A device and method for extracting dechlorination of desulfurization wastewater in a thermal power plant

Abstract

The application provides a power plant desulfurization wastewater extraction dechlorination device and method, the device comprises a first extractor, a second extractor, a third extractor, a first back extraction machine, a second back extraction machine and a third back extraction machine; the desulfurization wastewater enters from the water inlet of the first extractor and flows through the second extractor and the third extractor in sequence; the outlet of the first extractor is communicated with the inlet of the first back extraction machine, the outlet of the first back extraction machine is communicated with the inlet of the first extractor; the outlet of the second extractor is communicated with the inlet of the second back extraction machine, the outlet of the second back extraction machine is communicated with the inlet of the second extractor; the outlet of the third extractor is communicated with the inlet of the third back extraction machine, and the outlet of the third back extraction machine is communicated with the inlet of the third extractor. The device of the application realizes efficient and selective extraction of chlorine ions through hierarchical adaptation of composite extractants and multi-stage extraction synergy, and significantly improves the efficiency and stability of the desulfurization wastewater dechlorination treatment.

Description

Technical Field

[0001] This invention belongs to the field of desulfurization wastewater treatment technology, specifically relating to an extraction and dechlorination device and method for desulfurization wastewater from thermal power plants. Background Technology

[0002] Desulfurization wastewater from thermal power plants is an inevitable byproduct of wet desulfurization processes. It is characterized by high suspended solids, high salinity, complex and volatile water quality. The chloride ion concentration can fluctuate significantly from hundreds to tens of thousands of mg / L, becoming a key bottleneck restricting the wastewater from meeting discharge standards or being reused.

[0003] Existing dechlorination technologies, such as ion exchange and membrane separation, are ill-suited to handling desulfurization wastewater with significant chloride ion concentration fluctuations. Ion exchange resins are prone to saturation and failure, limiting their capacity for treating high-concentration chloride ions. Membrane separation is susceptible to concentration gradient polarization, leading to membrane module clogging and high maintenance costs. Solvent extraction has attracted considerable attention due to its high selectivity and large processing capacity, but single extractants are insufficient to meet the wide range of chloride ion concentrations required. Therefore, developing a dechlorination system that can flexibly address water quality fluctuations, is highly efficient, stable, and economically feasible is of significant practical importance for the recycling of water resources in thermal power plants. Summary of the Invention

[0004] This application provides an extraction and dechlorination device and method for desulfurization wastewater from thermal power plants, aiming to solve the problems of existing extraction methods being unable to adapt to the wide concentration range of chloride ion treatment requirements and having poor stability when treating desulfurization wastewater.

[0005] This application provides an extraction and dechlorination device for desulfurization wastewater from a thermal power plant, comprising a primary extractor, a secondary extractor, a tertiary extractor, a first-stage back-extractor, a second-stage back-extractor, and a third-stage back-extractor;

[0006] The desulfurization wastewater flows into the desulfurization wastewater extraction and dechlorination unit of the thermal power plant through the inlet of the primary extractor, and comes into contact with the first composite extractant in the primary extractor to achieve primary removal of chloride ions in the desulfurization wastewater; the outlet of the primary extractor is connected to the inlet of the secondary extractor, and the outlet of the secondary extractor is connected to the inlet of the tertiary extractor. The outlet of the primary extractor is connected to the inlet of the first reverse extractor, and the outlet of the first reverse extractor is connected to the inlet of the primary extractor. The outlet of the secondary extractor is connected to the inlet of the second back-extraction machine, and the outlet of the second back-extraction machine is connected to the inlet of the secondary extractor. The outlet of the three-stage extractor is connected to the inlet of the third-stage back-extraction machine, and the outlet of the third-stage back-extraction machine is connected to the inlet of the three-stage extractor.

[0007] According to some embodiments of the desulfurization wastewater extraction and dechlorination device for thermal power plants described in this application, it also includes a first composite extractant addition device, a second composite extractant addition device and a third composite extractant addition device. The first composite extractant addition device is connected to the inlet of the primary extractor and is used to add the first composite extractant to the primary extractor. The second composite extractant dosing device is connected to the inlet of the secondary extractor and is used to add the second composite extractant into the secondary extractor. The third composite extractant dosing device is connected to the inlet of the three-stage extractor and is used to add the third composite extractant into the three-stage extractor.

[0008] According to some embodiments of the desulfurization wastewater extraction and dechlorination device for thermal power plants described in this application, it also includes a back-extraction agent dosing device. The back-extraction agent dosing device is connected to the inlet of the No. 1 back-extraction machine, the inlet of the No. 2 back-extraction machine, and the inlet of the No. 3 back-extraction machine through a three-way valve, and is used to add back-extraction agent to the No. 1 back-extraction machine, the No. 2 back-extraction machine, and the No. 3 back-extraction machine.

