Questions about wet flue gas desulfurization

The absorbed waste alkali solution is generally sold to alkali manufacturers at a low price of 8–10 yuan per ton. The sulfur dioxide produced after combustion can only be released into the atmosphere.

　　The wet oxidation deodorization process for alkaline slag can effectively address the problem of sulfide contamination, and it is a relatively advanced treatment method for alkaline slag at present. 　　The wet oxidation deodorization process uses air to oxidize sodium sulfide, organic substances, and inorganic substances in alkaline slag under certain temperature and pressure conditions. The reaction processes are as follows:
2S2- + 2H2O → S2O3²- + 2H⁺ – 472.8 kJ/mol (Na2S)
S2O3²- + 2H2O → S2O5²- + 4H⁺ – 475.7 kJ/mol (Na2S)
The oxidation reactions are exothermic; therefore, superheated steam is required to supply heat at the start of operation. Bring the reactor to the necessary initial reaction temperature. 　　If incineration is used, a dedicated incinerator is required, and the waste gases generated can be absorbed using dry, semi-dry, or wet methods. 　　

Sodium hydroxide is used to produce a saturated solution of sodium sulfite — crystallization — centrifugal drying — and the product is obtained.

The alkaline solution can be sent for ammonia distillation; sulfur dioxide is recommended to react with hydrogen sulfide to produce sulfur

Since wet flue gas desulfurization is chosen, consideration must be given to the treatment of the rich liquid resulting from desulfurization. Discharging it is not possible, as environmental regulations prohibit it; moreover, it would constitute a waste and increase costs. Getting food delivered is also quite troublesome. Incineration causes equipment corrosion, and the gases produced as a result are also released into the atmosphere; environmental protection principles do not permit this either. It is better to recycle the liquid and reuse it in a closed loop. This solves a series of problems. The operation is also relatively simple.

Maturation is carried out using magnesium hydroxide. Magnesium sulfate obtained can be sold externally

It depends on which gases containing sulfur are to be removed. For the synthesis of ammonia, ammonia water is generally used; after absorbing hydrogen sulfide, air is introduced to blow it out, and the solution can be regenerated for reuse. In the case of ADA, a dilute alkaline solution absorbs hydrogen sulfides, which then react with sodium aluminate to produce elemental sulfur. The oxidized form of ADA can be reduced back to its original form; the process is rather complicated, but ADA can be reused. The waste gas from power plants is desulfurized using sodium hydroxide solution. The purification of petroleum pyrolysis gas, including desulfurization, can be carried out using alkaline water (sodium hydroxide); in some cases, ethanolamine is used to remove acidic gases (the ethanolamine method). Under this method, the solution that has completed the absorption process is taken out of the absorption tower, and a small amount of pyrolysis gasoline is added to dissolve the heavy hydrocarbons and polymers present in the rich liquid. After that, the mixture is sent to a separator for separation, and the resulting wash oil is then sent to a stripping tower where the acidic gases are released after being cooled and condensed. The solution can also be recycled. There is also the desulfurization of ethylene, which is similar to the desulfurization of syngas. It depends on whether the desulfurization method is physical or chemical. It’s nothing more than the recycling of desulfurization liquid and the recovery of sulfur. Depending on the different sites and processes, the methods for treatment and recycling vary.

His question seems to be about what to do with the solution that can no longer be reused. For example, after wet flue gas desulfurization solutions have been used for several years, the accumulation of double salts (due to stricter environmental regulations) reaches a certain level – above 300 g/l – at which point both corrosion and the efficiency of desulfurization are affected. In such cases, this solution needs to be discarded or partially replaced. It appears that this is the main issue he was asking about. However, this type of solution can be discharged into industrial wastewater treatment plants for use in pH adjustment during wastewater treatment; however, such plants often refuse to accept it. Dongshi Company affiliated with Northeast Normal University has conducted research on this topic, and it is said that industrial application of this solution has already been achieved. If the original poster is interested, he can get in touch to find out more!

I have a question: In delayed coking, hydrogen sulfide is absorbed using sodium hydroxide in a two-stage process. What is the efficiency of this absorption? How is the sodium carbonate produced by the carbon dioxide contained in it dealt with? It would be best to provide an overall process flow diagram! ! Ha~

Dongshi’s method is good, but I haven’t seen any industrialization of it. Does anyone upstairs know? Where is it?