BATHINDAGURU NANAK DEV THERMAL PLANT

HISTORY

• Foundation stone of G.N.D.T.P. at bathinda was laid on 19th November 1969

• First unit commissioned Sept, 1974• Second unit commissioned Sept, 1975• Third unit commissioned Mar, 1978• Fourth unit commissioned Jan, 1979• Each unit have capacity of 110MW

INTRODUCTION

• It is a coal-based plant

• combustion of coal Heat convert water in pipes into steam steam run the turbine Rotates generator three phase electric supply is produced

Hence basic requirements are :

• Fuel (coal)• Boiler• Steam turbine• Generator• Ash handling system• Unit auxiliaries

PLANT LAYOUT

DIFFERENT CELLS OF PLANT

• CHP(Coal Handling Plant) • Coal is unloaded from wagons using wagon

tippler• When coal reaches the plant, normal size of coal is

about 500mm primary crusher 120mm secondary crusher 25mm coal mill pulverized coal feeded in boiler.

Wagon tippler

• BOILER

• Coal burnt heat (15000 C) Superheated Steam(high P & T) in boiler pipes Turbine(power obtained)

•TURBINE

• steam rotates turbine at 3,000 rpm Rotates power generator electricity produced

•CIRCULATING WATER PUMP

• Two nos. of circulating water pumps provided for each unit.

• One for steam cycle in turbine-condenser-boiler

• 2nd for condenser-cooling tower water cycle

• Each have capacity of 17200 T/hr

•COOLING TOWER

• These are massive ferro-concrete structure having hyperbolic profile creating natural draught of air responsible for achieving the cooling effect.

• Height -- 120 m• Cooling capacity – 18000 T/hr for every 100c

•ASH PRECIPITATORS

• Fly ash carried by outgoing flue gases is arrested at two stages

a) Mechanical precipitators ash particles are separated out by centrifugal action.

b) Electrostatic Precipitators ash particles pass through high voltage electric field, particles get ionized and are attracted towards the collecting electrodes.

ELECTROSTATIC PRECIPITATOR

PROJECT

• WATER TREATMENT to prepare boiler

friendly feed water • COAL TESTING to calculate the grading

of coal

WATER TREATMENT

Natural water is available in abundance, but it contains impurities in many forms which are as :

• Cationic• Anionic• Undissolved (suspended)• Gaseous

TYPES OF IMPURITIES

Cationic Anionic Un-Dissolved Gaseous

Calcium Bicarbonate Turbidity, silt, mud, dirt and other suspended matter

Carbon dioxide

Magnesium Carbonate colour Hydrogen Sulphide

Sodium Hydroxide Organic matter Ammonia

Potassium Sulphate Colloidal silica Methane

Ammonium Chloride Oil Oxygen

Manganese Phosphate Corrosion products (condensate)

Chlorine

Iron Silica

HARDNESS AND SCALING

• Bicarbonates or carbonates of Ca and Mg form soft scale Temporary Hardness Deposits as soft scale in boiler pipes.

• Non-Carbonates of Ca and Mg (e.g.- Sulphates ,Chlorides) permanent hardness Deposits as hard scale in boiler pipes, which is difficult to remove.

When pH of feed water to boiler is below the recommended range chances of corrosion increases, and when it is above recommended value then chances of scaling increases.

Corrosion Scaling

NEGATIVE EFFECTS OF SCALING

• Decrease operating efficiency• Thermal damage• Reduced working life of a boiler• Increased cleaning time and cleaning costs

WATER TREATMENT STEPS

1. Pre-Treatment of water Make water free from suspended, colloidal

and organic impurities.

process involved in pre-treatment are :- a)Settling and Coagulation(using Alum) b)Filtration-Clay ,Colloids ,algae etc.

SETTLING AND COAGULATION

• Alum is mixed in water to make solid particles settle down.

Water from lakes

Clear well

DEMINERALISATION SYSTEM

• It is an ion exchange process with following steps :-

i) Conversion of salts to their corresponding acids by hydrogen cat-ion exchanger

ii)Removal of acids by anion exchangers • Two exchangers are normally in series. Normally

cat-ion precedes the anion exchanger

WORKING OF DM PLANT

•Cation exchanger mainly removes Calcium, Magnesium, sulfates, chloride , nitrates and sodium salts alkalinity from raw water

Water from sand filters

Degasser

•Carbon dioxide generated by dissociation of carbonic acid at cation outlet water, is removed by degasser system

Cation Exchanger

Anion Exchanger

•Anion exchangers remove the highly dissociated acids (like H2So4, HNo3, Hcl ) from the effluent of cation exchanger

DegasserMixed bed Deioniser

CONDUCTIVITY AND pH READINGS

• Raw water [pH>7 ,conductivity=200-300 µ.mhos]• Effluent of cation exchanger [pH≈4 ,conductivity=400-800 µ.mhos ]• Effluent of anion exchanger [ 7<pH<10 ,conductivity=14-15 µ.mhos]

Mixed-bed Deionisation

• Effluent water after anion exchanger may still have some salts due to them its conductivity is around 14-15 micro.mhos. 7 < pH <10 , so it is further passed through Mixed-Bed Deioniser

• The mixed bed mixture of Cation and Anion resins is present there.(resin+Hcl+NaOH)

Mixed-Bed Resin Container

•Treated water has pH 6.8-7.2 ,conductivity < 1µ.mhos

•During charging 100kg each of Hcl and NaOH are injected.

EXHAUST OF DM PLANT INDICATION

• Conductivity of cation exchanger decreases• Conductivity of anion exchanger increases

• It means its time to charge the ion-exchangers

• Cation ex. Charged with Hcl injection• Anion ex. Charged with NaOH injection

DM PLANT SPECIFICATION

• GNDTP has 2 units of DM Plant, each having capacity of 40 T/hr

• DM water storage tank have capacity of 2456m3

• Max running hrs 5(one unit)

COAL TESTING

• Coal used is Bituminous Carbon = (60-70) % Ash = (30-40) % Moisture < (2) % Calorific Value = (3500-4500) Kcal/Kg

Moisture Content Test

1gm sample of powdered coal is weighed and taken in the silicon dish. Then this sample is heated in oven at 1100C for 1hr.then sample is taken out and again weighed. Loss of weight is the water content.

Ash Content Test

In this test 1gm sample of powdered coal is weighed and taken in the silicon dish. Then this sample is heated in oven at 8100c for 1hr.then Sample is taken out and again weighed. Remaining is the only ash content.

Volatile Matter Test

For this test 1gm sample of powdered coal is taken. This sample is taken in a silicon crucible dish and heated at 900C for 7 minutes. Then the remaining amount of sample is noted and the losses are noted.

• Volatile matters are Hg and NH3.

COAL GRADING FORMULATION

• Moisture content - M• Ash content - A

• UHV (useful heat value)=[8900-138(M+A)] Kcal/Kg

The results of the laboratory tests performed on the basis of the representative samples prepared by the sampling system are used for: •Calculating the payment due for each batch of coal supplied •Adjusting the coal flow to the mills •Calculating the amount of by-products from each batch of coal•Calculating the emissions from each batch of coal

THANKS ..!!