1 problem
Yancheng Guotai Chemical Co., Ltd. Carbon monoxide preparation workshop The vertical labyrinth reciprocating CO compressor produced by JSW Company, which was put into operation in May 2005, has a suction capacity of 9566.2 m 3 /min, six-cylinder four-stage compression, labyrinth seal, and inter-machine tube. Road and buffer, cooling and other equipment for domestic design of domestic supporting products, motor power 2100kW, speed 370r / min. The equipment is used in the carbon monoxide gas compression section, the gas pressure is compressed from 0.03MPa to 3.8MPa.
Due to design defects and high gas impurity components, the compressor does not have enough work, the auxiliary machine and its pipelines have large vibration, large noise, and short operating cycle. The instability of its operation directly restricts the production of the downstream section. In response to the problems that arise, the technical transformation of the unit was carried out on the basis of relevant domestic and foreign related transformation technologies and combined with the practical experience of other units.
The problems with the crew are as follows:
(1) The vibration of auxiliary machinery and pipelines is large due to the original design defects.
Due to equipment failure caused by auxiliary machinery and pipeline vibration, it was forced to stop and repair for more than 30 times within half a year. The noise on the spot reached more than 95 decibels, which seriously affected the physical and mental health of the operators.
(2) Due to the sulfur, tar, moisture and some impurities in the compressed medium DDD carbon monoxide gas, the inner wall of the cylinder is corroded and fouled, especially in the case of the four-stage cylinder. When the gas is compressed, the temperature rises to produce carbon deposits, causing the cylinder to be eccentric. During the process of cleaning and cleaning the carbon deposit on the inner wall of the cylinder, the mirror seal line will be damaged to varying degrees, and the corrosion wear is uneven, resulting in an elliptical cylinder inner diameter, and the annular gap between the cylinder and the piston is increased and uneven, resulting in helium gas in the cylinder. The inlet medium temperature pressure rises, the front stage exhaust resistance is large, and the air volume does not reach the rated production capacity of the nameplate calibration.
2 technical transformation
2.1 Auxiliary machine technical transformation and solving problems
2.1.1 Add pipe support and pipe clamp on the process pipe to reduce pipe vibration
Since the reciprocating piston type CO compressor is intermittently sucking and venting, and the amount of suction and exhaust is large, the pressure and speed of the airflow are periodically changed, and the airflow is large. Large exciting forces are generated in pipe elbows, reducers, control valves, straight pipe sections, etc., causing pipe vibration.
A support plate is added to the original bracket of the secondary cooler, the tertiary outlet damper and the secondary outlet damper. Fastening pipe clamps are provided at the three-way intersection, the four-in-one pipeline elbow, and the secondary outlet cooler outlet elbow at the first, fourth, and fourth pipelines.
2.1.2 Adding a restrictor orifice plate to reduce the airflow pulse
According to the damping stability theory and the resonance theory, the pipeline stress between the CO compressors is recalculated, and the pulse vibration is eliminated to avoid the resonance gas disturbance frequency and the pipeline self-vibration frequency equal to the resonance of the pipeline.
In order to reduce the pulse generated by the airflow, it is selected to increase the orifice plate before and after the secondary outlet cooler with large original vibration and the third inlet separator.
2.1.3 Optimizing the device structure
In order to effectively eliminate the exciting force of the airflow on the separator and the cooler during the operation of the CO compressor, the structure of the separator is broken: from the original flat plate to the butterfly plate, the support of the cylinder increases the guard plate; The structure of the cooler anti-shock plate: from the original flat plate to the curved plate, the anti-shock plate is fixed on the rod to be fixed on the barrel; 3 is to reduce the vibration of the interstage cooler, and the cooler is from the vertical Change to horizontal.
2.1.4 Add buffer to eliminate standing wave vibration and reduce noise
The shell side medium of the cooler is compressed CO gas, and an acoustic standing wave is formed in a direction perpendicular to the fluid flow direction and the tube axis direction. If the frequency of the acoustic standing wave and the natural frequency of the tube bundle, the frequency of the card vortex shedding or the turbulence The flow jitter frequency is consistent, which stimulates the vibration of the acoustic standing wave. Therefore, the CO compressor generates strong noise during operation.
