Compressed gas dryer, compressor device and method for drying compressed gas

Abstract

The present invention relates to a compressed gas dryer, a compressor apparatus, and a method for drying compressed gas. A compressed gas dryer comprises: a pressure vessel having a drying zone and a regeneration zone therein; a drum provided with a regenerable desiccant; a drive device for rotating the drum to move the desiccant sequentially through the drying zone and the regeneration zone; an inlet for supplying the compressed gas to be dried; and an outlet for discharging the dried compressed gas. The drive device includes a motor provided with a start / stop controller.

Description

Technical Field

[0001] The invention relates to a dryer for compressed gas, a compressor installation provided with such a dryer and a method for drying compressed gas, for example air. Background Art

[0002] Dryers for compressed gas are known. These dryers comprise a pressure vessel comprising a drying zone, a regeneration zone, and optionally a cooling zone; and a rotatable drum within the pressure vessel containing a regenerable desiccant. The pressure vessel comprises an inlet for supplying the compressed gas to be dried into the drying zone and an outlet for discharging the dried gas. Hot regeneration gas is introduced into the regeneration zone to regenerate the desiccant. The dryer also comprises a drive for rotating the drum to move the desiccant sequentially through the drying and regeneration zones.

[0003] Compressed gas that has been heated by compression and therefore has a lower relative moisture content can be used as regeneration gas for regenerating the desiccant. In a first known embodiment, a portion of the compressed gas supply stream is branched off for regeneration and subsequently reintroduced into the compressed gas stream. In a second known embodiment, a portion of the dried compressed gas exhaust stream is branched off and heated for regeneration and subsequently reintroduced into the compressed gas stream. In a third known embodiment, the entire supply stream of compressed gas to be dried is first directed through a regeneration zone and then through a drying zone.

[0004] Other embodiments are also known, for example as disclosed in WO 2015 / 039193 A2.

[0005] It is known to combine the partial flow that has been used for regeneration with the supply flow of compressed gas to be dried, combining it upstream of the inlet side of the drying zone. In this regard, a Venturi ejector or a blower is used to generate a pressure difference that maintains the partial flow. Summary of the Invention

[0006] It is an object of the present invention to remedy one or more disadvantages of the prior art.

[0007] The object of the present invention is to provide a dryer or a drying device for compressed gas, in which the operation of the dryer can be better controlled by simple means.

[0008] The compressed gas can be, for example, air, but can also be other gases. After drying, the gas can be used in a downstream compressed air network for a wide range of purposes, such as for pneumatic conveying, driving pneumatic tools, etc.

[0009] In a first aspect of the present invention, which may be combined with other aspects or embodiments herein, the present invention provides a dryer or drying device for drying compressed gas, comprising: a pressure vessel having a rotationally symmetrical portion (e.g., cylindrical), having a drying zone and a regeneration zone in the rotationally symmetrical portion; a drum arranged in the rotationally symmetrical portion, the drum being provided with a regenerable desiccant; a driving device for rotating the drum relative to the rotationally symmetrical portion, i.e., rotating the drum and / or the rotationally symmetrical portion so that the desiccant moves successively through the drying zone and the regeneration zone; an inlet for supplying compressed gas to be dried toward the drying zone; an outlet for discharging the dried compressed gas; and a first connecting line for branching off a branch flow of the compressed gas to be dried or a branch flow of the compressed gas after drying, and directing the branch flow to the regeneration zone. The dryer further comprises a controllable device configured to combine the partial flow for regeneration with a supply flow of compressed gas to be dried and to control the flow rate of the partial flow relative to the supply flow; at least one sensor configured to measure at least one measurement value related to the operation of the dryer; and a control unit communicatively connected to the at least one sensor and the controllable device and configured to process the at least one measurement value, determine at least one control signal for controlling the controllable device based on the at least one measurement value, and apply the at least one control signal to the controllable device. Based on one or more measurement values, the control unit can influence the operation of the dryer by adjusting the control signal and, therefore, at least the flow rate of the partial flow for regeneration, in order to achieve, for example, a desired value for the pressure dew point and / or a desired stability of the pressure dew point within a defined range.

