The document discusses instrumentation and controls used in boiler systems. It describes the key objectives of instrumentation including measurement, control, quality control and safety. It then provides details on various control loops used in boiler instrumentation including drum level control, steam temperature control, combustion control, furnace pressure control, deaerator pressure and level control, and soot blower pressure control. It stresses the importance of good maintenance management for instrumentation and controls.

1. BOILER INSTRUMENTATION & CONTROLS

2. 1. INTRODUCTION: P ROCESS INSTRUMENTATION IMPLIES JUDICIOUS APPLICATION OF CERTAIN DEVICES, WHICH SUBSTITUTE OR SUPPLEMENT THE COGNITIVE HUMAN CHARACTERISTICS-LIKE PERCEPTUAL, COMMUNICATIVE, INTELLECTUAL OR MANIPULATIVE- IN ORDER TO IDENTIFY AND QUALIFY THE VITAL PROCESS VARIABLES (PHYSICAL OR CHEMICAL) TO ACCOMPLISH AUTOMATIC CONTROL OF THE PROCESS WITHIN SOME SPECIFIED LIMITATION.

3. P R I M A R Y O B J E C T I V E S O F INSTRUMENTATION TO PROVIDE: MEASUREMENT & CONTROL. ONLINE Q UALITY & H IGH P RODUCTIVITY. DOCUMENTATION&REPORT GENERATION. LONGIVITY OF THE PLANT.

4. GOOD INSTRUMENTATION MEANS QUALITY PRODUCTION, OPTIMISED OPERATION, LONGIVITY AND SAFETY OF THE PLANT . WE M E A N : TOTAL ECONOMY O F T HE P LANT .

5. " INSTRUMENTATION" CONNOTES FACT-FINDING, DISPLAY OF INFORMATION, APPLICATION-ENGINEERING AND AUTOMATIC CONTROL. THE PROGRESS OF MEASUREMENT IS THE PROGRESS OF SCIENCE. LIKEWISE ADVANCEMENT IN THE ART AND SCIENCE OF MEASUREMENT SH OULD LEAD ADVANCEMENT OF INDUSTRIAL PROGRESS.

6. “ BOILER INSTRUMENTATION &CONTROLS”- TOPIC OF THE DAY BOILERS PLAY AN IMPORTANT ROLE IN POWER GENERATION AND IN PROCESSINDUSTRIES AS HEATING MEDIUM, AS COMPARED TO ANY OTHER SOURCE AS STEAM ENERGY COSTS LESS.

7. THE PROBLEM OF BOILER CONTROL IS ONE OF THE COORDINATING FIVE FACTORS: STEAM PRESSURE, FEED WATER SUPPLY. FUEL QUANTITY, COMBUSTION-AIR QUANTITY AND REMOVAL OF WASTE GASES.

8. BOILER-CONTROLS OVERVIEW DRUM LEVEL 2. STEAM FLOW 3. FEED WATER FLOW 4. OUTLET STEAM PRESSURE 5. FUEL FLOW & COMBUSTION 6. S.H STEAM TEMPERATURE 7. FURNACE DRAFT 8. DEAIRATOR LEVAL 9. DEAIRATOR ST. PRESSURE 10.SOOT BLOW ST.PRESSURE 1. SAFETY INTERLOCKS 2. SOOT BLOW INTERLOCKS

9. BOILER WATER&STEAM BOILER AIR & GAS

10. AN INCREASE IN FIRING RATE OF THE BOILER, WHEN IT DROPS; A DECREASE IN FIRING RATE,WHEN IT INCREASES, INVOLVING FEED WATER, FUEL & AIR. A CHANGE IN STEAM PRESSURE CAUSES:

11. THREE ELEMENT DRUM LEVEL CONTROL: 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 LOOP ARE 1. DRUM LEVEL 2. STEAM FLOW 3.FEED WATER FLOW and OUTLET STEAM PRESSURE FOR DENSITY CORRECTION TO DRUM LEVEL

12. BOILER F. WATER& STEAM FLOW

13. DENSITY ‘D’ CORRECTION: Head on LP = H * Da ( Da- Water Density @30*C) Delta p = HP – LP =Hm (Dw-Ds) – H (Da-Ds) Hm = {delta p + H (Da-Ds)} / (Dw-Ds) H-Hm Hm HP LP 0mm WC Dw WATER DENSITY Ds. STEAM DENSITY H D elta P Condensate Pot

14. THREE ELEMENT DRUM LEVEL CONTROL: STEAM FLOW SIGNAL IS USED AS A FEED FORWARD SIGNAL TO TAKE CARE OF THE SHRINK & SWELL EFFECT DRUM WATER LEVEL. F.W. AND STEAM SQ-ROOT SIGNALS ARE LENIARIESED AND FED TO FLOW-COMPUTOR

15. COMPUTED FORMULEA: DRUM LEVEL CONTROLLER OUTPUT+ STEAM FLOW SIGNAL- 50 % = REMOTE SET POINT FOR FEED WATER FLOW CONTROLLER HENCE FEED WATER FLOW CONTROLLER IS A CASCADE CONTROLLER. IT’S OUTPUT ACTUATES THE FEED FLOW CONTROL VALVE- F.V. TO FILL DRUM / TO MAKEUP DRUM LEVEL.

