Auxiliary Power Reduction in Thermal Power Plant

8/13/2019 Auxiliary Power Reduction in Thermal Power Plant

http://slidepdf.com/reader/full/auxiliary-power-reduction-in-thermal-power-plant 1/27

Auxiliary Power Consumption

Reduction in Thermal PowerStations

Ramesh Bhatia

Schneider Electric



APC Reduction In Thermal Power

Stations

> APC - Scenario of Indian Thermal Power Stations> APC - Facts

> System-wise Opportunities and results



Indian Power Sector

Fuel MW

Total Thermal 105646.98

Coal 87,093.38

Gas 17,353.85

Oil 1,199.75

Hydro (Renewable) 37,033.40

Nuclear 4,560.00

Renewable Energy 16,429.42

Sources** (MNRE)

Total 1,63,669.80

(as on 31-07-2010 by CEA)

**include Small Hydro Project, Biomass Gasifier, Biomass Power, Urban & Industrial Waste Power, Wind Energy



APC - Indian Scenario(Source: CEA -Performance Review of Thermal Power Stations 2007-2008)

APC - Capacity wise SHR - Region wise (2007-2008)

Capacity Group in MW

500

250

Auxiliary Power consumption in %

6.13

8.80

Region Weighted Weighted

Average average

Design SHR Operating

(kcal/kWh) SHR

(kcal/kWh)

210 8.77Northern 2347.2 2603.2

195-200 7.67Western 2371.6 2787.0

100-150 10.32

<100 10.31

National Level APC - 8.32%Best Acheived Sipat STPS of NTPC 5.04%(Source: CEA -Performance Review of Thermal Power Stations 2008-2009)

Southern 2400.6 2653.2

Eastern 2391.4 2738.5

National Level SHR

Design 2376.8 kcal/kWh

Operating2703.9 kcal/kWh




Stations

> APC - Scenario of Indian Thermal Power Stations

> APC - Facts> System-wise Opportunities

and results



APC - Elements

Draft System(ID,FD,PA /SA, HGR

Others (Air washer, ACplant etc)

Lighting

Fans

AuxiliaryPower

Feed Water System ( BFP,

CEP)

Cooling water system (ACW,

MCW, CT)

Consumption

Water Coal HandlingTreatment & Grinding

System Plant

mpressed Ash handling Air System System



APC Break-up

Gross Generation Vs APC Typical APC Breakup

Cooling water systemNet Generation , 91.68% , 1.20%

APC, 8.32%

Feed water System , 3.22%

Coal Handling & Grinding , 0.58%

Ash Handling , 0.72%

Compressed Air System, 0.04%

Water treatment System, 0.27%

Lighiting , 0.07%

Draft System, 2.20%



THERMAL AUXILIARIES

FOR A TYPICAL 210 MW UNIT

HT Motors LT Motors

(6.6 KV) (415 V)

43 Nos 510 Nos

17.5%

Total Connected Load

Auxiliary Consumption as % of total generation



Auxiliary Power Consumption

Factors affecting APC

Operating the

equipment at maximum

efficiency

EnergyConservation

in PowerStations

Reduction of auxiliaryPower

consumption

Plant load factor

Operational efficiency of equipments

Startup & shutdown

Age of the plant

Coal Quality

High

Moderate*

Low

High*

Moderate to High

*Depends on R & M

Reduction of 0.2 - 0.3 % in APC with retrofits and system optimisation techniques could be achieved. Major retrofits can result into higher APC reduction



APC IN THERMAL STATIONS

Therefore,

„ Auxiliaries may consume upto 12% of total generation

„Reduction of even 0.5 - 1.0 % can result in huge savings andadditional output of a few Megawatts

Note,- APC is measured only from difference of generated and transmitted

power, but no direct measure

- APC calculation is approximate and efficiency of eachequipment is unavailable

- Loss of efficiency due to technical/maintenance reasons cannot beascertained and isolated




