Device and method for measuring dust content in air flow

Abstract

The invention provides a device (1) for measuring the dust content in an air flow (14). The device (1) comprises a supply line (3) having an air inlet (4) for supplying an air flow (14) to a measuring chamber (5) for measuring the dust content. A pump (6) whose flow rate can be adjusted according to a control parameter is configured to draw the air flow (14) into the measuring chamber (5). A first measuring system (7) is configured to measure the velocity, temperature, pressure and moisture content of the air flow (14) at the air inlet (4). A second measuring system (8) is configured to measure the flow rate, temperature, pressure and moisture content of the air flow (14) in the measuring chamber (5). A third measuring system (9) is configured to measure the dust content in the measuring chamber (5). The supply line (3) and the measuring chamber (5) have a predetermined shape and size to establish a predetermined relationship between the control parameter and the air flow rate in the measuring chamber (5) at a given air flow rate at the air inlet (4).

Description

Technical Field

[0001] The invention relates to a device for measuring the dust content in a gas flow, preferably a gas flow in a duct. Furthermore, the invention also relates to a method for measuring the dust content in a gas flow in a duct using the device according to the invention. Background Art

[0002] A device for measuring dust content in an airflow is known from WO 2010 / 053386 A1 or US 3,784,902 A. Such devices are provided with a supply line having an air inlet for supplying an airflow into the device. In addition, such devices also include a measuring chamber that is fluidically connected to the supply line. The device is provided with a pump with adjustable flow rate, which is used to suck the airflow into the measuring chamber through the supply line. The measuring chamber is provided with a measuring system for measuring the dust content in the airflow. In WO 2010 / 053386 A1, the measuring system includes a light source and a photovoltaic cell. The dust content in the airflow is then determined based on the change in light intensity received by the photovoltaic cell when the airflow passes through. In US 3,784,902 A, the measuring system includes two electrodes between which the airflow can flow. The dust content in the airflow is then determined based on the current flowing between the two electrodes that varies with the applied voltage. In order to be able to measure the dust content under isokinetic conditions, the air flow velocity outside the supply line at the air inlet is measured by a pitot tube and the air flow velocity in the supply line is measured by a venturi tube. The flow rate of the pump is then adjusted based on the difference between the two velocities until the two velocities are substantially equal.

[0003] Such devices entail the drawback that parameters of the air flow, such as pressure, temperature and moisture content, may change when the air flow is sucked into the measuring chamber via the supply line. However, these parameters are of interest in order to enable the air flow velocity outside the supply line at the air inlet to be compared in a correct manner with the air flow velocity in the supply line or in the measuring chamber in order to measure the dust content under isokinetic conditions. Furthermore, these parameters are of interest in order to enable a correct indication of the total amount of dust in the air flow supplied to the device based on the dust content in the measuring chamber measured by the measuring system.

[0004] Another drawback of such devices is that the pump is controlled in such a way that it may take some time to reach isovelocity conditions based on the difference between the velocity of the gas flow outside the supply line at the gas inlet and the velocity of the gas flow in the supply line. Summary of the invention

[0005] The object of the present invention is to provide a device and a method which enable accurate and direct measurement of the dust content in a gas stream.

[0006] This object is achieved by showing a device for measuring the dust content in an air flow and showing a computer-implemented method for measuring the dust content of an air flow in a duct by means of the device.

[0007] To achieve this object, the present invention provides a device for preferably measuring the dust content in an air flow in a pipeline. The device comprises a supply line having an air inlet for supplying an air flow into the device. The device comprises a measuring chamber in which the dust content in the air flow is measured. The measuring chamber is in fluid communication with the supply line. The device comprises a pump with an adjustable flow rate, which is used to draw the air flow into the measuring chamber through the supply line. The pump is in fluid communication with the measuring chamber. The flow rate of the pump can be adjusted according to a predetermined control parameter. The device comprises a first measuring system, which is configured to measure the velocity, temperature, pressure and moisture content of the air flow at the air inlet of the supply line outside the supply line and at the air inlet. Preferably, the first measuring system is configured to measure the velocity, absolute temperature, absolute pressure and absolute moisture content of the air flow outside the supply line and at the air inlet. The device comprises a second measuring system, which is configured to measure the flow rate, temperature, pressure and moisture content of the air flow in the measuring chamber in the measuring chamber. Preferably, the second measurement system is configured to measure the flow rate, absolute temperature, absolute pressure and absolute moisture content of the airflow in the measurement chamber in the measurement chamber. The device includes a third measurement system, which is configured to measure the dust content in the airflow in the measurement chamber. Preferably, the third measurement system is configured to use an electronically readable sensor to measure the dust content in the airflow. Preferably, the third measurement system is configured to measure the dust content in the airflow by optical measurement in the measurement chamber. Preferably, the third measurement system is configured to measure the dust content in the airflow by light scattering of dust particles in the airflow in the measurement chamber. The device includes a control unit for controlling the device. The control unit is operably connected to the pump, the first measurement system, the second measurement system and the third measurement system. The supply line and the measurement chamber have a predetermined shape and size so as to establish a predetermined relationship between the control parameters of the pump and the airflow flow rate in the measurement chamber at a given flow rate of the airflow at the air inlet of the supply line.

