A light impurity accident protection sensor

Abstract

The present application belongs to the field of uranium enrichment technology, and specifically relates to a light impurity accident protection sensor. The sensor has a partition in the middle of the cavity, which is divided into two chambers that are not connected to each other; multiple spiral sensitive elements are evenly distributed in the two chambers, and the resistance values ​​of the spiral sensitive elements in the two chambers are equal; a porous screen is sleeved on the outside of each chamber, and a flow guide cover is sleeved on the outside of the porous screen, and the porous screen and the flow guide cover on the outside of the two chambers are not connected; each flow guide cover is provided with a gas input channel and a gas output channel connected to the corresponding chamber, and a comparison gas and a light impurity gas are input respectively; multiple spiral sensitive elements are connected to the circuit board, so as to realize light impurity accident protection according to the resistance change of the spiral sensitive element in the chamber. The present application converts the change in thermal conductivity caused by the change in the components in the mixed gas into the change in the resistance of the spiral sensitive element, thereby realizing the measurement of the light impurity gas content.

Description

Technical Field

[0001] The present application belongs to the technical field of uranium enrichment, and specifically relates to a light impurity accident protection sensor. Background Art

[0002] In the field of nuclear industry production in my country, nuclear safety factors are of vital importance. Strict requirements are imposed on the measurement and control instruments used in the process of production. They must have stable and reliable performance and a long service life. We have developed a light impurity accident protection sensor. However, in actual use, we found that after the sensor has been running for a long time, the porous screen parts around the sensitive element have decreased permeability due to the attachment of aerosol substances, which affects heat dissipation, resulting in a decrease in sensor performance. The permeability of the porous screen parts is very important, which determines the interactive changes of fluid in and out, and has a significant impact on the output signal amplitude and response time of the sensor. Summary of the invention

[0003] The purpose of this application is to provide a light impurity accident protection sensor to solve the problem in the prior art that the permeability of the porous screen parts is reduced due to the attachment of aerosol substances, which affects the heat dissipation and leads to the performance degradation of the sensor.

[0004] Technical solution to achieve the purpose of this application:

[0005] The embodiment of the present application provides a light impurity accident protection sensor, the sensor comprising: a spiral sensitive element, a cavity, a porous screen, a flow guide cover and a circuit board;

[0006] A partition is provided in the middle of the cavity, dividing it into two chambers that are not connected to each other; a plurality of spiral sensitive elements are evenly distributed in the two chambers, and the resistance values ​​of the spiral sensitive elements in the two chambers are equal;

[0007] The outer side of each chamber is provided with a porous screen, and the outer side of the porous screen is provided with a flow guide cover, and the porous screens and flow guide covers on the outer sides of the two chambers are not connected;

[0008] Each flow guide cover is provided with a gas input channel and a gas output channel connected to the corresponding chamber, and the comparison gas and the light impurity gas are input respectively;

[0009] A plurality of spiral-shaped sensitive elements are connected to the circuit board so as to determine the content of the light impurity gas according to the resistance change of the spiral-shaped sensitive elements in the chamber, thereby realizing light impurity accident protection.

[0010] Optionally, the porous screen comprises two hollow cylinders which are sleeved together, the hollow cylinders are evenly provided with a plurality of ventilation holes, and a porous screen bottom cover is welded to the bottom end; the two hollow cylinders have different heights.

[0011] Optionally, the sensor further includes: a sensor body;

[0012] The deflector cover is fixed to the outer end surface of the lower part of the sensor body by a second screw; the upper ends of the two hollow cylinders are welded and fixed by a "Z"-shaped fixing plate, and the upper end of the higher hollow cylinder is welded to the fixing joint and fixedly connected to the outer end surface of the lower part of the sensor body.

[0013] Optionally, the sensor further comprises: a sealing flange, a bakelite pad, a sealing rubber pad and a positioning seat;

[0014] The positioning seat, the sealing rubber pad and the bakelite pad are installed in the sensor body from bottom to top; the sealing flange is fixed to the upper section of the sensor body by bolts, and is used to squeeze the positioning seat, the sealing rubber pad and the bakelite pad;

[0015] The positioning seat, the sealing rubber pad and the bakelite pad are all provided with mounting holes for passing a plurality of spiral sensitive element connecting wires. The circuit board is fixed on the upper end of the sealing flange and connected with the connecting wires of the spiral sensitive elements.

