Hydrogenated dry gas

It may be because, in addition to hydrogen sulfide, there are other sulfides present in the hydrogenated dry gas, such as thioethers or organic sulfur compounds, which results in a higher total sulfur content. The specific types of sulfides can be determined through further testing and analysis. .

Is the dry gas not dry enough, with too much organic sulfur?

It depends on the sulfur content of the raw materials; it’s usually over ten thousand

In the hydrogenated dry gas after desulfurization, the hydrogen sulfide (H₂S) content is within acceptable limits, but the total sulfur content is high; this may be caused by the following reasons: 1. Incomplete removal of organic sulfides. Reason: In addition to H₂S, the hydrogenated dry gas may also contain other organic sulfides such as thiols, thioethers, carbon disulfide, thiophenes, etc. If the desulfurization process (such as the amine method) is primarily aimed at removing H₂S, with insufficient efficiency in removing organic sulfur, this can result in H₂S levels being within acceptable limits while the total sulfur content exceeds the specified limits. Solution: Optimize the desulfurization process (e.g., by using composite amine solutions or specialized solvents). Add a hydrolysis reactor to convert organic sulfur into H₂S before removal (e.g., COS is hydrolyzed into H₂S and CO₂). 2. Incomplete hydrogenation. Reason: During the hydrogenation process, if the reaction temperature, pressure, or catalyst activity is insufficient, it may result in organic sulfur not being fully hydrolyzed into H₂S, leaving behind thiolates, thioethers, and similar compounds. Solution: Check the activity of the hydrogenation catalyst (whether it is deactivated or poisoned). Adjust the reaction conditions (increase temperature, pressure, or hydrogen-to-oil ratio). 3. Insufficient selectivity of the desulfurization solvent. Reason: If the amine solution used (such as MDEA) has high selectivity for H₂S but low efficiency in absorbing organic sulfur, it will result in residual organic sulfur. Solution: Replace the solvent (e.g., use mixed amines or physico-chemical composite solvents). Add auxiliary desulfurization units such as activated carbon adsorption. 4. Sampling or analysis errors: Reason: H₂S detection methods (such as lead acetate test strips) may not be able to detect other sulfides ； If the total sulfur analysis (such as the ultraviolet fluorescence method) is not properly calibrated, it may overestimate the results. Solution: Verify the analysis methods to ensure consistency in the detection standards for H₂S and total sulfur. Resample and analyze the sulfur forms using precise instruments such as gas chromatography (GC-SCD). 5. Process control issues: The reason is that parameters such as the liquid-to-gas ratio in the desulfurization tower, regeneration temperature, and the quality of the lean liquid are not optimal, which affects the removal of organic sulfur. Solution: Optimize the operating conditions of the desulfurization tower (such as increasing the circulation rate of the lean liquid or the regeneration efficiency). Monitor the sulfur load in the lean liquid to prevent solvent saturation. 6. Changes in the sulfur form of the feed gas: Reason – The composition of sulfur in the upstream feed changes (e.g., an increase in the proportion of organic sulfur), but the desulfurization process is not adjusted accordingly. Solution: Strengthen the monitoring of sulfur forms in the feed gas and adjust process parameters in a timely manner. 7. Equipment failure or leakage: Cause: Internal leakage in the heat exchanger leads to cross-contamination of sulfides, or contamination of the sampling system. Solution: Check the equipment’s sealing and the cleanliness of the sampling system. Suggested steps: Analyze sulfur forms: Determine the specific types of organic sulfur using GC-SCD. Process audit: Check whether the operating parameters of the hydrogenation and desulfurization units meet the specified standards. Solvent test: Evaluate the absorption capacity of the amine solution for organic sulfur. Catalyst evaluation: Check whether the activity of the hydrogenation catalyst has declined. Through targeted troubleshooting, the root cause can be identified and the desulfurization effect optimized.