[0010] In an embodiment of the present invention, the set of sensors may include one or more sensors for directly or indirectly measuring the supply flow rate and / or the diverted flow rate. The control unit may be configured to evaluate the directly or indirectly measured supply flow rate and / or diverted flow rate and apply a control signal based on the evaluation. The set of sensors may include, for example, a rotational speed sensor for measuring the rotational speed of a compressor supplying the supply flow as a measure of the supply flow rate; and / or a pressure sensor for measuring a pressure drop across the controllable device as a measure of the diverted flow rate used for regeneration.

[0011] In an embodiment of the present invention, the set of sensors may include one or more of the following sensors: a temperature sensor for measuring the temperature difference between the inlet side and the outlet side of the regeneration zone; a temperature sensor for measuring the temperature difference between the inlet side and the outlet side of the drying zone; and a pressure dew point sensor at the outlet for measuring the pressure dew point of the compressed gas exhaust flow after drying.

[0012] In an embodiment of the present invention, the first connecting line may be provided with a heat exchanger for heating the branch flow branched off and supplied to the dryer for regeneration by means of the compressed gas to be dried, and the set of sensors may include one or more of the following sensors: a pressure sensor for measuring the pressure difference between the outlet side of the drying zone and the inlet side of the regeneration zone; and a pressure sensor for measuring the pressure drop caused by the heat exchanger in the branch flow and / or in the supply flow.

[0013] In an embodiment of the present invention, the dryer may include at least one cooling device, which is configured to cool the compressed gas supply flow, and / or cool the branch flow for regeneration, and / or cool the combined flow; and the set of sensors may include one or more of the following sensors: a temperature sensor for measuring the temperature of the corresponding flow upstream and / or downstream of the corresponding cooling device; a pressure sensor for measuring the pressure drop caused by the corresponding cooling device in the corresponding flow; and a temperature sensor for measuring the temperature of the coolant used for cooling upstream and / or downstream of the cooling device.

[0014] In an embodiment of the present invention, the controllable device may include a venturi ejector configured to merge the split flow and the supply flow, provided with a controllable opening, and having a driving device for driving the controllable opening based on a control signal.

[0015] In an embodiment of the present invention, in addition, the control unit can be communicatively connected to a drive device for rotating the drum relative to the rotationally symmetrical portion, and the control unit can be configured to determine a second control signal for the drive device based on the at least one measurement value and apply the second control signal to the drive device.

[0016] In an embodiment of the present invention, in addition, the control unit can be communicatively connected to one or more of the at least one cooling device and can be configured to determine at least one third control signal for the at least one cooling device based on the at least one measurement value and apply the corresponding third control signal to the corresponding cooling device.

[0017] In a second aspect of the present invention, which may be combined with other aspects or embodiments herein, the present invention provides a dryer or drying device for drying compressed gas, comprising: a pressure vessel having a rotationally symmetrical portion (e.g., cylindrical) with a drying zone and a regeneration zone in the rotationally symmetrical portion; a drum disposed in the rotationally symmetrical portion, the drum being provided with a regenerable desiccant; a drive device for rotating the drum relative to the rotationally symmetrical portion, i.e., rotating the drum and / or the rotationally symmetrical portion so that the desiccant moves sequentially through the drying zone and the regeneration zone; an inlet for supplying the compressed gas to be dried toward the drying zone; an outlet for discharging the dried compressed gas; and a first connecting line for branching off a partial flow of the compressed gas to be dried or a partial flow of the dried compressed gas and directing the partial flow to the regeneration zone. The drive device for rotating the drum relative to the rotationally symmetrical portion comprises a motor, preferably an electric motor, having a start / stop controller, preferably for rotating the drum.

[0018] A start / stop controller is configured to turn the motor on and off, thereby providing an adjustable average rotational speed of the drum relative to the rotationally symmetrical portion. More specifically, the start / stop controller is configured to turn the motor on and off during the preferably continuous operation of the dryer, wherein, on the one hand, a continuous flow of compressed gas is supplied to and dried in the drying zone, and, on the other hand, a continuous (partial) flow of compressed gas to be dried or after drying is directed to a regeneration zone for regenerating the desiccant. This start / stop controller is economically more advantageous than a frequency controller for regulating the speed of an electric motor, thus providing cost savings in terms of investment costs. Furthermore, the start / stop controller is less complex, requiring less control electronics. Furthermore, the start / stop controller can cause the drum to rotate relative to the rotationally symmetrical portion in stages, thereby, for example, precisely moving a section the size of the regeneration zone (or a fraction thereof) at a time, and then stopping the movement of that section for a given period of time. Another advantage of the start / stop controller is that the average rotational speed can be adjusted over a wider range than with a frequency controller; specifically, the average rotational speed can be adjusted from 0 to the maximum motor speed.

