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Title:
AIR FILTER ARRANGEMENT, DEVICE AND SYSTEM
Document Type and Number:
WIPO Patent Application WO/2017/146633
Kind Code:
A1
Abstract:
The present invention relates to an air filter arrangement (20) configured to fitin an air flow passage. The air filter arrangement comprises an air filter framework (21), at least one filter medium (22) capable of removing particulate material and/or airborne molecular contamination, AMC, from an air flow received at the air flow passage, and an air filter sensor device(24)that is provided in the air filter framework (21) and configured to determine an operating state of the air filter arrangement. The air filter sensor device (24) includes air flow determining means for determining an air velocity of the air flow at the air filter arrangement (20), wherein the air flow determining means comprises measuring means configured to determine dynamic pressure or a pressure pulse attributable to a vortex pattern induced in the air flow, and in that the air filter framework comprises a structural element (23) configured to induce said vortex pattern. The invention also relates to air filter sensor device and a system for air filter management comprising the air filter sensor device.

Inventors:
JOHANSSON, Ulf (Mejselvägen 43, Hägersten, 126 38, SE)
HEDLUND, Kenny (Verktygsgatan 6C, Trosa, 619 33, SE)
Application Number:
SE2017/050162
Publication Date:
August 31, 2017
Filing Date:
February 20, 2017
Export Citation:
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Assignee:
CAMFIL AB (Sveavägen 56 E, Stockholm, 111 34, SE)
International Classes:
F24F3/16; F24F11/00
Foreign References:
US20050108996A12005-05-26
US5461368A1995-10-24
US20120145010A12012-06-14
SE537506C22015-05-26
Attorney, Agent or Firm:
ZACCO SWEDEN AB (P.O. Box 5581, Valhallavägen 117N, Stockholm, 114 85, SE)
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Claims:
CLAIMS

1. An air filter arrangement (20) configured to fit in an air flow passage, the air filter arrangement (20) comprising an air filter framework (21), at least one filter medium (22) capable of removing particulate material and/or airborne molecular contamination, AMC, from an air flow received at the air flow passage, and an air filter sensor device (24) that is provided in the air filter framework (21) and configured to determine an operating state of the air filter arrangement (20), characterised in that the air filter sensor device (24) includes air flow determining means for determining an air velocity of the air flow at the air filter arrangement (20), wherein the air flow determining means comprises measuring means configured to determine dynamic pressure or a pressure pulse attributable to a vortex pattern induced in the air flow, and in that the air filter framework comprises a structural element (23) configured to induce said vortex pattern.

2. The air filter arrangement (20) of claim 1, wherein the air filter sensor device (24) is attached to said structural element (23).

3. The air filter arrangement (20) of claim 1, wherein the air filter sensor device is integrated in said structural element (23). 4. The air filter arrangement (20) of any of the preceding claims, wherein the air filter arrangement (20) further includes one or more further sensors arranged to gather sensor data representative of an operating state of the air filter arrangement, said further sensors configured to measure at least one of pressure drop, temperature, humidity, particle concentration and gas concentration.

5. The air filter arrangement (20) of claim 4, wherein the air filter sensor device (24) comprises said one or more further sensors.

6. The air filter arrangement (20) of any of the preceding claims, wherein the air filter arrangement is configured to fit in an air flow passage to/from an industrial installation, a building or a clean process environment.

7. An air filter sensor device (24) arranged to be provided in an air filter arrangement (20) comprising an air filter framework and at least one filter medium, wherein the air filter sensor device (24) is configured to be provided in the air filter framework (21), characterised in that the air filter sensor device includes air flow determining means for determining an air velocity of an air flow at the air filter arrangement (20), wherein the air flow determining means comprises measuring means configured to determine dynamic pressure or a pressure pulse attributable to a vortex pattern induced in the air flow at the air filter arrangement (20) by a structural element of the air filter framework.

8. The air filter sensor device of claim 7, wherein the air filter sensor device further includes one or more further sensors arranged to gather sensor data representative of an operating state of the air filter arrangement, said further sensors configured to measure at least one of pressure drop, temperature, humidity, particle concentration and/or gas concentration.

