A multi-path water sample dual-mode sampling method and system

Abstract

This invention provides a multi-channel water sample dual-mode sampling method and system, belonging to the field of online water quality monitoring and water sample collection control technology. Addressing the problems of sample supply fluctuations due to differences in water sample flow rates, insufficient supply of low-flow water samples, and cross-contamination during multi-channel switching, this invention connects to the target water channel according to sampling instructions and detects the inlet flow rate. When the inlet flow rate meets the conditions for direct sampling, samples are supplied to the downstream water quality monitoring device through a bypass sampling path; when it does not meet the conditions, the water sample is introduced into a storage tank, and after the storage flow rate meets the conditions for metering sampling, samples are supplied through a metering pump. After sampling is completed, residual water sample is discharged and the target water channel is reset. The system includes multiple water sample collection channels, a flow detection component, a bypass sampling path, a storage tank, a metering pump, a sewage discharge path, and a control unit. This invention can improve the stability of multi-channel water sample supply, meet the single-test requirements of low-flow water samples, and reduce cross-contamination caused by water sample switching.

Description

Technical Field

[0001] This invention belongs to the field of online water quality monitoring and water sample collection control technology, specifically relating to a multi-channel water sample dual-mode sampling method and system. Background Technology

[0002] In the power, chemical, metallurgical, and industrial water treatment sectors, to promptly monitor the water quality of production water, circulating water, effluent, and process water, it is typically necessary to draw water samples from multiple sampling points and transport them to conductivity meters, pH meters, particle counters, and other water quality monitoring instruments. To reduce redundant configuration of monitoring instruments and improve detection efficiency, multiple water sampling pipelines are usually connected to one or more downstream water quality monitoring devices via valve switching mechanisms, allowing different water samples to be selected for testing sequentially according to the testing task.

[0003] Water sample pressure, flow rate, pipeline length, and pipeline resistance vary at different sampling points. When direct pipeline sampling is used, flow fluctuations and pressure changes in the main water sample pipe are easily transmitted to downstream monitoring instruments, causing changes in the water sample flow velocity in the instrument's flow cell and impacting the detection electrodes, particle counting components, and other detection components, thus affecting the stability of the detection data. For water samples with low flow rates, the injection flow rate often cannot meet the sampling requirements of downstream instruments within the duration required for a single detection task; if a pumping method is used directly, insufficient water sample supply can easily lead to problems such as cavitation, sample supply interruption, or unstable output.

[0004] Some existing sampling devices are equipped with buffer containers or transfer pumps to reduce the impact of upstream flow rate changes on downstream detection. However, such devices often lack clear selection criteria for direct bypass sampling and pumped sampling after accumulating flow. Some devices switch water paths based solely on a single flow rate detection value, without considering the flow rate and its fluctuations over a certain detection period, making frequent switching likely when the flow rate approaches the threshold. Other devices, while equipped with accumulator structures, do not determine the required accumulator flow rate for a single detection task based on the target sampling flow rate, sampling duration, and pipeline replacement volume. Consequently, they cannot guarantee a continuous supply of sufficient water sample after accumulating flow, and lack control measures to prevent the transfer pump from starting when accumulating flow is insufficient.

[0005] Furthermore, even if the front-end sampling water paths of multiple water samples are independent of each other, their outlets may still be connected to the same distribution main or back-end monitoring device. When switching water samples, the water sample from the previous path can easily remain in the outlet pipe, distribution main, and instrument flow section, mixing with the water sample from the next path, causing cross-contamination and delayed detection response. Existing solutions lack clear definitions regarding the discharge sequence of residual water samples, the volume of water replaced in the pipeline, the conditions for completion of flushing, and the interlocking relationships of multiple valves. They also lack a complete control process for stopping sample supply, isolating the target water path, and restoring standby status when the sample inlet flow is consistently insufficient, the flow storage is incomplete, the metering pump is malfunctioning, the back-end monitoring device is not ready, or the sewage discharge is incomplete.

[0006] Therefore, it is necessary to improve the flow rate determination of multiple water samples, the selection of sample supply channels, the accumulation of low-flow water samples, the metering and transportation, and the sewage discharge and reset process after sample supply. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a method and system for multi-channel water sample dual-mode sampling.

[0008] This invention provides a method for dual-mode multi-channel water sample supply, comprising the following steps: S1: Receive a sampling instruction, determine the target water sample from multiple candidate water samples according to the sampling instruction, and cause the target water sample to enter the target water channel corresponding to it; S2: Detect the injection flow rate of the target water channel to obtain the injection flow rate status; S3: Determine whether the target water path meets the direct sampling conditions based on the sampling flow rate. If it does, close the storage path and open the bypass sampling path, so that the target water sample enters the downstream water quality monitoring device through the bypass sampling path. If it does not meet the conditions, close the bypass sampling path and open the storage path, so that the target water sample enters the storage tank. After the storage flow rate in the storage tank meets the metering sampling conditions, control the metering pump to transport the target water sample in the storage tank to the downstream water quality monitoring device according to the target sampling flow rate. S4: After completing the sample supply for a single detection task, stop supplying samples to the backend water quality monitoring device, discharge the residual water sample in the target water path into the sewage discharge path, and close the target water path after the sewage discharge is completed, so that the target water path returns to standby state.

[0009] Furthermore, the injection flow rate status includes the average injection flow rate and the flow rate fluctuation level. The average injection flow rate and the flow rate fluctuation level are determined based on the injection flow rate continuously detected within a set detection time window. The flow rate fluctuation level is obtained by dividing the difference between the maximum and minimum injection flow rates within the set detection time window by the average injection flow rate. The direct sample supply condition is that the average injection flow rate is within the direct sample supply flow rate range, and the flow rate fluctuation level does not exceed the allowable fluctuation threshold.

[0010] Specifically, during the bypass direct sampling period, if the sampling flow rate does not meet the direct sampling conditions for a set duration, the sampling to the downstream water quality monitoring device is stopped, the bypass sampling passage is closed, and the storage passage is opened to allow the target water sample to enter the storage tank; after the storage flow rate meets the metering sampling conditions, the sampling to the downstream water quality monitoring device is resumed through the metering pump, and the storage metering sampling state is maintained until the single detection task is completed.

[0011] Specifically, the metering and sampling conditions include that the storage flow rate is not lower than the target storage flow rate; the water sample volume required for a single testing task is equal to the product of the target sampling flow rate and the sampling duration plus the pipeline replacement water volume, and the target storage flow rate is the sum of the water sample volume required for a single testing task and the remaining water volume.

[0012] Preferably, the storage flow rate is determined by accumulating the sample inflow rate detected during the storage period; the metering pump is kept stopped before the storage flow rate reaches the target storage flow rate, and the water supply to the storage tank is stopped and the metering pump is started after the storage flow rate reaches the target storage flow rate; the cumulative sample supply is determined according to the target sample supply flow rate and the running time of the metering pump, and the metering pump is stopped after the cumulative sample supply reaches the water sample volume required for the single detection task.

[0013] Specifically, the process of discharging the residual water sample in the target waterway into the sewage discharge passage includes discharging the residual water sample in the storage tank through the waterway sewage branch and discharging the residual water sample in the outlet passage of the target waterway through the shared sewage branch; when switching to the next target waterway, after closing the target waterway, the next target water sample flows through the outlet passage of the next target waterway through the shared pipe section and is discharged by the shared sewage branch; after the cumulative replacement water volume reaches the replacement water volume set according to the volume of the shared pipe section, the next target water sample is sent to the back-end water quality monitoring device.

[0014] Furthermore, a sequential interlock is implemented for multiple water sampling water paths, so that the next target water path is connected to the common sewage branch only after the target water path is closed, and is connected to the back-end water quality monitoring device after the residual water sample replacement is completed; during the sampling period, only one of the water sampling water paths is allowed to connect to the back-end water quality monitoring device.

[0015] Another aspect of the present invention provides a multi-channel water sample dual-mode sampling system, including a control unit, a sewage discharge passage and multiple water sample sampling channels, each of which is connected to a water sample main pipe. Each water sampling path includes an inlet path, a flow detection component, a bypass sampling path, a storage path, a metering sampling path, and an outlet path. The inlet path is equipped with a water path selection valve, and the flow detection component is located in the inlet path. The outlet of the flow detection component is connected to the inlet of the bypass sampling path and the inlet of the storage path, respectively. The bypass sampling path is equipped with a bypass valve, and the outlet of the bypass sampling path is connected to the outlet path. The storage path is sequentially equipped with a storage inlet valve and a storage tank. The outlet of the storage tank is connected to the outlet path via a metering sampling path equipped with a metering pump. The outlet path is used to connect to a downstream water quality monitoring device. The sewage discharge path includes water path sewage branches connected to each of the storage tanks and a common sewage branch connected to a common pipe section downstream of each of the outlet paths. Each water path sewage branch and the common sewage branch are equipped with a sewage valve. The control unit is connected to the water path selection valve, the flow detection component, the bypass valve, the storage inlet valve, the metering pump, and each of the drain valves. It controls the opening of the water path selection valve of the target water path in the multiple water sampling paths according to the sampling command. Based on whether the inlet flow rate of the target water path meets the direct sampling conditions, it controls the closing of the storage inlet valve and the opening of the bypass valve of the target water path when the direct sampling conditions are met, and controls the closing of the bypass valve and the opening of the storage inlet valve of the target water path when the direct sampling conditions are not met. After the storage flow rate in the storage tank of the target water path meets the metering sampling conditions, it controls the metering pump of the target water path to supply samples according to the target sampling flow rate. Finally, it stops the sampling after the sampling is completed and controls the pump to supply samples.

