Grain dryer: According to the relative movement direction of grain and airflow, dryers can be divided into cross-flow, mixed-flow, downstream, counter-current, downstream, downstream, etc.

1. Cross flow dryer

The cross-flow dryer is one of the first imported models in my country, mostly with cylindrical sieve or square tower sieve structure, and there are still many domestic manufacturers.

The machine has the advantages of simple manufacturing process, convenient installation, low cost and high productivity. The disadvantages are that the grain drying uniformity is poor, the unit heat consumption is high, and the variety of grains dried by one machine is limited, and the quality of some grains after drying is difficult to meet the requirements, and the inner and outer sieve holes need to be cleaned frequently. But small circulation dryers can avoid some of the above disadvantages.

2. Mixed flow dryer

The mixing dryer is mainly a tower structure composed of triangular or pentagonal boxes arranged in a staggered (fork) manner. There are more domestic manufacturers of this model than horizontal flow. Compared with horizontal flow, its advantages are: (1) hot air supply is uniform, and the moisture content of grain after drying is uniform; (2) unit heat consumption is 5%~15% lower; (3) under the same conditions, the fan power The unit consumption is small; (4) There are many kinds of dry food, both dry food and dry food; (5) Easy to clean and not easy to mix.

The disadvantages are: (1) the structure is complicated, and the manufacturing cost is slightly higher under the same productivity; (2) a small part of the grains at the four corners of the dryer is slow to rain.

3. Downstream dryer

Downstream dryers are mostly tower structures with a combination of funnel-type inlets and corner-box exhausts. Unlike mixed-flow dryers, which are heated by one main air duct, they are heated by multiple (stage) hot air ducts. Or part of the same hot air.

The number of domestic manufacturers is less than that of mixed-flow dryer manufacturers, and its advantages are: (1) The temperature of the hot air is high, and the temperature of the first-level high-temperature section can generally reach 150~250°C; (2) The unit heat consumption is low, which can ensure the quality of grain after drying (3) Dryers above three levels have the advantages of precipitation and high productivity; (4) The precipitation range is large during continuous drying, generally up to 10%~15%; (5) Most suitable for drying food crops and seeds with large moisture content .

The disadvantages are: (1) the structure is complex, and the manufacturing cost is close to or slightly higher than that of the mixed flow dryer; (2) the thickness of the grain layer is large, the power of the high-pressure fan required is large, and the price is high.

4. Downward and countercurrent, mixed and countercurrent, forward and mixed flow dryers

Pure countercurrent dryers are rarely produced and used, and are mainly used together with other airflow dryers, that is, the cooling section of cocurrent or mixed dryers, to form cocurrent and mixed countercurrent dryers. The advantage of counter-current cooling is that the natural cold air can fully contact the grain, which can increase the cooling speed and reduce the height of the cooling section appropriately. Downstream, mixed countercurrent and downflow dryers use their respective advantages to achieve high-temperature rapid drying, improve drying capacity, and ensure uniform grain quality and moisture content without increasing unit heat consumption.