Exhaust gas H2S level exceeds limits in the low-temperature methanol wash concentration tower
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In the production process of low-temperature methanol washing, 1: Is there a problem of excessive H2S levels in the air discharged from the concentration tower? What is an appropriate concentration for H2S? Are there environmental standards for H2S emissions? 2. What actions should be taken if H2S levels are above the limit?
If it exceeds the limit, quickly find ways to reduce it – by lowering the nitrogen in the stripping process and increasing the operating pressure
If the hydrogen sulfide level at the outlet of the concentration tower is too high, it is possible to increase the amount of sulfur-free methanol flowing back to Tower 3; at the same time, it is necessary to ensure that the carbon dioxide levels at the outlet of Tower 2 remain within the specified limits.
There are corresponding standards for exhaust emissions, and the emission height varies as does the concentration; you can look up specific details online. What’s your process? Let’s talk about our case. We use the 6-tower process from Dalian University of Technology. When adjusting the tower pressure, we need to take into account solution circulation; when adjusting the nitrogen in the stripping phase, we have to consider the regeneration load; and when adjusting the reflux of the CO2 product stream, we need to consider the sulfur content in that CO2 product. These are the conventional approaches, while other situations require special handling.
The H2S content in the off-gases from the low-temperature methanol washing process at Fengxi Group is less than 2%. Our company’s patented technology, namely the \"selective oxidation sulfur production process and catalyst\", has been in use for 3 years; the total sulfur content in the exhaust gases is less than 150 ppm (well below the national standards). The purity of the solid sulfur produced reaches 99.9%, with a total investment of around 8 million yuan
1 Increase the amount of methanol used for top washing and maintain a stable flow rate. 2 Reduce the amount of nitrogen used in gas stripping to keep it within the specified range. 3 Enhance exhaust gas analysis and take appropriate measures
I think we also need to pay attention to the temperature of sulfur-containing methanol; at low temperatures, even if the nitrogen stripping flow rate is higher, the sulfur content in the exhaust gases will not exceed the allowable limits.
1. Reduce the amount of nitrogen used in air lifting. 2. Reduce the absorption volume in the concentration section. 3. Check whether the flash pressure in the concentration section is too low. 4. Check whether the flash pressure in Section 1 is normal. 5. Reduce the section according to the situation based on the amount of methanol absorbed. 6. Check whether the methanol absorption capacity of the desulfurization tower meets the requirements for gas flow rate
I agree with the view from Floor 6; if it is a 6-tower process, there should be no problem with the exhaust gas passing through the scrubber towers, and the H2S level can be kept within the allowable emission limits