WO2017085183A1

WO2017085183A1 - Condensation particle counter comprising a filling level sensor element

Info

Publication number: WO2017085183A1
Application number: PCT/EP2016/077999
Authority: WO
Inventors: Christos Berger; Martin Augustin; Martin CRESNOVERH; Christian HÜTTER
Original assignee: Avl List Gmbh
Priority date: 2015-11-17
Filing date: 2016-11-17
Publication date: 2017-05-26
Also published as: DE112016005272A5; AT517950B1; AT517950A4

Abstract

The invention relates to a condensation particle counter (1) comprising a saturation section (S) with which at least one inlet (2), which is arranged in an inlet section (E), for a flow of an aerosol, which flow is laden with particles, is associated, wherein a condensation section (K), a measuring section (M) for condensation particles and also an outlet section (A) are arranged downstream (110) of the saturation section (S), and a critical nozzle (30) is situated in the outlet section, an outlet line (4) leading from said nozzle to a pump (3) for removing the aerosol by suction, wherein the saturation section (S) has at least one saturation body (10) with at least one flow path (9, 20) for the particle-laden aerosol to flow through. In this case, at least one filling level sensor element (81, 82) is arranged in a region of the saturation section (S) which faces the inlet section (E). This arrangement of the filling level measurement allows operation with a higher tilting angle than before, even in the inclined state.

Description

DESCRIPTION

Condensation particle counter with level sensor element

The invention relates to a condensation particle counter with a saturation section, which is assigned at least one inlet for a particle-laden stream of an aerosol, wherein the saturation section downstream of a condensation section, a measuring section for condensation particles and an outlet section and downstream in the outlet section of a critical nozzle from which an outlet line leads to a pump for aspirating the aerosol, wherein the saturation section has at least one saturation body with at least one flow path for the passage of the particle-laden aerosol.

Condensation particle counters are optical measuring devices for detecting small solid particles with dimensions, for example in the nm range, with which a carrier gas, e.g. Air, engine exhaust etc. is loaded. This carrier gas with the particles is referred to below with the relevant technical term aerosol.

Condensation particle counters are used for example in clean room technology or for measuring exhaust gas flows.

Solid particles in the nm range are too small to be detected directly by optical means. In order to be able to measure such solid particles, condensation nucleus counters are used in which the aerosol, eg an exhaust gas, is sent through a supersaturated atmosphere. The supersaturated atmosphere is generated, for example, in which the exhaust gas is saturated with vapors of a resource and then cooled. The solid particles then serve as condensation nuclei and they are formed by heterogeneous condensation enlarged so far that they can be optically detected. The size of the solid particles from which this condensation process takes place depends on the supersaturation and is referred to as Kelvin diameter. The smaller the Kelvin diameter for a given supersaturation, the smaller can be the solid particles that result in condensation of equipment. According to specifications, eg legal requirements, the particle size range of greater than 20 nm, typically 23 nm, to 2.5 μιτι to detect and condition the exhaust gas to a temperature of <35 ° C prior to the actual measurement, for example, for exhaust gases from motor vehicles. Due to the condensation, the size of the particles increases, for example to about 5 pm. Particles of such size can be optically detected individually, eg with optical particle counters based on scattered light.

A condensation particle counter basically consists of a saturation unit, a condensation unit and a measuring cell, as described in detail below. For example, EP 0 462 413 B, which shows a saturation unit with a cylindrical body of porous material, followed by a condensation unit and a measuring cell at a right angle, should be mentioned in the relevant state of the art. In this case, the operating fluid is provided in a cavity of the saturation unit. Losses of the operating fluid during the measuring operation are permanently compensated by external supply.

EP 2 194 370 A1 shows geometrically a similarly constructed device in which the saturation unit has a special shut-off device in order to prevent the penetration of equipment into the measuring cell.

WO 2012/142297 A1 shows an example of a saturation unit for a condensation particle counter, in which a porous body of interspersed with several channels through which the aerosol can flow.

Finally, US 2013/0180321 A1 discloses a condensation particle counter of the subject type, wherein a porous body has at its periphery a number of recesses in order to counteract undesirable capillary action between the outer wall and the porous body.

The actual measuring cell downstream of a pump for sucking the aerosol downstream, often between the measuring cell and the pump is a critical nozzle in the flow path, as shown for example, the already mentioned EP 2,194,370 AI.

