Prevention of Grain Silo / Fly Ash Silo Dust Explosion

Causes and hazards of dust explosion

With the improvement of application technology of grain silo/ fly ash steel silo, steel silo has become the mainstream of these industries. However, in the past 20 years, the dust explosion accident rate of steel silo is on the rise. It is reported that in some developed countries with advanced technology and equipment, dust explosion is always happened, too. The reason is that the management of steel silo is irregular, the operation is improper, the responsibility of personnel is not enough, the safety consciousness is not strong, and the design and construction of dust proof and explosion proof of steel silo is not reasonable.

Dust explosion not only brings environmental pollution, but also causes serious personal injury and serious economic loss. Therefore, it is necessary to take safe and effective preventive measures to prevent dust explosion, which should be paid enough attention to. Only by considering all kinds of influence factors and taking comprehensive preventive measures from design can dust explosion be effectively controlled and in other words, dust explosion accidents can be prevented.

Measures to prevent dust explosion

Management of steel silo

Strengthen management, raise awareness, enhance responsibility. Strengthen the education of safety knowledge of silo dust explosion, actively carry out safety training, strengthen the prevention consciousness of dust prevention, fire and explosion,  formulate strict safety work system and strictly abide by, operate in strict accordance with operation rules, actively do well clean and sanitary in and outside the steel silo area, maintain good ventilation conditions in the steel silo. At the same time, do a good job in daily safety management.

In order to do a good job of comprehensive safety inspection, all kinds of dangerous factors of dust explosion must be seriously analyzed. The safety inspection should be comprehensive and targeted, solve the problem in time, and never leave any hidden trouble.

Strengthen the equipment and management of safety facilities. There should be a complete fire control system in the steel silo area. Operators should be familiar with the performance of equipment and tools, use conditions and operating essentials, and do a good job of maintenance. It is strictly prohibited to conduct heat source operations such as electrical cutting and welding in the area without fire working conditions. Safety precautions should be taken when such operations are necessary. After the operation, to do a thorough inspection, eliminate all hidden dangers, to ensure the storage safety of steel silo.

Design and construction of steel silo

Starting with the design, try to eliminate the factors affecting the dust explosion in the following aspects:

Adopt more advanced dustproof and explosion-proof technology

Spray dust suppression technology not only improves the present dust control methods, but also broadens the existing new ideas for dust control. The technology has a good effect on the fine dust below 30μm. It can adsorb the dust and the regenerative dust in the process of processing on the grain surface, avoid flying, and help to control the dust explosion fundamentally. According to the related data, the white oil produced by Esso Company of America is used as dust repellent and the dosage is 2% of the mass flow rate, the dust can be effectively controlled. In the world, many developed countries have widely used this new technology in grain silo and transportation management, and achieved good results. But the technology needs further research and improvement.

Safety of Flyer Steel silo

Flyer steel silo is fully considered the problem of dust and explosion in the design process, the above mentioned various possible accident factors, can be professional design based on the needs of customers. In addition, the use and management of steel silo, Flyer can provide professional guidance on relevant training and management. So that once you choose Flyer steel silo, you are assured of safe use, Flyer relieve your worries.

• Do a good job of overall planning and design, follow the principle of overall fortification.
  The production process should be as close as possible, automation, for buildings, machinery and equipment with explosive danger should be set up a special safety wall and isolation zone (such as: firewall, green belt, fire doors, etc.), and appropriate use of fire-proof materials. For lightning protection, grounding, static control and fire protection design, safety and reliable preventive measures should be taken.
• In the structural design of the silo, the silo should be equipped with ventilation window, vent, inspection hole and other safety devices to maintain the atmospheric pressure in the silo.
  Steel silo and silos should be equipped with material level in order to send out full-bin signals to prevent hoist and conveyor from clogging. In order to achieve the purpose of releasing explosion, the explosion-proof windows should be set up for local vulnerable places (such as corridor, trestle and so on). Use lightning rod or lightning belt, etc.
• Ventilation and dust removal process design.
  Reasonable ventilation and dust removal technology plays a positive role in preventing dust explosion. It is important to select the appropriate parameters and methods at design time. 15-17m/s is the best wind speed in the air duct. Collect the dust directly at the dust generating point, after the dust collector purifies, row to the outdoor. Adopting a combination of partial ventilation and suction, full ventilation or natural ventilation (using external air pressure or temperature difference). At the same time, considering the uniformity of negative pressure in the suction pipe, grain particles, dust particles, equipment and their mutual collision, friction, uniformity of velocity in the pipe, the air cap should be installed at the outlet. When designing the wind net, the equipment such as removing stone and cleaning should design the wind net independently, and the conveying and lifting system should set up the combined wind net. The ventilation and dust removal system shall be interlocked with the relevant electrical equipment.
• Try to use vacuum cover, shield.
  Choose the suitable position of suction point and the structure form of wind cover, especially for the part of lower grain, should be formed wind belt with the outside world, and be prevented dust from flying. The dust is confined to a smaller range by installing a dust hood near the dust source, which ensures that there is enough negative pressure in the air suction cover without causing dust diffusion. The airflow in the cover is uniform, the contraction angle is not greater than 60 °, and the wind speed is generally 3-5 m/s (0.5-1.5 m/s). When the dust concentration is high, the specific gravity is large, and the distance between the suction port and the dust source is long, the wind speed of the suction port should be taken as large value, otherwise the value should be taken as small value. Otherwise, dust will spread seriously. After adding flange around the dust trap, the invalid airflow should be reduced, the suction volume can be saved by 25%, and the design wind speed may be 0.5-2.5 m/s. Because of the technical limitation, the open suction hood and the external air suction cover can be used when the mechanical equipment can not be sealed. There should be a shield at the air suction orifice, such as a fan.
• In the design of transportation process, the process flow should be brief, the equipment should be arranged reasonably, the equipment should be equipped with dust proof and explosion proof matching device and be sealed as far as possible, and magnetic separation equipment should be used as far as possible. The higher dust concentration is suitable for secondary purification. A reasonable dust shield must be designed for the feeding and throwing ends of belt conveyors. The dust source is flowing because the conveyer adopts the unloading car, so it should be designed reasonable dustproof device. Bucket hoist should be installed at the base of the air suction device and the use of electrical conductivity and non-flammable tape, the bucket should be plastic. The structure of spiral conveyer is very tight, but when the grain drop is large, the expanding box should be set up in the lower part of the air suction cover. Bucket hoists, conveyors and other conveyors shall be equipped with speed measuring devices, spray fire fighting devices, conveyor belt sliding and running off devices. When weather and operating conditions permit, roof scraper, hoist head, dust collector and other open-air arrangement. All mechanical and electrical equipment take grounding measures to prevent electrostatic accumulation.
• In the electrical design, lamps and wires should be used as explosion-proof type. The motor should adopt vibration absorber to reduce dust flying and diffusion. Design, should follow the principle of overall defense, dust-proof explosion-proof supporting design.