Device and method for evaporating and solidifying power plant wastewater by using flue gas waste heat

Abstract

The invention provides a device and a method for evaporating and solidifying power plant wastewater by using flue gas waste heat, the device comprises a bypass flue led out from a dust remover and a desulfurizing tower in a flue gas treatment main flue, the bypass flue is provided with an evaporating and solidifying unit, the evaporating and solidifying unit comprises an evaporating and solidifying device, an atomizing and spraying device and a dust filtering device, the dust filtering device and the atomizing and spraying device are positioned at the upper part in the evaporation and curing device, and the dust filtering device is positioned above the atomizing and spraying device; the dust filtering device comprises blowing pipes, filter bags and venturi tubes, the blowing pipes are connected with the filter bags through the venturi tubes, each blowing pipe corresponds to a plurality of groups of filter bags and venturi tubes, and the filter bags and the venturi tubes are in one-to-one correspondence. According to the device disclosed by the invention, by arranging the bypass flue, waste heat of flue gas is utilized to evaporate and solidify wastewater, so that wastewater recovery treatment and zero emission can be realized, additional energy consumption is not needed, the treatment efficiency is high, the treatment cost is low, a main flue gas treatment process is not influenced, and clean production is realized; the device is simple in structure, convenient to maintain and low in operation cost.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas and wastewater treatment, and relates to a device and method for evaporating and solidifying power plant wastewater by utilizing flue gas waste heat. Background Art

[0002] In the power industry, a large amount of flue gas is generated during thermal power generation. The flue gas needs to be treated by dust removal, desulfurization and other unit operations before it can be discharged. Based on the currently commonly used wet desulfurization process, a large amount of wastewater will be generated after desulfurization treatment. This type of wastewater contains high levels of pollutants such as salt and heavy metals. If it is directly discharged into the environment, it will cause serious pollution to water bodies, soil, etc., and thus pose a threat to the ecological environment and human health. Therefore, the wastewater needs to be treated and recycled.

[0003] At present, the wastewater from power plants is generally treated by pretreatment + wastewater concentration + crystallization solidification. The main operation process is to evaporate the water in the wastewater through evaporation, crystallization and other means, so that the pollutants in the wastewater are concentrated and separated, thereby achieving the purpose of reducing the amount of wastewater discharged and reducing the concentration of pollutant emissions. Among them, the common process routes of pretreatment technology include chemical softening and membrane filtration to remove calcium and magnesium ions and reduce hardness; the common process routes of wastewater concentration include membrane concentration and reduction technology and thermal concentration and reduction technology to achieve wastewater concentration, reduction and purification; the process technologies of crystallization solidification mainly include evaporation crystallization and flue evaporation. The latter refers to the use of flue gas waste heat in the flue to achieve wastewater evaporation, which can just use the heat in the flue gas generated by the power plant boiler, making it an effective way to treat power plant wastewater.

[0004] Flue evaporation technology mainly includes two types: main flue evaporation and bypass flue evaporation. The former is to spray atomized concentrated wastewater into the main flue gas duct for evaporation, and the latter is to add a bypass flue next to the main flue and set up an evaporator to introduce part of the high-temperature flue gas into the evaporator to evaporate the concentrated wastewater. The former has higher requirements on the flue and needs to have a sufficient length, otherwise it cannot be completely evaporated before entering the dust collector, and the problem of flue corrosion protection needs to be considered. Therefore, the bypass flue evaporation method is usually adopted at present, and it is necessary to ensure that the extraction of flue gas does not affect the operation of the boiler and power plant.

[0005] CN 105481157A discloses a zero-emission treatment method for desulfurization wastewater based on flue gas waste heat evaporation, which includes three systems, namely, a double alkali method pretreatment system, a membrane filtration desalination concentration reduction system, and a flue gas bypass evaporation tower zero-emission system, wherein the flue gas bypass evaporation tower is independently arranged between the boiler air preheater and the dust collector, and the evaporation tower extracts part of the high-temperature flue gas in the front or rear of the air preheater, evaporates and crystallizes the high-salt concentrated liquid in the evaporation tower, and the evaporated water vapor and crystals enter the dust collector together with the flue gas, and after gas-solid separation, the water vapor enters the desulfurization absorption tower for recycling with the flue gas, and the crystals are discharged with the fly ash. The evaporation tower used in the flue gas bypass system in the method does not have a clear specific structure, and the concentrated desulfurization wastewater is still discharged into the main flue pipeline for treatment after evaporation, which increases the processing load of the boiler flue, and the crystals cannot be recycled.

[0006] CN 108975437A discloses a device for concentrating wastewater using the waste heat of clean flue gas from a coal-fired boiler. The device includes a dust collector, a desulfurization tower, a chimney and a clean flue gas duct, and also includes a wastewater tank, a wastewater concentration component, a concentrated water tank, a pump station and a bypass wastewater concentration duct. An induced draft fan is provided inside the left end of the bypass wastewater concentration duct. The wastewater concentration component is located in the bypass wastewater concentration duct and includes a wastewater concentration chamber, a concentrated water collector and a demister. An atomizer is provided inside the left end of the wastewater concentration chamber, and a heat exchanger is provided at the left end. The drainage port of the wastewater pump station is connected to a water supply pipe. The device concentrates wastewater by setting a bypass duct instead of evaporating and solidifying the concentrated wastewater. The types of equipment and environmental conditions required for the two are different, and the subsequent separation process is also different. The recycling of crystals is not involved.

[0007] In summary, for the device and method of evaporation and solidification of power plant wastewater, the power plant layout needs to be reasonable and the flue gas should be selected, and the wastewater can be evaporated and solidified by using the remaining heat to achieve zero discharge of wastewater and recycling of crystals, which is energy-saving, environmentally friendly, safe and reliable. Summary of the invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a device and method for evaporating and solidifying power plant waste water by utilizing flue gas waste heat. The device utilizes the flue gas waste heat to evaporate and solidify the power plant waste water through the setting of a bypass flue, which can not only realize the treatment and recycling of waste water, but also does not require additional energy consumption, has high treatment efficiency, low treatment cost, and does not affect the main process of flue gas treatment, thereby realizing clean production.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] On the one hand, the present invention provides a device for evaporating and solidifying power plant wastewater by utilizing flue gas waste heat, the device comprising a bypass flue leading out from between a dust collector and a desulfurization tower in a flue gas treatment main flue, the bypass flue being provided with an evaporation and solidification unit, the evaporation and solidification unit comprising an evaporation and solidification device, a wastewater conveying device, an atomizing spraying device and a dust filtering device, the atomizing spraying device and the dust filtering device being both located in the upper part of the evaporation and solidification device, the dust filtering device being located above the atomizing spraying device, and the wastewater conveying device being connected to the inlet of the atomizing spraying device; the bypass flue leading out from the flue gas treatment main flue is connected to the lower inlet of the evaporation and solidification device, and the top outlet of the evaporation and solidification device is then connected back to the flue gas treatment main flue; the dust filtering device comprises a blowing pipe, a filter bag and a venturi tube, the blowing pipe is connected to the filter bag via the venturi tube, each blowing pipe corresponds to a plurality of groups of filter bags and venturi tubes, and the filter bags and venturi tubes correspond one to one.

