The issue of high levels of by-products salts in the desulfurization solution

Measure the total amount of reducing substances in the solution! What is the total amount of by-products now? An increase in the content of by-products will affect the operation of the sulfur recovery system; try raising the sulfur melting temperature to around 150 degrees! Be careful of tower blockages; it’s cold lately!

1. Lower the temperature of the gas and solution to stabilize the absorption and regeneration processes； 2. The formation of by-products is closely related to sulfur melting; the overflow volume should be reduced as much as possible while ensuring foam separation in the regeneration tank ； 3. The liquid discharged from the sulfur melting tank should be cooled and settled before being reintroduced into the regeneration tank ； 4. Increase the solution circulation rate to prevent the precipitation of by-products from blocking the tower.

The liquid discharged from the sulfur melting tank should be cooled and settled before being reintroduced into the regeneration tank. As far as I know, some manufacturers use four or even five stages of sedimentation and cooling, which shows just how important this process is! ~! !

Does anyone know what the ingredients of Melted Sulfur Clear Night are? The concentration of the by-products inside is not higher than that in the desulfurization liquid; go ahead and test it if you don’t believe me. You must have seen manufacturers that do not recycle sulfur foam; their by-product salt content is not high, right? ! Melting sulfur is a influencing factor but not the main one.

Thank you all for your replies. The 150°C mentioned by Branch ** probably refers to the temperature at the bottom of the sulfur melting tank. The Handan patented technology we purchased doesn’t have a thermometer on the lower part. The outlet temperature of the clear liquid from the sulfur melting tank is currently controlled at around 80°C. It’s not clear whether this is appropriate; since the tank has become clogged due to operational issues, we don’t dare to raise the temperature too much. The main by-product salt in our desulfurization solution is sodium sulfate; the concentration of sodium thiosulfate is very low, at 0.5 g/l, and it has remained at this level for several years. We have tried to change this situation for a long time without success. Could it be due to an excess amount of air during the regeneration process? I appreciate your advice.

  1. The solution temperature is maintained at 42-45°C and remains relatively stable. Is this appropriate? Can it be lowered further? 2. We have also considered condensing and settling the liquid discharged from the sulfur melting tank, but what to do with the by-products that settle down? Environmental regulations are very strict these days; how do others handle this issue?

1. The solution temperature can be controlled at 40°C or even lower, as long as it does not affect the desulfurization efficiency. 2. After cooling and sedimentation of the liquid discharged from the sulfur melting tank, the sediment is mainly sulfur paste, which needs to be cleaned regularly; it can be used for intermittent sulfur melting. 3. Sodium sulfate is the final product of further oxidation of sodium thiosulfate; if the loss from the solution is low, this results in an increase in the sodium sulfate content. 4. It is recommended to use a centrifuge for sulfur recovery. The key to desulfurization lies in sulfur recovery! In response to the comment on floor 5: Our company’s desulfurization unit originally used intermittent sulfur melting; the waste liquid was not recycled, and the concentration of by-products in the solution was around 10 g/l ； After continuous sulfur melting, the increase after one year rises to over 50 g/l.  

It is fine to keep the temperature of the clear liquid between 60 and 110 degrees, as long as the outlet pipe is not blocked. The formation of by-products prevents a large amount of sulfur from existing in the form of elemental sulfur, which affects the operating temperature of the sulfur melting vessel. The solution remains partial replacement of the desulfurization liquid. On the forum, one should talk about the actual situation; issues that cannot be resolved through environmental protection should be left for experts to study, and the actual methods of handling things should be stated truthfully. At the same time, please reply with the content requested by the poster, using your own responses as a reference for those seeking help.

1. Lowering the solution temperature facilitates absorption; therefore, the lower the temperature, the better the desulfurization effect. However, the same is not true for regeneration – the lower the temperature, the worse the regeneration effect； 2. Complete desulfurization is not the same as partial desulfurization; the formation rate of by-products is slow. Based on what you’ve said, do you think the by-product concentration can remain stable at 10 g/l even after a year without continuous sulfur melting? Regarding the issue raised by the poster, the first thing to address is the sulfur melting problem; the temperature at the outlet of the clear liquid should be increased to around 90–100 degrees to see if sulfur can be produced. At the same time, the clear liquid should not be recycled until the concentration of by-products drops to a reasonable level.

Agree with what was said above: first resolve the sulfur issue, and then take a look at the situation with the by-products.

Thank you all. Personally, I think it might be a leak in the jacket of the sulfur melting tank, which is causing poor sulfur melting results; however, I will make adjustments based on everyone’s suggestions.

If it is a jacket leak, it can be detected from the condensate. As the original poster mentioned, the sodium thiosulfate content is low while the sodium sulfate content is high; moreover, the temperature of the return liquid is not very high. It is likely that the suspended sulfur content in the solution is high, or the pH value of the solution is high, or the dissolved oxygen content in the solution is too high, or the residence time in the regeneration tank is too long – all of these factors can lead to an increased amount of sulfates being formed. With a high content of sodium sulfate, it is possible to draw out part of the solution during cold weather; the solution will then cool naturally, allowing sodium sulfate to crystallize out – this method is very effective! This post was last edited by ypff on 2008-2-29 00:42]

This post was last edited by wycasia on 2010-10-21 23:03. Desulfurization and sulfur recovery are part of a whole; taking a piecemeal approach often doesn’t work! Our company also uses continuous sulfur melting reactors, and sometimes it’s difficult to determine the cause of problems that arise!

Desulfurization is a cycle; its starting point and ending point can be considered to be in the regeneration tank； With the sodium sulfate concentration mentioned by the poster, it’s very difficult to achieve crystallization through natural cooling ； A total concentration of by-salts exceeding 300 g/l is relatively effective ； Furthermore, the concentration of sodium thiosulfate is unreliable; it is recommended to measure it again.

It is recommended to try keeping the temperature between 60 and 70!

What is the pressure at the outlet of the sulfur melting tank pump?

A fairly comprehensive explanation; worth learning*

It is recommended to try changing from continuous sulfur melting to intermittent sulfur melting.

It might be due to excessive air being introduced, or the rich liquid tank being too small resulting in insufficient residence time.

I can tell that one of the continuous sulfur melting reactors in your factory might not be working properly, as it gets clogged frequently