Reduction Of Byproduct Salt Formation In Wet Oxidation Desulfurization Process

Desulfurization technology has been developed since the 1980s.It has developed from dry,semi-dry and wet desulfurization to the emerging microbial desulfurization in recent years.The development of these technologies has improved the desulfurization process,higher desulfurization efficiency,simplified operating conditions and more environmental protection.However,there are still some unresolved problems,such as the generation of by-salt in the regeneration process.Taking PDS wet desulfurization as an example,the by-product salts generated are thiosulfate,sulfite,and sulfate,which are repeatedly used in the desulfurization solution.These by-product salts accumulate in the system,resulting in reduced desulfurization efficiency and operating conditions.deterioration.At present,the treatment methods for the salt-containing desulfurization liquid are mainly salt recovery and coal combustion in the furnace.However,these methods have their own disadvantages,such as increasing equipment costs,poor operating environment for workers,and low recovery rates.Reducing the generation of by-product salts from the source is the key to solving these problems.Na₂S₂O₃ is the main byproduct salt in the waste liquid of wet desulfurization.Reducing the amount of Na₂S₂O₃ produced is of great significance for green production.Firstly,the key factors affecting the production of Na₂S₂O₃ were screened out by Plackett-Burman test,i.e.pH value,sulfur concentration and temperature.On this basis,the response surface methodology is used to optimize the design of three factors and three levels with the production of Na₂S₂O₃ as the objective function.The results show that pH has the greatest influence on Na₂S₂O₃,followed by temperature and sulfur concentration.and the interaction between factors is small.The optimal operating conditions are pH 8.25,sulfur concentration 0.47 g/L,temperature 31.80?,PDS concentration 90 mg/L,oxygen-sulfur ratio 1.2 mmol/mmol,and Na₂S₂O₃production is 1.838 mmol/L.The oxidation-reduction potential can monitor the oxidation state in the regeneration tank,and controlling the oxidation-reduction potential value within a reasonable range can effectively prevent the occurrence of over-oxidation and under-oxidation.By studying the influence of different factors on the potential and response time of the S^2-selective electrode and the redox electrode,it is obtained that the performance of the sulfur electrode is better than the redox electrode in response time,accuracy,and the degree of influence of different factors on the electrode.The choice of sulfur electrode in the system will be more stable and more conducive to measurement.Sulfur ion meter is a kind of precision equipment,which is expensive,and the operating environment of industrial production is poor,the composition of the desulfurization liquid is complex,and it is easy to make the sulfur electrode scrapped at one time.The redox electrode has low cost,corrosion resistance and durability,and has been industrialized in many fields,so it is better for enterprises to balance these two aspects.Taking the existing wet oxidation desulfurization process of an enterprise as an example.Analyze the existing problems and make improvements from three aspects:pH value,elemental sulfur concentration and temperature.Control the temperature between 37.5?and 41.5?,and the pH value between 8.55–8.8.The gore filter is used instead of the molten sulfur kettle to improve the efficiency of elemental sulfur separation without increasing the temperature of the desulfurization solution.The elemental sulfur concentration can be reduced to between 0.07 g/L and 0.19 g/L.The increase in the concentration of Na₂S₂O₃ decreased from an increase of 1.88 g/L per day to 1.2 g/L per day,which greatly reduced the amount of by-product salts emissions and the emission cycle.