Method for monitoring the operation of a compressor and supporting apparatus thereof

Abstract

According to an embodiment, there is disclosed a method for monitoring the operation of a compressor, comprising iteratively performing the steps of measuring (107) process quantities indicative of instantaneous operation of the compressor; and estimating (102) the process quantities of the compressor, based on one or more setting parameters (101) of the compressor using a model; comparing (103) the estimated process quantities with the measured process quantities thereby obtaining an instantaneous performance indicator (201); characterised in that the method further comprises the steps of determining a degradation parameter (108), based on a successive series of instantaneous performance indicators; and wherein the estimating (102) is further also done, based on the performance indicator (108); reporting the operation, based on the degradation parameter (108).

Description

METHOD FOR MONITORING THE OPERATION OF A COMPRESSORAND SUPPORTING APPARATUS THEREOFTechnical Field

[0001] The present invention relates to a method for monitoring a compressor and supporting apparatus of such compressor.State of the art

[0002] A compressor is a mechanical machine, designed to provide a gas, such as ambient air, under higher pressure for applications in industrial processes and / or the medical sector. Depending on the required pressure, the desired application, a desired result, and other boundary conditions, there is a choice from a variety of compressor technologies, such as an axial compressor versus a centrifugal compressor, as well as an oil-free versus an oil-lubricated compressor.

[0003] Furthermore, compressors can be equipped with peripheral apparatus, also referred to as supporting apparatus, such as a cooler, an oil separator, a filter or air filter, a dryer, a drive motor, etc.

[0004] In addition, there may also be a cooling and / or lubricating circuit with a coolant and / or lubricant other than oil, such as water. When reference is made to oil as a coolant and / or lubricant, it should be understood that this may also include the use of another type of coolant and / or lubricant, such as water.

[0005] It is also obvious that in most industrial environments and / or the medical sector, high compressor availability is expected without having to compromise on performance. However, like most mechanical machines, some form of degradation will inevitably occur over time due to, among other things, the presence of rotating parts, contamination in the ambient air around the machine, being subject to large temperature differences, the loss of oil and other internal or external influences that may prevent and / or deteriorate the proper operation of the compressor.

[0006] Therefore, there is a need for a method to monitor the operation of a compressor, and, if necessary, the peripheral apparatus that support the compressor if present, in order to be able to alert, or at least inform, an operator, fleet manager and the like, that the proper functioning is jeopardized, or less stringent is no longer optimal.

[0007] It is therefore an object of the present invention to provide a method for monitoring a compressor and supporting apparatus of such compressor.Summary of the Invention

[0008] According to the present invention, the above-identified objective is achieved by providing, according to a first aspect of the invention, a computer-implemented method according to the first claim for monitoring an operation of a compressor and / or an supporting apparatus thereof, the method comprising iteratively performing the steps of measuring one or more process quantities indicative of instantaneous operation of the apparatus and / or compressor, estimating the one or more process quantities of the apparatus and / or compressor, based on one or multiple setting parameters of the compressor using a model, and comparing the estimated process quantities with the measured process quantities, thereby obtaining an instantaneous performance indicator, characterised in that the method further comprises the steps of determining a degradation parameter, based on a successive series of instantaneous performance indicators, and wherein the estimating is further also done, based on the degradation parameter, and then the step of reporting the operation, based on the degradation parameter.

[0009] The step of measuring is defined as the quantitative determination of a quantity obtained from one or more observations, recordings or sampling at a specific measuring location by means of suitable measuring instruments therefor, such as sensors for expressing an observed quantity as a number with a relevant unit that can be compared with other values of the same quantity.

[0010] The step of estimating is defined as determining a value of a quantity, based on measured process quantities and / or setting parameters, using a scientific model representative for a technical process and / or apparatus with, as input, the measured process quantities and / or setting parameters, and, as output, the value that needs to be determined and therefore is estimated, based on one or more calculations.

[0011] In a first step, process quantities are measured that are indicative of the instantaneous operation of the compressor and / or the apparatus. These process quantities are a temperature of the gas, an electric current of the compressor drive motor, a rotational speed of the rotating parts of the compressor, an inlet pressure of the compressor, an outlet pressure of the compressor, an ambient pressure around the compressor, a humidity level of the gas, a flow rate of the gas, and / or a valve position. It should further be noted that this list is not exhaustive and is therefore not limited to the quantities mentioned. On the other hand, it should also be noted that not all process quantities are measured, but some of them.

