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“You cannot Manage what you cannot Measure” (Accurately) - Jack Welch, CEO, General Electric

PRESENTATION ON ENERGY AUDITS IN THERMAL POWER STATION BY H.S.Bedi Sr. Vice President (Power) Energo Engineering Projects Ltd. A-57/4, Okhla Industrial Area, Phase – II, New Delhi - 110020. “You cannot Manage what you cannot Measure” (Accurately) - Jack Welch, CEO, General Electric.

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“You cannot Manage what you cannot Measure” (Accurately) - Jack Welch, CEO, General Electric

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  1. PRESENTATION ON ENERGY AUDITSIN THERMAL POWER STATIONBY H.S.BediSr. Vice President (Power)Energo Engineering Projects Ltd.A-57/4, Okhla Industrial Area,Phase – II, New Delhi - 110020

  2. “You cannot Manage what you cannot Measure” (Accurately) - Jack Welch, CEO, General Electric

  3. PATTERN OF ENERGY CONSUMPTION INTHERMAL POWER STATION

  4. TYPICAL PLANT LOSSES

  5. TYPICAL BOILER LOSSES

  6. TYPICAL CYCLE LOSSES

  7. 1.0 USEFULNESS OF ENERGY AUDIT IN THERMAL POWER STATION • Identifies Wastage areas of Fuel, Power and Water & Air Utilization. • Reduction in cost of generation by implementing findings of EA. • Increases power generation by efficient utilization of steam in turbine cycle and reduction in Aux Power Consumption. • Maintenance planning and availability improvement. Contd …

  8. Provides guidance in Loading Sequences of the Units. • Identification and Rectification of errors in on-line Instruments. • Leads to reduction in Green House Gases. • Utilizes specialized services of experienced Engineers. • Training of O&M staff for Efficient Control of Unit Operation. 1.0 USEFULNESS OF ENERGY AUDIT IN THERMAL POWER STATION Contd …

  9. 1.0 USEFULNESS OF ENERGY AUDIT IN THERMAL POWER STATION • Improves competitiveness by reducing unit generation. • Creates bench mark for all equipments and systems. • Fulfills bureau of energy efficiency mandatory requirement of Energy Audit.

  10. EFFECT OF INSTRUMENTATION ON ENERGY AUDITS • Plant on-line instruments with few audit instruments Accuracy around 3.0%. • Accurate calibrated instruments as per ASME-PTC-6 for steam turbine& ASME-PTC-4-1 for Boilers. • Accuracy around 0.5 % • ERROR OF PROCEDURE OF ENERGY AUDIT OTHER THAN • ASME-PTC-6 for steam turbines and ASME – PTC-4.1 for boiler • Error in Boiler Energy Audit – around 2.0% • Error in steam turbine Energy Audit – around 3.0% • Total error because of Instrumentation & Procedure 6.0% Contd….

  11. IMPORTANCE OF ACCURACY IN ENERGY AUDITS • 1.0% Deviation in findings means 25000 tons of coal loss/annum for 200 MW Unit or approx Rs. 5 crores / year (4000Kcal coal GCV & Rs.2000/ton coal cost) • Difference in cost of Energy Audit between B & A is 12 to 14 lacs as against 6 to 8 lacs.

  12. ECONOMIC ASPECTS OF INEFFICIENT MACHINES (200 MW) • NOTE: • TG CYCLE HEAT RATE IS TAKEN AS 2000 KCAL / KWh • COAL CV IS TAKEN AS 4000 KCAL / Kg • PRICE OF COAL TAKEN AS Rs. 2000 / TON • LOSS INCREASES WITH MACHINE SIZE

  13. Impact of Turbine Efficiency on HR/Output Description Effect on Effect on TG HR KW 1% HPT Efficiency 0.16% 0.3% 1% IPT Efficiency 0.16% 0.16% 1% LPT Efficiency 0.5 % 0.5 % Output Sharing by Turbine Cylinders are around HPT 28% IPT 23% LPT 49%

  14. HP/IP Turbine Efficiency Instrument Inaccuracy / lack of corrections

  15. Effect of Condenser Vacuum on Heat Rate 10 MM HG IMPROVEMENT IN CONDENSER VACUUM LEADS TO 20 Kcal/kwh (1%) IMPROVEMENT IN HEAT RATE FOR A 210 MW UNIT

