Laboratory fume hood with cascading spray wash structure

Abstract

The application discloses a laboratory fume hood with a hierarchical spraying washing structure and relates to the technical field of laboratory fume hoods.The laboratory fume hood is provided with a waste gas pipeline fixedly connected to the top end of the laboratory fume hood, and the tail end of the waste gas pipeline is provided with a first-stage spraying structure and a second-stage spraying structure.The first-stage spraying structure comprises a first-stage spraying washing cabin in communication with the tail end of the waste gas pipeline.The application is provided with a speed measuring fan and a concentration sensor in the first-stage spraying washing cabin and a quantitative output pump linked with a PH value sensor in the second-stage spraying washing cabin, so that a control framework of double detection of concentration and wind speed and hierarchical treatment of first-stage rough washing and second-stage fine washing is formed, the washing liquid supply can simultaneously respond to the dynamic changes of waste gas emission speed and waste gas concentration, and the first-stage spraying waste liquid PH value is compensated and sprayed, so that the accurate distribution of the washing liquid and the closed-loop guarantee of waste gas treatment effect are realized.

Description

Technical Field

[0001] This invention relates to the field of laboratory fume hood technology, and specifically to a laboratory fume hood with a graded spray washing structure. Background Technology

[0002] Laboratory fume hoods are core equipment for laboratory safety, used to effectively remove toxic, harmful, and corrosive gases and dust generated during experiments, protecting laboratory personnel from harmful substances. With increasingly stringent environmental regulations and growing awareness of laboratory safety, fume hoods with exhaust gas treatment capabilities are gradually becoming an industry trend.

[0003] In the prior art, various technical solutions have been proposed to integrate spray purification functions into fume hoods. For example, Chinese patent publication number CN212190532U discloses a fume hood with exhaust gas treatment, which utilizes a spray pipe installed inside the exhaust gas pipe to neutralize the exhaust gas with the spray liquid, and employs a serpentine exhaust gas pipe to extend the gas-liquid contact time. Chinese patent application publication number CN115338221A further incorporates a guide vane inside the air inlet pipe, which, in conjunction with an elastic sliding resistor tube, automatically adjusts the spray volume based on the wind speed. Some technical solutions also mention using a pH sensor to detect the state of the spray liquid and provide feedback to control the amount of washing liquid added, thereby achieving automatic adjustment of the exhaust gas treatment process.

[0004] However, the existing technologies still have the following shortcomings. First, the spray volume adjustment in the existing technologies is based on a single method, mostly relying on wind speed or preset programs to control the spray volume, without considering the dynamic changes in the actual concentration of the exhaust gas. When the exhaust gas concentration suddenly increases, the purification is incomplete, and when the concentration is low, the spray liquid is wasted. Second, the existing technologies still lack a real-time sensing and graded treatment mechanism for the actual saturation state of the spray liquid, making it difficult to determine whether the spray liquid is close to saturation, which makes it difficult to guarantee the final purification effect. Summary of the Invention

[0005] The purpose of this invention is to provide a laboratory fume hood with a graded spray washing structure to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A laboratory fume hood with a graded spray washing structure includes a laboratory fume hood and an exhaust gas duct. The exhaust gas duct is fixedly connected to the top of the laboratory fume hood. At the end of the exhaust gas duct are a primary spray structure and a secondary spray structure. The primary spray structure includes a primary spray washing chamber connected to the end of the exhaust gas duct. The secondary spray structure includes a secondary spray washing chamber fixedly connected to the end of the primary spray washing chamber via a pipe. Waste liquid discharge pipes are installed at the bottom of both the primary and secondary spray washing chambers. A primary supply chamber is mounted on the top of the primary spray washing chamber, and a speed-measuring fan and a sieve plate are installed inside the primary spray washing chamber. A concentration sensor is fixedly installed inside the primary spray washing chamber, located between the sieve plate and the speed-measuring fan. A secondary supply chamber is mounted on the top of the secondary spray washing chamber, and a metering pump is installed inside the secondary supply chamber. A pH sensor is fixedly installed in the waste liquid discharge pipe at the bottom of the primary spray washing chamber. The pH sensor is electrically connected to the metering pump inside the secondary supply chamber via a controller.

[0008] A further improvement of the technical solution of the present invention is that: a constant pressure output pump and an adjustment component associated with the constant pressure output pump are installed inside the primary liquid supply chamber, and a uniformly distributed spray head is fixedly connected to the bottom of the primary liquid supply chamber. The spray head is connected to the output pipe of the constant pressure output pump. The adjustment component is used to control the amount of washing liquid input of the constant pressure output pump. A pneumatic transmission component is installed between the adjustment component and the speed measuring fan.

[0009] The above technical solution transmits the exhaust gas emission speed measured by the speed measuring fan to the adjustment component through the pneumatic transmission component, thereby realizing the adaptive adjustment of the washing liquid supply according to the exhaust gas emission speed.