9. The air filter sensor device of any of claims 7 or 8, wherein the air filter sensor device further comprises a microprocessor arranged to determine operating state information based on gathered sensor data and the determined air velocity of the air flow in the air passage, and a communication unit arranged to transmit operating state information to a receiving air filter control system.

10. A system for air filter management comprising one or more air filter sensor devices (41a, b) according to any of claims 7-9, and an air filter control station (42) , characterized in that the air filter control station (42) is provided at a location remote from the one or more air filter sensor devices (41a,b) and in that each air filter sensor device (41a, b) comprises a communication unit for transmission of sensor data to the air filter control station.

Description:
Air filter arrangement, device and system

TECHNICAL FIELD

The present disclosure relates to an air filter arrangement configured to fit in an air flow passage and an air filter sensor device arranged to be provided in such an air filter arrangement. The disclosure also relates to a method performed in an air filter sensor device and a system for air filter management comprising such an air filter sensor device.

BACKGROUND ART

Controlled supply of clean air is essential in a variety of applications such as building ventilation systems, and air supply to clean processes or industrial installations. It is desirable to filter the inlet air for the purposes of removing various particles and/or gaseous matter and the like which may be entrained in the air, and thereby provide conditioned inlet air according to specified quality requirements. For this purpose, filter arrangements are provided at the air flow inlet to an application. The filters are arranged so that inlet air generally passes through a series of filters to remove contaminant matter from the air. As can be appreciated, filters in such arrangements gradually accumulate matter from the air and as this matter accumulates on the filter the resistance to flow of air through the filter increases. Filter arrangements are clogged up by particles trapped in the air filters but also by environmental conditions such as fog, rain, snow, and the like. The clogging may reduce filtration and operating efficiency while increasing the overall pressure drop. An increase of the pressure drop over the filter arrangement implies an inlet air pressure loss that may affect operations at a receiving end, e.g., the operation of an industrial installation.

A filter has a technical lifespan during which it functions adequately. The lifespan depends on different factors such as particle concentration in the air, the flow of air etc. The technical lifespan may be determined from measurements performed on the filter air flow and pressure drop. However, from an economical perspective, it may be advisable to make a filter replacement prior to the point when the filter is at the end of its technical lifespan. A number of techniques to estimate an optimal filter use time are available using combinations of data in the assessment of the use time. Access to reliable sensor data is a key to determine optimal filter use time. However, installation of sensors is usually time-consuming and there are also drawbacks in the accuracy provided from known sensor installations, especially for the assessment of air flow/air velocity in an air flow passage where air speed is slow and requiring highly sensitive sensors. This is also true for air handling units that are decentralized or rebuilt, where it may prove difficult to implement measurement systems in an easy and cost effective way with the drawback that important measurement data, such as air flow, may be ignored when assessing operating state of a filter.

Techniques for determining life cycle cost for an air handling unit are readily available, such as through SE537506 describing a method of determining an optimal time for operating a filter in a ventilation system in order to save costs and leave as little carbon dioxide footprint as possible. However, while there are methods and systems for determining life cycle cost, the sensor data used in these systems are usually inadequate especially when considering air flow.

Since air flow is an important factor for determining the technical lifetime and energy consumption of a filter, and depends on highly local environmental conditions, there is a need for improved accuracy with regard to air flow data. Furthermore, there is a need to provide for easier replacement of sensor devices, prior to the sensor device producing unreliable results due to such wear, aggregation of particulate material in the sensor or other factors that may impair the accuracy of the sensor.

Thus, there is a need for improvements relating to gathering of sensor data, and in particular for gathering accurate air flow data that may be used for estimating a filter operating state, e.g. in an air filter management system.

SUMMARY

It is an object of the present invention to improve gathering of sensor data for an air filter arrangement configured to fit in an air flow passage. In particular, it is an object of the present invention to improve gathering of air flow data at an air filter arrangement.

