CN111039492A - Low-cost zero-discharge desulfurization wastewater treatment system and method - Google Patents
Low-cost zero-discharge desulfurization wastewater treatment system and method Download PDFInfo
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Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/73—After-treatment of removed components
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/16—Treatment of water, waste water, or sewage by heating by distillation or evaporation using waste heat from other processes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/10—Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS]
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Organic Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Hydrology & Water Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
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- Treating Waste Gases (AREA)
Abstract
The invention provides a low-cost zero-discharge desulfurization wastewater treatment system and a method, wherein the system comprises: the system comprises a desulfurization wastewater pretreatment subsystem and a zero-discharge treatment subsystem, wherein the desulfurization wastewater pretreatment subsystem is used for pretreating desulfurization wastewater discharged from a desulfurization absorption tower, removing suspended matters, COD (chemical oxygen demand) and heavy metals, recovering gypsum to obtain pretreated wastewater, and the zero-discharge treatment subsystem is used for continuously evaporating and drying the pretreated wastewater to finally realize zero discharge; the desulfurization wastewater pretreatment subsystem comprises: gypsum cyclone, vacuum belt conveyor, filtrate vacuum tank, aeration tank, precipitator, first filter, product pond. This system no longer adopts traditional waste water swirler, and chooses for use gypsum swirler, vacuum belt feeder to ally oneself with and use to reach the effect of effectively getting rid of the suspended solid, preferentially adopts clarifier, non-membrane high accuracy filter, solves the problem solution that the suspended solid is difficult to get rid of in desulfurization waste water in the preliminary treatment stage, has promoted the stability of system's operation, effectively retrieves calcium sulfate simultaneously.
Description
Technical Field
The invention relates to the technical field of desulfurization wastewater treatment and environmental protection, in particular to a low-cost zero-discharge desulfurization wastewater treatment system and method.
Background
At present, the economy of China is developed at a high speed, and simultaneously, the environmental problem is increasingly serious along with the huge consumption of energy. In order to improve the current environmental situation, the national management of three wastes is getting tighter and tighter, and the zero discharge of industrial wastewater is a development trend, which is accepted by many enterprises and professionals, and gradually starts to be explored and implemented in the industrial field.
Water is an indispensable resource in the industrial field. The discharge of concentrated brine in industrial production is strictly regulated as an important environmental protection index, so that the realization of zero discharge of wastewater is an ideal target of environmental protection work. The problems of high operation cost and investment cost and lack of stable operation experience exist in the field of zero discharge in industrial wastewater in China, and how to find a more stable treatment method and a technical means with low operation cost through experiments are currently explored.
The desulfurization waste water is the waste water that is the most difficult to handle among all waste water of thermal power plant, and the impurity of this waste water comes from flue gas and desulfurized limestone, mainly includes suspended solid, supersaturated sulfite, sulfate and heavy metal, and wherein many are the first class pollutant that will control among the national environmental standard, because the particularity of quality of water, the desulfurization waste water treatment degree of difficulty is great, handles the water pollution serious that does not reach standard and cause. The treatment difficulty is specifically shown as follows: 1) the water quality and the water quantity are greatly influenced by the coal burning, the water replenishing of a desulfurization system and the desulfurization operation condition, and the water quality fluctuation range is large; 2) the concentration of suspended matters is high, the proportion of fine particles is large, and the membrane filtering device is easy to be polluted and blocked; 3) the concentration of silicon and magnesium is high, the supersaturation degree of calcium sulfate is high, the scaling tendency is strong, and the cleaning and recovery of a membrane system are difficult; 4) when the organic concentration is high, the operation performance of a membrane system is obviously influenced, membrane fouling and blocking are caused, and the like.
With the increasingly strict national environmental protection requirements, the national environmental protection department requires zero discharge of desulfurization wastewater. At present, common wastewater zero-discharge technical routes comprise a multi-effect evaporation concentration crystallization method, an MVR concentration crystallization method, a flue spray evaporation method and a hot flue gas drying evaporation tower wastewater treatment method; the existing desulfurization wastewater zero-discharge technology has extremely high investment cost and running cost (such as evaporative crystallization) or brings a great amount of side effects (such as flue injection, scaling and corrosion of a flue and an electric bag dust collector), and a new desulfurization wastewater zero-discharge solution is urgently needed to be found.
Therefore, it is necessary to develop a desulfurization wastewater treatment system and method that can reduce the dosage of desulfurization wastewater, reduce sludge discharge, recycle gypsum, and facilitate operation and maintenance.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a low-cost zero-discharge desulfurization wastewater treatment system and method, which have the advantages of simple design, convenient operation and maintenance and low cost, can reduce the dosage of desulfurization wastewater treatment, reduce sludge discharge and effectively recover calcium sulfate.
In order to achieve at least the above purposes, the invention adopts the following technical scheme:
a low-cost zero release desulfurization waste water treatment system which characterized in that includes: the system comprises a desulfurization wastewater pretreatment subsystem and a zero-discharge treatment subsystem, wherein the desulfurization wastewater pretreatment subsystem is used for pretreating desulfurization wastewater discharged from a desulfurization absorption tower, removing suspended matters, COD (chemical oxygen demand) and heavy metals, and recovering gypsum to obtain pretreated wastewater; the evaporation drying treatment subsystem is used for continuously carrying out evaporation and drying treatment on the pretreated wastewater, and finally realizing zero emission;
the desulfurization wastewater pretreatment subsystem comprises: the gypsum cyclone is used for carrying out primary solid-liquid separation treatment on the desulfurization wastewater to obtain gypsum slurry; an inlet of the vacuum belt conveyor is connected with an underflow outlet of the gypsum cyclone and is used for further solid-liquid separation treatment of the gypsum slurry to respectively obtain a gypsum filter cake and filtrate; an inlet of the filtrate vacuum tank is connected with a vacuum port of the vacuum belt conveyor and is used for keeping the vacuum belt conveyor in a vacuum state and storing filtrate discharged by the vacuum belt conveyor; an inlet of the aeration tank is connected with a filtrate outlet of the filtrate vacuum tank and is used for carrying out aeration treatment on the filtrate; the inlet of the precipitator is connected with the water outlet of the aeration tank and is used for performing flocculation precipitation treatment on the wastewater to obtain sludge and supernatant; the inlet of the first filter is connected with the water outlet of the precipitator and is used for filtering supernatant discharged by the precipitator to obtain pretreated wastewater; and the inlet of the water producing tank is connected with the water producing port of the first filter and is used for storing the pretreated wastewater.