[0009] According to some embodiments of the desulfurization wastewater extraction and dechlorination device for thermal power plants described in this application, a by-product collection device is also included; the outlets of the No. 1 back-extractor, the No. 2 back-extractor, and the No. 3 back-extractor are all connected to the by-product collection device.

[0010] According to some embodiments of the desulfurization wastewater extraction and dechlorination device for thermal power plants described in this application, it also includes a main extractant dosing device, a first modifier dosing device, a second modifier dosing device, and a diluent dosing device; The main extractant dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve. The first modifier dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device respectively via a three-way valve; The second modifier dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve; The diluent dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve.

[0011] The second aspect of this application provides a method for extracting and dechlorinating desulfurization wastewater from a thermal power plant, which is implemented using the extraction and dechlorination device for desulfurization wastewater from a thermal power plant described in the first aspect of this application.

[0012] According to some embodiments of the method for desulfurization and dechlorination of desulfurization wastewater from thermal power plants described in this application, the method includes the following steps: desulfurization wastewater is input into the inlet of a primary extractor, and a first composite extractant is added into the inlet of the primary extractor; the desulfurization wastewater and the first composite extractant are mixed and reacted to achieve primary dechlorination; the desulfurization wastewater after primary dechlorination flows into a secondary extractor and is mixed and reacted with a second composite extractant to achieve secondary dechlorination; the desulfurization wastewater after secondary dechlorination flows into a tertiary extractor and is mixed and reacted with a third composite extractant to achieve tertiary dechlorination. The chlorine-rich extractant produced by the primary extractor flows into the No. 1 back-extraction machine, and the regenerated extractant produced by the No. 1 back-extraction machine flows into the primary extractor for reuse. The chlorine-rich extractant produced by the secondary extractor flows into the secondary back-extraction machine, and the regenerated extractant produced by the second back-extraction machine flows into the secondary extractor for reuse. The chlorine-rich extractant produced by the three-stage extractor flows into the three-stage back-extraction machine, and the regenerated extractant produced by the three-stage back-extraction machine flows into the three-stage extractor for reuse.

[0013] According to some embodiments of the method for desulfurization and dechlorination of desulfurization wastewater from thermal power plants described in this application, the method further includes the step of collecting byproducts flowing out of the outlets of the No. 1, No. 2, and No. 3 back-extraction machines using a byproduct collection device.

[0014] According to some embodiments of the method for extracting and dechlorinating desulfurized wastewater from thermal power plants described in this application, the first composite extractant, the second composite extractant, and the third composite extractant each independently include a main extractant, a diluent, a first modifier, and / or a second modifier. The main extractant includes trioctylamine; The diluent includes tributyl phosphate; The first modifier includes isooctanol; The second modifier includes n-octanol.

[0015] According to some embodiments of the method for extracting and dechlorinating desulfurization wastewater from thermal power plants described in this application, when the mass concentration of chlorine in the desulfurization wastewater is 10,000-20,000 mg / L, the composite extractant used includes a main extractant, a first modifier, and a diluent in a mass ratio of 6:3:1, and the extraction time is 1.5-2.5 min. When the mass concentration of chlorine in the desulfurization wastewater is 5000-10000 mg / L, the composite extractant used includes a main extractant, a first modifier, a second modifier, and a diluent in a mass ratio of 6:2:1:1, and the extraction time is 2.5-3.5 min. When the mass concentration of chlorine in the desulfurization wastewater is 1000-5000 mg / L, the composite extractant used includes a main extractant, a first modifier, a second modifier, and a diluent in a mass ratio of 6:1:2:1, and the extraction time is 3.5-4.5 min. When the mass concentration of chlorine in the desulfurization wastewater is <1000mg / L, the composite extractant used includes an extractant, a second modifier, and a diluent in a mass ratio of 6:3:1, and the extraction time is 4.5-5.5min.

[0016] The beneficial effects of this application include: the desulfurization wastewater extraction and dechlorination device of the thermal power plant described in this application, through the graded adaptation of the composite extractant and the synergistic effect of the multi-stage extraction device, can flexibly adjust the composite extractant and set the optimal extraction time for desulfurization wastewater with different initial concentrations, so as to achieve efficient and selective extraction of chloride ions, and significantly improve the efficiency and stability of desulfurization wastewater dechlorination treatment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the extraction and dechlorination device for desulfurization wastewater from a thermal power plant as described in this application.