[0019] In an embodiment of the invention, the start / stop controller may be controlled by the same control unit as described elsewhere herein via a second control signal, which may be determined by the control unit based on measurements derived from the set of sensors.

[0020] Another aspect of the invention relates to a compressor arrangement comprising a compressor and a dryer according to any aspect or embodiment herein.

[0021] Another aspect of the invention relates to a method for drying a compressed gas using a dryer according to any aspect or embodiment herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be described in more detail below with reference to exemplary embodiments of the invention shown in the accompanying drawings.

[0023] Figure 1 A first embodiment of a compressor arrangement comprising a dryer according to the invention is shown.

[0024] Figure 2 A second embodiment of a compressor arrangement comprising a dryer according to the invention is shown.

[0025] Figure 3 A third embodiment of a compressor arrangement comprising a dryer according to the invention is shown.

[0026] Figure 4 A fourth embodiment of a compressor arrangement comprising a dryer according to the invention is shown.

[0027] Figure 5 A fifth embodiment of a compressor arrangement comprising a dryer according to the invention is shown.

[0028] Figure 6 Details of an embodiment of a controllable device that can be used according to Figures 1 to 5 In the embodiment of .

[0029] Figure 7A and Figure 7B An embodiment of a start and stop control device that can be used to drive a vehicle according to Figures 1 to 5 The roller in the embodiment of . DETAILED DESCRIPTION

[0030] The present invention will be described below with reference to certain embodiments and with reference to certain drawings, but the invention is not limited thereto but is defined solely by the claims. The drawings described are merely illustrative and do not limit the scope. In the drawings, the dimensions of some elements may be exaggerated and not drawn to scale; this is for ease of illustration. Dimensions and relative dimensions do not necessarily correspond to actual embodiments of the invention.

[0031] Furthermore, the terms "first," "second," "third," etc., are used in the description and claims to distinguish similar elements, but not necessarily to describe a sequential or chronological order. These terms are interchangeable under appropriate circumstances, and embodiments of the present invention may be practiced in an order other than that described or illustrated herein.

[0032] The terms "topmost," "upper," "bottommost," "lower," "above," "below," etc., in the description and claims are used for illustrative purposes and are not necessarily intended to describe relative positions. These terms are interchangeable under appropriate circumstances, and the embodiments of the invention described herein can be practiced in orientations other than those described or illustrated herein.

[0033] In addition, various embodiments that may be described as “preferred embodiments” should be understood as merely exemplary means and modes for implementing the present invention, and should not be understood as limiting the scope of the present invention.

[0034] The term "comprising" used in the claims should not be interpreted as being limited to the means or steps mentioned thereafter, and the term does not exclude other elements or steps. The term should be interpreted as indicating the presence of the described features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components or groups thereof. Therefore, the scope of the expression "a device or apparatus comprising means A and B" should not be considered to be limited to a device or apparatus consisting only of components A and B. This means that, for the present invention, only components A and B of the device are specifically mentioned, but the claims should be further interpreted to include equivalents of these components.

