Hydrogenation unit: The pressure of the fresh hydrogen feed has decreased – how to adjust it?
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The hydrogenation unit uses cold fractionation, without thermal fractionation; the hydrogen used is purchased from outside. The new hydrogen, after being pressurized by a new hydrogen compressor, is supplied to the circulating hydrogen buffer tank. Current problem: When the pressure of the incoming fresh hydrogen decreases, it causes the pressure in the recycled hydrogen system to drop as well. The self-circulation control valve of the new hydrogen compressor is operated manually, with little adjustment made; the solution taken is to manually open the manual valve on the hydrogen inlet pipeline. Then I call the hydrogen production plant, and it takes over an hour each time to get the pressure adjusted to normal. In such a situation, can it be controlled by adjusting the self-circulation control valve of the new hydrogen compressor, or are there other methods for making adjustments?
In such situations, the following measures are generally taken: 1. Switch to automatic control. It is recommended to change the self-circulation control valve of the new hydrogen compressor from manual control to automatic mode. If the self-circulating valve already has an automatic adjustment function, switching to automatic mode allows it to adjust its opening degree based on system pressure, thereby responding more promptly to changes in the pressure at the fresh hydrogen inlet. 2. Temporarily reducing the self-circulation volume manually: When automation is not feasible under the current conditions, it is possible to manually reduce the self-circulation volume temporarily (by closing the self-circulation control valve) in order to increase the amount of fresh hydrogen that enters the system, thereby rapidly raising the pressure in the recycle hydrogen buffer tank and alleviating temporary low-pressure issues. However, attention must be paid to the minimum flow requirement of the compressor to ensure the safe operation of the equipment. 3. Optimize the coordination mechanisms between upstream and downstream parties. Establish a more efficient communication system with hydrogen production plants, and agree in advance on rapid response procedures in case of fluctuations in hydrogen pressure, thereby reducing the time required for adjustments. Recommended solution: From the perspective of long-term stable operation, it is recommended to carry out automated control upgrades for the compressor’s self-circulation control valves, while also optimizing the communication and coordination mechanisms with hydrogen supply providers. .
If the amount of hydrogen supplied from upstream decreases and cannot be restored in the short term, the most effective measure is to reduce the system’s operation level appropriately to lower hydrogen consumption. Although reducing the return line of the new hydrogen machine will increase the amount of new hydrogen entering the system for a short period, it will also lead to a further drop in the pressure of the new hydrogen; this affects the operation of the new hydrogen machine and causes continued fluctuations in the system.