Method and system for automatically and rapidly measuring trace aluminum in cold water in high-voltage direct-current converter valve

Abstract

The invention provides a method and a system for automatically and rapidly measuring trace aluminum in cold water in a high-voltage direct-current converter valve. The system comprises a masking reagent bottle, a chromogenic reagent bottle, a buffer reagent bottle, a current-carrying reagent bottle, a water sample bottle, a flow injection analyzer, a multi-channel combination module, a first reaction coil, a second reaction coil, a third reaction coil, a temperature control module and a light splitting detector, the flow injection analyzer comprises a pump A, a pump B, a sampling valve and a sampling ring; the multi-channel combination module is provided with channels A, B and C which are not communicated with one another, and the channels A, B and C are respectively provided with sampling ports a, b and c; the sampling valve is provided with channels f, g, h and i which are not communicated with one another, and the channels f, g, h and i are provided with sampling ports d and e respectively. According to the method and the system provided by the invention, the trace aluminum ions in the cold water in the high-voltage direct-current converter valve can be automatically, quickly, accurately and reliably measured, and the detection limit is 1.0 mu g / L.

Description

Technical Field

[0001] This invention relates to the detection of water vapor in power plants, specifically to an automatic and rapid detection method and system for trace iron ions in water vapor from power plants. Background Technology

[0002] Converter valves are core equipment in high-voltage direct current transmission systems, and their power electronic components generate a large amount of heat during operation. To prevent overheating, aging, and damage to the internal components, converter valves are equipped with a closed-loop circulating water cooling system for forced cooling. The internal cooling water in the valve cooling system is the heat transfer medium and comes into direct contact with the electrically charged components; therefore, the quality of the internal cooling water must meet the system's insulation and corrosion protection requirements.

[0003] The radiator material of the converter valve water cooling system is generally aluminum. The aluminum content in the valve cooling water is an important water quality monitoring parameter characterizing the corrosion of the aluminum radiator and the scaling of the equalizing electrode. The "DL / T 1716-2017 Guidelines for the Operation and Management of Cooling Water for High Voltage Direct Current Transmission Converter Valves" (hereinafter referred to as the "Guidelines") requires that the aluminum content in the valve cooling water be controlled to be less than 2.0 μg / L. Timely and accurate monitoring of aluminum ions, the scaling factor in the valve cooling water, is crucial for ensuring the normal operation of the internal cooling water deep desalination and purification equipment. This is essential for preventing scaling of the equalizing electrode and ensuring the safe and stable operation of the converter valve.

[0004] The guidelines require the use of the industry standard DL / T 502.9-2006, "Methods for Analysis of Water and Steam in Thermal Power Plants, Part 9: Determination of Aluminum Content (Catechol Violet Spectrophotometric Method)," to determine trace aluminum in valve cooling water. This method is rarely used due to its involvement of hazardous chemical reagents and complex operation. Aluminum reagent spectrophotometry, chromium cyanine R spectrophotometry, and graphite furnace atomic absorption spectrophotometry are more commonly used for testing trace aluminum in water. Chromium azurite S spectrophotometry is widely used in environmental monitoring of drinking water and source water. ICP-MS is less commonly used in power production due to the high cost of instrument use and maintenance.

[0005] Spectrophotometric methods for aluminum in water, such as the catechol spectrophotometric method, the aluminum reagent spectrophotometric method, and the chromocyanine R spectrophotometric method, generally suffer from problems such as deep colorimetric reagents and high reagent blank values, making it difficult to achieve a detection limit below 10 μg / L. Furthermore, trace aluminum in water is easily contaminated during the determination process, making manual laboratory spectrophotometric methods unsuitable for the accurate detection of trace aluminum in the cooling water of exchanger valves. Graphite furnace atomic absorption spectrometry and ICP-MS can determine trace aluminum in exchanger cooling water, but the equipment maintenance costs are high, and online implementation is not easily achieved.

[0006] In summary, there is still a need to research technical solutions that can achieve automatic, rapid, and accurate detection of trace aluminum in the cooling water inside high-voltage DC converter valves. Summary of the Invention

[0007] The purpose of this invention is to provide a technical solution that enables the automatic, rapid, and accurate detection of trace aluminum in the cooling water inside a high-voltage DC converter valve.

[0008] To achieve the above objectives, the present invention provides the following three technical solutions.

[0009] In a first aspect, the present invention provides an automatic rapid determination system for trace aluminum in cold water inside a high-voltage DC converter valve. The system includes a masking reagent bottle, a colorimetric reagent bottle, a buffer reagent bottle, a current-carrying reagent bottle, a water sample bottle, a flow injection analyzer, a multi-channel combination module, a first reaction coil, a second reaction coil, a third reaction coil, a temperature control module, and a spectrophotometer. The flow injection analyzer includes an A pump, a B pump, a sampling valve, and a sampling loop.