[0016] Furthermore, the storage tank includes a tank body and an inlet port, an outlet port, an overflow port, and a top vent provided in the tank body. The inlet port is connected to the storage inlet valve via a quick-release connection structure, the outlet port is connected to the inlet of the metering pump via a quick-release connection structure, the overflow port is connected to a vertically extending overflow pipe, and the outlet of the overflow pipe is located at a height corresponding to the highest storage position of the storage tank, and is connected to the sewage branch of the waterway in an open drainage manner.

[0017] Specifically, the outlets of the bypass sampling passage and the metering sampling passage are both connected to the inlet of the outlet passage. Check valves and outlet isolation valves are sequentially installed in the outlet passage along the sampling direction. The common pipe section is connected to the downstream water quality monitoring device via an instrument inlet branch equipped with an instrument inlet valve. The control unit is connected to the water path selection valve, the outlet isolation valve, and the instrument inlet valve, and implements interlock control for each of the water sampling water paths so that when the target water path is connected to the downstream water quality monitoring device, the other water sampling water paths remain isolated, and the next target water sample enters the downstream water quality monitoring device after the replacement of the common pipe section.

[0018] The beneficial effects of this invention are as follows: This invention selects between direct bypass sampling or metered sampling after storage based on the target water sample's inlet flow rate. When the inlet flow rate is within the direct sampling flow rate range and the flow fluctuation does not exceed the allowable fluctuation threshold, direct sampling is performed through the bypass sampling path. When the inlet flow rate is insufficient or the flow fluctuation exceeds the allowable fluctuation threshold, the target water sample is buffered in a storage tank and then delivered by a metering pump according to the target sampling flow rate. Through target storage flow rate control, sampling status monitoring, residual water sample discharge, shared pipe section replacement, and multi-sample interlocking, the degree to which front-end flow and pressure changes are transmitted to the back-end water quality monitoring device can be reduced, and water sample backflow, cross-contamination, and other contamination can be minimized. This creates a complete control closed loop for sampling commands, target water path access, sampling mode selection, sampling, sewage discharge, and reset. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the steps of a multi-channel water sample dual-mode sampling method according to a specific embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a multi-channel water sample dual-mode sampling system according to a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a storage tank for a multi-channel water sample dual-mode sampling system according to a specific embodiment of the present invention; Figure 4 A top view of the storage tank of a multi-channel water sample dual-mode sampling system according to a specific embodiment of the present invention; Figure 5 This is a schematic diagram showing the connection between a multi-channel water sample dual-mode sampling system and a back-end water quality monitoring device according to a specific embodiment of the present invention.

[0020] The components include: 1. Cabinet; 2. Main water sample pipe; 3. Equipment switching valve; 4. Sample inlet solenoid valve; 5. Flow meter; 6. Bypass solenoid valve group; 7. Buffer storage tank; 8. Metering pump; 9. Check valve; 10. Sample outlet pipeline; 11. Sewage discharge pipeline; 12. Front-end valve; 13. Top vent; 14. Tank body; 15. Sample inlet interface; 16. Sealing ring; 17. Liquid outlet interface; and 18. Overflow interface. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown in the figure, a multi-channel water sample dual-mode sampling method provided by a specific embodiment of the present invention includes the following steps: S1: Receive a sampling instruction, determine the target water sample from multiple candidate water samples according to the sampling instruction, and cause the target water sample to enter the target water channel corresponding to it; S2: Detect the injection flow rate of the target water channel to obtain the injection flow rate status; S3: Determine whether the target water path meets the direct sampling conditions based on the sampling flow rate. If it does, close the storage path and open the bypass sampling path, so that the target water sample enters the downstream water quality monitoring device through the bypass sampling path. If it does not meet the conditions, close the bypass sampling path and open the storage path, so that the target water sample enters the storage tank. After the storage flow rate in the storage tank meets the metering sampling conditions, control the metering pump to transport the target water sample in the storage tank to the downstream water quality monitoring device according to the target sampling flow rate. S4: After completing the sample supply for a single detection task, stop supplying samples to the backend water quality monitoring device, discharge the residual water sample in the target water path into the sewage discharge path, and close the target water path after the sewage discharge is completed, so that the target water path returns to standby state.

[0023] In one embodiment, the sampling command is issued by a host computer, a DCS system, or a backend water quality monitoring device, and the sampling command includes at least the identification information of the target water sample. The control unit determines the target water path based on the identification information, and after confirming that other water sample sampling paths are not connected to the backend water quality monitoring device, controls the connection of the target water path, so that the target water sample enters the target water path from the corresponding water sample header.

[0024] Specifically, after the target water circuit is connected, the control unit closes the inlet valves of each instrument and opens the bypass valve, outlet isolation valve, and common drain valve of the target water circuit. This allows the target water sample to pass sequentially through the flow detection component, bypass sampling passage, outlet passage, and common pipe section, and then be discharged through the common drain branch. During this process, the target water sample does not enter the downstream water quality monitoring instruments. When the target water sample reaches the flow detection position and the flow detection signal is valid, the control unit begins the inlet flow detection within the set detection time window.

[0025] Furthermore, the bypass direct sampling relies on the target water sample's own inlet flow rate to meet the direct sampling conditions, and the bypass sampling path does not actively adjust the sampling flow rate through a metering pump. In contrast, the reservoir-metered sampling first utilizes a reservoir to temporarily store the target water sample and buffer changes in the upstream water sample's flow rate, and then the metering pump delivers the target water sample to the downstream water quality monitoring device according to the target sampling flow rate. The reservoir is used to support a single detection task of limited duration and is not used for long-term compensation of the difference between the target sampling flow rate and the inlet flow rate.

[0026] Based on the above basic implementation method, the injection flow rate status includes the average injection flow rate and the flow rate fluctuation degree. The average injection flow rate and the flow rate fluctuation degree are determined based on the injection flow rate continuously detected within a set detection time window. The flow rate fluctuation degree is obtained by dividing the difference between the maximum and minimum injection flow rates within the set detection time window by the average injection flow rate. The direct sample supply condition is that the average injection flow rate is within the direct sample supply flow rate range, and the flow rate fluctuation degree does not exceed the allowable fluctuation threshold.

[0027] Furthermore, within the set detection time window, multiple injection flow rates are obtained according to a set sampling interval, and the average injection flow rate is determined according to the following formula:

[0028] In the formula, This represents the average injection flow rate. Indicates the first One injection flow rate value, This indicates the number of injection flow rates obtained within the set detection time window.

[0029] The degree of flow fluctuation is determined according to the following formula:

[0030] In the formula, Indicates the degree of traffic fluctuation. and These represent the maximum and minimum injection flow rates within the set detection time window, respectively. When the average injection flow rate is zero, below the effective measurement lower limit of the flow detection component, or the flow detection signal is invalid, the control unit does not perform the division calculation of the flow fluctuation degree and determines that the target water path does not meet the direct sampling conditions.

[0031] Furthermore, the direct sampling flow rate range is determined based on the allowable inlet flow rate range of the downstream water quality monitoring device. The lower limit of the direct sampling flow rate range is not lower than the minimum inlet flow rate required for the downstream water quality monitoring device to complete normal testing, and the upper limit of the direct sampling flow rate range is not higher than the maximum allowable inlet flow rate of the downstream water quality monitoring device. The allowable fluctuation threshold is determined based on the allowable variation range of the inlet flow rate of the downstream water quality monitoring device. If the average inlet flow rate is lower than the lower limit of the direct sampling flow rate range, exceeds the upper limit of the direct sampling flow rate range, or the flow rate fluctuation exceeds the allowable fluctuation threshold, the target waterway is determined not to meet the direct sampling conditions.

[0032] In one specific implementation, during the bypass direct sampling period, if the sampling flow rate does not meet the direct sampling conditions for a set duration, the sampling to the downstream water quality monitoring device is stopped, the bypass sampling passage is closed, and the storage passage is opened to allow the target water sample to enter the storage tank; after the storage flow rate meets the metering sampling conditions, the sampling to the downstream water quality monitoring device is resumed through the metering pump, and the storage metering sampling state is maintained until the single detection task is completed.

[0033] In this embodiment, when the influent flow rate during the bypass direct sampling period continuously fails to meet the direct sampling conditions, the control unit first closes the outlet isolation valve to stop the target water sample from entering the downstream water quality monitoring device, then closes the bypass valve and opens the storage inlet valve to allow subsequent target water samples to enter the storage tank. By first isolating the downstream water quality monitoring device and then switching the sampling path, it prevents the target water sample with unstable flow rate from continuing to enter the downstream water quality monitoring device during the path switching process.

[0034] Furthermore, once the storage flow rate meets the metering and sampling conditions, the control unit starts the metering pump and opens the outlet isolation valve after the metering pump enters the set sampling state, allowing the target water sample in the storage tank to re-enter the downstream water quality monitoring device. To avoid repeated switching between the bypass sampling path and the metering sampling path during a single testing task, the bypass valve remains closed after entering the storage metering and sampling state until the current testing task is completed. When the inlet flow rate again meets the direct sampling conditions, the sampling mode is re-evaluated before the start of the next single testing task, and bypass sampling is not directly restored in the current testing task.

