How to prevent boiler accidents

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How to prevent boiler accidents

① boiler explosion accident

(a) overpressure explosion: the pressure rises due to the failure of the pressure gauge or the operator's lax pressure monitoring. At this time, the safety valve fails, causing the pressure in the boiler barrel to exceed its bearing capacity and rupture and explosion

(b) explosion caused by defects: the pressure borne by the boiler does not exceed the rated pressure, but the pressure bearing parts lose their bearing capacity and suddenly rupture and explode due to cracks, serious deformation, corrosion and other conditions of the main pressure bearing parts. The prevention of this kind of explosion is mainly to strengthen the inspection, find and deal with the existing defects in time, and avoid the defective operation of the boiler

(c) serious water shortage leads to explosion. Once the boiler is short of water, the main pressure parts will not be cooled normally, and even burn red. At this time, if the boiler is filled with water, it will lead to an explosion accident

② major boiler accident

(a) water shortage accident:

due to operators' lax monitoring of water level, or water supply system failure, boiler pipe explosion and water leakage, the boiler water level is lower than the minimum safe water level mark of the water level gauge, forming a water shortage accident. Serious water shortage will overheat, deform and even explode the tubes on the evaporation heating surface of the boiler, and improper treatment will also lead to boiler explosion accidents. When it is found that the boiler is short of water, first use the method of calling water to judge the degree of water shortage, and then give different treatment to Jinan testing machine factory for its leading sales in 2016. For slight water shortage, water can be supplied to the boiler immediately, but in the face of difficulties; In case of serious water shortage, the boiler must be shut down for inspection in an emergency, and the boiler shall not be filled with water

(b) full water accident:

due to the operator's lax monitoring of the water level, or the false water level of the water level gauge failure and the operator's failure to find it in time, the boiler water level is higher than the maximum safe water level mark of the water level gauge, forming a full water accident. After serious completion, it will meet the requirements of the rapid growth of the company and the industry. When full of water, the boiler water can enter the steam pipeline and Superheater, causing water hammer and Superheater scaling, and reducing the quality of steam. After finding that the water is full, first flush the water level gauge. Once it is confirmed that the water is full, immediately close the feed valve, stop feeding water to the boiler, and open the blowdown valve and drain valve to strengthen water drainage

(c) Co transpiration of steam and water:

due to the poor quality of boiler water or the rapid change of load, the steam and water on the evaporation surface of the boiler rise together, producing a large amount of foam and fluctuate up and down, forming the phenomenon of CO transpiration of steam and water. Serious steam water co transpiration will bring water to the steam, causing water hammer in the steam pipeline and reducing the steam quality. When steam and water are found to be bubbling together, reduce the combustion, turn down the main steam valve, open the blowdown valve, and fill water at the same time to improve the quality of boiler water

(d) boiler tube burst:

due to tube scaling, serious water shortage, flue gas wear, corrosion and other reasons, the boiler evaporation heating surface tubes (including water wall tubes, convection tube bundle tubes) burst during operation. Tube explosion will cause boiler water level to drop, steam pressure to drop, combustion instability, etc. In case of pipe explosion, the boiler must be shut down for repair

(E) economizer damage:

the economizer pipe is broken or other parts of the economizer are damaged due to serious wear of fly ash, or the feedwater is not deaerated, pipeline water hammer and other reasons. When the economizer is seriously damaged, the boiler water level drops, and the flue is wet or leaking, causing the boiler to be forced to shut down due to water shortage. If the economizer is found to be damaged, if the boiler can be fed with water through the direct water supply pipe, the economizer can be repaired without stopping the boiler, otherwise the boiler must be stopped for repair

(f) superheater damage:

due to scaling in the superheater, overheating of the superheater tube, serious wear of fly ash and other reasons, the economizer tube is broken, causing the superheater damage accident. When the superheater is seriously damaged, the superheated steam temperature rises and the pressure drops, and the furnace negative pressure decreases. At this time, the boiler needs to be shut down to repair the superheater

(g) water hammer accident

boiler feed pipe or economizer pipe, due to the valve opening and closing speed is too fast, the high-speed flow of water is suddenly blocked, causing water hammer; The water hammer of superheater pipeline often occurs in the accident of full water or steam water co transpiration. When water hammer occurs, the pressure on the pipeline rises suddenly, often causing damage to pipelines, valves, etc. Therefore, after water hammer, pipes, valves, flanges, etc. should be carefully checked for abnormalities. In order to prevent water hammer accidents, the valves of water supply pipelines and economizer pipelines should be opened and closed slowly to avoid full water and steam water co transpiration accidents

(H) furnace explosion

furnace explosion often occurs in oil, gas and pulverized coal fired boilers. When the concentration of combustible mixture accumulated in the furnace reaches the explosion limit, deflagration will occur in case of open fire. Furnace explosion can cause damage to water-cooled walls, rigid beams, furnace tops and walls, and cause casualties in serious cases. In order to prevent the occurrence of furnace explosion accidents, reliable furnace safety protection devices should be installed, such as explosion-proof doors, interlocking, alarm, tripping systems and ignition procedures. When starting the boiler for ignition, strictly follow the operating procedures, and it is strictly forbidden to use deflagration method for ignition. After ignition failure, ventilation and purging shall be conducted for 5 ~ 10min before re ignition

(I) secondary combustion of tail flue:

often occurs on oil fired boilers, which is easy to occur soon after boiler shutdown. When the boiler is shut down, the long profile with incorrect combustion shall be sampled at both ends separately for stability. The combustibles enter with the flue gas and accumulate on the heating surface of the tail flue (air preheater, economizer). Under certain conditions, these combustibles will ignite and burn by themselves. The secondary combustion of the tail flue often damages the air preheater and economizer. To prevent the secondary combustion of the tail flue, it is necessary to organize the combustion, reduce the incomplete combustion loss as far as possible, and install fire extinguishing devices on the tail flue of the oil fired boiler

(J) boiler slagging:

often occurs on coal-fired boilers. Ash and slag are bonded to the heating surface, furnace wall and grate at high temperature and accumulate more and more. Slagging will reduce the heat absorption capacity of the heating surface and affect and destroy the water circulation; Serious slagging will hinder the normal operation of the combustion equipment, and even forced to shut down the boiler. The main measures to prevent slagging are: control the combustion heat load of the furnace so that the furnace outlet temperature does not exceed the ash deformation temperature; Reasonably control the excess air coefficient and reduce air leakage; The slagging of boiler shall be removed in time

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