[0035] exist Figures 1 to 5 In the illustrated embodiments of the compressor apparatus, a compressor 60 is provided with a dryer 10; 30; 50; 70; 90, respectively, for compressing gas. In each case, the dryer comprises a pressure vessel 11 comprising a rotationally symmetrical portion defining a drying zone 12 and a regeneration zone 13; a drum 14 disposed within the rotationally symmetrical portion and provided with a regenerable desiccant; and a drive device 114 for rotating the drum relative to the rotationally symmetrical portion, i.e., rotating the drum 14 within the rotationally symmetrical portion or rotating the rotationally symmetrical portion around a stationary drum, so as to move the desiccant sequentially through the drying zone and the regeneration zone. Preferably, the rotationally symmetrical portion is cylindrical; however, this is not essential, and other rotationally symmetrical shapes are also possible. The dryer further comprises an inlet 15 connected to the inlet side of the drying zone of the pressure vessel 11 for supplying the compressed gas to be dried; and an outlet 16 connected to the outlet side of the drying zone of the pressure vessel 11 for discharging the dried compressed gas. The gas to be dried is supplied by a compressor 60 which may comprise a first compression stage 61, a second compression stage 62 and an interposed cooler ("intercooler") ("IC") 63. In the delivery line from the compressor 60 to the inlet 15, the compressed gas may pass through a heat exchanger (heat exchanger HE) 64 and / or a cooling device (aftercooler AC) 65.

[0036] In accordance with Figures 1 to 3 In the embodiment according to , at the outlet side of the compressor 60 , a portion of the compressed gas to be dried (having an increased temperature due to the compression) is branched off and passed to the regeneration zone for regeneration. Figure 1 In the embodiment according to Figure 2In the embodiment of the invention, the branch flow is first further heated by an active heating device 31 (e.g. an electric heating device). Figure 3 In the embodiment of FIG. 5 , the substream 51 is first further divided into a “first substream” 52 and a “second substream” 53, wherein only the “first substream” 52 is further heated by the heating device 54. As shown in the figure, the “first substream” 52 and the “second substream” 53 are respectively introduced into different areas of the regeneration zone 13.

[0037] In accordance with Figure 4 and Figure 5 In the embodiment of the present invention, connecting lines 77 and 97 are provided on the outlet side of the dryer for branching off a partial flow of the compressed gas after drying. This partial flow is conducted through the heat exchanger 64 to be heated by the heat present in the supply flow due to compression and then further conducted to the regeneration zone 13.

[0038] In accordance with Figures 1 to 5 In each embodiment of the present invention, the split flow for regeneration is returned to the main line 18 for the supply flow of compressed gas to be dried via the connecting line 19. As further described herein, this is performed by a controllable device such as a venturi ejector 21 or other controllable device for generating a pressure difference and maintaining the split flow for regeneration. One or more cooling devices can be provided in the connecting line 19 and / or the main line 18 and / or at the inlet 15 (after the confluence), such as the aftercooler 65 ("aftercooler AC") and / or the regeneration cooler 20 ("regeneration cooler RC") and / or the process cooler 91 ("process cooler PC") shown, each cooler being provided for cooling the corresponding gas flow by means of a coolant (e.g., cooling water or ice water).

[0039] In accordance with Figures 1 to 5 In the embodiment shown, the following sensors may be provided to measure the temperature of the corresponding compressed gas flow:

[0040] T1: temperature sensor at the inlet 15;

[0041] T2: temperature sensor at outlet 16;

[0042] T3: temperature sensor at the inlet side of the regeneration zone 13;

[0043] T4: temperature sensor at the outlet side of the regeneration zone 13;

[0044] T5: temperature sensor at the outlet side of the compressor (also the inlet side of the heat exchanger 64 or the aftercooler 65);

[0045] T6: temperature sensor in the main line 18 (between the aftercooler 65 and the venturi ejector 21);

[0046] T7: temperature sensor in the connecting line 19 (between the regeneration cooler 20 and the Venturi ejector 21);

[0047] T8 : Temperature sensor at the outlet side of the heat exchanger 64 .

[0048] In accordance with Figures 1 to 5 In the embodiment shown, pressure sensors as described below may be provided for measuring the pressure difference in the respective compressed gas flow across the respective elements, in each case providing a measure of the respective gas flow:

[0049] dP21: Pressure sensor for measuring the pressure difference across the venturi ejector 21 (see also Figure 6 );

[0050] dP REG : A pressure sensor for measuring the pressure difference between the outlet side of the drying zone 12 and the inlet side of the regeneration zone 13;

[0051] dP HEhot : a pressure sensor for measuring the pressure difference generated by the heat exchanger 64 in the supply flow of compressed gas to be dried supplied by the compressor 60;

[0052] dP HEcold : Pressure sensor for measuring the pressure difference generated by the heat exchanger 64 in the partial flow branched off for regeneration purposes.

