Three-box type water treatment pollution dosing device

Abstract

The utility model relates to a three-box type water treatment pollution dosing device, which effectively solves the technical problems that the liquid level of the existing three-box type dosing device is inconvenient to observe, the sampling concentration is inaccurate, and the dry powder caking dissolving effect is poor, and comprises a box body, the interior of the box body is divided into a premixing tank, a curing tank and a storage tank by a plurality of low partition plates and high partition plates, the device is characterized in that the upper end and the lower end of the storage tank are communicated with an upper viewing pipe and a lower viewing pipe which are arranged outside, a liquid level pipe is communicated between the upper viewing pipe and the lower viewing pipe, the lower viewing pipe is in threaded connection with a sampling pipe, the interior of the sampling pipe is a cavity, the outer end of the sampling pipe is open, and a sampling opening is formed in the side wall of the sampling pipe. According to the utility model, through the matching of the upper view pipe, the lower view pipe, the liquid level pipe and the sampling pipe, the liquid level of the box body can be conveniently observed, the concentration of a solution in the box body can be sampled, and the sampling solution is the solution in the box body, so that the accuracy of the sampling concentration is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental protection water treatment, in particular to a three - tank water treatment pollution dosing device. Background Technique

[0002] The three - tank water treatment pollution dosing device is composed of a water supply system, a dry powder dosing system, a dissolution and ripening system, and a control system. It is generally used in the automatic continuous configuration and dosing system of powdered polymer flocculants. The dry powder flocculant enters the premixing tank from the screw propeller and is premixed with clear water. The wetted material is diluted in the premixing tank and prepared according to the required concentration. During the preparation process, the water volume is constant, and the flocculant is dosed proportionally. The proportion of the flocculant mainly depends on the rotation speed and pitch of the screw propeller, so as to ensure that the concentration of the prepared solution remains unchanged during the whole working process.

[0003] The existing three - tank water treatment pollution treatment devices generally do not have a liquid level display height. Some are displayed through transparent strips, resulting in inconvenient observation. Moreover, the existing sampling ports are installed on the dosing pipeline, but the sampling concentration results are inaccurate. The main reason is that the sampling port is located on the dosing pipeline, and there is a distance of 1 - 2 meters between the dosing pipeline and the inside of the box body. This makes the sampling concentration often the concentration of the reserved solution in the dosing pipeline rather than the concentration of the solution in the box body, resulting in inaccurate sampling concentration.

[0004] In addition, when the screw propeller doses dry powder and contacts with water, it will form lumps (granules), and the premixing effect is not good, resulting in a slow dissolution rate of the dry powder in the box body or small lumps that cannot be dissolved, making the concentration of the prepared solution insufficient or the effect not good.

[0005] On this basis, the utility model provides a three - tank water treatment pollution dosing device. Content of the Utility Model

[0006] In view of the above situation, to overcome the defects of the prior art, the utility model provides a three - tank water treatment pollution dosing device. The structure of the utility model is novel and ingeniously conceived, effectively solving the technical problems of inconvenient observation of the liquid level, inaccurate sampling concentration, and poor dissolution effect of dry powder lumps in the existing three - tank dosing device.

[0007] A three - tank water treatment pollution dosing device includes a box body. The inside of the box body is divided into a premixing tank, a ripening tank, and a storage tank by a plurality of low partitions and high partitions. It is characterized in that an upper viewing tube and a lower viewing tube placed outside are communicated with the upper and lower ends of the storage tank respectively. A liquid level tube is communicated between the upper viewing tube and the lower viewing tube. The lower viewing tube is threadedly connected with a sampling tube. The inside of the sampling tube is a cavity with an outer opening, and a sampling port is arranged on the side wall of the sampling tube.

[0008] Preferably, stirring devices are fixed inside the premixing tank, aging tank, and storage tank, and a stirring motor is connected to the upper end of the stirring device.

[0009] Preferably, the stirring device includes a stirring shaft connected to the stirring motor, stirring blades fixed on the stirring shaft, L-shaped stirring rollers symmetrically fixed at the bottom end of the stirring shaft, and stirring rods fixed on the stirring rollers and arranged staggeredly with the stirring blades.

[0010] Preferably, cables are transmitted inside the stirring shaft, stirring blades, stirring rollers, and stirring rods.

