Control valve for regulating gas flow

Description

[0001] The present invention relates to a control valve for regulating a gas flow.

[0002] A control valve for regulating a gas flow is known, for example, from DE 102013110518A1. This control valve is a regulating slide device comprising a housing that forms a channel through which a gaseous or liquid medium can flow and has at least one inlet longitudinal section and one outlet longitudinal section, as well as an adjustable control element for changing the flow cross-section of the channel and adjusting the flow rate. The regulating slide device further comprises a seat ring element provided in the channel. The control element has a first longitudinal section that has a circular cross-section with diameters that vary in the longitudinal direction.The control element is adjustable in the longitudinal direction of the channel along an adjustment path, wherein the control element rests on the seat ring element in a closed position and closes the channel and forms a flow-through annular gap with the seat ring element in an open position, and the varying diameters along the first longitudinal section of the control element are designed such that the change in the flow-through cross-sectional area of ​​the annular gap behaves in relation to the adjustment of the control element in the longitudinal direction such that the volume flow through the annular gap behaves almost linearly to the adjustment of the control element along the adjustment path.

[0003] Further valves are shown, for example, in FR 2 871 212 A1, US 2018 / 161784 A1, FR 1 231 509 A, US 2009 / 272929 A1.

[0004] This well-known control valve has proven very advantageous in practice. In particular, it significantly reduces pressure losses in the control system, thus saving energy costs.

[0005] However, it was found that this well-known control valve cannot be operated optimally for smaller pipe diameters, especially DN 50 to DN 200.

[0006] Against this background, the object of the present invention is to create a control valve that, on the one hand, significantly reduces pressure losses in the control system and, on the other hand, is also optimally suitable for smaller sizes DN 50 to DN 200 with regard to control accuracy. Furthermore, there is also the desire to create a measuring range within the control valve that enables very precise flow measurement.

[0007] This object is achieved by a control valve having the features of claim 1. The control valve according to the invention has an elongated housing which defines a flow channel and is divided into an inflow section, a drive section and an outflow section which are arranged along a longitudinal axis, wherein the gas flows through the flow channel from the inflow section via the drive section to the outflow section. Within the drive section, a gear device is provided which has an externally drivable output shaft lying parallel to the longitudinal axis and a circular slide element which is arranged displaceably along the longitudinal axis via the output shaft and has an outer valve seat surface which closes an annular gap defined between itself and an inner surface of the outflow section by means of a longitudinal displacement in the direction of flow.Furthermore, a flow element is provided which is attached to the transmission device at its end facing the inflow section and has a dome-shaped outer surface which directs the gas coming from the inflow section into an annular gap between the transmission device and the inner surface of the drive section. The circular slide element is conical in shape with a circular base surface and a lateral surface which defines a valve surface between the valve seat surface and the tip of the circular slide element, wherein a blind hole running parallel to the longitudinal axis is provided at the tip of the circular slide element. The inflow section has a cylindrical flow channel which has a constant diameter essentially over its entire longitudinal extent and widens conically at the transition to the drive section.Preferably, the drive section has a flow channel whose diameter initially widens conically in the flow direction and then remains substantially constant. At least one opening is provided in the inflow section for the insertion of at least one measuring element, preferably a flow measuring element.

[0008] The control valve according to the invention is designed so that the inflowing gaseous medium is first directed outward via the flow element into a circular or annular gap-shaped flow channel section. This creates a flow-calmed area upstream of the flow element, which is optimal for a measurement, for example, a flow measurement.

[0009] The gaseous medium flows through the flow channel section further downstream past the outer valve seat surface and along the circular slide element into the outlet section. Because the medium flows only in a circular flow channel, hardly any flow vortexes are created, so pressure losses in the control range of the control valve are low. Furthermore, the circular slide element is arranged to close in the direction of flow, so it does not have to work against the flow pressure when closing. This allows for a significantly smaller drive due to the lower torque required, but without compromising control accuracy.

[0010] The object of the invention is thus completely solved.

