Desulfurization wastewater dechlorination system and method based on chloride ion online monitoring and regulation

Abstract

The invention discloses a desulfurization wastewater dechlorination system and method based on chloride ion on-line monitoring and regulation, a high-temperature steam input pipeline is communicated with an inlet of a steam-water mixing heater, a triple box water outlet pipeline is communicated with the inlet of the steam-water mixing heater, an outlet of the steam-water mixing heater is communicated with an inlet of a mixing reaction tank, and an outlet of the mixing reaction tank is communicated with an outlet of the triple box water outlet pipeline. The outlet of the lime milk storage tank is communicated with the inlet of the mixed reaction tank through a first metering pump, the outlet of the NaAlO2 storage tank is communicated with the inlet of the mixed reaction tank through a second metering pump, the outlet of the mixed reaction tank is communicated with the inlet of the clarification tank, and the water outlet of the clarification tank is communicated with a second chloride ion online inspection device; according to the system and the method, automatic dosing can be realized, the effluent quality is relatively stable, and the dosage of chemicals is relatively small.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and relates to a desulfurization wastewater dechlorination system and method based on online monitoring and control of chloride ions. Background Art

[0002] The coal-fired power generation process produces a large amount of smoke, SO2, NO x Flue gas pollutants such as Cl - The Cl in the desulfurization slurry will also be absorbed by the desulfurization slurry and will be continuously enriched with the operation of the desulfurization system. When its concentration reaches a certain level, it will cause equipment corrosion, inhibit the dissolution of limestone, reduce the desulfurization efficiency and gypsum quality, etc., affecting the normal operation of the desulfurization system. Therefore, it is necessary to regularly discharge a part of the slurry (i.e., desulfurization wastewater) from the desulfurization system to control the Cl in the system slurry. - The content is about 12000-20000mg / L. In addition, during the dehydration and washing process of gypsum, some desulfurization wastewater will also be produced. The above desulfurization wastewater usually has the characteristics of low pH, high hardness, high suspended matter and salt content, and excessive heavy metal ions. It cannot be discharged directly and needs to be properly treated.

[0003] The "triple box" is the most commonly used desulfurization wastewater treatment process. It adds lime milk, organic sulfur and flocculants to the wastewater in sequence to complete the neutralization, precipitation and flocculation processes, so that heavy metal ions, Ca 2+ 、F - , suspended solids, etc. are removed in the form of sediment. However, the desulfurization wastewater after treatment by the triple box still contains a large amount of Cl - If it is discharged directly, it will easily cause mineralization, hinder crop growth, and cause soil salinization, so most of the water discharged from the triplex box is reused in the factory through dry ash mixing, ash field spraying, and introduction into the boiler slag water system. However, with the continuous development of fly ash resource technology, the above-mentioned in-plant reuse methods have been subject to certain restrictions. The "Technical Policy for Pollution Prevention and Control of Thermal Power Plants" emphasizes the strategic policy of not discharging desulfurization wastewater from power plants. Therefore, an effective deep treatment technology is urgently needed for Cl - Remove it to expand the recycling and utilization of desulfurization wastewater and achieve zero wastewater discharge.

[0004] Currently available Cl - Removal technologies include chemical precipitation, membrane separation, evaporation crystallization, ion exchange, extraction and oxidation. Membrane separation and evaporation crystallization technology can effectively remove Cl - However, it has the disadvantages of high investment and operating costs and high energy consumption; the ion exchange system is easily affected by impurities, resulting in the removal of Cl -The efficiency is not ideal; solvent extraction is a simple and effective separation technology, but it also has problems such as high cost; the oxidation method has no secondary pollution, but the disadvantages such as low oxidant utilization rate and high chloride concentration in treated water cannot be ignored.

[0005] Freund's salt precipitation method has the advantages of low cost, simple operation and high efficiency. This method adds CaO / Ca(OH)2 and NaAlO2 to the water to form a layered calcium chloride compound Ca4Al2(OH) 14 , its interlayer ions OH - Can react with Cl in water - An exchange reaction occurs to form a Fred salt precipitate (Ca4Al2(OH) 12 Cl2), thereby achieving Cl - In addition, the by-product of the process, Fred salt, can be used as cement raw material, coagulant PAC raw material, adsorbent and sludge dewatering regulator, which has a large recovery value, improves the economy of the entire treatment process, and has a good application prospect in the field of dechlorination of desulfurization wastewater.