  16. EFFECT ON HEAT RATE FOR PARAMETER DEVIATION (500MW UNIT)

  17. Instrument calibration interval Calibration intervals should be based on the Specifications given by OEM / trended calibration observations. An example of Accuracy degradation as a function of time is: 06 mth 12 mth 18 mth 24 mth Accuracy 0.2 0.2 0.2 0.2 (% of span) Repeatability) 0.05 0.05 0.05 0.05 (of calibrated span) Drift (@06months) 0.1 0.2 0.3 0.4 Overall Instrument 0.30 0.40 0.50 0.60 accuracy

  18. CONFORMITY FOR ENERGY AUDITS FOLLOW TEST CODES • ASME PTC - 6 For Steam Turbines ASME PTC - 4.1 for Boilers CALIBRATION LAB • Govt. Accredited i.e. NABL Labs TEST SCHEME • To be Furnished And Approved Sample enclosed

  19. BOILER EFFICIENCY • HEAT LOSS METHOD • BOILER EFFICIENCY = 100 - % AGE LOSSES • Heat Loss in Dry flue gas • Hg = 0.24 wg (Tg – Ta) as percentage of heat input • G.C.V • Hg = K (Tg – Ta) /1.8 K=0.32 for fuel oil • % CO2 in flue gas K=0.35 for Bituminous coal • Heat loss due to evaporation of moisture & H2 in fuel • Hm = Wm+9H (100 – Tf) + 540 – 4.6 (Tg -100) %of heat input • G.C.V • Heat loss due to moisture in air • Ha = 0.26 Wma (Tg – Ta) % of heat input • G.C.V • Heat loss due to Incomplete combustion to Co • Hco = 2414 C x CO x 1 as % of heat input • CO+CO2 G.C.V • Heat loss due to unburnt carbon “C” • Hc = Wc x 7831 as % of heat input • G.C.V

  20. Heat loss due to Blow Down • Hbd = Wb (hbw – hw) as % of heat input • G.C.V • Heat loss due to Radiation • HR = Difficult to evaluate & thus take design values only • In above • Wg =Wt of dry flue gas • W..G = [44.01 *CO2 + 32*O2 28.02 * N2 + 28.01*CO]*[Cb + 12.01 * S/32.07] • 12.01 * (CO2 + CO) • Tg = Tempt. Of flue gas at exit of Boiler • Ta = Tempt. Of air at inlet (ambient) • Tf = Tempt. Of fuel inlet • hbw-hw = Heat in blow down • Wm = Weight of moisture • Wma = Wt of waterin Kg/Kg of air X Wt of air in Kg supplied / Kg of fuel • Wc = Weight of unburnt “C” • Wb = Wt of water blow down • All wts are / kg of fuel

  21. FG Expansion Bellow Economizer HVS APH Sampling Locations APH FG

  22. Annexure - I BOILER EFFICIENCY AND APH TEST SCHEME & INSTRUMENTATION DIAGRAM Grid measurement for gas compositionand gas temp. at air pre heater inlet / outlet. DEPTH

  23. D = Duct Depth (Internal) W = Duct Width (Internal) Tx = Traverse (x) (Pockets) x =1 to 5 (Width wise) Nxy = Nodexy (Sketch for one half of flue gas duct cross - section) Grid measurement for gas sampling and temperature measurement at 3 to 5 locations on APH inlet & at 3 to 5 locations on APH outlet ducting as close to APH as possible shall be taken provided test pockets are available for inserting sampling probes. Flue gas sampling and temperature measuring probe shall be inserted at each location and traversed to collect data at these points in each location. This shall eliminate effect of gas stratification. Air temperature at inlet and outlet of APH shall be measured at two points each in case spare pockets are available. Ambient temperature, barometric pressure & RH is measured near F.D. fans. Note1 : WBPDCL to provide the test pockets in each of the Air and Gas path for inserting test instrument. Note2 : Test instruments shall be used for the above.

