Method for controlling a first reference temperature of a device for compressing a gas

Abstract

A method for controlling a first reference temperature in an apparatus (1) for compressing a gas, the apparatus (1) comprising: an oil-injected element (2) for compressing the gas; and an oil injection pipe network (6) for injecting oil into the oil-injected element (2); the oil injection pipe network (6) comprising distribution means (8) for distributing oil to a first part and a second part; an oil cooler (10) cooled by a fan (9) for cooling the first part; and a bypass (11) for bypassing the second part over the oil cooler (10); wherein first a distribution rate of the first part is controlled to a required distribution rate, and then a speed of the fan (9) is controlled to a required speed, optionally based on the distribution rate, the distribution rate being controlled by a control unit (15) based on a non-fuzzy logic algorithm.

Description

[Technical field]

[0001] The present invention relates to a method for controlling a first reference temperature of a device for compressing a gas to a desired temperature value.

[0002] In this specification, "gas compressing apparatus" may refer to both compressor apparatus for compressing atmospheric gases to superatmospheric pressures, and vacuum pump apparatus for drawing a vacuum in a user network or enclosed space.

[0003] More particularly, the invention relates to a method for controlling a first reference temperature of an apparatus to a first desired temperature value, the apparatus comprising the following components: - an oil-injected element for compressing the gas; an oil injection pipe network having an outlet for injecting oil into the oil-injected element; The oil injection pipe network is - a distribution means for distributing oil between the first portion and the second portion; a fan-cooled oil cooler for cooling the first part; a bypass for routing the second portion past the oil cooler; wherein first the distribution rate of the first portion is controlled to a distribution rate required to bring a second reference temperature of the device to a second desired temperature value, and subsequently the speed of the fan is controlled to a speed required to bring the first reference temperature to the first desired temperature value.

[0004] In this specification, "reference temperature of the apparatus" means the temperature at a specific reference location of the apparatus, for example the temperature at the outlet of an oil-injected element where the gas temperature of the apparatus is usually highest, or the temperature at the outlet of an oil-injected pipe network where the oil temperature is important for cooling and lubrication of the apparatus.

[0005] In this specification, the "distribution ratio of the first portion" means the ratio of the flow rate or amount of the first portion to the total flow rate or amount of oil. Therefore, this distribution ratio can range from 0 to 100%. [Background technology]

[0006] The need and the method for controlling a particular reference temperature of a gas compressing device to a desired temperature value are already known.

[0007] On the one hand, the reference temperature must not fall below a minimum level, for example in order to avoid the formation of condensate from the gas, which would adversely affect the cooling or lubricating capacity of the oil in the device and further lead to corrosion of the components of the device, resulting in a shortened service life.On the other hand, it is also conceivable that the reference temperature should not be higher than a maximum level, for example in order to avoid damage to the device, for example due to deterioration of the oil in the device or deformation of the components in the device.

[0008] In some existing systems that include an oil-injected element for compressing gas and an oil injection pipe network for injecting oil into the oil-injected element, the reference temperature is controlled to a desired temperature using a thermostatic control valve with a fixed temperature setpoint and a fixed speed fan to cool the oil in the oil injection pipe network, and the fan is shut off when the reference temperature falls below a maximum level.

[0009] Tests have shown that devices using thermostatically controlled valves with fixed set temperatures and fans with fixed speeds are not necessarily energy efficient. Even if the reference temperature does not significantly exceed the maximum level, the fan is always started at a fixed speed, which causes the reference temperature to drop quickly and requires the fan to be stopped quickly. In the worst case, the reference temperature can drop too far below the minimum level, increasing the risk of condensation forming inside the device.

[0010] Other existing devices use thermostatically controlled valves and variable speed fans that are controlled with a PID controller. Such systems typically have separate control circuits for controlling the thermostatically controlled valve and the fan.

[0011] Tests have shown that such devices can exhibit erratic and oscillatory behavior due to interference between separate control circuits, the adverse effects of which include possible emergency shutdown of the device, damage to mechanical components of the device, and premature wear of various components of the device.

[0012] WO 2018 / 033827 describes a method for controlling the outlet temperature of an apparatus having an oil-injected element for compressing a gas and an oil injection pipe network for injecting oil into the oil-injected element, in which the position of a thermostatic control valve is controlled by applying a fuzzy logic algorithm to a measurement of the outlet temperature, and the speed of a fan for cooling the oil is controlled based on applying the fuzzy logic algorithm and further on the position of the thermostatic control valve.

[0013] The drawback of using a fuzzy logic algorithm is that it is a complex "multiple-input-multiple-output" (MIMO) computational algorithm. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] International Publication No. 2018 / 033827 Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention aims to overcome at least one of the above and / or other disadvantages.

[0016] More specifically, the object of the present invention is to provide a simple method for controlling the reference temperature of an apparatus for compressing a gas to a desired temperature value, which, on the one hand, uses as many separate sub-circuits as possible with the simplest possible calculation algorithms, but on the other hand, also has as little interference as possible between the separate control circuits in the apparatus. [Means for solving the problem]

[0017] For this purpose, the invention relates to a method for controlling a first reference temperature of a gas compression device to a desired temperature value, the device comprising the following components: an oil-injected element for aspirating gas at an inlet of the device and compressing the gas at an outlet of the oil-injected element to a working pressure; an oil injection pipe network having an outlet for injecting oil into the oil-injected element; The oil injection pipe network is - a distribution means for distributing oil between the first portion and the second portion; a fan-cooled oil cooler for cooling the first part; a bypass for routing the second portion past the oil cooler; Equipped with First, - a required distribution rate of the first portion is determined to bring a second reference temperature of the device to a second desired temperature value; - the distribution rate of the first portion is controlled to a desired distribution rate; after that - a required speed of the fan is determined to bring the first reference temperature to a first desired temperature value, and if the first reference temperature is the same as a second reference temperature, the required speed is determined based on the second desired temperature value and a distribution ratio; -The fan speed is controlled to the required speed, The distribution ratio is determined by the control unit. a first current value for a second reference temperature, and - a second desired temperature value, The control is based on a non-fuzzy logic algorithm with the above as input.

[0018] The advantage of this is that the distribution ratio is controlled by a standard controller, e.g. a PID controller or an ON / OFF controller, thus avoiding the use of complex "multiple input-multiple output" calculation algorithms as described in WO 2018 / 033827.