Conventional Kondensationspartikelzähler be filled from external reservoirs with resources. In this case, usually located in the resource supply line or in the reservoir, a level sensor that supplies depending on the measurement resource or prevents the supply line to prevent flooding of the Kondensationspartikelzählers or gas path and optics. The disadvantage of this is in particular that due to the arrangement of the level sensor malfunction occurs when the condensation particle counter is tilted - depending on the direction of inclination can lead to an oversupply (if the level sensor is flooded by the resource) or desiccation of the saturation unit (if the level sensor due to the inclination protrudes from the equipment). Therefore, condensation particle counters according to the prior art can only be operated at very low inclinations, for example 2 °, which makes mobile applications in particular impossible. An object of the invention is to counteract this problem in the simplest and most reliable way possible.

This object is achieved with a condensation particle counter of the type mentioned in the present invention, at least one level sensor element is arranged in an area of the saturation portion facing the inlet portion.

Thanks to the invention, it is possible to use the condensation particle counter at much greater inclinations and thus also in the mobile area, since the level sensor element is disposed within the condensation particle counter and thus tolerates larger tilt angle. The risk of flooding the gas path or the optics or drying of the saturation section is considerably reduced. This will not cause damage or possibly a failure of the meter, maintenance can be reduced. As a level sensor element, any sensor can be used - even a sensor element that only detects the exceeding of a certain filling level, without being able to make statements about the absolute height is sufficient.

In one variant of the invention, the filling level sensor element is arranged within the outside diameter of the at least one saturation body, preferably in the centroid of its base area. This achieves a particularly reliable function. Conveniently, the level sensor element is arranged in the longitudinal axis of the saturation body.

The inventive solution is applicable to any embodiments of the saturation body. According to a first variant, the saturation body is a hollow cylinder whose cylindrical interior forms the flow path for the flow of the particle-laden aerosol, wherein the level sensor element is disposed within an inner surface of the hollow cylinder.

In a second variant, the saturation body is a hollow cylinder with an inner cylinder arranged concentrically therewith, wherein the inner cylinder is listed either solid or with an inner bore and a gap between the two cylinders for the flow of the particle-laden aerosol, wherein at least one level sensor element at least one the following positions: Between an inner surface of the hollow cylinder and an outer surface of the inner cylinder or within the inner bore of the inner cylinder. This means that in this case also several fill level sensor elements can be provided at different positions. In this case, the axial extent in the direction of the longitudinal axis of the inner cylinder is favorably greater than the axial extent of the hollow cylinder, wherein the inner cylinder preferably extends further into the inlet portion than the hollow cylinder. The inner cylinder can extend to the bottom of the inlet portion, while the hollow cylinder has some distance to it. This makes it possible to reduce the overall height of the condensation particle counter, because there is space between the hollow cylinder and inlet section for the supply line and other units.

In a third variant, the saturation section has at least one saturation body with at least two holes passing through it for the passage of the particle-laden aerosol.

In a variant suitable for all embodiments described above, an operating trough is formed in the inlet section and the at least one filling level sensor element is in the operating trough, preferably in the direction of flow in the direction of the measuring section parallel to the longitudinal axis of the saturation body, extending, arranged. This allows the level sensor element to be easily positioned in the vicinity of the equipment.

The invention together with further advantages is explained below with reference to a non-limiting embodiment, which is illustrated in the drawings. In this show

1 is a schematic simplified section through a formed according to the invention condensation particle counter,

2 is a perspective view of a first variant of a saturation body,

3 shows a section through a further variant of a saturation body,

4 is a section along the plane VI-VI of Fig. 1,

5 shows a section along the plane VIII-VIII of Fig. 1,

6 is a section along the plane VII-VII of Fig. 1,

7 is a sectional view of a transfer section for the transition from an annular gap to individual channels,

Fig. 8 shows a detail of the sectional view of Fig. 1, and

9 is a perspective view of a second variant of a saturation body.

