I have questions regarding the desulfurization of liquefied gas and gasoline

1. What solvent is used for desulfide removal in alkali solution regeneration? How should the solvent that has absorbed disulfides be disposed of? The alkali solution we use is mixed with air before entering the oxidation tower; after passing through a heater, it enters the oxidation tower where a reaction takes place. Subsequently, it goes to a disulfide separation tank for separation. The regenerated alkali solution can be reused, while the disulfides are sent to the alkali tank 2. How are the exhaust gases generated during the regeneration of the alkali solution handled? How is oxygen content controlled when sending it to an incinerator? Our exhaust gases enter Regeneration Chimney 3 after passing through the exhaust gas separation tank. What is the effectiveness of gasoline desulfurization? Is there any problem? The effect is very good, and it can meet the ** standards

My brief opinion: 1. What solvent is used for desulfide removal in alkali solution regeneration? How should the solvent that has absorbed disulfides be disposed of? In cases where the thiol content is relatively high, solvents can be used to absorb disulfides; such solvents include hydrogenated gasoline and desulfurized straight-run gasoline ； The solvent that has absorbed disulfides is then subjected to rehydrogenation or alkaline washing; since the amount of this solvent is relatively small, it has almost no impact on the existing equipment. 2. How should the exhaust gas generated by the alkali solution regeneration be treated? How is oxygen content controlled when sending it to an incinerator? There are roughly two methods currently used for exhaust gas disposal: one is venting, which includes direct venting and venting after injecting nitrogen ； Another method is incineration, which includes burning directly in an incinerator, as well as burning after injecting fuel gas. These methods all have some problems, and there are discussions on the forum regarding them. 3. What is the effect of gasoline desulfurization? Is there any problem? The desulfurization of gasoline using alcohol seems to work well in the currently operating units, and the effectiveness can be guaranteed. The problem is that it cannot remove total sulfur, and it is suitable for situations with relatively low total sulfur content.

1. What solvent is used for desulfide removal in alkali solution regeneration? How should the solvent that has absorbed disulfides be disposed of? We did not use any solvents; the disulfides formed remained in the alkaline solution. A tank was designed to store these disulfides, but it was not used. In the end, the disulfides were discharged along with the alkaline residue. 2. How should the exhaust gases generated during the reprocessing of the alkaline solution be handled? How is oxygen content controlled when sending it to an incinerator? We discharge the exhaust gases directly into a catalytic chimney (located very close to the chimney). In the case of liquefied gas desulfurization, these gases are sent to the incinerator along with acidic gases. The oxygen content is controlled based on the amount of combustible gas, in order to ensure that the incinerator does not overheat. In short, if there is less exhaust gas and acidic gases, more oxygen is used; if there is more of these gases, less air is supplied to prevent the furnace from overheating

Alkali solution regeneration process: In the oxidation tower, the catalyst converts RSNa into water-insoluble disulfides, thereby regenerating the alkali solution. The disulfides move along with the alkali solution to the separation tank, from where they are discharged to the disulfide tank through the top of the tank; subsequently, nitrogen is used to push them to the disulfide treatment unit. The components of the exhaust gas generated by the separation tank can be absorbed using diesel as an absorbent; after absorption, it is returned, while the exhaust gas is discharged into a chimney or incinerator. As for the desulfation of fiber membranes, a fixed container is used, along with an appropriate carrier; an alkaline solution along with a catalyst are applied cyclically to the carrier to deposit alkali thereon, and then the alkaline solution is removed. Generally, such methods have a too short usage period and require frequent handling; the alkali needs to be replenished every 7–20 days. It is better to use a continuous alkali circulation method, which allows for a longer usage period with the alkali needing to be replaced only once every 30 days or more.

"As for the desulfation of fiber membranes, a fixed container is used, along with an appropriate carrier; an alkaline solution along with a catalyst are applied cyclically to the carrier to deposit alkali thereon, and then the alkaline solution is removed. Generally, such methods have a too short usage period and require frequent handling; the alkali needs to be replenished every 7–20 days. It is better to use a continuous alkali circulation method, which allows for a longer usage period with the alkali needing to be replaced only once every 30 days or more. "This process is different from the ordinary fiber membrane process. Could you explain the details? In the conventional fiber membrane desulfurization process, the key technology lies in the fiber membrane equipment; there is no issue of alkali accumulation, and the alkaline solution is recycled. However, the replenishment of alkaline solution can be done continuously or intermittently, depending on the sulfur content of the raw material and changes in the concentration of the alkaline solution.

Reclaimed alkaline solution contains a high concentration of disulfides, and achieving precise separation is the key technology determining the quality of this reclaimed alkaline solution. Using gasoline back-extraction yields certain results, with an extraction rate of around 30%. However, in terms of investment and hydrotreatment costs, its cost-performance ratio needs improvement. Another problem with back-extraction is that it can cause the liquefied gas oil stain test to fail, as hydrocarbons with a molecular weight of C5 or higher remain in the alkaline solution; during the cycle of desulfurization and denaturation, these hydrocarbons dissolve into the liquefied gas. Similar problems have been observed in several industrial installations.

1. What solvent is used for desulfide removal in alkali solution regeneration? How should the solvent that has absorbed disulfides be disposed of? The desulfurization and alkylation unit for liquefied gas in Maoming is capable of separating around 18 tons of disulfides per month, without using coal bed desulfurization or back-extraction methods. The separated disulfides can be sent for hydrogenation; currently, their research institute is studying the use of disulfides in fine chemical applications. 2. How should the exhaust gas generated by the alkali solution regeneration be treated? How is oxygen content controlled when sending it to an incinerator? Depending on the different alkali regeneration processes, the fate of the exhaust gases varies; it is possible to request exhaust gas treatment solutions from the technology provider. 3. What is the effect of gasoline desulfurization? Is there any problem? In the past two years, gasoline deodorization units using the liquid film process have been built in China one after another. This process provides a large surface area for liquid-liquid-gas mass transfer, while also overcoming the problem of alkali entrainment. The greatest advantage of this process is that it requires no activators, only one main unit of equipment is needed, there is no complexity associated with switching, the concentrations of the alkaline solution and catalyst can be controlled, and the system operates in a completely continuous manner.