[0010] A further improvement of the technical solution of the present invention is that: the pneumatic transmission component is used to control the adjustment amount of the adjustment component according to the exhaust gas emission speed measured by the speed measuring fan. The adjustment component includes an adjustment chamber assembled inside the primary liquid supply chamber. The adjustment chamber is connected to the top of the inner wall of the primary liquid supply chamber through uniformly distributed limit rods. A servo motor is fixedly connected to the top of the adjustment chamber. The drive shaft of the servo motor extends into the interior of the adjustment chamber and is fixedly connected to a central gear plate.

[0011] In the above technical solution, the servo motor drives the central gear disk to rotate according to the concentration sensor signal, so as to realize the precise adjustment of the washing liquid supply according to the concentration of exhaust gas. The concentration signal and the speed signal are controlled in concert through the same adjustment component.

[0012] A further improvement of the technical solution of the present invention is as follows: a partition plate located above the top of the constant pressure output pump is fixedly connected inside the primary liquid supply chamber. The partition plate divides the interior of the primary liquid supply chamber into upper and lower areas. The upper area is used to store washing liquid. An input pipe extending to the top of the partition plate is fixedly connected to the top of the constant pressure output pump. An adjustment pipe corresponding to the position of the input pipe is rotatably connected to the bottom of the adjustment chamber. A first opening is opened on the adjustment pipe, and a second opening with a shape adapted to the first opening is opened on the input pipe. Both the first and second openings are rectangular, and the vertical length is greater than the horizontal length. The top of the adjustment pipe extends into the interior of the adjustment chamber and is fixedly connected to a transmission gear. The transmission gear meshes with the central gear plate. The servo motor and the concentration sensor are electrically connected through a controller.

[0013] Using the above technical solution, the horizontal overlap area of ​​the first and second openings is changed by rotating the regulating tube, and the vertical overlap position of the two openings is changed by raising and lowering the regulating chamber. The channel size is precisely controlled by a two-dimensional superposition of rectangular openings. The horizontal overlap is adjusted by the concentration signal, and the vertical overlap is adjusted by the wind speed signal.

[0014] A further improvement of the technical solution of the present invention is that: the pneumatic transmission assembly includes a centrifugal disc fixedly connected to one end of the rotating shaft of the speed measuring fan near the first-stage liquid supply chamber and a pneumatic rod fixedly connected to the top of the first-stage liquid supply chamber. An annular sleeve is rotatably connected to the outside of the centrifugal disc. The annular sleeve is fixedly connected to the frame of the speed measuring fan. The centrifugal disc has evenly distributed centrifugal pipes inside. The annular sleeve has a cavity covering the centrifugal pipes on its inner side. The annular sleeve and the pneumatic rod are connected through a first connecting pipe. A centrifugal block is sleeved inside the centrifugal pipe. A first spring is fixedly connected between the centrifugal block and the centrifugal pipe. A sealing ring is sleeved on the outside of the centrifugal block. The end of the telescopic part of the pneumatic rod is fixedly connected to a servo motor.

[0015] Using the above technical solution, when the speed of the speed measuring fan changes, the centrifugal block slides in the centrifugal pipe. The change in air pressure drives the air pressure rod to extend and retract, which in turn drives the regulating chamber and servo motor to rise and fall as a whole. The wind speed signal is converted into a vertical displacement in a purely mechanical way, without the need for additional electrical conversion.

[0016] A further improvement of the technical solution of the present invention is that it also includes a gear control component, which is used to control the adjustment range of the pneumatic transmission component. The gear control component includes evenly spaced positioning blocks sleeved on the inner wall of the centrifugal pipe. A telescopic cavity adapted to the shape of the positioning block is opened on the inner wall of the centrifugal pipe. A second spring is fixedly connected between the positioning block and the telescopic cavity. The end of the positioning block extends into the centrifugal pipe. The spacing between the positioning blocks is greater than the thickness of the centrifugal block.

[0017] In the above technical solution, the centrifugal block is blocked by the positioning block in the centrifugal pipeline, so that the adjustment range of the air pressure rod changes gradually in stages, reducing the adjustment frequency to reduce the wear of structural components, and at the same time avoiding the impact of wind speed detection lag on the spraying effect.

[0018] A further improvement of the technical solution of the present invention is that it also includes a cleaning component, which is used for periodic cleaning of the screen plate. The cleaning component includes fixed spokes symmetrically installed on both sides of the screen plate. The fixed spokes are rotatably connected to the middle of the screen plate through a rotating shaft. Cleaning strips are fixedly connected to the side of the fixed spokes near the screen plate. The middle of the cleaning strip is provided with an I-shaped deformation zone, and the end of the cleaning strip is in contact with the outside of the screen plate. An angle is provided between the cleaning strip and the long side of the fixed spoke. A limiting plate located outside the fixed spoke is sleeved on the outside of the screen plate.

[0019] Using the above technical solution, the cleaning strip scrapes the surface of the screen plate as it rotates with the fixed spokes. The I-shaped deformation zone keeps the cleaning strip in close contact with the screen plate, and the limiting plate confines the scraped particles to the bottom of the screen plate for easy centralized cleaning.