With reference to FIG. 1, an embodiment of the invention will be described with reference to a simplified schematic illustration Invention trained condensation particle counter 1 described. A particle-laden aerosol, which originates for example from the exhaust gases of an internal combustion engine, passes via an inlet 2, namely a line, into an inlet section E of the counter 1, from which it, here at its upper end, by means of a pump 3 via an outlet 4, namely, a line is sucked out of an outlet section A. Between the inlet section E and the outlet section A are a saturation section S, possibly an overfeed section U, an insulating section I - transfer section U and insulating section I can also be combined into one component - a condensation section K and a measuring section M. All these sections with possible variants and their function will be described in detail below.

The inlet section E has the function of ensuring a desired flow behavior, generally a laminar flow, in the direction downstream of the flow direction 110 of the aerosol downstream saturation portion S and the subsequent condensation section K. However, the detailed design of the here schematically outlined inlet section E is not the subject of the invention.

As can also be seen from FIG. 2, in the saturation section S z. B. a two-part saturation body 10, according to the illustrated embodiment, a hollow cylinder 5 with a with respect to a longitudinal axis 100 of the saturation body 10 concentrically arranged inner cylinder 6, the latter is also formed here as a hollow cylinder with an inner bore 7. The latter can, for example, accommodate a mechanically stabilizing and / or thermally conductive mandrel 8 (see FIG. 2) for adjusting the temperature. Between both cylinders 5 and 6 is a gap 9 with annular cross-section for the flow of the particle-laden Aerosols in the flow direction 110, which is indicated in Fig. 1 by arrows left.

As the material for the two cylinders 5, 6, which here form a two-part saturation body 10, an absorbent, porous material, for example a sintered plastic, a wick material od. Like. Used; however, in the embodiment shown, at least a portion 5n (see Fig. 2), here a sector of the hollow cylinder 5, is made of non-porous material, e.g. made of aluminum or a plastic, wherein the remaining portion 5p is made of porous material. If the porous material is not self-supporting, not shown, e.g. net-like holding structures are used. The section 5n shown in FIG. 2 has a partial cross-sectional area 51 and a material thickness with a radial partial length 131. The section 5p has a partial cross-sectional area 52 and also a material thickness with a radial partial length 131. The inner cylinder 6 has a material thickness with a radial partial length 132.

A stored in a container 11 resources 12, such as water, an alkane or an alcohol or other suitable medium is fed via a line assembly 13 to the saturation body 10, wherein within the particle counter 1 condensed resource, for example via a line 14, a resource pump 15th and a filter 16 may be returned to the container 11 or simply discharged (not shown). At most, for metering or flow control of the equipment 12 required metering devices or valves in the lines 13, 14 are not shown for the sake of clarity. Only indicated, as known to those skilled in the art, are a heating unit 17 for the saturation section S, for example a heating jacket, and a tempering / cooling unit 18 for the condensation section K.

It is further known that condensation particle counters with external equipment containers may experience problems with resource delivery due to pressure fluctuations between the pressure in the aerosol inlet or in the exhaust gas inlet to the condensation particle counter and the internal pressure in the equipment tank. Such pressure fluctuations can occur, for example, when the aerosol inlet is clogged. This can lead to unwanted disturbances of the measuring operation such as flooding of the flow path of the aerosol up to the flooding of the measuring section M with resources. Likewise, there may be an undesirable drying out of the saturation body due to disturbances in the supply of equipment.

In order to prevent the aforementioned malfunctions and to ensure a permanent pressure equalization between the aerosol inlet 2 and the resource container 11, in the illustrated in Fig. 1 embodiment of the condensation particle counter 1, a pressure equalization line 150 between the tubular inlet 2 and the container 11 is outlined. Advantageously, the pressure equalization line 150 serves to equalize pressure differences between the aerosol inlet 2 and the resource container 11. Alternatively or in addition to this, in FIG. 1, a further pressure equalization line 151 is shown by dashed lines, which extends directly from the container 11 into the saturation body 10 and serves to equalize the pressure between the equipment container 11 and the saturation section S. Likewise, one or more further pressure compensation lines, which are not shown here, may be arranged between the container 11 and the condensation section K if necessary. The supersaturated aerosol present in the saturation section S heated to a predetermined temperature flows through the condensation section K cooled to a likewise predetermined temperature, where the operating medium condenses on the particles present in the aerosol and thus leads to the desired particle enlargement. The counting efficiency, ie the number of detected particles of a certain size is small for very small particles, then increases very rapidly, for example in the range of 15 to 35 nm, for example at 50 to 50, and for larger particles , typically from 40 nm, at values of over 90%. It should also be noted that the temperature difference between the saturation section and the condensation section influences the particle size and the growth, respectively, the smaller the larger the temperature difference is, and the smaller the particles are detected.

