV/433V – 2 nos per
unit.
Dry type station service transformer 2000KVA-3.3KV/433V – 2
nos per unit.
Oil filled fire water pump house service transformer 2000KVA –
3.3KV/433V – 2 nos.
Oil filled fire water pump house service transformer 2000KVA –
3.3KV/433V – 2 nos.
Oil filled off site service transformer 2000KVA – 3.3KV/433V – 2
nos.
Oil filled ESP service transformer 1600KVA- 3.3KV/433V – 8 nos
per unit.
The MD-BFP, ID, CW, PA, FD and CEP motors, rated above 1500KW
are fed by 11KV. The mills, ECW, ACW, compressor & make-up/ raw
water motors rated above 200 KW to 1500KW are fed by 3.3KV & up
to 200 KW by 415V systems.
The each unit emergency is fed by 1200 KW DG set with one spare
common DG set.
D.C System: (Supplied by M/s HBL Nife through BHEL) 220V – 2 Nos.
with float a boost charger to supply DC emergency pumps, scanner air
fan & some selected service for 30 minutes duration.
PLANT AUXILIARY SYSTEMS:
The regenerative feed water heating system design is conventional
one. Six stages of feed water heating comprises of 3 LP heaters,
Dearator, and two high pressure heater. The LP heater & HP
heaters is tubed with SS tube material of SA688 TP 304 specification.
3x50 percent capacity condensate extraction pumps are driven by 11
KV motor. One 50% Boiler Feed pump is motor driven for start up
purpose & other 2 x 50 % Boiler capacity are turbine driven feed
pump. The feed pump turbine exhaust is connected to main turbine
condenser.
Page 9 of 175
ASH HANDLING SYSTEM : (Supplied by M/s Burn & Standard)
Boiler bottom Ash extracted in wet form & disposed off in wet form.
The fly ash is extracted in dry form from ESP to be taken to hopper for
onward transportation to ash silo in dry form or slurred in wetting
units for ultimate disposed in wet form to ash disposal area (ASH
DYKE).
The bottom ash & fly ash slurry are led into common slurry sump for
further disposal to ash disposal areas through pumps & piping work.
WATER SUPPLY & COOLING WATER SYSTEM:
Water supply for the plant is from the Rihand reservoirs and make up
water is drawn from two locations - from stage-I CW pumping system
water for DM water requirement and potable water system & make up
water requirement for CW system is drawn from stage-I CW discharge
channel, which also serves other miscellaneous requirements of ash
handling/AC & ventilation etc.
M/s PAHARPUR supplied Re-circulating & Forced draft type cooling
towers are installed for stage – II, unlike open channel for stage-I.
3x50% capacity clarified water pumps using discharge water drawn
from clarified water storage tank, through bar screen & trash rack.
The total water requirement is 60,000 m³/hour. Five numbers of half
capacity (two for each with a common standby) concrete volute
vertical pit turbine type (30400 m³/hour) pumps of M/s KBL make with
BHEL Bhopal make vertical motors are installed in CW pump house.
Single M.S. pipe of 3600mm diameter pipe carries the water from the
fore bay to plant & back to the fore bay through cooling towers.
Aux. Cooling:
For the auxiliary cooling water system, the water is drawn from CW
inlet pipe before condenser & 3x50% capacity pump will take suction
and discharge to the CW outlet at the CW out let pipe near condenser
through 2x100% capacity & 3x50% capacity plate heat exchangers of
boiler side cooling water & turbine side cooling water cooler
respectively, removing the heat of closed water DM cooling water
system of boiler common auxiliaries & turbine, generator auxiliaries.
The vacuum pump coolers are directly cooled by CW water.
The equipment cooling water is DM water closed with NaOH, is
separate overhead tank and pumping arrangement with piping to
different coolers & back to pump suction.
Page 10 of 175
2x100% capacity pumps are used for boiler side + compressor &
3x50% capacity pumps serves turbine side equipment cooling
requirement.
COMPRESSED AIR SYSTEM: (Supplied by M/s Atlas Copco through
BHEL)
The compressor air system is common for both the plants. 5
numbers of rotary screw type compressors - 3 for service air and 2 for
instrument air serves the plant requirement with a provision for
connection to stage-I.
The plant and instrument air piping at the out let of the compressor is
having facility for interconnection and the regenerative drier 2 nos is
provided with all peripherals like tank etc.
FIRE PROTECTION SYSTEM : (Supplied by M/s Wormald through
BHEL)
A comprehensive fire detection system like (infrared quratzoid bulb,
linear heat sensing cable, photoelectric type heat sensors and
protection system like high, medium velocity water spray, Hydrant
water monitor, foam system inergene system, fire extinguisher to be
actuated through sensors/manual actuation facility protects against
fire. Other associated system like pumps, tanks, booster form part of
the fire protection system.
AIR CONDITIONING & VENTILATION SYSTEM:
(Supplied by M/s ABB through BHEL)
The system comprises of central chilled water type of 2x50 vapor
absorption machine (both working) and 2x50% screw chiller normal
standby mode for main plant control room, UPS & SWAS room, ESP-
VFD control room of unit 3 &4 air-conditioning requirement. The
subsystems associated with this are cooling water system including
cooling towers & make up water system, chilled water system with
make up provision form expansion tank, air handling units at 11
different locations with fans and air flow control devise. All the controls
