Device for drying compressed gas and a method of operating a device for drying compressed gas

Abstract

Device for drying compressed gas, which device (1) is provided with an inlet (2) and an outlet (3) and with a dryer (4) comprising a first and second vessel (5a, 5b) and a controllable valve system (6) connecting said inlet (2) and outlet (3) to the vessels (5a, 5b), wherein the controllable valve system (6) is such that by controlling the valve system (6), the vessels (5a, 5b) can each in turn dry compressed gas, wherein the device (1) is provided with a regeneration line (8), characterised in that the regeneration line (8) is connected to a collector block (9), and in which a pressure controller (10) is incorporated for controlling the pressure of the regeneration gas to a fixed desired pressure, wherein a number of collector lines (14) leave the collector block (9), run towards to each vessel (5a, 5b), wherein each of the collector lines (14) is provided with a constriction (16).

Description

[0001] 03 SEPTEMBER 2025

[0002] TRANSLATION (RULE 12.3)

[0003] 1

[0004] Device for drying compressed gas and a method of operating a device for drying compressed gas.

[0005] 5 The present invention relates to a device for drying compressed gas.

[0006] More specifically, the invention is intended to dry compressed gas, such as compressed air, originating from a compressor.

[0007] It is known that compressed gas in most cases must be dried to remove the water, present in the gas, to prevent, for example, consumers of the compressed gas, such as pneumatic tools, or the pipes, valves and the like of the compressed air network, from suffering damage from the water present. 5 For this purpose, devices for drying compressed gas are already known, which are provided with an inlet for compressed gas to be dried and an outlet for dried compressed gas.

[0008] This inlet is typically connected to an outlet of a compressor device and the outlet of the0 device for drying compressed gas is typically connected to a consumer network.

[0009] The known devices are provided with a dryer, comprising two vessels containing a regenerable drying agent and a controllable valve system, consisting of a first valve block and a second valve block, which connects said inlet and said outlet, respectively, to said vessels.

[0010] The controllable valve system is configured such that one vessel of compressed gas dries, while the other vessel is being regenerated, and that by controlling the valve system, the vessels can each in turn dry compressed gas. 0

[0011] During the first phase of the drying cycle, compressed gas from a compressor will be directed through one of the vessels, for example, vessel A, wherein it will interact with the drying agent. Moisture, present in the compressed gas, will be absorbed by the drying agent, and the dried compressed gas will leave vessel A.

[0012] Meanwhile, a regeneration gas will flow through the other vessel, for example vessel B, to regenerate the drying agent in this vessel B, which has dried compressed gas during a previous phase of the drying cycle, thus saturating the drying agent in vessel B with moisture, or, in other words, to remove the moisture from the drying agent.

[0013] After a certain amount of time, the drying agent in vessel A will be completely saturated, meaning that the drying agent in vessel A can no longer absorb moisture.

[0014] At this moment, a next phase of the drying cycle will start, wherein, by switching the valve system, compressed gas to be dried is directed through vessel B, now comprising regenerated drying agent, to be dried, while a regeneration gas is directed through vessel A to regenerate the moisture-saturated drying agent.

[0015] To regenerate a vessel, i.e. to dry the moisture-saturated drying agent, a regeneration gas is passed through it.

[0016] For this purpose, known devices are provided with a so-called regeneration line that separates a part of the dried compressed gas as regeneration gas and transports it to the vessel that is being regenerated for the regeneration of the drying agent.

[0017] Devices are already known wherein the regeneration line comprises a line that connects the outlets, provided for this purpose on both vessels, and that directs part of the dried compressed gas from one vessel A, which is currently drying, to the other vessel B, which is currently being regenerated, and in which a constriction is provided in the form of a nozzle.

[0018] The function of the nozzle is to ensure that the separated regeneration gas flows through the vessel B at a specific flow rate.

[0019] The flow rate of regeneration gas through the vessel that is being regenerated is important because it affects the efficiency and speed of drying agent regeneration within that vessel.

[0020] Too high a flow rate will reduce the efficiency and waste dried compressed gas, while too low a flow rate will cause regeneration to take too long or not be complete.

[0021] A characteristic of such a nozzle is that, based on the pressure of the separated regeneration gas, a known, specific flow rate will exit the nozzle.