[0016] Optionally, an insulating column is installed in the mounting hole; the lead-out electrode passes through the lower end of the insulating column and is connected to the spiral sensitive element, and the upper end is connected to the circuit board;

[0017] The exposed part of the lead-out electrode welding wire is equipped with an insulating sleeve.

[0018] Optionally, there are eight spiral sensitive elements in total; four spiral sensitive elements are respectively arranged in each cavity, and every two adjacent spiral sensitive elements are connected in series.

[0019] Optionally, the sensor further comprises: a shaft, a "U"-shaped fixed pole, a semicircular fixed sheet and a limit clamp ring;

[0020] The upper end of the shaft is connected by threads and installed on the positioning seat; there are holes on the semicircular fixing plate, which is installed on the lower end of the shaft. Each semicircular fixing plate has holes, and a "U"-shaped fixed pole is installed in every two adjacent holes. The lower ends of every two adjacent spiral sensitive elements are respectively connected to the two ends of the "U"-shaped fixed pole.

[0021] Optionally, a cavity bottom cover is installed at the bottom of the cavity; and a "dish-shaped" rubber sealing pad is installed at the lower end of the positioning seat.

[0022] Optionally, the sensor further comprises: a plug fixing plate, a first support, a second support and a housing;

[0023] The lower end of the second pillar is fixed on the sealing flange, the upper end of the second pillar is mounted with a circuit board, and the upper end of the circuit board is mounted with the first pillar; the plug fixing plate is connected to the first pillar by a third screw;

[0024] The outer shell is sleeved on the outer side of the circuit board and fixed on the sensor body by the fifth screw; a plug is arranged on the outer shell, the circuit board is connected with the plug, and the plug is fixed on the top of the plug fixing plate by the first screw.

[0025] Optionally, the sensor further comprises: a flange;

[0026] The groove of the flange faces downward and is installed on the step of the sensor body.

[0027] The beneficial technical effects of this application are:

[0028] The embodiment of the present application provides a light impurity accident protection sensor, which includes: a spiral sensitive element, a cavity, a porous screen, a flow guide cover and a circuit board; a partition is arranged in the middle of the cavity, dividing it into two chambers that are not connected to each other; a plurality of spiral sensitive elements are evenly distributed in the two chambers, and the resistance values ​​of the spiral sensitive elements in the two chambers are equal; a porous screen is sleeved on the outside of each chamber, and a flow guide cover is sleeved on the outside of the porous screen, and the porous screen and the flow guide cover on the outside of the two chambers are not connected; each flow guide cover is provided with a gas input channel and a gas output channel connected to the corresponding chamber, and a comparison gas and a light impurity gas are input respectively; a plurality of spiral sensitive elements are connected to the circuit board, so as to determine the content of the light impurity gas according to the resistance change of the spiral sensitive element in the chamber, so as to realize light impurity accident protection. The embodiment of the present application provides a light impurity accident protection sensor, which adopts the method of thermal conduction analysis, converts the change of the total thermal conductivity caused by the change of the component to be analyzed in the mixed gas into the change of the resistance of the sensor sensitive element, and adopts a bridge circuit to realize the measurement of the light impurity gas content. It can be used as a special sensor in the field of uranium enrichment engineering. It is used to detect the content of light impurity gas in the process system, and the sensor generates a DC voltage pulse signal. When the light impurity content exceeds the allowable range specified in the process operation, the signal generated by the sensor will immediately send out an alarm message through the automatic control system and control the corresponding actuator action, forming an important light impurity accident protection for the main process equipment. The performance of the sensor is inseparable from the process operation conditions, and plays an important role in product quality control and the safe and continuous operation of the host.

[0029] A light impurity accident protection sensor provided in the embodiment of the present application has a wide applicable flow range, enhanced airflow permeability of the porous screen component structure, and strong corrosion resistance; the structural design of the sensor working chamber and compensation chamber parts is improved; and the structure of the sensor is easy to process, the material is easy to obtain, and the service life is longer; and it has been proven through laboratory performance tests and engineering applications that the performance is reliable and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A schematic diagram of the structure of a light impurity accident protection sensor provided in an embodiment of the present application;

[0031] Figure 2 A cross-sectional view of a light impurity accident protection sensor provided in an embodiment of the present application;

[0032] Figure 3 A circuit schematic diagram of a light impurity accident protection sensor provided in an embodiment of the present application.

