The C 4204 air compressor is an important equipment for the high-pressure ethylene plant. It is a diaphragm compressor. Its function is to inject compressed air as an initiator into the secondary compressor inlet line to provide meterable air to the front end of the reactor. 5KW. The driving motor power is 5. 5KW. The inlet pressure is 0. 5Mpa, the outlet motor is 5. 1Mpa, the driving motor power is 5. 5KW. During the use of high-pressure C 4204 air compressor in the Maoming ethylene plant, the gas chamber membrane head often has abnormal phenomena, frequent maintenance, and the average interval is seven days for maintenance. The total service life of the diaphragm is 600h. At the same time, the domestic Daqing Petrochemical Complex and Yanshan are compared. The operation of the same type of compressor in the ethylene plant can achieve a service life of 2 000 h. Through the analysis of on-site maintenance statistics, the main problems affecting the operating cycle of the C 4204 air compressor are: diaphragm leakage. 1 Analysis of the cause of diaphragm leakage By comparing the inspection records with the physical analysis of the field equipment, the various aspects of the problem of low diaphragm life are analyzed to find out all the end factors that cause the diaphragm to leak. According to its working principle, the causes of diaphragm leakage are usually as follows: 1) The film head is not strong enough. After field verification, the position of the air outlet of the film head is thin, the deformation resistance is poor, the strength is insufficient, and the strength is 258Mpa after the strength calculation, so the 560Mpa strength of the design is not achieved, and the tightening force of the bolt is too large. , exceeding the required 720N m, so the film head is deformed outward after being pressed during use, causing the convex surface of the film head to protrude, and the integrity of the curved surface of the film head cannot be maintained, resulting in a change in the curvature of the curved surface of the film head; Deformation causes the diaphragm to be easily damaged during operation, and cracks cause the diaphragm to leak. Conclusion: Insufficient membrane head strength is the main cause. 2) The valve cover of the valve is not tight. After on-site verification, there are many O-ring seals that need to be replaced during the process of repairing the intake and exhaust valves. Therefore, during the process of tightening the valve cover, the compression margin is large and the force is not enough, resulting in the pressure not being tight. The valve O-ring seal is poorly sealed, causing the valve to leak; if it is too tight, the ring plug protrudes from the film head, causing the diaphragm to rupture. Conclusion: Improper tightening of the valve cover is the main cause. 3) The working oil pressure is too high. Through the on-site inspection of the system oil circuit, oil circuit blockage, oil check valve, relief valve, relief valve adjustment failure, will make the working oil pressure too high, affecting the normal operation of the diaphragm; according to the operation record of four months of use 3%。 Conclusion: The working oil pressure is not the main cause. 4) The suction and exhaust valve is damaged. The 5% of the damage caused by the damage of the suction and exhaust valve is less than 0.5%. Conclusion: Damage to the intake and exhaust valves is not the main cause. 5) The ring plug protrudes. According to the field investigation, since the annular plug protrudes from the film head, the stress concentrates on the bump of the annular plug during the working process, so the diaphragm crack is easily caused, and the crack point of the diaphragm is at the top of the annular plug. . Conclusion: The annular plug is the main cause. 6) The O-ring seal material is not suitable. After investigation and verification, the O-ring seal used in the inspection is of different material, the cross-sectional diameter is not uniform, and the size is 160 4. 2mm, and there are 159 4. 5mm. After replacing the seal, tighten the bolt. The compression amount of the O-ring seal is unstable, and the seal ring is easily deformed during the work process, resulting in poor sealing effect, oil leakage and leakage, which has a certain influence on the operation state of the air compressor, but does not cause The diaphragm is cracked. Conclusion: The inappropriate material of the O-ring is not the main cause. 7) The quality of the diaphragm is poor. 5mm. The thickness of the film is about 0. 5mm. The oil side diaphragm is in the same form as the air pressure side diaphragm, and both have a flat plane, and the intermediate side diaphragm has a leak passage for the purpose that gas or liquid can flow out and can be detected. Through investigation, the C 4204 air compressor diaphragm, although different manufacturers, the materials used are different, the diaphragm's elasticity and strength are not the same, but through the field verification, the diaphragm can be used normally. Conclusion: The poor quality of the diaphragm is not the main cause. Through the above analysis and argumentation, the main reasons for the leakage of the C 4204 air compressor diaphragm are: (1) insufficient strength of the diaphragm head; (2) improper clamping force of the valve cover; (3) the annular plug protrudes. 