Hydrogen recovery vent gas
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Guys, I’ve run into a tricky problem recently. We’ve just replaced the hydrogen recovery membrane with one from abroad, and the manufacturer requires that the methanol content in the membrane be below 200 ppm – but our current levels don’t meet this requirement at all. I was wondering if anyone knows whether the hydrogen recovery system measures the methanol content in the off-gas after it passes through the scrubber tower What is the typical temperature control after the vent gas heater, and what is the amount of vent gas? There is also the wash water flow rate
The amount of water used for washing is determined by the volume of air. It’s generally achievable; most values are below 100. Check to see if the alcohol content in your exhaust gas is too high. The membrane temperatures should vary; generally, they are around 50±5°C. Ours has a capacity of 20,000 air volume and 3.5 cubic meters of water. Check to see if there are any issues with the internals of your washing tower
There is no water washing here; the methanol content in the atmosphere should be around 5000PPM, and the membranes remain intact. In fact, as long as the pressure is reduced and no light components condense, that’s sufficient. So we keep the temperature a bit higher. I would like to ask about the specific damage that liquid inside the membrane can cause to it.
As long as there is liquid in the gas phase, it causes fatal damage to the membrane. With a methanol content as high as 0.5%, a water scrubber must be installed to ensure the safe long-term operation of the membrane.
Reply to 4# ChuanQ: What’s the specific reason?
High levels of ammonia and methanol can damage the structure of the membrane. Generally, membranes used for hydrogen recovery have requirements regarding the levels of ammonia and methanol. 5000PPM。 . . . . I personally think this is not appropriate; it might be an error resulting from a lack of understanding of your membranes. But from what I know, for membranes and related materials, imported membranes have requirements regarding ammonia and methanol content. As long as the water does not condense into a liquid, that’s fine.
When methanol-containing off-gas enters the membrane separation process, it can damage the areas where the membranes are fixed, thereby reducing their service life! If the gas contains liquid, the impact on the membrane cannot be underestimated!
Normally, the methanol content should be kept at no more than 100 ppm. The amount of off-gas is determined by the design capacity for hydrogen recovery; generally, the inlet temperature should be maintained at least at 50 degrees, but it should not be too high, as high temperatures can easily cause leaks in the head of the hydrogen recovery membrane reactor.