[0019] Nevertheless, the device according to the invention has the same basic advantages as described in WO 2018 / 033827.

[0020] More specifically, if the first reference temperature is the same as the second reference temperature, the method according to the invention also avoids any interference between the control of the distribution ratio and the control of the fan speed, in stark contrast to the risk of this kind of interference strictly warned about in the case of devices using SISO control units for the control of the distribution ratio and for the control of the variable speed fan on page 2, lines 18-27 of WO 2018 / 033827.

[0021] In a preferred embodiment of the method according to the invention, the second desired temperature value is determined based on a maximum temperature value within a group of one or more temperature values.

[0022] As a result, the second desired temperature value can be determined based on any number of desired purposes.

[0023] Furthermore, the second desired temperature value can be adjusted to the most relevant purpose depending on the operating area of ​​the device.

[0024] In a more preferred embodiment of the method according to the invention, the first temperature value in the group is determined such that the temperature of the compressed gas at the outlet is: the first condensation temperature of the compressed gas at the outlet, or - a first condensation temperature plus a first safety margin; represents the value of the second reference temperature, which is equal to

[0025] In this way, when the second desired temperature value is determined, the first objective is taken into account with respect to avoiding the formation of condensate in the device.

[0026] Preferably, the first temperature value is limited in this respect according to a first temperature interval between a first minimum temperature limit value and a first maximum temperature limit value.

[0027] this is, if the first temperature value is lower than the first minimum temperature limit, the first temperature value is set equal to the first minimum temperature limit; if the first temperature value is higher than the first maximum temperature limit, the first temperature value is set equal to the first maximum temperature limit; - if the first temperature value is in a first temperature interval between a first minimum temperature limit value and a first maximum temperature limit value, the first temperature value is not changed; This means that...

[0028] By limiting the first temperature value to a first temperature interval, safety constraints can be taken into account, for example with respect to minimum and maximum operating temperatures of the device.

[0029] In a further preferred embodiment of the method according to the invention, the second temperature value in the group represents a second reference temperature value at which the specific energy requirement of the device is minimal.

[0030] In this way, when the second desired temperature value is determined, the second objective is taken into account in terms of minimizing the specific energy requirement and, consequently, maximizing the energy efficiency of the device.

[0031] Preferably, the second temperature value is at least a second current value representative of the operating pressure, and a third current value representative of the temperature of the gas at the inlet, is determined based on:

[0032] In the context of the present invention, a "current value representative of" a particular parameter does not necessarily mean that the current value is equal to the value of this parameter, but rather that the current value can be derived from the value of this parameter.

[0033] In this way, the second temperature value is determined based on two standard state variables of the device, the values ​​of which can be reliably and easily measured using accurate, relatively inexpensive and readily available sensors.

[0034] More preferably, when the oil-injected element is driven by a variable speed motor, the second temperature value is further determined based on a tenth current value representative of the rotational speed of the variable speed motor.

[0035] As a result, the rotational speed of the variable speed motor, and consequently the variable power supplied by the variable speed motor to the gas compression process, is taken into account when determining the second temperature value.

[0036] Furthermore, the second temperature value is alternatively or additionally preferably limited according to a second temperature interval between a second minimum temperature limit value and a second maximum temperature limit value.

[0037] this is, if the second temperature value is lower than the second minimum temperature limit, the second temperature value is set equal to the second minimum temperature limit; if the second temperature value is higher than the second maximum temperature limit, the second temperature value is set equal to the second maximum temperature limit; if the second temperature value is in a second temperature interval between a second minimum temperature limit value and a second maximum temperature limit value, the second temperature value is not changed; This means that...

[0038] By limiting the second temperature value to a second temperature interval, safety constraints can be taken into account, for example with respect to minimum and maximum operating temperatures of the device.

[0039] In a further preferred embodiment of the method according to the invention, - the second reference temperature is controlled from the old temperature value to a second desired temperature value; and To determine the second desired temperature value, said maximum temperature value is limited according to a third temperature interval between, on the one hand, the old temperature value minus the maximum temperature decrease value and, on the other hand, the old temperature value plus the maximum temperature increase value.

[0040] In this way, the variation of the second reference temperature can be limited when the second reference temperature is controlled to a second desired temperature value, for example to take into account safety constraints related to temperature variations within the device.

[0041] Preferably, the second reference temperature is controlled from the old temperature value to the second desired temperature value in a preset time interval, and the maximum temperature decrease value and the maximum temperature increase value are positively dependent on the length of the preset time interval.

[0042] In this way, the variation of the second reference temperature can be limited according to a preset time interval, for example to take into account safety constraints related to maximum absolute temperature time gradients in the device.

[0043] In a further preferred embodiment of the method according to the invention, the required distribution rate is determined on the basis of a first ratio between the first current value and the second desired temperature value.

[0044] The first ratio is a measure of the deviation of the first current value from the second desired temperature value.

[0045] If the first ratio is smaller than 1, this indicates that the value of the second reference temperature is too low, and the requested distribution ratio should be selected to be lower than the current value of the distribution ratio, if possible, in which case less oil will be sent to the oil cooler, which will result in less cooling of the injected oil and an increase in the second reference temperature.

[0046] If the first ratio is greater than 1, this indicates that the value of the second reference temperature is too high, and the requested distribution ratio should be selected to be higher than the current value of the distribution ratio; in such a case, more oil will be sent to the oil cooler, so that the injected oil is cooled more and the second reference temperature will decrease.

[0047] Preferably, the requested allocation percentage depends on the first ratio according to a first monotonically increasing function between a minimum value of zero and a maximum value of 100%.

[0048] In this way, the change in the distribution rate relative to the requested distribution rate will never be small when there is a large deviation between the second reference temperature and the second desired temperature value.

[0049] Alternatively, and preferably, the desired distribution ratio is: The first current value is - higher than a second desired temperature value or a second desired temperature value plus a second safety margin, or during the first time period, the temperature is greater than a second desired temperature value or the second desired temperature value plus a second safety margin; The maximum value is 100%. - Otherwise, it is the minimum zero value.

[0050] This is a simple ON / OFF control and all oil is sent to the oil cooler if the reference temperature is likely to be too high, more specifically, if it is higher than a second desired temperature value or the second desired temperature value plus a second safety margin.

