Method for realizing integrated desulfurization and denitrification and product recovery based on magnesium-ammonium method

Abstract

The invention relates to a method for realizing integrated desulfurization and denitrification and product recovery based on the magnesium-ammonium method in the technical field of environment. The method comprises the following steps: firstly adding an oxidant into smoke gas, using magnesium oxide serous fluid containing urea for simultaneously integrated desulfurization and denitrification, andtransforming sulfur dioxide in the smoke gas to magnesium sulfite and magnesium sulfate; and transforming nitrogen oxide to nitrate or nitrogen; and reacting desulfurization waste liquid with ammoniabicarbonate solution after full aeration and oxidation to obtain mixed solution of basic magnesium carbonate precipitate, ammonium sulfate and ammonium nitrate after centrifugation, wherein the basicmagnesium carbonate is used for circulating desulfurization or can be used as an industrial grade product after drying; ammonium sulfate solids containing a small quantity of ammonium nitrate can be obtained after concentrating and crystallizing the centrifuged solution, and the ammonium sulfate solids can be used as fertilizer; and dilute mother liquor is used for preparing magnesium oxide desulfurization serous fluid and can be recycled. By adopting the method, the ammonium sulfate solid fertilizer containing the small quantity of the ammonium nitrate and the industrial grade basic magnesium carbonate can be simultaneously obtained under the premise of ensuring the integrated desulfurization and denitrification efficiency of the smoke gas.

Description

technical field [0001] The invention relates to a method in the field of environmental technology, in particular to a method for realizing comprehensive desulfurization and denitrification and product recovery based on magnesium-ammonium method. Background technique [0002] Magnesium desulfurization technology is a promising wet desulfurization technology, which has the advantages of high desulfurization efficiency, not easy to scale, compact equipment, and low corrosion of desulfurization liquid to equipment. Therefore, this method has received extensive attention in recent years. However, the existing problems of this method are mainly that the high-temperature regeneration method of the desulfurizer is relatively complicated and the regeneration process consumes a lot of energy. If the by-product is recovered as magnesium sulfate, there is a problem of the sale of the by-product, and the desulfurization process needs to be continuously replenished with new magnesium-bas...

AI Technical Summary

Problems solved by technology

However, judging from the current operation of related projects at home and abroad, the usual problems of ammonia desulfurization technology are: the ammonia in the desulfurization solution is easy to volatilize into the flue gas, resulting in the escape loss of ammonia, and the ammonia gas that escapes into the flue gas It is also easy to interact with the residual sulfur dioxide in the flue gas to form ammonium salt aerosol particles that are difficult to capture in the flue gas, resulting in scarring of downstream pipelines and new secondary pollution

These problems greatly limit the practical promotion of direct ammonia desulfurization technology

[0003] In addition, the technical demand for flue gas denitrification of coal-fired boilers in my country is also increasing. The conventional SCR flue gas denitrification technology has high catalyst prices, limited life, and consumes a large amount of ammonia (or urea), resulting in high denitrification costs.

At present, the simultaneous desulfurization and denitrification technology using appropriate oxidation methods combined with wet desulfurization has received extensive attention, but the main problems at present are: 1) when the conventional wet desulfurization method is used for simultaneous denitrification, the nitrate products obtained are mixed into the desulfurization liquid In this process, the properties of the desulfurization liquid and the quality of the desulfurization product will be greatly affected. For example, the calcium nitrate salt mixed in the calcium desulfurization liquid is difficult to remove from the desulfurization liquid; sodium nitrate will interfere with the normal cycle regeneration of the sodium-calcium double alkali method 2) If a certain urea reducing agent or chlorine-containing oxidizing agent is added to the desulfurization solution, the ammonium salt and chloride ion obtained after the reaction will also affect the normal calcium or sodium desulfurization process and cause secondary pollution Emergence of problems (such as ammonia nitrogen and nitrate ion discharge in wastewater)

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