Flue gas desulfurization method for circulating zinc sulfite clear liquid

Abstract

The invention relates to a flue gas desulfurization method for circulating zinc sulfite clear liquid, and belongs to the technical field of flue gas desulfurization. Pure water and zinc sulfite are mixed to obtain the zinc sulfite clear liquid; adding the zinc sulfite clear liquid into a clear liquid tank, and enabling the zinc sulfite clear liquid to enter an absorption tower in a spraying manner; the method comprises the following steps: continuously introducing sulfur dioxide-containing flue gas into an absorption tower, reversely contacting the flue gas with a zinc sulfite clear liquid from bottom to top and carrying out an absorption reaction, discharging the desulfurized flue gas out of the absorption tower, and taking the zinc sulfite clear liquid after the absorption reaction as slurry. According to the method, the problems of low reaction activity, low desulfurization efficiency, large desulfurization agent consumption, large energy consumption and easy blockage of a desulfurization agent in the existing zinc oxide flue gas desulfurization technology are solved, the flue gas desulfurization can be circularly desulfurized by adopting the method, the continuity of desulfurization work is improved, and the working efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas desulfurization, and in particular relates to a flue gas desulfurization method with zinc sulfite clear liquid circulation. Background Art

[0002] Flue gas desulfurization technology is constantly developing. At present, the main flue gas desulfurization processes include sodium alkali method, limestone (lime)-gypsum method, circulating fluidized bed method, magnesium oxide method, zinc oxide method, ammonia method, activated coke adsorption method, organic amine adsorption and desorption method (ionic liquid method), etc. As an environmental protection facility, flue gas desulfurization does not generate direct economic benefits. Therefore, the selection of desulfurization process requires a comprehensive comparison of investment and operating costs on the premise of meeting emission standards. The main factors affecting the desulfurization cost include desulfurization agent cost, disposal of desulfurization products, power consumption and other factors. For zinc smelting enterprises, zinc roasted sand and zinc suboxide produced by the pyrometallurgical system can be used as desulfurization agents for zinc oxide desulfurization. The desulfurization products, zinc sulfite or zinc sulfate, can be returned to the zinc smelting system to recover zinc, and the investment in zinc oxide desulfurization is relatively moderate. Therefore, the zinc smelting system uses zinc oxide desulfurization, which has cost advantages over other processes;

[0003] The basic process of existing traditional zinc oxide desulfurization is to prepare solid zinc oxide powder into 10-20% zinc oxide slurry, send it into an absorption tower to contact with sulfur dioxide-containing flue gas for absorption reaction, and the single-stage desulfurization efficiency is about 90%. The desulfurization slurry discharged after absorption often contains multiple components such as zinc sulfite, zinc bisulfite, zinc sulfate, zinc oxide, etc. These waste materials need to be recycled for the second time, which increases the process steps. Summary of the invention

[0004] The object of the present invention is to provide a flue gas desulfurization method with zinc sulfite clear liquid circulation in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] The present invention provides a flue gas desulfurization method with zinc sulfite clear liquid circulation, comprising the following steps:

[0007] Step S1, mixing pure water and zinc sulfite to obtain a zinc sulfite clear solution;

[0008] Step S2, adding zinc sulfite clear solution into a clear solution tank, and allowing the zinc sulfite clear solution to enter an absorption tower by spraying;

[0009] Step S3, continuously introducing sulfur dioxide-containing flue gas into an absorption tower, the flue gas from bottom to top contacts with the zinc sulfite clear liquid from top to bottom in reverse direction and undergoes an absorption reaction, the desulfurized flue gas is discharged from the absorption tower, and the zinc sulfite clear liquid after the absorption reaction is a slurry;

[0010] Step S4, the slurry flows from the bottom of the absorption tower to the regeneration reaction tank from top to bottom;

[0011] Step S5, the slurry flows into the regeneration reaction tank, zinc oxide powder is added, the reaction pH is controlled to be no greater than 6.5, and after the reaction is completed, solid-liquid separation is performed to obtain a filtrate and a filter residue;

[0012] Step S6, discharging the filtrate into the clean liquid tank and mixing with pure water, and discharging the obtained circulating liquid and filter residue into the recovery system;

[0013] Step S7, the circulating liquid enters the absorption tower by spraying;

[0014] Step S8, continuously introducing sulfur dioxide-containing flue gas into the absorption tower, and the flue gas from bottom to top contacts the circulating liquid from top to bottom in reverse direction and undergoes absorption reaction;

[0015] Step S9, continuously discharging the desulfurized flue gas from the absorption tower.

