SE541665C2

SE541665C2 - Vacuum cleaning system for hot dust and particles

Info

Publication number: SE541665C2
Application number: SE1550432A
Authority: SE
Inventors: Mattias Petersson
Original assignee: Disab Tella Ab
Priority date: 2015-04-13
Filing date: 2015-04-13
Publication date: 2019-11-19
Also published as: EP3283769A1; WO2016166033A1; SE1550432A1

Abstract

A vacuum unit (11), a vacuum cleaning system (1) and a method for controlling a vacuum unit (11) is presented. The vacuum unit (11) comprises a compressor suction pump (30), an air valve (36) arranged at the inlet (40) of the compressor suction pump (30), at least one temperature sensor (32, 33) for sensing the temperature of air flowing through the compressor suction pump (30). A control unit (34) is configured to selectively open the air valve (36) in response to the temperature, wherein surrounding air is admitted into the inlet. The vacuum cleaning system (1) comprises the vacuum unit (11), a filtering system (12), and a pipe system (13) provided with a suction nozzle (14). The method includes creating (102) a first air stream, transferring dust and particles by means of the first air stream through the pipe system, measuring (104) the temperature of the air at the vacuum unit (11), and selectively opening (106) the air valve (36) in response to the temperature, so as to cool the first air stream.

Description

Vacuum cleaning system for hot dust and particles Technical Field The invention relates to vacuum cleaning systems for industrial use comprising a vacuum unit, a filtering system, and a pipe system provided with a suction nozzle. The filtering system is arranged in a suction direction between the nozzle and the vacuum unit.

Background Known industrial vacuum cleaning systems include a vacuum unit provided with a compressor suction pump that has a high power level in order to provide appropriate suction and air flow. The power level can be of such a magnitude that the vacuum unit may raise the temperature of the air flow significantly during the compression, for example the temperature may be raised about 50-90 degrees Centigrade. Compressor suction pumps can be configured so that the risk that they will become overheated when operating in “normal” conditions is small, such as when operating at a room temperature of 15-25 degrees Centigrade. If the temperature of the incoming air flow is high, the raise in temperature during compression may lead to a temperature level wherein a safe operation cannot be guaranteed. Vacuum units may comprise a safety system that breaks the electric supply to the vacuum unit if the temperature becomes too high, say above 150 degrees Centigrade.

Working with hot dust and particles may therefore not be possible, since the vacuum unit may be over-heated and/or unnecessarily stopped.

Document US 2004/0258551 A1 (‘551) describes a vacuum suction pump comprising a screw-type compressor. The screw compressor is provided with an air cooler (35 in '551) arranged to receive a part of the heated air from an exhaust outlet (12 in is returned into the screw compressor, via an inlet (37 in '551) into a receiving section (17 in '551) at the area of the exhaust outlet (12) in order to cool the compressed air in the discharge side. The cooler (35) prevents overheating. A disadvantage with such a cooling is that it requires arranging a separate cooler and arranging connections into the screw compressor. The cooling is also not adapted for varying temperatures of the air that arrives at the inlet.

Summary of invention An object of the invention is to overcome the disadvantages of the prior art.

An object of the invention is to clean an industry from hot dust and particles, by sucking in and transferring the hot dust and particles.

An object of the invention is to provide facilitated means for implementing a reliable method and system for sucking in and transferring hot dust and particles.

An object of the invention is also to provide means for handling varying temperatures of the air flow.

The present invention relates to a vacuum cleaning system for sucking and transferring hot dust and hot particles. The vacuum cleaning system comprises a vacuum unit. The vacuum unit comprises: - a compressor suction pump having an inlet and an outlet, - a duct comprising a connection for a pipe system of a cleaning system, which duct is arranged at the inlet and configured to provide an air flow path from the pipe system to the inlet. By connecting the pipe system to the inlet of the compressor suction pump a suction is created in the pipe system. The vacuum unit further comprises - an air valve arranged at the duct between the inlet and the pipe system connection, which air valve is arranged to selectively admit air into the duct; - a control unit operatively connected to the air valve and configured to control the air valve, and - at least one temperature sensor for sensing (e.g. measuring) the temperature of air flowing through the compressor suction pump and which temperature sensor is connected to the control unit.

