A supercritical carbon dioxide boiler working medium impurity measuring device and method thereof

Abstract

The present application relates to a kind of supercritical carbon dioxide boiler working medium impurity measuring device and method thereof, belong to boiler working medium measurement technical field.Solve is the short development time of emerging supercritical CO2 boiler technology, its quality evaluation system is blank at home and abroad problem.Including sampling valve, flowmeter, first particle filter, temperature and pressure reducing device, pressure gauge, temperature sensor, second particle filter, analyzer and end pump, sampling valve, flowmeter, first particle filter, temperature and pressure reducing device, pressure gauge, temperature sensor, second particle filter, analyzer, end pump are sequentially connected.Can measure the impurity of supercritical carbon dioxide brayton cycle system of power cycle, solve its quality system is blank at home and abroad problem.

Description

Technical Field

[0001] This invention relates to a device and method for measuring the working fluid in a supercritical carbon dioxide boiler, belonging to the field of boiler working fluid measurement technology. Background Technology

[0002] The working medium in supercritical CO2 boilers differs significantly from that in traditional steam boilers. Therefore, supercritical CO2 boilers require a completely new quality evaluation technology system in areas such as material performance, design and manufacturing inspection, operation monitoring, and commissioning. Boilers using water as the medium are subject to strict standards for working medium quality management during operation, with limitations on pH value, impurity types, and content. Low-quality working medium will affect the overall operating performance of the unit and may even threaten safe production.

[0003] As a novel power cycle, the purity, impurity types, and content of CO2 in the Brayton cycle system are closely related to its performance and safety. During long-term operation, the working fluid can cause carbon corrosion of steel; therefore, monitoring the impurity content in the working fluid is crucial for assessing the overall corrosion status of the system's materials. Furthermore, using food-grade CO2 as the working fluid source significantly improves its quality, but the operating cost is far higher than using industrial-grade CO2. However, the development of supercritical CO2 boiler technology is relatively recent, and its quality evaluation system is lacking both domestically and internationally. Therefore, the development of relevant testing and inspection techniques is of great significance for guiding the development of supercritical CO2 boilers.

[0004] Therefore, there is an urgent need to propose a measuring device and method for impurities in the working fluid of supercritical carbon dioxide boilers to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention addresses the issue that the development of emerging supercritical CO2 boiler technology is relatively recent, and its quality evaluation system is lacking both domestically and internationally. A brief overview of the invention is provided below to offer a basic understanding of certain aspects of it. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0006] The technical solution of this invention:

[0007] A measuring device for impurities in the working fluid of a supercritical carbon dioxide boiler includes a sampling valve, a flow meter, a first particulate filter, a desuperheating and pressure reducing device, a pressure gauge, a temperature sensor, a second particulate filter, an analyzer, and an end pump. The sampling valve, flow meter, first particulate filter, desuperheating and pressure reducing device, pressure gauge, temperature sensor, second particulate filter, analyzer, and end pump are connected in sequence.

[0008] Preferably, the analyzer includes an oxygen sensor and a gas phase analyzer arranged in series, and also includes a third filter connected between the second filter and the oxygen sensor.

[0009] Preferably, it also includes a purge valve, and the purge valve and the sampling valve are connected in parallel to the first particulate filter.

[0010] Preferably, the inlet end of the purge valve is connected to a high-pressure gas tank, and the inlet end of the sampling valve is connected to a sampling tube.

[0011] A method for measuring impurities in the working fluid of a supercritical carbon dioxide boiler, comprising the aforementioned measuring device for impurities in the working fluid of a supercritical carbon dioxide boiler, and including the following steps:

[0012] Step 1: Purge the measuring device:

[0013] Before measurement, purging is required. Close the sampling valve and the de-cooling and de-pressure device, and open the purging valve. Purging is complete when the oxygen concentration detected by the analyzer is zero.

[0014] Step 2: Transfer and purify the working fluid:

[0015] Close the purge valve, open the sampling valve and the de-cooling and pressure reducing device. After the sampling working fluid passes through the flow meter for flow measurement, it enters the first particle filter to remove the solid impurities carried by the working fluid itself. Then, it passes through the de-cooling and pressure reducing device to reduce the pressure and temperature of the working fluid to the set value. Subsequently, the working fluid enters the second particle filter. During the separation process of the working fluid in the second particle filter, the working fluid produces metal precipitation crystals due to phase change. Then, the working fluid enters the third particle filter to filter out the residual solid particles.

[0016] Step 3: Measure the working fluid:

[0017] The working fluid sequentially enters the oxygen sensor and the gas phase analyzer to complete the measurement of gas phase components.

