The common hidden dangers of boiler workers are

Common accidents and preventive measures

First, common accidents

1. Operators are lax in labor discipline, have no rules to follow, and leave their posts without permission. Specifically, the operators do not go to work on time, or read novels, do private work, play poker, wash clothes, or even leave their posts to sleep and drink, causing serious boiler accidents.

2. The operator is not skilled, misoperation, and even do not understand the safe operation technology of the boiler.

3. The boiler structure is unreasonable, the welding quality is poor, and the safety accessories are incomplete.

4. The boiler is not treated with water supply or improperly treated with water supply.

Second, preventive measures.

First of all, the pot is short of water.

When the water level in the pot is lower than the minimum allowable water level, it is called water shortage in the pot. It is divided into mild water shortage and severe water shortage.

Slight water shortage: When the boiler water level disappears from the glass tube (plate) water level gauge, the water level can reappear by flushing the water level gauge, which is called slight water shortage.

Severe water shortage: when the water level in the pot can't appear in the glass tube (plate) water level gauge after the washing water level gauge is called water, it is called severe water shortage.

When the boiler is seriously short of water, it will cause an explosion accident of the furnace tube. When the furnace tube or drum is red-hot, if a large amount of water is supplied due to improper handling, a large amount of steam will be generated when the water touches the red-hot furnace tube or drum. Due to the sudden surge of steam pressure, it will cause boiler explosion accidents. Especially the shell boiler with high pressure and large water volume is more powerful when it explodes. Therefore, when there is serious water shortage in the pot, it is forbidden to add water to the pot, and emergency shutdown measures should be taken.

There are many reasons for the lack of water in the pot. According to the statistical data analysis of the national labor department, about 70% of them are mainly caused by lax labor discipline and misoperation of operators. For example, forgetting to supply water for a long time; Forget to close the blowdown valve or close it loosely after blowdown; The water level gauge is not flushed on time, which makes the cock of the water level gauge blocked, forming a false water level and so on. The remaining 30% is caused by equipment defects or other failures. For example, the water supply equipment suddenly breaks down, or the water supply is suddenly interrupted and the water supply is stopped. Therefore, to put an end to the boiler water shortage accident, the key is to strengthen the education of boiler operators to abide by labor discipline. As long as the operators have a high sense of responsibility and master the operation technology skillfully, even if the equipment fails, the boiler water shortage accident can be completely eliminated in time.

Second, the boiler overpressure

Boiler overpressure means that the working pressure of the boiler exceeds the maximum allowable working pressure.

Boiler overpressure and boiler explosion accidents are mostly the result of blindly increasing the working pressure of the boiler or the fireman leaving his post without authorization and leaving the boiler unattended. So we can't blindly improve the working pressure of the boiler. If you need to improve the working pressure of the boiler, you must go through strict technical appraisal by the relevant departments. In addition, from the example of boiler overpressure explosion, we can see the importance of training firefighters and strengthening post responsibility system.

Sometimes the pressure gauge and safety valve fail at the same time, which may also cause boiler overpressure.

Third, the pot is full of water.

When the pot is full of water, the water level in the pot exceeds the maximum allowable water level line, and in severe cases, the steam pipe makes a water impact sound.

The pot is full of water. Generally, the operator is negligent and the water supply is too large. When the pot is full of water, the drain valve should be opened immediately to release excess water so as to keep the water level normal and eliminate the pot from being full of water.

Four, soda * * * Teng

The characteristics of soda water * * * Teng are that the water level in the water level gauge fluctuates violently, the boiler water bubbles, and there is a lot of water in the steam, which seriously causes water impact in the pipeline.

The main reason for the boiling of soda water is the high salt content of boiler water. Therefore, the main measure to prevent soda water from rising is to control the salt content of boiler water within the critical salt content. Strengthening water supply treatment and increasing continuous sewage discharge are also effective measures to prevent soda water from rising.

Five, furnace tube blasting furnace tube blasting has a significant blasting sound, steam jet sound, then the water level drops rapidly, the steam pressure is significantly reduced, and it is generally impossible to maintain the steam pressure and water level, so it is necessary to stop the furnace urgently.

The main reason for the explosion of general industrial boilers is that the water supply treatment is not good or there is no water supply treatment at all, resulting in scaling or corrosion. Scaling in the boiler is because the hardness of feed water exceeds the specified standard for a long time, which deposits scale on the inner wall of the furnace tube and even blocks the furnace tube. Corrosion is caused by the oxygen content or acid value in the feed water exceeding the allowable regulations. According to the survey, many units do not pay attention to water supply treatment, resulting in serious accidents such as furnace tube explosion or furnace tube blockage and boiler scrapping, which is enough to take a warning. Therefore, only by strengthening the management of water treatment can we fundamentally put an end to the explosion accident of furnace tubes and save a lot of fuel, steel, manpower and financial resources.

Secondly, because the boiler is seriously short of water and the furnace tube is overheated, it will also cause an explosion accident of the furnace tube, which will soon cause water shortage. Therefore, tube explosion and water shortage often cause and effect each other. Therefore, it is very important to closely monitor the water level in boiler operation to prevent boiler water shortage and tube explosion accidents.

Six, furnace explosion

When the concentration of combustible substances mixed with air in the furnace reaches the explosion limit range, the furnace tube will explode or deflagrate when it meets an open flame. When the furnace explodes, the flame is ejected from the ignition hole and fire hole of the boiler, which is very easy to hurt people. When the furnace explodes, it will cause the furnace to collapse, damage the boiler and seriously threaten personal safety.

