A desulfurization wastewater treatment method and system

Abstract

The present invention provides a desulfurization wastewater treatment method and system, the method comprising: determining the water inlet mode of the desulfurization wastewater to be treated according to the type of the desulfurization wastewater to be treated; transporting the desulfurization wastewater to be treated to a first clarification device for treatment to obtain a first transition clear liquid, or transporting the desulfurization wastewater to be treated to a second clarification device for treatment to obtain a second transition clear liquid; transporting the first transition clear liquid to a first electrochemical reaction device for treatment to obtain a first reaction product, or transporting the second transition clear liquid to a second electrochemical reaction device for treatment to obtain a second reaction product; transporting the first reaction product to a first reuse treatment device for treatment to obtain a first target product, or transporting the second reaction product to a second reuse treatment device for treatment to obtain a second target product. The scheme of the present invention treats wastewater through electrochemical reaction to achieve target product reuse and zero discharge of desulfurization wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of desulfurization wastewater treatment, and in particular to a desulfurization wastewater treatment method and system. Background Art

[0002] At present, coal is still the main energy source in my country. The flue gas produced by coal combustion contains a large amount of pollutant SO2, which must be removed. Calcium desulfurization and magnesium desulfurization are the two most mature desulfurization processes. These two desulfurization processes are widely used because of their high efficiency, strong adaptability, and easy availability of desulfurizers. However, desulfurization wastewater will be generated during the desulfurization process. Desulfurization wastewater is difficult to treat because of its excessive heavy metal content, high salt content, and high suspended solids concentration.

[0003] The zero-discharge treatment of desulfurization wastewater from coal-fired power plants at home and abroad has formed a combined process consisting of three units: pretreatment, concentration and reduction treatment, and solidification treatment. The pretreatment unit removes heavy metals, COD, suspended solids and other components; the concentration and reduction treatment unit reduces the desulfurization wastewater to reduce the wastewater discharge at the back end; the solidification treatment unit is currently mature and applied, including evaporation crystallization and bypass flue evaporation, which is the last link in the desulfurization wastewater treatment; evaporation crystallization will consume electricity and steam in the plant, and the operating cost and construction cost of the system are relatively high. The evaporation crystallization evaporator will discharge a certain amount of circulating mother liquor during operation, and it cannot achieve 100% "zero emission". The final product is basically impurities, which are difficult to use effectively, and solid waste treatment has become a difficulty; bypass flue evaporation is to set up a bypass corrosion-resistant flue, extract part of the high-temperature flue gas before the air preheater, and spray the concentrated desulfurization wastewater concentrate into the bypass flue, atomize it into fine droplets through the nozzle, and exchange heat with the hot air flow at a certain flow rate to evaporate the water rapidly. The solid waste enters the subsequent system with the ash. Its essence is the transfer of impurities, that is, the impurities in the water are transferred to the ash, which affects the comprehensive utilization of fly ash;

[0004] In summary, the current desulfurization wastewater treatment methods mainly involve the transfer of harmful substances, which cannot achieve "zero emissions". At the same time, the products produced after treatment cannot be reused, resulting in energy waste. Summary of the invention

[0005] The present invention provides a desulfurization wastewater treatment method and system to solve the problem that the current desulfurization wastewater treatment method mainly involves the transfer of harmful substances and cannot achieve "zero emission". At the same time, the products produced after treatment cannot be reused, resulting in energy waste.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A desulfurization wastewater treatment method is applied to a desulfurization wastewater treatment system, wherein the desulfurization wastewater treatment system comprises an electrochemical reaction device, a clarification device and a recycling treatment device connected to the electrochemical reaction device, and the method comprises:

[0008] Determine the water inlet mode of the desulfurized wastewater to be treated according to the type of the desulfurized wastewater to be treated, wherein the type of the desulfurized wastewater to be treated includes: desulfurized wastewater generated by calcium desulfurization or desulfurized wastewater generated by magnesium desulfurization;

[0009] According to the water inlet method, the desulfurization wastewater to be treated is transported to the first clarification device for treatment to obtain the first transition clear liquid, or the desulfurization wastewater to be treated is transported to the second clarification device for treatment to obtain the second transition clear liquid;

[0010] According to the water inlet method, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product;

[0011] According to the water inlet method, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product.

[0012] Optionally, according to the type of desulfurization wastewater to be treated, the water inlet method of the desulfurization wastewater to be treated is determined, including:

[0013] When the desulfurization wastewater to be treated is desulfurization wastewater produced by calcium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the first water inlet mode;

[0014] When the desulfurization wastewater to be treated is desulfurization wastewater produced by magnesium desulfurization, the water inlet mode of the desulfurization wastewater to be treated is determined to be the second water inlet mode.

[0015] Optionally, in the case of the first water inlet mode, the desulfurization wastewater to be treated is transported to a first clarification device for treatment to obtain a first transition clear liquid, including:

[0016] The desulfurization wastewater to be treated generated by calcium desulfurization is transported to a gypsum dehydration system for dehydration to obtain first filtrate water;

[0017] The first filtrate water is transported to a three-tank treatment system for treatment to obtain a first transition clear liquid.

[0018] Optionally, in the case of the first water inlet mode, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, including:

[0019] The first transition clear liquid is transported to a first electrochemical reaction device, an anode reaction chamber of the first electrochemical reaction device produces a first gas reaction product, and a cathode reaction chamber of the first electrochemical reaction device produces a first liquid reaction product.