The solution with sections of the saturation body 10 also made of nonporous material causes an inhomogeneity of the gas saturation and allows an influence of the measured particle sizes in the direction of larger particles. This solution flattens the wake-up characteristic or the counting efficiency curve of the overall system and makes it easier to compensate for manufacturing tolerances or the fulfillment of legal requirements which determine which Kelvin diameter is to be measured.

FIG. 3 shows that a sector-shaped portion 6n of the inner cylinder 6 with a partial cross-sectional area 61 may consist of non-porous material, the remainder of the inner cylinder being a section 6p of porous material with a partial cross-sectional area 62. It should be noted at this point that the inner cylinder 6, which here extends in the radial direction 130 with a partial length 132, does not necessarily have one Inner bore 7 must have, but can also be designed as a full cylinder.

The illustration according to FIG. 9 shows a cylindrical saturable body 19, which possesses these passing through bores 20 for the flow of the particle-laden aerosol, thus being designed differently than the saturation body shown in FIG. 1 and in its geometry, for example, the embodiment according to WO mentioned above 2012/142297 AI corresponds. A segment-shaped portion 19n having a partial cross-sectional area 191, for example containing two holes 20, is here made of non-porous material, e.g. aluminum, while the remainder of the saturable body 19 is a porous material portion 19p having a partial cross-sectional area 192. Embodiments are also possible in which the saturable body consists entirely of a porous material, but the flow path of at least one of the bores is limited at least over part of its length by a non-porous material, for example by a metal sleeve.

Referring back to Fig. 1 and taking Beise of Figs. 4, 5 and 6 and Fig. 7 recognizes the formation of the Überführabschnittes U, which has the task, the flow from the annular gap 9 as laminar as possible in a number of downstream Transfer individual channels. For this purpose, in the embodiment shown, a ring insert 21 is provided, which on its underside, which forms the inlet side 200 of Überführabschnitts U or the ring insert 21 in mounting position in continuation of the annular gap 9 an opening 22 again in the form of an annular gap, wherein of the Top of the ring insert, which consists for example of aluminum, a number of individual channels 23, here nine individual channels 23 (in Fig. 7, five of which are seen), open into the annular gap-shaped opening 22. The top of the shown here in Fig. 7 Ring insert 21 forms in the installed position the outlet side 210 of Überführabschnitts U. The Überführabschnitt U and its annular insert 21 are in a preferred embodiment in an expedient manner with the saturable portion S in thermally conductive connection to prevent unwanted premature condensation in this area.

What is essential is a transition from the annular gap-shaped opening 22 in the individual channels 23 as continuously as possible to the flow of the aerosol without turbulence laminar continue in individual channels 24i of the insulating section I or its continuation, namely individual channels 24 _{K of} the condensation section K. , respectively. In this section, the individual channels 24 _{K are formed} in a condensation insert 25, in the upper region of which they are brought together again to form a single channel 26, which then opens into a separating nozzle 27, which is located in front of or in the measuring section M. It can be seen from the sections of FIGS. 4, 5 and 6 that the annular gap 9 of the saturation section S (FIG. 4) merges into individual channels 23 further up in the insulating section I (FIG. Still further above, in the region of the condensation section K, these individual channels are already closer together (FIG. 5), in order to then pass into the single single channel 26 just before the nozzle 27.

The provided in this embodiment, but not necessarily required insulating section I with the individual channels 24i provides for a thermal separation of the saturation portion S of the condensation section K.

In the measuring section M, the actual counting of the particles enlarged by condensation, which emerge from the separating nozzle 27 with the aerosol stream, takes place. In a known manner, a light unit 28 is provided for this purpose, for example a focused laser light source whose Light beam hits emerging from the nozzle 27 particles. The resulting scattered light is detected by a photodetector 29 and the resulting signals are forwarded to an evaluation unit, not shown. Other measuring methods can also be used here.

The aerosol with the particles passes after the measuring section into the outlet section A, which according to the invention has a special design which is intended to prevent clogging of a critical nozzle 30 arranged at the outlet of the counter 1. This critical nozzle 30 is used in a known manner to set a constant volume flow and has a small diameter, typically 0.3 mm, with the risk that in the course of operation, the outflowing particles move this small opening and thus affect the accuracy or make the measurement impossible.