[0006] Increasing the temperature of the reaction system can accelerate the reaction of Ca4Al2(OH) 14 The formation of - The exchange reaction will occur, but it will also cause the crystal size of Freund's salt to decrease, the structure to be dense, and its sedimentation performance to decrease. Freund's salt will decompose at temperatures above 40°C to generate Ca3Al2(OH) 12 and releases Cl - , reduce Cl - Removal efficiency. Therefore, in the process of Freund's salt precipitation and chlorine removal, the temperature of the reaction system needs to be maintained within an appropriate range.

[0007] In addition, the reagent dosage, that is, the ratio of Ca / Al / Cl to Cl in the reaction system - The removal efficiency of CaO also has a great impact: when the CaO / Ca(OH)2 dosage is too high, Ca 2+ Prefer Ca(OH)2 rather than Ca4Al2(OH) 14 exists in the form of Cl - When the dosage of NaAlO2 is too high, the excess Al(OH)4 - or (OH) - Will Ca4Al2(OH) 12 Cl in Cl2 - Replace it and reduce Cl - removal efficiency; when Ca / Cl and Al / Cl are low or high, the former will lead to Ca4Al2(OH) 14The content is low, so that the Cl - The effect is not ideal, and the latter will not only cause waste of reagents, but also increase sludge production and treatment costs. Most power plants use manual dosing or quantitative dosing, which cannot make corresponding adjustments to changes in influent water quality, resulting in unstable effluent quality or waste of reagents. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a dechlorination system and method for desulfurization wastewater based on online monitoring and control of chloride ions. The system and method can realize automatic dosing, the effluent water quality is relatively stable, and the amount of reagents used is relatively small.

[0009] To achieve the above object, the present invention discloses a desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions, comprising a high-temperature steam input pipeline, a steam-water mixing heater, a triple-box outlet pipeline, a mixing reaction tank, a lime milk storage tank, a NaAlO2 storage tank, a clarifier and a PLC control system;

[0010] The high-temperature steam input pipeline is connected to the inlet of the steam-water mixing heater, the water outlet pipeline of the triple box is connected to the inlet of the steam-water mixing heater, the outlet of the steam-water mixing heater is connected to the inlet of the mixing reaction tank, the outlet of the lime milk storage tank is connected to the inlet of the mixing reaction tank via the first metering pump, the outlet of the NaAlO2 storage tank is connected to the inlet of the mixing reaction tank via the second metering pump, the outlet of the mixing reaction tank is connected to the inlet of the clarification tank, the water outlet of the clarification tank is connected to the second chloride ion online detection device, and the outlet of the steam-water mixing heater is connected to the first chloride ion online detection device.

[0011] The input end of the PLC control system is connected to the output end of the first chloride ion online detection device and the output end of the second chloride ion online detection device, and the output end of the PLC control system is connected to the control end of the first metering pump and the control end of the second metering pump.

[0012] The further improvement of the desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions described in the present invention is:

[0013] Furthermore, the outlet of the first online chloride ion detection device is connected to the ditch, and the outlet of the second online chloride ion detection device is connected to the ditch.

[0014] Furthermore, it also includes a wastewater recycling pipeline, and the outlet of the clarification tank is connected to the wastewater recycling pipeline.

[0015] Furthermore, the high-temperature steam input pipeline is connected to the inlet of the steam-water mixing heater via the solenoid valve, and the outlet of the steam-water mixing heater is connected to the inlet of the mixing reaction tank via the temperature sensor and the electromagnetic flowmeter in turn.

[0016] Furthermore, the input end of the PLC control system is connected to the output end of the temperature sensor and the output end of the electromagnetic flowmeter.

[0017] The present invention discloses a method for dechlorinating desulfurization wastewater based on online monitoring and regulation of chloride ions, comprising the following steps:

[0018] The first chloride ion online testing device is used to test the Cl ion content of the outlet water of the steam-water mixing heater. - Concentration and send it to the PLC control system;

[0019] The PLC control system controls the frequencies of the first metering pump and the second metering pump according to the measured values ​​of the first chloride ion online detection device and the measured values ​​of the electromagnetic flowmeter to ensure that the ratio of Ca / Al / Cl in the mixed reaction tank is a preset ratio;

[0020] The Cl in the effluent from the clarifier is detected by the second chloride ion online detection device. - concentration and transmit it to the PLC control system;

[0021] The PLC control system compares the measured value of the second chloride ion online detection device with the preset Cl - Concentration value, when the measured value of the second chloride ion online detection device is greater than the preset Cl - When the concentration value is less than or equal to the preset Cl concentration, the frequency of the first metering pump and the second metering pump is increased so that the measured value of the second chloride ion online detection device is less than or equal to the preset Cl concentration. - Concentration value.