[0010] The multi-channel combination module is configured with non-interconnected channels A, B, and C, with sampling ports a, b, and c respectively for channels A, B, and C; the sampling valve is configured with non-interconnected channels f, g, h, and i, with sampling ports d and e respectively for channels f, g, h, and i.

[0011] The masking reagent bottle, colorimetric reagent bottle, and buffer reagent bottle are connected via connecting tubing to sampling ports a, b, and c of the multi-channel combination module via pump A (i.e., the masking reagent bottle is connected to sampling port a of channel A via connecting tubing, the colorimetric reagent bottle is connected to sampling port a of channel B via connecting tubing, and the buffer reagent bottle is connected to sampling port a of channel C via connecting tubing, the same as the previous method). The current-carrying reagent bottle and water sample bottle are connected via connecting tubing to sampling ports d and f of the sampling valve via pump B (i.e., the current-carrying reagent bottle is connected to sampling port d of channel i via connecting tubing, the same as the previous method, and the same as the previous method, ... The sampling port d of the sampling coil is connected to the sampling port b of channel A of the multi-channel combination module via a connecting pipe; the sampling ring is connected at both ends to the sampling ports e of channel h and f of the sampling valve in the sampling state, and at both ends to the sampling ports e of channel g and i of the sampling valve in the detection state; in the sampling state, the sampling port e of channel i of the sampling valve is connected to the sampling port e of channel g via a connecting pipe; the two ends of the first reaction coil are connected to the sampling ports c of channel A and b of channel B of the multi-channel combination module; the two ends of the second reaction coil are connected to the sampling ports c of channel B and b of channel C of the multi-channel combination module; the two ends of the third reaction coil are connected to the sampling port c of channel C of the multi-channel combination module and the inlet of the spectrophotometer via connecting pipes, and the temperature control module is used to control the temperature of the third reaction coil.

[0012] The automated rapid determination system for trace aluminum in the cooling water of a high-voltage DC converter valve provided by this invention combines flow injection analysis (FIA) with aluminum reagent spectrophotometry to automatically, rapidly, accurately, and reliably analyze and determine trace aluminum in the cooling water of the converter valve. The system achieves a detection limit below 5.0 μg / L and a relative standard deviation of less than 10%.

[0013] The automatic rapid determination system for trace aluminum in the cold water inside a high-voltage DC converter valve provided by this invention exhibits different connection methods in sampling and detection states. This is achieved by changing the connection method of the e-sampling ports of the f, g, h, and i channels of the sampling valve. In sampling state, the e-sampling port of the h channel and the e-sampling port of the f channel are connected through a sampling ring, and the e-sampling port of the i channel and the e-sampling port of the g channel are connected through a connecting pipe. In detection state, the e-sampling port of the g channel and the e-sampling port of the i channel are connected through a connecting pipe. This achieves the following: In sampling mode, water sample enters the sampling loop from the water sample bottle via connecting tubing and pump B. The carrier reagent, from the carrier reagent bottle via connecting tubing and pump B, and the masking reagent, from the masking reagent bottle via connecting tubing and pump A, are collected in the multi-channel combination module. After flowing through the first reaction coil, the sample is collected with the colorimetric reagent, from the colorimetric reagent bottle via connecting tubing and pump A, in the multi-channel combination module. After flowing through the second reaction coil, the sample is collected with the buffer reagent, from the buffer reagent bottle via connecting tubing and pump A, in the multi-channel combination module. In the detection state, the carrier reagent enters the sampling loop from the carrier reagent bottle via the connecting pipe and pump B, and then enters the multi-channel combination module via the connecting pipe. It is then combined with the masking reagent from the masking reagent bottle via the connecting pipe and pump A in the multi-channel combination module 11. After flowing through the first reaction coil, it is combined with the colorimetric reagent from the colorimetric reagent bottle via the connecting pipe and pump A in the multi-channel combination module. After flowing through the second reaction coil, it is combined with the buffer reagent from the buffer reagent bottle via the connecting pipe and pump A in the multi-channel combination module.

[0014] According to the system of the present invention, preferably, the system further includes a waste liquid bottle, and the drain port of the spectrophotometer is connected to the waste liquid bottle through a connecting pipe.

[0015] According to the system of the present invention, preferably, the system further includes a wastewater bottle, wherein the d sampling port of the h channel of the sampling valve is connected to the wastewater bottle via a connecting pipe and / or the e sampling port of the f channel of the sampling valve is connected to the wastewater bottle via a connecting pipe during the sampling state.

[0016] According to the system of the present invention, preferably, the a sampling port and b sampling port of each channel of the multi-channel combination module are located on both sides of the c sampling port.

[0017] According to the system of the present invention, preferably, the d sampling port of each channel of the sampling valve is located in the outer ring and the e sampling port is located in the inner ring.

[0018] According to the system of the present invention, preferably, the sampling valve is an eight-channel sampling valve; however, it may be used, but is not limited to, an eight-channel sampling valve conventional in the art.