[0018] In the diagram: 1 is the primary extractor, 2 is the secondary extractor, 3 is the tertiary extractor, 4 is the first back-extraction machine, 5 is the second back-extraction machine, 6 is the third back-extraction machine, 7 is the by-product collection device, 8 is the first compound extractant dosing device, 9 is the second compound extractant dosing device, 10 is the third compound extractant dosing device, 11 is the back-extraction agent dosing device, 12 is the main extractant dosing device, 13 is the diluent dosing device, 14 is the first modifier dosing device, 15 is the second modifier dosing device, 1-1 is the inlet of the primary extractor, 1-2 is the outlet of the primary extractor, 1-3 is the inlet of the primary extractor, 1-4 is the outlet of the primary extractor, 2-1 is the inlet of the secondary extractor, and 2-2 is the outlet of the secondary extractor. 1-2 is the inlet of the secondary extractor, 2-3 is the outlet of the secondary extractor, 3-1 is the water inlet of the tertiary extractor, 3-2 is the water outlet of the tertiary extractor, 3-3 is the inlet of the tertiary extractor, 3-4 is the outlet of the tertiary extractor, 4-1 is the inlet of the first back-extraction machine, 4-2 is the outlet of the first back-extraction machine, 4-3 is the inlet of the first back-extraction machine, 4-4 is the outlet of the first back-extraction machine, 5-1 is the inlet of the second back-extraction machine, 5-2 is the outlet of the second back-extraction machine, 5-3 is the inlet of the second back-extraction machine, 5-4 is the outlet of the second back-extraction machine, 6-1 is the inlet of the first back-extraction machine, 6-2 is the outlet of the first back-extraction machine, 6-3 is the inlet of the first back-extraction machine, 6-4 is the outlet of the first back-extraction machine. Detailed Implementation

[0019] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0021] This application provides an extraction and dechlorination device for desulfurization wastewater from a thermal power plant, including a primary extractor, a secondary extractor, a tertiary extractor, a first-stage back-extractor, a second-stage back-extractor, and a third-stage back-extractor; The desulfurization wastewater flows into the desulfurization wastewater extraction and dechlorination unit of the thermal power plant through the inlet of the primary extractor, and comes into contact with the first composite extractant in the primary extractor to achieve primary removal of chloride ions in the desulfurization wastewater; the outlet of the primary extractor is connected to the inlet of the secondary extractor, and the outlet of the secondary extractor is connected to the inlet of the tertiary extractor. The outlet of the primary extractor is connected to the inlet of the first reverse extractor, and the outlet of the first reverse extractor is connected to the inlet of the primary extractor. The outlet of the secondary extractor is connected to the inlet of the second back-extraction machine, and the outlet of the second back-extraction machine is connected to the inlet of the secondary extractor. The outlet of the three-stage extractor is connected to the inlet of the third-stage back-extraction machine, and the outlet of the third-stage back-extraction machine is connected to the inlet of the three-stage extractor.

[0022] The desulfurization wastewater extraction and dechlorination device described in this application, through the graded adaptation of composite extractants and the synergistic effect of multi-stage extraction devices, can flexibly adjust the composite extractants and set the optimal extraction time for desulfurization wastewater with different initial concentrations, thereby achieving efficient and selective extraction of chloride ions and significantly improving the efficiency and stability of desulfurization wastewater dechlorination treatment.

[0023] In some embodiments of this application, a first composite extractant dosing device, a second composite extractant dosing device, and a third composite extractant dosing device are also included. The first composite extractant dosing device is connected to the inlet of the primary extractor and is used to add the first composite extractant to the primary extractor. The second composite extractant dosing device is connected to the inlet of the secondary extractor and is used to add the second composite extractant into the secondary extractor. The third composite extractant dosing device is connected to the inlet of the three-stage extractor and is used to add the third composite extractant into the three-stage extractor.

[0024] The desulfurization wastewater extraction and dechlorination device described in this application can select and formulate the appropriate type of composite extractant according to the initial concentration of chloride ions in the desulfurization wastewater to achieve the best dechlorination effect.

[0025] In some embodiments of this application, a back-extraction agent dosing device is also included. The back-extraction agent dosing device is connected to the inlet of the No. 1 back-extraction machine, the inlet of the No. 2 back-extraction machine, and the inlet of the No. 3 back-extraction machine via a three-way valve, and is used to add back-extraction agent to the No. 1 back-extraction machine, the No. 2 back-extraction machine, and the No. 3 back-extraction machine.

[0026] In some embodiments of this application, a by-product collection device is also included; the outlets of the No. 1 back-extraction machine, the No. 2 back-extraction machine, and the No. 3 back-extraction machine are all connected to the by-product collection device.

[0027] In some embodiments of this application, a main extractant dosing device, a first modifier dosing device, a second modifier dosing device, and a diluent dosing device are also included. The main extractant dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve. Online flow meters are installed on the pipelines connecting the main extractant dosing device and the first, second, and third composite extractant dosing devices, which can accurately control the flow rate of the main extractant entering the pipeline.

