Problems with high-pressure air throttle valves
Thread Content
How to put into use the high-pressure air throttle valve at 7.2 Mpa during the commissioning of an air separation unit? What should be noted during the commissioning process?
Considering it was put into use at that stage, purging? Cooling? Normal?
If the purging is complete and it’s time to start the expander, how should this high-pressure throttle valve be operated? Thank you
Open it to a small degree, within 10 degrees; you can figure this out by trial and error. The high-pressure throttle valve should be gradually opened as the oxygen pump starts operating and under load, which will also increase the pressure of the booster. Are you referring to an internal compression process or a liquid flow process?
Internal compression process, during the startup phase of venting gas into the lower tower
Just set the backflow valve to a low setting – backflow mainly occurs through the low-pressure plate valve, while the high-pressure throttle valve remains unchanged
Then what does high-plate cooling rely on? What I mean is that all gas conduction relies on the lower plates; so once cooling of those lower plates is complete, can the temperature of the upper plates drop as well? Thank you
What is your high-plate process like? Could you give a general description? Is it a low-pressure plate process?
1. After the purging is complete, this valve should be slightly open, but not too much； 2. After starting the expander, in my opinion, adjustments should be made based on the temperature drop within the main tower; it is best to refer to the temperature before the throttle valve and make adjustments by comparing it with other temperatures inside the tower, in order to prevent too rapid or too slow a temperature drop ； 3. Once liquid appears inside the tower, it is necessary to make adjustments based on the inlet temperature of the expander and the load on the unit; generally, it is best for the temperature before the throttle valve to be close to the specified value.
In any case, the opening speed of this valve must be slow
For units equipped with high and low pressure heat exchangers, the high-pressure air throttle valve should be slightly opened when guiding air, usually by 3 to 5 degrees (as per our standards!). During purging, since the volume of gas flow is relatively small, the outlet valve of the booster pump can be closed and then the throttle valve can be opened a bit more to allow air to flow back inside the tower for purging After the expander is started, it can be adjusted based on the temperature difference at the high-heat-exchange end; when the temperature of the cold material exiting this end is significantly lower than that of the hot material, the high-pressure air valve can be opened slightly more to recover the cold energy (This is how it is on our end)