Desirable as run information system for energy efficiency of utility class boilers

DESIRABLE as run INFORMATION SYSTEM NEEDS FOR ENERGY EFFICIENCY of UTILITY CLASS

BOILERS :

D.PAWAN KUMAR

For energy efficiency, a desirable as run information system on key thermal power station parameters may cover the following, to take care of reporting needs, as well as, as a powerful tool for management plans for energy cost optimization

DESIRABLE as run INFORMATION SYSTEM NEEDS FOR ENERGY EFFICIENCY of UTILITY CLASS BOILERS

Actual Gen. (MU)P L F (%) Av. Hrs for Generation Availability Factor (%)Av. GCV of Coal (kCal/kg)APC (MU) APC (%) Oil rate incl. start up (ml/kWh) Coal Rate (kg/kWh). Heat rate (kCal/kWh)

STATION PERFORMANCE PARAMETERS as run:

PAT/ORT/ERC target (MU)Av. Hrs for GenerationAvailability Factor (%)APC %P L F (%)Coal ConsumptionOil Consumption As fired GCV of Coal (kCal/kg)Oil rate incl. start up (ml/kWh) Coal Rate (kg/kWh). Heat rate (kcal/kWh) Thermal Efficiency (%)by heat loss method.

BOILER SYSTEM: RATED AND as-run PLANT PERFORMANCE PARAMETERS

BOILER PERFORMANCE PARAMETERS (Rated and as run VALUES)

Sl. No Performance Parameter Unit

1 Avg. Unit Load MW 2 % OF NCR % 3 Main Steam Flow TPH 4 Main Steam Pressure kg/cm2 (g) 5 Main Steam Temperature OC 6 Feed Water Temperature at FCV OC 7 GCV of Coal (as received basis) kCal/kg 8 Hot Reheat Steam Pressure Kg/cm2

9 Hot Reheat Steam Temperature OC 10 Cold Reheat Steam Pressure kg/cm2

11 Cold Reheat Steam Temperature OC12 G C V OF COAL (as fired basis) kCal/kg 13 TOTAL AIR FLOW TPH 14 GC V OF CARBON kCal/kg 15 BOTTOM ASH QTY. kg/kg 16 COMB. IN BOTTOM ASH % 17 COMB. IN FLY ASH % 18 FLY ASH QTY. kg/kg

BOILER PERFORMANCE PARAMETERS (Rated and as run VALUES) continued…

Sl. No Performance Parameter Unit

19 Flue gas analysis (APH Out) 19.1 CARBON DIOX!DE (CO2) % 19.2 CO % 19.3 OXYGEN (O2) % 19.4 TEMPERATURE Deg C 20 Ambient air parameters 20.1 DRY BULB TEMP Deg C 20.2 WET BULB TEMP Deg C 20.3 RELATIVE HUMIDITY % 20.4 MOISTURE LOAD kg/kg 21 Proximate analysis of Coal

21.1 FIXED. CARBON %

21.2 VOLATILE MATTER %

21.3 TOTAL MOISTURE %

21.4 ASH %

21.5 G C V OF COAL (as fired basis) kCal/kg

22 Ultimate analysis of Coal

22.1 CARBON (C) %

22.2 HYDROGEN (H) %

22.3 SULPHUR (S) %

22.4 TOTAL MOISTURE (H2O) %

19.3 OXYGEN (O2) %

19.4 TEMPERATURE Deg C

AS RECEIVED AND AS FIRED COAL QUALITY (AVG. VALUES):(Deviation between as received and as fired to be minimal)

Inherent Moisture (%)Total Moisture (%)Ash (%)VM (%)Total Carbon (%)Fixed Carbon (%)Hydrogen (%)Sulphur (%)GCV (kCal/kg)

FLUE GAS as run ANALYSIS (AVG. VALUES)

%O2 at APH inlet

%O2 at APH outlet

%O2 at ID fan inletDiff. pressure on gas side across APH(mmwc)Flue gas temperature at APH inlet (OC)Flue gas temperature at APH outlet (OC)Secondary air temperature at APH outlet (OC)% Differential O2 APH to ID fans inlet

