The document describes the fuel master and coordinated control system (CCS) used to automatically control the amount of coal fed to a boiler. The fuel master control loop uses a controller to vary the output to multiple coal feeders based on the boiler's operating mode and demand. The CCS provides coordinated control of the boiler and turbine to maintain balance of the unit load, steam pressure, and fuel/air demand. It can operate the boiler in follow, coordinated, or base modes depending on the status of the boiler and turbine masters.

1. FUEL MASTER AND CCS AUTO LOOP
29/03/2021
ITPCL/IMD/0011 Arun kumar.J

2.  THE FUEL MASTER CONTROL LOOP IS USED TO CONTROL THE AMOUNT OF COAL
FED TO THE BOILER.
 THE SET POINT OF THE CONTROLLER DEPENDS UPON THE MODE IN WHICH THE
BOILER IS OPERATED
 BOILER FOLLOW DEMAND IF OPERATED IN BOILER FOLLOW MODE
 BOILER COORDINATED DEMAND IF OPERATED IN CCS.
 THE OUTPUT OF THE CONTROLLER IS FED TO ALL THE COAL FEEDERS.
FUEL MASTER CONTROL
Set point
Process Value
Measurement
Final Control Element
SET POINT IS
BOILER MASTER DEMAND
OR
DEMAND AS PER TOTAL
AIR FLOW.
TOTAL FUEL FLOW TPH
COAL + OIL
Fed to COAL FEEDEER
A,B,C,D,E,F AND G.

3. FUEL MASTER CONTROL
Δ
PI
A
M
Set by Operator
PV
OP
FDR
A
SP
K .85
Kp 0.5
Ki .89
TOTAL AIR FLOW
IN %
F(X)
INPUT
OUTPU
T
0 0
50 55
70 90
90 120
110 130
150 165
<
TOTAL FUEL FLOW
COAL + OIL
FDR
B
FDR
C
FDR
D
FDR
E
FDR
F
FDR
G
BOILER MASTER
DEMAND

4. Condition in which Fuel Master control comes out of Auto to Manual mode
 Any Feeder not in AUTO.
Any Feeder speed signal bad quality
 Runback and FCB not active and Fuel Master demand and total fuel flow
having deviation of +/- 25%
 Total fuel flow >125% or < 0 %
FUEL MASTER CONTROL

5.  The coordinated control system considering the boiler and turbine controls as
whole by controlling the unit load control, main steam pressure, boiler fuel
demand.
 CCS Master Control System will respond to the demand signal from Unit load
Demand
 Coordinated boiler-turbine control is considered as unit coordinated. Turbine has
faster response to the pressure and load than the boiler. It is necessary to
improve the boiler’s response speed to fuel in order to ensure the energy
balance between boiler and turbine.
 The system controls the unit load and the main steam pressure, and produces
the position demand to turbine control valve (CV) as well as the fuel/air demand
to boiler.
CCS CONTROL

6. UNIT CONTROL MODE
BOILER FOLLOW MODE
BOILER MASTER
IN AUTO
TURBINE MASTER
NOT AUTO
AND
TURBINE FOLLOW MODE
BOILER MASTER
NOT AUTO
TURBINE MASTER
IN AUTO
AND
CCS MODE
BOILER MASTER
IN AUTO
TURBINE MASTER
IN AUTO
AND
BASE MODE
BOILER MASTER
NOT AUTO
TURBINE MASTER
NOT AUTO
AND

7. BOILER FOLLOW MODE
In the boiler follow mode operation, the boiler energy signal is given as boiler
demand. The boiler energy calculation is based on First stage steam pressure, main
steam pressure and main steam pressure set point.
The ratio of First stage steam pressure to main steam pressure indicates
the turbine demand. The main steam pressure set point variation indicates the
demand variation. Hence the function of these signals forms the boiler demand.
TURBINE FOLLOW MODE
In the turbine follow mode operation the main steam pressure set point is
taken as set point for this controller. The controller action shall be that any increase
in the main steam pressure (PV) will increase the controller output and vice versa.
In normal, the boiler follow mode will be utilized to improve the stability and
response. The turbine follow mode will be adopted when RUNBACK occurs.
UNIT CONTROL MODE

