Utilization of synthetic ammonia off-gas
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During the ammonia synthesis process, the off-gases produced contain a certain amount of methane and hydrogen. What technologies can be used to extract methane and hydrogen from it? The requirements are that the purity of hydrogen be 99.9% and that of methane be 96%.
Friend, using pressure swing adsorption separation to recover purge gas can yield H2 with a purity as high as 99.9%. Our facility uses hollow fiber membrane separation technology, achieving a hydrogen recovery rate of 95% with a hydrogen purity of around 98%
It’s impossible to meet the original poster’s requirements with just one set of devices. Because with hydrogen recovery, the permeate gas is 99% H2, but the exhaust gas consists of methane and nitrogen, with a low methane content. To recover 99% of methane, it seems we will need to find another approach.
Purification of 99.9% H2 can be achieved by recovering purge gas using pressure swing adsorption separation. What’s the use of methane with a recoverable purity of 96%? I really want to recycle it, using cryogenic separation.
Pressure swing adsorption is better: it not only produces gas of high purity, but also handles large volumes of material, features simple equipment, and has a high degree of automation!
Is that amount of methane worth it?
We use membrane separation technology to separate hydrogen with a precision of up to 98%; the remaining off-gas is then passed through soft water to absorb the ammonia contained in it, before being used as fuel in the boiler to maintain its temperature at a stable level
Hydrogen recovery is carried out using membrane filtration; our plant employs Prisen hollow fiber membranes. Two of these membranes are usually sufficient for operation, with one serving as a backup. The hydrogen content in the permeate gas is over 98%, while the gas from the non-permeate stream can be used as fuel. Additionally, by removing the inert gases from this non-permeate stream, the accumulation of such gases in the synthesis tower is reduced, which facilitates the synthesis reaction.
We use a combined absorption tower to absorb the ammonia present for urea decomposition, while the remaining ammonia is sent to a waste heat furnace for combustion
Hydrogen recovery is carried out using membrane filtration; our plant employs Prisen hollow fiber membranes. The hydrogen content in the permeate gas is over 98%, while the non-permeate gas is used to power the gravity-driven ammonia recovery system. Additionally, by removing the inert gases from the non-permeate gas, their accumulation in the synthesis tower is reduced, which facilitates the synthesis reaction
Hydrogen is extracted using hollow fiber membrane separation, with the hydrogen content in the permeate gas exceeding 99%.