16. Temperature & Pressure Compensation for any compressible fluid like steam /air. THE EQUATION FOR COMPENSATION DONE AT FUNCTION BLOCK FX 704 IS AS GIVEN BELOW. ACTUAL STEAM FLOW:= INDICATED STEAM FLOW X SQRT{[(P1+1.209)*(485.0+273)]/[(66.0+1)*(T1+273)]} P1- MEASURED STEAM PRESSURE SIGNAL. T1- MEASURED TEMPERATURE SIGNAL DESIGN PRESSURE (CONSTANT) SAY, 66.0 KG/CM2 &. DESIGN TEMPERATURE (CONSTANT) 485.0 DEG C.

17. COMBUSTION CONTROL: INCLUDES: STEAM FLOW OUTLET STEAM PRESSURE O2 % IN FLUE GAS AND PRIMARY AIR FLOW FUEL CHARGING RATE. EXCEPT ‘DRUM LEVEL & FEED FLOW

18. FUEL FLOW CONTROLLER

19. Combustion Control

20. STEAM BOILER-AIR & FUEL FLOW

21. AN INCREASE IN FIRING RATE OF THE BOILER, WHEN IT DROPS; A DECREASE IN FIRING RATE,WHEN IT INCREASES, COMBUSTION CONTROL DOES THIS JOB OF ADJUSTING FIRING RATE BY WAY CONTROLLING FUEL & AIR . A CHANGE IN STEAM PRESSURE CAUSES:

22. THE STEAM HEADER PRESSURE SIGNAL IS FED TO THE MASTER PRESSURE CONTROLLER. STEAM FLOW SIGNAL IS FED AS A FEED FORWARD SIGNAL TO THE OUTPUT OF MASTER P.I. C TO COMPUTING BLOCK WHICH ADJUSTS THE OUTPUT w.r.to STEAM FLOW SIGNAL, WHICH IS DISTRIBUTED TO INDIVIDUAL RICE HUSK FEEDER#1 & RICE HUSK FEEDER#2 THROUGH THEIR RESPECTIVE AUTO-MANUAL STATIONS.

23. THE OUTPUT OF THESE INDIVIDUAL AUTO/MANUAL STATION ARE CONNECTED TO THE RESPECTIVE VARIABLE FREQUENCY DRIVE OF THE RISE HUSK FEEDERS TO CONTROL THE RISE HUSK FEED. FURTHER THE OUTPUT OF STEAM ‘P.I.C’ ALSO GOES TO THE AIR-FLOW CONTROLLER AS REMOTE SETPOINT. ON LINE O2 VALUE IS MEASURED BY ANALYSER AND O2 ‘A.I.C’ OUTPUT CORRECTS THE REMOTE SET POINT VALUE FOR AIR FLOW CONTROLLER IN COMPUTING BLOCK.

24. AIR FLOW MEASURED BY USING AEROFOIL WHOSE DIFFERENTIAL PRESSURE IS SENSED BY THE AIR FLOW TRANSMITTER SQ. ROOTED IS COMPENSATED TO THE AIR TEMPERATURE AT FUNCTION BLOCK. THE COMPENSATED AIR FLOW ACTS AS PROCESS VARIABLE TO. THE OUTPUT OF FIC POSITIONS THE FD FAN DAMPER ACTUATOR

25. 100% 0 150% 0 2 % STEAM LOAD 4 50% 2 O2 Vs STEAM FLOW CHART 6 5.5 4.2 4 4.7

26. 3. Steam Temperature Control. A WELL MAINTAINED STEAM TEMPERATURE HELPS IN ITS EFFICIENT USAGE DOWN STREAM EITHER TO DRIVE TURBINES OR AS A HEATING MEDIUM. CONSTANT TEMPERATURE MEANS CONSTANT SPECIFIC VOLUME, THERE BY CONSTANT PRESSURE ON TRANSMISSION OF STEAM THROUGH PIPE LINES. THE TEMPERATURE OF STEAM IS CONTROLLED BY ATTEMPERATION I.E. BY SPRAYING FEED WATER INTO THE STEAM AFTER THE SUPER HEATER.

27. HERE S.H I STAGE ‘TIC’ ACTS AS A FEED FORWARD CONTROLLER. ‘TI’ FIRST SENSES ANY VARIATION IN TEMPERATURE AND ‘TIC’ TAKES THE CORRECTIVE ACTION. WHATEVER DEVIATION IS PASSED ON TO, IS SENSED BY I STAGE & II STAGE ’TE’s AND II STAGE ‘TIC’ WILL TAKE THE CORRECTIVE ACTION BY CHANGING THE OUT PUT,- - THAT GOES AS REMOTE SETPOINT TO I STAGE S.H.‘TIC’ WHICH FURTHER CORRECTS THE TEMPERATURE.

