A wastewater treatment system and wastewater treatment method for a thermal power plant

Abstract

The invention discloses a wastewater treatment system for a thermal power plant, comprising a coal-fired boiler (11) of the thermal power plant, a flue gas denitration device (12), an air preheater (13), an electrostatic precipitator (5), a desulfurization tower (7) and a wastewater collection header (2), comprising an atomizing medium introduction device (1), a wastewater concentration and reduction device (3) and a wastewater atomization evaporation device (4). The wastewater collection header (2) is connected to the wastewater concentration and reduction device (3), so that the thermal power plant wastewater in the wastewater collection header (2) is passed into the wastewater concentration and reduction device (3). The wastewater concentration and reduction device (3) and the atomizing medium introduction device (1) are respectively connected to the wastewater atomization evaporation device (4), so that the flue gas, steam or compressed air atomizing medium introduced by the atomizing medium introduction device (1) and the concentrated and reduced wastewater output from the wastewater concentration and reduction device (3) enter the wastewater atomization evaporation device (4). The wastewater atomization evaporation device (4) is connected to the electrostatic precipitator (5).

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment in thermal power plants, and in particular relates to a wastewater treatment system and a wastewater treatment method in thermal power plants. Background Art

[0002] Since my country has abundant coal resources, and coal-fired power generation is reliable and has mature technology, coal-fired power generation has long been the main source of energy supply in my country. However, various wastewaters are generated during the operation of coal-fired power plants, mainly including desulfurization wastewater, circulating cooling system sewage, acid and alkali wastewater, and domestic sewage. Among them, desulfurization wastewater has become one of the most difficult wastewaters to treat in coal-fired power plants due to its complex composition and many types of pollutants. At present, desulfurization wastewater is mainly treated by chemical precipitation, but this process also has the disadvantages of difficulty in meeting some water quality indicators, and the high salt content of the treated water, and direct discharge is prone to secondary pollution. In recent years, many scholars at home and abroad have conducted relevant research reports, and many new treatment technologies have been introduced into desulfurization wastewater treatment.

[0003] Domestic patent 201711495164.6 discloses a low-energy consumption anti-blocking atomizing spray device, in which an internal nozzle seat is provided with a dual-fluid nozzle, and the device uses two flow channels of liquid and gas and a nozzle sleeve at the outlet of the atomizing mixing chamber to achieve the best atomization effect of the liquid. However, its internal mechanical structure is too complicated, and the dual-fluid nozzle set in the internal nozzle seat is prone to blockage, making the mechanical processing and assembly of the entire device extremely difficult. Summary of the invention

[0004] An object of the present invention is to provide a wastewater treatment system and a wastewater treatment method for a thermal power plant, which can utilize boiler flue gas, high-temperature steam waste heat from extraction and MVR to evaporate wastewater and achieve wastewater concentration and reduction.

[0005] Specifically, the present invention is achieved through the following technical solutions:

[0006] A wastewater treatment system for a thermal power plant comprises a coal-fired boiler of the thermal power plant, a flue gas denitration device, an air preheater, an electrostatic precipitator, a desulfurization tower and a wastewater collecting manifold, comprising an atomizing medium introducing device, a wastewater concentrating and reducing device and a wastewater atomizing evaporating device. The wastewater collecting manifold is connected with the wastewater concentrating and reducing device so that the thermal power plant wastewater in the wastewater collecting manifold is passed into the wastewater concentrating and reducing device. The wastewater concentrating and reducing device and the atomizing medium introducing device are respectively connected with the wastewater atomizing evaporating device so that the flue gas, steam or compressed air atomizing medium introduced by the atomizing medium introducing device and the concentrated and reduced wastewater output from the wastewater concentrating and reducing device enter into the wastewater atomizing evaporating device. The wastewater atomizing evaporating device is connected with the electrostatic precipitator.

[0007] Preferably, the wastewater atomizing evaporation device comprises an atomizing nozzle array, a concentrated wastewater inlet pipe and an atomizing chemical inlet pipe, the atomizing nozzle array is installed in the wastewater atomizing evaporation device, and the wastewater atomizing evaporation device is installed as a whole in the flue of the boiler of a thermal power plant.

[0008] Preferably, the atomizing nozzle array is composed of a plurality of atomizing nozzle units arranged at intervals.

[0009] Preferably, the atomizing nozzle unit comprises a concentrated wastewater inlet, one or more atomizing medium inlets and an atomizing nozzle.

[0010] Preferably, the atomizing medium in the atomizing medium introduction device is any one or any combination of boiler high-temperature flue gas, power plant high-temperature steam or compressed air.

[0011] Preferably, the wastewater concentration and reduction device includes a wastewater evaporation section and a gas-water separator, the wastewater evaporation section is respectively connected to the gas-water separator and the wastewater collecting manifold, and the gas-water separator is also respectively connected to the desulfurization tower and the power plant thermal system and the recycled water system.

[0012] Preferably, the wastewater evaporation section includes any one or a combination of a wastewater flue evaporation section, a wastewater high-temperature steam evaporation section or a wastewater MVR evaporation section.

[0013] Preferably, the water vapor obtained by evaporating the wastewater in the wastewater evaporation section is recovered according to its temperature, pressure or composition and enters the steam header, deaerator, condenser or industrial water tank or other thermal system inlet of the thermal power plant.