[0011] In the present invention, for the treatment of power plant wastewater, after pretreatment and concentration treatment, the soluble salt therein usually needs to be separated by crystallization and solidification. In the present invention, the power plant flue gas is used as a heat source to treat the power plant wastewater, so a bypass flue is set to lead out the flue gas to avoid affecting the main process and equipment of flue gas treatment. An evaporation and solidification device is set on the bypass flue, and the wastewater is evaporated and solidified by the waste heat of the flue gas. By setting an atomizing spray device in the evaporation and solidification device, the difficulty of evaporation and solidification of the wastewater is reduced, the treatment efficiency is high, and the formed solidified material can be further separated and recovered, and the dust filtering device can filter out the solidified material carried in the flue gas to avoid entering the main flue. The device utilizes the waste heat resources of the power plant without consuming additional energy, which can reduce the treatment cost, and the device has a simple structure, convenient maintenance and low operating cost.

[0012] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0013] As a preferred technical solution of the present invention, the main flue for flue gas treatment is provided with a denitrification device, an air preheater, an economizer, a dust collector, a desulfurization tower and a chimney connected by the boiler flue gas outlet in sequence.

[0014] Preferably, the dust collector comprises any one of an electrostatic precipitator, a bag dust collector or an electric bag composite dust collector.

[0015] As a preferred technical solution of the present invention, the main flue gas treatment duct is further provided with a first induced draft fan and a second induced draft fan. The first induced draft fan is located on the flue between the dust collector and the desulfurization tower, and the second induced draft fan is located on the flue between the desulfurization tower and the chimney.

[0016] Preferably, the bypass flue is led out from the main flue between the dust collector and the first induced draft fan.

[0017] Preferably, a first isolating valve is provided on the connecting flue between the dust collector and the first induced draft fan, and a bypass flue is led out from the front of the inlet of the first isolating valve. The bypass flue is divided into two sections according to its location before and after the evaporation and curing device, namely, a first-section bypass flue and a second-section bypass flue.

[0018] Preferably, the first-stage bypass flue is provided with a second isolation valve, and the second-stage bypass flue is provided with a third isolation valve.

[0019] In the present invention, due to the arrangement of the bypass flue and the evaporation and curing unit, in order to ensure that the flue gas can quickly return to the main flue, a draft fan is arranged on the main flue after the bypass flue and before the desulfurization tower to accelerate the circulation of the flue gas; and the arrangement of multiple isolation valves is to ensure the independent operation of the main flue and the bypass flue, especially when the evaporation and curing unit fails or is under maintenance, the isolation valve on the bypass flue is closed and the isolation valve on the main flue is opened, which does not affect the operation of the main process of the unit.

[0020] As a preferred technical solution of the present invention, the main structure of the evaporation and curing device is an evaporation and curing cylinder, the bottom of the evaporation and curing cylinder is an ash hopper, and the bottom of the ash hopper is provided with a solidified material collecting port.

[0021] Preferably, a smoke inlet is provided at the bottom of the evaporation and curing cylinder, and a smoke outlet is provided at the top.

[0022] Preferably, the atomizing spray device comprises a spray plate and an atomizing nozzle, the spray plate is horizontally arranged, and comprises at least one, such as one, two or three, etc., and each spray plate is provided with a plurality of atomizing nozzles.

[0023] Preferably, when the number of the spray discs is two or more, the spray discs are arranged in parallel and spaced apart, and the atomizing nozzles on two adjacent spray discs are arranged in a staggered manner.

[0024] In the present invention, when the atomizing nozzles are staggered, the overlapping coverage of wastewater spraying is ensured to be no less than 200%, for example, 200%, 220%, 240%, 250%, 270%, 280% or 300%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the atomizing spray device is provided with a wastewater inlet, and the outlet of the wastewater conveying device is connected to the wastewater inlet of the atomizing spray device.

[0026] Preferably, the spray plate and the atomizing nozzle material independently include any one of polypropylene, polyvinylidene fluoride, ABS plastic, stainless steel, fiberglass or silicon carbide or a combination of at least two thereof. Typical but non-limiting examples of the combination include: a combination of polypropylene and polyvinylidene fluoride, a combination of polypropylene and ABS plastic, a combination of stainless steel and fiberglass, etc.

[0027] In the present invention, considering the corrosiveness of wastewater, the structure in the atomizing spray device can be made of organic polymer materials such as polypropylene, and the inner wall of the evaporation curing cylinder and the ash hopper can be anti-corrosive using carbon steel + acid-resistant clay.

[0028] As a preferred technical solution of the present invention, a compressed gas inlet is provided on the blowing pipe of the dust filtering device, and an electromagnetic pulse valve is provided on the compressed gas inlet pipeline.

[0029] Preferably, the blowing pipe is connected to a plurality of venturi tubes arranged in parallel, and each venturi tube is connected to a filter bag.

[0030] In the present invention, the expression "several" means that the number of corresponding devices or components can be specifically selected according to production needs and is not further limited here.

[0031] Preferably, the material of the filter bag includes any one of polyphenylene sulfide, aramid fiber or polyacrylonitrile fiber, or a combination of at least two of them. Typical but non-limiting examples of the combination include: a combination of polyphenylene sulfide and aramid fiber, a combination of aramid fiber and polyacrylonitrile fiber, a combination of polyphenylene sulfide, aramid fiber and polyacrylonitrile fiber, etc. The polyacrylonitrile fiber can specifically be acrylonitrile homopolymer fiber.

[0032] In the present invention, the spraying of the dust filtering device is controlled by an electromagnetic pulse valve, and the compressed gas can be selected from compressed air, compressed nitrogen, etc. Through the design of the venturi tube, the rate at which the compressed gas is blown to the filter bag can be increased, thereby effectively removing the dust accumulated on the bag; the filter bag can be selected from materials such as polyphenylene sulfide, which can withstand temperatures as high as 190°C and can also work under conditions of high dust content coal-fired flue gas.