  24. b) Turbine cycle heat rate. • This varies with the system changes in cycle i.e. • Location of Aux. Stm. Tapping. • Whether Reheater spray is reqd. or not. • Whether spray for superheaterattemperation is tapped off from BFP discharge or after top heater. • Cycle with Aux. Steam from MS or No Aux. Stm.; • No. RH Spray, ; • H. Rate = M1 (H1 – hF) + M2 (H3 – H2 ) • Pg • Same as (a) but Aux. Steam from CRH • H. Rate = [M1 (H1 – hF) + M2 (H3 – H2) – MAS (H3 – Hc )] • Pg • Same as (a) but with Reheat Spray. • H. Rate = M1 (H1 – hF) + M2 (H3 – H2) + MRHS (H3 – hRHS ) • Pg • Same as (a) but Spray for Superheater from BFP discharge • H. Rate = M1 (H1 – hF) + M2 (H3 – H2) + MSHS (hF – hSHS ) • Pg

  25. ENERGY AUDIT SCHEME FOR 210 LMW STEAM TURBINE

  26. PERFORMANCE TEST PROCEDURE FOR PUMPS Total dynamic head at test speed N H = (PD – PS) X 10 / W MLC Total dynamic head at design speed N1 H1 = HX (N1 / N)2 MLC Fluid flow at design speed N1 Q1 = QX (N1 / N) M3 / Hr Based ion characteristic curve of the pump the expected flow Q2M3 / Hr shall be worked out at H1MLC of total dynamic head (TDH) CONCLUSION For Normal Pump performance Q1M3 / Hr should be more than or equal to Q2 M3 / Hr Q1> Q2

  27. FREQUENCY OF READINGS FOR ACCURATE DATA COLLECTION TURBINE CYCLE AUDIT Pressure - 5 Minutes Temperature - 5 Minutes Flow - 1 Minute Power - 1 Minute Levels - 10 Minutes BOILER UNIT AUDIT Temperature - 15 to 30 Minutes Flue Gas Composition - ½ to one hour DURATION OF AUDIT TEST Turbine Cycle - 2 Hrs Boiler Unit - 4 Hrs

  28. TEST INSTRUMENTS ACCURACY, CODE & CALIBRATION LAB Accuracy of Energy Audit Instruments • Pressure Measuring Instruments 0.1 % Acc. • Temperatures 1/2 DIN Tolerance Or ASME CLASS ‘A’ • Aux. Power Measuring Instruments 0.2 % Acc. • Generator Power Measurement 0.1 % Acc. • Flue Gas Analysis 0.5 % Acc. • Data Logger 0.03 % Acc. • Ultrasonic Flow Meter 0.5 % Acc. Note: - Price and Quality / Grade of Energy Audit Depends largely on Instrument Accuracies

  29. 3.0 METHODOLOGY TO BE ADOPTED FOR ENERGY AUDIT • 3.1 INTERACTION WITH PLANT ENGINEERS AND OBTAIN DATA ON • Various equipment problems. • Present performance level i.e. unit heat rate, fuel consumption, DM Water and raw water consumption etc. • Plant design data for the main and auxiliary equipments. • Boiler TG Cycle layout, condensate, feed and steam pipe line schematics. • Performance / Guarantee test reports of the tests carried out on equipments. • Plant electrical power distribution system and transformer etc

  30. Auxiliary power distribution system and transformer etc. • Evaluation procedure for day to day monitoring i.e. plant M.I.S. systems • Loading / requirement during test. • 3.2 Follow enclosed Test scheme for boiler and turbine testing. • 3.3 Develop Energy Audit procedure covering following for each equipment • Object of energy audit • Scheme and list of measurements • Range, make & class of accuracy of instruments.

  31. Frequency of instrument readings. • Duration of instrument readings. • Required man power. • Interconnected plant data required. • Finalize procedure with customer / consultants • 3.4 CHECK UP THE AVAILABILITY OF INSTRUMENT • MOUNTING POINTS AND ORGANIZE FOR MISSING • POINTS. (CUSTOMER TO ARRANGE OR SPARE • ALTERNATE POINTS) • 3.5 ARRANGE CALIBRATED INSTRUMENTS. • 3.6 PLAN SCHEDULE OF ACTIVITIES FOR ENERGY • AUDIT.

  32. 3.7 Customer to Arrange shutdown if required for providing non available / missing points and attending defects noticed during walk down survey. 3.8 Conduct test as per above plan. 3.9 Prepare preliminary energy audit report. 3.10 Evaluate Final Results. 3.11 Conduct mass and energy balance in Turbine cycle components and boiler.