[0014] A method for treating wastewater from a thermal power plant, the method comprising:

[0015] S1: The wastewater collection manifold collects the desulfurization wastewater discharged from the desulfurization tower, or other industrial wastewater generated in thermal power plants;

[0016] S2: The wastewater treatment control module determines the type of concentration and reduction device into which the wastewater flows according to the amount, temperature and pressure of the wastewater collected by the wastewater collection header, and generates concentrated and reduced wastewater;

[0017] S3: The wastewater treatment control module controls the water pump to send the concentrated and reduced wastewater into the wastewater atomization evaporation device;

[0018] S4: The wastewater treatment control system controls the opening of the concentrated wastewater inlet valve on each atomizing nozzle unit in the atomizing nozzle array according to the amount of concentrated wastewater generated, and distributes the concentrated wastewater flow rate flowing through each atomizing nozzle unit;

[0019] S5: The wastewater treatment control system determines the pressure, temperature and flow rate of the introduced high-temperature flue gas and / or high-temperature steam and / or compressed air according to the concentrated wastewater flow rate of the concentrated wastewater inlet of each atomizing nozzle unit, so that the wastewater atomized particles entering the flue from the atomizing nozzle outlet of each atomizing nozzle unit meet the standards;

[0020] S6: The wastewater treatment control system monitors the temperature and humidity parameters of the flue gas between the wastewater atomization evaporation device and the electrostatic precipitator, and starts and stops the wastewater atomization evaporation device according to the temperature and humidity parameters.

[0021] Preferably, the wastewater treatment control system controls the wastewater flow temperature, flue gas and / or high-temperature steam and / or compressed air flow temperature to satisfy the following calculation formula:

[0022] Fwastewater*[Cpwater*(Tmixed-T0water)+qlatent heat of vaporization]>Fsmoke*Cpsmoke*(Tsmoke-Tmixed)+Fsteam*Cpsteam*(Tsteam-Tmixed)+Fair*Cpair*(Tair-Tmixed).

[0023] The beneficial effects of the present invention are as follows: (1) The wastewater is concentrated and reduced by utilizing the flue gas from the boiler, the waste heat from the high-temperature steam from the extraction, and the MVR to evaporate the wastewater. (2) The atomized particles of the concentrated wastewater are made small in diameter by utilizing a gas-liquid mixing nozzle with a simple structure, thereby ensuring that the concentrated wastewater is completely evaporated before entering the electrostatic precipitator in the flue. (3) The water vapor or water recovered from the wastewater concentration and reduction is returned to the thermal system or the water recovery system of the power plant, thereby realizing the efficient recovery of the working fluid or heat. (4) The system can achieve zero discharge of wastewater from thermal power plants such as desulfurization wastewater, thus providing a solution for energy conservation and emission reduction in thermal power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of a wastewater treatment system for a thermal power plant provided in a first embodiment of the present invention;

[0026] Figure 2 A schematic diagram of an atomizing nozzle array provided by the present invention;

[0027] Figure 3 A first schematic diagram of the atomizing nozzle provided by the present invention;

[0028] Figure 4 A second schematic diagram of the atomizing nozzle provided by the present invention;

[0029] Figure 5 A third schematic diagram of the atomizing nozzle provided by the present invention;

[0030] Figure 6 A first schematic diagram of a wastewater treatment system for a thermal power plant provided by the present invention;

[0031] Figure 7 A second schematic diagram of a wastewater treatment system for a thermal power plant provided by the present invention;

[0032] Figure 8 A third schematic diagram of a wastewater treatment system for a thermal power plant provided by the present invention;

[0033] Fig. 9 A fourth schematic diagram of a wastewater treatment system for a thermal power plant provided by the present invention;

[0034] Fig.10 It is the relationship curve between the atomized droplet size and the evaporation time;

[0035] Fig.11 It is a schematic diagram of the angle (15-90 degrees) between the incident angle of the high-temperature flue gas inlet and the working fluid inlet and the central axis of the atomizing mixing chamber.

[0036] Description of Reference Numerals

[0037] In order to further clearly illustrate the structure of the present invention and the connection relationship between the various components, the following figure numbers are given and explained.

[0038] Atomizing medium introduction device 1; coal-fired boiler 11 of thermal power plant; flue gas denitration equipment 12; air preheater 13; wastewater collection header 2; wastewater concentration and reduction device 3; wastewater flue evaporation section 311; wastewater high-temperature steam evaporation section 312; MVR evaporation section 313; first conduction valve 314; second conduction valve 315; third conduction valve 316; water pump 33; wastewater atomization evaporation device 4; atomization nozzle array 41; atomization nozzle unit 411; concentrated wastewater introduction port 411a; High-temperature flue gas inlet 411b; atomizing mixing chamber 411c; nozzle 411d; first atomizing fluid inlet 411e; nozzle 411f; working fluid introduction pipe 411g; wastewater circulation pipe 411h; first atomizing fluid inlet 411i; first atomizing fluid inlet 411j; second atomizing fluid inlet pipe 411k; concentrated wastewater introduction pipe 42; atomizing fluid introduction pipe 43; electrostatic precipitator 5; desulfurization tower 7; power plant thermal system 81; recycled water system 82.

[0039] Through the above-mentioned description of the accompanying drawings, combined with the embodiments of the present invention, the technical solution of the present invention can be more clearly understood and explained. DETAILED DESCRIPTION

[0040] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0041] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0042] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0043] The present invention will be described in detail below through examples.