[0051] By applying the first period before controlling the distribution rate to a state where all the oil is sent to the oil cooler, it is possible to avoid a rapid and unnecessary switching of the distribution rate from a minimum value of zero to a maximum value of 100% and back to a value of zero, which would otherwise occur if the second reference temperature is higher than the second desired temperature or the second desired temperature plus a second safety margin for a limited harmless period shorter than the first period.

[0052] Thus, by applying the first period, the control dynamics of the distribution means and the device generally do not react or react less with respect to harmless short-term increases in the second reference temperature, so that the control dynamics are more stable than if the first period were not applied.

[0053] In a further preferred embodiment of the method according to the invention, the second reference temperature is is the temperature of the gas at the outlet of the oil-injected element, or The temperature of the oil at the outlet of the oil injection pipe network.

[0054] At the outlet of the oil-injected element, the pressure of the gas in the device is the highest. As a result, the risk of condensation formation is also highest at this outlet, since the higher the gas pressure, the higher the condensation temperature of the gas. It is necessary to ensure that the temperature of the gas at the outlet does not fall below the condensation temperature of the gas at this outlet. The temperature of the gas at the outlet of the oil-injected element is therefore the relevant second reference temperature in the device with the aim of avoiding the formation of condensation in the device.

[0055] The temperature of the oil at the outlet of the oil injection pipe network determines the cooling capacity of the oil. It is necessary to ensure that this cooling capacity is not too high in order to prevent the temperature of the gas at a given location in the device from falling below the condensation temperature of the gas at this location. The temperature of the oil at the outlet of the oil injection pipe network is therefore a relevant second reference temperature in the device, also with the aim of avoiding the formation of condensate in the device.

[0056] In a further preferred embodiment of the method according to the invention the required fan speed is determined based on a maximum speed value from a set of one or more speed values.

[0057] This allows the required speed to be determined based on as many criteria as desired.

[0058] Furthermore, the required speed can be adjusted to the most relevant criteria depending on the operating area of ​​the device.

[0059] In a more preferred embodiment of the method according to the invention, the first speed value in said set represents a fan speed value required to achieve a second desired temperature value relative to a second reference temperature.

[0060] In this way, the first criterion is taken into account with respect to achieving the second desired temperature value when determining the required fan speed. In other words, control of the fan in this respect has the same objective as the distribution ratio control as described above, and thus helps achieve the goals of the distribution ratio control.

[0061] In a further preferred embodiment of the method according to the invention, - if the fourth current value for the second reference temperature is greater than a preset minimum temperature, and the fifth current value related to the distribution ratio is higher than a preset minimum distribution ratio and the fourth current value is higher than a desired temperature value; The first velocity value is at least a sixth current value representative of the operating pressure, and a seventh current value representing the temperature of the gas at the inlet, is determined based on:

[0062] In this way, the first speed value is determined on the basis of two standard state variables of the device, the values ​​of which can be reliably and easily measured using accurate, relatively inexpensive and readily available sensors.

[0063] Preferably, when the oil-injected element is driven by a variable speed motor, the first speed value is further determined based on an eleventh current value representative of the rotational speed of the variable speed motor.

[0064] As a result, the rotational speed of the variable speed motor, and consequently the variable power supplied by this variable speed motor to the gas compression process, is taken into account when the first speed value is determined.

[0065] Alternatively or additionally, preferably the fourth current value is greater than the second desired temperature value plus the first tolerance value, or - during a second time period, the fourth current value is greater than a second desired temperature value plus the first tolerance value; or the fourth current value is less than a second desired temperature value minus a second tolerance; or during a third time period, if the fourth current value is less than the second desired temperature value minus the second tolerance value; The first velocity value is at least - a fifth current value for the distribution ratio, and a second ratio between the fourth current value and the second desired temperature value; The same will be further determined based on:

[0066] By determining the first speed value based on the fifth current value related to the distribution ratio, the distribution ratio can be taken into account when determining the fan speed, and thus any interference between the fan speed control and the distribution ratio control can be avoided.

[0067] The second ratio is a measure of the deviation between the fourth current value and the second desired temperature value.

[0068] If the second ratio is smaller than 1, this indicates that the value of the second reference temperature is too low, and the requested distribution fraction should be selected to be lower than the current value of the distribution fraction, in which case less oil will be sent to the oil cooler, resulting in less cooling of the injected oil and an increase in the second reference temperature.

[0069] If the second ratio is greater than 1, this indicates that the value of the second reference temperature is too high, and the requested distribution ratio should be selected to be higher than the current value of the distribution ratio, in which case more oil will be sent to the oil cooler, resulting in more cooling of the injected oil and a decrease in the second reference temperature.

[0070] More preferably, the first speed value depends on the second ratio according to a second monotonically increasing function.

[0071] In this way, when there is a large deviation between the second reference temperature and the second desired temperature value, the change in fan speed relative to the first speed value will not be small.

[0072] Alternatively or additionally, and more preferably, the first speed value depends on the fifth current value according to a third monotonically increasing function.

[0073] As a result, when controlled to the first speed value, the fan speed will not become slower when the distribution fraction increases, and will not become faster when the distribution fraction decreases.

[0074] This is advantageous for the stability of the fan speed control, since it allows the fan speed to be gradually increased as the distribution percentage increases and gradually decreased as the distribution percentage decreases, thereby preventing the fan from suddenly having to start up at high speed from a stopped state when the distribution percentage increases from a zero value, or from suddenly going from high speed to a stopped state when the distribution percentage suddenly drops to a zero value.

[0075] In a further preferred embodiment, if the device comprises an aftercooler for cooling the compressed gas downstream of the oil-injected element, if the eighth current value for the minimum effective temperature in the aftercooler is higher than the value for the required minimum effective temperature, the second speed value in the set is a first velocity value, and a third ratio between the eighth current value and the value of the required minimum effective temperature; is determined based on Otherwise, the second speed value is set equal to zero.

[0076] In this way, if the eighth current value for the minimum useful temperature of the aftercooler is too high, the fan speed can be controlled to a second speed value higher than the first speed value, so that the fan is utilized to sufficiently cool the aftercooler in addition to cooling the oil cooler, and the maximum temperature of the gas in the aftercooler can be controlled and limited to the required minimum useful temperature.

