Alkali solution for liquefied gas alkali washing
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Dear sea friends, how do you handle the slag resulting from the alkaline washing of liquefied gas? The concentration of the alkaline solution in my tank is now over 20%, but the viscosity of the alkaline solution has increased significantly. The motor keeps experiencing overcurrent, so I’m forced to reduce the circulation rate. Yet sulfur still doesn’t get removed. What should I do?
It needs to be replaced with fresh material. Don’t you have process cards?
Sulfur exists in liquefied gas in various forms, including hydrogen sulfide, elemental sulfur, non-thiophene compounds (thiols, thioethers, disulfides), and thiophene compounds. Alkali washing can only remove some hydrogen sulfide and thiol compounds; large molecular thiophene sulfides cannot be removed by alkali washing at all.
Our unit requires an alkali concentration of 10%-12%; at 20%, it’s necessary to replace the alkali. The slag resulting from the alkaline washing using liquefied gas is sent to the sulfur unit for reprocessing
A concentration of 20% is also acceptable, but circulating only alkaline solution for desulfurization is not sufficient. Alcohol desulfurization also requires a catalytic alkaline solution. Hydrogen sulfide also needs to be removed using diethanolamine
It should be replaced. We’ve taken all our waste alkali outside for disposal. And don’t think that just because something has been treated with alkali it’s necessarily qualified – there are many types of sulfides here; for example, our stabilizer copper corrosion test always fails
The alkali solution resulting from the desulfurization and alkylation of liquefied gas is generally discharged into a waste alkali tank for centralized treatment; the commonly used treatment method at present is acidification. If the content of alkaline residues in the alkali solution is too high, the solution must be replaced; otherwise, it will affect the desulfurization efficiency of liquefied gas.
Reply to 1# lijianhuai: For alkali washing to remove desulfurized alcohols, the alkaline solution can be oxidized and regenerated, which helps to reduce the emission of alkaline sludge.
We replace the alkali with a new one. Occasionally, even after replacing it, the desulfurization result still doesn’t meet the standards; however, the result becomes acceptable after running a set of parallel tests. I’m not sure if it’s the people in the laboratory causing this issue
The desulfurization efficiency of liquefied gas cannot be determined solely by the alkali concentration: 1. A too high alkali concentration does not necessarily lead to better desulfurization results; generally, it should be between 10–15% (by mass concentration). 2. The concentration of catalysts in the alkaline solution also has an impact. 3. The quality of alkali solution regeneration. (Regeneration temperature, air volume, etc.) 4. The performance of the hydrogen sulfide removal extraction tower ahead. 5. Is the amount of liquefied gas due to high operating load or high sulfur content in the liquefied gas itself? 6. The quality of disulfide separation. 7. Regularly discharge alkali slag.
Reduction washing can only remove lower-level sulfur, while higher-level sulfur requires liquefied gas desulfurization