[0011] In a preferred embodiment, the transmission device has a drive shaft extending perpendicular to the output shaft and connected to it via a transmission. One end of the output shaft is located outside the housing and can be coupled to a drive device. The transmission is preferably designed as a deflection transmission, preferably as a bevel gear transmission.

[0012] These measures have the advantage of enabling a compact gear unit that allows for highly precise control behavior. The gear unit allows for reproducible adjustment of even very small adjustment ranges of the rotary slide element.

[0013] Preferably, a ring element is provided in the outflow section concentrically to the longitudinal axis, said ring element having at least two radially extending spokes which hold a pin extending parallel to the longitudinal axis, wherein the pin engages in the blind hole in order to support and guide the circular slide element.

[0014] These measures have proven particularly advantageous. In particular, they improve the guidance of the rotary valve element via the pin, thus increasing control accuracy and making it more reproducible. The conical design of the rotary valve element allows for a very good flow pattern with low vortex formation.

[0015] In a preferred development, a surface line of the surface of the circular slide element is a non-straight curve and the inner surface of the outflow section has a control contour, wherein the control contour and the valve seat surface are matched to one another in such a way that the change in the flow-through cross section of the annular gap between the inner surface and the valve seat surface is matched to an adjustment path of the circular slide element in the longitudinal direction in such a way that a substantially linear operating characteristic curve is achieved.

[0016] To achieve a linear operating characteristic during operation, a non-linear control valve characteristic is required. The inventor recognized that with increasing flow, the dynamic pressure loss increases, and therefore the control valve must open its cross-section disproportionately to maintain a constant flow rate.

[0017] Further preferably, the control contour has at least one control contour end region, which is designed such that, when the control valve is closed, it at least partially supports the valve seat surface of the circular slide element in the flow direction and cooperates with it in a sealing manner. Further preferably, the control contour has a non-rectilinear profile.

[0018] These measures achieve a further optimization of the control behavior of the control valve.

[0019] In a preferred development, the output shaft is designed as a spindle, preferably as a trapezoidal thread spindle and interacts with a spindle nut, wherein the spindle nut is coupled to the circular slide element.

[0020] This design has proven to be particularly advantageous because it enables reproducible adjustment of the circular slide element with very small tolerances.

[0021] In a preferred development, the inflow section, the drive section and the outflow section each have a flange at their longitudinal ends, wherein the sections are detachably connected to one another via the flanges.

[0022] This measure has the advantage of achieving a high degree of flexibility in terms of installation situations by dividing the control valve into three sections. In other words, the control valve can be easily adapted to different conditions, for example, by using inlet or outlet sections of different lengths. Furthermore, this naturally also reduces manufacturing and assembly costs.

[0023] Preferably, the flow channel in the drive section has, at least in sections, two separate annular segment-shaped channels. Further preferably, the outflow section has, in an upstream region, an annular flow channel whose diameter in the flow direction initially corresponds to the diameter of the adjacent drive section and then tapers conically to a diameter that essentially corresponds to the diameter of the inflow section, wherein the annular flow channel merges into a circular flow channel.

[0024] These designs of the various sections of the flow channel have proven to be particularly advantageous in order to achieve, on the one hand, a flow-calmed measuring area in the inflow section and, on the other hand, to achieve a low-turbulence and reproducible flow with low pressure losses over the entire length of the control valve.

[0025] Further preferably, a flow straightening element, preferably a perforated disc, is provided at the upstream end of the inflow section.

[0026] This measure has the advantage of allowing a measuring element to be easily integrated into the control valve. Furthermore, the flow straightener element allows the flow to be further optimized to achieve particularly good measurement results.

[0027] The drive device is preferably designed as a pneumatic drive device, a hydraulic drive device or an electric drive device.

[0028] In a preferred further development, the control valve is dimensioned so that it can be used in a pipeline with a nominal diameter between DN 50 and DN 200.

[0029] The control valve according to the invention can be used particularly well with these smaller pipe diameters.

[0030] The control valve according to the invention can be used particularly advantageously as a control valve in a flotation system for regulating the gas flow, i.e., the gas quantity, into several tanks of the flotation system. This application in particular can achieve very significant energy savings compared to previous solutions. If flotation systems are equipped with the control valve according to the invention instead of the previous control valves, significantly more economical operation can be achieved. Furthermore, the high control precision significantly improves the flotation process and increases system performance.