[0008] In addition to measuring the velocity or flow rate, the first measurement system and the second measurement system are also configured to measure the temperature, pressure and moisture content of the air flow at the air inlet outside the supply pipeline and the air flow in the measurement chamber, respectively. The advantage is that these parameters can be taken into account so that the air flow velocity at the air inlet outside the supply pipeline can be compared with the air flow velocity in the measurement chamber in a correct manner, so that the dust content can be measured under isokinetic conditions in the measurement chamber using the third measurement system.

[0009] The first measurement system and the second measurement system are configured to measure the temperature, pressure and moisture content of the air flow at the air inlet outside the supply pipeline and the air flow in the measurement chamber, respectively, which has the advantage that these parameters can also be used based on the dust content of the air flow in the measurement chamber measured by the third measurement system to correctly indicate the amount of dust in the air flow supplied to the device.

[0010] The advantage of the predetermined shape and size of the supply line and the measuring chamber is that, based on the flow rate of the airflow outside the supply line at the air inlet, determined according to the parameters measured by the first measurement system (speed, temperature, pressure and moisture content of the airflow), the control parameters of the pump can be directly set to produce an airflow flow rate in the measuring chamber that is substantially equal to the airflow flow rate outside the supply line at the air inlet. For this purpose, the measurement conditions can be quickly brought to isokinetic conditions, under which the dust content in the airflow in the measuring chamber can be measured by the third measurement system. Then, if necessary, the airflow flow rate in the measuring chamber determined according to the parameters measured by the second measurement system (flow rate, temperature, pressure and moisture content of the airflow) can also be used to make a small correction to the control parameters of the pump, so as to achieve a high accuracy of the airflow flow rate in the measuring chamber close to the flow rate of the airflow outside the supply line at the air inlet.

[0011] In an embodiment of the device according to the invention, the device further comprises a housing. Preferably, the device comprises a portable housing. The supply line is at least partially arranged inside the housing, the air inlet of the line being outside the housing. The first measuring system is arranged outside the supply line and at the air inlet. The measuring chamber, the pump, the second measuring system, the third measuring system and the control unit are arranged in the housing.

[0012] Mounting the different components of the device in a housing according to the invention has the advantage of shielding the different components from any external influences that could affect the measurement, thereby improving the accuracy of the measurement. Mounting the different components of the device in a portable housing has the advantage of making the device mobile and enabling direct and accurate measurements to be made quickly on site.

[0013] In an embodiment of the device according to the invention, the second measurement system is further configured to measure the oxygen content of the gas flow in the measurement chamber.

[0014] Another meaningful parameter for being able to correctly indicate the amount of dust in the air flow supplied to the device under certain conditions based on the dust content of the air flow in the measuring chamber measured by the third measuring system is the oxygen content of the air flow in the measuring chamber. For this purpose, it is advantageous to also configure the second measuring system to determine the oxygen content in the air flow in the measuring chamber, thereby improving the accuracy of the amount of dust in the air flow supplied to the device, wherein the amount of dust in the air flow supplied to the device is determined based on the dust content in the air flow in the measuring chamber measured by the third measuring system.

[0015] In an embodiment of the device according to the invention, the device further comprises a filter in the measuring chamber and downstream of the third measuring system, which filter determines gravimetrically the dust content of the air flow in the measuring chamber.

