Air-cooled device and method for controlling the air-cooled device

Abstract

A method for controlling an air-cooled device (1) for compressing a gas, the air-cooled device (1) comprising at least one element (2) for compressing a gas, at least one air-cooled chiller (9, 12) for cooling a fluid in the air-cooled device (1), and two or more fans (10, 13), at least one of the fans (10, 13) being a variable speed fan (13) for generating a flow of cooling air for cooling the air-cooled chiller (9, 12), the method comprising controlling the speed of the variable speed fan (13) to a minimum required speed to prevent backflow of cooling air moving in at least a direction opposite to said flow when there is no need to cool the air-cooled chiller (9, 12).

Description

Technical Field

[0001] The present invention relates to a method for controlling an air-cooled device for compressing gas.

Background Art

[0002] In this specification, the "device for compressing gas" means a compression device, a blower device, and a vacuum pump device.

[0003] Specifically, the present invention intends to control a variable-speed fan provided in the device.

[0004] In this case, the "air-cooled device" means that the device includes at least one air-cooled cooler for cooling a liquid, such as oil, injected into an element of the device and / or for cooling a gas compressed by the device.

[0005] It is not excluded that the air-cooled device according to the present invention further includes another type of cooler.

[0006] The air-cooled cooler includes a fan that generates a flow of cooling air for cooling the air-cooled cooler.

[0007] This device generally includes a plurality of such fans that generate a flow of cooling air for cooling one or more air-cooled coolers.

[0008] The above air-cooled cooler cools the injected liquid and / or the compressed gas.

[0009] Cooling the injected liquid and / or the compressed gas may sometimes become unnecessary.

[0010] Therefore, the related air cooler should not cool the injected liquid and / or the gas.

[0011] Therefore, in known devices for compressing gases, it is known that the associated fan can be switched off to ensure a reduction in the power consumed by the fan.

[0012] When a fan stops, if multiple coolers are connected to a common outlet for cooling air, a backflow of heated cooling air across the air-cooled coolers can occur. This backflow of heated cooling air can then mix with fresh cooling air, resulting in an increase in the average cooling air temperature on the cooler side of the air-cooled coolers that still need cooling, which will then lead to an undesirable decrease in cooling capacity.

[0013] For this reason, slats or louvers are often used to prevent this undesirable backflow.

[0014] This has the disadvantage of incurring additional costs and making the equipment bulkier.

[0015] Furthermore, this is coupled with a pressure drop in the cooling air across the slats, resulting in more power being required to achieve the same volume of cooling air flow, even when the slats are fully open. [Overview of the project] [Problems that the invention aims to solve]

[0016] The present invention aims to provide a solution to at least one of the above-mentioned and / or other drawbacks. [Means for solving the problem]

[0017] The present invention relates to a method for controlling a device for compressing a gas, the device comprising at least one element for compressing a gas, at least one air-cooled cooler for cooling a fluid in the device, and two or more fans, at least one of the fans being a variable-speed fan for generating a flow of cooling air to cool the air-cooled cooler, and the method comprises controlling the speed of the variable-speed fan to the minimum required speed in order to prevent backflow of cooling air moving at least in the opposite direction to the flow when it is not necessary to cool the air-cooled cooler.

[0018] One advantage is that the method according to the present invention can optimize the energy consumption of the device by optimizing the energy consumption of the variable-speed fan(s).

[0019] By operating the variable-speed fan at the minimum required speed when possible, energy consumption can be minimized.

[0020] A further advantage is that when a variable-speed fan supplies cooling air for cooling purposes, backflow of heated cooling air is avoided without any further pressure drop in the cooling airflow.

[0021] This is to ensure that the minimum required fan speed generates the minimum necessary cooling airflow to guarantee that the variable-speed fan cannot reverse.

[0022] The amount of time an air-cooled cooler does not require cooling depends not only on the function of the cooler, i.e., whether it cools compressed gas or injects liquid into the element, but also on the operating mode of the device.

[0023] The above-mentioned cooler can be a cooler for the injected liquid, an intermediate cooler for the compressed gas, or a final cooler for the compressed gas.

[0024] Preferably, the speed of the variable-speed fan is -When an air-cooled cooler is used to cool the gas compressed by the device, when there is no need to cool the compressed gas, and / or -When a heat recovery system cools the required fluid instead of the air-cooled cooler, and / or -When the element is stopped or operating under no load, It is reduced to the minimum required speed.