[0031] The problem with flotation systems with regard to regulating the air volume is that, on the one hand, several tanks are supplied with air via a common compressor (via a common piping system), and on the other hand, the conditions in the tanks are different and can also change dynamically. For example, the liquid levels in the tanks vary, so the air must be introduced against different static pressures (while maintaining a constant air volume). The density of the liquids in the tanks can also change, causing the static pressures to change. Without control valves in the lines to the tanks that can respond quickly and precisely to such pressure changes in order to keep the air volume in the tanks constant despite changing pressure, the amount of air introduced into a tank would constantly change. It is clear that this would impair the flotation process itself.

[0032] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0033] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. These show: Figure 1 shows a side view of the control valve according to the invention with a drive device; Figure 2 shows a side sectional view of the control valve in the open state; Figure 3 shows a side sectional view of the control valve in the closed state, the view being rotated by 90° compared to the view of Figure 2 rotated; Figure 4 shows a sectional view along the line AA from Figure 2 ; Figure 5 a sectional view along the line BB and a sectional view along the line CC of the Figure 2; and Figure 6 is a perspective view of the control valve according to the invention, wherein the outflow section is shown offset.

[0034] In Figure 1 A control valve according to the invention is shown in a sectional view and designated by reference numeral 10. The control valve serves in particular to regulate the flow rate of a gaseous medium, preferably air, for example, in a flotation system. The control valve 10 is designed so that it can be retrofitted into existing piping systems.

[0035] The control valve 10 is detachably coupled to a drive device 12, which serves for the controlled opening and closing of the control valve 10. Depending on the application, the drive device 12 can have an electric drive, a pneumatic drive, or a hydraulic drive. Since the drive device 12 is a known component, it will not be discussed further. However, it is important that the drive device 12 is detachably attached to the control valve so that it can be replaced at any time.

[0036] The control valve 10 is divided into three sections: an inlet section 14 with a length L1, a drive section 16 with a length L2, and an outlet section 18 with a length L3. The three sections 14, 16, and 18 form independent assemblies that are detachably connected to one another and can therefore be replaced at any time. For example, it would be conceivable to design the inlet section 14 with different lengths depending on the application.

[0037] As can be seen from Figure 1 The three sections 14, 16 and 18 are arranged along a longitudinal axis L, resulting in a quasi-rectilinear flow path through the control valve 10. In other words, this means that an inlet opening 20 of the control valve 10 is concentric with an outlet opening 22.

[0038] The flow direction of the gaseous medium is in Figure 1represented by the arrows S. The gaseous medium flows into the control valve 10 through the inlet opening 20 and exits it through the outlet opening 22. It should be noted at this point that the control valve 10 can only be used advantageously in this way. In other words, if the gaseous medium flowed in the opposite direction through the control valve 10, the aforementioned advantages would not be achieved. The flow direction of the control valve 10 is therefore of great importance, unlike with other control valves.

[0039] The exact structure of the control valve 10 will be explained below using the Figure 2-5 be explained in more detail.

[0040] In Figure 2 is the control valve 10 of Figure 1 shown enlarged, but the section plane has been rotated by 90°.

[0041] The inflow section 14 comprises a tubular housing 24 with a flange 26 at both ends. The tubular housing 24 forms a cylindrical flow channel 28 with an inner diameter D1 in the region of the inflow opening 20. The inner diameter of the flow channel 28 remains constant over almost the entire length L1, but then widens—as seen in the flow direction—to an inner diameter D2. The length L1 is preferably approximately 200 mm.

[0042] As from Figure 2As can be seen, the housing 24 has a tubular (with a circular or oval cross-section) branch 30, which extends outward approximately halfway along the length of the inflow section 14 at right angles to the longitudinal axis L. The branch 30 ends with a flange 32. The branch 30 thus forms a channel 34, which creates a connection from the outside into the flow channel 28. A measuring instrument, in particular a flow measuring instrument 36, can be introduced into the flow channel 28 via this channel 34. Figure 4 Branch 30 is shown even more clearly. In particular, it can be seen here that the measuring instrument has two sensor tips positioned in the center of the flow channel. It has proven particularly advantageous to arrange the sensor tips approximately 100 mm apart from the downstream end of the inflow section in the longitudinal direction.