[0012] In a second step, one or more process quantities of the apparatus and / or the compressor are estimated. This estimation is made, based on one or more setting parameters of the compressor that serve as input to a scientific model of the compressor, optionally in combination with the apparatus, wherein the output of the model are the estimated process quantities. According to an embodiment, the estimation can also be done, based on measured process quantities, in other words that other process quantities can be derived, based on measured process quantities. Note that estimating the process quantities is therefore a calculation, as already mentioned.

[0013] The model used is initially the model of a compressor and / or supporting apparatus without defects, in other words, a model of an ideal machine, being a compressor and / or supporting apparatus.

[0014] Later in the text, reference will be made to a machine, a compressor, and / or an apparatus, but further note that these terms are interchangeable for purposes of discussing the invention. When referring to the term machine, it can refer to either a compressor, a supporting apparatus, or a combination of both.

[0015] The model representative for the machine is a scientific model such as a physical or multi-physical model comprising a set of differential equations and / or empirical relations describing the different physical parts of the machine and dependent on each other by means of one or more common variables.

[0016] It should be further noted that the first and second steps can be performed in parallel and simultaneously. The term 'first' and 'second' used therefore serves to distinguish between the different steps, but does not indicate a specific chronology and / or hierarchy between the two steps.

[0017] Subsequently, the measured process quantities are compared with the estimated process quantities. Because a model of an ideal machine is initially used to estimate the process quantities, i.e. a machine without any defects, a difference, also called a delta, between the measured and estimated process quantities will in principle indicate deviating behaviour between an ideal or healthy machine and the actual machine. The greater this difference is, the greater is the deviating behaviour of the machine compared to a healthy machine.

[0018] The difference between the measured process quantities and the estimated process quantities is further referred to as a performance indicator, as it is, in principle, an indication of the performance of the machine compared to an ideal machine. A calculated performance indicator at a specific point in time is then an instantaneous performance indicator at this specific point in time.

[0019] The steps of estimating the process quantities and measuring the process quantities are done iteratively, in other words, the steps are performed repeatedly, resulting in a series of successive instantaneous performance indicators.

[0020] According to a new and innovative concept of the invention, the computer-implemented method further comprises the steps of determining a degradation parameter, based on a successive series of instantaneous performance indicators and the estimating is further also done, based on this degradation parameter.

[0021] The calculated successive series of instantaneous performance indicators over a series of successive points in time is again an indication of a deviating behaviour of the machine compared to, in principle, a healthy machine, but in this case not instantaneously but over a certain time period. This time period then encompasses the successive points in time. For example, if this series of instantaneous performance indicators shows a linear downward trend, depending on how it is defined, this indicates a gradual downward trend in deviant behaviour. An instantaneous performance indicator is then defined as a difference between an estimated value on the one hand and a measured value on the other. As a result, the performance indicators will decrease as degradation increases. This gradually decreasing deviant behaviour then further points to decay, aging or degradation of the machine. Based on this successive series of instantaneous performance indicators, the degradation parameter defined above is determined or derived.

[0022] In other words, to determine the degradation parameter, a certain amount of data over a predefined limited time period is analysed, within which the degradation parameter is assumed to be constant. This batch of data is composed of a sequential series of instantaneous performance indicators, further reducing the effect of potential noise on this data. Over a longer time period, both the performance indicators and the degradation parameter will show a decreasing or increasing trend, depending on their definition.

[0023] Note that aging, decay or degradation of a mechanical machine, although undesirable, is unavoidable even under ideal conditions and will occur from the moment it is put into service and will continue to occur during operation. This degradation is caused by friction of moving parts, by corrosion of materials, by deformation, such as fatigue or creep of materials, by metal fatigue or permanent deformation, by external factors such as contamination and the presence of dust particles, seasonal temperature differences, by oil loss, and / or other factors as known by the skilled person.

[0024] In such a situation, the series of instantaneous performance indicators will, depending on how defined, gradually decrease. On the other hand, it is also possible that this series has a sudden or abrupt course, such that larger differences can benoted across the series. This may indicate a defect or malfunction that deviates from normal degradation of the machine.

[0025] Subsequently, the estimating of the process quantities will also be done, based on the determined degradation parameter. Finally, the operation of the compressor and / or supporting apparatus can then be reported, based on the degradation parameter.