As a preferred embodiment, the above-mentioned low-cost zero-discharge desulfurization wastewater treatment system includes: the inlet of the evaporator is connected with the water outlet of the water producing pool and is used for carrying out evaporation concentration treatment on the pretreated wastewater; the inlet of the second filter is connected with the concentrated solution outlet of the evaporator and is used for filtering the concentrated solution output by the evaporator; a waste water inlet of the flue gas drying tower is connected with a water outlet of the second filter and is used for drying the clear liquid output by the second filter to obtain crystallized salt powder and water vapor; and the inlet of the dust remover is connected with the flue gas outlet of the flue gas drying tower and is used for treating the flue gas exhausted from the flue gas drying tower.
As a preferred embodiment, the low-cost zero-discharge desulfurization wastewater treatment system comprises a reaction tank arranged in the precipitator, a guide cylinder arranged in the middle of the reaction tank, a stirrer arranged above the reaction tank, a chemical adding device connected with the reaction tank, a water inlet of the reaction tank connected with a water outlet of the aeration tank, and a water outlet of the reaction tank communicated with the precipitator through a pipeline;
preferably, the dosing device comprises a first dosing device and a second dosing device, the first dosing device is used for adding the flocculation compound medicament, and the second dosing device is used for adding the pH regulator;
preferably, the settler is a clarifier; more preferably a high efficiency cyclone clarifier.
In the low-cost zero-discharge desulfurization wastewater treatment system, as a preferred embodiment, the first filter is a high-precision filter; preferably a non-membrane high precision filter; further, the filtration accuracy of the non-membrane high-accuracy filter was 2 μm.
As a preferred embodiment, the low-cost zero-discharge desulfurization wastewater treatment system is characterized in that the aeration tank is provided with a high-efficiency aerator.
As a preferred embodiment, the evaporator is a 2-4-effect evaporator, preferably a four-effect evaporator;
more preferably, the evaporator is provided with an evaporator matching device, a flue gas heat exchange device and a water vapor heat exchange device, wherein the evaporator matching device is used for cleaning and controlling the evaporator; the flue gas heat exchange device is arranged in the main flue and is used as a heat source of the water vapor heat exchange device; the water vapor heat exchange device is used for heating wastewater;
furthermore, the flue gas heat exchange device is connected with the evaporator, and a water source used in the flue gas heat exchange device is condensed water obtained by condensing steam discharged by the evaporator;
furthermore, the heat exchanger of the flue gas heat exchange device adopts a heat pipe type heat exchanger; and the heat exchanger of the water vapor heat exchange device adopts a shell-and-tube heat exchanger.
In the above low-cost zero-discharge desulfurization wastewater treatment system, as a preferred embodiment, the filtration precision of the second filter is 50 μm; more preferably, the second filter is a fully automatic filter.
Above-mentioned low-cost zero release desulfurization effluent disposal system, as an preferred embodiment, be equipped with the atomizer in the flue gas drying tower, the atomizer is high-efficient rotatory atomizer.
As an optimal implementation mode, the low-cost zero-discharge desulfurization wastewater treatment system is characterized in that the dust remover is a bag-type dust remover or an electric dust remover.
A low-cost zero-discharge desulfurization wastewater treatment method is implemented by the low-cost zero-discharge desulfurization wastewater treatment system; preferably, a flocculation composite medicament and a pH regulating medicament are added into a reaction tank of the sedimentation tank, and the pH value is regulated to 8-9; preferably, the temperature of the hot secondary air or the high-temperature flue gas for heating the fog drops in the flue gas drying tower is 300-350 ℃, and the wind speed or the flue gas flow velocity is controlled to be 3-6 m/s.
Compared with the prior art, the invention has the advantages that:
1) the desulfurization wastewater treatment system provided by the application realizes low-cost zero-emission operation of desulfurization wastewater through process experiments and transformation;
2) the desulfurization wastewater treatment system provided by the application has the advantages of short flow, low operation cost and convenience in maintenance and operation, and solves the problems of high investment and high operation cost of the conventional desulfurization wastewater treatment facility;
3) the desulfurization wastewater treatment system is provided with the high-efficiency aerator, so that the blockage of the aeration device is avoided; meanwhile, the efficient flocculation composite medicine is added in a matching manner, so that the dosage of the desulfurization wastewater treatment is further reduced, the sludge discharge is reduced, and conditions are created for realizing low-cost zero discharge of the desulfurization wastewater;
4) the utility model provides a desulfurization effluent disposal system no longer adopts traditional waste water swirler, chooses for use gypsum swirler, the vacuum belt feeder allies oneself with to be used for reaching the effect of effectively getting rid of the suspended solid, and further preferred adoption clarifier, non-membrane high accuracy filter solve the problem that the suspended solid is difficult to get rid of in desulfurization waste water in the preliminary treatment stage, has promoted the stability of system's operation, also can retrieve calcium sulfate effectively simultaneously, realizes the resource recovery.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only references to some embodiments in this application document, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts, and some parts of them can be used after adjustment.