[0043] The special design of the control valve 10 allows for a very homogeneous flow in the flow channel 28, making measurement particularly advantageous in this area. The measurement results are very accurate and reproducible.

[0044] Depending on the application, a flow straightener element 38 can be provided in the area of ​​the inlet opening 20, also to improve measurement. A perforated disc 39 is preferably used for this purpose. The flow straightener element 38 can also be used for targeted pressure reduction in connected control circuits with different pressures and a common gas supply. In this way, for example, the noise level and control valve wear can be reduced and the control quality can be increased.

[0045] The inlet section 14 is adjoined by the drive section 16, which also has a tubular housing 40, which is also delimited in the longitudinal direction by two flanges 26. The inlet section 14 and drive section 16 are detachably and gas-tightly connected to one another via the adjacent flanges 26. The inlet opening of the drive section 16 is the same size as the outlet opening of the inlet section 14 and therefore has an inner diameter D2.

[0046] The housing 40 forms a flow channel 42, which widens - viewed in the flow direction - from the inner diameter D2 to a larger inner diameter D3. As can be seen from Figure 2 The longer length of the drive section 16 has the inner diameter D3. In particular, the outlet opening of the drive section 16 has the inner diameter D3.

[0047] Located within and held by the housing 40 is a gear mechanism 50 comprising all the components necessary for regulating the gas flow. These components, which will be discussed in detail below, are surrounded by a flow-optimized housing 52 or housing cladding, which is preferably arranged centrally to the longitudinal axis L in the flow channel 42. It should also be noted at this point that the housing 52 is rigidly connected to the housing 40 of the drive section 16, but extends from the drive section 16 into the adjacent outflow section 18. In other words, this means that the two sections 16, 18 remain detachable from one another, even though part of the housing 52 is located in the outflow section 18.

[0048] As already mentioned, the housing 52 is designed to be flow-optimized so that the gaseous medium can flow through the flow channel 42 with as little resistance as possible. For this purpose, the housing 52 has a dome-shaped flow element 54 at its upstream end, which faces the inflow section 14. The flow element 54 has the task of directing the inflowing gas outward into the flow channel 42. It should be noted at this point that the flow channel 42 is circular in shape at the upstream end of the drive section 16. In other words, the center of the flow channel 42 is occupied by the housing 52.

[0049] The flow element 54, with its convex shape, has a decisive influence on the flow in the inlet section 14 and thus also on the measurement results achievable there. The flow element 54 acts as an integrated flow straightener and thus stabilizes the flow profile in the inlet section 14.

[0050] At the downstream end of the housing 52 facing the outlet opening 22, a control element is provided which is designed as a circular slide element 60. In Figure 2 This circular slide element 60 is shown in a fully open position and in Figure 3 in a fully closed position. The circular slide element 60 is arranged in the housing 52 so that it can be displaced longitudinally, so that by moving the circular slide element 60, the cross-sectional area of ​​the flow channel through which the fluid flows can be changed.

[0051] The circular slide element 60 has a truncated cone shape with a circular base 62, as in Figure 3 shown, and a lateral surface 64 which extends from the base surface 62 to a tip 66. The lateral surface 64 has a non-rectilinear surface line 68. Starting from the base surface 62, the diameter of the circular slide element 60 - seen in the longitudinal direction - initially reduces greatly, and then changes only slightly towards the tip 66.

[0052] In the area of ​​the base surface 62, a sealing ring 69 is provided, which forms a valve seat surface of the circular slide element 60. As can be seen from Figure 3 The circular slide element 60 is arranged concentrically to the longitudinal axis L. The sealing ring 69, ie the valve seat surface, forms with the radially opposite inner surface of the outflow section 18 the flow cross-section which is changed to regulate the flow rate.