[0033] In the figure:

[0034] 1- spiral sensitive element; 2- cavity; 3- porous screen; 4- guide cover; 5- first screw; 6- plug fixing plate; 7- first pillar; 8- circuit board; 9- first variable resistor; 10- second pillar; 11- bolt; 12- sealing flange; 13- installation mark; 14- bakelite pad; 15- rubber pad; 16- positioning seat; 17- insulating column; 18- second screw; 19- fixed joint; 20- third screw; 21- shell; 22- fourth screw; 23- second variable resistor; 24- insulating sleeve; 25- fifth screw; 26- sensor body; 27- shaft; 28- "U" shaped fixed pole; 29- semicircular fixed plate; 30- limit clamp; 31- cavity bottom cover; 32- porous screen bottom cover; 33- lead pole; 34- "Z" shaped fixed plate; 35- flange; 36- "disc-shaped" rubber sealing pad; X1- plug. DETAILED DESCRIPTION

[0035] In order to make those skilled in the art better understand the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described below are only a part of the embodiments of the present application, not all. Based on the embodiments recorded in the present application, all other embodiments obtained by those skilled in the art without paying creative work are within the scope of protection of the present application.

[0036] See also Figure 1 , which is a schematic diagram of the structure of a light impurity accident protection sensor provided in an embodiment of the present application.

[0037] A light impurity accident protection sensor provided in an embodiment of the present application includes: a spiral sensitive element 1, a cavity 2, a porous screen 3, a flow guide cover 4 and a circuit board 8;

[0038] A partition is provided in the middle of the cavity 2, dividing it into two chambers that are not connected to each other; a plurality of spiral sensitive elements 1 are evenly distributed in the two chambers, and the resistance values ​​of the spiral sensitive elements 1 in the two chambers are equal;

[0039] A porous screen 3 is sleeved on the outside of each chamber, and a flow guide cover 4 is sleeved on the outside of the porous screen 3. The porous screens 3 and flow guide covers 4 on the outsides of the two chambers are not connected.

[0040] Each flow guide cover 4 is provided with a gas input channel and a gas output channel connected to the corresponding chamber, and the comparison gas and the light impurity gas are input respectively;

[0041] A plurality of spiral-shaped sensitive elements 1 are connected to the circuit board 8 so as to determine the content of light impurities in the gas according to the resistance change of the spiral-shaped sensitive elements 1 in the chamber, thereby realizing light impurity accident protection.

[0042] It can be understood that when the light impurity gas component changes, its thermal conductivity also changes accordingly. Compared with the comparison gas, the resistance of the spiral sensitive element 1 changes. The change in the total thermal conductivity caused by the change in the component to be analyzed in the mixed gas is converted into a change in the resistance of the sensor sensitive element. The content of the light impurity gas can be determined by the resistance change of the spiral sensitive element 1 in the chamber to achieve light impurity accident protection.

[0043] In one example, the porous screen 3 may include two hollow cylinders nested together, wherein the hollow cylinders are evenly provided with a plurality of vent holes, and a porous screen bottom cover 32 is welded to the bottom end; the two hollow cylinders have different heights.

[0044] As an example, Figure 1 As shown, the height of the inner hollow cylinder is higher than the height of the outer hollow cylinder.

[0045] In some possible implementations of the embodiments of the present application, the sensor may further include: a sensor body 26;

[0046] The deflector 4 is fixed to the outer end surface of the lower part of the sensor body 26 by the second screw 18; the upper ends of the two hollow cylinders are welded and fixed by a "Z"-shaped fixing plate 34, and the upper end of the higher hollow cylinder is welded to the fixing joint 19 and fixedly connected to the outer end surface of the lower part of the sensor body 26.

[0047] In some possible implementations of the embodiments of the present application, the sensor may further include: a sealing flange 12, a bakelite pad 14, a sealing rubber pad 15 and a positioning seat 16;

[0048] The positioning seat 16, the sealing rubber pad 15 and the bakelite pad 14 are installed in the sensor body 26 from bottom to top; the sealing flange 12 is fixed to the upper section of the sensor body 26 by bolts 11, and is used to squeeze the positioning seat 16, the sealing rubber pad 15 and the bakelite pad 14;

[0049] The positioning seat 16 , the sealing rubber pad 15 and the bakelite pad 14 are all provided with mounting holes for passing the connecting wires of the multiple spiral sensitive elements 1 . The circuit board 8 is fixed to the upper end of the sealing flange 12 and connected to the connecting wires of the spiral sensitive elements 1 .