[0022] Based on the properties of the compressed gas to be dried and the dried compressed gas, and in particular the pressure of this gas, also known as the operating pressure of the dryer, a suitable type and size of nozzle will be selected to be arranged in the regeneration line, such that the desired flow rate is achieved through the nozzle for this specific operating pressure.

[0023] A disadvantage is that, when the pressure of the dried compressed gas changes, the flow rate exiting the nozzle will also change. The flow rate, delivered by the nozzle, depends on the pressure of the dried compressed gas, such that an increase or decrease of this pressure entails an increase or decrease of the delivered flow rate.

[0024] Of course, this results in a too high or too low a flow rate of regeneration gas, directed through the vessel that is being regenerated.

[0025] The pressure of the dried compressed gas may change when the operating pressure of the compressor, supplying the compressed gas to be dried, changes for drying using the device.

[0026] This mainly occurs with so-called mobile or 'portable' applications, wherein the operating pressure can change daily.

[0027] To ensure that the desired flow rate of regeneration gas will still be directed through the regenerated vessel in these cases, various types and sizes of nozzles are provided, which are interchanged in the regeneration line, based on the prevailing operating pressure. In this way, it is ensured that the desired flow rate of regeneration gas is always provided by selecting the nozzle with the correct specifications.

[0028] Of course, a disadvantage thereof is that not only all possible expected different nozzles have to be provided, but also that the device has to be shut down to realise the exchange of nozzles in the regeneration line.

[0029] The present invention aims to provide a solution to at least one of said and other disadvantages.

[0030] The present invention relates to a device for drying compressed gas, which device is provided with an inlet for compressed gas to be dried and an outlet for dried compressed gas, wherein the device is provided with at least one dryer, comprising at least a first vessel and a second vessel that contain a regenerable drying agent, and a controllable valve system, comprising a first valve block and a second valve block connecting said inlet and said outlet, respectively, to said vessels, wherein the controllable valve system is configured such that at least one vessel dries compressed gas while at least one other vessel is being regenerated, and that by controlling the valve system, the vessels can each in turn dry compressed gas, wherein the device is provided with a regeneration line, configured to separate a portion of the dried compressed gas as regeneration gas and to convey it to the at least one vessel that is being regenerated, for the regeneration of said at least one vessel that is being regenerated, characterised in that the regeneration line is connected to a collector block, wherein a pressure controller is incorporated into the regeneration line for controlling the pressure of the separated regeneration gas, downstream of the pressure controller, to a fixed, desired pressure, wherein a number of collector lines leave the collector block, wherein each of the collector lines runs towards an inlet, provided for that purpose in each vessel, wherein a constriction is provided in each of the collector lines to obtain a desired flow rate of the separated regeneration gas.

[0031] Said pressure controller will control the pressure of the separated regeneration gas downstream of the pressure controller to a fixed, specific pressure which is independent of the operating pressure of the device, i.e. of the pressure of the dried compressed gas. This results in that, even if the operating pressure of the device would change, the pressure of the regeneration gas downstream of the pressure controller always has the same value.

[0032] The regeneration gas in the collector block therefore always has the same pressure, and consequently also in the collector lines.

[0033] An advantage is that the flow rate of regeneration gas passing through the constriction will always be the same.

[0034] In other words, as the operating pressure changes, the same flow rate of regeneration gas will continue to flow through the vessel that is being regenerated, such that regeneration of this vessel will always proceed as efficiently as possible, without too much compressed dried gas being lost as regeneration gas or the drying agent not being sufficiently regenerated.

[0035] An additional advantage is that there is no longer a need to exchange nozzles, and said constrictions, which can take the form of nozzles, no longer need to be replaced, depending on the prevailing operating pressure. Consequently, shutting down the device is no longer necessary.

[0036] Said collector block enables a connection of the regeneration line to the collector lines; it is a sort of collection block, distributing to various "tap-off points," namely the collector lines. It can be implemented in various ways, as will be explained further in the description.

[0037] Furthermore, it is not excluded that more than two vessels are provided in the dryer. In this case, the valve system will be expanded or modified such that one vessel is always drying and the other is being regenerated. The other vessels can dry or regenerate, or, if necessary, cooled after being regenerated before drying again.

