A zero-discharge system for recycling desulfurization wastewater

Abstract

The invention discloses a zero-discharge system for resource utilization of desulfurized wastewater, which mainly includes a desulfurization treatment device, a high-pressure centrifugal cyclone, a raw water regulating tank, an electric flocculation device, a high-efficiency clarification softener, a membrane filter, a high-pressure ozone device, a high-pressure ultraviolet device, a single-head encapsulated hollow ultrafiltration, a security filter, an NF device, a magnesium sulfate concentration device, a magnesium sulfate crystallizer, a freezing separator, a purification device, a sodium bed, a primary RO device, a HIRO device, an electrolysis device, a sodium chloride crystallizer, a flue evaporation crystallization device, a secondary RO device, a high-efficiency adsorbent dosing device, a sodium hydroxide dosing device, a calcium hydroxide dosing device, a sodium sulfate dosing device, a coagulant dosing device, a pH meter, a Ca online monitor, a Mg online monitor, an online COD meter, and a sludge dehydration device. This system can reduce the amount of dosing, and at the same time reduce the amount of sludge produced in the water, generate industrial-grade magnesium sulfate and sodium chloride byproducts, and solve the problems currently encountered in thermal power plants.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection of desulfurization wastewater treatment in thermal power plants, and in particular to a zero-discharge system for resource utilization of desulfurization wastewater. Background Art

[0002] Water is an indispensable resource in the industrial field, and the discharge of concentrated brine is an important environmental indicator. The key problem of zero discharge in the field of industrial wastewater in my country, especially in thermal power plants, is that the operating cost and investment cost of desulfurization wastewater are too high, and there is a lack of stable operation experience. We are now exploring how to experiment to find more stable treatment methods and technologies with lower operating costs.

[0003] In order to maintain stable operation under normal operating conditions, the desulfurization system continuously discharges desulfurization wastewater. Some desulfurization wastewater has a Mg content of more than 2000 mg. During the softening process, the traditional method requires the precipitation of Mg to generate Mg(OH)2, which not only requires the addition of a large amount of OH roots, but also generates a large amount of sludge, increasing the system operation and maintenance costs.

[0004] Therefore, it is necessary to develop a system that can reduce the amount of chemicals added to desulfurization wastewater, reduce sludge discharge, and recycle the by-products. Summary of the invention

[0005] The present invention overcomes the shortcomings of the prior art and provides a zero-discharge system for recycling desulfurization wastewater.

[0006] In view of the above problems in the prior art, according to one aspect of the present invention, in order to solve the above technical problems, the present invention adopts a zero-emission system for resource utilization of desulfurization wastewater, which mainly includes a desulfurization treatment device, a high-pressure centrifugal cyclone, a raw water regulating tank, an electric flocculation device, a high-efficiency clarifier softener, a membrane filter, a high-pressure ozone device, a high-pressure ultraviolet device, a single-head encapsulated hollow ultrafiltration, a security filter, an NF device, a magnesium sulfate concentration device, a magnesium sulfate crystallizer, a freezing separator, a purification device, a sodium bed, a primary RO device, a HIRO device, an electrolysis device, a sodium chloride crystallizer, a flue evaporation crystallization device, a secondary RO device, a high-efficiency adsorbent dosing device, a sodium hydroxide dosing device, a calcium hydroxide dosing device, a sodium sulfate dosing device, a coagulant dosing device, a pH meter, a Ca online monitor, a Mg online monitor, an online COD meter, and a sludge dewatering device.

[0007] Compared with the prior art, the advantages of the present invention are:

[0008] (1) Add high-efficiency composite inorganic adsorbent to obtain the original organic sulfur, flocculant, and coagulant aid, reducing the dosage;

[0009] (2) Equipped with high-pressure ozone device and high-pressure ultraviolet device to effectively reduce COD;

[0010] (3) Mg ions eventually form magnesium sulfate heptahydrate, which reduces the dosage of precipitated magnesium ions and reduces the amount of sludge;

[0011] (4) The sodium bed is regenerated to utilize the concentrated water of the HIRO device, saving reagents and part of the wastewater investment and operation treatment costs;

[0012] (5) The concentrated water produced by the HIRO device enters the electrolysis device and the sodium chloride crystallizer, and the by-products produced are comprehensively utilized;

[0013] (6) The mother liquor of the evaporation crystallizer is discharged into the flue evaporation crystallization device to achieve true zero emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present application document or the technical solutions in the prior art, the drawings required for use in the description of the embodiments or the prior art are briefly introduced below. Obviously, the drawings described below are only references to some embodiments in the present application document. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, and some parts of them can also be adjusted for use.