[0028] The first modifier dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve. Online flow meters are installed on the pipelines connecting the first modifier dosing device and the first, second, and third composite extractant dosing devices, which can accurately control the flow rate of the first modifier entering the pipeline.

[0029] The second modifier dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve. Online flow meters are installed on the pipelines connecting the second modifier dosing device and the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device, which can accurately control the flow rate of the second modifier entering the pipeline.

[0030] The diluent dosing device is connected to the first, second, and third composite extractant dosing devices via three-way valves. Online flow meters are installed on the pipes connecting the diluent dosing device to each of the three devices, allowing for precise control of the diluent flow rate.

[0031] This application also provides a method for extracting and dechlorinating desulfurization wastewater from a thermal power plant, which is implemented using the thermal power plant desulfurization wastewater extraction and dechlorination device described in the first aspect of this application.

[0032] In some embodiments of this application, the process includes the following steps: desulfurization wastewater is input into the inlet of a primary extractor, and a first composite extractant is added into the inlet of the primary extractor; the desulfurization wastewater and the first composite extractant are mixed and reacted to achieve primary dechlorination; the desulfurization wastewater after primary dechlorination flows into a secondary extractor and is mixed and reacted with a second composite extractant to achieve secondary dechlorination; the desulfurization wastewater after secondary dechlorination flows into a tertiary extractor and is mixed and reacted with a third composite extractant to achieve tertiary dechlorination. The chlorine-rich extractant produced by the primary extractor flows into the No. 1 back-extraction machine, and the regenerated extractant produced by the No. 1 back-extraction machine flows into the primary extractor for reuse. The chlorine-rich extractant produced by the secondary extractor flows into the secondary back-extraction machine, and the regenerated extractant produced by the second back-extraction machine flows into the secondary extractor for reuse. The chlorine-rich extractant produced by the three-stage extractor flows into the three-stage back-extraction machine, and the regenerated extractant produced by the three-stage back-extraction machine flows into the three-stage extractor for reuse.

[0033] The desulfurization wastewater extraction and dechlorination device for thermal power plants described in this application, through the graded adaptation of composite extractants and the synergistic effect of multi-stage extraction devices, can flexibly adjust the composite extractants and set the optimal extraction time for desulfurization wastewater with different initial concentrations, achieving efficient and selective extraction of chloride ions and significantly improving the efficiency and stability of desulfurization wastewater dechlorination treatment. Furthermore, the composite extractants can be reused through the action of a back-extraction machine.

[0034] In some embodiments of this application, the step of collecting byproducts flowing out of the outlets of the No. 1 back-extractor, the No. 2 back-extractor, and the No. 3 back-extractor is further included using a byproduct collection device.

[0035] In some embodiments of this application, the first composite extractant, the second composite extractant, and the third composite extractant each independently include a main extractant, a diluent, a first modifier, and / or a second modifier; The main extractant includes trioctylamine; The diluent includes tributyl phosphate; The first modifier includes isooctanol; The second modifier includes n-octanol.

[0036] In some embodiments of this application, when the mass concentration of chlorine in the desulfurization wastewater is 10,000-20,000 mg / L, the composite extractant used includes a main extractant, a first modifier, and a diluent in a mass ratio of 6:3:1, and the extraction time is 1.5-2.5 min. When the mass concentration of chlorine in the desulfurization wastewater is 5000-10000 mg / L, the composite extractant used includes a main extractant, a first modifier, a second modifier, and a diluent in a mass ratio of 6:2:1:1, and the extraction time is 2.5-3.5 min. When the mass concentration of chlorine in the desulfurization wastewater is 1000-5000 mg / L, the composite extractant used includes a main extractant, a first modifier, a second modifier, and a diluent in a mass ratio of 6:1:2:1, and the extraction time is 3.5-4.5 min. When the mass concentration of chlorine in the desulfurization wastewater is <1000mg / L, the composite extractant used includes a main extractant, a second modifier, and a diluent in a mass ratio of 6:3:1, and the extraction time is 4.5-5.5min.

[0037] The type of extractant and reaction time for each stage are determined based on the chloride ion concentration in the desulfurization wastewater. For example, for desulfurization wastewater with a chloride ion concentration range of 10,000-20,000 mg / L, type A composite extractant (composite extractant includes main extractant, first modifier, and diluent in a mass ratio of 6:3:1) is selected for stage A, with a reaction time of 2 minutes. When the chloride ion concentration in the desulfurization wastewater is 5,000-10,000 mg / L, type B composite extractant (composite extractant includes main extractant, first modifier, second modifier, and diluent in a mass ratio of 6:2:1:1) is selected, with a reaction time of 3 minutes. When the chloride ion concentration in the desulfurization wastewater is 1,000-5,000 mg / L, type C composite extractant (composite extractant includes main extractant, first modifier, second modifier, and diluent in a mass ratio of 6:1:2:1) is selected, with a reaction time of 4 minutes. When the mass concentration of chlorine in the desulfurization wastewater is <1000 mg / L, type D composite extractant (composite extractant includes a main extractant, a second modifier, and a diluent with a mass ratio of 6:3:1) should be selected, and the reaction time should be 3 min.