When all kinds of combustible substances are mixed with air, there is a certain explosion concentration limit range, and it is not easy to explode if the concentration is too low or too high. The following table lists the explosive concentration limit range of some combustible substances mixed with air at normal temperature and pressure.

For boilers burning fuel oil (heavy oil), natural gas, dry gas, coal gas and pulverized coal, it is difficult to completely avoid the explosion concentration limit range of fuel in actual operation, especially during ignition, and it is easy to cause furnace deflagration or furnace explosion accidents due to improper operation.

In order to prevent furnace explosion or deflagration, boilers burning fuel oil (heavy oil), natural gas, dry gas, gas and pulverized coal must be ventilated for more than 5 minutes before ignition. The torch should be used for ignition, not the residual heat of the furnace; During operation, the temperature of combustible materials in the furnace should not be too high, and the coordination of blast and induced air volume should be balanced.

Seven. secondary combustion

The phenomenon that combustible substances deposited at the tail of the boiler are ignited and burned again is called secondary combustion. When the secondary combustion of the boiler occurs, both the economizer and the induced draft fan will be burned out, and in severe cases, the tail of the boiler may be completely burned out.

Combustible substances deposited at the tail of boiler, such as carbon black, waste oil, pulverized coal, etc. Due to incomplete combustion, it is mainly brought into the tail of the boiler. Especially during ignition and shutdown, it is most likely to cause incomplete combustion and deposit a large amount of combustible substances at the tail of the boiler. These deposits reduce the heat transfer effect of the tail heating surface and increase the exhaust temperature. When the exhaust temperature rises to a certain value and there is enough oxygen to support combustion, secondary combustion will occur.

Some secondary combustion occurs after stopping the boiler for a few minutes or hours, which is related to the ignition point and heat dissipation conditions of combustible materials. The flow velocity of flue gas at the tail of the boiler is fast, and the heat generated by combustible substances is quickly taken away by the flue gas, which can only be oxidized slowly and cannot be ignited and burned. After the boiler is stopped, the flue gas stops flowing, so the heat generated by the oxidation of combustible materials is not easy to be lost, and the temperature will rise. If the oven door or flue damper is not closed tightly, fresh air will leak into it to help combustion, which will cause secondary combustion after stopping the furnace.

In order to prevent the secondary combustion of the boiler tail, the fundamental measure is to prevent combustible substances from depositing in the boiler tail. So if there is no fire during ignition, you must immediately stop supplying fuel (such as coal, oil, gas, etc.). ) to the furnace to prevent combustible materials from being brought into the tail of the boiler. During operation, soot blowing should be strengthened and air distribution should be appropriate, so that the combustion is complete and no black smoke is emitted. After stopping the boiler, the temperature of the economizer should be monitored. If the sudden rise of tens of degrees has caused spontaneous combustion, fire-fighting measures should be taken immediately.

In order to eliminate the secondary combustion in time, carbon dioxide fire extinguisher can be used to extinguish the fire, and steam fire extinguishing pipe can also be installed on the heating surface at the tail of the boiler. Steam fire extinguishing pipes should be evenly distributed, with small resistance to flue gas, no influence on soot blowing, tight and no leakage, and their exhaust capacity should be enough to suffocate secondary combustion.

Eight, boiler flameout

Boiler flameout is also called boiler fire extinguishing. Refers to the sudden flameout of the boiler during normal operation. Sudden flameout is a common fault in the operation of oil-fired boilers.

Nine, the furnace wall is damaged. The phenomena of furnace wall damage are: there are falling bricks in the slag remover; The temperature of furnace wall bracket, furnace shell or arch brick hoisting part suddenly rises and even burns red; A large amount of asbestos filler falls on the junction of furnace wall and the contact between furnace wall and steel frame, wall bushing and so on. , causing too much cold air to invade the furnace, reducing the furnace temperature and reducing the boiler load; The outer wall of the furnace is seriously protruding and cracked, which is in danger of collapse.

Reasons for the damage of furnace wall: in design, the structure of furnace arch and furnace wall is unreasonable, which hinders the normal expansion of boiler pressure components; Arrange fewer water wall tubes; The burner position is incorrect, resulting in excessive temperature of some furnace walls and arches. In terms of operation, the combustion flame is not properly adjusted and the flame center deviates; Long-term positive pressure combustion, high furnace temperature, low melting point of fly ash, serious coking in the furnace; Burning fire, stopping furnace and increasing or decreasing load are too urgent, which makes the furnace wall and arch suddenly cool and heat up; Touching the furnace wall when removing coke slag; Caused by explosion and the impact of combustible gas in the furnace. In terms of installation and maintenance, the brick edge is damaged and the brick joint is too large; Improper mortar ratio, poor maintenance and weak brick bonding; Not enough expansion joints are left; The oven drying time is too short, and the furnace wall is not completely dried, that is, the booster operation.

In the operation of the boiler, if cracks are found in the furnace wall, the tightness inspection should be carried out, and the load should be reduced, the induced air volume should be increased, and the negative pressure in the furnace should be maintained. When the outer wall of the furnace is slightly cracked, it can generally be filled with asbestos rope and coated with refractory cement slurry or cement lime slurry. If a small amount of refractory bricks fall off or the outer wall of the furnace protrudes slightly, the inspection should be strengthened during operation, and the operation should be temporarily maintained until the furnace is stopped. If the damaged area of the furnace wall is large, the temperature of the outer surface of the furnace wall and the furnace frame rises and there is a danger of collapse, the furnace should be stopped urgently.