[0011] Preferably, a dry powder box is fixed to the upper end of the box body, a screw propeller is fixed to the lower end of the dry powder box, the end of the screw propeller is communicated with a premixer, the premixer includes a premixing cylinder communicated with the premixing tank, a funnel-shaped premixing hopper is rotatably installed in the premixing cylinder, the lower end of the premixing hopper is communicated with a premixing pipe, the lower end of the premixing pipe is communicated with a premixing disc, a plurality of circumferentially evenly distributed premixing ports are opened on the premixing disc, and a plurality of circumferentially evenly distributed cutting knives are fixed to the bottom of the premixing disc.

[0012] Preferably, a premixing bevel gear set is sleeved on the premixing pipe, and the premixing bevel gear set is connected to an external premixing motor.

[0013] Preferably, the screw propeller includes a screw pipe communicated with the dry powder box, a screw rod placed at the bottom end of the dry powder box is installed in the screw pipe, one end of the screw rod is connected to a screw bevel gear set, and the screw bevel gear set is connected to a screw motor.

[0014] Preferably, a sewage pipe is installed at the lower end of the side wall of the box body, an overflow pipe communicated with the storage tank is connected to the sewage pipe, a water inlet pipe is installed on the side wall of the box body, and the water inlet pipe is branched into a water supply pipe placed in the premixing tank and a pre-water pipe placed above the premixing cylinder.

[0015] The utility model has the following technical effects.

[0016] 1. Through the cooperation of the upper viewing tube, lower viewing tube, liquid level tube and sampling tube, the utility model can not only conveniently observe the liquid level of the box body, but also sample the solution concentration in the box body, and the sampled solution is the solution in the box body, improving the accuracy of the sampled concentration.

[0017] 2. On the basis of the original stirring shaft and stirring blades, the utility model adds stirring rollers and stirring rods, enlarging the stirring range of the stirring device. At the same time, with the cooperation of cable heating, the stirring dissolution rate is improved, and finally the stirring efficiency is improved.

[0018] 3. The utility model adds a premixing cylinder, and a rotatable premixing hopper, premixing pipe and premixing plate are added in the premixing cylinder, so that dry powder is premixed with water in advance, and after the dry powder is mixed with water, it is centrifugally thrown into the premixing tank through a cutter and a rotatable premixing port, preventing the dry powder from caking and improving the dissolution efficiency of the dry powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings are used to provide a further understanding of the utility model, and constitute a part of the specification. They are used together with the embodiments of the utility model to explain the utility model, and do not constitute a limitation to the utility model. In the drawings:

[0020] Figure 1 It is an enlarged three-dimensional schematic diagram of the liquid level pipe of the utility model.

[0021] Figure 2 It is a three-dimensional schematic diagram of the whole of the utility model.

[0022] Figure 3 It is a front view sectional schematic diagram of the utility model.

[0023] Figure 4 It is an enlarged three-dimensional schematic diagram of the premixer of the utility model.

[0024] Reference numerals:

[0025] 1 - box body; 2 - low partition board; 3 - high partition board; 4 - premixing tank; 5 - aging tank; 6 - storage tank; 7 - upper viewing tube; 8 - lower viewing tube; 9 - liquid level tube; 10 - sampling tube; 11 - sampling port; 12 - stirring motor; 13 - stirring shaft; 14 - stirring blade; 15 - stirring roller; 16 - stirring rod; 17 - cable; 18 - dry powder box; 19 - premixing cylinder; 20 - premixing hopper; 21 - premixing pipe; 22 - premixing plate; 23 - premixing port; 24 - cutter; 25 - premixing bevel gear set; 26 - premixing motor; 27 - spiral tube; 28 - spiral rod; 29 - spiral bevel gear set; 30 - spiral motor; 31 - sewage pipe; 32 - water inlet pipe; 33 - water supply pipe; 34 - pre - water pipe; 35 - overflow pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Regarding the foregoing and other technical contents, features and effects of the utility model, they will be clearly presented in the following detailed description of the embodiments in conjunction with the Figures 1 to 4 reference to the accompanying drawings. The contents mentioned in the following embodiments are all referenced to the drawings of the specification.

[0027] The following will describe the exemplary embodiments of the utility model with reference to the drawings.