[0016] As a further optimization scheme of the present invention, the solid content of zinc sulfite in the zinc sulfite clear solution and the circulating liquid is not more than 0.1%, the rest is pure water, the concentration of zinc sulfite is 0.009 mol / L, and the concentration of zinc bisulfite is 0.0468 mol / L.

[0017] As a further optimization scheme of the present invention, the circulating liquid volume is calculated according to the sulfur dioxide concentration in the flue gas, and the calculation formula is:

[0018] Q liquid = V × C SO2 × 9.82 × 10-7

[0019] Where: Q liquid - total liquid volume, unit m3 / h

[0020] V—Flue gas volume, unit Nm3 / h

[0021] C so2—Sulfur dioxide concentration, unit: mg / Nm3.

[0022] As a further optimization scheme of the present invention, in step S5, 3200 g of zinc oxide is added.

[0023] As a further optimization scheme of the present invention, in step S6, 1000 L of pure water is added.

[0024] As a further optimization scheme of the present invention, the method is used to treat flue gas with a sulfur dioxide concentration of 0-1000 mg / Nm3.

[0025] A flue gas desulfurization method with the above zinc sulfite clear liquid circulation is prepared by the above preparation method.

[0026] The beneficial effects of the present invention are: the flue gas desulfurization technology in the method has high reaction activity, high desulfurization efficiency, low desulfurizer consumption, low energy consumption, and is not easy to clog. In addition, the flue gas desulfurization method can achieve cyclic desulfurization, increase the continuity of the desulfurization work, and increase work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process flow chart of the cyclic desulfurization method of the present invention. DETAILED DESCRIPTION

[0028] The present application is described in further detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0029] Material

[0030] Unless otherwise specified, the methods used in the present invention are conventional methods known to those skilled in the art, and the reagents and other materials used are commercially available products unless otherwise specified.

[0031] method

[0032] Step S1, mixing pure water with zinc sulfite, wherein the solid content of the zinc sulfite is 0.1% and the rest is pure water, the concentration of zinc sulfite is 0.009 mol / L, and the concentration of zinc bisulfite is 0.0468 mol / L, to obtain a zinc sulfite clear solution;

[0033] Step S2, adding zinc sulfite clear solution into a clear solution tank, and allowing the zinc sulfite clear solution to enter an absorption tower by spraying;

[0034] Step S3, continuously introducing sulfur dioxide-containing flue gas into an absorption tower, the flue gas from bottom to top contacts with the zinc sulfite clear liquid from top to bottom in reverse direction and undergoes an absorption reaction, the desulfurized flue gas is discharged from the absorption tower, and the zinc sulfite clear liquid after the absorption reaction is a slurry;

[0035] Step S4, the slurry flows from the bottom of the absorption tower to the regeneration reaction tank from top to bottom;

[0036] Step S5, the slurry flows into the regeneration reaction tank and 3200g of zinc oxide powder is added, the reaction pH is controlled to be 6.5, and after the reaction is completed, solid-liquid separation is performed to obtain a filtrate and a filter residue;

[0037] Step S6, discharging the above filtrate into a clear liquid tank, adding 1000L of pure water for mixing, and obtaining a circulating liquid, wherein the solid content of zinc sulfite in the circulating liquid is 0.1%, the rest is pure water, the concentration of zinc sulfite is 0.009mol / L, the concentration of zinc bisulfite is 0.0468mol / L, and the filter residue is discharged to a recovery system;

[0038] Step S7, the circulating liquid enters the absorption tower by spraying;