COAL FINENESS _ as run

BEFORE AND AFTER CRUSHER SIEVE ANALYSIS BEFORE MILL SIEVE ANALYSIS MILL OUTPUT ANALYSIS as run : 50 Mesh100 Mesh150 Mesh200 Mesh

TURBINE SYSTEM as run PARAMETERS:

TURBINE CYLINDERS: HPT I/L (MS) pressure (kg/cm2)HPT I/L (MS) temp. (0C)CRH Steam pressure (kg/cm2)CRH Steam Temperature (0C)HRS Steam pressure / IP inlet (kg/cm2)HRS Steam Temperature (0C)IPT Exhaust / LPT inlet pressure (kg/cm2)IPT Exhaust / LPT inlet temperature (0C)LPT Exhaust pressure (kg/cm2)LPT Exhaust temperature (0C)

HP HEATERS as run parameters:HP Heater Extraction pressureHP Heater Extraction TemperatureHP Heater drip pressureHP Heater drip TemperatureTTD and DCA

LP HEATERS as run parameters:LP Heater Extraction pressureLP Heater Extraction TemperatureLP Heater drip pressureLP Heater drip TemperatureTTD and DCA

CONDENSATE as run PARAMETERS:Condensate pressure at HP Heater inletCondensate temperature at HP Heater inletCondensate pressure at HP Heater outletCondensate temperature at HP Heater outletCondensate pressure at LP Heater inletCondensate temperature at LP Heater inletCondensate pressure at LP Heater outletCondensate temperature at LP Heater outletCond. Vacuum

CONDENSATE EXTRACTION PUMPS as run PARAMETERS (CEP):CEP Suction side pressureCEP Suction side temperatureCEP Discharge header pressureCEP Discharge header temperature

DE AERATORSDe aerator pressureDe aerator feed water temperature

CONDENSER SYSTEM as run :Sl. No.

DESCRIPTION UNITS Nomenclature

1 Condenser Back Pressure (Vacuum) mbar absolute

2 CW Inlet Temp. (Left) °C t1L

3 CW Inlet Temp. (Right) °C t1R

4 CW Inlet Temp. (L/R-avg) °C ( t1 )

5 CW Outlet Temp. (Left) °C ( t2L )

6 CW Outlet temp. (Right) °C ( t2R )

7CW Outlet Temp.

(L/R-avg)°C ( t2 )

CONDENSER SYSTEM as run PARAMETERS:

Sl. No.

DESCRIPTION UNITS Nomenclature

8 CW Temp. rise (avg) °C ( t2 – t1 )

9 Saturation Temp °C ( T )

10 Terminal Temperature Difference (TTD) °C (T – t2)

11Saturation and inlet temperature difference

°C (T-t1)

12 Condenser Effectiveness Factor

13 DP Across Condenser (L) mwc

14 DP Across Condenser (R) mwc

15DP Across Condenser

(L/R-avg)mwc

16 Condenser CW flow M3/hr

17 LMTD °C

18 Condenser Thermal Load MkCal/hr

1

12

tT

tt

AUXILIARIES POWER CONSUMPTION:

Overall Auxiliary Power Consumption MU %

Total Generation: Year

Auxiliary Power Consumption 100

Unit Key Auxiliaries MU %BFP's

CW Pumps

ID Fans

PA Fans

Coal Mills

CEP's

FD Fans

RATED AND as run PARAMETERS OF BOILER FEED PUMPS (BFPs):Unit Load (MW)Frequency (Hz)Suction flow (TPH)BFP flow (TPH)Suc. Pressure (kg/cm2)Dis. Pressure (kg/cm2)Total Dev Head (kg/cm2)Total Dev Head (TDH) (mwc)Suction Temp. (0C)Density (kg/m3)BFP (motor input) (kW)Scoop position (%)% Loading on motor% Loading on flow%Recirculation% Loading on HeadSp. Energy Consumption (kWh/T)Efficiency %FRS pressure drop

RATED AND as run PARAMETERS OF ALL CONDENSATE EXTRACTION PUMPS (CEP):