[0053] In accordance with Figures 1 to 5 In the embodiment shown, the following sensors may also be provided:

[0054] "RPM": a sensor for measuring the rotational speed of the compressor 60, providing a measure of the flow rate of the supply gas to be dried;

[0055] “PDP”: pressure dew point sensor for measuring the pressure dew point at outlet 16;

[0056] T ACin and T ACout : Temperature sensors for measuring the coolant (cooling water) temperature at the inlet and outlet of the aftercooler 65;

[0057] T RCin and T RCout : Temperature sensors for measuring the coolant (cooling water) temperature at the inlet and outlet of the regenerative cooler 20;

[0058] T PCin and T PCout : Temperature sensors for measuring the coolant (cooling water) temperature at the inlet and outlet of the process cooler 91.

[0059] In accordance with Figures 1 to 5In the embodiment shown, a control unit 100 is provided in each case. Each of the above-mentioned sensors can be provided with means for communicating with the control unit 100. The communication connections can be wireless or wired; for the sake of clarity, they are not shown in FIG. Figures 1 to 5 Shown in.

[0060] In accordance with Figures 1 to 5 In the illustrated embodiment, at least the merging device for merging the partial flow for regeneration with the main flow of the supply gas to be dried is designed as a controllable device 21, 121 in each case. The control unit 100 is at least configured to process at least one measurement value provided by the aforementioned sensor, to determine a first control signal 101 for the aforementioned controllable device based on the at least one measurement value, and to apply the first control signal to the controllable device. The controllable device may comprise, for example, a Venturi ejector 21 with a controllable opening (see Figure 6 The controllable device may also include: a blower with a control for the blower speed; or a plurality of smaller venturi ejectors or nozzles arranged in parallel, with corresponding controls for opening or closing them. This has the advantage that the size of the controllable device can be smaller than that of a single venturi ejector, so that the controllable device can be better integrated into the pressure vessel. Moreover, the controllable device may alternatively include a venturi ejector with a controllable bypass around it. Other controllable devices are also possible.

[0061] In accordance with Figure 1 In the embodiment of the invention, the first control signal 101 is determined based on at least the RPM sensor (compressor RPM: supply flow of compressed gas) and the dP21 sensor (pressure drop across the venturi ejector 21: flow of the shunt), that is, based on these two measured values, at least the flow of the shunt branched for regeneration is controlled. Figure 2 and Figure 3 In the embodiment of the present invention, the first control signal 101 is further determined based on the temperature sensors T1 to T7 and based on the pressure dew point sensor "PDP". According to an alternative embodiment, one or more of these temperature sensors and the pressure dew point sensor can be arranged according to Figure 1 In the compressor device, and / or the control unit 100 can be further configured to determine the application of the second control signal and / or the third control signal for the rotational speed of the drum relative to the rotationally symmetrical portion of the pressure vessel and / or the one or more cooling devices (similar to Figure 4 and Figure 5 ), and / or other control signals.

[0062] In accordance with Figure 4 and Figure 5In an embodiment of the present invention, the control unit may be configured to determine and apply a first control signal 101, a second control signal 102 and / or at least one third control signal 103, 104, 105. These control signals are determined by the control unit based on one or more measured values ​​from the following sensors: RPM sensor (compressor RPM: supply flow of compressed gas), dP21 (pressure drop across the venturi ejector 21: flow of the split flow), dP REG (pressure drop between the outlet side of the drying zone 12 and the inlet side of the regeneration zone 13), dP HEhot (pressure drop in the main flow across the heat exchanger 64), dP HEcold (pressure drop in the split flow across the heat exchanger 64), one or more of T1 to T8, pressure dew point sensor PDP.

[0063] In another embodiment (not shown), the control unit 100 may be further communicatively connected to a remote computer system, for example, for remote monitoring, control, adjustment and / or software updating.

