The complex iron desulfurization process utilizes the redox properties of alkaline complex iron catalysts to absorb H2S from the feed gas. H2S is directly oxidized by a complex iron catalyst to generate elemental sulfur, which is converted into complex ferrous. During the regeneration process, air is blown in to oxidize the complex ferrous in the catalyst rich solution, converting the complex ferrous in the catalyst rich solution into complex ferrous, thereby regenerating and reusing. The generated sulfur is processed through the sulfur recovery system.
The principle of complex iron desulfurization reaction is as follows:
In the overall reaction, the role of chelating iron ions is to transfer the electrons obtained from the absorption reaction to the elemental oxygen during the regeneration reaction. The production of each elemental sulfur atom requires two trivalent iron ions to participate in the reaction. Therefore, although iron ions participate in the reaction, they are not consumed in the total reaction, but serve as intermediate electron carriers in the reaction of hydrogen sulfide and oxygen, and are a component of the catalyst system.
Desulfurization process flow
The biogas from the dual membrane gas tank is pressurized by a booster fan and enters the absorption and desulfurization compartment of the desulfurization regeneration tower. H2S in the acid gas enters the reaction compartment and reacts with Fe3+in the catalyst, converting it into elemental sulfur. At the same time, Fe3+is reduced to Fe2+.
The solution after reaction enters the oxidation chamber through self circulation, and oxygen in the air is blown into the oxidation regeneration chamber through a fan. Fe2+is oxidized to Fe3+, which is then self circulated back for absorption and the reaction chamber continues to absorb and react with H2S to remove over 99.99% of H2S from the acidic gas.
After the generated elemental sulfur settles in the conical section at the bottom of the desulfurization regeneration tower, it is pumped by the sulfur slurry to the plate and frame filter for sulfur filtration; The purified gas after desulfurization is sent out of the battery limit through gas-liquid separation. The waste air is discharged from the top of the desulfurization regeneration tower.
The complete set of complex iron desulfurization technology has the following advantages for biogas purification:
(1) In the desulfurization of raw gas, hydrogen sulfide is converted into sulfur in one step, and the concentration of hydrogen sulfide in the purified gas is less than 10ppm.
(2) The device has high operational flexibility, and fluctuations in hydrogen sulfide concentration from 0.5 to 2V% do not affect the operation of the device.
(3) The absorption, regeneration, and sulfur deposition are all in one equipment, with integrated design and simple process, saving land.
(4) The catalyst is environmentally friendly, and there are no "three wastes" emissions during the desulfurization process.
(5) Reliable operation, ensuring long-term stable operation.
(6) Supplied in a skid mounted manner and can be moved as needed.
(7) The unit operating cost of each cubic meter of biogas desulfurization system can be as low as 0.03-0.07 yuan.