Complete Technology of Hydrogen Production from Natural Gas
〖Natural gas desulphurization〗
At 360 degrees and a pressure of 1.6MPa, the raw material gas that has been mixed with the return hydrogen first converts organic sulfur into inorganic sulfur through the cobalt-molybdenum hydrogenation catalyst, and then enters the reaction of manganese oxide and zinc oxide desulfurizer to remove the total sulfur in the raw gas Fall below 0.1ppm
RS + H₂ -> HR + H₂S
H₂S + MnO -> MnS + H₂O
H₂S + ZnO -> ZnS + H₂O
(RS is: RSH-mercaptan; R₁SR₂-sulfide; R₁SSR₂-disulfide; C₄H₄S-thiophene; COS- carbon sulfide; CS₂-carbon disulfide)
〖Steam reforming of natural gas〗
The steam reforming of natural gas is at 780～850℃, 1.2～3.0Mpa, using steam as the oxidant, under the action of nickel catalyst, the hydrocarbon material is transformed to obtain the raw gas for producing hydrogen.
CH₄ + H₂O -> CO + 3H₂ -206kJ/mol (endothermic)
CO + H₂O -> CO₂ + H₂ 41kJ/mol (exothermic)
Due to the high reaction temperature and short reaction residence time, the concentration of carbon monoxide in the reaction product is higher than that of carbon dioxide. The high temperature and high water-to-carbon ratio are conducive to the improvement of methane conversion.
The higher alkanes are first cracked into lower alkanes and CO and H₂ are generated under the action of water vapor. This process also occurs at the same time as carbon evolution, carbon removal, polymerization and other side reactions, and also produces H₂.
CnHm + nH₂O -> n CO + (n+m/2) H₂
〖Carbon monoxide and steam shift reaction〗
The conversion reaction product has higher CO. It and the unreacted water vapor are transformed under the action of the catalyst Fe₃O₄ to generate CO₂ and H₂, which can increase the amount of hydrogen, reduce the consumption of raw natural gas, and reduce the pressure swing adsorption purification load.
Transformation principle：
CO + H₂O -> CO₂ + H₂ 41.2kJ/mol
Methanation reaction：
CO + 3H₂ -> CH₄ + H₂O (Exothermic)
〖Device Characteristics〗
Under high temperature conditions, natural gas and water vapor are converted into hydrogen, carbon monoxide, and carbon dioxide through the catalyst bed, and then undergo intermediate transformation, decarbonization, and pressure swing adsorption to obtain the product H₂. It has the following salient features:
1. Reasonable heat utilization, optimized heat exchange method, and improved thermal efficiency.
2. Select the anti-carbon evolution conversion catalyst, and the upper and lower catalysts have different sizes to ensure the conversion rate while fully considering the resistance of the furnace tube.
3. Use a variety of special high-efficiency adsorbents to ensure the quality of hydrogen.
4. The analytical gas is stabilized and then sent back to combustion, which has little effect on the combustion fluctuation of the furnace.
5. The device is equipped with a backup sequence. When the PSA fails, the tower can be cut to ensure the continuity of production.
〖Performance〗
Yield：On demand
Press：0～2.5 MPa
Purity：Up to 99.999%
Unit consumption: less than 42Nm³CH₄/100Nm³-H₂
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