[0020] Optionally, in the case of the first water inlet mode, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, including:

[0021] The first gas reaction product is chlorine gas, and the first gas reaction product is transported to the first acid liquid tank, and the gas overflowing from the first acid liquid tank enters the first liquid alkali tank to obtain a sodium hypochlorite product;

[0022] The first intermediate liquid discharged from the first acid tank is transported to a neutralization water tank added with refined lime powder, and then transported to a sedimentation tank. The sediment in the sedimentation tank is a refined gypsum product, and the supernatant in the sedimentation tank is transported to a pulping system;

[0023] The first liquid reaction product is transported to a slurry making system and combined with the supernatant output from the sedimentation tank and lime powder to prepare a first desulfurizing agent slurry.

[0024] Optionally, in the case of the second water inlet mode, the desulfurization wastewater to be treated is transported to a second clarification device for treatment to obtain a second transition clear liquid, including:

[0025] The desulfurization wastewater to be treated generated by magnesium desulfurization is transported to a rapid clarification device for clarification to obtain a second transition clear liquid.

[0026] Optionally, in the case of the second water inlet mode, the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product, including:

[0027] The second transition clear liquid is transported to a second electrochemical reaction device, the anode reaction chamber of the second electrochemical reaction device produces a second gas reaction product, and the cathode reaction chamber of the second electrochemical reaction device produces a second liquid reaction product.

[0028] Optionally, in the case of the second water inlet mode, the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product, including:

[0029] The second gas reaction product is chlorine gas, and the second gas reaction product is transported to the second acid liquid tank, and the gas overflowed from the second acid washing tank enters the second liquid alkali tank to obtain a sodium hypochlorite product;

[0030] The second intermediate liquid discharged from the second acid liquid tank is transported to the desulfurization slurry pool;

[0031] The second liquid reaction product is transported to a desulfurization slurry pool, and combined with the second intermediate liquid and magnesium oxide discharged from the second acid liquid tank to prepare a second desulfurization agent slurry.

[0032] The present invention also provides a desulfurization wastewater treatment system, comprising an electrochemical reaction device, a clarification device and a recycling treatment device connected to the electrochemical reaction device;

[0033] The electrochemical reaction device comprises: a first electrochemical reaction device and a second electrochemical reaction device;

[0034] The clarification device comprises: a first clarification device and a second clarification device;

[0035] The reuse processing device comprises: a first reuse processing device and a second reuse processing device;

[0036] The liquid outlet of the first clarification device is connected to the liquid inlet of the first electrochemical reaction device, and the liquid outlet of the first electrochemical reaction device is connected to the liquid inlet of the first recycling treatment device;

[0037] The liquid outlet of the second clarification device is connected to the liquid inlet of the second electrochemical reaction device, and the liquid outlet of the first electrochemical reaction device is connected to the liquid inlet of the second recycling treatment device;

[0038] According to the water inlet method, the desulfurization wastewater to be treated is transported to the first clarification device for treatment to obtain the first transition clear liquid, or the desulfurization wastewater to be treated is transported to the second clarification device for treatment to obtain the second transition clear liquid;

[0039] According to the water inlet method, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product;

[0040] According to the water inlet mode, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product;

[0041] The water inlet mode of the desulfurization wastewater to be treated is determined according to the type of the desulfurization wastewater to be treated, and the type of the desulfurization wastewater to be treated includes: desulfurization wastewater generated by calcium desulfurization or desulfurization wastewater generated by magnesium desulfurization.

[0042] Optionally, the first clarification device comprises: a gypsum dehydration system and a triple-box treatment system, the water outlet of the gypsum dehydration system is connected to the water inlet of the triple-box treatment system, and the water outlet of the triple-box treatment system is connected to the water inlet of the first electrochemical reaction device through a clean water tank;

[0043] The first recycling treatment device comprises: a first acid liquid tank, a first liquid alkali tank, a neutralization water tank, a sedimentation tank and a pulping system, the liquid outlet of the cathode reaction chamber of the first electrochemical reaction device is connected to the pulping system, the liquid outlet of the anode reaction chamber of the first electrochemical reaction device is connected to the liquid inlet of the first acid liquid tank, the gas outlet of the first acid liquid tank is connected to the gas inlet of the first liquid alkali tank, the liquid outlet of the first acid liquid tank is connected to the liquid inlet of the neutralization water tank, the liquid outlet of the neutralization water tank is connected to the sedimentation tank, and the liquid outlet of the sedimentation tank is connected to the pulping system;

[0044] The second clarification device comprises a rapid clarification device, and a water outlet of the rapid clarification device is connected to a water inlet of the second electrochemical reaction device;

[0045] The second recycling treatment device includes: a second acid liquid tank, a second liquid alkali tank and a desulfurization slurry pool, the liquid outlet end of the cathode reaction chamber of the second electrochemical reaction device is connected to the desulfurization slurry pool, the liquid outlet end of the anode reaction chamber of the second electrochemical reaction device is connected to the liquid inlet end of the second acid liquid tank, the gas outlet end of the second acid liquid tank is connected to the gas inlet end of the second liquid alkali tank, and the liquid outlet end of the second acid liquid tank is connected to the desulfurization slurry pool.