[0015] Figure 1 The present invention shows a schematic diagram of a zero-emission system for resource utilization of desulfurization wastewater according to an embodiment of the present invention. In the figure, (101) a desulfurization treatment device, (102) a high-pressure centrifugal cyclone, (103) an electroflocculation device, (104) a high-efficiency clarification softener, (105) a membrane filter, (106) a high-pressure ozone device, (107) a high-pressure ultraviolet device, (108) a single-head encapsulated hollow ultrafiltration, (109) a security filter, (110) a NF device, (111) a magnesium sulfate concentration device, (112) a magnesium sulfate crystallizer, (113) a refrigeration separator, (114) Pure device, (115) sodium bed, (116) primary RO device, (117) HIRO device, (118) electrolysis device, (119) sodium chloride crystallizer, (120) flue evaporation crystallization device, (121) secondary RO device, (122) coagulant dosing device, (123) sodium hydroxide dosing device, (124) calcium hydroxide dosing device, (125) high-efficiency adsorbent dosing device, (126) sodium sulfate dosing device, (127) sludge dewatering device. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0017] Figure 1A zero-emission system for recycling desulfurization wastewater according to an embodiment of the present invention is shown, comprising (101) a desulfurization treatment device, (102) a high-pressure centrifugal cyclone, (103) an electrocoagulation device, (104) a high-efficiency clarifier and softener, (105) a membrane filter, (106) a high-pressure ozone device, (107) a high-pressure ultraviolet device, (108) a single-head encapsulated hollow ultrafiltration, (109) a security filter, (110) a NF device, (111) a magnesium sulfate concentration device, (112) a magnesium sulfate crystallizer, (113) a magnesium sulfate crystallizer, and (114) a magnesium sulfate crystallizer. 3) Refrigeration separator, (114) Purification device, (115) Sodium bed, (116) Primary RO device, (117) HIRO device, (118) Electrolysis device, (119) Sodium chloride crystallizer, (120) Flue gas evaporation crystallization device, (121) Secondary RO device, (122) Coagulant dosing device, (123) Sodium hydroxide dosing device, (124) Calcium hydroxide dosing device, (125) High-efficiency adsorbent dosing device, (126) Sodium sulfate dosing device, (127) Sludge dewatering device.

[0018] In order to realize the resource utilization of desulfurization wastewater, this system is divided into five steps to achieve it, connecting each device in the system through pipes and pumps.

[0019] (1) The wastewater produced by the desulfurization treatment device (101) enters the high-pressure centrifugal cyclone (102) from the bottom through a high-pressure pump. A coagulant dosing port is provided in front of the high-pressure centrifugal cyclone (102), which is connected to the coagulant dosing device (122). Then, the wastewater is distributed by the cyclone in the central cylinder. A clean water port is provided at the top, which is connected to the raw water regulating tank through a pipeline. A waste liquid port is provided at the bottom, which is connected to the vacuum belt conveyor in the desulfurization treatment device (101) through a pipeline, and enters the end of the vacuum belt conveyor;

[0020] (2) The raw water regulating tank is connected to the (103) electric flocculation device through a pipeline by a water pump. The (103) electric flocculation device is equipped with a DC power supply. The (103) electric flocculation device is connected to the (104) high-efficiency clarification and softening device through a pipeline. The (104) high-efficiency clarification and softening device consists of two front mixing tanks, a flocculation tank, and a high-efficiency clarification device. The front mixing tank is equipped with a pipeline mixer before entering the front pipeline. The pipeline mixer is connected to the (123) sodium hydroxide dosing device and the (124) calcium hydroxide dosing device. After the treatment, a pH meter is installed. The second front mixing tank is connected to the (126) sodium sulfate dosing device. The device is connected to the (125) high-efficiency adsorbent dosing device, the outlet water is provided with a Ca online monitor and a Mg online monitor, a fast mixer is provided in the front mixing tank, a lifting mixer is provided in the flocculation tank, a guide tube is provided in the middle, the flocculation tank is connected to the (125) high-efficiency adsorbent dosing device, the outlet water of the flocculation tank enters the high-efficiency clarifier, the water inlet pipe enters the guide tube of the high-efficiency clarifier at the top tangent, the guide tube is provided with a variable spacing and variable angle blade type swirl cloth, the high-efficiency clarifier is provided with a two-layer inclined pipe device, the bottom is a cone bucket, and it is connected to the (127) sludge dewatering device through a sludge pump;