[0044] Embodiment 1

[0045] A wastewater treatment system for a thermal power plant, such as Figure 1As shown, it includes a coal-fired boiler 11 of a thermal power plant, a flue gas denitration device 12, an air preheater 13, an electrostatic precipitator 5, a desulfurization tower 7 and a wastewater collection header 2. The coal-fired boiler 11 of the thermal power plant, the flue gas denitration device 12 and the air preheater 13 are connected in sequence. The coal-fired boiler 11 of the thermal power plant burns coal to generate flue gas. After the flue gas is denitrated by the flue gas denitration device 12, it is preheated in the air preheater 13. The wastewater treatment system of the thermal power plant also includes an atomizing chemical introduction device 1, a wastewater concentration and reduction device 3, and a wastewater atomization and evaporation device. 4, the wastewater collecting manifold 2 is connected with the wastewater concentrating and reducing device 3, so that the thermal power plant wastewater in the wastewater collecting manifold 2 passes into the wastewater concentrating and reducing device 3, the wastewater concentrating and reducing device 3 and the atomizing medium introducing device 1 are respectively connected with the wastewater atomizing and evaporating device 4, so that the atomizing medium such as flue gas, steam or compressed air introduced by the atomizing medium introducing device 1 and the concentrated and reduced wastewater output from the wastewater concentrating and reducing device 3 enter the wastewater atomizing and evaporating device 4, and the wastewater atomizing and evaporating device 4 is connected with the electrostatic precipitator 5. The wastewater collecting manifold 2 collects wastewater from a thermal power plant. The wastewater from the thermal power plant is concentrated and reduced by the wastewater concentration and reduction device 3. The concentrated wastewater output by the wastewater concentration and reduction device 3 is introduced into the wastewater atomization and evaporation device 4. The concentrated and reduced wastewater in the wastewater atomization and evaporation device 4 is atomized at high temperature by the atomized medium output by the atomization medium introduction device 1 to produce completely vaporized wastewater droplets. The vaporized wastewater droplets are then subjected to an electrostatic precipitator 5 to eliminate the vaporized wastewater droplets, thereby achieving zero discharge of wastewater from the thermal power plant. The wastewater concentration and reduction device 3 obtains water vapor by evaporating the wastewater. The control system selects to recycle the water vapor into the steam collecting manifold, deaerator, condenser, industrial water tank or other thermal system inlet according to the temperature, pressure and composition of the water vapor.

[0046] Specifically, Figure 2 As shown, the wastewater atomizing evaporation device 4 includes an atomizing nozzle array 41, a concentrated wastewater inlet pipe 42 and an atomizing medium inlet pipe 43. The atomizing nozzle array 41 is installed in the wastewater atomizing evaporation device 4, and the wastewater atomizing evaporation device 4 is installed as a whole in the flue of the boiler of the thermal power plant.

[0047] Specifically, the atomizing nozzle array 41 is composed of a plurality of atomizing nozzle units 411 arranged at intervals.

[0048] Specifically, the atomizing nozzle unit 411 includes a concentrated wastewater inlet, one or more atomizing first atomizing medium inlets and an atomizing nozzle.

[0049] Specifically, Figure 3As shown, the atomizing nozzle unit 411 includes a concentrated wastewater inlet 411a, a high-temperature flue gas inlet 411b, an atomizing mixing chamber 411c and a nozzle 411d. The concentrated wastewater inlet 411a is connected to one end of the atomizing mixing chamber 411c, the high-temperature flue gas inlet 411b is arranged on the side wall of the atomizing mixing chamber 411c and is connected, and the nozzle 411d is connected to the other end of the atomizing mixing chamber 411c.

[0050] Furthermore, the atomizing nozzle unit 411 further includes a first atomizing chemical inlet 411e, which is disposed on a side wall of the atomizing mixing chamber 411c and communicates with the atomizing mixing chamber 411c.

[0051] Specifically, the atomizing medium in the atomizing medium introduction device is any one or any combination of boiler high-temperature flue gas, power plant high-temperature steam or compressed air.

[0052] Further, the wastewater concentration and reduction device 3 includes a wastewater evaporation part and a gas-water separator, the wastewater evaporation part is connected to the gas-water separator and the wastewater collection manifold 2 respectively, and the gas-water separator is also connected to the desulfurization tower 7 and the thermal system 81 of the power plant and the water recovery system 82 respectively. The wastewater collection manifold 2 inputs the wastewater into the wastewater flue evaporation part for evaporation to generate new gas and concentrated and reduced wastewater, the new gas is introduced into the gas-water separator, the separated gas is introduced into the desulfurization tower 7, the water or water vapor is recycled into the thermal system 81 of the power plant or the water recovery system 82 according to the temperature, pressure and components, and a water pump 33 is also arranged between the wastewater concentration and reduction device 3 and the wastewater atomization evaporation device 4, and the concentrated and reduced wastewater is input into the wastewater atomization evaporation device 4 through the water pump 33.

[0053] Further, such as Figure 6 to Figure 8 As shown, the wastewater evaporation section includes any one or a combination of a wastewater flue evaporation section 311 , a wastewater high-temperature steam evaporation section 312 or a wastewater MVR evaporation section 313 .

[0054] Furthermore, the water vapor obtained by evaporating the wastewater in the wastewater evaporation section is recovered according to its temperature, pressure or composition and enters the steam header, deaerator, condenser or industrial water tank of the thermal power plant or other thermal system inlet.