and operation are PLC based with hook up with main control room PLC.
Service building air conditioning requirement is met with two screw
chillers with all the peripherals as enumerated for the main plant.
BALANCE OF PLANT - Split air condition units of different capacity
serve balance of plant control room air conditioning requirement.
Page 11 of 175
THE VENTILATION SYSTEM is separate for each unit. The B-C bay
ventilation unit located at 24 meter elevation & A row at 8.5 meter
elevation serves the TG hall, MCC, switch gear room, etc. Other offside
plant and other buildings, which are not connected with main
ventilation system, are provided with ventilation fans of adequate
numbers.
AUXILIARY HEATING:
From the stage-I, steam is drawn for supply of steam for unit start up,
for serves like fuel oil heating/steam tracing, steam coil air pre heater,
vapour absorption machine, flue gas conditioning skid etc.
WATER CONDITION & QUALITY CONTROL:
The conditioning of cycle make up water is common for both units. All
other water treatment, conditioning & monitoring is separate for each
unit.
The DM plant of 100 m³/hour is of six-bed concept, supplied by M/s
Ion Exchange.
The steam generator-turbine-condenser cycle is controlled in a fashion
normal for a drum type of boiler. These include volatile chemicals for
feed water corrosion reduction such as ammonia & hydrazine and
utilize the coordinated phosphate method of control for boiler water.
The condensate polishing re-generation (CPU) is common for
both units supplied by M/s DRIPLEX through BHEL. A powdered-resin
condensate polishing system capable of handling full load condensate
with its two filters polished with by pass facility.
CW basin is provided with shock chlorination for algae control.
The equipment cooling water system will be closed with sodium
hydroxide.
A centralized water quality monitoring system receive sample from
through out the plant as well as grab sample analysis facility ensures
the plant water regime.
Page 12 of 175
CONTROL & PLANT MONITORING:
Microprocessor controller EDN MAX DNA boiler turbine controls &
protection is DDCMIS. The coordinated system is providing control
unit generation on a feed forward basis. The controls provide for
automatic operation either the constant pressure or sliding pressure
mode. Also included in the system is automatic control of super
heater by passing the steam in HP/LP by-pass system for matching the
steam temperature with the turbine metal temperature during hot
start and initial start up etc.
The system is very extensive and includes:
Generation of operating information
Generation of historical records
Control of electrical system
Large video screens
Man machine interface
Alarm system & analysis
Digital display analogue trends & dynamic graphics
Vibration monitoring system.
All the balance of plant controls are PLC based supplied by GE-FANUC
with a battery back up of HBL-Nife.
PUBLIC ADDRESS SYSTEM: (Supplied by M/s Bytes Communication
through BHEL)
A distributed amplifier based public address system is provided for
communication within the plant through hand set stations distributed
throughout the plant to ensure proper communication.
ENVIRONMENTAL ASPECTS:
Water Pollution: Since the CW system is re-circulation type there is
no significant thermal pollution.
The CW blow down water used for coal dust suppression & extraction
system & service water system is of re-circulation type.
Ash water re-circulation system is provided with adequate treatment
facilities.
Oil water separator is provided to separate the oil and the water from
the bottom would be recycled.
All the effluent (from DM plant, CPU regeneration plant, plant
drainage, oil water separator is treated at Effluent treatment plant
(supplied by M/s DRIPLEX through BHEL) before discharging to Rihand
reservoir.
Oil & Chemicals: The fuel oil, lubricant and chemicals are controlled
by containment. Chemicals like Hydrochloric acid, sodium hydroxide,
sulphur is stored in vessels with lined concrete containment.
Air Pollution:
1. In an effort, to minimize the environment impact of NTPC Rihand
stage-II, High efficiency ESP is provided with Flue gas
conditioning system (Installed first time in INDIA by M/s
Bahmann India Ltd under technical collaboration with M/s
Wahlco USA through BHEL) with Sulphur tri oxide injection to
reduce the resistibility of ash & increase collection at the plate
and SOX reduction.
2. Chimney height is 275 meter will disperse hot flue gas to
atmosphere with stack emission monitor.
Solid water waste management :
Fly ash & bottom ash - It is disposed in a separate ash dyke
(Constructed by M/s HSCL) impoundments to be reclaimed through
tree plantation after abandonment. Also fly ash collected as dry is used
for making bricks & filling of earth in the plant, township and nearby
areas.
The mill rejects from each pulverizer is sluiced individually to the
bunker (pneumatic transportation) and periodically collected and
hauled to the allotted location. The Mill Reject System is installed by
M/s Macabber Bekay through BHEL.
NOX Control:
The tangential fuel firing system, which promote large amount of
essentially horizontal re-circulation of gases in the furnace, this
completed with slow mixing of fuel air, provides for combustion, that is
inherently low in NOX reduction. The over fire air design and two
stage air admission reduce the NOX production.

