Desulfurization wastewater treatment system for coal-fired power plant

Abstract

A desulfurization wastewater treatment system for a coal-fired power plant belongs to the technical field of wastewater treatment. The problems that an organic ultrafiltration or microfiltration membrane of an existing treatment system is prone to blockage and short in service life are solved. The adjusting tank is connected with the softening and clarifying module, the softening and clarifying module is connected with the multi-medium filter, the multi-medium filter is connected with the gas-liquid mixer, the ozone generator is connected with the gas-liquid mixer, the gas-liquid mixer is connected with the water inlet tank of the ceramic membrane filter, and the water inlet tank of the ceramic membrane filter is connected with a second water inlet of the adjusting tank; the ceramic membrane filter water inlet tank is connected with the ceramic membrane filter, the ceramic membrane filter is connected with the resin tank, the resin tank is connected with the nanofiltration device, the nanofiltration device is connected with the reverse osmosis device, the nanofiltration device is respectively connected with the third water inlet of the regulating reservoir and the carnallite treatment module, and the reverse osmosis device is connected with the pure salt treatment module. According to the utility model, the problems that the organic ultrafiltration or microfiltration membrane is easy to block, large in occupied area, unstable in membrane system operation and short in service life can be solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of wastewater treatment, in particular to a desulfurization wastewater treatment system for a coal-fired power plant. Background Art

[0002] In limestone-gypsum wet flue gas desulfurization (FGD) technology, to control the Cl ion concentration in the desulfurization slurry, a portion of the overflow from the gypsum hydrocyclone station, known as desulfurization wastewater, must be regularly discharged. However, this wastewater contains large amounts of dissolved salts, suspended solids, and small amounts of harmful pollutants such as fluoride and heavy metal ions, making it unsuitable for discharge. Conventional chemical treatment methods have limited effectiveness in achieving acceptable standards. Furthermore, due to environmental constraints, even if harmful substances are purified, the high neutral salt content makes it difficult to recycle and cannot be discharged. The most comprehensive treatment method currently available is solidification. Current solidification treatment for desulfurization wastewater primarily involves solar evaporation or heating, which volatilizes the wastewater into the atmosphere. Salts, suspended solids, and small amounts of harmful pollutants such as fluoride and heavy metal ions are then fixed and collected. Currently, evaporation technology is an effective means of achieving zero discharge of desulfurization wastewater. However, direct evaporation requires a large amount of water, consumes significant steam and electricity, and generates high investment and operating costs. It also generates large amounts of salty solid waste. Nanofiltration and reverse osmosis membrane separation methods can separate inorganic salts from wastewater, concentrate and reduce wastewater volume, and reuse produced water, but they place high demands on influent quality. Therefore, a zero-emission desulfurization wastewater treatment route typically includes pretreatment, nanofiltration, reverse osmosis, and evaporation and crystallization. In the pretreatment unit, traditional processes typically utilize a dual-alkali chemical softening method and organic ultrafiltration membranes. However, practical applications present challenges such as large solid waste disposal volumes, extensive land requirements, and the susceptibility of organic ultrafiltration membranes to fouling and short lifespans.

[0003] The invention patent with the authorization publication number CN105712559B provides a desulfurization wastewater membrane treatment system, including a raw water tank, a pre-sedimentation tank, a first reaction tank, an intermediate water tank, a second reaction tank, a concentration tank, a tubular microfiltration membrane device, a tubular membrane water production tank, an ultra-high pressure reverse osmosis device, an evaporator and a drying device connected in sequence by pipelines; the tubular membrane device is connected to the concentration tank through a reflux pipeline, and the concentrated water outlet of the ultra-high pressure device is connected to the evaporator inlet. This invention patent adopts a softening coupled tubular membrane treatment process, lacks an organic matter degradation treatment unit, and causes the tubular membrane filtration device to be easily clogged. In addition, the tubular membrane has a poor ability to retain organic matter. Organic matter penetrates the tubular membrane into the nanofiltration salt separation device, which will cause contamination of the nanofiltration membrane, affect the salt separation characteristics of the nanofiltration membrane, and shorten its service life. Based on this, a zero-emission treatment system for desulfurization wastewater is provided to solve the above technical problems. Utility Model Content