The control unit is configured to selectively open the air valve in response to the temperature received from the at least one temperature sensor.

By configuring the control unit to control the opening and closing of the air valve, the air flow arriving at the inlet can be cooled so that the air flow through the compressor suction pump becomes cooler, the compressor suction pump is cooled, and the air flowing through the outlet becomes cooler. Thus, the vacuum unit has been especially adapted for high temperatures of the arriving air flow, such as leading to a temperature of e.g. 150 degrees Centigrade at the outlet, and is suitable for use in processes for cleaning of hot material and hot environments.

By configuring the control unit to selectively open the air valve based on the sensed temperature, the air valve can be kept closed so as not to decrease the suction power in the pipe system when cooling is not needed. The vacuum unit may suitable be dimensioned to operate without using the air valve when cleaning dust and particles of room temperature, i.e. at 15 to 25 degrees Centigrade. Thus, the air inlet valve controlled by the control unit in response to the air flow temperature makes it possible to also suck in and transfer hot dust and particles when such cleaning is needed. In this way the vacuum unit may be used both for room temperature cleaning and for cleaning hot areas, and thus the air valve arrangement enhances the use range for the vacuum unit.

Arranging a duct between the inlet of the compressor suction pump and a pipe connection, which duct is provided with an air valve that is controlled by a control unit, simplifies modification of existing vacuum cleaning systems without the need for reconstruction of the compressor suction pump.

The air valve is suitable arranged to admit the atmospheric air surrounding the vacuum unit to blend with the air stream received from the areas that are cleaned. The connection for a pipe system can be used to arrange the vacuum unit away from hot areas to be cleaned and to receive the incoming air stream via the pipe system.

In an embodiment, the at least one temperature sensor is configured to measure the temperature of the air flowing through the outlet of the compressor suction pump, wherein the control unit is configured to open the air valve based on the temperature of the air flow at the outlet.

The temperature sensor is preferably arranged at the outlet where the temperature of the vacuum unit is the highest.

In an embodiment, the control unit is configured to open the air valve in response to the temperature exceeding a first threshold.

The first threshold should be slightly lower, e.g. ten degrees lower, than a maximum allowed temperature of the vacuum unit. For a vacuum unit having a maximum allowed temperature for safe operation of 150 degrees Centigrade, the first threshold can be set to about 140 degrees Centigrade.

In an embodiment, the control unit is configured to close the air valve in response to the temperature falling below a second threshold, which second threshold is lower than the first threshold.

An open air valve decreases the suction power provided by the vacuum unit, and the air valve should be closed when cooling is not needed. The second threshold should be lower than the first threshold to prevent excessive opening and closing of the air valve. A suitable level for the second threshold can be 125 degrees Centigrade.

In an embodiment, a suitable vacuum suction pump is a compressor suction pump selected from any of: - a rotary lobe compressor, - a screw compressor, and - a rotary displacement blower.

Preferably, the compressor suction pump is a rotary lobe compressor. A rotary lobe compressor is more suitable to use than a screw compressor, since the rotating lobes have a more even temperature, whereas a screw of a screw compressor is warmer close to the outlet than at the inlet. Therefore, the cooling provided by air flowing from the air valve will more efficiently cool a rotary lobe compressor.

These types of compressors are suitable for compressor suction pumps in order to create appropriate power. The compressor suction pump can suitably be selected that has, or be dimensioned to provide, a vacuum level of 500 mbar to 900 mbar. Air displacement blowers are also referred to as Rootstype blower or compressors, or rotary displacement blowers. Rotary lobe compressor are a special type of Roots-type compressors. Screw compressors are also referred to as Lysholm-type compressors. The compressor suction pump should be able to provide a suction suitable for industrial cleaning in contrast to domestic cleaning, and the listed compressor types are suitable for providing comparably high volume rates of flowing air.

It is preferred to measure the temperature at the outlet of the compressor suction pump since the compressor suction pump raises the temperature of the air flowing through the suction pump due to the compression performed. However, the temperature of air arriving at the inlet of the compressor suction pump may be sensed, and used for controlling the selective opening and closing of the air valve.

