Residual chlorine sensor accessory and residual chlorine sensor assembly

Abstract

Provided in the present invention is a residual chlorine sensor accessory, comprising a flow cell main body and a cleaning impeller. The sensor accessory can be used in conjunction with a residual chlorine sensor, so that when the residual chlorine sensor operates, the cleaning impeller rotates around the residual chlorine sensor, thereby achieving the technical effect of cleaning the residual chlorine sensor. Further provided in the present invention is a residual chlorine sensor assembly, comprising the residual chlorine sensor accessory and an integrated residual chlorine sensor. The residual chlorine sensor assembly exhibits a self-cleaning feature that avoids the adverse impact of impurities, algae, bubbles and other interference factors on measurement results while also having the technical effects of low flow requirements and simple maintenance.

Description

Residual chlorine sensor accessory and residual chlorine sensor assembly TECHNICAL FIELD

[0001] The present application relates to the field of online detection of residual chlorine in water, and in particular to a residual chlorine sensor accessory capable of imparting self-cleaning function to a residual chlorine sensor, and a residual chlorine sensor assembly with the residual chlorine sensor accessory. BACKGROUND

[0002] Residual chlorine refers to the residual chlorine remaining in water after the water is disinfected or treated with chlorine. Scientific research shows that the residual chlorine can have various adverse effects on human health. Therefore, with the improvement of living standards, more and more people begin to pay attention to the residual chlorine content in water for daily use and drinking water.

[0003] In the prior art, the most common method for detecting residual chlorine is to use an integrated residual chlorine sensor, which includes a pair of measuring electrodes arranged at the detection end and a reference electrode arranged inside the sensor. When the residual chlorine in the water reaches a certain level, the residual chlorine will undergo an oxidation-reduction reaction on the measuring electrodes, thereby generating an electric current between the measuring electrode pairs. By measuring the electric current, the residual chlorine content can be effectively detected. However, in actual use, many factors can interfere with the operation of the measuring electrodes, thereby causing the detection results to deviate from the true value. For example, impurities and algae attached to the measuring electrodes can affect the strength of the generated electric current. In addition, if there are bubbles in the water, the bubbles will also attach to the measuring electrodes and affect the detection results. Therefore, using an integrated residual chlorine sensor to detect residual chlorine has the technical problem of inaccurate measurement results caused by impurities, algae and bubbles.

[0004] To solve the technical problems described above, different solutions have been proposed. One of the chlorine sensing units adopts a design in which the reference electrode and the measuring electrode are arranged separately, wherein the measuring electrode is arranged in a flow cell with a certain number of ceramic beads, and the measuring electrode is driven to rotate at a speed of 600 revolutions per minute by an electric motor. In this way, the ceramic beads can polish the electrode to keep the electrode clean. However, this technical solution not only has high requirements for the service life of the electric motor, but also has the problems of complex structure, high processing cost and high sealing requirement. Moreover, due to the complex process of taking out and loading the ceramic beads, the maintenance cost of this technical solution is also relatively high. In addition, this technical solution is only suitable for designs in which the reference electrode and the measuring electrode are separated, and is not suitable for traditional integrated residual chlorine sensors.

[0005] Chinese patent application 201820848585.6 discloses a residual chlorine analyzer. When in use, a certain number of glass (corundum or other materials) grinding beads are arranged in a flow cell for containing water samples. After the water enters the flow cell, the mechanical structure makes the water flow swirl, driving the grinding beads in the flow cell to move, so that the grinding beads continuously impact the measurement electrode, avoiding impurities adhering to the measurement electrode. This design of using water flow to drive grinding beads often requires a large water flow, which is not necessarily acceptable to regular users. In addition, this design also has maintenance problems.