8. BOILER MASTER DEMAND
BOILER FOLLOW
DEMAND
BOILER CCS
DEMAND
T
IN CCS
M/A
STATION
BOILER MASTER
DEMAND
MAIN STEAM PR.
MAIN STEAM SP.
PV
SP
A

9. MAIN STEAM SETPOINT
OR
REMSET
STATION
MAIN
STEAM
SETPOINT
A
CCS AND
VAR. PR. SELECTED
RUNBACK
BASE MODE
T
T
T
RUNBACK MS SP.
RUNBACK
BASE MODE
MAINSTEAM PR.
MAINSTEAM SP.
INPUT OUTPUT
0 0
60 1
300 1
F(X) SUM
UNIT
LOAD
LIMITER
MS SP. BIAS
74.1
169

10. BOILER FOLLOW DEMAND
Δ
PI
PV
OP
SP K 0.5
Kp 1.0
Ki 0.1
DIV
BOILER FOLLOW
DEMAND
0
MAIN STEAM SP.
MAIN STEAM PV.
SUB MUL by -1
INPUT OUTPUT
0 0
167 100
F(X)
MUL
MAIN STEAM SP
MAIN STEAM PV.
FIRST STAGE PR.
FF

11. BOILER CCS DEMAND
INPUT OUTPUT
0 0
600 100
F(X) MUL
UNIT LOAD
0.7
SUM
TO NEXT
PAGE
MAIN STEAM PR.
PV-SP ERROR
LAG 150 SEC
SUB LIMITER
(-)
1
-1
UNIT LOAD DMD
+ RGMO DMD
LAG 40 SEC
SUB LIMITER
(-) 5
-5
F(X)
INPUT OUTPUT
0 0
600 100
630 105
MAIN STEAM PR.
SET POINT
LAG 60 SEC
SUB
(-)

12. BOILER CCS DEMAND
Δ
PI
PV
OP
SP
K 2
Kp 1.5
Ki 80
BOILER CCS
DEMAND
0
DEB SIGNAL
FF
SUM
BI
BD
ACTUAL LOAD – LOAD
DEMAND > +150
ACTUAL LOAD – LOAD
DEMAND < -150
FROM PREVIOUS
PAGE

13. DIRECT ENERGY BALANCE SIGNAL
DIV
MAIN STEAM SP.
MAIN STEAM PV.
SUM
MUL
INPUT OUTPUT
0 0
200 20
SUM
DRUM PRESSURE
DEB SIGNAL
FIRST STAGE PR. F(X)
F(X)
F(X)
F(X)
LAG 25SEC
FIRST STAGE PR.
SUM
LAG
1 SEC
S3 1
S4 6.5
S3 1
S4 -1

14. TURBINE MASTER DEMAND
TURBINE FOLLOW
DEMAND
TURBINE CCS
DEMAND
T
IN CCS
M/A
STATION
TURBINE MASTER
DEMAND
UNIT LOAD DEMAND
UNIT ACTUAL LOAD
PV
SP
A
TO DEH
COMMAND TO CV’S

15. TURBINE FOLLOW DEMAND
Δ
PI
PV
OP
SP K 0.5
Kp 0.5
Ki 1.5
TURBINE FOLLOW
DEMAND
0
UNIT ACTUAL LOAD MUL
INPUT OUTPUT
0 1
60 1
300 1
F(X)
MS PV-SP ERROR

16. TURBINE CCS DEMAND
Δ
PI
PV
OP
SP
K .85
Kp .85
Ki 3
TURBINE CCS
DEMAND
0
INPUT OUTPUT
0 1
300 1
SUB LIMITER
UNIT
ACTUALLOAD
UNIT LOAD
DEMAND
MAIN STEAM
SP-PV ERROR
F(X)
F(X) MUL F(X)
INPUT OUTPUT
-50 -50
-1.5 0
1.5 0
50 50
INPUT OUTPUT
-15 -15
-5 0
1.5 0
50 50
SUB
(-)
(-)
35
-35

17. UNIT LOAD DEMAND
REM SET
BY
OPERATOR
UNIT
LOAD
DEMAND
T
RUNBACK RATE
RUNBACK
SUM
INTEGRAL
RUNDOWN RATE
>
LIMITER
LOAD
COMMAND
FROM RGMO
0
630
K 1
Ki 1