In recent years, all parts of our country have paid close attention to environmental protection, especially the control and prevention of industrial pollution emissions, and achieved initial results. But at the same time, the impact on some industrial sectors is inevitable. Taking the grain dryer industry as an example, the heat source part is an important part of the grain dryer, and the traditional grain dryer heat source is mainly coal. With the implementation of the "coal ban" in various places, grain dryers have to seek new heat sources to replace the more polluted coal, which puts forward a new topic for the national grain dryer manufacturers. For a long time, the grain industry is a low value-added industry, and the development of the industry has always been a state of "small profits but quick turnover, winning by quantity. Coal, as a traditional energy source, has been used as the heat source of grain dryer because of its "low price and easy access. However, under the pressure of national environmental protection policy, manufacturers have to develop new alternative energy programs to ensure the normal use of grain dryers under the premise of meeting environmental emissions. At present, the main alternatives are: natural gas, air energy heat pump, biomass particles, steam and other ways. The following is the successful experience of Zhengzhou Wangu Machinery Co., Ltd. for more than 20 years, focusing on grain dryers, respectively, to introduce different energy methods.

Natural gas is a kind of clean energy. In the case of full combustion, it mainly generates non-toxic carbon dioxide and water, and produces a very small amount of sulfur dioxide and nitrogen oxides. Because the content is very low, it has little impact on the environment and can be ignored. Therefore, the combustion exhaust gas of natural gas can be discharged directly without treatment. Therefore, the gas hot blast stove is more and more used in the grain drying industry. Users usually use fixed natural gas pipelines or natural gas transport vehicles and other non-fixed ways to supply the required natural gas.

Steam heat exchanger is a kind of heat exchange equipment that uses steam to heat air at room temperature when it condenses. It has the advantages of cleanliness, cleanliness, easy control of air temperature, and simple operation. The air at room temperature can be directly used as a grain dryer after being heated. The drying medium is used. This method is generally only applicable to the occasion of large-scale industrial steam resources near the grain dryer factory area, especially the grain dryer built by some large grain deep processing enterprises, because the factory area is usually equipped with large-scale steam boilers, and there is surplus industrial steam available. At present, Zhengzhou Wangu has successfully built dozens of steam grain dryers with a daily output of 1000 tons in Northeast, Northwest, Henan and other provinces.

Biomass pellet fuel is a granular new energy fuel produced by processing straw, rice husk, firewood, peanut shell, corncob, camellia shell, cottonseed shell, etc. Since biomass pellet fuel does not contain sulfur and phosphorus, it does not produce sulfur and phosphorus oxides during combustion, which will not cause acid rain and cause less environmental pollution. There is very little ash after the combustion of biomass pellet fuel, which can reduce the site for stacking slag, and the ash after the combustion of biomass pellet fuel is organic potash fertilizer, which can be recycled to create profits. Generally, biomass particles have the characteristics of small bulk density, low calorific value, and more fine dust after combustion. Therefore, the furnace structure and exhaust dust removal of hot blast stoves need to be optimized to meet the heating and environmental protection dust emission standards of grain dryers.

Air energy heat pump is a kind of drying form that uses electricity as energy to absorb and convert the energy in the air into heat energy. Air energy heat pump technology, with its advantages of clean and pollution-free, has been gradually applied in the field of grain dryer in recent years. However, due to the limitations of the working principle of heat pump technology, the current technology is mostly used in small grain dryer equipment, and the use is limited by the region, often used in the warm areas of the south, and mostly used as a heat source for low-temperature rice drying.