[0020] A further improvement of the technical solution of the present invention is that: a first transmission rod is fixedly connected to the outside of the fixed spokes near the speed measuring fan; a pressure sleeve is slidably fitted on the outside of the first transmission rod; a guide groove adapted to the shape of the pressure sleeve is provided on the first transmission rod; an electric telescopic rod that can drive the pressure sleeve to slide is fixedly connected to the outside of the first transmission rod; a second transmission rod corresponding to the position of the first transmission rod is fixedly connected to the end of the rotating shaft of the speed measuring fan near the screen plate; and a pressure head adapted to the shape of the pressure sleeve is fixedly connected to the end of the second transmission rod.

[0021] The above technical solution involves the periodic engagement and disengagement of the electric telescopic rod driving the pressure sleeve and the pressure head, which intermittently transmits the rotational power of the speed measuring fan to the fixed spokes to drive the cleaning action. After cleaning is completed, the connection is automatically disconnected to avoid continuous interference with the normal operation of the speed measuring fan.

[0022] A further improvement of the technical solution of the present invention is that: the screen plate is fixedly connected to the outside of the screen plate with uniformly distributed clamping plates for fixing the limiting plate; the limiting plate has a circular opening in the middle with a radius value that matches the length value of the fixed spoke; the bottom of the screen plate has symmetrically distributed slag discharge ports; and the bottom end of the primary spray washing chamber is fitted with a sealing seat for sealing the slag discharge ports.

[0023] In the above technical solution, the clamping plate fixes the limiting plate to the outside of the screen plate to restrict the cleaning range. The scraped particles accumulate between the limiting plate and the screen plate and are discharged periodically through the slag discharge port, which is convenient for maintenance and cleaning.

[0024] By adopting the above technical solution, the technical effects achieved by this invention compared to the prior art are as follows:

[0025] 1. This invention provides a laboratory fume hood with a graded spray washing structure. By installing a speed measuring fan and a concentration sensor in the first-stage spray washing chamber and a quantitative output pump linked to a pH sensor in the second-stage spray washing chamber, a control architecture is formed that enables dual detection of concentration and wind speed and graded treatment of first-stage coarse washing and second-stage fine washing. This allows the washing liquid supply to respond simultaneously to the dynamic changes in exhaust gas emission speed and exhaust gas concentration, and to compensate for the spraying according to the pH value of the waste liquid after the first-stage spraying, thereby achieving precise distribution of washing liquid and closed-loop guarantee of exhaust gas treatment effect.

[0026] 2. This invention provides a laboratory fume hood with a graded spray washing structure. By setting up a structure in which the regulating pipe driven by a servo motor cooperates with the rectangular opening on the input pipe, the concentration signal controls the horizontal overlapping area, and the wind speed signal controls the vertical overlapping position through a pneumatic transmission component. The two work together to adjust the size of the channel opening in a two-dimensional superposition manner. The concentration has a greater weight in adjusting the opening amplitude than the wind speed, which ensures the accuracy of the main control of the exhaust gas concentration while taking into account the compensation requirements for wind speed changes.

[0027] 3. The present invention provides a laboratory fume hood with a graded spray washing structure. By setting a gear control component consisting of a positioning block and a second spring in the centrifuge pipe, the centrifuge block slides in the centrifuge pipe in a graded progressive movement, which limits the adjustment range caused by wind speed to a step-like rather than continuous fluctuation, reduces the adjustment frequency of the channel opening to reduce mechanical wear, and avoids the interference of wind speed detection lag on the spray effect.

[0028] 4. This invention provides a laboratory fume hood with a graded spray washing structure. By setting up a cleaning component consisting of fixed spokes, cleaning strips and I-shaped deformation zones, and using an intermittent power engagement structure achieved by a first transmission rod, a second transmission rod and an electric telescopic rod, the particle accumulation on the surface of the sieve plate can be periodically scraped off and the power connection can be automatically disconnected after cleaning. This ensures the uniform dispersion effect of the sieve plate on the exhaust gas and the accuracy of concentration detection, while avoiding interference with the continuous operation of the speed measuring fan. Attached Figure Description

[0029] The invention will now be further described with reference to the accompanying drawings.

[0030] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0031] Figure 2 This is a schematic diagram of the combined structure of the primary spray washing chamber and the secondary spray washing chamber of the present invention;

[0032] Figure 3This is a schematic diagram of the internal structure of the primary spray washing chamber and the secondary spray washing chamber of the present invention;

[0033] Figure 4 A schematic diagram of the structure of the primary liquid supply tank, sieve plate and speed measuring fan;

[0034] Figure 5 This is a schematic diagram of the exploded structure of the sieve plate;

[0035] Figure 6 A schematic diagram of the structure for the fixed spokes and the cleaning strip;

[0036] Figure 7 for Figure 6 Enlarged structural diagram at point A in the middle;

[0037] Figure 8 This is a schematic diagram of the mating structure of the first transmission rod, the second transmission rod, the pressing head, and the pressing sleeve.

