Reconstruction of compressed air system for drill pipe inner coating production line
The drill pipe inner coating production line mainly includes key processes such as thread cleaning, hot cleaning, inner wall sanding, primer coating, and coating curing. The above processes all use compressed air as a power source. The production line is equipped with air compressor stations that provide compressed air. There are 6 air compressors in the station, each with a displacement of 30m3/min. For normal use, 4 and 2 are used. The process flow is as shown. The average gas consumption of the inner coating production line is 5800m3/h, and the maximum gas consumption is 7200m3/h. The gas consumption of the main gas equipment is shown in Table 1.
The system adopts centralized branch pipeline gas supply mode. Because the gas consumption of the equipment is not balanced, the instantaneous gas consumption is up to 75m3/h when the sand blasting equipment and the inner wall are purged, causing the working pressure of the pipe network to drop from 0.7MPa to 0.5MPa instantaneously. The pressure of the air source is required to be high and multiplied. In addition, changes in the user's production load may cause the prototype to not operate at full load, rendering the test ineffective.
(3) Testing by the inspection agency. According to the requirements of the equipment supply and marketing agreement, it must be inspected by a third party, and it is also a common mode for air compressor reliability testing. The inspection organization has excellent test conditions and professional personnel, the test results are accurate, the reliability is high, the test safety is high, the time schedule is compact, and the efficiency is high. The disadvantage is that the inspection agency generally does not carry out the production of other products, and the compressed air produced by the test cannot be utilized.
Compressed air energy recovery method Commonly used compressed air energy recycling method is to use the compressed air generated by the test directly for the original design, most of which are used as power source to drive pneumatic tools, pneumatic equipment or gas transportation. This method of recycling requires that the test and recycling time be synchronized and the load synchronized. However, the inevitable instability and continuity requirements of the test are difficult to achieve synchronization with the stable and intermittent work requirements of the equipment used, which results in low energy recovery or no recycling.
The energy stored or converted is provided in the form of energy that is generally required, so that there are many occasions for use, and energy recovery can be completed simultaneously. For the former, there is currently demand. For example, storing compressed air in a container can be used for fire rescue, blowing compressed air to toxic gases in underground or local space, protecting personnel, or starting certain specific internal combustion engines, or for some precision instruments. Cooling, etc., but the transportation cost of the pressure vessel, transportation safety, storage cost, storage security, business license and other issues need to be resolved. For the latter, the energy currently used in China is electricity, gas, fuel oil, steam, etc. Among them, the conversion of compressed air energy into electric energy is the most feasible, and there is a very serious impact on the equipment management and maintenance of 2014 Noll smooth liquid coating equipment. . In addition, the degreaser and the filter element installed at the outlet of the air compressor are aging and blockage, resulting in an increase in the exhaust resistance of the air compressor, and a “squeezing†phenomenon occurs when the exhaust gas is loaded. Since the gas generated by the air compressor cannot be smoothly discharged, the air compressor is quickly unloaded because the pressure of the exhaust port rises to the unloading pressure, and the pressure is good. With the adjustment of national policies, individuals or enterprises are allowed to access the power grid and sell them to the country. This allows the electricity produced by the compressor reliability test process to be directly utilized.
Air compressor reliability and energy saving test bench design In order to avoid repeated investment, the air compressor reliability test bench is built in a third-party inspection agency is more reasonable, the equipment utilization rate is high, and the production enterprises will submit the products to be inspected to the inspection agency for inspection, which will greatly reduce the cost. The energy recovery utilization rate has been raised to the most reasonable level. See the test equipment for air energy generation systems.
3 station test system for 3 air compressors at the same time reliability test 1 inner coating production line main gas equipment gas consumption gas equipment pressure / MPa gas volume / (m3 /!) gas equipment pressure / MPa Gas volume / (m3 /!) thread cleaning 0.5-0.660 inner wall purge 0.4-0.61500 mechanical sandblasting 3900 powder coating 0.5-0.660 manual sandblasting 0.4-0.6100 natural gas furnace door 0.7-0.810 spray motor 0.7-0.820 oil spray word 0.4 When the -0.6100 is lowered to the loading pressure, the air compressor is immediately loaded and running. The number of switchings per hour is up to 10 times, which seriously affects the service life of the air compressor main engine and each valve member. During the unloading process of the air compressor, the running current is 200A, but no compressed air is output, which increases the operating cost of the equipment.
The moisture content of compressed air is high due to the high working temperature of the equipment, and the air compressor exhaust temperature has been above 50T. In the summer high temperature season, the temperature of the compressed air discharged by the air compressor is as high as 60. The high temperature compressed air causes the adsorption type dryer to prematurely fail, and the drying capacity is reduced. After the high temperature compressed air enters the main line of the production line, as the temperature decreases, the water vapor in the compressed air condenses into liquid water, which eventually causes the compressed air provided by the compressed air system to contain a lot of water. The compressed air contains not only the operation of precision instruments and pneumatic valves such as enamel sand and enamel coating. If moisture enters the inside of the pipe with compressed air, it will seriously affect the anti-corrosion performance of the inner coating and bury hidden dangers for the inherent quality of the product.