Control engg

1. Chapter 1 THE EXCITEMENT OF CONTROL ENGINEERING
1.1 Preview
2. This chapter is intended to provide motivation for studying control engineering.
3. In particular it covers: • an overview of the scope of control • historical periods in the development of control theory • types of control problems • introduction to system integration • economic benefits analysis 1.2 Motivation for Control Engineering Feedback control has a long history which began with the early desire of humans to harness the materials and forces of nature to their advantage.
4. Early examples of control devices include clock regulating systems and mechanisms for keeping wind-mills pointed into the wind.
5. A key step forward in the development of control occurred during the industrial revolution.
6. At that time, machines were developed which greatly enhanced the capacity to turn raw materials into products of benefit to society.
7. However, the associated machines, specifically steam engines, involved large amounts of power and it was soon realized that this power needed to be controlled in an organized fashion if the systems were to operate safely and efficiently.
8. A major development at this time was Watt’s fly ball governor.
9. This device regulated the speed of a steam engine by throttling the flow of steam, see Figure 1.1.
10. These devices remain in service to this day.
11. 5 6 The Excitement of Control Engineering Chapter 1 Figure 1.1.
12. Watt’s fly ball governor The World Wars also lead to many developments in control engineering.
13. Some of these were associated with guidance systems whilst others were connected with the enhanced manufacturing requirements necessitated by the war effort.
14. The push into space in the 1960’s and 70’s also depended on control developments.
15. These developments then flowed back into consumer goods, as well as commercial, environmental and medical applications.
16. These applications of advanced control have continued at a rapid pace.
17. To quote just one example from the author’s direct experience, centre line thickness control in rolling mills has been a major success story for the application of advanced control ideas.
18. Indeed, the accuracy of centre line thickness control has improved by two orders of magnitude over the past 50 years due, in part, to enhanced control.
19. For many companies these developments were not only central to increased profitability but also to remaining in business.
20. By the end of the twentieth century, control has become a ubiquitous (but largely unseen) element of modern society.
21. Virtually every system we come in contact with is underpinned by sophisticated control systems.
22. Examples range from simple household products (temperature regulation in air-conditioners, thermostats in hot water heaters etc.) to more sophisticated systems such as the family car (which has hundreds of control loops) to large scale systems (such as chemical plants, aircraft, and manufacturing processes).
23. For example, Figure 1.2 on page 8 shows the process schematic of a Kellogg ammonia plant.
24. There are about 400 of these plants around the world.
25. An integrated chemical plant, of the type shown in Figure 1.2 will typically have many hundreds of control loops.
26. Indeed, for simplicity, we have not shown many of the utilities in Figure 1.2, yet these also have substantial numbers of control loops associated with them.
27. Many of these industrial controllers involve cutting edge technologies.
28. For example, in the case of rolling mills (illustrated in Figure 1.
29. 3 on page 13), the control system involves forces of the order of 2,000 tonnes, speeds up to 120 km/hour and tolerances (in the aluminum industry) of 5 micrometers or 1/500th of the thickness of a human hair! All of this is achieved with precision hardware, advanced computational tools and sophisticated control algorithms.
30. Beyond these industrial examples, feedback regulatory mechanisms are central to the operation of biological systems, communication networks, national economies, and even human interactions.
31. Indeed if one thinks carefully, control in one form or another, can be found in every aspect of life.
32. In this context, control engineering is concerned with designing, implementing and maintaining these systems.
33. As we shall see later, this is one of the most challenging and interesting areas of modern engineering.
34. Indeed, to carry out control successfully one needs to combine many disciplines including modeling (to capture the underlying physics and chemistry of the process), sensor technology (to measure the status of the system), actuators (to apply corrective action to the system), communications (to transmit data), computing (to perform the complex task of changing measured data into appropriate actuator actions), and interfacing (to allow the multitude of different components in a control system to talk to each other in a seemless fashion).
35. Thus control engineering is an exciting multidisciplinary subject with an enormously large range of practical applications.
36. Moreover, interest in control is unlikely to diminish in the foreseeable future.
37. On the contrary, it is likely to become ever more important due to the increasing globalization of markets and environmental concerns.
1.2.1 Market GlobalizationI ssues
1. Market globalization is increasingly occurring and this means that, to stay in business, manufacturing industries are necessarily placing increasing emphasis on issues of quality and efficiency.
2. Indeed, in today’s society, few if any companies can afford to be second best.
3. In turn, this focuses attention on the development of improved control systems so that processes operate in the best possible way.
4. In particular, improved control is a key enabling technology underpinning: • enhanced product quality • waste minimization • environmental protection • greater throughput for a given installed capacity 8 The Excitement of Control Engineering Chapter 1 • greater yield • deferring costly plant upgrades, and • higher safety margins.
5. All of these issues are relevant to the control of an integrated plant such as that shown in Figure 1.2.
6. Figure 1.2. Process schematic of a Kellogg ammonia plant 1.2.2 Environmental Issues All companies and governments are becoming increasingly aware of the need to achieve the benefits outlined above whilst respecting finite natural resources and preserving our fragile environment.
7. Again, control engineering is a core enabling technology in reaching these goals.
8. To quote one well known example, the changes in legislation covering emissions from automobiles in California have led car manufacturers to significant changes in technology including enhanced control strategies for internal combustion engines.
9. Section 1.3.
10. Historical Periods of Control Theory 9 Thus, we see that control engineering is driven by major economic, political, and environmental forces.
11. The rewards for those who can get all the factors right can be enormous.
1.3 Historical Periods of Control Theory
1. We have seen above that control engineering has taken several major steps forward at crucial times in history (e.g. the industrial revolution, the Second World War, the push into space, economic globalization, shareholder value thinking etc.).
2. Each of these steps has been matched by a corresponding burst of development in the underlying theory of control.
3. Early on, when the compelling concept of feedback was applied, engineers sometimes encountered unexpected results.