Unit Load (MW)Frequency (Hz)CEP flow (TPH)Suc. Pressure (Cond. Back Pr.) (kg/cm2)Dis. Pressure (kg/cm2)Total Dev Head (kg/cm2)Total Dev Head (TDH) (mwc)Suction Temp. (0C)Density (kg/m3)CEP (motor input) (kW)% Loading on motor% Loading on flow% Loading on HeadSp. Energy Consumption (kWh/T)Efficiency %

RATED AND as run PARAMETERS OF ALL CIRCULATING COOLING WATER (CW) PUMPS:

Unit Load (MW)Frequency (Hz)CW pump flow (TPH)Suc. Pressure (mwc)Dis. Pressure (kg/cm2)Total Developed Head (kg/cm2)Total Developed Head (TDH) (mwc)CW pump (motor input) (kW)% Loading on motor% Loading on flow% Loading on HeadSp. Energy Consumption (kWh/T)Efficiency %CW Bypass valve condition

RATED AND as run PARAMETERS OF ALL INDUCED DRAFT (ID) FANS:Unit load (MW)Frequency (Hz)FGT at ID inlet (0C)Density (kg/m3)Avg. Suction Press. (mmwc)Avg. Discharge Press. (mmwc)Total static head developed (mmwc)FG Quantity handled (CMS)kW of ID fan motors (kW)Scoop position (%)Or IGV open (%)% Loading on motor% Loading on flow% Loading on HeadSp. Energy Consumption (kWh/T)Efficiency %% Oxygen difference across APH inlet and ID fan inlet

RATED AND as run PARAMETERS OF ALL FORCED DRAFT (FD) FANSUnit load (MW)Frequency (Hz)Suction temperature (0C)Density (kg/m3)Avg. Suction Press. (mwc)Avg. Discharge Press. (mwc)Total static head developed (mwc)FD air flow (TPH)kW of FD fan motors (kW)IGV/Damper open (%)% Loading on motor% Loading on flow% Loading on HeadSp. Energy Consumption (kWh/T)Efficiency %

RATED AND as run PARAMETERS OF ALL MILLSUnit load (MW)Frequency (Hz)Secondary air temperature(deg C)Mill outlet temperature (deg C)Mill differential pressure (mmwc)Coal flow (TPH)Air flow (TPH)Coal sieve analysis (mill inlet)Coal fineness at mill outlet(passing on 200 mesh)Motor input kW% Loading on motor% Load on coal outputSp. Energy Consumption (kWh/T)Mill rejects %

RATED AND as run PARAMETERS OF ALL PRIMARY AIR (PA) FANS:Unit load (MW)Frequency (Hz)Suction temperature (0C)Density (kg/m3)Avg. Suction Press. (mmwc)Avg. Discharge Press. (mmwc)Total static head developed (mmwc)PA air flow (CMS)kW of PA fan motors (kW)% Loading on motor% Loading on flow% Loading on HeadSp. Energy Consumption (kWh/T)Efficiency %

RATED AND as run PARAMETERS OF ALL STATION AUXILLIARIES:COOLING TOWERS (CT):Unit load (MW)Frequency (Hz)Hot well temperature (0C)Cold well temperature (0C)DBT & WBT at CT fan outletDBT & WBT at ambient.CT fan flow (CMS)Blade angle settingCT effectiveness %Cycles of concentrationCT approach

PLANT and INSTRUMENT AIR COMPRESSOR PARAMETERS:

FAD test:Initial pressure at receiver (kg/cm2)Final pressure at receiver (kg/cm2)Receiver + pipe volume (M3)Time taken from initial pressure to final pressure (Min)Compressor motor input power (kW)Sp. Energy Consumption (kWh/M3)Compressor efficiency

COAL HANDLING PLANT (CHP) PARAMETERS:

Plant running hrsCoal Qty handled (TPH)Direct Bunkering %Stacking & Reclaiming %% Capacity UtilizationOverall unit consumption (CHP)Overall Sp. Energy Consumption (kWh/T)

ASH HANDLING PLANT (AHP):Unit-wise ash generation(TPH)Average Ash- Water RatioOverall unit consumption (AHP)Sp. Energy Consumption (kWh/T of ash)

