Exhaust emissions do not meet standards
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Acid production from flue gases from boiling roasting metallurgy, wet adiabatic evaporation and conventional purification and washing processes, two-turn two-absorption acid production； No tail suction device is installed. The sulfur dioxide concentration is 5.1%, and the sulfur dioxide level in the exhaust gases is around 260 mg/nm3. The catalyst used is domestic; the conversion efficiency after one cycle is over 94%, while the overall conversion efficiency is 99.78%. This still isn’t sufficient – it does not meet the standards. Is there any solution? Reduce exhaust emissions?
There are many methods; it’s not clear which one would be suitable for your company: 1. Use power to remove mist; 2. Operate the back-suction device; 3. Replace the catalyst to improve conversion efficiency
It’s not easy to meet the standards; it’s better to use an exhaust treatment device as a safety measure
Online environmental monitoring – penalties are imposed if violations are detected; the pressure is high. It’s better to use a rear suction system!
What are the exhaust emission standards? The existing sulfuric acid emission standards should be met.
Environmental protection inherently involves costs, and exhaust gas treatment is an effective way to address excessive emissions.
Our plant uses end-suction; water is used for a second washing step, and then the water is measured before being added to the circulating acid tank, with the concentration kept at 73 mg/nm3
This conversion rate is already good enough; the emission levels should meet the standards, right?
Your current figures show a quite good conversion rate; there isn’t much room for further improvement. You should be aiming to reduce the electricity consumption associated with flue gas desulfurization. Suggested approaches: 1. Increase the amount of catalyst in stages 3 and 4. You can add them in both places; if you want to add them only in one place, then calculate the balanced conversion rate for the three layers based on the operating parameters of your system (it’s likely there won’t be much room for adjustment). 2. Adjust the operating conditions (temperature, pressure) of the four-stage conversion layers to maximize the secondary conversion rate.
Agree with what was said above – a conversion rate of 99.78% is already quite good! However, the simplest and most convenient method is still to adjust the catalyst loading scheme, replace it with a catalyst of higher activity, or increase the amount of catalyst placed at the bottom. The catalyst at the bottom could be replaced with a cesium-containing catalyst that exhibits good activity at low temperatures and high conversion rates. Catalyst manufacturers can conduct a simulation calculation based on the actual operating conditions of the plant, to determine whether adjusting the catalyst loading strategy and increasing the amount of catalyst used can resolve the emission issues. If the catalytic method doesn’t work, then consider other methods, starting with the simplest ones and moving on to more complex ones!
If you’re not in a special area, your exhaust emissions should meet the standards. It’s not clear though whether they remain below these levels at all times; if there is instability, it’s recommended to use an exhaust extractor. Our company uses the flue gas from copper smelting to produce acid, with an average conversion rate of 99.75%, though this rate is not stable. **Online monitoring is in place, and fines are imposed on a daily basis if the limits are exceeded; these fines are quite substantial. As a result, the exhaust extraction system remains operational at all times, as we cannot afford to be careless.