The three-point temperature of the low temperature of the air separation tower is: T3 temperature refers to the temperature before the high pressure air throttles; T2 temperature refers to the temperature of the air after expansion; t1 refers to the temperature after the first heat exchanger and before the expansion machine. The function of the three-point temperature is mainly to control the gas distribution between the expansion machine and the joint-1 valve during the start-up stage of the air separation tower. There is no need to control the normal and stable operation. If only one or two of the thermometer is out of order, we can speculate the working condition according to the intact temperature point. When the three-point temperature is completely out of order, it can be operated according to the temperature difference between the Heat end of the heat exchanger (namely the temperature difference between the air inlet device of processing air and the outlet temperature of oxygen, nitrogen and distillation, make the temperature difference of the hot end not greater than the normal value.
If the temperature difference of the hot end is in the normal value, try to turn on the cam mechanism as large as possible and turn off the small high pressure air throttle accordingly. When the cam mechanism has been opened to the maximum air intake position, the joint-1 valve can be used to adjust according to the need of liquid oxygen level. If the temperature difference of the hot end is greater than the normal value, open the big section-1 valve and close the small cam mechanism. In this case, the operation should be predictable, and the delayed reaction should be paid attention.
Because the change of temperature difference at the Heat end of the heat exchanger is the result of the internal temperature change of the first and second heat exchanger. When the air passing through the expansion machine is too much, the air volume passing through the joint-1 valve decreases correspondingly, and the positive flow air of the second heat exchanger decreases while the amount of oxygen and nitrogen flowing back remains unchanged, the function of the second heat exchanger is not fully played. On the contrary, the load of the first heat exchanger increases, the cold recovery of the return gas is not perfect, and the temperature difference of the Heat end is enlarged. When starting, the liquid oxygen level is not easy to rise, and when depressurizing, it cannot depressurize. When the temperature difference of the original hot end is relatively large, after adjusting the opening degree of the joint-1 valve and Cam, and the temperature difference of the hot end is close to the normal value, it should be carefully and slowly stabilized. The operation without low thermometer indication depends entirely on personal experience, and the previous operation records can be used as reference.