[0016] The advantage of also providing a filter in the measuring chamber is that a gravimetric determination of the dust content of the air flow in the measuring chamber can be performed in addition, which measurement can be used as a control for the measurement of the dust content of the air flow in the measuring chamber by the third measuring system. This further increases the accuracy of the device according to the invention.

[0017] In an embodiment of the device according to the invention, the device further comprises a dehumidification system between the measuring chamber and the pump for dehumidifying the air flow. The dehumidification system is located before the pump in the device, which is advantageous for protecting the pump from potential damage by moisture.

[0018] In an embodiment of the apparatus according to the invention, the dehumidification system comprises a steam trap and a silica filter.

[0019] In an embodiment of the device according to the invention, the pump is a diaphragm pump.

[0020] In an embodiment of the device according to the invention, the first measurement system comprises a pitot tube and a differential pressure sensor for measuring the gas flow velocity at the gas inlet of the supply line.

[0021] In an embodiment of the device according to the invention, the second measurement system comprises a hot wire mass flow meter for measuring the gas flow rate in the measurement chamber.

[0022] In an embodiment of the device according to the invention, the supply line is provided with a heater for heating the gas flow in the supply line.

[0023] In addition, the present invention also provides a computer-implemented method for measuring the dust content in the air flow in the pipeline by means of the device according to the present invention. The supply pipeline of the device is arranged in the pipeline, and the air inlet is in the air flow. The method comprises the following steps performed by a control unit: The method comprises the step a): measuring the velocity, temperature, pressure and moisture content of the air flow at the air inlet of the supply pipeline by a first measurement system. Preferably, the method comprises the step a): measuring the velocity, absolute temperature, absolute pressure and absolute moisture content of the air flow at the air inlet of the supply pipeline by the first measurement system. The method comprises the step b): calculating the flow rate of the air flow at the air inlet of the supply pipeline based on the velocity, temperature, pressure and moisture content of the air flow at the air inlet of the supply pipeline measured by the first measurement system. The method comprises the step c): calculating the required control parameters of the pump so as to establish the air flow rate in the measurement chamber according to the predetermined relationship between the control parameters of the pump and the air flow rate in the measurement chamber at a given flow rate of the air flow at the air inlet of the supply pipeline, and the air flow rate in the measurement chamber is substantially equal to the calculated air flow rate at the air inlet of the supply pipeline. The method comprises the step d): controlling the pump according to the calculated control parameters to draw the airflow in the pipeline into the measuring chamber through the supply pipeline. The method comprises the step e): measuring the flow rate, temperature, pressure and moisture content of the airflow drawn in the measuring chamber by a second measuring system. Preferably, the method comprises the step e): measuring the flow rate, absolute temperature, absolute pressure and absolute moisture content of the airflow drawn in the measuring chamber by a second measuring system. The method comprises the step f): calculating the flow rate of the airflow drawn in the measuring chamber based on the flow rate, temperature, pressure and moisture content of the airflow drawn in the measuring chamber measured by the second measuring system. The method comprises the step g): comparing the calculated airflow flow rate drawn in the measuring chamber with the calculated airflow flow rate at the air inlet of the supply pipeline. If the calculated airflow rate inhaled in the measuring chamber is not substantially equal to the calculated airflow rate at the air inlet of the supply line, step g) further comprises adjusting the control parameters of the pump accordingly and repeating steps d) to g) using the adjusted control parameters of the pump until the calculated airflow rate inhaled in the measuring chamber and the calculated airflow rate at the air inlet of the supply line are substantially equal. The method comprises step h): measuring the dust content of the airflow inhaled in the measuring chamber by a third measuring system. Step h) further comprises measuring the temperature, pressure and moisture content of the airflow inhaled in the measuring chamber by a second measuring system. Preferably, step h) further comprises measuring the absolute temperature, absolute pressure and absolute moisture content of the airflow inhaled in the measuring chamber by a second measuring system.The method comprises step i): calculating the dust content of the air flow sucked into the measuring chamber under normal conditions based on the dust content of the air flow sucked into the measuring chamber measured by the third measuring system and the temperature, pressure and moisture content of the air flow sucked into the measuring chamber measured by the second measuring system.