[0050] In one example, an insulating column 17 is installed in the mounting hole; the lead-out pole 33 passes through the lower end of the insulating column 17 and is connected to the spiral sensitive element 1, and the upper end is connected to the circuit board 8;

[0051] The exposed portion of the lead-out electrode 33 welding wire is provided with an insulating sleeve 24 .

[0052] In another example, there are eight spiral sensitive elements 1 in total; four spiral sensitive elements 1 are respectively arranged in each cavity, and every two adjacent spiral sensitive elements 1 are connected in series.

[0053] In some possible implementations of the present application, such as Figure 1 and 2 As shown, the sensor further includes: a shaft 27, a "U"-shaped fixed pole 28, a semicircular fixed sheet 29 and a limiting snap ring 30;

[0054] The upper end of the shaft 27 is connected by a thread and installed on the positioning seat 16; the semicircular fixing plate 29 has a hole and is installed on the lower end of the shaft 27. Each semicircular fixing plate 29 has a hole, and a "U"-shaped fixed pole 28 is installed in every two adjacent holes. The lower ends of every two adjacent spiral sensitive elements 1 are respectively connected to the two ends of the "U"-shaped fixed pole 28.

[0055] In one example, a cavity bottom cover 31 is installed at the bottom of the cavity 2 ; and a “dish-shaped” rubber sealing pad 36 is installed at the lower end of the positioning seat 16 .

[0056] In some possible implementations of the embodiments of the present application, the sensor further includes: a plug fixing plate 6, a first support 7, a second support 10 and a housing 21;

[0057] The lower end of the second support 10 is fixed on the sealing flange 12, the upper end of the second support 10 is mounted with a circuit board 8, and the upper end of the circuit board 8 is mounted with a first support 7; the plug fixing plate 6 is connected to the first support 7 by a third screw 20;

[0058] The housing 21 is sleeved on the outside of the circuit board 8 and fixed to the sensor body 26 by the fifth screw 25 ; a plug X1 is provided on the housing 21 , the circuit board 8 is connected to the plug X1 , and the plug X1 is fixed to the top of the plug fixing plate 6 by the first screw 5 .

[0059] In one example, the sensor further includes: a flange 35;

[0060] The groove of the flange 35 faces downward and is mounted on the step of the sensor body 26. The first variable resistor 9 and the second variable resistor 23 are fixed on the circuit board.

[0061] A light impurity accident protection sensor provided by an embodiment of the present application is described in detail below with reference to a specific example.

[0062] A light impurity accident protection sensor provided in an embodiment of the present application includes: a total of 8 spiral sensitive elements 1 with the same characteristics, a total of 8 lead-out poles 33, a total of 4 "U"-shaped fixed poles 28, a total of 2 semicircular fixing plates 29, a total of 4 limiting snap rings 30, and a total of 2 shafts 27; in the lower structure of the sensor, the semicircular fixing plate 29 has a hole and is installed on the lower end of the shaft 27, and the upper and lower surfaces where the shaft 27 is connected to the semicircular fixing plate 29 are installed through the shaft 27 to limit the semicircular fixing plate 29, and each of the 4 holes on each semicircular fixing plate 29 has a "U"-shaped fixed pole 28 installed in every 2 adjacent holes, and the upper end of the shaft 27 is connected by a thread and installed on the positioning seat 16, and there are 2 such identical structural parts, and the plane ends of the two semicircular fixing plates 29 are close together, and the outer shape is a truncated cone cut in the middle.

[0063] One end of the first spiral sensitive element 1 is fixed on the first lead-out pole 33, and the other end is fixed on one pole of the "U"-shaped fixed pole 28. One end of the second spiral sensitive element 1 is fixed on the second lead-out pole 33, and the other end is fixed on the other pole of the "U"-shaped fixed pole 28. Through such a fixing method, the first spiral sensitive element 1 and the second spiral sensitive element 1 are connected in series to form a first new sensitive element. Similarly, in the same connection method, the third spiral sensitive element 1 and the fourth spiral sensitive element 1 are connected in series to form a second new sensitive element, the fifth spiral sensitive element 1 and the sixth spiral sensitive element 1 are connected in series to form a third new sensitive element, and the seventh spiral sensitive element 1 and the eighth spiral sensitive element 1 are connected in series to form a fourth new sensitive element. These four new sensitive elements are compensation sensitive elements R5 and R8 and working sensitive elements R6 and R7 respectively. After the positions of the eight spiral sensitive elements 1 are fixed, the spacing is the same, they are parallel to each other, and are parallel to the axis 27.