FIG. 1 shows a flow diagram of a low-cost zero-emission desulfurization wastewater treatment system according to a preferred embodiment of the present application.
In the figure, 10 is a gypsum cyclone, 20 is a vacuum belt conveyor, 30 is a filtrate aeration tank, 301 is an aerator, 40 is a precipitator, 401 is a reaction tank, 402 is a first medicine adding device, 403 is a second medicine adding device, 50 is a first filter, 60 is a water generating tank, 70 is an evaporator, 701 is an evaporator matching device, 702 is a flue gas heat exchange device, 703 is a water vapor heat exchange device, 80 is a second filter, 90 is a flue gas drying tower, 901 is an atomizer, 902 is hot secondary air or high-temperature flue gas, and 100 is a dust remover.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail with reference to the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto, and the described examples are only a part of examples of the present invention, but not all examples. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are for convenience of description of the present invention only and do not require that the present invention must be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. The terms "connected" and "connected" used herein should be interpreted broadly, and may include, for example, a fixed connection or a detachable connection; they may be directly connected or indirectly connected through intermediate members, and specific meanings of the above terms will be understood by those skilled in the art as appropriate.
As shown in fig. 1, the present invention provides a low-cost zero-discharge desulfurization wastewater treatment system, which comprises: the system comprises a desulfurization wastewater pretreatment subsystem and a zero-discharge treatment subsystem, wherein the desulfurization wastewater pretreatment subsystem is used for pretreating desulfurization wastewater, and the pretreatment wastewater comprises gypsum separation, suspended matter treatment, COD removal and the like, so that pretreated wastewater is finally obtained; the evaporation and drying subsystem continues to evaporate and dry the pretreated wastewater, and finally zero discharge is realized; the desulfurization wastewater pretreatment subsystem comprises: the system comprises a gypsum cyclone 10, a vacuum belt conveyor 20, a filtrate vacuum tank, an aeration tank 30, a precipitator 40, a first filter 50 and a water production tank 60; the evaporation drying processing subsystem comprises: an evaporator 70, a second filter 80, a flue gas drying tower 90, a dust separator 100, and piping and pumps for connecting the various devices within the system. The following describes the above devices and their connections.
And the gypsum cyclone 10 is used for receiving the raw water of the desulfurization wastewater, performing primary solid-liquid separation on the raw water and separating gypsum slurry from the raw water. Specifically, the inlet of the gypsum cyclone 10 is connected with a desulfurization waste water outlet arranged in a slurry tank at the lower part of the desulfurization absorption tower, and the underflow outlet of the gypsum cyclone 10 is connected with a vacuum belt conveyor 20; the desulfurization reaction products generated in the desulfurization absorption tower are collected into a slurry pool at the lower part to form desulfurization wastewater, namely raw desulfurization wastewater to be treated by the low-cost zero-emission desulfurization wastewater treatment system provided by the invention, together with unreacted desulfurization slurry and the like, the desulfurization wastewater is generally conveyed into a gypsum cyclone 10 through a pump to be subjected to primary solid-liquid separation treatment, most of gypsum, namely gypsum slurry, is separated and discharged through an underflow outlet, the gypsum slurry is conveyed to a vacuum belt conveyor 20 to be further subjected to solid-liquid separation treatment, and the remaining desulfurization wastewater flows out through an overflow outlet of the gypsum cyclone 10 and is conveyed back to the desulfurization absorption tower for use.
And an inlet of the vacuum belt conveyor 20 is connected with an underflow outlet of the gypsum cyclone 10 and is used for further solid-liquid separation treatment of the gypsum slurry to respectively obtain a gypsum filter cake and filtrate. Specifically, the inlet of the vacuum belt conveyor 20 is connected with the underflow outlet of the gypsum cyclone 10, and the filtrate outlet of the vacuum belt conveyor 20 is connected with the filtrate vacuum tank; the gypsum slurry from the underflow outlet of the gypsum cyclone 10 enters a vacuum belt conveyor 20 for vacuum dehydration to respectively obtain a filter cake (mainly gypsum) and a filtrate, the gypsum filter cake is recycled, and the filtrate is discharged to subsequent equipment for further treatment through the filtrate outlet of the vacuum belt conveyor 20.
An inlet of the filtrate vacuum tank is connected with a vacuum port of the vacuum belt conveyor 20, and is used for keeping the vacuum belt conveyor in a vacuum state, storing filtrate discharged by the vacuum belt conveyor 20, and an outlet of the filtrate vacuum tank is connected with the aeration tank 30. The desulfurized wastewater is further dewatered in vacuum by a vacuum belt conveyor 20 to separate gypsum, and then enters a filtrate vacuum tank in the form of filtrate, and then is further conveyed to an aeration tank 30 for further treatment.
And the aeration tank 30 is connected with the filtrate outlet of the filtrate vacuum tank at the inlet and is used for carrying out aeration treatment on the filtrate so as to remove COD and sulfite. Specifically, an inlet of the aeration tank 30 is connected to a filtrate outlet of the filtrate vacuum tank, a water outlet of the aeration tank 30 is connected to the precipitator 40, an aerator and a stirrer are arranged in the aeration tank 30, the desulfurization wastewater (filtrate) enters the aeration tank 30 and is uniformly stirred by the stirrer, and part of substances in the filtrate react with oxygen provided by the aerator to be removed, for example, COD is oxidized and decomposed to be reduced, and calcium sulfite is oxidized to calcium sulfate.