[0033] As a preferred technical solution of the present invention, the wastewater conveying device includes a wastewater pump.

[0034] Preferably, the evaporation and curing unit further comprises a wastewater storage device, and an outlet of the wastewater storage device is connected to an inlet of the wastewater conveying device.

[0035] Preferably, a filtering device is further provided between the wastewater storage device and the wastewater conveying device.

[0036] Preferably, the wastewater storage device comprises a wastewater tank.

[0037] In the present invention, the wastewater is obtained from a wastewater tank in a factory area, a wastewater pump is provided for pressurization, and a filter is provided at the inlet of the wastewater pump to filter out possible solid particles.

[0038] In the present invention, the device is automatically controlled as a whole, including modules such as wastewater injection control, evaporation and solidification control, and dust filter blowing control.

[0039] On the other hand, the present invention provides a method for evaporating and solidifying power plant wastewater using the above device, the method comprising the following steps:

[0040] (1) A bypass flue is drawn from the main flue of the power plant flue gas treatment, and the concentrated power plant wastewater is contacted with the flue gas in countercurrent through atomization spraying, and the waste heat of the flue gas is used to evaporate and solidify the power plant wastewater to obtain a solidified product and flue gas containing steam;

[0041] (2) The steam-containing flue gas obtained in step (1) is filtered and dust-removed by a dust filter device, returned to the main flue for further processing, and the dust filter device is purged and dust-removed at regular intervals.

[0042] As a preferred technical solution of the present invention, the position where the bypass flue is led out and returned in step (1) is located between the dust collector and the desulfurization tower on the main flue, preferably between the dust collector and the first induced draft fan.

[0043] Preferably, the temperature of the flue gas at the outlet of the dust collector is 90-100°C, such as 90°C, 92°C, 94°C, 95°C, 96°C, 98°C or 100°C, and the flue gas volume is 2.7 to 3.2 million Nm 3 / h, for example 2.7 million Nm 3 / h, 2.8 million Nm 3 / h, 2.9 million Nm 3 / h、3 million Nm 3 / h, 3.1 million Nm 3 / h or 3.2 million Nm 3 / h, etc., the smoke moisture content is 5-10%, for example 5%, 6%, 7%, 8%, 9% or 10%, etc.; but it is not limited to the listed values, and other unlisted values ​​within the respective numerical ranges are also applicable. The smoke moisture content is the volume content of water vapor.

[0044] Preferably, a first isolation valve is provided on the main flue between the outlet and return positions of the bypass flue, and the first isolation valve is closed when flue gas is introduced into the bypass pipeline.

[0045] Preferably, a second isolation valve and a third isolation valve are respectively provided on the bypass flue before and after the evaporation and curing device. When flue gas is introduced into the bypass flue, both are opened, and when the bypass flue is in a non-operating state, fails or is under maintenance, both are closed.

[0046] As a preferred technical solution of the present invention, the power plant wastewater in step (1) has been pretreated and concentrated before evaporation and solidification.

[0047] Preferably, the power plant wastewater is concentrated and stored in a wastewater tank, and then filtered and transported by a wastewater pump to the atomizing spray device in the evaporation and curing device.

[0048] Preferably, the mass concentration of the concentrated power plant waste water in step (1) is 10-20wt%, for example, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable; the flow rate is 8-12t / h, for example, 8t / h, 8.5t / h, 9t / h, 9.5t / h, 10t / h, 10.5t / h, 11t / h, 11.5t / h or 12t / h, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0049] Preferably, the atomized spraying of the power plant wastewater in step (1) is achieved by an atomizing nozzle, and the spray angle of the atomizing nozzle is 90 to 120 degrees, for example, 90 degrees, 95 degrees, 100 degrees, 105 degrees, 110 degrees, 115 degrees or 120 degrees, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] As a preferred technical solution of the present invention, the flow rate of the flue gas in the evaporation and curing device in step (1) is 3.5 to 4.0 m / s, for example, 3.5 m / s, 3.6 m / s, 3.7 m / s, 3.8 m / s, 3.9 m / s or 4.0 m / s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] Preferably, the waste heat of the flue gas vaporizes the liquid water in the atomized wastewater into water vapor, and the solute therein forms a solid.

[0052] Preferably, the solidified material in step (1) comprises calcium sulfate, sodium chloride, magnesium sulfate and calcium chloride, which are collected after settling to the ash hopper at the bottom of the evaporation and solidification device.

[0053] In the present invention, according to the source and pre-treatment of the desulfurization wastewater from the power plant, the solidified product after evaporation and solidification includes calcium sulfate, sodium chloride, magnesium sulfate and calcium chloride, wherein the calcium sulfate is mainly in the form of gypsum CaSO 4 ·2H 2O form, which may account for 50-70wt% of the solidified product, such as 50wt%, 55wt%, 60wt%, 65wt% or 70wt%, etc., sodium chloride accounts for 20-30wt%, such as 20wt%, 22wt%, 25wt%, 27wt% or 30wt%, etc., magnesium sulfate accounts for 5-10wt%, such as 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%, etc., sodium chloride accounts for 3-8wt%, such as 3wt%, 4wt%, 5wt%, 6wt%, 7wt% or 8wt%, etc.; the solidified products have their respective applications after subsequent separation.

[0054] As a preferred technical solution of the present invention, the steam-containing flue gas in step (2) carries some solidified matter, which is filtered and dust-removed by a dust filter device and then leaves from the top flue gas outlet and enters the main flue again.

[0055] Preferably, the dust filtering device uses pulse jetting to periodically perform back-blowing cleaning.

[0056] Preferably, the frequency of the pulse blowing is 4 to 10 times / h, for example 4 times / h, 5 times / h, 6 times / h, 7 times / h, 8 times / h, 9 times / h or 10 times / h, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] Preferably, the pulse blowing is carried out using compressed gas, and the pressure of the compressed gas is 0.5-0.7 MPaG, for example, 0.5 MPaG, 0.55 MPaG, 0.6 MPaG, 0.65 MPaG or 0.7 MPaG, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] Preferably, the solidified material obtained by the pulse spraying settles into an ash hopper and is collected together.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The device of the present invention uses the waste heat of flue gas to evaporate and solidify wastewater by setting a bypass flue. By setting an atomizing spray device in the evaporation and solidification device, the difficulty of evaporation and solidification of wastewater is reduced, and the treatment efficiency is improved. The formed solidified matter can be further separated and recovered. The dust filter device can filter out the solidified matter carried in the flue gas to prevent it from entering the main flue, thereby realizing wastewater recovery and zero emission without consuming additional energy and with low treatment cost.