[0077] Preferably, the required minimum effective temperature is equal to the second condensation temperature of the aftercooler gas plus an offset.

[0078] The formation of condensate in the aftercooler can be avoided by offsetting.

[0079] Alternatively or additionally, the second speed value depends on the third ratio, preferably according to a fourth monotonically increasing function.

[0080] In that case, if there is a large deviation of the minimum effective temperature beyond the value for the required minimum effective temperature, the second speed value will not be decreased so that the minimum effective temperature is not allowed to deviate further from the value for the required minimum effective temperature at the accelerating speed.

[0081] In a further preferred embodiment of the method according to the invention the third speed value in the set is: a ninth current value for the first reference temperature, and a preset maximum value for the first reference temperature, and a third speed value is determined based on - equal to zero if the ninth current value is lower than a preset maximum value; and - If the ninth current value is higher than the preset maximum, it is equal to a value representing the maximum speed of the fan.

[0082] In this way, the fan speed can be adjusted to a third speed value determined by exceeding a preset maximum value, this preset maximum being, for example, a maximum value of a first reference temperature of a gas above which the first reference temperature must not rise for safety reasons.

[0083] The present invention further comprises, for carrying out a method according to any of the above-described embodiments, a first computing and control unit, comprising a control unit for controlling a second reference temperature in the device for compressing a gas to a second desired temperature value; a second computing and control unit for controlling a first reference temperature of the device to a first desired temperature value; The present invention relates to a computer controlled assembly comprising:

[0084] Finally, the invention relates to a device for compressing gas, comprising such a computer-controlled assembly according to the invention.

[0085] It is clear that such a computer controlled assembly and such an apparatus offer the same advantages as the method according to the embodiment of the invention described above.

[0086] In order to better explain the characteristics of the present invention, a number of preferred embodiments of the method, computer-controlled assembly and device according to the invention are described below by way of non-limiting example with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0087] [Figure 1] 1 shows an apparatus equipped with a computer controlled assembly according to the present invention; [Diagram 2]1 shows a schematic overview of the method according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0088] FIG. 1 shows a device 1 for compressing a gas, which comprises an oil-injected element 2 for aspirating gas at an inlet 3 of the device 1 and compressing this gas at its outlet 4 up to a working pressure.

[0089] Within the scope of the present invention, the device 1 is to be understood as a complete compressor or vacuum pump installation, in particular comprising an oil-injected element 2 in the form of a compressor or vacuum pump element, respectively, all typical connecting pipes and valves, a possible housing of the device 1, and a motor 5 driving the oil-injected element 2.

[0090] In the context of the present invention, an oil-filled element 2 is understood as an element housing in which gas is compressed by the movement of a rotating rotor or of a reciprocating piston.

[0091] In this regard, by way of non-limiting example, the oil-injected element 2 may comprise one or more screw rotors, gear rotors, baffles, lobes or pistons.

[0092] If the apparatus 1 comprises a compressor element, the inlet 3 of the apparatus 1 is typically fluidly connected to the atmospheric environment of the apparatus 1. If the apparatus 1 comprises a vacuum pump element, the inlet 3 is typically fluidly connected to a user network or an enclosed space at sub-atmospheric pressure.

[0093] Furthermore, the device 1 comprises an oil injection pipe network 6 having an outlet 7 for injecting oil into the oil-injected element 2 .

[0094] In this respect, it is not excluded within the scope of the present invention for the oil-injection pipe network 6 to comprise a plurality of outlets 7 for injecting oil into the oil-injected element 2 .

[0095] Compression of the gas in the oil-injected element 2 generates heat of compression which heats the gas. In order to keep the temperature of the compressed gas at the outlet 4 of the oil-injected element 2 below a certain maximum safety limit, the temperature of the injected oil must be below a maximum level corresponding to this safety limit. On the other hand, the temperature of the compressed gas at the outlet 4 must not fall below a first condensation temperature of the gas at the outlet 4 or below the first condensation temperature plus a first safety margin in order to avoid the formation of condensate at the outlet 4. As a result, the temperature of the injected oil must be above a minimum level corresponding to this first condensation temperature or this first condensation temperature plus a first safety margin. The temperature of the gas at the outlet 4 of the oil-injected element 2 and, accordingly, the temperature of the oil at the outlet 7 of the oil-injected pipe network 6 must therefore be controlled at both ends to values ​​within a correspondingly limited temperature interval.

[0096] For this purpose, the oil injection pipe network 6 is - a distribution means 8, for example a thermostatically controlled valve, for distributing the oil between the first and second portions; an oil cooler 10 cooled by a fan 9 for cooling the first part; a bypass 11 for bypassing the second portion beyond the oil cooler 10; Equipped with.

[0097] The speed of the fan 9 is variable and is driven by a second motor 12. This makes it possible, for example, to control the cooling of the first portion of the injected oil by adjusting the speed of the fan 9.

[0098] More generally, in the present invention, the speed of the fan 9 is adjusted such that a first reference temperature of the device 1 is controlled to a first desired temperature value.

[0099] The distribution means 8 and the bypass 11 are provided for diverting the second part of the injected oil beyond the oil cooler 10, thus more or less limiting the cooling of the injected oil by the oil cooler 10 by controlling the distribution rate of the first part of the oil. In this way, the second reference temperature of the device 1 can be controlled to a second desired temperature value, for example the temperature of the compressed gas at the outlet 4 of the oil-injected element 2 or the temperature of the oil at the outlet 7 of the oil-injected pipe network 6. The first reference temperature controlled by the fan 9 can be the same as the second reference temperature, in which case the first desired temperature value is equal to the second desired temperature value.

[0100] To control the distribution ratio, the device 1 comprises a first computing and control unit 13. This first computing and control unit 13 comprises: a calculation unit 14 for determining a second desired temperature value; a control unit 15 for adjusting the distribution ratio of the first portion for a second desired temperature based on a first current value for a second reference temperature; Equipped with.

[0101] In this case, the control device 15 is designed, for example, as a PID controller or an ON / OFF controller.

[0102] In this case, the first current value related to the second reference temperature is provided by measurement using a temperature sensor, for example a first temperature sensor 16 at the outlet 4 of the oil-injected element 2 or a second temperature sensor 17 at the outlet 7 of the oil-injected pipe network 6.