[0038] The desulfurization wastewater enters through the inlet of the primary extractor and flows sequentially through the secondary and tertiary extractors. In each extractor, the wastewater fully contacts and reacts with the corresponding composite extractants, gradually removing chloride ions. The chloride ions are transferred to the organic phase, and the final treated wastewater is discharged from the outlet of the tertiary extractor. The primary extraction removes approximately 50% of chloride ions, the secondary extraction cumulatively removes approximately 80%, and the tertiary extraction cumulatively removes over 97%.

[0039] The composite extractant used in the primary, secondary, and tertiary extraction machines is added by the corresponding composite extractant dosing devices (No. 1, No. 2, and No. 3). The composite extractant is automatically prepared and added to each extraction machine according to the formula through the main extractant dosing device, the first modifier dosing device, the second modifier dosing device, and the diluent dosing device. The chlorine-rich saturated extractant produced by the primary, secondary, and tertiary extraction machines is regenerated in the No. 1, No. 2, and No. 3 back-extraction machines. The byproducts generated during back-extraction are collected by the byproduct collection device for resource utilization. The regenerated composite extractant from the No. 1, No. 2, and No. 3 back-extraction machines is collected and recycled by the corresponding composite extractant dosing devices. The back-extraction agent used for regeneration is added by the back-extraction agent dosing device.

[0040] The dosage of the main extractant, the first modifier, the second modifier, and the diluent is automatically controlled by the corresponding automatic valves and online flow meters.

[0041] The No. 1 compound agent dosing device, the No. 2 compound agent dosing device, and the No. 3 compound agent dosing device can all prepare any one of the following: type A compound extractant, type B compound extractant, type C compound extractant, and type D compound extractant.

[0042] The technical solution of this application will be further described below with reference to specific embodiments.

[0043] Example 1 A desulfurization and dechlorination device for desulfurization wastewater from a thermal power plant includes a primary extractor, a secondary extractor, a tertiary extractor, a first back-extractor, a second back-extractor, and a third back-extractor. Desulfurization wastewater flows into the desulfurization wastewater extraction and dechlorination unit of the thermal power plant through the inlet of the primary extractor, where it comes into contact with the first composite extractant in the primary extractor to achieve primary removal of chloride ions from the wastewater. The outlet of the primary extractor is connected to the inlet of the secondary extractor, and the outlet of the secondary extractor is connected to the inlet of the tertiary extractor. The desulfurization wastewater flows sequentially through the secondary and tertiary extractors, where it fully contacts and reacts with the corresponding composite extractants to gradually remove chloride ions from the wastewater. The chloride ions are transferred to the organic phase, and the finally treated wastewater is discharged from the outlet of the tertiary extractor.

[0044] The outlet of the primary extractor is connected to the inlet of the first back-extraction unit, and the outlet of the first back-extraction unit is connected to the inlet of the primary extractor. The outlet of the secondary extractor is connected to the inlet of the second back-extraction unit, and the outlet of the second back-extraction unit is connected to the inlet of the secondary extractor. The outlet of the tertiary extractor is connected to the inlet of the third back-extraction unit, and the outlet of the third back-extraction unit is connected to the inlet of the tertiary extractor. The chlorine-rich saturated extractant produced by the primary, secondary, and tertiary extractors is regenerated in the corresponding back-extraction units. The apparatus described in this application also includes a by-product collection device. The outlets of the first, second, and third back-extraction units are all connected to the by-product collection device, which collects the by-products for resource utilization.

[0045] The apparatus described in this application embodiment further includes a first composite extractant dosing device, a second composite extractant dosing device, and a third composite extractant dosing device. The first composite extractant dosing device is connected to the inlet of the primary extractor and is used to add the first composite extractant to the primary extractor. The second composite extractant dosing device is connected to the inlet of the secondary extractor and is used to add the second composite extractant to the secondary extractor. The third composite extractant dosing device is connected to the inlet of the tertiary extractor and is used to add the third composite extractant to the tertiary extractor. The composite extractants generated during the regeneration of the No. 1, No. 2, and No. 3 back-extraction machines are collected in the corresponding No. 1, No. 2, and No. 3 composite extractant dosing devices for recycling. The back-extraction agent used for regeneration is added by the back-extraction agent dosing device. The back-extraction agent dosing device is connected to the inlet of back-extraction machine No. 1, back-extraction machine No. 2 and back-extraction machine No. 3 respectively through a three-way valve, and is used to add back-extraction agent to back-extraction machine No. 1, back-extraction machine No. 2 and back-extraction machine No. 3.

