Flue gas cleaning resource recovery system and method

Abstract

The application belongs to the technical field of flue gas purification and discloses a flue gas purification resource recovery system and method, wherein the resource recovery system comprises a flue gas low-temperature adsorption purification regeneration system, an alkali preparation system, a first purification system, a sodium metabisulfite synthesis system, a tail gas treatment system and a separation and drying system; the flue gas low-temperature adsorption purification regeneration system comprises a cooling device for cooling flue gas to low-temperature flue gas below room temperature, a low-temperature adsorption device for adsorbing and purifying the low-temperature flue gas into clean flue gas by an adsorbent and a regeneration device for regenerating the adsorbent saturated with adsorption and generating sulfur-containing regenerated gas; the first purification system is connected with the regeneration device; and the sodium metabisulfite synthesis system is connected with the alkali preparation system and the first purification system. The flue gas purification resource recovery system and method have the advantages that the produced sodium metabisulfite product has high purity and no yellowing phenomenon; and the synthesis tail gas and the drying tail gas are treated separately, no external discharge is generated and no secondary pollution is caused.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas purification, and in particular relates to a flue gas purification resource recovery system and a flue gas purification resource recovery method. Background Art

[0002] During the flue gas purification process, the sulfur-containing regeneration gas obtained usually consists of: SO2 2-5% by volume, NO x 3-6% by volume, N2 55-62% by volume, CO2 2-5% by volume, HCl 0.05-0.1% by volume, HF 0.05-0.1% by volume, H2O19-28% by volume, solid particles; wherein the solid particles include Fe 0.005-0.015wt%, Hg 0.001-0.0.01wt%, dust, etc.

[0003] This sulfur-containing regeneration gas is usually used for sodium metabisulfite process recovery, but due to the high content of gas impurities, the presence of metal ions such as iron and mercury, and the low sulfur dioxide content, there are problems such as low product purity (95-96%), yellow color, and complex pretreatment procedures before synthesizing sodium metabisulfite, high cost and energy consumption. At the same time, related industries use activated carbon desulfurization and denitrification system regeneration gas to prepare sodium metabisulfite, and the treated reaction tail gas usually requires SO2 < 35mg / Nm 3 , and then discharged into the atmosphere. However, this process has the disadvantages of low treatment concentration, large amounts of absorption liquid required, and high alkaline solution consumption. In addition, other flue gas treatment technologies, such as Cold Oxidation Adsorption (COAP), have been proposed. However, the regenerated gas contains high concentrations of sulfur dioxide and nitrogen monoxide, and direct discharge can cause secondary environmental pollution. Furthermore, due to the high temperature of the flue gas, direct discharge not only pollutes the environment but also wastes heat energy. Summary of the Invention

[0004] In view of this, one object of the present invention is to propose a flue gas purification resource recovery system, in which the sulfur-containing regeneration gas from the flue gas low-temperature adsorption purification regeneration system is used for metabisulfite production, and the produced sodium metabisulfite product has good purity, no yellowing phenomenon, and high product whiteness; at the same time, the synthetic tail gas and the drying tail gas are treated separately, which can save the amount of soda ash, save costs, and no external discharge will cause secondary pollution; in addition, the separation drying system uses the hot flue gas to be treated as the heat exchange medium, which saves heat source and reduces energy consumption.

[0005] Another object of the present invention is to provide a flue gas purification resource recovery method.

[0006] To achieve the above objectives, the present invention proposes a flue gas purification resource recovery system, comprising:

[0007] A flue gas low-temperature adsorption purification and regeneration system, comprising a cooling device for cooling the flue gas to low-temperature flue gas below room temperature, a low-temperature adsorption device for purifying the low-temperature flue gas into clean flue gas through adsorption by an adsorbent, and a regeneration device for regenerating the adsorbent that has been saturated with adsorption and generating sulfur-containing regeneration gas;

[0008] an alkali preparation system, the alkali preparation system being used to prepare soda ash into alkali liquor;

[0009] a first purification system, the first purification system being connected to the regeneration device and being used to purify the sulfur-containing regeneration gas discharged from the regeneration device;

[0010] a sodium metabisulfite synthesis system, connected to the alkali preparation system and the first purification system, for synthesizing sodium metabisulfite using the alkali solution prepared by the alkali preparation system and the purified sulfur-containing regeneration gas;

[0011] An exhaust gas treatment system, connected to the alkali preparation system and the sodium metabisulfite synthesis system, for purifying the synthesis exhaust gas discharged from the sodium metabisulfite synthesis system using the alkali solution prepared by the alkali preparation system;

[0012] A separation and drying system having a liquid inlet, a drying gas inlet, and a drying tail gas outlet, wherein the liquid inlet is connected to the sodium metabisulfite synthesis system, the drying gas inlet is connected to a hot flue gas pipeline, and the drying tail gas outlet is connected to a cooling device of the flue gas low-temperature adsorption purification and regeneration system. The separation and drying system is used to utilize the hot flue gas supplied by the hot flue gas pipeline to dry the supersaturated solution discharged from the sodium metabisulfite synthesis system to obtain a finished sodium metabisulfite product, and the dried tail gas is sent to the flue gas low-temperature adsorption purification and regeneration system for adsorption purification treatment.

[0013] The flue gas purification resource recovery system of the present invention uses the sulfur-containing regeneration gas from the flue gas low-temperature adsorption purification and regeneration system for metabisulfite production. The produced sodium metabisulfite product has high purity, no yellowing, and high whiteness. At the same time, the synthetic tail gas and the drying tail gas are treated separately, which can save the amount of soda ash used and save costs, and no external discharge will cause secondary pollution. In addition, the separation drying system uses the hot flue gas from the power plant as the heat exchange medium, which saves heat source and reduces energy consumption.

[0014] Furthermore, the sulfur-containing regeneration gas includes the following components: SO2 28-30% by volume, NO x4.7-5.1% by volume, N242-44% by volume, CO2 4-6% by volume, H2O 19-21% by volume, HCl 0.05-0.1% by volume, and dust. In the present invention, the sulfur-containing regeneration gas has a high sulfur dioxide content, a low gas impurity content, and is free of other particulate matter other than dust and metal ions such as iron. When used in the preparation of metabisulfite, it has few side reactions, a fast chemical reaction rate, and a high yield, thereby obtaining high-quality (high purity, purity >98%, no yellowing, and high product whiteness) sodium metabisulfite.

[0015] Furthermore, the slurry outlet of the separation and drying system is connected to the alkali preparation system to return the slurry discharged from the separation and drying system to the alkali preparation system for preparing alkali solution. In this way, the slurry can be reused, saving the overall alkali solution consumption of the system.

[0016] Furthermore, in some cases, the first purification system is a spray scrubber. In the present invention, the first purification system adopts a spray scrubber, which can remove hydrogen chloride, dust and water-soluble NO in the sulfur-containing regeneration gas by spray scrubbing. x wait.