[0046] The above solution of the present invention includes at least the following beneficial effects:

[0047] The above scheme of the present invention determines the water inlet mode of the desulfurized wastewater to be treated according to the type of the desulfurized wastewater to be treated, and the type of the desulfurized wastewater to be treated includes: one of the desulfurized wastewater produced by calcium desulfurization or the desulfurized wastewater produced by magnesium desulfurization; according to the water inlet mode, the desulfurized wastewater to be treated is transported to a first clarification device for treatment to obtain a first transition clear liquid, or the desulfurized wastewater to be treated is transported to a second clarification device for treatment to obtain a second transition clear liquid; according to the water inlet mode, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product; according to the water inlet mode The first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product; the desulfurization wastewater is treated by the principle of electrochemical reaction to separate alkali solution, acid solution and chlorine gas, the alkali solution is reused as a desulfurizer, the chlorine gas is absorbed by liquid alkali to generate sodium hypochlorite, which can be used for sterilization and algae removal, and the acid solution is neutralized and then reused, forming a zero-discharge process treatment route for desulfurization wastewater based on electrochemical reaction, and achieving zero discharge of desulfurization wastewater; to solve the problem that the current desulfurization wastewater treatment method is mainly the transfer of harmful substances, which cannot achieve "zero discharge", and the products produced after treatment cannot be reused, resulting in energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a flow chart of a desulfurization wastewater treatment method provided by an embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the treatment process of desulfurization wastewater generated by calcium desulfurization provided by an embodiment of the present invention;

[0050] Figure 3 It is a schematic diagram of the treatment process of desulfurization wastewater generated by magnesium-based desulfurization provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0052] like Figure 1As shown, an embodiment of the present invention provides a desulfurization wastewater treatment method, which is applied to a desulfurization wastewater treatment system. The desulfurization wastewater treatment system includes an electrochemical reaction device, a clarification device and a recycling treatment device connected to the electrochemical reaction device. The method includes:

[0053] Step 11, determining the water inlet mode of the desulfurization wastewater to be treated according to the type of the desulfurization wastewater to be treated, wherein the type of the desulfurization wastewater to be treated includes: desulfurization wastewater generated by calcium desulfurization or desulfurization wastewater generated by magnesium desulfurization;

[0054] Step 12, according to the water inlet mode, the desulfurization wastewater to be treated is transported to a first clarification device for treatment to obtain a first transition clear liquid, or the desulfurization wastewater to be treated is transported to a second clarification device for treatment to obtain a second transition clear liquid;

[0055] Step 13, according to the water inlet mode, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product;

[0056] Step 14, according to the water inlet method, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product.

[0057] In this embodiment, the water inlet mode of the desulfurized wastewater to be treated is determined according to the type of the desulfurized wastewater to be treated, and the type of the desulfurized wastewater to be treated includes: one of the desulfurized wastewater generated by calcium desulfurization or the desulfurized wastewater generated by magnesium desulfurization; according to the water inlet mode, the desulfurized wastewater to be treated is transported to a first clarification device for treatment to obtain a first transition clear liquid, or the desulfurized wastewater to be treated is transported to a second clarification device for treatment to obtain a second transition clear liquid; according to the water inlet mode, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product; according to the water inlet mode , the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product; the desulfurization wastewater is treated by the principle of electrochemical reaction to separate alkali solution, acid solution and chlorine gas, the alkali solution is reused as a desulfurizer, the chlorine gas is absorbed by liquid alkali to generate sodium hypochlorite, which can be used for sterilization and algae removal, and the acid solution is neutralized and then reused, forming a zero-emission process treatment route for desulfurization wastewater based on electrochemical reaction, and achieving zero emission of desulfurization wastewater; to solve the problem that the current desulfurization wastewater treatment method is mainly the transfer of harmful substances, which cannot achieve "zero emission", and the products produced after treatment cannot be reused, resulting in energy waste.

[0058] In an optional embodiment of the present invention, step 11 may include:

[0059] Step 111, when the desulfurization wastewater to be treated is desulfurization wastewater generated by calcium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the first water inlet mode;

[0060] Step 112, when the desulfurization wastewater to be treated is desulfurization wastewater generated by magnesium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the second water inlet mode.

[0061] In this embodiment, corresponding treatment processes are set up for the desulfurization wastewater generated by calcium desulfurization and the desulfurization wastewater generated by magnesium desulfurization. When the desulfurization wastewater generated by calcium desulfurization or the desulfurization wastewater generated by magnesium desulfurization is treated, after clarification, it is electrochemically treated by an electrochemical reaction device, and then treated by a recycling treatment device to obtain a target product. The obtained target product can be used for other production purposes. While achieving zero emissions after the desulfurization wastewater is treated, the resource utilization of the desulfurization wastewater can be realized, which is environmentally friendly.

[0062] In an optional embodiment of the present invention, in the case of the first water inlet mode, step 12 may include:

[0063] Step 1211, transporting the untreated desulfurization wastewater generated by calcium desulfurization to a gypsum dehydration system for dehydration to obtain first filtrate water;

[0064] In step 1212, the first filtrate water is transported to a three-tank treatment system for treatment to obtain a first transition clear liquid.

[0065] In this embodiment, the untreated desulfurization wastewater generated by calcium desulfurization enters the gypsum dehydration system for dehydration, and the dry material generated by the dehydration is stored in the gypsum warehouse for reuse. The first filtrate water generated by the gypsum dehydration system enters the triple-box treatment system. The fluoride and metal and heavy metal in the first filtrate water form precipitation after reaction. The clear liquid flowing out of the triple-box treatment system is the first transition clear liquid. The untreated desulfurization wastewater generated by calcium desulfurization is clarified by the gypsum dehydration system and the triple-box treatment system; wherein the gypsum dehydration system is a vacuum belt dehydration system.

[0066] In an optional embodiment of the present invention, in the case of the first water inlet mode, step 13 may include:

[0067] Step 1311 , transporting the first transition clear liquid to a first electrochemical reaction device, wherein the anode reaction chamber of the first electrochemical reaction device produces a first gas reaction product, and the cathode reaction chamber of the first electrochemical reaction device produces a first liquid reaction product.