This object is achieved by an air filter arrangement configured to fit in an air flow passage. The air filter arrangement comprises an air filter framework, at least one filter medium capable of removing particulate material and/or airborne molecular contamination, AMC, from an air flow received at the air flow passage, and an air filter sensor device that is provided in the air filter framework and configured to determine an operating state of the air filter arrangement. The air filter sensor device includes air flow determining means for determining an air velocity of the air flow at the air filter arrangement, wherein the air flow determining means comprises measuring means configured to determine dynamic pressure or a pressure pulse attributable to a vortex pattern induced in the air flow, and in that the air filter framework comprises a structural element configured to induce said vortex pattern.

The present invention provides the specific advantages of providing the air filter arrangement with an air filter sensor device so that the sensor data retrieved with the sensor specifically relates to the air flow through the air filter arrangement and the face velocity of this air flow. The providing of an air filter sensor device in the air filter arrangement, e.g. in a location downstream of a filter medium, has the positive implication that the air filter arrangement serves as a conditioner of the air flow, thereby improving accuracy for the air flow determination. Mounting of the air filter sensor device in the air filter frame work also contributes to simplified and more cost effective implementation of local measurement points in an air filter management system.

Furthermore, the determining of air velocity from a pressure pulse attributable to a vortex pattern induced in the air flow, e.g. by a structural element of the air filter framework, provides the advantage of a measurement relevant for the air flow at the air filter arrangement, as compared to prior art measurements derived in the outer surroundings of an air filter arrangement. The filter arrangement serves as a conditioner of the air flow. Furthermore, using a structural element of the air filter frame work to generate the vortex pattern provide the benefit of truly determining air flow sensor data relevant for determining the operating state of the air filter arrangement. According to an aspect of the disclosure, the air flow determining means comprise known means for determining an air velocity for an air flow, such as a thermal anemometer, turbine anemometer, ultrasonic anemometer. According to another aspect of the disclosure, the air filter sensor device is attached to the structural element. Thus, the air filter sensor device may be configured as a separate entity that is attachable to previously installed air filter arrangements thereby enabling air filter management also for air filter systems that were not originally configured in this regard. According to an alternative aspect of the disclosure, particularly advantageous when replacing an air filter arrangement, the air filter sensor device may be integrated in the air filter framework of the air filter arrangement. Integrating the air filter sensor device provides for a very simple and cost effective installation.

According to aspects of the invention, the air filter arrangement further includes one or more further sensors arranged to gather sensor data representative of an operating state of the air filter arrangement, said further sensors configured to measure at least one of pressure drop, temperature, humidity, particle concentration and gas concentration. Preferably, these sensor devices are comprised in the air filter sensor device.

An air filter arrangement comprising a compact air filter sensor device comprising a set of sensors providing sensor data required for air filter management provides significant improvements to monitoring and control of air filter parameters in an air handling unit and a solution to the need of implementing a measurement system that combines cost effectiveness with accuracy.

The present invention also relates to an air filter sensor device arranged to be provided in an air filter arrangement comprising an air filter framework and at least one filter medium, wherein the air filter sensor device is configured to be provided in the air filter framework. Air flow determining means for determining an air velocity of an air flow at the air filter arrangement is included in the air filter sensor device, wherein the air flow determining means comprises measuring means configured to determine dynamic pressure or a pressure pulse attributable to a vortex pattern induced in the air flow at the air filter arrangement by a structural element of the air filter framework.

The present invention further relates to a system for air filter management comprising an air filter control station and one or more of said air filter sensor devices. The air filter control station is provided at a location remote from the one or more air filter sensor devices. Each air filter sensor device comprises a communication unit for wired or wireless transmission of sensor data to the air filter control stations. Thus, a system is provided with a central node in which sensor data is aggregated from a plurality of local nodes. The aggregated data provides the ability to base life expectancy on input from a plurality of air filters in operation, which may significantly improve air filter management for the individual air filter arrangements as well as creating insights to development of next generation products.

The air filter sensor device and the system for air filter management display corresponding advantages as those that have been mentioned for the air filter arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing will be apparent from the following more particular description of the example embodiments, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the example embodiments.