[0053] At the tip 66 of the circular slide element 60, a bore 70 is provided, which is designed as a blind hole. The bore 70 extends along the longitudinal and symmetrical axis of the circular slide element 60.

[0054] The bore 70 is designed to receive a pin 72. The pin 72 is fixedly mounted on a ring element 74 opposite the outlet section 18, as shown, for example, in Figure 5 which, in turn, is arranged in the region of the outflow opening 22 of the outflow section 18. The ring element 74 has an outer ring with spokes 75 extending therefrom, which hold the pin 74 at one of its two ends. Preferably, at least three spokes are provided. The other end of the pin 74 projects into the bore 70, so that the circular slide element 60 is held in the region of its tip 66 on the one hand and guided on the other hand when the circular slide element 60 moves in the longitudinal direction.

[0055] Referring to the Figure 3 A bushing-shaped element 80 is provided in the area of ​​the base surface 62 of the circular slide element 60. It is firmly connected to the base surface 62. A spindle nut 82 is mounted within the element 80, which interacts with a threaded spindle 84. The threaded spindle 84 is arranged within the housing 52 concentrically to the longitudinal axis L and serves as an output shaft.

[0056] The threaded spindle 84 or the output shaft is coupled at its upstream end to a gear 88, which is preferably designed as a bevel gear 90. The gear 88 serves to transmit the energy introduced via a drive shaft 92 to the output shaft. The drive shaft 92 extends perpendicular to the longitudinal axis L in the drive section 16 into the housing 54. The gear 88 thus converts the rotational movement about the axis perpendicular to the longitudinal axis L into a rotational movement about the longitudinal axis L.

[0057] As can be seen from a comparison of the Figure 2 and 3 The drive shaft 92 also extends through a part of the flow channel 42, so that this is blocked at least in sections. The sectional view along the line BB from Figure 2 , which is shown in Figure 5, illustrates that in this area the flow channel consists of two separate circular ring segment-shaped openings 94.

[0058] The drive shaft 92 is connected to the drive device 12, in particular detachably connected, so that the drive device 12 can be replaced without simultaneously replacing the gear 88.

[0059] The outflow section 18, like the other two sections 12, 14, has a tubular housing 98, as shown in Figure 3which has a flange 26 at each of its two ends. The housing 98 is connected in a gas-tight manner to the drive section 16 via the flange 26, wherein the inner diameter of the inlet opening of the outlet section 18 corresponds to the diameter D3 of the drive section 16.

[0060] The housing 98 forms a flow channel 100 that tapers in the direction of flow. The inner diameter of the flow channel 100 decreases from the inner diameter D3 to the inner diameter D1 at the outlet opening 22.

[0061] As already mentioned, the housing 52 of the gear device 50 extends into the flow channel 100 of the outflow section 18, so that only a circular cross-section is available for the flow.

[0062] In the area of ​​the transition from the inner diameter D3 to the inner diameter D1, the inner surface of the flow channel 100 has a control contour 102, which determines the control behavior of the control valve. As can be seen from the Figure 2 and 3 When the circular slide element 60 is moved in the longitudinal direction, the cross section between the sealing ring 69 and the inner surface of the flow channel is changed. In the fully open state of the control valve 10, as in Figure 2 shown, the cross-section or cross-sectional area is maximum. In the fully closed state of the control valve 10, as in Figure 3As shown, the cross-sectional area is zero, meaning that the sealing ring 69 is in sealing contact with the inner surface. By adjusting the circular slide element in the longitudinal direction, a relatively large stroke can be achieved, which allows for very precise control. In other words, the large stroke enables a high resolution in the adjustment of different opening cross-sections of the control valve.

[0063] As previously mentioned, the circular slide element 60 has a non-rectilinear surface line 68. This surface line is selected such that the cross-sectional area of ​​the flow channel increases rapidly after the sealing ring 69. Furthermore, irregularities 104 can be provided in the control contour 102 in order to adapt the control behavior to specific conditions. In particular, a linear operating characteristic can be achieved by selecting the control contour 102.

