Industrial Internship Presentation

Presentation on Industrial Training at

210 MW Shiddhirganj Thermal Power Station

ME-370

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210 MW Shiddhirganj Thermal Power Station

Training Participants:–Md. Jubayer Hossain(0510077)–Shuvra Banik(0510094)–Aminul Islam Khan(0510117)–Sudarshan Chandra Saha(0510119)–Md. Shoeb Hasan(0510130)

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Overview of the plant

– Plant name: Shiddhirganj 210 MW Thermal Power Station

– Site of the plant: Shiddhirganj, Narayanganj

– Plant capacity: 210 MW

– Area of the power plant: 88.56 acre– Plant efficiency: 36%

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Steam power plant energy conversion

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Boiler

• Boiler capacity (Superheated steam): 670 t/h• Reheat steam flow rate: 580 t/h• Superheated steam temperature: 545 ⁰C• Reheat steam temperature at boiler outlet: 540

⁰C• Feed water temperature: 247 ⁰C• Boiler efficiency: 93%

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Turbine

• Nominal capacity of the turbine: 210 MW• Number of cylinder: 03• Total number of stage: 29• Number of extraction: 7• Frequency of rotor rotation: 3000 r.p.m• Steam consumption of turbine at full load: 638.1

t/h

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Generator

• Power output: 210 MW• Power factor: 0.85• Stator voltage: 15.75 ± 5% KV• Excitation voltage: 430V• Phase: 3• Frequency: 50 Hz• Stator cooling media: Demi-water• Rotor cooling media: Hydrogen

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Simplified line diagram of 210 MW STPS

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Description of boiler

•It is the steam generation unit of the plant•It transfers the heat energy of the combustion of fuel to the water•It consists of a boiler drum, mountings and accessories

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Water circulation in boiler

•Feed pump sends demi water to the boiler drum through economizer•Heat produced by combustion converts demi-water into steam•Difference of density between steam and water creates a natural circulation in the downcomer riser circuit. 10

Boiler mountings

• These are the fittings, which are mounted on the boiler for its proper and safe functioning

• Different mountings:»Water level indicator»Pressure gauge»Safety valve»Steam stop valve»Feed regulating valve»Blow off cock»Steam regulating valve

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Boiler accessories

• These are devices which are used as integral parts of a boiler, and help in running efficiently.

• Different accessories:»Feed water pump»Superheater»Economizer»Air preheater»Reheater

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Steam flow in heater

Fig: Flow diagram of steam in superheater

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Air preheating

Fig: Air preheater

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Description of turbine

It consists of 3 cylinders:1. High pressure

cylinder2. Intermediate

pressure cylinder3. Low pressure

cylinderNumber of stages are 29

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Turbine of bearing

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Steam sealing in turbine

Fig: Labyrinth Seal17

Turning gear

•Used during starting and shut down•It rotates the turbine shaft at 2-3 r.p.m•It prevent thermal stresses developed due to non-uniform cooling

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Generator

A generator consists the following parts:•Stator winding (conductor)•Rotor (magnet)•Stator core

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Cooling system of generator

• Two coolants are used: Water and Hydrogen• Stator winding is water cooled• Rotor and stator core are hydrogen cooled• Minimum hydrogen pressure required is 3

kgf/cm2

• Hydrogen purity is maintained 99.9 %• Regulating valve always maintain 0.8kgf/cm2

pressure difference between water and hydrogen

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Maintenance sequence in generator

• Since hydrogen is explosive in contact with air, to avoid this hazard the following sequence is followed during maintenance

• During Opening: 1. Hydrogen out 2. Carbon dioxide (CO2) in3. When the percentage of CO2 is reached to 99-

100 %, air is introduced and CO2 gets out.4. Open the generator

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• During closing:1. Air out2. CO2 in

3. When percentage of CO2 is reached to 99-100%, hydrogen is introduced and CO2 gets out

4. When hydrogen purity reached to 99.9%, generator is closed

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Unit protection system

• Two type of protection system are used in 210MW STPS. These are

»Electrical protection system »Technical protection or process

protection

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Start-up of 210 MW unit• The following starting sequences are followed-• Start circulating water pump(CWP)• Fill the deaerator• Fill the boiler drum• Fire the boiler• Start the turning gear• Check the steam condition• Speed up the turbine• Then gradually increase temperature and

pressure which will take higher load

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Shut down

• Before shut down load is cut down to 70 MW. Then switch off. After shutting off, turning gear runs for about 72 hours at 3rpm.

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Condenser

• It is a shell and tube type condenser • Cooling water passes through the tube and

steam passes outside the tube• The number of tubes are more than 12000• The inside temperature is 45oc• It works at a pressure lower than atmosphere.

It is 0.1kgf/cm2(-0.9kgf/cm2)

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• Ejector pump is used to vacuum the condenser

• The working principle of the ejector pump is based on venturi meter (Bernoulli's principle)

Fig: Vacuum creating principle27

Deaerator

• It removes the dissolved gas from the feed water

• The feed water is heated to saturation temperature by the steam extracted from the turbine to remove the dissolved gas

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Description of pumps

Fig: Vacuum pump

•Vacuum pump is used to create vacuum to bring the syphon come into action. •There are two vacuum pumps•One runs and another remains standby

•Vacuum pump

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Circulating water pump(CWP)

•There are 3 circulating water pumps, two of them are running and one remains standby•They supply water to water treatment plant, firefighting units and they supply water to all the place where cooling is necessary

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Syphonic action and water supply to CW pump

Fig: Water supply to CW pump 31

Other pumps

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Description of HP/LP Heater

• They raise the temperature of feed water before it enters the economizers.

• There are seven feed water heaters• LP heater works at around 13.6-16kgf/cm2

pressure• HP heater works at a pressure of around 182-

185kgf/cm2

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Water treatment plant

• Maintaining good feed water is an important and fundamental aspect of any steam turbine power plant.

• A plant that maintains good feed water achieves the following three benefits:

1. Help to ensure maximum life2. Reduce maintenance expenses3. Maintain optimal thermal performance

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Impurities of natural water

• Dissolved gases• Hardness salts• Non-hardness forming salts• Suspended matters

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Water treatment process

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Chemical reactions at different stages

• Clarifier Al2(SO4)3 + 3Ca(HCO3)2 = Al(OH)3 + CaSO4 + CO2

• Cat-ion exchanger HR + CaSO4 = CaR2 + H2SO4

HR + CaCl2 = CaR2 + HClRegeneration of HRCaR2 + H2SO4 = CaSO4 + HR

• An-ion exchangerROH + H2SO4 = R2SO4 + H2OROH + HCl = RCl + H2ORegeneration of ROHR2SO4 + NaOH = ROH + Na2SO4

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THANK YOU

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