[0064] Figure 6 Details of a controller for a controllable device according to an embodiment of the present invention are shown, in this case a Venturi ejector 21 with a controllable opening. In this embodiment, the Venturi ejector has a controllable opening driven by a drive rod having a gear drive 121. The figure shows that the pressure drop caused by the controllable opening in the main flow 18 of the gas to be dried is measured by pressure sensors P1 and P2 communicating with a control unit 100. Based on this, the control unit 100 determines a first control signal 101 that is applied to the driver 121. By varying the position of the controllable opening, the pressure drop changes, and thus the suction force on the regeneration split flow 19 changes. In this way, the flow rate of the regeneration split flow is controlled.

[0065] As mentioned above, according to Figures 1 to 5 In each embodiment, a drive device 114 is provided to rotate the drum 14 relative to the rotational symmetry of the pressure vessel 11. The drive device may comprise a motor, preferably an electric motor, preferably having a start / stop controller, and is preferably controlled by a second control signal 102 from the control unit 100.

[0066] A start / stop controller is configured to turn the motor on and off, thereby providing an adjustable average rotational speed of the drum relative to the rotationally symmetrical portion. More specifically, the start / stop controller is configured to turn the motor on and off during the preferably continuous operation of the dryer, wherein, on the one hand, a continuous flow of compressed gas is supplied to and dried in the drying zone, while, on the other hand, a continuous (divided) flow of the compressed gas to be dried is directed to the regeneration zone for regeneration of the desiccant. This start / stop controller is economically more advantageous than a frequency control for regulating the speed of the electric motor, thus providing cost savings in terms of investment costs. Furthermore, the start / stop controller is less complex, requiring less control electronics. Specifically, the start / stop controller need only turn the motor on and off according to a desired duty cycle (in terms of on / off ratio) to provide a desired average rotational speed of the drum. Furthermore, the start / stop controller can cause the drum to rotate in stages relative to the rotationally symmetrical portion, for example, precisely moving a segment corresponding to the size of the regeneration zone (or a portion thereof) at a time, and then stopping the movement of that segment for a given period of time. Another advantage of the start / stop controller is that the range of average speed is wider than when using a frequency control; in particular, the average speed can be adjusted from 0 to the maximum speed of the motor.

[0067] Figure 7A and Figure 7B Shows some examples of start / stop controllers. Figure 7A The average speed is the maximum speed of the motor v max 1 / 3, in Figure 7B The average speed is the maximum speed of the motor v max The duty cycle has a period T. The average speed can be varied by varying the time the motor is on within the period T. The average speed can also be varied by keeping the time the motor is on constant and varying the time the motor is off (this means that the length of the duty cycle T is variable).

[0068] Application examples:

[0069] In a first application, the exemplary embodiments of the invention described herein can be applied as follows. A relatively high temperature and saturated gas (e.g. air) is supplied to the inlet 15 for the gas to be dried. The fact that the gas is at a relatively high temperature T1 means that it has a relatively high moisture content, so the drying drum 14 needs to remove more moisture from the gas, which in turn means that more regeneration is required and therefore a higher flow rate of regeneration gas is required. By measuring the temperature T1, which can vary, for example, depending on the ambient temperature of the compressor equipment, a measure of the moisture load of the gas supplied to the inlet 15 can be derived. The control unit 100 controls the flow rate of the regeneration flow (divided flow for regeneration) according to T1; in particular, as T1 increases, the control unit increases the flow rate, for example according to a predetermined table or characteristic control curve. The proper operation of the dryer is monitored by feedback provided by the measurement of the pressure dew point sensor "PDP" at the outlet 16.

[0070] In a second application, the exemplary embodiments of the present invention described herein can be applied as follows. If the flow rate of the regeneration stream varies (e.g., to maintain a stable pressure dew point (PDP) within a certain range, or to vary in response to pressure fluctuations), it may be desirable to adjust the cooling of the outgoing regeneration stream 19 and / or the rotational speed of the drum 14 based on the regeneration stream flow rate. A measure of the regeneration stream flow rate can be obtained by measuring the pressure drop across the venturi ejector 21. The control unit can, for example, control the flow rate of cooling water through the cooling device 20 used to cool the outgoing regeneration stream, or can control the flow rate of cooling water through the cooling device 91 used to cool the combined stream (the regeneration stream and the supply stream of the gas to be dried) to provide more cooling as the regeneration stream increases, thereby avoiding a situation where insufficient cooling results from an increase in the regeneration stream flow rate. In conjunction with this, or independently of this, the control unit 100 can control the rotational speed of the drum 14 based on the regeneration stream flow rate to optimize the ratio of the two. In this way, the control unit can take into account the life of the desiccant and adjust the drum speed to accommodate the desiccant's reduced regeneration capacity and / or absorption capacity.