4. These then became catalysts for rigorous analysis.
5. For example, if we go back to Watt’s fly ball governor, it was found that under certain circumstances these systems could produce self sustaining oscillations.
6. Towards the end of the 19th century several researchers (including Maxwell) showed how these oscillations could be described via the properties of ordinary differential equations.
7. The developments around the period of the SecondWorldWar were also matched by significant developments in Control Theory.
8. For example, the pioneering work of Bode, Nyquist, Nichols, Evans and others appeared at this time.
9. This resulted in simple graphical means for analyzing single-input single-output feedback control problems.
10. These methods are now generally known by the generic term Classical Control Theory.
11. The 1960’s saw the development of an alternative state space approach to control.
12. This followed the publication of work by Wiener, Kalman (and others) on optimal estimation and control.
13. This work allowed multivariable problems to be treated in a unified fashion.
14. This had been difficult, if not impossible, in the classical framework.
15. This set of developments is loosely termed Modern Control Theory.
16. By the 1980’s these various approaches to control had reached a sophisticated level and emphasis then shifted to other related issues including the effect of model error on the performance of feedback controllers.
17. This can be classified as the period of Robust Control Theory.
18. In parallel there has been substantial work on nonlinear control problems.
19. This has been motivated by the fact that many real world control problems involve nonlinear effects.
20. There have been numerous other developments including adaptive control, autotuning, intelligent control etc.
21. These are too numerous to detail here.
22. Anyway, our purpose is not to give a comprehensive history but simply to give a flavor for the evolution of the field.
23. At the time of writing this book, control has become a mature discipline.
24. It is thus possible to give a treatment of control which takes account of many different viewpoints and to unify these in a common framework.
25. This is the approach we will adopt here.
26. 10 The Excitement of Control Engineering Chapter 1 1.
27. 4 Types of Control System Design Control system design in practice requires cyclic effort in which one iterates between modeling, design, simulation, testing, and implementation.
28. Control system design also takes several different forms and each requires a slightly different approach.
29. One factor that impacts on the form that the effort takes is whether the system is part of a predominantly commercial mission or not.
30. Examples where this is not the case include research, education and missions such as landing the first man on the moon.
31. Although cost is always a consideration, these types of control design are mainly dictated by technical, pedagogical, reliability and safety concerns.
32. On the other hand, if the control design is motivated commercially, one again gets different situations depending on whether the controller is a small sub-component of a larger commercial product (such as the cruise controller or ABSi n a car) or whether it is part of a manufacturing process (such as the motion controller in the robots assembling a car).
33. In the first case one must also consider the cost of including the controller in every product, which usually means that there is a major premium on cost and hence one is forced to use rather simple microcontrollers.
34. In the second case, one can usually afford significantly more complex controllers, provided they improve the manufacturing process in a way that significantly enhances the value of the manufactured product.
35. In all of these situations, the control engineer is further affected by where the control system is in its lifecycle, e.g.: • Initial grass roots design • Commissioning and Tuning • Refinement and Upgrades • Forensic studies 1.4.1 Initial Grass Roots Design In this phase, the control engineer is faced by a green-field, or so called grass roots projects and thus the designer can steer the development of a system from the beginning.
36. This includes ensuring that the design of the overall system takes account of the subsequent control issues.
37. All too often, systems and plants are designed based on steady state considerations alone.
38. It is then small wonder that operational difficulties can appear down the track.
39. It is our belief that control engineers should be an integral part of all design teams.
40. The control engineer needs to interact with the design specifications and to ensure that dynamic as well as steady-state issues are considered.
41. Section 1.5.System Integration 11 1.4.2 Commissioning and Tuning Once the basic architecture of a control system is in place, then the control engineer’s job becomes one of tuning the control system to meet the required performance specifications as closely as possible.
42. This phase requires a deep understanding of feedback principles to ensure that the tuning of the control system is carried out in an expedient, safe and satisfactory fashion.
43. 1.4.3 Refinement and Upgrades Once a system is up and running, then the control engineer’s job turns into one of maintenance and refinement.
44. The motivation for refinement can come from many directions.
45. They include • internal forces - e.g. the availability of new sensors or actuators may open the door for improved performance • external forces - e.g. market pressures, or new environmental legislation may necessitate improved control performance 1.4.4 “Forensic” Studies Forensic investigations are often the role of control engineering consultants.
46. Here the aim is to suggest remedial actions that will rectify an observed control problem.
47. In these studies, it is important that the control engineer take a holistic view since successful control performance usually depends on satisfactory operation of many interconnected components.
48. In our experience, poor control performance is as likely to be associated with basic plant design flaws, poor actuators, inadequate sensors, or computer problems as it is to be the result of poor control law tuning.
49. However, all of these issues can, and should be, part of the control engineer’s domain.
50. Indeed, it is often only the control engineer who has the necessary overview to successfully resolve these complex issues.
51. 1.5 System Integration As is evident from the above discussion, success in control engineering depends on taking a holistic viewpoint.
52. Some of the issues that are embodied in a typical control design include: • plant, i.e. the process to be controlled • objectives • sensors • actuators • communications 12 The Excitement of Control Engineering Chapter 1 • computing • architectures and interfacing • algorithms • accounting for disturbances and uncertainty These issues are briefly discussed below.
53. 1.5.1 Plant As mentioned in subsection 1.4.1, the physical layout of a plant is an intrinsic part of control problems.
54. Thus a control engineer needs to be familiar with the physics of the process under study.
55. This includes a rudimentary knowledge of the basic energy balance, mass balance and material flows in the system.
56. The physical dimensions of equipment and how they relate to performance specifications must also be understood.