[0022] The further improvement of the dechlorination method of desulfurization wastewater based on online monitoring and control of chloride ions described in the present invention is:

[0023] Furthermore, the high-temperature steam input pipeline is connected to the inlet of the steam-water mixing heater via the solenoid valve, and the outlet of the steam-water mixing heater is connected to the inlet of the mixing reaction tank via the temperature sensor and the electromagnetic flowmeter in turn.

[0024] Furthermore, the input end of the PLC control system is connected to the output end of the temperature sensor and the output end of the electromagnetic flowmeter.

[0025] Furthermore, it also includes:

[0026] The temperature and flow information of the water at the water inlet of the mixing reaction tank are measured by the temperature sensor and the electromagnetic flowmeter, and sent to the PLC control system;

[0027] The PLC control system calculates the deviation between the measured value of the temperature sensor and the preset temperature, and when the deviation is greater than or equal to the preset deviation value, adjusts the opening of the solenoid valve so that the deviation is less than the preset deviation value.

[0028] Furthermore, the preset ratio includes but is not limited to: 6:3:1, 10:4:1, 5:3:1 and 6:2:1.

[0029] The present invention has the following beneficial effects:

[0030] In the specific operation of the desulfurization wastewater dechlorination system and method based on online monitoring and control of chloride ions described in the present invention, the PLC control system controls the frequency of the first metering pump and the second metering pump according to the measured value of the first chloride ion online detection device and the measured value of the electromagnetic flowmeter, and the PLC control system compares the measured value of the second chloride ion online detection device with the preset Cl - The concentration value is used to control the first metering pump and the second metering pump to achieve automatic control of the dosage. It should be noted that the present invention measures the temperature, flow rate and Cl concentration of the water entering the reaction pool in real time. - Concentration parameters, the high-temperature steam pipeline solenoid valve and the dosing pump frequency are adjusted accordingly, which can ensure that the temperature and Ca / Al / Cl ratio in the mixed reaction tank are maintained at the optimal reaction conditions when the inlet water quality fluctuates, thereby improving the removal of Cl - Effect; at the same time, based on the above adjustments, based on the effluent Cl - The concentration measurement results are used to fine-tune the dosing pump frequency, thereby minimizing the consumption of chemicals and reducing the operating costs of the dechlorination system while ensuring that the effluent quality meets the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 It is a system schematic diagram of the present invention.

[0033] Among them, 1 is a solenoid valve, 2 is a steam-water mixing heater, 3 is a first chloride ion online detection device, 4 is a PLC control system, 5 is a temperature sensor, 6 is an electromagnetic flowmeter, 7 is a first metering pump, 8 is a second metering pump, 9 is a lime milk storage tank, 10 is a NaAlO2 storage tank, 11 is a mixing reaction tank, 12 is a clarification tank, and 13 is a second chloride ion online detection device. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0036] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0037] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0038] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0039] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0042] refer to Figure 1 The desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions of the present invention comprises a solenoid valve 1, a steam-water mixing heater 2, a first chloride ion online detection device 3, a PLC control system 4, a temperature sensor 5, an electromagnetic flowmeter 6, a first metering pump 7, a second metering pump 8, a lime milk storage tank 9, a NaAlO2 storage tank 10, a mixing reaction tank 11, a clarification tank 12 and a second chloride ion online detection device 13;

[0043] The high-temperature steam input pipeline is connected to the inlet of the steam-water mixing heater 2 through the solenoid valve 1, the water outlet pipeline of the triple box is connected to the inlet of the steam-water mixing heater 2, the outlet of the steam-water mixing heater 2 is connected to the inlet of the mixing reaction tank 11 through the temperature sensor 5 and the electromagnetic flowmeter 6 in turn, the outlet of the lime milk storage tank 9 is connected to the inlet of the mixing reaction tank 11 through the first metering pump 7, the outlet of the NaAlO2 storage tank 10 is connected to the inlet of the mixing reaction tank 11 through the second metering pump 8, the outlet of the mixing reaction tank 11 is connected to the inlet of the clarification tank 12, the outlet of the clarification tank 12 is connected to the wastewater reuse pipeline, the wastewater reuse pipeline is connected to the second chloride ion online detection device 13, and the outlet of the steam-water mixing heater 2 is connected to the first chloride ion online detection device 3.

[0044] The outlet of the first online chloride ion detection device 3 is connected to the ditch, and the outlet of the second online chloride ion detection device 13 is connected to the ditch.

