It explodes if it doesn't agree with each other If you know more about air compressors, you will have one more amulet

It explodes if it doesn't agree with each other If you know more about air compressors, you will have one more amulet

There have been several explosion accidents of air compressors in enterprises recently, causing great losses to enterprises. okmarts.com kindly reminds you: earnestly guarantee the safe operation of air compressors, and have a safe year.

　　 Because air compressors use compressor oil as lubricating oil, the compressor oil forms oil deposits along the entire exhaust steam channel during the compressor compression process. This deposit is called carbon deposit. It can spontaneously ignite under certain conditions, causing the air compressor device to explode. Cylinders, valve chambers, pipelines, coolers, and gas storage tanks where there are carbon deposits may explode.

　　 1. Analysis of the causes of air compressor explosion

　　 Compressor oil is subjected to high temperature and high pressure in the cylinder, and evaporates, fractionates and oxidizes to form acid pitch and other compounds. These substances form deteriorated oil mist in the cylinder, which is mixed with dust and worn-out metal particles in the air to aggravate it. After the deteriorated and aggravated compressor oil is discharged from the cylinder, deposits-carbon deposits are formed on the walls of various parts of the exhaust passage. Under normal circumstances, the generated heat is taken away by the air compressor cooling system to achieve thermal equilibrium without spontaneous combustion. When the working pressure or temperature of the air compressor increases sharply and the sediment reaches a certain thickness, the heat dissipation balance will be broken and the sediment will be automatically heated, which will ignite spontaneously in the exhaust system, leading to the explosion of the air compressor system.

　　The main factors inducing the explosion of air compressors

　　1) If the temperature of the compressed air exceeds a certain limit value, it will promote the accelerated oxidation of the deposits and automatically heat up, causing spontaneous combustion. This limit value is a variable value and is closely related to the thickness of the sediment. Therefore, the main factor that causes an air compressor to explode is the temperature of the air compressor.

　　 2) The thickness of the deposit directly affects its spontaneous combustion temperature limit. In other words, if the exhaust gas temperature does not increase and the thickness of the deposits continues to increase, the spontaneous combustion temperature limit of the deposits will be lowered and spontaneous combustion will occur. The thicker the deposit, the lower the spontaneous combustion limit temperature; the thinner the deposit, the higher the spontaneous combustion limit temperature. For example, when the thickness of the deposit is 1mm, the limit autoignition temperature is 160℃. Therefore, the thickness of the deposit is another factor that promotes the explosion of the air compressor. Several explosion accidents of pressure relief valve and aftercooler occurred in the air compressor of a mine. After analysis and calculation, the thickness of the deposit at the explosion point of the intercooler was greater than 2mm, and the limit spontaneous combustion temperature was 150℃. The thickness of the deposit at the explosion point of the rear wind envelope is greater than 3mm, and the limit spontaneous combustion temperature is 115℃.

　　3) When the flow rate of the compressed air decreases, the temperature of the compressed air will increase. This phenomenon is most likely to occur for a compressed air system composed of multiple air compressors. In addition, when the compressed air flow rate decreases, the spontaneous combustion temperature limit of the deposits will also decrease. Therefore, the section from the secondary exhaust cylinder to the gas storage tank is the most sensitive area, and the cooler and the gas storage tank are most likely to explode. If the carbon deposits in the exhaust manifold are quite thick, when the air compressor is stopped or the working conditions are adjusted, the flow rate suddenly drops or drops to zero, which is very likely to cause the danger of spontaneous combustion and explosion of the deposits. The explosion time of the air compressor is most likely to occur when the mine load is reduced. The shift time is a dangerous period of air compressor explosion.

　　4) As the temperature of the intake air increases, a large amount of superheated steam will be produced during the compression process, and the loose deposits will absorb a large amount of superheated steam and emit heat, which will increase the exhaust temperature and cause the deposits to ignite spontaneously. Rainy and foggy days are also prone to air compressor explosion.

5) At the moment when the air compressor starts to unload, the action time of the secondary suction valve is 1.5-2s later than the primary suction valve, and it is still in normal working condition, causing the secondary exhaust temperature to rise sharply; when unloading When it finally resumes normal operation, the cut-off section of air is heated by the cylinder and the piston, and the temperature rises from normal temperature to 150°C. The temperature of the secondary exhaust can reach 250°C when the high temperature is sucked in. Therefore, frequent unloading may also cause the air compressor to explode. The deposit produces a large amount of carbon monoxide after spontaneous combustion. When the compressed air contains 1.5%-7.5% carbon monoxide, it can explode.