2 Technical modification measures for diaphragm In order to cause the leakage of air compressor diaphragm and diaphragm head, technical transformation measures were proposed. 2. 1 Redesign and processing the original film head For the deformation of the film head, the original film head of the C 4204 air compressor was measured, and the cause of the deformation was analyzed. It was found that the thickness between the top of the film head and the bottom of the inlet and outlet valve seat was too small, resulting in impact resistance and fatigue resistance. Insufficient strength, calculated by strength, and increased from the original thickness of 9. 5mm to 15.5mm under the premise of ensuring the safety factor; at the same time, due to the reduction of the valve seat depth, the size of the valve and its supporting sleeve is unchanged, the outlet flange cover bolt It needs to be relatively lengthened by about 6mm. After the membrane head was modified, its strength increased from 258Mpa to 712Mpa, exceeding the design requirement of 560Mpa, which met the requirements for use. Through the four months of use and maintenance records after the technical transformation, the damage rate of the film head is 0%, resulting in a film damage rate of 0%, and the operation of the film head is good. 2. 2 Change the preload of the valve cover When checking the valve condition, the valve gland bolt was replaced for easy inspection and spare parts processing. The original inch 7 16 was changed to the metric M12 bolt; after the valve gland bolt was replaced, the valve pressure was applied. The pre-tightening force of the cap bolt is changed under the premise of ensuring the seal. According to the nominal diameter of the bolt, the pre-tightening force is 120N. According to the use and maintenance record of the four months after the technical transformation, the preload of the valve cover of the gas valve is observed. The probability of damage to the diaphragm caused by improper force is 0%, and the effect is good. 2. 3 Adjust the size of the ring plug When replacing the diaphragm, first install the outlet valve, and tighten the gland, then observe whether the ring plug protrudes from the membrane head, and then remove the ring plug again according to the actual amount of protrusion. By implementation, the size of the annular plug is well controlled. 5%以上进行进行效果。 The use of the ring plug caused by the damage of the diaphragm is less than 0.5%, the implementation effect is good. Install the ring plug without the O-ring, assemble the ring plug and tighten it, then measure the amount of the ring plug to adjust the size of the ring plug so that it does not protrude from the film head, that is, the height of the ring plug is equivalent to the film. The thickness from the head exit hole to the bottom of the seat. According to the use and maintenance records of the four months after the technical transformation, the damage rate of the annular plug to the diaphragm after the implementation of the measure is 0%, and the implementation effect is good. After the film head is modified, the length of the annular plug is changed from the original 13.5mm by 6mm to 19.5mm. After installation, the annular plug is kept at a distance of about 2mm from the upper part of the outlet hole. After the measure is implemented, the annular plug maintains a gap of 2 mm with the bottom of the membrane head and remains in good condition. Through the four months of use and maintenance records after the technical transformation, there is no diaphragm leakage due to the problem of the ring plug. After implementing the measures to adjust the size of the ring plug, from the four months of use and maintenance records after the technical transformation, the probability of diaphragm leakage is less than 1%, and the implementation effect is good. 3 Conclusion After analyzing the cause of diaphragm leakage and technical transformation, the C 4204 air compressor was followed up for inspection in the following four months. The operating parameters were within the standard range, and the diaphragm did not leak. The service life has increased from 600h before the retrofit to 2100h after the retrofit, which greatly increases the service life of the diaphragm. By modifying the air compressor head of the air compressor, the maintenance frequency of the air compressor and the hidden troubles caused by the equipment parking are reduced, the material consumption is reduced, the environmental pollution and material waste are reduced, and significant social benefits and economy are achieved. benefit. Reeded Or Stripe Acrylic Sheet Reeded Or Stripe Acrylic Sheet,Reeded Acrylic Sheet,Reeded Acryilc Panels,Textured Acrylic Sheet Jiangmen Kunxin new Material Technology Co.,Ltd , https://www.plasticsjmkunxin.com
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