[0018] Preferably, in step one: the high-pressure gas tank is filled with purge gas, which is nitrogen, argon or carbon dioxide, and the purge time is 5-10 minutes. After confirming the selection of the purge gas, a corresponding gas alarm is installed in the personnel operation area to detect the concentration of the purge gas in the operation area.

[0019] Preferably, in step two, the working fluid pressure at the sampling valve can be in the range of 8-20 MPa, the temperature range of 32-600℃, the working fluid pressure setting value is 0.2-0.5 MPa, and the working fluid temperature setting value is 23-25℃.

[0020] Preferably, in step two, if solid impurities are measured in the third particle filter, the filter membranes of the first and second particle filters need to be replaced before the measurement is repeated.

[0021] The present invention has the following beneficial effects:

[0022] 1. This device enables on-site monitoring of the working fluid quality in a supercritical carbon dioxide circulation system. The gas phase components can be measured online, and it has the advantages of fast response speed and comprehensive component testing.

[0023] 2. Solid impurities in this device can be collected in different forms and their microstructure and composition can be analyzed. This enables the monitoring of the corrosion of the circulating circuit steel by supercritical carbon dioxide, ensuring that the working fluid quality meets the quality requirements during boiler operation, guaranteeing the safe and economical operation of the boiler, and solving the problem that its quality system is a blank both domestically and internationally.

[0024] 3. The end pump of this device should prevent air backflow when the working fluid pressure is insufficient. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a device for measuring impurities in the working fluid of a supercritical carbon dioxide boiler.

[0026] In the diagram, 1-sampling working fluid flow, 2-sampling valve, 3-flow meter, 4-first particle filter, 5-de-temperature and pressure reducing device, 6-pressure gauge, 7-temperature sensor, 8-second particle filter, 9-third particle filter, 10-oxygen sensor, 11-gas phase analyzer, 12-analyzer and terminal pump, 13-purge valve, 14-purge gas. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0028] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] Specific implementation method one: Combining Figure 1This embodiment describes a device for measuring impurities in the working fluid of a supercritical carbon dioxide boiler. The device includes a sampling valve 2, a flow meter 3, a first particulate filter 4, a desuperheating and pressure reducing device 5, a pressure gauge 6, a temperature sensor 7, a second particulate filter 8, an analyzer, and a terminal pump 12. These components are connected sequentially. The terminal pump 12 prevents air backflow when the working fluid pressure is insufficient. This device can be installed on-site in a supercritical carbon dioxide circulation system and can measure the gaseous components of the working fluid online. It is of great significance for monitoring and controlling the quality of the working fluid and can realize the detection of working fluid quality in a closed-loop supercritical carbon dioxide circulation process. Monitoring of gas phase components (working fluid composition) ensures that the working fluid quality meets quality requirements during boiler operation, guaranteeing safe and economical boiler operation. The desuperheating and pressure-reducing device can utilize common circulating water or heat sinks, while pressure reduction can be achieved through expansion joints or other pressure-reducing components. Existing carbon dioxide working fluid measurements are primarily used for non-supercritical states. The analyzer includes an oxygen sensor 10 and a gas phase analyzer 11, connected in series. The oxygen sensor 10 has a range of 0-2000ppm or 0-5000ppm. Industrial-grade carbon dioxide may contain various impurities such as CO, SO2, NO2, NO, and CmHn. The gas phase analyzer 11 is a sensor capable of detecting these impurities, and its selection depends on the site conditions. Currently, the analyzer is an MRU. The VARIO PLUS-NEW instrument, while capable of simultaneously measuring oxygen and other gases, has an oxygen sensor with a measurement range in the percentile (%) range, meaning oxygen concentrations above 0.1% are detectable. The separate pre-mounted oxygen sensor 10 has a measurement range in the ppm range, allowing detection at oxygen concentrations as low as 1 ppm, thus compensating for the limitations of the MRU. In addition to direct measurement, N2 concentration can be calculated from the O2 content based on the N2 / O2 concentration ratio in the air. The N2 to O2 volume fraction ratio is 78.1 / 20.9, and the N2 concentration calculation method is: N2 mass concentration = 78.1 / 20.The H2O concentration is calculated using the condensate volume in the condensate collector of the gas phase analyzer 11 and the data recorded by the flow meter. The water content is calculated as: condensate volume / total working fluid flow rate = condensate volume / integral of the flow count over time. The system also includes a third filter 9, connected between the second filter 8 and the oxygen sensor 10. Under normal operating conditions, the third filter 9 should not accumulate solid impurities. If so, the filter membranes of the first and second filters 4 and 8 must be replaced, and the test repeated. Solid impurities are collected in the first and second filters 4 and 8. The first, second, and third filters 4 and 8 are removable, and the filter membranes can be removed. Solid impurities can be collected by morphology and their microstructure and composition can be analyzed. The amount of solid impurities deposited is obtained by weighing, and the solid impurity concentration (g / Nm³) is calculated based on the data recorded by the flow meter 3. 3 It also includes a purge valve 13, which and sampling valve 2 are connected in parallel to the first particulate filter 4; the inlet end of the purge valve 13 is connected to a high-pressure gas tank, and the inlet end of the sampling valve 2 is connected to a sampling pipe; the working fluid sampling port can be selected at several locations with stable pressure and temperature in the closed supercritical carbon dioxide cycle, and connected to the sampling valve 2 through the sampling pipe. The sampling working fluid flows through the sampling valve 2 and the flow meter 3, and then through the first particulate filter 4 to the depressurization and pressure reduction device 5 for depressurization and cooling. The outlet of the depressurization and pressure reduction device 5 is equipped with a pressure gauge 6 and a temperature sensor. The working fluid enters the analyzer after passing through the second filter 8 and the third filter 9. The flow rate of the working fluid is controlled by the flow meter 3 and the sampling valve 2. The working fluid enters the de-cooling and pressure reducing device 5. The pressure of the working fluid at the outlet of the de-cooling and pressure reducing device 5 is reduced from a high pressure state to 0.2-0.5MPa. The temperature of the working fluid at the outlet of the de-cooling and pressure reducing device 5 is close to the ambient temperature. The pressure gauge 6 and the temperature sensor 7 detect and record the working fluid. The working fluid that meets the pressure and temperature conditions enters the second filter 8 and the third filter 9 in sequence. Then, the working fluid without solid impurities enters the analyzer.