[0035] It should be noted that the above switching process prioritizes the protection of the downstream water quality monitoring device. Short-term interruptions in sample supply are allowed during the switching process, but this does not mean that the existing structure can achieve seamless and continuous switching between the two sample supply modes.

[0036] In another specific embodiment, the metering and sampling conditions include that the storage flow rate is not lower than the target storage flow rate; the water sample volume required for a single detection task is equal to the product of the target sampling flow rate and the sampling duration plus the pipeline replacement water volume, and the target storage flow rate is the sum of the water sample volume required for a single detection task and the water volume surplus.

[0037] In this embodiment, the water sample volume and target storage capacity required for a single detection task are determined according to the following formulas:

[0038] In the formula, This indicates the amount of water sample required for a single testing task. This indicates the target sample flow rate of the metering pump. This indicates the duration of sample supply required for the backend water quality monitoring device to complete effective testing. This indicates the volume of water required to replace residual water samples in the outlet water passage and shared pipe section. Indicates the target storage capacity. This indicates the remaining water volume.

[0039] Specifically, the water volume margin is used to compensate for the cumulative error of the sample injection flow rate, the delivery error of the metering pump, and the residual water volume in the storage tank and connecting pipeline. It is also used to provide the amount of sewage required to discharge the residual water sample in the metering sample supply path, the water outlet path and the common pipe section into the common sewage branch after the metering sample supply is completed, and to ensure that the metering pump inlet retains the minimum amount of water required to avoid cavitation at the end of the sewage discharge.

[0040] For low-flow water samples, the storage tank first accumulates the sample over a longer period, and then the metering pump supplies the sample within a shorter supply period. If the target water sample does not reach the target flow rate within the specified storage time, the metering pump is stopped, the target water path is closed, and an insufficient flow signal is output to the host computer or DCS system, ending or rescheduling the current testing task.

[0041] In another specific embodiment, the storage flow rate is determined by accumulating the sample inflow rate detected during the storage period over time; the metering pump is kept stopped before the storage flow rate reaches the target storage flow rate, and the water supply to the storage tank is stopped and the metering pump is started after the storage flow rate reaches the target storage flow rate; the cumulative sample supply is determined based on the target sample supply flow rate and the running time of the metering pump, and the metering pump is stopped after the cumulative sample supply reaches the water sample volume required for the single detection task.

[0042] Furthermore, at the start of the storage process, the control unit resets the cumulative storage flow rate to zero, and only accumulates the injection flow rate during the period when the bypass valve is closed, the storage inlet valve is open, and the target water sample enters the storage tank. The storage flow rate is determined according to the following formula:

[0043] In the formula, Indicates the current stored flow rate. This indicates the initial water sample volume in the storage tank at the start of the flow storage process. Indicates the first Sample injection flow rate within a cumulative time period This indicates the corresponding cumulative time period. When the storage tank discharges residual water samples after each sewage discharge reset, the initial water sample volume is determined according to the known residual volume after reset; when the storage tank is emptied, the initial water sample volume is set to zero.

[0044] This method of determining the storage flow rate utilizes existing flow detection components and control units, and does not require a liquid level sensor as a necessary condition.

[0045] Specifically, the control unit prevents the metering pump from starting before the storage flow reaches the target storage flow; after the storage flow reaches the target storage flow, the control unit closes the storage inlet valve to stop water intake into the storage tank, and then starts the metering pump. When the metering pump operates at the target sampling flow rate, the cumulative sampling volume is determined according to the following formula:

[0046] In the formula, Indicates the cumulative sample supply. This indicates the time the metering pump operates at the target sample supply flow rate. When the cumulative sample supply reaches the water sample volume required for a single testing task, the metering pump stops, and the remaining water in the storage tank is discharged during subsequent sewage discharge.

[0047] The metering pump operates according to the calibrated working parameters. The cumulative sample supply is the sample supply obtained based on the target sample supply flow rate and the running time, and does not indicate that the system has set up a metering pump outlet flow feedback closed loop.

[0048] In another specific embodiment, the process of discharging the residual water sample in the target waterway into the sewage discharge passage includes discharging the residual water sample in the storage tank through the sewage discharge branch of the waterway, and discharging the residual water sample in the outlet passage of the target waterway through the common sewage discharge branch; when switching to the next target waterway, after closing the target waterway, the next target water sample flows through the outlet passage of the next target waterway through the common pipe section and is discharged by the common sewage discharge branch; after the cumulative replacement water volume reaches the replacement water volume set according to the volume of the common pipe section, the next target water sample is sent to the back-end water quality monitoring device.

[0049] Furthermore, after a single testing task is completed, the control unit closes the corresponding instrument inlet valve and opens the common drain valve. With the current sample supply path and outlet path remaining connected, the target water sample flows through the outlet path and the common pipe section before being discharged through the common drain branch. Once the cumulative discharge volume reaches the discharge volume set according to the volume of the outlet path and the common pipe section, the control unit stops the current sample supply and closes the outlet isolation valve and the common drain valve. When using a storage-based metering sample supply, the control unit also opens the corresponding water circuit drain valve, allowing the remaining water sample in the storage tank to be discharged through the water circuit drain branch. After the storage tank discharge conditions are met, the water circuit drain valve and the target water circuit selection valve are closed, restoring the target water circuit to standby mode.

[0050] The shared pipe section refers to the pipe through which different water samples flow between the outlet passage of each water sample sampling path and the inlet valve of each instrument, including at least the confluence of each outlet passage and the main water sample distribution pipe.

[0051] Specifically, when switching to the next target water path, the control unit closes the inlet valves of each instrument, opens the outlet isolation valve and the common drain valve of the next target water path, allowing the next target water sample to flow through the common pipe section via the outlet passage and be discharged through the common drain branch. After the cumulative replacement water volume reaches the set replacement water volume, the control unit closes the common drain valve and opens the inlet valve of the instrument corresponding to the detection task, allowing the next target water sample to enter the corresponding back-end water quality monitoring device.

[0052] The set replacement water volume is determined based on the volume of the shared pipe section and satisfies:

[0053] In the formula, This indicates the cumulative amount of water replaced. Indicates the volume of the shared pipe section. This represents the replacement coefficient determined based on the allowable residual ratio. The replacement coefficient is determined according to pipeline structure, water sample differences, and testing accuracy requirements, and is not limited to a specific value.

[0054] When the replacement flow rate remains stable, the replacement time can be determined based on the shared pipe section volume and the replacement flow rate. The above replacement process preferentially uses the next target water sample as the replacement medium, and does not require a separate flushing water source as a necessary condition.

[0055] In another specific embodiment, multiple water sampling water paths are sequentially interlocked, so that the next target water path is connected to the common sewage branch only after the target water path is closed, and is connected to the back-end water quality monitoring device after the residual water sample is replaced; during the sampling period, only one of the water sampling water paths is allowed to connect to the back-end water quality monitoring device.

[0056] Furthermore, the control unit sets independent operating states for each water sampling circuit. These operating states include at least standby, connection, flow determination, bypass sampling, storage, metering sampling, sewage discharge, and fault stop. Before issuing the start command for the next target water circuit, the control unit first confirms that the current target water circuit has stopped sampling, the metering pump has stopped, the bypass valve and the storage inlet valve have closed, and the residual water sample replacement process has been completed. If the aforementioned conditions are not met, the next target water circuit is not allowed to enter the sampling state.

[0057] Specifically, at any given time, only the target water path's selection valve and outlet isolation valve are allowed to be in the open state required for sampling, while other water sampling paths remain isolated. When the control unit receives instructions to simultaneously supply samples from two or more water sampling paths, it will not execute conflicting sampling instructions and will keep non-target water paths closed.

[0058] Before supplying samples to the downstream water quality monitoring device, the control unit can also obtain the readiness status of the downstream water quality monitoring device through the communication unit. If the downstream water quality monitoring device is not ready, the outlet isolation valve remains closed, and the target water sample enters the sewage discharge path, or the flow continues to be stored if the remaining volume of the storage tank allows. After the downstream water quality monitoring device becomes ready, the sampling task continues to be performed according to the current storage flow and sample inlet flow status. It should be noted that some component names in the attached drawings are from the structural disclosure stage and have the following correspondence with the names used in this specification: Water sample main pipe 2 in the attached drawings corresponds to the water sample header pipe as referred to in this specification; equipment switching valve 3 corresponds to the device switching valve; sample inlet solenoid valve 4 corresponds to the inlet solenoid valve; flow meter 5 belongs to the flow detection component; bypass solenoid valve group 6 corresponds to the bypass valve; buffer storage tank 7 corresponds to the storage tank; sample outlet pipe 10 corresponds to the outlet water passage; and sewage discharge pipe 11 corresponds to the sewage discharge branch of the water system. Figure 5 The drainage branch connected to the lower part of the main distribution pipe shares a common sewage branch, and the front-end valve 12 corresponds to the outlet isolation valve. The components referred to by the different names mentioned above have the same structural position and function in this embodiment, and will be described below according to the terminology used in this specification.