The system uses a non-thermal regenerative adsorption dryer to dry, because the dryer needs to use compressed air to bring out the moisture adsorbed in the drier, the volume of the dryer is as high as 14m3/min. After actual measurement, open 3 air pressures. When the machine is used, the actual gas output after the filtration is only 86m3/min, and the average gas consumption of the production line is 96m3/min. Therefore, 4 air compressors must be turned on to meet the needs of the production line, resulting in the average loading rate of the air compressor. Only 60%, the system is in an inefficient operating state.
In addition, the equipment on the production line is not synchronized. When the sand and slag coating equipment is overhauled, the natural gas furnace is still running. It is necessary to open one air compressor to meet the gas demand of these equipments, resulting in a great waste of energy.
Optimize the air compressor station process route to install a gas storage tank on the pipeline between the air compressor outlet and the degreaser. As shown, the gas storage tank can buffer, stabilize and reduce system resistance. Relieve system pressure fluctuations and avoid air compressor unloading.
Optimize the dry treatment method. Install a cold thousand machine on the pipeline between the adsorption type dryer and the degreaser, and use the cold thousand machine to pre-cool the compressed air discharged from the air compressor, and finally enter the compressed air after the suction modification. System process flow chart (down to page 87 inspection, the product to be inspected can be tested in a single test, or multiple tests, the models can be the same or different, as long as the rated exhaust pressure expander intake pressure can ensure the normal operation of the entire system .
(1 The shut-off valve is closed after the equipment is stopped, and is turned on before the equipment is turned on, which functions to disconnect the local equipment without affecting the operation of other equipment; the automatic control regulating valve on the air compressor exhaust line is used to automatically control the air compressor The exhaust pressure makes the reliability test stable and effective; the pressure reducing valve is used to decompress the exhaust system when the air compressor pressure is higher than the inlet pressure of the expander, to ensure the pressure in the gas tank is stable, and the air pressure of different pressures The machine can be tested at the same time; the check valve is used to prevent the compressed air from flowing back when the test air compressor is faulty or stopped, to prevent the air compressor from reversing, and to prevent the gas tank system from losing pressure; the automatic control regulating valve in the inlet pipe of the expander It is used for automatic switching when the compressed air volume changes, switching single operation or multiple operations to maintain the higher efficiency of the expander and generator.
(2 air compressor tests are operated independently, any one can start and stop debugging at any time, replace parts, do not affect each other, as long as the air compressor that needs to be adjusted is shut down, close the shut-off valve on the exhaust pipe, then The valve is opened before the start of the machine, which does not affect the operation of the whole system. The pressure reducing valve in the exhaust line can ensure the pressure of the gas storage system downstream of the valve is stable, and meet the requirements of the inlet pressure of the expander, and the exhaust pressure is high. The air compressor needs to be connected to the pressure reducing valve. If the air compressor does not have a gas storage device and the exhaust system pressure cannot be stabilized, a gas storage valve can be connected upstream of the shutoff valve on the exhaust pipe. The tank and the automatic regulating valve can ensure the stable operation of the air compressor. In order to improve the operating efficiency of the system and reduce the loss of the compressed air energy caused by the decompression valve decompression, the selected air compressor is selected as much as possible to make the rated exhaust pressure. Close to the expander intake pressure.
(3) The combination of two expanders to drive two generators is to adapt to the fluctuation caused by the change of compressed air volume during the air compressor test due to the need of the prototype. The power of the two sets of power generation systems is large and small, when compressed When the air volume is small, the small-power power generation device operates, and when the gas volume is medium, the high-power power generation device is operated. When the gas volume is large, the two sets of devices are operated at the same time. This configuration can ensure that the power generation system always keeps running close to the rated state, which is close to the highest efficiency.
The rated exhaust pressure of the air compressor has various specifications from 0.25MPa to 45MPa. The set test device can not fully meet the test requirements of various specifications. The medium and high pressure air compressor is built with 1 set system, and the low pressure air compressor is built with 1~2 sets of system. It is a reasonable model to meet the testing needs of most manufacturers. The number of product tests for which the pressure deviates from the design requirements of the expander is controllable, and the best match is achieved in improving mechanical efficiency, reducing one-time investment and improving equipment utilization.
Energy saving assessment of test system The national air compressor production enterprises are based on 800 households, including various test purposes. According to the average, each of the five air compressors has 500h reliability test requirements per year. The average power consumption per unit is 50kW, h, per year. The test consumes at least 100 million kW, h. If all the energy-saving air compressor reliability test bench is used for testing, the electric energy is converted into compressed air energy, and then the expander drives the generator to convert the compressed air energy into electric energy. If it can reach 35%, it will save 35 million kW-h, saving energy and reducing emissions while saving a part of the test cost for enterprises with test needs.
[Editor Li Bo] Processing Center Troubleshooting Yu Xiaohao Liu Cuilun Li Xiaobin (Capital Aerospace Machinery Co., Ltd. Beijing) Industrial Center, the display suddenly black screen during Y-axis movement. Restart the machine, the machine's total power supply can not be opened and closed, and it is invalid repeatedly. Based on this, it is suspected that there is a short circuit in the circuit part of the machine, causing the machine to trip A rough inspection of the machine tool revealed that the protective metal tube of the X-axis power cord of the machine tool was torn and the internal wiring was damaged.