[0004] The utility model aims to provide a desulfurization wastewater treatment system for a coal-fired power plant, which is used to solve the problems of easy clogging and short service life of organic ultrafiltration or microfiltration membranes in existing treatment systems.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a desulfurization wastewater treatment system for a coal-fired power plant, comprising a regulating tank, a softening and clarifying module, a multi-media filter, a gas-liquid mixer, an ozone generator, a ceramic membrane filter water inlet box, a ceramic membrane filter, a resin tank, a nanofiltration device, a reverse osmosis device, a pure salt treatment module and a miscellaneous salt treatment module, the desulfurization wastewater enters the regulating tank through the first water inlet of the regulating tank, the outlet of the regulating tank is connected to the inlet of the softening and clarifying module, the outlet of the softening and clarifying module is connected to the inlet of the multi-media filter, the outlet of the multi-media filter is connected to the liquid inlet of the gas-liquid mixer, the odor of the ozone generator ... The oxygen outlet is connected to the gas inlet of the gas-liquid mixer, the outlet of the gas-liquid mixer is connected to the water inlet of the ceramic membrane filter water inlet box, the external discharge port of the ceramic membrane filter water inlet box is connected to the second water inlet of the regulating tank, the water outlet of the ceramic membrane filter water inlet box is connected to the water inlet of the ceramic membrane filter, the water production port of the ceramic membrane filter is connected to the inlet of the resin tank, the outlet of the resin tank is connected to the water inlet of the nanofiltration device, the water production port of the nanofiltration device is connected to the water inlet of the reverse osmosis device, the concentrate water inlet of the nanofiltration device is respectively connected to the third water inlet of the regulating tank and the water inlet of the mixed salt treatment module, and the concentrate water inlet of the reverse osmosis device is connected to the water inlet of the pure salt treatment module.

[0006] Furthermore, the softening and clarification module includes a primary granulation fluidized bed reactor, the carrier particles filled in the primary granulation fluidized bed reactor are one or more of quartz sand, calcite, garnet, gypsum, brucite, magnesite, limestone, and hydroxyapatite, and one or more of sodium carbonate and sodium hydroxide are added at the dosing port of the primary granulation fluidized bed reactor.

[0007] Furthermore, the softening and clarification module includes a two-stage granulation fluidized bed reactor, wherein the first-stage granulation fluidized bed reactor adds one or more of hydrochloric acid, sulfuric acid, sodium hydroxide, ferric chloride, and ferric sulfate; the second-stage granulation fluidized bed reactor adds one or two of sodium hydroxide and sodium carbonate; the first-stage granulation fluidized bed carrier filler is one or more of gypsum, quartz sand, and garnet, and the second-stage granulation fluidized bed carrier filler is one or more of brucite, magnesite, calcite, quartz sand, and garnet, and the water outlet of the softening and clarification module is provided with a pH online meter and an acid addition port.

[0008] Furthermore, a sludge hopper is provided at the bottom of the water inlet tank of the ceramic membrane filter, and the sludge hopper is provided with a sludge discharge outlet. The sludge discharged from the sludge discharge outlet is further dehydrated by a plate and frame filter press, and the filtrate discharged from the plate and frame filter press is returned to the water inlet tank of the ceramic membrane filter.

[0009] Furthermore, the ceramic membrane filter uses a ceramic membrane doped with iron-based or manganese-based oxide active components.

[0010] Furthermore, the resin tank includes at least one first-stage resin tank. When it is a first-stage resin tank, the resin tank is filled with weak acid macroporous resin. When it is a two-stage resin tank, the first-stage resin tank is filled with weak acid macroporous resin and the second-stage resin tank is filled with selective defluorination resin.

[0011] Furthermore, the nanofiltration device includes n sections, n≥2, and a nanofiltration separation and concentration device.

[0012] Furthermore, the reverse osmosis device includes i sections, i≥2, and a reverse osmosis separation and concentration device.

[0013] Furthermore, the pure salt disposal module is one or more of an evaporation crystallization device, a spray drying device, an electrolytic chlorine production device, and a bipolar membrane device.