And the precipitator 40, the inlet of which is connected with the water outlet of the aeration tank 30, is used for carrying out flocculation precipitation treatment on the desulfurization wastewater to obtain sludge and supernatant. Specifically, the inlet of the precipitator 40 is connected with the water outlet of the aeration tank 30, the water outlet of the precipitator 40 is connected with the first filter 50, and the precipitator 40 is provided with a dosing device for adding chemicals such as flocculant and the like; in operation, after the desulfurization wastewater from the water outlet of the aeration tank 30 enters the precipitator 40, suspended matters in the desulfurization wastewater and the added chemicals are subjected to flocculation reaction to generate flocculates (having a function of removing heavy metals at the same time), the flocculates are precipitated to the lower part of the precipitator 40 to form sludge, the sludge is discharged through the sludge outlet of the precipitator 40, and the obtained supernatant flows to the first filter 50 through the water outlet of the precipitator 40.
And the inlet of the first filter 50 is connected with the water outlet of the precipitator 40 and is used for filtering the supernatant discharged from the precipitator 40 so as to further remove the non-soluble COD in the desulfurization wastewater and intercept fine suspended matters. Specifically, the inlet of the first filter 50 is connected with the water outlet of the precipitator 40, and the water producing port of the first filter 50 is connected with the water producing pond 60; the supernatant from the outlet of the precipitator 40, which still contains non-soluble COD and non-precipitated smaller sized suspended matter, requires further purification by the first filter 50 for subsequent treatment. Preferably, the first filter 50 has a function of intercepting suspended matter of 10 μm or more.
And an inlet of the water producing tank 60 is connected with the water producing port of the first filter 50 and is used for storing the pretreated desulfurization wastewater, namely the pretreated wastewater, specifically, the clear liquid flowing out of the water producing port of the first filter 50. The clear liquid is the desulfurized wastewater after pretreatment, belongs to high-salinity wastewater and contains SO4 2-、Cl-、Mg2-、Ca2-、Na+In which SO4 2-、Mg2-The content is high, and the advanced treatment is required to be carried out continuously. Specifically, the inlet of the water producing tank 60 is connected to the water producing port of the first filter 50, the outlet of the water producing tank 60 is connected to the wastewater inlet of the evaporation drying treatment subsystem (specifically, the wastewater inlet of the evaporator), and the pretreated desulfurization wastewater enters the water producing tank 60 and is conveyed to the evaporation drying treatment subsystem for subsequent advanced treatment, so as to achieve the ultimate goal of zero wastewater discharge.
And an inlet of the evaporator 70 is connected with an outlet of the water producing tank 60, and is used for performing evaporation concentration treatment on the effluent (namely the pretreated wastewater) of the water producing tank 60 to respectively obtain a concentrated solution and distilled water. Specifically, a wastewater inlet of the evaporator 70 is connected with an outlet of the water producing tank 60, and a concentrated solution outlet of the evaporator 70 is connected with the second filter 80; after being treated by the above-mentioned equipment, the desulfurization waste water is conveyed to the evaporator 70 through the outlet of the water producing tank 60 to form a concentrated solution through low-temperature flash evaporation, the concentrated solution is conveyed to the second filter 80 through the concentrated solution outlet of the evaporator 70, and the steam obtained by evaporating the desulfurization waste water is condensed into distilled water by the tail gas condenser to be recycled. The evaporator 70 is preferably a 2-4 effect evaporator, and in the specific embodiment of the invention, a four effect evaporator is adopted, so that more energy can be saved, and the cooperation with subsequent equipment can be more facilitated to achieve a better comprehensive use effect.
A second filter 80, an inlet of which is connected to the concentrated solution outlet of the evaporator 70, for filtering the concentrated solution output from the evaporator 70 to separate solid from liquid; the concentrated solution output from the evaporator 70 still contains a part of salts precipitated from gypsum, magnesium sulfate crystals and the like, and the part of the salts can be recycled, and meanwhile, in order to protect subsequent equipment and maintain the stable operation of the system, a second filter 80 is arranged in the system. Specifically, an inlet of the second filter 80 is connected to a concentrated solution outlet of the evaporator 70, a water outlet of the second filter 80 is connected to the flue gas drying tower 90, the concentrated solution output from the evaporator 70 enters the second filter 80 to undergo solid-liquid separation, so as to obtain sludge and clear solution respectively, wherein the clear solution is sent into the flue gas drying tower 90 through the water outlet of the second filter 80 to be processed.
An inlet of the flue gas drying tower 90 is connected with a water outlet of the second filter 80, and the flue gas drying tower is used for drying the clear liquid output by the second filter 80 to obtain crystallized salt powder; specifically, a wastewater inlet of the flue gas drying tower 90 is connected with a water outlet of the second filter 80, a flue gas outlet of the flue gas drying tower 90 is connected with the dust remover 100, clear liquid output by the second filter 80 enters the flue gas drying tower 90 to be evaporated to dryness, zero discharge of wastewater is realized, namely, most of crystallized salt in dry matter obtained after the wastewater is evaporated to dryness falls into the bottom end of the flue gas drying tower 90 and is conveyed to an ash silo by a bin pump, a small part of crystallized salt and water vapor enter the dust remover 100 along with the flue gas to be treated, the small part of crystallized salt is trapped, and the water vapor is discharged into the air.
And the inlet of the dust remover 100 is connected with the flue gas outlet of the flue gas drying tower 90 and is used for treating the flue gas discharged from the flue gas drying tower 90 to enable the flue gas to meet the emission standard, and the dust remover 100 can intercept particulate matters (including a small part of crystallized salt powder obtained by drying waste water) in the flue gas.