Take measures: between the secondary outlet to the secondary cooler, between the secondary cooler and the secondary separator, add a silencing buffer once and for all times.
2 cylinder technical transformation and treatment problems
According to the wear status of the four-stage cylinder of the compressor, the method of using the boring cylinder and the inlaid cylinder sleeve ensures that the four-stage cylinder operation of the compressor meets the design requirements. Since the four-stage cylinder and the two-stage cylinder (two) are three-cylinder integrated, therefore, The positioning and alignment requirements of the cylinder and the reloading cylinder are relatively high.
2.1 strength check
According to the strength calculation, the wall thickness of the four cylinders after the cylinder and the inlay cylinder must be greater than 30mm, otherwise the strength requirement cannot be met. The rear cylinder wall (material QT45-10) has a thickness of 20mm and a cylinder liner (material HT250-BcrCu) of 10mm. The cylinder and the cylinder sleeve adopt a small interference positioning.
It is found by calculation that the maximum stress is the equivalent stress on the outer surface of the cylinder liner, but this stress is less than the required stress of the cylinder liner, so the scheme is feasible.
2.2 The problem of strength near the screw hole on the end face of the cylinder behind the cylinder
The contact area between the cylinder and the cylinder head of the cylinder and the cylinder liner does not change. When the preload force is constant, the pressure per unit contact area does not change, and the compressive stress does not change. Therefore, the bolt holes on the original cylinder body will not be broken due to the cylinder.
2.3 é•— cylinder, inlaid cylinder liner and process
The roughing of the cylinder liner leaves the machining allowance, manually eliminates the stress of the cylinder liner, corrects and positions the cylinder installation reference, and refines the cylinder, determines the inner hole of the cylinder liner according to the actual required size, and selects the interference amount according to the actual size of the expansion cylinder. , the outer cylinder assembly cylinder sleeve of the refined car cylinder, the alignment and positioning of the cylinder installation reference, the inner hole of the cylinder liner, the remaining amount of the grinding wheel, the inner hole of the cylinder is corrected, the inner hole is honed to the design requirement, the clamp is repaired, Deburr, complete the cylinder, inlay the cylinder liner.
2.4 cylinder installation and alignment problems
Before the cylinder is disassembled, mark it. After the locating pin of the cylinder is disassembled, mark the hoisting cylinder. Adjust the installation size according to the mark, drive the locating pin according to the original orientation, and reinstall the cylinder fastening bolt, but do not tighten it. The four-stage piston (the piston rod jumps ≤0.05mm) measures the crosshead clearance of the upper and lower dead points of the piston, the guide bearing clearance, and the clearance around the piston. Based on the measured data before disassembly, the gap between the crosshead and the guide bearing is guaranteed. Adjust the cylinder block within the required range to ensure uniform annular clearance of the second and fourth stages, tighten the cylinder connecting bolts, and complete the cylinder installation.
3The operation effect of the compressor after the transformation
3.1 stable operation at full load
The advanced machine plus benchmarking technology completes the three-cylinder integrated inlay cylinder sleeve work, which not only ensures the requirements of the inner wall labyrinth seal, but also ensures that the compressor operating pressure, temperature and other parameters meet the production requirements, and the functional force meets the rated requirements.
3.2 Long-term operation, eliminating safety hazards By modifying the vibration speed and acceleration of the CO compressor auxiliary machine, the probability of failure and leakage of the auxiliary machine and pipeline caused by vibration is reduced, and the CO poisoning accident of the operator is avoided. The unit's operating stability and cycle are greatly improved. The noise of the unit has dropped below 80dB, and the physical and mental health of the on-site operators has been guaranteed.
3.3 Energy saving and economic benefits
In the past, the spare parts and pipelines caused by vibration caused the cost of spare parts to be about 200,000 yuan per year. If the overall replacement of the second and fourth-stage cylinders is about 5 million yuan.
After the technical transformation of the CO compressor, it provides a favorable guarantee for the stable and long-term operation of the system. The annual economic benefit due to the reduction of the number of stops is about 4 million yuan.
3.4 Good environmental benefits
Through the technical transformation of the CO compressor, the number of venting caused by opening and stopping is reduced, and the environmental pollution caused by the emission of CO is reduced.
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