[0026] The advantage of this method for monitoring the operation of a compressor and / or supported machine is that, in this way, an unwanted but natural or expected degradation of the machine in normal operation is taken into account. This provides a more correct and accurate picture of the actual operation of the machine.

[0027] On the other hand, as already mentioned, a sudden change will in turn indicate an acute defect or malfunction of the machine. Also, in this situation, a machine operator will obtain a better picture of the operation of the compressor and / or supporting apparatus.

[0028] According to an embodiment, the method further comprises the step of updating the model, based on the degradation parameter.

[0029] The model that is initially representative for an ideal machine will further comprise a parameter such that the model becomes representative for a machine that has already been in operation. This results in a model that is more representative for the actual machine. A consequence of this is that the estimated values of the process quantities are closer to the actual values.

[0030] According to an embodiment, the model may also contain a parametric model comprising one or more model parameters, such as a heat transfer coefficient, an efficiency parameter, a temperature correction parameter, a cooling parameter, a speed correction parameter, a friction parameter, or any other parameter suitable to model the machine.

[0031] A parametric model comprises a set of model parameters that are directly or indirectly linked to each other via a set of variables. The input for the parametric model is then the setting parameters of the machine that correspond to the variables of the model and a selection of the measured process quantities, after which the process quantities can be estimated, based on the model parameters. Furthermore, some of the measured process quantities can be used to validate the output of the model. The step of updating the model is then done by updating the model parameters.

[0032] According to an embodiment, the computer-implemented method for monitoring an operation of a compressor and / or supporting apparatus further comprises the step of deriving a health indicator, based on the model parameters.

[0033] The parametric model, which comprises the model parameters, describes the operation of the machine. Because the model parameters are updated iteratively while monitoring the operation of the machine according to the described method to bring the estimated values into agreement with the observations, based on the measurements, these model parameters are therefore also representative for its operation. The health indicator then expresses the set of model parameters in at least a single value, whereby this health indicator is representative for the operation of the compressor and / or supporting apparatus. In other words, at least one value, the health indicator, expresses the condition or operation of the compressor and / or supporting apparatus. Alternatively, multiple health indicators can be derived, based on multiple partial selections of the model parameters. Furthermore, note that this health indicator already takes into account possible degradation of the machine. Therefore, this health indicator is a correct representation of the condition of the actual machine and therefore not of an ideal machine. Moreover, these steps will further limit the possible effect of noise on the measurements as mentioned above.

[0034] In an optional step, the health indicator can also be reported.

[0035] According to an embodiment of the invention, the method further comprises the step of limiting a range of setting parameters of the compressor, based on the degradation parameter.

[0036] If it can be deduced from the degradation parameter that the machine is working suboptimally or that there is a risk that the machine is going to work suboptimally, this can already be anticipated by limiting the range of the setting parameters. This prevents the risk of a sudden failure, as well as prevents any further damage to the machine if it continues to operate, based on setting parameters that could have a negative influence on its further operation. These setting parameters comprise a pressure, a flow rate, optionally a humidity level, and / or a power, or other possible setting parameters of a compressor.

[0037] Another advantage is that the availability of the machine can be optimized. Although the machine will then run suboptimally, it will be possible to ensure that it indeed remains in operation. This can then be further anticipated by scheduling maintenance in a timely manner. In addition, the operation of a compressor room controller for controlling a group of compressors can also be optimized.

[0038] Furthermore, the method may also comprise the step of switching off the compressor when the degradation parameter exceeds a predefined value. Note that this is a limit case on limiting the range of the setting parameters, which then limits the range to a limit value, being the value at which operation is completely prevented. This step will be performed, for example, if the value of the degradation parameter indicates an acute danger, or when urgent maintenance needs to be carried out.

[0039] According to a second aspect of the invention, there is disclosed a data processing system comprising a processing unit configured to perform the method according to the first aspect of the invention.

[0040] According to a third aspect of the invention, there is disclosed a computer program product containing computer-executable instructions to perform the method of the first aspect when this program is executed on a computer.

[0041] According to a fourth aspect of the invention, there is disclosed a computer readable storage means containing the computer program product of the third aspect.

[0042] According to a fifth aspect of the invention, there is disclosed a compressor comprising the data processing system according to the second aspect of the invention.