[0038] Figure 9 A schematic diagram showing a partial cross-sectional view of the centrifugal disc and the annular casing;

[0039] Figure 10 for Figure 9 Enlarged structural diagram at point B;

[0040] Figure 11 This is a schematic diagram of the internal structure of the primary feed tank;

[0041] Figure 12 This is a schematic diagram of the internal structure of the regulating compartment;

[0042] Figure 13 This is a schematic diagram of the three-dimensional structure of the input tube and the regulating tube.

[0043] In the diagram: 1. Laboratory fume hood; 2. Exhaust gas duct; 3. Primary spray scrubbing chamber; 4. Secondary spray scrubbing chamber; 5. Waste liquid discharge pipe; 6. Primary supply chamber; 7. Secondary supply chamber; 8. Concentration sensor; 9. pH sensor; 10. Sieve plate; 11. Speed ​​measuring fan; 12. Centrifuge disc; 13. Pneumatic rod; 14. First connecting pipe; 15. Clamping plate; 16. Limiting plate; 17. Fixed spokes; 18. Slag discharge port; 19. Sealing seat; 20. First transmission rod; 21. Cleaning strip; 22. Deformation zone; 23. 24. Second transmission rod; 25. Pressing head; 26. Guide groove; 27. Pressing sleeve; 28. Electric telescopic rod; 29. ​​Annular sleeve; 30. First spring; 31. Centrifugal pipe; 32. Centrifugal block; 33. Telescopic cavity; 34. Positioning block; 35. Second spring; 36. Servo motor; 37. Limiting rod; 38. Adjusting chamber; 39. Partition plate; 40. Constant pressure output pump; 41. Spray head; 42. Central gear plate; 43. Transmission gear; 44. Input pipe; 45. Adjusting pipe; 46. First opening; 47. Second opening. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the embodiments.

[0045] Example 1

[0046] like Figure 1-13 As shown, this invention provides a laboratory fume hood with a graded spray washing structure, including a laboratory fume hood 1 and an exhaust gas duct 2. The exhaust gas duct 2 is fixedly connected to the top of the laboratory fume hood 1. A primary spray structure and a secondary spray structure are provided at the end of the exhaust gas duct 2. The primary spray structure includes a primary spray washing chamber 3 connected to the end of the exhaust gas duct 2. The secondary spray structure includes a secondary spray washing chamber 4 fixedly connected to the end of the primary spray washing chamber 3 via a pipe. Waste liquid discharge pipes 5 are provided at the bottom of both the primary spray washing chamber 3 and the secondary spray washing chamber 4. The exhaust gas generated during the operation of the laboratory fume hood 1 is treated through the exhaust gas duct 2. During the emission process, the exhaust gas sequentially enters the primary and secondary spray structures at the end of exhaust gas pipeline 2. The primary spray structure measures the exhaust gas volume based on the measured exhaust gas concentration and emission rate, and quantitatively distributes the washing liquid according to the measurement data for primary spray washing. After primary spray washing, the content of harmful gases in the exhaust gas is reduced, and the gas is then introduced into the secondary spray structure through the pipeline. The secondary spray structure determines the purification effect based on the pH value of the waste liquid in the primary spray structure, and then compensates for the effect by performing secondary spray washing. This ensures the exhaust gas treatment effect of the entire equipment and precise control of the washing liquid dosage.

[0047] like Figure 1-3 As shown, in this embodiment, preferably, a primary liquid supply chamber 6 is installed on the top of the primary spray washing chamber 3, and a speed measuring fan 11 and a sieve plate 10 are provided inside the primary spray washing chamber 3. A concentration sensor 8 is fixedly installed inside the primary spray washing chamber 3 between the sieve plate 10 and the speed measuring fan 11. The sieve plate 10 is used to uniformly disperse the exhaust gas output from the exhaust gas pipe 2 and input it into the primary spray washing chamber 3 for concentration sensor 8 to detect the concentration. The sieve plate 10 is fixedly installed at one end of the primary spray washing chamber 3 near the end of the exhaust gas pipe 2. The sieve plate 10 has uniformly distributed through openings. The exhaust gas entering the primary spray washing chamber 3 must pass through the through openings on the sieve plate 10 and be uniformly dispersed through the through openings, so that the concentration of the exhaust gas in each part of the primary spray washing chamber 3 is uniform, which can effectively improve the accuracy of the exhaust gas concentration detected by the concentration sensor 8, so that the primary spray washing structure can subsequently control the amount of washing liquid supplied during primary spray washing according to the exhaust gas concentration.

