The working principle of hot air furnace

It is the use of direct combustion of fuel, high purification treatment to form a hot air, and direct contact with the material heating and drying or baking. The fuel consumption of this method is about half of that of the steam type or other indirect heaters. Therefore, in the case of not affecting the quality of the dried products, it is completely possible to use direct high purification hot air.

Fuel can be divided into:

①Solid fuel, such as coal, coke.

② Liquid fuels, such as diesel, heavy oil, alcohol-based fuels

③ Gas fuels, such as gas, natural gas, liquid gas.

Fuel combustion reaction obtained after the high-temperature combustion gas further contact with the outside air, mixed to a certain temperature directly into the drying room or baking room, and the material to be dried in contact with the heating, evaporation of moisture, so as to obtain the dry product. In order to utilize the combustion reaction heat of these fuels, it is necessary to add a set of fuel combustion devices. Such as: coal burner, fuel oil burner, gas burner, etc..

This direct heating hot air furnace can not be used for breeding and other heating. Mainly suitable for being dried materials are not allowed to be contaminated, or applied to the lower temperature of the heat-sensitive material drying. Such as: milk powder, pharmaceuticals, synthetic resins, fine chemicals and so on. This type of heating device, that is, the steam, thermal oil, flue gas, etc. as a carrier, through a variety of forms of heat exchangers to heat the air.

The most essential issue of indirect hot air furnace is heat exchange. The larger the heat exchange area, the higher the heat conversion rate, the better the energy-saving effect of the hot air furnace, the longer the life of the furnace and heat exchanger. Conversely, the size of the heat exchange area can also be recognized from the flue gas temperature. The lower the smoke temperature, the higher the heat conversion rate, the larger the heat exchange area.

After the separation of fuel and heating source, it can be used for human heating. The working principle can be divided into two kinds of heat storage and heat exchange

Heat storage, according to the heat storage body inside the hot air furnace is divided into ball hot air furnace (referred to as the ball furnace) and the use of lattice bricks of the hot air furnace, according to the combustion method can be divided into the top combustion type, the internal combustion, external combustion, and so on several kinds. How to improve the wind temperature, is the industry's long-term research direction. Commonly used methods are mixing high calorific value gas, or increase the heat exchange area of the hot stove lattice brick, or change the material and density of the lattice brick, or change the shape of the heat storage body (such as heat storage ball), as well as through a variety of methods will be the gas and combustion air preheating.

Advantages: high heat transfer temperature, high heat utilization. Disadvantages: large size, large footprint, hot air temperature is not stable, switching institutions, easy to get out of the problem, short life of the heat storage body, high maintenance costs, the acquisition cost is very high.

Heat exchanger type, the main use of high-temperature heat exchanger as the core components, this component can not use metal heat exchanger, only the use of high-temperature ceramic heat exchanger, gas gas in the combustion chamber fully combusted, the hot air after combustion, through the heat exchanger, the heat to the fresh cold air, the fresh air can be made to reach a temperature of more than 1,000 degrees.

Advantages: high heat transfer temperature, high heat utilization, small size, stable hot air temperature, no switching institutions, long life, high maintenance costs, low acquisition costs.

Disadvantages: the heat transfer temperature is not as high as the heat storage type, appeared later, has not been generally used.