[0017] Furthermore, in some other cases, the first purification system includes a first oxidation tower and a first ozone generator; the first ozone generator has a first ozone outlet, and the first oxidation tower has a first ozone inlet, a first gas inlet, a first gas outlet, a first process water inlet, and a first acid outlet; the first ozone inlet is connected to the first ozone outlet, the first gas inlet is connected to the sulfur-containing regeneration gas outlet of the regeneration device, the first gas outlet is connected to the sodium metabisulfite synthesis system to supply the purified sulfur-containing regeneration gas to the sodium metabisulfite synthesis system, the first process water inlet is connected to the first process water pipeline, and the first acid outlet is connected to the plant water treatment system. When the first purification system uses the first oxidation tower, the sulfur-containing regeneration gas passing through the first oxidation tower can absorb and remove NO, producing pure SO2, which is beneficial for improving product purity; and compared with traditional purification pretreatment processes, the use of the first oxidation tower can simultaneously remove NO and scrub the flue gas to remove particulate matter and gases such as HCl.

[0018] Furthermore, in some other cases, the flue gas purification resource recovery system also includes a second purification system and a nitrogen recovery system; the second purification system includes a second oxidation tower and a second ozone generator; the second ozone generator has a second ozone outlet, and the second oxidation tower has a second ozone inlet, a second gas inlet, a second process water inlet and a second acid liquid outlet; the second ozone inlet is connected to the second ozone outlet, the second gas inlet is connected to the tail gas outlet of the tail gas treatment system, the second process water inlet is connected to the second process water pipeline, and the second acid liquid outlet is connected to the nitrogen recovery system. In this way, the nitrogen-containing tail gas from the tail gas treatment system enters the second oxidation tower and converts nitrogen monoxide into nitrogen dioxide under the action of ozone. The nitrogen dioxide dissolves in the second process water and is converted into nitric acid. The nitric acid is sent to the nitrogen recovery system, or is directly collected, or continues to react with liquid ammonia to form ammonium nitrate, thereby realizing the recovery and utilization of nitrogen in the sulfur-containing regeneration gas.

[0019] Furthermore, the flue gas purification resource recovery system also includes a second purification system, the air inlet of the second purification system is connected to the tail gas outlet of the tail gas treatment system; the second purification system is a boiler for burning NO in the tail gas purified by the tail gas treatment system. x .

[0020] Furthermore, the tail gas treatment system is a tail gas absorption tower. The tail gas discharged from the sodium metabisulfite synthesis system is absorbed by the absorption liquid (soda ash solution) in the tail gas absorption tower, and the tail gas concentration can be reduced to SO2 < 3500 mg / Nm 3 .

[0021] Furthermore, the sodium metabisulfite synthesis system is a sodium metabisulfite synthesis multi-stage reactor.

[0022] Furthermore, the separation and drying system includes a centrifuge and a dryer connected in sequence, the liquid inlet of the centrifuge is connected to the supersaturated solution outlet of the sodium metabisulfite synthesis system, the solid outlet of the centrifuge is connected to the solid inlet of the dryer, the exhaust pipeline of the feed port of the centrifuge, the overflow pipeline of the alkali preparation system, the pit exhaust pipeline, and the dry tail gas outlet of the dryer are all connected to the flue gas low-temperature adsorption purification and regeneration system, and the dry gas inlet of the dryer is connected to the hot flue gas pipeline. The separation and drying system uses the hot flue gas of the power plant as a heat exchange medium, which saves heat source and has low energy consumption. In addition, by connecting the exhaust pipeline of the feed port of the centrifuge, the overflow pipeline of the alkali preparation system, the pit exhaust pipeline, and the dry tail gas outlet of the dryer to the flue gas low-temperature adsorption purification and regeneration system, the waste gas in the factory area can be treated as much as possible and environmental pollution can be reduced.

[0023] The present invention also proposes a flue gas purification resource recovery method, comprising:

[0024] Cooling the flue gas to low-temperature flue gas below room temperature;

[0025] Adsorbing and purifying the low-temperature flue gas into clean flue gas by using an adsorbent;

[0026] regenerating the adsorbent saturated with adsorption to obtain regenerated adsorbent and sulfur-containing regeneration gas;

[0027] The purified sulfur-containing regeneration gas is reacted with the prepared alkali solution to obtain a supersaturated sodium bisulfite solution;

[0028] The supersaturated sodium bisulfite solution is sequentially subjected to solid-liquid separation and hot flue gas drying to obtain a sodium metabisulfite product;

[0029] Cooling the dry tail gas generated by the drying to low-temperature flue gas below room temperature for adsorbent purification;

[0030] The synthetic tail gas generated by the reaction of the sulfur-containing regeneration gas and the alkali solution is subjected to alkali solution purification treatment.

[0031] Preferably, the sulfur-containing regeneration gas comprises the following components: SO2 28-30% by volume, NO x 4.7-5.1% by volume, N242-44% by volume, CO2 4-6% by volume, H2O 19-21% by volume, HCl 0.05-0.1% by volume, and dust. In the present invention, the sulfur-containing regeneration gas has a high sulfur dioxide content, a low gas impurity content, and is free of other particulate matter other than dust and metal ions such as iron. When used in the preparation of metabisulfite, it has few side reactions, a fast chemical reaction rate, and a high yield, thereby obtaining high-quality (high purity, purity >98%, no yellowing, and high product whiteness) sodium metabisulfite.

[0032] Preferably, in some cases, the purification method of the sulfur-containing regeneration gas is: the sulfur-containing regeneration gas is sprayed and washed with process water in a spray washing tower. In the present invention, the process water spray washing can remove hydrogen chloride, dust and water-soluble NO in the sulfur-containing regeneration gas. x wait.

[0033] Preferably, in other cases, the sulfur-containing regeneration gas is purified by reacting the sulfur-containing regeneration gas with ozone in a first oxidation tower to convert nitrogen monoxide into nitrogen dioxide, which is then absorbed by water. Passing the sulfur-containing regeneration gas through the first oxidation tower can, on the one hand, absorb and remove NO, producing pure SO2, thereby improving product purity. Furthermore, compared to traditional purification pretreatment processes, the use of the first oxidation tower can simultaneously remove NO and scrub the flue gas to remove particulate matter and gases such as HCl.

[0034] Preferably, in some cases, the flue gas purification resource recovery method further includes: sending the tail gas discharged from the synthesis tail gas treatment system after the alkali solution purification treatment to a boiler for recycling. In this way, the tail gas discharged from the synthesis tail gas treatment system can be burned in the boiler to remove nitrogen oxides, especially nitric oxide.

[0035] Preferably, in other cases, the flue gas purification resource recovery method further comprises:

[0036] The tail gas discharged from the tail gas treatment system is sent to a second oxidation tower to convert nitrogen monoxide into nitrogen dioxide under the action of ozone;

[0037] Nitrogen dioxide is reacted with water to produce nitric acid, or with water and liquid ammonia to produce ammonium nitrate. This not only removes nitrogen monoxide from the tail gas, but also recycles nitrogen resources.

[0038] In some embodiments, the flue gas purification resource recovery method further includes: cooling the overflow gas from the alkali solution and the exhaust gas from the pit to low-temperature flue gas and performing adsorption purification. In this way, the waste gas from the factory can be treated as much as possible, reducing environmental pollution.

[0039] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0041] Figure 1 Schematic diagram of a flue gas purification resource recovery system according to one embodiment of the present invention.