[0055] Furthermore, the wastewater treatment system of the thermal power plant also includes a wastewater treatment control module, which includes multiple temperature sensors, multiple pressure sensors, multiple flow sensors and control valves. The control valve is used to control the wastewater flow, and the temperature sensor, pressure sensor and flow sensor are used to obtain the wastewater temperature, wastewater pressure and wastewater flow respectively. In the wastewater collection manifold 6, a wastewater collection tank water volume sensor, a wastewater collection tank temperature sensor and a wastewater collection tank water pressure sensor are set, which are used to collect the water volume, temperature and pressure of the wastewater respectively. An inlet pipe flow sensor is set on the wastewater inlet pipe, a nozzle valve is set on each atomizing nozzle unit 411, a nozzle flow sensor is set on each atomizing nozzle unit 411, and a gas pressure sensor, a gas temperature sensor and a gas flow sensor are set in the atomizing mixing chamber 411c.

[0056] Further, such as Fig. 9 As shown, the wastewater concentration and reduction device 3 also includes a first conduction valve 314, a second conduction valve 315 and a third conduction valve 316. The first conduction valve 314 can conduct the water outlet of the wastewater collecting manifold 2 and the water inlet passage of the wastewater flue evaporation part 311, the wastewater high-temperature steam evaporation part 312, and the MVR evaporation part 313 under control; the second conduction valve 315 can conduct the passage between the concentrated and reduced wastewater outlet of the wastewater flue evaporation part 311, the wastewater high-temperature steam evaporation part 312, and the MVR evaporation part 313 and the water pump 33 under control; the third conduction valve 316 can conduct the passage between the evaporation gas outlet of the wastewater flue evaporation part 311, the wastewater high-temperature steam evaporation part 312, and the MVR evaporation part 313 and the gas-water separator 32 under control.

[0057] Embodiment 2

[0058] like Figure 3 As shown, the wastewater atomizing nozzle unit 411 includes a shell, the interior of the shell is hollow to form an atomizing mixing chamber 411c, the atomizing mixing chamber 411c is provided with a concentrated wastewater inlet 411a, a high-temperature flue gas inlet 411b and a first atomizing medium inlet 411e, the outlet end of the atomizing mixing chamber 411c gradually narrows and is provided with a nozzle 411f, the other end of the nozzle 411f is connected to a spray nozzle 411d, and the spray nozzle 411d gradually widens from the nozzle 411f to the outside. The wastewater atomizing nozzle unit 411 adopts any one of a pressure atomizing nozzle, a rotary atomizing nozzle, a pneumatic atomizing nozzle, an ultrasonic or whistle atomizing nozzle.

[0059] The concentrated wastewater inlet 411a is located on the central axis of the atomizing mixing chamber 411c and is connected to the concentrated wastewater inlet pipe 42. The concentrated wastewater enters the wastewater atomizing nozzle unit 411 through the concentrated wastewater inlet 411a to be atomized.

[0060] The high-temperature flue gas inlet 411b is arranged on the side wall of the atomizing mixing chamber 411c and is connected to the atomizing medium inlet pipe 43. The high-temperature flue gas generated by the thermal power plant boiler enters the wastewater atomizing nozzle unit 411 from the atomizing medium inlet pipe 43. The incident angle of the high-temperature flue gas and the central axis of the atomizing mixing chamber 411c are in the range of 15 degrees to 90 degrees. Fig.11 According to the experimental data, the following relationship curve between the atomized droplets and the complete evaporation time in the flue can be obtained, as shown in Fig.10 As shown. The droplet size after atomization is related to the internal structure of the nozzle, the incident angle and flow rate of the fluid entering the atomizing mixing chamber 411c, so the angle between the incident angle of the high-temperature flue gas and the working medium entering the wastewater atomizing nozzle unit 411 and the central axis of the atomizing mixing chamber 411c is adjusted from 15 degrees to 90 degrees. The high-temperature flue gas is drawn from any position after the flue gas denitrification equipment 12 of the coal-fired boiler 11 of the thermal power plant or before or after the air preheater 13.

[0061] Furthermore, the first atomizing medium inlet 411e is provided on the side wall of the atomizing mixing chamber 411c and is connected to the medium introduction pipe 411g. The high-temperature steam or compressed air generated by the boiler of the thermal power plant enters the wastewater atomizing nozzle unit 411 from the first atomizing medium inlet 411e through the medium introduction pipe 411g. The angle between the incident angle of the medium and the central axis of the atomizing mixing chamber 411c is 15 degrees to 90 degrees. Fig.11 The working medium includes at least one of high-temperature flue gas, high-temperature steam and compressed air. The high-temperature steam can be drawn from any one of the main steam of the thermal power plant, high-pressure cylinder extraction steam, high-pressure cylinder exhaust steam, reheat hot section extraction steam, medium-pressure cylinder extraction steam and medium-pressure cylinder exhaust steam.

[0062] Further, the first atomized substance inlet 411e and / or the high-temperature flue gas inlet 411b are equipped with any one of a temperature sensor, a pressure sensor or a flow sensor. The sensor is any one of a resistive, capacitive, inductive, photoelectric, grating, thermoelectric, piezoelectric, infrared, optical fiber, ultrasonic, and laser sensor.

[0063] Furthermore, the first atomizing medium inlet 411e and / or the high-temperature flue gas inlet 411b are provided with a flow regulating valve for regulating and controlling the flow of the medium entering the atomizing mixing chamber 411c. Preferably, the flow regulating valve is a solenoid valve. The solenoid valve is any one of a direct-acting, step-by-step direct-acting, and pilot-operated solenoid valve.

