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Power Plant

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Power Plant

  1. 1. Report By: Syed Muhammad Ali Shah Electrical Engineer from UET Lahore Submittedto: Captain Shoaib
  2. 2. Introduction PowerPlant A power plant (also referred to as a generating station, power plant, powerhouse or generating station) is an industrial facility for the generation of electric power. Basic Mechanism The center of nearly all power stations is a generator, a rotating machine that converts mechanical power into electrical power by creating relative motion between a magnetic field and a conductor. The energy source harnessed to turn the generator varies widely. It depends chiefly on which fuels are easily available, cheap enough and on the types of technology that the power company has access to. Most power stations in the world burn fossil fuels such as coal, oil, and natural gas to generate electricity, and some use nuclear power, but there is an increasing use of cleaner renewable sources such as solar, wind, wave and hydroelectric. Types of powerplants In short there are following types of power plants  Thermal power plant (fossil fuels, coal, oil, natural gas)  Hydro power plant  Nuclear power plant  Solar power plant  Wind power plant  Wave water plant
  3. 3. Nishat Power Plant Nishat power plant is indeed a “Thermal Power Plant”. This uses Furnas oil as a source of fuel. It has 11 engines to drive same number of alternators (synchronous generators). It is a combine- cycle power plant which uses the waste smoke of engines to run STG (steam turbine generator). One alternator produces 17MW and STG produces 15MW, so the power plant has the total capacity of 200MW. It uses 4MW to derive its own auxiliaries. So the dispatch to wapda is 196MW. Systems of Nishat PowerPlant This is a power plant which has the following systems in it.  Fuel system  Cooling system  Lube oil system  Compressed air system  Engine operation  Engine instrumentation  Programmable logic control (PLC) system  Alternator working  Alternator construction  Alternator protection  Motors  Switchyard description  Power Transformers basics  Power Transformer protection  Feeder protections  Heat recovery system generator (HRSG)  Heat recovery system generator operation  Steam Turbine  Steam Turbine operation  Steam Turbine instrumentations
  4. 4. Fuel System Decanting Area First of all oil tankers are placedindecantingarea,where the supervisortakesthe sample of oil tankersand sendthissample toChemical-labforchecking.Afterclearance fromchemical lablabreports are sendto decantingareastaff anddecantingprocessstarted.
  5. 5. Chemical Lab Chemical lab has chemical engineers which usually check the following requirements.  Density test  Viscosity test  Water contents test  Stability and compatibility test FT House  Oil Transfer Pump Oil from “Storage tanks” come to FT House by using suction pump, from where it is pumped to “Buffer tanks”. There are two buffer tanks; each has the capacity of 200m3. Temperature of oil in Buffer tank is approximately 65 to 70 degrees centigrade.  Separator Oil from Buffer tanks pump back to FT House to pass through “Separator”. There are six separators. It works on the principal of centrifugal force, where impurities move towards the wall of separator and pure oil is collected from center. From separator oil is pumped into “Day tank”. There are two Day tanks, each has the capacity of 500m3. Temperature of oil in Day tank is approximately 85 to 90 degrees centigrade.  Feeder Unit
  6. 6. Oil from Day tank is pumped into feeder unit, where there is a check of its density, viscosity, pressure and flow rate. The pressure is maintained to 5 bars. The important sensors in this unit are given below  Viscosity meter  Macro meter  Candle valve  By pass Buckle valve After this the oil is send to engine.  Oil in Engine Clean leak Dirty leak Tank HFO from feeder unit go into “Clean leak Dirty leak Tank”. Here it comes into and go out, it has only the function to maintain temperature to 94 degree centigrade. Than it goes through three way valve, where we can also have a control to take Diesel(LFO) in the line instead of HFO in case of maintenance. Fuel shut off valve This is an emergency valve to disconnect fuel supply. Flow meter Than we have a flow meter, to check rate of flow of fuel Mixing tank Here we have a mixing tank, it allows the fuel  To settle down  To obtain the same temperature  Allows the engine to run for one or two minutes in case of emergency when fuel is disconnected due to some fault.  Oil from clean leak apartment in “clean leak dirty leak tank” also comes into it.  Unburnt oil is also pumped back into it. Booster pump This increases the pressure of oil. Heater This rises the temperature of fuel to 109 degree centigrade. Duplex filters Now there are two duplex filters, one is under use other one is standby mode. It cleans the fuel and allows going into the Combustion chamber.