[0043] According to a sixth aspect of the invention, there is disclosed a method for monitoring an operation of a compressor and / or an supporting apparatus thereof, the method comprising iteratively performing the steps of measuring one or more process quantities indicative of an instantaneous operation of the apparatus and / or compressor; and estimating one or more process quantities of the apparatus and / or compressor, based on one or more setting parameters of the compressor using a model; comparing the estimated process quantities with the measured process quantities, thereby obtaining an instantaneous performance indicator; characterised in that the method further comprises the steps of determining a degradation parameter, based on a successive series of instantaneous performance indicators; and wherein the estimating is further also done, based on the degradation parameter; reporting the operation, based on the degradation parameter.

[0044] Furthermore, one or more process quantities can be estimated, based on measured process quantities.

[0045] Furthermore, the method comprises the step of updating the model, based on the degradation parameter.

[0046] The process quantities comprise one or more of the group of temperature, flow, speed, inlet pressure, outlet pressure, ambient pressure, humidity, flow rate, and / or valve position.

[0047] The model may comprise a parametric model comprising one or more model parameters. The updating can then be done by updating the model parameters. Furthermore, the method may comprise the step of deriving a health indicator, based on the model parameters. The model parameters can then comprise one or more of the group of a heat transfer coefficient, an efficiency parameter, a temperature correction parameter, a cooling parameter, a speed correction parameter, a friction parameter.

[0048] Furthermore, the method may comprise the step of limiting a range of setting parameters of the compressor, based on the degradation parameter. The setting parameters can then comprise one or more of the group of a pressure, a flow rate, a humidity level, a power.

[0049] Furthermore, the method may comprise the step of switching off the compressor when the degradation parameter exceeds a predefined value.Brief description of the drawings

[0050] The invention will be further illustrated with reference to the figures, wherein

[0051] Fig. 1 schematically illustrates a method for calculating instantaneous performance indicators of a compressor and / or supporting apparatus;

[0052] Fig. 2 schematically illustrates a method for monitoring an operation of a compressor and / or supporting apparatus according to an embodiment of the invention;

[0053] Fig. 3 illustrates a physical model, representative for the operation of a compressor and supporting apparatus;

[0054] Fig. 4 illustrates another model, representative for the operation of a compressor and supporting apparatus;

[0055] Fig. 5 illustrates a closed cooling circuit comprising oil together with a schematic representation of the heating of this oil;

[0056] Fig. 6A-C illustrate a result of a regression exercise for determining parameters and / or coefficients in the model as illustrated in Fig. 3;

[0057] Fig. 7A-B illustrate a result of adjusting a contamination parameter in the model as illustrated in Fig. 3 to match estimates thereof with measurements wherein the cooling circuit has a degree of contamination of 75%;

[0058] Fig. 8A-B illustrate a result of adjusting a contamination parameter in the model as illustrated in Fig. 3 to match estimates thereof with measurements wherein the cooling circuit has a degree of contamination of 92%;

[0059] Fig. 9A-B illustrate a result of adjusting a contamination parameter in the model as illustrated in Fig. 3 to match estimates thereof with measurements wherein the cooling circuit has a degree of contamination of 94.8%;

[0060] Fig. 10 illustrates a contamination parameter as adjusted in the illustrations of Fig. 7-9 as a function of the degree of contamination; and

[0061] Fig. 11 illustrates a determination of health areas, based on the contamination parameter as a function of the degree of contamination.Detailed description of the embodiments

[0062] The present invention will be described with respect to certain embodiments and with reference to certain drawings, but the invention is not limited thereto and is determined only by the claims. The drawings described are only schematic and nonlimiting. In the drawings, the size of certain elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and relative dimensions do not necessarily correspond to actual practical embodiments of the invention.

[0063] Furthermore, the terms first, second, third and the like are used in the description and in the claims to distinguish between similar elements and not necessarily to describe a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention may be practiced in sequences other than those described or illustrated herein.

[0064] In addition, the terms top, bottom, over, below and the like in the description and claims are used for illustrative purposes and not necessarily to describe relative positions. The terms so used are interchangeable under appropriate circumstances and the embodiments of the invention described herein may be employed in orientations other than those described or illustrated herein.

[0065] Furthermore, the various embodiments, although referred to as "preferred embodiments", are to be construed as exemplary means of carrying out the invention rather than as a limitation of the scope of the invention.