[0038] Preferably, the pressure controller is bridged by a bypass line in which a pressure equalization valve is incorporated. The purpose of the pressure equalization valve is to bring the pressure in the vessel that is being regenerated back to the operating pressure after regeneration.

[0039] At the moment the regeneration is started, the vessel is at operating pressure, i.e. at a pressure equal to the pressure of the compressed gas to be dried.

[0040] To initiate regeneration, the pressure in this vessel is first decreased to or just above atmospheric pressure, to then pass the regeneration gas through it.

[0041] After the regeneration, this vessel will begin drying again. This means that compressed gas to be dried is passed through the vessel. The pressure difference between the pressure of the gas in the vessel immediately after regeneration and the pressure of the compressed gas to be dried can cause shocks and damage to the vessel and / or drying agent.

[0042] Therefore, it is advisable to increase the pressure of the gas in the vessel before the vessel starts to dry again.

[0043] By opening the pressure equalisation valve, the pressure controller will be bypassed, and the separated regeneration gas will end up directly into the collector block and the collector lines, and thus into the vessel, without reducing the pressure.

[0044] In a practical embodiment, a second check valve is provided in each of the collector lines between the collector block and the constriction, which only allows a gas flow from the collector block to the vessel.

[0045] This has the advantage that, when the respective compressed gas vessel is drying, no compressed gas can flow or leak away via the collector line to the collector block, while regeneration gas can flow to the vessel when the vessel is regenerated. In this embodiment, a second check valve is provided per collector pipe.

[0046] In an alternative embodiment, the collector block is divided into sub-collector blocks, each connected to the regeneration line, wherein as many sub-collector blocks are provided as there are vessels in the dryer or dryers, wherein each vessel, or all corresponding vessels of the dryers, are connected to one of the sub-collector blocks.

[0047] In other words, if there are two vessels provided in the dryer, two sub-collector blocks will be provided; if there are three vessels, three sub-collector blocks will be provided in the device.

[0048] With corresponding vessels is meant vessels that are always in the same phase of the drying cycle, i.e., they are always drying and are being regenerated at the same time. This means that the vessels that are connected to a specific sub-collector block are always either all drying compressed gas, all being regenerated, or all being cooled if the drying cycle also comprises a cooling phase.

[0049] In this case, it is preferable to provide a third check valve in the regeneration line, between the pressure controller and each of the sub-collector blocks, which only allows gas flow to one of the sub-collector blocks.

[0050] These third check valves will ensure that, when the respective compressed gas vessel is drying, no compressed gas can flow or leak out through the collector line and the collector block, while regeneration gas can flow to the vessel when the vessel is regenerated.

[0051] In other words, the third check valves perform the same function as the second check valves, but in this embodiment, the total number of third check valves will be equal to or less than the number of second check valves in the previous embodiment. In this embodiment, the number of check valves is equal to the number of sub-collector blocks, while in the previous embodiment, it is equal to the total number of vessels.

[0052] In the case that the device comprises multiple dryers, this will drastically reduce the number of check valves.

[0053] In a practical embodiment, the device is provided with a minimum pressure valve, connected to the outlet, and the regeneration line is connected to the outlet of the device, such that dried compressed gas is separated off at the outlet as regeneration gas.

[0054] The minimum pressure valve will ensure that, if the pressure in the vessels becomes too low, the compressed air network, connected to the outlet of the device, will not allow any compressed air to pass to the device.

[0055] The provision of this minimum pressure valve allows to branch off, using the regeneration line, dried compressed gas at the outlet of the device, for example just upstream of the minimum pressure valve.

[0056] The minimum pressure valve will not always be present (or required to be present), for example if the compressor or compressor device that is connected to the device inlet, is provided with a minimum pressure valve.

[0057] In such a variant embodiment of the device wherein the device is free from a minimum pressure valve at the outlet, one dryer is provided with a connecting line between the first and second vessel, in which two separate fourth check valves are provided which only allow a gas flow from the vessels, wherein the regeneration line connects to a point in the connecting line between both check valves.

[0058] In other words, in this case the regeneration gas is branched off from the vessels, instead of at the outlet of the device, to prevent gas from the compressed air network being used as regeneration gas when the operating pressure of the device is too low.