[0019] In one specific embodiment, the sampling valve is provided with i-channel, f-channel, g-channel, h-channel, j-channel, k-channel, l-channel, and m-channel that are not interconnected. Each of the i-channel, f-channel, g-channel, h-channel, j-channel, k-channel, l-channel, and m-channel is provided with a d-sampling port and an e-sampling port. The d-sampling port is located on the outer ring, and the e-sampling port is located on the inner ring.

[0020] According to the system of the present invention, preferably, the inner diameter of the connecting pipe is 1.0 mm.

[0021] According to the system of the present invention, preferably, the length of the first reaction coil is 50-80 cm;

[0022] According to the system of the present invention, preferably, the inner diameter of the first reaction coil is 0.5 mm.

[0023] According to the system of the present invention, preferably, the length of the second reaction coil is 100-150 cm;

[0024] According to the system of the present invention, preferably, the inner diameter of the second reaction coil is 0.5 mm.

[0025] According to the system of the present invention, preferably, the length of the third reaction coil is 150-200 cm;

[0026] According to the system of the present invention, preferably, the inner diameter of the third reaction coil is 0.5 mm.

[0027] According to the system of the present invention, preferably, the sampling volume of the sampling loop is 500-1000 μL.

[0028] According to the system of the present invention, preferably, the system further includes a workstation electrically connected to the spectrophotometer.

[0029] The workstation is a conventional device in the field, which can be used to process and display the detection results of the spectrophotometer, and can even control the detector and other devices by inputting data through a human-machine interface.

[0030] According to the system of the present invention, preferably, the spectrophotometer can be, but is not limited to, an ultraviolet spectrophotometer commonly used in the art.

[0031] According to the system of the present invention, preferably, the optical path length of the flow cell of the spectrophotometer is 10-30 mm and the maximum absorption wavelength is 530 nm.

[0032] In the system according to the present invention, preferably, pump A is a peristaltic pump.

[0033] In the system according to the present invention, preferably, pump B is a peristaltic pump.

[0034] According to the system of the present invention, preferably, the inner diameter of the pump tube connected to the masking reagent bottle in pump A is 0.5-1.0 mm, the inner diameter of the pump tube connected to the colorimetric reagent bottle is 0.5-1.0 mm, and the inner diameter of the pump tube connected to the buffer reagent bottle is 0.5-1.0 mm.

[0035] According to the system of the present invention, preferably, pump A is capable of providing a rotational speed of 30-50 rpm and a flow rate of 1.0-2.0 mL / min.

[0036] According to the system of the present invention, preferably, the inner diameter of the pump tube connected to the reagent bottle in pump B is 1.0-1.5 mm, and the inner diameter of the pump tube connected to the water sample bottle is 1.0-1.5 mm.

[0037] According to the system of the present invention, preferably, pump B is capable of providing a rotational speed of 30-50 rpm and a flow rate of 1.0-2.0 mL / min for each flow path.

[0038] According to the system of the present invention, preferably, the temperature control module is capable of controlling the temperature of the third reaction coil to be 20-50°C.

[0039] According to the system of the present invention, preferably, the sampling loop may be, but is not limited to, a sampling loop commonly used in the art.

[0040] Secondly, the present invention provides an automated and rapid method for determining trace aluminum in the cooling water inside a high-voltage DC converter valve. This method utilizes the automated and rapid determination system for trace aluminum in the cooling water inside a high-voltage DC converter valve provided in the first aspect of the present invention, and employs a flow injection-spectrophotometric analysis method.

[0041] The masking agent used was an aqueous solution of ascorbic acid;

[0042] The colorimetric reagent used was an aluminum reagent solution;

[0043] The buffer solution used was an acetic acid-ammonium acetate buffer solution;

[0044] The flux carrier used was pure water;

[0045] The temperature of the third reaction coil is 20-50℃.

[0046] According to the method of the present invention, preferably, the method includes the following steps:

[0047] a. Sampling process: When the system is in sampling mode, the water sample enters the sampling loop via the sampling valve driven by pump B through the connecting pipe. At the same time, the carrier reagent driven by pump B is collected with the masking reagent driven by pump A in the multi-channel combination module through the sampling valve. After flowing through the first reaction coil, it is collected with the colorimetric reagent driven by pump A in the multi-channel combination module. After flowing through the second reaction coil, it is collected with the buffer reagent driven by pump A in the multi-channel combination module. After flowing through the third reaction coil and reacting at 20-50℃, it enters the spectrophotometer for detection. The detection signal is acquired and processed in real time by the workstation to obtain the baseline signal.

[0048] b. Detection process: After the sampling process is completed, the system is adjusted to the detection state. The carrier reagent pushes the water sample in the sampling loop to collect with the masking and reducing reagent driven by pump A in the multi-channel combination module. After flowing through the first reaction coil, it collects with the colorimetric reagent driven by pump A in the multi-channel combination module. After flowing through the second reaction coil, it collects with the buffer reagent driven by pump A in the multi-channel combination module. After flowing through the third reaction coil, it enters the spectrophotometer for detection. After flowing through the third reaction coil and reacting at 20-50℃, it enters the spectrophotometer for detection. After flowing through the third reaction coil, it enters the spectrophotometer for detection. The detection signal is acquired and processed in real time by the workstation to obtain the detection signal.

