Gas storage tank refers to the equipment specially used to store gas, which also plays the role of stabilizing the system pressure. It can be divided into high-pressure gas storage tank, low-pressure gas storage tank and atmospheric gas storage tank according to the different bearing pressure of the gas storage tank.It can be divided into carbon steel gas tank, low alloy steel gas tank and stainless steel gas tank according to different materials of gas tank.Gas storage tank (pressure vessel) is generally composed of cylinder, head, flange, connecting pipe, sealing element, support and other parts and components.In addition, it is also equipped with safety devices, meters and internals for different production processes.
Air compressorIt is one of the important large fixed power equipment in coal mines, and is widely used underground and on the ground, mainly for the use of air picks, air drills and rock drills at the mining face.The air storage tank is the supporting equipment of the air compressor, which is installed outdoors. The air enters the compressor and is sent to the air storage tank after being pressurized, and then is supplied to each gas consuming place by the air storage tank pipeline. The main role of the air storage tank in the air compression system is to ensure stable air supply.The compressed air accumulates water in the air storage tank to regulate the air pressure fluctuation of pneumatic equipment due to unbalanced air consumption, increase the pressure stability of the gas equipment, or store a part of compressed air, so that the user can use this part of compressed air to control the pressure of pneumatic equipment orPneumatic controlThe system is used for emergency treatment.[1]
Introduction to classification
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Gas storage tank refers to the equipment specially used to store gas.Gas tanks are often used to store and transport gas.It can be divided into ultra-high pressure gas storage tank, high-pressure gas storage tank, low-pressure gas storage tank and medium pressure gas storage tank according to different bearing pressure of gas storage tank;According to the different metal materials used in the gas storage tank, it can be divided into stainless steel gas storage tank, carbon steel stainless steel gas storage tank and alloy stainless steel gas storage tank.
Container structure used to store gas in urban gas supply engineering.The function of the container is shown in the gas tank, which is also used in petroleum, chemical and metallurgical industries.According to the gas storage pressure, it can be divided into low pressure and high pressure. The former can be divided into wet type and dry type according to the structure.
Wet gas storage tank
Vertical air storage tank
The lower part is a water tank, and the upper part is provided with several lifting sleeve shaped tower sections welded by steel plates.The tower section rises and falls with the change of gas storage.Water seals are set between tower sections to ensure connection and sealing between tower sections.There are two lifting modes of tower section: guide pillar type and spiral guide rail type.A guide pillar frame with considerable rigidity composed of guide pillars, cross web members and annular beams is arranged around the water tank of the guide pillar type air receiver.The guide wheel installed at the upper end of the tower section slides up and down along the guide post (Figure 1).A spiral guide rail with a slope angle of 45 ° is welded on the outer wall of the tower section of the spiral guide air tank. The guide wheel at the upper end of each tower section can rotate along the guide rail to rise and fall.
The sink can be made of steel plate or prefabricated or cast-in-placeprestressed concreteConstruction.Due to the heavy weight of water in the tank, when the tank is built on poor foundation, pile foundation can be used to prevent excessive tank settlement, or the tank can be designed as a ring to reduce the water volume.In addition, the water tank can also be built underground, which can reduce both the settlement and the total height of the tank.[2]
Dry gas storage tank
The tank body is a vertical cylinder welded with steel plates, with a piston inside, and gas is stored below the piston.The piston rises and falls with the amount of gas stored.A sealing mechanism is installed around the piston to prevent the escape of stored gas.Place a weight on the top surface of the piston to obtain the required gas storage pressure.The sealing methods of dry gas storage tank include oil sealing, grease sealing and flexible film sealing.
① Oil sealed gas tank。The cross section of the barrel and piston is regular polygon.The corners of the polygon are provided with I-shaped columns.The wall plate, top plate and piston bottom plate are composed of trough shaped members pressed by 5-6mm thick steel plates, which have certain bending strength and rigidity.The upper part of the piston is arranged in a radial shape, and the upper and lower ends of the truss are equipped with guide wheels.When the piston rises and falls, the guide wheel slides along the column.A circular corridor is set every 15 meters along the full height outside the tank.The sealing mechanism is the oil groove and sliding plate around the piston. The oil groove is filled with mineral oil to seal the gas under the piston.
② Grease sealed gas tank。The cross section of the cylinder is circular.I-steel columns shall be set at certain intervals outside the cylinder wall, and annular pedestrian corridors along the trunk roads shall be installed along the full height to strengthen the rigidity of thin-walled cylinders.The piston is spherical shell.The top surface of the piston is provided with a truss along the outer periphery. There is a guide wheel at the top and bottom of the truss, which slides up and down along the inner side of the cylinder wall as the piston rises and falls.The truss and guide wheel can also prevent the piston from tilting during operation.The sealing mechanism of the gas tank is composed of a sealing ring and a pressing device pressed with cotton cloth and rubber interlayer.Grease is injected between the sealing ring and the tank wall plate to enhance sealing performance and reduce friction.