[0042] Figure 2 is a schematic diagram of a flue gas purification resource recovery system according to another embodiment of the present invention.

[0043] Figure 3 Schematic diagram of a flue gas purification resource recovery system according to another embodiment of the present invention.

[0044] Figure 4 Schematic diagram of a flue gas low-temperature adsorption purification and regeneration system in a flue gas purification resource recovery system according to an embodiment of the present invention.

[0045] Figure 5 yes Figure 2 Schematic diagram of the first purification system in the flue gas purification resource recovery system.

[0046] Figure 6 yes Figure 2Schematic diagram of the second purification system in the flue gas purification resource recovery system.

[0047] Figure 7 This is a schematic diagram of the structure of an adsorption unit in an exemplary flue gas purification resource recovery system of the present application.

[0048] Reference numerals:

[0049] 1-Alkali preparation system; 2-First purification system; 201-First oxidation tower; 202-First ozone generator; 203-First air pipeline; 204-First process water pipeline; 205-Plant water treatment system; 206-First circulation pump; 3-Sodium metabisulfite synthesis system; 4-Tail gas treatment system; 5-Separation and drying system; 6-Flue gas low-temperature adsorption purification and regeneration system; 601-Cooling device; 602-Low-temperature adsorption device; 6021-Adsorbent particles; 6022-Breathable shell; 603-Regeneration device; 7-Second purification system; 701-Second oxidation tower; 702-Second ozone generator; 703-Second process water pipeline; 704-Second air pipeline; 705-Second circulation pump; 8-Nitrogen recovery system; 10-Soda ash; 11-Sulfur-containing regeneration gas; 12-Hot flue gas pipeline; 13-Finished salt. DETAILED DESCRIPTION

[0050] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0051] In the invention, the raw materials, equipment, etc. involved, unless otherwise specified, are all raw materials and equipment that can be obtained through commercial channels or known methods; the methods involved, unless otherwise specified, are all conventional methods.

[0052] The following describes a flue gas purification resource recovery system and a flue gas purification resource recovery method according to an embodiment of the present invention with reference to the accompanying drawings.

[0053] Figure 1 Schematic diagram of a flue gas purification resource recovery system according to one embodiment of the present invention.

[0054] like Figure 1 As shown, the flue gas purification resource recovery system of an embodiment of the present invention includes a flue gas low-temperature adsorption purification and regeneration system 6, an alkali preparation system 1, a first purification system 2, a sodium metabisulfite synthesis system 3, an exhaust gas treatment system 4 and a separation and drying system 5.

[0055] The flue gas low-temperature adsorption purification regeneration system 6 includes a cooling device 601 for cooling the flue gas to low-temperature flue gas below room temperature, a low-temperature adsorption device 602 for purifying the low-temperature flue gas into clean flue gas through adsorption by an adsorbent, and a regeneration device 603 for regenerating the adsorption-saturated adsorbent and generating sulfur-containing regeneration gas.

[0056] The alkali preparation system 1 is used to prepare soda ash 10 into an alkaline solution. The first purification system 2 is connected to the regeneration device 603 and is used to purify the sulfur-containing regeneration gas 11 discharged from the regeneration device 603. The sodium metabisulfite synthesis system 3 is connected to the alkali preparation system 1 and the first purification system 2 and is used to synthesize sodium metabisulfite using the alkaline solution prepared by the alkali preparation system 1 and the purified sulfur-containing regeneration gas.

[0057] The tail gas treatment system 4 is connected to the alkali preparation system 1 and the sodium metabisulfite synthesis system 3 and is used to purify the synthesis tail gas discharged from the sodium metabisulfite synthesis system 3 using the alkali solution prepared by the alkali preparation system 1. The separation and drying system 5 has a liquid inlet, a drying gas inlet, and a drying tail gas outlet. The liquid inlet is connected to the sodium metabisulfite synthesis system 3, the drying gas inlet is connected to the hot flue gas pipeline 12, and the drying tail gas outlet is connected to the cooling device 601 of the flue gas low-temperature adsorption purification and regeneration system 6. The separation and drying system 5 is used to dry the supersaturated solution discharged from the sodium metabisulfite synthesis system 3 using the hot flue gas supplied by the hot flue gas pipeline 12 to produce the finished sodium metabisulfite. The dried tail gas is then sent to the flue gas low-temperature adsorption purification and regeneration system 6 for adsorption purification.

[0058] The flue gas purification and resource recovery system of the present invention utilizes sulfur-containing regeneration gas from a low-temperature flue gas adsorption purification and regeneration system for metabisulfite production. The resulting sodium metabisulfite product boasts a purity exceeding 98%, exhibits no yellowing, and exhibits high whiteness. Furthermore, the separate treatment of synthesis and drying tail gas reduces soda ash usage and costs, while eliminating exhaust and secondary pollution. Furthermore, the separate drying system utilizes hot flue gas, such as from a power plant, as a heat exchange medium, conserving heat sources and reducing energy consumption.

[0059] It should be noted that, in the embodiment of the present invention, since the sulfur-containing regeneration gas of the flue gas low-temperature adsorption purification and regeneration system has a high sulfur dioxide content, a low gas impurity content, and no particulate matter other than dust, and no metal ions such as iron, it is used for the preparation of metabisulfite, with few side reactions, a fast chemical reaction rate, and a high yield, so that high-quality (good purity, purity > 98%, no yellowing, and high product whiteness) sodium metabisulfite can be obtained.

[0060] In addition, treating the synthetic tail gas and the dry tail gas separately, in addition to saving the amount of soda ash compared to treating both the dry tail gas and the synthetic tail gas with alkaline solution absorption, is also based on the following considerations: on the one hand, the temperature of the dry tail gas is much higher than that of the synthetic tail gas, and direct alkaline solution absorption will waste the residual heat in the dry tail gas, resulting in energy waste. If it is treated separately, it can be reused in the plant heat exchange system (such as production and domestic water, etc.) to realize waste heat utilization; on the other hand, the dry tail gas contains dust and is not suitable for entering the boiler for subsequent treatment. After the synthetic tail gas is absorbed by the alkaline solution, a boiler can be set up for subsequent treatment in order to further purify it.

[0061] In the embodiment of the present invention, when the flue gas low-temperature adsorption purification regeneration system is used, the flue gas is cooled to low-temperature flue gas by a cooling device, for example, cooled to below room temperature, preferably below zero degrees Celsius, for example (-80) ℃ ~ (-5) ℃, more preferably below zero (-20) ℃ ~ (-15) ℃, and then contains SO2 and NO x The low-temperature flue gas enters the low-temperature adsorption device to remove sulfur dioxide and nitrogen oxides in the flue gas. The adsorbent saturated with adsorption (such as activated coke, etc.) enters the regeneration device for heating and desorption of sulfur dioxide and nitrogen oxides to form sulfur-containing regeneration gas.