[0103] The second desired temperature value comprises at least: a second current value indicative of the actuation pressure (this second current value is provided, for example, by measurement using a first pressure sensor 18 at the outlet 4 of the oil-injected element 2), and a third current value indicative of the temperature of the gas at the inlet 3 (this third current value is for example provided by measurement with a third temperature sensor 19 at the inlet 3 of the device 1), is determined by the calculation unit 14 based on

[0104] In addition, it is also possible to take into account a measurement of the atmospheric pressure at the inlet 3, which is for example provided by a measurement with a second pressure sensor 20 at the inlet 3 of the device 1. However, the absolute standard value of the atmospheric pressure can also simply be assumed to be 1 bar or 1 atmosphere, which means that this measurement of the atmospheric pressure, and thus the second pressure sensor 20, is not strictly necessary for the invention.

[0105] It is likewise possible to take into account the measurement of the relative humidity at the inlet 3, for example using the humidity sensor 21 at the inlet 3. Alternatively, a worst-case relative humidity value of 100% can be assumed for this gas at the inlet 3. In the latter case, the measurement of the relative humidity at the inlet 3, and thus the humidity sensor 21, is not strictly necessary for the invention.

[0106] Based on the second desired temperature value determined by the calculation unit 14 and the first current value for the second desired temperature value, the control unit 15 determines a required distribution ratio and controls the distribution ratio of the first portion of oil to this required distribution ratio.

[0107] 1, the distribution means 8 is arranged downstream of the oil cooler 10 and the bypass 11. However, in the context of the present invention, it is not excluded that the distribution means 8 is arranged upstream of the oil cooler 10 and / or the bypass 11, for example at the point where the piping to the oil cooler 10 and the bypass 11 branch off from each other.

[0108] To control the speed of the fan 9 , the device 1 comprises a second arithmetic and control unit 22 .

[0109] The second computing and control unit 22 together with the first computing and control unit 13 form a computing and control assembly according to the present invention.

[0110] The control of the fan 9, analogous to the control of the distribution rate of the first portion of oil already mentioned above, can have the purpose of controlling the second reference temperature to a second desired temperature value, in which case the first reference temperature will be the same as the second reference temperature and the first desired temperature value will be equal to the second desired temperature value.

[0111] In this case, if the fourth current value related to the second reference temperature is higher than the second desired temperature value and the fifth current value related to the distribution ratio is higher than a preset minimum distribution ratio, then the second arithmetic and control unit 22 performs at least a sixth current value indicative of the actuation pressure (the sixth current value is provided, for example, by measurement with the first pressure sensor 18 at the outlet 4 of the oil-injected element 2), and a seventh current value indicative of the temperature of the gas at the inlet 3 (the seventh current value is for example provided by measurement using a third temperature sensor 19), The required speed of the fan 9 is determined based on

[0112] The fourth current value may be provided, for example, by measurement with the first temperature sensor 16 or the second temperature sensor 17 .

[0113] The second desired temperature value is obtained from the computing unit 14 by the second computing and control unit 22 .

[0114] In order then to be able to take into account the distribution rate of the first part of oil when controlling the speed of the fan 9, a fifth current value related to the distribution rate can also be taken into account in order to determine a specific value for the required speed of the fan 9. This fifth current value can be provided by measurement using the position or flow sensor 23 of the distribution means 8, which allows to measure the opening of the distribution means 8 and thus the distribution rate of the first part of oil.

[0115] Of course, in the context of the present invention, it is also possible for the second arithmetic and control unit 22 to obtain the fifth current value directly from the control unit 15 (not shown in FIG. 1), in which case the position sensor or flow sensor 23 is no longer necessary and can be omitted.

[0116] FIG. 1 also shows that the gas compressed by the oil-injected element 2 can be passed, for example, through an oil separator 24, where the compressed gas is purified by separating the oil previously injected into the oil-injected element 2 from the compressed gas before the resulting purified compressed gas exits the apparatus 1.

[0117] The oil separated in a possible oil separator 24 is in this case preferably re-injected into the oil-injected element 2 via the oil-injection pipe network 6 .

[0118] Optionally, the compressed gas, whether purified or not, can also be sent to an aftercooler 25 before leaving the device 1. In this aftercooler 25, the compressed gas can be cooled by the same fan 9 as used in the oil cooler 10. The speed of the fan 9 can then be controlled so that the minimum effective temperature of the gas in the aftercooler 25 is below the required minimum effective temperature. In this case, the first reference temperature is equal to the minimum effective temperature of the gas in the aftercooler 25. The fan 9 is controlled on the basis of the required minimum effective temperature and an eighth current value related to the minimum effective temperature, which is measured, for example, by means of a fourth temperature sensor 26 at a suitable position in the aftercooler 25.

[0119] The speed of the fan 9 can also be controlled based on a preset maximum value for a first reference temperature, for example in places in the device 1 where the temperature is generally relatively high and needs to be kept below the maximum value for safety reasons, where the first reference temperature is for example the temperature of the motor 5, the second motor 12 or the frequency converter of the device 1. The first reference temperature can also be the temperature of the gas leaving the aftercooler 25.

[0120] The speed of the fan 9 is then controlled using as input a ninth current value related to the first reference temperature, this ninth current value being measured, for example, by means of the fifth temperature sensor 27 .

[0121] In the context of the present invention, it is not impossible for this fifth temperature sensor 27 to coincide for example with the first temperature sensor 16 or the second temperature sensor 17 .

[0122] If the motor 5 is a variable speed motor, the calculation unit 14 can also take into account a tenth current value indicating the rotational speed of the motor 5 when determining the second desired temperature, and the second calculation control unit 22 can also take into account an eleventh current value indicating the rotational speed of the motor 5 when determining the required speed of the fan 9.

[0123] FIG. 2 shows a schematic overview of the method according to the invention.

[0124] As mentioned above, the second desired temperature value relative to the second reference temperature is determined in the calculation unit 14 .

[0125] In this case, the second desired temperature value is determined based on the maximum temperature value within the group of two temperature values, which is illustrated in Figure 2 by the first maximization operator MAX1.

[0126] Thus, the first temperature value T1 in the above group represents a second reference temperature value at which the temperature of the compressed gas at the outlet 4 of the oil-injected element 2 is equal to a first condensation temperature of the compressed gas at the outlet 4 of the oil-injected element 2 or to this first condensation temperature plus a first safety margin.