[0025] In some cases, when the consumer of the compressed gas requires warm or hot gas for its application, cooling of the compressed gas is not necessary.

[0026] The device can also be equipped with a heat recovery system. If the system recovers sufficient heat, additional cooling by the above-mentioned air-cooled cooler is not necessary. The heat recovery system can be used for the liquid circuit and the compressed gas of the device.

[0027] In the case of a device having a plurality of elements connected in parallel, for example, when the demand for compressed gas is low, one or more of the elements can be switched off or operated under no load at a specific time, and as a result, cooling for the elements related to the injection liquid and / or the compressed gas is not necessary.

[0028] According to a preferred feature of the present invention, the variable-speed fan is driven by a fan motor cooled by the variable-speed fan, and the method consists of controlling the speed of the variable-speed fan to the minimum required speed when the air-cooled cooler does not need to perform cooling in order to prevent the reverse flow of the cooling air and to cool the fan motor without excess or deficiency to avoid overheating of the fan motor.

[0029] One advantage is that in this way, it is possible to prevent not only the reverse flow of the heated cooling air but also the overheating of the fan motor.

[0030] The present invention also relates to a device for compressing a gas, the device comprising at least one element for compressing the gas, at least one air-cooled cooler for cooling a fluid within the device, and two or more fans for cooling the air-cooled cooler, the device comprising at least one of the fans being a variable-speed fan for generating a flow of cooling air for cooling the air-cooled cooler, the variable-speed fan comprising a control device configured to perform the method according to the present invention.

[0031] The advantages of such a device are the same as the advantages of this method.

[0032] For the purpose of better illustrating the features of the present invention, many preferred embodiments of the air-cooled device and the method for controlling the air-cooled device according to the present invention are described below without limitation with reference to the accompanying drawings. [Brief explanation of the drawing]

[0033] [Figure 1] A schematic diagram of the apparatus according to the present invention is shown below. [Figure 2] A modified version of Figure 1 is shown. [Figure 3] Further variations of Figure 1 are shown. [Modes for carrying out the invention]

[0034] The apparatus 1 according to the present invention, shown in Figure 1, comprises two elements 2 connected in parallel for compressing gas.

[0035] Each element 2 has an inlet 3 and an outlet 4 connected thereto, with an outlet line 5, and the two outlet lines 5 merge to form an outlet line 6 of the device 1.

[0036] Element 2 can be a screw compressor element, but this is not essential in the present invention.

[0037] In this case, element 2 is a liquid injection element 2, but this is not essential in the present invention.

[0038] Furthermore, liquid separators 7 are provided at each outlet line 5 downstream of each element 2 in order to separate the liquid injected into the element 2.

[0039] The separated oil is returned to element 2 via the return line 8 and injected into element 2.

[0040] Both return lines 8 are equipped with air-cooled coolers 9 with fans 13.

[0041] In this case, the fan 13 has a variable speed. Within the scope of the present invention, if another fan in the device has a variable speed, it is not excluded that the fan does not have a variable speed.

[0042] In this case, the heat recovery system 11 is provided in each return line 8 downstream of the liquid separator 7 and upstream of the air-cooled cooler 9, and this heat recovery system can recover the heat generated in element 2 from the liquid. This heat can be reused, for example, for heating purposes or for heating household water.

[0043] The heat recovery system 11 described above is optional in this invention.

[0044] Downstream of both liquid separators 7, the outlet line 5 of element 2 merges with the outlet line 6 of device 1.

[0045] An air-cooled cooler 12 equipped with a fixed-speed fan 10 is positioned at the outlet line 6 of the device 1.

[0046] The above-mentioned cooler 12 is also called the final cooler.

[0047] All coolers 9 and 12 are connected to cooling air outlets (not shown) through which heated cooling air is discharged after passing through the coolers 9 and 12.

[0048] In this case, each of the variable-speed fans 13 described above is equipped with a variable-speed fan motor 14 controlled by a single control device 15.

[0049] According to the method of the present invention, the control device 15 described above is configured to control the variable-speed fan 13.

[0050] Furthermore, in this case, the control device 15 is connected to a temperature sensor 16 that measures the temperature of the liquid in the return line 8 upstream of the cooler 9. It is not ruled out that the temperature sensor 16 also measures the temperature of the liquid downstream of the cooler 9.

[0051] Furthermore, the control device 15 is connected to an inlet sensor 17 that measures the environmental parameters of the compressed gas, and a pressure sensor 18 that measures the pressure of the cooling airflow generated by each of the variable-speed fans 13.

