The throttling expansion process of the throttle valve and the expansion process of the expander often encountered in the oxygen generator can be regarded as an adiabatic process. After expansion, the pressure decreases. However, the former is irreversible adiabatic expansion, and the entropy value increases before and after expansion.DEAR Liquid air separation unit.If there is thick dirt on the wall, its thermal conductivity is much smaller than that of metal, which will weaken the heat transfer and reduce the heat transfer coefficient K. attention should be paid to keep the heat transfer wall clean in the production process. It can be seen that under different conditions, the heat transfer coefficient has different values, which can be determined by theoretical calculation or referring to the measured results of similar equipment.DEAR Liquid air separation unit.The control of non switching plate fin heat exchanger in molecular sieve purification pressurization process is not as strict as the temperature difference control of switching heat exchanger in self cleaning process under stable conditions. Since there is no self cleaning problem, the heat exchanger only needs to control the temperature difference at the hot end and the air extraction temperature in the middle.
DEAR Liquid air separation unit.After all valves are in place, they shall be opened and closed again, and it is qualified if they are flexible and free from jamming; after large air separation tower is exposed to cold, the flange of connecting valve shall be pre tightened once in cold state to prevent leakage at room temperature but at low temperature; it is strictly forbidden to climb the valve stem as scaffold during installation.The temperature of expander can also be regulated by bypass air (low temperature air at the outlet of heat exchanger). In a word, as long as the temperature difference at the hot end is controlled and the intermediate extraction temperature is within a certain range, the working condition of the non switching plate fin heat exchanger is basically stable. Even if there are some changes, as long as the cooling capacity can be balanced, there is no need to make more adjustments.Since nitrogen still accounts for about 60% in the liquid air, most of argon condenses in the liquid air. Generally speaking, the argon content in the liquid air of the lower tower ranges from 1.3% to 1.6%, and the argon content in the liquid nitrogen is only 0.0%. There are two argon rich zones above and below the liquid air inlet.
DEAR Liquid air separation unit.There is a certain relationship between the thermodynamic state parameters, for different substances, their relationship is different. This relationship reflects its thermodynamic properties. Usually, if any two independent state parameters are known, the values of other parameters can be determined. For example, the enthalpy h and entropy 5 can be determined according to the temperature and pressure P.In order to reduce the moisture brought into the purifier (or dryer) by the heating gas and ensure the service life of the purifier (or dryer), the heating pressure of the purifier should be controlled to the normal working pressure (2MPa). In addition, the gas flow velocity in the purifier is inversely proportional to the pressure.The so-called saturated liquid refers to the liquid whose temperature has reached the gasification temperature under the pressure at that time but has not yet been gasified. If the saturated liquid continues to be heated, saturated vapor will be generated and the temperature will remain unchanged.
