Technology of synchronous desulfurization and denitration through flue gas ammonia method based on electrolytic regeneration iron removal

Abstract

The invention discloses a technology of synchronous desulfurization and denitration through a flue gas ammonia method based on electrolytic regeneration iron removal. The problem that for an existing desulfurization and denitration technology, the regeneration efficiency of an absorption solution is not high is solved. According to the technical scheme, the technology comprises the steps that pressurizing is conducted on flue gas, the flue gas is sent to a concentration tower to be reacted with a concentrated solution in the tower in a contacting mode, the flue gas coming out of the concentration tower is sent to an absorption tower to be reacted with the circulation absorption solution in the tower in a contacting mode, the concentrated solution reacted at the tower bottom part of the concentration tower is sent into an ammonium sulfate crystal system after iron is removed through a first electrolytic reactor, the absorption solution reacted at the tower bottom part of the absorption tower is sent back to the upper portion of the absorption tower to serve as the circulation absorption solution through regeneration, and the concentration solution enters an anode chamber in a reaction unit of the first electrolytic reactor to conduct an oxidation reaction and then enters a cathode chamber to conduct a reduction reaction; a reacted electrolyte is discharged from an outlet connection short pipe and sent into the ammonium sulfate crystal system. The technology of synchronous desulfurization and denitration through the flue gas ammonia method based on electrolytic regeneration iron removal has the advantages of being simple in method, low in investment cost and operating cost, high in conversion efficiency, good in iron removing effect and good in desulfurization and denitration effect.

Description

technical field [0001] The invention relates to a flue gas desulfurization and denitrification process in the field of energy saving and environmental protection, in particular to a flue gas ammonia synchronous desulfurization and denitrification process based on electrolytic regeneration to remove iron. Background technique [0002] Wet flue gas synchronous desulfurization and denitrification technology, especially wet ammonia-complexation synchronous desulfurization and denitrification technology, has been highly valued by the industry due to its advantages of high desulfurization efficiency, low investment, low water consumption, effective use of by-products, and no secondary pollution. Fe(II)EDTA has a good complexing effect on NO and high denitrification efficiency. For example, the patent application with the publication number 104226095A and the title of the invention is "Synchronous denitrification process based on flue gas wet ammonia desulfurization", which can real...

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Problems solved by technology

[0003] In the iron removal step, alkali needs to be added to adjust the pH value, so that a large amount of alkali metal ions are brought into the concentrated solution into the absorption solution, which increases the production cost and is not conducive to the subsequent crystallization of ammonium sulfate, affecting the quality of desulfurization products

[0004] There are following problems in adopting the iron filings method in the regeneration step: (1) because the absorption liquid is acidic, the iron filings are easily corroded, resulting in a large consumption of iron filings, and the concentration of iron ions in the absorption liquid is too high, which not only increases the cost of iron removal, but also Affect the quality of desulfurization and denitrification by-products; (2) Since the elemental iron in the iron filings is oxidized and corroded into the solution, the pH value of the absorption solution increases, resulting in the weakening of the regenerative reduction ability of the iron filings to the complexing agent

In order to ensure the denitrification efficiency, acid needs to be added to the system, resulting in a further increase in denitrification costs

(3) The consumption of iron filings is relatively large, and a large amount of elemental iron is oxidized into the absorption liquid. Since the pH value of the absorption liquid is controlled above 5.0, the absorption liquid contains a large amount of ferric hydroxide colloid (suspended matter), which will lead to circulation The wear of the impeller of the pump is increased, and it will also cause the nozzle and pipeline to block

(4) Since iron filings are filled in the closed regeneration tower, and the consumption of iron filings is continuous, continuous replenishment of iron filings cannot be realized

[0010] (1) For the reaction system with good electrochemical reversibility between the reactant and the product, the existing electrolysis device will cause repeated conversion between the reactant and the product in the electrolysis reactor, which not only affects the conversion efficiency, but also waste of electricity;

[0011] (2) The existing electrolysis device cannot effectively use the flow of the electrolyte itself to provide a large turbulent force for rapid renewal of the reactants on the electrode surface, and the electrochemical reaction speed is relatively slow, thereby reducing the reaction conversion rate;

[0012] (3) For complex reaction systems containing side reactions, existing electrolysis devices cannot effectively remove electrochemical reaction products that cause side reactions in a timely manner;

[0013] (4) The existing electrolysis device has a complex structure and a large footprint

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