OTHER KEY PARAMETERS:Make-up water consumption in each unit as %:Blow down % in each unit:Number of soot blowers installed and actually operational:Number of LP heaters operational:Number of HP heaters operational: number of unit trippings due to boiler tube leakages and other reasons:Mill outage hours:Oil gun hours:

ENCON OPTIONS TO BE TAPPED, BASED ON MIS PARAMETERS1. High Pressure Turbine Efficiency

A. Effect on Heat Rate (per percentage points):•0.2 % of Unit Heat rate or 5 kcal/kWh for a unit with a HR of 2500 kcal/kWh.B. Possible Causes of Deviation•Erosion of nozzle blocks•Erosion of turbine blades•Deposits of nozzles or blades•Broken turbine blades•N2 packing leak (HP and turbine are in the same shell)•Excess gland packing leaks•Strip Seal leakage•Malfunctioning Control Valve

C. Possible Corrective Measures

•Repair or replace nozzle block•Repair or replace turbine blades•Clean turbine blades•Replace gland packing•Replace turbine seal strips

ENCON OPTIONS TO BE TAPPED, BASED ON MIS PARAMETERS

2. Intermediate Pressure Turbine EfficiencyA. Effect on Heat Rate (per percentage point):•0.2% of unit Heat rate or 5 kCal/kWh for a unit with a HR of 2500 kCal/kWh.B. Possible Causes of Deviation•Erosion turbine blades•Deposits on turbine blades•Reheater bypass valve leakage•Excess Gland Seal leakage•Strip seal leaksC. Possible Corrections•Repair or replace turbine blades•Repair leaking reheater bypass valve•Repair strip seal•Repair gland seals


3. Main Steam (Throttle) PressureA. Effect on Heat Rate (per kg/cm2)

•1 kCal/kWhB. Possible Causes of Deviation

•Feed water flow too low (once-through units)•Firing rate inadequateC. Possible Corrections

1. Operator Controllable•Increase feed water flow•Increase firing rate


4. Main Steam (Throttle) TemperatureA. Effects on Heat Rate (per deg C)• 0.5 kCal/kWh B. Possible Causes of Deviation•Super heater spray control problems•Super heater spray valve leakage•Fouling of the super heater (low temperature)•Fouling of the boiler water wall (high temperature)•High excess air•Burner tilts mispositioned•Gas tempering flow inadequate•Bypass dampers mispositioned•Temperature control setting calibration drift•Super heater tube leaks•Incorrect amount of super heater heat transfer surface


C. Possible Corrections•Blow soot•Adjust burner tilts•Adjust bypass damper settings•Control excess air•Manually control super heater spray flow•Calibrate temperature control set point•Repair super heater spray control valve•Clean boiler water walls•Clean super heater platens•Repair super heater tube leaks•Add or remove super heater heat transfer surface


5. Reheat TemperatureA. Effect on Heat Rate (per deg C)•0.5 kCal/kWhB. Possible Causes of Deviation•Reheat Attemperation control problems•Reheat Attemperation control valve leakage•Fouling of the reheater (low temperature)•Fouling of the boiler water wall (high temperature)•Fouling of the super heater•High excess air•Burner tilts mispositioned•Gas tempering flow inadequate•Bypass dampers mispositioned•Reheater tube leaks•Incorrect amount of reheater heat transfer surface


C. Possible Corrections•Blow soot•Adjust burner tilts•Adjust bypass damper settings•Adjust attemperating air flow damper•Control excess air•Manually control reheat spray flow•Repair super heater spray control valve•Clean boiler water walls•Clean super heater platens•Clean reheater platens•Repair reheater tube leaks•Add or remove reheater heat transfer surface


6. Super heater AttemperationA. Effect on heat rate (for 10 t/hr flow rate):• 0.25 kcal/kWhB. Possible Causes of Deviation•Improperly adjusted control set point•Leaking spray control valve•Broken spray nozzle•Fouling of boiler water walls•High levels of excess air•Improperly set gas attemperation•Improperly set gas bypass dampers