[0064] The wastewater generated by the desulfurization tower 7 in the wastewater treatment system of the thermal power plant is collected in the wastewater collecting manifold 2, concentrated by the wastewater flue evaporation section 311, and the concentrated and reduced wastewater is sent to the concentrated wastewater inlet 411a of the wastewater atomizing nozzle unit 411 in the wastewater atomizing device of the wastewater atomizing evaporation device 4 through the concentrated wastewater inlet pipe 42. The wastewater atomizing nozzle unit 411 uses high-temperature flue gas and high-temperature steam to atomize and concentrate the wastewater, thereby achieving zero discharge of wastewater from the thermal power plant and providing a solution for energy conservation and emission reduction in thermal power plants. Specifically, the wastewater treatment control system controls the flow rate of high-temperature flue gas introduced into the atomizing mixing chamber 411c according to the detected flow rate of concentrated wastewater and the detection data of the temperature sensor and the pressure sensor. At the same time, as needed, the reheat hot section extraction steam is used as the working medium entering the atomizing mixing chamber 411c, and its flow rate is controlled. Under the premise of ensuring that the atomized particles can be completely vaporized and dried in the flue before entering the electrostatic precipitator 5, the total heat brought into the atomizing mixing chamber 411c by the high-temperature steam and flue gas is less than the total heat required for complete evaporation of the concentrated wastewater, that is, the temperature in the atomizing mixing chamber 411c cannot reach the saturation temperature of the concentrated wastewater under the corresponding pressure, thereby preventing the concentrated wastewater from being completely evaporated and vaporized in the atomizing mixing chamber 411c, causing the nozzle 411f to be blocked, thereby avoiding the occurrence of smoke scale or insufficient evaporation.

[0065] Embodiment 3

[0066] like Figure 4 As shown, the wastewater atomizing nozzle unit 411 is composed of a wastewater circulation pipe 411h and a first atomizing medium inlet pipe 411i. The wastewater circulation pipe 411h is cylindrical and has a concentrated wastewater inlet port 411a at one end. The first atomizing medium inlet pipe 411i is provided with a first atomizing medium inlet port 411j. The first atomizing medium inlet pipe 411i is sleeved on the outside of the wastewater circulation pipe 411h. The wastewater circulation pipe 411h and the outlet end of the first atomizing medium inlet pipe 411i together form a spray nozzle 411d.

[0067] The concentrated wastewater inlet 411a is located on the central axis of the wastewater atomizing nozzle unit 411 and is connected to the concentrated wastewater inlet pipe 42. The concentrated wastewater enters the wastewater atomizing nozzle unit 411 through the concentrated wastewater inlet 411a to be atomized.

[0068] The first atomizing medium inlet 411j is inclined and connected to the medium introduction pipe 411g. The incident angle of the medium and the central axis of the atomizing mixing chamber 411c are 15 to 90 degrees. Fig.11As shown. The working medium includes at least one of high-temperature flue gas, high-temperature steam and compressed air. The high-temperature steam is drawn from any one of the main steam, high-pressure cylinder extraction steam, high-pressure cylinder exhaust steam, reheat hot section extraction steam, medium-pressure cylinder extraction steam and medium-pressure cylinder exhaust steam of the thermal power plant. The high-temperature flue gas is drawn from any position after the flue gas denitrification equipment 12 or before the air preheater 13 or after the air preheater 13 of the coal-fired boiler 11 of the thermal power plant.

[0069] The first atomized material inlet 411j is equipped with any one of a temperature sensor, a pressure sensor or a flow sensor. The sensor is any one of a resistive, capacitive, inductive, photoelectric, grating, thermoelectric, piezoelectric, infrared, optical fiber, ultrasonic, and laser sensor.

[0070] Furthermore, the first atomizing medium inlet 411j is provided with a flow regulating valve for regulating and controlling the flow of the medium entering the atomizing mixing chamber 411c. Preferably, the flow regulating valve is a solenoid valve. The solenoid valve is any one of a direct-acting, step-by-step direct-acting, and pilot-operated solenoid valve.

[0071] The industrial wastewater generated in the thermal power plant is collected in the wastewater collection manifold 2, concentrated by the MVR evaporation section 313, and the concentrated and reduced wastewater is sent to the concentrated wastewater inlet 411a in the wastewater atomization device of the wastewater atomization evaporation device 4 through the concentrated wastewater inlet pipe 42. At least one of high-temperature flue gas, high-pressure cylinder exhaust steam, and compressed air is introduced into the wastewater atomization nozzle unit 411 through the first atomization medium inlet 411j to atomize and concentrate the wastewater, thereby achieving zero discharge of wastewater from the thermal power plant and providing a solution for energy conservation and emission reduction in thermal power plants. Specifically, the wastewater treatment control system selects the type of working fluid entering the wastewater atomizing nozzle unit 411 and controls its flow rate based on the detected flow rate of concentrated wastewater and the detection data of the temperature sensor and the pressure sensor. On the premise of ensuring that the atomized particles can be completely vaporized and dried in the flue before entering the electrostatic precipitator 5, the total heat brought into the wastewater atomizing nozzle unit 411 by the high-temperature steam and flue gas is less than the total heat required for complete evaporation of the concentrated wastewater, that is, the temperature in the wastewater atomizing nozzle unit 411 does not reach the saturation temperature of the concentrated wastewater under the corresponding pressure, thereby preventing the concentrated wastewater from being completely evaporated and vaporized in the wastewater atomizing nozzle unit 411 and causing blockage, thereby avoiding the occurrence of soot or insufficient evaporation.

