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1. BOILER AUTOMATION
PRESENTED BY
AMAR GUPTA

2. Importance of AUTOMATION in Boiler

3. 1. The controller we are using in the
boiler is ABB 800M Make Ethernet
based.
2. It is a comprehensive, distributed and
modular process I/O system that
communicates with parent controllers
over industry-standard field buses
3.. In our arrangement we have to two
system one is server and other redundant
PC of server (and can be access in case
of emergency)

4. Boiler Existing Control loop
 DRUM LEVEL (via 3 Element & Single Element)
 Combustion Control
 Deaerator Level
 Deaerator Pressure
 Furnace pressure control function
 P.R.D.S.H.
 S.H. STEAM TEMPERATURE
 BOILER INTERLOCKS

5. SINGLE ELEMENT DRUM LEVEL CONTROL
OF L.P. BOILER
 IN A SINGLE ELEMENT CONTROL , THE LEVEL
TRANSMITTER ON THE STEAM DRUM WILL
TRANSMIT THE LEVEL SIGNAL TO THE
CONTROLLER.
 LEVEL CONTROLLER COMPARES THIS SIGNAL
WITH THE SET POINT
 AND SENDS AN OUTPUT SIGNAL TO THE FEED
WATER CONTROL VALVE
 TO OPEN OR CLOSE TO INCREASE OR
DECREASE THE FEED WATER FLOW quantity TO
THE BOILER.

6. Steam Drum LT
LIC
I/P
Feed
Pump
Single element drum level control in LP Boiler
CONTROL VALVE
BY PASS VALVE
SET POINT

7.  In high pressure boilers , when the steam demand of the boiler increases
suddenly ,
 The withdrawal of steam from the steam drum will be higher than the
steam generation as combustion control will take some time to react and
increase the fuel heat input to the boiler.
 This will result in drum pressure falling temporarily, this loss of pressure
will result in the formation of steam bubbles in the drum water due to the
enthalpy difference between the two pressure levels.
 This bubbling in the drum water will result in the foaming and increase
in the volume leading to the level going up spuriously.
 The level transmitter will transmit this increase in drum level to the
controller leading to reduction in feed water flow instead of increasing
the feed water flow due to higher demand on boiler.
 To avoid such a wrong control 3 element drum level control is required

8. THREE ELEMENT DRUM LEVEL CONTROL IN H.P.
BOILER
 THE AIM OF THIS CONTROL LOOP IS TO MAINTAIN
THE DRUM LEVEL AT THE NORMAL OPERATING
LEVEL OF THE BOILER DRUM. THE THREE
ELEMENTS IN THIS LOOPARE
1.DRUM LEVEL
2.STEAM FLOW
3.FEED WATER FLOW
.

9. Three Element Loop Diagram

10. DEAERATOR LEVEL CONTROL LOOP
 The deaerator level control is similar
to the single element drum level
control.
DEAERATOR
TANK
D.C.S.
I/P
Two wire P.S..
FEED WATER
4 – 20 mA. AIR SIG.
WATER INLET
BY PASS VALVE

11. DEAERATOR PRESSURE CONTROL LOOP
DEAERATOR
TANK
P.T.
D.C.S.
I/P
TwowireP.S.
STEAM PRESSURE
0.2 - 0.5 KG/CM^2
 This is
necessary to
maintain the
de-aeration
temperature at
the required
to achieve the
removal of
gases from
water.
P.R.V.
Pressure
Transmitter
4 – 20 mA
WATER INLET
FEED
PUMP
AIR SIG.

12.  In boilers with high super heat
temperatures it is necessary to protect the
down stream equipment like steam
turbine from large variation in
temperatures.
 The steam temperature leaving the boiler
is required to be maintained constant in
many applications.
 The super heater outlet temperature is
sent to the controller by the temperature
transmitter.
 The controllers compares the same with
the set point and gives a resultant signal
to the spray control valve to change the
spray water quantity.
De-superheater
spray flow valve
TT
PV
MV
SP
+
-
-
Temperature
control
Water flow to de-superhtr.
Heat flow to
1st stage
+
Steam temp from
1st stage superhtr.
Heat flow to
2nd stage
2nd stage
superheate
r.

13.  In boilers provided with both FD
and id fans it is necessary to
maintain the furnace draft at near
zero pressure. ( between –5 to –10
mmwc to prevent flame from
coming out and injuring operating
personnel )
 The furnace draft transmitter sends
the furnace draft signal to the
controller.
 Controller on comparing the same
with the set point sends an output
signal to the V.F.D. of the id fan
and it control the speed and thus
controls the furnace pressure
within limits.
SP GIVEN BY
OPERATOR
Furnace
ID Fan
extraction
rate
Draft control
PT
PV
SP
+
-
-
+
FD air flow
Difference will integrate
to change pressure over
time

14.  The main object of automatic boiler combustion control is to
regulate automatically, the heat input to a boiler in terms of fuel and
air supplied in relation to output or steam demand.
 This should be implemented as efficiently as possible in terms of
combustion quality and furnace stability.
 Steam pressure is taken as the indication for boiler load as the
steam pressure decreases in increasing load and vice versa.
 Hence variations in steam pressure is detected and the supply of the
fuel and air adjusted accordingly.
 The successful operation of the combustion control system depends
upon the capability to vary the fuel supply to the furnace based on
the signals from the control system.

15.  The steam demand from boiler vary
depending upon change in process
requirement or power requirement.
 The fuel fed to the boiler should be
controlled to give the necessary quantity
of steam.
 The steam demand increase or decrease
will be indicated by the boiler outlet
pressure.
 Hence combustion control is essentially
a control to keep the boiler outlet
pressure constant.
 The steam pressure transmitter in the
main steam line sends the signal to the
controller which in turn sends an output
signal to the feeder motors in the solid
fuel fired boilers and to the fuel control
valve in the case of oil and gas fired
boilers.
Boiler master
controller
Fuel Air ratio
Air
controller
Fuel
controller
FD air
V.F.D.
Fuel
V.F.D.
Furnace
/Steam
PT
S.P.
S.P.
S.P.S.P.
Firing Rate
Demand

16. Pressure Reducing Desuper heating
 This control loop is very important for
process point of view in sugar industry
 Because the reaming amount of steam is
completed by this conversion in Boiling
House.
 In this live steam is enter of pressure
45Kg/cm^2 and temperature of 440-
445*C
 Now with the help of pressure reducing
valve and de-super heating valve this live
steam is converted into required demand
of Boiling House up to 1.5 Kg/cm^2 @
118 – 122 *C and one more PRDSH need
to install requirement of 7 Kg/cm^2 *C
steam for Sulphur Burner and Super
heated wash water.
 For continuous controlling of both
parameter we have a feedback loop of
Pressure transmitter and Temperature
transmitter
PT
TT
D.C.S
I/P
P.R.V.
Water Inlet
BY PASS VALVE
45 Kg/cm^2
1.5 or 7Kg/cm^2
Steam Inlet
410-425*C
118-125*C

17. BOILER INTERLOCKS
 In addition to closed loop fully modulating controls required for the
normal operation of the boiler , interlock controls are required for the
safe startup, shut-down and operation of the boiler.
 The following are some of the interlocks are being used for baggass fired
boilers.
 ID run feed back with FD fan.
 Fuel feeder will not start without FD and ID fans run.
 Fuel feeder trip in case of steam drum low level very low trip switch is
activated
 Boiler will trip if instrument air pressure fails.
 Standby feed pump will automatically come into operation when
operating pump fails (NOT EXISTING)