Stations

> APC - Scenario of Indian Thermal Power Stations

> APC - Facts

> S ystem-wise Opportunities

and results



Auxiliary Power ConsumptionOverview

Process

Requirement Analysis

Effectiveness analysis

Break-even in terms of power consumption and process

gain

Multi level / element Control

Process Upgrades

System

Pressure drop analysis

Flow requirement, sizing And layout

System level control

System retrofits for full /

partial load requirement

System retrofits for abnormal

And normal conditions

Equipment

Actual requirement corrections

Corrections due to

Performance deterioration

Equipment control and retrofits

Internals replacement and retrofits

Energy Efficient Equipments



System Configuration for Energy Management System in a Power PlantCONTROL ROOM

eLAN

Client

Software- 1

eLAN eLANServer Redundant

Software Software

LAN

eLAN eLAN

Client Client

Software-2 Software-3

8 Port Ethernet Switch

12 Port 12 Port 12 Port

LIU LIU LIU

12 Port Dept. A 12 Port Dept. B 12 Port Dept. C

LIU LIU LIU

8 Port Ethernet Switch 8 Port Ethernet Switch 8 Port Ethernet Switch

RS RS RS RS RS RS

485-1 485-2 485-1 485-2 485-1 485-2

1 20 1 20 1 20 1 20 1 20 1 20

EM 6400 EM 6400 EM 6400 EM 6400 EM 6400 EM 6400 EM 6400 EM 6400 EM 6400 EM 6400 EM 6400 EM 6400

10/ 100 Mbps Cat6 RS 485 Fibre 6 core Cat6 ION 7550Single ModePatch Cable patch Single Cable RTUMedia Convertorchord chord Mode Cable



APC Reduction Measures

Boiler Feed Water System

BFP & CEP• Speed control in place of valve control

• Variable speed drive (BFP, CEP)

• Variable speed Hydraulic coupling (BFP)

• BFP scoop operation in three element mode instead of DP mode

• Avoid Recirculation

• Faulty valve • BFP Cartridge Replacement

• CEP Pressure reduction by Stage removal Scoop operation in Direct Mode

BFP re-circulation through bypass valve leakage was established through study in one of the plant (manual valve closed for 1 hour) and 45 kW (3%) power reduction in BFP was observed Operation of BFP with lower DP (14 bar to 6 bar ) in a 2 x 125 MW plant resulted in to reduction1.8 MU




Draft System

FD, PA & ID FansArresting Air in-leaks in draft system (by O2 measurement)

Excess Air for combustion - Increase in FD, PA & ID fan power Leakage in APH - increase in FD, PA & ID fan power consumption Leakage in Duct & ESP body - increase in ID fan power

consumption

Comparative analysis of fan performance with respect to design

Excess Air

Air ingress

Flowincreasein ID fan

Identification of the gaps by investigation & Observation Inlet/outlet Duct connection

Fan body - for holes/cracks

Deposits formation in impellers/casings Erosion of impeller blades

Maintain Primary Air to Secondary Air ratio to reduce the PA fan power consumption

Fuel

Pulverized Coal

Type of Furnace or Excess Air

Burners (%by wt)

Completely water-cooled 15-20 Furnace or slag-

tap or dry-ash removal

Partially water-cooled 15 -40 Furnace or dry-ash

Removal

14% air ingress between APH and ID Fan was indentified in one of the plants and it was rectified to 4% , this resulted in 17% reduction in ID Fan power consumption




Draft System

Elimination of damper/Inlet Guide vane based capacity

control with variable speed control system

Variable speed drive

Variable speed hydraulic coupling

Use of energy efficient fans

Fan Curve atConst. Speed Fan Efficiency 77%

700 Partially B Oversize Fan 82%closed valve

Change of impeller with energy efficient / appropriately sized

impeller

500

420

StaticPressure

A

System Curves C

Full open valve

Required Fan

Operating Points

30000 50000 Flow (m3/hr)

Efficiency improvement by replacing fans and impellers of FD, PA and ID Fan results in Energy Saving of 14.5 MU at an investment of Rs. 20 MINR




Coal Handling PlantCoal Handling Plant

Proper Capacity utilization/under loading of system

Idle running of conveyors/crushers

Consumes 15 to 20% of full load power Auto Star-Delta- Star in place of DOL/Star- Delta

Minimization of motor losses for under

loaded motors (<40%)

Control of transfer point dust extraction fans and dust suppression pumps

Adequate and constant loading of crushers (often seen loading <50%)

Optimisation of crusher loading has resulted in reduction 25% of operating time and 16% in energy consumption i.e. 0.5 MU per annum




Coal Milling

Coal Milling/Grinding System• Maintain proper air fuel ratio

• Periodic testing of coal particle size • To minimize fines (less than minimum required size)

• Optimized Mill parameters

•Ball loading in Ball/ tube mill

•Roller pressure with respect to grindability of coal • Mill internals replacement with regression analysis of previous and present consumption pattern (including particle distribution)

Ball Load

Power &Roller Pressure

Break-even point for replacement must be identified so as to avoid excess energy consumption in

coal mill



Replacement Analysis

Grinding Roll Run Hours Vs Specific Power Consumption

10

9.5 9

8.5 8

7.5 7

6.5

6

5.5

5

0 500 1000 1500

y = 2E-07x2 - 0.0004x + 6.9991 R2 = 0.9685

2000 2500 3000 3500 4000 4500 5000

Run Hours




Cooling Water System

Cooling Water Pumps

• Suction related issues • Mis-match of required head and rated

head

• Number of pumps operation based on vacuum during favorable condition

(careful analysis to be made between power gain and pump consumption)