[0006] Another residual chlorine analyzer adopts a design considering separate arrangement of reference electrode and measurement electrode, and the measurement electrode includes a ring-shaped electrode and an unconventional cylindrical electrode. The rotor in the form of a sheet has a cylindrical electrode as a rotation axis on one side and a bottom surface in contact with the ring-shaped electrode on the other side. In this way, during use, the rotor can rotate by the push of water flow, thereby scraping the working electrode to achieve cleaning. However, this design requires a unique working electrode configuration, which is not suitable for conventional integrated residual chlorine sensors. In addition, this design also has the problems of large flow requirement and difficult maintenance.

[0007] Therefore, it is necessary to develop a residual chlorine sensor accessory capable of endowing a conventional integrated residual chlorine sensor with a self-cleaning function and a residual chlorine sensor assembly with the residual chlorine sensor accessory to solve the above problems.

[0008] SUMMARY

[0009] In order to solve the problem of inaccurate detection results of the integrated residual chlorine sensor in the prior art, the purpose of the present application is to provide a residual chlorine sensor accessory and a residual chlorine sensor assembly capable of solving the above problems.

[0010] To this end, the present application provides a residual chlorine sensor accessory, comprising:

[0011] a flow cell body, an inner part of the flow cell body is provided with a flow cell, the flow cell body is provided with a water inlet and a water outlet communicating with the flow cell, and a top part of the flow cell body is further provided with an opening for a residual chlorine sensor, the opening allowing a measurement end of the residual chlorine sensor to be positioned in the flow cell; and

[0012] A cleaning impeller comprising an impeller body and one or more impeller blades attached to the outer circumference of the impeller body, the impeller body being provided with a vertical hole that preferably extends through the impeller body, the one or more impeller blades extending in the radial direction of the vertical hole; the cleaning impeller being arranged in the flow cell, in use, the measuring end of the residual chlorine sensor being positioned in the vertical hole such that the side wall of the vertical hole is in contact with the measuring electrode of the residual chlorine sensor; the one or more impeller blades being pushed by the water passing through the flow cell to cause the cleaning impeller to rotate around the residual chlorine sensor, thereby cleaning the measuring electrode.

[0013] Furthermore, the present invention also provides a residual chlorine sensor assembly comprising:

[0014] a residual chlorine sensor attachment as described above; and

[0015] a one-piece residual chlorine sensor in the form of a cylinder and provided with at least one measuring electrode in the form of a ring at one end; in use, the measuring end of the one-piece residual chlorine sensor being positioned in the vertical hole of the cleaning impeller such that the side wall of the vertical hole is in contact with the measuring electrode of the one-piece residual chlorine sensor and such that the cleaning impeller rotates around the one-piece residual chlorine sensor.

[0016] The residual chlorine sensor attachment of the present invention can be used together with a conventional one-piece residual chlorine sensor, thereby constituting a residual chlorine sensor assembly. The residual chlorine sensor assembly not only has a self-cleaning function but also requires a relatively small water flow, for example, in some cases only a flow of 15 L / h is required for stable operation. Furthermore, the cleaning impeller can be easily removed, which greatly reduces the difficulty of maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0017] The advantages and features of the present invention will now be described in detail with reference to the accompanying drawings, in which the components are not necessarily drawn to scale, and wherein:

[0018] Fig. 1 shows a front view of a residual chlorine sensor assembly of the present invention, in which the flow cell body, the flow cell top cover and the flow cell bottom cover are cut along a vertical plane to show the internal details.

[0019] Fig. 2 shows a sectional view of the residual chlorine sensor assembly shown in Fig. 1 after being cut along the cutting line A-A.

[0020] Fig. 3 shows a perspective view of a cleaning impeller of the residual chlorine sensor assembly shown in Fig. 1.

[0021] Fig. 4 shows a partial enlarged view of the cleaning impeller shown in Fig. 3, which specifically shows the protrusions of the cleaning impeller.

