Air Preheaters:

Air preheaters are devices used in thermal power plants and industrial processes to improve the efficiency of boilers and furnaces. They work by recovering waste heat from the exhaust gases and using it to preheat the combustion air before it enters the furnace.  

The preheated air reduces the amount of fuel needed to produce the same amount of heat, thereby improving the overall efficiency of the process. Air preheaters can be of different types, such as rotary regenerative air preheaters, plate type air preheaters, and tubular type air preheaters, among others.  

Air preheaters are an essential component of modern thermal power plants and industrial processes, and they are used to reduce emissions, improve energy efficiency, and save costs.