28. THE TRANSFER SWITCH WHEN SELECTED, ENABLES THE OUTPUT OF T.I.C - -TO TRACK THE SIGNAL WHEN THE S.H. OUT LET TEMP. IS < THAN THE RATED TEMPERATURE, SO AS TO AVOID TIC SIGNAL GOING >100%. THE FEED WATER FLOW FOR ATTEMPERATION IS MEASURED & INDICATED IN ‘FI’. THE TOTALISER ‘FQ’ INDICATES THE TOTALISED FLOW.

29. 4. Furnace Pressure Control. IT IS ESSENTIAL TO MAINTAIN THE BALANCE BETWEEN FURNACE PRESSURE CAUSED BY COMBUSTION AND SUCTIONAL FORCE GENERATED BY ID/ EXHAUST FAN TO TAKE THIS FLUE GAS OUT OF BOILER. THE MEASURED SIGNAL IS FED TO PRESSURE CONTROLLER. THE OUTPUT OF CONTROLLER GOES TO THE I.D. FAN DAMPER ACTUATOR AND THE OPERATION OF ID FAN FINALLY CONTROLS THE FURNACE DRAFT. THIS LOOP CONCERNS WITH THE SAFETY OF BOILER& TO PREVENT FURNACE EXPLOSION OR BUCKLING

30. Deaerator Pressure & Level Control THE CONTENT OF DISSOLVED OXYGEN IN FEED WATER ESCAPES DURING BOILING AND OXEDISES /RUSTS THE INNER WALLS OF BOILER TUBES AND DRUMS. TO REMOVE THIS ‘ O 2 ’, WATER IS BOILED IN THE DEAIRATOR BEFORE FEEDING IN TO BOILER.

31. Deaerator Pressure & Level Control

32. THE HEATING STEAM PRESSURE IS MAINTAINED BY A CONTROLLER . IT’S OUTPUT ACTS ON THE DEAERATOR PRESSURE CONTROL VALVE . . TO MAINTAIN A CONSTANT LEVEL OF WATER INSIDE THE DEAERATOR IS A MUST FOR EJECTING OUT THE LIBERATED O 2 FULLY. A LEVEL CONTROL LOOP IS EMPLOYED USING A ‘LT’, ‘LIC’ AND ‘LCV’

33. Soot Blower Pressure Control. SOOT OR CARBON DEPOSITS WASTAGE OF FUEL & COMBUSTION LOSSES AND ESCAPING OF MORE HEAT TO ATMOSPHERE SO, FOR PERIODICAL REMOVAL OF DEPOSITS ON THE SAID PARTS, STEAM IN A CONTROLLED PRESSURE IS USED TO DE-DUST DRUM, W. TUBES, S.H. TUBES. ETC.

34. ‘ PT’ SIGNAL TO SOOT BLOWER PRESSURE CONTROLLER, MEASURES THE SOOT BLOWER PRESSURE. THE OUTPUT OF ‘PIC’ ACTS ON THE SOOT BLOWER PRESSURE CONTROL VALVE. ACTION OF SOOT BLOWER PRESSURE CONTROL VALVE IS AIR TO OPEN TYPE. FAIL- SAFE ACTION IS CLOSE.

35. Good Maintenance Management of Instruments Controls : IMPORTANT ASPECTS:  RECRUITMENT OF PROPER INSTRUMENTPERSONNALS TRAINING IN MODERN TECHNIQUES, ON SPECIALISED INSTRUMENTS CALIBRATION & TESTING FELICITIES AND METHODS.  DESIGNING AND EQUIPPING WITH A GOOD INSTRUMENT CALIBRATION ANDREPAIR SHOP WITH GADGETS KEEPING STOCK OF REQUIRED SPARES,

36. APART FROM ROUTINE MAINTENANCE, PREVENTIVE MAINTENANCE TO PREVENT LOSS OF PRODUCTIONS, BREAK DOWN LOSSES AND OTHER WASTAGE. PREDICTIVE MAINTENANCE SYSTEM , DERIVING THE BENEFIT OUT OF SCADA SYSTEMS AND ITS POTENTIAL TO GENERATE DETAILED ANALYSIS OF PLANT AND PROCESS RELATED EVENTS ON SCREEN.

37. ECONOMY AND SAFETY OFA NATION MUCH DEPENDS UPON GOOD MEASURING AND MONITORING SYSTEM IT EMPLOYS. Have a measure 0n every step To have total control On our target

38. REMEMBER : “ COUNTDOWN TO LAUNCH” IS ENSURED BY SAFE LOGIC CONTROLS!!

39. THANK YOU