[0049] c. The workstation processes the baseline signal and the detection signal to obtain the aluminum content in the water sample.

[0050] According to the method of the present invention, preferably, the concentration of ascorbic acid in the ascorbic acid aqueous solution is 0.5-1.5% based on the total mass of the ascorbic acid aqueous solution being 100%.

[0051] According to the method of the present invention, preferably, the concentration of aluminum reagent in the aluminum reagent solution is 0.05-0.2% based on the total mass of the aluminum reagent solution being 100%.

[0052] According to the method of the present invention, preferably, the pH value of the acetic acid-ammonium acetate buffer solution is 4.0-4.5.

[0053] According to the method of the present invention, preferably, the resistivity of pure water is not less than 17 MΩ·cm.

[0054] According to the method of the present invention, preferably, the sampling volume is 500-1000µL.

[0055] According to the method of the present invention, preferably, the rotational speed of pump A is 30-40 rpm (e.g., 35 rpm).

[0056] According to the method of the present invention, preferably, the rotational speed of the B pump is 30-40 rpm (e.g., 35 rpm).

[0057] According to the method of the present invention, preferably, the flow rate of the carrier reagent is 1.0-2.0 mL / min (e.g., 1.8 mL / min).

[0058] According to the method of the present invention, preferably, the flow rate of the colorimetric reagent is 0.5-1.5 mL / min (e.g., 1.4 mL / min).

[0059] According to the method of the present invention, preferably, the flow rate of the buffer reagent is 0.5-1.5 mL / min (e.g., 1.4 mL / min).

[0060] According to the method of the present invention, preferably, the flow rate of the masking agent is 0.5-1.5 mL / min (e.g., 1.2 mL / min).

[0061] According to the method of the present invention, preferably, the aluminum content in the water sample is 1.0-2000 μg / L.

[0062] The technical solution provided by this invention realizes the automated instrumental analysis and detection of trace aluminum in the cooling water of high-voltage DC converter valves. It has a high level of automation, fast analysis speed, and is easy to implement online. It has high scientific research value and practical value. The detection limit is below 5.0 μg / L, and can usually reach 1.0 μg / L. Attached Figure Description

[0063] Figure 1 This is a specific embodiment (sampling state) of the automatic rapid determination system for trace aluminum in the cold water inside the high-voltage DC converter valve of the present invention.

[0064] Figure 2 This is a specific embodiment (detection state) of the automatic rapid determination system for trace aluminum in the cold water inside the high-voltage DC converter valve of the present invention.

[0065] Figure 3 This is a schematic diagram showing the specific connection relationship of the sampling valve in a specific embodiment (sampling state) of the automatic rapid determination system for trace aluminum in the cold water inside the high-voltage DC converter valve of the present invention.

[0066] Figure 4 This is a schematic diagram showing the specific connection relationship of the sampling valve in a specific embodiment (detection state) of the automatic rapid determination system for trace aluminum in the cold water inside the high-voltage DC converter valve of the present invention.

[0067] Figure 5 The standard working curve diagram for the automatic and rapid determination method of trace aluminum in the cold water inside the high-voltage DC converter valve provided by the present invention is shown in the figure.

[0068] Figure 6The automatic and rapid determination method for trace aluminum in the cooling water inside a high-voltage DC converter valve provided by this invention is shown in the detection signal spectrum when determining trace aluminum in the cooling water inside a high-voltage DC converter valve.

[0069] Main icon number explanation

[0070] Masking reagent bottle 1, colorimetric reagent bottle 2, buffer reagent bottle 3, flow carrier reagent bottle 4, water sample bottle 5, A pump 6, B pump 7, sampling valve 8, sampling loop 9, flow injection analyzer 10, multi-channel combination module 11, first reaction coil 12, second reaction coil 13, third reaction coil 14, temperature control module 15, spectrophotometer 16, workstation 17, waste liquid bottle 18, waste water bottle 19;

[0071] The sampling valve 8 includes sixteen sampling ports, namely the d sampling port d1 of channel h, the d sampling port d2 of channel i, the d sampling port d3 of channel j, the d sampling port d4 of channel k, the d sampling port d5 of channel l, the d sampling port d6 of channel m, the d sampling port d7 of channel f, and the d sampling port d8 of channel g.

[0072] The e-sampling ports e1 for channel h, e2 for channel i, e3 for channel j, e4 for channel k, e5 for channel l, e6 for channel m, e7 for channel f, and e8 for channel g. Detailed Implementation

[0073] The following detailed description of the implementation process and beneficial technical effects of the present invention, through specific embodiments and accompanying drawings, aims to help readers better understand the essence and features of the present invention, but is not intended to limit the scope of implementation of this invention.