Claims

1. A dryer for compressed gas, comprising: A pressure vessel (11) comprising a rotationally symmetrical portion having a drying zone (12) and a regeneration zone (13) in the rotationally symmetrical portion; A drum (14) is arranged in the rotationally symmetrical portion, and the drum is provided with a regenerable desiccant; A driving device (114) for rotating the drum relative to the rotationally symmetrical portion or rotating the rotationally symmetrical portion relative to the drum, so that the desiccant moves through the drying zone and the regeneration zone successively; an inlet (15) connected to the inlet side of the drying zone of the pressure vessel for supplying the compressed gas to be dried; as well as an outlet (16) connected to the outlet side of the drying zone of the pressure vessel for discharging the compressed gas after drying; a first connecting line for branching off a branch flow of the compressed gas to be dried or a branch flow of the compressed gas after drying and guiding the branch flow of the compressed gas to be dried or the branch flow of the compressed gas after drying to the regeneration zone; a controllable device, provided at the inlet (15), for merging the regenerated split flow discharged from the outlet side of the regeneration zone with the supply flow of the compressed gas to be dried, and controlling the flow rate of the regenerated split flow relative to the supply flow of the compressed gas to be dried; Wherein, the driving device (114) includes a motor provided with a start / stop controller; The invention is characterized in that the controllable device comprises a Venturi ejector (21), the Venturi ejector being provided with a controllable opening and being provided with a drive rod having a gear drive (121), the gear drive being used to drive the controllable opening based on a first control signal (101); by measuring the pressure drop caused by the controllable opening in the supply flow of the compressed gas to be dried, the control unit determines the first control signal to be applied to the gear drive on this basis; by changing the position of the controllable opening, the pressure drop is changed and, as a result, the suction force to which the regenerated split flow is subjected is changed; in this way, the flow rate of the regenerated split flow is controlled; The venturi ejector has an inlet port for a supply flow of compressed gas to be dried, an inlet port for a branch flow after regeneration, and an outlet port for a combined flow connected to the inlet (15), a controllable opening is provided inside the venturi ejector, one end of a drive rod can extend into the controllable opening, and the other end of the drive rod has teeth that engage with a gear drive.

2. The dryer according to claim 1, characterized in that The motor is an electric motor.

3. The dryer according to claim 2, characterized in that The start / stop controller is configured to turn the motor on and off so that the motor can be switched between a maximum motor speed and a stop state.

4. The dryer according to claim 1, characterized in that The dryer further comprises: a sensor group comprising at least one sensor, configured to measure at least one measurement value related to the operation of the dryer; and a control unit (100), the control unit being communicatively connected to the at least one sensor and the start / stop controller, and the control unit being configured to process the at least one measurement value to determine a second control signal (102) for controlling the start / stop controller based on the at least one measurement value and to apply the second control signal to the start / stop controller.

5. The dryer according to claim 4, characterized in that The set of sensors comprises one or more sensors for directly or indirectly measuring the flow rate of the supply stream of the compressed gas to be dried and / or the flow rate of the diverted stream after regeneration; The control unit (100) is further configured to evaluate a directly or indirectly measured supply flow rate of the compressed gas to be dried and / or a diverted flow rate after regeneration and to apply a second control signal (102) based on the evaluation.

6. The dryer according to claim 4, characterized in that The set of sensors includes one or more of the following sensors: a rotational speed sensor (RPM) for measuring the rotational speed of a compressor (60) supplying the supply flow of compressed gas to be dried; a pressure sensor for measuring the pressure drop across the controllable device.

7. The dryer according to claim 4, characterized in that The set of sensors includes one or more of the following sensors: a temperature sensor for measuring the temperature difference between the inlet side and the outlet side of the regeneration zone; a temperature sensor for measuring the temperature difference between the inlet side and the outlet side of the drying zone; and a pressure dew point sensor (PDP) at the outlet (16) for measuring the pressure dew point of the compressed gas outflow after drying.