[0066] The term “comprising”, used in the claims, should not be construed as being limited to the means or steps set forth below; the term does not exclude other elements or steps. The term should be interpreted as specifying the presence of the mentioned features, elements, steps or components referred to, but does not exclude the presence or addition of one or more other features, elements, steps or components, or groups thereof. The scope of the expression “a device comprising means A and B” should therefore not be limited to devices consisting only of components A and B. The meaning is that, with respect to the present invention, only components A and B of the device are listed, and the claim is further to be construed to also include equivalents of these components.

[0067] Fig. 1 schematically illustrates a method for calculating instantaneous performance indicators of a compressor and / or supporting apparatus. The first step comprises measured data 101 as input for a model 102, representative for the compressor and / or supporting apparatus. For example, the model 102 is a physical model as further illustrated in Fig. 3. The input comprises a speed nnitand a pressure pnit300, an inlet temperature T^ir-in302, and a heat transfer coefficient UA 108. In 303 the power Pcompr can then be calculated, based on the speed and pressure 300. Based thereon, the heat produced when the compressor is active, can then be calculated as Q he at generated 305, as illustrated in Fig. 3, for example by taking an efficiency factor into account. The required compressor power can be determined from a compression model 308 using Tout309 the air outlet temperature, Tinthe air inlet temperature, poutthe air outlet pressure and pinthe air inlet pressure.

[0068] It is further understood that the above illustrated example of the physical model 102 may be replaced by other models, representative for the compressor and / or supporting apparatus. With reference to Fig. 4 which illustrates another model 400, a set of inputs 401-405, for example a speed 401 , a pressure 402, an inlet temperature 403,a ventilation condition 404, and an oil temperature at a certain point in time 405, is provided, such that, with a set of equations 406, an oil temperature at a subsequent point in time 407 can be calculated.

[0069] Again with reference to Fig. 3 and thus to the physical model 102, reference 304 comprises a model for determining the cooling capacity Pcooier ofacooling circuit of a cooler, present in an arrangement comprising the compressor. With reference to Fig. 5, the cooling circuit 500 is, for example, a closed oil circuit. Oil circulates by means of a pump 501 to one or more machine parts 502 where heat is removed to the oil. The oil is then cooled again in an oil cooler 504, for example by means of a ventilator 505. The oil can then be used further as lubrication 506 of machine parts, such as a gearbox, and recirculated through the pump 501 in the cooling circuit 500.

[0070] The correct functioning of the oil circuit 500 can be negatively influenced in various ways. For example, oil can become contaminated due to wear of moving parts in the oil circuit 500, which can clog the conduits and hinder the lubrication and cooling of bearings and gears. At the beginning, the oil will be very pure, but when very fine particles in the sucked cooling air from the environment are no longer retained by a filter, the oil can become contaminated. This phenomenon can occur with an oil-injected compressor. A non-oil-injected compressor has a closed oil circuit, which means that the oil does not flow along the compressor elements, and thus, this phenomenon is less likely to occur. However, just like with oil-injected compressors, the air side of the oil cooler 504 will also become clogged with dirt particles in the air. This phenomenon is also called clogging 503, and the oil cooler 504 will function over time suboptimally. This is because heat transfer is made more difficult, causing the overall temperature of the oil to increase. This in turn results in the temperature of the compressed air increasing because, for example, the housing also reaches a higher temperature. In addition, the lubrication conditions of the bearings and gears will be subop- timal, such that these parts heat up further, age in an accelerated way, and jeopardize the availability of the compressor.

[0071] The closed circuit can be modelled as a system wherein parameters are only time dependent, also called a lumped system, wherein the heating 509 of the oildepends on the heat absorbed 507 as a result of losses, and on the heat released 508 by the cooler, and therefore the cooling capacity.

[0072] The cooling capacity is then the heat Qheatremoved removed during operation and is proportional to the difference between an oil temperature ToUand a cooling air temperature Tair iniet, wherein the proportionality factor is equal to the heat transfer coefficient UA 108 of the cooler. Furthermore, an extra fanstate factor is added that takes into account whether or not forced ventilation is active. The cooling air temperature itself can be modelled as a correction on top of the temperature in the compressor enclosure. The cooling capacity Pcooier corresponding to the removed heat then becomes Pcoo ierfans tat6 , UA, Ton, Ta^rinlet> ••• ) Qheat removed 307.