③ Flexible membrane sealed air tank。The shape is cylindrical, similar to oil tank.A spherical shell piston is arranged in the tank.A sealing flexible film is installed around the piston, and the other end of the flexible film is connected with the inner side of the tank wall.In this way, a closed space is formed below the piston. When the piston rises and falls, the flexible sealing film will roll up and down accordingly.A sleeve type guardrail composed of spiral corrugated plates is installed around the top surface of the piston to prevent lateral deformation of the flexible film.The tank body is equipped with a balancing device to automatically correct the tilt of the piston.[3]
High pressure gas storage tank
High quality tankHigh strength steel plateWelded into cylindrical or spherical shape.Spherical tank has small steel consumption and uniform force.However, spherical tanks are more difficult to process, install and weld than cylindrical tanks, so they are generally only used in situations with high gas storage pressure.Both ends of the cylindrical tank are oval orHemispherical head。When an elliptical head is used, in order to make the head strength equal to the tank body, the ratio of the long axis to the short axis of the ellipse can be 2:1.[4]
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Composition of air tank
The air storage tank of the air compressor is composed of a head, a cylinder and several connecting pipes attached to the air storage tank. The head and cylinder are bent from plates, including the cylinder, which passes throughFlange connectionThe upper head and the lower head, the outer side of the upper elliptical head is respectively provided with a pressure gauge interface, an air outlet, and a safety valve interface connected with the tank, the cylinder is provided with an air storage chamber, the bottom of the lower head is provided with a drain valve, and the outer wall of the lower head is provided with a support;The air storage chamber is provided with a dehydrator, which comprises a cylindrical cylinder with a conical bottom surface, a fixed support which is fixedly connected with the cylindrical cylinder is arranged on the inner wall of the lower head, an air inlet pipe which extends into the air storage chamber and is connected to the cylindrical cylinder along the tangential direction of the cylindrical cylinder is arranged on the cylinder, the top surface of the cylindrical cylinder is provided with an air guide pipe, and the bottom of the conical bottom surface of the cylindrical cylinder is connected with an outlet pipe,The outlet pipe is connected to the drain valve.[1]
Inspection requirements for air receiver
Usually used as a simple pressure vessel,Air storage tank of air compressorIt has always been considered as a kind of relatively safe special equipment, but there are also certain dangers. If problems occur in design, manufacturing quality, installation standards, operation and management, and the requirements are not met, hidden dangers will be buried, and serious accidents may occur in use, causing casualties and equipment damage.
The air storage tank shall be reported for installation before installation. After installation, the pressure vessel use certificate shall be obtained according to the requirements of special equipment, and regular inspection shall be carried out. The air storage tank can be put into use only after passing the inspection and obtaining the inspection report.Regular inspection shall be carried out according to the pressure level and service life of the air tank. The air tank that has not passed the regular inspection shall not be used.The volume and pressure of the air storage tank shall comply with the design standards and shall not be configured randomly. One air compressor is equipped with one air storage tank.groundAir compressor stationThe air storage tank shall be protected from direct sunlight. The air storage tank must have an inspection hole, and the oil dirt in the tank shall be removed regularly.[1]
Requirements for safety accessories and protective devices of air tank
The main function of the safety valve of the air storage tank is to force the discharge when the air compressor fails to automatically relieve pressure according to the set pressure and the pressure reaches the relief pressure of the safety valve, so that the pressure of the air storage tank will not rise too high. Therefore, the safety valve should be calibrated regularly, because the air storage tank is a container for storing compressed air,When the pressure and temperature exceed the bearing capacity of the container, it will explode.The safety valve must be fixed according to the working pressure. The safety valve is sensitive and reliable, and checked regularly.The safety valve shall not be unsealed after inspection during operation, and manual and automatic startup tests of the safety valve shall be carried out regularly to check the reliability of the safety valve.The common failure of safety valve is that it does not open when reaching the opening pressure, and it automatically opens when not reaching the opening pressure.
2) Pressure gauge of air tank
The main function of the pressure gauge of the air receiver is to display the medium pressure in the tank. The pressure gauge should be calibrated once a year with an inspection certificate. If the pressure gauge is damaged during use, it should be replaced in time to ensure that the pressure gauge is accurate
2. Air tank protection device
1) The air tank must be equipped with an overtemperature protection device. During operation, the temperature in the air tank should be kept below 120 ℃. In case of overtemperature, the power supply can be cut off automatically and an alarm can be given.