[0064] In Figure 6The control valve 10 is shown again in a perspective view, with the outflow section 18 detached from the drive section 16 and, in particular, exposing the circular slide element 60. The special shape of the outer surface 64 of the circular slide element 60 with its non-rectilinear surface line is clearly visible. Furthermore, the bushing-shaped element 80, which is connected to the circular slide element, is shown. Otherwise, the same parts as in the previous figures are identified by the same reference numerals.

[0065] The operation of the control valve 10 is now as follows:

[0066] The control valve 10 can be installed into an existing piping system, but the flow direction must be observed, as the control valve 10 can only be used effectively in one direction. The control valve 10 is specifically designed for nominal diameters from DN 50 to DN 200. For larger nominal diameters, other valves, in particular the regulating slide valve mentioned in the introduction to the description, are more suitable.

[0067] The gas flowing through the inlet opening 20 passes through the flow channel 28 and, at the end of the inlet section 14, is guided by the flow element 54 into the outer annular region of the flow channel 42. Due to the special shape of the flow element 54, a reproducible flow profile is realized, particularly in the center (seen in the radial direction) of the flow channel 28, where the flow measuring instrument is provided.

[0068] The gas deflected by the flow element 52 flows along the inner surface of the flow channel 42, i.e., between the housing 40 and the housing 52, through the two circular ring-segment-shaped openings 54 into the flow channel 100 of the outflow section 18. This region of the flow channel 100 is circular up to the outflow opening 22, with the cross-sectional area of ​​the flow channel increasing continuously, preferably non-linearly, from the sealing ring 69 to the tip of the circular slide element 60. The Venturi effect occurring in this region contributes significantly to the low energy losses of the control valve 10.

[0069] If the gas flow rate is to be reduced, the circular slide element 60 is displaced in the flow direction via the drive device 12, so that the cross-sectional area through which the gas flows decreases, preferably linearly, with the adjustment travel due to the control contour 102. The flow rate can be measured stably via the flow measuring instrument 36, allowing a control device (not shown) to set and maintain the desired flow rate.

[0070] It's important to note at this point that, when the control valve 10 is properly installed, the circular slide element 60 does not have to work against the pressure of the incoming gas when closing. Rather, the control valve 10 is closed by a displacement of the circular slide element 60 in the direction of flow. This design allows for smaller torques, allowing the components of the transmission device 50 to be designed smaller.

[0071] To further optimize the flow behavior in the area of ​​the circular slide element 60, guidance by pin 72 is provided. This guidance prevents, for example, tilting of the circular slide element 60 relative to its longitudinal axis, which would lead to asymmetries in the flow channel.

[0072] Overall, the control valve 10 according to the invention enables particularly precise, reproducible control of the flow rate of a gas, especially for pipeline systems with a nominal diameter of DN 50 to DN 200.

[0073] An advantageous possible application of this control valve 10 according to the invention can be seen in so-called flotation systems. Such flotation systems utilize the introduction of air into large liquid tanks to separate solids, such as ores. The control valve 10 according to the invention can now be very easily integrated into existing piping systems of such flotation systems. The energy consumption for introducing the air can thus be significantly reduced compared to previous systems. Furthermore, the amount of air supplied to the tanks of the system can be controlled very precisely, even when the pressure conditions in the tanks change dynamically. This consistency in the amount of air supplied is of great importance with regard to the processes in the tanks.

Claims

1. Control valve for controlling a gas through-flow, comprising an elongate housing (24, 52, 98), which delimits a flow channel (28, 42, 100) and is divided into an inflow portion (14), a drive portion (16), and an outflow portion (18), which are arranged adjacent to one another along a longitudinal axis (L), wherein the gas flows through the flow channel from the inflow portion (14) via the drive portion (16) to the outflow portion (18) when the control valve is used as intended, a gearing mechanism (50), which is provided within the drive portion (16) and has an externally drivable output shaft (84) parallel to the longitudinal axis and a rotary slide element (60), which is arranged displaceably along the longitudinal axis via the output shaft and has an outer valve seat surface (69), which closes an annular gap, defined between itself and an inner surface (102) of the outflow portion (18), by a longitudinal displacement in the flow direction, and a flow element (54), which is provided on the gearing mechanism (50) at its end facing the inflow portion and has a dome-shaped outer surface, which directs the gas coming from the inflow portion into an annular gap between the gearing mechanism (50) and the inner surface of the drive portion; characterized in that the inflow portion has a cylindrical flow channel (28), which has a constant diameter (D1) substantially over the entire longitudinal extent and widens conically at the transition to the drive portion, and in that at least one opening for inserting at least one measuring element (36), preferably a flow measuring element, is provided in the inflow portion; and the rotary slide element (60) is conical with a circular base surface and a lateral surface (64), which is provided between the valve seat surface (69) and the tip of the rotary slide element, wherein a blind hole (70) parallel to the longitudinal axis is provided at the tip (66) of the rotary slide element.

