1. Direct high-purification biomass hot air boiler
It is the direct combustion of the fuel, the high-purification treatment to form the hot air, and the material is directly contacted by heating, drying or baking. This method consumes about half as much fuel as steam or other indirect heaters. Therefore, direct high-purification hot air can be used without affecting the quality of the dried product.
The high-temperature combustion gas obtained by the combustion reaction of the fuel is further contacted with the outside air, and after being mixed to a certain temperature, directly enters the drying chamber or the baking room, contacts the material to be dried, and heats and evaporates the water to obtain a dried product.
2. Indirect biomass hot air boiler
It is mainly suitable for the dry materials not allowed to be contaminated, or applied to the drying of heat-sensitive materials with lower temperature. Such as: milk powder, pharmaceuticals, synthetic resins, fine chemicals, etc. Such a heating device uses steam, heat transfer oil, flue gas or the like as a carrier to heat the air through various forms of heat exchangers.
The most essential problem of indirect biomass hot air boilers is heat exchange. The larger the heat exchange area, the higher the heat conversion rate, the better the energy saving effect of the hot blast stove, and the longer the life of the furnace body and the heat exchanger. Conversely, the size of the heat exchange area can also be identified from the temperature of the flue gas. The lower the temperature of the smoke, the higher the heat transfer rate and the larger the heat exchange area.
Working principle can be divided into regenerative and heat exchange
According to the regenerative type, the regenerator ball-type hot blast stove (referred to as the ball furnace) and the hot blast stove using the checker bricks in the hot blast stove can be classified into a top-burning type, an internal combustion type, and an external combustion type according to the combustion method. How to improve the wind temperature is the direction of long-term research in the industry. Commonly used methods are mixed high-calorie gas, or increase the heat exchange area of the hot-blast stove, or change the material and density of the brick, or change the shape of the heat storage (such as heat storage balls), and the gas by various methods. Preheating with combustion air.
Advantages: high heat exchange temperature and high heat utilization rate.
Disadvantages: large size, large battlefield area, unstable hot air temperature, many switching mechanisms, easy problem, short life of regenerator, high maintenance cost, and high purchase cost.
The heat exchange type is mainly used as a core component using a high temperature heat exchanger, and this component cannot be used.
Advantages: high heat exchange temperature, high heat utilization rate, small volume, stable hot air temperature, no switching mechanism, long service life, high maintenance cost and low purchase cost.
Disadvantages: The heat exchange temperature is not high in regenerative heat, and it appears late and is not commonly used.