System and method for eliminating carbon dioxide in water sample

Abstract

The invention belongs to the technical field of nuclear power, and particularly relates to a system and a method for eliminating carbon dioxide in a water sample. According to the invention, the integrated membrane degassing, gas purging and vacuum degassing technologies are combined with the control system, so that carbon dioxide can be efficiently removed on the premise of keeping the original characteristics of the water sample, and the water sample treatment efficiency and quality are greatly improved. The branch pipeline is led out of the main pipeline and connected with the pressure reducing device, the water sample is guided into the system for multi-stage filtration, pH value adjustment and efficient CO2 removal treatment, the problem that CO2 in the water sample is difficult to efficiently and stably remove in a traditional method is solved, the quality of the water sample of the nuclear power plant before ion chromatography analysis is ensured, and the detection accuracy is improved. And the accuracy and reliability of an analysis result are ensured.

Description

Technical Field

[0001] This disclosure pertains to the field of nuclear power technology, specifically relating to a system and method for removing carbon dioxide from a water sample. Background Technology

[0002] In related technologies, nuclear power plants often require regular water quality testing and continuous monitoring. Ion chromatography plays a crucial role in water sample monitoring at nuclear power plants, helping to ensure that water quality in various aspects, including cooling water systems, wastewater treatment, and reactor safety, meets stringent safety and environmental standards. Through its high sensitivity, high resolution, and powerful separation capabilities, ion chromatography can accurately monitor the ionic composition, corrosion products, and contaminants in water samples, thereby supporting the safe operation and environmental compliance management of nuclear power plants.

[0003] Among the various analytical methods, the carbon dioxide (CO2) content in water samples is one of the key factors affecting the accuracy of analytical results. Samples analyzed by ion chromatography (IC) contain carbon dioxide, which dissolves in water to form carbonic acid, subsequently partially dissociating into bicarbonate and carbonate ions. This leads to a decrease in the solution's pH value. Changes in pH can affect the morphology and behavior of target ions, thus impacting the separation efficiency and quantitative accuracy of ion chromatography. Furthermore, bicarbonate and carbonate ions are strongly retained ions, potentially competing with target ions for adsorption sites on the chromatographic column, leading to peak overlap or decreased resolution, affecting the accuracy of quantitative analysis. The strong retention characteristics of bicarbonate and carbonate ions can also cause them to accumulate on the chromatographic column, reducing its separation efficiency and shortening its lifespan. Therefore, it is crucial to effectively remove carbon dioxide from water samples before performing ion chromatography analysis to avoid interfering with the analytical results. Summary of the Invention

[0004] To overcome the problems existing in related technologies, a system and method for removing carbon dioxide from water samples are provided.

[0005] According to one aspect of the present disclosure, a system for removing carbon dioxide from a water sample is provided. The system includes: a sample pretreatment unit, a CO2 removal unit, a control system, and a post-treatment unit. The sample pretreatment unit includes a filter and an adjustment tank for removing impurities from the water sample and adjusting the pH value of the water sample. The CO2 removal unit is connected downstream of the pretreatment unit for removing CO2 from the pretreated water sample. The control system includes sensors and a control module for ensuring the coordinated operation of each module and real-time monitoring of parameter changes based on pH data and air pressure data collected by the sensors in the water sample.

[0006] In one possible implementation, the filter includes a first filter and a second filter. The first filter has a pore size of no more than 5 micrometers and is installed at the inlet of a branch pipe for first-pass filtration of the water sample. The second filter has a pore size of no more than 0.2 micrometers and is installed downstream of the first filter for second-pass filtration of the water sample.

[0007] In one possible implementation, the filter is made of polytetrafluoroethylene or polyethersulfone.

[0008] In one possible implementation, the conditioning tank is connected downstream of the filter for adjusting the pH value of the water sample. The conditioning tank is equipped with a first pH sensor for real-time monitoring of the pH value of the water sample. When the control module detects from the first pH sensor that the pH value of the water sample does not meet the threshold, it controls the regulator to add regulator to adjust the pH of the water sample in the conditioning tank until the pH value of the water sample meets the threshold.

[0009] In one possible implementation, the CO2 elimination unit includes a membrane degassing module, a gas purging module, and a vacuum degassing module;

[0010] The membrane degassing module is connected downstream of the equalization tank, and the gas purging module, vacuum degassing module and membrane degassing module are connected in sequence via pipelines.