  7. 7. Pump Now there is a pump which rises the pressure of fuel to 1400 bars. Injector Injector allows the fuel to inject into combustion chamber with the pressure of 450 bars. Oil from open channels From open channels, oil go into dirty apartment of “Clean leak Dirty leak Tank”. Fromwhere it is wasted as sludge. Oil from close channels From close channels, oil go into clean apartment of “Clean leak Dirty leak Tank”. from where there is a three way valve to control whether we want to move this into “Buffer tanks” or in “Mixing Tank”. Lube oil We start from decanting area. After checking the specificities of lube oil, it is unloaded from the tankers, where it goes into “New lube oil tank” by passing through lube oil pump unit. If due to leakage or after the service of engine, lube oil is required to collect into Sump of engine, it is pumped from the lube oil pump unit. Lube oil comes into, lube oil pump unit from two ways:  New lube oil tank  Service tank There are basically two very important processes regarding to lube oil system
  8. 8.  Lube oil separator  Lube oil temperature maintenance unit Lube oil separator Lube oil from sump after passing through stainer pumped into separator chamber, which works on the principle of centrifugal. Impurities go towards the walls of separator while cleaned oil from the center go again into the sump. Lube oil temperature maintenance unit Lube oil from the sump is pumped into a unit with a pressure of 4.3 bar , where there is a “three way valve” and a “steam heater”. P.L.C controls the opening of three way valve in such a way, that the temperature of lube oil is maintained at 63 degree centigrade. After this there are two, parallel “Candle filters” which cleans the lube oil. Now the lube oil is ready to go into “Oil gallery”, where it is used to lubricate the inner parts of engine. But one more thing, before going into oil gallery, there are two pipes known as “Turbo A and Turbo B”, which have the oil from candle filters but with the pressure of 1.9 bar. After lubrication, lube oil comes back into the sump. Used Lube Oil and Service Lube Oil Tank There is a pipe connection in separator unit, from which we can control whether the oil is allowed to go in “Used lube oil tank” or “Service tank  If the oil is dirty and completes its life it is pumped into used lube oil tank, from where it is wasted.  If the engine is allowed to have a maintenance than engine is made empty with lube oil. This is pumped into service tank. From where it goes into lube oil pump unit, where it is ready to be used for engine. Pre Lube oil There is a line in parallel to pump, when the engine is just started than lube oil of this line is under use. Compressed Air System  There are 6 compressed air pumps to have an air with the pressure of 30 bars.  There are 2 “instrument air units” to have an air with pressure 7 bars. 30 bars Compressed Air First there is are 3 units, each having two compressed air pumps. Each pump followed by a separator unit, which removes “oil/ water contents” from the compressed air. Than
  9. 9. there is a “mechanical valve. After that the lines of two pumps becomes common, and this line now becomes common with the other two units. Finally the compressed air is stored in “Air bottles.  Actually two from the six pumps are on operation; other four are on standby mode.  When compressed air has pressure 25 bars, the pumps are on.  When pressure becomes 30 bars, the pumps are off. Air Bottles There are three air bottles in Hall-A and two in Hall-B. Each one have the following parameters  Capacity of 2800 liters  Compressed air in it has temperature 75-76 degree centigrade Use There are two uses of compressed air  For starting When ignition is not started, this air compresses the piston to achieve a specific rpm, after that, fuel is injected for combustion.  For control purposes  Cut off fuel supply  Pneumatic valves 7 bars Compressed Air There are two “Instrument air units” which compressed the air to 7 bars. Each unit have a compressed air pump, than the separator and a valve. These units have their own air storage bottles. There is also a line from 30 bars compressor unit to air bottles of bars, with the “pressure controlled pump”, which control pressure from 30 bars to 7 bars. Use This air is used by air consumers. Cooling System There are two important terms used in cooling system
  10. 10.  “HT water” which means high temperature water above 70 degree centigrade  “LT water” which means low temperature water. Cooling Towers Water from “Heat Exchanger” go into cooling towers, where it showers from the top, and its temperature reduces to 36 degree centigrade. The cooled water is than pumped back into the heat exchanger. Actually it is an open water system, and it does not mix with water which flows into close system (water which cools different parts of system). Three Way valve There is a three way valve controlled by PLC system for the temperature of HT to maintain at specific level. HT line There is a line from the three way valve known as HT line. HT pump pumps the water into the “Engine Liner” for its cooling and than the water go for the cooling of “Engine Head”. Temperature of “engine lining and head” are very high, so they are cooled by HT water of temperature 90 degree centigrade. The outgoing water has the temperature of 91 degree centigrades. And now the HT water reaches again at three way valve. LT line If outgine water from the engine header has temperature greater than 91 degree centigrade, than PLC decides through three way valve and allow the water to go towards heat exchanger for cooling. After cooling of water if required it passes through LFO to decrease its temperature. Than there is a line of HT which meets the line of LT to maintain the temperature of LT around 43 degree centigrade. The LT water is pumped into 2nd side of Turbo-cooler, than it passes through Lube-oil Heat exchanger, finally it passes through 1st side of Turbo-cooler. Now the water line again reach at the point just after the three way valve. Condensate Preheater Sometimes condensate is very much cooled, so to maintains its temperature, the water that is going for cooling in heat exchanger is passed through it, which warms the condensate. Preheater When the engine is just started its temperature is not too high. To keeps its temperature above 53 degree centigrade, a line which takes water from HT from one point and drops it into the HT line
