Comprehensive prevention and control measures of d

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Comprehensive prevention and control measures for dust explosion in grain silos

with the improvement of the application technology of grain silos, especially steel plate silos have become the mainstream type of silos in the grain and oil industry. However, the dust explosion accident rate of grain silos in grain and oil processing plants and feed plants has increased in the past 20 years. It is reported that in some developed countries with advanced technology and equipment, the phenomenon of dust explosion is very serious. Dust explosion not only brings environmental pollution, but also causes serious casualties and heavy economic losses. Therefore, it is very necessary to take safe and effective prevention and control measures to prevent dust explosion, and people should pay enough attention to it. The author believes that starting from the design, considering various influencing factors, comprehensive prevention and control measures should be taken to effectively control dust and prevent dust explosion accidents

1. Strengthen management, raise awareness, enhance heart

1.1 strengthen the education of silo dust explosion and safety knowledge, actively carry out safety training, strengthen the awareness of dust prevention, fire prevention and explosion prevention, formulate a strict safety work system and strictly abide by it, operate in strict accordance with the operating procedures, actively clean the inside and outside of the reservoir area, and maintain good ventilation conditions in the silo. At the same time, do a good job in daily safety management

1.2 do a good job of comprehensive safety inspection. We must carefully analyze various risk factors of dust explosion. The safety inspection should be comprehensive and targeted, and the problems found should be solved in time without leaving any hidden dangers

1.3 strengthen the allocation and management of safety facilities. There should be a complete fire-fighting system in the reservoir area; Operators should be familiar with the performance, use conditions and operation essentials of equipment and tools, and do a good job of maintenance; It is strictly prohibited to carry out electric cutting and welding and other operations that are easy to generate heat sources in the reservoir area without fire operation conditions. When such operations must be carried out, relatively safe precautions shall be taken. After the operation, a thorough inspection should be carried out to eliminate all hidden dangers and ensure the safety of grain storage in the silo

2. Starting from the design, try to eliminate the factors affecting dust explosion

2.1 do a good job in the overall planning and design of the reservoir area, and follow the principle of overall fortification. The production process shall be sealed and automated as far as possible; Special safety walls and isolation belts (such as firewalls, green belts, fire doors, etc.) should be set up for buildings and mechanical equipment with explosion hazards, and appropriate fire-proof materials should be used; The lightning protection, grounding, anti-static and fire protection design should be comprehensively considered and safe and reliable preventive measures should be taken

2.2 in the structural design of the vertical silo, the vertical silo should be equipped with ventilation windows, explosion vents, inspection holes and other safety devices to maintain the atmospheric pressure in the silo; A level gauge shall be set in the silo and silo to send a full bin signal and prevent the hoist and conveyor from blocking; Explosion proof windows shall be set in places that are easy to be damaged locally (such as corridors, trestles, etc.) to achieve the purpose of explosion relief; Adopt lightning rod or lightning strip, etc

2.3 ventilation and dust removal process design. Reasonable ventilation and dust removal technology plays a positive role in preventing dust explosion. It is very important to choose appropriate parameters and methods in design. The best wind speed of air duct is m/s; The dust is collected directly at the point of dust generation, and then discharged outdoors after being purified by the dust collector; Adopt a combination of local exhaust and suction, and fully ventilated or naturally ventilated (using external wind pressure or temperature difference). At the same time, considering the uniformity of negative pressure in the suction pipe, the collision and friction between grain particles, dust particles, equipment and each other, and the uniformity of velocity in the pipe, a hood should be set at the air outlet. When designing the air, the stone removal, cleaning and other equipment should design the air independently, and the conveying and lifting system should be equipped with combined air. Ventilation and dust removal system shall be interlocked with relevant electrical equipment

try to use dust suction cover and protective cover. Select the appropriate position of suction point and the structural form of wind cover, especially for the grain feeding part, so as to form a wind belt with the outside world during grain feeding, so as to prevent dust flying. Install a dust hood near the dust source to limit the dust to a small range, that is, to ensure that there is sufficient negative pressure in the dust hood without causing dust diffusion. The air flow in the hood is uniform, the contraction angle is not greater than 60, and the wind speed is generally selected as m/s (grain), 0 5m/s (powder). When the dust concentration is large and the ratio is significant, and the distance between the suction port and the dust source is long, the wind speed at the suction port should be taken as the large value, and vice versa. Otherwise, the dust will fly and spread seriously. After adding orchids around the dust hood, the invalid air flow should be reduced, and the suction air volume can be saved by 25%. The wind speed can be 0% in the design 5m/s。 Due to process limitations, when mechanical equipment cannot be sealed, open suction hood and external suction hood can be selected. Protective cover shall be provided at the air intake of fan and other places

2.4 in the design of grain conveying process, the process flow should be brief, the selection and layout of equipment should be reasonable, dust-proof and explosion-proof supporting devices should be equipped and sealed as far as possible, and magnetic separation equipment should be used as far as possible. Secondary purification should be adopted for parts with high dust concentration. The feeding end and throwing end of the belt conveyor must be designed with reasonable dust cover. Because the conveyor on the top of the silo adopts the unloading trolley, the dust source is flowing, so a reasonable dust-proof device should be designed. The bucket elevator should be equipped with an air suction device at the base and adopt conductive and non combustible tape, and the dustpan should be of plastic type. The screw conveyor has a tight structure, and generally there is no dust-proof device, but when the grain drop is large, an expansion box should be set under the suction hood. Bucket elevators, conveyors and other conveying equipment shall be equipped with speed detection devices, spray fire-fighting devices, conveyor belt slipping and deviation devices. When the climate and operating conditions permit, the scraper on the top of the warehouse and the hoist head can promote the development of new materials and the use of integration, dust collectors and other outdoor arrangements in other fields. Grounding measures shall be taken for all electromechanical equipment to prevent static electricity accumulation

2.5 in the design of electrical appliances, lamps and wires should be of correct specifications and models, and should be explosion-proof, meeting the requirements of Chapter III of the code for design of electrical installations in explosive and fire hazardous environments and relevant standards. The motor should adopt vibration damping device to reduce dust flying and diffusion. During the design, the principle of overall fortification should be followed, and the supporting design of dust and explosion prevention should be done well

3. Adopting the new dust-proof and explosion-proof technology

spray dust suppression technology not only improves the current dust control methods, but also broadens the existing new ideas of dust prevention and control. This technology has a good inhibitory effect on fine dust with a particle size of less than 30 m. It can adsorb the dust and the regenerative dust in the process on the grain surface. Whether it can go out of the investment face and avoid flying is conducive to the fundamental control of dust explosion. According to relevant information, the white oil produced by Esso company of the United States is used as dust-proof agent, and the dosage is 0.02% of the material flow for spray, which can effectively control the dust in grain. In the world, many developed countries have widely applied this new technology in grain storage and transportation management, and achieved good results. But this technology needs further research and improvement. In addition, the application of "the mechanical properties of spraying water mist prevention data to get the reactive explosion dust removal technology on the dial" can effectively suppress the dust flying, and the dust suppression effect is good, which is more suitable for grain and oil processing plants and grain transfer warehouses

in addition, in order to effectively prevent the dust explosion of grain silos, while actively taking dust removal and explosion-proof measures, we should also strengthen the dust removal and explosion-proof technical management and technical training during the use of silos

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