[0048] like Figure 1-3As shown, in this embodiment, preferably, a secondary liquid supply chamber 7 is installed on the top of the secondary spray washing chamber 4. A quantitative output pump is installed inside the secondary liquid supply chamber 7. A pH sensor 9 is fixedly installed in the waste liquid discharge pipe 5 at the bottom of the primary spray washing chamber 3. The pH sensor 9 and the quantitative output pump inside the secondary liquid supply chamber 7 are electrically connected through a controller. The exhaust gas after the primary spray washing in the primary spray washing chamber 3 is input into the secondary spray washing chamber 4. At the same time, the waste liquid generated by the spray washing is discharged through the waste liquid discharge pipe 5 at the bottom of the primary spray washing chamber 3. The pH sensor 9 detects the pH value of the waste liquid and controls the quantitative output pump to compensate a certain amount of washing liquid for secondary spray washing based on the detected pH value, thereby ensuring the purification effect of the discharged exhaust gas.

[0049] like Figure 8-13As shown, in this embodiment, preferably, a constant pressure output pump 39 and an adjustment component associated with the constant pressure output pump 39 are provided inside the primary liquid supply tank 6. A uniformly distributed spray head 40 is fixedly connected to the bottom of the primary liquid supply tank 6. The spray head 40 is connected to the output pipe of the constant pressure output pump 39. The adjustment component is used to control the amount of washing liquid input from the constant pressure output pump 39. A pneumatic transmission component is provided between the adjustment component and the speed measuring fan 11. The pneumatic transmission component is used to control the adjustment amount of the adjustment component according to the exhaust gas emission speed measured by the speed measuring fan 11. The adjustment component includes an adjustment chamber 37 assembled inside the primary liquid supply tank 6. The adjustment chamber 37 is connected to the top of the inner wall of the primary liquid supply tank 6 by a uniformly distributed limiting... The position rod 36 is connected to the top of the regulating chamber 37, and a servo motor 35 is fixedly connected to the top of the regulating chamber 37. The drive shaft of the servo motor 35 extends into the interior of the regulating chamber 37 and is fixedly connected to the central gear plate 41. The interior of the primary liquid supply chamber 6 is fixedly connected to a partition 38 located above the top of the constant pressure output pump 39. The partition 38 divides the interior of the primary liquid supply chamber 6 into upper and lower areas. The upper area is used to store washing liquid. The top of the constant pressure output pump 39 is fixedly connected to an input pipe 43 extending above the partition 38. The bottom of the regulating chamber 37 is rotatably connected to an regulating pipe 44 corresponding to the position of the input pipe 43. The regulating pipe 44 has a first opening 45, and the input pipe 43 has a second opening 45 that matches the shape of the first opening 45. 6. Both the first opening 45 and the second opening 46 are rectangular, and their vertical length is greater than their horizontal length. The top of the regulating pipe 44 extends into the interior of the regulating chamber 37 and is fixedly connected to a transmission gear 42. The transmission gear 42 meshes with the central gear disk 41. The servo motor 35 is electrically connected to the concentration sensor 8 via a controller. The washing liquid is stored in the upper area of ​​the primary supply chamber 6. After the concentration sensor 8 detects the concentration of the exhaust gas passing through the primary spray washing chamber 3, it can control the servo motor 35 to perform primary adjustment. Specifically, in the initial state, the regulating pipe 44 is fitted into the input pipe 43, and the first opening 45 on the regulating pipe 44 and the second opening 46 in the input pipe 43 are not in the same position. The first opening 45 and the second opening 46 are completely offset from each other, with no overlap between them. This means that there is no connecting channel between the input pipe 43 and the area where the washing liquid is stored in the primary liquid supply tank 6. After the servo motor 35 measures the concentration according to the concentration sensor 8, the drive shaft of the servo motor 35 rotates at a corresponding angle. Then, through the transmission between the central gear plate 41 and the transmission gear 42, the regulating pipe 44 rotates. This causes the regulating pipe 44 to rotate in the same way as the input pipe 43. Consequently, the first opening 45 and the second opening 46 also overlap in the horizontal direction due to the rotation. This allows the exhaust gas concentration to directly affect the size of the channel formed between the input pipe 43 and the primary liquid supply tank 6.