[0014] Furthermore, the impurity salt disposal module is one or more of a dry ash mixing device, an evaporation crystallization device, and a spray drying device.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. This utility model utilizes a ceramic membrane doped with active iron or manganese oxide components. By adding ozone, strong oxidizing free radicals are generated on the membrane surface, effectively degrading organic matter in the wastewater and preventing it from clogging. The combination of a granulated fluidized bed, ozone, and specialized ceramic membranes addresses the issues of easy clogging of organic ultrafiltration or microfiltration membranes in existing treatment systems, large footprints, unstable membrane system operation, and short lifespans in conventional desulfurization wastewater treatment processes.

[0017] 2. The utility model adopts at least one stage of granulation fluidized bed device for softening treatment, thereby realizing resource utilization of inorganic salt components and reducing the floor space occupied by the softening device.

[0018] 3. The filter membrane of the utility model has a longer service life, lower energy consumption per ton of water, and lower operating costs. The softening treatment area is greatly reduced, and solid waste disposal is easier. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a work flow chart of the present utility model.

[0020] The names and reference numerals of the components in the above drawings are as follows:

[0021] 1. Equalization tank; 2. Softening and clarification module; 3. Multi-media filter; 4. Gas-liquid mixer; 5. Ozone generator; 6. Ceramic membrane filter water inlet tank; 7. Ceramic membrane filter; 8. Resin tank; 9. Nanofiltration device; 10. Reverse osmosis device; 11. Pure salt treatment module; 12. Miscellaneous salt treatment module. DETAILED DESCRIPTION

[0022] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] Specific implementation: Figure 1 As shown, this embodiment discloses a desulfurization wastewater treatment system for a coal-fired power plant, comprising a regulating tank 1, a softening and clarifying module 2, a multi-media filter 3, a gas-liquid mixer 4, an ozone generator 5, a ceramic membrane filter water inlet box 6, a ceramic membrane filter 7, a resin tank 8, a nanofiltration device 9, a reverse osmosis device 10, a pure salt disposal module 11 and a miscellaneous salt disposal module 12. The desulfurization wastewater enters the regulating tank 1 through the first water inlet of the regulating tank 1, the outlet of the regulating tank 1 is connected to the inlet of the softening and clarifying module 2, the outlet of the softening and clarifying module 2 is connected to the inlet of the multi-media filter 3, the outlet of the multi-media filter 3 is connected to the liquid inlet of the gas-liquid mixer 4, the ozone outlet of the ozone generator 5 is connected to the gas inlet, and the ozone outlet of the ozone generator 5 is connected to the gas inlet. The gas inlet of the liquid mixer 4 is connected, the outlet of the gas-liquid mixer 4 is connected to the water inlet of the ceramic membrane filter water inlet box 6, the external discharge port of the ceramic membrane filter water inlet box 6 is connected to the second water inlet of the regulating tank 1, the water outlet of the ceramic membrane filter water inlet box 6 is connected to the water inlet of the ceramic membrane filter 7, the water production port of the ceramic membrane filter 7 is connected to the inlet of the resin tank 8, the outlet of the resin tank 8 is connected to the water inlet of the nanofiltration device 9, the water production port of the nanofiltration device 9 is connected to the water inlet of the reverse osmosis device 10, the concentrated water port of the nanofiltration device 9 is respectively connected to the third water inlet of the regulating tank 1 and the water inlet of the mixed salt treatment module 12, and the concentrated water port of the reverse osmosis device 10 is connected to the water inlet of the pure salt treatment module 11.

[0024] Furthermore, the softening and clarification module 2 includes a first-stage granulation fluidized bed reactor, the first-stage granulation fluidized bed reactor has a total height greater than 6m, wherein the filler fluidization height is greater than 2.5m, and the filling carrier particles are one or more of quartz sand, calcite, garnet, gypsum, brucite, magnesite, limestone, and hydroxyapatite, and one or more of sodium carbonate and sodium hydroxide are added at the dosing port of the first-stage granulation fluidized bed reactor.