In the low-cost zero-discharge desulfurization wastewater treatment system, as another preferred embodiment, the aeration tank 30 is provided with the aerator 301, the aerator 301 adopts the high-efficiency aerator, in the specific embodiment of the invention, the high-efficiency aerator is detachable aeration, is made of polypropylene (PP), has the aeration pore diameter of Ø 25mm, adopts a vortex-shaped structure, and avoids the aeration tank 30 from being polluted and blocked, in the specific embodiment of the invention, the high-efficiency aerator can be directly placed in the aeration tank 30 without connection, and can also be fixed at the top of the aeration tank 30 through a pipeline, and the high-efficiency aerator adopted in the invention can be purchased from the market, for example, the high-efficiency aerator of the OHR institute of fluid technology (Japan) with the model of AE-130N.
As another preferred embodiment, the sludge outlet of the precipitator 40 is connected with the underflow outlet of the gypsum cyclone 10, and is merged with the underflow of the gypsum cyclone 10, and then enters the vacuum belt conveyor 20 for treatment.
In the low-cost zero-discharge desulfurization wastewater treatment system, as another preferred embodiment, the sludge outlet of the first filter 50 is connected with the underflow outlet of the gypsum cyclone 10, and is merged with the underflow of the gypsum cyclone 10 and then enters the vacuum belt conveyor 20 for treatment.
As another preferred embodiment, the low-cost zero-discharge desulfurization wastewater treatment system is characterized in that a reaction tank 401 is arranged in the precipitator 40, a guide cylinder is arranged in the middle of the reaction tank 401, a stirrer is arranged above the reaction tank 401, the reaction tank 401 is further externally connected with a dosing device, a water inlet of the reaction tank 401 is connected with a water outlet of the aeration tank 30, and a water outlet of the reaction tank 401 is communicated with the precipitator 40 through a pipeline; when the system is in operation, wastewater enters the reaction tank 401 to perform flocculation reaction with the medicament to generate flocculate, and wastewater mixed with the flocculate after reaction enters the precipitator 40 to be precipitated.
The settler 40 is preferably a clarifier, and in particular embodiments of the present invention is a high efficiency cyclone clarifier. High efficiency cyclone clarifiers are commercially available as solutions, such as Beijing Waider Chuangyu environmental protection facilities, Inc.
In a specific embodiment of the invention, the mixer is a variable speed, liftable mixer, rotating at 40-200rpm, with the lifting amount being 5-10 times the amount of incoming water.
In a specific embodiment of the present invention, the chemical adding device includes a first chemical adding device 402 and a second chemical adding device 403, and the reaction tank 401 is provided with a chemical adding port, which is connected to the first chemical adding device 402 and the second chemical adding device, respectively, wherein the first chemical adding device 402 is used for adding a flocculation compound chemical, such as a high efficiency flocculation compound chemical provided by beijing hua de chuangyao environmental protection equipment limited company with model number HD-SS02, and the second chemical adding device 403 is used for adding a pH adjusting agent, such as sodium hydroxide, ammonia water, etc.; in the preferred embodiment of the invention, the flocculation effect is enhanced by adding the flocculation composite medicament, and simultaneously, the pH value is adjusted to 8-9 by adding the sodium hydroxide, so that a better flocculation effect can be achieved, the medicament is less in addition, the flocculate is easier to separate, and the corrosivity of effluent is lower.
In the low-cost zero-emission desulfurization waste water treatment system, as another preferred embodiment, the first filter 50 is a high-precision filter, and in view of the relative easy fouling of the membrane filter, the first filter 50 is more preferably a non-membrane high-precision filter in the present invention; non-membrane high-precision filters are commercially available, such as those available from Obo Water treatment, Inc. of Beijing; further, the filtration accuracy of the non-membrane high-accuracy filter was 2 μm.
As another preferred embodiment, the evaporator 70 is provided with an evaporator matching device 701, a flue gas heat exchange device 702, and a water vapor heat exchange device 703, wherein the evaporator matching device 701 is used for cleaning and controlling the evaporator 70; the flue gas heat exchange device 702 is arranged in the main flue and used for recovering flue gas waste heat after the dust remover as a heat source of the water vapor heat exchange device 703; the water vapor heat exchange device 703 is used to heat the wastewater. More preferably, the flue gas heat exchange device 702 is connected to the evaporator 70, and the water source used in the flue gas heat exchange device 702 is condensed water obtained by condensing steam discharged from the evaporator 70. The evaporator may be a commercially available solution. Further preferably, the evaporator 70 is a four-effect evaporator.
In the specific embodiment of the invention, the heat exchanger of the flue gas heat exchange device 702 adopts a heat pipe type heat exchanger; the heat exchanger of the water vapor heat exchange device 703 adopts a shell-and-tube heat exchanger, wherein the material of the inner pipeline can be dual-phase steels 2205 and 2507, the material of the shell is carbon steel, 316 and dual-phase steel 2205, the heat exchanger of the water vapor heat exchange device 703 is provided with a cathode protection device, two ends of the heat exchanger are provided with differential pressure transmitters, the heat exchanger can be two-stage, three-stage, four-stage or more, the tube side caliber of the heat exchanger of the water vapor heat exchange device is 16-32 mm, a light tube turbulent flow structure is adopted, the flow rate is controlled to be 3m/s, steam flows away.
In the low-cost zero-discharge desulfurization waste water treatment system, as another preferred embodiment, the second filter 80 has a filtering precision of 50 μm, and is more preferably a fully automatic filter. Fully automatic filters are commercially available, such as the model INTEGERA20 available from Next-Fuel corporation, USA.
