Due to the hard work of valve opening and closing, the valve stem is often twisted and the hand wheel is broken. Therefore, after the maintenance of the valve, the packing should be installed evenly and tightly, and the compression nut should be tightened. During the overall leakage test of air separation unit, the leakage at the valve rod packing should also be checked, and this problem should be solved before cold start-up.DEAR Liquid air separation unit.Prepare the foundation according to the manufacturer's drawings and local soil conditions. Clean the foundation hole and prepare about 10 pieces of pad iron (recommended as 100 mm × 60 mm × 15 mm, slope ratio of 1:12). Check the appearance of the wooden box, and then open the box to check the spare parts and accessories;In order to make the temperature difference at the hot end zero, it is impossible to make the heat exchanger infinite. When designing an air separation unit, the investment and operation economy of the unit are considered comprehensively, and the design is based on the selected temperature difference at the hot end. Generally, the allowable temperature difference at the hot end is 2-3 ℃ for large air separation units and 5-7 ℃ for small medium pressure air separation units.
The middle pumping volume should be small at the beginning. For the 6000m3 / h oxygen generator, 200m3 / h can be pumped first. With the continuous decrease of the temperature of the intermediate extraction, the gas extraction volume is gradually increased. Increase 500m3 / h each time, so that the temperature at the bottom of the accumulator does not rise sharply and the outlet temperature of the expander is not lower than - 180 ℃.DEAR Liquid air separation unit.Close the blow off valve, analysis valve, upper and lower valves of liquid level gauge and heating valve of lower tower system. Open the blow off valve of the upper tower, install the pressure gauge and open the valve. Slowly open the high pressure air throttle valve to make the lower tower pressure rise slowly. When the pressure rises to 0.3MPa, stop the pressure rise, and check the external connecting flange and valve for air leakage with soapy water.For the low pressure air separation unit, the air pressure is close to the lower tower pressure and can not be increased at will. The air pressure of the medium pressure air separation unit is much higher than that of the lower tower, which is expanded by throttle valve and expander respectively before entering the lower tower. Since the working pressure does not affect the distillation condition, it can be determined according to the need of cooling capacity.
Failure on the stem. The common fault is that the screw thread on the valve stem and screw sleeve is worn, which makes the valve unable to close. Generally, the screw thread of the valve stem is not easy to be worn, while the female thread on the screw sleeve (brass) is easy to be damaged. Most of the reasons are too much force when the valve is opened, or hard screw after the valve is opened or closed, so that the screw thread is damaged.DEAR Liquid air separation unit.The oxygen content in blast is increased by 1%, the pig iron production is increased by 3%, and the coal injection per ton of iron can be increased by 13 kg. At present, the oxygen content is generally 23% - 25%, and the highest is 27%. The blast volume of blast furnace is very large, and 12000m3 air is needed for each ton of iron. Although the oxygen enrichment degree is not high, the oxygen consumption is also quite large. The oxygen content is increased by 1%, and about 16-18m3 / T oxygen is needed for each ton of iron.