[0068] In this embodiment, the first electrochemical reaction device is a built-in ultrasonic diaphragm electrolyzer. The first transition clear liquid flowing out of the triple box treatment system passes through the clean water tank and enters the first electrochemical reaction device, and electrochemical reactions are carried out in the cathode reaction chamber and the anode reaction chamber of the first electrochemical reaction device. Specifically, in the anode reaction chamber, the electrochemical reaction potential of chloride ions is the lowest, so it is the main electrochemical reaction, specifically: 2Cl - →Cl2↑+2e - , thereby generating the first gas reaction product: chlorine, of which a small part of the chlorine directly reacts with the water in the anode reaction chamber to generate hypochlorous acid: Cl2+H2O→HClO+HCl; at the same time, the anode chamber reacts to generate hypochlorous acid or sodium hypochlorite, and sulfur dioxide is absorbed by the lime slurry to generate sulfite. When sulfite meets hypochlorite, a redox reaction occurs: ClO - +SO3 2- →Cl - +SO4 2- ;

[0069] In the cathode reaction chamber, a hydrolysis electrochemical reaction occurs, releasing hydrogen and generating hydroxide. At the same time, under the action of the electric field force, the calcium ions and sodium ions in the anode reaction chamber migrate to the cathode reaction chamber through the cation exchange membrane. The hydroxide combines with the calcium ions to generate calcium hydroxide precipitation. The hydroxide meets the bicarbonate to generate carbonate. The carbonate meets the calcium ions to generate calcium carbonate precipitation, as follows:

[0070] 2H2O+2e→H2↑+2OH - ;

[0071] HCO3 - +OH - →CO3 2- +H2O;

[0072] Ca 2+ +CO3 2- →CaCO3↓;

[0073] Ca 2+ +2OH - →Ca(OH)2↓.

[0074] In an optional embodiment of the present invention, in the case of the first water inlet mode, step 14 may include:

[0075] Step 1411, the first gas reaction product is chlorine gas, and the first gas reaction product is transported to the first acid liquid tank, and the gas overflowing from the first acid liquid tank enters the first liquid alkali tank to obtain a sodium hypochlorite product;

[0076] Step 1412, the first intermediate liquid discharged from the first acid liquid tank is transported to a neutralization water tank added with refined lime powder, and then transported to a sedimentation tank, the sediment in the sedimentation tank is a refined gypsum product, and the supernatant in the sedimentation tank is transported to a pulping system;

[0077] Step 1413, the first liquid reaction product is transported to a slurry making system, and combined with the supernatant output from the sedimentation tank and lime powder to prepare a first desulfurizing agent slurry.

[0078] In this embodiment, chlorine, the first gas reactant, is precipitated from the cathode reaction chamber of the first electrochemical reaction device and enters the first acid liquid tank for treatment to remove impurities mixed with the chlorine. Under vacuum negative pressure, chlorine is precipitated from the first acid liquid tank and enters the first liquid alkali tank. Chlorine reacts with liquid alkali to generate sodium hypochlorite, which can be used for disinfection. The first intermediate liquid flowing out of the first liquid alkali tank enters the neutralization water tank, and refined lime powder is added to the inside of the neutralization water tank. The liquid inside the neutralization water tank enters the sedimentation tank for precipitation. The resulting precipitate is a refined gypsum product. This gypsum has a relatively high purity and can be used as a building material. The supernatant of the sedimentation tank is transported to the pulping system. The cathode reaction chamber of the first electrochemical reaction device produces a first liquid reaction product that enters the pulping system. Lime powder is added to the pulping system, and a first desulfurizer slurry is prepared by the pulping system. The first desulfurizer slurry can be used for calcium desulfurization.

[0079] In an optional embodiment of the present invention, in the case of the second water inlet mode, step 12 may include:

[0080] Step 1221, the untreated desulfurization wastewater generated by magnesium desulfurization is transported to a rapid clarification device for clarification to obtain a second transition clear liquid.

[0081] In this embodiment, the desulfurization wastewater to be treated generated by magnesium desulfurization is clarified by a rapid clarification device to eliminate impurities in the desulfurization wastewater to be treated, thereby obtaining a second transition clear liquid.

[0082] In an optional embodiment of the present invention, in the case of the second water inlet mode, step 13 may include:

[0083] Step 1321 , transporting the second transition clear liquid to a second electrochemical reaction device, wherein the anode reaction chamber of the second electrochemical reaction device produces a second gas reaction product, and the cathode reaction chamber of the second electrochemical reaction device produces a second liquid reaction product.

[0084] In this embodiment, the second electrochemical reaction device is a built-in ultrasonic diaphragm electrolytic cell, and the second transition clear liquid flowing out of the rapid clarification device enters the second electrochemical reaction device, and electrochemical reactions are carried out in the cathode reaction chamber and the anode reaction chamber of the second electrochemical reaction device; specifically, in the anode reaction chamber, the electrochemical reaction potential of chloride ions is the lowest, so it is the main electrochemical reaction, specifically: 2Cl - →Cl2↑+2e - , thereby generating the second gas reaction product: chlorine, of which a small part of the chlorine directly reacts with the water in the anode reaction chamber to generate hypochlorous acid: Cl2+H2O→HClO+HCl; at the same time, the anode chamber reacts to generate hypochlorous acid or sodium hypochlorite, and sulfur dioxide is absorbed by the lime slurry to generate sulfite. When sulfite meets hypochlorite, a redox reaction occurs: ClO - +SO32- →Cl - +SO4 2- ;

[0085] In the cathode reaction chamber, a hydrolysis electrochemical reaction occurs, releasing hydrogen and generating hydroxide. At the same time, under the action of the electric field force, the magnesium ions and sodium ions in the anode reaction chamber migrate to the cathode reaction chamber through the cation exchange membrane, and the hydroxide combines with the magnesium ions to generate magnesium hydroxide precipitation, as follows:

[0086] 2H2O+2e→H2↑+2OH - ;

[0087] HCO3 - +OH - →CO3 2- +H2O;

[0088] Mg 2+ +2OH - →Mg(OH)2↓.