[0022] Figure 5 shows another enlarged view of the cleaning impeller shown in Figure 3, specifically showing the circular arc structure of the cleaning impeller. DETAILED DESCRIPTION

[0023] In the present specification, the "bottom surface, top surface, vertical" are divided with the orientation shown in Figure 1 as a reference.

[0024] In one aspect, the present application proposes a residual chlorine sensor accessory, comprising:

[0025] a flow cell body, an inner part of which is provided with a flow cell, the flow cell body being provided with a water inlet and a water outlet communicating with the flow cell, and the top of the flow cell body being further provided with an opening for a residual chlorine sensor, the opening allowing the positioning of a measuring end of the residual chlorine sensor in the flow cell; and

[0026] a cleaning impeller, the cleaning impeller comprising an impeller body and one or more impeller blades attached to the outer periphery of the impeller body, the impeller body being provided with a vertical hole penetrating, preferably through, the impeller body, the one or more impeller blades extending in the radial direction of the vertical hole; the cleaning impeller is arranged in the flow cell, in use, the measuring end of the residual chlorine sensor is positioned in the vertical hole, so that the side wall of the vertical hole is in contact with the measuring electrode of the residual chlorine sensor; the one or more impeller blades are pushed by the water in the flow cell to make the cleaning impeller rotate around the residual chlorine sensor, thereby cleaning the measuring electrode. Preferably, the cleaning impeller is not fixed in the flow cell, i.e. the cleaning impeller can move freely in the flow cell. In this way, when used with a residual chlorine sensor, as long as the measuring end of the residual chlorine sensor is positioned in the vertical hole of the cleaning impeller, the cleaning impeller can effectively rotate around the residual chlorine sensor, thereby achieving the purpose of cleaning the residual chlorine sensor.

[0027] In a preferred embodiment of the present application, the flow cell comprises a central cell in the form of a cylinder and an annular space surrounding the central cell, the annular space being concentric with the central cell, a ring wall is provided between the central cell and the annular space, at least one cell passage for introducing water from the annular space into the central cell is provided on the ring wall; the water inlet communicates with the annular space. More preferably, the at least one cell passage comprises three cell passages which are evenly distributed along the circumference of the central cell, and each cell passage extends in a direction tangent to the inner side wall of the ring wall. The annular space enables the water flowing in from the water inlet to be evenly distributed circumferentially, achieving the effect of stabilizing the water pressure. Further, the three cell passages which are evenly distributed at intervals of 120 degrees in the circumferential direction can effectively push the cleaning impeller to rotate from three positions, more greatly utilize the inflowing water, and reduce the flow demand. Still further, the tangential configuration of the cell passage enables the force arm of the water flow incident from the cell passage to be maximized when pushing the cleaning impeller to rotate, which further reduces the flow demand. Still further, the evenly distributed three cell passages enable the thrust on the cleaning impeller to be uniform and balanced. In this way, when the cleaning impeller rotates around the residual chlorine sensor, the cleaning impeller and the residual chlorine sensor can maintain good coaxiality, ensuring the uniformity of cleaning.

[0028] In a preferred embodiment of the present application, the opening for the residual chlorine sensor is in the form of a circular hole, which is concentric with the central pool; the residual chlorine sensor accessory further comprises a flow cell top cover, the bottom surface of which is connected to the top surface of the flow cell body, wherein the flow cell top cover is provided with a sensor cavity for accommodating and positioning the residual chlorine sensor, the sensor cavity is in communication with the opening, and the flow cell top cover is further provided with an overflow port, which is in communication with the sensor cavity and thus serves as the water outlet. More preferably, the sensor cavity is in the form of a stepped hole, the small diameter part of which is used to fix the residual chlorine sensor, and the large diameter part of which has a diameter larger than the fixed residual chlorine sensor; the flow cell top cover is further provided with a vent hole, which is arranged above the overflow port and is in communication with the sensor cavity. In some embodiments, the overflow port is in communication with the large diameter part of the sensor cavity in the form of a stepped hole, so that the water detected by the residual chlorine sensor can be discharged from the overflow port, while the vent hole is also in communication with the large diameter part and is arranged above the overflow port, the function of the vent hole is to guide the gas trapped in the water out, and at the same time to provide the water flowing through the flow cell with ambient atmospheric pressure. Still more preferably, the bottom surface of the flow cell top cover is further provided with a fixing part, which forms a detachable connection with the annular space. In some embodiments, the fixing part is a downwardly extending annular part, which can form a convenient detachable connection structure with the annular space, such as threaded connection, snap connection, tight fit connection, etc. In this way, the flow cell top cover can be conveniently removed, so as to realize the cleaning and maintenance of the annular space and the like position.

