Coal fired Power Plant Boiler Economizer expansion bellows High Quality exhaust stacks
Power Plant Boiler Economizer Introduction
1. In a steam boiler, it is a heat exchanger device that heats up fluids or recovers residual heat from the combustion product i.e. flue gases in a thermal power plant before being released through the chimney.
2. Flue gases are the combustion exhaust gases produced at power plants consist of mostly nitrogen, carbon dioxide, water vapor, soot carbon monoxide etc.
3. Hence, the economizer in thermal power plants is used to economize the process of electrical power generation, as the name of the device is suggestive of. The recovered heat is in turn used to preheat the boiler feed water, that will eventually be converted to super-heated steam.
4. Thus, saving on fuel consumption and economizing the process to a large extent, as we are essentially gathering the waste heat and applying it to, where it is required. Nowadays, however, in addition to that, the heat available in the exhaust flue gases can be economically recovered using Air Preheater which is essential in all pulverized coal-fired boiler.
H fin tubes Economizer Inspection
1. The major problem at the economizer section is low temperature corrosion and problems from gas side deposits.
2. Sliding and leaky expansion joints at the casing may allow accumulation of soot with severe acid attack.
3. Inspection of tubes bends by opening the inspection covers needs to be carried out to check these.
4. Uptake area may show cracked expansion bellows sign of acid corrosion.
5. General cleanliness of these areas indicates the combustion performance in boiler.
Economizers are used externally to boilers for further heat recovery. Economizers are found in the cooler gas zone and are fed with water temperatures around 116oC or 185oC depending upon whether the feed cycle includes high pressure feed heaters after the de-aerator.
Hot Water Boilers
Hot Oil Heaters
Ovens and Dryers
Specific Combustion Sources
The function of Boiler Economiser
1. The Economizer in Boiler works on the principle of Heat Transfer. Heat transfer usually takes place from high temperature to low temperature.
In the case of Boilers, flue gases or exhaust from the boiler outlet are at high temperature and water that needs to be preheated is at low temperature.
2. So, this temperature difference between water and flue gases helps to increase the feed water temperature.
3. Depending on the type of operations, design of Economisers can be smoke tube type or water tube type.
4. In smoke tube type flue gases are inside the tubes and water is on the shell side while in the water tube type, water is in the tube and flue gases are on the shell side.