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This unit generates the H2 gas that is used in batch annealing line. The HGM-2000 is a factory-built steam methane reformer system that automatically converts natural gas and deionized water to hydrogen. The HGM-2000 includes a built-in gas cleanup system that provides up to 99.999% pure hydrogen at flow rates between 31.1 to 56.6 Nm3/hr. Pure hydrogen is generated by the HGM through the following steps:
- Steam reforming of natural gas.
- Shift reaction of carbon monoxide.
- PSA (Pressure Swing Adsorption) purification
The natural gas is mixed with steam generated in the HGM from de-ionized water and is passed through the reformation vessel. The reformation of methane and higher hydrocarbons typically found in natural gas in the presence of steam is governed by the following reactions in the top section of the HGM reactor:
A) Cm Hn + mH2O → mCO + (m + n/2)H2
For methane (m=1 & n=4) this reaction becomes:
B) CH4 + H2O → CO + 3 H2
Carbon monoxide, produced by the reformation reaction, mixes with additional steam at a lower temperature to produce carbon dioxide and more hydrogen as follows:
C) CO + H2O → CO2 + H2 (the water-gas shift reaction)
The reformate gas produced by the above reactions is approximately 75% hydrogen by volume, on a dry basis. After cooling, the impurities including CO2, CO, CH4, N2 and water are removed using a built-in pressure swing adsorption (PSA) purification system. The purge stream from the PSA (containing some hydrogen plus CO and CH4 fuel) is burned and the heat produced provides most of the energy required for the overall reaction, which is endothermic.