[0059] In one specific embodiment, a multi-channel water sample dual-mode sampling system is provided, including a control unit, a sewage discharge passage and multiple water sample sampling channels, each of which is connected to a water sample main pipe. Each water sampling path includes an inlet path, a flow detection component, a bypass sampling path, a storage path, a metering sampling path, and an outlet path. The inlet path is equipped with a water path selection valve, and the flow detection component is located in the inlet path. The outlet of the flow detection component is connected to the inlet of the bypass sampling path and the inlet of the storage path, respectively. The bypass sampling path is equipped with a bypass valve, and the outlet of the bypass sampling path is connected to the outlet path. The storage path is sequentially equipped with a storage inlet valve and a storage tank. The outlet of the storage tank is connected to the outlet path via a metering sampling path equipped with a metering pump. The outlet path is used to connect to a downstream water quality monitoring device. The sewage discharge path includes water path sewage branches connected to each of the storage tanks and a common sewage branch connected to a common pipe section downstream of each of the outlet paths. Each water path sewage branch and the common sewage branch are equipped with a sewage valve. The control unit is connected to the water path selection valve, the flow detection component, the bypass valve, the storage inlet valve, the metering pump, and each of the drain valves. It controls the opening of the water path selection valve of the target water path in the multiple water sampling paths according to the sampling command. Based on whether the inlet flow rate of the target water path meets the direct sampling conditions, it controls the closing of the storage inlet valve and the opening of the bypass valve of the target water path when the direct sampling conditions are met, and controls the closing of the bypass valve and the opening of the storage inlet valve of the target water path when the direct sampling conditions are not met. After the storage flow rate in the storage tank of the target water path meets the metering sampling conditions, it controls the metering pump of the target water path to supply samples according to the target sampling flow rate. Finally, it stops the sampling after the sampling is completed and controls the pump to supply samples.

[0060] In this embodiment, each water sampling channel is sequentially divided into an inlet section, a supply branch section, and an outlet section according to the water flow direction. The target water sample in the main water sample pipe enters the inlet channel via a water channel selection valve, and after passing through a flow detection component, enters either the bypass supply channel or the storage channel. The bypass supply channel bypasses the storage tank and metering pump before connecting to the outlet channel; the storage channel connects to the inlet of the storage tank, and the outlet of the storage tank connects to the outlet channel via a metering pump. The two supply channels converge at the outlet channel and supply samples to the downstream water quality monitoring device; the water channel selection valve controls the entry of the water sample from the corresponding main water sample pipe into the water sampling channel. In the two-stage isolation implementation structure, the water channel selection valve is composed of a device switching valve located on the main water sample pipe side and an inlet solenoid valve located on the inlet channel; as shown... Figure 2As shown, the multi-channel water sample dual-mode sampling system in this embodiment includes a cabinet 1 and four water sample extraction channels installed within the cabinet 1. Each of the four water sample extraction channels is connected to a corresponding water sample header 2. Each water sample extraction channel uses the same fluid structure and is equipped with a device switching valve 3, an inlet solenoid valve 4, a flow meter 5, a bypass valve 6, a storage tank 7, a metering pump 8, a check valve 9, an outlet passage 10, a sewage discharge passage 11, and an outlet isolation valve 12.

[0061] The device switching valve 3 is located between the water sample header 2 and the corresponding water sample sampling path, and is used to control whether the water sample in the corresponding water sample header 2 enters the cabinet 1. The sampling solenoid valve 4 is located after the device switching valve 3, and is used to further isolate the water sample entering the cabinet 1. The device switching valve 3 and the sampling solenoid valve 4 work together to form a water path selection structure. When a certain water sample sampling path is determined as the target water path, the control unit controls the device switching valve 3 and the sampling solenoid valve 4 corresponding to the target water path to open, while keeping the device switching valve 3 and the sampling solenoid valve 4 corresponding to the other water sample sampling paths closed.

[0062] The flow meter 5 is installed after the solenoid valve 4 to detect the flow rate of the sample entering the target water path and transmit the detected flow rate signal to the control unit. Figure 2 This is a simplified schematic diagram of the fluid structure. The bypass sampling passage is represented by a dashed line to distinguish it from the main pipeline. Due to the limitations of the planar layout in the attached diagram, the upper end of the dashed line extends from the inlet passage side on the drawing, which does not indicate that the bypass sampling passage is connected to the inlet passage before the flow meter 5. In terms of the actual fluid connection relationship, the target water sample passes sequentially through the device switching valve 3, the inlet solenoid valve 4, and the flow meter 5. The outlet of the flow meter 5 is connected to both the bypass sampling passage and the storage passage via a diversion connection. Therefore, the target water sample entering either the bypass sampling passage or the storage passage has already been detected by the flow meter 5.

[0063] Figure 2 The dashed branch of the bypass valve 6 in the attached diagram represents the bypass sampling path. This dashed line is used to distinguish the bypass pipeline from the main pipeline in the drawing and does not indicate electrical control connections. The bypass sampling path bypasses the storage tank 7 and the metering pump 8, and merges with the metering sampling path before the check valve 9. When the target water path meets the conditions for direct sampling, the control unit opens the bypass valve 6 and closes the storage path leading to the storage tank 7, allowing the target water sample to enter the downstream water quality monitoring device via the bypass sampling path, check valve 9, outlet isolation valve 12, and outlet path 10. During this sampling process, the target water sample is transported by the pressure and flow rate of the water sample header 2 itself, while the metering pump 8 remains stopped.

[0064] When the target water path does not meet the conditions for direct sampling, the control unit closes the bypass valve 6 and opens the storage path to the storage tank 7, allowing the target water sample passing through the flow meter 5 to enter the storage tank 7. The storage inlet valve used to control the water sample entering the storage tank 7... Figure 2 The valve structure serving as the storage flow path is simplified and not separately labeled. The storage inlet valve is located between the flow meter 5 and the storage tank 7, and its opening or closing is controlled by the control unit; the storage inlet valve is located between the outlet of the flow meter 5 and the inlet of the storage tank 7. Figure 2 The storage inlet valve is not separately labeled, and the omission of the storage inlet valve does not change the actual fluid relationship in which the flow meter 5 outlet, the storage inlet valve and the storage tank 7 are connected in sequence.

[0065] After the target water sample enters the storage tank 7, it is temporarily stored within the tank. The metering pump 8 remains stopped until the storage flow rate reaches the metering and sample supply condition. Once the storage flow rate reaches the metering and sample supply condition, the control unit closes the storage inlet valve and starts the metering pump 8, allowing the target water sample in the storage tank 7 to enter the downstream water quality monitoring device via the metering pump 8, check valve 9, outlet isolation valve 12, and outlet passage 10. The metering pump 8 delivers the water sample according to the target sample supply flow rate to complete a single detection task with a limited duration.

[0066] Check valve 9 is located after the junction of the bypass sampling passage and the metering sampling passage. It allows flow from bypass valve 6 and metering pump 8 towards the outlet passage 10, preventing water samples in the outlet passage 10 or downstream pipeline from flowing back into the storage tank 7, metering pump 8, or bypass sampling passage. Outlet isolation valve 12 is located after check valve 9 and controls whether the current water sample collection path is connected to the downstream water quality monitoring device.

[0067] Specifically, the sampling processes of multiple water sampling circuits—including inlet, flow detection, bypass sampling, storage, metering sampling, and effluent—are independent of each other. Each sewage branch merges into the main sewage pipe after its corresponding sewage valve, ensuring that the different water sampling circuits remain isolated from each other when the sewage valves are closed. Multiple water sampling circuits share the control unit, communication unit, power supply, and cabinet. Figure 2 In this system, each reservoir 7 is connected to a corresponding water discharge branch, with label 11 indicating the water discharge branch and the water discharge valve located on that branch. The water discharge branch is used to discharge the remaining water sample and overflow water from the corresponding reservoir 7. Each water discharge branch merges into the main discharge pipe downstream of the corresponding water discharge valve.

[0068] The sewage discharge passages 11 of each water sampling water path converge into the main sewage pipe after the corresponding sewage discharge valve. When the sewage discharge valve is closed, the sewage discharge passages 11 of each water sampling water path remain isolated; when the sewage discharge valve is open, the water sample in the corresponding storage tank 7 or the corresponding water sampling water path enters the main sewage pipe.

[0069] After sampling is completed, the shared pipe section and the storage tank are discharged through the shared sewage branch and the water sewage branch, respectively. The control unit first closes the corresponding instrument inlet valve and opens the shared sewage valve, allowing the target water sample to continue flowing through the outlet passage 10 and the shared pipe section before being discharged through the shared sewage branch; after the sewage discharge conditions of the shared pipe section are met, the current sampling is stopped and the outlet isolation valve 12 and the shared sewage valve are closed. When using storage metering for sampling, the control unit then opens the corresponding water sewage valve, allowing the remaining water sample in the storage tank 7 to be discharged through the water sewage branch; after the sewage discharge conditions of the storage tank are met, the water sewage valve, the device switching valve 3, and the sampling solenoid valve 4 are closed, restoring the target water path to standby status.

[0070] Figure 2 This mainly indicates the water supply and drainage branches of each of the 7 storage tanks and the corresponding water sampling channels. Figure 5 This mainly indicates the shared sewage branch of the main distribution pipe. Figure 2 and Figure 5 The sewage discharge structure of this embodiment is represented by a common diagram, and it is not required that the two types of sewage discharge branches be drawn repeatedly in the same attached drawing.