[0029] In a preferred embodiment of the present application, the flow cell body is further provided with a flow cell bottom cover opening, which is arranged on the bottom side of the flow cell, the flow cell bottom cover opening is in the form of a threaded hole; the residual chlorine sensor accessory further comprises a flow cell bottom cover, which is configured to be connected with the flow cell bottom cover opening, thereby sealing the flow cell bottom cover opening. More preferably, the flow cell bottom cover is in the form of a stepped shaft, the small diameter part of which has a thread for threaded connection with the flow cell bottom cover opening. In this way, the impeller maintenance can be directly taken out by unscrewing the flow cell bottom cover, which greatly reduces the difficulty of maintenance. More preferably, a stop valve and a stop valve mounting port provided on the flow cell bottom cover are further included, the stop valve mounting port is in communication with the flow cell, so that the sewage can be discharged by opening the stop valve. The provision of the stop valve makes it possible to realize sewage discharge without removing the flow cell bottom cover, further enhancing the convenience of maintenance.

[0030] In a preferred embodiment of the present application, the cleaning impeller comprises an impeller body in the form of a cylinder, which is concentric with the vertical hole, and the impeller blades are evenly distributed along the circumference of the impeller body on the circumferential surface of the impeller body. More preferably, the cleaning impeller has six impeller blades. Six impeller blades evenly distributed along the circumference make full use of the incident water flow, reducing the flow requirement.

[0031] In a preferred embodiment of the present application, at least one protrusion is provided on the top surface of each of the impeller blades. The protrusion reduces the frictional contact surface between the cleaning impeller and the inner wall of the flow tank, reduces the friction generated during rotation, and reduces the flow requirement.

[0032] In a preferred embodiment of the present application, the side wall of the vertical hole has a plurality of circular arc structures, wherein each of the circular arc structures is configured to contact the measurement electrode of the residual chlorine sensor at least at one point. The contact between the circular arc structure and the measurement electrode of the residual chlorine sensor can effectively clean the measurement motor, for example, in a manner similar to scraping. In some embodiments, in order to achieve thorough cleaning, the contact is a line contact across at least one measurement electrode. The provision of the circular arc structure reduces the rotational friction of the cleaning impeller, enhances the wear resistance of the cleaning impeller, and improves the service life. In addition, the provision of the circular arc structure ensures that the measurement electrode can be in contact with the water to be measured at any time, improving the accuracy of the measurement. It should be understood that the circular arc structure described in the present application should be understood in a broad sense, and can refer to any type of protrusion or projection extending from a base surface (such as the side wall of the vertical hole).

[0033] In a preferred embodiment of the present application, the cleaning impeller is made of a material with a density lower than water, preferably a polymer. Since the density of the cleaning impeller is lower than that of water, the cleaning impeller can float in the flow tank, which further reduces the friction during rotation of the cleaning impeller. In addition, in the case of being provided with the protrusions described above, the floating of the cleaning impeller can maximize the friction reduction benefit brought by the provision of the protrusions.

