Seek absorption methods for the emission of residual phosgene and hydrogen chloride gases in exhaust gases
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The phosgene and hydrogen chloride remaining in the exhaust gas are absorbed through a primary falling film absorber; hydrogen chloride is further absorbed via two stages of water washing. In the following two stages, the phosgene is broken down through water washing, and then it is destroyed using 10% liquid alkali in the third stage. An exhaust fan at the back draws the gas away for release into the atmosphere, yet the exhaust gas still contains large amounts of phosgene and hydrogen chloride. Online testing is about to start; I urgently need a solution!
Increase the number of falling film absorption stages; at least four such stages are required. Add three more alkali destruction towers before discharge, and install an additional ammonia spraying system as a contingency measure to ensure absolute reliability
If it is an existing facility, adding more absorption devices may not allow enough time for design, construction, or even determining the appropriate location on site. Adjustments can only be made operationally, by increasing the circulation rate and spraying volume. Try reducing the amount of gas slightly. Or lower the temperature.
It’s probably due to insufficient absorption capacity. The first method is to control at the source by reducing production. The second method is to increase the amount of the absorbing solution.
It’s understandable if phosgene doesn’t have an effective destructive effect and can’t be removed; hydrogen chloride should be easy to handle. Is the amount of alkali used for absorption designed to be too small?
With so many absorption processes involved, it’s still not possible to handle the waste effectively; it’s not a problem with your processing methods – it’s likely an issue with the equipment design. Handling exhaust gases isn’t something that can be accomplished just by having more absorption devices.
It’s not normal to still be unable to handle that many stages; have you tried replacing 7501 with activated carbon?