[0073] The heating of the oil in the oil circuit can be described as Qheatgenerated ~ Qheat removed, represented by reference 306. Based on the above, with an operator 308, optionally supplemented with a gain factor, the oil temperature at a certain point in time as output 309 of the model can be calculated.

[0074] Again with reference to Fig. 1 , the difference between the estimated values 309 and measured values 107 can then be calculated in 103. Reference 104 then comprises a series of residues.

[0075] In principle, the aforementioned gain factors, representative for respective parameters, and / or coefficients, describing the operation of the compressor and the cooling circuit, can be determined, based on a sufficient number of measurements on a new and / or healthy machine. These can then be determined, for example, via least squares regression. Fig. 6A-C illustrate a result of such a regression exercise. The y- axes of the illustrated graphs show, as a function of time, the oil temperature expressed in degrees Celsius °C, the compressor speed expressed in revolutions per minute rpm, and the inlet temperature expressed in degrees Celsius °C, respectively. It should be further noted that Fig. 6B, 7B, 8B, and 9B has two y-axes, with the right y-axis representing the outlet pressure expressed in bar.

[0076] As long as the oil circuit can be assumed to be healthy, the above model can be used to determine the efficiency of the cooling system and / or compressor. Measurements and estimates via the calculations will then be in accordance with each other. However, when the cooler begins to clog up, the heat transfer coefficient UA of the cooler will decrease. This degradation can be included in the model by introducing an additional factor f>a, further referred to as a contamination parameter, which is an example of the degradation parameter defined above, wherein the value ranges between 1 , corresponding to a healthy machine, and 0, wherein there is no heat transfer at all. Then, the capacity of the cooler is Pcooler= Qheat removed=

[0077] The model used 102 therefore comprises the contamination parameter f>vwhich is representative for the health status, or in other words, the degradation status, of the machine or a part of it such as the cooling circuit. Furthermore, in the example of model 102, it is possible to use a gain factor anwhich is representative for a friction factor for the compressor and / or peripherals as an indication of the health status. When the compressor and / or peripherals are put into service, this will be equal to an expected friction factor of a new machine, but over time a significant discrepancy will arise between the measurements and the estimates because this friction factor no longer corresponds to that of a new machine.

[0078] With reference to Fig. 2, the degradation of the compressor and / or peripheral apparatus and associated cooling circuit will be taken into account according to a new and innovative 200 method. Fig. 2, as in Fig. 1 , shows measured data 101 as input, the model 102 representative for the compressor and / or supporting apparatus, a calculation of the difference 103 between measured values 107 and estimated values 309, and a series of residuals 104. However, unlike the method as illustrated in Fig. 1 , the residuals 104 are minimized in step 201 by updating one or more parameters of the model 102 by the feedback 202, such as the contamination parameter fy and gain factor an.

[0079] It is also possible to adjust optionally other parameters such as those used in other aspects of the model, such as, a.o. the efficiency of the compressor, the oilspeed, the friction factor, etc. In other words, by adjusting parameters and / or variables in the model 102, the estimates will be brought into agreement with the measurements and thus the residuals 104 will be reduced to a minimum, i.e. to the level of noise.

[0080] For example, if, in a simple case, only the friction factor is changed via the feedback 202, it may show a monotonically increasing trend in the event of natural or expected degradation of the cooling circuit 500. On the other hand, depending on the reference and definition of this factor in the model, also a monotonous decreasing trend may be noted. It should therefore be understood that there is a change over time in one or more parameters due to the feedback 202.

[0081] With reference to Fig. 7A, an illustration of the oil temperature on the y-axis over time on the x-axis is given, wherein the solid line represents measurements 107 and the dashed line represents estimates, based on the model 102. Thereby, the difference is calculated between these as error [%], which corresponds to the residuals 104. By the feedback 202, the above-mentioned parameters are adjusted to bring the estimates in agreement with the measurements. Furthermore, in Fig. 7B are shown the measurements of velocity on the left y-axis and exhaust pressure on the right y-axis over time on the x-axis, measured at the same points in time as the oil temperature measurements.