[0024] In an embodiment of the method according to the invention, step h) further comprises measuring the oxygen content of the air flow sucked into the measuring chamber by means of a second measuring system. In step i), the dust content in the air flow sucked into the measuring chamber under normal conditions is also calculated based on the oxygen content in the air flow sucked into the measuring chamber measured by the second measuring system.

[0025] In an embodiment of the method according to the invention, steps h) and i) are repeated periodically within a predetermined period of time in order to calculate the average dust content of the air flow sucked into the measuring chamber under normal conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Hereinafter, the present invention will be described in further detail through the following description and accompanying drawings.

[0027] Figure 1 A schematic diagram of a device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] The invention will be described hereinafter with reference to specific embodiments and certain drawings, but the invention is not limited thereto but only by the claims. The drawings shown herein are only schematic and non-restrictive. In the drawings, the dimensions of certain elements may be exaggerated, which means that the components discussed are only for illustrative purposes and are not drawn to scale. The dimensions and relative dimensions do not necessarily correspond to actual reductions in the implementation of the invention.

[0029] Furthermore, terms such as "first," "second," "third," etc., in the description and claims are used to distinguish similar elements and not necessarily to describe a sequential or chronological order. The terms discussed are interchangeable under appropriate circumstances, and embodiments of the invention may operate in other sequences than those described or illustrated herein.

[0030] Furthermore, terms such as "top", "bottom", "above", "below", etc. in the description and claims are used for descriptive purposes and not necessarily for indicating relative positions. The terms so used are interchangeable under appropriate circumstances, and the embodiments of the invention described herein may operate in other orientations than described or illustrated herein.

[0031] The term "comprises" and its derivatives used in the claims should not be interpreted as being limited to the means listed thereafter, and it does not exclude other elements or steps. It should be interpreted as limiting the presence of the mentioned features, integers, steps or components, but not excluding the presence or addition of one or more additional features, integers, steps or components or combinations thereof. Therefore, the scope of expressions such as "a device comprising means A and B" is not limited to a device consisting only of means A and B. With respect to the present invention, it only means that the relevant components of the device are A and B.

[0032] Figure 1 A schematic diagram of a device 1 for measuring dust content in a gas flow 14 according to an embodiment of the present invention is shown.

[0033] The device 1 comprises a housing 2, in which the main components of the device 1 are arranged, except for a supply line 3 for supplying a gas flow 14 to the device 1. The supply line 3 has an air inlet 4, through which the gas flow 14 can flow into the supply line 3. The air inlet 4 is located outside the housing 2. The supply line 3 extends from the air inlet 4 to the housing 2, and then the supply line 3 continues to extend inside the housing 2. In order to achieve a proper supply of the gas flow 14 to the device 1, the air inlet 4 is preferably arranged substantially perpendicular to the flow direction of the gas flow 14. The supply line 3 can optionally be provided with a heating device for heating the gas flow 14 in the supply line 3. The supply line 3 can also be provided with a shut-off valve for shutting off the supply line 3, so that the device 1 can be leak tested.

[0034] The apparatus 1 further comprises a measuring chamber 5 in fluid communication with the supply line 3, such that a gas flow 14 can flow from the supply line 3 to the measuring chamber 5. The measuring chamber is configured to measure the dust content in the gas flow 14 therein.

[0035] The device 1 further comprises a pump 6 in fluid communication with the measuring chamber 5. The pump 6 is configured to draw the airflow 14 into the measuring chamber 5 via the supply line 3. The pump 6 is configured such that the flow rate of the pump 6 can be adjusted according to a control parameter. The control parameter can be, for example, a control voltage of the pump 6 or, in the case of a numerically controlled pump 6, for example, a digital signal. By setting the flow rate of the pump 6 via the control parameter, the dust content of the airflow 14 in the measuring chamber 5 can be measured under isokinetic conditions, in which the velocity of the airflow 14 outside the supply line 3 at the air inlet 4 is substantially equal to the velocity of the airflow 14 in the measuring chamber 5.

[0036] A diaphragm pump can be used, for example, as the pump 6. The diaphragm pump 6 has the advantage of being relatively compact and lightweight. This enables the pump 6 to be easily installed in the housing 2 and also enables the device 1 to remain light and compact. In addition, the diaphragm pump 6 can also handle a wide range of flow rates for the suction airflow 14, so that the device 1 can measure the dust content of the airflow 14 at different speeds under isokinetic conditions. However, it should be understood that other suitable pumps known to those skilled in the art can also be used.