  11. 11. at another point, resulting the circulation of HT into the engine which continuously increses its temperature at the appropriate point. Expansion Vessel There is an expansion vessel, its water also circulate in the circuit. It has following purposes;  For make-up water in case of leakage  Its reading also tells, whether there is any water leakage in the circuit. Steam Turbine Generator (STG) Boiler Feed Water Tank Temperature of water in Feed Water Tank is 166 degrees centigrade. Whenever its level decreases less than 20m3, TDS pure water tank fills it. Main Parts of Boiler There are four main parts of a boiler 1) LP Evaporator 2) Economizer 3) HP Evaporator
  12. 12. 4) Super Heater LP Evaporator Water from Feed Water Tank comes in LP evaporator, and then returns back to Feed Water Tank. This circulation of water between Feed Water Tank and LP Evaporator is in order to maintain the temperature of Feed Water Tank to 165 degrees centigrade. Economizer There are Feed Water Pumps which pump the water from Feed Water Tank to Economizer through Feed Water Assembly. When water level in boiler is:  50% than half valves of Feed Water Assembly are open  More than 50% than valves of Feed Water Assembly start towards closing  Less than 50% than valves of Feed Water Assembly start towards opening. This Feed Water Assembly Valves are controlled by PLC. The temperature in this section is about 250 degrees centigrade. The water than goes into Steam Drum. HP Evaporator High temperature water from Steam Drum comes now in HP Evaporator. The temperature of this section is around 275 degrees centigrade. The water is converted into steam and sends back to Steam Drum. Super Heater Steam from Steam Drum comes now in Super Heater. Here the temperature is around 300 degrees centigrade, so if any of moisture is there in steam, it is converted into steam. So we get a “Dry Steam”. Steam Header From all the boilers, the lines of their Dry Steam fall into Steam Header, where it is collected. Cyclone Separator Steam from Steam Header passes through Cyclone Separator in order to remove, if any of water content is there in it. Isolating Valves Then there are two isolating valves, which allows the steam to go either in Turbine or in Condensate. Emergency Stop Valve Then there is an Emergency Stop Valve to stop the steam flow.
  13. 13. Lube Oil System Sump There is a Sump in which Lube Oil is present or it comes after lubricating different parts of turbine. There are three different pumps which pump the oil from sump in different situations.  DC Pump When turbine is just started, Lube Oil is pumped with the help of DC Pump.  Machine Pump When turbine is in normal running condition, Lube Oil is pumped with the help of Machine Pump.  Auxiliary Pump When turbine’s rpm go below 5200, than Lube Oil is pumped with the help of Auxiliary Pump. NRV valve (no return valve) This is a valve followed by each pump, so whenever any of the pump is in operation, the NRV valve of the other pump makes it confirm for the Lube Oil not to flow in that pump in opposite direction. All the three pumps meet at a common point. Lube Oil Cooler Lube oil passes through Lube Oil Cooler, where it is cooled. Lube Oil Filter After cooling lube oil passes through Lube Oil Filter where impurities are removed from it. Then there are two lines emerging from that point. 1) One going towards Control Pump, which after passing through “Control valve” reaches “Emergency stop valve” and then lubricates “Throatier Valves”. 2) Second line lubricates different parts of Turbine. Heat Engine Definition Heat Engine is a mechanical machine which converts chemical energy of fuel into mechanical energy. Parts of Heat Engine
  14. 14.  Turbo Charger  Turbo charger cooler  Set of Pistons  Engine head  Sump  Crank shaft  Fly wheel  Fuel injector Working of Heat Engine Different systems for the proper working of heat engine are given below:  Fuel system After refining, maintaining temperature and appropriate pressure fuel is injected into combustion chamber of engine. Fuel is injected at the pressure of 450 bars. Pressure and temperature are maintained to increase efficiency. This is a complete system as already been discussed.  Air system To increase the efficiency of engine, air is filtered and compressed by turbo charger, then cooled by “charger coolers”, which than mix with fuel to produce combustion. This is a complete system as already been discussed.  Lube oil system To lubricate different parts of fuel, lube oil is used. This is a complete system as already been discussed.  Water system To cool different parts of engine, water system is there for this purpose. This is a complete system as already been discussed. Engine Protections Different protections of Engine are given below:  Lube Oil level  Lube Oil pressure  Lube Oil temperature  Lube Oil properties
  15. 15.  OMD (Oil Mist Detector)  Water level  Over speed (Electrical 10% + Mechanical 15%)  Barring temperature safety  High exhaust safety