[0062] Regarding the selection of low-temperature flue gas temperature, the inventors have found through research that the lower the flue gas temperature, the more beneficial it is for adsorption purification. However, too low a flue gas temperature leads to a complex structure for cooling the flue gas and increased energy consumption. For example, insulation layers are required for the cooling equipment, adsorption tower, and pipelines, requiring high sealing, which increases costs. In addition, too low a temperature condition easily leads to condensation in the adsorption tower, causing the adsorbent to stick and clog, affecting adsorption. Therefore, cooling the flue gas to a temperature of (-20)°C to (-15)°C is beneficial.

[0063] In some embodiments, as Figure 7 As shown, the adsorbent is part of the adsorption unit, which is provided in a low-temperature adsorption device (for example, an adsorption tower). The adsorption unit further includes a breathable shell 6022, in which the adsorbent is filled. The adsorbent can be in granular form (such as Figure 7The adsorbent particles 6021) or powdered adsorbent in the adsorbent body may also be an adsorbent body made of powdered or granular adsorbent, such as a sphere or cylinder formed by a powdered or granular adsorbent through a binder. Of course, a protective shell may be further formed on the outside of the adsorbent body, such as a breathable film covering the outside of the adsorbent body, to improve the strength of the adsorbent body. The breathable outer shell 6022 has air holes, through which the flue gas can enter the breathable outer shell, and the flue gas can pass through the gaps between adjacent adsorbents and / or the holes of the adsorbent itself, thereby reducing not only the direct collision, friction and wear between the adsorbents, but also the generation of dust. The breathable outer shell 6022 may be in the shape of a rotating body such as a sphere or a cylinder, wherein the diameter of the adsorption unit is 10mm-100mm, and the diameter of the adsorbent is 1mm-10mm.

[0064] As a non-limiting example, Figure 4 As shown, the cooling device 601 of the flue gas low-temperature adsorption purification regeneration system 6 includes but is not limited to a spray cooling tower, etc., and the low-temperature adsorption device 602 includes but is not limited to a device capable of simultaneously adsorbing SO2 and NO at low temperatures. x The adsorption tower, etc., the regeneration device 603 includes but is not limited to the regeneration tower, etc.

[0065] In some embodiments, the composition of the sulfur-containing regeneration gas includes: SO2 28-30%, NO x 4.7-5.1%, N2 42-44%, CO2 4-6%, H2O 19-21%, HCl 0.05-0.1% and dust, where "%" is the volume percentage. The composition does not contain any other particulate matter other than dust and does not contain metal ions such as iron. NO x The NO content in it is above 90%.

[0066] In some embodiments, the alkali preparation system 1 can be a commercially available fully automatic alkali preparation system, and the sodium metabisulfite synthesis system 3 can also be a sodium metabisulfite synthesis multi-stage reactor, such as an existing three-stage reactor (e.g., three stainless steel reactors connected in series).

[0067] In some embodiments, the separation and drying system includes a centrifuge and a dryer connected in sequence, wherein the liquid inlet of the centrifuge is connected to the supersaturated solution outlet of the sodium metabisulfite synthesis system 3 for solid-liquid separation of the supersaturated solution. The solid outlet of the centrifuge is connected to the solid inlet of the dryer. The centrifuge discharge port exhaust pipeline, the overflow pipeline of the alkali preparation system 1, the pit exhaust pipeline, and the dry tail gas outlet of the dryer are all connected to the flue gas low-temperature adsorption purification and regeneration system 6. The dryer's dry gas inlet is connected to the hot flue gas pipeline 12, using the waste heat of the hot flue gas to dry the solids from the centrifuge. The finished salt (i.e., the sodium metabisulfite product) is then collected through the solid outlet of the dryer.

[0068] It should be noted that the pit gas in the pit exhaust pipeline comes from the acidic washing liquid discharged from the pretreatment system (the pretreatment system here refers to the situation where the first purification system is a spray washing tower or an additional washing pretreatment system for sulfur-containing tail gas before entering the sodium metabisulfite synthesis system). The acid water in the pit will release acidic gas, which is the waste gas in the sodium metabisulfite synthesis system.

[0069] It should also be noted that the exhaust gases discharged along with the drying exhaust gas into the flue gas low-temperature adsorption purification and regeneration system 6, such as the overflow gas from the alkali preparation system, the exhaust gas from the centrifuge discharge port, and the exhaust gas from the pit, can be collected as a whole and then fed into the flue gas low-temperature adsorption purification and regeneration system. Alternatively, the hot flue gas in the dryer can be dried in direct contact with sodium metabisulfite.

[0070] In some embodiments, to reuse the slurry and save the overall alkali solution usage of the system, the slurry outlet of the separation and drying system 5 is connected to the alkali preparation system 1 to return the slurry discharged from the separation and drying system to the alkali preparation system for preparing alkali solution. Specifically, the slurry outlet of the centrifuge can be connected to the material inlet of the alkali preparation system 1.

[0071] In the embodiment of the present invention, the first purification system can purify the sulfur-containing regeneration gas to obtain clean sulfur-rich gas which enters the sodium metabisulfite synthesis system to react with soda ash to produce a supersaturated sodium bisulfite solution.

[0072] In some embodiments, the first purification system 2 uses a spray scrubber. In other embodiments, such as Figure 2 and Figure 5 As shown, the first purification system 2 includes a first oxidation tower 201 and a first ozone generator 202; the first ozone generator 202 has a first ozone outlet, which is connected to the first ozone inlet of the first oxidation tower 201; the first oxidation tower 201 is provided with a first gas inlet (i.e., a sulfur-containing regeneration gas inlet) and a first gas outlet; the first gas inlet is connected to the sulfur-containing regeneration gas outlet of the regeneration device 603, and the first gas outlet is connected to the sodium metabisulfite synthesis system 3 to supply the purified sulfur-containing regeneration gas to the sodium metabisulfite synthesis system.

[0073] As a non-limiting example, the embodiment of the present application uses air to produce ozone, in which case the first ozone generator 202 further has a first air inlet, which is connected to the first air pipeline 203. The first oxidation tower 201 further has a first process water inlet, which is connected to the first process water pipeline 204, and a first acid liquid outlet, which is connected to the plant water treatment system 205. A first circulating pump 206 can be installed on the pipeline connecting the first acid liquid outlet and the plant water treatment system 205. In this way, the nitrogen monoxide in the sulfur-containing regenerated gas can be oxidized by ozone in the first oxidation tower to convert into nitrogen dioxide, which is then absorbed by the first process water. At the same time, the particulate matter and HCl gas in the high-concentration sulfur-containing regenerated gas of the low-temperature method pollutant integrated removal system can be removed, and a relatively pure sulfur-rich gas (in terms of volume fraction, the composition of the sulfur-rich gas is: SO2 30-32%, N2 43-45%, CO2 3-4%, H2O 19-21%) can be obtained.

[0074] In some embodiments, the tail gas treatment system 4 can use a tail gas absorption tower. In order to further purify the tail gas discharged by the tail gas treatment system, the flue gas purification resource recovery system of the embodiment of the present application further includes a second purification system 7, the gas inlet of which is connected to the tail gas outlet of the tail gas treatment system 4.