[0011] When a water sample passes through the water-blocking and air-permeable membrane of the membrane degassing module, the water-blocking and air-permeable membrane can effectively prevent water from entering the gas side, allowing CO2 to diffuse through the micropores of the membrane to the gas side of the membrane. Dry nitrogen gas is introduced into the gas side, which can effectively remove the CO2 released from the water sample.

[0012] The control module automatically adjusts the working state of the vacuum pump by setting the vacuum pump and pressure sensor to achieve negative pressure. Through the adjustment of the control module, the negative pressure control of the vacuum degassing module can be realized.

[0013] The gas purging module also includes a purging pipeline, a diffuser, and a gas collection pipeline. The purging pipeline is connected to the nitrogen supply system and the end of the purging pipeline is in contact with the water sample. It is used to evenly distribute nitrogen into the water sample, and the nitrogen is in full contact with the water sample. The nitrogen carries away the CO2 molecules dissolved in the water through bubbles and enters the gas collection pipeline.

[0014] The vacuum degassing module can extract the gas from CO2 using a vacuum pump, creating a low-pressure environment. At this time, CO2 in the water sample will escape from the water due to the pressure difference and changes in gas solubility.

[0015] In one possible implementation, the rate at which nitrogen is introduced into the gas side of the water-resistant and breathable membrane is not less than 1 liter per minute.

[0016] In one possible implementation, the control system's sensors further include multiple CO2 concentration sensors, with CO2 concentration sensors installed at the front and rear ends of the CO2 elimination unit, respectively. The control module monitors the CO2 concentration of the water sample before and after treatment based on data collected by the CO2 concentration sensors installed before and after the CO2 elimination unit.

[0017] In one possible implementation, the sensors of the control system further include multiple pressure sensors. Pressure sensors are installed on the gas side of the vacuum degassing module and the membrane degassing module, respectively. The control module adjusts the working state of the vacuum pump according to the pressure sensors installed on the gas side of the membrane degassing module, so that the negative pressure state of the vacuum degassing module and the membrane degassing module is maintained at a set value.

[0018] According to another aspect of the present disclosure, a method for removing carbon dioxide from a water sample is provided, the method comprising the following steps:

[0019] Step 1: Draw a portion of the water sample from the main pipeline and pass it through a pressure reducing valve into the branch pipeline;

[0020] Step 2: Filter the water sample sequentially through the first filter and the second filter to remove particulate impurities from the water sample;

[0021] Step 3: Based on Step 2, use the equalization tank to adjust the pH value of the water sample to a suitable range;

[0022] Step four: Based on step three, carbon dioxide in the water sample is removed sequentially using a membrane degassing module, a gas purging module, and a vacuum degassing module, while the control system monitors and adjusts the working status of each module in real time.

[0023] Step 5: Adjust the pH value of the treated water sample using the post-processing unit, and then send the treated water sample into the ion chromatography analysis system.

[0024] The beneficial effects of the system for removing carbon dioxide from water samples disclosed herein are as follows:

[0025] 1. This disclosure utilizes integrated membrane degassing, gas purging, and vacuum degassing technologies, combined with a control system, to efficiently remove carbon dioxide while maintaining the original characteristics of the water sample, thereby greatly improving the efficiency and quality of water sample treatment.

[0026] 2. This disclosure introduces a branch pipe from the main pipeline and connects it to a pressure reducing device to introduce the water sample into the system for multi-stage filtration, pH adjustment, and efficient CO2 removal. This solves the problem of difficult and stable removal of CO2 from water samples in traditional methods, ensuring the quality of nuclear power plant water samples before ion chromatography analysis and guaranteeing the accuracy and reliability of the analysis results. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a system for removing carbon dioxide from a water sample, as shown in an embodiment of this disclosure.

[0028] In the picture:

[0029] 1-Decompression device; 2-Sample pretreatment unit; 21-First filter; 22-Second filter;

[0030] 23-Equalization tank; 3-CO2 elimination unit; 31-Membrane degassing module; 32-Gas purging module;

[0031] 33-Vacuum degassing module; 34-Chlorine supply system; 35-Vacuum pump; 4-Control system;

[0032] 41-First pH sensor; 42-CO2 concentration sensor; 43-Pressure sensor;

[0033] 44-Second pH sensor; 5-Post-processing unit; 6-Main pipeline; 7-Ion chromatography analysis system. Detailed Implementation

[0034] The present disclosure will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0035] Unless otherwise defined, the technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains; the terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure; the term "comprising" and any variations thereof in this disclosure are intended to cover non-exclusive inclusion. Clearly, the embodiments described in this disclosure are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure.