[0059] Furthermore, the present invention relates to a method for operating a device for drying compressed gas, wherein the method comprises the following steps: drying the compressed gas in a first vessel, containing a first amount of a regenerable drying agent; separating a portion of the compressed gas, dried in the first vessel, as regeneration gas; regenerating a second vessel, containing a second amount of the regenerable drying agent, by means of the separated regeneration gas, characterized in that the pressure of the regeneration gas is controlled to a fixed desired pressure to obtain a desired flow rate of the regeneration gas to the second vessel.

[0060] It is obvious that such a method enjoys the same and / or similar advantages as the above-described embodiments of the device for drying compressed gas according to the invention.

[0061] With the view to better demonstrate the features of the invention, some preferred embodiments of a device for drying compressed gas according to the invention and a method of operating a device for drying compressed gas according to the invention are described hereinafter, by way of example but not in any way limiting, with reference to the accompanying drawings, in which:

[0062] Figure 1 schematically shows a first embodiment of a device according to the invention; Figure 2 shows a second embodiment of a device according to the invention;

[0063] Figure 3 shows a variant of Figure 1;

[0064] Figure 4 shows a variant of Figure 2.

[0065] Figure 1 schematically shows a device 1 for drying compressed gas according to the invention.

[0066] The device 1 mainly comprises an inlet 2 for compressed gas to be dried and an outlet 3 for dried compressed gas and a dryer 4.

[0067] In this case, more than one dryer 4 is provided, namely five dryers 4.

[0068] It is clear that the invention is not limited to this, and that any number of dryers 4 is possible. The dryers 4 are connected in parallel between the inlet 2 and the outlet 3 of the device

[0069] 1, meaning that each dryer 4 is directly connected to the inlet 2 and the outlet 3.

[0070] Each dryer 4 comprises at least a first vessel 5a and a second vessel 5b.

[0071] Also, the number of vessels 5a, 5b is not limiting for the invention and in the example shown, each dryer 4 has exactly two vessels 5a, 5b, but there may also be three, four, five or more vessels 5a, 5b.

[0072] Each vessel 5a, 5b contains or is filled with a regenerative drying agent or desiccant.

[0073] The dryers 4 are provided with a controllable valve system 6, which comprises a first valve block 7a and a second valve block 7b.

[0074] In the example shown, the first and second valve blocks 7a, 7b for each dryer 4 are separate components or parts of the device 1, but it is not excluded that all first valve blocks 7a are integrated into one common first valve block 7a and / or that all second valve blocks 7b are integrated into one common second valve block 7b.

[0075] The first valve block 7a connects the vessels 5a, 5b of the dryer 4 to said inlet 2, while the second valve block 7b connects the vessels 5a, 5b to said outlet 3.

[0076] Each valve block 7a, 7b is a collection or combination of lines and valves, such as solenoid valves, 3 / 2 pneumatic valves, check valves, controllable valves, butterfly valves, which allow to connect the various vessels 5a, 5b of the dryer 4 to the inlet 2 and the outlet 3 at the appropriate time.

[0077] Indeed, the controllable valve system 6 is configured in such a way that one vessel 5a dries compressed gas, i.e. compressed gas can flow through it from the inlet 2 to the outlet 3, while the other vessel 5b is being regenerated, meaning that a regeneration gas is passed through it.

[0078] By appropriately controlling or actuating valve system 6, the vessels 5a and 5b will each dry compressed gas in turn, such that a cyclical process is obtained wherein the drying process comprises several phases, wherein, for example, in a first phase, one vessel 5a will dry compressed gas and the other vessel 5b will be regenerated, while in a subsequent phase, vessel 5a will be regenerated and vessel 5b will dry. These two phases are repeated over and over again during the drying process. This will be explained in more detail below.

[0079] The device 1 is further provided with a regeneration line 8. This regeneration line 8 will separate part of the compressed dried gas as regeneration gas to direct it to the vessel 5b that is being regenerated for the regeneration of this vessel 5b.

[0080] This regeneration line 8 is connected to a collector block 9.

[0081] A pressure controller 10 is incorporated in the regeneration line 8 for controlling the pressure of the separated regeneration gas downstream of the pressure controller 10 to a fixed, desired pressure.

[0082] This pressure controller 10 may take various forms and may comprise a pressure reducing valve or a pressure controlled valve with electronic or mechanical control or a pressure controller provided with a control valve.