[0064] The cavity 2 is cylindrical in structure, with a partition in the middle, and is divided into two chambers of equal volume by the partition, namely, a working chamber and a compensation chamber. There are holes on the walls of the two chambers to facilitate the connection between the chamber and the outside. The bottom of the cavity 2 is installed with a cavity bottom cover 31; a "disc-shaped" rubber sealing pad 36 is installed at the lower end of the positioning seat 16. The cavity 2 with a partition in the middle passes through two semicircular fixing pieces 29, reaches the lower end of the positioning seat 16, and contacts with the "disc-shaped" rubber sealing pad 36, and is fixed through the threaded fixing joint on the upper part of the porous screen 3. The head 19 cooperates with the sensor body 26 and is fixed by spinning; the porous screen 3 is composed of two cylinders of different diameters and heights, and there are holes on the cylinders. The bottom ends of the two cylinders are welded with the porous screen bottom cover 32. Due to the different heights between the two cylinders, they are welded and fixed by three "Z"-shaped fixing plates 34. The three "Z"-shaped fixing plates 34 are evenly distributed at 120°, and the upper end of the inner cylinder is welded to the threaded fixing joint 19; the deflector 4 is fixed to the outer end surface of the lower part of the sensor body 26 by three second screws 18.

[0065] In the upper structure of the sensor, the groove of the flange 35 faces downward and is installed on the step of the sensor body 26; the three parts of the positioning seat 16, the sealing rubber pad 15 and the bakelite pad 14 are installed in the sensor body 26 in sequence, and each of the positioning seat 16, the sealing rubber pad 15 and the bakelite pad 14 has 8 holes. During installation, it must be ensured that the 8 holes on the three parts correspond to each other, and the centers of the holes remain coaxial. Insulating columns 17 are installed in the 8 holes of the positioning seat 16; 8 lead-out poles 33 penetrate the holes of the three parts of the positioning seat 16, the sealing rubber pad 15 and the bakelite pad 14, play a connecting role, and connect the upper and lower electrical components of the sensor. One end of each lead-out pole 33 is welded with a spiral sensitive element 1, and the other end is welded with a wire. One end of the 8 wires is connected to the corresponding position of the circuit board 8 The exposed part of the lead-out electrode 33 welding wire is equipped with an insulating sleeve 24; the sealing flange 12 is fixed to the sensor body 26 by 4 bolts 11, which is used to squeeze the positioning seat 16, the sealing rubber pad 15 and the bakelite pad 14; there are 2 second pillars 10 with threads at both ends, the lower end of the second pillar 10 is fixed to the sealing flange 12, the upper end of the second pillar 10 is installed with a circuit board 8, and the upper end is installed with a first pillar 7, and there are 2 first pillars 7; the plug fixing plate 6 is connected to the first pillar 7 by two third screws 20; the plug X1 is fixed to the top of the plug fixing plate 6 by four first screws 5; there are 4 wires on the circuit board 8 connected to the plug X1, 2 wires supply power to the sensor, and the other 2 wires are sensor signal lines; the housing 21 is fixed to the sensor body 26 by a fifth screw 25.