57. In particular, we recommend the production of back of the envelope physical models as a first step in designing and maintaining control systems.
58. These models will typically be refined as one progresses.
59. 1.5.2 Objectives Before designing sensors, actuators or control architectures, it is important to know the goal, that is, to formulate the control objectives.
60. This includes • what does one want to achieve (energy reduction, yield increase, . . . ) • what variables need to be controlled to achieve these objectives • what level of performance is necessary (accuracy, speed, . . . ) 1.5.3 Sensors Sensors are the eyes of control enabling one to see what is going on.
61. Indeed, one statement that is sometimes made about control is: If you can measure it,you can control it.
62. This is obviously oversimplified and not meant literally.
63. Nonetheless, it is a catchy phrase highlighting that being able to make appropriate measurements is an intrinsic part of the overall control problem.
64. Moreover, new sensor technologies often open the door to improved control performance.
65. Alternatively, in those cases where particularly important measurements are not readily available then one can often infer these vital pieces of information from other observations.
66. This leads to the idea of a soft or virtual sensor.
67. We will see that this is one of the most powerful techniques in the control engineer’s bag of tools.
68. Section 1.5. System Integration 13 1.5.4 Actuators Once sensors are in place to report on the state of a process, then the next issue is the ability to affect, or actuate, the system in order to move the process from the current state to a desired state.
69. Thus, we see that actuation is another intrinsic element in control problems.
70. The availability of new or improved actuators also often opens the door to significant improvements in performance.
71. Conversely, inadequate, or poor, actuators often lie at the heart of control difficulties.
72. A typical industrial control problem will usually involve many different actuators - see, for example, the flatness control set-up shown in Figure 1.3. Figure 1.3. Typical flatness control set-up for rolling mill 1.5.5 Communications Interconnecting sensors to actuators, involves the use of communication systems.
73. A typical plant can have many thousands of separate signals to be sent over long distances.
74. Thus the design of communication systems and their associated protocols is an increasingly important aspect of modern control engineering.
75. There are special issues and requirements for communication systems with real time data.
76. For example, in voice communication, small delays and imperfections in transmission are often unimportant since they are transparent to the recipient.
77. However, in high speed real time control systems, these issues could be of major importance.
78. For example, there is an increasing tendency to use Ethernet type connections for data transmission in control.
79. However, as is well known by those familiar with this technology, if a delay occurs on the transmission line, then the transmitter simply tries again at some later random time.
80. This obviously introduces a non-deterministic delay into the transmission of the data.
81. Since all control 14 The Excitement of Control Engineering Chapter 1 systems depend upon precise knowledge of, not only what has happened, but when it happened, attention to such delays is very important for the performance of the overall system.
82. 1.5.6 Computing In modern control systems, the connection between sensors and actuators is invariably made via a computer of some sort.
83. Thus, computer issues are necessarily part of the overall design.
84. Current control systems use a variety of computational devices including DCS’s (Distributed Control Systems), PLC’s (Programmable Logic Controllers), PC’s (Personal Computers), etc.
85. In some cases, these computer elements may be rather limited with respect to the facilities they offer.
86. As with communication delays, computational delays can be crucial to success or failure in the operation of control systems.
87. Since, determinism in timing is important, a multi-tasking real-time operating system may be required.
88. Another aspect of computing is that of numerical precision.
89. We know of several control systems that failed to meet the desired performance specifications simply because of inadequate attention to numerical issues.
90. For this reason, we will devote some attention to this issue in the sequel.
91. A final computer based question in control concerns the ease of design and implementation.
92. Modern computer aided tools for rapid prototyping of control systems provide integrated environments for control system modeling, design, simulation and implementation.
93. These pictures to real time code facilities have allowed development times for advanced control algorithms to be reduced from many months to the order of days or, in some cases, hours.
94. 1.5.7 Architectures and Interfacing The issue of what to connect to what is a non-trivial one in control system design.
95. One may feel that the best solution would always be to bring all signals to a central point so that each control action would be based on complete information (leading to so called, centralized control).
96. However, this is rarely (if ever) the best solution in practice.
97. Indeed, there are very good reasons why one may not wish to bring all signals to a common point.
98. Obvious objections to this include complexity, cost, time constraints in computation, maintainability, reliability, etc.
99. Thus one usually partitions the control problem into manageable sub-systems.
100. How one does this is part of the control engineer’s domain.
101. Indeed, we will see in the case studies presented in the text that these architectural issues can be crucial to the final success, or otherwise, of a control system.
102. Indeed, one of the principal tools that a control system designer can use to improve performance is to exercise lateral thinking relative to the architecture of the control problem.
103. As an illustration, we will present a real example later in the text (see Chapter 8) where thickness control performance in a reversing rolling mill is irrevocably constrained by a particular architecture.
104. It is shown that no improvement in actuators, sensors or algorithms (within this architecture) can remedy the probSection 1.5. System Integration 15 lem.
105. However, by simply changing the architecture so as to include extra actuators (namely the currents into coiler and uncoiler motors) then the difficulty is resolved (see Chapter 10).
106. As a simpler illustration, the reader is invited to compare the difference between trying to balance a broom on one’s finger with one’s eyes open or shut.
107. Again there is an architectural difference here - this time it is a function of available sensors.
108. A full analysis of the reasons behind the observed differences in the difficulty of these types of control problems will be explained in Chapters 8 and 9 of the book.
109. We thus see that architectural issues are of paramount importance in control design problems.
110. A further architectural issue revolves around the need to divide and conquer complex problems.