In an embodiment, at least one of the at least one temperature sensor is configured to measure the temperature of the air flowing through the inlet of the compressor suction pump, wherein the control unit is configured to open the air valve in response to the temperature at the inlet exceeding a third threshold.

The relation between the inlet air temperature and the outlet air temperature depends on the compression performed by the compressor suction pump and therefore the relation can be known, at least approximately, during use. The inlet air temperature may be used as an alternative to using the outlet air temperature. The inlet air temperature and outlet air temperature may also be used in combination, for example as a safety measure from malfunctioning temperature measurements at the outlet. Measuring the inlet air temperature also provides operational data for monitoring the performance of the compressor suction pump.

In an embodiment, the control unit is configured to close the air valve in response to the temperature at the inlet falling below a fourth threshold, which fourth threshold is lower than the third threshold.

In an embodiment, the control unit is configured to stop the suction pump when reaching a maximum allowed temperature at the outlet, which maximum temperature is higher than the first threshold.

Thus, if enough cooling cannot be provided by opening of the air valve, the vacuum unit may stop the compressor suction pump. For a compressor suction pump driven by motor, such as an electrical motor or combustion engine, the control unit may be operatively connected to the motor and adapted to switch off the motor when the temperature exceeds the maximum allowed temperature. The control unit can, for example, be configured to break the electric power to the motor by means of switching off an electronically controlled power switch of the electric motor or combustion engine, respectively.

In an embodiment, the vacuum unit comprises at least one vacuum release valve. The vacuum release valve can suitable be of a spring-loaded type arranged to open when the pressure at the inlet becomes too low, i.e. the vacuum level becomes too high. The vacuum release valve is adapted to open when the vacuum level exceeds the vacuum level that the compressor suction pump is dimensioned for.

In an embodiment, the control unit is configured with a standby mode of operation, which when activated allows running the compressor suction pump in idling at the same time as keeping the air valve open. In this way, the vacuum unit can be cooled when a cleaning process is paused by keeping the compressor suction pump running without sucking in and transferring dust and particles.

Thus, the present invention relates to a vacuum cleaning system for sucking and transferring hot dust and hot particles. The vacuum cleaning system comprises: - a vacuum unit as described above, - a filter system, and - a pipe system provided with a suction nozzle, wherein the pipe system is connected to the suction side connection of the vacuum unit and wherein the filter system is arranged in an air flow direction between the nozzle and the vacuum unit.

The vacuum unit is suitably arranged in an area of an industrial plant that has a lower temperature than an area with hot dust and particles that are cleaned.

According to the present invention the vacuum unit is arranged outdoors, the pipe system extends into a building and the suction nozzle is arranged for sucking in hot dust and hot particles inside the building.

The vacuum unit including the air valve can be arranged outside the building to selectively admit the air outside the building into the duct in order to cool the air flow. Arranging the vacuum unit outside a building with a pipe extending through a wall of the building into hot areas, is beneficial compared to incorporating cooling equipment in the vacuum cleaning system. The air temperature outside the building can be utilized and in this way a vacuum cleaning system with a compressor suction pump dimensioned for normal room temperatures can be utilized also for cleaning hot material.

In an embodiment, the filter system comprises a pre-separator and a filter unit.

Description of drawings Fig. 1 is a side view of vacuum cleaning system; Fig. 2 is a perspective view of the vacuum cleaning system in fig. 1; Fig. 3 is a side view of a vacuum unit; Fig. 4 is a perspective view of the vacuum unit of fig. 3; Fig. 5 illustrates, schematically, details of a pump of the prior art, which shares design features with a first embodiment of a compressor suction of a vacuum unit of the invention; Fig. 6 illustrates an embodiment of a duct suitable for a vacuum unit in accordance with the invention; Fig. 7 illustrates a method of controlling a vacuum unit; Fig. 8 illustrates a method of controlling a vacuum cleaning system.

