What is a rotary air heater?
Rotary air preheater is the main equipment used to recover. waste heat from the exhaust flue gases in thermal power plants. By preheating the combustion air with the hot flue gases. leaving out of the boiler, a considerable increase in efficiency.
What are the different types of air preheater?
There are two types of regenerative air preheaters: the rotating-plate regenerative air preheaters (RAPH) and the stationary-plate regenerative air preheaters (Rothemuhle).
What is the purpose of air preheater?
The purpose of the air preheater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas.
What is the function of economiser and air preheater?
Air Preheaters Similar to economisers, they are devices that transfer heat from one surface to another – but this time from fluid to air. The main objective is to increase the thermal efficiency of a boiler system by recovering the heat from the flue gas and using it to heat the air.
What is preheater in cement plant?
Preheaters are used industrial dry kiln cement production plants to heat the raw mix and drive off carbon dioxide and water before it is fed into the kiln.
Which of the following is not a type of air preheater?
Which of the following is NOT a valid type of air preheater? Explanation: There are three types of air preheater – tubular type, storage type and plate type. There is no such category as temperature type.
What is tubular type air preheater?
Tubular type air preheater(Recuperative Type) This type of preheater is constructed with a large number of vertical or horizontal tubes. These tubes are used to transfer flue gases. These tubes are fitted along with baffles at certain spaces Which manage the airflow. Soots is collected in the soot hopper at the bottom.
What is the difference between economiser and air preheater?
1. economizer requires lesser space and surface area compared to the air heater due to the high tube side water heat transfer coefficient and larger U compared to the air heater. In addition,extended surfaces make them very compact. Air heaters have very low overall U and hence huge.
What is the function of air preheater Mcq?
Explanation: The function of an air preheater is to heat the air that is supplied to the furnace. It helps in the combustion and eases the burning of coal.
What is the difference between economizers and pre heaters?
How does an air preheater increase efficiency?
Air Preheaters For every degree that the incoming air is heated, that results in less energy required from the boiler. In other words, an air preheater saves energy by doing some of the heavy lifting done by the boiler in order to raise the incoming fluid to the appropriate temperature.
What is preheater cyclone?
The cyclone preheater is the core equipment of the new dry process cement production technology. It uses the suspension preheating method to preheat and partially decompose the raw material to shorten the length of the rotary kiln, and at the same time make the raw material and the hot gas flow in the kiln full.
How does a rotary regenerative air preheater work?
The Rotary Regenerative Air Preheater (RAPH) consists of a central rotating-plate element within a casing that is divided into sectors containing seals around the element. The seals allow the element to rotate through all the sectors, but prevent gas leakage between sectors while providing separate gas air and flue gas paths through each sector.
What are the advantages of a rotary pre heater?
The advantages of the rotary regenerative air preheater are: Smaller footprint and lighter structure, which usually results in lower installed cost. Replaceable heat transfer surfaces.
How are rotary heaters different from plate heat exchangers?
Rotary regenerative air preheaters have a much reduced size and cost relative to recuperative tubular or plate heat exchangers. The Howden air preheaters are designed around external insulation. The housing and ducts are structurally independent of the rotor.
What should the temperature be in a cast pre heater?
Typically Flue Gases leaves the convection section of the heater at around 400 °C, and a cast type Air Preheater brings down its temperature to around 200 °C thus resulting in 10% increase in efficiency.