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author：EBICO 2019-10-21
Common boilers on the market are coal-fired boilers, oil-fired boilers, gas boilers, electric boilers, air source boilers, biomass boilers.This paper details the safety hazards and preventive measures of these six boilers.Help you to solve the boiler safety hidden trouble, avoid boiler accident.
There are mainly two kinds of hazards of coal-fired boilers. One is the safety hazard caused by soot emission of coal-fired boilers, and the other is the boiler hazard caused by coking of coal-fired boilers.The users of coal-fired boilers are mostly small and small enterprises. Due to the consideration of operating costs, they often use inferior coal and directly discharge it into the atmosphere without adopting desulfurization and dust removal equipment. This is one of the most important reasons for the current large-scale haze weather.Seven ministries and commissions have issued a plan to upgrade coal-fired boilers, phasing out and banning all new coal-fired boilers with less than 10 tons of capacity.
1. Safety hazards caused by soot emission from coal-fired boilers;
(1) the high sulfur content of inferior coal and the poorly handled flue gas contain a lot of smoke and dust, which is one of the most important reasons for the widespread haze weather. Electrostatic precipitators, bag precipitators and ink precipitators are generally adopted to solve the large emission of smoke and dust.
(2) in addition to the produce large amounts of coal burning. So, also generates a small amount of SO3. General S03 concentration in flue gas is 10 ~ 40 g/l. as smoke contains water (4 ~ 12), makes the generated. So instantaneously form the sulfuric acid mist. When the temperature is lower, sulfuric acid mist condenses into sulfuric acid, attached to the equipment on the inner wall, or dissolved in liquid detergent, corrosion of absorption tower and other related equipment. The solution includes: absorption tower with corrosion resistant materials, such as stainless steel, epoxy glass fiber reinforced plastic, hard PVC, ceramic, etc.;The inner wall of the equipment is coated with anticorrosive materials, such as water glass, etc.The equipment is lined with rubber, etc. The flue gas containing smoke and dust passes through the equipment and pipes at high speed, and is in contact with the turbulent agitation of absorption fluid in the absorption tower, causing serious wear and tear of the equipment.
2. Boiler hazards caused by coking of coal-fired boilers;
(1) coking will cause a high temperature rise of overheating steam, and lead to overheating steam temperature, reheat steam temperature dehydrating warm water to open up, and even lead to the explosion of soda pipe;Coking will reduce the boiler output and cause forced shutdown in serious cases.Coking will shorten the service life of boiler equipment;The loss of exhaust smoke increases and the efficiency of boiler decreases.The consumption of induced draft fan increases;Because coking is often uneven, water wall slagging will have an adverse effect on water cycle safety of natural circulation boiler and thermal deviation of water wall of forced circulation boiler.
(2) coke is easy to become a large piece of ash slag, slag dregs, slag crusher transport difficulties, sometimes overload trip, serious slag ditch blocked, had to reduce the load of operation.
(3) if the coke is fused into a large block, it will fall from the upper part due to gravity, resulting in breaking the water wall of the cold ash bucket.Low load will cause unstable combustion and even flame - out due to the loss of large coke.
(4) if the water wall is completely coking, only manual coke cleaning can be carried out by stopping the furnace.
(5) the boiler of large focal block off after the machine in dregs, instantly generate large amounts of water vapor, destruction of water seal machine in dregs, make the bottom leakage into the large amounts of cold air at the same time, due to the burner area (especially the lower burner area) the serious deterioration of pulverized coal flame ignition condition, make the hearth negative pressure produces volatility (transfinite) caused by the fire boiler.
3. Measures to prevent coking of coal-fired boilers;
(1) in terms of operation, preventive measures include:
(1) choose reasonable running oxygen, that is, the furnace oxidation or reducing atmosphere.
(2) choose a reasonable furnace outlet temperature.
(3) to ensure the good mixing of air and fuel, avoid the formation of a reducing atmosphere near the water wall, prevent local serious ash, coking.
(4) application of various operating measures to control the temperature level in the furnace.
The reasonable and good organization of the furnace aerodynamic field is the prerequisite to prevent coking.
Six corner coal concentration and the burner should be as uniform as possible.
7) appropriate pulverized coal fineness.
8 appropriate increase in the primary wind speed can reduce the coking near the burner.
9) the outlet temperature field of the chamber should be as even as possible.
Attending to burn different kinds of coal.
?With the wind, high load open the bottom of the wind.To strengthen the furnace blowing ash, prevent the low load of ash on the boiler combustion produced bad disturbance.
(2) chemical coke removal during combustion
According to the analysis of coking situation of boiler in different power plants at home and abroad, experts reach a consistent conclusion: no matter how your boiler is designed and how carefully adjusted it is in operation, there is no coal-fired boiler in the world that can completely block the problem of boiler coking!According to the development of science and technology, chemical coke removal in combustion should be the only way.