In most parts of China, grain moisture is generally higher than the safe moisture postpartum (14%), is not conducive to storage, storage, use of natural precipitation, not only time-consuming, laborious, accounting for space, but also difficult to achieve the purpose of the desired effect. So many food banks are using artificial rainfall. By grain drying method, it can be divided into the dryer; dryer heat convection, conduction drying dryer, dryer and high-frequency electric field of radiation drying machines. Among them, the conduction drying dryer in the early 1980s and 1990s has been widely used for food companies. This dryer also known as steam boilers, storage silos, pre-heating tower, drying tower, cooling towers and a variety of transportation equipment. Its advantages are: large rainfall, one can of precipitation in 10% -15%, the production capacity, high degree of automation. The disadvantage is the high cost, fuel consumption, maintenance inconvenient. The dryer works are:

Grain drying flowchart This drying method, steam is not directly in contact with the food, but through metal pipes, food pipeline flowing outside to absorb heat, after heating food temperature, its internal moisture transfer from the surface of vaporization, the vaporization of the water away from the drying medium , thereby reducing grain moisture. According to their works, saving measures are as follows: 1. An improved drying medium. For grain drying time can be mixed with steam and take a substance known as drying medium. According to the definition of the apparent drying medium, if the drying medium to maximize the drying process of heating food; and to continue to vaporize water vapor away, then the food will be dry. And it depends on the capacity of the drying medium package of water vapor, that is, absolute humidity of the air. The number of different absolute humidity of air at different temperatures, at a certain temperature, wet air contain water vapor there is a limit, when the water vapor in the atmosphere to accommodate the number of water vapor in the air condenses as a dynamic equilibrium when the amount of water which contain water to maximize the number of steam, when the air is called saturated air, its absolute humidity is called absolute saturation humidity. The same kind of air saturation at different humidity humidity values are different, such as 20 ℃ saturated humidity value of 17.2g / m3,34 ℃ when compared to 37.3 g / m3. Visible, saturated humidity higher the value, the drying capacity stronger. Conventional steam dryers, flue gas after the preheating tower on into a large vapor, not only pollute the environment, but also a waste of energy. In order to improve energy use efficiency, the flue gas can be directly used as the drying medium. After specific transformation approach is preheated flue gas directly into the heating tower from the smoke box. This would at no additional heat source under the premise that the most effective way of raising the temperature of the drying medium. It should be noted in production should pay attention to the furnace gas temperature, if the temperature is too high will affect the quality of food, the temperature of the drying medium in general should be controlled between 80 ℃ -130 ℃. 2, drying - ventilation drying. The traditional drying method is usually dried to a moisture content of grain by 14% -15%, then cooled storage. The drying - dry air law first high-temperature drying of grain. It dropped to 18 percent water, and then the moisture of the food into the warehouse tempering 5-7 hours, so that food grains between internal and surface temperature and moisture tend to balance, then subjected to a slow ventilation, air volume 25m3 a 50 m3 / h, ventilation time of about 8 hours, so that the temperature of the food and the atmosphere at the same temperature, the higher the grain temperature is usually fed into the bins, the more moisture is removed (about 4% or so). The advantage of this method is as follows: (1) increasing the drying capacity. Due to water drops of 14% rather than 18%; (2) reduce energy consumption. Because the food is low precipitation in the device; performing tempering process, when the slow ventilation, use of food itself further precipitation heat savings. (3) to ensure food quality. After drying grain because the direct cooling often cause food grain fissuring, and the use of this law to reduce crack ratio, broken rate; (4) the use of this method can reduce the drying cost about 13%.