[0075] As an optional example, the second purification system 7 can use a boiler. In this case, after the reaction tail gas discharged from the sodium pyrosulfite synthesis system is absorbed by the absorption liquid (soda solution) in the tail gas absorption tower, the concentration of the tail gas can be reduced to SO2 < 3500 mg / Nm 3 After that, the tail gas discharged from the tail gas treatment system is sent to the plant boiler for re-furnace combustion treatment to remove NO x from the tail gas.

[0076] As another optional example, as Figure 3 and Figure 6As shown, in order to achieve the simultaneous recovery and utilization of sulfur and nitrogen in the high-concentration sulfur-containing regeneration gas, the flue gas purification resource recovery system of the embodiment of the present invention also includes a nitrogen recovery system 8. In this case, the second purification system 7 includes a second oxidation tower 701 and a second ozone generator 702; the second ozone generator 702 has a second air inlet and a second ozone outlet, the second air inlet is connected to the second air pipeline 704, and the second ozone outlet is connected to the second ozone inlet of the second oxidation tower 701; the second oxidation tower 701 is also provided with a second gas inlet, a second process water inlet, and a second acid liquid outlet; the second gas inlet is connected to the exhaust gas outlet of the exhaust gas treatment system 4, the second process water inlet is connected to the second process water pipeline 703, and the second acid liquid outlet is connected to the nitrogen recovery system 8. A second circulation pump 705 can be installed on the pipeline connecting the second acid liquid outlet and the nitrogen recovery system 8. The nitrogen-containing tail gas from the tail gas treatment system enters the second oxidation tower, where the nitrogen monoxide is converted into nitrogen dioxide under the action of ozone. The nitrogen dioxide is dissolved in the second process water and converted into nitric acid. The nitric acid is sent to the nitrogen recovery system, where it is either directly collected or further reacted with liquid ammonia to form ammonium nitrate, thereby realizing the recovery and utilization of nitrogen in the sulfur-containing regeneration gas.

[0077] It should be noted that, in the flue gas purification resource recovery system of the embodiment of the present invention, when the second purification system includes a second oxidation tower, the first purification system preferably adopts a spray scrubbing tower.

[0078] In addition, it should be noted that in the flue gas purification resource recovery system of the embodiment of the present invention, the communication method between the various components and parts includes but is not limited to pipeline communication, and any suitable communication method in the field can be used.

[0079] The following describes a method for recovering flue gas purification resources according to an embodiment of the present invention. The method for recovering flue gas purification resources according to an embodiment of the present invention comprises the following steps:

[0080] S101. Cool the flue gas to low-temperature flue gas below room temperature.

[0081] In some embodiments, the temperature of the low-temperature flue gas is below zero degrees Celsius, for example (-80)°C to (-5)°C, and preferably (-20)°C to (-15)°C.

[0082] S102. Utilize an adsorbent to adsorb and purify the low-temperature flue gas into clean flue gas.

[0083] In some embodiments, the adsorbent includes but is not limited to activated coke, zeolite, molecular sieve, etc., preferably activated coke.

[0084] S103, regenerating the adsorbent that has reached adsorption saturation to obtain regenerated adsorbent and sulfur-containing regeneration gas.

[0085] The composition of sulfur-containing regeneration gas includes: SO2 28-30%, NOx 4.7-5.1%, N2 42-44%, CO2 4-6%, H2O19-21%, HCl 0.05-0.1% and dust, where "%" is volume percentage. The composition does not contain other particles other than dust and does not contain metal ions such as iron. NO x The NO content in it is above 90%.

[0086] S104, reacting the purified sulfur-containing regenerated gas with the prepared alkali solution to obtain a supersaturated sodium bisulfite solution.

[0087] In some embodiments, the alkali solution may be a 15-30 wt% pure alkali solution.

[0088] In some embodiments, when the first purification system utilizes a spray scrubber, the sulfur-containing regeneration gas is purified within the spray scrubber using process water spray scrubbing. After purification, the sulfur-containing regeneration gas becomes clean, sulfur-rich gas. The sulfur-rich gas comprises, by volume, 28.5-30.5% SO2, 4.8-5.2% NO, 42.5-44.5% N2, 4.5-6.5% CO2, and 19-21% H2O.

[0089] In other embodiments, when the first purification system includes a first oxidation tower and a first ozone generator, the sulfur-containing regeneration gas is purified by reacting the sulfur-containing regeneration gas with ozone in the first oxidation tower to convert nitrogen monoxide into nitrogen dioxide, which is then absorbed by water. After purification, the sulfur-containing regeneration gas becomes clean, sulfur-rich gas. The sulfur-rich gas has a composition, by volume, of 30-32% SO2, 43-45% N2, 3-4% CO2, and 19-21% H2O.

[0090] In the embodiment of the present invention, the sulfur-containing regeneration gas is purified and reacted with alkaline solution to obtain a supersaturated sodium bisulfite solution, and the reaction principle for finally obtaining sodium metabisulfite is as follows:

[0091] (1) SO2 is introduced into a sodium carbonate solution until the pH reaches 4.1 to generate a sodium bisulfite solution. The reaction formula is:

[0092] Na2CO3+2SO2+H2O——2NaHSO3+CO2;

[0093] (2) Sodium bisulfite solution is then added with sodium carbonate to adjust the pH to 7-8, which converts it into sodium sulfite. The reaction formula is:

[0094] Na2CO3+2NaHSO3——2Na2SO3+CO2+H2O;

[0095] (3) Sodium sulfite reacts with SO2 to pH 4.1 to generate sodium bisulfite solution. The reaction formula is:

[0096] Na2SO3+SO2+H2O——2NaHSO3;

[0097] (4) When the sodium bisulfite content in the solution reaches supersaturated concentration, sodium metabisulfite crystals precipitate, reaction formula:

[0098] 2NaHSO3——Na2S2O5+H2O;

[0099] The overall reaction equation is: Na2CO3+2SO2——Na2S2O5+CO2.

[0100] S105. The supersaturated sodium bisulfite solution is sequentially subjected to solid-liquid separation and hot flue gas drying to obtain a sodium metabisulfite product (i.e., finished salt).

[0101] In some embodiments, solid-liquid separation is performed in a centrifuge of the separation and drying system, and hot flue gas drying is performed in a dryer of the separation and drying system.

[0102] In some embodiments, the hot flue gas conditions are: 110℃~150℃, dust content <20mg / Nm 3 .

[0103] In some embodiments, the hot flue gas is dried by direct contact with the sodium metabisulfite.

[0104] S106, cooling the dry tail gas generated by drying to low-temperature flue gas below room temperature for adsorbent purification.

[0105] The composition of dry tail gas includes: dust ≤ 20mg / Nm 3 ; SO2≤2000mg / Nm 3 .

[0106] The temperature of the low-temperature flue gas in step S106 is the same as that in step S101 , and the adsorbent in step S106 is the same as that in step S103 .

[0107] S107, subjecting the synthetic tail gas produced by the reaction of the sulfur-containing regeneration gas and the alkali solution to alkali solution purification treatment.

[0108] In some embodiments, the synthesis tail gas is a high-concentration sulfur-containing gas. When the first purification system adopts a spray scrubber and the sulfur-containing regeneration gas in step S104 is spray-washed with process water, the composition of the synthesis tail gas, calculated by volume fraction, includes: SO2 3-4%, NO 5-7%, N2 48-54%, CO2 5-8%, and H2O 24-27%.