[0046] The composite extractant is automatically prepared and added to each stage of the extraction machine according to the formula through the main extractant addition device, the first modifier addition device, the second modifier addition device, and the diluent addition device. The chlorine-rich saturated extractant produced by the first, second, and third stage extraction machines is regenerated in the first, second, and third back-extraction machines, respectively. The by-products generated by back-extraction are collected by the by-product collection device for resource utilization. The composite extractant after regeneration in the first, second, and third back-extraction machines is collected and recycled in the first, second, and third composite extractant addition devices, respectively. The back-extraction agent used for regeneration is added by the back-extraction agent addition device.

[0047] The main extractant dosing device is connected to the first, second, and third composite extractant dosing devices via three-way valves. The first modifier dosing device is also connected to these devices via three-way valves. The second modifier dosing device is also connected to these devices via three-way valves. The diluent dosing device is connected to these three devices via three-way valves. The composite extractant is automatically prepared and added to each stage of the extraction machine according to the formula via the main extractant dosing device, the first modifier dosing device, the second modifier dosing device, and the diluent dosing device.

[0048] Example 2 A method for extracting and dechlorinating desulfurization wastewater from a thermal power plant is implemented using the extraction and dechlorination device for desulfurization wastewater from a thermal power plant described in Example 1. The specific operating steps include: The chloride ion concentration in the desulfurization wastewater is 15000 mg / L. The following extraction methods were determined: First-stage extraction: Type A composite extractant (composed of trioctylamine, isooctyl alcohol, and tributyl phosphate in a mass ratio of 6:3:1), with an extraction reaction time of 2 min; Second-stage extraction: Type B composite extractant (composed of trioctylamine, isooctyl alcohol, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:2:1:1), with an extraction reaction time of 3 min; Tertiary extraction: Type C composite extractant (composed of trioctylamine, isooctyl alcohol, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:1:2:1), with an extraction reaction time of 4 min.

[0049] The desulfurization wastewater enters through the inlet of the primary extractor and flows sequentially through the secondary and tertiary extractors. In each extractor, the wastewater fully contacts and reacts with the corresponding composite extractant, gradually removing chloride ions from the wastewater. The chloride ions are transferred to the organic phase, and the treated wastewater is finally discharged from the outlet of the tertiary extractor.

[0050] The composite extractant used in the primary, secondary, and tertiary extraction machines is added by the corresponding composite extractant dosing devices (No. 1, No. 2, and No. 3). The composite extractant is automatically prepared and added to each extraction machine according to the formula through the main extractant dosing device, the first modifier dosing device, the second modifier dosing device, and the diluent dosing device. The chlorine-rich saturated extractant produced by the primary, secondary, and tertiary extraction machines is regenerated in the No. 1, No. 2, and No. 3 back-extraction machines. The byproducts generated during back-extraction are collected by the byproduct collection device for resource utilization. The regenerated composite extractant from the No. 1, No. 2, and No. 3 back-extraction machines is collected and recycled by the corresponding composite extractant dosing devices. The back-extraction agent used for regeneration is added by the back-extraction agent dosing device.

[0051] The dosage of the main extractant, the first modifier, the second modifier, and the diluent is automatically controlled by the corresponding automatic valves and online flow meters.

[0052] After primary extraction, the chloride ion concentration decreased to 7500 mg / L, after secondary extraction to 3000 mg / L, and after tertiary extraction to 450 mg / L.

[0053] Example 3 A method for extracting and dechlorinating desulfurization wastewater from a thermal power plant is implemented using the extraction and dechlorination device for desulfurization wastewater from a thermal power plant described in Example 1. The specific operating steps include: The chloride ion concentration in the desulfurization wastewater was 7500 mg / L. The following extraction methods were determined: First-stage extraction used a type B composite extractant (composed of trioctylamine, isooctyl alcohol, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:2:1:1), with an extraction reaction time of 3 min; Second-stage extraction used a type C composite extractant (composed of trioctylamine, isooctyl alcohol, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:1:2:1), with an extraction reaction time of 4 min; Third-stage extraction used a type C composite extractant (composed of trioctylamine, isooctyl alcohol, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:1:2:1), with an extraction reaction time of 4 min.

[0054] The desulfurization wastewater enters through the inlet of the primary extractor and flows sequentially through the secondary and tertiary extractors. In each extractor, the wastewater fully contacts and reacts with the corresponding composite extractant, gradually removing chloride ions from the wastewater. The chloride ions are transferred to the organic phase, and the treated wastewater is finally discharged from the outlet of the tertiary extractor.