As another preferred embodiment, the sewage discharge port of the second filter 80 is connected to the underflow outlet of the gypsum cyclone 10, and is merged with the underflow of the gypsum cyclone 10 and then enters the vacuum belt conveyor 20 for treatment.
As another preferred embodiment, the low-cost zero-emission desulfurization wastewater treatment system is characterized in that an atomizer 901 is arranged in the flue gas drying tower 90, an air inlet of the flue gas drying tower 90 is connected with hot secondary air of a boiler fan or high-temperature flue gas discharged from a boiler and in front of an air preheater, and an outlet of the flue gas drying tower is connected with the dust remover 100. In the preferred embodiment of the present application, the dust collector 100 is preferably a bag-type dust collector or an electric dust collector. In the preferred embodiment of the application, the temperature of the hot secondary air is 300-350 ℃, and the flow velocity of the flue gas in the flue gas drying tower is controlled to be 5m/s, so that a better treatment effect can be obtained. In a preferred embodiment of the present invention, the atomizer 901 is a high efficiency rotary atomizer, which is commercially available, such as the model DM19-8 high efficiency rotary atomizer available from Sweden der environmental Technology AB. The concentrated wastewater output by the second filter 80 is atomized into droplets by the high-efficiency rotary atomizer, the droplets enter the flue gas drying tower 90, and contact with high-temperature flue gas or hot secondary air and are rapidly evaporated to dryness, most of the crystallized salt in the obtained dry matter falls into the bottom end of the flue gas drying tower 90 and is conveyed to an ash storehouse by a bin pump, a small part of the crystallized salt and water vapor are discharged along with the flue gas and enter a subsequent dust remover 100 for treatment, the small part of the crystallized salt is captured by the subsequent dust remover 100, and the water vapor is discharged into the air.
In order to ensure the long-term stable operation of the desulfurization wastewater treatment system and realize complete zero discharge, the system also comprises a related cleaning device, a dosing device, an electrical system and an instrument control system which are matched with each other.
The invention also provides a low-cost zero-discharge desulfurization wastewater treatment method which can be implemented by the low-cost zero-discharge desulfurization wastewater treatment system.
As a preferred embodiment, the desulfurization wastewater treatment method comprises the step of adding a flocculation composite medicament and a pH regulating medicament into a reaction tank 401 of the sedimentation tank 40 to regulate the pH value to 8-9.
As a preferred embodiment, the temperature of the hot secondary air or the high-temperature flue gas for heating the fog drops in the flue gas drying tower 90 is 300-350 ℃, and the wind speed or the flue gas flow rate is controlled to be 3-6 m/s.
Examples
The desulfurization waste water in the prior art generally has the following characteristics: 1) the wastewater is slightly acidic, and the pH is generally kept between 4.5 and 5.5; 2) the suspended matters are very high (gypsum particles and the like), and the mass percent can reach tens of thousands of mg/L; 3) the fluoride, COD and heavy metal exceed the standard; 4) very high in salt content, mainly composed of Ca2+、Mg2+、Cl-、SO4 2-、 SO3 2-And the like; 5) the water quantity is generally 5t/h of 30 ten thousand units or 10t/h of 60 ten thousand units. In this regard, fig. 1 shows a preferred embodiment of the present invention, which provides a low-cost zero-discharge desulfurization waste water treatment system comprising: gypsum cyclone 10, vacuum belt conveyor 20, filtrate aeration tank 30 and aerationThe device comprises a precipitator 301, a precipitator 40, a reaction tank 401, a first dosing device 402, a second dosing device 403, a first filter 50, a water production tank 60, an evaporator 70, an evaporator matching device 701, a flue gas heat exchange device 702, a water vapor heat exchange device 703, a second filter 80, a flue gas drying tower 90, a high-efficiency rotary atomizer 901, hot secondary air/high-temperature flue gas 902, a dust remover 100, and a pipeline and a pump for connecting the devices. The system realizes zero-discharge low-cost operation of the desulfurization wastewater through process experiments and transformation. The connection and material flow relationships of the various devices of the system are detailed below.
A desulfurization wastewater inlet is arranged on the gypsum cyclone 10, raw desulfurization wastewater enters the gypsum cyclone 10 through the wastewater inlet so as to realize preliminary solid-liquid separation, namely most of gypsum is separated from the raw desulfurization wastewater, discharged through an underflow outlet of the gypsum cyclone 10 and conveyed to a vacuum belt conveyor 20 for further solid-liquid separation treatment; the separated desulfurization waste water is discharged through an overflow outlet (i.e., an upper overflow outlet) of the gypsum cyclone 10, and returned to the desulfurization absorption tower for use.
The vacuum belt conveyor 20 is used for further performing solid-liquid separation on gypsum slurry treated by the gypsum cyclone 10 and further removing insoluble substances such as calcium sulfate and the like to obtain filtrate and filter cakes, the underflow outlet of the gypsum cyclone 10 is connected with the inlet of the vacuum belt conveyor 20, the vacuum port of the vacuum belt conveyor 20 is connected with a filtrate vacuum tank, the filtrate port of the filtrate vacuum tank is connected with a filtrate aeration tank 30, an aerator 301 is arranged in the filtrate aeration tank 30, the aerator adopts a high-efficiency aerator which is detachable and connected by a flange, is made of polypropylene (PP), has an aeration pore diameter of Ø 25mm and is internally provided with a vortex-shaped structure to avoid pollution and blockage, and the filtrate aeration tank 30 is used for aerating through the aerator 301 so as to decompose reductive impurities in the filtrate and remove COD and sulfite.