[0021] (3) (105) The membrane filter is composed of an automatic control system, a flexible valve group, a membrane filter assembly, and a tank pipe. The membrane filter passes through a pipeline (106) and a high-pressure ozone device (107) and a high-pressure ultraviolet device, and is connected to a (108) single-head encapsulated hollow ultrafiltration through a pump. The (108) single-head encapsulated hollow ultrafiltration mainly uses a PVDF membrane wire with a reinforcing rib, and one end of the membrane wire is encapsulated;

[0022] (4) (108) the single-head encapsulated hollow ultrafiltration is connected to (109) the security filter and (110) the NF device through a pipeline and a pump. The (110) NF device is a one-stage two-stage device. The concentrate outlet of the (110) NF device is connected to the (111) magnesium sulfate concentration device. The water outlet of the (111) magnesium sulfate concentration device is connected to the (121) secondary RO device. The concentrate outlet of the (111) magnesium sulfate concentration device is connected to the (112) magnesium sulfate crystallizer. The (112) magnesium sulfate crystallizer is composed of an OSLO crystallizer, a (113) freezing separator, a circulation pump, a thickener, a mother liquor tank and a process pump. The magnesium sulfate finally formed is purified by the (114) purification device. The mother liquor tank of the (112) magnesium sulfate crystallizer is connected to the (120) flue evaporation crystallization device.

[0023] (5) There are two types of flue evaporation crystallization devices (120), one is flue direct injection and the other is flue bypass; the mother liquor discharged from the (112) magnesium sulfate crystallizer and the (119) sodium chloride crystallizer enters the flue evaporation crystallization device (120), and a gas-liquid bidirectional flow nozzle is used for circular tangential air intake;

[0024] (6) An online COD meter is provided before the (110) NF device. The produced water of the (110) NF device is connected to the (115) sodium bed. The produced water of the (115) sodium bed is connected to the (116) primary RO device. The concentrated water of the (116) primary RO device is connected to the (117) HIRO device. The produced water outlet of the (116) primary RO device and the produced water outlet of the (117) HIRO device are connected to the (121) secondary RO device. The concentrated water of the (121) secondary RO device is connected to the (116) primary RO device. The concentrated water of the (117) HIRO device is connected to the (118) electrolysis device, the (119) sodium chloride crystallizer and the (115) sodium bed. The mother liquor of the (119) sodium chloride crystallizer is discharged to the (120) flue evaporation crystallization device. The temperature of the (120) flue evaporation crystallization device is 350 degrees and the pressure is 500KPA.

[0025] (7) Antiscalant is added before (110) NF device, (116) primary RO device and (117) HIRO device. The pressure of (116) primary RO device is PN4.0Mpa~PN6.4Mpa, and high pressure anti-fouling membrane is used. The flow channel is 45mil. The pressure of (117) HIRO device is PN16Mpa, and a roll-type high pressure wide flow channel anti-fouling membrane is used. The flow channel is 50mil and the material is PVDF.

[0026] (8) Each device is connected through pipes and pumps. The pipes are made of UPVC and the water pumps are made of anti-corrosion materials.

[0027] In order to ensure the long-term stable operation of this process system and achieve completely zero emissions while utilizing the products, related supporting cleaning devices, dosing devices, electrical systems and instrument control are also involved in the operation of this desulfurization wastewater resource utilization zero emission system.

[0028] The "one embodiment" and "embodiment" mentioned in this specification refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when a specific feature, structure or characteristic is described in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of the present invention.