[0072] Embodiment 4

[0073] like Figure 5 As shown, it includes a wastewater flow pipe 411h, a second atomizing fluid inlet pipe 411k and a first atomizing fluid inlet pipe 411i;

[0074] A concentrated wastewater inlet 411a is provided on the wastewater circulation pipe 411h, and the concentrated wastewater inlet 411a is located on the central axis of the wastewater atomizing nozzle unit 411, and the outlet end of the wastewater circulation pipe 411h is located in the second atomizing medium inlet pipe 411k; the second atomizing medium inlet pipe 411k is sleeved on the outside of the wastewater circulation pipe 411h; the second atomizing medium inlet pipe 411k is provided with a high-temperature flue gas inlet 411b; the first atomizing medium inlet pipe 411i is sleeved on the outside of the second atomizing medium inlet pipe 411k, and the first atomizing medium inlet pipe 411i is provided with a first atomizing medium inlet 411j, and the outlet ends of the first atomizing medium inlet pipe 411i and the second atomizing medium inlet pipe 411k jointly form a spray nozzle 411d.

[0075] The high-temperature flue gas inlet 411b is inclined and connected to the atomizing medium inlet pipe 43. The high-temperature flue gas generated by the thermal power plant boiler passes through the atomizing medium inlet pipe 43 and enters the wastewater atomizing nozzle unit 411 from the high-temperature flue gas inlet 411b. The incident angle of the high-temperature flue gas and the central axis of the wastewater atomizing nozzle unit 411 are 15 degrees to 90 degrees. Fig.11 The high-temperature flue gas is introduced from any position after the coal-fired boiler 11 of the thermal power plant, after the flue gas denitrification equipment 12, before the air preheater 13, or after the air preheater 13.

[0076] The first atomizing medium inlet 411j is inclined and connected to the medium introduction pipe 411g. The incident angle of the medium and the central axis of the wastewater atomizing nozzle unit 411 are 15 to 90 degrees. Fig.11 As shown. The working medium of the first atomized working medium inlet 411j includes at least one of high-temperature steam and compressed air. The high-temperature steam is drawn from any one of the main steam of the thermal power plant, high-pressure cylinder extraction steam, high-pressure cylinder exhaust steam, reheat hot section extraction steam, medium-pressure cylinder extraction steam, and medium-pressure cylinder exhaust steam.

[0077] The first atomized material inlet 411j is equipped with any one of a temperature sensor, a pressure sensor or a flow sensor. The sensor is any one of a resistive, capacitive, inductive, photoelectric, grating, thermoelectric, piezoelectric, infrared, optical fiber, ultrasonic, and laser sensor.

[0078] Furthermore, the first atomizing medium inlet 411j is provided with a flow regulating valve for regulating and controlling the flow of the medium entering the atomizing mixing chamber. Preferably, the flow regulating valve is a solenoid valve. The solenoid valve is any one of a direct-acting, step-by-step direct-acting, and pilot-operated solenoid valve.

[0079] The wastewater generated by the desulfurization tower 7 in the wastewater treatment system in the thermal power plant is collected in the wastewater collecting manifold 2, concentrated by the wastewater high-temperature steam evaporation section 312, and the concentrated and reduced wastewater is sent to the concentrated wastewater inlet 411a in the wastewater atomization device of the wastewater atomization evaporation device 4 through the concentrated wastewater inlet pipe 42. At least one of the high-temperature flue gas, medium-pressure cylinder exhaust steam, and compressed air is introduced into the wastewater atomization nozzle unit 411 through the first atomizing medium inlet 411j to atomize and concentrate the wastewater, thereby achieving zero discharge of wastewater from the thermal power plant. Specifically, the wastewater treatment control system selects the type and flow rate of the working fluid entering the wastewater atomizing nozzle unit 411 according to the detected flow rate of concentrated wastewater and the detection data of the temperature sensor and the pressure sensor, and ensures that the atomized particles can be completely vaporized and dried in the flue before entering the electrostatic precipitator 5. The total heat brought into the wastewater atomizing nozzle unit 411 by the high-temperature steam and flue gas is less than the total heat required for complete evaporation of the concentrated wastewater, that is, the temperature in the wastewater atomizing nozzle unit 411 does not reach the saturation temperature of the concentrated wastewater under the corresponding pressure, thereby preventing the concentrated wastewater from being completely evaporated and vaporized in the wastewater atomizing nozzle unit 411, causing the nozzle to be blocked, thereby avoiding the occurrence of soot or insufficient evaporation.

[0080] Embodiment 5

[0081] The present invention also provides a method for treating wastewater from a thermal power plant, wherein the wastewater treatment method uses the aforementioned wastewater treatment system of the thermal power plant, and the treatment method comprises:

[0082] S1: The wastewater collecting manifold 2 collects the desulfurization wastewater discharged from the desulfurization tower 7, or other industrial wastewater generated in thermal power plants.

[0083] S2: The wastewater treatment control module determines the type of concentration and reduction device into which the wastewater flows according to the amount, temperature and pressure of the wastewater collected by the wastewater collection header 2, and generates concentrated and reduced wastewater.

[0084] Specifically, if it is determined that the concentration and reduction device into which the wastewater flows is the wastewater flue evaporation section 311, the wastewater treatment control module controls the first conduction valve 314, the second conduction valve 315 and the third conduction valve 316 respectively, so that the wastewater in the wastewater collection manifold 2 flows into the wastewater flue evaporation section 311 through the first conduction valve 314, the generated concentrated and reduced wastewater flows into the water pump 23 through the second conduction valve 315, and the generated gas flows into the gas-water separator 32 through the third conduction valve 316.

[0085] If it is determined that the concentration and reduction device into which the wastewater flows is the wastewater high-temperature steam evaporation section 312 or the MVR evaporation section 313, the method by which the wastewater treatment control module controls the first conduction valve 314, the second conduction valve 315 and the third conduction valve 316 respectively is similar to the method when the concentration and reduction device into which the wastewater flows is the wastewater flue evaporation section 311, and will not be repeated here.