The filtrate aeration tank 30 is connected with a reaction tank 401 of the precipitator 40 through a pump and a pipeline, a variable speed stirrer is arranged on the top of the reaction tank 401, the rotating speed is 40-200rpm, the stirrer is of a lifting type, the lifting amount is 5-10 times of the amount of incoming water, the stirrer lifts water to uniformly mix water with air/oxygen and promote the oxidation reaction, a guide cylinder is arranged in the middle of the reaction tank 401 and is used for uniformly distributing water in the reaction tank 401 and facilitating the stirring of the stirrer, a dosing port is arranged on the reaction tank 401 and is respectively connected with a first dosing device 402 and a second dosing device 403, a flocculation compound medicament is added into the reaction tank through the first dosing device 402, sodium hydroxide is added through the second dosing device 403 at the same time, the PH value is adjusted to 8-9, flocculation reaction occurs under the condition so as to further remove suspended matters in the desulfurization wastewater and remove heavy metals, the water outlet of the reaction tank 401 is connected to the precipitator 40, and the sludge port of the precipitator 40 is connected with the underflow outlet at the bottom of the gypsum cyclone 10 through a pump. The precipitator 40 in this embodiment employs a high efficiency cyclone clarifier.
The first filter 50 is used for filtering the wastewater treated by the precipitator 40 and further removing fine suspended matters and non-soluble COD in the desulfurization wastewater, the water outlet of the high-efficiency precipitator 40 is connected to the first filter 50, and the sludge port of the first filter 50 is connected with the underflow outlet of the gypsum cyclone 10. The first filter 50 is a non-membrane high-precision filter having a filtration precision of 2 μm.
The water producing tank 60 is used for receiving water produced by the first filter 50, a water producing port of the first filter 50 is connected with the water producing tank 60, and water discharged from the water producing tank 60 is pumped into a subsequent device, namely an evaporator 70 through a water pump.
The waste water inlet of the evaporator 70 is connected with the water producing tank 60, the concentrated solution outlet of the evaporator 70 is connected with the second filter 80, and the evaporator 70 adopts a flash evaporation mode to realize evaporation concentration of the pretreated desulfurization waste water. The evaporator 70 is a four-effect evaporator.
The evaporator 70 is provided with an evaporator matching device 701, and the flue gas heat exchange device 702 is a heat pipe type efficient heat exchanger, wherein the evaporator matching device 701 is used for cleaning and controlling the evaporator 70; the flue gas heat exchange device 702 is arranged in the main flue, is connected with the water vapor heat exchange device 703 and is used for recovering the waste heat of the flue gas after the dust remover as the heat source of the water vapor heat exchange device 703; the water-vapor heat exchanger 703 is used to heat the wastewater to be concentrated. The heat exchanger of the water vapor heat exchange device 703 adopts a shell-and-tube heat exchanger, wherein the material of an internal pipeline can be dual-phase steels 2205 and 2507, the material of a shell is carbon steel, 316 and the dual-phase steel 2205, the heat exchanger is provided with a cathode protection device, pressure difference transmitters are arranged at two ends of the heat exchanger and are matched with a four-effect evaporator, the heat exchanger of the water vapor heat exchange device 703 has four stages, the tube side caliber of the heat exchanger of the water vapor heat exchange device 703 is 16-32 mm, a light tube turbulent flow structure is adopted, the flow rate is controlled to be 3m/s, steam flows.
The fourth effect of the evaporator 70 is connected to the second filter 80; the second filter 80 adopts a full-automatic filter, the filtering precision is 50 μm, the sewage outlet of the second filter 80 is connected to the underflow outlet of the gypsum cyclone 10, and the water outlet of the second filter 80 is connected with the flue gas drying tower 90.
The concentrated solution output from the evaporator 70 is filtered by the second filter 80 and then flows to the flue gas drying tower 90 for drying treatment. The flue gas drying tower 90 is provided with an atomizer 901, the atomizer 901 is a high-efficiency rotary atomizer, the concentrated solution is atomized by the high-efficiency rotary atomizer and sprayed into the flue gas drying tower 90, an air inlet of the flue gas drying tower 90 is connected with hot secondary air 902 (or high-temperature flue gas) of a boiler fan, the air temperature is 300-350 ℃, the flue gas flow rate in the flue gas drying tower 90 is controlled to be 5m/s, the hot secondary air or the high-temperature flue gas in the tower is contacted with atomized droplets of the concentrated solution to rapidly evaporate the droplets of the concentrated solution to dryness, and finally salts in the wastewater form powdery products (mainly crystalline salts and the like), wherein most of the crystalline salts fall into the bottom end of the flue gas drying tower 90 and are conveyed to an ash storehouse by a storehouse pump, and a small part of the crystalline salts enter.
The flue gas outlet of the flue gas drying tower 90 is connected with a dust remover 100, and the dust remover 100 can be a cloth bag dust remover or an electric dust remover of a power plant.
In order to ensure the long-term stable operation of the process system, realize complete zero emission and utilize products, the method also comprises an electric system and instrument control which participate in the operation of the desulfurization wastewater recycling zero emission method.
Reference throughout this specification to "one embodiment," "an embodiment," and so forth, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment described generally throughout this application. The appearances of the same phrase in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the scope of the invention to effect such feature, structure, or characteristic in connection with other embodiments.
Although the invention has been described herein with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More specifically, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, other uses will also be apparent to those skilled in the art.
It will be appreciated by those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the invention are intended to be embraced therein.