[0127] The first condensation temperature can be determined in a manner known to those skilled in the art, for example as described in WO 2018 / 033827.

[0128] When determining the first temperature value, a value T representing the first condensation temperature with or without a first safety margin is selected. cond is also the first minimum temperature limit T min,1 and the first maximum temperature limit T max,1 The limiting of this first condensing temperature plus or without a first safety margin is performed in a first limiting operator LIM1.

[0129] If the second reference temperature is the temperature of the gas at the outlet 4 of the oil-filled element 2, then the first minimum temperature limit T min,1 and the first maximum temperature limit T max,1 The value of may vary, for example, between 0° C. and 120° C., and this value may be set with an accuracy of, for example, 1° C.

[0130] The second temperature value in the group is the second reference temperature value T at which the specific energy requirement of the device 1 is minimal. SER Represents.

[0131] If the motor 5 is a fixed speed motor, this second reference temperature value T SER can be calculated based on the second current value α2 representative of the operating pressure and the third current value α3 representative of the temperature of the gas at the inlet 3, for example according to the following formula: T SER =B·α3+C·α2+D (Eq. 1)

[0132] If the motor 5 is a variable speed motor, the value of this second reference temperature T SER a second current value α2 representing the working pressure, a third current value α3 representing the temperature of the gas at the inlet 3, and a tenth current value α 10 Based on this, it can be calculated, for example, according to the following formula: T SER = A α 10 +B·α3+C·α2+D (Eq. 2)

[0133] Here, the current value α 10 is the value of the rotational speed of the motor 5 determined as a percentage of the maximum rotational speed of the motor 5.

[0134] In the above Equations 1 and 2, the value of the second reference temperature T SER is expressed in °C, the second current value α2 is determined as the operating pressure in bar and the third current value α3 is determined as the temperature of the gas at the inlet 3 in °C.

[0135] If the second reference temperature is the temperature of the gas at the outlet 4 of the oil-injected element 2, then the possible value intervals for the constants A, B, C and D in the above equations 1 and 2 are as follows: JPEG2025502459000002.jpg9150 JPEG2025502459000003.jpg7150 JPEG2025502459000004.jpg7150 JPEG2025502459000005.jpg7150

[0136] Once the second temperature value T2 has been determined, the value T SER is the second minimum temperature limit T min,2 and the second maximum temperature limit T max,2 The temperature can be limited according to a second temperature interval between the value T SER This restriction of is performed by a second restriction operator LIM2.

[0137] If the second reference temperature is the temperature of the gas at the outlet 4 of the oil-filled element 2, then the second minimum temperature limit T min,2 and the second maximum temperature limit T max,2 The value of may vary, for example, between 0° C. and 120° C., and this value may be set with an accuracy of, for example, 1° C.

[0138] Optionally, if the second reference temperature is controlled from an old temperature value to a second desired temperature value, the maximum temperature value resulting from the first maximization operator MAX1 is on the one hand a maximum temperature decrease value ΔT max,down On the other hand, the old temperature value is multiplied by the maximum temperature increase ΔT max,up This makes it possible to avoid an excessive decrease or increase in the second reference temperature. This limiting of the maximum temperature value is performed by a third limiting operator LIM3.

[0139] Here, a preset time interval Δt can be determined for controlling the old temperature value to the second desired temperature value, and a maximum temperature reduction value ΔT max,down and maximum temperature increase value Δ Tmax,up depends positively on the length of this preset time interval Δt.

[0140] Optionally, the second desired temperature value is on the other hand less than a third minimum temperature limit value T min,3 and on the other hand the third maximum temperature limit T max,3 and a fourth temperature interval between the first and second temperatures.

[0141] If the second reference temperature is the temperature of the gas at the outlet 4 of the oil-filled element 2, then the third minimum temperature limit T min,3 can be set as a value between 20° C. and 80° C., for example with an accuracy of 1° C., to prevent the formation of condensate at the outlet 4.

[0142] Alternatively, if the oil injection pipe network 6 further comprises a heat recovery system (not shown in FIG. 1) capable of recovering heat from the oil separated by the oil separator 24 to a heat absorbing fluid, the third minimum temperature value Tmin,3 can be set as a high value, for example 105° C. The third minimum temperature value Tmin,3 Such a high value of allows the heat recovery system to recover a greater amount of heat from the oil in the oil injection pipe network 6, even when the temperature of the heat absorbing fluid is relatively high.

[0143] The third maximum temperature value T max,3 can be set, for example, as a value between 100° C. and 120° C., with an accuracy of, for example, 1° C.

[0144] The second desired temperature value thus determined in the calculation unit 14 is further used in the control unit 15 for determining the required distribution proportion based on a first ratio β1 between the first current value α1 for the second reference temperature and this second desired temperature value.

[0145] The requested allocation percentage may be determined as a continuous percentage between a minimum value of zero and a maximum value of 100% depending on a first ratio β1 according to a first monotonically increasing function.

[0146] On the other hand, the required distribution ratio is, during the operation of the device 1, - maximum value 100% if higher than the second desired temperature value; - higher than a second desired temperature value or a second desired temperature value plus a second safety margin, or - during the first time period, higher than a second desired temperature value or the second desired temperature value plus a second safety margin; and - otherwise it is the minimum zero value, It can also be determined as a binary proportion.

[0147] Here, the second safety margin can be set to a value between, for example, 0°C and 20°C, with an accuracy of, for example, 0.1°C.

[0148] The first period may be set to a value between 0 and 255 seconds, for example.

[0149] Based on the required distribution rate determined by the control unit 15, the distribution means 8 are then operated to actually achieve this required distribution rate.

[0150] The required fan 9 speed for controlling the first reference temperature to the first desired temperature value is determined using the second calculation and control unit 22 .

[0151] For this purpose, the requested speed is selected as the highest speed value from a set of speed values, in this case three speed values, which is illustrated in Figure 2 by the second maximization operator MAX2.

[0152] The first speed value v1 in said set then represents the speed value of the fan 9 required to achieve a second desired temperature value relative to a second reference temperature.