[0089] In an optional embodiment of the present invention, in the case of the second water inlet mode, step 14 may include:

[0090] Step 1421, the second gas reaction product is chlorine gas, and the second gas reaction product is transported to the second acid liquid tank, and the gas overflowed from the second acid washing tank enters the second liquid alkali tank to obtain a sodium hypochlorite product;

[0091] Step 1422, the second intermediate liquid discharged from the second acid liquid tank is transported to the desulfurization slurry tank;

[0092] Step 1423, transporting the second liquid reaction product to the desulfurization slurry pool, and preparing a second desulfurization agent slurry by combining the second intermediate liquid and magnesium oxide discharged from the second acid liquid tank.

[0093] In this embodiment, the second gas reactant chlorine is precipitated from the cathode reaction chamber of the second electrochemical reaction device and enters the second acid liquid tank for treatment to remove impurities mixed with the chlorine. Under vacuum negative pressure, the chlorine is precipitated from the second acid liquid tank and enters the second liquid alkali tank. The chlorine reacts with the liquid alkali to generate sodium hypochlorite, which can be used for disinfection; the second intermediate liquid flowing out of the second liquid alkali tank enters the desulfurization slurry pool, and the cathode reaction chamber of the second electrochemical reaction device produces a second liquid reaction product that enters the desulfurization slurry pool. Magnesium oxide is added to the desulfurization slurry pool, and a second desulfurizer slurry is prepared through the desulfurization slurry pool. The second desulfurizer slurry can be used for magnesium desulfurization.

[0094] like Figure 2As shown, when treating the desulfurization wastewater generated by calcium desulfurization, the desulfurization wastewater to be treated is transported to the gypsum dehydration system for dehydration; the filtrate water of the gypsum dehydration system enters the triple box treatment system for treatment; the filtered water produced by the triple box treatment system enters the first electrochemical reaction device through the clean water tank; the effluent from the cathode reaction chamber of the first electrochemical reaction device is alkaline, and the pH value can be adjusted between 9 and 12 according to the working conditions. The effluent from the cathode reaction chamber enters the pulping system for preparing the desulfurizer slurry; the effluent from the anode reaction chamber is acidic, accompanied by chlorine precipitation, and is absorbed by liquid alkali through vacuum negative pressure to generate sodium hypochlorite, which can be used for disinfection; the acid generated in the anode reaction chamber is neutralized with lime to generate calcium sulfate, i.e., gypsum precipitation. The purity of this gypsum is relatively high and can be used as a building material or a cement additive; the neutralized water is precipitated and the supernatant enters the pulping system for preparing the desulfurizer slurry.

[0095] By treating the desulfurization wastewater generated by calcium desulfurization through the above-mentioned clarification + electrochemical reaction treatment combination method, zero discharge of desulfurization wastewater can be achieved, and resource utilization of desulfurization wastewater can be realized, which is environmentally friendly;

[0096] The main problems of calcium desulfurization include: chloride ion concentration control, which is generally controlled below 10,000 mg / L; sodium sulfate poisoning. When the sodium sulfate concentration reaches a certain condition, it will affect the desulfurization efficiency and even cause the desulfurizer to fail. The zero-discharge treatment method for calcium desulfurization wastewater based on the principle of electrochemical reaction can effectively solve the above problems of calcium desulfurization and optimize desulfurization. The zero-discharge treatment method for desulfurization wastewater based on the principle of electrochemical reaction optimizes the performance parameters of the desulfurization circulating slurry, such as pH value, liquid / gas ratio, calcium / sulfur ratio, oxidation air volume, slurry concentration, flue gas flow rate, etc., to ensure the continuous, stable and economical operation of the flue gas desulfurization system.

[0097] like Figure 3 As shown, when treating the desulfurization wastewater generated by magnesium desulfurization, the desulfurization wastewater to be treated passes through a rapid clarification device, and the filtered water enters the second electrochemical reaction device. The effluent from the cathode reaction chamber of the second electrochemical reaction device is alkaline. According to the working conditions, the pH value can be adjusted between 9-12. The effluent from the cathode reaction chamber enters the desulfurization slurry pool for preparing desulfurization slurry; the effluent from the anode reaction chamber of the second electrochemical reaction device is acidic, accompanied by chlorine precipitation; the chlorine is absorbed by liquid alkali to generate sodium hypochlorite, which can be used for disinfection. The acid generated in the anode reaction chamber and the alkali generated in the cathode reaction chamber are mixed to prepare the desulfurizer slurry for magnesium desulfurization.

[0098] By treating the desulfurization wastewater generated by magnesium desulfurization through the above-mentioned clarification + electrochemical reaction treatment combination method, zero discharge of desulfurization wastewater can be achieved, and resource utilization of desulfurization wastewater can be realized, which is environmentally friendly;

[0099] For magnesium desulfurization, the main problems are basically the same as those of calcium desulfurization, but when the magnesium sulfate concentration reaches a certain condition, it is treated with impurities and then crystallized into MgSO4·7H2O through a concentration device; compared with calcium desulfurization, the main problem is the control of chloride ion concentration; and the zero-discharge treatment method for desulfurization wastewater based on the principle of electrochemical reaction can effectively solve these problems. The zero-discharge treatment method for desulfurization wastewater based on the principle of electrochemical reaction optimizes the performance parameters of the desulfurization circulating slurry, such as pH value, liquid / gas ratio, magnesium / sulfur ratio, oxidation air volume, slurry concentration, flue gas flow rate, etc., to ensure the continuous, stable and economical operation of the flue gas desulfurization system.

