Coke oven gas desulfurization

Our company’s coking process doesn’t have desulfurization at all; production is going ahead smoothly.:L

The desulfurization section of a coking plant consists of three parts: desulfurization, sulfur recovery, and ammonia evaporation from the remaining ammonia water. Its main functions are to reduce the hydrogen sulfide content in coal gas to below 20 mg/Nm3, to recover sulfur paste, and to evaporate the ammonia from the remaining ammonia water that comes from the cold drum. (1) Comparison of process options: The methods for removing H2S from gas include dry desulfurization and wet desulfurization. The dry desulfurization process is simple, but it can handle only a small volume of gas; the equipment is bulky, labor-intensive, and requires a large amount of space. Additionally, the waste desulfurizing agents are difficult to dispose of. The commonly used methods for wet flue gas desulfurization in China include the A.D.A. method, which uses Na2CO3 as the base source, and the PDS method, which utilizes ammonia present in coal gas as the base source. In the A.D.A method using Na2CO3 as the base source, numerous salts are generated as side reactions during desulfurization. To maintain a high desulfurization efficiency, salt extraction devices made of high-quality materials are required, which not only increases the initial investment in the project but also entails the use of large amounts of Na2CO3 during the production process, thereby raising operational costs. The PDS + tannin desulfurization method is a new desulfurization technique that uses ammonia in coal gas as the base source and PDS + tannin as a composite catalyst. This process features high desulfurization efficiency; there is no need to purchase alkali externally, and the circulating liquid contains little salt, so no salt recovery device is required. The waste liquid generated can be reused in coking coal. As a result, it not only offers cost savings in terms of investment and operating expenses but also provides good environmental benefits. (2) Determination of the process scheme: (a) This section adopts a wet oxidation desulfurization process that uses the ammonia contained in coke oven gas as the alkaline source, along with PDS + tannin as a composite catalyst. (b) To ensure the hydrogen sulfide content in coke oven gas, a pre-cooling tower is installed before the desulfurization tower. The pre-cooling tower type is a cross-tube indirect cooling tower. (c) The regeneration of the desulfurized rich liquid is carried out using tower-type air oxidation regeneration. (d) Sulfur recovery is carried out using a centrifuge to obtain sulfur paste. (e) For the vaporization of ammonia from the remaining ammonia solution, a reboiler is used for indirect heating to evaporate the ammonia; an appropriate amount of alkali is added to the remaining ammonia solution to account for the decomposition of fixed ammonia.

It depends on what purpose your gas is intended for; if it is only used for reheating in furnaces and as industrial fuel, the requirements are relatively low. Conventional dry desulfurization can be used, or the AS method can be employed to wash hydrogen sulfide using ammonia as a base, supplemented by alkaline washing with sodium hydroxide. If used as an industrial feed gas, such as for methanol production, further desulfurization is required, using NHD wet scrubbing to remove organic sulfur.

Who has the design data for desulfurizing coke oven gas?

Desulfurization and sulfur recovery: The raw gas from the cold drum section enters the lower part of the desulfurization tower, where it comes into countercurrent contact with the desulfurization liquid sprayed from the top of the tower. As a result, the H2S content in the gas is reduced to less than 0.02 g/m3. After the mist droplets are removed in the mist capture section, the gas is sent entirely to the ammonium sulfate production section. The desulfurization solution, which has absorbed H2S and HCN from the desulfurization tower, is sent to the solution circulation tank. It is then pumped by a solution circulation pump to the lower part of the regeneration tower, where it is regenerated in parallel with compressed air from the air compression station. The regenerated desulfurization solution is returned to the top of the desulfurization tower for cyclic spraying to carry out desulfurization. Sulfur foam is discharged from the expanded section at the top of the regeneration tower into the sulfur foam tank, where it is pressurized before being sent to a pressure filter for the production of sulfur paste for sale. The clear liquid separated in the filter press is sent to the solution circulation tank for reuse. The remaining ammonia water from the cold drum is heat-exchanged with the ammonia-vaporizing wastewater coming from the bottom of the ammonia vaporization tower in the ammonia water heat exchanger; after that, 40% NaOH solution is added to it before it enters the ammonia vaporization tower. It is directly distilled by steam in the ammonia vaporization tower; the ammonia gas produced enters the ammonia fractionator. The liquid that condenses goes directly to the top of the ammonia vaporization tower as reflux. The ammonia vapor containing approximately 10% NH3, which has not condensed, enters the ammonia condenser where it is condensed into concentrated ammonia solution, which is then sent to the desulfurization unit as a supplementary liquid for desulfurization. The ammonia-vapor-containing wastewater discharged from the bottom of the tower is exchanged heat with the remaining ammonia water in an ammonia-water heat exchanger before being sent to the wastewater tank. Thereafter, it is pressurized by a wastewater pump and cooled by a wastewater cooler, then sent to the cold drum and the electrostatic capture section for washing the exhaust gas, before being sent for biochemical treatment.