Figure 1 is an example view of an air flow passage to an application;

Figure 2 is an example view of an air filter arrangement containing an air filter sensor device;

Figure 3 is a block diagram for an air filter sensor device Figure 4 is a block diagram for a system for air filter management;

Figure 5 is a flow diagram of exemplary method steps performed in an air filter sensor device;

Figure 6 is a flow diagram of exemplary method steps performed in an air filter management system using an air filter sensor device

DETAILED DESCRIPTION

Aspects of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. The devices and method disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout. The terminology used herein is for the purpose of describing particular aspects of the disclosure only, and is not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Figure 1 illustrates an example view of an air flow passage 1 to an application 2, such as a building ventilation system, an air supply to clean processes or an air supply to an industrial installation. A combustion turbine power plant, a turbine powered compressor station or a turbine powered mechanical drive are examples of such an industrial installation. Laboratory or manufacturing environments for semiconductors, chemicals, biochemical and pharmaceuticals represent examples of areas requiring clean process environments.

Ambient air is supplied to the application through an air intake 3. While being readily available, a problem with an ambient air supply is that the ambient air contains at least some degrees of material that may be contaminating. A supply of ambient air to the application consequently implies a supply of contaminating material. One or more air filter arrangements 4 in the air flow inlet to the application provide means to overcome the problems associated with using ambient, impure air

As disclosed in Figure 1, an air filter arrangement 4 is positioned in the air flow inlet 1 to the application 2. The disclosed air filter arrangement 4 comprises an air filter medium 5. Embodiments comprising a plurality of air filter media or air filter units are of course also within the scope of the present invention, e.g. a plurality of air filter units with varying filter qualities, e.g., a coarse air filter unit of a lower filter class, an intermediary air filter unit and a final filter unit capable of filtering out particles of very small sizes. This means that coarser materials such as e.g. insects or sand particles can be entrapped by a particle filter unit closer to the air intake 3, while small particles such as salt and airborne molecular contamination, AMC, is removed from the air stream in a more downstream filter unit. The air filter medium has an upstream surface directed towards the air intake 3 and a downstream surface directed towards the application 2, by which is meant that the upstream surface is the side of the filter unit that is first reached by the air flow and the downstream surface is on the side where the air stream leaves the filter unit after having passed through a filter medium in the filter unit. Other air filter arrangements 4 are also possible, e.g. air filter arrangements 4 comprising filter units positioned in a V-shape with a peak facing the incoming air flow and air filter arrangement containing any number of filter units. Ambient air is supplied to the application 2 through the air flow inlet 1. The air filter medium provides for filtering with specific characteristics with regard to susceptibility for clogging and changes in pressure drop. When in operation, contaminants in the ambient air are removed in the filtration process. This implies that the contaminants are retained in the air filter arrangement 4, while the cleaned air is allowed to pass into the application 2. An effect of the filtration and the retaining of contaminants in the filter medium 5 is that this will eventually need replacement due to clogging up from said contaminants. Figure 2 is an example view of an air filter arrangement 20, such as that of Figure 1. The air filter arrangement 20 is configured to fit in the air flow inlet to an application, such as an industrial installation, a clean process or a building ventilation system. The air filter arrangement comprises a filter medium as described in relation to Figure 1.

The air filter arrangement 20 comprises an air filter framework 21 and at least one filter medium 22 which is fastened in the air filter framework in a conventional installation. The air filter medium 22 is arranged to remove particulate material and/or airborne molecular contamination, AMC, from an air flow received in an air flow passage wherein the air filter arrangement is fitted. The air filter framework is configured to be tightly joined to an air flow inlet or air flow passage to the application so that the air supply to the application is provided only through the filter arrangement 20. The air filter arrangement 20 also comprises an air filter sensor device 24 that is provided in the air filter framework 21 and is configured to determine an operating state of the air filter arrangement. Said air filter sensor device 24 includes air flow determining means for determining an air velocity of the air flow received at the at least one filter medium. Thus, the air filter arrangement is provided with an air filter sensor device so that the sensor data retrieved with the sensor specifically relates to the air flow through the air filter arrangement 20, the air filter sensor device 24 providing a simplified and more cost effective implementation of local measurement points in an air filter management system including the air filter arrangement. The positioning of the air filter sensor device in the air filter arrangement, e.g., in a downstream or upstream position in relation to the filter medium, has the positive implication that the air filter arrangement serves as a conditioner of the air flow, thereby improving accuracy for the air flow determination.