[0050] like Figure 3-11As shown, in this embodiment, preferably, the pneumatic transmission assembly includes a centrifugal disc 12 fixedly connected to one end of the rotating shaft of the speed measuring fan 11 near the first-stage liquid supply chamber 6, and a pneumatic rod 13 fixedly connected to the top of the first-stage liquid supply chamber 6. An annular sleeve 28 is rotatably connected to the outside of the centrifugal disc 12, and the annular sleeve 28 is fixedly connected to the frame of the speed measuring fan 11. The centrifugal disc 12 has evenly distributed centrifugal pipes 30 inside, and the annular sleeve 28 has a cavity covering the centrifugal pipes 30 on its inner side. The annular sleeve 28 and the pneumatic rod 13 are connected... The centrifugal pipe 30 is connected to the centrifugal pipe 30 by a first connecting pipe 14. A centrifugal block 31 is installed inside the centrifugal pipe 30. A first spring 29 is fixedly connected between the centrifugal block 31 and the centrifugal pipe 30. A sealing ring is installed on the outside of the centrifugal block 31. The end of the telescopic part of the air pressure rod 13 is fixedly connected to the servo motor 35. The exhaust gas dispersed by the sieve plate 10 passes through the speed measuring fan 11 and drives the speed measuring fan 11 to rotate. When the speed measuring fan 11 rotates, its shaft drives the centrifugal disk 12 to rotate. After the centrifugal disk 12 rotates, it moves away from the centrifugal disk under the action of centrifugal force. The centrifugal block 31 slides in the centrifugal pipe 30 and stretches the first spring 29. At the same time, due to the sealing ring outside the centrifugal block 31, the sliding of the centrifugal block 31 in the centrifugal pipe 30 will cause the air pressure in the space formed by the cavity inside the annular sleeve 28 and the centrifugal pipe 30 to change. This air pressure change is transmitted through the first connecting pipe 14, which drives the telescopic end of the air pressure rod 13 to produce a corresponding displacement. In turn, it drives the servo motor 35 and the regulating chamber 37 to adjust the height inside the first-stage liquid supply chamber 6 according to the speed of the speed measuring fan 11, changing the relative height of the first opening 45 and the second opening 46, so that they overlap vertically. This vertical overlap, combined with the horizontal overlap of the first opening 45 and the second opening 46 brought about by the regulating component, forms a channel between the input pipe 43 and the first-stage liquid supply chamber 6. Based on the shape of the first opening 45 and the second opening 46, it can be seen that the adjustment range of the channel opening size is more affected by the concentration and less affected by the exhaust gas emission speed. The two work together to achieve precise distribution of washing liquid in the first-stage spray washing chamber 3.

[0051] Example 2

[0052] like Figure 8-10As shown, based on Embodiment 1, the present invention provides a technical solution: preferably, it further includes a gear control component, which is used to control the adjustment range of the pneumatic transmission component. The gear control component includes evenly spaced positioning blocks 33 sleeved on the inner wall of the centrifugal pipe 30. A telescopic cavity 32 adapted to the shape of the positioning blocks 33 is opened on the inner wall of the centrifugal pipe 30. A second spring 34 is fixedly connected between the positioning blocks 33 and the telescopic cavity 32. The end of the positioning block 33 extends into the centrifugal pipe 30, and the distance between the positioning blocks 33 is greater than the thickness of the centrifugal block 31. When the speed of the speed measuring fan 11 is low, the centrifugal force of the centrifugal block 31 is insufficient to overcome the elastic force of the second spring 34, and cannot push the positioning block 33 into the telescopic cavity 32. The centrifugal block 31 is restricted between two adjacent sets of positioning blocks 33, and the pneumatic rod 13 adjusts the size of the connection between the input pipe 43 and the primary liquid supply chamber 6 only according to the range corresponding to the current gear. When the speed measuring fan 11 increases its rotational speed to the point that the centrifugal force is sufficient to overcome the elastic force of the second spring 34, the centrifugal block 31 pushes the positioning block 33 into the telescopic cavity 32 and passes over the group of positioning blocks 33, entering the next group of positioning blocks 33. The adjustment range of the pneumatic rod 13 then switches to the next gear. In this way, the change in the rotational speed of the speed measuring fan 11 is converted into a gradual movement of the centrifugal block 31 in the centrifugal pipe 30, making the adjustment of the connection port size a step-like change rather than a continuous fluctuation. This reduces the adjustment frequency of the channel port, reduces wear between structural components, and even if the exhaust gas emission speed detected by the speed measuring fan 11 has a certain lag, it will not affect the spray washing effect in the primary spray washing chamber 3.

[0053] Example 3

[0054] like Figure 4-8As shown, based on Embodiment 1, the present invention provides a technical solution: preferably, it further includes a cleaning component for periodic cleaning of the sieve plate 10. The cleaning component includes fixed spokes 17 symmetrically installed on both sides of the sieve plate 10. The fixed spokes 17 are rotatably connected to the middle of the sieve plate 10 via a rotating shaft. Cleaning strips 21 are uniformly distributed and fixedly connected to the side of the fixed spokes 17 near the sieve plate 10. The middle of the cleaning strips 21 is provided with an I-shaped deformation zone 22, and the ends of the cleaning strips 21 are in contact with the outside of the sieve plate 10. An angle is provided between the cleaning strips 21 and the long side of the fixed spokes 17. A limiting plate 16 located outside the fixed spokes 17 is sleeved on the outside of the sieve plate 10, and uniformly distributed clamping plates 15 for fixing the limiting plate 16 are fixedly connected to the outside of the sieve plate 10. The middle of the limiting plate 16 is open. A circular opening with a radius matching the length of the fixed spoke 17 is provided. A first transmission rod 20 is fixedly connected to the outside of the fixed spoke 17 near the speed measuring fan 11. A pressure sleeve 26 is slidably fitted on the outside of the first transmission rod 20, and a guide groove 25 matching the shape of the pressure sleeve 26 is provided on the first transmission rod 20. An electric telescopic rod 27 that can drive the pressure sleeve 26 to slide is fixedly connected to the outside of the first transmission rod 20. A second transmission rod 23 corresponding to the position of the first transmission rod 20 is fixedly connected to the end of the rotating shaft of the speed measuring fan 11 near the screen plate 10. A pressure head 24 matching the shape of the pressure sleeve 26 is fixedly connected to the end of the second transmission rod 23. Symmetrically distributed slag discharge ports 18 are provided at the bottom of the screen plate 10. A sealing seat 19 for sealing the slag discharge ports 18 is fitted at the bottom of the first-stage spray washing chamber 3.