111. This leads to a hierarchical view of control as illustrated in Table 1.1 Level Description Goal Time frame Typical design tool 4 Plant wide optimization Meeting customer orders and scheduling supply of materials Everyday (say) Static optimization 3 Steady state optimization at unit operational level Efficient operation of a single unit (e.g. distillation column) Every hour (say) Static optimization 2 Dynamic control at unit operation level Achieving set-points specified at level 3 and achieving rapid recovery from disturbances Every minute (say) Multivariable control, e.g. Model Predictive Control 1 Dynamic control at single actuator level Achieving liquid flow rates etc as specified at level 2 by manipulation of available actuators (e.g. valves) Every second (say) Single variable control, e.g. PID Table 1.1. Typical control hierarchy Having decided what connections need to be made, there is the issue of interfacing the various sub-components.
112. This is frequently a non-trivial job as it is often true that special interfaces are needed between different equipment.
113. Fortunately vendors of control equipment are aware of this difficulty and increasing attention is being paid to standardization of interfaces.
114. 16 The Excitement of Control Engineering Chapter 1 1.5.8 Algorithms Finally, we come to the real heart of control engineering i.e. the algorithms that connect the sensors to the actuators.
115. It is all to easy to underestimate this final aspect of the problem.
116. As a simple example from the reader’s everyday experience, consider the problem of playing tennis at top international level.
117. One can readily accept that one needs good eye sight (sensors) and strong muscles (actuators) to play tennis at this level, but these attributes are not sufficient.
118. Indeed eye-hand coordination (i.e. control) is also crucial to success.
119. Thus beyond sensors and actuators, the control engineer has to be concerned with the science of dynamics and feedback control.
120. These topics will actually be the central theme of the remainder of this book.
121. As one of our colleagues put it; Sensors provide the eyes and actuators the muscle but control science provides the finesse.
122. 1.5.9 Disturbances and Uncertainty One of the things that makes control science interesting is that all real life systems are acted on by noise and external disturbances.
123. These factors can have a significant impact on the performance of the system.
124. As a simple example, aircraft are subject to disturbances in the form of wind gusts, and cruise controllers in cars have to cope with different road gradients and different car loadings.
125. However, we will find that, by appropriate design of the control system, quite remarkable insensitivity to external disturbances can be achieved.
126. Another related issue is that of model uncertainty.
127. All real world systems have very complex models but an important property of feedback control is that one can often achieve the desired level of performance by using relatively simple models.
128. Of course, it is beholden on designers to appreciate the effect of model uncertainty on control performance and to decide if attention to better modeling would enable better performance to be achieved.
129. Both of the issues raised above are addressed, in part, by the remarkable properties of feedback.
130. This concept will underpin much of our development in the book.
131. 1.5.10 Homogeneity A final point is that all interconnected systems, including control systems, are only as good as their weakest element.
132. The implications of this in control system design are that one should aim to have all components (plant, sensors, actuators, communications, computing, interfaces, algorithms, etc) of roughly comparable accuracy and performance.
133. If this is not possible, then one should focus on the weakest component to get the best return for a given level of investment.
134. For example, there is no point placing all one’s attention on improving linear models (as has become fashionable in parts of modern control theory) if the performance limiting factor Section 1.5. System Integration 17 is that one needs to replace a sticking valve or to develop a virtual sensor for a key missing measurement.
135. Thus a holistic viewpoint is required with an accurate assessment of error budgets associated with each sub-component.
136. 1.5.11 Cost Benefit Analysis Whilst on the subject of ensuring best return for a given amount of effort it is important to raise the issue of benefits analysis.
137. Control engineering, in common with all other forms of engineering, depends on being able to convince management that there is an attractive cost-benefit trade-off in a given project.
138. Payback periods in modern industries are often as short as 6 months and thus this aspect requires careful and detailed attention.
139. Typical steps include: • assessment of a range of control opportunities • developing a short list for closer examination • deciding on a project with high economic or environmental impact • consulting appropriate personnel (management, operators, production staff, maintenance staff etc) • identifying the key action points • collecting base case data for later comparison • deciding on revised performance specifications • updating actuators, sensors etc • development of algorithms • testing the algorithms via simulation • testing the algorithms on the plant using a rapid prototyping system • collecting preliminary performance data for comparison with the base case • final implementation • collection of final performance data • final reporting on project 18 The Excitement of Control Engineering Chapter
140. 1 1.6 Summary
141. • Control Engineering is present in virtually all modern engineering systems
142. • Control is often the hidden technology as its very success often removes it from view
143. • Control is a key enabling technology with respect to ◦ enhanced product quality ◦ waste and emission minimization ◦ environmental protection ◦ greater throughput for a given installed capacity ◦ greater yield ◦ deferring costly plant upgrades, and ◦ higher safety margins
144. • Examples of controlled systems include System Controlled outputs include Controller Desired performance includes Aircraft Course, pitch, roll, yaw Autopilot Maintain flight path on a safe and smooth trajectory Furnace Temperature Temperature controller Follow warm-up temperature profile, then maintain temperature Wastewater treatment pH value of effluent pH controller Neutralize effluent to specified accuracy Automobile Speed Cruise controller Attain, then maintain selected speed without undue fuel consumption
145. • Control is a multidisciplinary subject that includes ◦ sensors ◦ actuators ◦ communications ◦ computing ◦ architectures and interfacing ◦ algorithms
146. • Control design aims to achieve a desired level of performance in the face of disturbances and uncertainty Section 1.7.Further Reading 19
147. • Examples of disturbances and uncertainty include System Actuators Sensors Disturbances Uncertainties Aircraft Throttle servo, rudder and flap actuators, etc.
148. Navigation instruments Wind, air pockets, etc.
149. Weight, exact aerodynamics, etc.
150. Furnace Burner valve actuator Thermocouples, heat sensors Temperature of incoming objects, etc.
151. Exact thermodynamics, temperature distribution Wastewater treatment Control acid valve servo pH sensor Inflow concentration pH gain curve, measurement errors Automobile Throttle positioning Tachometer Hills Weight, exact dynamics 1.
152. 7 Further Reading Historical notes The IEEE History Centre and its resources are an excellent source for the historically interested reader.
--

