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

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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
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You cannot Manage what you cannot
Measure (Accurately) - Jack Welch, CEO,
General Electric
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PATTERN OF ENERGY CONSUMPTION INTHERMAL POWER
STATION
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TYPICAL PLANT LOSSES
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TYPICAL BOILER LOSSES
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TYPICAL CYCLE LOSSES
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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
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1.0 USEFULNESS OF ENERGY AUDIT IN
THERMAL POWER STATION

• 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 OM staff for Efficient Control of
  Unit Operation.

Contd
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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.

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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.
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• 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.

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ECONOMIC ASPECTS OF INEFFICIENT MACHINES (200 MW)
SHORT FALL LOSS IN CRORES PER ANNUM
TURBINE CYCLE HEAT RATE 1.0 5.0
TG OUTPUT 1.0 5.0
BOILER EFFICIENCY 1.0 1.75
AUX. POWER CONSUMPTION 5.0 2.5

• 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

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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
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HP/IP Turbine Efficiency
Instrument Inaccuracy / lack of corrections
HPT Efficiency Main Steam Main Steam HPT Exhaust HPT Exhaust
HPT Efficiency Pressure Kg/cm2 Temp Deg C Pressure Kg/cm2 Temp Deg C
HPT Efficiency 1 1 1 1
HPT Efficiency 0.6 0.6 2.0 0.7
IPT Efficiency IPT Inlet IPT Inlet IPT Exhaust IPT Exhaust
IPT Efficiency Pressure Kg/cm2 Temp Deg C Pressure Kg/cm2 Temp Deg C
IPT Efficiency 1 1 1 1
IPT Efficiency 1.2 0.3 6.0 0.4
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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
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EFFECT ON HEAT RATE FOR PARAMETER DEVIATION
(500MW UNIT)
DEVIATION IN PARAMETER EFFECT ON HEAT RATE (KCAL/KWH)
1. HPT inlet press. by 5.0 ata 6.25
2. HPT inlet temperature by 10.0deg C 6.0
3. IPT inlet temperature by 10.0deg C 5.6
4. Condenser pressure by 10.0 mm of Hg 9.0
5. Re spray water quantity by 1.0 4.0
6. HPT Cylinder efficiency by 1.0 3.5
7. IPT Cylinder efficiency by 1.0 4.0
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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 (_at_06months)
0.1 0.2 0.3
0.4 Overall Instrument 0.30
0.40 0.50 0.60 accuracy


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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

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• 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 K0.32 for fuel oil
• CO2 in flue gas K0.35 for Bituminous coal
• Heat loss due to evaporation of moisture H2 in
  fuel
• Hm Wm9H (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
• COCO2 G.C.V
• Heat loss due to unburnt carbon C
• Hc Wc x 7831 as of heat input

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• 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 32O2 28.02 N2
  28.01COCb 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

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FG
Expansion Bellow
Economizer
HVS
APH
Sampling Locations
APH
FG
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• Annexure - I
• BOILER EFFICIENCY AND APH TEST SCHEME
  INSTRUMENTATION DIAGRAM
•  
• Grid measurement for gas composition and gas
  temp. at air pre heater inlet / outlet.

W/6 W/3 T1 W/3 T2 W/6 T3
N11 N21 N31 D/6
N12 N22 N32 D/3
N13 N23 N33 D/3
D/6
DEPTH
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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.
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• 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 superheater attemperation 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

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ENERGY AUDIT SCHEME FOR 210 LMW STEAM TURBINE
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PERFORMANCE TEST PROCEDURE FOR PUMPS
Measured flow Q M3 / HR
Suction pressure Ps kg / m2
Discharge Pressure PD kg / cm2
Test speed Nrpm
Liquid temp. T C
Specific weight of liquid W kg / M3
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 gt Q2
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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
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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

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• 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

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• 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.

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• 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

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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.
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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
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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

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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.

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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.
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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.

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• 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.

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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.

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• 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

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• 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

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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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• Electrical system

1 Transformers Assessment of the health Transformer load loss of GT, UAT, Station Service transformers etc. Identification of possible Energy conservation options in this area.
2 Motors Assessment of Loading condition of HT and LT motors of Boiler area, Turbine area and Balance of Plant area. Assessment of operating parameters like load variation, Power factor, of HT and LT motors consuming power more than 50 KW. Identification of possible Energy conservation options in this area (with latest techniques).
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Capacitors Assessment of health of capacitors.
Plant Lighting system Lighting load survey and Assessment of installed load efficacy (I.L.E) and I.L.E ratio at various areas of plant. Assessment of present lighting controls Identification of Energy Conservation Opportunities.
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• D Fans and Pumps Performance
• Performance of fans consuming power more than 50
  KW such as ID, FD, PA fans etc.
• Input power measurement
• Fan loading and combined efficiency of fan and
  motor
• Specific energy consumption
• Pump performance for BFPs, CEPs, Aux C.W.P
  C.W.Pand pumps consuming power more than 50 KW
  etc.
• Check Performance of the pumps by comparing the
  corrected measured flow at operating speed to
  design speed with that of the expected flow
  derived from the characteristic curves against
  the corrected total dynamic head at design speed.
• Determine Pump efficiency as the ratio of power
  input to the pump shaft to hydraulic power.
• Specific power consumption