[0086] S3: The wastewater treatment control module controls the water pump to send the concentrated and reduced wastewater into the wastewater atomization evaporation device 4.

[0087] Specifically, the water pump sends the concentrated and reduced wastewater into the concentrated wastewater inlet 411a of each atomizing nozzle unit 411 in the atomizing nozzle array 41.

[0088] S4: The wastewater treatment control system controls the opening and closing of the valves set on each atomizing nozzle unit 411 in the atomizing nozzle array 41 to distribute the flow rate of the concentrated wastewater flowing through each atomizing nozzle unit 411.

[0089] S5: The wastewater treatment control system determines the pressure, temperature, and flow rate of the high-temperature flue gas and / or high-temperature steam entering the atomizing mixing chamber 411c according to the flow rate of the concentrated wastewater at the concentrated wastewater inlet 411a of each atomizing nozzle unit 411, so that the wastewater atomization particles entering the flue through the spray nozzle 411d of each atomizing nozzle unit 411 meet the standards.

[0090] S6: The wastewater treatment control system monitors the temperature and humidity parameters of the flue gas between the wastewater atomization evaporation device 4 and the electrostatic precipitator 5, and operates the opening and closing of the atomizing nozzle valves according to the temperature and humidity parameters.

[0091] The described wastewater treatment control system needs to control that the wastewater entering each atomizing nozzle does not completely evaporate in the atomizing mixing chamber, that is, the wastewater flow rate temperature, the flue gas and / or high-temperature steam flow rate temperature satisfy the following calculation formula:

[0092] F_wastewater * [C_p_water * (T_mix - T_0_water) + q_vaporization latent heat] > F_flue gas * C_p_flue gas * (T_flue gas - T_mix) + F_steam * C_p_steam * (T_steam - T_mix) + F_air * C_p_air * (T_air - T_mix);

[0093] In the formula:

[0094] Q_wastewater evaporation is the heat required for the evaporation of the concentrated wastewater, kJ / kg;

[0095] Q_flue gas is the heat brought by the flue gas entering the nozzle, kJ / kg;

[0096] Q_steam is the heat brought by the high-temperature steam entering the nozzle, kJ / kg;

[0097] F_wastewater is the flow rate of the concentrated wastewater inlet, kg / h;

[0098] F_flue gas is the flow rate of the flue gas inlet, kg / h;

[0099] F_steam is the flow rate of the first atomization working medium inlet, kg / h;

[0100] C p water is the specific heat capacity of concentrated wastewater, kJ / kg℃;

[0101] C p smoke is the specific heat capacity of boiler flue gas, kJ / kg℃;

[0102] C p steam is the specific heat capacity of high temperature steam, kJ / kg℃;

[0103] T0water is the temperature of the concentrated wastewater inlet, °C;

[0104] Tsmoke is the temperature of the smoke inlet, °C;

[0105] T steam is the temperature of the first atomizing fluid inlet, °C;

[0106] Tmix is ​​the average temperature of the atomization mixing chamber, °C;

[0107] Tsaturation is the saturation temperature of concentrated wastewater under the pressure in the atomizing mixing chamber, °C;

[0108] q Latent heat of vaporization is the latent heat of vaporization of concentrated wastewater, kJ / kg.

[0109] As long as the above inequality is met, that is, the total heat brought into the atomization mixing chamber by high-temperature steam and flue gas is less than the total heat required for complete evaporation and vaporization of the concentrated wastewater, that is, the temperature in the atomization mixing chamber does not reach the saturation temperature of the concentrated wastewater under the corresponding pressure, the concentrated wastewater will not be completely evaporated and vaporized in the atomization mixing chamber, and the atomization nozzle can achieve the function of atomizing the concentrated wastewater using flue gas or steam.

[0110] By implementing method steps S1 to S6, the wastewater treatment control system is used to control valves and temperature, pressure and flow sensors, and to control the temperature, pressure and flow of various working fluid mixtures, so as to achieve a wastewater droplet diameter of less than 200 μm at the outlet of the atomizing nozzle. This ensures that within the general flue length range, the concentrated wastewater atomized droplets are completely vaporized before the flue gas enters the electrostatic precipitator.

[0111] According to the experimental data, the following relationship curve between the atomized droplets and the complete evaporation time in the flue can be obtained, such as Fig.10 shown.