[0034] In a preferred embodiment of the present application, a impeller speed detection mechanism for detecting the rotation speed of the cleaning impeller is further included. More preferably, the impeller speed detection mechanism comprises a Hall sensor, a Hall sensor mounting port provided in the flow tank body such that the sensing surface of the Hall sensor is parallel to the rotation axis of the impeller body, and a magnet provided on the impeller blade for marking the rotation of the cleaning impeller. The impeller speed detection mechanism can detect the rotation speed of the cleaning impeller, thereby determining the working state of the residual chlorine sensor.

[0035] In another aspect, the present application also provides a residual chlorine sensor assembly, comprising:

[0036] The residual chlorine sensor accessory as described above; and

[0037] The integral residual chlorine sensor is in the form of a cylinder and is provided with at least one measuring electrode in the form of a ring at one end; in use, the measuring end of the integral residual chlorine sensor is positioned in the vertical hole of the cleaning impeller so that the side wall of the vertical hole is in contact with the measuring electrode of the integral residual chlorine sensor and so that the cleaning impeller rotates around the integral residual chlorine sensor. More preferably, the measuring electrode is a pair of platinum rings and the integral residual chlorine sensor is further provided with a reference electrode. The residual chlorine sensor accessory disclosed herein is suitable for use in combination with a conventional integral residual chlorine sensor to form a residual chlorine sensor assembly with automatic cleaning function. The residual chlorine sensor assembly has the characteristics of low flow requirement, easy cleaning and maintenance.

[0038] The various components of the residual chlorine sensor accessory of the present application can be made of corrosion-resistant, especially chlorine-resistant, plastic or metal materials and prepared by conventional processing methods. If plastic materials are used, the conventional processing methods are injection molding, molding, extrusion molding, etc. If metal materials are used, the conventional processing methods are machining, casting, stamping, bending, etc. Preferably, the cleaning impeller is made of a material with a density lower than water, such as a polymer material. More preferably, the flow cell body is made of PMMA (polymethyl methacrylate) material. The integral residual chlorine sensor in the residual chlorine sensor assembly of the present application is a sensor type commonly known in the prior art.

[0039] In the most basic case, the residual chlorine sensor accessory of the present application only has the features of water inlet, water outlet, flow cell body, cleaning impeller, etc., which can achieve the technical effect of water-driven impeller rotation to clean the residual chlorine sensor. Preferably, the residual chlorine sensor accessory of the present application also has the features of flow cell upper cover, flow cell lower cover, protrusion, circular arc structure, etc., which reduce the flow requirement and maintenance difficulty.

[0040] The specific embodiments of the present application are described below in conjunction with the accompanying drawings, but the present application is not limited by these specific embodiments. In the illustrated embodiments, the residual chlorine sensor is a known product, the flow cell body is made of PMMA material, and the cleaning impeller is made of plastic. However, it is understood that they can be made of other materials.

[0041] Figure 1 shows a front view of the residual chlorine sensor assembly of the present application, wherein the flow cell body, the flow cell top cover and the flow cell bottom cover are cut along a vertical plane to show the internal details. As shown in Figure 1, the residual chlorine sensor assembly as a whole is denoted by reference numeral 100. The residual chlorine sensor assembly 100 comprises a flow cell body 101, a flow cell top cover 102, a flow cell bottom cover 103, a cleaning impeller 104, an integrated residual chlorine sensor 105, a Hall sensor 106, and a stop valve 107. The top surface of the flow cell body 101 is provided with an opening 101A in the form of a circular hole, and the bottom surface is provided with a flow cell bottom cover opening 101B in the form of a threaded hole. The flow cell bottom cover 103 is in the form of a stepped shaft, the small diameter portion of which is threaded for threaded connection with the flow cell bottom cover opening 101B, so that the flow cell bottom cover 103 is fixed on the bottom surface of the flow cell body 101. The flow cell bottom cover 103 is further provided with a stop valve mounting port 103A, which is in communication with the flow cell, and in which the stop valve 107 is mounted. The flow cell top cover 102 comprises a sensor chamber 102A for accommodating and positioning the integrated residual chlorine sensor 105, the sensor chamber 102A is in the form of a stepped hole and is concentric with the opening 101A, so that the measurement end of the integrated residual chlorine sensor 105 can extend into the flow cell body 101 through the flow cell top cover 102. The flow cell top cover 102 further comprises an air vent hole 102B and an overflow port 102C, which are respectively in communication with the large diameter segment of the sensor chamber 102A. In addition, the flow cell top cover 102 further comprises a fixing portion 102D extending downward from the bottom surface of the flow cell top cover 102, which forms a detachable connection with the flow cell body 101, so that the flow cell top cover 102 is fixed on the top surface of the flow cell body 101. The integrated residual chlorine sensor 105 is generally in the form of a cylinder, the bottom end of which is the measurement end, and two annular platinum measurement electrodes are provided on the measurement end. The cleaning impeller 104 is arranged in the flow cell in the flow cell body 101, and the cleaning impeller 104 can rotate around the integrated residual chlorine sensor 105. In addition, the Hall sensor 106 for detecting the rotational speed of the cleaning impeller 104 is also arranged on the flow cell body 101.

