The Application of Low-temperature Ventilation Technology In Grain Storage Silos

Steel silos are mainly used to store bulk small block and powder materials. It has the characteristics of good air tightness, short construction period, low cost, and small floor area. In the grain industry, steel silo is a kind of essential storage equipment (usually called grain storage silo) used for storing various types of grains. Considering the special characteristics of grain, such as easy mildew, we will apply some corresponding technologies to ensure its safe storage. The low-temperature ventilation technology is one of the most important.

Characteristics of Grain

The grain is an organism of life, with respiratory function. When it is in wide contact with air, it will produce aerobic respiration, generating carbon dioxide, water, and heat. When it is in an anoxic condition, it will produce anaerobic respiration and internal oxidation-reduction reaction, generating alcohol, carbon dioxide, and heat. Both of the two conditions cause high grain temperature and humidification, thus speeding up the grain respiration process.
The moisture content in the grain heap tends to move slowly from the inside of grain to its surface and then to the air in the grain gap. They gather between grains and begin to condense when they reach a saturation point, resulting in fermentation and temperature rise. At the same time, the dust, impurities, especially organic impurities in grain accelerate this process. Such a vicious cycle provides a powerful condition for the reproduction of mold and makes the grain moldy and spoil.

Conditions for Safe Grain Storage

The safe grain storage means that the grain is kept dry, fresh, and free of mold and insect infestation. According to the above analysis, we can know that the appropriate temperature and moisture are two important factors to ensure the safe storage of grain.
Safe Storage Moisture
The safe storage moisture of grain refers to the highest water content of grain storage in a certain period without temperature rising and mildew. It strictly controls the respiration of grain and the occurrence of mildew.

Grain	Storage Quantity	Maximum Safe Moisture Content
Threshed corn & sorghum	1a	14%
Threshed corn & sorghum	More than 1a	13%
Soybean	1a	12%
Wheat	1a	13%
Sunflower seed	1a	9%

Safe Storage Temperature
For insect pests, 20-30 ℃ is the most suitable temperature for breeding. The most suitable temperature for microorganisms is 28-30 ℃. If the temperature is controlled below 10 ℃, it can inhibit the growth of microorganisms, prevent mildew, and thus avoid the damage to grain. Therefore, a low temperature is crucial to grain storage. It has the following functions:
Reduce the respiration intensity of grain
Low-temperature storage reduces the respiration intensity of grain and reduces the dry matter consumption of grain.
Inhibit the growth and reproduction of pests and mildew
At 5℃-10℃, even if the moisture content of the grain is 18% and the storage period is eight months, microbes are less likely to develop. When the temperature is below 0℃, most fungi do not grow.
Delay the grain aging and keep the fresh quality
It is well known that the low-temperature storage helps to protect the quality of grain and seeds. For every 5℃ decrease in temperature, the life of seeds doubles.

Water Content	Temperature To Prevent Mold Propagation	Temperature To Prevent Pest Propagation
17%	13℃	Lower than 17℃
18%	11℃	Lower than 17℃
19%	9℃	Lower than 17℃
20%	8℃	Lower than 17℃
21%	6℃	Lower than 17℃
22%	5℃	Lower than 17℃

The Low Temperature & Ventilation Technology

Ventilation and low temperature are important means to maintain the stability of steel silo grain storage. Reasonable control of the storage temperature and humidity of grain is very important. So nowadays, most of the grain steel silos are equipped with an automated ventilation system and temperature control system. They exhaust the accumulated heat in the grain pile, reduce the temperature difference between inside and outside the silo, prevent moisture transfer caused by the diffusion of moisture and heat in the grain pile to improve the stability of steel silo grain storage.
Flyer is one of the professional steel silo manufacturers in China. The spiral steel grain storage silos produced by us obtain the ISO9001:2000 quality management system certification and have a fair price. We provide a series of sustainable solutions for the various aspects of storage projects, including product design, manufacturing, installation, and maintenance. If you are interested in our products, please feel free to contact us!

Date	7/1	4/2	31/3	20/5	15/9	27/9	20/10	10/11	11/12
No Ventilation (℃)	16.8	11.1	8.9	21.1	27.8	27	27	29.1	23.6
Ventilation (℃)	6.5	7.0	7.2	20.9	27.4	19.1	18	9.9	7.4
Temperature Difference (℃)	10.3	4.6	1.7	0.2	0.4	7.9	9.0	19.2	16.2

In a word, to achieve the goal of safe grain storage in the steel grain silo, the ventilation cooling, ventilation reducing water, and low-temperature storage must be implemented. It plays an important role in reducing and balancing grain temperature, stopping moisture condensation, controlling insect pests, preventing high temperatures, and reducing expenses.