[0039] Step S8, continuously introducing sulfur dioxide-containing flue gas into the absorption tower, and the flue gas from bottom to top contacts the circulating liquid from top to bottom in reverse direction and undergoes absorption reaction;

[0040] Step S9, continuously discharging the desulfurized flue gas from the absorption tower. This method is used to treat flue gas with a sulfur dioxide concentration of 990 mg / Nm3;

[0041] The circulating liquid volume is calculated based on the sulfur dioxide concentration in the flue gas, and the calculation formula is:

[0042] Q liquid = V × C SO2 × 9.82 × 10-7

[0043] Where: Q liquid - total liquid volume, unit m3 / h

[0044] V—Flue gas volume, unit Nm3 / h

[0045] C so2—sulfur dioxide concentration, unit: mg / Nm3;

[0046] The main reactions of this flue gas desulfurization method are as follows:

[0047] Reaction formula in step S1-step S3: ZnSO3+SO2+H2O→Zn(HSO3)2;

[0048] The reaction formula in step S4-step S9 is: Zn(HSO3)2+ZnO→2ZnSO3+H2O.

[0049] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A flue gas desulfurization method with zinc sulfite clear solution circulation, characterized in that: The following steps are involved: Step S1, mixing pure water and zinc sulfite to obtain a zinc sulfite clear solution; Step S2, adding zinc sulfite clear solution into a clear solution tank, and allowing the zinc sulfite clear solution to enter an absorption tower by spraying; Step S3, continuously introducing sulfur dioxide-containing flue gas into an absorption tower, the flue gas from bottom to top contacts with the zinc sulfite clear liquid from top to bottom in reverse direction and undergoes an absorption reaction, the desulfurized flue gas is discharged from the absorption tower, and the zinc sulfite clear liquid after the absorption reaction is a slurry; Step S4, the slurry flows from the bottom of the absorption tower to the regeneration reaction tank from top to bottom; Step S5, the slurry flows into the regeneration reaction tank, zinc oxide powder is added, the reaction pH is controlled to be no greater than 6.5, and after the reaction is completed, solid-liquid separation is performed to obtain a filtrate and a filter residue; Step S6, discharging the filtrate into the clean liquid tank and mixing with pure water, and discharging the obtained circulating liquid and filter residue into the recovery system; Step S7, the circulating liquid enters the absorption tower by spraying; Step S8, continuously introducing sulfur dioxide-containing flue gas into the absorption tower, and the flue gas from bottom to top contacts the circulating liquid from top to bottom in reverse direction and undergoes absorption reaction; Step S9, continuously discharging the desulfurized flue gas from the absorption tower.

2. The flue gas desulfurization method of zinc sulfite clear solution circulation according to claim 1, characterized in that: The solid content of zinc sulfite in the zinc sulfite clear liquid and the circulating liquid is not more than 0.1%, and the rest is pure water. The concentration of zinc sulfite is 0.009 mol / L, and the concentration of zinc hydrogen sulfite is 0.0468 mol / L.

3. The flue gas desulfurization method of zinc sulfite clear solution circulation according to claim 1, characterized in that: The circulating liquid volume is calculated based on the sulfur dioxide concentration in the flue gas, and the calculation formula is: Q liquid = V × C SO2 × 9.82 × 10-7 Where: Q liquid - total liquid volume, unit m3 / h V—Flue gas volume, unit Nm3 / h C so2—Sulfur dioxide concentration, unit: mg / Nm3.

4. The flue gas desulfurization method with zinc sulfite clear solution circulation according to claim 1, characterized in that: In the step S5, 3200 g of zinc oxide is added.

5. The flue gas desulfurization method with zinc sulfite clear solution circulation according to claim 1, characterized in that: In step S6, 1000 L of pure water is added.

6. The flue gas desulfurization method with zinc sulfite clear solution circulation according to claim 1, characterized in that: The method is used to treat flue gas with a sulfur dioxide concentration of 0-1000 mg / Nm3.

7. A flue gas desulfurization method with zinc sulfite clear solution circulation, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.

Images