[0061] (2) The bypass flue of the present invention can be removed separately in case of failure or maintenance, thus avoiding the impact on the main flue gas treatment process and equipment;

[0062] (3) The device of the present invention has a simple structure, is easy to maintain and has low operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a schematic diagram of the structure of a device for evaporating and solidifying power plant wastewater using flue gas waste heat provided in Example 1 of the present invention;

[0064] Figure 2 is a schematic structural diagram of an evaporation curing unit provided in Example 1 of the present invention;

[0065] Figure 3 is a schematic structural diagram of an evaporation curing device provided in Example 1 of the present invention;

[0066] Among them, 11-boiler, 12-denitrification device, 13-air preheater, 14-economizer, 15-dust collector, 16-first induced draft fan, 17-desulfurization tower, 18-second induced draft fan, 19-chimney, 110-first isolating valve, 21-evaporation and curing device, 211-evaporation and curing cylinder, 212-ash hopper, 213-cured material collecting port, 214-smoke inlet, 215-smoke outlet, 22-atomizing spray device, 221-spraying plate, 222-atomizing nozzle, 223-wastewater inlet, 23-dust filtering device, 231-blowing pipe, 232-filter bag, 233-Venturi tube, 234-compressed gas inlet, 235-electromagnetic pulse valve, 24-second isolating valve, 25-third isolating valve, 26-wastewater storage device, 27-wastewater conveying device, 28-filtering device. DETAILED DESCRIPTION

[0067] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0068] The following are typical but non-limiting embodiments of the present invention:

[0069] Embodiment 1:

[0070] This embodiment provides a device for evaporating and solidifying power plant wastewater using flue gas waste heat. The structural schematic diagram of the device is shown in FIG. Figure 1 As shown, it includes a bypass flue leading from the dust collector 15 and the desulfurization tower 17 in the main flue of flue gas treatment, and the bypass flue is provided with an evaporation curing unit. The structural schematic diagram of the evaporation curing unit is shown in Figure 2 As shown, it includes an evaporation curing device 21, a wastewater conveying device 27, an atomization spraying device 22 and a dust filtering device 23. The structural schematic diagram of the evaporation curing device is shown in FIG. Figure 3As shown, the atomizing spray device 22 and the dust filtering device 23 are both located in the upper part of the evaporation and curing device 21, the dust filtering device 23 is located above the atomizing spray device 22, and the wastewater conveying device 27 is connected to the inlet of the atomizing spray device 22; the bypass flue is connected to the lower inlet of the evaporation and curing device 21 after being led out from the main flue of flue gas treatment, and the top outlet of the evaporation and curing device 21 is connected back to the main flue of flue gas treatment; the dust filtering device 23 includes a blowing pipe 231, a filter bag 232 and a venturi tube 233, the blowing pipe 231 is connected to the filter bag 232 via the venturi tube 233, each blowing pipe 231 corresponds to a plurality of groups of filter bags 232 and venturi tubes 233, and the filter bags 232 and the venturi tubes 233 correspond to each other.

[0071] The main flue for flue gas treatment is provided with a denitration device 12, an air preheater 13, an economizer 14, a dust collector 15, a desulfurization tower 17 and a chimney 19 connected to the flue gas outlet of the boiler 11 in sequence.

[0072] The dust collector 15 is an electrostatic dust collector.

[0073] The main flue gas treatment flue is also provided with a first induced draft fan 16 and a second induced draft fan 18 . The first induced draft fan 16 is located on the flue between the dust collector 15 and the desulfurization tower 17 , and the second induced draft fan 18 is located on the flue between the desulfurization tower 17 and the chimney 19 .

[0074] The bypass flue is led out from the main flue between the dust collector 15 and the first induced draft fan 16 .

[0075] A first isolating valve 110 is provided on the connecting flue between the dust collector 15 and the first induced draft fan 16, and a bypass flue is led out from the inlet of the first isolating valve 110. The bypass flue is divided into two sections according to being located before and after the evaporation and curing device 21, namely, a first bypass flue and a second bypass flue.

[0076] The first stage bypass flue is provided with a second isolation valve 24 , and the second stage bypass flue is provided with a third isolation valve 25 .

[0077] The main structure of the evaporation and curing device 21 is an evaporation and curing cylinder 211 , the bottom of the evaporation and curing cylinder 211 is an ash hopper 212 , and the bottom of the ash hopper 212 is provided with a solidified material collecting port 213 .

[0078] The evaporation curing cylinder 211 has a smoke inlet 214 at the bottom and a smoke outlet 215 at the top.

[0079] The atomizing spray device 22 includes a spray plate 221 and an atomizing nozzle 222 . The spray plate 221 is horizontally arranged and includes two of them. Each spray plate 221 is provided with a plurality of atomizing nozzles 222 .

[0080] The spray plates 221 are arranged in parallel and spaced apart, and the atomizing nozzles 222 on two adjacent spray plates 221 are arranged in a staggered manner.

[0081] The atomizing spray device 22 is provided with a wastewater inlet 223 , and the outlet of the wastewater conveying device 27 is connected to the wastewater inlet 223 of the atomizing spray device 22 .

[0082] The spray plate 221 and the atomizing nozzle 222 are both made of polypropylene.

[0083] The blowing pipe 231 of the dust filtering device 23 is provided with a compressed gas inlet 234 , and an electromagnetic pulse valve 235 is provided on the compressed gas inlet 234 pipeline.

[0084] The blowing pipe 231 is connected to a plurality of venturi tubes 233 arranged in parallel, and each venturi tube 233 is connected to a filter bag 232 .

[0085] The filter bag 232 is made of polyphenylene sulfide.

[0086] The wastewater conveying device 27 is a wastewater pump.

[0087] The evaporation curing unit further includes a wastewater storage device 26 , and an outlet of the wastewater storage device 26 is connected to an inlet of a wastewater conveying device 27 .

[0088] A filtering device 28 is further provided between the wastewater storage device 26 and the wastewater conveying device 27 .

[0089] The wastewater storage device 26 is a wastewater tank.