The air flow determining means of the air filter sensor device 24 preferably comprises measuring means configured to determine a pressure pulse attributable to a vortex pattern induced in the air flow at the air filter arrangement. However, other air flow determining means may also be used in order to determine an air velocity of the air flow in the air filter arrangement. Such other air flow determining means comprise a thermal anemometer, a turbine anemometer, and ultrasonic anemometer or measuring means configure to determine dynamic pressure. In the disclosure of Figure 2, the air filter sensor device 24 is attached to a structural element 23 of the air filter framework, such as a lath at a downstream or upstream receiving side of the air filter arrangement 20. The air filter sensor device 24 may be attached by snapping the air filter sensor device 24 to the structural element 23 by means of two or more resilient arms extending from a body including the flow determining means. According to another aspect of the disclosure, the air filter sensor device 24 is integrated with the air filter framework 21 and arranged at a downstream or upstream receiving side of the air filter arrangement. In the latter case, the exterior of the air filter arrangement does not reveal the existence of the air filter sensor device. It should be understood that the air filter sensor device could be removably attached to the air filter arrangement so that the air filter device 24 is removed when removing the air filter arrangement and then subsequently reinstalled when providing a new air filter arrangement In another embodiment the air filter sensor device will be fixed to the air filter framework and replaced upon replacement of the air filter arrangement.

In accordance to the embodiment of Figure 2, the air filter sensor device 24 is attached to a upstream or downstream side of the air filter arrangement, but it should be appreciated that the air filter sensor may also be attached within the air filter framework. In the disclosure of Figure 2, the structural element is capable of inducing a vortex pattern in an air flow received in the air flow passage where the air filter arrangement is fitted. According to an aspect of the disclosure, the air filter sensor device 24 may also be configured to induce a vortex pattern in the air flow when contained in an air filter arrangement. While not apparent from Figure 2, the air filter arrangement 20 may further include one or more additional sensors that are arranged to gather sensor data representative of an operating state of the air filter arrangement. The further sensors are configured to measure any combination of a pressure drop, temperature, humidity, particle concentration and gas concentration; thereby enabling access to a comprehensive set of parameters for the operating state.

Consequently, with the present invention, the air filter arrangement will serve as a measurement platform and the air filter framework does not only serve to hold the filter medium, but is also a vortex inducing body enabling use of measurements based on Vortex shedding. In addition, the air filter arrangement serves as a conditioner of the air flow creating an air flow pattern prior to the measurement point of the sensor device; thereby contributing to the needed accuracy of the measurement that also benefits from being performable at a lower cost than in previously known solutions. Another benefit of the present air filter sensor device is that there is no pressure loss in the system due to sensors and flow conditioners. Figure 3 discloses a block diagram of an air filter sensor device 30 configured to be contained in an air filter arrangement, such as the air filter arrangement 4 of Figure 1 or the air filter arrangement 20 of Figure 2. The air filter sensor device 30 includes air flow determining means 31a for determining an air velocity of the air flow received at the air flow inlet. According to an aspect of the disclosure, the air flow determining means 31a is a vortex sensor configured to determine a pressure pulse attributable to the vortex pattern. According to another aspect of the disclosure, the air flow determining means is a pitot tube configured to determine an air speed of the air flow received at the air flow inlet. Use of other types of anemometers is of course also within the scope of the present invention, e.g., thermal anemometers, sonic anemometers, turbine anemometers, or any other type of anemometer that may be fitted into a compact air filter sensor device 30.

