What is the original solid of high negative pressure in the preheater smoke chamber?

Air preheater, referred to as air preheater, is a kind of preheating equipment to improve the heat exchange performance of boiler and reduce heat loss. The function of the air preheater is to transfer the heat carried in the flue gas discharged from the tail flue of the boiler to the air before entering the boiler through the heat sink, and preheat the air to a certain temperature. Generally called air preheater. Mostly used in coal-fired power station boilers. There are two types: box type and rotary type, and the rotary type is divided into two types: fan cover rotary type and heating surface rotary type. Power plant boilers often use rotary preheaters with heating surfaces. There are generally two silos, three silos and four silos in boilers, among which four silos are widely used in circulating fluidized bed boilers.