[0100] When treating desulfurization wastewater generated by calcium desulfurization or magnesium desulfurization, according to specific working conditions, concentration treatment can be added after the desulfurization wastewater to be treated is clarified and before the electrochemical reaction. After the desulfurization wastewater is clarified, flocculated and concentrated, an electrochemical reaction is carried out through an electrochemical reaction device, and then it is treated through a recycling treatment device to achieve zero discharge of plug flow wastewater and resource utilization of desulfurization wastewater.

[0101] The present invention also provides a desulfurization wastewater treatment system, comprising an electrochemical reaction device, a clarification device and a recycling treatment device connected to the electrochemical reaction device;

[0102] The electrochemical reaction device comprises: a first electrochemical reaction device and a second electrochemical reaction device;

[0103] The clarification device comprises: a first clarification device and a second clarification device;

[0104] The reuse processing device comprises: a first reuse processing device and a second reuse processing device;

[0105] The liquid outlet of the first clarification device is connected to the liquid inlet of the first electrochemical reaction device, and the liquid outlet of the first electrochemical reaction device is connected to the liquid inlet of the first recycling treatment device;

[0106] The liquid outlet of the second clarification device is connected to the liquid inlet of the second electrochemical reaction device, and the liquid outlet of the first electrochemical reaction device is connected to the liquid inlet of the second recycling treatment device;

[0107] According to the water inlet method, the desulfurization wastewater to be treated is transported to the first clarification device for treatment to obtain the first transition clear liquid, or the desulfurization wastewater to be treated is transported to the second clarification device for treatment to obtain the second transition clear liquid;

[0108] According to the water inlet method, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product;

[0109] According to the water inlet mode, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product;

[0110] The water inlet mode of the desulfurization wastewater to be treated is determined according to the type of the desulfurization wastewater to be treated, and the type of the desulfurization wastewater to be treated includes: desulfurization wastewater generated by calcium desulfurization or desulfurization wastewater generated by magnesium desulfurization.

[0111] Optionally, the first clarification device comprises: a gypsum dehydration system and a triple-box treatment system, the water outlet of the gypsum dehydration system is connected to the water inlet of the triple-box treatment system, and the water outlet of the triple-box treatment system is connected to the water inlet of the first electrochemical reaction device through a clean water tank;

[0112] The first recycling treatment device comprises: a first acid liquid tank, a first liquid alkali tank, a neutralization water tank, a sedimentation tank and a pulping system, the liquid outlet of the cathode reaction chamber of the first electrochemical reaction device is connected to the pulping system, the liquid outlet of the anode reaction chamber of the first electrochemical reaction device is connected to the liquid inlet of the first acid liquid tank, the gas outlet of the first acid liquid tank is connected to the gas inlet of the first liquid alkali tank, the liquid outlet of the first acid liquid tank is connected to the liquid inlet of the neutralization water tank, the liquid outlet of the neutralization water tank is connected to the sedimentation tank, and the liquid outlet of the sedimentation tank is connected to the pulping system;

[0113] The second clarification device comprises a rapid clarification device, and a water outlet of the rapid clarification device is connected to a water inlet of the second electrochemical reaction device;

[0114] The second recycling treatment device includes: a second acid liquid tank, a second liquid alkali tank and a desulfurization slurry pool, the liquid outlet end of the cathode reaction chamber of the second electrochemical reaction device is connected to the desulfurization slurry pool, the liquid outlet end of the anode reaction chamber of the second electrochemical reaction device is connected to the liquid inlet end of the second acid liquid tank, the gas outlet end of the second acid liquid tank is connected to the gas inlet end of the second liquid alkali tank, and the liquid outlet end of the second acid liquid tank is connected to the desulfurization slurry pool.

[0115] Optionally, according to the type of desulfurization wastewater to be treated, the water inlet method of the desulfurization wastewater to be treated is determined, including:

[0116] When the desulfurization wastewater to be treated is desulfurization wastewater produced by calcium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the first water inlet mode;

[0117] When the desulfurization wastewater to be treated is desulfurization wastewater produced by magnesium desulfurization, the water inlet mode of the desulfurization wastewater to be treated is determined to be the second water inlet mode.

[0118] Optionally, in the case of the first water inlet mode, the desulfurization wastewater to be treated is transported to a first clarification device for treatment to obtain a first transition clear liquid, including:

[0119] The desulfurization wastewater to be treated generated by calcium desulfurization is transported to a gypsum dehydration system for dehydration to obtain first filtrate water;

[0120] The first filtrate water is transported to a three-tank treatment system for treatment to obtain a first transition clear liquid.

[0121] Optionally, in the case of the first water inlet mode, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, including:

[0122] The first transition clear liquid is transported to a first electrochemical reaction device, an anode reaction chamber of the first electrochemical reaction device produces a first gas reaction product, and a cathode reaction chamber of the first electrochemical reaction device produces a first liquid reaction product.

[0123] Optionally, in the case of the first water inlet mode, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, including:

[0124] The first gas reaction product is chlorine gas, and the first gas reaction product is transported to the first acid liquid tank, and the gas overflowing from the first acid liquid tank enters the first liquid alkali tank to obtain a sodium hypochlorite product;

[0125] The first intermediate liquid discharged from the first acid tank is transported to a neutralization water tank added with refined lime powder, and then transported to a sedimentation tank. The sediment in the sedimentation tank is a refined gypsum product, and the supernatant in the sedimentation tank is transported to a pulping system;

[0126] The first liquid reaction product is transported to a slurry making system and combined with the supernatant output from the sedimentation tank and lime powder to prepare a first desulfurizing agent slurry.