  33. 3.12 Make comparison with design Acceptance test data and establish shortfall areas. 3.13 Furnish recommendations in the form of cost benefit analysis. 3.14 Give presentation on findings with backup data

  34. SCOPE FOR CONSULTANT • Frame SPECS for Energy Audits • Approve Energy Audit Schematics • Approve Procedure Covering Evaluation Procedure, Type and Class of Accuracy of Instruments & their Calibrations • Installation of Instruments and Ensure Compatibility of Data Thermodynamically • Supervise Conductance of Energy Audit • Review & Acceptance of Audit Report

  35. SCOPE OF WORK FOR ENERGY AUDIT OF THERMAL POWER PLANT UNITS • Energy Audit should cover evaluation of the present performance level of all major equipments, identify the controllable losses and suggest remedial measures for improvements with cost benefit analysis and pay back period. The detailed scope of work covering the following is given as under. • Boilers • Turbine including regenerative cycle and condenser • Electrical system • Fans and Pumps in the above areas • Insulation • Balance of Plant including Station auxiliaries power consumption, Coal Handling plant, ash handling system, DM Plant, Station Compressed air system, CW system and Air conditioning.

  36. Preliminary Energy Audit, Preliminary Checking / Hot walk downEnergy Auditing agency to check the complete unit steam, condensate and feed water system along with the functioning of Heat cycle equipment like Boiler, Condenser Regenerative system Turbine Cylinders etc. during HOT WALK DOWN. Problem if any, shall be brought to the notice of the authority for rectification and arranging provisions for mounting audit instruments during Audit Preparatory Activities, prior to start of the detailed EA.

  37. A Energy Audit Of BoilersPerformance of Boiler and APH be established by measuring exit flue gas temperature and its analysis at around nine to fifteen points in flue gas duct cross section before and after APH to eliminate effect of gas stratification as per international practice (Refer enclosed boiler test scheme Annexure – I). This is because boiler efficiency differs by around 2.0% by this method than if the measurements are taken at single point. Scope will include the following DETAILED ENERGY AUDIT • Conduct boiler efficiency measurements as per above test scheme by indirect method i.e heat loss method, evaluate Boiler efficiency and identify potential areas for improvements such as.

  38. Heat loss due to heat in dry flue gas. Heat loss due to moisture in as fired fuel. Heat loss due to moisture from burning of hydrogen in fuel Heat loss due to moisture in air. Heat loss due to surface radiation and convection. Heat loss due to formation of carbon monoxide. Heat loss due to combustibles in bottom and fly ash Check up air ingress in boiler from LTSH area downwards upto I.D fans.

  39. Determine Air preheater performance to establish. • Gas Side Efficiency – As ratio of gas temperature drop corrected for no air leakage to temperature heads. • Air leakage as percentage of air passing from airside to gas side. • X-Ratio I,e heat capacity of air passing through the air heater to the heat capacity of gas passing through the air heater. • Air side and gas side pressure loss across the air heater. • Input power measurement of ID FANS / FD fans, PA fans, Fan Loading & combined efficiency of fan and motor and their specific power consumption • Energy Audit test has to be carried out for four hours by recording parameters at every 15 minutes and average of data to be utilized for evaluation.

  40. B Energy Audit of steam turbine cycle and it auxiliaries For Energy Audit of steam turbine cycle, all the parameters as per the enclosed scheme in Annexure – II are to be measured simultaneously by hooking up these calibrated instruments to a data logger. The recording has to be at least for a minimum period of two hours with each measurement being recorded at an interval of one minute. Average of the data so collected to be utilized for evaluation of the following and suggestions for deficient areas for improvements to be made. Turbine cycle heat rate. HP and IP cylinders efficiency Turbine pressure survey

  41. TTD & DCA of HP / LP heaters performance • Condenser performance i.e • Condenser back pressure after duly considering the effect of present C.W inlet temp. C.W flow, heat load on condenser and air ingress to condenser vis-à-vis design conditions • C.W side pressure drop in condenser • Cycle losses • Performance of turbine glands • Ejector performance

  42. For accurate heat rate determination, Turbine inlet flow and reheat flow need to be evaluated as per international practice by measuring condensate flow through measurement of ∆p of plant condensate flow orifice after checking its condition and using evaluated drip and extraction to deaerator flows through heat and mass balance across heaters and deaerator as per scheme. Fall in deaerator level and HPTV and IPV leak off flow are also considered. Alternately by mass balance across deaerator if flow orifices are installed in drip and extraction lines to deaerator. Deaerator outlet feed flow shall then be taken as the main steam flow after considering for RH spray tap off from Boiler feed line.

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