[0028] The utility model relates to a three - tank water treatment pollution dosing device, which includes a box body 1. A control box is fixed on the box body 1 and is used to control subsequent water supply, stirring, dry powder feeding, liquid medicine conveying, etc. There are multiple control buttons on the control box. The box body 1 is overall rectangular with a cavity inside, and a box cover is buckled on the upper end. The inside of the box body 1 is divided into three tanks, namely a premixing tank 4, a ripening tank 5, and a storage tank 6 in sequence. A tank cover is buckled on the box cover corresponding to the upper end of each tank. The specific division is by two partitions with a relatively short distance between them, which are respectively called a lower partition 2 and a higher partition 3. A diversion cavity is formed between the lower partition 2 and the higher partition 3. For example, after the dry powder enters the premixing tank 4 for premixing, it passes through the lower end of the lower partition 2 and enters the diversion cavity, then flows into the ripening tank 5 from the upper end of the higher partition 3, and then enters the storage tank 6 through another lower partition 2 and higher partition 3. Finally, the medicine is added from the solution in the storage tank 6 into the water to be treated.

[0029] Most of the existing box bodies 1 are equipped with liquid level sensors to alarm when the liquid level is lower than the lowest liquid level and higher than the highest liquid level. However, most of them do not have liquid level display at normal liquid levels and can only remind when the range is exceeded. Some reserve vertical long holes on the wall of the box body 1, and a transparent plate is installed at the long holes. This installation method requires good sealing treatment during production, and the installation is relatively troublesome. The transparent plate used is also relatively thick. After long - term use, the oil stain on the surface will cause the clarity of the transparent plate to decrease.

[0030] During sampling, a sampling tube is installed on the metering pump and the dosing pipeline at the end of the storage tank 6. Since it is installed on the pipeline, the sampling concentration during sampling is the concentration of the solution in the pipeline. If the dosing pipeline does not have backflow or is not in use, it will cause inaccurate sampling concentration.

[0031] An upper viewing tube 7 and a lower viewing tube 8 are connected and installed on the outer side wall of the storage tank 6. The outer end of the upper viewing tube 7 is closed, the outer end of the lower viewing tube 8 is open, and internal threads are provided inside it. A transparent liquid level tube 9 is connected between the upper viewing tube 7 and the lower viewing tube 8. According to the principle of communicating vessels, the liquid inside the storage tank 6 will enter the liquid level tube 9 through the lower viewing tube 8 for display.

[0032] A sampling tube 10 is internally threaded and connected to the lower viewing tube 8. External threads matching the internal threads of the lower viewing tube 8 are provided on the outside of the sampling tube 10, and a sealing gasket is installed at the threaded connection of the sampling tube 10 and the lower viewing tube 8.

[0033] The inside of the sampling tube 10 is a cavity, the outer side end is open, and the inner side end is closed. A sampling port 11 communicating with the inside is provided on the side wall of the sampling tube 10.

[0034] During normal use, the upper viewing tube 7, the lower viewing tube 8, and the liquid level tube 9 play the role of liquid level display. At this time, the inner end of the sampling tube 10 plugs the lower viewing tube 8, and the sampling port 11 is placed outside the liquid level tube 9.

[0035] When sampling is required, the sampling tube 10 is rotated inward and the sampling tube 10 moves inward. When the inner end of the sampling tube 10 enters the storage tank 6 and the sampling port 11 enters the storage tank 6, the liquid in the storage tank 6 flows out from the sampling port 11 through the inside of the sampling tube 10 and from the outer end of the sampling tube 10. At this time, the side wall of the sampling tube 10 blocks the lower end of the liquid level tube 9 so that the liquid in the liquid level tube 9 does not flow out. It should be noted here that during the sampling operation, as the sampling tube 10 rotates inward, when the sampling port 11 moves below the liquid level tube 9, a small amount of liquid in the liquid level tube 9 will flow out from the sampling port 11. Therefore, when sampling, a small amount of solution in the liquid level tube 9 needs to flow out first. Because as the sampling tube 10 continues to move, the inner wall of the sampling tube 10 will block the liquid level tube 9, so only a small amount of solution will flow out.