[0090] Embodiment 2:

[0091] The present embodiment provides a device for evaporating and curing wastewater from a power plant by utilizing waste heat from flue gas, the device comprising a bypass flue leading out from between a dust collector 15 and a desulfurization tower 17 in a main flue for flue gas treatment, the bypass flue being provided with an evaporation and curing unit, the evaporation and curing unit comprising an evaporation and curing device 21, a wastewater conveying device 27, an atomizing spraying device 22 and a dust filtering device 23, the atomizing spraying device 22 and the dust filtering device 23 being both located at the upper part of the evaporation and curing device 21, the dust filtering device 23 being located above the atomizing spraying device 22, the wastewater conveying device 27 being disposed ... The delivery device 27 is connected to the inlet of the atomizing spray device 22; the bypass flue is led out from the main flue of flue gas treatment and connected to the lower inlet of the evaporation and curing device 21, and the top outlet of the evaporation and curing device 21 is connected back to the main flue of flue gas treatment; the dust filtering device 23 includes a blowing pipe 231, a filter bag 232 and a venturi tube 233, the blowing pipe 231 is connected to the filter bag 232 via the venturi tube 233, each blowing pipe 231 corresponds to a plurality of groups of filter bags 232 and venturi tubes 233, and the filter bags 232 and the venturi tubes 233 correspond to each other.

[0092] The main flue for flue gas treatment is provided with a denitration device 12, an air preheater 13, an economizer 14, a dust collector 15, a desulfurization tower 17 and a chimney 19 connected to the flue gas outlet of the boiler 11 in sequence.

[0093] The dust collector 15 is an electric bag composite dust collector.

[0094] The main flue gas treatment flue is also provided with a first induced draft fan 16 and a second induced draft fan 18 . The first induced draft fan 16 is located on the flue between the dust collector 15 and the desulfurization tower 17 , and the second induced draft fan 18 is located on the flue between the desulfurization tower 17 and the chimney 19 .

[0095] The bypass flue is led out from the main flue between the dust collector 15 and the first induced draft fan 16 .

[0096] A first isolating valve 110 is provided on the connecting flue between the dust collector 15 and the first induced draft fan 16, and a bypass flue is led out from the inlet of the first isolating valve 110. The bypass flue is divided into two sections according to being located before and after the evaporation and curing device 21, namely, a first bypass flue and a second bypass flue.

[0097] The first stage bypass flue is provided with a second isolation valve 24 , and the second stage bypass flue is provided with a third isolation valve 25 .

[0098] The main structure of the evaporation and curing device 21 is an evaporation and curing cylinder 211 , the bottom of the evaporation and curing cylinder 211 is an ash hopper 212 , and the bottom of the ash hopper 212 is provided with a solidified material collecting port 213 .

[0099] The evaporation curing cylinder 211 has a smoke inlet 214 at the bottom and a smoke outlet 215 at the top.

[0100] The atomizing spray device 22 includes a spray plate 221 and an atomizing nozzle 222 . The spray plate 221 is horizontally arranged and includes one atomizing nozzle 222 . The spray plate 221 is provided with a plurality of atomizing nozzles 222 .

[0101] The atomizing spray device 22 is provided with a wastewater inlet 223 , and the outlet of the wastewater conveying device 27 is connected to the wastewater inlet 223 of the atomizing spray device 22 .

[0102] The spray plate 221 and the atomizing nozzle 222 are both made of polyvinylidene fluoride.

[0103] The blowing pipe 231 of the dust filtering device 23 is provided with a compressed gas inlet 234 , and an electromagnetic pulse valve 235 is provided on the compressed gas inlet 234 pipeline.

[0104] The blowing pipe 231 is connected to a plurality of venturi tubes 233 arranged in parallel, and each venturi tube 233 is connected to a filter bag 232 .

[0105] The filter bag 232 is made of polyacrylonitrile fiber.

[0106] The wastewater conveying device 27 is a wastewater pump.

[0107] The evaporation curing unit further includes a wastewater storage device 26 , and an outlet of the wastewater storage device 26 is connected to an inlet of a wastewater conveying device 27 .

[0108] The wastewater storage device 26 is a wastewater tank.

[0109] Embodiment 3:

[0110] This embodiment provides a method for evaporating and solidifying power plant wastewater using flue gas waste heat. The method is performed using the device in Example 1 and includes the following steps:

[0111] (1) A bypass flue is drawn from the position between the dust collector 15 and the first induced draft fan 16 on the main flue of the power plant flue gas treatment. The temperature of the flue gas at the outlet of the dust collector 15 is 90°C and the flue gas volume is 2.9 million Nm 3 / h, the moisture content of the flue gas is 5.53%, the power plant waste water is pretreated and concentrated, the mass concentration of the concentrated power plant waste water is 10wt%, the flow rate is 10t / h, and then atomization spraying is carried out to contact with the flue gas in countercurrent, the spraying angle during the atomization spraying is 100 degrees, the flow rate of the flue gas in the evaporation and curing device 21 is 3.8m / s, the liquid water in the atomized power plant waste water is vaporized into water vapor by using the waste heat of the flue gas, and the solute therein forms a solid to obtain a solid and flue gas containing steam, the composition of the solid includes calcium sulfate, sodium chloride, magnesium sulfate and calcium chloride, which are collected after settling to the ash hopper 212 at the bottom of the evaporation and curing device 21;

[0112] (2) The steam-containing flue gas obtained in step (1) carries some solidified matter, which is filtered and dust-removed by the dust filter device 23 and then leaves from the top flue gas outlet 215 and returns to the main flue for further processing. The dust filter device uses pulse spraying to periodically perform back-blowing and cleaning. The frequency of the pulse spraying is 6 times / h. The pulse spraying is performed using compressed air with a pressure of 0.5 MPaG. The solidified matter obtained by the pulse spraying settles in the ash hopper 212 for collection.

[0113] In this embodiment, 10 t / h of concentrated wastewater is atomized and sprayed and then heat-exchanged with flue gas, and the residual heat of flue gas is used to vaporize all the liquid water in the wastewater. The heat absorbed by the water vaporization process and the solid matter heating up is: 10000×(1-10%)×(2650.27-83.92)+10000×10%×0.945×(84.36-20)=23.158 GJ / h, and the heat released by the solid matter crystallization process is: 10000×10%×1000 / 138×14=0.101 GJ / h, where (1) 10000 is the flow rate of concentrated desulfurization wastewater in the power plant, in kg. / h; (2) 10wt% is the mass concentration; (3) 2650.27 is the enthalpy of saturated steam at 84.36℃, in kJ / kg, calculated according to IAPWS-IF97 standard; (4) 83.92 is the enthalpy of water at 20℃, in kJ / kg, calculated according to IAPWS-IF97 standard; (5) 0.945 is the average specific heat of the solid substance after evaporation and crystallization, in kJ / (kg·℃); (6) 138 is the average molecular weight of the solid substance after evaporation and crystallization, in g / mol; (7) 14 is the average precipitation heat of the solid substance during crystallization, in kJ / mol.