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• E Insulation Audit
• Walk through survey of Boiler, Turbine and
  associated steam piping to identify the damaged
  and Hot spot area.
• Surface temperature measurement at the damaged
  and Hot spot area by infrared temperature
  indicator.
• Estimation of heat loss in the hot spots and
  damaged insulation area.
•  
• F Balance Of Plant
• (i) Compressed air system
• Free Air Delivery i.e. Capacity evaluation of the
  Plant and Instrument air compressors.
• Checking volumetric efficiency of compressors.
• Assessment of compressed air leakage quantity.
• Assessment of Energy performance of the air
  compressors/ specific power consumption.
• Study of the compressed air network and suggest
  suitable energy saving options.

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• (ii) Air conditioning system
• Performance evaluation of AC Plant w.r.t net
  cooling / refrigeration capacity along with heat
  load of Air handling unit and energy requirements
  at the operating conditions vis-à-vis design
  condition to be determined.
• (iii) Ash Plant
• Performance of ash Slurry pumps through power
  measurement and flow measurement.
• Ash water ratio assessment and recommendations
  for optimization in water and power consumption.
• (iv) Cooling Tower Performance
• It shall include establishment of
• Liquid/Gas ratio
• Fan efficiency as the ratio of shaft power
  developed and the work done by the fan
• Cooling Tower Effectiveness, approach and range.
• Cooling capacity.

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• V Coal Handling Plant
• Input Power measurement of all the key equipment
  of the CHP area like Paddle feeders, Conveyors,
  Stacker Re-claimer, Wagon Tipplers, Crushers,
• Establishment of specific energy performance
  indicators.
•  
• Accuracy and calibration of the instruments
•  
• The proposed instruments should have following
  level of accuracy.
• Thermocouples and PRTs ASME special class A
  i.e ½ DIN tolerance
• Pressure and differential pressure - 0.1
• transmitters better than

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• Power Meter for generator - 0.1
• Unit Aux Power measurement
• iv Data Logger - 0.03
• v Power transducers / Load Analyser - 0.5
• vi Flue gas analyser - 0.5
• vii Ultrasonic flow meters - 0.5
• viii Anemometer - 1.0
• xi Infrared Thermometer - 1.0
• x Lux meter - 1.0
• xi RH meter - 1.0
• These should be duly calibrated from NABL
  accredited lab.
• The above accuracies for S.No. I to V are as per
  ASME specified for Performance Evaluation of
  Thermal Power Plants.

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• OUR EXPERIENCE OF ENERGY AUDITS OF
• THERMAL POWER PLANTS
• Two 2 x 210 MW units of M/s WBPDCL Kolaghat
  Thermal Power Plant.
• 15 units of Saudi Electric company of Saudi
  Arabia having unit sizes varying from 60 MW to
  660 MW.
• Two 2 x 18 MW units of M/s Shree Cements Captive
  Power Plant.

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METHODS / OBSERVATION FOR SAVINGS ENERGY IN POWER
PLANT

• Operation of machine at very low turbine I/L
  parameters.
• Operation of turbine at lower loads.
• HP and IP turbine cylinder efficiencies are very
  low.
• Main steam and HRH inlet temperature to turbine
  very low.
• RH pressure drop high
• High quantity of SH Spray and its tapings before
  HPH-5 resulting of loss in heat because of
  changed cycle.

Contd.
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METHODS / OBSERVATION FOR SAVINGS ENERGY IN POWER
PLANT

• HP heater no. 5 out of service.
• Turbine cycle not operating as per design scheme
  i.e. Ejector and Deaerator pegging steam from
  PRDS header as against normal source from
  deaerator extraction steam respectively.
• Passing of turbine cycle drain valves.
• Make up quantity to cycle is very high which
  indicates excessive system steam (heat) loss.
• TTD DCA of heaters high

Contd.
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METHODS / OBSERVATION FOR SAVINGS ENERGY IN POWER
PLANT

• Condenser air ingress and dirty tubes.
• Under loading of motors
• Excessive air leakage in compressed air system
• Faulty insulation
• Drain valves passing
• Air ingress to Boiler furnace
• FAD of compressors low

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Thanks
Energo Engineering Projects Ltd. A-57/4, Okhla
Industrial Area, Phase II Phone 91 - 11 -
26385323/ 28/ 29/ 38 Fax 91 11
26385333 E-mail energo_at_del3.vsnl.net.in
energo_at_energo.co.in Web www.energoindia.com