Sometimes the thread is completely "biting", the valve can only be opened, but not closed. To close the valve, the valve stem can only be pushed inward with temporary additional bolts, and then it can be repaired when it is overhauled. To prevent this kind of failure, the most important thing is not to use too much force when opening and closing the valve, and do not open or close the valve hard when it cannot be opened or closed.DEAR Air separation equipment.The removal amount of waste nitrogen (or distillate) is too large, the opening of liquid air and liquid nitrogen control valves is improper, and the working condition of lower tower is not adjusted properly. Poor heat exchange of main cooling system. Insufficient heat exchange surface of the main cooler or more non condensable gas on the nitrogen side affect the heat transfer of the main cooler and reduce the evaporation of liquid oxygen.DEAR Air separation equipment.The purpose of temperature condition adjustment is to keep the temperature difference between cold end and hot end within the specified range. Then, why should the middle temperature be taken as the criterion? It depends on the relationship between the middle temperature and the temperature difference between the cold end and the hot end, as well as the law of temperature change along the height direction of the accumulator (or switched heat exchanger).
The common fault of the automatic valve is that it is not closed tightly, resulting in gas channeling at the middle and low pressure cold end. This is reflected by the increase of air flow and the decrease of pressure. At the same time, the pressure of the low pressure system increases. The failure of automatic valve is also a great threat to the normal production of oxygen generator.When liquid began to accumulate in the main cooling system, the temperature in the nitrogen channel of the main cooling system at the top of the lower tower was higher than that of the liquid oxygen. If the temperature difference is too large and the liquid evaporates too fast, the rise of liquid oxygen level will be slow or even not. At this time, turn down the regulating valve-1 and slightly open the liquid nitrogen reflux valve, so that the distillation condition of the lower tower can be established as soon as possible.In normal operation, the main operation of the condensing evaporator is to keep the oxygen level at the specified height. There are many reasons for the fluctuation of the main cooling liquid level, but in a word, it is caused by unbalanced cooling capacity or improper liquid distribution.
The activation temperature should be higher than 200 ℃ and lower than 250 ℃. When the outlet temperature reaches 80 ℃, it can be cold blown. The activation time shall not be less than two switching cycles; when the molecular sieve adsorber is started, the process of gas supply and pressure rise shall be slow, and when the vent valve is closed, care shall be taken to prevent the molecular sieve in the bed from being damaged due to pressure fluctuation; when the two expanders need to be started, the outlet return valve of the booster shall be fully opened to reduce the pressure of the first operating expander, and then the two expanders shall be loaded at the same time to prevent the latter The start-up supercharger has a surge;DEAR Air separation equipment.When its thickness increases, the evaporation efficiency decreases, and the evaporation decreases sharply with time. Generally, defrosting methods are needed, such as blowing the frost with steam or sweeping the frost with a broom to restore the evaporation. The steam water bath evaporator uses hot water to heat the low-temperature liquid in the evaporation tube to make it evaporate.
DEAR Air separation equipment.In some processes, the crude neon and helium must go through two steps of hydrogen and nitrogen removal. Hydrogen is removed by catalytic oxidation to generate water, which is then removed by desiccator. The remaining nitrogen is removed by condensation or low temperature adsorption with activated carbon. Because the difference of boiling point between neon and helium is about 23K, condensation method can be used to separate pure neon and helium mixture. Because the freezing temperature of neon is - 248.7 ℃, the gas helium and solid neon can be separated by freezing method.Compared with gas leakage, liquid leakage is more harmful, because its unit cooling capacity is twice as large as that of gas at the same temperature, and the density of liquid is hundreds of times of that of gas. Taking liquid oxygen as an example, if the leakage occurs at the speed of 1l / min, the increased cooling loss is 27200kj / h = 7.6kw, and the expansion of 600m3 / h is needed to make up for it. In fact, the equipment can not work normally. Therefore, the leakage of liquid pipeline is absolutely not allowed.
