POWER PROCESS

The Thermal Plant mainly consists of boiler, turbine generator and other auxiliary systems.

Coal/Oil/Gas is burnt in the furnace of the boiler. Walls of the furnace are made of membrane wall (water tubes welded to each other). The heat generated by combustion is absorbed by the water circulated through the water wall tubes and generates steam. The water steam mixture goes to the steam drum where steam is separated. The steam is super heated by passing through superheater tubes arranged within the steam generator. This high pressure and high temperature steam is admitted into the steam turbine to rotate the turbine. The thermal energy of the steam is converted to mechanical energy by the steam. The rotational energy of the turbine runs a generator which produces electricity.

Steam from the turbine is condensed in the condenser. Cooling water is circulated through the condenser to condense the steam. Condensate is pumped through low pressure heaters to deareator. The low pressure heaters are supplied with steam extracted from the low pressure stages of the turbine to heat the condensate.

From the deaerator, which removes dissolved oxygen from the water, water is pumped through high pressure heaters to the boiler by means of boiler feed pump. High pressure heaters receive steam from high pressure stages of the turbine. Heaters are provided for improving the thermal efficiency of the cycle.

A demineralising (DM) plant meets requirements of demineralised water to feed the water make-up to the boiler. It also employs closed circuit cooling water system in which the water from the condenser outlet is cooled in an induced draft type cooling tower.

Coal after grinding into fine powder is mixed with the primary air and supplied to coal burners. Air for combustion (secondary air) is supplied by forced draft fans. Combustion products i.e., flue gases from the boiler are cooled down in air preheaters and then passed through electrostatic precipitators to remove ash. The cleansed flue gas is disposed through the chimney by induced draft fans.