[0074] Example 1

[0075] This embodiment provides an automatic and rapid determination system for trace aluminum in the cooling water inside a high-voltage DC converter valve.

[0076] The automatic rapid determination system for trace aluminum in the cold water inside the high-voltage DC converter valve provided in this embodiment includes: a masking reagent bottle 1, a colorimetric reagent bottle 2, a buffer reagent bottle 3, a current-carrying reagent bottle 4, a water sample bottle 5, a flow injection analyzer 10, a multi-channel combination module 11, a first reaction coil 12, a second reaction coil 13, a third reaction coil 14, a spectrophotometer 16, a workstation 17, a waste liquid bottle 18, and a waste water bottle 19; the flow injection analyzer 10 includes an A pump 6, a B pump 7, a sampling valve 8, and a sampling ring 9.

[0077] The multi-channel combination module 11 is provided with non-interconnected channels A, B and C, and channels A, B and C are respectively provided with sampling port a, sampling port b and sampling port c; the sampling ports a and b of each channel of the multi-channel combination module are located on both sides of the sampling port c.

[0078] The sampling valve 8 is an eight-channel sampling valve. The sampling valve 8 has non-interconnected channels i, f, g, h, j, k, l, and m arranged clockwise. Channels i, f, g, h, j, k, l, and m are respectively equipped with sampling ports d and e; sampling port d is located on the outer ring, and sampling port e is located on the inner ring. Specifically, the sampling valve 8 is equipped with the following sampling ports: h channel d1, i channel d2, j channel d3, k channel d4, l channel d5, m channel d6, f channel d7, g channel d8, h channel e1, i channel e2, j channel e3, k channel e4, l channel e5, m channel e6, f channel e7, and g channel e8.

[0079] When the system is in sampling state (e.g.) Figure 1 , Figure 3As shown, masking reagent bottle 1 is connected to sampling port a of channel A of multi-channel combination module 11 via connecting pipe A pump 6. Developing reagent bottle 2 is connected to sampling port a of channel B of multi-channel combination module 11 via connecting pipe A pump 6. Buffer reagent bottle 3 is connected to sampling port a of channel C of multi-channel combination module 11 via connecting pipe A pump 6. Current carrier reagent bottle 4 is connected to sampling port d2 of channel i of sampling valve 8 via connecting pipe B pump 7. Sampling port e2 of channel i of sampling valve 8 is connected to sampling port e8 of channel g via connecting pipe. Sampling port d8 of channel g of sampling valve 8 is connected to sampling port b of channel A of multi-channel combination module 11 via connecting pipe. Water sample bottle 5 is connected to sampling port d7 of channel f of sampling valve 8 via connecting pipe B pump 7. Sampling port e7 of channel f of sampling valve 8 is connected to sampling ring 9. The sampling port e1 of channel h is connected to the sampling port c of channel A of multi-channel combination module 11. The sampling port b of channel B of multi-channel combination module 11 is connected through the first reaction coil 12. The sampling port c of channel B of multi-channel combination module 11 is connected through the second reaction coil 13 to the sampling port b of channel C of multi-channel combination module 11. The sampling port c of channel C of multi-channel combination module 11 is connected to the inlet of third reaction coil 14 through a connecting pipe. The outlet of third reaction coil 14 is connected to spectrophotometer 16 through a connecting pipe. Waste liquid bottle 18 is connected to spectrophotometer 16 through a connecting pipe. Waste water bottle 19 is connected to sampling port d1 of channel h and sampling port e6 of channel m of sampling valve 8 through connecting pipes. Workstation 17 is electrically connected to spectrophotometer 16. Temperature control module 15 is used to control the temperature of third reaction coil 14.

[0080] Among them, when the system is in detection state (e.g.) Figure 2 , Figure 4As shown, masking reagent bottle 1 is connected to sampling port a of channel A of multi-channel combination module 11 via connecting tubing and pump A 6. Developing reagent bottle 2 is connected to sampling port a of channel B of multi-channel combination module 11 via connecting tubing and pump A 6. Buffer reagent bottle 3 is connected to sampling port a of channel C of multi-channel combination module 11 via connecting tubing and pump A 6. Current-carrying reagent bottle 4 is connected to sampling port d2 of channel i of sampling valve 8 via connecting tubing and pump B 7. Sampling port e8 of channel g of sampling valve 8 is connected to sampling port e2 of channel i via sampling ring 9. Sampling port e1 of channel h of sampling valve 8 is connected to sampling port e3 of channel j via connecting tubing. Sampling port d8 of channel g of sampling valve 8 is connected to sampling port b of channel A of multi-channel combination module 11 via connecting tubing. Water sample bottle 5 is connected to sampling valve 8 via connecting tubing and pump B 7. The sampling port d7 of channel f is connected; the sampling port c of channel A of multi-channel combination module 11 is connected to the sampling port b of channel B of multi-channel combination module 11 through the first reaction coil 12; the sampling port c of channel B of multi-channel combination module 11 is connected to the sampling port b of channel C of multi-channel combination module 11 through the second reaction coil 13; the sampling port c of channel C of multi-channel combination module 11 is connected to the inlet of third reaction coil 14 through a connecting pipe; the outlet of third reaction coil 14 is connected to spectrophotometer 16 through a connecting pipe; waste liquid bottle 18 is connected to spectrophotometer 16 through a connecting pipe; waste water bottle 19 is connected to the sampling port d1 of channel h and the sampling port e7 of channel f of sampling valve 8 through connecting pipes respectively; workstation 17 is electrically connected to spectrophotometer 16; and temperature control module 15 is used to control the temperature of third reaction coil 14.