According to further aspects of the disclosure, the air filter sensor device 30 further includes one or more further sensors 31b,c representative of an operating state of the air filter arrangement, e.g., said further sensors configured to measure at least one of pressure drop, temperature, humidity, particle concentration and gas concentration. Such further sensors 31b,c may also be incorporated into a compact housing. According to aspects of the disclosure, the air filter sensor device 30 also comprises a microprocessor 32 arranged to process sensor data received from said sensors 31a-c, and a communication unit 33 arranged to transmit processed sensor data to a receiving air filter control system. Hence, the air filter device may be configured as a smart device including control circuitry, i.e., a microprocessor, for on-site processing of sensor data. The microprocessor 32 of the air filter sensor device 30 is arranged to receive or obtain data from the set of sensors 31a-c, e.g., on a continuous basis recording values according to predetermined time intervals. According to aspects of the disclosure, the microprocessor 32 is embodied in a printed circuit board with a CPU that collects signals and records the data every 20 minutes. The microprocessor is arranged to perform a Fast Fourier transform on one of the signal outputs resulting in a discrete peak value that may be stored in a memory of the air filter device and/or transferred to the air filter control station. Data storage of approximately 500kB per month is expected for each air filter device, thus, a memory is also foreseen in the air filter sensor device. According to an aspect of the disclosure, the air filter sensor device also comprises a communication unit 33, e.g., user equipment arranged to transmit the collected data on a regular basis, e.g. by using a wireless link in machine to machine communication. The communication unit 33 in the air filter device may be configured to transmit the processed sensor data to a receiving air filter control station. The processed sensor data may also be communicated to a receiving air filter control station capable of processing of sensor data received from a plurality of air filter sensor devices, e.g., a plurality of devices located at the same industrial installation or at varying industrial installations. The communication unit 33 may be any type of wireless communication unit configured for machine to machine communication, e.g. using WiFi, GSM, LTE or any type of suitable wireless technology. According to another aspect of the disclosure, there is also a power supply or power reservoir for each air filter device to power the communication unit, the sensors and the microprocessor. All entities are configured for low power consumption, so that the battery is able to provide power all through the intended use time of the air filter arrangement holding the air filter device 30. Thus, the present invention provides for a "smart" air filter arrangement that significantly will improve the ability to retrieve relevant measurements during air filter management. The air filter sensor devices may not only be used for the purpose of determining a life expectancy of an air filter, but may also function to provide an air handling unit with feedback so that a fan or other air regulation device may be operated based on output from the air filter sensor device, e.g., to control a power increase in a fan in order to increase or maintain an air flow to the receiving application.

Figure 4 discloses an exemplary block diagram of a system 40 for air filter management comprising an air filter control station 42 and one or more air filter sensor devices 41a, b. In the air filter management system 40, each air filter sensor device 41a, b is to be provided in an air filter arrangement configured to fit in an air flow passage to an application, e.g., an industrial installation, a building ventilation system or a clean room air supply system. The air filter control station of the system may be provided at a location remote from the one or more air filter arrangements, e.g., in an operations control environment of the industrial installation or as a software application accessible through a computer, tablet or mobile device. Each air filter sensor device of an air filter arrangement comprises a communication unit for wired or wireless transmission of sensor data to the air filter control station. Hence, a communication link is established between air filter sensor devices and the remote control station.

The air filter sensor devices of the system may be contained in air filter arrangements located at different geographical locations, such as in air filter arrangements located at different combustion turbine power plants. The air filter control station is configured to compile data from a plurality of air filter devices, preferably air filter devices of differing locations and to use the compiled data in order to establish a reliable estimate for a remaining life span and cost of operating the corresponding air filter arrangements. The filter further comprises a set of sensors, a microprocessor and a communication unit. As mentioned above, aspects relating to clogging and pressure drop vary between the filter units of the disclosed filter arrangement. Consequently, the system for air filter management may comprise a set of sensors arranged in a plurality of air filter devices comprising sensors positioned on or in the vicinity of one or more specific filter units or a single air filter device comprising a greater number of sensors positioned on or in the vicinity of several filter units in the filter arrangement. The one or more air filter devices are arranged to gather sensor data representative of the operating state of the air filter arrangement. By sensor is meant a device comprising one or more sensing probes and an instrument capable of sensing a condition to be monitored. The output obtained from each sensor is an output value corresponding to the measured condition, e.g. airflow of cubic metres per hour, relative air humidity in percent, dust concentration of grams of dust per cubic metre and a pressure drop in pascals (dP).