[0127] Optionally, in the case of the second water inlet mode, the desulfurization wastewater to be treated is transported to a second clarification device for treatment to obtain a second transition clear liquid, including:

[0128] The desulfurization wastewater to be treated generated by magnesium desulfurization is transported to a rapid clarification device for clarification to obtain a second transition clear liquid.

[0129] Optionally, in the case of the second water inlet mode, the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product, including:

[0130] The second transition clear liquid is transported to a second electrochemical reaction device, the anode reaction chamber of the second electrochemical reaction device produces a second gas reaction product, and the cathode reaction chamber of the second electrochemical reaction device produces a second liquid reaction product.

[0131] Optionally, in the case of the second water inlet mode, the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product, including:

[0132] The second gas reaction product is chlorine gas, and the second gas reaction product is transported to the second acid liquid tank, and the gas overflowed from the second acid washing tank enters the second liquid alkali tank to obtain a sodium hypochlorite product;

[0133] The second intermediate liquid discharged from the second acid liquid tank is transported to the desulfurization slurry pool;

[0134] The second liquid reaction product is transported to a desulfurization slurry pool, and combined with the second intermediate liquid and magnesium oxide discharged from the second acid liquid tank to prepare a second desulfurization agent slurry.

[0135] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for treating desulfurization wastewater, characterized in that: Applied to a desulfurization wastewater treatment system, the desulfurization wastewater treatment system includes an electrochemical reaction device, a clarification device and a recycling treatment device connected to the electrochemical reaction device, and the method includes: Determine the water inlet mode of the desulfurized wastewater to be treated according to the type of the desulfurized wastewater to be treated, wherein the type of the desulfurized wastewater to be treated includes: desulfurized wastewater generated by calcium desulfurization or desulfurized wastewater generated by magnesium desulfurization; According to the water inlet method, the desulfurization wastewater to be treated is transported to the first clarification device for treatment to obtain the first transition clear liquid, or the desulfurization wastewater to be treated is transported to the second clarification device for treatment to obtain the second transition clear liquid; According to the water inlet method, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product; According to the water inlet mode, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product; Among them, according to the type of desulfurization wastewater to be treated, the water inlet method of the desulfurization wastewater to be treated is determined, including: When the desulfurization wastewater to be treated is desulfurization wastewater produced by calcium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the first water inlet mode; When the desulfurization wastewater to be treated is desulfurization wastewater produced by magnesium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the second water inlet mode; Wherein, in the case of the first water inlet mode, the desulfurization wastewater to be treated is transported to the first clarification device for treatment to obtain the first transition clear liquid, including: The desulfurization wastewater to be treated generated by calcium desulfurization is transported to a gypsum dehydration system for dehydration to obtain first filtrate water; The first filtrate water is transported to a triple-tank treatment system for treatment to obtain a first transition clear liquid; The first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, including: The first transition clear liquid is transported to a first electrochemical reaction device, wherein an anode reaction chamber of the first electrochemical reaction device produces a first gas reaction product, and a cathode reaction chamber of the first electrochemical reaction device produces a first liquid reaction product; The first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, comprising: The first gas reaction product is chlorine gas, and the first gas reaction product is transported to the first acid liquid tank, and the gas overflowing from the first acid liquid tank enters the first liquid alkali tank to obtain a sodium hypochlorite product; The first intermediate liquid discharged from the first acid tank is transported to a neutralization water tank added with refined lime powder, and then transported to a sedimentation tank. The sediment in the sedimentation tank is a refined gypsum product, and the supernatant in the sedimentation tank is transported to a pulping system; The first liquid reaction product is transported to a slurry making system, and combined with the supernatant output from the sedimentation tank and lime powder to prepare a first desulfurizing agent slurry; The effluent from the cathode reaction chamber of the first electrochemical reaction device is alkaline, and the pH value is adjusted between 9 and 12; Wherein, in the case of the second water inlet mode, the desulfurization wastewater to be treated is transported to the second clarification device for treatment to obtain the second transition clear liquid, including: The desulfurization wastewater to be treated generated by magnesium desulfurization is transported to a rapid clarification device for clarification to obtain a second transition clear liquid; The second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product, including: The second transition clear liquid is transported to a second electrochemical reaction device, the anode reaction chamber of the second electrochemical reaction device produces a second gas reaction product, and the cathode reaction chamber of the second electrochemical reaction device produces a second liquid reaction product; The second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product, comprising: The second gas reaction product is chlorine gas, and the second gas reaction product is transported to the second acid liquid tank, and the gas overflowed from the second acid washing tank enters the second liquid alkali tank to obtain a sodium hypochlorite product; The second intermediate liquid discharged from the second acid liquid tank is transported to the desulfurization slurry pool; The second liquid reaction product is transported to a desulfurization slurry pool, and combined with the second intermediate liquid and magnesium oxide discharged from the second acid liquid tank to prepare a second desulfurization agent slurry; The outlet water of the cathode reaction chamber of the second electrochemical reaction device is alkaline, and the pH value is adjusted between 9 and 12 according to the working conditions.