[0052] The environmental parameters mentioned above include, but are not limited to, atmospheric pressure, ambient temperature, and / or gas humidity in the environment of apparatus 1.

[0053] The operation of device 1 is very simple and is as follows:

[0054] Element 2 compresses the gas in a known manner, and a liquid is injected into element 2 to lubricate and cool it.

[0055] The liquid is separated using a liquid separator 7 and passes through a heat recovery system 11 via a return line 8. The liquid is then cooled in an air-cooled cooler 9 before being injected back into element 2.

[0056] Subsequently, the compressed gas passes through the cooler 12 at the outlet line 6 of the device 1, where it is cooled.

[0057] The control device 15 controls the fan motor 14 according to the method according to the present invention.

[0058] When the heat recovery system 11 is operating, the liquid has already been cooled as it passes through the cooler 9, so the cooler 9 does not need to perform any further cooling.

[0059] In such cases, the control device 15 controls the variable speed fan 13 to reduce its speed to the minimum required speed in order to avoid backflow of cooling air, that is, to prevent heated cooling air at the outlet for cooling air discharged from the other cooler 9 and / or the cooler 12 of the outlet line 6 of the device 1 from flowing back into the cooler 9.

[0060] In this case, the minimum required speed mentioned above is determined based on environmental parameters and the pressure of the cooling airflow generated by the fan 13.

[0061] If fans 10 and 13 have a common outlet for cooling air, the minimum required speed can also be determined based on the pressure of the cooling air in the common outlet for cooling air.

[0062] The control device 15 determines the minimum required speed based on the signals from the inlet sensor 17 and the pressure sensor 18.

[0063] It is also possible to consider only environmental parameters, only the pressure of the airflow generated by fan 13, or only the pressure of the cooling air in the common outlet for cooling air.

[0064] If the control device 15 determines that the liquid is sufficiently cooled based on the measurements from the temperature sensor 16, the control device 15 controls the fan motor 14 in such a manner that the speed of the fan 13 is reduced to the minimum required speed determined above.

[0065] In all these cases, the fan motor 14 consumes less energy.

[0066] As described above, the minimum required speed is preferably determined at regular intervals, and the minimum required speed is adapted when the parameter on which the minimum required speed is determined changes.

[0067] However, the minimum required speed can also be a predetermined fixed value determined based on the worst-case scenario of the operating modes of another fan 10 and / or cooler 12 at the outlet line 6 of device 1.

[0068] This means that in the above-mentioned case where cooling is not required, the control device 15 controls the variable-speed fan 13 in such a manner that the speed of the variable-speed fan 13 becomes equal to the minimum fixed value.

[0069] In this case, the variable-speed fan motor 14 also consumes less energy.

[0070] In such cases, it is important to note that the variable-speed fans 13 are returned to their minimum possible speeds so that the reduction in energy consumption is maximized.

[0071] It will be clear that apparatus 1 in Figure 1 is just one possible embodiment.

[0072] Figure 2 shows a first modification of Figure 1 as an example, in which the three elements 2 for compressing the gas are connected in parallel.

[0073] In this case, the air-cooled coolers 9 are located on the return line 8, and each has its own variable-speed fan 13.

[0074] Each of the above fans 13 is driven by a variable-speed fan motor 14, and all are controlled by a single control device 15.

[0075] This is not essential, as each fan 13 may also have its own sub-control device.

[0076] Furthermore, some fans 13 may have a single common control device 15, while each of the other fans 13 may have its own separate sub-control device.

[0077] In this case, each of the variable-speed fans 13 also cools its associated fan motor 14.

[0078] Furthermore, each fan motor 14 is equipped with a temperature sensor 19 that can measure the temperature of the fan motor 14, for example, the temperature of the windings and / or bearings inside the fan motor 14.

[0079] The temperature sensor 19 is connected to the control device 15.

[0080] The control device 15 is also connected to a pressure sensor 18 that measures the pressure of the cooling airflow generated by the fan 13.

[0081] Furthermore, the outlet line 6 of the device 1 is provided with a final cooler in the form of an air-cooled cooler 12, which is equipped with a fan 10 whose speed cannot be adjusted.

[0082] In this case, the heat recovery system 11 is not provided, and similarly, the temperature sensor 16 is not provided downstream of the cooler 9.