[0109] In some embodiments, the alkali solution purification is carried out in a tail gas absorption tower, and the alkali solution can be a 15-30 wt% soda ash solution. After the synthetic tail gas is purified by the alkali solution, the tail gas concentration is reduced to SO2 < 3500 mg / Nm 3 .

[0110] In some embodiments, the flue gas purification resource recovery method further includes: sending the synthetic tail gas after the alkaline solution purification treatment into a boiler for recycling and combustion treatment.

[0111] In some embodiments, in order to achieve nitrogen recovery, the flue gas purification resource recovery method further includes: sending the exhaust gas discharged from the exhaust treatment system 4 into the second oxidation tower 701, converting nitrogen monoxide into nitrogen dioxide under the action of ozone; and reacting nitrogen dioxide with water to generate nitric acid.

[0112] In other embodiments, in order to achieve nitrogen recovery, the flue gas purification resource recovery method further includes: sending the exhaust gas discharged from the exhaust treatment system 4 into the second oxidation tower 701, converting nitrogen monoxide into nitrogen dioxide under the action of ozone; and reacting nitrogen dioxide with water and liquid ammonia to generate ammonium nitrate.

[0113] In some embodiments, the flue gas purification resource recovery method further includes: cooling the overflow gas from the alkali solution (i.e., the overflow gas from the alkali preparation system) and the exhaust gas from the pit into low-temperature flue gas and performing adsorption purification. The specific processing process is the same as step S102.

[0114] It should be noted that the various steps of the flue gas purification resource recovery method according to the embodiment of the present invention can be adjusted as needed. For example, alkali solution can be prepared first, and then the sulfur-containing regeneration gas can be purified; or the sulfur-containing regeneration gas can be purified first, and then alkali solution can be prepared, and so on.

[0115] The flue gas purification resource recovery system and flue gas purification resource recovery method according to the embodiments of the present invention have the following advantages:

[0116] 1) In related technologies, sulfur-containing regeneration gas from, for example, steel mills, after being recovered through a sodium metabisulfite process, often suffers from high impurity content and yellowish color. The flue gas purification resource recovery system and flue gas purification resource recovery method of the present invention purify the sulfur-containing regeneration gas from a low-temperature flue gas adsorption purification and regeneration system and then use it in sodium metabisulfite production. The resulting sodium metabisulfite product has high purity (>98%), no yellowing, and high whiteness.

[0117] 2) The dry tail gas can be processed in sections and directly sent to the flue gas low-temperature adsorption purification and regeneration system. There is no external discharge and no secondary pollution.

[0118] 3) Compared with other industries that use activated carbon desulfurization and denitrification systems to prepare sodium metabisulfite from regenerated gas and use alkali solution to treat tail gas, the flue gas purification resource recovery system and method of the embodiments of the present invention separately treats the synthetic tail gas and the dry tail gas, which can save soda ash usage and save costs.

[0119] 4) The sulfur and nitrogen resources in the sulfur-containing regenerated gas are recycled and utilized simultaneously, generating economic benefits.

[0120] 5) Sulfur-containing regenerated gas passes through the oxidation tower, which can absorb and remove NO to obtain pure SO2, which is beneficial to improving product purity. On the other hand, compared with the traditional purification pretreatment process, the use of the oxidation tower can remove NO while washing and purifying the flue gas to remove particulate matter and gases such as HCl.

[0121] 7) Separate drying system uses hot flue gas from power plants as heat exchange medium, saving heat source and reducing energy consumption.

[0122] The following non-limiting examples further illustrate the flue gas purification resource recovery system, flue gas purification resource recovery method and some features of the present invention.

[0123] Example 1 (Partial treatment of tail gas)

[0124] like Figure 1 As shown, the flue gas purification resource recovery system of this embodiment includes a flue gas low-temperature adsorption purification and regeneration system 6, an alkali preparation system 1, a first purification system 2, a sodium metabisulfite synthesis system 3, an exhaust gas treatment system 4 and a separation and drying system 5.

[0125] The flue gas low-temperature adsorption purification regeneration system 6 includes a cooling device 601 for cooling the flue gas to a low-temperature flue gas below room temperature (preferably below zero degrees Celsius, more preferably (-20)°C to (-15)°C), a low-temperature adsorption device 602 for purifying the low-temperature flue gas into clean flue gas through adsorption by an adsorbent, and a regeneration device 603 for regenerating the adsorption-saturated adsorbent and producing sulfur-containing regeneration gas.

[0126] The cooling device 601 adopts a spray cooling tower, and the low-temperature adsorption device 602 adopts an adsorption tower that can simultaneously remove sulfur dioxide and nitrogen oxides. The adsorption tower is provided with an adsorbent, which is activated coke. The regeneration device 603 is a regeneration tower.

[0127] The alkali preparation system 1 adopts a commercially available fully automatic alkali preparation system, which is used to prepare soda ash 10 into alkali solution; the inlet of the first purification system 2 is connected to the sulfur-containing regeneration gas outlet of the regeneration device 603, which is used to purify the sulfur-containing regeneration gas discharged from the regeneration device; the first purification system 2 adopts a spray washing tower, which is provided with a process water inlet for spray purification of the sulfur-containing regeneration gas 11.

[0128] The sodium metabisulfite synthesis system is a three-stage reactor (three stainless steel reactors connected in series). The alkali solution inlet of the sodium metabisulfite synthesis system 3 is connected to the alkali solution outlet of the alkali preparation system 1, and the gas inlet of the sodium metabisulfite synthesis system 3 is connected to the gas outlet of the first purification system 2, so as to synthesize sodium metabisulfite using the alkali solution prepared by the alkali preparation system and the purified sulfur-containing regeneration gas.

[0129] The tail gas treatment system 4 uses a tail gas absorption tower. The alkali liquid inlet of the tail gas treatment system 4 is connected to the alkali liquid outlet of the alkali preparation system 1, and the air inlet of the tail gas treatment system 4 is connected to the tail gas outlet of the sodium metabisulfite synthesis system 3. The tail gas discharged from the sodium metabisulfite synthesis system is purified by the alkali liquid prepared by the alkali preparation system. The tail gas outlet of the tail gas treatment system 4 is connected to the second purification system 7. The second purification system is a boiler for burning NO in the tail gas purified by the tail gas treatment system. x .

[0130] The separation and drying system 5 includes a centrifuge and a dryer connected in sequence, wherein the liquid inlet of the centrifuge is connected to the supersaturated solution outlet of the sodium metabisulfite synthesis system 3 for solid-liquid separation of the supersaturated solution; the solid outlet of the centrifuge is connected to the solid inlet of the dryer, and the dry gas inlet of the dryer is connected to the hot flue gas pipeline 12. The dry tail gas outlet of the dryer, the exhaust pipeline of the discharge port of the centrifuge, the overflow pipeline of the alkali preparation system, and the pit exhaust pipeline are all connected to the gas inlet of the cooling device 601 of the flue gas low-temperature adsorption purification and regeneration system 6.