[0071] The control unit includes a PLC and an input / output unit. The flow detection component outputs a sample inlet flow signal to the control unit, and the control unit outputs control commands to the water path selection valve, bypass valve, storage inlet valve, metering pump, drain valve, and outlet isolation valve. The communication unit is used to transmit sampling commands, operating status, sample supply completion signals, and fault signals between the control unit and the host computer, DCS system, or backend water quality monitoring device; such as... Figure 5 As shown, the sampling water source refers to the water sample to be tested provided by multiple water sample headers 2, and the on-site sampling constant current and pressure stabilizing device refers to the multi-channel water sample dual-mode sampling system installed in the cabinet 1. Figure 5 The term "constant flow and stable pressure" indicates that water samples with low flow or fluctuating flow are buffered by the storage tank 7 and then output by the metering pump 8 according to the target sample supply flow rate. It does not indicate that the metering pump 8 actively adjusts the flow rate during the bypass direct sample supply process.

[0072] A multi-channel, dual-mode water sample supply system is installed between the sampling water source and the intelligent water quality and sample switching device. The control unit selects the appropriate water sample header 2 according to the sampling command, allowing the target water sample to enter the cabinet 1 via the device switching valve 3 and the inlet solenoid valve 4. The inlet flow rate of the target water sample is detected by the flow meter 5. After the target water sample is directly supplied via a bypass or metered after storage, it is transported to the intelligent water quality and sample switching device via the outlet passage 10.

[0073] Figure 5The intelligent water quality and water sample switching device includes a main distribution pipe and multiple instrument sampling branches connected to the main distribution pipe. The main distribution pipe corresponds to the common pipe section referred to in this specification, and each instrument sampling branch is connected to instrument 1, instrument 2, instrument 3, and instrument 4, respectively. Instruments 1 to 4 are downstream water quality monitoring devices, used to receive target water samples distributed by the main distribution pipe and perform corresponding water quality parameter detection. Figure 5 The sampling module included in the instrument 2 is used to sample the target water sample entering the corresponding instrument's sampling branch.

[0074] The lower part of the distribution manifold and Figure 5 The drainage branch shown is part of the sewage discharge passage 11. When switching water samples, the target water sample first flows through the main distribution pipe and is discharged through the drainage branch to replace the water sample remaining in the main distribution pipe from the previous channel. After the set replacement volume is reached, the common sewage discharge valve is closed and the corresponding instrument inlet valve is opened to allow the target water sample to enter the corresponding instrument.

[0075] Figure 5 The PLC shown is the control unit referred to in this manual. It is used to receive sampling instructions, flow signals, instrument status signals and fault signals, and to send control instructions to the multi-channel water sample dual-mode sampling system and the water quality and water sample intelligent switching device. Figure 5 The HMI shown is connected to the PLC and is used to input sampling commands and display the current target water sample, sampling mode, instrument operating status, and fault status. The PLC also interacts with the host computer or DCS system via control and communication lines. Figure 2 and Figure 5 The sewage discharge structures at different locations are shown. Figure 2 The sewage discharge passage 11 shown is mainly used to discharge the remaining water samples and wastewater in the storage tank 7 and the corresponding water sample sampling passage; Figure 5 The shared sewage branch shown is mainly used to discharge residual water samples and replacement water samples from the main distribution pipe. Figure 2 The sewage discharge passage 11 shown is Figure 5 When all the drainage branches shown are connected to the sewage system, they are isolated by corresponding valves. The instrument inlet pipe section downstream of the instrument inlet valve is not included in the volume of the common pipe section replaced by the common sewage branch. The inlet replacement time and signal stabilization time required by the downstream water quality monitoring device are included in the sampling duration.

[0076] After the sample supply task is completed, first through Figure 2 The sewage discharge path 11 shown discharges the residual water sample from the current target water path and the storage tank 7; when switching to the next target water sample, the next target water sample is then allowed to flow through it. Figure 5The main distribution pipe is shown, and the water is discharged through the drainage branch. Only after the replacement water volume determined according to the main distribution pipe volume is reached will the next target water sample enter the corresponding instrument, thereby reducing the residue of the previous water sample in the target water path and the subsequent shared pipe section. The sewage discharge structure in this embodiment includes water path sewage branch and shared sewage branch. The water path sewage branch is used to discharge the remaining water sample in the corresponding storage tank and water sample sampling water path. The shared sewage branch is connected to the end or lower position of the main distribution pipe and is used to discharge the residual water sample and replacement water sample in the shared pipe section. Each instrument inlet branch is equipped with an instrument inlet valve. When replacing the shared pipe section, each instrument inlet valve is closed, and the outlet isolation valve of the next target water path and the shared pipe section drain valve are opened, allowing the next target water sample to flow through the outlet passage through the shared pipe section and be discharged through the shared sewage branch; after reaching the set replacement water volume, the shared pipe section drain valve is closed, and the instrument inlet valve corresponding to the detection task is opened.

[0077] In one specific embodiment, the storage tank includes a tank body and an inlet, an outlet, an overflow port, and a top vent. The inlet is connected to the storage inlet valve via a quick-release connection, and the outlet is connected to the inlet of the metering pump via a quick-release connection. The overflow port 18 is connected to a vertically extending external overflow pipe. The outlet of the external overflow pipe is located at a height corresponding to the highest storage position of the storage tank 7 and is connected to the sewage branch of the waterway via an open drainage method. When the water sample in the tank 14 exceeds the highest storage position, the water sample exceeding this position enters the sewage branch of the waterway through the external overflow pipe under the action of gravity. The outlet of the external overflow pipe is kept open to the outside to avoid the external overflow pipe forming a continuous siphon. Figure 3 and Figure 4 This indicates the connection position of the overflow port 18 on the pool body 14, but does not indicate the specific route of the external overflow pipe outside the pool body 14; the storage pool 7 includes a top vent 13, a pool body 14, a water inlet port 15, a sealing ring 16, a water outlet port 17, and an overflow port 18. Figure 3 This is a cross-sectional structural diagram of the reservoir 7, used to show the connection relationship between each interface and the internal space of the reservoir body 14; Figure 4 This is a top view of the reservoir 7, used to show the projected positions of each interface on the reservoir body 14.

[0078] The interior of the pool body 14 forms a storage space for temporarily storing the target water sample. A top vent 13 is located at the top of the pool body 14 and communicates with the storage space inside the pool body 14. This vent is used to balance the air pressure inside and outside the pool body 14 when the water sample enters or exits, preventing pressure buildup or negative pressure during storage or drainage. The top vent 13 is only used for pressure balancing and is not used to actively introduce gas into the target water sample.

[0079] The inlet port 15 is used to connect to the storage and flow path. The inner side of the inlet port 15 extends into the tank body 14 to form an inlet pipe, so that the target water sample enters the tank body 14 through the inlet port 15 and is released at the outlet of the inlet pipe. The outlet of the inlet pipe and the outlet port 17 are spaced apart to extend the path of the target water sample from the inlet position to the outlet position, reducing the possibility that the water sample entering the tank body 14 will flow directly to the outlet port 17.

[0080] Figure 4 The projection of the middle water inlet 15 and the top vent 13 in the top view direction coincides. The top vent 13 is located at the top of the pool body 14. The water inlet 15 is connected from the bottom of the pool body 14 and extends into the pool body. The two are spaced apart in the height direction and form independent channels, and do not belong to the same interface.

[0081] The outlet port 17 is located at the lower part of the tank body 14 and is connected to the inlet of the metering pump 8. After the metering pump 8 is started, the target water sample in the storage tank 7 enters the metering pump 8 through the outlet port 17, and is then transported by the metering pump 8 to the outlet passage 10. The inlet port 15 and the outlet port 17 are respectively provided with connecting joints. The connecting joints are quick-release connection structures as described in this specification, used to connect the storage tank 7 to the corresponding pipeline, and allowing the storage tank 7 to be removed during maintenance.

[0082] Overflow port 18 is connected to the sewage branch of the water system via an external overflow pipe. The external overflow pipe extends upward from overflow port 18 to a height corresponding to the highest flow position of the storage tank 7, and then connects to the sewage branch of the water system. When the water sample in the tank 14 reaches the highest flow position, the water sample exceeding this position enters the sewage branch of the water system through the overflow pipe and overflow port 18. Figure 3 and Figure 4 This indicates the connection position of the overflow interface 18 on the pool body 14, but does not indicate the specific route of the external overflow pipe outside the pool body 14.

[0083] Furthermore, the inlet of the storage tank is used to receive the target water sample transported by the storage flow path, the outlet is located in a position suitable for directing the water sample in the tank to the metering pump, and the overflow port is used to discharge excess water sample into the sewage discharge path when the water sample in the storage tank reaches the maximum allowable storage level. The top vent is used to balance the air pressure inside and outside the storage tank, preventing pressure buildup during storage and drainage. The top vent is for air pressure balance and is not used for aeration of the target water sample.

[0084] Furthermore, the inlet pipe of the storage tank extends from the inlet interface into the tank body, with the inlet release point and outlet interface spaced apart. This increases the flow path of the target water sample from the inlet to the outlet interface, reducing the probability of the inlet flowing directly to the outlet interface. The outlet position of the inlet pipe is determined based on the effective storage range of the storage tank, avoiding the formation of obvious drop-offs and continuous gas-liquid mixing.