Detailed description Fig. 1 illustrates a vacuum cleaning system 1 for cleaning an industrial plant by sucking and transferring particles and dust, especially hot particles and hot dust, from for example a casting mold 2. The vacuum cleaning system comprises a vacuum unit 11, a filtering system 12, a pipe system 13a-e that includes a flexible steel hose 13d, and a movable end section 13e provided with a suction nozzle 14. The end section 13e is maneuvered by an industrial robot 20 in order to remove hot particles and dust from the mold 2 by sucking in and transferring the dust and particles through the pipe system, sections 13d, 13c, to the filtering system 12. The pipe system 13a-e connects the vacuum unit 11 to the nozzle 14 via the filtering system 12, in order to provide a vacuum suction at the nozzle 14 and provides a direction of the flow of air from the nozzle 14 through the filtering system 12 and further to the vacuum unit 11.

The filtering system 12 comprises a pre-separator 12a and a filter unit 12b. A respective container or bag 16a, 16b is arranged below the pre-separator 12a and the filter unit 12b to collect dust and particles from each respective unit 12a, 12b.

The pipe system 13a-e comprises a first section, or end section, 13e provided with the nozzle 14, a maneuverable steel hose 13d and a second pipe section 13c arranged from the steel hose 13d 14 to the filtering system 12. A third pipe section 13b is arranged between the pre-separator 12a and the filter unit 12b.

A fourth pipe section 13a, exemplified as two individual pipes, connects the filtering unit 12b of the filtering system 12 to the vacuum unit 11.

The components in the interior of the vacuum unit 11 are illustrated in more detail in figs. 3-4.

The vacuum unit 1 1 comprises a compressor suction pump 30, which is driven by an electric motor 31. The vacuum unit 1 1 comprises a temperature sensor, the outlet temperature sensor 33, arranged at the outlet (50 in fig. 5) of the compressor suction pump 30, and a temperature sensor, or inlet temperature sensor 32, arranged at the inlet (40 in fig. 5) of the compressor suction pump 30. The temperature sensors 32, 33 are arranged inside the inlet and outlet, respectively, and arranged to sense the temperature of the incoming and outgoing air stream, respectively. The vacuum unit 11 has two pipe connections 35, or alternatively only one pipe connection, for connecting the inlet of the compressor suction pump 30 to the pipe system 13. The vacuum unit 1 1 also comprises an air valve 36 for selectively admitting surrounding air to the inlet (40 in fig. 5) of the compressor suction pump 30. The vacuum unit 1 1 comprises a control unit 34 configured to control the air valve 36 based on the temperature at the outlet (50 in fig. 5) of the compressor suction pump 30, as measured by the outlet temperature sensor 33.

An air filter 39 is arranged to filter the air flow entering at the pipe connections 35 and the air valve 36 before the air flow reaches the inlet (40 in fig. 5) of the compressor suction pump 30. The air filter 39 is arranged in a compartment of the vacuum unit 11, which compartment forms an air duct 38 (see 38 in fig. 6), which air duct extends between the air valve 36, the pipe connection 35 and the inlet 40 of the compressor suction pump 30.

As illustrated in fig. 4, the vacuum unit 1 preferably also comprises safety valves, or vacuum release valves 37, which are spring-loaded in order to open if the vacuum (or under pressure) in the vacuum unit 11, becomes too low. The vacuum release valves 37 can suitably be configured in dependence of the maximum vacuum level of the compressor suction pump 30 to open at for example 50% to 90% vacuum in order to let surrounding air into the vacuum unit 11. The vacuum release valves 37 are also arranged at the air duct 38 compartment.

Fig. 4 also illustrates a pipe connection 51 for releasing outlet air from the vacuum unit 30. The outlet (50 in fig. 5) of the compressor suction pump 30 feeds the outlet air into a container beneath the floor of the vacuum unit 11, and the pipe connection 51 is arranged in the floor to convey the ejected air away from the vacuum unit 1 1 through the floor, for example by means of a pipe (not shown) connected to the pipe connection 51 and acting as a chimney.