[0036] In this disclosure, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] Figure 1 This is a schematic diagram of a system for removing carbon dioxide from a water sample, as shown in an embodiment of this disclosure. Figure 1As shown, the system is connected to a branch pipe leading from the main pipe 6. The system includes a sample pretreatment unit 2, a CO2 elimination unit 3, a control system 4, and a post-treatment unit 5. The sample pretreatment unit 2 includes a filter and an equalization tank 23, used to remove impurities from the water sample and adjust the pH value of the water sample. The CO2 elimination unit includes a membrane degassing module 31, a gas purging module 32, and a vacuum degassing module 33, used to remove CO2. The control system includes sensors and a control module, used to ensure the coordinated operation of each module and to monitor parameter changes in real time.

[0038] In one possible implementation, to avoid clogging subsequent processing devices, a filter is used to remove particulate impurities from the water sample. The filter includes a first filter 21 and a second filter 22. The first filter, with a pore size no greater than 5 micrometers, is installed at the inlet of a branch pipe for the first pass of filtration of the water sample. This removes larger particles, improves system efficiency, and reduces particle load. The second filter, with a pore size no greater than 0.2 micrometers, is installed downstream of the first filter for the second pass of filtration. This removes finer particles, ensuring water sample cleanliness, preventing particle clogging and contamination of the chromatographic column, and facilitating analysis in subsequent ion chromatography. Through the first coarse filtration and the second fine filtration, the water flow rate is minimally affected, system pressure is reduced, and the water sample cleanliness meets filtration requirements, preventing excessive filter clogging and improving overall system efficiency.

[0039] In one possible implementation, the filter material is chosen to be chemically inert, such as polytetrafluoroethylene (PTFE) or polyethersulfone (PES). These materials do not react with the components in the water, avoiding the introduction of new contaminants that could affect IC analysis. They also have sufficient pressure resistance and corrosion resistance, especially for corrosive substances (such as metal ions) in nuclear power plant water samples.

[0040] The conditioning tank 23 is connected downstream of the second filter 22 and is used to adjust the pH value of the water sample. A first pH sensor 41 is installed in the conditioning tank to monitor the pH value of the water sample in real time. If the control module detects from the first pH sensor that the pH value of the water sample does not meet the threshold, it controls the regulator to add regulator to adjust the pH of the water sample in the conditioning tank until the pH value of the water sample meets the threshold. In one possible implementation, the regulator can be selected based on the potential interference it may cause to the analysis and the required pH range.

[0041] like Figure 1 The membrane degassing module 31 is connected downstream of the regulating tank 23, and the gas purging module 32, vacuum degassing module 33 and membrane degassing module 31 are connected in sequence via pipelines.

[0042] The CO2 elimination unit disclosed herein also includes a vacuum pump 35 and a nitrogen supply system 34, which includes two nitrogen supply lines for realizing the functions of the membrane degassing module and the gas purging module, respectively.

[0043] For example, the water-blocking and air-permeable membrane of the membrane degassing module can be a hydrophobic polytetrafluoroethylene membrane. When the water sample passes through the water-blocking and air-permeable membrane, it can effectively prevent moisture from entering the gas side, but allow CO2 to diffuse through the micropores of the membrane to the gas side of the membrane. Dry nitrogen gas is introduced into the gas side, which can effectively remove the CO2 released by the water sample. In order to enhance the flow rate on the gas side and further accelerate the diffusion and removal of CO2, the nitrogen flow rate is set to be no less than 1 liter / minute.

[0044] Furthermore, in order to enhance the diffusion rate of CO2 from water and thus accelerate CO2 removal, the membrane degassing module needs to maintain negative pressure. The control module automatically adjusts the working state of the vacuum pump by setting the vacuum pump 35 and the pressure sensor 43 to achieve negative pressure. Through the adjustment of the control module, precise negative pressure control can be achieved.

[0045] The gas purging module also includes a purging pipeline, a diffuser, and a gas collection pipeline. The purging pipeline connects to the nitrogen supply system and the end of the purging pipeline to contact the water sample. It is used to uniformly distribute nitrogen into the water sample, ensuring full contact between the nitrogen and the water sample. The nitrogen carries away CO2 molecules dissolved in the water through bubbles and enters the gas collection pipeline.