[0055] After prolonged operation, the sieve plate 10 inevitably accumulates particulate residue from the exhaust gas. This residue affects the dispersion effect of the sieve plate 10, thus impacting the detection accuracy of the subsequent primary spray washing structure. Therefore, a cleaning component is installed to periodically scrape off the particles adsorbed on the sieve plate 10. Specifically, after the entire device has been operating for a period of time, the electric telescopic rod 27 periodically drives the pressure sleeve 26 to slide along the guide groove 25 outside the first transmission rod 20, causing the pressure sleeve 26 to move closer to the pressure head 24 until the pressure sleeve 26 and the pressure head 24 make contact. This creates a pressure connection between the second transmission rod 23 and the first transmission rod 20. At this time, the rotation of the speed measuring fan 11 will drive the fixed spokes 17 to move briefly outside the sieve plate 10 through the transmission of the second transmission rod 23 and the first transmission rod 20. After the fixed spokes 17 rotate two to three times around the outside of the screen plate 10, the electric telescopic rod 27 drives the pressure sleeve 26 to reset, disconnecting the connection between the second transmission rod 23 and the first transmission rod 20. This prevents the speed measuring fan 11 from being disturbed for a long time due to the rotational load of the first transmission rod 20 and the fixed spokes 17, thus affecting the final purification effect of the equipment. When the fixed spokes 17 rotates, the cleaning strips 21 come into contact with the outer surface of the screen plate 10, scraping off the particles accumulated on the outside of the screen plate 10 and letting them fall into the bottom area between the screen plate 10 and the limiting plate 16 for storage. This maintains the dispersion effect of the screen plate 10 on the exhaust gas for a long time. When cleaning later, the closed seat 19 can be removed from the bottom of the first-stage spray washing chamber 3 to open the slag discharge port 18, allowing the accumulated particle residue to leak out, which is convenient for subsequent maintenance and cleaning of the equipment.

[0056] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A laboratory fume hood with a graded spray washing structure, comprising a laboratory fume hood (1) and an exhaust gas duct (2), wherein the exhaust gas duct (2) is fixedly connected to the top of the laboratory fume hood (1), characterized in that, The exhaust gas duct (2) is equipped with a primary spray structure and a secondary spray structure. The primary spray structure includes a primary spray scrubbing chamber (3) connected to the end of the exhaust gas duct (2). The secondary spray structure includes a secondary spray scrubbing chamber (4) fixedly connected to the end of the primary spray scrubbing chamber (3) via a pipe. Waste liquid discharge pipes (5) are provided at the bottom of both the primary spray scrubbing chamber (3) and the secondary spray scrubbing chamber (4). The top of the primary spray washing chamber (3) is equipped with a primary liquid supply chamber (6), and the interior of the primary spray washing chamber (3) is equipped with a speed measuring fan (11) and a sieve plate (10). The interior of the primary spray washing chamber (3) is fixedly installed with a concentration sensor (8) located between the sieve plate (10) and the speed measuring fan (11). The top of the secondary spray washing chamber (4) is equipped with a secondary liquid supply chamber (7). The secondary liquid supply chamber (7) is equipped with a quantitative output pump. A pH sensor (9) is fixedly installed in the waste liquid discharge pipe (5) at the bottom of the primary spray washing chamber (3). The pH sensor (9) and the quantitative output pump inside the secondary liquid supply chamber (7) are electrically connected through a controller.

2. A laboratory fume hood with a graded spray washing structure according to claim 1, characterized in that: The primary liquid supply chamber (6) is equipped with a constant pressure output pump (39) and an adjustment component associated with the constant pressure output pump (39). The bottom of the primary liquid supply chamber (6) is fixedly connected with uniformly distributed spray heads (40). The spray heads (40) are connected to the output pipe of the constant pressure output pump (39). The adjustment component is used to control the amount of washing liquid input of the constant pressure output pump (39). A pneumatic transmission component is provided between the adjustment component and the speed measuring fan (11). The pneumatic transmission component is used to control the adjustment amount of the adjustment component according to the exhaust gas emission speed measured by the speed measuring fan (11).

