Questions regarding the operation of the PSA final lift control valve
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These days I have been learning *PSA, and I have a small question regarding the final pressure increase of the product gas during the operation process. I would appreciate it if the teachers could provide an answer. Our PSA is Huaxi, with a 10-2-4 operation mode. Regarding the operating steps, does the product final lift control valve open only during the final lift phase, or does it open both during the final lift and the initial lift phases? My personal understanding is that during the final pressure increase, the valve opens to the extent specified by the set upper and lower limits, thereby completing the final pressure rise in the adsorption tower. The documentation states that during this initial pressure increase in the adsorption tower as well, the valve opens to the extent defined by those upper and lower limits; I’m not quite sure about this. Please, teachers, provide an explanation. {:1_90:} The documentation states that the circuit control for this product gas final rise valve operates in two stages: in the first stage, it operates within the 0-10% range; in the second stage, it operates within the 15-25% range once the final rise is achieved. The overall adsorption and regeneration process is as follows: adsorption, adsorption, adsorption, adsorption, first level of pressure reduction, second level of pressure reduction, third level of pressure reduction, fourth level of pressure reduction, release in the forward direction, release in the reverse direction, release in the reverse direction, flushing, flushing, flushing, flushing, fourth level of pressure increase, third level of pressure increase, second level of pressure increase, first level of pressure increase, and finally, the product gas reaches its final rise level.
There is an opening value both for lifetime and average values; which refinery are you from?
The final rise valve is opened to its lower limit; as the pressure rises, the valve gradually opens further until the final rise pressure is reached, provided that the valve is in automatic mode. In the event of a fault and manual operation is required, the same lower limit applies, and the valve is gradually opened further according to the set upper and lower limits as well as the PID control, until it reaches its maximum limit and the final rise pressure is attained! When the final adsorption time is reached, it shuts down even if the upper limit has not been attained; a longer final adsorption time allows the upper limit to be reached. This is adjusted based on the quality of the hydrogen produced, by either modifying the upper and lower limits or the PID parameters!
This post was last edited by dpclove21 on 2016-9-8 at 17:25. In fact, valve number 9 of Zhongsheng is always open, while valve number 3 is only open during the Yijun and Zhongsheng phases. The final rise control valve operates at the set lower limit, while during final rise it operates at the set upper limit.
Adjusting the upper and lower limits seems to have little impact on product quality; the main goal is to control the rate of rise and avoid fluctuations in air flow. I would like to ask how to manually control the end-rise valve?
Isn’t it written above? Can’t you read it? When switching to manual operation due to a fault, the set value is also the lower limit; during the final rise, the valve is gradually opened up to the upper limit based on the set upper and lower limits and the PID control, until the final rising pressure is reached! When the final adsorption time is reached, it shuts down even if the upper limit has not been attained; a longer final adsorption time will allow the upper limit to be reached! He is responsible for ensuring the final rising pressure as well as the uniform pressure. If the upper and lower limits are not adjusted properly, it will be impossible to achieve the desired final rising pressure and uniform pressure – wouldn’t that affect product quality? Go and look up some information to learn it by yourself!
The final rising speed in automatic mode is automatically calculated based on the system pressure program to achieve the final rise, while in manual mode it is determined by the upper and lower limits as well as the PID control valve – it’s quite clear already
Unreasonable adjustments to the upper and lower limits have a greater impact on pressure fluctuations, and do not affect purity in the short term
Then, since pressure fluctuations don’t have an impact, just call it a fluctuation!
I would like to ask: is the purpose of activating the lower-limit opening control valve during equalization to ensure that the adsorption tower reaches the set pressure? Can an adsorption tower with a constant descent pressure not be brought to the set pressure together with an adsorption tower with a constant ascent pressure?
Yes, it’s to ensure that the voltage is the same throughout; there are upper and lower limits for this value, as well as upper and lower limits for the final rise