2. Control valve according to claim 1, characterized in that the gearing mechanism has a drive shaft (92), which extends perpendicularly to the output shaft and is connected thereto via a gear, wherein one end of the output shaft is located outside the housing and can be coupled to a drive mechanism.

3. Control valve according to claim 2, characterized in that the gear is designed as an idler gear, preferably as a bevel gear (90).

4. Control valve according to one of the preceding claims, characterized in that the valve seat surface (69) is designed as a sealing ring.

5. Control valve according to claim 1 or 4, characterized in that a ring element (74) is provided in the outflow portion concentrically with the longitudinal axis and has at least two radially extending spokes (75), which hold a pin (72) extending in parallel with the longitudinal axis, wherein the pin engages in the blind hole in order to support and guide the rotary slide element.

6. Control valve according to claim 1 or 4, characterized in that a surface line (68) of the lateral surface (64) of the rotary slide element is a non-straight curve and the inner surface of the outflow portion has a control contour (102), and the control contour and the valve seat surface (69) are matched to each other in such a way that the change in the flowed-through cross-section of the annular gap between the inner surface and the valve seat surface is matched to an adjustment path of the annular slide element in the longitudinal direction such that a substantially linear operating characteristic curve is achieved.

7. Control valve according to claim 6, characterized in that the control contour has at least one control contour end area, which is designed such that, in the closed state of the control valve, it at least partially supports the valve seat surface (69) of the rotary slide element in the flow direction and cooperates with it in a sealing manner, wherein the control contour (102) preferably has a non-rectilinear course.

8. Control valve according to one of the preceding claims, characterized in that the output shaft is designed as a spindle, preferably as a trapezoidal thread spindle, and cooperates with a spindle nut (82), wherein the spindle nut (82) is coupled to the rotary slide element (60), or in that the gearing mechanism has a gear cover (52), which has a flow-optimized outer surface, wherein the gear cover surrounds both the drive shaft and the output shaft.

9. Control valve according to claim 1, characterized in that the drive portion has a flow channel (42), of which the diameter initially widens conically, when viewed in the flow direction, and then remains substantially constant, wherein the flow channel in the drive portion preferably has, at least in portions, two separate circular-ring-segment-shaped channels (94).

10. Control valve according to claim 1, characterized in that the outflow portion (18) has, in an upstream area, a toroidal flow channel (100), of which the diameter in the flow direction initially corresponds to the diameter of the adjacent drive portion and then tapers conically to a diameter that substantially corresponds to the diameter of the inflow portion, wherein the toroidal flow channel transitions into a circular flow channel.

11. Control valve according to claims 6 and 10, wherein the control contour (102) is located in the conically tapered area of the outflow portion.

12. Control valve according to claim 1, characterized in that a flow straightener element (38), preferably a perforated disk (39), is provided in the inflow portion at the upstream end.

13. Control valve according to one of the preceding claims, characterized in that it is dimensioned such that it can be used in a pipeline with a nominal diameter between DN 50 and DN 200.

14. Flotation plant for separating solids, in particular ores, with multiple tanks and at least one line for supplying gas to each tank, wherein a control valve according to one of claims 1 to 13 is provided in the line to each tank to control the gas flow into each tank.

15. Use of a control valve according to one of claims 1 to 13 in a flotation plant for controlling the gas inflow into a tank of the flotation plant.