Discussion on Improvement of New Gas Compressor and Its Auxiliary Equipment
The 7 gas pressure station established by Maanshan Iron & Steel Co., Ltd. to cooperate with the slab continuous casting project of Sangang Plant, the main equipment consists of 3 sets of 4L D9 10 gas compressors, a 1 000 mm denaphthalene tower and two sets of 8 m × 8 m Desulfurization tank composition. Since the pressure station was put into operation in the early 1990s, the coke oven gas quality has been poor due to its proximity to the coking plant. The H 2 S content is 2 500-3 500 mgm 3 and the naphthalene content is 1 800-2500 mgm 3 . With the successive commissioning of the six-machine six-flow cutting machine and the profiled continuous casting and cutting machine of the No. 3 Steel Plant, the gas consumption increased from 500 m 3 h to the current 1 200 m 3 h, and the gas purification facilities have insufficient processing capacity; This type of compressor was originally an air compressor. After changing the medium, the manufacturer has insufficient estimation of the quality of the coke oven gas in the metallurgical enterprise. The design and manufacturing aspects are not well considered. The system operation condition has been unsatisfactory and the faults are frequent. To this end, Ma Gang The pressure station system was thoroughly inspected and several modifications were taken to achieve significant results.
2 gas compressor system transformation
The 4L D9 10 gas compressor was originally an air compressor. Due to the change of the imported medium, the coke oven gas has been de-naphthalene and desulfurized, but the coke oven gas still contains a considerable amount of impurities. The compressor's automatic sewage system has not been working. Normal, often the automatic drain valve is completely blocked in two or three days, and it must be shut down for maintenance. Not only does the maintenance of the drain valve have a large amount of work, but it also causes impurities such as tar and water to be deposited in the cylinder, so that the cylinder has an abnormal sound; water collection in the cylinder is liable to cause a water hammer accident; the drain valve is malfunctioning, and the suction and exhaust valve is easily sealed. It is not good, so that the first-stage pressure is too high and the second-stage pressure is lowered; therefore, the compressor is often shut down for maintenance and cleaning after one week of operation; the sewage valve is abnormal, the corrosion of the intercooler and the aftercooler is seriously corroded, and the compressor cooling system is affected. Working life, it is necessary to repair and clean in two months. The intercooler and aftercooler will be replaced in two years, which will aggravate the maintenance task and increase the production cost, which will seriously affect the production of the three steel mills.
Due to the design of the original sewage valve system, the gas discharged from the sewage is directly discharged into the trench, so that the gas content in the trench exceeds the standard, and the CO content can reach 2×10 -3 at the highest level, which not only endangers the personal safety of the operator, but also in the trench. The corrosion of a large number of cables and instrumentation wires is also quite serious, threatening the safe operation of the equipment.
Reconstruction plan: Install a three-way valve between the primary and secondary sewage outlet pipe of the unit and the automatic sewage discharge valve, and connect the sewage outlet pipe automatic sewage discharge valve and the newly installed sewage disposal pipe respectively. A manual drain valve is installed on the installed drain pipe, and a 25 mm pipe is installed through the trench. The manual sewage and automatic sewage are directly connected to the outdoor pipe on the 25 mm pipe, and the sewage is discharged regularly. This not only does not affect the operation of the automatic drain valve, but also uses the manual drain valve for sewage discharge, reducing the operating frequency of the automatic sewage system and reducing the failure. Practice has proved that the compressor operating cycle has increased from the original seven or eight days to three months; the water cooling system has been extended from the original two or three months to more than half a year, and the corrosion of cables and other equipment has been reduced, and safety hazards have been eliminated.
Reconstruction of 3 denaphthalene tower
3. 1 transformation of the top structure
It not only affects the operation of the denaphthalene system, but also causes problems such as insufficient gas source and low pressure of the gas compressor in the next process, and cannot guarantee the normal supply of gas to the three steel slabs.