The air filter sensor device containing the sensors is included in the air filter arrangement, e.g., on an upstream side or on a downstream side. The air filter sensor device may also receive additional input from sensors positioned outside of the air filter arrangement, e.g. some sensors positioned on an upstream side of the air filter arrangement, while others are placed on the downstream side. As disclosed, air filter sensor devices may be arranged on two or more filter units in the filter arrangement. Thus, the output from the air filter control station may include input from a plurality of air filter devices in the same air filter arrangement, but relating to an operating state of different filter units in the air filter arrangement. The input for the respective air filter devices to a receiving air filter control station may vary in that different air filter devices may include different sensors, but where the input for the respective air filter devices differs with regard to the sensor data input, e.g., content of particles and pressure drop. The use of a plurality of air filter devices allows for a more detailed and balanced information of the condition of individual filter units when having multiple filter units in a filter arrangement, providing information on which filter that may be most economical to change and also viable estimates on a remaining lifetime on the present filter units.

The air filter devices are arranged to collect air filter data, but may according to aspects of the disclosure also collect performance related data. Such data may also be retrieved to the air filter control station directly from an operation environment of the application, e.g., in a combustion turbine power plant.

The block diagram of Figure 4 discloses an example system 40 for air filter management comprising two air filter devices 41 a,b provided at air filter arrangements of uncorrelated air flow passages to respective applications and an air filter control station 42. According to an aspect of the disclosure, each air filter device 41a, b is embodied as described with reference to Figure 3. According to an aspect of the disclosure, each air filter device 41a, b is integrated with a respective air filter arrangement, e.g. being part of a structural element of an air filter framework. Even though the block diagram discloses a direct wireless link 43 between the air filter sensor device and the air filter control station, it is obvious to a person skilled in the art that the entities may communicate by means of a multitude of wireless nodes so that wireless communication is used for delivering data from the air filter sensor devices to a receiving control station, but that wireless links may not be needed in every communication instance from the air filter sensor device 41a, b to the air filter control station 42. It should also be understood that the air filter control station may include one or more cooperating entities, where a user interface may be provided as an application in a computer, mobile phone or on a tablet, while the actual processing is performed in a cloud environment, e.g., by cooperating servers located in different locations or in a same geographical location. For the case of failed transmission, local storage for up to 6 months data is also foreseen in the air filter device. As mentioned, the air filter sensor device also comprises a memory arranged to provide for such local storage.

The system 40 for air filter management comprises a plurality of air filter devices 41a, b and an air filter control station 42. Each air filter device 41a, b is provided at an air filter arrangement in an air flow inlet to an industrial installation, which air filter arrangement comprises at least one filter medium capable of removing particulate material and/or airborne molecular contamination, AMC, from an air flow received at the air flow inlet. Each air filter sensor device 41a, b comprises a set of sensors, i.e. at least flow determining means for determining air velocity and preferably also sensors to determine pressure drop over the air filter arrangement containing the air filter sensor device, arranged to gather sensor data representative of an operating state of the air filter arrangement. Each air filter sensor device 41a, b further comprises a microprocessor and a communication unit. The air filter control station 42 also comprises a communication unit arranged to receive sensor data from the plurality of air filter sensor devices 41a, b. The air filter control station provides a user interface for selecting an air filter arrangement of an air filter device 41a, b. Processing circuitry of the air filter control station is arranged to estimate a life expectancy of the selected air filter arrangement based on the sensor data received from the air filter sensor device 41a, b contained in the air filter arrangement and on the sensor data received from one or more other air filter sensor devices 41a, b. According to an aspect of the disclosure, the air filter sensor device comprises one or more of the following sensors: a temperature and humidity sensor, pressure drop sensor(s), ambient dust sensor and an air flow sensor. Thus, the air filter sensor device may provide a comprehensive set of sensor data required in management of the air filter arrangements. In the air flow sensor, air speed is analysed by a custom vortex flowmeter. A pressure sensor installed facing away from the airflow is used to determine pressure variations and the frequency of these variations. A Fast Fourier Transform, FFT, is performed for the input from the pressure sensor and used to determine the main frequency of vortex shedding caused by the moving air. From this frequency, the speed of moving air can be determined. Input from the air flow measurements may also be used when estimating a pressure loss and a pressure loss trend, dP trend. The dP trend depends on the pressure loss due to dust loading in the filter, but also to pressure loss due to humidity and rain. Pressure loss due to dust loading in the filter may be correlated to dust concentration (g/m 3 ) and airflow (m 3 /hour). The pressure loss due to humidity may be estimated from a correlation to humidity. According to the principles of the present invention, the air filter arrangement is used as a well-defined measurement platform for measuring a broad range of sensor data. Hence, the air filter arrangement is no longer used only for filtration, but in this case the grid of the air filter arrangement may be used for inducing a vortex in the air stream entering the air filter arrangement. Components contained in the air filter device, and consequently also in the air filter arrangement, are used to generate more accurate life cycle cost estimates based on highly reliable sensor data.