[0131] The flue gas purification resource recovery method of this embodiment specifically includes the following steps:

[0132] 1) Flue gas enters the cooling device 601 of the flue gas low-temperature adsorption purification and regeneration system 6 and is cooled to below room temperature (eg -20°C) to form low-temperature flue gas.

[0133] 2) The low-temperature flue gas enters the low-temperature adsorption device 602 and is adsorbed and purified by the adsorbent at a temperature below room temperature (eg -20°C) to remove sulfur dioxide and nitrogen oxides, and the obtained clean flue gas is discharged.

[0134] 3) After the adsorbent in the low-temperature adsorption device 602 is saturated with adsorption, the saturated adsorbent is sent to the regeneration device 603 for heating and regeneration to obtain regenerated adsorbent and sulfur-containing regeneration gas. The regenerated adsorbent can be reused in the low-temperature adsorption device.

[0135] The composition of sulfur-containing regeneration gas is: SO2 28.67%, NO x 4.82%, N2 42.84%, CO2 4.52%, H2O19.08%, HCl 0.07% and dust, where "%" is the volume fraction. There is no other particulate matter other than dust in the composition and no metal ions such as iron, NO xThe NO content is 95%.

[0136] 4) The soda ash is sent to the fully automatic alkali preparation system, prepared into a 30 wt% alkali solution and sent to the sodium metabisulfite synthesis system 3.

[0137] 5) The sulfur-containing regenerated gas obtained in step 3) enters the first purification system and is washed with process water to obtain clean sulfur-rich gas (the sulfur-rich gas composition by volume is: SO2 28.69%, NO 4.82%, N2 42.87%, CO2 4.52%, H2O 19.1%). It then enters the sodium metabisulfite synthesis system 3 to react with soda ash to produce a supersaturated sodium bisulfite solution. The flow rate of the sulfur-rich gas is 2500 Nm 3 / h, the flow rate of alkali solution (30% wt) is 4m 3 / h, reaction time is 50min, and reaction temperature is 55-75℃.

[0138] 6) The supersaturated sodium bisulfite solution enters the separation and drying system 5, and is centrifuged and dried in the dryer with hot flue gas from the factory to obtain the finished product sodium bisulfite.

[0139] The hot flue gas conditions from the factory are: temperature 110℃~150℃, dust content <20mg / Nm 3 .

[0140] 7) The dry tail gas generated by separation and drying in step 6) is cooled to low-temperature flue gas below room temperature (eg, -20°C) and sent to the flue gas low-temperature adsorption purification regeneration system 6 for adsorbent purification.

[0141] The composition of dry tail gas is: dust ≤ 20mg / Nm 3 ; SO2≤2000mg / Nm 3 .

[0142] 8) The 70°C synthesis tail gas (composition of the synthesis tail gas by volume is: SO2 4%, NO 7%, N2 54%, CO2 8%, H2O 27%) generated by the reaction of the sulfur-containing regeneration gas and alkali solution discharged from the sodium metabisulfite synthesis system 3 enters the tail gas treatment system. After being absorbed by the absorption liquid alkali solution, the SO2 concentration of the tail gas is reduced to 3000 mg / Nm 3 The reaction tail gas is sent to the factory boiler for recycling combustion treatment.

[0143] 5) The dry tail gas is collected from the alkali solution overflow, centrifuge discharge port exhaust, pit exhaust, etc. and then sent to the flue gas low-temperature adsorption purification regeneration system 6, cooled to low-temperature flue gas below room temperature (for example, -20°C) in the cooling device 601, and then enters the low-temperature adsorption device 602 for adsorption purification.

[0144] Testing has shown that using hot flue gas instead of steam as the drying gas heat source can save steam consumption: With a designed sodium metabisulfite production capacity of no less than 3.1 tons / hour, this translates to an annual production capacity of 24,800 tons / year (based on 8,000 hours of annual utilization), and an actual production capacity of 10,900 tons / year (based on 3,514 hours of actual annual utilization). Taking 200°C and 0.23 MPa(A) as an example, this saves 1.1 tons / hour of steam, equivalent to 3,865.4 tons per year.

[0145] Example 2 (the first purification system includes a first oxidation tower)

[0146] This embodiment differs from embodiment 1 in that:

[0147] like Figure 2 As shown, in the flue gas purification resource recovery system of this embodiment, the first purification system 2 includes a first oxidation tower 201 and a first ozone generator 202; the first ozone generator 202 has a first ozone outlet, which is connected to the first ozone inlet of the first oxidation tower 201; the first oxidation tower 201 is provided with a first gas inlet and a first gas outlet; the first gas inlet is connected to the sulfur-containing regeneration gas outlet of the regeneration device 603, and the first gas outlet is connected to the gas inlet of the sodium metabisulfite synthesis system 3 to supply the purified sulfur-containing regeneration gas to the sodium metabisulfite synthesis system. The first ozone generator 202 also has a first air inlet, which is connected to the first air pipeline 203; the first oxidation tower 201 also has a first process water inlet and a first acid outlet, the first process water inlet is connected to the first process water pipeline 204, and the first acid outlet is connected to the plant water treatment system 205.

[0148] The flue gas purification resource recovery method of this embodiment includes:

[0149] In step 5), the sulfur-containing regeneration gas is purified by the first purification system as follows: air enters the first ozone generator to generate ozone, and then is fed into the first oxidation tower; in the first oxidation tower, the ozone and the sulfur-containing regeneration gas react at room temperature (20-30° C.), first process water is fed into the first oxidation tower, particulate matter and gases such as HCl are removed in the first oxidation tower, and NO is oxidized to NO2 by O3, and NO2 is sprayed and absorbed by the first process water to obtain clean sulfur-rich gas (the sulfur-rich gas composition, by volume, is: SO2 32%, N2 45%, CO2 4%, H2O 19%).

[0150] In step 8), the composition of the synthetic tail gas is, by volume fraction, SO2 11%, N2 54%, CO2 8%, and H2O 27%.

[0151] Example 3 (Recycling of Nitrogen Resources in Tail Gas)

[0152] This embodiment differs from embodiment 1 in that:

[0153] like Figure 3 As shown, in the flue gas purification resource recovery system of this embodiment, the second purification system 7 includes a second oxidation tower 701 and a second ozone generator 702; the second ozone generator 702 has a second air inlet and a second ozone outlet, the second air inlet is connected to the second air pipeline 704, and the second ozone outlet is connected to the second ozone inlet of the second oxidation tower 701; the second oxidation tower 701 is also provided with a second gas inlet, a second process water inlet and a second acid liquid outlet; the second gas inlet is connected to the tail gas outlet of the tail gas treatment system 4, the second process water inlet is connected to the second process water pipeline 703, and the second acid liquid outlet is connected to the nitrogen recovery system 8, which can prepare nitric acid or ammonium nitrate from NO2 for recycling.

[0154] The flue gas purification resource recovery method of this embodiment includes:

[0155] Step 8) is modified as follows: The reaction exhaust gas discharged from the exhaust gas treatment system is fed into a second oxidation tower 701. The second oxidation tower 701 uses ozone to oxidize NO in the exhaust gas discharged from the exhaust gas treatment system into NO2. The NO2 is sprayed with the second process water to form nitric acid, which is then collected in the nitrogen recovery system 8 or reacted with liquid ammonia to produce ammonium nitrate.

