Category: Steam Generators

The purpose of steam generator control is to provide the steam flow required by the turbine at design pressure and temperate. The variables that are controlled are (i) fuel firing rate, (ii) air flow rate, (iii) gas flow distribution, (iv) feed-water flow rate, and (v) turbine valve-setting. The key measurements that describe the plant performance…

A boiler generates 4000 kg/h of steam at 20 bar, 400°C. The feed-water temperature is 50°C. The efficiency of the boiler is 80%. The calorific value of fuel used is 44,500 kJ/kg. The steam generated is supplied to a turbine developing 450 kW and exhausting at 2 bar with dryness fraction 0.96. Calculate the fuel…

1 Evaporation Rate The quantity of water evaporated into steam per hour is called the evaporation rate. It is expressed as kg of steam/h, kg of steam/h/m2 of heating surface, kg of steam/h/m3 of furnace volume, or kg of steam/kg of fuel fired. Equivalent Evaporation It is the equivalent of the evaporation of 1 kg of water…

Boilers are not always required to supply steam for economic or rated load but also required to meet the fluctuating demand of load, that is, peak fractional load. The boiler takes an appreciable time to change the rate of steam generation but the demand for a considerable change of power may occur instantly if the…

These are the appliances installed to increase the overall efficiency of the steam power plant. The various accessories installed are pressure reducing valve, steam trap, steam separator, economiser, air preheater, superheater, feed pump, and injector. The functions of the various accessories are as follows: We shall discuss the air preheater, economiser, and superheater in detail.…

Different fittings and devices necessary for the operation and safety of a boiler are called boiler mountings. The various boiler mountings are as follows: 1 Water Level Indicator The water-level indicator indicates the level of water in the boiler constantly. Every boiler is normally fitted with two water-level indicators at its front end. Figure 3.19 shows a…

Fluidised bed boilers produce steam from fossil and waste fuels by using a technique called fluidised bed combustion (FBC). 1 Bubbling Fluidised Bed Boiler (BFBB) A schematic diagram of BFBB is shown in Fig. 3.18. In this boiler, crushed coal (6−20 mm) is injected into the fluidised bed of limestone just above an air-distribution grid at…

The separation of steam from steam-water mixture can be done by the following methods: The internal details of a controlled circulation boiler are shown in Fig. 3.17. Figure 3.17 Drum internals of a controlled circulation boiler

The purposes of drum used in boiler are as follows: A mixture of water, steam, foam and sludge is discharged into the drum by the risers. Steam must be separated from the mixture before it leaves the drum. Any moisture carried with steam to the superheater tubes contains dissolved salts. In the superheater, water evaporates…

The flow of water and steam within the boiler circuit is called circulation. The insulated downcomers carry water from the steam drum to the header and are located outside the furnace. The risers are located inside the furnace and carry steam to the steam drum from the header. Risers installed all around the four-walls of…