2. A desulfurization wastewater treatment system, comprising an electrochemical reaction device, a clarification device and a recycling treatment device connected to the electrochemical reaction device, characterized in that: The electrochemical reaction device comprises: a first electrochemical reaction device and a second electrochemical reaction device; The clarification device comprises: a first clarification device and a second clarification device; The reuse processing device comprises: a first reuse processing device and a second reuse processing device; The liquid outlet of the first clarification device is connected to the liquid inlet of the first electrochemical reaction device, and the liquid outlet of the first electrochemical reaction device is connected to the liquid inlet of the first recycling treatment device; The liquid outlet of the second clarification device is connected to the liquid inlet of the second electrochemical reaction device, and the liquid outlet of the first electrochemical reaction device is connected to the liquid inlet of the second recycling treatment device; According to the water inlet mode, the desulfurization wastewater to be treated is transported to the first clarification device for treatment to obtain the first transition clear liquid, or the desulfurization wastewater to be treated is transported to the second clarification device for treatment to obtain the second transition clear liquid; According to the water inlet method, the first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, or the second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product; According to the water inlet mode, the first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, or the second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product; Wherein, the water inlet mode of the desulfurization wastewater to be treated is determined according to the type of the desulfurization wastewater to be treated, and the type of the desulfurization wastewater to be treated includes: desulfurization wastewater generated by calcium desulfurization or desulfurization wastewater generated by magnesium desulfurization; Among them, according to the type of desulfurization wastewater to be treated, the water inlet method of the desulfurization wastewater to be treated is determined, including: When the desulfurization wastewater to be treated is desulfurization wastewater produced by calcium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the first water inlet mode; When the desulfurization wastewater to be treated is desulfurization wastewater produced by magnesium desulfurization, determining that the water inlet mode of the desulfurization wastewater to be treated is the second water inlet mode; Wherein, in the case of the first water inlet mode, the desulfurization wastewater to be treated is transported to the first clarification device for treatment to obtain the first transition clear liquid, including: The desulfurization wastewater to be treated generated by calcium desulfurization is transported to a gypsum dehydration system for dehydration to obtain first filtrate water; The first filtrate water is transported to a triple-tank treatment system for treatment to obtain a first transition clear liquid; The first transition clear liquid is transported to a first electrochemical reaction device for treatment to obtain a first reaction product, including: The first transition clear liquid is transported to a first electrochemical reaction device, wherein an anode reaction chamber of the first electrochemical reaction device produces a first gas reaction product, and a cathode reaction chamber of the first electrochemical reaction device produces a first liquid reaction product; The first reaction product is transported to a first recycling treatment device for treatment to obtain a first target product, comprising: The first gas reaction product is chlorine gas, and the first gas reaction product is transported to the first acid liquid tank, and the gas overflowing from the first acid liquid tank enters the first liquid alkali tank to obtain a sodium hypochlorite product; The first intermediate liquid discharged from the first acid tank is transported to a neutralization water tank added with refined lime powder, and then transported to a sedimentation tank. The sediment in the sedimentation tank is a refined gypsum product, and the supernatant in the sedimentation tank is transported to a pulping system; The first liquid reaction product is transported to a slurry making system, and combined with the supernatant output from the sedimentation tank and lime powder to prepare a first desulfurizing agent slurry; The effluent from the cathode reaction chamber of the first electrochemical reaction device is alkaline, and the pH value is adjusted between 9 and 12; Wherein, in the case of the second water inlet mode, the desulfurization wastewater to be treated is transported to the second clarification device for treatment to obtain the second transition clear liquid, including: The desulfurization wastewater to be treated generated by magnesium desulfurization is transported to a rapid clarification device for clarification to obtain a second transition clear liquid; The second transition clear liquid is transported to a second electrochemical reaction device for treatment to obtain a second reaction product, including: The second transition clear liquid is transported to a second electrochemical reaction device, the anode reaction chamber of the second electrochemical reaction device produces a second gas reaction product, and the cathode reaction chamber of the second electrochemical reaction device produces a second liquid reaction product; The second reaction product is transported to a second recycling treatment device for treatment to obtain a second target product, comprising: The second gas reaction product is chlorine gas, and the second gas reaction product is transported to the second acid liquid tank, and the gas overflowed from the second acid washing tank enters the second liquid alkali tank to obtain a sodium hypochlorite product; The second intermediate liquid discharged from the second acid liquid tank is transported to the desulfurization slurry pool; The second liquid reaction product is transported to a desulfurization slurry pool, and combined with the second intermediate liquid and magnesium oxide discharged from the second acid liquid tank to prepare a second desulfurization agent slurry.

3. The desulfurization wastewater treatment system according to claim 2, characterized in that: The first clarification device comprises: a gypsum dehydration system and a triple-box treatment system, the water outlet of the gypsum dehydration system is connected to the water inlet of the triple-box treatment system, and the water outlet of the triple-box treatment system is connected to the water inlet of the first electrochemical reaction device through a clean water tank; The first recycling treatment device comprises: a first acid liquid tank, a first liquid alkali tank, a neutralization water tank, a sedimentation tank and a pulping system, the liquid outlet of the cathode reaction chamber of the first electrochemical reaction device is connected to the pulping system, the liquid outlet of the anode reaction chamber of the first electrochemical reaction device is connected to the liquid inlet of the first acid liquid tank, the gas outlet of the first acid liquid tank is connected to the gas inlet of the first liquid alkali tank, the liquid outlet of the first acid liquid tank is connected to the liquid inlet of the neutralization water tank, the liquid outlet of the neutralization water tank is connected to the sedimentation tank, and the liquid outlet of the sedimentation tank is connected to the pulping system; The second clarification device comprises a rapid clarification device, and a water outlet of the rapid clarification device is connected to a water inlet of the second electrochemical reaction device; The second recycling treatment device includes: a second acid liquid tank, a second liquid alkali tank and a desulfurization slurry pool, the liquid outlet end of the cathode reaction chamber of the second electrochemical reaction device is connected to the desulfurization slurry pool, the liquid outlet end of the anode reaction chamber of the second electrochemical reaction device is connected to the liquid inlet end of the second acid liquid tank, the gas outlet end of the second acid liquid tank is connected to the gas inlet end of the second liquid alkali tank, and the liquid outlet end of the second acid liquid tank is connected to the desulfurization slurry pool.

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