Thermal power plants presentation (bathinda)
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The document describes the key components of a thermal power plant's air and flue gas circuit. It discusses the primary components including the primary air fan, forced draft fan, and induced draft fan which work to move air and flue gases through the system. The air preheater helps further utilize heat from flue gases to preheat air entering the combustion chamber. Fly ash is also removed from flue gases using electrostatic precipitators before being released through the chimney. The overall circuits in a coal-based thermal power plant include feed water/steam, coal/ash, air/flue gas, and cooling water.
Thermal power plants presentation (bathinda)
- 1. THERMAL POWER PLANTS Presentation Transcript: 1. DESCRIPTION OF COMPONENTS OF AIR AND FLUE GAS CIRCUIT PRIMARY AIR FAN PA Fan sucks the atmospheric air and sends it to the APH. This hot air goes to the coal mill to provide sensible heat to the powdered coal and a medium to go to the combustion chamber, Another link from the PA Fan sends cooler air so that the temperature of hotter air can be controlled. 2. (B) FORCED DRAFT FAN FD Fan sucks the atmospheric air and sends to the APH. This hot air enters combustion chamber providing oxygen which is required for combustion process. (C) INDUCED DRAFT FAN ID Fan sucks the flue gases and disposes it to the chimney. 3. AIR PREHEATER The heat carried out with the flue gases coming out of economizer are further utilized for preheating the air before supplying to the combustion chamber. It is a necessary equipment for supply of hot air for drying the coal in pulverized fuel systems to facilitate grinding and satisfactory combustion of fuel in the furnace (E) ELECTRO-STATIC PRECIPITATORS From APH this flue gases (mixed with ash) goes to ESP. The precipitator has plate banks (A-F) which are insulated from each other between which the flue gases are made to pass. The dust particles are ionized and attracted by charged electrodes. Hammering is done to the plates so that fly ash comes down and collect at the bottom. 4. MAIN CIRCUITS OF COAL BASED THERMAL POWER PLANT Feed water and steam circuit Coal and ash circuit Air and flue gas circuit Cooling water circuit 5. FEED WATER CIRCUIT AND STEAM CIRCUIT 6.COAL CIRCUIT 7.ASH CIRCUIT
- 2. 8.AIR AND FLUE GAS CIRCUIT 9.BOILER A boiler is defined as "a closed vessel in which water or other liquid is heated, steam or vapor is generated, steam is superheated, or any combination thereof, under pressure or vacuum, for use external to itself, by the direct application of energy from the combustion of fuels, from electricity or nuclear energy." IBR Steam Boilers means any closed vessel exceeding 22.75 liters in capacity and which is used expressively for generating steam under pressure and includes any mounting or other fitting attached to such vessel, which is wholly, or partly under pressure when the steam is shut off. 10.TYPES OF BOILING NUCLEATE BOILING:- As heat flux increases, the water temperature near the surface increases and reaches saturation temperature , at this point a change from liquid to vapor occurs. As phase change occurs to vapor, small bubbles are formed and they rise to boiler tubes. This is known as nucleate boiling. FILM BOILING:- Beyond nucleate boiling, the bubbles form a film of steam inside heating surface. This is known as film boiling. Nucleate boiling is used in all power plants because film boiling leads to excess temperature in boiler tubes which can lead to failover of boiler tubes. The point at which this failover occurs is called DEVIATION FROM NUCLEATE BOILING (DNP) 11.BASIC COMPONENTS OF RANKINE CYCLE 12.WORKING OF RANKINE CYCLE There are four processes in the Rankine cycle. Process 1-2: The working fluid is pumped from low to high pressure. As the fluid is a liquid at this stage the pump requires little input energy. Process 2-3: The high pressure liquid enters a boiler where it is heated at constant pressure by an external heat source to become a dry saturated vapour. The input energy required can be easily calculated using mollier diagram or h-s chart or enthalpy-entropy chart also known as steam tables. Process 3-4: The dry saturated vapour expands through a turbine, generating power. This decreases the temperature and pressure of the vapour, and some condensation may occur. The output in this process can be easily calculated using the Enthalpy-entropy chart or the steam tables.
- 3. Process 4-1: The wet vapour then enters a condenser where it is condensed at a constant temperature to become a saturated liquid. 13. TYPES OF WATER CIRCULATION NATURAL CIRCULATION:- In natural circulation boilers, circulation of water depends on the difference between the density of an ascending mixture of hot water and steam and a descending body of relatively cool and steam-free water. Natural circulation may be free or accelerated. Natural circulation boilers are of two types: (a) drum type (b) header type FORCED CIRCULATION:- Forced circulation boilers depend upon pumps, rather than upon natural differences in density, for the circulation of water within the boiler. Because forced circulation boilers are not limited by the requirements that hot water and steam must be allowed to flow upward while the cooler water flows downward, a great variety of arrangements may be found in forced circulation boilers. Forced circulation is also known as positive circulation. 14. Thanks.