[0082] To bring the estimates in agreement with the measurements, the parameters are therefore adjusted, which results in a higher degree of contamination or blockage being imposed on the cooler in the model. This provides insight into the degree of contamination of the cooler. Again with reference to Fig. 2, the degree of contamination 205 of the cooler can then be derived, based on the feedback 202 via an additional model 204, for example a regression model. Block 201 is here a minimizer that proposes new values of parameter 108 that lead to a next iteration via feedback 202. After convergence is achieved, the result is an updated version of the converged value of the degradation parameter 203, and 108 is then the suggested values of the degradation parameter.

[0083] In Fig. 7, this degree of contamination corresponds to 75%. In Fig. 8A-B and Fig. 9A-B further illustrations are given as in Figs. 7A-B, wherein in Fig. 8 the coolerhas a degree of contamination of 92% and Fig. 9 the cooler has a degree of contamination of 94.8%.

[0084] Furthermore, in Fig. 10 is shown that the contamination parameter pUtshown here as a normalized value, pctoghas a decreasing trend depending on the degree of contamination of the cooler. Based thereon, it is possible to determine health areas as to what extent this parameter represents the health of the cooling circuit and therefore the compressor. As illustrated in Fig. 11 , for example, three areas are shown, being a completely clogged cooler, Fully clogged, a partially clogged cooler, Partially clogged, and a healthy cooler, Healthy.

[0085] By determining the degree of contamination, maintenance can be planned more efficiently. As soon as the degree of contamination exceeds a limit value, as illustrated for example in Fig. 10, this maintenance can be scheduled to ensure machine availability and efficiency. Maintenance can therefore be planned when necessary, rather than purely periodically and therefore as a precaution. Finally, it is also possible to better estimate the risk of failure of the oil cooler, and therefore also of the compressor, and, if necessary, to notify an operator in time such that there is no confrontation with an unexpected failure.

Claims

CLAIMS1.- A computer-implemented method for monitoring the operation of a compressor and / or a supporting apparatus thereof, the method comprising iteratively performing the steps of:- measuring (107) one or more process quantities (101) indicative of instantaneous operation of the apparatus and / or compressor; and- estimating (102) the one or more process quantities of the apparatus and / or compressor, based on one or more setting parameters of the compressor using a model (102, 400);- comparing (103) the estimated process quantities with the measured process quantities, thereby obtaining an instantaneous performance indicator (104);CHARACTERISED IN THAT the method further comprises the steps of:- determining (202) a degradation parameter (203), based on a successive series of instantaneous performance indicators (104); and wherein the estimating (102) is further also done, based on the degradation parameter (108);- reporting the operation, based on the degradation parameter (108).2.- The computer-implemented method according to claim 1 , wherein the estimating of the one or more process quantities is further done, based on measured process quantities (107).3.- The computer-implemented method according to any one of the preceding claims, further comprising the step of updating (202) the model, based on the degradation parameter (108).

4. The computer-implemented method according to any one of the preceding claims, wherein the process quantities (101) comprising one or more of the group of atemperature, flow, speed, inlet pressure, outlet pressure, ambient pressure, humidity, flow rate, and / or valve position.

5. The computer-implemented method according to any one of the preceding claims, wherein the model (102, 400) comprises a parametric model comprising one or more model parameters.6.- The computer-implemented method according to claim 5 when dependent on claim 3 or 4, wherein the updating (202) is done by updating the model parameters (305, 306, 307).7.- The computer-implemented method according to any one of claims 5 to 6, further comprising the step of:- deriving a health indicator (205), based on the model parameters (305, 306, 307).8.- The computer-implemented method according to any one of claims 5 to 7, the model parameters comprising one or more of the group of a heat transfer coefficient, an efficiency parameter, a temperature correction parameter, a cooling parameter, a speed correction parameter, a friction parameter.9.- The computer-implemented method according to any one of the preceding claims, further comprising the step of: limiting a range of compressor setting parameters, based on the degradation parameter (108).10.- The computer-implemented method according to claim 9, the setting parameters comprising one or more of the group of a pressure, a flow rate, a humidity level, a power.11.- The computer-implemented method according to any one of the preceding claims, further comprising the step of:- switching off the compressor when the degradation parameter (108) exceeds a predefined value.

12. - A data processing system comprising a processing unit configured to perform the method according to any one of the preceding claims.

13. - A computer program product containing computer-executable instructions to perform the method according to any one of claims 1 to 11 when this program is executed on a computer.

14. - A computer readable storage medium containing the computer program product according to claim 13.

15. - A compressor comprising the data processing system according to claim 12.

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