Boiler Basics Essay

2585 Words Oct 11th, 2011 11 Pages
Boiler Basics
Design and operation A boiler is an enclosed vessel that provides a means for combustion heat to be transferred into water until it becomes heated water or steam. The hot water or steam under pressure is then usable for transferring the heat for the steam requirements of process industries or for power generation. Combustion boilers are designed to use the chemical energy in fuel to raise the energy content of water so that it can be used for heating and power applications. Many fossil and non-fossil fuels are fired in boilers, but the most common types of fuel include coal, oil and natural gas. During the combustion process, oxygen reacts with carbon, hydrogen and other elements in the fuel to produce a flame and hot
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Economisers Economisers are the last stage of the feedwater system. They are designed to extract heat value from exhaust gases to heat the steam still further and improve the efficiency of the boiler. They are simple finned tube heat exchangers. Not all boilers have economizers. Usually they are found only on water tube boilers using fossil fuel as an energy conservation measure. A feedwater economiser reduces steam boiler fuel requirements by transferring heat from the flue gas to incoming feedwaer. By recovering waste heat, an economiser can often reduce fuel requirements by 5 per cent to 10 per cent and pay for itself in less than two years. A feedwater economiser is appropriate when insufficient heat transfer surface exists within the boiler to remove combustion heat. Boilers that exceed 100 boiler hp, operating at pressures exceeding 75 psig or above, and those that are significantly loaded all year long are excellent candidates for econimiser retrofit. Steam system Steam and mud drums A boiler system consists of a steam drum and a mud drum. The steam drum is the upper drum of a watertube boiler where the separation of water and steam occurs. Feedwater enters the boiler steam drum from the economizers or from the feedwater heater train if there is no economiser. The colder feedwater helps create the circulation in the boiler. The steam outlet line normally takes off from this

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