[0046] The vacuum degassing module can extract the gas in CO2 through the vacuum pump 35 to form a low-pressure environment. At this time, CO2 in the water sample will escape from the water due to the pressure difference and the change in gas solubility. In order to reduce the complexity of the system design and reduce the number and cost of pipelines, the exhaust pipeline is merged in this application.

[0047] In summary, by using a triple treatment method of membrane degassing, gas purging, and vacuum degassing, the CO2 concentration in the water sample can be reduced as much as possible.

[0048] The control system includes multiple CO2 concentration sensors and multiple pressure sensors. CO2 concentration sensors are installed at both the front and rear ends of the CO2 elimination unit. The control module monitors the CO2 concentration of the water sample before and after treatment based on data collected by the CO2 concentration sensors installed before and after the CO2 elimination unit. Pressure sensors are installed on the gas side of the vacuum degassing module and the membrane degassing module. The control module controls the vacuum pump and adjusts it to maintain a negative gas pressure based on feedback from the pressure sensors. The control module can be, for example, a PLC control module.

[0049] The post-processing unit includes a pH adjuster to ensure that the pH value of the treated water sample meets the requirements of ion chromatography analysis, improves the stability of the water sample, and avoids pH fluctuations from affecting subsequent analysis results. A second pH sensor 44 is used to monitor the pH value of the water sample.

[0050] In one possible implementation, valves are installed on the pipes between the modules to facilitate system maintenance and fault diagnosis.

[0051] Based on the above system, this disclosure proposes a method for removing carbon dioxide from a water sample, comprising the following steps:

[0052] Step 1: Draw a portion of the water sample from the main pipeline and pass it through a pressure reducing valve into the branch pipeline;

[0053] Step 2: Filter the water sample sequentially through the first filter and the second filter to remove particulate impurities from the water sample;

[0054] Step 3: Based on Step 2, use the equalization tank to adjust the pH value of the water sample to a suitable range;

[0055] Step four: Based on step three, carbon dioxide in the water sample is removed sequentially using a membrane degassing module, a gas purging module, and a vacuum degassing module, while the control system monitors and adjusts the working status of each module in real time.

[0056] Step 5: Adjust the pH value of the treated water sample using the post-processing unit, and then send the treated water sample into the ion chromatography analysis system.

[0057] According to this disclosure, for water samples from nuclear power plants, the system and method can effectively remove CO2 from the water and send the water sample directly into the ion chromatography analysis system 7, ensuring the stability of the water quality and avoiding interference with the analysis results.

[0058] This disclosure discloses a system and method for removing carbon dioxide from water samples. By leading a branch pipe from the main pipeline and connecting it to a pressure reducing device, the water sample is introduced into the system for multi-stage filtration, pH adjustment, and efficient CO2 removal. This solves the problem of difficult and inefficient CO2 removal from water samples in traditional methods, ensuring the quality of nuclear power plant water samples before ion chromatography analysis and guaranteeing the accuracy and reliability of the analysis results.

[0059] This disclosure presents a system and method for removing carbon dioxide from water samples, which realizes the transformation from manual pretreatment of water samples to automated treatment, effectively reducing errors caused by manual operation, reducing the workload of operators, reducing the risk of personnel coming into contact with radioactive water samples, and improving work safety.

[0060] This disclosure discloses a system and method for removing carbon dioxide from water samples. It employs a triple treatment technology of membrane degassing, gas purging, and vacuum degassing, combining the advantages of chemical and physical methods. This not only removes CO2 from the water sample but also preserves its original characteristics, avoiding interference with subsequent ion chromatography analysis. Furthermore, the system uses chemically inert materials to fabricate filters, ensuring the purity of the water sample and improving the accuracy of the analysis.

[0061] This disclosure discloses a system and method for removing carbon dioxide from water samples. Through an integrated control system, the entire treatment process is automatically monitored and regulated, including real-time monitoring of key parameters such as pH value, CO2 concentration, and system pressure. This ensures the stability and controllability of the treatment process and also facilitates the management and maintenance of the system by operators.

[0062] The system and method for removing carbon dioxide from water samples disclosed herein are highly flexible and adaptable. They can be applied not only to the treatment of water samples from nuclear power plants, but also, with appropriate adjustments, to water sample treatment processes in other fields that require CO2 removal, such as industrial wastewater treatment and drinking water purification. They have broad application prospects and good promotional value.