8. The dryer according to claim 4, characterized in that In the case where the first connecting line branches off a branch flow of the dried compressed gas and guides the branch flow of the dried compressed gas to the regeneration zone, the first connecting line is provided with a heat exchanger (64) for heating the branch flow of the dried compressed gas branched off for regeneration by means of the compressed gas to be dried supplied to the dryer; and the set of sensors includes one or more of the following sensors: a pressure sensor for measuring a pressure difference between an outlet side of the drying zone and an inlet side of the regeneration zone; and a pressure sensor for measuring the pressure drop caused by the heat exchanger in the partial flow of the compressed gas after drying and / or in the supply flow of the compressed gas to be dried.

9. The dryer according to claim 4, characterized in that The dryer comprises at least one cooling device for cooling a supply flow of compressed gas to be dried, and / or cooling a branch flow after regeneration, and / or cooling a combined flow; and the set of sensors comprises one or more of the following sensors: a temperature sensor for measuring the temperature of the corresponding flow upstream and / or downstream of the corresponding cooling device; a pressure sensor for measuring the pressure drop caused by the corresponding cooling device in the corresponding flow; and a temperature sensor for measuring the temperature of the coolant used for cooling upstream and / or downstream of the cooling device.

10. A compressor arrangement comprising a compressor and further comprising a dryer according to any one of the preceding claims.

11. A method for drying compressed gas, the method using a dryer, the dryer comprising a pressure vessel, the pressure vessel comprising a rotationally symmetrical portion, the rotationally symmetrical portion having a drying zone (12) and a regeneration zone (13), the dryer further comprising a drum (14) disposed in the pressure vessel, the drum being provided with a regenerable desiccant, the method comprising the following steps: The drum is rotated relative to the rotationally symmetrical portion or the rotationally symmetrical portion is rotated relative to the drum by a driving device (114), so that the desiccant moves through the drying zone and the regeneration zone successively; supplying the compressed gas to be dried via an inlet (15) connected to the inlet side of the drying zone of the pressure vessel; Discharging the dried compressed gas through an outlet (16) connected to the outlet side of the drying zone of the pressure vessel; as well as Branching off a part flow of the compressed gas to be dried or a part flow of the dried compressed gas via a first connecting line and supplying the part flow of the compressed gas to be dried or the part flow of the dried compressed gas to a regeneration zone for regenerating the desiccant, and withdrawing the regenerated part flow from the regeneration zone at an outlet side of the regeneration zone; Using a controllable device provided at the inlet (15), the regenerated split flow discharged from the outlet side of the regeneration zone is merged with the supply flow of the compressed gas to be dried, and the flow rate of the regenerated split flow relative to the supply flow of the compressed gas to be dried is controlled; The drive device (114) includes a motor provided with a start / stop controller, and the start / stop controller turns the motor on and off in a timely manner according to a duty cycle. The invention is characterized in that the controllable device comprises a Venturi ejector (21), the Venturi ejector being provided with a controllable opening and being provided with a drive rod having a gear drive (121), the gear drive being used to drive the controllable opening based on a first control signal (101); by measuring the pressure drop caused by the controllable opening in the supply flow of the compressed gas to be dried, the control unit determines the first control signal to be applied to the gear drive on this basis; by changing the position of the controllable opening, the pressure drop is changed and, as a result, the suction force to which the regenerated split flow is subjected is changed; in this way, the flow rate of the regenerated split flow is controlled; The venturi ejector has an inlet port for a supply flow of compressed gas to be dried, an inlet port for a branch flow after regeneration, and an outlet port for a combined flow connected to the inlet (15), a controllable opening is provided inside the venturi ejector, one end of a drive rod can extend into the controllable opening, and the other end of the drive rod has teeth that engage with a gear drive.

12. The method according to claim 11, characterized in that The start / stop controller is used to switch the motor on and off during continuous operation of the dryer, wherein, on the one hand, a continuous supply flow of the gas to be compressed is supplied to the drying zone and dried therein, and, on the other hand, a continuous branch flow of the compressed gas to be dried or a branch flow of the dried compressed gas is directed to the regeneration zone for regenerating the desiccant.

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