[0153] If the device 1 is in the first operating range in which it has not yet warmed up, i.e. if the fourth current value α4 for the second reference temperature is lower than a preset minimum temperature, for example 90°C, required to end this first operating range of warming up, the first speed value v1 is equal to a zero value.

[0154] In a second operating range of the device 1, in which the fourth current value α4 is higher than the preset minimum temperature, if the distribution rate is lower than the preset minimum distribution rate or the fourth current value α4 is lower than the second desired temperature value, the first speed value v1 is still equal to zero value.

[0155] The predetermined minimum allocation percentage may be set, for example, as a value between, for example, 0% and, for example, 100%, with an accuracy of, for example, 1%.

[0156] On the other hand, in the second operating region, when the fifth current value α5 related to the distribution ratio is higher than the preset minimum distribution ratio and the fourth current value α4 is higher than the second desired temperature value, the first speed value v1 is at least a sixth current value α6 representative of the operating pressure, and a seventh current value α7, which represents the temperature of the gas at the inlet 3; is determined based on:

[0157] If the motor 5 is a variable speed motor, then when the first speed value v1 is determined, an eleventh current value α representing the rotation speed of the motor 5 is determined, for example according to the following formula: 11 will also be taken into consideration. v1=v 1,raw = E α 11 +F·α7+G·α6+H (Eq. 7)

[0158] Here, the current value α 11 is the value of the rotational speed of the motor 5 determined as a percentage of the maximum rotational speed of the motor 5.

[0159] In equation 7 above, the first speed value v1 is determined as a percentage of the maximum speed of the fan 9, the sixth current value α6 is determined as the operating pressure in bar and the seventh current value α7 is determined as the temperature of the gas at the inlet 3 in °C.

[0160] If the second reference temperature is the temperature of the gas at the outlet 4 of the oil-injected element 2, then the possible value intervals for the constants E, F, G, H in equation 7 are as follows: JPEG2025502459000006.jpg7150 JPEG2025502459000007.jpg7150 JPEG2025502459000008.jpg7150 JPEG2025502459000009.jpg7150

[0161] In the following cases, i.e. the fourth current value α4 is higher than the second desired temperature value plus the first tolerance value, or during the second time period, the fourth current value α4 is higher than the second desired temperature value plus the first tolerance value, or the fourth current value α4 is lower than the second desired temperature value minus a second tolerance value, or during a third time period, if the fourth current value α4 is lower than the second desired temperature value minus the second tolerance value; The first velocity value v1 is at least a fifth current value α5 for the distribution ratio, and a second ratio β2 between the fourth current value α4 and the second desired temperature value, The same will be further determined based on:

[0162] The first and second tolerance values ​​may for example be set between values ​​of for example 0°C and for example 20°C, with an accuracy of for example 0.1°C.

[0163] The second and third periods can be set, for example, between values ​​of 0 seconds and, for example, 255 seconds.

[0164] The first speed value v1 in this case preferably depends on the second ratio β2 according to a second monotonically increasing function and alternatively or additionally, preferably depends on the fifth current value α5 according to a third monotonically increasing function, for example according to the following equation: v1=v 1,raw ·α5^P·β2^Z (Eq. 12)

[0165] The possible value intervals for the constants P and Z in Equation 12 are as follows: P=0-4 (Equation 13) Z=0-4 (Equation 14)

[0166] A second velocity value v2 in the set is determined as follows: if the eighth current value α8 for the minimum effective temperature of the aftercooler 25 is higher than the value for the required minimum effective temperature, the second speed value v2 is a first velocity value v1, and a third ratio β3 between the eighth current value α8 and the required minimum effective temperature value, is determined based on Otherwise, the second velocity value v2 is set to zero.

[0167] The required minimum effective temperature is equal to the second condensation temperature of the gas in the aftercooler 25 plus an offset.

[0168] The second speed value v2 preferably depends on the third ratio β3 according to a fourth monotonically increasing function. If the eighth current value α8 for the minimum effective temperature of the aftercooler 25 is higher than the value for the required minimum effective temperature, the second speed value v2 is calculated, for example, according to the following formula: v2=v1-β3^P (Equation 15)

[0169] In equation 15 above, the second speed value v2 is determined as a percentage of the maximum speed of the fan 9.

[0170] The interval of possible values ​​of the constant P is already given in Equation 13.

[0171] The third velocity value in the set, v3, is a ninth current value α9 for the first reference temperature, and a preset maximum value for the first reference temperature, The third velocity value α9 is determined based on zero if the ninth current value α9 is lower than a preset maximum value; - the ninth current value α9 is a value that represents the maximum speed of the fan 9 if it is higher than a preset maximum value.

[0172] The preset maximum value can be set between a value of, for example, 90° C. and, for example, 120° C., with an accuracy of, for example, 1° C.

[0173] Finally, based on the required speed determined by the second arithmetic and control unit 22, the second motor 12 is activated and the fan 9 actually operates at the required speed.

[0174] The invention is not limited to the embodiments described and illustrated by way of example, and the method, the computing control device or the device according to the invention can be implemented in any and all variants without departing from the scope of the invention as defined in the claims. [Explanation of symbols]

[0175] 1 device 2 Oil-injected elements 6 Oil injection pipe network 8 Distribution means 9 Fan 10 Oil cooler 11 Bypass 15 Control Unit

Claims

1. A method for controlling a first reference temperature in a device (1) for compressing a gas to a first desired temperature value, said device (1) comprising the following components: - an oil-injected element (2) for aspirating said gas at an inlet (3) of said device (1) and compressing said gas to a working pressure at an outlet (4) of the oil-injected element (2); - an oil injection pipe network (6) having an outlet (7) for injecting oil into said oil-injected element (2); The oil injection pipe network (6) comprises: - distribution means (8) for distributing said oil between a first portion and a second portion; - an oil cooler (10) cooled by a fan (9) for cooling said first part; a bypass (11) for bypassing said second portion beyond said oil cooler (10); Equipped with First, - a required distribution rate of said first portion is determined in order to bring a second reference temperature of said device (1) to a second desired temperature value, - the distribution rate of the first portion is controlled to the required distribution rate, after that a required speed of said fan (9) is determined in order to bring a first reference temperature to a first desired temperature value, said required speed being determined on the basis of said second desired temperature value and said distribution ratio if said first reference temperature is the same as said second reference temperature, - the speed of said fan (9) is controlled to said required speed, The distribution ratio is controlled by a control unit (15): a first current value α for said second reference temperature 1 , and - said second desired temperature value, The method is controlled based on a non-fuzzy logic algorithm using the input.