[0055] The composite extractant used in the primary, secondary, and tertiary extraction machines is added by the corresponding composite extractant dosing devices (No. 1, No. 2, and No. 3). The composite extractant is automatically prepared and added to each extraction machine according to the formula through the main extractant dosing device, the first modifier dosing device, the second modifier dosing device, and the diluent dosing device. The chlorine-rich saturated extractant produced by the primary, secondary, and tertiary extraction machines is regenerated in the No. 1, No. 2, and No. 3 back-extraction machines. The byproducts generated during back-extraction are collected by the byproduct collection device for resource utilization. The regenerated composite extractant from the No. 1, No. 2, and No. 3 back-extraction machines is collected and recycled by the corresponding composite extractant dosing devices. The back-extraction agent used for regeneration is added by the back-extraction agent dosing device.

[0056] The dosage of the main extractant, the first modifier, the second modifier, and the diluent is automatically controlled by the corresponding automatic valves and online flow meters.

[0057] After primary extraction, the chloride ion concentration decreased to 3750 mg / L, after secondary extraction to 1500 mg / L, and after tertiary extraction to 225 mg / L.

[0058] Example 4 A method for extracting and dechlorinating desulfurization wastewater from a thermal power plant is implemented using the extraction and dechlorination device for desulfurization wastewater from a thermal power plant described in Example 1. The specific operating steps include: The concentration of chloride ions in the desulfurization wastewater is 4000 mg / L. The following extraction methods were determined: First-stage extraction: Use a type C composite extractant (composed of trioctylamine, isooctyl alcohol, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:1:2:1), with an extraction reaction time of 4 min; Second-stage extraction: Use a type D composite extractant (composed of trioctylamine, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:3:1), with an extraction reaction time of 5 min; Third-stage extraction: Use a type D composite extractant (composed of trioctylamine, n-octyl alcohol, and tributyl phosphate in a mass ratio of 6:3:1), with an extraction reaction time of 5 min.

[0059] The desulfurization wastewater enters through the inlet of the primary extractor and flows sequentially through the secondary and tertiary extractors. In each extractor, the wastewater fully contacts and reacts with the corresponding composite extractant, gradually removing chloride ions from the wastewater. The chloride ions are transferred to the organic phase, and the treated wastewater is finally discharged from the outlet of the tertiary extractor.

[0060] The composite extractant used in the primary, secondary, and tertiary extraction machines is added by the corresponding composite extractant dosing devices (No. 1, No. 2, and No. 3). The composite extractant is automatically prepared and added to each extraction machine according to the formula through the main extractant dosing device, the first modifier dosing device, the second modifier dosing device, and the diluent dosing device. The chlorine-rich saturated extractant produced by the primary, secondary, and tertiary extraction machines is regenerated in the No. 1, No. 2, and No. 3 back-extraction machines. The byproducts generated during back-extraction are collected by the byproduct collection device for resource utilization. The regenerated composite extractant from the No. 1, No. 2, and No. 3 back-extraction machines is collected and recycled by the corresponding composite extractant dosing devices. The back-extraction agent used for regeneration is added by the back-extraction agent dosing device.

[0061] The dosage of the main extractant, the first modifier, the second modifier, and the diluent is automatically controlled by the corresponding automatic valves and online flow meters.

[0062] After primary extraction, the chloride ion concentration decreased to 2000 mg / L, after secondary extraction to 800 mg / L, and after tertiary extraction to 120 mg / L.

[0063] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A dechlorination extraction device for desulfurization wastewater from a thermal power plant, characterized in that, This includes a primary extraction machine, a secondary extraction machine, a tertiary extraction machine, a No. 1 back-extraction machine, a No. 2 back-extraction machine, and a No. 3 back-extraction machine; The desulfurization wastewater flows into the desulfurization wastewater extraction and dechlorination unit of the thermal power plant through the inlet of the primary extractor, and comes into contact with the first composite extractant in the primary extractor to achieve primary removal of chloride ions in the desulfurization wastewater; the outlet of the primary extractor is connected to the inlet of the secondary extractor, and the outlet of the secondary extractor is connected to the inlet of the tertiary extractor. The outlet of the primary extractor is connected to the inlet of the first reverse extractor, and the outlet of the first reverse extractor is connected to the inlet of the primary extractor. The outlet of the secondary extractor is connected to the inlet of the second back-extraction machine, and the outlet of the second back-extraction machine is connected to the inlet of the secondary extractor. The outlet of the three-stage extractor is connected to the inlet of the third-stage back-extraction machine, and the outlet of the third-stage back-extraction machine is connected to the inlet of the three-stage extractor.