[0081] The connecting pipes have an inner diameter of 1.0 mm; the first reaction coil 12 has a length of 80 cm and an inner diameter of 0.5 mm; the second reaction coil 13 has a length of 140 cm and an inner diameter of 0.5 mm; the third reaction coil 14 has a length of 200 cm and an inner diameter of 0.5 mm; the spectrophotometer 16 is an ultraviolet spectrophotometer with a flow cell optical path of 20 mm and a maximum absorption wavelength of 530 nm; pumps A 6 and B 7 are peristaltic pumps; the inner diameter of the pump tube connected to the masking reagent bottle 1 in pump A 6 is 0.68 mm, and the inner diameter of the pump tube connected to the colorimetric reagent bottle 2 is 0.68 mm. The inner diameter of the pump tube connected to the buffer reagent bottle 3 is 0.89 mm; the rotation speed of pump A 6 is 35 rpm; the inner diameter of the pump tube connected to the flow carrier reagent bottle 4 in pump B 7 is 1.0 mm, and the inner diameter of the pump tube connected to the water sample bottle 5 is 1.0 mm; the rotation speed of pump B 7 is 35 rpm; the flow rates of the flow paths connected to the masking reagent bottle 1, the colorimetric reagent bottle 2, and the buffer reagent bottle 3 in pump A 6 are 1.2 mL / min, 1.4 mL / min, and 1.4 mL / min, respectively; the flow rate of the flow path connected to the flow carrier reagent bottle 4 in pump B 7 is 1.8 mL / min.

[0082] The system can be programmed to set pump speed, flow rate, etc. The sample "sampling" and "injection" are automatically switched according to the set program, realizing the automated control of the entire connection pipeline system.

[0083] Example 2

[0084] This embodiment provides an automatic and rapid method for determining trace aluminum in the cooling water inside a high-voltage DC converter valve.

[0085] The automatic and rapid determination method for trace aluminum in the cooling water inside the high-voltage DC converter valve provided in this embodiment uses the automatic and rapid determination system for trace aluminum in the cooling water inside the high-voltage DC converter valve provided in Embodiment 1. The method includes the following steps:

[0086] Sampling process: The automatic rapid determination system for trace aluminum in cold water inside the high-voltage DC converter valve is in sampling mode. The water sample enters the sampling loop via the sampling valve driven by pump B through the connecting pipe. At the same time, the carrier reagent driven by pump B is collected with the masking reagent driven by pump A in the multi-channel combination module through the sampling valve. After flowing through the first reaction coil, it is collected with the colorimetric reagent driven by pump A in the multi-channel combination module. After flowing through the second reaction coil, it is collected with the buffer reagent driven by pump A in the multi-channel combination module. After flowing through the third reaction coil and reacting at 40°C, it enters the spectrophotometer for detection. The detection signal is acquired and processed in real time by the workstation to obtain the baseline signal.

[0087] Detection process: After the sampling process is completed, the automatic rapid determination system for trace aluminum in the cold water inside the high-voltage DC converter valve is adjusted to the detection state. The current-carrying reagent pushes the water sample in the sampling loop to collect with the masking and reducing reagent driven by pump A in the multi-channel combination module. After flowing through the first reaction coil, it collects with the colorimetric reagent driven by pump A in the multi-channel combination module. After flowing through the second reaction coil, it collects with the buffer reagent driven by pump A in the multi-channel combination module. After flowing through the third reaction coil and reacting at 40°C, it enters the spectrophotometer for detection. The detection signal is acquired and processed in real time by the workstation to obtain the detection signal.

[0088] The workstation processes the baseline and detection signals to obtain the aluminum content in the water sample.

[0089] The masking agent used is an aqueous solution of ascorbic acid; the concentration of ascorbic acid in the aqueous solution is 1.0%, based on the total mass of the aqueous solution of ascorbic acid being 100%.

[0090] The colorimetric reagent used is an aluminum reagent solution; with the total mass of the aluminum reagent solution being 100%, the concentration of aluminum reagent in the aluminum reagent solution is 0.1%.

[0091] The buffering reagent used was an acetic acid-ammonium acetate buffer solution; the pH value of the acetic acid-ammonium acetate buffer solution was 4.0.