[0042] Figure 2 shows a sectional view of the residual chlorine sensor assembly 100 shown in Figure 1 after being cut along the cutting line A-A. As shown in Figure 2, the flow cell of the flow cell body 101 includes a central cell 101D in the form of a cylinder and an annular space 101E surrounding the central cell 101D, the annular space 101E being concentric with the central cell 101D. The cleaning impeller 104 is disposed in the central cell 101D and is not fixed with the central cell 101D, i.e. the cleaning impeller 104 is able to rotate freely around the integrated residual chlorine sensor 105. A ring wall is disposed between the central cell 101D and the annular space 101E, and three cell passages 101F for introducing water from the annular space 101E into the central cell 101D are disposed on the ring wall. The cell passages 101F are evenly spaced at intervals of 120 degrees around the circumference of the central cell 101D, and each cell passage 101F extends in a direction tangent to the inner side wall of the ring wall. The flow cell body 101 further includes a water inlet 101C which communicates with the annular space 101E so as to introduce the water to be measured into the flow cell. It should be understood that although Figure 2 does not show it, the annular space 101E can constitute the detachable connection with the fixed part 102D shown in Figure 1. Furthermore, as shown in Figure 2, the sensing surface 106A of the Hall sensor 106 faces the cleaning impeller 104, i.e. the sensing surface 106A is parallel to the rotation axis of the cleaning impeller 104. This enables the Hall sensor 106 to effectively detect the rotational speed of the cleaning impeller 104.

[0043] Figure 3 shows a perspective view of the cleaning impeller 104 of the residual chlorine sensor assembly shown in Figure 1. As shown in Figure 3, the cleaning impeller 104 includes a cleaning impeller body 104A, impeller blades 104B, a vertical hole 104C, protrusions 104D, a circular arc structure 104E, and a magnet 104F. The cleaning impeller body 104A is concentric with the vertical hole 104C, and six impeller blades 104B are evenly distributed around the circumference of the cleaning impeller body 104A. One protrusion 104D is respectively disposed on the upper surface of each impeller blade 104B. The circular arc structure 104E is disposed on the side wall of the vertical hole 104C and is evenly distributed around the circumference of the vertical hole 104C. The magnet 104F is disposed on the side surface of one of the impeller blades 104B for marking the rotation of the cleaning impeller 104.

[0044] Figure 4 shows a partial enlarged view of the cleaning impeller 104 shown in Figure 3, which specifically shows the protrusions 104D of the cleaning impeller 104. As shown in Figure 4, the protrusions 104D are hemispherical protrusions extending upward from the top surface of the cleaning impeller 104, and the protrusions 104D enable the cleaning impeller 104 to make point contact rather than surface contact with the top surface of the central cell 101D shown in Figure 2, which greatly reduces the rotational friction of the cleaning impeller 104 during operation.