[0036] Furthermore, since the premixing tank 4 and the maturation tank 5 are mainly used for mixing flocculants and water, and the storage tank 6 is mainly used for storing liquid medicine, most three-box dosing devices now only install stirring devices in the premixing tank 4 and the maturation tank 5, and do not install stirring devices in the storage tank 6. However, since the liquid is flowing in the three-box dosing device, if the dry powder agglomerates are not completely dissolved in the premixing tank 4 and the maturation tank 5, direct dosing and transportation through the storage tank 6 will result in poor liquid medicine effect. Therefore, the utility model installs stirring devices in the premixing tank 4, the maturation tank 5, and the storage tank 6, and each stirring device is connected to a stirring motor 12 placed on the box cover, and the stirring motor 12 is connected to the control box.

[0037] Furthermore, the current stirring devices all have 1-2 stirring blades 14 mounted on the stirring shaft 13. Since the three-box dosing device is a mobile dosing device, the simple stirring device leads to poor solution stirring effect. In order to increase the stirring effect in a short time, the stirring device includes a stirring shaft 13 connected to the stirring motor 12, and the stirring blades 14 are fixed on the stirring shaft 13. In addition, upward L-shaped stirring rollers 15 are symmetrically fixed on both sides of the lower end of the stirring shaft 13. The stirring rollers 15 are close to the box walls or low (high) partitions on both sides. Stirring rods 16 facing the stirring shaft 13 and arranged crosswise with the stirring blades 14 are fixed on the stirring rollers 15, thereby increasing the stirring area and improving the stirring efficiency in a short time.

[0038] Furthermore, in order to further improve the stirring efficiency in a short period of time, a through hole is opened inside the stirring shaft 13, the stirring blade 14, the stirring roller 15, and the stirring rod 16. The through hole is opened from the upper end of the stirring shaft 13 and is connected to the stirring blade 14, the stirring roller 15, and the stirring rod 16 in sequence, but the ends of the stirring blade 14, the stirring roller 15, and the stirring rod 16 are not connected to the outside. A cable 17 is passed through the through hole so that the cable 17 does not contact the solution. The cable 17 is connected to an external power supply and a control box.

[0039] Further, in order to further improve the dry powder mixing effect and prevent dry powder caking, a dry powder box 18 is fixed at the upper end of the box body 1. The dry powder box 18 has a trapezoidal cross-section. A vibration motor is fixed on the outer side wall of the dry powder box 18 to facilitate the downward transportation of dry powder. An observation window is also installed on the side wall of the dry powder box 18 to facilitate observing the internal feeding amount. A screw propeller is fixed at the lower end of the dry powder box 18. One end of the screw propeller communicates with a premixer. The premixer includes a closed premixing cylinder 19 with a cavity inside. The premixer communicates with the premixing tank 4. The end of the screw propeller is placed inside the premixing cylinder 19 to prevent dry powder from caking when encountering humid air. A funnel-shaped premixing hopper 20 is rotatably installed inside the premixing cylinder 19. Specifically, a rotating groove is opened on the inner wall of the premixing cylinder 19, and a rotating ring rotatably installed in the rotating groove is fixed on the side wall of the premixing hopper 20. The lower end of the premixing hopper 20 communicates with a premixing pipe 21 coaxially. The lower end of the premixing pipe 21 communicates with a premixing disc 22. A plurality of premixing ports 23 circumferentially distributed and communicating with the premixing pipe 21 are opened on the side wall of the premixing disc 22. A plurality of circumferentially distributed cutting knives 24 are fixed at the center of the premixing disc 22.

[0040] Further, in order to ensure the rotation of the premixing pipe 19, a premixing bevel gear set 25 is sleeved outside the premixing pipe 19. The premixing bevel gear set 25 includes a first bevel gear sleeved outside the premixing pipe 19. The first bevel gear meshes with a second bevel gear. The second bevel gear is connected by a premixing rotating shaft to a premixing motor 26 placed outside the premixing pipe 19 and on the box body 1. The premixing motor 26 is connected to the control box. A bearing seat and a gasket are sleeved on the premixing rotating shaft.