[0156] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0157] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0158] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0159] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0160] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0161] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A flue gas purification resource recovery system, characterized in that: include: A flue gas low-temperature adsorption purification and regeneration system, comprising a cooling device for cooling the flue gas to low-temperature flue gas below room temperature, a low-temperature adsorption device for purifying the low-temperature flue gas into clean flue gas through adsorption by an adsorbent, and a regeneration device for regenerating the adsorbent that has been saturated with adsorption and generating sulfur-containing regeneration gas; an alkali preparation system, the alkali preparation system being used to prepare soda ash into alkali liquor; a first purification system, the first purification system being connected to the regeneration device and being used to purify the sulfur-containing regeneration gas discharged from the regeneration device; a sodium metabisulfite synthesis system, connected to the alkali preparation system and the first purification system, for synthesizing sodium metabisulfite using the alkali solution prepared by the alkali preparation system and the purified sulfur-containing regeneration gas; An exhaust gas treatment system, connected to the alkali preparation system and the sodium metabisulfite synthesis system, for purifying the synthesis exhaust gas discharged from the sodium metabisulfite synthesis system using the alkali solution prepared by the alkali preparation system; A separation and drying system having a liquid inlet, a drying gas inlet, and a drying tail gas outlet, wherein the liquid inlet is connected to the sodium metabisulfite synthesis system, the drying gas inlet is connected to a hot flue gas pipeline, and the drying tail gas outlet is connected to a cooling device of the flue gas low-temperature adsorption purification and regeneration system. The separation and drying system is used to utilize the hot flue gas supplied by the hot flue gas pipeline to dry the supersaturated solution discharged from the sodium metabisulfite synthesis system to obtain a finished sodium metabisulfite product, and the dried tail gas is sent to the flue gas low-temperature adsorption purification and regeneration system for adsorption purification treatment.

2. The flue gas purification resource recovery system according to claim 1, characterized in that: The sulfur-containing regeneration gas includes the following components: SO2 28-30% by volume, NO x 4.7-5.1% by volume, N242-44% by volume, CO24-6% by volume, H2O 19-21% by volume, HCl 0.05~0.1% by volume and dust.

3. The flue gas purification resource recovery system according to claim 1, characterized in that: The slurry outlet of the separation and drying system is connected to the alkali preparation system to return the slurry discharged from the separation and drying system to the alkali preparation system for preparing alkali solution; And / or, the first purification system is a spray washing tower.

4. The flue gas purification resource recovery system according to claim 1, characterized in that: The first purification system includes a first oxidation tower and a first ozone generator; the first ozone generator has a first ozone outlet, and the first oxidation tower has a first ozone inlet, a first gas inlet, a first gas outlet, a first process water inlet and a first acid liquid outlet; the first ozone inlet is connected to the first ozone outlet, the first gas inlet is connected to the sulfur-containing regeneration gas outlet of the regeneration device, the first gas outlet is connected to the sodium metabisulfite synthesis system to supply the purified sulfur-containing regeneration gas to the sodium metabisulfite synthesis system, the first process water inlet is connected to the first process water pipeline, and the first acid liquid outlet is connected to the plant water treatment system.

5. The flue gas purification resource recovery system according to any one of claims 1 to 3, characterized in that: It also includes a second purification system and a nitrogen recovery system; the second purification system includes a second oxidation tower and a second ozone generator; the second ozone generator has a second ozone outlet, and the second oxidation tower has a second ozone inlet, a second gas inlet, a second process water inlet and a second acid liquid outlet; the second ozone inlet is connected to the second ozone outlet, the second gas inlet is connected to the exhaust gas outlet of the exhaust treatment system, the second process water inlet is connected to the second process water pipeline, and the second acid liquid outlet is connected to the nitrogen recovery system.

6. The flue gas purification resource recovery system according to any one of claims 1 to 4, characterized in that: The second purification system also includes an air inlet connected to the tail gas outlet of the tail gas treatment system; the second purification system is a boiler for burning NO in the tail gas purified by the tail gas treatment system. x .

7. The flue gas purification resource recovery system according to claim 1, characterized in that: The tail gas treatment system is a tail gas absorption tower; And / or, the sodium metabisulfite synthesis system is a sodium metabisulfite synthesis multi-stage reactor; And / or, the separation and drying system includes a centrifuge and a dryer connected in sequence, the liquid inlet of the centrifuge is connected to the supersaturated solution outlet of the sodium metabisulfite synthesis system, the solid outlet of the centrifuge is connected to the solid inlet of the dryer, the discharge port exhaust pipeline of the centrifuge, the overflow pipeline of the alkali preparation system, the pit exhaust pipeline, and the dry tail gas outlet of the dryer are all connected to the flue gas low-temperature adsorption purification and regeneration system, and the dry gas inlet of the dryer is connected to the hot flue gas pipeline.

8. A flue gas purification resource recovery method, characterized in that: The flue gas purification resource recovery method is performed using the flue gas purification resource recovery system according to any one of claims 1 to 7, comprising: Cooling the flue gas to low-temperature flue gas below room temperature; Adsorbing and purifying the low-temperature flue gas into clean flue gas by using an adsorbent; regenerating the adsorbent saturated with adsorption to obtain regenerated adsorbent and sulfur-containing regeneration gas; The purified sulfur-containing regeneration gas is reacted with the prepared alkali solution to obtain a supersaturated sodium bisulfite solution; The supersaturated sodium bisulfite solution is sequentially subjected to solid-liquid separation and hot flue gas drying to obtain a sodium metabisulfite product; Cooling the dry tail gas generated by the drying to low-temperature flue gas below room temperature for adsorbent purification; The synthetic tail gas generated by the reaction of the sulfur-containing regeneration gas and the alkali solution is subjected to alkali solution purification treatment.

9. The flue gas purification resource recovery method according to claim 8, characterized in that: The sulfur-containing regeneration gas includes the following components: SO2 28-30% by volume, NO x 4.7-5.1% by volume, N242-44% by volume, CO24-6% by volume, H2O 19-21% by volume, HCl 0.05-0.1% by volume and dust; and / or, the purification method of the sulfur-containing regeneration gas is: the sulfur-containing regeneration gas reacts with ozone in a first oxidation tower to convert nitrogen monoxide into nitrogen dioxide, which is then absorbed by water; and / or, sending the synthetic tail gas after the alkali solution purification treatment into a boiler for recycling and combustion treatment; And / or, the overflow gas and pit exhaust gas from the alkali solution are cooled to low-temperature flue gas and then subjected to adsorption purification.

10. The flue gas purification resource recovery method according to claim 8, characterized in that: The purification method of the sulfur-containing regenerated gas is as follows: the sulfur-containing regenerated gas is sprayed and washed with process water in a spray washing tower; and / or, sending the tail gas discharged from the tail gas treatment system into a second oxidation tower to convert nitrogen monoxide into nitrogen dioxide under the action of ozone; Nitrogen dioxide is reacted with water to form nitric acid, or nitrogen dioxide is reacted with water and liquid ammonia to form ammonium nitrate.

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