[0114] The flue gas temperature drop is: (23.158-0.101) / 2900000 / 1.383 / 1.020=5.64℃; (1) 23.158 is the heat absorbed by the water vaporization process and the solid matter heating up, in GJ / h; (2) 0.101 is the heat released by the solid matter crystallization process, in GJ / h; (3) 2900000 is the flue gas volume, in Nm3 / h; (4) 1.383 is the smoke density, unit: kg / Nm 3 ; (5) 1.020 is the average specific enthalpy of flue gas, unit kJ / (kg·℃), calculated according to "Thermal Calculation of Industrial Boiler Design Calculation Methods" 2005.

[0115] According to the smoke moisture content of 5.53%, the volume of water vapor in the smoke is 2900000 × 5.53% = 160370 Nm 3 / h, the steam volume after complete evaporation of 10t / h of wastewater is approximately 10000×(1-10%) / 18×8.314×273.15 / 101.325=11206Nm 3 / h, the moisture content of the flue gas after the wastewater evaporates is (160370+11206) / (2900000+11206)=5.89%, where (1) 18 is the molar mass of water, in g / mol; (2) 8.314 is the universal gas constant, in J / (mol·K); (3) 273.15 is the thermodynamic temperature, in K; (4) 101.325 is the gas pressure, in kPa.

[0116] After the above treatment, the flue gas temperature dropped from 90℃ to 84.36℃, and the flue gas moisture content increased from 5.53% to 5.89%; after cooling, the flue gas temperature is still higher than the water dew point of the flue gas (about 34.7℃, calculated according to Dalton's partial pressure law and "Thermal Calculation of Industrial Boiler Design Calculation Methods" 2005), and the concentrated wastewater is evaporated and solidified by using the waste heat of the flue gas, which can completely absorb the concentrated wastewater generated by the desulfurization unit.

[0117] Embodiment 4:

[0118] This embodiment provides a method for evaporating and solidifying power plant wastewater using flue gas waste heat. The method is performed using the device in Example 1 and includes the following steps:

[0119] (1) A bypass flue is drawn from the position between the dust collector 15 and the first induced draft fan 16 on the main flue of the power plant flue gas treatment. The outlet flue gas temperature of the dust collector 15 is 95°C and the flue gas volume is 3 million Nm 3 / h, the moisture content of the flue gas is 7%, the power plant waste water is pretreated and concentrated, the mass concentration of the concentrated power plant waste water is 15wt%, the flow rate is 12t / h, and then atomization spraying is carried out to contact with the flue gas in countercurrent, the spraying angle during the atomization spraying is 90 degrees, the flow rate of the flue gas in the evaporation and curing device 21 is 3.5m / s, the liquid water in the atomized power plant waste water is vaporized into water vapor by using the flue gas waste heat, and the solute therein forms a solid to obtain a solid and flue gas containing steam, the solid composition includes calcium sulfate, sodium chloride, magnesium sulfate and calcium chloride, which are collected after settling to the ash hopper 212 at the bottom of the evaporation and curing device 21;

[0120] (2) The steam-containing flue gas obtained in step (1) carries some solidified matter, which is filtered and dust-removed by the dust filter device 23 and then leaves from the top flue gas outlet 215 and returns to the main flue for further processing. The dust filter device uses pulse spraying to periodically perform back-blowing and dust cleaning. The frequency of the pulse spraying is 8 times / h. The pulse spraying is performed using compressed air with a pressure of 0.6 MPaG. The solidified matter obtained by the pulse spraying settles in the ash hopper 212 for collection.

[0121] In this embodiment, 12 t / h of concentrated wastewater is atomized and sprayed and then heat-exchanged with flue gas, and the residual heat of flue gas is used to vaporize all the liquid water in the wastewater. The heat absorbed by the water vaporization process and the solid matter during heating is: 12000×(1-15%)×(2657.61-83.92)+12000×15%×0.945×(88.83-20)=26.369 GJ / h, and the heat released by the solid matter crystallization process is: 12000×15%×1000 / 138×14=0.183 GJ / h, where (1) 12000 is the flow rate of concentrated desulfurization wastewater in the power plant, in kg. / h; (2) 15wt% is the mass concentration; (3) 2657.61 is the enthalpy of saturated steam at 88.83℃, in kJ / kg, calculated according to IAPWS-IF97 standard; (4) 83.92 is the enthalpy of water at 20℃, in kJ / kg, calculated according to IAPWS-IF97 standard; (5) 0.945 is the average specific heat of the solid substance after evaporation and crystallization, in kJ / (kg·℃); (6) 138 is the average molecular weight of the solid substance after evaporation and crystallization, in g / mol; (7) 14 is the average precipitation heat of the solid substance during crystallization, in kJ / mol.

[0122] The flue gas temperature drop is: (26.369-0.183) / 3000000 / 1.374 / 1.029=6.17℃; (1) 26.369 is the heat absorbed by the water vaporization process and the solid matter heating up, unit GJ / h; (2) 0.183 is the heat released by the solid matter crystallization process, unit GJ / h; (3) 3000000 is the flue gas volume, unit Nm3 / h; (4) 1.374 is the smoke density, unit: kg / Nm 3 ; (5) 1.029 is the average specific enthalpy of flue gas, unit kJ / (kg·℃), calculated according to "Thermal Calculation of Industrial Boiler Design Calculation Methods" 2005.

[0123] According to the smoke moisture content of 7%, the volume of water vapor in the smoke is 3000000 × 7% = 210000 Nm 3 / h, the steam volume after complete evaporation of 12t / h of wastewater is approximately 12000×(1-15%) / 18×8.314×273.15 / 101.325=12701Nm 3 / h, the moisture content of the flue gas after the wastewater evaporates is (210000+12701) / (3000000+12701)=7.39%, where (1) 18 is the molar mass of water, in g / mol; (2) 8.314 is the universal gas constant, in J / (mol·K); (3) 273.15 is the thermodynamic temperature, in K; and (4) 101.325 is the gas pressure, in kPa.

[0124] After the above treatment, the flue gas temperature dropped from 95°C to 88.83°C, and the flue gas moisture content increased from 7% to 7.39%; after cooling, the flue gas temperature is still higher than the water dew point of the flue gas (about 38.9°C, calculated according to Dalton's partial pressure law and "Thermal Calculation of Industrial Boiler Design Calculation Methods" 2005), and the concentrated wastewater is evaporated and solidified by using the flue gas waste heat, which can completely absorb the concentrated wastewater generated by the desulfurization unit.