[0041] Further, the screw propeller includes a screw pipe 27 communicating with the bottom of the dry powder box 18. The end of the screw pipe 27 is placed inside the premixing pipe 19 and above the premixing hopper 20. A horizontally arranged screw rod 28 is installed between the screw pipe 27 and the bottom of the dry powder box 18. The other end of the screw rod 28 is installed with a screw bevel gear set 29. The screw bevel gear set 29 includes a third bevel gear sleeved on the screw rod 28. The third bevel gear meshes with a fourth bevel gear. The fourth bevel gear is coaxially connected with a screw motor 30. The screw motor 30 is connected to the control box.

[0042] Further, a sewage discharge pipe 31 is installed at the lower end of the side wall of the box body 1. The sewage discharge pipe 31 communicates with the premixing tank 4, the curing tank 5, and the storage tank 6 through a plurality of pipes respectively. The sewage discharge pipe 31 is connected to the inside of the premixing tank 4 through an overflow pipe 35. A water inlet pipe 32 is also installed above the sewage discharge pipe 31. A pressure gauge, a solenoid valve, and a flow meter are installed on the water inlet pipe 32. Then, it is respectively connected to a water supply pipe 33 placed inside the premixing tank 4 and a pre-water pipe 34 communicating above the premixing cylinder 19 through a water distribution pipe. Solenoid valves are installed on the water inlet pipe 32, the water supply pipe 33, and the pre-water pipe 34. The solenoid valves are connected to the control box.

[0043] When premixing, put the dry flocculant powder into the dry powder box 18. Driven by the spiral motor 30, the dry powder drives the spiral rod 28 to rotate. The spiral rod 28 drives the dry powder to move towards the premixing cylinder 19, and the dry powder enters the premixing hopper 20 of the premixing cylinder 19. At the same time, the water in the pre-water pipe 34 enters the premixing cylinder 19 and is mixed with the dry powder in advance. The water and the flocculant enter the premixing disc 22 through the premixing hopper 20 and the premixing pipe 21. The flocculant is cut and crushed by the cutter 24 in the premixing disc 22. Then, driven by the rotation of the premixing pipe 21, the premixing disc 22 rotates. The flocculant and water are centrifugally thrown out through the premixing port 23 and enter the premixing tank 4 again, so that the dry powder is premixed in advance, and is cut by the cutter and centrifugally thrown out through the premixing port 23 to minimize dry powder caking.

[0044] The dry powder entering the premixing tank 4, under the cooperation of the stirring shaft 13, the stirring blades 14, the stirring rollers 15 and the stirring rods 16, increases the stirring area, improves the stirring efficiency, and is heated in cooperation with the cable 17. Through heat transfer, the stirring shaft 13, the stirring blades 14, the stirring rollers 15 and the stirring rods 16 are heated to accelerate the dissolution rate of the dry powder.

[0045] The utility model is an automatic continuous configuration and dosing system for powdered polymer flocculants (such as PAM). The dry powder flocculant enters the premixer from the screw propeller and is premixed with clean water. The wetted material enters the premixing tank 4 for dilution and is prepared according to the required concentration. During the preparation process, the water volume is constant, and the flocculant is dosed proportionally. Thus, it is ensured that the concentration of the prepared solution remains unchanged throughout the working process. The prepared solution enters the storage tank 6 from the premixing tank 4 through the aging tank 5. A liquid level sensor is installed in the storage tank 6. When the liquid level in the storage tank 6 is at a high level, the preparation process automatically stops. When the solution drops to the middle liquid level, the batching process automatically restarts. Stirring devices are provided in the premixing tank 4, the aging tank 5 and the storage tank 6 to fully ensure the dilution and aging of the flocculant. When the solution drops to the low liquid level, the system gives an alarm, indicating that a certain part of the system may need to be inspected and repaired. The range of the prepared solution is 0 - 20000 liters per hour, and the concentration is 0.1% - 0.5%. Material selection: 304 material, 316 material, PP material. Chemical dosing pump selection: metering pump, screw pump. The standard configuration is a screw feeder, and a vacuum feeder or a screw rod feeder can also be selected.

[0046] The utility model has the following technical effects.

[0047] 1. Through the cooperation of the upper viewing tube, the lower viewing tube, the liquid level tube and the sampling tube, the utility model can not only conveniently observe the liquid level of the box body, but also sample the solution concentration in the box body. Moreover, the sampled solution is the solution in the box body, which improves the accuracy of the sampled concentration.