[0083] In this case, but not necessarily, this pressure controller 10 is bridged to the collector block 9 by a bypass line 11 in which a pressure equalizing valve 12 is incorporated.

[0084] In this case, but not necessarily, a first check valve 13 is incorporated in the regeneration line 8 between the pressure controller 10 and the collector block 9. This first check valve 13 is oriented in such a way that it only allows a gas flow from the pressure controller 10 to the collector block 9.

[0085] According to the invention, the device 1 is further provided with a number of collector lines 14, which run from the collector block 9 to each vessel 5a, 5b, which for this purpose are provided with an inlet or connection 15 for one of these collector lines 14. The number of collector lines 14 is equal to the total number of vessels 5a, 5b; in this case of Figure 1, there are ten collector lines 14.

[0086] According to the invention, a constriction 16 is provided in each of these collector lines 14 to obtain a desired flow rate of the separated regeneration gas that flows via the collector lines 14 to the vessels 5a, 5b.

[0087] This constriction 16 in each of these collector lines 14 is located near the vessel 5a, 5b.

[0088] The constriction 16 can be constructed in various ways: for example, as a nozzle or as an orifice plate. However, any means or equipment that can convert a specific pressure into a specific, fixed flow rate is suitable for use as the constriction 16.

[0089] Furthermore, in this embodiment, but not necessary for the invention, a second check valve 17 is provided in each of the collector lines 14 between the collector block 9 and the constriction 16, which only allows a gas flow from the collector block 9 to the vessel 5a, 5b.

[0090] Furthermore, in this embodiment, but not necessary for the invention, a minimum pressure valve 18 is provided, connected to outlet 3, and said regeneration line 8 is connected to outlet 3 of device 1, such that dried compressed gas is separated from outlet 3 as regeneration gas.

[0091] Also, in the example shown, a dew point sensor 19 is provided at outlet 3, which measures the dew point of the dried compressed gas leaving outlet 3.

[0092] Finally, in this case, but not necessary for the invention, the first valve block 7a is provided with a blow-off valve 20a, 20b to blow off the regeneration gas after passing through the vessel 5b that is being regenerated and / or to blow off the compressed gas contained in the vessel 5b that is being regenerated before starting the regeneration.

[0093] More specifically, in this case two blow-off valves 20a, 20b are provided, being a first blow-off valve 20a and a second blow-off valve 20b, wherein the first blow-off valve 20a will be used to blow off compressed gas from the vessel 5b before starting regeneration, and wherein both blow-off valves 20a, 20b are used to blow off regeneration gas.

[0094] The operation of device 1 is very simple and as follows.

[0095] Compressed gas to be dried, originating from a compressor or compressor device, enters the device 1 via the inlet 2.

[0096] Via the first valve blocks 7a, this gas is directed to the vessels 5a of the dryers 4, which dry compressed gas.

[0097] It is passed through the drying agent vessels 5a, where the drying agent will absorb the moisture, present in the compressed gas.

[0098] The dried compressed gas is then passed through the second valve blocks 7b to the outlet 3, where it will leave the device 1 and be passed to a compressed air network.

[0099] The other vessels 5b, which have already dried gas during a previous cycle, contain moist drying agent and are being regenerated in the meantime.

[0100] The first and second valve blocks 7a, 7b are connected appropriately for this purpose.

[0101] First, the blow-off valve 20a will be opened to release the pressure from these vessels 5b.

[0102] Subsequently, the dried compressed gas that is separated off via the regeneration line 8 and has a pressure equal to the operating pressure of, for example, twelve bar, will be reduced in pressure by the pressure controller 10 up to a fixed, desired pressure of, for example, five bar.

[0103] This regeneration gas at a pressure of five bar enters the collector block 9 via the first check valve 13, from where it is passed to the vessels 5b to be regenerated via the collector lines 14. Since these vessels 5b are at a low pressure, the regeneration gas can flow through the second check valves 17 into these vessels 5b.

[0104] Since the vessels 5a that are currently drying are at operating pressure, the regeneration gas cannot pass through the second check valves 17 of these vessels 5a.

[0105] It is clear that these second check valves 17 can be replaced by controllable or switchable valves that are switched over at the appropriate time to obtain the same functionality.

[0106] When the regeneration gas flows through the second check valves 17, it will then be directed through the constrictions 16.