[0085] When the storage tank is made of transparent and corrosion-resistant material, the water sample status inside the tank can be observed from the outside. The inlet and outlet interfaces adopt a quick-release connection structure to facilitate the removal of the storage tank for cleaning. The volume of the storage tank is determined based on the target storage flow rate, the minimum retention water volume at the metering pump inlet, and the overflow location, ensuring that the effective storage volume of the storage tank is not less than the target storage flow rate.

[0086] For water samples sensitive to pH, dissolved gases, or volatile components, the residence time of the water sample in the storage tank should be shortened, and the gas-liquid contact during the water intake process should be reduced. Open-ventilation storage methods should not be used indiscriminately for testing items that are highly sensitive to air contact.

[0087] In one specific embodiment, the outlet of the bypass sampling passage and the outlet of the metering sampling passage are both connected to the inlet of the outlet passage. A check valve and an outlet isolation valve are sequentially arranged in the outlet passage along the sampling direction. The common pipe section is connected to the downstream water quality monitoring device via an instrument inlet branch equipped with an instrument inlet valve. The control unit is connected to the water path selection valve, the outlet isolation valve, and the instrument inlet valve, and implements interlock control for each of the water sampling water paths so that when the target water path is connected to the downstream water quality monitoring device, the other water sampling water paths remain isolated, and the next target water sample enters the downstream water quality monitoring device after the replacement of the common pipe section is completed.

[0088] Specifically, the outlets of the bypass sampling path and the metering sampling path are both connected to the inlet of the outlet water path. A check valve is installed after the connection point between the two sampling paths and the outlet water path. The allowable flow direction of the check valve is from the two sampling paths towards the downstream water quality monitoring device, preventing backflow of water samples from the downstream or shared pipe sections into the bypass sampling path, metering pump, or storage tank. An outlet isolation valve is installed between the check valve and the downstream water quality monitoring device to control whether the current water sampling path is connected to the downstream water quality monitoring device.

[0089] Furthermore, in the bypass direct sampling state, the control unit closes the storage inlet valve, opens the bypass valve, and opens the outlet isolation valve after confirming that the target water sample meets the direct sampling conditions and the downstream water quality monitoring device is in a ready state; in the storage state, the control unit closes the bypass valve and the outlet isolation valve, and opens the storage inlet valve; in the metering sampling state, the control unit keeps the bypass valve closed, closes the storage inlet valve, starts the metering pump, and opens the outlet isolation valve; in the water circuit discharge state, the control unit closes the outlet isolation valve and opens the water circuit discharge valve, allowing the remaining water sample in the storage tank to enter the water circuit discharge branch; in the shared pipe section replacement state, the control unit closes the sampling valves of each instrument, opens the outlet isolation valve and the shared discharge valve of the target water circuit, allowing the replacement water sample to flow through the shared pipe section and be discharged by the shared discharge branch; in another embodiment, the control unit performs abnormal handling based on the flow detection component, the metering pump operating status, the downstream water quality monitoring device status, and the communication status. When the sample inlet flow rate is consistently below the minimum storage condition, the current sample supply task is stopped and the target water circuit is closed; when the flow rate fluctuation continuously exceeds the allowable fluctuation range, the bypass direct sample supply is stopped and the system switches to storage mode; when the storage tank fails to reach the target storage flow rate within the limited storage time, the metering pump remains stopped and outputs a storage insufficiency signal; when the metering pump returns to a fault state, the metering pump is stopped, the outlet isolation valve is closed, and the target water circuit is kept isolated from the downstream water quality monitoring device; when the downstream water quality monitoring device is not ready or communication is interrupted, the sample supply to the downstream water quality monitoring device is stopped, and the current water circuit remains in a sewage discharge or isolation state; when the sewage discharge process has not yet reached the set replacement water volume, the next target water circuit is not allowed to enter the sample supply state.

[0090] The above-mentioned abnormal handling should prioritize stopping the metering pump, closing the outlet isolation valve leading to the downstream water quality monitoring device, isolating non-target water paths, and outputting fault signals. Adding pressure sensors, level sensors, or outlet flow detection components is not a necessary condition.

[0091] In one specific embodiment, a multi-channel water sampling dual-mode sampling method is provided, in which a control unit controls the operation of multiple water sampling channels. This embodiment sets up four water sampling channels, each connected to a main water sampling pipe, and each channel is equipped with a channel selection valve, a flow detection component, a bypass sampling channel, a storage channel, a metering sampling channel, an outlet channel, and a sewage discharge channel. The bypass sampling channel is equipped with a bypass valve, the storage channel is equipped with a storage inlet valve and a storage tank, the metering sampling channel is equipped with a metering pump, the outlet channel is equipped with an outlet isolation valve, and the sewage discharge channel is equipped with a sewage discharge valve.

[0092] When each water sampling water path is in standby mode, all water path selection valves, bypass valves, storage inlet valves, outlet isolation valves, and drain valves are closed, and all metering pumps are stopped. Each water sample continues to flow in the original flow direction of its corresponding water sample header and does not enter the water sampling water path of this embodiment.

[0093] In this embodiment, taking the water sample corresponding to the second water sampling channel as the target water sample as an example, the specific sampling process includes the following steps.

[0094] Target waterway access: The control unit receives a sampling instruction from the backend water quality monitoring device or the upper control system, obtains the number of the water sample to be tested from the sampling instruction, and determines the second water sample sampling path as the target water path.

[0095] The control unit first confirms that the water selection valves and outlet isolation valves of the other three water sampling paths are all closed, thus isolating the remaining water sampling paths from the downstream water quality monitoring device. Then, the control unit closes the storage inlet valve and drain valve of the target water path, keeps all instrument inlet valves closed, opens the bypass valve, outlet isolation valve, and common drain valve of the target water path, and then opens the water selection valve of the target water path.

[0096] The target water sample enters the target water circuit through the corresponding main water pipe, flows sequentially through the water circuit selection valve, flow detection component, bypass sample supply passage, outlet passage, and common pipe section, and is discharged through the common sewage branch. The target water sample in this stage does not enter the downstream water quality monitoring device, but is used to replace the original residual water sample in the outlet passage and common pipe section of the target water circuit, and to provide flow detection data for judging the sample flow status.

[0097] Injection flow rate status judgment: During the flow of the target water sample through the flow detection component, the control unit continuously acquires multiple injection flow values ​​within a set detection time window, and determines the average injection flow and flow fluctuation based on the multiple injection flow values.

[0098] The average injection flow rate is determined by the following formula:

[0099] In the formula, The average injection flow rate, To set the detection time window for the first The injection flow rate obtained from the second test. This represents the number of traffic detections.

[0100] The degree of flow fluctuation is determined by the following formula:

[0101] In the formula, For the degree of traffic fluctuation, and These are the maximum and minimum injection flow rates within the set detection time window, respectively.

[0102] When the average injection flow rate is zero, the control unit directly determines that the target water path does not meet the conditions for direct sampling and no longer performs division calculations.

[0103] The conditions for direct sampling include: the average injection flow rate is within the direct sampling flow rate range, and the flow rate fluctuation does not exceed the allowable fluctuation threshold. The direct sampling flow rate range is determined based on the allowable injection flow rate range of the downstream water quality monitoring device.

[0104] When both of the above conditions are met, the control unit selects the bypass direct sample supply mode; when the average injection flow rate exceeds the direct sample supply flow rate range, or the flow rate fluctuation exceeds the allowable fluctuation threshold, the control unit selects the storage metering sample supply mode.

[0105] Bypass direct sample supply: When the target water path meets the conditions for direct sampling, the control unit keeps the metering pump stopped and the storage inlet valve closed, so that the target water sample continues to flow to the outlet water path through the bypass sampling path.

[0106] Before officially supplying samples to the downstream water quality monitoring device, the control unit closes the sampling valves of each instrument, keeps the outlet isolation valve of the target water path open, and opens the common drain valve, allowing the target water sample to continue flowing through the outlet passage and the common pipe section, and then be discharged through the common drain branch. The control unit determines the cumulative replacement water volume based on the sampling flow rate and replacement time detected by the flow detection component.

[0107] Once the cumulative water replacement volume reaches the preset pipeline replacement volume, the control unit closes the common drain valve and opens the instrument inlet valve corresponding to the detection task, allowing the target water sample to enter the downstream water quality monitoring device. The sampling duration is calculated from the moment the target water sample enters the downstream water quality monitoring device.

[0108] The replacement water volume in the pipeline is determined based on the effective volume to be replaced in the outlet passage of the target water path, the shared pipe section, and the downstream sampling pipeline. This value can be set as a multiple of the aforementioned effective volume. Therefore, before the target water sample enters the downstream water quality monitoring device, the water sample from the previous path has already been replaced and discharged by the target water sample.

[0109] During bypass sampling, the target water sample enters the downstream water quality monitoring device based on the pressure and flow rate of the main water sample pipe itself; the metering pump does not participate in bypass sampling. The control unit continuously monitors the inlet flow rate of the target water path and updates the inlet flow rate status according to the set monitoring time window.

[0110] When the injection flow rate always meets the direct sample supply conditions and the continuous sample supply time reaches the sample supply duration required for a single detection task, the control unit determines that the sample supply is complete.