[0037] In order to protect the pump 6 from condensed water in the gas stream 14, the apparatus 1 may also optionally be provided with a dehumidification system 12 between the measuring chamber 5 and the pump 6. The dehumidification system 12 may, for example, comprise a steam trap for removing most of the condensed water in the gas stream 14. If necessary, the dehumidification system 12 may also be equipped with a silica filter in order to further dry the gas stream 14 after it leaves the steam trap and before the pump 6.

[0038] The device 1 is provided with a first measuring system 7 outside the supply line 3 at the air inlet 4. The first measuring system 7 is configured to measure at this location the velocity, temperature, pressure and moisture content of the air flow 14. Preferably, the absolute temperature, absolute pressure and absolute moisture content of the air flow 14 are thereby measured. To measure the velocity of the air flow 14, the first measuring system 7 is provided, for example, with a pitot tube combined with a differential pressure sensor, although other suitable sensors for measuring the velocity of the air flow 14 known to those skilled in the art may also be used.

[0039] In the measuring chamber 5, the device 1 is provided with a second measuring system 8. The second measuring system 8 is configured to measure the flow rate, temperature, pressure and moisture content of the gas flow 14 in the measuring chamber 5. Preferably, the absolute temperature, absolute pressure and absolute moisture content of the gas flow 14 are thereby measured. In order to measure the flow rate of the gas flow 14, the second measuring system 8 is provided, for example, with a hot wire mass flow meter, although other suitable sensors known to those skilled in the art for measuring the flow rate of the gas flow 14 can also be used. The second measuring system 8 is preferably also configured to measure the oxygen content of the gas flow 14 in the measuring chamber 5.

[0040] In the measuring chamber 5, the device 1 is also provided with a third measuring system 9. The third measuring system 9 is configured to measure the dust content of the airflow 14 in the measuring chamber 5. For measuring the dust content in the airflow 14, preferably a combination of a laser light source for irradiating the airflow 14 and a sensor for measuring light scattered by dust particles in the airflow 14 in one or more directions different from the direction of the laser beam of the laser light source is used. Such optical measurement enables a rapid measurement of the dust content in the airflow 14, which can then be read out electronically from the sensor. However, other sensors for measuring the dust content in the airflow 14 known to the person skilled in the art can also be used, which enable a rapid measurement of the dust content and a rapid electronic readout of the measured dust content.

[0041] Optionally, the device 1 can also be provided with a filter 11 located after the third measuring system in the measuring chamber 5 (as viewed in the flow direction of the air flow 14 from the air inlet 4 of the supply line 3 towards the pump 6). The filter 11 is configured for gravimetric determination of the dust content of the air flow 14 in the measuring chamber 5. Here, the dust contained in the air flow 14 is deposited on the filter 11 with a known weight, and after the measurement, the filter 11 and the deposited dust are weighed in order to determine the amount of dust in the air flow 14 in the measuring chamber 5. This additional measurement is then used to control the measurement of the dust content in the air flow 14 in the measuring chamber 5 by the third measuring system 9.

[0042] The supply line 3, the measurement chamber 5, and any connector extending between the measurement chamber 5 and the pump 6 all have predetermined shapes and sizes. This establishes a predetermined relationship between the control parameters of the pump 6 and the flow rate of the airflow 14 in the measurement chamber 5 for a given flow rate of the airflow 14 at the air inlet 4 of the supply line 3. The predetermined relationship enables the first measurement system 1 to be used to determine the flow rate of the airflow 14 at the air inlet 4 and then to select appropriate control parameters for the pump 6 based on the relationship, so as to achieve that the flow rate of the airflow 14 in the measurement chamber 5 is substantially equal to the flow rate of the airflow 14 at the air inlet 4 of the supply line 3, so that the dust content of the airflow 14 in the measurement chamber 5 can be measured under isovelocity conditions using the third measurement system 9.