[0025] Furthermore, the softening and clarification module 2 includes a two-stage granulation fluidized bed reactor, wherein the first-stage granulation fluidized bed reactor adds one or more of hydrochloric acid, sulfuric acid, sodium hydroxide, ferric chloride, and ferric sulfate, and the effluent pH is controlled to be 6-8; the second-stage granulation fluidized bed reactor adds one or two of sodium hydroxide and sodium carbonate, and the effluent pH is controlled to be 10.5-11; the first-stage granulation fluidized bed carrier filler is one or more of gypsum, quartz sand, and garnet, and the second-stage granulation fluidized bed carrier filler is one or more of brucite, magnesite, calcite, quartz sand, and garnet. The outlet of the softening and clarification module 2 is provided with a pH online meter and an acid addition port for automatically adjusting the effluent pH.

[0026] Furthermore, a sludge hopper is provided at the bottom of the water inlet tank of the ceramic membrane filter 7, and the sludge hopper is provided with a sludge discharge outlet. The sludge discharged from the sludge discharge outlet is further dehydrated by a plate and frame filter press, and the filtrate discharged from the plate and frame filter press is returned to the water inlet tank 6 of the ceramic membrane filter.

[0027] Furthermore, the ceramic membrane filter 7 adopts a ceramic membrane doped with an active component of iron or manganese oxides, and the separation layer of the ceramic membrane filter element is doped with iron oxides and / or manganese oxides. The water production rate is greater than 95%, and the water production rate is controlled by the water discharge volume of the ceramic membrane filter water inlet tank 6.

[0028] Furthermore, the resin tank 8 includes at least one first-stage resin tank 8. When it is one-stage, the resin tank 8 is filled with weak acid macroporous resin. When it is two-stage, the first-stage resin tank 8 is filled with weak acid macroporous resin, and the second-stage resin tank 8 is filled with selective defluorination resin.

[0029] Furthermore, the nanofiltration device 9 includes n sections, n≥2, which are nanofiltration separation and concentration devices.

[0030] Furthermore, the reverse osmosis device 10 includes i sections, i≥2, and a reverse osmosis separation and concentration device, which improves the quality of produced water through a reflux mechanism.

[0031] Furthermore, the pure salt disposal module 11 is one or more of an evaporation crystallization device, a spray drying device, an electrolytic chlorine production device, and a bipolar membrane device.

[0032] Furthermore, the impurity salt disposal module 12 is one or more of a dry ash mixing device, an evaporation crystallization device, and a spray drying device.

[0033] The regulating tank 1 is used to regulate the water quality and quantity of the desulfurization wastewater, the softening and clarification module 2 is used to soften and clarify the wastewater, the multi-media filter 3 is used to further filter the wastewater, the ozone generator 5 and the gas-liquid mixer 4 are used to mix ozone with the wastewater, the ceramic membrane filter water inlet tank 6 is used to receive the mixed wastewater, and is provided with an external discharge port connected to the water inlet of the regulating tank 1 to regulate the water quality, and the ceramic membrane filter 7 is used to filter the wastewater through a ceramic membrane filter element doped with iron oxides and / or manganese oxides The resin tank 8 is used to further treat the produced water. The nanofiltration device 9 includes n-stage (n≥2) nanofiltration separation and concentration devices, wherein the nth stage is a high-pressure disc tube nanofiltration device. The reverse osmosis device 10 includes i-stage (i≥2) reverse osmosis separation and concentration devices. The reverse osmosis produced water from the 1st to i-1th stages is collected as the produced water of the device. The reverse osmosis produced water from the i-th stage is refluxed and mixed with the influent water of the i-1th stage reverse osmosis device. The pure salt disposal module 11 is used to treat the reverse osmosis concentrated water, and the miscellaneous salt disposal module 12 is used to treat the nanofiltration concentrated water.