[0111] Switching from bypass sampling to flow metering sampling: During bypass direct sampling, if the injection flow rate temporarily does not meet the direct sampling conditions, the control unit will not immediately switch the sampling mode, but will continue to monitor the injection flow rate. If the duration of the failure to meet the direct sampling conditions reaches the set time, the control unit will determine that the target water sample can no longer be stably directly sampled.

[0112] The control unit first closes the instrument inlet valve corresponding to the current detection task and opens the common drain valve, causing the target water sample with unstable flow to stop entering the downstream water quality monitoring device and redirect to the common drain branch. Then, it closes the target water path selection valve and the outlet isolation valve, stopping the upstream target water sample from entering the target water path. After the valve action waiting time, the control unit closes the bypass valve and the common drain valve and opens the storage inlet valve. After the storage inlet valve completes its opening action, it reopens the water path selection valve, allowing the target water sample to enter the storage tank.

[0113] This switching sequence isolates the downstream water quality monitoring device from the target water path before switching the bypass valve and the storage inlet valve, preventing water samples with unstable flow rates from continuing to enter the downstream water quality monitoring device during the switching process.

[0114] Because the sample supply is interrupted during the switching process, this embodiment recalculates the continuous sampling time after the metering pump resumes sampling to ensure that the downstream water quality monitoring device obtains continuous water samples that meet the set duration. Before the completion of the current single detection task, the sampling will not switch back to bypass direct sampling from the storage metering system; the sampling mode will be re-determined at the start of the next detection task.

[0115] Target storage capacity determined: When the target water path does not meet the conditions for direct sampling, or when switching from direct sampling via bypass to metered sampling, the control unit determines the target storage flow rate based on the target sampling flow rate, sampling duration, pipeline replacement water volume, and water volume margin.

[0116] The target storage capacity is determined according to the following formula:

[0117] In the formula, Accumulate traffic for the target. This refers to the target sampling flow rate used when the metering pump delivers water samples to the downstream water quality monitoring device. The duration of sample supply required for the downstream water quality monitoring device to complete a single testing task. This is the amount of water sample required to replace residual water in the effluent passage and shared pipe section before formal testing. The water volume margin is set to compensate for the cumulative error of the injection flow rate, the delivery error of the metering pump and the water volume remaining in the pipeline, and to provide the water volume required to discharge the residual water sample in the metering supply path, the water outlet path and the common pipe section after the metering supply is completed, as well as the minimum water volume retained at the inlet of the metering pump.

[0118] The target storage flow rate shall not exceed the effective storage volume of the storage tank. When the target storage flow rate determined according to the above relationship exceeds the effective storage volume of the storage tank, the control unit shall not start the metering pump and shall output a fault signal indicating that the storage flow rate and the storage tank volume are mismatched.

[0119] Accumulated flow rate and metering pump start-up: Before entering the storage state, the previous residual water sample in the storage tank has been discharged, the metering pump remains stopped, and the sewage discharge passage of the storage tank remains closed. The control unit begins to accumulate the amount of water sample entering the storage tank after the storage inlet valve is fully opened.

[0120] The storage capacity is determined by accumulating the injection flow rate detected by the flow detection component during the storage period over time, and is expressed in continuous form as follows:

[0121] When using discrete flow data, the storage flow is expressed as:

[0122] In the formula, To accumulate traffic, For the first Sample flow rate within each detection cycle This refers to the duration of the corresponding detection cycle.

[0123] Before the storage flow reaches the target storage flow, the control unit keeps the metering pump stopped to prevent it from cavitating due to insufficient storage. Once the target storage flow is reached, the control unit closes the water circuit selection valve and the storage inlet valve, stopping water supply to the storage tank. The control unit starts the metering pump after the storage inlet valve has closed to prevent storage and metering from occurring simultaneously, which could affect the determination of the storage flow and sample supply.

[0124] This embodiment adopts a working method of first storing the flow and then supplying the sample, without relying on the storage tank to make up for the long-term insufficient flow. When the inlet flow rate of the target water sample is low, the amount of water sample required to complete a limited-duration detection task is obtained by extending the storage time; when the inlet flow rate is zero or the target storage flow rate cannot be reached within the limited storage time, the metering pump is not started.

[0125] Metering pump for quantitative sample supply: After the metering pump starts, the control unit closes the inlet valves of each instrument, opens the outlet isolation valve and the common drain valve of the target water circuit, so that the target water sample output by the metering pump flows through the metering supply passage, the outlet passage and the common pipe section in sequence, and is discharged through the common drain branch.

[0126] When the cumulative metered sample supply reaches the pipeline replacement water volume, the control unit closes the common drain valve and opens the instrument inlet valve corresponding to the detection task, so that the target water sample enters the back-end water quality monitoring device according to the target sample supply flow rate, and starts calculating the sample supply duration.

[0127] In this embodiment, the metering pump operates according to a pre-set and calibrated target sample supply flow rate, without using the sample inlet flow rate to control the instantaneous output of the metering pump. The sample inlet flow rate is used to determine the sample supply mode and calculate the storage flow rate, while the metering pump is used to deliver water samples from the storage tank according to the target sample supply flow rate; their functions are different.

[0128] The cumulative sample supply of the metering pump is determined according to the following formula:

[0129] In the formula, For the cumulative sample supply, This represents the cumulative operating time of the metering pump.

[0130] When the cumulative sample supply reaches the sum of the pipeline replacement water volume and the water sample volume required for formal testing, that is, after the metering pump has completed pipeline replacement and continuously supplied samples according to the target sample supply flow rate for the specified time, the control unit stops the metering pump and determines that the sample supply is complete. The water sample retained in the storage tank as a reserve is discharged during subsequent sewage discharge.

[0131] Sewage discharge and resetting after sample supply: When using a bypass for direct sampling, after sampling is completed, the control unit first closes the corresponding instrument inlet valve and opens the common drain valve to stop the target water sample from entering the downstream water quality monitoring instrument. The control unit keeps the target water path selection valve, bypass valve, and outlet isolation valve open, allowing the target water sample to continue flowing through the outlet passage and common pipe section and discharged through the common drain branch. When the cumulative discharge volume reaches the discharge volume set according to the volume of the outlet passage and common pipe section, the control unit closes the water path selection valve, bypass valve, and outlet isolation valve, and closes the common drain valve.

[0132] When using a storage-flow metering sampling method, once the cumulative sample supply reaches the required water sample volume for a single testing task, the control unit stops the metering pump and closes the corresponding instrument inlet valve, ending the metering sampling phase. Subsequently, the shared drain valve is opened and the metering pump is restarted, utilizing the remaining water in the storage tank to transport the residual water sample in the metering sampling path, outlet path, and shared pipe section to the shared drain branch. The metering pump operating time during the draining phase is accumulated separately from the effective operating time during the testing sampling phase. When the cumulative drain volume reaches the drain volume set according to the volume of the metering sampling path, outlet path, and shared pipe section, the control unit stops the metering pump and closes the outlet isolation valve and the shared drain valve. Then, the control unit opens the water drain valve, allowing the remaining water sample in the storage tank to be discharged through the water drain branch.

[0133] Once the sewage discharge duration of the storage tank reaches the set discharge time determined based on the remaining water volume in the storage tank and the drainage capacity of the sewage branch in the waterway, the sewage discharge of the storage tank is deemed complete. After the target waterway meets the corresponding sewage discharge completion conditions, the control unit closes all sewage discharge valves, storage inlet valves, bypass valves, and the waterway selection valve of the target waterway, restoring the target waterway to standby status.

[0134] Switching to the next target water sample: When it is necessary to test the next water sample, the control unit first stops the sampling of the current target water circuit, closes the outlet isolation valve, water circuit selection valve, bypass valve, and storage inlet valve of the current target water circuit, and completes the water circuit discharge for the current target water circuit. After the current target water circuit is closed, the control unit allows the next target water circuit to enter the discharge state.

[0135] After the next target water path is connected, the control unit keeps all instrument inlet valves closed, opens the outlet isolation valve and common drain valve of the next target water path, allowing the next target water sample to enter the outlet path through the bypass sampling path or metering sampling path, then flow through the common pipe section and be discharged through the common drain branch. After the cumulative replacement water volume reaches the replacement water volume set according to the volume of the common pipe section, the control unit closes the common drain valve and opens the instrument inlet valve corresponding to the detection task, allowing the next target water sample to enter the corresponding downstream water quality monitoring device.

[0136] During the entire switching process, the next target waterway enters the shared pipe section replacement state after the current target waterway is closed, but it is not connected to the specific back-end water quality monitoring instrument before the replacement is completed; in the sampling state, only one water sampling waterway is allowed to supply samples to the back-end water quality monitoring device at the same time.

[0137] Abnormal state handling: The control unit will suspend the current sample supply process if any of the following conditions occur: The following are examples of water flow rate issues: the target water flow rate is zero or consistently lower than the minimum required for storage; the cumulative storage flow rate fails to reach the target storage flow rate within the specified storage time; the target storage flow rate exceeds the effective storage volume of the storage tank; the metering pump fails to enter the operating state according to the control command; multiple water sampling water lines simultaneously request to connect to the downstream water quality monitoring device during the sampling period; and the cumulative replacement water volume fails to reach the set pipeline replacement water volume within the specified replacement time.