Fig. 5 illustrates an example of a compressor suction pump 30, a so called Roots pump, which is provided with an inlet 40 for sucking in air and an outlet 50 for ejecting air. The illustrated roots pump also comprises intermediate inlets 60a-b for drawing in air in order to cool the pump, which intermediate inlets are arranged between the inlet 40 and the outlet 50 in the air flow direction. The compressor suction pump 30, exemplified as a Roots pump, comprises two counter rotating lobes 70a-b to compress the air. The configuration of the Roots pump is suitable for performing the invention. However, the compressor suction pump used may, but need not, be provided with the intermediate inlets 60a, 60b as illustrated in fig. 5. Thus a Roots-pump that have an inlet 40 and an outlet 50, but no intermediate inlets can be selected as a compressor suction pump 30 in accordance with the invention.

An alternative to a Roots pump is to use a screw compressor as a compressor suction pump 30, which screw compressor can be similar to the screw compressor of the previously cited document '551 (US 2004/0258551 A1), which, however, can be used without the cooler described in '551.

The control unit 34 is configured to open the air valve 36, in order to let surrounding air enter and blend with the air stream received from the pipe system 13, when the temperature at the outlet 50 reaches a first temperature threshold, which first temperature threshold is slightly below a maximum allowed temperature. The control unit 34 is further configured to close the air valve 36 when the temperature at the outlet 50 falls to a second temperature threshold below the first temperature threshold. Opening the air valve 36 decreases the vacuum (i.e. the pressure level below atmospheric pressure) provided by the vacuum unit 11, but ensures the air flow from the vacuum unit 11 does not become overheated. The air valve 36 is arranged to admit air surrounding into the vacuum unit 11, which air should be at atmospheric pressure. The vacuum unit 11, including the air valve 36, can be arranged outside an industrial building inside which heated materials are handled, wherein the pipe system 13 may be arranged to extend through a wall of the building.

As an example the compressor suction pump 30 may have a maximum allowed temperature of 150 degrees Centigrade at the outlet, and the control unit 34 may be configured to open the air valve 36 in order to cool the inlet air stream when the outlet air stream reaches 140 degrees Centigrade. The control unit 34 may be configured to close the air valve 36 when the air temperature at the outlet falls below a second temperature threshold of 125 degrees Centigrade. The control unit 34 may also be configured to stop the compressor suction pump 30 by switching off the electric power (not illustrated) that is fed to the electric motor 31 when the air temperature at the outlet 50 reaches the maximum allowed temperature of 150 degrees Centigrade.

Thus, the control unit 30 selectively opens and closes the air valve 36 so that the temperature of the outlet 50 is kept below the maximum temperature and controls the temperature by regulating the air flow when the outlet temperature is within a range from 125 to 140 degrees Centigrade when cleaning hot areas in for example a metal working plant, iron works plant, or aluminum smelting plant.

The air valve 36 is an electronically controlled air valve, and can preferably constitute an electronically controlled sliding valve.

Fig. 6 illustrates a vacuum unit 11 comprising a compressor suction pump 30 having an inlet 40 and an outlet 50. A duct 38 comprising a connection 35 for a pipe system 13 , is connected to the inlet 40 of the compressor suction pump 30. An air valve 36, in the form of a sliding valve 36, is arranged at the duct 38. Fig. 6 is simplified in order to illustrate main features of the invention in a detailed embodiment. The compressor suction pump 30 creates a first air stream through the duct 38 entering through the pipe connection 35. The first air stream is compressed by the compressor suction pump 30 and exits through the outlet 50. The vacuum unit 1 1 may be provided with an air filter (39 in fig. 3 but not illustrated in fig. 6) arranged in the duct 38. The temperature of the first air stream rises during the compression, and the control unit 34 is configured to selectively admit a second air stream to enter through the air inlet valve 36 in order to lower the temperature of the incoming first air stream.

The control unit 34 may be configured to provide a step wise opening of the air valve 36, and provide a successive opening of the air valve 36 within a temperature range, for example between 130-140 degrees Centigrade. Thus, regulating the opening of the air valve from a closed position at 130 degrees to a fully open position at 140 degrees.

An embodiment of a method, which is not part of the present invention, for controlling a vacuum unit 1 1 of a vacuum cleaning system 1 is illustrated in figure 7.

The method includes creating 102 a first air stream for sucking in and transferring dust and particles.

The method includes measuring 104 the temperature of the air flow at the vacuum unit 11, especially the temperature at the outlet 50 of the compressor suction pump 30.

