aux power saving
TRANSCRIPT
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ATAR SINGH
Dy. DIRECTOR
NPTI FARIDABAD
ENERGY AUDIT OF AUXILIARY POWER CONSUMPTION
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Energy Conservation in Power
Utility
Power plant produces electrical energy
and also consumes a substantial amountof energy in the form of auxiliary
consumption required for various plant
equipments and services
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Energy Conservation in Power Utility
Achieved mainly by:
Operating the equipments at maximumefficiency and
Reduction of auxiliary Power
consumption
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The auxiliary power consumption (APC) varies from 6-14% ,
depending on Size of plant ,use of TDBFP &age of plant
The 500 MW units register the least APC, largely due to the
incorporation of TDBFP.
In some of the old 110 MW plants, APC consumption of 14%is also observed.
Energy audit in a vast thermal power station (TPS) is better
tackled when the thermal power plant operations are
segregated into different sub-areas like:
main plant auxiliaries, draft system (consisting of ID/FD/PAfans), feed water system [consisting of Boiler Fed Pumps
(BFPs) / Condensate Extraction Pumps (CEPs), Circulating
Water (CW) system-including Cooling Tower (CTs)], and off
sites (consisting of coal handling plants, ash handling plants,
air compressors, AC plants, station lightings etc.).
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Auxiliary Power Consumption in ThermalPower Plant is major source of energyconsumption.
During the financial year 2007-08 totalgeneration by coal plant was 488157.46 MUswith PLF 78.75.
Auxiliary Power Consumption was 8.17%.
If this APC gets reduced only by 0.17%then it is equivalent to fresh capacity additionof 120 MW without any investment.
APC Scenario In India
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Trombay Station of Tata Power Co. Ltd achieved lowest
auxiliary power consumption (4.30%) in the country.
Among Central Sector Stations, Talcher
STPS of NTPC achieved the lowest auxiliary
power consumption (5.34%).
Among State Sector Stations, Chandrapur
STPS of MAHAGENCO achieved the lowest
auxiliary power consumption (7.40%).
Among different capacity groups, the lowest
auxiliary power consumption was 6.13% in 500
MW group.
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Requirement of works power with load
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Factors Affecting Auxiliary Power
Consumption
- Unit Generation and load Pattern
- Operation of Plant Auxiliaries
- Service auxiliary such as Illumination , air
conditioning
- Unit Startup / shutdown
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Data collection
Measurements & Observations
Exploration for energy conservation measures
Report preparation
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
DATA COLLECTION
Motor details required-
ID code, Application, Make, Brief details of drivenequipment, Type of the Motor, Motor kW, Motor frame,
Duty, Rated RPM, Rated p.f., Rated motor efficiency ,Motormake, Motor voltage, Rated current of motor,Year,Operating hours,Energy meter installed or Not , No. oftimes the motor is rewound
Collect the above information for all motors to be covered inthe energy audit.
Collect the motor efficiency curves
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Instruments Required-
Power Analyzer: Used for measuring electrical parameters
such as kW, kVA, pf, V, A and Hz Infrared pyrometer (In case any heating of cable or
motor is suspected)
Stroboscope: To measure the speed of the driven
equipment and motor
The above instruments can be used in addition to thecalibrated online / plant instruments
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Parameters to be measured-
Energy consumption pattern of motors (daily / monthly/yearly consumption if available)
Motor electrical parameters (kW, kVA, Pf, A, V, Hz,
etc.) for individual motors Equipment operational details
While conducting the measurement or performanceevaluation of any system simultaneously, the followingneed to be noted
Unit load of the plant Date & time of measurement Instruments used for measurement Frequency of the measurement
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
MEASUREMENTSAND OBSERVATIONS
System detailsDetailed interactions with the plant personnel
Energy consumption Pattern
If the plant is monitoring the energy consumption, itis suggested to record the data and monitor the daily and
monthly consumption pattern
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Equipment AnnualConsumption
MWH
Average Load
KW
% of TotalGeneration
% of total APC
Air Compressors
Coal Handling Plant
Raw Water pumps
DM water pumps
A/C systems
ESP
Total
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Equipment AnnualConsumption
MWH
Average Load
KW
% of TotalGeneration
% of total APC
Boiler Feed Pump
Condensate extraction
Pump
CW Pumps
ID Fans
FD Fans
PA Fans
Mils
CT Fans
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MW % MW % MW % MW % MW % MW %