2) A pressure relief valve must be installed on the outlet pipeline of the air tank, its diameter shall not be less than the diameter of the air pipe, and the relief pressure shall be 1.25~1.4 times of the maximum working pressure of the air compressor.
3) Since the compressed air has a high temperature, it will gradually cool down after passing through the air tank, and the moisture in the air will also condense. Therefore, the drain valve at the bottom of the air tank should be opened regularly to drain this moisture. Otherwise, not only the quality of compressed air will be affected, but also the air tank will be corroded. Therefore, a drainage device must be installed for the air tank.
The drainage device is equipped with manual switch and solenoid valve switch, which does not require manual timing drainage under normal conditions;If the solenoid valve fails, the manual switch can also be opened manually to drain water, so that the whole air compressor air tank has high safety, high efficiency, high reliability and long service life.[1]
Requirements for safe operation of air tank
1) Establish and improve relevantRules and regulationsIncluding operating procedures, maintenance system, operation records, patrol records, and protection test records.The operating procedures shall be strictly followed so that the working pressure of the air receiver shall not be higher than the specified pressure, and the patrol inspection shall be carried out on time, and the operation record shall be filled in in time.
2) Before operation, check whether the surface of the air receiver is damaged, whether the pipeline connection is sealed, whether the pressure gauge is normal, whether the pressure gauge is within the normal pressure range, and the exhaust valve should be opened slowly, pay attention to the water discharge in the tank, and open the inlet valve after there is no abnormality.
3) Timely check the pipeline and tank body for leakage. If any problem is found, the machine must be shut down for treatment. Operation with fault is not allowed.
4) During daily work, equipment patrol inspection shall be carried out in a timely manner to check the indicated value of the pressure gauge of the air receiver. If the working pressure is higher than the set pressure of the safety valve, the safety valve shall automatically open, otherwise, the air intake shall be stopped immediately, and the operation shall be stopped. If there is air leakage in the pipeline, it shall be repaired in a timely manner, and attention shall be paid to whether the safety valve and pressure gauge are normal.
5) When the air receiver is in use, check whether the drain valve at the bottom of the air receiver is equipped with an automatic drain valve. If it has been installed, pay attention to whether the automatic drain valve can drain normally, otherwise the moisture in the air will flow to the production line due to too much, affecting the product quality;If not, it is required to manually open the valve at least once per shift for drainage.
6) The gas storage tank is a high-pressure vessel, and no flammable and explosive gas is allowed near it. Keep the tank clean, dry and ventilated, and no sundries are allowed to pile around it.7) It is forbidden to collide and knock the tank body with metal tools during operation.The air tank is free of serious corrosion, the support is flat and stable, the welding point is free of cracks, and there is no severe shaking during operation.[1]
Cause Analysis and Maintenance of Gas Tank Explosion
1. Causes of explosion of gas tank
The gas pressure in the gas tank rises sharply. If it exceeds the strength limit of the tank wall thickness, the failure of the safety valve will lead to overpressure operation of the gas tank.Due to carbon deposition in the gas tank, mechanical impact of hard particles during movement and spark generated by electrostatic discharge, due to poor cooling, the gas tank accumulates a large amount of oil and carbide, and is not cleaned in time, resulting in carbon combustion in the tank, which is prone to combustion and explosion of the gas tank.
2. Maintenance of air tank
1) The maintenance of the gas tank is very important. Check whether the connecting screws of the pipeline are loose and invalid every day. Apply grease to the screws to prevent the screws from rusting, inconvenient disassembly and inspection, damage to the tank body. Keep the tank body clean and free of rust. Rust proof treatment shall be carried out for the tank body paint every year. When checking and repairing, pay attention to prevent wood chips, iron chips, wipers, etc. from falling into the gas tank and the pipe.If the air tank is not used for a long time, the water in the tank shall be drained and the tank shall be kept dry.
2) The appearance of the gas storage tank shall be bright, the surface treatment shall be uniform, the welds shall be flat, the lines shall be clear, and there must be an equipment nameplate, on which there must be the working pressure of the gas storage tank, manufacturing date, volume size, factory number, weight, volume, medium, supervision unit, manufacturer, and steel seal number of the product directly below the nameplate, according to relevant national regulations,Each air receiver must be provided with a quality guarantee certificate when leaving the factory.Establish one machine and one file for the air tank equipment, including the air tank inspection report, use certificate, relevant technical data, rules and regulations, drawings, etc.Operators must work with certificates to realize remote monitoring and unattended operation. Special personnel shall be assigned to patrol regularly and deal with problems found in a timely manner.[1]
