Function of valve V1250 at the molecular sieve outlet
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Today I went with a colleague to work on the V1250; it was really dangerous. There was no platform at the site, so people had to climb up there, and it was difficult for two people to operate the equipment from that height. One of my colleagues jumped down from a pipe and accidentally knocked off the copper pipe that supplied gas to the instruments in V1203, causing a leak. It was a close call, but the issue was resolved quickly since the copper pipe wasn’t broken. Afterwards, the maintenance team built a temporary platform to address the problems related to operating the V1250. According to my colleague, the V1250 uses air as a source of gas for regenerating the molecular sieve. I’m not sure where this air comes from; there are many things I don’t understand as a newcomer. Please give me some advice{:1_90:}
As a supplementary note, it is equipment from Hangyang; it’s a 30,000 capacity oxygen generator using a full-low-pressure internal compression process. The new unit has just been started up and is currently under purging
This valve should be equipped with ladders and platforms in the future, otherwise it will cause unnecessary difficulties in operation. You don’t know where this gas comes from, or maybe you haven’t studied the flow diagram carefully. I suggest that you familiarize yourself well with the flow diagram. In fact, this gas is the gas produced by the molecular sieve; when there is no backflow of contaminated nitrogen gas during operation, the dried gas coming from the molecular sieve is used as a substitute for that contaminated nitrogen gas to serve as the gas source for regenerating the molecular sieve! Ours also uses Hangyang equipment, a 40,000 cubic meter air separation unit!
Thank you. I really should take a closer look at the flowcharts. I haven’t checked my own flowcharts yet; mainly because the copies of the drawings provided to us were too poor in quality, almost like pirated versions. Upon careful consideration, it’s clear that the gas used for regenerating the molecular sieve must be dry. I was confused today; since it seemed that the molecular sieves in the DCS system weren’t in use at that time, I asked that strange question: dizzy:
Are your V1250 valves manual? The ones we have here are automatic valves; they can be operated via the DCS. Although they are only used during startup, it’s still better to have an automatic system as it allows one to monitor pressure changes. However, we have been facing the issue of stuck valves here. When the temperature reached 50 degrees, neither the pressure nor the flow rate changed; at 55 degrees, the safety valve might have activated, so a new valve was installed later.
There is a pressure gauge at the outlet of this valve; when operating the valve manually, be sure to avoid exceeding the pressure limit. Also, before opening this valve, it is necessary to ensure that the nitrogen filling valve for the cryogenic tank is closed, as it is connected to the contaminated nitrogen pipeline.
After opening this valve, it must be ensured that either the valve for molecular sieve regeneration or the valve for bypassing the regeneration gas is open.
I didn’t understand what was said on the seventh floor. Why is that? .
The equipment at Hangyang Oxygen has a low level of automation; the V1250 unit is operated manually. It is indeed connected to the nitrogen pipeline, and it is used during hot startup – pressure needs to be monitored, and we do this via the DCS system. Communication with the operators on site is carried out through walkie-talkies, which is quite inconvenient. The oxygen generators generate a lot of noise on site, and it is difficult to coordinate various operations from the control room
It would be great to change this valve to an automatic one; however, it’s better to add a manual valve as well, because if this valve leaks, energy consumption will increase
Hangyang’s V1250 valves are available in both automatic and manual versions, depending mainly on the customer’s requirements. In the case of a manual valve, there is an on-site pressure gauge next to it, and the valve is opened by referring to the pressure shown on the gauge. At the same time, to prevent overpressure, the molecular sieve regeneration gas vent valve should be slightly opened.