• Auxiliary Cooling water Pumps

• Avoid circulation of cooling in standby systems (i.e. oil coolers etc)

• Used ACW water to condenser

Cooling tower• Nozzles to give better distribution over the fill

• Follow Manufacturers recommended clearances around cooling towers and relocate or modify structures that interfere with exhaust or air intake

• Optimize cooling tower fan blade angle on a seasonal and/ or load basis

• Correct excessive and/ or uneven fan blade tip clearance

• Replace splash bars with self extinguishing PVC cellular film fills

• Periodically clean plugged cooling tower distribution nozzles

• Maintain the Optimum L/G ratio 1.4 to 1.6 ( Rectify distribution problems)

Old cooling water pumps operating at 52% efficiency and developing only 70% of

the rated head has been replaced and saved 0.8 MU per annumDetailed study of cooling tower capability, L/G ratio, gas exit velocity, air flow and

recirculation to operate 7 CTs instead of 8 CTs has resulted in to energy saving

of 0.43 MU per annum



Water Treatment Plant and Water

Pumping

Avoid over sizing and improper selection of pump Using start stop control

Eg: filling the tank with level based control

Variable speed drives with feedback control Impeller Trimming to permanently reduce the capacity Proper maintenance

Periodic checking of valves Cavitation

Leakage in gland sealing Deposits on impeller/casing

Change the RO discharge Pressure setting with respect to raw water TDS

Multiple pumps in parallel operation as per flow requirement


Detailed study of entire system from intake to make-up water has potential in optimisation

complete system (intermittent operation of additional pump, avoiding recirculation,

installation of VFDs (raw water make-up, cooling tower make-up, ash water make-up, service wate make-up, drinking water make-up). Estimated annual savings of these measures is 1.38 MU with

investment payback of 20 months




Compressed air System

Air CompressorAir Optimizing discharge air pressureInstrument air application - 6 bar(g)

Ash Conveying - 3 bar(g)Open ended cleaning houses- 2 bar(g) Optimum capacity utilization Loading > 80%

Capacity control

Cascading operationCylinder cut off

Variable speed

Energy efficient compressorsScrew in place of reciprocation

Other Steps

Take cool, Dry & clean air

Reduction of generation pressure (identified areas), additional piping to reduce pressure drop, improvement of Volumetric efficiency, separation of cleaning air network with PRV and cleaning

nozzles has potential to save 1.2 MU (8 x 120 MW )




Supply Side: Compressor ControlInternal Control: Most common foun

Load/Unload control

Our benchmarking values:

High Efficiency: Unloading rate < 20%

Average Efficiency: 50% >Unloading rate > 20%

Bad Efficiency: 70% >Unloading rate > 50%

Very Bad Efficiency: Unloading rate >70%




Compressed air System

Distribution SystemReduce the compressed air leakage Low pressure drop network

Maximum Pr drop 0.6 to 1.0 bar

DriersUse of heat of compression air dryer

instead of electrically heated air dryer

User EndOpen ended usage - use nozzles

& pressure regulator

Separation of cleaning air network and reduction of service air generation pressure in a PP resulted in stopping of one air compressor 0.35 MU




Power Distribution

MotorsLoading < 30% - Stat Delta Star

connection to minimize motor losses

Example: CHP conveyor Motors Energy Efficient Motors

TransformersOptimizing Voltage level of distribution

Transformer Loading Optimization

Optimum loading 50 to 60%Shifting of loads to under loaded

Transformers

Power Factor Improvement(Applicable only on selected areas)

Benefitsreduced kVA drawn , KVAR & current reduction of transformer load

reduction of cable losses, reduction of switch gear rating Enhanced life of equipment

Fixed capacitor banks

(Shunt Connected) at major load ends

15 - 20 years old rewound and under load (<40% loading) motors are Candidates for replacement with Energy Efficient Motors

BoP area distribution transformersBoP area, ESP, AHP transformers could be considered for PF Improvement



Conclusion●Yesterday, we operated plant processes, systems and equipments manually

●Today, we are operating these with localised controls and partial integrated control

●Tomorrow, we will have to operate with full integrated and intelligent controls with innovative solutions

where we do more than we can imagine today, with

less than we used yesterday!

●The key to success is changing our behaviour…



Make the most of your energy™

Documents

Auxiliary Power Reduction in Thermal Power Plant