The air filter devices are used to gather the sensor data that is transmitted to an air filter control station on a regular basis. Each operator of the application is able to access data relating to conditions of their specific application from the air filter control station. According to an aspect of the disclosure, a communications interface to the air filter control station is provided by means of a web site or an application for a tablet.

The collected data is processed in the air filter control station. Such processing implies correcting data for flow conditions, creating historical trend lines for pressure drop, dP, based on measured data, and forecast future dP based on the historical trend lines. In a communication interface of the air filter control station, the end user may receive visual information on an operating state of the filter and operational aspects such as time until the filters need to be replaced due to technical reasons, i.e. pressure loss; time until filter replacement is recommended for commercial reasons; cost savings for making the filter replacement based on commercial reasons rather than technical reasons. Figure 5 discloses a flow diagram of exemplary method steps performed in an air filter sensor device of the system for air filter management disclosed in Figure 4. The air filter sensor device is configured to obtain S51 sensor data representative of an operating state of an air filter arrangement provided in an air flow passage to/from an industrial installation; the air filter arrangement comprising an air filter framework and at least one filter medium capable of removing particulate material and/or airborne molecular contamination, AMC, from an air flow received at the air flow passage. The air filter sensor device further comprises a microprocessor configured to process the obtained sensor data to determine S52 operating state information representing an operating state of the air filter arrangement where the air filter sensor device is located. The air filter sensor device transmits S53 the operating state information to a receiving remote air filter control station. The transmission of processed sensor data may be wireless and performed over a wireless link from the air filter sensor device to a receiving wireless access node enabling access to a data network and Internet.

A computer program product is also provided which is arranged to perform the above disclosed method steps when executed in an air filter device. Figure 6 discloses a flow diagram of an example method performed in an air filter control station for air filter management in an air filter management system. The disclosed method steps relate to operations in an air filter control station 42 of the air filter management system 40 disclosed in Figure 4. In its most general context, the method comprises receiving S61 sensor data from a plurality of air filter devices. According to an aspect of the disclosure, the air filter sensor devices may also be arranged to receive S62 performance data relevant for the application wherein the air filter arrangement is operated. In a further step, the air filter control station receives a filter condition query S63 relevant for a selected air filter arrangement of one or more air filter devices in the air filter management system. The air filter control station processes the query and provides operating state information S64, e.g., remaining life time or life expectancy of the selected air filter arrangement, based on sensor data received from that air filter device and possibly also from sensor data received from one or more other air filter devices. The query is received S63 over a user interface accessible to users having access to a login and password. Such users include application owners, but also filter maintenance personnel. The estimate for a life expectancy of the selected filter arrangement may either be performed upon receipt of data in the system, i.e., for any filter in the air filter arrangement as soon as new data is entered into the system or on receipt of a query relating to life expectancy of a given filter.

According to an aspect of the disclosure, the air filter control station may be a cloud application wherein data is collected and analyzed at regular intervals, e.g., once per day. Each customer receives a login and password that gives them access to filter data. The customer is able to determine the condition of every air flow inlet to the application, the technical lifetime of the filter arrangement and the economic lifetime for the filter arrangement, i.e., the point in time when the cost of maintaining the filter in further operation surpasses the cost for exchanging the filter. Data from the air filter control station may also be accessible to filter replacement providers so that they are able to improve service with regard to aftermarket filter replacement sales, but also to suggest amendments to the filter configurations based on historical performance data.

The air filter device and the air filter management system disclosed in the description above provides access to more reliable filter data in the air filter management system. Furthermore, the provisioning of an air filter arrangement that encompasses the air filter sensor device enables fast and cost effective installation or replacement of an air filter sensor device.