[0107] This ensures that a desired and appropriate flow rate of regeneration gas is directed through the vessels 5b.

[0108] As the regeneration gas passes through these vessels 5b, it will extract moisture from the saturated drying agent to regenerate it.

[0109] After passing through, the now-moist regeneration gas is routed via the first valve blocks 7a to the blow-off valves 20a, 20b, with both blow-off valves 20a, 20b now open.

[0110] When the regeneration is completed and the drying agent is fully regenerated and therefore dry, the vessels 5b will first be brought back up to operating pressure before drying again.

[0111] To this end, the pressure equalization valve 12 is opened to bypass the pressure controller 10, after both blow-off valves 20a and 20b have first been closed.

[0112] The compressed dry gas, separated through the regeneration line 8, will now enter the collector block 9 via the bypass line 11 without undergoing a pressure reduction and from there via the collector lines 14 into the vessels 5b until they are pressurized. By the presence of the first check valve 13, compressed dry gas is preventing from flowing back to the pressure controller 10.

[0113] Subsequently, the next phase of the drying cycle can be started.

[0114] Starting the next phase will be done based on the measurements of the dew point sensor 19 at the outlet 3: when the dew point of the dried compressed gas reaches a threshold value, which means that the drying agent in the vessels 5a, drying the compressed gas, is saturated, the next phase will be started.

[0115] When the measured dew point is below the threshold value, no subsequent phase will be initiated yet. This means that vessels 5a and 5b will not be exchanged yet, and vessel 5b will now enter a standby phase, wherein it will not be regenerated any further, while vessel 5a, which is drying gas, will continue drying compressed gas until the dew point of the dried compressed gas reaches a threshold value.

[0116] During a subsequent phase, the first and second valve blocks 7a and 7b are used to switch vessels 5a and 5b, such that compressed gas to be dried is directed to vessels 5b, which, after regeneration, now contain a dry drying agent, and such that regeneration gas is directed through vessels 5a, which, after drying the compressed gas, now contain a saturated drying agent. Operation in this subsequent phase is as described above for the first phase, wherein the functions of only vessels 5a and 5b are switched.

[0117] In Figure 2, a second embodiment of a device 1 according to the invention is shown, which is very similar to the device in Figure 1, wherein, in this case, the collector block 9 is divided into sub-collector blocks 9a, 9b, each of which is connected to the regeneration line 8.

[0118] There are as many sub-collector blocks 9a, 9b as there are vessels 5a, 5b in a dryer 4. In this case, each dryer 4 has two vessels 5a, 5b, and therefore also two sub-collector blocks 9a, 9b. These sub-collector blocks 9a, 9b are each directly connected to the regeneration line 8.

[0119] Each vessel 5a, 5b of a dryer 4 is connected to one of the sub-collector blocks 9a, 9b, wherein each vessel 5a, 5b of a dryer 4 is connected to another sub-collector block 9a, 9b.

[0120] Corresponding vessels 5a, 5b of the different dryers 4 are connected to the same subcollector block 9a, 9b.

[0121] Corresponding vessels 5a, 5b refer to vessels 5a, 5b that are always in the same phase of the drying cycle, i.e., they are always drying and being regenerated at the same time. This means that the vessels 5a, 5b that are connected to a specific sub-collector block 9a, 9b, are always either all drying compressed gas, all being regenerated, or all being cooled if the drying cycle also comprises a cooling phase.

[0122] Furthermore, in this case, but not necessary for the invention, third check valves 21 are provided in the regeneration line 8, between the pressure controller 10 and each subcollector block 9a, 9b, which only allow a gas flow to the sub-collector block 9a, 9b.

[0123] More specifically, in this case the third check valves 21 are provided between the first check valve 13 after the pressure controller 10 and each sub-connector block 9a, 9b.

[0124] The second check valves 17 in the collector lines 14 are not present in this embodiment.

[0125] Otherwise, the device 1 is identical to that in Figure 1.

[0126] Therefore, the operation is very similar.

[0127] When, in a first phase of the drying process, the vessels 5a dry compressed gas, the subcollector block 9a, connected to these vessels 5a, will now be at the operating pressure.

[0128] The sub-collector block 9b that is connected to the vessels 5b that are being regenerated is at a pressure of, for example, five bar, or the pressure to which the pressure controller 10 reduces the separated regeneration gas from the operating pressure.