[0030] Specific Implementation Method Two: Combining Figure 1 This embodiment describes a method for measuring impurities in the working fluid of a supercritical carbon dioxide boiler. The method involves selecting sampling ports at several locations where the pressure and temperature of the closed-loop supercritical carbon dioxide circulation are stable, and connecting these sampling ports to a measuring device for measuring impurities in the working fluid of the supercritical carbon dioxide boiler. The method includes the following steps:

[0031] Step 1: Purge the measuring device:

[0032] Before measurement, purging is required. The high-pressure gas tank is filled with purging gas 14, which can be nitrogen, argon or carbon dioxide. Close the sampling valve 2 and the de-icing and pressure reducing device 5, open the purging valve 13, and purge for 5-10 minutes. When the oxygen concentration detected by the analyzer is zero, the purging is complete. After confirming the selection of the purging gas, equip the personnel operation area with a corresponding gas alarm to detect the concentration of the purging gas in the operation area and avoid personal safety hazards caused by high concentrations of purging gas.

[0033] Step 2: Transfer and purify the working fluid:

[0034] Close the purge valve 13, open the sampling valve 2 and the de-cooling and pressure reducing device 5. The sampling working fluid flow 1 (sampling working fluid) enters the first particle filter 4 after the flow meter 3 measures the flow rate. The solid impurities carried by the working fluid are removed. Then, the de-cooling and pressure reducing device 5 reduces the pressure and temperature of the working fluid to the set value. The working fluid then enters the second particle filter 8. During the separation process of the working fluid in the second particle filter 8, the working fluid produces metal precipitation crystals due to phase change. The working fluid then enters the third particle filter 9 to filter the residual solid particles, ensuring that no solid particles remain.

[0035] Step 3: Measure the working fluid:

[0036] The working fluid sequentially enters the oxygen sensor 10 and the gas phase analyzer 11 to complete the measurement of gas phase components; the O2 concentration measurement accuracy is ≤±3% (ppm level) or ±0.2% (% level), that is, the MRU analyzer has a % level oxygen sensor with an accuracy of ±0.2%; the pre-sensor is a ppm level oxygen sensor with an accuracy of ±3%; the CO and other gas concentration measurement accuracy is ±5ppm or ±5% of the reading. Currently, there are no such online measurement methods and devices in China, which can effectively improve the quality control and management capabilities of circulating working fluids on engineering sites.

[0037] Specific implementation method three: Combining Figure 1 This embodiment describes a method for measuring impurities in the working fluid of a supercritical carbon dioxide boiler. In step two, the working fluid pressure at sampling valve 2 can be in the range of 8-20 MPa, the temperature range of 32-600℃, the working fluid pressure setting value is 0.2-0.5 MPa, and the working fluid temperature setting value is 23-25℃.