　　 2. Measures to prevent air compressor explosion

　　 1. At the institutional level

　　1.1 Strengthen equipment maintenance and management

　　 The condition of each component of the air compressor should be verified regularly, a complete major and medium repair plan should be developed, the project should be specific, and there should be acceptance standards. Especially for regular charcoal cleaning work, a dedicated person is responsible for the acceptance. The suction port should not be located indoors, and the specified suction volume should be ensured to prevent the air filter from clogging and reducing the intake volume, causing the exhaust temperature to rise. Strengthen water cooling to ensure that the temperature difference between the inlet and outlet of the cooling tank is not higher than 10°C, and the temperature at the outlet of the cooling tank shall not exceed 50°C even in summer. Regularly remove the carbon deposits inside the compressor, generally check the cleaning exhaust valve every 600h, and replace the exhaust valve every 4000h.

　　1.2 Strengthen operation management

　　 Air compressors can be treated as dangerous sources, so operators are required to be trained and certified to work. Operators must be able to judge and deal with general air compressor failures while operating strictly in accordance with the operating procedures. Operators are required to have a clear understanding of the working principle of the air compressor, the cause of the explosion, reasonable oil injection, regular sewage discharge, and strict implementation of the startup and shutdown system.

　　1.3 Improve the monitoring capability of air compressor operating status

　　 On the basis of ensuring the basic safety facilities such as air cooling of the air compressor, temperature and pressure instrument display, safety valve, etc., an automatic temperature alarm should be installed at the connection of the outlet pipeline of the exhaust valve to strictly control the temperature not to exceed the specified 150°C.

　　2. In actual operation, the main measures to prevent air compressor explosion:

　　2.1 Measures to prevent carbon deposits

　　 Strictly control the exhaust temperature, and the double cylinder shall not exceed 160℃.

　　 Use compressor oil that has a flash point of not less than 215°C and has passed laboratory tests. Compressor oil should not be mixed with other lubricants.

　　Cylinders, suction and exhaust valves are not allowed to use ordinary mechanical oil.

　　 Clean the exhaust valve and valve chamber frequently.

　　To clean the exhaust pipe, cooler core and rear air bag regularly.

　　 Record the fuel consumption per unit operating time of each air compressor, and make statistics. If the fuel consumption increases abnormally, the compressor should be shut down to check the sealing condition of the air compressor.

　　2.2 Safe use of air filters, coolers and gas tanks

　　The function of the air filter is to remove dust and impurities in the inhaled air. When the air containing dust and impurities is sucked into the cylinder, it will not only cause the wear of the cylinder mirror and the piston rod, but also because of the high temperature in the cylinder, the impurities and oil mixture will easily adhere to the valve, cylinder wall and piston groove to form fouling , Stagnant piston ring. When the suction air temperature increases by 3℃, the efficiency of the air compressor decreases by 1%.

　　 Usually, the metal mesh filter is dipped with spindle oil. When the dirty air passes through, the dust and impurities are blocked by the mesh, and the adsorption of the oil makes it stick to the wire mesh. To clean the filter, use 1% -5% caustic soda solution to boil for cleaning. Since the exhaust temperature of the last stage of the piston air compressor reaches 140-160℃, the oil and moisture in the compressed air at this temperature are all gaseous, and the gaseous oil will be flammable when brought into the wind drum and pipeline. The water vapor is brought into the wind drum and pipeline to condense into water and cause water hammer. If the rear wind drum is closer to the air compressor, the temperature cannot be effectively reduced, which will promote the spontaneous combustion of combustibles and aggravate water shock.

　　All aftercoolers can effectively protect the wind pack. The air bag is mainly used to store a certain amount of compressed air, maintain the balance of the air supply, stabilize the pressure fluctuation, and at the same time remove the oil and water in the compressed air. Air filter, cooler and gas storage tank should be cleaned for 350-400h cumulative operation.

　　2.3 Main measures to prevent air compressor explosion

　　 The volume of the gas tank is as small as possible.

　　 The installation of the gas storage tank should avoid the resonance point.

　　 Use the aftercooler to reduce the temperature of the gas tank by 100-110℃, and the deposition can be avoided by spontaneous combustion.

　　 The pipeline between the air compressor woven air storage tank must avoid sharp expansion and protrusion.

　　 Use qualified lubricants, and the driver should control the fuel consumption.