[0083] In this case, the control device 15 controls the fans 13 of the air-cooled cooler 9 on the return line 8 in such a way that, when it is not necessary to cool one or more of the coolers 9, the speed of each fan 13 is returned to the minimum required speed in order to avoid backflow of cooling air and cool the fan motor 14.

[0084] One or more of the above-mentioned coolers 9 do not need to perform cooling when their respective elements 2 are stopped or operating under no load.

[0085] If a heat recovery system 11 is provided, and the heat recovery system 11 can sufficiently cool the liquid, then if there is no longer a need to cool the returned liquid, then one or more of the coolers 9 do not need to perform cooling in the same manner.

[0086] In such cases, the speed of each fan 13 can be returned to the minimum required speed mentioned above.

[0087] The minimum required speed is determined based on environmental parameters, the pressure of the airflow generated by the fan 13, and the temperature of the fan motor 14 of the variable-speed fan 13.

[0088] The control device 15 determines the minimum required speed based on the signals from sensors 17, 18, and 19.

[0089] If fan 13 or fan 10 and fan 13 have a common outlet for cooling air, the minimum required speed can also be determined based on the pressure of the cooling air in the common outlet for cooling air.

[0090] If the control device 15 receives a signal that the returned liquid does not need to be cooled, and / or a signal that one of the elements 2 is stopped or operating without load, the control device 15 controls the associated fan motor 14 in such a manner that it reduces the speed of the fan 13 to the minimum required speed determined above, thereby ensuring that the fan 13 still cools the fan motor 14 to prevent overheating, and that the fan 13 prevents backflow of heated cooling air.

[0091] In all these cases, the fan motor 14 consumes less energy.

[0092] Figure 3 shows a second modified example of Figure 1.

[0093] In this case, it is an oil-free two-stage device having two two-stage units installed in parallel.

[0094] Each of the two stages of the equipment comprises a low-pressure element 2a for compressing gas and a high-pressure element 2b for further compressing the gas compressed by the low-pressure element 2a, and these low-pressure and high-pressure elements are installed in series.

[0095] Device 1 includes an intercooler 9 between the low-pressure element 2a and the high-pressure element 2b.

[0096] The above-mentioned intercooler 9 is equipped with a variable-speed fan 13.

[0097] Each of the above fans 13 is driven by a variable-speed fan motor 14, and all are controlled by a single control device 15.

[0098] In this case, each of the variable-speed fans 13 also cools the associated fan motor 14.

[0099] Furthermore, each fan motor 14 is equipped with a temperature sensor 19 that can measure the temperature of the fan motor 14, for example, the temperature of the windings and / or bearings inside the fan motor 14.

[0100] The temperature sensor 19 is connected to the control device 15.

[0101] The control device 15 is also connected to a pressure sensor 18 that measures the pressure of the cooling airflow generated by the fan 13.

[0102] Downstream of the high-pressure element 2b, the heat recovery system 11 is housed in each outlet line 5.

[0103] Furthermore, in addition to the intercooler 9, heat recovery systems 11 are housed in each outlet line 5 of the high-pressure element 2b and the two-stage equipment upstream of the intercooler 9.

[0104] It is also possible for only the heat recovery system 11 to be located upstream of the high-pressure element 2b.

[0105] The outlet line 6 of device 1 is also provided with a final cooler in the form of an air-cooled cooler 12, which is equipped with a fan 10 whose speed cannot be adjusted.

[0106] The operation is otherwise similar to the embodiments described above.

[0107] In this case, when heat recovery between the low-pressure element 2a and the high-pressure element 2b is active, and / or when one of the two parallel-installed two-stage systems is switched off or not operating, each fan 13 can be adjusted to the minimum required speed.

[0108] In the embodiments described above, each air-cooled cooler 9, 12 is cooled by one fan 10, 13, but it is not excluded that the air-cooled coolers 9, 12 are cooled by two or more fans 10, 13, and / or that one fan 10, 13 cools multiple air-cooled coolers 9, 12.

[0109] In all the embodiments described above, the air-cooled cooler 12 of the outlet line 6 of the device 1 is equipped with a fixed-speed fan 10, but it is not excluded that the air-cooled cooler 12 is equipped with a variable-speed fan 13.

[0110] Figure 3 illustrates this point with a dotted line.

[0111] The variable-speed fan 13 includes a fan motor 14 driven by a control device 15, and the fan motor is connected to the control device 15.