[0063] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A system for removing carbon dioxide from a water sample, characterized in that, The system includes: a sample pretreatment unit, a CO2 elimination unit, a control system, and a post-treatment unit; the sample pretreatment unit includes a filter and an equalization tank for removing impurities from the water sample and adjusting the pH value of the water sample; the CO2 elimination unit is connected downstream of the pretreatment unit for removing CO2 from the pretreated water sample; the control system includes sensors and a control module for ensuring the coordinated operation of each module and real-time monitoring of parameter changes based on the pH and air pressure data collected by the sensors in the water sample.

2. The system according to claim 1, characterized in that, The filter includes a first filter and a second filter. The first filter has a pore size of no more than 5 micrometers and is installed at the inlet of the branch pipe for the first filtration of the water sample. The second filter has a pore size of no more than 0.2 micrometers and is installed downstream of the first filter for the second filtration of the water sample.

3. The system according to claim 1, characterized in that, The filter is made of polytetrafluoroethylene and polyethersulfone.

4. The system according to claim 1, characterized in that, The conditioning tank is connected downstream of the filter and is used to adjust the pH value of the water sample. The conditioning tank is equipped with a first pH sensor for real-time monitoring of the pH value of the water sample. When the control module detects from the first pH sensor that the pH value of the water sample does not meet the threshold, it controls the regulator to add regulator to adjust the pH of the water sample in the conditioning tank until the pH value of the water sample meets the threshold.

5. The system according to claim 1, characterized in that, The CO2 elimination unit includes a membrane degassing module, a gas purging module, and a vacuum degassing module; The membrane degassing module is connected downstream of the equalization tank, and the gas purging module, vacuum degassing module and membrane degassing module are connected in sequence via pipelines. When a water sample passes through the water-blocking and air-permeable membrane of the membrane degassing module, the water-blocking and air-permeable membrane can effectively prevent water from entering the gas side, allowing CO2 to diffuse through the micropores of the membrane to the gas side of the membrane. Dry nitrogen gas is introduced into the gas side, which can effectively remove the CO2 released from the water sample. The control module automatically adjusts the working state of the vacuum pump by setting the vacuum pump and pressure sensor to achieve negative pressure. Through the adjustment of the control module, the negative pressure control of the vacuum degassing module can be realized. The gas purging module also includes a purging pipeline, a diffuser, and a gas collection pipeline. The purging pipeline is connected to the nitrogen supply system and the end of the purging pipeline is in contact with the water sample. It is used to evenly distribute nitrogen into the water sample, and the nitrogen is in full contact with the water sample. The nitrogen carries away the CO2 molecules dissolved in the water through bubbles and enters the gas collection pipeline. The vacuum degassing module can extract the gas from CO2 using a vacuum pump, creating a low-pressure environment. At this time, CO2 in the water sample will escape from the water due to the pressure difference and changes in gas solubility.

6. The system according to claim 5, characterized in that, The rate at which nitrogen gas is introduced into the gas side of the water-resistant and breathable membrane is not less than 1 liter / minute.

7. The system according to claim 1, characterized in that, The control system also includes multiple CO2 concentration sensors. CO2 concentration sensors are installed at the front and rear ends of the CO2 elimination unit, respectively. The control module monitors the CO2 concentration of the water sample before and after treatment based on the data collected by the CO2 concentration sensors installed before and after the CO2 elimination unit.

8. The system according to claim 1, characterized in that, The control system also includes multiple pressure sensors. Pressure sensors are installed on the gas side of the vacuum degassing module and the membrane degassing module, respectively. The control module adjusts the working state of the vacuum pump according to the pressure sensors installed on the gas side of the membrane degassing module, so that the negative pressure state of the vacuum degassing module and the membrane degassing module is maintained at the set value.

9. A method for removing carbon dioxide from a water sample, characterized in that, The process includes the following steps: Step 1: Draw a portion of the water sample from the main pipeline and pass it through a pressure reducing valve into the branch pipeline; Step 2: Filter the water sample sequentially through the first filter and the second filter to remove particulate impurities from the water sample; Step 3: Based on Step 2, use the equalization tank to adjust the pH value of the water sample to a suitable range; Step four: Based on step three, carbon dioxide in the water sample is removed sequentially using a membrane degassing module, a gas purging module, and a vacuum degassing module, while the control system monitors and adjusts the working status of each module in real time. Step 5: Adjust the pH value of the treated water sample using the post-processing unit, and then send the treated water sample into the ion chromatography analysis system.

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