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A Project Report (TD607)

On

Abhijeet MADC Nagpur Energy Private Limited

Mihan Power Plant, Khairy Khurd, Hingna, Nagpur

Submitted in partial fulfillment for the Degree of

M. Tech. in Technology & Development

by

Vishal Singh

(Roll No. 123350007)

Under the guidance of

Prof. A. B. Rao

Centre for Technology Alternatives for Rural Areas (CTARA),

Indian Institute of Technology Bombay,

Powai, Mumbai – 400076.

March, 2013

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Contents List of symbols ....................................................................................................................... 3

List of subscripts .................................................................................................................... 3 Certificate by AMNEPL ............................................................................................................ 4 Executive Summary ................................................................................................................... 5 Objective of audit ....................................................................................................................... 5

Chiller Plant ........................................................................................................................... 5

Air Handling Units ................................................................................................................. 5 Boiler Systems ....................................................................................................................... 5

Introduction ................................................................................................................................ 6 Objectives of audit ................................................................................................................. 6 Methodology .......................................................................................................................... 6

Chiller Plant ............................................................................................................................... 7 Figure 1: Chiller plant operation ............................................................................................ 7 Chillers ................................................................................................................................... 8

Condenser water branch ......................................................................................................... 8

Cooling towers ....................................................................................................................... 8 Figure 2: Chiller facility......................................................................................................... 8

Air Handling Units ..................................................................................................................... 9 Figure 3: Air Handling Unit Operations ................................................................................ 9 Compressors ........................................................................................................................... 9

Mechanical ventilation systems ............................................................................................. 9 Indoor air quality.................................................................................................................... 9

Exhaust systems ..................................................................................................................... 9 Boiler Systems ......................................................................................................................... 10

Figure 4: Boiler system operation ........................................................................................ 10 Boiler details ........................................................................................................................ 10

Boiler performance .............................................................................................................. 10 Feedwater pump performance .............................................................................................. 10 Overall boiler system performance (Operating parameters) ................................................ 11 Turbine performance ............................................................................................................ 11

Other details ......................................................................................................................... 11 Total production ................................................................................................................... 11 Figure 5: Grid for distribution.............................................................................................. 11

Measures taken for energy saving............................................................................................ 12 Already implemented ........................................................................................................... 12

Under progress ..................................................................................................................... 12 Conclusions .............................................................................................................................. 13

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List of symbols

mass flow rate kg/s

T temperature (°C)

work done (kJ/s)

heat transfer (kJ/s)

E flow energy (kJ/s)

S specific entropy (kJ/kg K)

H Specific entropy (kJ/kg)

List of subscripts

A air

F fuel

G gas

O dead state

S steam

W water

I inlet

O outlet

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Certificate by AMNEPL

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Executive Summary

The Abhijeet MADC Nagpur Energy Private Limited (AMNEPL) has a thermal power plant

called the “Mihan Power Plant” situated at Khairy Khurd near Hingna in Nagpur. It is located

at a distance of about 35 Kms from the railway station and about 30 Kms from the airport.

The facility is located at a very secluded place away from population and the only

agricultural activity seen nearby was cotton farming on the native black soil.

Objective of audit

The audit was conducted in a walk through fashion on the Twelfth day of February '2013.

The primary objective of this audit was to understand and estimate the quantity of energy that

a thermal power plant takes as input and the amount of followed output of logical energy that

it produces. Key systems and equipment studied are listed as follows:

Chiller Plant

Chillers

Condenser water branch

Cooling towers

Air Handling Units

Compressors

Mechanical ventilation systems

Indoor air quality

Exhaust systems

Boiler Systems

Boiler performance

Feedwater pump performance

Overall boiler system performance

Turbines

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Introduction

Coal based thermal power plant generally operates on Rankine cycle. In ideal vapor power

cycle Carnot cycle has impracticalities associated with it which can be eliminated by

superheating the steam in the boiler and condensing it completely in the condenser. This is

achieved by the Rankine cycle.

The audit was carried out on 12th

February 2013 so as to fulfill the following objectives:

Objectives of audit

To study the energy production and consumption patterns of the of the facility

To identify energy conservation measures for implementation that take into

consideration facility’s technical and operational limitations

Brief description of facility audited

Methodology

Contact with HR department: Ms. Supriya

Fixing of appointment with HR head: 12th

February 2013, 1000 hrs

Meeting with Mr. NCSV Raju, AGM-HR & IR, Abhijet Group, Nagpur

Primary data collection: Mr. Prashant (HR)

Redirected to energy engineer: Mr. Mehul Tatia

Detailed data collection and process understanding

Recording of collected data

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Chiller Plant

A chiller plant normally consists of evaporator pumps, chillers, condenser pumps, and

cooling towers. The evaporator pumps pump chilled water out to air handler units. They use

valves to vary the amount of chilled water entering the unit's water coil to control the

temperature of the air coming out of the unit. This process conserves energy by adding heat

back to the water which goes to the plant.

