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Safe production of coal mill system in cement plant

Date:2019-08-19 15:30 Source:cementepcViews:

In the current cement production process, a large amount of fuel is needed as a guarantee, and coal is the main fuel.Coal burning in cement production needs the support of coal grinding system.In the operation of coal mill system, there are many unsafe factors, easy to cause safety accidents, so how to adopt effective measures to ensure the safety production of coal mill system is the key content of cement plant safety management.
 

1. Potential safety hazard of coal mill system

 

1.1 spontaneous combustion


The cement production process requires the use of large amounts of coal.And the use of coal is mostly in the form of pulverized coal.Pulverized coal needs to be prepared in advance and stored to eliminate the impact of coal supply supplement on cement production.During storage, combustion powder will be oxidized in contact with air, especially after a large amount of coal powder is accumulated, the oxidation reaction will be more intense.Oxidation reaction will continue to exothermic, if the exothermic process heat dissipation effect is not good, it will cause spontaneous combustion.
 

1.2 cause an explosion


Cement production using the pulverized coal, so need through the pulverized coal system of coal grinding, grinding after particularly fine coal dust, dust collection efficiency is not good, if the production area will be suspended in the air of a large number of pulverized coal, pulverized coal after it is exposed to air, if after reaching a certain critical value, can produce intense oxidation reaction, explode.The explosion of coal mill system in cement production is related to many reasons, so we should pay attention to control the concentration, temperature and oxygen content of coal in the air.In the safety management of cement plant, the coal mill should be operated in order to control the explosion.

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2.Key points of safety management for cement production coal mill system

 

2.1 strengthen the management of hidden dangers in production


In the management of cement enterprises, it is necessary to realize the potential safety risks of coal mill system and strengthen the management according to the dangerous factors existing in production.The management of coal stacking should be strengthened.Fuel storage to consider the environment, eliminate the presence of fire in the surrounding area.

Different management methods are adopted according to the thickness of coal, and volatile characteristics of coal are also taken into account. Targeted safety management measures are adopted in daily safety management combined with the characteristics of different coal.For fine pulverized coal or high volatile content of the coal should pay attention to the control of piling compaction and height.Secondly, it is necessary to ensure the stable state of coal.The safety management of coal grinding system should pay attention to the reliable operation of relevant instruments.The waste gas produced by the coal mill system should also be better managed to eliminate air leakage and avoid overheating.Also to ensure drying conditions, to the lowest temperature of coal mill production, mill inlet area temperature control should be combined with volatile matter, to control as far as possible in a safe range.

The carbon monoxide concentration in the coal bin area should be monitored to detect the change of carbon oxide concentration in the air, which is conducive to the early detection of hidden dangers and the adoption of preventive measures.In addition, to ensure the reliability of explosion-proof valve, explosion-proof valve should be checked regularly to ensure the reliability of its function.

 

2.2 use of high-risk fuels


In terms of the current cement production process, fuel is the base material for cement production.So the coal mill system USES a variety of high-risk fuels.The use of high-risk fuels has great safety risks. If there is no scientific and standard management, it will easily lead to spontaneous combustion and explosion.Therefore, the safety management of coal mill system should take the characteristics of high-risk fuels into consideration, and the production operation should be in strict accordance with relevant regulations.Coal mill system to strengthen the management of explosion protection, safety equipment and safety facilities to check regularly.For example, the blowout valve should be controlled under the condition of self-reset and checked regularly.Lead outside;Coal mill body and dust collector and other related equipment to ensure reliability;For fuel characteristics to strengthen inspection, clear dust gas ignition temperature, fuel dust oxygen content and control.To determine the ignition temperature of dust gas, the inlet gas temperature of the mill can be reasonably controlled.Determining oxygen content of fuel dust can ensure reasonable control of dust collector content.In addition, we must strengthen the management of fire fighting system to ensure the function of fire fighting system.
 

2.3 temperature control


The safety hidden danger of coal mill system in cement production mainly comes from spontaneous combustion and explosion, so the control of temperature should be paid attention to.In the operation of coal mill system, temperature control is helpful to reduce the reliability of coal mill system explosion or fire, so the temperature in production should be controlled.

It mainly includes the following contents: alarm temperature in high position condition and valve closing temperature in limit condition.The temperature control should be in accordance with the relevant standards to ensure that the coal mill system operating conditions in a safe temperature range.High alarm temperature should ensure reasonable temperature control under limit conditions.System valves should close quickly if the temperature exceeds the limit.The limit temperature is the direct cause of spontaneous combustion. The reasonable control of limit temperature can reduce the possibility of spontaneous combustion.

 

2.4 control of raw coal stacking


In order to control spontaneous combustion of coal pile, storage of raw coal under normal conditions should consider the influence of storage period and volatile content.The storage period of raw coal with volatile content less than 15% should be controlled within 4 months.The volatile limit of raw coal is 15%~25%, and the storage period should be controlled within 3 months.The volatile limit of raw coal is 25%~35%, and the storage period should be controlled within 1 month.The storage period of raw coal volatiles higher than 35% should be controlled within 4 weeks.In addition, the cement plant for coal storage and consideration of height.The height should be controlled according to the standard.The volatile boundary of raw coal is 15%~25%, and the height is less than 10 meters.The volatile boundary of raw coal is 25%~35%, and the height of coal pile is less than 8 meters.The volatilization of raw coal is higher than 25% and the height is lower than 6 meters.
 

2.5 control spontaneous combustion


Of coal pile up want basis standard in order to assure safety, pile up want to control occurrence slump, pile up want to assure neat, can use the way of mechanical compacting, eliminate the generation of pore, eliminate air to enter coal seam to bring about oxidation reaction.In the storage of raw coal but also eliminate dead material area, the design of the bunker to be reasonable, for easy to send dead material area to ensure a certain inclination Angle, dead material area to facilitate the slide of coal seam, but also consider the impact of coal wind pipe, and the level of the included Angle to be reasonable.In order to eliminate the accumulation of pulverized coal due to Angle problems, an included Angle can be set under special conditions, and the maximum included Angle cannot be greater than 5°.In the upper part of the bunker and dust concentration area, the temperature monitoring device should be installed to effectively monitor the temperature and prevent spontaneous combustion of coal seam.The grinding and dust collecting systems are prone to spontaneous combustion in the preparation of pulverized coal.In the coal mill area, the reliability of fire protection facilities should also be ensured. Usually, foam extinguishing devices are used. Considering the rationality of the location, foam extinguishing devices are usually placed at the entrance of the mill and near the dust collector.
 

2.6 controlled explosion


Under normal conditions, the explosion control of coal mill system should consider the influencing conditions: the dispersion condition of combustible material;The concentration of combustible material is close to the critical range;Explosive gas content reaches dangerous value;A source of fire, etc.In addition, the explosion-proof valve to ensure that reliable, through regular inspection to eliminate hidden dangers.
 

3. Summary


Cement production enterprises should strengthen the safety management of coal mill system, in view of the hidden danger of coal mill system, cement production enterprises should improve the safety management system, take active preventive measures, grasp the key points of safety management, strengthen the process control of coal mill production, reduce the possibility of safety accidents.

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