[0045] The input end of the PLC control system 4 is connected to the output end of the first chloride ion online detection device 3, the output end of the second chloride ion online detection device 13, the output end of the temperature sensor 5 and the output end of the electromagnetic flowmeter 6, and the output end of the PLC control system 4 is connected to the control end of the first metering pump 7 and the control end of the second metering pump 8.

[0046] refer to Figure 1 The method for dechlorination of desulfurization wastewater based on online monitoring and control of chloride ions of the present invention comprises the following steps:

[0047] The outlet water of the triple tank is heated by high-temperature steam and a steam-water mixing heater 2. The heated water sample enters the mixing reaction tank 11 through the temperature sensor 5 and the electromagnetic flowmeter 6 in turn. At the same time, the first metering pump 7 extracts the lime milk in the lime milk storage tank 9 and sends it to the mixing reaction tank 11. The second metering pump 8 extracts the NaAlO2 in the NaAlO2 storage tank 10 and sends it to the mixing reaction tank 11. The Cl in the water sample in the mixing reaction tank 11 - , NaAlO2 and lime milk undergo the following reactions:

[0048] 2NaAlO2+4H2O→2Al(OH)3+2NaOH

[0049] 4Ca(OH)2+2Al(OH)3→Ca4Al2(OH) 14

[0050] Ca4Al2(OH) 14 +2Cl - →Ca4Al2Cl2(OH) 12 +2OH -

[0051] The Cl ion of the outlet water of the steam-water mixing heater 2 is measured by the first chloride ion online detection device 3 - concentration and sent to the PLC control system 4.

[0052] It should be noted that the measurement period of the first chloride ion online detection device 3 is set by the power plant according to actual production needs, ranging from 20 minutes to 2 hours.

[0053] The temperature and flow information of the water at the water inlet of the mixing reaction tank 11 are measured by the temperature sensor 5 and the electromagnetic flowmeter 6 and sent to the PLC control system 4 .

[0054] The PLC control system 4 calculates the deviation between the measured value of the temperature sensor 5 and the preset temperature. When the deviation is greater than or equal to the preset deviation value, the opening of the solenoid valve 1 is adjusted so that the deviation is less than the preset deviation value.

[0055] It should be noted that the preset temperature is CaO / Ca(OH)2, NaAlO2 and Cl - The optimal temperature for the reaction, as determined by preliminary experiments, ranges from 30°C to 40°C.

[0056] The PLC control system 4 controls the frequencies of the first metering pump 7 and the second metering pump 8 according to the measurement values ​​of the first chloride ion online detection device 3 and the measurement values ​​of the electromagnetic flowmeter 6 to ensure that the ratio of Ca / Al / Cl in the mixed reaction tank 11 is a preset ratio.

[0057] It should be noted that the preset ratio is CaO / Ca(OH)2, NaAlO2 and Cl - The optimal ratio of the reaction is obtained from preliminary experiments, including but not limited to 6:3:1, 10:4:1, 5:3:1, and 6:2:1;

[0058] The effluent from the mixed reaction tank 11 enters the clarification tank 12 for solid-liquid separation, wherein the separated supernatant flows into the wastewater reuse pipeline for subsequent recycling, and the separated Freund's salt precipitate is used as an adsorbent, sludge dehydration regulator, etc. after dehydration and other treatments.

[0059] Further, the Cl ion in the effluent of the clarification tank 12 is detected by the second chloride ion online detection device 13. - concentration and transmit it to the PLC control system 4.

[0060] The PLC control system 4 compares the measured value of the second chloride ion online detection device 13 with the preset Cl - concentration value, when the measured value of the second chloride ion online detection device 13 is greater than the preset Cl - When the concentration value is less than or equal to the preset Cl concentration, the frequency of the first metering pump 7 and the second metering pump 8 is increased so that the measured value of the second chloride ion online detection device 13 is less than or equal to the preset Cl concentration. - Concentration value.

[0061] It should be noted that the default Cl - The concentration value is set by the power plant based on the specific requirements of subsequent wastewater reuse methods.