[0129] The separated compressed gas is led through the regeneration line 8, via the pressure controller 10 and the third check valve 21, to the sub-collector block 9b.

[0130] Since the pressure in the sub-collector block 9a is higher than the pressure of the regeneration gas downstream of the pressure controller 10, no regeneration gas will enter this sub-collector block 9a and no dried compressed gas will flow from the subcollector block 9a to the regeneration line 8 and the other sub-collector block 9b.

[0131] In other words, the regeneration gas only enters the vessels 5b that need to be regenerated. Even when the pressure equalization valve 12 is opened to repressurize the vessels 5b, due to the action of the third check valves 21, the regeneration gas will only enter the sub-collector block 9b and thus the vessels 5b.

[0132] Furthermore, the operation is identical to that of the embodiment in Figure 1.

[0133] Figure 3 shows a variant of the device 1 of Figure 1, wherein, in this case, there is no minimum pressure valve 18 at the outlet 3.

[0134] Also, the regeneration line 8 will not connect to the outlet 3 of the device 1, as was the case in Figures 1 and 2.

[0135] Instead, one dryer 4 is provided with a connecting line 22 between the first vessel 5a and second vessel 5b, in which two separate fourth check valves 23 are provided which only allow a gas flow from the vessels 5a, 5b, wherein the regeneration line 8 connects to a point P in the connecting line 22 between both check valves 23.

[0136] Otherwise, this embodiment is the same as the embodiment in Figure 1.

[0137] The operation is therefore very similar, only in this case the compressed gas will not be separated off at the outlet 3, but from the connecting line 22. Such an embodiment can be used when there is indeed no minimum pressure valve 18 at the outlet 3, for example because this is not desired, not possible, or because a minimum pressure valve 18 is already present elsewhere in the system.

[0138] In order to avoid that in such a case, when the pressure in the device 1 is too low, the regeneration line 8 takes compressed gas from the consumer network, connected to the outlet 3, the regeneration line 8 is, in such a case, connected to the connecting line 22 provided for that purpose.

[0139] Figure 4 shows a variant of the device 1 of Figure 2, wherein, in this case, there is no minimum pressure valve 18 at the outlet.

[0140] Also, the regeneration line 8 will not connect to the outlet 3 of the device, as was the case in Figures 1 and 2.

[0141] Instead, one dryer 4 is provided with a connecting line 22 between the first vessel 5a and second vessel 5b, just as in Figure 3, in which two fourth check valves 23 are provided which only allow a gas flow from the vessels 5a, 5b, wherein the regeneration line 8 connects to a point P in the connecting line 22 between both check valves 23.

[0142] Otherwise, this embodiment is the same as the embodiment in Figure 2.

[0143] The operation is therefore very similar, only in this case, as in Figure 3, the compressed gas will not be separated at the outlet 3, but from the connecting line 22. The rest of the operation is as explained for Figure 2.

[0144] What is identical for all four of said embodiments, is the method of controlling or operating the device 1, wherein the method consists in drying compressed gas in a first vessel 5a, containing regenerable drying agent, and separating a portion of the compressed gas dried by the first vessel and using it as a regeneration gas to regenerate a regenerable drying agent in a second vessel 5b, wherein the pressure of the regeneration gas is controlled each time to a fixed desired pressure to obtain a desired flow rate of regeneration gas to the second vessel 5b.

[0145] The present invention is by no means limited to the embodiments, described by way of example and shown in the figures, but a device for drying compressed gas according to the invention can be realised in all kinds of shapes and sizes without departing from the scope of the invention as defined in the claims.