[0048] 2. On the basis of the original stirring shaft and stirring blades, the utility model adds stirring rollers and stirring rods, which enlarges the stirring range of the stirring device. At the same time, in cooperation with cable heating, it improves the stirring and dissolution rate, and finally realizes the improvement of stirring efficiency.

[0049] 3. By installing a premixing cylinder, the utility model adds a rotatable premixing hopper, premixing pipe and premixing plate in the premixing cylinder, so that the dry powder is premixed with water in advance, and after the dry powder and water are mixed, they are centrifugally thrown into the premixing tank through a cutter and a rotatable premixing port, preventing the dry powder from caking and improving the dissolution efficiency of the dry powder.

[0050] Although the content of the present utility model has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present utility model. After those skilled in the art have read the above content, various modifications and substitutions of the present utility model will be obvious. Therefore, the protection scope of the present utility model should be defined by the appended claims.

Claims

1. A three-tank water treatment pollution dosing device, comprising a tank (1), wherein the interior of the tank (1) is divided into a premixing tank (4), a maturation tank (5), and a storage tank (6) by a plurality of low partitions (2) and high partitions (3), wherein: The upper and lower ends of the storage tank (6) are connected to an upper sight tube (7) and a lower sight tube (8) disposed outside, and a liquid level tube (9) is connected between the upper sight tube (7) and the lower sight tube (8). The lower sight tube (8) is threadedly connected to a sampling tube (10). The interior of the sampling tube (10) is a cavity with an open outer end, and a sampling port (11) is provided on a side wall of the sampling tube (10).

2. A three-tank water treatment pollution dosing device according to claim 1, characterized in that: A stirring device is fixed inside the premixing tank (4), the maturation tank (5) and the storage tank (6), and a stirring motor (12) is connected to the upper end of the stirring device.

3. A three-box water treatment pollution dosing device according to claim 2, characterized in that: The stirring device comprises a stirring shaft (13) connected to a stirring motor (12), a stirring blade (14) being fixed to the stirring shaft (13), an L-shaped stirring roller (15) being symmetrically fixed to the bottom end of the stirring shaft (13), and a stirring rod (16) being fixed to the stirring roller (15) and arranged in an alternating manner with the stirring blade (14).

4. A three-tank water treatment pollution dosing device according to claim 3, characterized in that: The stirring shaft (13), the stirring blade (14), the stirring roller (15), and the stirring rod (16) are internally provided with a cable (17).

5. A three-tank water treatment pollution dosing device according to claim 1, characterized in that: A dry powder box (18) is fixed at the upper end of the box body (1), a screw propeller is fixed at the lower end of the dry powder box (18), a premixer is connected to the end of the screw propeller, the premixer comprises a premixing barrel (19) connected to the premixing tank (4), a funnel-shaped premixing bucket (20) is rotatably installed in the premixing barrel (19), the lower end of the premixing bucket (20) is connected to a premixing pipe (21), the lower end of the premixing pipe (21) is connected to a premixing disk (22), a plurality of premixing ports (23) evenly distributed around the circumference are formed on the premixing disk (22), and a plurality of cutting knives (24) evenly distributed around the circumference are fixed to the bottom of the premixing disk (22).

6. A three-tank water treatment pollution dosing device according to claim 5, characterized in that: The premixing tube (21) is sleeved with a premixing bevel gear set (25), and the premixing bevel gear set (25) is connected to an external premixing motor (26).

7. A three-tank water treatment pollution dosing device according to claim 6, characterized in that: The screw propeller comprises a screw tube (27) connected to the dry powder box (18), a screw rod (28) arranged at the bottom end of the dry powder box (18) is installed in the screw tube (27), one end of the screw rod (28) is connected to a screw bevel gear set (29), and the screw bevel gear set (29) is connected to a screw motor (30).

8. A three-tank water treatment pollution dosing device according to claim 7, characterized in that: A sewage pipe (31) is installed at the lower end of the side wall of the box body (1), and the sewage pipe (31) is connected to an overflow pipe (35) connected to the storage tank (6). A water inlet pipe (32) is installed on the side wall of the box body (1), and the water inlet pipe (32) is connected to a water supply pipe (33) placed in the premixing tank (4) and a premixing pipe (34) placed above the premixing cylinder (19).

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