3. A laboratory fume hood with a graded spray washing structure according to claim 2, characterized in that: The regulating assembly includes a regulating chamber (37) assembled inside the primary liquid supply chamber (6). The regulating chamber (37) is connected to the top of the inner wall of the primary liquid supply chamber (6) by a uniformly distributed limiting rod (36). A servo motor (35) is fixedly connected to the top of the regulating chamber (37). The drive shaft of the servo motor (35) extends into the interior of the regulating chamber (37) and is fixedly connected to a central gear plate (41). An input pipe (43) extending to the top of the constant pressure output pump (39) is fixedly connected to the top of the pump (39) and extends to the top of the partition plate (38). A regulating pipe (44) corresponding to the position of the input pipe (43) is rotatably connected to the bottom of the regulating chamber (37). The top of the regulating pipe (44) extends into the interior of the regulating chamber (37) and is fixedly connected to a transmission gear (42). The transmission gear (42) meshes with the central gear plate (41). The servo motor (35) is electrically connected to the concentration sensor (8) through a controller.

4. A laboratory fume hood with a graded spray washing structure according to claim 3, characterized in that: The interior of the primary liquid supply chamber (6) is fixedly connected to a partition (38) located above the top of the constant pressure output pump (39). The partition (38) divides the interior of the primary liquid supply chamber (6) into upper and lower areas. The upper area is used to store washing liquid. A first opening (45) is opened on the regulating pipe (44), and a second opening (46) that matches the shape of the first opening (45) is opened on the input pipe (43). Both the first opening (45) and the second opening (46) are rectangular, and the vertical length is greater than the horizontal length.

5. A laboratory fume hood with a graded spray washing structure according to claim 4, characterized in that: The pneumatic transmission assembly includes a centrifugal disc (12) fixedly connected to one end of the rotating shaft of the speed measuring fan (11) near the first-stage liquid supply chamber (6) and a pneumatic rod (13) fixedly connected to the top of the first-stage liquid supply chamber (6). An annular sleeve (28) is rotatably connected to the outside of the centrifugal disc (12). The annular sleeve (28) is fixedly connected to the frame of the speed measuring fan (11). The centrifugal disc (12) has evenly distributed centrifugal pipes (30) inside. The annular sleeve (28) has a cavity covering the centrifugal pipes (30) on the inner side. The annular sleeve (28) and the pneumatic rod (13) are connected through a first connecting pipe (14). A centrifugal block (31) is sleeved inside the centrifugal pipe (30). A first spring (29) is fixedly connected between the centrifugal block (31) and the centrifugal pipe (30). A sealing ring is sleeved on the outside of the centrifugal block (31). The end of the telescopic part of the pneumatic rod (13) is fixedly connected to the servo motor (35).

6. A laboratory fume hood with a graded spray washing structure according to claim 5, characterized in that: It also includes a gear control component, which is used to control the adjustment range of the pneumatic transmission component. The gear control component includes evenly spaced positioning blocks (33) fitted on the inner wall of the centrifugal pipe (30). A telescopic cavity (32) adapted to the shape of the positioning block (33) is opened on the inner wall of the centrifugal pipe (30). A second spring (34) is fixedly connected between the positioning block (33) and the telescopic cavity (32). The end of the positioning block (33) extends into the centrifugal pipe (30). The spacing between the positioning blocks (33) is greater than the thickness of the centrifugal block (31).

7. A laboratory fume hood with a graded spray washing structure according to claim 1, characterized in that: It also includes a cleaning component, which includes rotatable fixed spokes (17) symmetrically installed on both sides of the screen plate (10). The fixed spokes (17) are rotatably connected to the middle of the screen plate (10) via a rotating shaft. The fixed spokes (17) are fixedly connected to the side of the screen plate (10) with uniformly distributed cleaning strips (21). The middle of the cleaning strips (21) is provided with an I-shaped deformation zone (22), and the end of the cleaning strips (21) is in contact with the outside of the screen plate (10). An angle is provided between the cleaning strips (21) and the long side of the fixed spokes (17). The screen plate (10) is fitted with a limiting plate (16) located outside the fixed spokes (17).

8. A laboratory fume hood with a graded spray washing structure according to claim 7, characterized in that: The cleaning assembly is used for the periodic cleaning of the screen plate (10). A first transmission rod (20) is fixedly connected to the outside of the fixed spoke (17) near the speed measuring fan (11). A pressure sleeve (26) is provided on the outside of the first transmission rod (20), and a guide groove (25) adapted to the shape of the pressure sleeve (26) is provided on the first transmission rod (20). An electric telescopic rod (27) that can drive the pressure sleeve (26) to slide is fixedly connected to the outside of the first transmission rod (20). A second transmission rod (23) corresponding to the position of the first transmission rod (20) is fixedly connected to the end of the rotating shaft of the speed measuring fan (11) near the screen plate (10). A pressure head (24) adapted to the shape of the pressure sleeve (26) is fixedly connected to the end of the second transmission rod (23).

9. A laboratory fume hood with a graded spray washing structure according to claim 8, characterized in that: The screen plate (10) is fixedly connected to the outside with evenly distributed clamping plates (15) for fixing the limiting plate (16). The limiting plate (16) has a circular opening in the middle with a radius value that matches the length value of the fixed spoke (17). The bottom of the screen plate (10) has symmetrically distributed slag discharge ports (18). The bottom end of the primary spray washing chamber (3) is fitted with a sealing seat (19) for sealing the slag discharge ports (18).

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