[0034] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0035] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A desulfurization wastewater treatment system for a coal-fired power plant, characterized by: The system comprises a regulating tank (1), a softening and clarifying module (2), a multi-media filter (3), a gas-liquid mixer (4), an ozone generator (5), a ceramic membrane filter water inlet tank (6), a ceramic membrane filter (7), a resin tank (8), a nanofiltration device (9), a reverse osmosis device (10), a pure salt treatment module (11) and a miscellaneous salt treatment module (12), wherein the desulfurization wastewater enters the regulating tank (1) through the first water inlet of the regulating tank (1), the outlet of the regulating tank (1) is connected to the inlet of the softening and clarifying module (2), the outlet of the softening and clarifying module (2) is connected to the inlet of the multi-media filter (3), the outlet of the multi-media filter (3) is connected to the liquid inlet of the gas-liquid mixer (4), the ozone outlet of the ozone generator (5) is connected to the gas outlet of the gas-liquid mixer (4), and the ozone outlet of the ozone generator (5) is connected to the gas outlet of the gas-liquid mixer (4). The inlet of the gas-liquid mixer (4) is connected to the water inlet of the ceramic membrane filter water inlet box (6), the external discharge port of the ceramic membrane filter water inlet box (6) is connected to the second water inlet of the regulating tank (1), the water outlet of the ceramic membrane filter water inlet box (6) is connected to the water inlet of the ceramic membrane filter (7), the water production port of the ceramic membrane filter (7) is connected to the inlet of the resin tank (8), the outlet of the resin tank (8) is connected to the water inlet of the nanofiltration device (9), the water production port of the nanofiltration device (9) is connected to the water inlet of the reverse osmosis device (10), the concentrated water port of the nanofiltration device (9) is respectively connected to the third water inlet of the regulating tank (1) and the water inlet of the mixed salt treatment module (12), and the concentrated water port of the reverse osmosis device (10) is connected to the water inlet of the pure salt treatment module (11).

2. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 1, characterized in that: The softening and clarifying module (2) comprises a first-stage granulation fluidized bed reactor, wherein the carrier particles filled in the first-stage granulation fluidized bed reactor are one of quartz sand, calcite, garnet, gypsum, brucite, magnesite, limestone, and hydroxyapatite, and one of sodium carbonate and sodium hydroxide is added to the dosing port of the first-stage granulation fluidized bed reactor.

3. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 1, characterized in that: The softening and clarifying module (2) comprises a two-stage granulation fluidized bed reactor, wherein the first-stage granulation fluidized bed reactor is fed with one of hydrochloric acid, sulfuric acid, sodium hydroxide, ferric chloride, and ferric sulfate; the second-stage granulation fluidized bed reactor is fed with one of sodium hydroxide and sodium carbonate; the carrier filler of the first-stage granulation fluidized bed is one of gypsum, quartz sand, and garnet, and the carrier filler of the second-stage granulation fluidized bed is one of brucite, magnesite, calcite, quartz sand, and garnet; the water outlet of the softening and clarifying module (2) is provided with a pH online meter and an acid addition port.

4. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 2 or 3, characterized in that: A sludge hopper is provided at the bottom of the water inlet tank of the ceramic membrane filter (7), and the sludge hopper is provided with a sludge discharge outlet. The sludge discharged from the sludge discharge outlet is further dehydrated by a plate and frame filter press, and the filtrate discharged from the plate and frame filter press is returned to the water inlet tank (6) of the ceramic membrane filter.

5. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 4, characterized in that: The resin tank (8) comprises at least one first-stage resin tank (8). When the resin tank is in the first stage, the resin tank (8) is filled with a weak acid macroporous resin. When the resin tank is in the second stage, the first-stage resin tank (8) is filled with a weak acid macroporous resin, and the second-stage resin tank (8) is filled with a selective defluorination resin.

6. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 5, characterized in that: The nanofiltration device (9) comprises n sections, n≥2, of a nanofiltration separation and concentration device.

7. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 6, characterized in that: The reverse osmosis device (10) comprises i sections, i≥2, and a reverse osmosis separation and concentration device.

8. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 7, characterized in that: The pure salt disposal module (11) is one or more of an evaporation crystallization device, a spray drying device, an electrolytic chlorine production device, and a bipolar membrane device.

9. The desulfurization wastewater treatment system for a coal-fired power plant according to claim 8, characterized in that: The miscellaneous salt disposal module (12) is one or more of a dry ash mixing device, an evaporation crystallization device, and a spray drying device.

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