Claims (10)
1. A low-cost zero release desulfurization waste water treatment system which characterized in that includes: the system comprises a desulfurization wastewater pretreatment subsystem and a zero-discharge treatment subsystem, wherein the desulfurization wastewater pretreatment subsystem is used for pretreating desulfurization wastewater discharged from a desulfurization absorption tower, removing suspended matters, COD (chemical oxygen demand) and heavy metals, and recovering gypsum to obtain pretreated wastewater; the evaporation drying treatment subsystem is used for continuously carrying out evaporation and drying treatment on the pretreated wastewater, and finally realizing zero emission;
the desulfurization wastewater pretreatment subsystem comprises:
the gypsum cyclone is used for carrying out primary solid-liquid separation treatment on the desulfurization wastewater to obtain gypsum slurry;
an inlet of the vacuum belt conveyor is connected with an underflow outlet of the gypsum cyclone and is used for further solid-liquid separation treatment of the gypsum slurry to respectively obtain a gypsum filter cake and filtrate;
an inlet of the filtrate vacuum tank is connected with a vacuum port of the vacuum belt conveyor and is used for keeping the vacuum belt conveyor in a vacuum state and storing filtrate discharged by the vacuum belt conveyor;
an inlet of the aeration tank is connected with a filtrate outlet of the filtrate vacuum tank and is used for carrying out aeration treatment on the filtrate;
the inlet of the precipitator is connected with the water outlet of the aeration tank and is used for performing flocculation precipitation treatment on the wastewater to obtain sludge and supernatant;
the inlet of the first filter is connected with the water outlet of the precipitator and is used for filtering supernatant discharged by the precipitator to obtain pretreated wastewater;
and the inlet of the water producing tank is connected with the water producing port of the first filter and is used for storing the pretreated wastewater.
2. The low-cost zero-emission desulfurization wastewater treatment system of claim 1, wherein the evaporation drying treatment subsystem comprises:
the inlet of the evaporator is connected with the water outlet of the water producing pool and is used for carrying out evaporation concentration treatment on the pretreated wastewater;
the inlet of the second filter is connected with the concentrated solution outlet of the evaporator and is used for filtering the concentrated solution output by the evaporator;
a waste water inlet of the flue gas drying tower is connected with a water outlet of the second filter and is used for drying the clear liquid output by the second filter to obtain crystallized salt powder and water vapor;
and the inlet of the dust remover is connected with the flue gas outlet of the flue gas drying tower and is used for treating the flue gas exhausted from the flue gas drying tower.
3. The low-cost zero-emission desulfurization wastewater treatment system according to claim 1 or 2, wherein a reaction tank is arranged in the precipitator, a guide flow cylinder is arranged in the middle of the reaction tank, a stirrer is arranged above the reaction tank, the reaction tank is further externally connected with a chemical dosing device, a water inlet of the reaction tank is connected with a water outlet of the aeration tank, and a water outlet of the reaction tank is communicated with the precipitator through a pipeline;
preferably, the dosing device comprises a first dosing device and a second dosing device, the first dosing device is used for adding the flocculation compound medicament, and the second dosing device is used for adding the pH regulator;
preferably, the settler is a clarifier; more preferably a high efficiency cyclone clarifier.
4. The low-cost zero-emission desulfurization wastewater treatment system according to claim 1 or 2, wherein the first filter is a high-precision filter; preferably a non-membrane high precision filter; further, the filtration accuracy of the non-membrane high-accuracy filter was 2 μm.
5. The low-cost zero-emission desulfurization wastewater treatment system according to claim 1 or 2, wherein a high-efficiency aerator is provided in the aeration tank.
6. The low-cost zero-discharge desulfurization wastewater treatment system of claim 2, wherein the evaporator is a 2-4 effect evaporator, preferably a four effect evaporator;
more preferably, the evaporator is provided with an evaporator matching device, a flue gas heat exchange device and a water vapor heat exchange device, wherein the evaporator matching device is used for cleaning and controlling the evaporator; the flue gas heat exchange device is arranged in the main flue and is used as a heat source of the water vapor heat exchange device; the water vapor heat exchange device is used for heating wastewater;
furthermore, the flue gas heat exchange device is connected with the evaporator, and a water source used in the flue gas heat exchange device is condensed water obtained by condensing steam discharged by the evaporator;
furthermore, the heat exchanger of the flue gas heat exchange device adopts a heat pipe type heat exchanger; and the heat exchanger of the water vapor heat exchange device adopts a shell-and-tube heat exchanger.
7. The low-cost zero-discharge desulfurization wastewater treatment system according to claim 2, wherein the second filter has a filtration precision of 50 μm; preferably, the second filter is a fully automatic filter.
8. The low-cost zero-emission desulfurization wastewater treatment system of claim 2, wherein an atomizer is arranged in the flue gas drying tower, and the atomizer is a high-efficiency rotary atomizer.
9. The low-cost zero-discharge desulfurization wastewater treatment system of claim 2, wherein the dust remover is a bag dust remover or an electric dust remover.
10. A low-cost zero-discharge desulfurization wastewater treatment method implemented by the low-cost zero-discharge desulfurization wastewater treatment system according to any one of claims 1 to 9;
preferably, a flocculation composite medicament and a pH regulating medicament are added into a reaction tank of the sedimentation tank, and the pH value is regulated to 8-9;
preferably, the temperature of the hot secondary air or the high-temperature flue gas for heating the fog drops in the flue gas drying tower is 300-350 ℃, and the wind speed or the flue gas flow velocity is controlled to be 3-6 m/s.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112125463A (en) * | 2020-10-14 | 2020-12-25 | 青岛润扬环境科技有限公司 | Power plant variable load coal-fired boiler desulfurization wastewater zero discharge system |
| CN112194318A (en) * | 2020-09-28 | 2021-01-08 | 国家电投集团远达环保工程有限公司重庆科技分公司 | Flue gas waste heat concentration method and device for desulfurization wastewater |
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