[0112] If consumers do not require cooled compressed gas, and therefore the compressed gas supplied from the device does not need to be cooled, the speed of the fan 13 of the air-cooled cooler 12 can be controlled to the minimum required speed as described above.

[0113] In this case, it is not ruled out that there is no heat recovery system 11 at the outlet line 5 downstream of the high-pressure element 2b.

[0114] Although the present invention is not limited to the embodiments described and illustrated as examples, the air-cooled device and the method for controlling the air-cooled device according to the present invention can be implemented according to various alternative means without exceeding the scope of the present invention. [Explanation of symbols]

[0115] 1 device 2 elements 2a Low-pressure element 2b High-voltage element 3 entrance 4 exit 5 Exit Line 6 Exit Line 7 Liquid separator 8. Return line 9 Air-cooled cooler 10 Fans 11. Heat Recovery System 12 Air-cooled cooler 13 Fans 14 Variable Speed ​​Fan Motor 15 Control device 16 Temperature Sensor 17. Entrance Sensor 18. Pressure Sensor 19. Temperature sensor

Claims

1. A method for controlling an air-cooled device (1) for compressing a gas, wherein the air-cooled device (1) comprises at least one element (2) for compressing the gas, at least one air-cooled cooler (9, 12) for cooling a fluid within the air-cooled device (1), and two or more fans (10, 13), wherein at least one of the fans (10, 13) is a variable-speed fan (13) for generating a flow of cooling air to cool the air-cooled cooler (9, 12). The above method, when it is not necessary to cool the air-cooled coolers (9, 12), consists of controlling the speed of the variable-speed fan (13) to the minimum required speed in order to prevent backflow of cooling air moving in the opposite direction to the flow, The minimum required speed is, - Atmospheric pressure, ambient temperature and / or humidity of the gas in the environment of the air-cooled device (1), and / or - The pressure of the cooling airflow generated by the fan (13), and / or - The pressure of the cooling air flow generated by the fans (10, 13) at the common outlet for the cooling air of the air-cooled device (1), A method characterized by being determined based on the above.

2. The speed of the variable-speed fan (13) is - When the air-cooled coolers (9, 12) are used to cool the gas compressed by the air-cooled device (1), and / or when it is not necessary to cool the compressed gas, - When the heat recovery system (11) performs the required cooling of the air-cooled device (1) instead of the air-cooled coolers (9, 12), and / or - When element (2) is stopped or operating without load, The method according to claim 1, wherein the required speed is reduced to the minimum required speed.

3. The variable-speed fan (13) is driven by a fan motor (14) which is cooled by the fan (13). The method according to claim 1 or 2, wherein, in order to prevent the backflow of cooling air and to cool the fan motor (14) without excess or deficiency in order to avoid overheating the fan motor (14), the air-cooled cooler (9, 12) does not need to perform cooling, the speed of the variable-speed fan (13) is controlled to the minimum required speed.

4. The method according to claim 3, wherein the minimum required speed is determined based on the temperature of the fan motor (14) of the variable-speed fan (13).

5. The method according to claim 4, wherein the temperature of the fan motor (14) is representative of the temperature of one or more bearings of the fan motor (14).

6. The method according to claim 4, wherein the temperature of the fan motor (14) is representative of the temperature of one or more windings of the fan motor (14).

7. The method according to claim 1 or 2, wherein the minimum required speed is a predetermined fixed value determined based on the worst-case scenario of the operating modes of the other fans (10) and / or air-cooled coolers (9, 12) of the air-cooled device (1).

8. An air-cooled device for compressing a gas, comprising: at least one element (2) for compressing the gas; at least one air-cooled cooler (9, 12) for cooling the fluid within the air-cooled device (1); and two or more fans (10, 13), wherein at least one of the fans (10, 13) is a variable-speed fan (13) for generating a flow of cooling air to cool the air-cooled cooler (9, 12). The air-cooled device is characterized in that the variable-speed fan (13) is equipped with a control device (15) configured to perform the method described in claim 1 or 2.

9. The air-cooled device (1) comprises a plurality of air-cooled coolers (9, 12) for cooling one or more fluids within the air-cooled device (1) and a plurality of variable-speed fans (13), wherein the variable-speed fans (13) are equipped with the control device (15) configured to perform the method described in claim 1 or 2, as described in claim 8.

10. The air-cooling device according to claim 9, wherein at least one of the variable-speed fans (13) is equipped with a separate sub-control device.

11. The air-cooling device according to claim 9, wherein one control device (15) is provided for all of the variable-speed fans (13).

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