[0029] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise many other modifications and implementations that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure, drawings, and claims, a variety of variations and improvements may be made to the components and / or layout of the subject combination layout. In addition to variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A zero-discharge system for recycling desulfurization wastewater, characterized in that: Including desulfurization treatment device, high-pressure centrifugal cyclone, raw water regulating tank, electric flocculation device, high-efficiency clarification softener, membrane filter, high-pressure ozone device, high-pressure ultraviolet device, single-head encapsulated hollow ultrafiltration, security filter, NF device, magnesium sulfate concentration device, magnesium sulfate crystallizer, freezing separator, purification device, sodium bed, primary RO device, HIRO device, electrolysis device, sodium chloride crystallizer, flue evaporation crystallization device, secondary RO device, high-efficiency adsorbent dosing device, sodium hydroxide dosing device, calcium hydroxide dosing device, sodium sulfate dosing device, coagulant dosing device, pH meter, Ca online monitor, Mg online monitor, online COD meter, sludge dehydration device; The high-efficiency clarifier and softener consists of two front mixing tanks, a flocculation tank, and a high-efficiency clarifier. A pipeline mixer is provided in the front pipeline entering the front mixing tank. The pipeline mixer is connected to the sodium hydroxide dosing device and the calcium hydroxide dosing device. A pH meter is provided after treatment. The second front mixing tank is connected to the sodium sulfate dosing device and the high-efficiency adsorbent dosing device. The effluent is provided with a Ca online monitor and an Mg online monitor. A fast mixer is provided in the front mixing tank, a lifting mixer is provided in the flocculation tank, and a guide tube is provided in the middle. The flocculation tank is connected to the high-efficiency adsorbent dosing device. The effluent from the flocculation tank enters the high-efficiency clarifier. The water inlet pipe is a guide tube that enters the high-efficiency clarifier at the top tangent. The guide tube is provided with a variable spacing and variable angle blade-type swirl cloth. The high-efficiency clarifier is provided with a two-layer inclined pipe device and a cone bucket at the bottom, which is connected to the sludge dewatering device through a sludge pump; the high-efficiency clarifier is connected to a membrane filter; The membrane filter passes through the high-pressure ozone device and the high-pressure ultraviolet device through the pipeline, and is connected to the single-head encapsulated hollow ultrafiltration through a pump. The single-head encapsulated hollow ultrafiltration adopts PVDF membrane wire with reinforced ribs, and one end of the membrane wire is encapsulated; The single-head encapsulated hollow ultrafiltration is connected to the security filter and the NF device through pipelines and pumps. The NF device is a one-stage two-stage device. The concentrated water outlet of the NF device is connected to the magnesium sulfate concentration device, the water outlet of the magnesium sulfate concentration device is connected to the secondary RO device, the concentrated water outlet of the magnesium sulfate concentration device is connected to the magnesium sulfate crystallizer, and the mother liquor tank of the magnesium sulfate crystallizer is connected to the flue evaporation crystallization device; An online COD meter is installed in front of the NF device. The produced water of the NF device is connected to the sodium bed, the produced water of the sodium bed is connected to the primary RO device, the concentrated water of the primary RO device is connected to the HIRO device, the primary RO device and the HIRO device are connected to the secondary RO device, the concentrated water of the secondary RO device is connected to the primary RO device, the concentrated water of the HIRO device is connected to the electrolysis device, the sodium chloride crystallizer and the sodium bed, and the mother liquor of the sodium chloride crystallizer is discharged to the flue evaporation crystallization device; The wastewater produced by the desulfurization treatment device enters the high-pressure centrifugal cyclone from the bottom through a high-pressure pump. A coagulant dosing port is provided in front of the high-pressure centrifugal cyclone, and then the wastewater is distributed in the central cylinder. A clean water port is provided at the top, which is connected to the raw water regulating tank through a pipeline. A waste liquid port is provided at the bottom, which is connected to the vacuum belt conveyor in the desulfurization treatment device through a pipeline and enters the end of the vacuum belt conveyor. The raw water regulating tank is connected to the electric flocculation device by a water pump through a pipeline. The electric flocculation device is equipped with a DC power supply. The electric flocculation device is connected to the high-efficiency clarification and softening device through a pipeline. The membrane filter is composed of an automatic control system, a flexible valve group, a membrane filtration component, and tank piping.

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