[0138] Specifically, when sampling is interrupted, the control unit closes the outlet isolation valve and the water path selection valve, stops the metering pump, and isolates the target water path from the downstream water quality monitoring device. When the sewage discharge path is ready for discharge, the sewage discharge valve is opened to discharge the water samples from the target water path and the storage tank, and a fault signal is output to the upper-level control system. After the fault is cleared and the target water path has completed sewage discharge and reset, the control unit receives the sampling command again and does not directly resume sampling from the interrupted position.

[0139] In summary, this embodiment has at least the following technical effects: This invention detects the inlet flow rate of the target water channel and selects either bypass direct sampling or metered sampling after storage based on whether the inlet flow rate meets the conditions for direct sampling. This allows water samples with sufficient and stable flow to quickly enter the downstream water quality monitoring device, while avoiding water samples with insufficient or fluctuating flow from directly impacting the downstream water quality monitoring device, thus balancing sampling efficiency and sampling stability. When the sample flow rate is insufficient or the fluctuation exceeds the allowable range, the present invention first uses a storage tank to accumulate the water sample required for a single detection task, and then uses a metering pump to deliver the water sample according to the target sample supply flow rate, so that the low flow rate water sample can be continuously supplied within a limited detection time, and reduces the impact of front-end flow rate changes and pressure fluctuations on the back-end detection process. This invention determines the target storage flow rate based on the target sample supply flow rate, sample supply duration, pipeline replacement water volume, and water volume surplus. It starts the metering pump after the storage flow rate meets the metering sample supply conditions, which can avoid premature sample supply when the storage flow is insufficient and metering pump cavitation, thereby improving the reliability of completing a single detection task. This invention continuously monitors the inlet flow rate during bypass sampling. When the inlet flow rate does not meet the conditions for direct sampling, it first stops the sampling to the downstream water quality monitoring device and then switches to the storage metering sampling. This can prevent unstable water samples from continuing to enter the downstream water quality monitoring device during the mode switching process. This invention discharges residual water sample in the current target water path before water sample switching, and allows the next target water sample to flow through the outlet passage and the common pipe section into the sewage passage. After reaching the set replacement water volume, it is then sent to the back-end water quality monitoring device. Combined with the check valve structure and multi-channel interlock control, it can reduce water sample backflow, cross-contamination caused by liquid mixing and residual water sample from the previous path. This invention coordinates the control of water path selection valve, bypass valve, storage inlet valve, metering pump, drain valve, and outlet isolation valve through a control unit. This enables the target water path access, flow rate judgment, sampling mode selection, storage, metering sampling, drain replacement, and standby reset to form a complete closed loop. It also ensures that only one water sampling path is connected to the downstream water quality monitoring device during the sampling period, thereby improving the safety and reliability of automatic switching and continuous detection of multiple water samples.

[0140] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A dual mode sampling method for multiple water samples, comprising: Includes the following steps: S1: Receive a sampling instruction, determine the target water sample from multiple candidate water samples according to the sampling instruction, and cause the target water sample to enter the target water channel corresponding to it; S2: Detect the injection flow rate of the target water channel to obtain the injection flow rate status; S3: Determine whether the target water path meets the direct sampling conditions based on the sampling flow rate status. If it does, close the storage channel and open the bypass sampling channel, so that the target water sample enters the downstream water quality monitoring device through the bypass sampling channel. If it does not meet the conditions, close the bypass sampling channel and open the storage channel, so that the target water sample enters the storage tank. After the storage flow rate in the storage tank meets the metering sampling conditions, transport the target water sample in the storage tank to the downstream water quality monitoring device according to the target sampling flow rate. S4: After completing the sample supply for a single detection task, stop supplying samples to the backend water quality monitoring device, discharge the residual water sample in the target water path into the sewage discharge path, and close the target water path after the sewage discharge is completed, so that the target water path returns to standby state.

2. The dual mode multiple water sample feeding method of claim 1, wherein, The injection flow rate status includes the average injection flow rate and the flow rate fluctuation level. The average injection flow rate and the flow rate fluctuation level are determined based on the injection flow rate continuously detected within a set detection time window. The flow rate fluctuation level is obtained by dividing the difference between the maximum and minimum injection flow rates within the set detection time window by the average injection flow rate. The direct sample supply conditions are that the average injection flow rate is within the direct sample supply flow rate range, and the flow rate fluctuation does not exceed the allowable fluctuation threshold.

3. The multi-channel water sample dual-mode sampling method according to claim 2, characterized in that, During the bypass direct sampling period, if the sampling flow rate does not meet the direct sampling conditions for a set duration, the sampling to the downstream water quality monitoring device is stopped, the bypass sampling passage is closed and the storage passage is opened, so that the target water sample enters the storage tank. After the storage flow rate meets the metering and sampling conditions, the metering pump re-supplyes the downstream water quality monitoring device and maintains the storage flow metering and sampling status until the single detection task is completed.

4. The multi-channel water sample dual-mode sampling method according to claim 1, characterized in that, The metering and sampling conditions include that the storage flow rate is not lower than the target storage flow rate; the water sample volume required for a single testing task is equal to the product of the target sampling flow rate and the sampling duration plus the pipeline replacement water volume, and the target storage flow rate is the sum of the water sample volume required for a single testing task and the remaining water volume.

5. The multi-channel water sample dual-mode sampling method according to claim 4, characterized in that, The storage flow rate is determined by accumulating the injection flow rate detected during the storage period over time; the metering pump is kept stopped before the storage flow rate reaches the target storage flow rate, and the water supply to the storage tank is stopped and the metering pump is started after the storage flow rate reaches the target storage flow rate; The cumulative sample supply is determined based on the target sample supply flow rate and the operating time of the metering pump, and the metering pump is stopped after the cumulative sample supply reaches the water sample volume required for a single detection task.

6. The multi-channel water sample dual-mode sampling method according to claim 1, characterized in that, The process of discharging the residual water sample in the target waterway into the sewage discharge passage includes: discharging the residual water sample in the storage tank through the sewage discharge branch of the waterway, and discharging the residual water sample in the outlet passage of the target waterway through the common sewage discharge branch; when switching to the next target waterway, after closing the target waterway, the next target water sample flows through the outlet passage of the next target waterway through the common pipe section and is discharged by the common sewage discharge branch; after the cumulative replacement water volume reaches the replacement water volume set according to the volume of the common pipe section, the next target water sample is sent to the back-end water quality monitoring device.

7. The multi-channel water sample dual-mode sampling method according to claim 6, characterized in that, Multiple water sampling waterways are sequentially interlocked, so that the next target waterway is connected to the common sewage branch only after the target waterway is closed, and is connected to the back-end water quality monitoring device after the residual water sample is replaced; during the sampling period, only one of the water sampling waterways is allowed to connect to the back-end water quality monitoring device.

8. A multi-channel water sample dual-mode sampling system, characterized in that, It includes a control unit, a sewage discharge passage, and multiple water sampling channels, each of which is connected to a water sample header. Each water sampling path includes an inlet path, a flow detection component, a bypass sampling path, a storage path, a metering sampling path, and an outlet path. The flow detection component is located in the inlet path. The outlet of the flow detection component is connected to the inlet of the bypass sampling path and the inlet of the storage path, respectively. The outlet of the bypass sampling path is connected to the outlet path. A storage inlet valve and a storage tank are sequentially provided on the storage path. The outlet of the storage tank is connected to the outlet path via a metering sampling path equipped with a metering pump. The sewage discharge path includes a water discharge branch connected to each of the storage tanks and a common sewage branch connected to a common pipe section downstream of each of the outlet paths. Each water discharge branch and the common sewage branch are equipped with a sewage valve. The control unit is connected to the water path selection valve, the flow detection component, the storage inlet valve, the metering pump, and each of the drain valves. It is used to control the opening of the water path selection valve of the target water path among the multiple water sampling water paths according to the sampling command; to control the closing of the storage inlet valve and the opening of the bypass valve of the target water path when the direct sampling conditions are met; to control the closing of the bypass valve and the opening of the storage inlet valve of the target water path when the direct sampling conditions are not met; and to control the metering pump of the target water path to supply samples according to the target sampling flow rate after the sampling is completed, and to stop the sampling and control the discharge valve after the sampling is completed.

9. The multi-channel water sample dual-mode sampling system according to claim 8, characterized in that, The reservoir includes a reservoir body and an inlet, an outlet, an overflow, and a top vent. The inlet is connected to the reservoir inlet valve via a quick-release connection structure. The outlet is connected to the inlet of the metering pump via a quick-release connection structure. The overflow is connected to a vertically extending overflow pipe, and the outlet of the overflow pipe is located at a height corresponding to the highest reservoir position.

10. The multi-channel water sample dual-mode sampling system according to claim 8, characterized in that, The outlet ends of the bypass sampling passage and the metering sampling passage are both connected to the inlet end of the outlet water passage. Check valves and outlet isolation valves are sequentially installed in the outlet water passage along the sampling direction. The common pipe section is connected to the downstream water quality monitoring device via an instrument inlet branch equipped with an instrument inlet valve. The control unit is connected to the water path selection valve, the outlet isolation valve, and the instrument inlet valve, and implements interlock control for each of the water sampling water paths so that when the target water path is connected to the downstream water quality monitoring device, the other water sampling water paths remain isolated, and the next target water sample enters the downstream water quality monitoring device after the replacement of the common pipe section is completed.

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