[0043] The device 1 further comprises a control unit 10 for controlling the different components of the device 1. Thus, the control unit 10 is operatively connected to the first measurement system 7 to measure the velocity, temperature, pressure and moisture content of the gas flow 14 outside the supply line 3 at the gas inlet 4; the control unit is operatively connected to the second measurement system 8 to measure the flow rate, temperature, pressure, moisture content and optionally the oxygen content of the gas flow 14 in the measurement chamber 5; the control unit is operatively connected to the third measurement system 9 to measure the dust content in the gas flow 14 in the measurement chamber 5. Thus, the control unit 10 can instruct the first measurement system 7, the second measurement system 8, the third measurement system 9 to perform measurements, read the values ​​measured by the respective first measurement system 7, the second measurement system 8, the third measurement system 9 and process the measured values ​​for further use.

[0044] Furthermore, the control unit 10 is also operably connected to the pump 6 to control the pump 6 based on the control parameter. Thus, for the flow rate of the gas flow 14 at the gas inlet 4 of the supply line 3, which is calculated based on the values ​​measured by the first measurement system 7, the control unit 10 can determine the control parameter according to the relationship between the control parameter of the pump 6 and the flow rate of the gas flow 14 in the measurement chamber 5. Here, the flow rate of the gas flow 14 in the measurement chamber 5, which is calculated based on the values ​​measured by the second measurement system 8, can also be compared with the flow rate of the gas flow 14 outside the supply line 3 at the gas inlet 4, which is calculated based on the values ​​measured by the first measurement system 7, in order to correct the control of the pump 6.

[0045] If necessary, the control unit 10 may also be operatively connected to a shut-off valve provided on the supply line 3 to open and close the supply line 3. Thus, the control unit 10 may also be arranged to perform a leak test on the device 1 by closing the supply line 3 via the shut-off valve.

[0046] The dust content of the gas flow 14 in the duct 13 is then measured using the device 1 according to an embodiment of the invention as described below.

[0047] First, the supply line 3 of the device 1 is arranged in the duct 13 together with the air inlet 4. Here, the air inlet 4 is preferably arranged in the duct 13 substantially perpendicularly to the flow direction of the air flow 14 in order to achieve a proper supply of the air flow 14 to the device 1.

[0048] Subsequently, the first measurement system 7 is controlled by the control unit 10 to measure the velocity, temperature, pressure and moisture content of the air flow 14 at the air inlet 4 of the supply line 3. Then, based on the values ​​measured by the first measurement system 7, the control unit 10 calculates the flow rate of the air flow 14 at the air inlet 4 of the supply line 3 in the pipe 13.

[0049] Then, in a subsequent step, the control unit 10 calculates the control parameters of the pump 6 as needed to achieve a flow rate of the gas flow 14 in the measurement chamber 5 that is substantially equal to the flow rate of the gas flow 14 at the gas inlet 4 of the supply line 3, which is calculated by the control unit 10 based on the values ​​measured by the first measurement system 7. This is done based on the following known relationship: the known relationship is a known relationship between the control parameters of the pump 6 and the flow rate of the gas flow 14 in the measurement chamber 5 at a given flow rate of the gas flow 14 at the gas inlet 4 of the supply line 3.

[0050] Then, in a further step, the control unit 10 controls the pump 6 as a function of the calculated control parameter in order to draw the gas flow 14 in the duct 5 into the measuring chamber 5 via the supply line 3 .

[0051] Subsequently, the control unit 10 controls the second measurement system 8 to measure the flow rate, temperature, pressure, moisture content and optionally oxygen content of the gas flow 14 sucked into the measurement chamber 5 by the pump 6 in the measurement chamber 5. Then, the control unit 10 calculates the flow rate of the gas flow 14 in the measurement chamber 5 based on the values ​​measured by the second measurement system 8.

[0052] Then, in a subsequent step, the control unit 10 compares the flow rate of the airflow 14 in the measurement chamber 5, calculated based on the values ​​measured by the second measurement system 8, with the flow rate of the airflow 14 at the air inlet 4 of the supply line 3, calculated based on the values ​​measured by the first measurement system 7. In the case where the two calculated flow rates are not substantially equal, the control unit 10 calculates the adjusted control parameters of the pump 6 based on the difference between the calculated flow rates. The control unit 10 can then repeat the aforementioned steps starting with controlling the pump 6 using the adjusted control parameters until the calculated flow rates are substantially equal. In the case where the calculated flow rates are substantially equal, the isovelocity condition is achieved, and the following steps of measuring the dust content of the airflow 14 can be performed.

