1. The air valve leaks and the piston ring is badly worn. If the valve plate of the air valve breaks, the valve spring will fail and the seal will not be tight. In addition, when the air valve is not installed properly, the air valve tilts, and the ejector pin on the valve cover pushes the air valve tightly, which also causes air leakage of the air valve, and compressed air directly enters and exits from the sealing position of the air valve seat. Air leakage will reduce the intake air volume and increase the in-cylinder temperature and exhaust temperature; The leakage of exhaust valve will reduce the exhaust volume and intake volume, and make the compressed gas flow backwards, thus increasing the temperature in the cylinder and the exhaust temperature. Wear or fracture of piston ring makes the sealing effect of air compressor worse. The gas on the compression side will leak to the suction side through the piston ring, which will lead to gas channeling in the cylinder block, raise the temperature of the cylinder block and increase the exhaust temperature.
2. The equipment is rusted. When overhauling the air compressor, it was found that there was a thick layer of rust and a lot of rust in the corner of the cooling partition in the middle of the air compressor, and the partition was broken. When the air compressor leaves the factory, these rusts easily enter the air valve, causing the valve plate to tilt, the spring to be damaged, the seal to be loose, and air leakage, which will inevitably lead to an increase in exhaust temperature. Because the compressed medium air is impure gas containing oil and water, the cylinder is cast iron, and the intercooler is ordinary steel plate, which is easy to rust under the corrosion of water vapor. After the air compressor is stopped, the temperature difference between cooling water and cylinder is large, which is easy to condense. If the condensed water can't evaporate in time, it will corrode the inner wall of the cylinder. In addition, the cylinder gasket is not tight, and the cooling water system is not tight, which leads to water entering the freestyle body and rusting the cylinder body. 3. The equipment is polluted and accumulated water. When the equipment is overhauled, it is found that there is scale and sludge in the water jacket of the intermediate cylinder of the secondary cylinder through the disintegration of the air compressor, which reduces the heat exchange effect. Moreover, due to the blockage of the intercooler tube bundle, the cooling water flow decreases, which reduces the effective cooling area and cooling effect. The cooling water of aftercooler is not discharged in time, and there is too much accumulated water, which causes the secondary exhaust of air compressor to be cloudy, and the heat exchange effect of cooling core fins decreases after hot air enters, which leads to the increase of secondary exhaust temperature.
4. Hot air of intercooler is short-circuited.
Due to the crack of the welding seam of the intermediate cooling baffle, air short-circuited into the secondary cylinder, and the cooling was insufficient. The secondary air inlet temperature is too high and the secondary temperature rise is too fast. Third, improvement measures.
1. Take advantage of the parking opportunity to thoroughly clean the scale, silt and rust at the bottom of the water jacket of the intermediate cylinder and the valve cavity of the air chamber, check whether the sealing and flexibility of the air valve are in good condition and whether the piston ring is worn, and decide to replace the spare intercooler and aftercooler cores according to the external temperature and the cooler's good condition.
2. Replace the cooling partition plates in 2# and 3# air compressors with stainless steel plates, and there is no abnormality.
3. Replace all the carbon steel annular valve safety filters originally used by the air compressor with stainless steel. Stainless steel filter has good overall performance, strong impact resistance, no rust and long service life. From the use effect, there is no abnormality or damage.
4. There is scale and sludge in the water jacket of the intermediate cylinder of the secondary cylinder of the air compressor, indicating that there is a dead angle in the water jacket of the intermediate cylinder and the cooling water does not flow. According to the structure of the air compressor, an inlet and an outlet cooling water pipe are added to the cylinder head (where dirt and mud are accumulated), and the original design water pipe is cancelled. Judging from the operation of the air compressor, the effect is better than before. After disassembling the cylinder head, no scale and sludge were found.
5. Shorten the drainage time of intercooler, and switch standby machines regularly to prevent condensed water from corroding cylinder block.
6. Necessary tools for diligent inspection, maintenance and configuration can be used to often auscultate the air valve of the equipment with a listening stick. The sound of the air valve running is crisp, indicating that the air valve parts are normal. If you hear a "hissing" scream, it may be that the valve plate is damaged or the air valve is leaking. Regularly open the drain valves on the intercooler and aftercooler to discharge the accumulated water and some small particle impurities in the cooler in time. If the hand touches the suction valve cover, if the valve cover temperature is high, it can be judged that the suction valve is leaking or damaged. Using advanced infrared thermometer to compare the working temperature of each suction valve can find the faulty valve as soon as possible and save maintenance time. Fourth, improve performance.
By strengthening equipment management and transformation, improving maintenance quality and carrying out equipment transformation, after careful maintenance at ordinary times, the equipment runs stably and normally for a long time, providing sufficient qualified instruments and industrial compressed air for each branch. Solve the problem that it can't run stably and normally due to high temperature, and it will jump at any time.