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NSPCL

A JOINT VENTURE OF NTPC and SAIL

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NTPC Ltd formed a joint venture with SAIL on 50:50  basis

in March, 2001 in the name NTPC-SAIL Power Company

Private Limited (NSPCL). NSPCL took over captive power

plant-II located at Durgapur Steel Plant (2X60 MW) and

Rourkela Steel Plant (2X60 MW) from SAIL.

THE COMPANY AND ITS OBJECTIVE

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To supply power to Bhilai, Durgapur and Rourkela Steel Plants of Steel Authority of India

Ltd. (SAIL) on captive basis from its coal based captive power plants –II at Bhilai

(Chhattisgarh) 2X30 MW + 1X14 MW, Durgapur (West Bengal) 2X60 MW and Rourkela

(Orissa) 2X60 MW. To meet additional captive power requirement of Bhilai Steel Plant and

other units of SAIL, NSPCL commissioned Bhilai CPP-II Expansion Power Project

(2X250MW) during 2008-09 and commercialized the units during 2009-10. From the

expansion plant, NSPCL is supplying power to the beneficiaries viz. Union Territory of

Dadra & Nagar Haveli , Union Territory of Daman & Diu, Chhattisgarh and Bhilai Steel

Plant / SAIL in the western region.

OBJECTIVE

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1.Coal handling plant2.Pulverising plant3.Draft fans4.Boiler5.Ash handling plant6.Turbine7.Condenser8.Cooling towers9.Feedwater heater10.Economiser11.Air-Preheater

MAIN AND AUXILIARY EQUIPMENTS

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Coal handling plant

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Use of F- grade coal(3500kcal/kg) Process involved are:1.Seperation of metal2.Stone collection3.Magnetic separator4.Crushing to a size of 20mm5.storage

Details of coal handling plant

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The difference between atmospheric pressure and the pressure existing in the furnace or flue gas passage of a boiler is termed as draft.

There are 2 types of draft fans used in thermal plants:-

1. Induced draft2. Forced draft

DRAFT SYSTEM

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Placed at the outlet of boiler

Exhausts all gaseous combustion products or flue gas by creating negative pressure

More susceptible to erosion and corrosion

Induced draft

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Forced draft

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Supply the air necessary for combustion pushing the air through combustion chamber to the furnace

Most efficient fans in power plants

These are centrifugal fans, uses variable pitch axial fans

Function of FD

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BOILERS

Definition: An enclosed vessel where heating of fuel or gas takes place

Place where differential heating takes place

To maximize efficiency water tubes are constructed

Water tubes absorb the heat

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Water tube boilers Corner fixed Drum type Natural recirculation Tilted firing superheated Vertically downward expansion

TYPES OF BOILERS

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Water tube boiler

A pressure of 140kg/cm2 can be obtained easily.

Increases boiler efficiency

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Definition: It is a water to steam separator

Water entering into the drum has Temp. about 3500 C and pressure about170kg/cm2

It is placed 60m high

It includes natural recirculation process

If pressure >190kg/ cm2 ,then forced recirculation is done

Boiler drum(steam cycle)

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Boiler drum

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Ash is the residue remaining after the coal is incinerated

SiO2, Al2O3, Fe2O3, CaO , MgO are the components in ash

Ash generated in power plant is about 30-40% of total coal consumption 

2 type of ashes:1. Fly Ash -Around 80% is the value of fly ash

generated2. Bottom ash -Bottom ash is 20% of the ash

generated in coal based power stations.

Ash handling plant

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Bottom Ash Handling System: Bottom ash resulting from the combustion of coal in the boiler 

Further the slurry is passed through pipes

Coarse Ash (Economizer Ash) handling System: Ashes generated in economizer

Fly Ash Handling System: Fly ash is considered to be collected in ESP Hoppers.

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TURBINES Turbines form the heart of power plants Generally to maximize the efficiency, steam

has to be expanded Work increases in stages use of HPT,LPT and intermediate turbines

(IPT)- multi stage turbines HPT and IPT are single flow

turbines(expansion of steam on only 1 side) having 24 stages.

LPT is double flow turbine with 8 stages.

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Flow diagram

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HPT Details

Inlet pressure (kg/cm2 )

Inlet temperature(o

C)

Outlet pressure(kg/cm2 )

Outlet temperature(o C)

35 350 147 540

Low Pressure Turbine

Outlet pressure Outlet temperature

8-10 kg/cm2 <500 o C

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IMPULSE TURBINE & REACTION TURBINE

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Have fixed nozzle that orients the flow into high speed jets

High kinetic energy, results in shaft rotation

Drop in the pressure from inlet to outlet increases the expansion rate of steam

Steam velocity increases

There is a loss of energy due to high exit velocity which is called as carry over velocity

EXPLANATION (IMPULSE TURBINE)

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A condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it.

The latent heat is given up by the substance, and will transfer to the condenser coolant.

In thermal Power plant we use surface condenser

condenser

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CROSS-SECTION OF SURFACE CONDENSER

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Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere

Classified into two:1.HVAC cooling tower2.Industrial cooling tower

HVAC(heating , ventilation &air-conditioning)- HVAC use of a cooling tower pairs the cooling tower with a water-cooled chiller or water-cooled condenser.

Industrial Cooling tower- Industrial cooling towers can be used to remove heat from various sources such as machinery or heated process material. 

 The primary use- cooling towers is to remove the heat absorbed in the circulating cooling water systems used in power plants.

Cooling towers

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An air preheater absorbs waste heat from flue gas, then transfers this heat to incoming cold air.

Two types of air preheaters are used: bisector (one air stream per air heater) and trisector ( two air streams per air heater).

The trisector incorporates both primary and secondary air within one housing.

AIR - PREHEATER

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Control room