BFP's 4.52 2.78 4.29 2.98 4.52 3.39 - - - - 13.34 1.02%
CEP's 0.43 0.26 0.43 0.30 0.41 0.31 1.69 0.45 1.78 0.42 4.73 0.36%
FD's 0.35 0.22 0.31 0.22 0.30 0.23 1.21 0.29 1.26 0.29 3.43 0.26%
ID's 2.26 1.38 2.08 1.44 2.34 1.51 8.18 2.24 7.25 1.51 22.12 1.69%
PA's 2.31 1.41 2.38 1.65 2.36 1.52 4.85 1.34 4.82 1.00 16.72 1.28%
Coal Mills 1.21 0.74 1.53 1.06 1.69 1.08 2.92 0.81 2.92 0.61 10.25 0.79%
CHP 0.57 0.35 0.57 0.39 0.57 0.36 1.11 0.31 1.11 0.23 3.92 0.30%
AHP 0.47 0.29 0.47 0.33 0.47 0.30 0.52 0.14 0.52 0.11 2.45 0.19%Air
Compressors
0.42 0.26 0.42 0.29 0.42 0.27 0.38 0.11 0.38 0.08 2.04 0.16%
Others
(CWPs,
RWPs, DM
Plant, etc )
3.89 2.37 4.21 2.92 4.11 2.64 10.28 2.84 10.22 2.13 32.70 2.50%
Total 16.42 10.06 16.67 11.58 17.18 11.61 31.14 8.53 30.26 6.38 111.70 8.56%
MW %
Total Generation 1305.57 81.60 (of installed capacity)
Auxiliary Power Consumption 111.7 8.56 (of actual generation)
Contribution
To APC By
Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Over All
STEPS INVOLVED IN CONDUCTING ENERGY
AUDIT
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Motor loading survey
Details Rated Kw Rated Efficiency Rated Speed Measurement of parameters Power factor
kVA KW drawn Frequency Harmonics Motor speed Driven Voltage Current
Power equipment speed Driven equipment parameters Operational observations Transmission % loading on the motor
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Motor loading can be estimated by:
% Loading =
Input kW to motor x 100
---------------------------------------------------------------------
Name plate kW /Name plate full load motor efficiency
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
While conducting motor load survey,
observations on machine side:
parameters such as speed, load, pressure,temperature, etc., (as relevant) are also taken
availability of load-end capacitors for PF
correction & energy meters for monitoring is alsolooked into for each case.
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Motor Rewinding History
comparison of no load current and stator resistance
per phase of a rewound motor with the original no-load
current and stator resistance at the same voltage can be one
of the indicators to assess the efficacy of rewinding.
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Power Factor Correction
Induction motors are characterized by power factorsless than unity, leading to lesser efficiency (higher
overall operating cost) associated with a plant'selectrical system.
Capacitors connected in parallel (shunted) with themotor are typically used to improve the power factor
The impacts of PF correction include reduced kVAdrawn , KVAR & current, reduction of transformer load,
Reduction of cable losses, reduction of switch gear rating, Enhanced life of equipment
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
EXPLORATION OF ENERGY CONSERVATION
MEASURES
Replacement / sizing of motors Opting for energyefficient motors, Use of high efficiency motors,
Use of energy efficient transmission
Replacement of pulleys
Direct coupling
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STEPS INVOLVED IN CONDUCTING
ENERGY AUDIT
Analysis of observations
o Loading pattern - % loading
o Comments of power supply quality
The BIS standards specify that a motor should becapable of delivering its rated output with a voltage
variation of 6 % and frequency variation of 3 %. Motor
o Identified motors with less than 50 % loading, 50 75 %
loading, 75- 100 % loading, over 100 % loading
o Identified motors with machine side losses / inefficiencieslike idle operations, throttling/damper operations
o Motor load survey is aimed not only as a measure to
identify motor efficiency areas but equally importantly, as
a means to check combined efficiency of the motor, driven
machine and controller
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AUXILIARY POWER CONSUMPTION
Operating only 4 mills instead of 5 mills in 210 MW units
Shutting of CTs cells in conjunction with favorable weather
conditions and replacing existing aluminum cast and GRP blades
with FRP
avoiding idle running of conveyors & crushers
incorporating soft starter - energy savers etc.
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STRATEGY
Variable frequency drive for PA Fans & ID Fans & CEPs
Air in-leaks in draft system (O2 measurement) blanketing
Replacement of inefficient BFPs as a part of R& M of the oldplants.
Clipping of one stage from the multi stage BFPs to balance thepressure drop requirements between HP heaters, economizer andboiler drum etc.
Use of higher pressure in the deareator to commensurately
reduce BFP power consumption (reduced head developed) Running of two CEPs instead of 3 CEPs (3 CEPs are run to avoidtripping due to lower frequency in some of the power plants)
Application of variable speed drives
Installation of hydraulic turbine instead of feed regulating sectionto avoid pressure drops and to generate additional power
AUXILIARY POWER CONSUMPTION
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