Reconstruction plan: The original tower top is a whole, and the top cannot be opened. The method of transformation is to disconnect the mist trap to the outlet pipe, and clean or replace the blocked tower top mister screen one by one, taking into account the gas equipment movement. Fire overhaul, and the difficulty of moving fire in the oil depot area, add a pair of flanges at the outlet pipe for easy maintenance and troubleshooting.
3. 2 installed sewage pipe valve at the bottom
Since the denaphthalene process requires that the Oil Pump be sprayed into the tower for 10 s -10 light diesel oil every 10 m in, the diesel fuel is sprayed several times to produce a large amount of water and dirt mixture into the packing system. Since it is intermittently sprayed, there is sufficient time for the water-oil mixture in the diesel to settle to the bottom of the oil sump, the inlet of the oil pump tube. With the increase of water-soil mixture, when the oil pump is working, the water-soil mixture is sprayed into the tower instead of pure diesel oil, which reduces the efficiency of denaphthalene removal, generally between 50% and 70%, which seriously affects the efficiency of denamination. And compressor working life. In the past, we often changed the diesel oil in the oil tank to improve the efficiency of removing naphthalene. Therefore, the consumption of diesel oil is very large, and we consume 90 tons of diesel per year.
Reconstruction plan: Install a 20 mm sewage pipe and sewage valve at the bottom of the denaphthalene tower oil tank. The oil is discharged regularly every shift, and the discharged oil enters the underground oil pool through the newly installed pipeline. After the sedimentation and separation, the diesel oil is recycled. After the transformation, the denaphthalene effect has been maintained at more than 90%, and the consumption of light diesel oil has been greatly reduced. After 3 years of practice, it is proved that only 20 tons of diesel oil is used per year, and only the diesel consumption is reduced by 70 tons, and the annual cost is 240,000 yuan. .
3. 3 denaphthalene tower inlet and outlet pipes installed with a purge tube
The diameter of the denaphthalene inlet and outlet pipeline is 300 mm, which is close to the coking plant, and the user's gas consumption has more than doubled. The design has not considered the cleaning facilities. After a period of time, the tar and naphthalene deposits in the pipeline account for half of the pipeline. Above, the gas pressure before the compressor is low, which affects the user's production.
Reconstruction plan: Install a 50 mm drain valve at the lower end of the denaphthalene tower inlet and outlet pipe, and install a 20 mm steam purge head at the upper end of the pipe. After running for a period of time, use it regularly or during the inspection of the three steel mills. Steam purging eliminates hidden dangers, improves conveying capacity, and ensures user production.
4 other renovation projects
4. After the degassing and desulfurization process of the coke oven gas of 140 m 3 low-pressure tank, the gas also contains a considerable part of impurities and water. The residence time of the gas in the low-pressure tank is short, resulting in high water content of the compressor inlet gas. To accumulate water in the cylinder of the compressor, a fine stainless steel wire mesh with a thickness of about 140 mm is installed at the outlet of the 40 m 3 low-pressure tank to further reduce the moisture and impurities in the gas, improve the gas quality before the compressor, and optimize the operation of the gas compressor. surroundings.
4. 2 Desulfurization tank inlet and outlet water seal modification Desulfurization tank inlet and outlet water seal overflow pipe is a 15 mm pipe, inserted into the bottom of the water seal from the upper part of the water seal, due to the excessive impurities and corrosion in the coke oven gas. The overflow pipe is blocked and loses its function, and the water level of the water seal cannot be judged, so that the water enters the desulfurization tank or the other side of the joint water seal, causing the gas to be cut off. To this end, a 25 mm U-shaped hose is attached to the bottom of the desulfurization water seal to abolish the original overflow pipe. A 25 mm gate valve is installed on the U-shaped pipe to facilitate cleaning and sewage discharge. At the same time, a new overflow pipe is added to the overflow pipe. The device is easy to overhaul or replace, which solves the problem of water level judgment and overflow pipe blockage of the water seal.
5 Conclusion
The transformation of the above aspects was basically completed in 1995. After four years of operation and practice, the above-mentioned transformations have obvious effects, which not only reduced operating costs, but also eliminated safety hazards and ensured the supply of high-pressure coke oven gas in Sangang Plant.
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