Cut off the torn part of the protection tube of the X-axis power line, and confirm that one of the 24V power lines of the X-axis zero return switch is broken, and two feedback lines in the X-axis motor encoder are broken. In order to ensure the stability after maintenance, the broken power cord is cut off from the breakage, reconnected inside the plug, and the protection tube is re-reinforced. After the test is completed, the power switch still cannot be closed. According to this, the problem of short-circuiting the wires in the protection tube can be eliminated.
Check the machine related circuit (figure) and find that the machine power supply is powered off and tripped (NFBSKIP is controlled by K23 and K43 relays. K23 relay is used for software control power failure in machine operation PN setting, that is, the machine automatically powers off after the M30 command is completed; K43 relay is hardware control machine power off. Two relays are measured separately, and they are normally open normally under power failure condition, which can basically eliminate software faults. K43 relay is controlled by K42 when working, K42 is associated with machine tool door switch status Check the status of the machine cabinet door key switch is normal. To determine the fault point, first remove the K42 relay, then the K42 is in the off state, the K43 relay coil has no voltage, will not pick up, the machine can be powered on normally. Use the multimeter voltage block to measure the voltage of the K42 coil input terminal (line 241) to 13.7V, and then measure the output voltage of the upper P1 part, which is also 13.7V. View the electrical drawing, and the P1 end is output from the machine tool VPA002B board. There are 3 P1 terminals, one of which is the peripheral DC24V input, the measurement is normal here, and the other two P1 are the two DCs separated by the internal circuit of the board. One port of 24V port is output to line 241). Measuring the output voltage of these two 24V ports is 13.7V, obviously this voltage does not match the inlet voltage. According to this, it is confirmed that this circuit board is faulty. The board is removed and carefully inspected. It is found that there is obvious ablation on the back of the circuit board. It is the line that is input to several branches at the P1 end. To ensure proper operation of the board, the ablation line is cut and new lines are reintroduced between several solder joints of the ablation line. After repairing the circuit board, install the K42 relay, power on the test, the machine is powered on normally, and the fault is eliminated.
Under normal circumstances, the electric cabinet door is closed before the machine is energized (the key switch KEY is closed, the K42 normally closed relay coil at the lower part of the P1 end is energized and then disconnected, the K43 coil is not energized, and the machine tool is normally powered on. Because of the protection inside the tube A short circuit occurs in the line breakage, burning the P1 terminal power supply circuit on the VPA002B circuit board, causing the output voltage of the P1 terminal to be reduced from 24V to 13.7V. The K42 normally closed relay coil voltage is only 13.7V when the machine is powered on. The normally closed contact of the relay cannot be normal. Disconnected. In the actual wiring, the P1 line before the K42 normally closed contact does not pass the VPA002B circuit board, the voltage is 24V, so that the K43 coil is energized, the normally open contact is closed, and the power supply is turned off and the power is tripped (the NFBSKIP coil is powered). The power supply is tripped open, causing the machine to fail to power on.
[Editing Ling Rui] (Continued with the temperature of the compressed air on the 81-page attached dryer to 2~5 and then using the adsorption dryer to further dry the cooled compressed air. Using a refrigerated dryer and The adsorption type drier combination method can reduce the working load of the compressed air dryer, reduce the working load of the adsorption type dryer, reduce the amount of compressed air in the regeneration section of the drying agent, realize energy saving, and ensure the compressed air quality meets the production needs.
Optimized gas supply mode The gas consumption of the smear motor and natural gas furnace door is only 0.5m3/min, but the gas pressure requirement must be >0.6MPa. The combination of one-way check valve and gas storage tank avoids compressed air. System pressure reduction affects the normal operation of the smear and natural gas furnace equipment, as shown.
According to the working condition of the equipment, a 10m3 gas storage tank is added, and the system pressure rises to 0.75MPa gap when the sand is used for loading and unloading 4 times, 5min each time. The system inflates the liquid sputum coating and the natural gas furnace gas storage tank until The gas tank and the pipe network have the same pressure. The check valve prevents leakage of compressed air from the storage tank to the main line when the pressure in the sand working system is reduced. In addition, a small air compressor with a displacement of 1 m3/min is added to the gas storage tank of the natural gas furnace. When other equipment is being repaired, a small air compressor is used to supply gas to the natural gas furnace.
Through the optimization and transformation of the compressed air system of the inner coating line of the drill pipe, the operation of the production of the hollow press was reduced from 4 to 3, the average operating pressure was reduced from 0.7MPa to 0.6MPa, and the operating current of the air compressor was from the original 480A. Reduced to 400A, the system runs more smoothly and smoothly, extending the service life of air compressor mainframe, motor and bearing. The problem of large system pressure fluctuation and high compressed water content is solved, and the overall operation quality and operation efficiency of the system are improved, and the electricity cost is saved 1.6 million yuan.
[Editor Li Bo] Equipment Management and Maintenance 2014No11
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