[0053] Then, in these steps, the control unit 10 controls the third measuring system 9 to measure, in the measuring chamber 5, the dust content of the airflow 14 sucked into the measuring chamber 5 by the pump 6. Then, the control unit 10 also controls the second measuring system 8 to measure, in the measuring chamber 5, the temperature, pressure, moisture content and, optionally, oxygen content of the airflow 14 sucked into the measuring chamber 5 by the pump 6. These measurements are performed within a predetermined time period and, if necessary, can be repeated to calculate an average value.

[0054] The control unit 10 then calculates the dust content of the air flow 14 sucked into the measuring chamber 5 by the pump 6 under normal conditions based on the dust content measured by the third measuring system 9 and the value measured by the second measuring system 8. If necessary, the flow rate of the air flow 14 at the air inlet 4 of the supply line 3 and the flow rate of the air flow 14 in the measuring chamber 5 can also be monitored by the control unit 10 during the measurements performed by the first measuring system 7 and the second measuring system 8, respectively. This is to verify whether isovelocity conditions are maintained during the measurement of the dust content of the air flow 14 in the measuring chamber 5 by the third measuring system 9.

[0055] If necessary, before and after using the device 1 to measure the dust content of the gas flow 14 in the duct 13, a leak test can additionally be performed to ensure that no leaks are present in the device 1 which could have an influence on the dust content measurement.

[0056] Reference numerals

[0057] 1 Equipment

[0058] 2 Housing

[0059] 3 Supply lines

[0060] 4 Air Inlet

[0061] 5 Measurement chamber

[0062] 6 Pumps

[0063] 7 First measurement system

[0064] 8 Second measurement system

[0065] 9 Third measurement system

[0066] 10 Control unit

[0067] 11 Filters

[0068] 12 Dehumidification system

[0069] 13 Pipe

[0070] 14 Airflow

Claims

1. A device (1) for measuring the dust content in a gas stream (14), wherein: The device (1) comprises: a supply line (3) having an air inlet (4) for supplying a gas flow (14) in the device (1); a measuring chamber (5) for measuring the dust content of the air flow (14) therein, wherein the measuring chamber (5) is in fluid communication with the supply line (3); a pump (6) capable of regulating flow, the pump being used to draw a gas flow (14) into the measuring chamber (5) via the supply line (3), wherein the flow rate of the pump (6) can be regulated according to a predetermined control parameter; a first measurement system (7) configured to measure, outside the supply line (3) and at the air inlet (4), the velocity, temperature, pressure and moisture content of the air flow (14) at the air inlet (4) of the supply line (3); a second measurement system (8) configured to measure, in the measurement chamber (5), the flow rate, temperature, pressure and moisture content of the air flow (14) in the measurement chamber (5); a third measuring system (9) configured to measure the dust content of the air flow (14) in the measuring chamber (5); and a control unit (10) for controlling the device (1), wherein the control unit (10) is operatively connected to the pump (6), the first measuring system (7), the second measuring system (8) and the third measuring system (9); The supply line (3) and the measuring chamber (5) have a predetermined shape and size so as to establish a predetermined relationship between the control parameters of the pump (6) and the flow rate of the air flow (14) in the measuring chamber (5) at a given flow rate of the air flow (14) at the air inlet (4) of the supply line (3); based on the predetermined relationship, the control parameters of the pump (6) are set so that the flow rate of the air flow (14) in the measuring chamber (5) is equal to the air flow (14) at the air inlet (4) of the supply line (3). The flow rates of the air flow at the air inlet of the supply pipeline (3) are substantially equal, the flow rate of the air flow at the air inlet of the supply pipeline is determined based on the velocity, temperature, pressure and moisture content of the air flow (14) at the air inlet (4) of the supply pipeline (3) measured by the first measurement system (7), and the control parameters of the pump (6) can be corrected using the flow rate of the air flow (14) in the measurement chamber (5) determined based on the flow rate, temperature, pressure and moisture content of the air flow (14) in the measurement chamber (5) measured by the second measurement system (8).

2. The device (1) according to claim 1, wherein: The device (1) further comprises a housing (2), wherein the supply line (3) is at least partially arranged inside the housing (2), the air inlet (4) is located outside the housing (2), wherein the first measuring system (7) is arranged outside the supply line (3) and at the air inlet (4), and wherein the measuring chamber (5), the pump (6), the second measuring system (8), the third measuring system (9) and the control unit (10) are arranged inside the housing (2).