2. The extraction and dechlorination device for desulfurization wastewater from thermal power plants according to claim 1, characterized in that, It also includes a first compound extractant dosing device, a second compound extractant dosing device and a third compound extractant dosing device. The first compound extractant dosing device is connected to the inlet of the primary extractor and is used to add the first compound extractant to the primary extractor. The second composite extractant dosing device is connected to the inlet of the secondary extractor and is used to add the second composite extractant into the secondary extractor. The third composite extractant dosing device is connected to the inlet of the three-stage extractor and is used to add the third composite extractant into the three-stage extractor.

3. The extraction and dechlorination device for desulfurization wastewater from thermal power plants according to claim 1, characterized in that, It also includes a back-extraction agent dosing device, which is connected to the inlet of the No. 1 back-extraction machine, the inlet of the No. 2 back-extraction machine and the inlet of the No. 3 back-extraction machine respectively through a three-way valve, and is used to add back-extraction agent to the No. 1 back-extraction machine, the No. 2 back-extraction machine and the No. 3 back-extraction machine.

4. The extraction and dechlorination device for desulfurization wastewater from thermal power plants according to claim 1, characterized in that, It also includes a by-product collection device; the outlets of the No. 1 back-extraction machine, the No. 2 back-extraction machine, and the No. 3 back-extraction machine are all connected to the by-product collection device.

5. The extraction and dechlorination device for desulfurization wastewater from thermal power plants according to claim 3, characterized in that, It also includes a main extractant dosing device, a first modifier dosing device, a second modifier dosing device, and a diluent dosing device; The main extractant dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve. The first modifier dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve; The second modifier dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve; The diluent dosing device is connected to the first composite extractant dosing device, the second composite extractant dosing device, and the third composite extractant dosing device via a three-way valve.

6. A method for extracting and dechlorinating desulfurization wastewater from a thermal power plant, characterized in that, The process is carried out using the extraction and dechlorination device for desulfurization wastewater from thermal power plants as described in any one of claims 1-5.

7. The method for extracting and dechlorinating desulfurization wastewater from thermal power plants according to claim 6, characterized in that, Includes the following steps: Desulfurization wastewater is input into the inlet of the primary extractor, and the first composite extractant is added through the inlet of the primary extractor. The desulfurization wastewater and the first composite extractant react to achieve primary dechlorination. The desulfurization wastewater after primary dechlorination flows into the secondary extractor and reacts with the second composite extractant to achieve secondary dechlorination. The desulfurization wastewater after secondary dechlorination flows into the tertiary extractor and reacts with the third composite extractant to achieve tertiary dechlorination. The chlorine-rich extractant produced by the primary extractor flows into the No. 1 back-extraction machine, and the regenerated extractant produced by the No. 1 back-extraction machine flows into the primary extractor for reuse. The chlorine-rich extractant produced by the secondary extractor flows into the secondary back-extraction machine, and the regenerated extractant produced by the second back-extraction machine flows into the secondary extractor for reuse. The chlorine-rich extractant produced by the three-stage extractor flows into the three-stage back-extraction machine, and the regenerated extractant produced by the three-stage back-extraction machine flows into the three-stage extractor for reuse.

8. The method for extracting and dechlorinating desulfurization wastewater from thermal power plants according to claim 7, characterized in that, It also includes the step of collecting the byproducts flowing out of the outlets of the No. 1, No. 2 and No. 3 back-extraction machines using a byproduct collection device.

9. The method for extracting and dechlorinating desulfurization wastewater from thermal power plants according to claim 7, characterized in that, The first composite extractant, the second composite extractant, and the third composite extractant each independently include a main extractant, a diluent, a first modifier, and / or a second modifier; The main extractant includes trioctylamine; The diluent includes tributyl phosphate; The first modifier includes isooctanol; The second modifier includes n-octanol.

10. The method for extracting and dechlorinating desulfurization wastewater from thermal power plants according to claim 7, characterized in that, When the mass concentration of chlorine in the desulfurization wastewater is 10,000-20,000 mg / L, the composite extractant used includes a main extractant, a first modifier, and a diluent in a mass ratio of 6:3:1, and the extraction time is 1.5-2.5 min. When the mass concentration of chlorine in the desulfurization wastewater is 5000-10000 mg / L, the composite extractant used includes a main extractant, a first modifier, a second modifier, and a diluent in a mass ratio of 6:2:1:1, and the extraction time is 2.5-3.5 min. When the mass concentration of chlorine in the desulfurization wastewater is 1000-5000 mg / L, the composite extractant used includes a main extractant, a first modifier, a second modifier, and a diluent in a mass ratio of 6:1:2:1, and the extraction time is 3.5-4.5 min. When the mass concentration of chlorine in the desulfurization wastewater is <1000mg / L, the composite extractant used includes an extractant, a second modifier, and a diluent in a mass ratio of 6:3:1, and the extraction time is 4.5-5.5min.

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