Hydrogen sulfide (H₂S) is a common toxic and harmful gas found in industries such as petroleum, natural gas, coal chemical, and biogas. It not only severely corrodes equipment and pollutes the environment but also poses a significant threat to the life safety of workers. Low concentrations can irritate the respiratory tract and eyes, while high concentrations can quickly inhibit the respiratory center, leading to suffocation and death. Therefore, efficient desulfurization has become an indispensable key step in industrial gas purification.
Among various desulfurization technologies, iron oxide desulfurizer has become one of the most widely used dry desulfurization materials due to its high desulfurization efficiency (above 98%), low cost, room temperature operation, and renewability. Its core principle is to convert toxic H₂S into harmless sulfides through a chemical reaction between iron oxide and hydrogen sulfide, achieving gas purification.
However, in practical use, many enterprises often experience decreased desulfurization efficiency, shortened desulfurizer lifespan, and even safety hazards due to irregular loading and improper operation. This article systematically reviews the specific operational methods of iron oxide desulfurizer in three core stages: "preparation—standardized loading—scientific commissioning," accompanied by practical tips and precautions to help enterprises use it correctly and fully leverage the desulfurizer's effectiveness.
Before use, it is necessary to fully understand the basic characteristics of iron oxide desulfurizer. This desulfurizer is made mainly from iron oxide as the active component, with various promoters added, appearing as brownish strip-shaped particles (common specifications φ5～6×5～15mm) with a high porosity (typically 50～60%). Its desulfurization performance is closely related to particle strength, porosity, and surface alkalinity; the stronger the surface alkalinity, the better the adsorption capacity for acidic H₂S.
Main preparation work includes two aspects:
Desulfurizer Inspection and Screening: Newly purchased desulfurizer tends to generate dust during transportation, so it must be screened to remove powder and broken particles before loading. Also, inspect the appearance; if large clumps or abnormal color (non-normal brownish) are found, indicating moisture or deterioration, it should be replaced.
Equipment Inspection: Ensure the desulfurization tower (tank) is clean and free of debris, with no significant corrosion, intact grids, smooth inlet and outlet pipelines, flexible and reliable valves, and a normal condensate discharge system to ensure timely removal of accumulated water and prevent bed moisture compaction.
Loading quality directly determines the contact area between the desulfurizer and gas and the uniformity of airflow distribution, which is a core factor affecting the overall desulfurization effect. Uneven loading can lead to airflow deviation (channeling), causing some desulfurizer to fail quickly while others are not fully utilized, seriously wasting materials.
Loading operation points are as follows:
Equipment Pre-treatment: Thoroughly clean rust, debris, and stagnant water inside the tower. Lay two layers of 8～10 mesh stainless steel wire mesh on the grid to prevent particle leakage. Then lay a 20～30mm thick layer of crushed coke or quartz sand, with particle diameter 20～30mm, as a gas distribution buffer layer to protect the desulfurizer bed from direct airflow impact.
Layered Uniform Loading: Use a rotating unloading pipe to evenly add screened desulfurizer from around the tower wall, strictly prohibiting direct dumping from the center. Control the loading height of each layer at 0.7～1 meter, lightly flatten with a wooden board after loading to ensure a smooth surface with no significant height difference. The bed height-to-diameter ratio should be greater than 3 to ensure sufficient gas contact time. The total loading amount should be calculated based on H₂S concentration, gas flow, and expected replacement cycle.
Loading Taboos and Details: Strictly prohibit personnel from directly stepping on the bed. If inspection is necessary, wooden boards must be laid to distribute weight. A protective grid or crushed coke layer should be installed at the raw gas inlet to prevent high-speed airflow from scattering the desulfurizer. After loading, check for any depressions or voids in the bed, promptly supplement and level it to ensure uniform density.
After loading is completed, the system should be started strictly following the sequence of purging and replacement, preheating and drying, and formal commissioning. This prevents sudden impact that may damage the bed structure or reduce desulfurizer activity.
Purging and Replacement
Close the inlet and outlet valves, and purge the tower with inert gas (such as nitrogen) for at least 30 minutes. The flow velocity should be controlled at 0.1–0.2 m/s. This process removes air and impurities, preventing explosive mixtures of H₂S and air while avoiding oxygen consumption of the desulfurizer. Oxygen content must be tested after purging, and only when it meets the required standard can the next step proceed.
Preheating and Humidity Control
The suitable operating temperature for iron oxide desulfurizer is 20–100°C. Gas humidity must be properly controlled. A small amount of water vapor helps form a thin liquid film on the desulfurizer surface, improving reactivity; however, excessive moisture can cause condensation, pore blockage, and bed compaction. If necessary, the gas source can be moderately preheated (not exceeding 50°C) or pre-dehydrated.
Formal Commissioning and Parameter Control
Gradually open the inlet valve and slowly increase the flow rate to avoid bed impact. Key parameters should be controlled as follows:
Space velocity: 400–800 h⁻¹ under normal pressure; up to 1000 h⁻¹ under pressurized or low-concentration conditions
Linear velocity: Maintain 0.10–0.30 m/s to ensure uniform gas distribution
Pressure: Typically controlled from atmospheric pressure up to 3.92 MPa (40 kg/cm²)
Strict adherence to these procedures can significantly improve desulfurization efficiency, extend the service life of the desulfurizer, and ensure production safety.
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