Claims

Claims.1.- A device for drying compressed gas, which device (1) is provided with an inlet (2) for compressed gas to be dried and an outlet (3) for dried compressed gas, wherein the device (1) is provided with at least one dryer (4), comprising at least a first vessel (5a) and a second vessel (5b) that contain a regenerable drying agent, and a controllable valve system, (6) comprising a first valve block (7a) and a second valve block (7b) connecting said inlet (2) and said outlet (3), respectively, to said vessels (5a, 5b), wherein the controllable valve system (6) is configured such that at least one vessel (5a) dries compressed gas while at least one other vessel (5b) is being regenerated, and that by controlling the valve system (6), the vessels (5a, 5b) can each in turn dry compressed gas, wherein the device (1) is provided with a regeneration line (8), configured to separate a portion of the dried compressed gas as regeneration gas and to convey it to the at least one vessel (5b) that is being regenerated, for the regeneration of said at least one vessel (5b) that is being regenerated, characterised in that the regeneration line (8) is connected to a collector block (9), wherein a pressure controller (10) is incorporated in the regeneration line (8) for controlling the pressure of the separated regeneration gas, downstream of the pressure controller (10), to a fixed desired pressure, wherein a number of collector lines (14) leaves the collector block (9), wherein each of the collector lines (14) runs towards an inlet (15), provided for that purpose in each vessel (5a, 5b), wherein a constriction (16) is provided in each of the collector lines (14) to obtain a desired flow rate of the separated regeneration gas.2.- The device according to claim 1, characterised in that the pressure controller (10) is bridged by a bypass line (11) in which a pressure equalisation valve (12) is incorporated.3.- The device according to claim 1 or 2, characterised in that a first check valve (13) is incorporated in the regeneration line (8) between the pressure controller (10) and the collector block (9), which only allows a gas flow from the pressure controller (10) to the collector block (9).4.- The device according to any one of the preceding claims, characterised in that thedevice (1) is provided with several dryers (4), connected in parallel between the inlet (2) for compressed gas to be dried and the outlet (3) for dried compressed gas.5.- The device according to any one of the preceding claims, characterised in that a second check valve (17) is provided in each of the collector lines (14) between the collector block (9) and the constriction (16), which only allows a gas flow from the collector block (9) to the vessel (5a, 5b).6.- The device according to any one of the preceding claims 1 to 4, characterised in that the collector block (9) is divided into sub-collector blocks (9a, 9b), each connected to the regeneration line (8), wherein as many sub-collector blocks (9a, 9b) as there are vessels (5a, 5b) in the dryer (4) or dryers (4) are provided, wherein each vessel (5a, 5b), or all corresponding vessels (5a, 5b) of the dryers (4), are connected to one of the subcollector blocks (9a, 9b).7.- The device according to claim 6, characterised in that a third check valve (21) is provided in the regeneration line (8) between the pressure controller (10) and each one of the sub-collector blocks (9a, 9b), which only allows a gas flow to one of the subcollector blocks (9a, 9b).8.- The device according to any one of the preceding claims, characterised in that the device (1) is provided with a minimum pressure valve (18), connected to the outlet (3), and that the regeneration line (8) is connected to the outlet (3) of the device (1), such that dried compressed gas is separated off at the outlet (3) as regeneration gas.9.- The device according to any one of the preceding claims 1 to 8, characterised in that the device (1) is free from a minimum pressure valve (18) at the outlet (3), and that one dryer (4) is provided with a connecting line (22) between the first vessel (5a) and the second vessel (5b), in which two fourth check valves (23) are provided which only allow a gas flow from the vessels (5a, 5b), wherein the regeneration line (8) connects to a point (P) in the connecting line (22) between both fourth check valves (23).10.- The device according to any one of the preceding claims, characterised in that theconstriction (16) is embodied as a nozzle or orifice plate.11.- The device according to any one of the preceding claims, characterised in that the pressure controller (10) comprises a reducing valve or pressure-controlled valve or a pressure-controlled valve with an electronic or mechanical control or a pressure controller, provided with a control valve.12.- The device according to any one of the preceding claims, characterised in that the first valve block (7a) is provided with a blow-off valve (20a, 20b) to blow off the regeneration gas after passing through the vessel (5b) that is being regenerated, and / or to blow off the compressed gas, contained in the vessel (5b) to be regenerated, before starting the regeneration.13.- A method of operating a device for drying compressed gas, wherein the method comprises the following steps:- drying the compressed gas in a first vessel (5a), containing a first amount of a regenerable drying agent;- separating a portion of the compressed gas, dried in the first vessel (5a), as regeneration gas;- regenerating a second vessel (5b), containing a second amount of the regenerable drying agent, by means of the separated regeneration gas, characterised in that a pressure of the regeneration gas is controlled to a fixed desired pressure to obtain a desired flow rate of the regeneration gas to the second vessel (5b).

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