H2/He Separation Technology
H2-absorbing materials are like sponges absorbing water, which can reversibly absorb and release large amount of H2. Once H2 comes into contacting with a H2-absorbing material, it can decompose into H atoms on its surface, which then diffuse into the material structure until it reacts with the material to form hydrides. At this point, H2 is stored in an atomic state in the crystallization point of the H2-absorbing material (the gap between tetrahedra and octahedral). H2-absorbing material is a material that realizes reversible adsorption and discharge of H2, which has significant advantages such as large H2 adsorption capacity, low storage pressure, small module size, and convenient use in limited space.
The H2/He gas mixture is treated with a H2-absorbing material, and the material absorbs the H2 in the mixture and discharges the He, thereby separating H2 and He. The absorbent material bed is switched to the regeneration process, and the absorbed H2 can be released by heating the material to realize the regeneration of the H2-absorbing material.
The H2 and He separation material is a material that realizes reversible adsorption and discharge of H2. When H2 is selectively absorbed, H2 reacts chemically with the material to form hydrides, which captures the gaseous H2 in a solid state. When regulating the external pressure and temperature, the hydride will decompose and reversibly release H2 with a purity of more than 99.999%mol, and the hydride will redecompose and return to the intrinsic state.
H2-absorbing materials are a series of materials that have excellent adsorption properties for H2 or that can react reversibly with H2 to achieve H2 storage and release. The purification system uses a novel H2-absorbing material composed of titanium, manganese, zirconium and transition metal elements composition (cobalt, chromium, nickel, lanthanum and vanadium-iron alloys or compounds of two or more metal elements). It is prepared by vacuum induction melting and has a simple manufacturing process. The purification material could purify H2 at -20~120 Celsius degree, which is lower than the working temperature of the Zr-Mn-Fe alloy by 300 Celsius degree or more. The content of the impurity gas such as N2 and O2 in H2 can be reduced from several hundred ppmv to less than 100ppbv by one stage purification, and H2 could be purified to 6N, suitable for pan-semiconductors, fuel cells, high purity gas chromatography and many other fields and occasions requiring ultra-high-purity H2.
The advantages of H2 helium separation technology include, but are not limited to, the following:
1 High level of security
For the separation of He and H2, the conventional solution is to add additional O2, and then oxidize H2 to H2O through copper oxide or palladium catalysis or combustion, and then remove H2O and excess O2 respectively, so as to achieve the purpose of separating H2 in He.
1.1 Security risks of conventional technologies
The explosion limit of H2 is about 4~76%mol, and the extremely high risk of explosion caused by direct combustion or catalytic oxidation. At the same time, the huge heat generation is very dangerous due to the large concentration and flow rate of H2.
1.2 High safety of the H2-absorbing method
The separation of H2 and He by H2-absorbing materials does not require combustion, and the whole separation process can be carried out in the highly safe environment and temperature of circulating water.
2 Flexible operation scope, little technical risk, and reliable performance
2.1 Technical risks of conventional technologies
Whether it is combustion or catalytic oxidation, the amount of O2 is calculated based on the amount of H2, and feed gas flow and content fluctuations can cause process fluctuations, causing technical and safety issues.
In addition, since the H2 concentration is in the explosion range, multi-stage dilution or reflux is required. Secondly, H2 and O2 require multiple reactions, so the process is more complex with lower security and cost performance. In addition, the way of adding O2 catalytic combustion should need extra O2 station, deO2 tower, drying and dehydration tower, etc., the process is complex and under the strictly safety supervision.
2.2 No other gases are introduced into the H2-absorbing process
In addition to H2 in He by catalytic oxidation, other trace impurities in the air will be brought into the air due to the active introduction of O2, resulting in the final concentration of He not meeting the standard and having to increase the low-temperature separation unit.
2.3 Extremely high technical tolerance of H2-absorbing method
The H2-absorbing method uses special alloy materials to separate H2 and He, which is suitable for any proportion of H2/He, and no other gases are introduced in the entire process, even if the feed gas composition changes or fluctuates, it will not affect the stability and safety of the process.
3 Energy and resources saving, good economy benefits, meeting with carbon neutrality and carbon emission reduction
Whether it is combustion or catalytic oxidation, it is necessary to configure a series of auxiliary devices and produce a large amount of solid waste, which not only requires huge investment (especially worse with little feed gas flow), but also wastes a large amount of H2, which is a big waste of resources and energy. At the same time, due to the laying of auxiliary devices, it will occupy a large land resource.
The H2-absorbing method uses special alloy materials to separate H2 and He, instead of catalytic combustion to remove H2 in He, but to achieve perfect separation, the by-product ultra-pure H2 is not only an efficient fuel, but also an important chemical raw material, but also a commonly used gas in the electronics industry.
