Several issues worth noting when changing the desulfurization absorbent from ammonia water to soda ash

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There are several issues worth noting when changing the desulfurization absorbent from ammonia water to soda ash.* * The increasing emphasis on environmental protection and the disadvantages caused by the use of ammonia as an absorbent in production and the adverse effects on subsequent processes. Therefore, many manufacturers that use ammonia as desulfurization absorbent have switched to soda ash. Most of them were successfully replaced once, and the desulfurization efficiency and comprehensive economic benefits have been improved, and the impact of some adverse factors has been resolved. But there are also a few manufacturers who have recurrences. This issue will be discussed as follows: ? 1. Chemical reaction formula for absorbing H2S with soda ash solution: ?Dehydrogenation sulfide: Na2CO3+H2S=NaHS+NaHCO3? Oxidation to release sulfur: NaHS+1/2O2=NaOH+S↓? Solution regeneration: NaHCO3+NaOH=Na2CO3+H2O? Side reaction: 2NaHS+2O2=Na2S2O3+H2O? 2Na2S2O3+O2=2Na2SO4+2S↓? Na2CO3+HCN=NaCN+NaHCO3? NaCN+Na2S2O3=NaCNS+Na2CO3 Na2CO3+CO2+H2O=2NaHCO3? 2. Several issues worth noting when using soda ash method for desulfurization? 1. Since NH4OH is slightly more alkaline, the reaction speed is fast, the sulfur evolution regeneration reaction proceeds simultaneously, and the solution viscosity is low, which is conducive to diffusion absorption, so the equipment is required to be more flexible. It is generally believed that using NH3 as the absorbent is easy to operate, and the absorption reaction of the gas leaving the desulfurization tower is still continuing, so the system outlet index qualification rate is high. Therefore, manufacturers with too little production capacity or unmatched equipment are not suitable for changing to the soda ash method. ? 2. The disadvantage of using ammonia water as the absorbent is that NH3 is easy to volatilize, causing a series of contradictions and is not good for environmental protection. The Na2CO3 solution has relatively stable components, low consumption, and strong anti-interference properties. If the working conditions are properly controlled and the 888 catalyst is used, no waste liquid will be discharged, it is non-toxic and does not pollute the environment, but the process operation management should be adjusted accordingly. ? 3. Na2CO3 and NH4OH solutions are both alkaline solutions. The chemical reaction principles are the same, but there are still differences in control indicators. Therefore, after Na2CO3 completely replaces NH4OH and runs for a period of time, it is necessary to re-formulate a process indicator and operation method that meets the production requirements of the device and is both scientific and operable based on the production load, H2S content and the characteristics of the soda ash method. ? 4. Conventional sulfur process requirements in semi-removal system using soda ash as absorbent and 888 catalyst: (for reference)?