[0092] The current-carrying reagent used was pure water; the resistivity of pure water is 18.2 MΩ·cm.

[0093] The sampling volume was 750µL.

[0094] The pump A operates at 35 rpm, the colorimetric reagent flows at 1.2 mL / min, the buffer reagent flows at 1.4 mL / min, and the reducing reagent flows at 1.4 mL / min.

[0095] Pump B operates at a speed of 35 rpm and carries a reagent flow rate of 1.8 mL / min.

[0096] Test case

[0097] 1. Determination of the standard working curve

[0098] Aluminum ion standard solutions with concentrations of 2.0 μg / L, 5.0 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, 100 μg / L, and 300 μg / L were prepared. Using the system provided in Example 1 of this invention and the method provided in Example 2 of this invention, the corresponding detection values ​​(peak height absorbance values) for each aluminum ion standard solution were determined. The measurement results are shown in [Figure 2]. Figure 5 and Figure 6 As shown.

[0099] The standard working curve obtained by measurement is as follows: Figure 5 As shown. From Figure 5 As can be seen, its working curve is y = 0.1014x - 0.0345, r = 0.9997; within the range of 0-300 μg / L, this method exhibits good linearity, with a linear coefficient greater than 0.999; the determination range of this method is 0-2000 μg / L.

[0100] 2. Reproducibility determination

[0101] The reproducibility of this method was determined by performing parallel determinations of 5.0 μg / L and 50 μg / L aluminum ion standard solutions at least seven times each, and the results are shown in Table 1. The relative standard deviations of the 5.0 μg / L and 50 μg / L aluminum ion standard solutions were 6.47% and 4.48%, respectively, which are less than 10%, indicating that the method has good reproducibility.

[0102] Table 1

[0103]

[0104] 3. Determination of the lower limit of detection

[0105] In this method, the detection limit refers to the lower limit of the peak height of the analyte that can be clearly distinguished on the workstation signal recording graph. It is generally considered that the minimum peak height of the response signal that can be clearly distinguished should be three times the baseline noise, corresponding to the concentration of the analyte. The detection limit is calculated using the following formula:

[0106]

[0107] In the formula: S is the blank standard deviation; k is the slope of the standard curve equation.

[0108] The detection limit of this method is 1.16 μg / L.

[0109] Application examples

[0110] The method provided in Embodiment 2 of this invention was used to determine trace aluminum ions in the cold water of multiple high-voltage DC converter valves, and the determination results were compared with the detection results obtained by ICP-MS. The experimental data are shown in Table 2.

[0111] Table 2

[0112]

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

Claims

1. An automatic and rapid determination system for trace aluminum in the cooling water inside a high-voltage DC converter valve, wherein, The system includes a masking reagent bottle, a colorimetric reagent bottle, a buffer reagent bottle, a current-carrying reagent bottle, a water sample bottle, a flow injection analyzer, a multi-channel combination module, a first reaction coil, a second reaction coil, a third reaction coil, a temperature control module, and a spectrophotometer. The flow injection analyzer includes an A pump, a B pump, a sampling valve, and a sampling loop. The multi-channel combination module has three independent channels, A, B, and C, with sampling ports a, b, and c respectively. The sampling valve has three independent channels, f, g, h, and i, with sampling ports d and e respectively. The masking reagent bottle, colorimetric reagent bottle, and buffer reagent bottle are connected via connecting tubing to sampling ports a of channel A, a of channel B, and a of channel C of the multi-channel combination module, respectively, through pump A. The carrier reagent bottle and water sample bottle are connected via connecting tubing to sampling ports d of channel i and d of channel f of the sampling valve, respectively, through pump B. Sampling port d of channel g of the sampling valve is connected via connecting tubing to sampling port b of channel A of the multi-channel combination module. In sampling mode, the sampling loop is connected at both ends to sampling ports e of channel h and e of channel f of the sampling valve, respectively; in detection mode, it is connected at both ends to the sampling valve's... The e-sampling port of channel g and the e-sampling port of channel i are connected; in the sampling state, the e-sampling port of channel i of the sampling valve is connected to the e-sampling port of channel g through a connecting pipe; the two ends of the first reaction coil are connected to the c-sampling port of channel A and the b-sampling port of channel B of the multi-channel combination module, respectively; the two ends of the second reaction coil are connected to the c-sampling port of channel B and the b-sampling port of channel C of the multi-channel combination module, respectively; the two ends of the third reaction coil are connected to the c-sampling port of channel C of the multi-channel combination module and the sample inlet of the spectrophotometer through connecting pipes, respectively. The temperature control module is used to control the temperature of the third reaction coil.

2. The system according to claim 1, wherein, The system also includes a waste liquid bottle, and the drain port of the spectrophotometer is connected to the waste liquid bottle via a connecting pipe; The system also includes a wastewater bottle, with the sampling port d of the sampling valve's h channel connected to the wastewater bottle via a connecting pipe and / or the sampling port e of the sampling valve's f channel connected to the wastewater bottle via a connecting pipe during sampling.