[0045] Figure 5 shows another enlarged view of the cleaning impeller 104 shown in Figure 3, which specifically shows the circular arc structure 104E of the cleaning impeller 104. It should be understood that the circular arc structure 104E of the cleaning impeller 104, when in use, forms a line contact with the sensor 105 shown in Figure 1 across two annular platinum measuring electrodes. In this way, when the cleaning impeller 104 rotates, the circular arc structure 104E can constantly scrape the measuring electrodes, thereby achieving cleaning of the sensor.

[0046] Although Figures 1 and 2 show the case of a residual chlorine sensor, i.e. the case of a residual chlorine sensor assembly, the present application also includes the case of a residual chlorine sensor without a residual chlorine sensor, i.e. the case of a residual chlorine sensor accessory. In the case of not including a residual chlorine sensor, the residual chlorine sensor accessory can be sold as a stand-alone product, and the user can install the purchased residual chlorine sensor accessory to an existing residual chlorine sensor. The above are all within the protection scope of the present application.

Claims

1. A residual chlorine sensor attachment characterized by, Comprising: a flow cell body, an inside of which is provided with a flow cell, the flow cell body being provided with a water inlet and a water outlet which communicate with the flow cell, and the top of the flow cell body being further provided with an opening for a residual chlorine sensor, the opening allowing the positioning of a measuring end of the residual chlorine sensor in the flow cell; and a cleaning impeller, the cleaning impeller comprising an impeller body and one or more impeller blades attached to the outer periphery of the impeller body, the impeller body being provided with a vertical hole which penetrates, preferably through, the impeller body, and the one or more impeller blades extending in the radial direction of the vertical hole; the cleaning impeller being disposed in the flow cell, in use, the measuring end of the residual chlorine sensor being positioned in the vertical hole, such that the side wall of the vertical hole is in contact with the measuring electrode of the residual chlorine sensor; the one or more impeller blades being pushed by the water passing through the flow cell to rotate the cleaning impeller around the residual chlorine sensor, thereby cleaning the measuring electrode. The cleaning impeller is not fixed in the flow cell.

2. The residual chlorine sensor attachment of claim 1, wherein, The flow cell comprises a central cell in the form of a cylinder and an annular space surrounding the central cell, the annular space being concentric with the central cell, and a ring wall being provided between the central cell and the annular space, and at least one cell passage for introducing water from the annular space into the central cell being provided on the ring wall; the water inlet communicating with the annular space.

3. A residual chlorine sensor attachment according to claim 1 or 2, characterised in that, The at least one cell passage comprises three cell passages which are uniformly distributed along the circumference of the central cell, and each cell passage extends in a direction tangent to the inner side wall of the ring wall.

4. The residual chlorine sensor attachment of claim 3, wherein, The opening for the residual chlorine sensor is in the form of a circular hole, concentric with the central cell; 5. A residual chlorine sensor attachment according to claim 3 or 4, characterised in that, The residual chlorine sensor accessory further comprises a flow cell top cover, the bottom surface of which is connected to the top surface of the flow cell body, wherein the flow cell top cover is provided with a sensor chamber for accommodating and positioning a residual chlorine sensor, the sensor chamber communicating with the opening, and the flow cell top cover is further provided with an overflow port which communicates with the sensor chamber to serve as the water outlet. The sensor chamber is in the form of a stepped hole, the small-diameter part of which is used to fix the residual chlorine sensor, and the large-diameter part of which has a diameter larger than the fixed residual chlorine sensor; the flow cell top cover is further provided with a vent hole, which is arranged above the overflow port and communicates with the sensor chamber.

6. The residual chlorine sensor attachment of claim 5, wherein, The bottom surface of the flow cell top cover is further provided with a fixing part which forms a detachable connection with the annular space.