[0062] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0063] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions, characterized in that: It comprises a high-temperature steam input pipeline, a steam-water mixing heater (2), a triple-tank outlet pipeline, a mixing reaction tank (11), a lime milk storage tank (9), a NaAlO2 storage tank (10), a clarification tank (12) and a PLC control system (4); The high-temperature steam input pipeline is connected to the inlet of the steam-water mixing heater (2), the triple box water outlet pipeline is connected to the inlet of the steam-water mixing heater (2), the outlet of the steam-water mixing heater (2) is connected to the inlet of the mixing reaction tank (11), the outlet of the lime milk medicine storage tank (9) is connected to the inlet of the mixing reaction tank (11) via the first metering pump (7), the outlet of the NaAlO2 medicine storage tank (10) is connected to the inlet of the mixing reaction tank (11) via the second metering pump (8), the outlet of the mixing reaction tank (11) is connected to the inlet of the clarification tank (12), the water outlet of the clarification tank (12) is connected to the second chloride ion online detection device (13), and the outlet of the steam-water mixing heater (2) is connected to the first chloride ion online detection device (3); The input end of the PLC control system (4) is connected to the output end of the first chloride ion online detection device (3) and the output end of the second chloride ion online detection device (13), and the output end of the PLC control system (4) is connected to the control end of the first metering pump (7) and the control end of the second metering pump (8).

2. The desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions according to claim 1 is characterized in that: The outlet of the first online chloride ion detection device (3) is connected to the ditch, and the outlet of the second online chloride ion detection device (13) is connected to the ditch.

3. The desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions according to claim 1 is characterized in that: It also includes a wastewater recycling pipeline, and the outlet of the clarification tank (12) is connected to the wastewater recycling pipeline.

4. The desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions according to claim 1 is characterized in that: The high-temperature steam input pipeline is connected to the inlet of the steam-water mixing heater (2) via the electromagnetic valve (1), and the outlet of the steam-water mixing heater (2) is connected to the inlet of the mixing reaction tank (11) via the temperature sensor (5) and the electromagnetic flowmeter (6) in turn.

5. The desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions according to claim 4 is characterized in that: The input end of the PLC control system (4) is connected to the output end of the temperature sensor (5) and the output end of the electromagnetic flowmeter (6).

6. A method for dechlorination of desulfurization wastewater based on online monitoring and control of chloride ions, characterized in that: The desulfurization wastewater dechlorination system based on online monitoring and control of chloride ions according to claim 5 comprises the following steps: The Cl ion content of the outlet water of the steam-water mixing heater (2) is measured by a first online chloride ion detection device (3). - concentration and sent to the PLC control system (4); The PLC control system (4) controls the frequencies of the first metering pump (7) and the second metering pump (8) according to the measured value of the first chloride ion online detection device (3) and the measured value of the electromagnetic flowmeter (6) to ensure that the ratio of Ca / Al / Cl in the mixed reaction tank (11) is a preset ratio; The Cl ion content of the effluent from the clarification tank (12) is detected by a second chloride ion online detection device (13). - concentration and transmit it to the PLC control system (4); The PLC control system (4) compares the measured value of the second chloride ion online detection device (13) with the preset Cl - concentration value, when the measured value of the second chloride ion online detection device (13) is greater than the preset Cl - When the concentration value is greater than or equal to the preset Cl concentration, the frequencies of the first metering pump (7) and the second metering pump (8) are increased so that the measured value of the second chloride ion online detection device (13) is less than or equal to the preset Cl concentration. - Concentration value.

7. The method for dechlorination of desulfurization wastewater based on online monitoring and control of chloride ions according to claim 6, characterized in that: The high-temperature steam input pipeline is connected to the inlet of the steam-water mixing heater (2) via the electromagnetic valve (1), and the outlet of the steam-water mixing heater (2) is connected to the inlet of the mixing reaction tank (11) via the temperature sensor (5) and the electromagnetic flowmeter (6) in turn.

8. The method for dechlorination of desulfurization wastewater based on online monitoring and control of chloride ions according to claim 7, characterized in that: The input end of the PLC control system (4) is connected to the output end of the temperature sensor (5) and the output end of the electromagnetic flowmeter (6).

9. The method for dechlorination of desulfurization wastewater based on online monitoring and control of chloride ions according to claim 8, characterized in that: Also includes: The temperature and flow rate information of the water at the water inlet of the mixing reaction tank (11) are measured by a temperature sensor (5) and an electromagnetic flow meter (6), and sent to the PLC control system (4); The PLC control system (4) calculates the deviation between the measured value of the temperature sensor (5) and the preset temperature, and when the deviation is greater than or equal to the preset deviation value, adjusts the opening of the solenoid valve (1) so that the deviation is less than the preset deviation value.

10. The method for dechlorination of desulfurization wastewater based on online monitoring and control of chloride ions according to claim 6, characterized in that: The preset ratios include but are not limited to: 6:3:1, 10:4:1, 5:3:1 and 6:2:1.

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