Exploration of the crystalization issues in anhydrous sulfuric acid
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This post was last edited by zhaolijun on 2015-6-17 at 18:55. Dear colleagues, in our company’s ammonia-based desulfurization system (evaporation and crystallization in towers), since the introduction of a sulfur recovery unit to treat flue gas, the H2SO4·AN solution has become light yellow; previously, it was a colorless liquid. Moreover, during evaporation crystallization, the crystals formed are flaky in shape and white in color; they are difficult to separate using a centrifuge, often resulting in a diluted product. Our company’s relevant personnel believe that it is hydrogen sulfide gas present in the exhaust gases from the sulfur recovery incinerator; upon entering the desulfurization tower, this gas reacts with ammonia water to form ammonium sulfide. When ammonium sulfide coexists with ammonium sulfide solutions, ammonium sulfide alters the shape of sulfuric acid an crystals, making separation by centrifugation difficult. I urgently need help from all fellow sailors: is the analysis done by my company accurate? If it is, what methods can be used to remove it? I’m asking everyone.
It may be due to the reaction of SO2 and H2S to form elemental sulfur
Elemental sulfur must not be present in the ammonia-based desulfurization solution, as it will form thioesters that prevent crystallization. Hydrogen sulfide was oxidized to elemental sulfur
Now, we send the sulfur recovery exhaust gas to a circulating fluidized bed boiler for secondary combustion, where H2S and S in this exhaust gas are burned again to produce SO2. As a result, the issue of sulfate crystals is resolved, and the operation performance is good.
OP, which desulfurization technology do you guys use? How is the overall performance?
What material are the heat exchange equipment such as coolers and heaters used for the evaporation and crystallization of sulfuric acid in your company? The design provided by the other party for our side uses titanium in all parts, which results in high costs; we’re looking to see if it’s possible to use a less expensive material
We adopt the external crystallization process of Jiangsu and Yichang. The evaporation heater is made of titanium, as other lower-grade materials cannot withstand corrosion.