The return water from the building goes to the evaporator side of the chillers & they cool it

down, transferring the heat to the condenser side of the chillers, which is a separate water

loop again contributing to energy economy.

The condenser pumps pump the water out to the cooling towers. The water is pumped to the

top of the tower & then rains down inside it. There are big fans on the top of the tower that

pulls air through, thus across the raining water & blows it outside. This water pools up at the

bottom of the tower & is sucked back into the building to run through the condenser side of

the chillers again, thus removing the heat from the building.

The major constituents of the chiller plant are as follows:

Chillers

Condenser water branch

Cooling towers

Figure 1: Chiller plant operation1

1 http://www.energyc2.com/home/energyC2Images/coolingCycle.jpg

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Chillers

Details of the equipment: Auxiliary Chilled water pumps

Total: 6 nos.

Flow rate: 1000 l/s

Pump head: 42.5 m

Motor power: 180 kW

Efficiency: >80%

Condenser water branch

Details of the equipment: Condenser water pump

Total: 10 nos.

Flow rate: 5500 m3/min

Pump head: 2.5 m

Motor power: 490 kW

Efficiency: >80%

Cooling towers

Condenser water supply: 38oC

Condenser water return: 28oC

Power: 75 kW

Figure 2: Chiller facility

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Air Handling Units

Figure 3: Air Handling Unit Operations2

Major parts of the AHU are as follows:

Compressors

Mechanical ventilation systems

Indoor air quality

Exhaust systems

Compressors

Service air compressors: 8 nos.

Capacity: 160 kW/1000 cfm

Instrumentation screw type air compressors: 4 nos.

Capacity: 140 kW/750 cfm

Mechanical ventilation systems

Self-rotating type

Indoor air quality

Maintained by air conditioners

Exhaust systems

Use of long chimneys

2 http://docs.oracle.com/cd/E19065-01/servers.e25k/805-5863-13/figures/ch3-4.gif

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Boiler Systems

Figure 4: Boiler system operation3

Major parts of the boiler system are discusses in details as follows:

Boiler details

Total: 4 nos.

Steam capacity: 250 tons/hr

Water flow rate: 255 tons/hr

Operating pressure: 98 kg/cm2

Safety measures: J seal blower

Boiler performance

Excess air: 20%

Flue gas temperature: 140oC

Temperature difference (Out-In): 110o-112

oC

Estimated boiler efficiency: 87%

Feedwater pump performance

Total: 4 nos.

Flow rate: 300 m3/hr

Head pressure: 175 kg/cm2

Power: 1600 kW

Pump efficiency: 87%

3 http://www.way2science.com/wp-content/uploads/2012/02/boiler.jpg

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Overall boiler system performance (Operating parameters)

Steam production: 250 kg/s

Feedwater flow rate: 250 kg/s

No. of feedwater pumps in operation: 1

Total feedwater pump: 100 kW

Feedwater temperature: 240oC\

Turbine performance

Total: 4 nos.

Turbine heat rate: 2218 kcal/kWh

Auxiliary power consumption: 10.5%

Design vacuum: 0.91

Actual vacuum: 0.93

Other details

Unburnt in fly ash: 2%

Unburnt in bed ash: <1%

Total production

Overall plant heat rate: 2650 (± 20) kcal/kWh

Overall production: 4 X 61.5 MW

Overall plant efficiency: 36%

Figure 5: Grid for distribution

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Measures taken for energy saving

The AMNEPL has undertaken some major steps in the recent years for saving of energy and

conservation of resources on the whole. Some of them are listed below:

Already implemented

₹45 lac saved in the boiler per unit (4 units of 1600 kW each) per annum by using

“Auto scoop control”.

Energy saved by 10% collectively in the boiler unit

Reduction in unburnt fly ash/bed ash as per operating philosophy is achieved

Under progress

Installation of new variable frequency drives, cooling tower fans, compressors, etc.

APH leak test in all 4 units to be conducted; heat rate reduced by ~ 250 kcal/kWh

Modification of CHP: running hours reduced to 4-5 hrs from 7-8 hrs earlier

Running capacity increased to 350 kcal/kWh from earlier 250

Vacuum improvement: earlier 0.87-0.88; now 0.91-0.93

Total improvement due to vacuum: 16 kcal/kWh (0.01% improvement)

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Conclusions

The energy audit was successfully carried out at the premises of the Hingna Power Plant of

AMNEPL, Nagpur. This study provided valuable insights to the on-going processes in such a

thermal power plant. It also provided the knowledge that only about a third of the total energy

contained in the fuel source (coal in this case) is successfully converted to electricity and

supplied as output.

There are many transmission and leakage losses which the produced power faces before

reaching the consumer and hence the efficiency of conversion falls further down. The

leaching of resources in the form of thousands of tonnes of coal and millions of cubic meters

of water in the name of producing energy does seem wrong at so many levels. That too when

the very people of the locality have to face about 6 hours load shedding when there is 246

MW power plant running there itself.