　　 Clean the oil-water separator frequently, and drain the lubricating oil in the oil-water separator, gas storage tank, and cooler.

　　 Prevent stringing oil into the cylinder.

　　 Inhale clean cold air.

　　 The cooling water pressure is 0.1-0.15MPa, the temperature is not higher than 35℃, and the inlet and return water temperature is 6-12℃.

　　 Use softened water. When using demineralized water unconditionally, it is necessary to add as little cooling water as possible so that the cooling water does not flow out of circulation.

　　 Insist on using ultra-high temperature alarm to stop.

　　 Clean the air filter, pipeline, air bag, cooler and pipe network scale regularly. The cleaning process is to soak in 5% caustic soda for 8 hours, then rinse with clean water, and finally blow dry with high temperature and pressure.

　　 Regularly check and repair the safety protection device, and regularly remove the first-level exhaust safety valve for setting effect inspection.

　　 3. Typical case analysis

　　 1. Case: An L5.540/8 air compressor exploded in an air compressor workshop of an enterprise. According to on-site investigation and statistics, the main damage modes of the air compressor air supply system are:

　　 Air compressor workshop: The lower cylinder body and base of the second cylinder of the air compressor burst, the valve chamber burst, the aftercooler burst, and the inner core burst. The compensator between the secondary cylinder and the cooler burst, the cast iron pipe burst, and a large amount of sludge and coking materials existed in this section. Most of the partition wall at the upper part of the plant wall collapsed.

　　Pipe network: About 200m from the air compressor workshop to the user room, two-thirds of the Dg219mm pipeline had joint open welding and fell to the ground from the support. The pipe interface has no groove, the weld height is 3mm, and part of the weld meat is insufficiently fused with the pipe.

　　2, damage state analysis

　　Analyzed from the damage pattern (a), it is the explosion source in the air compressor workshop. The secondary cylinder to the aftercooler is an explosive section and a form of destruction, which causes serious damage to the equipment in this section. The shock wave of the explosion caused the weak part of the factory wall to collapse due to impact damage.

　　 The damage to the pipe network is due to the insufficient strength of the weld, and the weld is torn due to the impact of the explosive gas shock wave. In addition, the pipeline is not firmly fixed on the bracket, and the pipeline is often bent and arranged unevenly, causing the pipeline to bounce and fall after being impacted.

　　 3. Analysis of the cause of the explosion

Judging from on-site oil pollution, intercooler coking material (34mm thick), valve chamber (severe oil accumulation, local sludge thickness up to 10mm), it shows that the air compressor oiler has a large amount of oil and the timing of sewage discharge is not timely, and the maintenance and cleaning of carbon is incomplete , Resulting in a large amount of sludge, coking and coke deposits.

　　 The air inlet of the air compressor is set near the chemical iron workshop, and the amount of dust is large, which is easy to block the air filter, resulting in small air intake and high exhaust temperature. In addition, the inspection of the composition of the coking material proved that there are small particles of dust. The combination of dust and lubricating oil can easily generate sludge and coking, which is not conducive to compressed air cooling. Coking and carbon deposits will cause the exhaust valve to be loose, resulting in air leakage, causing the exhaust to heat up, so it has the conditions to generate high temperatures.

　　 The air compressor cylinder is lubricated with HS-13 compressor oil, without oil quality certificate and laboratory inspection form. After the oil product was tested, the engine impurities and ash content exceeded the standard, and the thermal oxidation stability index was restricted by the conditions. Compared with the current LDAB air compressor oil, this oil has been eliminated due to its fast generation of carbon deposits. Therefore, the use of old brand oils is one of the reasons for the increase in carbon deposits.

In summary, due to the irregular management of air compressor cylinder lubrication oil, operation, maintenance and other problems, the air compressor generates a large amount of carbon deposits, and the exhaust temperature is high, and carbon deposits and fire spots occur at the exhaust valve of the second cylinder. , The thermal oxidation and decomposition of lubricating oil is intensified at high temperature. When the light carbonized hydrogen and free carbon produced reach the explosive limit in the compressed air, an explosion occurs. Therefore, coke deposition and local overheating are the main causes of explosions, and the failure of operators to discover abnormalities in time is also one of the causes of the accident.

　　 Four. Conclusion

　　 This article analyzes the cause of the air compressor explosion, and describes the mechanism and preventive measures of combustion and explosion. These measures play a significant role in improving the operating conditions of the air compressor and preventing the combustion and explosion of the air compressor.