Euler's formula

An Imaginary Tale: The Story of the Square Root of Minus One


http://betterexplained.com/articles/intuitive-understanding-of-eulers-formula/

Lumped Ckt Abstraction

POWER OF ABSTRACTION

1. Engineering is purposeful use of science.
2. Science provides understanding of natural phenomena.
3. Scientific study involves experiment.
4. Scientific laws (concise statements or equations) explain experimental data.
5. Laws of physics abstract experimental data to practitioners
6. Practitioners use specific phenomena (without specifics of experiments & data that inspired laws)
7. Abstractions have goals.
8. Abstractions apply when appropriate constraints are met.

Eg: Newton’s laws of motion

1. Here simple statements relate dynamics of rigid bodies to their masses & external forces.
2. The laws apply under certain constraints (ex: when velocities are much smaller than speed of light.)
3. Scientific abstractions are simple & easy to use.
4. Scientific abstractions help us use properties of nature.

1. Electrical engg is purposeful use of Maxwell’s Equations (or Abstractions) for EMG phenomena.
2. To ease use of EMG, EE creates a new abstraction layer on top of Maxwell’s Equations
3. This abstraction is called ‘Lumped circuit abstraction’.
4. Lumped circuit abstraction connects physics & EE.
5. It makes EE an art of creating & exploiting successive abstractions to manage complexity of building useful electrical systems.

6. Abstraction makes building complex systems manageable.

Eg: force equation: F = ma.
1. With this we calculate acceleration (of a particle with a given mass) for an applied force.
2. Abstraction disregards size, shape, density, and temperature (properties immaterial to calculation of object’s acceleration.)
3. It ignores myriad details (of experiments & observations) that led to force equation.
4. Force equation is accepted as a given.

1. Laws & abstractions leverage/build upon past experience & work.
2. Over past century,a set of EE abstractions transformed physical sciences to engg - to build useful, complex systems.
3. Abstractions transform science to engg (and saves us from scientific minutiae)
4. Abstractions are derived through discretization discipline.
5. Discretization is called lumping.
6. A discipline is a self-imposed constraint.
7. Discipline of discretization states that
a. We choose to deal with discrete elements or ranges &
b. We ascribe a single value to each discrete element or range.
8. Discretization discipline ignores distribution of values within a discrete element.
9. Discretization discipline requires systems (built on this principle) operate within appropriate constraints so that single-value assumptions hold.
10. LCA (fundamental to EE) is based on lumping or discretizing matter.
11. Digital systems use digital abstraction.
12. Digital abstraction is based on discretizing signal values.
13. Clocked digital systems are based on discretizing both signals and time.
14. Digital systolic arrays are based on discretizing signals, time and space.


1. EE creates further abstractions to manage complexity of building large systems.
2. A lumped circuit element is an abstract representation (model) of material with complicated internal behavior.
3. A circuit often is an abstract representation of interrelated physical phenomena.
4. Operational amplifier is composed of primitive discrete elements
5. An opamp is a powerful abstraction that simplifies building of bigger analog systems.
6. Logic gate, digital memory, digital finite-state machine, and microprocessor are all abstractions developed to facilitate building complex computer & control systems.
7. Art of computer programming is creating successively higher-level abstractions from lower-level primitives.