[0066] like Figure 3As shown, a light impurity accident protection sensor includes compensation sensitive elements R5, R8, working sensitive elements R6, R7, fixed resistor R1, zero point corrector (i.e., first variable resistor) R2, and sensitivity corrector (i.e., second variable resistor) R4; ①, ②, ③, ④, ⑤, ⑥, ⑦, ⑧ are respectively the wire codes leading out of both ends of each element of compensation sensitive elements R5, R8 and working sensitive elements R6, R7; nodes 1-19 are respectively the welding hole position codes on the circuit board; fixed resistor R1 is connected between node 13 and node 15, zero point corrector R2 is connected between node 16 and node 17, and the variable end of zero point corrector R2 is connected to 14, that is, R2 is connected in parallel with R1; ① end of compensation sensitive element R5 is connected to node 6, and the compensation sensitive element R6 is connected to the variable end of zero point corrector R2 ... The ② end of component R5 is connected to node 7; the ⑦ end of compensation sensitive element R8 is connected to node 10, and the ⑧ end of compensation sensitive element R8 is connected to node 11; the ③ end of working sensitive element R6 is connected to node 12, and the ④ end of working sensitive element R6 is connected to node 5; the ⑤ end of working sensitive element R7 is connected to node 8, and the ⑥ end of working sensitive element R7 is connected to node 9; sensitivity corrector R4 is connected between node 18 and node 19, and the variable end of sensitivity corrector R4 is connected to node 19; nodes 1, 2, 3, and 4 are connected to contacts 1, 2, 3, and 4 on plug X1 respectively, contact 1 on plug X1 is the positive pole of power supply, contact 2 on plug X1 is the negative pole of power supply, contact 3 on plug X1 is the positive end of output signal, and contact 4 on plug X1 is the negative end of output signal.

[0067] R1, R2 and R5, R6, R7, R8 form a DC unbalanced bridge circuit. The sensitive elements R5, R6, R7, R8 have the same resistance and the same volt-ampere characteristics. The first variable resistor R2 is a zero point corrector, which can ensure that the correction range of the sensor is not less than ±50mV; the second variable resistor R4 is a sensitivity corrector, which adjusts the power supply voltage of the bridge; the power supply of the sensor circuit is 12.0±0.1VDC.

[0068] When there are no light impurities, the bridge circuit of the sensor is in a balanced state and the sensor output signal is zero. Within the sensor measurement range, the sensor outputs a DC pulse voltage signal proportional to the light impurity content. When the specified value is reached, the output signal can cause the actuator of the automatic control system to act, thereby protecting the host device.

[0069] After testing, the performance of the light impurity accident protection sensor provided in the embodiment of the present application can reach the following parameters:

[0070] 1. When the temperature is 10-35°C and the pressure of the test medium is 1-90 mmHg:

[0071] When the load resistance is ≥250Ω and the volume fraction of light impurities varies within the range of 6% to 20%, the sensitivity of the sensor is (8.0±1.6)mV / %;

[0072] 2. The time for the amplitude output signal to increase from 0.1 to 0.8 shall not exceed:

[0073] 9s——When the pressure of the testing medium is 1~10mmHg;

[0074] 14s——When the pressure of the testing medium is 10~45mmHg.

[0075] 3. The power supply of the sensor is 12.0±0.1VDC.

[0076] A light impurity accident protection sensor provided in the embodiment of the present application has a wide applicable flow range, enhances the airflow permeability of the porous screen component structure, and has strong corrosion resistance; improves the structural design of the sensor working chamber and compensation chamber parts; and the structure of the sensor is easy to process, the material is easy to obtain, and the service life is longer; and it has been proven through laboratory performance tests and engineering applications that the performance is reliable and stable. The embodiment of the present application calculates and determines the parameters of the sensitive element, designs the sensor structure, selects materials and processes the components based on the working principle, function and technical parameters of the sensor, and after assembly, the technical performance of the sensor is achieved by using a laboratory performance testing device. The structure of the working chamber and the structure of the porous screen have a great influence on the performance of the sensor.

[0077] The present application is described in detail above in conjunction with the accompanying drawings and embodiments, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present application. Any content not described in detail in the present application can adopt the existing technology.

Claims

1. A light impurity accident protection sensor, characterized in that: The sensor comprises: a spiral sensitive element (1), a cavity (2), a porous screen (3), a flow guide cover (4) and a circuit board (8); A partition is arranged in the middle of the cavity (2) to divide it into two chambers that are not connected to each other; a plurality of spiral-shaped sensitive elements (1) are evenly distributed in the two chambers, and the resistance values ​​of the spiral-shaped sensitive elements (1) in the two chambers are equal; The outer side of each chamber is provided with a porous screen (3), the outer side of the porous screen (3) is provided with a flow guide cover (4), and the porous screens (3) and flow guide covers (4) on the outer sides of the two chambers are not in communication with each other; Each flow guide cover (4) is provided with a gas input channel and a gas output channel which are connected with the corresponding chamber, and are used to input the comparison gas and the light impurity gas respectively; A plurality of spiral-shaped sensitive elements (1) are connected to a circuit board (8) so as to determine the content of light impurity gas according to the resistance change of the spiral-shaped sensitive elements (1) in the chamber, thereby realizing light impurity accident protection.

