Could someone analyze the reasons for the high hydrogen sulfide levels after the desulfurization tower in the vacuum potassium carbonate desulfurization process?
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In the vacuum potassium carbonate process, the hydrogen sulfide level behind the tower has been quite high recently, reaching up to 1000 mg/m3. Due to poor absorption in the potassium section, a large amount of sodium alkali is consumed in the sodium hydroxide spraying section. Could anyone with expertise offer some guidance? Thank you!
Check if the temperature is too high, or if the flow rate is too high, causing it to be unable to absorb it?
Reply to 2# lipanhg: The absorption temperature in the upper section is relatively high, reaching 40 degrees, while the absorption temperature in the lower section is 37 degrees； The coal gas flow rate remains essentially unchanged ； At the moment, dozens of tons of potassium hydroxide have been added to the system; could this be causing side reactions?
On the surface, it might be due to poor absorption. High temperatures are one aspect. Check again whether the solution is clean; if it isn’t, then consider the possibility of numerous side reactions and poor solution regeneration.
It is possible that the content of by-products has increased. The main by-products generated during the desulfurization process are sodium bicarbonate, sodium thiocyanate, sodium thiosulfate, and sodium sulfate. If the combined content of sodium thiocyanate, sodium thiosulfate, and sodium sulfate exceeds 100 g/L, the following hazards will occur: 1. Increased alkali consumption. 2. The increased density and viscosity of the solution cause backflow in the ejector, resulting in less air being drawn in and a lower efficiency in solution regeneration, which in turn leads to a reduced desulfurization efficiency. 3. It leads to a decrease in sulfur recovery rate. 4. If the concentration of the by-product salt is high enough to reach saturation, it will cause crystals to form, thereby blocking equipment and pipes. If the by-product salt continues to increase gradually, the alkali consumption will also rise slowly. Once it reaches a certain level, this will affect sulfur recovery and degrade the desulfurization solution, thereby impacting the efficiency of desulfurization. Finally, the alkalinity keeps dropping, and even by adding a large amount of alkali daily, it may not be possible to raise the alkalinity; at this point, other measures need to be taken.
Reply to 5# chenlu: The color of the solution is fine at present, its viscosity is not high, and the vacuum level is acceptable. However, the temperature at the bottom of the regeneration tower is a bit low (55–56 degrees), and the amount of acid vapor is very small. Could there be an issue with the regeneration process? Help me diagnose it, thank you.
It is recommended to carefully inspect the regeneration system (vacuum pump, pressure gauge, etc.)
Reply to 7# txd82: The regeneration system has been checked; no leaks were found, and it is functioning normally. It is that the temperature of the rich liquid after heat exchange is low, while the temperature of the lean liquid entering the desulfurization tower is high. Currently, the pressure at the top of the regeneration tower is between -84 and -86 KPa. There is a high amount of impurities in the bottom of the regeneration tower as well as in the desulfurization circulation tank (black substances that dissolve in hydrochloric acid but not in toluene; these are preliminarily identified as inorganic salts), which frequently cause blockages in the pump inlet filters.
Reply to 5# chenlu: What do the other measures refer to?
Great master on the 5th floor, are you referring to HPF?
It mainly depends on the operation of the regeneration tower; based on your data, the temperature in that tower is low, which prevents the acid gas from being separated. Are there any fluctuations in the temperature of the acid gas after the separator, as well as fluctuations in the pressure at the top of the regeneration tower? Has the quality of the desulfurization liquid deteriorated (increased viscosity)?