1.2 LUMPED CIRCUIT ABSTRACTION
1. A lightbulb lights up when connected to battery (by pair of cables).
2. To know current flowing through bulb, we employ Maxwell’s equations.
3. We derive current by analysis of physical properties of bulb, battery, and cables.
4. This is a complicated process.
5. EEs do such computations to design more complex circuits (say with multiple bulbs & batteries.)
6. So how to simplify our task?
7. We observe that if we discipline ourselves to asking only simple questions, such as what is net current flowing through bulb, we can ignore internal properties of bulb and represent bulb as a discrete element.
8. Further, for purpose of computing current, we can create a discrete element known as a resistor and replace bulb with it.
9. We define resistance of bulb R to be ratio of voltage applied to bulb and resulting current through it.
10. In other words, R = V/I.
11. Notice that actual shape and physical properties of bulb are irrelevant provided it offers resistance R.
12. We were able to ignore internal properties and distribution of values inside bulb simply by disciplining ourselves not to ask questions about those internal properties.
13. In other words, when asking about current, we were able to discretize bulb into a single lumped element whose single relevant property was its resistance.
14. This situation is analogous to point mass simplification that resulted in force relation in Equation 1.1, where single relevant property of object is its mass.
15. As illustrated in Figure 1.5, a lumped element can be idealized to point
16. Terminal FIGURE where it can be treated as a black box accessible through a few terminals.
17. Behavior at terminals is more important than details of behavior internal to black box.
18. That is, what happens at terminals is more important than how it happens inside black box.
19. Said another way, black box is a layer of abstraction between user of bulb and internal structure of bulb.
20. Resistance is property of bulb of interest to us.
21. Likewise, voltage is property of battery that we most care about.
22. Ignoring, for now, any internal resistance of battery, we can lump battery into a discrete element called by same name supplying a constant voltage V, as shown in Figure 1.4b.
23. Again, we can do this if we work within certain constraints to be discussed shortly, and provided we are not concerned with internal properties of battery, such as distribution of electrical field.
24. In fact, electric field within a real-life battery is horrendously difficult to chart accurately.
25. Together, collection of constraints that underlie lumped circuit abstraction result in a marvelous simplification that allows us to focus on specifically those properties that are relevant to us.
26. Notice also that orientation and shape of wires are not relevant to our computation.
27. We could even twist them or knot them in any way.
28. Assuming for now that wires are ideal conductors and offer zero resistance,3 we can rewrite bulb circuit as shown in Figure 1.4b using lumped circuit equivalents for battery and bulb resistance, which are connected by ideal wires.
29. Accordingly, Figure 1.4b is called lumped circuit abstraction of lightbulb circuit.
30. If battery supplies a constant voltage V and has zero internal resistance, and if resistance of bulb is R, we can use simple algebra to compute current flowing through bulb as I = V/R.
31. Lumped elements in circuits must have a voltage V and a current I defined for their terminals.
32. 4 In general, ratio of V and I need not be a constant.
33. ratio is a constant (called resistance R) only for lumped elements that obey Ohm’s law.
34. 5 circuit comprising a set of lumped elements must also have a voltage defined between any pair of points, and a current defined into any terminal.
35. Furthermore, elements must not interact with each other except through their terminal currents and voltages.
36. That is, internal physical phenomena that make an element function must interact with external electrical phenomena only at electrical terminals of that element.
37. As we will see in Section 1.3, lumped elements and circuits formed using these elements must adhere to a set of constraints for these definitions and terminal interactions to exist.
38. We name this set of constraints lumped matter discipline.
39. lumped circuit abstraction Capped a set of lumped elements that obey lumped matter discipline using ideal wires to form an assembly that performs a specific function results in lumped circuit abstraction.
40. Notice that lumped circuit simplification is analogous to point-mass simplification in Newton’s laws.
41. Lumped circuit abstraction represents relevant properties of lumped elements using algebraic symbols.
42. For example, we use R for resistance of a resistor.
43. Other values of interest, such as currents I and voltages V, are related through simple functions.
44. ease of using algebraic equations in place of Maxwell’s equations to design and analyze complicated circuits will become much clearer in following chapters.
45. process of discretization can also be viewed as a way of modeling physical systems.
46. resistor is a model for a lightbulb if we are interested in finding current flowing through lightbulb for a given applied voltage.
47. It can even tell us power consumed by lightbulb.
48. Similarly, as we will see in Section 1.6, a constant voltage source is a good model for battery when its internal resistance is zero.
49. Thus, Figure 1.4b is also called lumped circuit model of lightbulb circuit.
50. Models must be used only in domain in which they are applicable.
51. For example, resistor model for a lightbulb tells us nothing about its cost or its expected lifetime.
52. primitive circuit elements, means for combining them, and means of abstraction form graphical language of circuits.
53. Circuit theory is a well established discipline.
54. With maturity has come widespread utility.
55. Language of circuits has become universal for problem-solving in many disciplines.
56. Mechanical, chemical, metallurgical, biological, thermal, and even economic processes are often represented in circuit theory terms, because mathematics for analysis of linear and nonlinear circuits is both powerful and well-developed.
57. For this reason electronic circuit models are often used as analogs in study of many physical processes.
58. Readers whose main focus is on some area of electrical engineering other than electronics should therefore view material in this