[0125] Embodiment 5:

[0126] This embodiment provides a method for evaporating and solidifying power plant wastewater using flue gas waste heat. The method is performed using the device in Example 1 and includes the following steps:

[0127] (1) A bypass flue is drawn from the position between the dust collector 15 and the first induced draft fan 16 on the main flue of the power plant flue gas treatment. The outlet flue gas temperature of the dust collector 15 is 100°C and the flue gas volume is 2.8 million Nm 3 / h, the moisture content of the flue gas is 10%, the power plant waste water is pretreated and concentrated, the mass concentration of the concentrated power plant waste water is 20wt%, the flow rate is 9t / h, and then atomization spraying is carried out to contact with the flue gas in countercurrent, the spraying angle during the atomization spraying is 120 degrees, the flow rate of the flue gas in the evaporation and curing device 21 is 4m / s, the liquid water in the atomized power plant waste water is vaporized into water vapor by using the flue gas waste heat, and the solute therein forms a solid to obtain a solid and flue gas containing steam, the solid composition includes calcium sulfate, sodium chloride, magnesium sulfate and calcium chloride, which are collected after settling to the ash hopper 212 at the bottom of the evaporation and curing device 21;

[0128] (2) The steam-containing flue gas obtained in step (1) carries some solidified matter, which is filtered and dust-removed by the dust filter device 23 and then leaves from the top flue gas outlet 215 and returns to the main flue for further processing. The dust filter device uses pulse spraying to periodically perform back-blowing and dust cleaning. The frequency of the pulse spraying is 4 times / h. The pulse spraying is performed using compressed air with a pressure of 0.7 MPaG. The solidified matter obtained by the pulse spraying settles in the ash hopper 212 for collection.

[0129] In this embodiment, 9 t / h of concentrated wastewater is atomized and sprayed and then heat-exchanged with flue gas, and the residual heat of flue gas is used to vaporize all the liquid water in the wastewater. The heat absorbed by the water vaporization process and the solid matter heating up is: 9000×(1-20%)×(2668.14-83.92)+9000×20%×0.945×(95.33-20)=18.735 GJ / h, and the heat released by the solid matter crystallization process is: 9000×20%×1000 / 138×14=0.183 GJ / h, where (1) 9000 is the flow rate of concentrated desulfurization wastewater in the power plant, in kg / h ; (2) 20wt% is the mass concentration; (3) 2668.14 is the enthalpy of saturated steam at 95.33℃, in kJ / kg, calculated according to IAPWS-IF97 standard; (4) 83.92 is the enthalpy of water at 20℃, in kJ / kg, calculated according to IAPWS-IF97 standard; (5) 0.945 is the average specific heat of solid matter after evaporation and crystallization, in kJ / (kg·℃); (6) 138 is the average molecular weight of solid matter after evaporation and crystallization, in g / mol; (7) 14 is the average precipitation heat of solid matter crystallization process, in kJ / mol.

[0130] The flue gas temperature drop is: (18.735-0.183) / 2800000 / 1.355 / 1.047=4.67℃; (1) 18.735 is the heat absorbed by the water vaporization process and the solid matter heating up, in GJ / h; (2) 0.183 is the heat released by the solid matter crystallization process, in GJ / h; (3) 2800000 is the flue gas volume, in Nm 3 / h; (4) 1.355 is the smoke density, unit: kg / Nm 3 ; (5) 1.047 is the average specific enthalpy of flue gas, unit kJ / (kg·℃), calculated according to "Thermal Calculation of Industrial Boiler Design Calculation Methods" 2005.

[0131] According to the smoke moisture content of 10%, the volume of water vapor in the smoke is 2800000×10%=280000Nm 3 / h, the steam volume after complete evaporation of 9t / h of wastewater is approximately 9000×(1-20%) / 18×8.314×273.15 / 101.325=8965Nm 3 / h, the moisture content of the flue gas after the wastewater evaporates is (280000+8965) / (2800000+8965)=10.29%, where (1) 18 is the molar mass of water, in g / mol; (2) 8.314 is the universal gas constant, in J / (mol·K); (3) 273.15 is the thermodynamic temperature, in K; and (4) 101.325 is the gas pressure, in kPa.

[0132] After the above treatment, the flue gas temperature is reduced from 100℃ to 95.33℃, and the moisture content of the flue gas is increased from 10% to 10.29%; after cooling, the flue gas temperature is still higher than the water dew point of the flue gas (about 45.2℃, calculated according to Dalton's partial pressure law and "Thermal Calculation of Industrial Boiler Design Calculation Methods" 2005), and the concentrated wastewater is evaporated and solidified by using the waste heat of the flue gas, which can completely absorb the concentrated wastewater generated by the desulfurization unit.

[0133] Based on the above embodiments, it can be concluded that the device of the present invention uses the waste heat of flue gas to evaporate and solidify the wastewater by setting a bypass flue, and by setting an atomizing spray device in the evaporation and solidification device, the difficulty of evaporation and solidification of the wastewater is reduced, the treatment efficiency is improved, and the formed solidified material can be further separated and recovered, while the setting of the dust filter device can filter out the solidified material carried in the flue gas to avoid entering the main flue, thereby realizing the recovery and zero emission of wastewater without additional energy consumption and low treatment cost; the setting of the bypass flue can be removed separately in case of failure or maintenance to avoid affecting the main process and equipment of flue gas treatment; the device has a simple structure, convenient maintenance and low operating cost.

[0134] The applicant declares that the present invention uses the above embodiments to illustrate the detailed devices and methods of the present invention, but the present invention is not limited to the above detailed devices and methods, that is, it does not mean that the present invention must rely on the above detailed devices and methods to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the device of the present invention, addition of auxiliary devices, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A device for evaporating and solidifying power plant wastewater using flue gas waste heat, characterized in that: The device comprises a bypass flue leading out from between a dust collector and a desulfurization tower in a main flue of flue gas treatment, wherein an evaporation and curing unit is arranged on the bypass flue, wherein the evaporation and curing unit comprises an evaporation and curing device, a wastewater conveying device, an atomizing spraying device and a dust filtering device, wherein the atomizing spraying device and the dust filtering device are both located at the upper part of the evaporation and curing device, wherein the dust filtering device is located above the atomizing spraying device, and wherein the wastewater conveying device is connected to the inlet of the atomizing spraying device; wherein the bypass flue is connected to the lower inlet of the evaporation and curing device after being led out from the main flue of flue gas treatment, and wherein the top outlet of the evaporation and curing device is connected back to the main flue of flue gas treatment; wherein the dust filtering device comprises a blowing pipe, a filter bag and a venturi tube, wherein the blowing pipe is connected to the filter bag via the venturi tube, wherein each blowing pipe corresponds to a plurality of groups of filter bags and venturi tubes, and wherein the filter bags and the venturi tubes correspond to one another.