3. The system according to claim 1, wherein, In the multi-channel combination module, the sampling ports a and b of each channel are located on both sides of the sampling port c. The sampling port d of each channel of the sampling valve is located on the outer ring, and the sampling port e is located on the inner ring.

4. The system according to any one of claims 1-3, wherein, The inner diameter of the connecting pipe is 1.0 mm; The length of the first reaction coil is 50-80cm; The inner diameter of the first reaction coil is 0.5 mm; The length of the second reaction coil is 100-150cm; The inner diameter of the second reaction coil is 0.5 mm; The length of the third reaction coil is 150-200 cm; The inner diameter of the third reaction coil is 0.5 mm; The temperature control module can control the temperature of the third reaction coil to 20-50℃; The sampling volume of the sampling loop is 500-1000 μL; The optical path length of the flow cell of the spectrophotometer is 10-30 mm, and the maximum absorption wavelength is 530 nm.

5. The system according to any one of claims 1-3, wherein, The inner diameter of the pump tube connected to the masking reagent bottle in pump A is 0.5-1.0 mm, the inner diameter of the pump tube connected to the colorimetric reagent bottle is 0.5-1.0 mm, and the inner diameter of the pump tube connected to the buffer reagent bottle is 0.5-1.0 mm. The A pump can provide a rotational speed of 30-50 rpm and a flow rate of 1.0-2.0 mL / min.

6. The system according to any one of claims 1-3, wherein, The inner diameter of the pump tube connected to the reagent bottle in pump B is 1.0 mm, and the inner diameter of the pump tube connected to the water sample bottle is 1.0 mm. The B pump can provide a rotational speed of 30-50 rpm and a flow rate of 1.0-2.0 mL / min.

7. An automated and rapid method for determining trace aluminum in the cooling water inside a high-voltage direct current converter valve, wherein the method is performed using the automated and rapid determination system for trace aluminum in the cooling water inside a high-voltage direct current converter valve as described in any one of claims 1-6, and the method employs a flow injection-spectrophotometric analysis method; wherein, The masking agent used was an aqueous solution of ascorbic acid; The colorimetric reagent used was an aluminum reagent solution; The buffer solution used was an acetic acid-ammonium acetate buffer solution; The flux carrier used was pure water; The temperature of the third reaction coil is 20-50℃.

8. The method according to claim 7, wherein, The method includes the following steps: a. Sampling process: When the system is in sampling mode, the water sample enters the sampling loop via the sampling valve driven by pump B through the connecting pipe. At the same time, the carrier reagent driven by pump B is collected with the masking reagent driven by pump A in the multi-channel combination module through the sampling valve. After flowing through the first reaction coil, it is collected with the colorimetric reagent driven by pump A in the multi-channel combination module. After flowing through the second reaction coil, it is collected with the buffer reagent driven by pump A in the multi-channel combination module. After flowing through the third reaction coil and reacting at 20-50℃, it enters the spectrophotometer for detection. The detection signal is acquired and processed in real time by the workstation to obtain the baseline signal. b. Detection process: After the sampling process is completed, the system is adjusted to the detection state. The carrier reagent pushes the water sample in the sampling loop to collect with the masking and reducing reagent driven by pump A in the multi-channel combination module. After flowing through the first reaction coil, it collects with the colorimetric reagent driven by pump A in the multi-channel combination module. After flowing through the second reaction coil, it collects with the buffer reagent driven by pump A in the multi-channel combination module. After flowing through the third reaction coil, it enters the spectrophotometer for detection. After flowing through the third reaction coil and reacting at 20-50℃, it enters the spectrophotometer for detection. After flowing through the third reaction coil, it enters the spectrophotometer for detection. The detection signal is acquired and processed in real time by the workstation to obtain the detection signal. c. The workstation processes the baseline signal and the detection signal to obtain the aluminum content in the water sample.

9. The method according to claim 7 or 8, wherein, Based on the total mass of the ascorbic acid aqueous solution being 100%, the concentration of ascorbic acid in the ascorbic acid aqueous solution is 0.5-1.5%; Based on the total mass of the aluminum reagent solution being 100%, the concentration of aluminum reagent in the aluminum reagent solution is 0.05-0.2%; The pH of the acetic acid-ammonium acetate buffer solution is 4.0-4.5; The resistivity of pure water is not less than 17 MΩ·cm.

10. The method according to claim 7 or 8, wherein, The sampling volume is 500-1000µL; The rotational speed of pump A is 30-40 rpm; The speed of pump B is 30-40 rpm; The flow rate of the carrier reagent is 1.0-2.0 mL / min; The flow rate of the colorimetric reagent is 0.5-1.0 mL / min; The flow rate of the buffer reagent is 0.5-1.5 mL / min; The flow rate of the masking reagent is 0.5-1.5 mL / min; The aluminum content in the water samples ranged from 1.0 to 2000 μg / L.

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