Reasons for the high hydrogen content in the PSA desorbed gas
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Our hydrogen production unit has just been started; the analysis of the hydrogen content in the off-gas shows a level of 40%–50%, and the color of the burner in the conversion furnace is blue. Is this level normal? What causes the pressure to be too high after all four values have decreased? Is the adsorption time still too short? Dear experts, please share your thoughts more
Please consider and investigate the following points: 1. The adsorption time is too short; 2. The exhaust gas pressure is too high, resulting in poor desorption efficiency; 3. The adsorbent has lost its effectiveness; 4. There is internal leakage in the programmable valve. Generally, in hydrogen production units, the hydrogen content in the reacted gas is around 74%, while the hydrogen content in the exhaust gas is about 20%. Since the current hydrogen content is 40–50%, the hydrogen recovery rate must be very low. The hydrogen content in the exhaust gas from domestic reforming units using PSA is relatively high; the hydrogen content in PSA output is over 50%
There are only ten towers, with a maximum of four equalization operations. Now remove one tower, and it becomes three equal ones
The hydrogen yield we calculated is 70%, which is very low. Firstly, the adsorption time has been gradually increasing, but the effect is not very noticeable ； Furthermore, currently 9 towers are in operation, and the pressure after the three-stage pressure reduction is approximately 0.57 MPa. Is this pressure too high? All of the hydrogen gas after the three-stage pressure reduction goes into the desorption system ； Third, this is our first time starting operations, and all the adsorbents are new, so the possibility of them becoming deactivated is low ； Fourth, from the operation curve, it is generally quite close to the ideal curve; if there is internal leakage in the programmable valve, this can be detected from the fishing net line. I guess the parameters still haven’t been adjusted properly. . Keep trying harder
Even with a forward pass step, this pressure is a bit high. Appropriately reduce the pressure for voltage equalization to extend the adsorption time. The hydrogen content in the desorbed gas is generally around 30%; when the purity is satisfactory, try to extend the operation time as much as possible.