2. The device according to claim 1, characterized in that The main flue gas treatment flue is provided with a denitration device, an air preheater, an economizer, a dust collector, a desulfurization tower and a chimney connected to the boiler flue gas outlet in sequence; Preferably, the dust collector includes any one of an electrostatic precipitator, a bag dust collector or an electrostatic bag composite dust collector; Preferably, the main flue gas treatment flue is further provided with a first induced draft fan and a second induced draft fan, wherein the first induced draft fan is located on the flue between the dust collector and the desulfurization tower, and the second induced draft fan is located on the flue between the desulfurization tower and the chimney; Preferably, the bypass flue is led out from the main flue between the dust collector and the first induced draft fan; Preferably, a first isolation valve is provided on the connecting flue between the dust collector and the first induced draft fan, and a bypass flue is led out from the inlet of the first isolation valve, and the bypass flue is divided into two sections according to being located before and after the evaporation and curing device, namely, a first bypass flue and a second bypass flue; Preferably, the first-stage bypass flue is provided with a second isolation valve, and the second-stage bypass flue is provided with a third isolation valve.

3. The device according to claim 1 or 2, characterized in that: The main structure of the evaporation curing device is an evaporation curing cylinder, the bottom of the evaporation curing cylinder is an ash hopper, and the bottom of the ash hopper is provided with a solidified material collecting port; Preferably, a smoke inlet is provided at the bottom of the evaporation curing cylinder, and a smoke outlet is provided at the top; Preferably, the atomizing spray device comprises a spray plate and an atomizing nozzle, the spray plate is horizontally arranged, and comprises at least one, and each spray plate is provided with a plurality of atomizing nozzles; Preferably, when the spray discs include two or more, the spray discs are arranged in parallel and spaced apart, and the atomizing nozzles on two adjacent spray discs are arranged in a staggered manner; Preferably, the atomizing spray device is provided with a wastewater inlet, and the outlet of the wastewater conveying device is connected to the wastewater inlet of the atomizing spray device; Preferably, the spray plate and the atomizing nozzle are independently made of any one of polypropylene, polyvinylidene fluoride, ABS plastic, stainless steel, fiberglass or silicon carbide, or a combination of at least two thereof.

4. The device according to any one of claims 1 to 3, characterized in that: The blowing pipe of the dust filter device is provided with a compressed gas inlet, and an electromagnetic pulse valve is provided on the compressed gas inlet pipeline; Preferably, the blowing pipe is connected to a plurality of venturi tubes arranged in parallel, and each venturi tube is connected to a filter bag; Preferably, the material of the filter bag includes any one of polyphenylene sulfide, aramid fiber or polyacrylonitrile fiber, or a combination of at least two of them.

5. The device according to any one of claims 1 to 4, characterized in that: The wastewater conveying device comprises a wastewater pump; Preferably, the evaporation curing unit further comprises a wastewater storage device, and the outlet of the wastewater storage device is connected to the inlet of the wastewater conveying device; Preferably, a filtering device is further provided between the wastewater storage device and the wastewater conveying device; Preferably, the wastewater storage device comprises a wastewater tank.

6. A method for evaporating and solidifying power plant wastewater using the device according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) A bypass flue is drawn from the main flue of the power plant flue gas treatment, and the concentrated power plant wastewater is contacted with the flue gas in countercurrent through atomization spraying, and the waste heat of the flue gas is used to evaporate and solidify the power plant wastewater to obtain a solidified product and flue gas containing steam; (2) The steam-containing flue gas obtained in step (1) is filtered and dust-removed by a dust filter device, and returned to the main flue for further processing, and the dust filter device is purged and dust-removed in a timely manner.

7. The method according to claim 6, characterized in that The position where the bypass flue is led out and returned in step (1) is located between the dust collector and the desulfurization tower on the main flue, preferably between the dust collector and the first induced draft fan; Preferably, the temperature of the flue gas at the outlet of the dust collector is 90-100°C, and the flue gas volume is 2.7-3.2 million Nm 3 / h, the humidity content of flue gas is 5-10%; Preferably, a first isolation valve is provided on the main flue between the outlet and return positions of the bypass flue, and when the bypass pipeline introduces flue gas, the first isolation valve is closed; Preferably, a second isolation valve and a third isolation valve are respectively provided on the bypass flue before and after the evaporation and curing device. When flue gas is introduced into the bypass flue, both are opened, and when the bypass flue is in a non-operating state, fails or is under maintenance, both are closed.

8. The method according to claim 6 or 7, characterized in that: The power plant wastewater in step (1) has been pre-treated and concentrated before evaporation and solidification; Preferably, the power plant wastewater is concentrated and stored in a wastewater tank, and then filtered and transported by a wastewater pump to the atomizing spray device in the evaporation and curing device; Preferably, the mass concentration of the concentrated power plant wastewater in step (1) is 10-20wt% and the flow rate is 8-12t / h; Preferably, the atomized spraying of the power plant wastewater in step (1) is achieved by an atomizing nozzle, and the spraying angle of the atomizing nozzle is 90 to 120 degrees.

9. The method according to any one of claims 6 to 8, characterized in that: The flow rate of the flue gas in the evaporation and curing device in step (1) is 3.5-4.0 m / s; Preferably, the flue gas waste heat vaporizes the liquid water in the atomized wastewater into water vapor, and the solute therein forms a solid; Preferably, the solidified material in step (1) comprises calcium sulfate, sodium chloride, magnesium sulfate and calcium chloride, which are collected after settling to the ash hopper at the bottom of the evaporation and solidification device.

10. The method according to any one of claims 6 to 9, characterized in that: The steam-containing flue gas in step (2) carries part of the solidified matter, which is filtered and dusted by the dust filter device and then leaves from the flue gas outlet at the top and enters the main flue again; Preferably, the dust filtering device uses pulse jetting to periodically perform back-blowing and dust cleaning; Preferably, the frequency of the pulse jet is 4 to 10 times / h; Preferably, the pulse spraying is performed using compressed gas, and the pressure of the compressed gas is 0.5-0.7 MPaG; Preferably, the solidified material obtained by the pulse spraying settles into an ash hopper and is collected together.

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