2. The method of claim 1 , wherein the second desired temperature value is determined based on a maximum temperature value within a group of one or more temperature values.

3. The first temperature value T 1 the temperature of the compressed gas at the outlet (4) is a first condensation temperature of the compressed gas at the outlet (4), or the first condensation temperature plus a first safety margin; The second reference temperature value T cond The method of claim 2 , wherein

4. The first temperature value T 1 is the first minimum temperature limit value T min,1 and the first maximum temperature limit value T max,1 4. The method of claim 3, wherein the temperature is limited according to a first temperature interval between

5. The second temperature value T 2 The method according to any of claims 2 to 4, wherein represents the value of the second reference temperature at which the specific energy requirement of the device (1) is minimal.

6. The second temperature value T 2 At least a second current value α representative of said operating pressure 2 , and a third current value α representative of the temperature of the gas at the inlet (3) 3 , The method of claim 5 , wherein the step is determined based on

7. The second temperature value T 2 is the second minimum temperature limit value T min,2 and the second maximum temperature limit value T max,2 7. The method of claim 5 or 6, wherein the temperature is limited according to a second temperature interval between

8. - the second reference temperature is controlled from an old temperature value to a second desired temperature value; and To determine the second desired temperature value, the maximum temperature value is determined on the one hand by a maximum temperature decrease ΔT from the old temperature value. max,down on the other hand, the old temperature value plus a maximum temperature increase value ΔT max,up plus a third temperature interval between 8. The method according to claim 2, wherein the first and second electrodes are arranged in a first direction.

9. The second reference temperature is controlled from the old temperature value to the second desired temperature value in a preset time interval Δt, and the maximum temperature decrease value ΔT max,down and the maximum temperature increase value ΔT max,up The method of claim 8 , wherein x is positively dependent on the length of the preset time interval Δt.

10. The requested distribution ratio is the first current value α 1 and the second desired temperature value, 1 The method according to any one of claims 2 to 9, wherein the formula is determined according to

11. The requested allocation percentage varies according to a first monotonically increasing function with respect to the first ratio β between a minimum value of zero and a maximum value of 100%. 1 The method of claim 10, wherein the method is dependent on

12. The requested distribution ratio is: - the first current value α 1 but, - higher than the second desired temperature value or the second desired temperature value plus a second safety margin, or if, during the first period of time, the temperature is greater than the second desired temperature value or the second desired temperature value plus the second safety margin; has a maximum value of 100% - otherwise the minimum zero value, 11. The method of claim 10 having the following structure:

13. The second reference temperature is - the temperature of the gas at the outlet (4) of the oil injection element (2), or The method according to any of the preceding claims, wherein the temperature of the oil at the outlet (7) of the oil injection pipe network (6) is

14. 14. A method according to any preceding claim, wherein the requested velocity is determined based on a maximum velocity value within a set of one or more velocity values.

15. The first velocity value in the set, v 1 15. The method of claim 14, wherein x represents the value of the speed of the fan (9) required to achieve the second desired temperature value relative to the second reference temperature.

16. a fourth current value α for said second reference temperature 4 is greater than a preset minimum temperature, and A fifth current value α related to the distribution ratio 5 is higher than a preset minimum distribution ratio, and the fourth current value α 4 is greater than the second desired temperature value; The first velocity value v 1 At least a sixth current value α representative of said operating pressure 6 , and a seventh current value α representative of the temperature of the gas at the inlet (3) 7 , The method of claim 15, wherein the determination is based on

17. the fourth current value α 4 is greater than the second desired temperature value plus a first tolerance value; or In the second period, the fourth current value α 4 is greater than the second desired temperature value plus the first tolerance value; or - the fourth current value α 4 is less than the second desired temperature value minus a second tolerance value; or In the third period, the fourth current value α 4 is less than the second desired temperature value minus the second tolerance value; The first velocity value v 1 At least A fifth current value α related to the distribution ratio 5 , and - the fourth current value α 4 and a second desired temperature value β 2 , The method of claim 16 , further determined based on:

18. The first velocity value v 1 The second ratio β increases according to a second monotonically increasing function. 2 The method of claim 17, wherein the method is dependent on

19. The first velocity value v 1 The fifth current value α 5 19. The method according to claim 17 or 18, wherein the method is dependent on

20. If the device (1) comprises an aftercooler (25) for cooling the compressed gas downstream of the oil-injected element (2), an eighth current value α for the minimum effective temperature in the aftercooler (25); 8 is higher than the value for the required minimum effective temperature, the second speed value v 2 teeth, said first velocity value v 1 , and the eighth current value α 8 and the value of the required minimum effective temperature. 3 , is determined based on otherwise, the second velocity value v 2 20. The method of claim 14, wherein is set to zero.

21. 21. The method of claim 20, wherein the required minimum effective temperature is equal to a second condensation temperature of the gas in the aftercooler (25) plus an offset.

22. The second velocity value v 2 The third ratio β 3 22. The method according to claim 20 or 21, wherein the method is dependent on

23. The third velocity value in the set, v 3 teeth, a ninth current value α for said first reference temperature 9 , and a preset maximum value for said first reference temperature, is determined by The third velocity value v 3 teeth, the ninth current value α 9 is equal to zero if is lower than a preset maximum value, and the ninth current value α 9 23. The method according to any of claims 14 to 22, wherein if is higher than a preset maximum value, is equal to a value representing a maximum speed of the fan (9).

24. When the oil-injected element (2) is driven by a variable speed motor, the second temperature value T 2 and / or the first velocity value v 1 respectively, a tenth current value α 10 and the eleventh current value α 11 The method of claim 6 and / or 16, further determined based on, respectively:

25. A computer controlled assembly for carrying out a method according to any one of claims 1 to 24, comprising: a first computing and control unit (13) comprising a control unit (15) for controlling a second reference temperature in the device (1) for compressing a gas to a second desired temperature value; a second computing and control unit (22) for controlling a first reference temperature of said device (1) to a first desired temperature value; A computer control assembly comprising:

26. 26. An apparatus for compressing a gas comprising a computer controlled assembly according to claim 25.

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