3. The device (1) according to claim 1 or 2, wherein: The device (1) further comprises a filter (11) in the measuring chamber (5) after the third measuring system (9), which is used to determine the dust content of the air flow (14) in the measuring chamber (5) by gravimetric analysis.

4. The device (1) according to claim 1 or 2, wherein: The device also comprises a dehumidification system (12) between the measuring chamber (5) and the pump (6), the dehumidification system being used to dehumidify the air flow (14).

5. The device (1) according to claim 4, wherein: The dehumidification system (12) includes a steam trap and a silica filter.

6. The device according to claim 1 or 2, wherein: The pump (6) is a diaphragm pump.

7. The device (1) according to claim 1 or 2, wherein: The first measurement system (7) comprises a pitot tube and a differential pressure sensor for measuring the velocity of the air flow (14) at the air inlet (4) of the supply line (3).

8. The device (1) according to claim 1 or 2, wherein: The second measurement system (8) comprises a hot-wire mass flow meter for measuring the flow rate of the gas flow (14) in the measurement chamber (5).

9. The device (1) according to claim 1, wherein: The third measuring system is configured to measure the dust content of the air flow (14) in the measuring chamber (5) by optical measurement.

10. A computer-implemented method for measuring the dust content of an air flow (14) in a duct (13) by means of a device (1) according to claim 1 or 2, wherein: The supply line (3) of the device (1) is arranged in the duct (13) and the air inlet (4) is in the air flow (14), wherein the method comprises the following steps performed by a control unit (10): a) measuring the velocity, temperature, pressure and moisture content of the gas flow (14) at the gas inlet (4) of the supply line (3) by means of a first measuring system (7); b) calculating the flow rate of the air flow (14) at the air inlet (4) of the supply line (3) based on the velocity, temperature, pressure and moisture content of the air flow (14) at the air inlet (4) of the supply line (3) measured by the first measurement system (7); c) calculating a required control parameter of the pump (6) so as to establish a flow rate of the air flow (14) in the measuring chamber (5) that is substantially equal to the calculated flow rate of the air flow (14) at the air inlet (4) of the supply line (3) based on a predetermined relationship between the control parameter of the pump (6) and the flow rate of the air flow (14) in the measuring chamber (5) at a given flow rate of the air flow (14) at the air inlet (4) of the supply line (3); d) controlling the pump (6) according to the calculated control parameter to draw the gas flow (14) in the pipe (13) into the measuring chamber (5) through the supply line (3); e) measuring the flow rate, temperature, pressure and moisture content of the air flow sucked into the measuring chamber (5) by means of a second measuring system (8); f) calculating the flow rate of the air flow (14) sucked into the measuring chamber (5) based on the flow rate, temperature, pressure and moisture content of the air flow (14) sucked into the measuring chamber (5) measured by the second measuring system (8); g) comparing the calculated flow rate of the air flow (14) sucked into the measuring chamber (5) with the calculated flow rate of the air flow (14) at the air inlet (4) of the supply line (3), and if the calculated flow rate of the air flow (14) sucked into the measuring chamber (5) is not substantially equal to the calculated flow rate of the air flow (14) at the air inlet (4) of the supply line (3), adjusting the control parameters of the pump (6) accordingly, and repeating steps d) to g) using the adjusted control parameters of the pump (6) until the calculated flow rate of the air flow (14) sucked into the measuring chamber (5) is substantially equal to the calculated flow rate of the air flow (14) at the air inlet (4) of the supply line (3); h) measuring the dust content of the air flow (14) sucked into the measuring chamber (5) by means of a third measuring system (9), and measuring the temperature, pressure and moisture content of the air flow (14) sucked into the measuring chamber (5) by means of the second measuring system (8); and i) calculating the dust content of the air flow (14) sucked into the measuring chamber (5) under normal conditions based on the dust content of the air flow (14) sucked into the measuring chamber (5) measured by the third measuring system (9) and the temperature, pressure and moisture content of the air flow sucked into the measuring chamber (5) measured by the second measuring system (8).

11. The method according to claim 10, wherein: Steps h) and i) are repeated periodically within a predetermined period of time to calculate the average dust content of the air flow (14) sucked into the measurement chamber (5) under normal conditions.

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