Investigation into the reasons for high outlet temperature of WSA waste boilers
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The waste pot behind the WSA incinerator needs to be stopped frequently for cleaning. An increase in outlet temperature occurs one month after clearing. On the surface, it is due to a decline in the heat exchange efficiency of the waste boiler. I would like to ask everyone about other causes of reduced heat exchange efficiency in this waste heat boiler, apart from scaling on the water side, as well as the solutions for these issues.
I’m not sure whether your facility recycles waste acid or produces acid from ordinary acidic gases. For WSA units, a high exhaust temperature of the boiler essentially rules out scaling on the water side; scaling is usually caused by scaling inside the tubes. Especially in waste acid regeneration units, scaling or even blockage of the waste heat exchangers occurs frequently, which ultimately leads to poor heat exchange and an increase in the temperature at the outlet of these exchangers.
We use about 15% H2S gas to produce acid through combustion
The waste acid regeneration unit has experienced blockages in the tube side, as the waste acid is quite dirty； But as the original poster said, acid is produced from acidic gases; where do these acidic gases come from, and could they bring impurities with them? In general, acidic gases in refineries originate from solvent regeneration and acidic water stripping units ； On the one hand, the H2S concentration in the solvent regeneration unit cannot be that low ； On the other hand, if it comes from an acidic water stripping unit, the acidic gas will inevitably contain NH3. The temperature in the WSA process furnace is generally maintained around 1000°C, and at this temperature ammonia does not burn completely, resulting in the formation of ammonium salts that can clog the tubes inside the furnace. In my opinion, it is necessary for the person asking the question to clarify the source of the acidic gas in order to make an accurate assessment.
Our acidic gases come from the gases released during the regeneration of syngas purification, and contain trace amounts of ammonia (a few hundred ppm)
Based on the acidic gas from rental units provided by the poster, the raw material is likely to come from coal chemical industries; the acidic gas produced in such industries is often complex and relatively dirty, which may be the reason why the waste boilers get clogged frequently.