7. A residual chlorine sensor attachment according to claim 5 or 6, characterised in that, The opening for the residual chlorine sensor is in the form of a circular hole; 8. The residual chlorine sensor attachment according to claim 1 or 2, characterized in that The residual chlorine sensor accessory further comprises a flow cell top cover, the bottom surface of which is connected to the top surface of the flow cell body, wherein the flow cell top cover is provided with a sensor chamber for accommodating and positioning a residual chlorine sensor, the sensor chamber communicating with the opening, and the flow cell top cover is further provided with an overflow port which communicates with the sensor chamber to serve as the water outlet. ​ 9. The residual chlorine sensor attachment of claim 8, wherein, The sensor chamber is in the form of a stepped hole, the small diameter part of which is used to fix the residual chlorine sensor, and the large diameter part of which has a diameter larger than the fixed residual chlorine sensor; the flow cell top cover is further provided with a vent hole arranged above the overflow port and in communication with the sensor chamber.

10. The residual chlorine sensor attachment according to any one of claims 1 to 9, characterized in that The flow cell body is further provided with a flow cell bottom cover opening in the form of a threaded hole arranged at the bottom side of the flow cell. The residual chlorine sensor accessory further comprises a flow cell bottom cover configured to be connected with the flow cell bottom cover opening to seal the flow cell bottom cover opening.

11. The residual chlorine sensor attachment of claim 10, wherein, The flow cell bottom cover is in the form of a stepped shaft, the small diameter part of which is threaded for threaded connection with the flow cell bottom cover opening.

12. The residual chlorine sensor attachment of any one of claims 1 to 11, wherein, A stop valve and a stop valve mounting port provided on the flow cell bottom cover are further included, the stop valve mounting port being in communication with the flow cell so that sewage can be discharged by opening the stop valve.

13. The residual chlorine sensor attachment of any one of claims 1 to 12, wherein, The cleaning impeller comprises an impeller body in the form of a cylinder concentric with the vertical hole, and the impeller blades are evenly distributed on the circumferential surface of the impeller body along the circumferential direction of the impeller body.

14. The residual chlorine sensor attachment of claim 13, wherein, The cleaning impeller has six impeller blades.

15. The residual chlorine sensor attachment of any one of claims 1 to 14, wherein, At least one protrusion is arranged on the top surface of each impeller blade.

16. The residual chlorine sensor attachment of any one of claims 1 to 15, wherein, The side wall of the vertical hole has a plurality of circular arc structures, each of which is configured to contact the measuring electrode of the residual chlorine sensor at least at one point.

17. The residual chlorine sensor attachment of any one of claims 1 to 16, wherein, The cleaning impeller is made of a material with a density lower than water, preferably a polymer.

18. The residual chlorine sensor attachment of any one of claims 1 to 17, wherein, A impeller speed detection mechanism for detecting the rotating speed of the cleaning impeller is further included.

19. The residual chlorine sensor attachment of claim 18, wherein, The impeller speed detection mechanism comprises a Hall sensor; a Hall sensor mounting port arranged in the flow cell body so that the sensing surface of the Hall sensor is parallel to the rotation axis of the impeller body; a magnet arranged on the impeller blade to mark the rotation of the cleaning impeller.

20. A residual chlorine sensor assembly characterized by, comprises: the residual chlorine sensor accessory according to any one of claims 1 to 19; and an integrated residual chlorine sensor in the form of a cylinder and provided with at least one ring-shaped measuring electrode at one end; in use, the measuring end of the integrated residual chlorine sensor is positioned in the vertical hole of the cleaning impeller so that the side wall of the vertical hole contacts the measuring electrode of the integrated residual chlorine sensor, and the cleaning impeller rotates around the integrated residual chlorine sensor.

21. The residual chlorine sensor assembly of claim 20, wherein, The measuring electrode is a pair of platinum gold rings, and the integrated residual chlorine sensor is further provided with a reference electrode.

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