[0112] The droplet size in the above diagram is directly related to the internal structure of the nozzle and the incident angle and flow rate of the gas phase fluid entering the mixing chamber. Fig.11 As shown, the angle between the incident angle of the gas phase fluid of the atomizing nozzle unit with a mixing chamber and the central axis of the mixing chamber can be adjusted from 15 degrees to 90 degrees.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wastewater treatment system for a thermal power plant, comprising a coal-fired boiler (11) of a thermal power plant, a flue gas denitrification device (12), an air preheater (13), an electrostatic precipitator (5), a desulfurization tower (7) and a wastewater collection header (2), characterized in that: The invention comprises an atomizing medium introduction device (1), a wastewater concentration and reduction device (3) and a wastewater atomizing and evaporating device (4); the wastewater collecting manifold (2) is connected to the wastewater concentration and reduction device (3), so that the thermal power plant wastewater in the wastewater collecting manifold (2) is passed into the wastewater concentration and reduction device (3); the wastewater concentration and reduction device (3) and the atomizing medium introduction device (1) are respectively connected to the wastewater atomizing and evaporating device (4), so that the flue gas, steam or compressed air atomizing medium introduced by the atomizing medium introduction device (1) and the concentrated and reduced wastewater output from the wastewater concentration and reduction device (3) enter the wastewater atomizing and evaporating device (4); the wastewater atomizing and evaporating device (4) is connected to an electrostatic precipitator (5); the wastewater atomizing and evaporating device (4) comprises an atomizing nozzle array (41), and the atomizing nozzle array (41) is composed of a plurality of spaced-apart nozzles. The wastewater atomizing evaporation device (4) is composed of an atomizing nozzle unit (411), the atomizing nozzle unit (411) includes one or more atomizing medium inlet ports, the wastewater concentration and reduction device (3) includes a wastewater evaporation section, the wastewater evaporation section includes any one or a combination of a wastewater flue evaporation section, a wastewater high-temperature steam evaporation section or a wastewater MVR evaporation section; the wastewater atomizing evaporation device (4) includes a concentrated wastewater inlet pipe (42) and an atomizing medium inlet pipe (43), the atomizing nozzle array (41) is installed in the wastewater atomizing evaporation device (4), and the wastewater atomizing evaporation device (4) is installed in the flue of a boiler in a thermal power plant as a whole; the atomizing nozzle unit (411) includes a concentrated wastewater inlet port and an atomizing nozzle; the atomizing medium in the atomizing medium inlet device is any one or any combination of boiler high-temperature flue gas, power plant high-temperature steam or compressed air.

2. The wastewater treatment system of a thermal power plant according to claim 1, characterized in that: The wastewater concentration and reduction device (3) comprises a gas-water separator, the wastewater evaporation part is respectively connected to the gas-water separator and the wastewater collection manifold (2), and the gas-water separator is also respectively connected to the desulfurization tower (7) and the power plant thermal system (81) and the recycled water system (82).

3. The wastewater treatment system of a thermal power plant according to claim 2, characterized in that: The wastewater evaporation unit obtains water vapor by evaporating wastewater, and according to its temperature, pressure or components, it is recycled and enters the steam header, deaerator, condenser or industrial water tank of the thermal power plant or other thermal system inlet.

4. A method for treating wastewater from a thermal power plant, used in the wastewater treatment system of a thermal power plant according to any one of claims 1 to 3, characterized in that: The method comprises: S1: The wastewater collecting manifold (2) collects the desulfurization wastewater discharged from the desulfurization tower (7) or other industrial wastewater generated in thermal power plants; S2: The wastewater treatment control module determines the type of concentration and reduction device into which the wastewater flows according to the amount, temperature and pressure of the wastewater collected by the wastewater collection header (2), and generates concentrated and reduced wastewater; S3: the wastewater treatment control module controls the water pump to send the concentrated and reduced wastewater into the wastewater atomization evaporation device (4); S4: the wastewater treatment control system controls the opening of the concentrated wastewater inlet valve on each atomizing nozzle unit (411) in the atomizing nozzle array (41) according to the amount of concentrated wastewater generated, and distributes the concentrated wastewater flow rate flowing through each atomizing nozzle unit (411); S5: The wastewater treatment control system determines the pressure, temperature, and flow rate of the introduced high-temperature flue gas and / or high-temperature steam and / or compressed air according to the flow rate of the concentrated wastewater at the concentrated wastewater inlet (411a) of each atomizing nozzle unit (411), so that the atomized particles of the wastewater entering the flue from the outlet of the spray nozzle (411d) of each atomizing nozzle unit (411) meet the standards. S6: The wastewater treatment control system monitors the temperature and humidity parameters of the flue gas between the wastewater atomization evaporation device (4) and the electrostatic precipitator (5), and performs start-stop operations on the wastewater atomization evaporation device according to the temperature and humidity parameters.

5. The method for treating wastewater from a thermal power plant according to claim 4, characterized in that: The described wastewater treatment control system controls the wastewater flow rate temperature, flue gas and / or high-temperature steam and / or compressed air flow rate temperature to satisfy the following calculation formula: F_wastewater * [Cp_water * (T_mix - T_0_water) + q_vaporization latent heat] > F_flue_gas * Cp_flue_gas * (T_flue_gas - T_mix) + F_steam * Cp_steam * (T_steam - T_mix) + F_air * Cp_air * (T_air - T_mix); where: Q_wastewater_evaporation is the heat required for the evaporation of the concentrated wastewater, kJ / kg; Q_flue_gas is the heat brought into the nozzle by the flue gas, kJ / kg; Q_steam is the heat brought into the nozzle by the high-temperature steam, kJ / kg; F_wastewater is the flow rate at the concentrated wastewater inlet, kg / h; F_flue_gas is the flow rate at the flue gas inlet, kg / h; F_steam is the flow rate at the first atomization working medium inlet, kg / h; Cp_water is the specific heat capacity of the concentrated wastewater, kJ / kg·°C; Cp_flue_gas is the specific heat capacity of the boiler flue gas, kJ / kg·°C; Cp_steam is the specific heat capacity of the high-temperature steam, kJ / kg·°C; T_0_water is the temperature at the concentrated wastewater inlet, °C; T_flue_gas is the temperature at the flue gas inlet, °C; T_steam is the temperature at the first atomization working medium inlet, °C; T_mix is the average temperature of the atomization mixing chamber, °C; T_saturation is the saturation temperature of the concentrated wastewater under the pressure in the atomization mixing chamber, °C; q_vaporization latent heat is the latent heat of vaporization of the concentrated wastewater, kJ / kg.

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