C. Possible Corrections•Blow water wall soot•Reduce excess air to proper levels•Adjust gas attemperation•Adjust gas bypass dampers•Repair spray valves•Calibrate temperature controls•Replace spray nozzle


7. Reheat attemperation 1. Effect on heat rate (per 1% of MS flow):•2.5 to 3.5 kCal/kWhB. Possible causes of Deviation•Fouled water walls•High levels of excess air•Fouled super heater sections•Improperly set gas bypass dampers•Improperly spray control valve•Broken spray nozzleC. Possible Corrections•Adjust gas bypass dampers•Adjust excess air to proper levels•Soot blow water walls•Soot blow super heater sections•Repair spray control valves•Replace spray nozzles•Calibrate temperature control set point


8. Condenser Backpressure A. Effect on heat rate (per 1 mm Hg)•2 kCal/kWh B. Possible causes of Deviation•Air leakages•Excess condenser load•Tube fouling•Low circulating water flow•Increases in circulating water inlet temperature•Changes in ambient conditions•Problems with cooling tower performance C. Possible Corrections•Increase circulating water flow•Add an additional vacuum pump•Check cycle isolation•Place additional circulating water pumps in service•Place additional cooling tower cells in service


9. Auxiliary Power Consumption A. Effect on Heat Rate (per percentage point):• 20 kCal/kWh B. Possible Causes of Deviation•Continuous running of non continuous loads•Decline in efficiency of operating equipment•Operation of redundant equipment during low-load operation C. Possible Corrections•Stop non-continuous loads•Reduce equipment operation at low loads•Repair or replace inefficient equipment•Maintain equipment whose power usage increases with deteriorating performance, e.g., electrostatic precipitators, pulverizes, etc.


10. Make up Water Consumption A. Effect on heat rate (per percentage point):•6 kcal/kWhB. Possible Causes of Deviation•Boiler tube leaks•Excess deaerator venting to atmosphere•Excess continuous blow down•Excess steam lost through condenser venting•Valve packing leaks•Pump seal leaks•Steam leaks to atmosphereC. Possible Corrections•Check deaerator vent orifices or valve settings•Repair valve and pump packing and seals•Repair boiler tube leaks•Optimize continuous blow down•Isolate cycle losses


11 . Feed water Heater PerformanceA. Effect on Heat Rate: 1. TTD (per deg C):• 1.8 kCal/kWh 2. DCA (per deg C)• 0.2 kCal/kWh3 High Pressure Heaters Out of Service:• First Heater: 23 kCal/kWh• Second Heater: 17 kCal/kWh• Third Heater: 17 kCal/kWh4 Heater out of service 0.67 kCal/kWh for every 1DegC feed water

heating lost B. Possible Causes of Deviation:•Changes in heater level•Changes in extraction line pressure drop•Reduced condensate flow through the heater•Heater baffle leaks•Failure to vent noncondensible gases•Tube fouling


C. Possible Corrections• Set feed water heater levels•Optimize feed water heater levels•Maintain heater vent valves and line orifices•Repair baffle leaks•Clean tube bundles

12. Startup A. Effect on heat rate:•1.85 kcal/kWh B. Possible Causes of Deviation•Forced outages•Unscheduled outagesC. Possible Corrections•Eliminate unscheduled outages through effective predictive and preventive maintenance.


13.OTHER GENERIC OPTIONS :•Upkeep of cooling tower fills to be in order.•Thermal insulation of boiler surfaces to be in order.•Makeup water consumption to be controlled to less than 3%•Differential oxygen between air preheater inlet and ID fan inlet to be limited to 3 %.•TTD of feed heaters to be maintained around 3 deg C•FRS pressure drop to be maintained as low as feasible.•Recirculation of feed water to be avoided in BFP circuit.•If part loading is necessitated often, option of variable frequency drives for key auxiliary drives may be considered.•Direct bunkering rather than stacking reclaiming route is desirable in CHP.•Mill loading/capacity utilization to be close to rating.•Mill inlet coal size to be ensured close to design value.•CHP loading to be preferably above 50 %•Ash water ratio to be maintained closer to design value.•Water balance to be carried out often to optimize water consumption.-

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Desirable as run information system for energy efficiency of utility class boilers