Air separation oxygen production area: [Weekly Topic] Week 19 of 2011——How to carry out air separation heating quickly and effectively?

I’ve never driven a vehicle before; the operating procedures provided by the company state that it involves opening all the blow-off valves and connection valves in the distillation system, and then blowing air through them intensively for 36 hours~ (I’m a beginner O(∩_∩)O~ Please don’t be too harsh in your criticism.)

When heating after parking, draining, and allowing the liquid to settle, it is required that the temperature rise at all points be even, and the rate of temperature increase should not be too high. It is mainly to prevent heat stress from damaging the equipment. When the average temperature is at a normal level, heated gas is sent to the areas where there is severe blockage during betting; to save time, those areas with severe blockages are even purged separately. However, I believe that since heating is applied, it must be done thoroughly in order to ensure that the dew points of all components remain within acceptable limits during the cooling phase for the next operating cycle.

It then moves to heat the pipes at the back, focusing on heating and purging those pipes that are difficult to heat, closely monitoring changes in temperature at various points as well as the pipes experiencing such changes. Once the required conditions are met, it quickly shifts its focus to another target, avoiding any waste of time!

Drainage can be carried out under pressure; once the liquid has been drained, the corresponding drain valve must be closed promptly, after which the normal heating process should be resumed until the required temperature is reached. Be careful not to let the temperature rise too quickly

We have also encountered such situations, especially when it is difficult to blow out the ice in the argon system or when a long time is required to do so. The measures we took were as follows: 1. After allowing the cold box to return to normal temperature, we opened all the blow-off valves surrounding the cold box, as well as the drain valves at the low-pressure end of the argon system and all the vent valves. Then we directed gas into the distillation tower, opening all the valves leading to the upper part of the tower and those related to the argon system, in order to allow as much gas as possible to flow into those areas； 2. When the temperature difference in the lower column is approximately sufficient, gradually reduce the flow rate of the blowdown valve in that column until it is fully closed. As the temperature of the pipes rises, continue to reduce the flow rate of the blowdown valve step by step. 3. While heating the main column, use the heating gas from the argon pump to warm the bottom of the crude argon column, via the inlet of the argon pump. This heating is done intermittently, with the aim of preventing water from accumulating at the bottom of the crude argon column, while also accelerating the heating of the argon system

Heating begins after the distillation tower has emptied at night; the heating process must be carried out slowly, with minimal temperature differences between different parts, in order to prevent excessive stress on the pipes and avoid damage to them. During the further heating process, the discharge blowoff valves of the upper column and the argon column should be fully open, while the opening degree of the discharge valve of the lower column should not be too large, in order to prevent pressure from the lower column from entering the upper column through the discharge pipes. Generally, heating is carried out for 48 hours; distillation columns with argon may require a longer time.

When heating, attention should also be paid to the pressure inside the tower to prevent overpressure; ensure that the exhaust pressure of the compressor does not fluctuate excessively

1. During heating and purging, it is necessary to control the amount of gas entering the tower at the beginning, in order to prevent excessive temperature differences within the distillation tower, which could cause thermal stress on the internal components of the tower and lead to equipment damage. 2. When the temperature of the gas discharged from each purge valve is above zero degrees, the heating purge can be considered complete.

It is not necessary to blow for 36 hours or 48 hours; generally, a dew point meter is used to measure the dew point of the heated gas at the outlet of the blow-off valve, and based on the typical performance of air separation units, this value should be around -65°C. . . I can’t remember the exact figure, but it seems very difficult to achieve. . . Basically, setting a target of -40 to -50°C should still be feasible; if the dew point meets the requirements, a few hours of drying should be sufficient. . .

Before heating, make sure to drain the liquid oxygen and liquid nitrogen from the heat exchanger.