[0038] Specific implementation method four: Combination Figure 1This embodiment describes a method for measuring impurities in the working fluid of a supercritical carbon dioxide boiler. In step two, if solid impurities are measured in the third particle filter 9, the filter membranes of the first particle filter 4 and the second particle filter 8 need to be replaced, and the measurement should be repeated from step one. Samples of the solid impurities on the filter membranes are taken and sent to the laboratory for examination of their microstructure and elemental composition. The solid impurities enriched in the first particle filter 4 are the original solid impurities carried by the working fluid, while the solid impurities enriched in the second filter 8 are impurities precipitated from the working fluid after depressurization. Both are measured and statistically analyzed separately. The measurement is performed step-by-step. Measuring the amount of solid impurities in the working fluid allows for the differentiation of the form in which metallic impurities exist within the fluid at the source. Solid impurities can be collected by morphology and subjected to microscopic morphology and composition analysis. The amount of solid impurity deposition is obtained by weighing, which is an important basis for analyzing the degree and causes of steel corrosion during supercritical carbon dioxide cycling. Specifically, the microscopic morphology and composition analysis methods are as follows: morphology and composition analysis are carried out using a scanning electron microscope combined with a matching energy dispersive spectroscopy (EDS) instrument, and lattice analysis is performed using an X-ray diffractometer. The results of these analyses can be compared with various corrosion tests, and the corrosion occurrence conditions and mechanisms can be further inferred through the composition and morphology.

[0039] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0040] This embodiment is merely an exemplary description of this patent and does not limit its scope of protection. Those skilled in the art can make partial changes to it, as long as they do not exceed the spirit and essence of this patent, they are all within the scope of protection of this patent.

Claims

1. A device for measuring impurities in a supercritical carbon dioxide boiler working fluid, characterized by: The device comprises a sampling valve (2), a flow meter (3), a first particle filter (4), a pressure and temperature reducing device (5), a pressure gauge (6), a temperature sensor (7), a second particle filter (8), an analyzer and an end pump (12), which are connected in sequence. The analyzer comprises an oxygen sensor (10) and a gas phase analyzer (11) arranged in series, and further comprises a third particle filter (9) connected between the second particle filter (8) and the oxygen sensor (10). The device further comprises a purge valve (13) connected in parallel with the sampling valve (2) to the first particle filter (4). The inlet end of the purge valve (13) is connected to a high-pressure gas tank, and the inlet end of the sampling valve (2) is connected to a sampling pipe.

2. A method of measuring a supercritical carbon dioxide boiler working fluid impurity, characterized by: The method uses the device for measuring impurities in supercritical carbon dioxide boiler working medium according to claim 1, and comprises the following steps: Step one: purging the measuring device Before measurement, the sampling valve (2) and the pressure and temperature reducing device (5) are closed, the purge valve (13) is opened, and the purging is completed when the oxygen concentration detected by the analyzer is zero. Step two: delivering the working medium and purifying the working medium The purge valve (13) is closed, the sampling valve (2) and the pressure and temperature reducing device (5) are opened, the sampling working medium passes through the flow meter (3) for flow measurement and then enters the first particle filter (4) to remove the solid impurities carried by the working medium, and then passes through the pressure and temperature reducing device (5) for pressure and temperature reduction, so that the pressure and temperature of the working medium are reduced to the set values, and then the working medium enters the second particle filter (8), which separates the working medium and causes metal to precipitate and crystallize due to phase change, and then the working medium enters the third particle filter (9) to filter the residual solid particles. Step three: measuring the working medium The working medium enters the oxygen sensor (10) and the gas phase analyzer (11) in sequence to complete the measurement of the gas phase components.

3. The method of claim 2, wherein: In step one, the high-pressure gas tank contains purge gas, which is nitrogen, argon or carbon dioxide, and the purging time is 5-10 minutes, and a corresponding gas alarm is provided in the personnel operation area to detect the concentration of the purge gas in the operation area.

4. The method of claim 3, wherein: In step two, the working medium pressure at the sampling valve (2) can be in the range of 8-20 MPa, and the temperature range is 32-600℃, the working medium pressure set value is 0.2-0.5 MPa, and the working medium temperature set value is 23-25℃.

5. The method of claim 4, wherein: In step two, if solid impurities are measured in the third particle filter (9), the filter membrane of the first particle filter (4) and the second particle filter (8) needs to be replaced before re-measurement.

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