2. The light impurity accident protection sensor according to claim 1, characterized in that: The porous screen (3) comprises two hollow cylinders which are sleeved together. The hollow cylinders are evenly provided with a plurality of ventilation holes, and a porous screen bottom cover (32) is welded to the bottom end. The heights of the two hollow cylinders are different.

3. The light impurity accident protection sensor according to claim 2, characterized in that: The sensor further comprises: a sensor body (26); The deflector (4) is fixed to the outer end surface of the lower part of the sensor body (26) by a second screw (18); the upper ends of the two hollow cylinders are welded and fixed by a "Z"-shaped fixing plate (34), and the upper end of the taller hollow cylinder is welded to the fixing joint (19) and fixedly connected to the outer end surface of the lower part of the sensor body (26).

4. The light impurity accident protection sensor according to claim 3, characterized in that: The sensor also includes: a sealing flange (12), a bakelite pad (14), a sealing rubber pad (15) and a positioning seat (16); The positioning seat (16), the sealing rubber pad (15) and the bakelite pad (14) are installed in the sensor body (26) from bottom to top; the sealing flange (12) is fixed to the upper section of the sensor body (26) by bolts (11) and is used to squeeze the positioning seat (16), the sealing rubber pad (15) and the bakelite pad (14); The positioning seat (16), the sealing rubber pad (15) and the bakelite pad (14) are all provided with mounting holes for passing the connecting wires of the plurality of spiral-shaped sensitive elements (1). The circuit board (8) is fixed to the upper end of the sealing flange (12) and connected to the connecting wires of the spiral-shaped sensitive elements (1).

5. The light impurity accident protection sensor according to claim 4, characterized in that: An insulating column (17) is installed in the installation hole; the lead-out pole (33) passes through the lower end of the insulating column (17) and is connected to the spiral sensitive element (1), and the upper end is connected to the circuit board (8); The exposed part of the lead-out electrode (33) welding wire is provided with an insulating sleeve (24).

6. The light impurity accident protection sensor according to claim 4, characterized in that: There are eight spiral-shaped sensitive elements (1) in total; four spiral-shaped sensitive elements (1) are respectively arranged in each cavity, and every two adjacent spiral-shaped sensitive elements (1) are connected in series.

7. The light impurity accident protection sensor according to claim 6, characterized in that: The sensor further comprises: a shaft (27), a "U"-shaped fixed pole (28), a semicircular fixed sheet (29) and a limiting clamp ring (30); The upper end of the shaft (27) is connected by a thread and mounted on the positioning seat (16); a semicircular fixing plate (29) has a hole and is mounted on the lower end of the shaft (27); each semicircular fixing plate (29) has a hole, and a "U"-shaped fixed pole (28) is installed in every two adjacent holes, and the lower ends of every two adjacent spiral sensitive elements (1) are respectively connected to the two ends of the "U"-shaped fixed pole (28).

8. The light impurity accident protection sensor according to claim 4, characterized in that: A cavity bottom cover (31) is installed at the bottom of the cavity (2); and a "dish-shaped" rubber sealing pad (36) is installed at the lower end of the positioning seat (16).

9. The light impurity accident protection sensor according to claim 4, characterized in that: The sensor further comprises: a plug fixing plate (6), a first support column (7), a second support column (10) and a housing (21); The lower end of the second pillar (10) is fixed on the sealing flange (12), the upper end of the second pillar (10) is mounted with a circuit board (8), and the upper end of the circuit board (8) is mounted with the first pillar (7); the plug fixing plate (6) is connected to the first pillar (7) by a third screw (20); The housing (21) is sleeved on the outside of the circuit board (8) and is fixed to the sensor body (26) by means of a fifth screw (25); a plug (X1) is provided on the housing (21), the circuit board (8) is connected to the plug (X1), and the plug (X1) is fixed to the top of the plug fixing plate (6) by means of a first screw (5).

10. The light impurity accident protection sensor according to claim 3, characterized in that: The sensor further comprises: a flange (35); The flange (35) is mounted on the step of the sensor body (26) with the groove facing downward.

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