The temperature is measured 104 during the cleaning in order to detect an overheated air flow.

The method further includes controlling 106 the air valve 36, by selectively opening 106A and closing 106B the air valve 36 in response to the temperature, i.e. preferably the temperature of the outgoing air stream as sensed by the outlet temperature sensor 33.

The opening 106A includes opening the air valve 36 to the air surrounding the vacuum unit 11, wherein a second air stream is provided in the duct 38 in order to cool the first air stream, which second air stream blends with the first air stream and the blended air stream enters at the inlet 40 of the vacuum unit 11. The closing 106B includes closing the air valve 36 when the temperature has decreased to a safe level, wherein the full suction power is provided to the pipe system of the vacuum cleaning system.

A detailed embodiment of a method for controlling a vacuum cleaning system 1 is illustrated in figure 8.

The method of controlling a vacuum cleaning system starts with creating 102 an air stream by starting the compressor suction pump 30 of the vacuum unit 1 1, in order to create a vacuum suction, especially in the pipe system 13 connected to the vacuum unit 11. The end section 13e of the pipe system 13 is maneuvered towards dust and particles to be cleaned, e.g. by means of an industrial robot 20. The starting of the compressor suction pump and the maneuvering of the nozzle 14 at the end section 13e creates 102 a first air stream for sucking in and transferring the dust and particles, which first air stream extends from the nozzle 14 to the vacuum unit 11.

The method further includes cleaning 103 including sucking 103A in the dust and particles, especially hot dust and particles, by means of the nozzle 14, and transferring 103B the dust and particles through the pipe system 13, in order to filter out 103C the dust and particles by means of the filtering system 12.

The dust and particles are filtered 103C out by means of the filtering system 12 arranged in the air flow direction of the first air stream between the nozzle 14 and the vacuum unit 1 1.

The first air stream arrives at the inlet 40, where the first air stream is compressed by means of the compressor suction pump 30, wherein the temperature of the air flowing through vacuum unit 11 is raised.

The method further comprises measuring 104 the temperature of the air at the vacuum unit 11. The measuring 104 preferably includes measuring the temperature of the air flow at the outlet 50. The measuring 104 may include both measuring the temperature at the inlet 40 and the temperature at the outlet 50.

The method further includes controlling the air valve 36 including selectively opening 106A and selectively closing 106B the air valve 36 in response to the temperature, wherein opening 106A of the air valve provides a second air stream into the duct 38. The second air stream blends with the first air stream at the inlet 40 of the vacuum unit 11 so as to cool the first air stream, and thereby lower the temperature at the outlet 50.

The controlling 106 of the air valve 36 includes selectively closing 106B the air valve 36 in response to the temperature, especially the outlet air temperature. When the temperature reaches a first threshold, the air valve 36 is opened 106A and when the air temperature falls to a second threshold, the air valve 36 is closed 106B.

The method may include stopping 108 the compressor suction pump 30, by turning off the electric motor 31 , based on the temperature, especially stopping 108 the compressor suction pump 30 if the temperature reaches a predefined maximum temperature. The first threshold is set lower than the allowed maximum temperature, and the second threshold is set lower than the first threshold.

The selective opening and closing 106 of the air valve 36 can also include a partial opening and a partial closing, respectively, of the air valve 36 performed at respective third and fourth thresholds. Thus, a third threshold for partial opening is set lower than the first threshold for full opening, and a fourth threshold for partial closing is set higher than the second threshold for fully closing the air valve. The third and fourth thresholds may be set to the same temperature, the air valve 36 will then be partially opened when the temperature level rises above the third threshold and if the air valve 36 subsequently is fully opened, the air valve 36 will be partially closed when the temperature falls below the forth threshold at the same temperature level as the temperature for partial opening.

