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With the improvement of grain varieties, the improvement of yields and the increase of state investment in grain drying equipment, more and more large, medium and small grain drying facilities have been built. It is important to choose a dryer with high quality, long service life, economical and practical, high reliability and high degree of automation.
Model features
According to the relative movement direction of grain and airflow, the dryer can be divided into crossflow, mixed flow, downstream, countercurrent and forward flow, mixed reverse flow, and smooth mixed flow.
Cross flow dryer
The cross-flow dryer is the first type of machine introduced in China. It is mostly a cylindrical sieve hole type or square tower type sieve hole structure. There are still many manufacturers in China. The machine has the advantages of simple manufacturing process, convenient installation, low cost and high productivity. The disadvantages are: the uniformity of grain drying is poor, the unit heat consumption is high, and the drying of a variety of grains in one machine is limited. After baking, some grain quality is difficult to meet the requirements, and the inner and outer screen holes need to be cleaned frequently. However, the small circulating dryer can avoid some of the above disadvantages.
Mixed flow dryer
The mixed flow dryer is mostly a tower structure composed of a triangular or pentagonal box interlaced (fork) arrangement. Domestic manufacturers of this type of machine are more than cross-flow. Compared with cross-flow, its advantages are: (1) uniform supply of hot air, uniform moisture content after drying; (2) unit heat consumption is 5% to 15% lower; 3) Under the same conditions, the required fan power is small, and the consumption of drying medium is also small; (4) The variety of dried grains can be both dry and dry; (5) easy to clean and difficult to mix. The disadvantages are: (1) the structure is complicated, the manufacturing cost is slightly higher under the same productivity conditions; (2) a small part of the grain at the four corners of the dryer is slow.
Downstream dryer
The downstream dryer is mostly a tower structure combining a funnel-type intake port and a horn-shaped box exhaust passage, which is different from the mixed-flow dryer by a main air duct for supplying hot air, but by multiple (levels) The hot air duct supplies different or partially identical hot air. The number of domestic manufacturers is less than that of mixed-flow dryer manufacturers. The advantages are: (1) the use of hot air is high, and the temperature of the first-grade high-temperature section can reach 150-250 °C; (2) the unit heat consumption is low, which can ensure the grain after baking. (3) The dryer above the three-stage downstream has the advantage of reducing the water and can obtain higher productivity; (4) The maximum precipitation is continuous during continuous drying, generally up to 10% to 15%. (5) The most suitable food crops and seeds for drying large water. The disadvantages are: (1) the structure is more complicated, 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, and the high-pressure fan required is high in power and high in price.
Smooth flow dryer
Pure counter-current dryers are rarely produced and used. Most of them are used in conjunction with dryers for other airflows, ie for the cooling section of downstream or mixed-flow dryers, forming a counter-flow and mixed counter-flow dryer. The advantage of countercurrent cooling is that the natural cold air can be fully contacted with the grain, which can increase the cooling rate and appropriately reduce the height of the cooling section. The counter-reverse flow, mixed counter-flow and smooth mixed-flow dryers respectively utilize their respective advantages to achieve high-temperature rapid drying, improve drying capacity, increase unit heat consumption, and ensure uniform grain quality and moisture content.
Device Selection
Different dryers can be used for different food varieties. For example, wheat, rice-based grain production areas can choose mixed-flow, mixed-flow type dryers. For corn-based production areas, multi-stage downstream high temperature quick dryers are available. For example, in rice-based production areas, low-temperature, large-slow-segment dryers such as countercurrent flow and mixed countercurrent flow are available. Different foods have different drying processes and different drying temperatures. Different types of drying processes and dryers can be selected depending on the amount of grain during the drying period. If there are many varieties of food, a small amount or scattered food, a small batch (circulating) dryer or a small mobile dryer should be used. If the variety is single, the quantity is large, and the drying period is short, a large continuous dryer should be used.
Production capacity
The equipment of the dryer should not be small, because in most cases, when the rainy season is encountered during the harvest season, it is necessary to play the role of the dryer. The large amount of drying and the small productivity cannot solve the problem. National and local reserve banks, large and medium-sized dryers should be built in the production areas where food is concentrated. The service radius of the fixed dryer should be small and not large, so as to reduce the transportation distance, reduce the cost and improve the efficiency. The mobile dryer can be used in rural areas where grain production is not concentrated and in small grain-producing areas in the south. The productivity is generally 2~5t/h, which is too small, not popular with users. It is best to use more than one machine, not only for grain and Grains are also suitable for some cash crops. The radius of the service should be larger to play the role of a mobile dryer.
Corn dryer automatic degree, long service life, economical and practical
The corn dryer is ideal for drying grain and oil. The processed product is fed from the top of the tower and passed through the feeder to ensure that the equipment is always fully loaded during operation. The inwardly turned bottomless V-shaped baffle and the multi-row V-shaped baffle arranged in a staggered arrangement allow the processed product to be mixed, and also serve as an inlet and outlet passage for the dry air, and the fan sends the used gas. Into the collector, purified, most of the dry air can be recycled, so the fuel consumption is very small.