Examples of a vacuum unit 1 1, a vacuum cleaning system 1 and methods of controlling a vacuum unit 11 and a cleaning system has been presented, which are especially adapted for cleaning of hot dust and particles. The vacuum unit 11 comprises a compressor suction pump 30, an air valve 36 arranged at the inlet 40 of the compressor suction pump 30, at least one temperature sensor 32, 33 for sensing the temperature of air flowing through the compressor suction pump 30. A control unit 34 is configured to selectively open the air valve 36 in response to the temperature, wherein surrounding air is admitted into the inlet. The vacuum cleaning system 1 comprises the vacuum unit 11, a filtering system 12, and a pipe system 13 provided with a suction nozzle 14. The method includes creating 102 a first air stream, transferring dust and particles by means of the first air stream through the pipe system, measuring 104 the temperature of the air at the vacuum unit 11, and selectively opening 106 the air valve 36 in response to the temperature, so as to cool the first air stream.

These examples have been provided to fascilitate enabling the invention. The invention is however not limited to the illustrated examples, but may be varied within the scope of the following claims.

Claims

1. A vacuum cleaning system (1) for sucking and transferring hot dust and hot particles, which vacuum cleaning system (1) comprises - a vacuum unit (1 1) comprising: - a compressor suction pump (30) having an inlet (40) and an outlet (50), - a duct (38) comprising a connection (35) for a pipe system (13) of the cleaning system (1), which duct (38) is arranged at the inlet (40) and configured to provide an air flow path from the pipe system (13) to the inlet (40); - an air valve (36) arranged at the duct (38) between the inlet (40) and the connection (35), which air valve (36) is arranged to selectively admit air into the duct (38); - a control unit (34) operatively connected to the air valve (36) and configured to control the air valve (36), and - at least one temperature sensor (32, 33) for sensing the temperature of air flowing through the compressor suction pump (30) and which temperature sensor (32, 33) is connected to the control unit (34), wherein the control unit (34) is configured to selectively open the air valve (36) in response to the temperature sensed by the at least one temperature sensor (32, 33), and that the vacuum cleaning system (1) further comprises - a filtering system (12), and that - the pipe system (13) is provided with a suction nozzle (14), wherein the pipe system (13) is connected to a suction side connection (35) of the duct (38) of the vacuum unit (11) and wherein the filter system (12) is arranged in an air flow path between the suction nozzle (14) and the vacuum unit (11), and wherein the vacuum unit (11) is arranged outdoors, the pipe system extends into a building and the suction nozzle (14) is arranged for sucking in hot dust and hot particles inside the building.

2. The vacuum cleaning system (1) according to claim 1, wherein the filtering system (12) comprises a pre-separator (12a) and a filter unit (12b).

3. The vacuum cleaning system (1) of claim 1 or 2, wherein at least one of the at least one temperature sensor (32, 33) is configured to measure the temperature of the air flowing through the outlet (50) of the compressor suction pump (30), wherein the control unit (34) is configured to open the air valve (36) based on the temperature of the air flow at the outlet (51) .

4. The vacuum cleaning system (1) according to any of claims 1-3, wherein the control unit (34) is configured to open the air valve (36) in response to the temperature exceeding a first threshold.

5. The vacuum cleaning system (1) according to claim 4, wherein the control unit (34) is configured to close the air valve (36) in response to the temperature falling below a second threshold, which second threshold is lower than the first threshold.

6. The vacuum cleaning system (1) according to any of claims 1 to 5, wherein the compressor suction pump (30) is selected from any of: - a rotary lobe compressor, - a screw compressor, and - a displacement blower.

7. The vacuum cleaning system (1) according to claim 6, wherein the compressor suction pump (30) is a rotary lobe compressor.

8. The vacuum cleaning system (1) according to any of claims 1 to 7, wherein at least one of the at least one temperature sensor (32, 33) is configured to measure the temperature of the air flowing through the inlet (40) of the compressor suction pump (30), wherein the control unit (34) is configured to open the air valve (36) in response to the temperature at the inlet (40) exceeding a third threshold.

9. The vacuum cleaning system (1) according to claim 8, wherein the control unit (34) is configured to close the air valve (36) in response to the temperature at the inlet falling below a fourth threshold, which fourth threshold is lower than the third threshold.

10. The vacuum cleaning system (1) according to any of claims 1 to 9, wherein the control unit (34) is configured to stop the suction pump (30) when the temperature reaches a maximum allowed temperature threshold.

11. The vacuum cleaning system (1) according to any of claims 1 to 10, wherein the vacuum unit (11) comprises at least one vacuum release valve (37).