In order to counteract this disadvantage, an outlet line 31 from the measuring section M ends in the outlet section A in a narrowed region 32, which opens into a particle catching chamber 34 with a sharp swirling edge 33. The narrowed region 32 and additionally the swirling edge 33 lead to a swirling of the aerosol stream, which favors a deposition of particles, especially in the lower edge region 35 of the particle catching chamber, where (FIG. 1) deposited particles are indicated.

In order to effectively prevent unwanted disturbances of the measuring operation as described above, such as the flooding of the flow path of the aerosol up to the flooding of the measuring section M with operating means, which may occur due to pressure fluctuations due to, for example, clogging of the aerosol inlet 2, the following solution is provided: between the critical nozzle 30 - strictly speaking, between the outlet of the nozzle 30 facing away from the measuring section M - and the pump 3 At least one adjustable valve device 70 is provided. The valve device 70 can be adjusted as a function of a default value, in particular at negative pressure within the gas path between the inlet 2 and the critical nozzle 30 so that the outlet line is partially or completely closed in the region between the critical nozzle 30 and pump 3, whereby flooding can be prevented ,

Contrary to the prior art, the condensation particle counter 1 according to the invention is also an operation at high tilt angles possible - while conventional counters can only be operated to slopes of 2 ° or 10 ° maximum, in the solution described below, an inclination up to 38 ° is possible.

For this purpose, a level sensor element 81, 82 is arranged in a region of the saturation section S facing the inlet section E. The positioning may occur in a resource trough 80 of the inlet portion E from which the resource continues to rise into the saturation portion. The level sensor element 81, 82 then extends in the direction of flow 110 in the direction of the measuring section M, or parallel to the longitudinal axis 100 of the saturation body. This element detects the overshoot of a certain level and then inhibits the supply of additional resources to prevent flooding of the gas path or optics.

The filling level sensor element 81, 82 is arranged within the outer diameter of the saturable body, preferably in the centroid of its base, and thus compatible for high tilt angle. The saturation body may be cylindrical with an annular flow path 9 (see FIGS. 1, 2 and 8) as well as a solid saturation body 19 with diameter-setting bores 20 (see FIG. 9). Also, an embodiment of the saturable body as Hohlylinder 5, the cylindrical interior of the Flow path 9 forms for the flow of the aerosol is possible - the level sensor element 81, 82 is then disposed within the inner surface of the hollow cylinder 5.

FIGS. 1 and 8 show a first level sensor 81 positioned in the longitudinal axis 100 of the saturation body 5, 6, 10. This arrangement in the axis of symmetry allows a particularly wide tilting, because always a wetting of the saturation body is ensured. The saturation body 10 is, as described above, a hollow cylinder 5 with a concentrically arranged inner cylinder 6, between which a gap 9 for the flow of the particle-laden aerosol is left. The inner cylinder 6 can be executed either solid or with an inner bore 7. In addition to the position described at the beginning of the paragraph of a first level sensor 81, which is disposed within the inner bore 7 of the inner cylinder 6, additionally or instead, a second level sensor 82 may be positioned in the region between an inner surface of the hollow cylinder 5 and an outer surface of the inner cylinder 6 ,

It is also shown in FIG. 8 that an installation space optimization of the condensation particle counter 1 can be achieved. The axial extent of the inner cylinder 6 can be made larger than the axial extent of the hollow cylinder 5, wherein the inner cylinder 6 advantageously extends further into the inlet section E. As the hollow cylinder 5 in the area which is released by the different axial lengths, the inlet 2 and other components can be accommodated, the length of the condensation particle counter 1 is reduced. By axial extent is meant here the extension in the direction to or parallel to the longitudinal axis 100 of the inner cylinder 6.

Claims

PATENT APPLICATIONS

A condensation particle counter (1) having a saturation portion (S) to which is associated at least one inlet (2) for a particle-laden stream of an aerosol, wherein the saturation portion (S) downstream of (110) is a condensation section (K), a measurement section (M) for condensation particles and an outlet section (A) are arranged downstream and in the outlet section a critical nozzle (30), from which an outlet line (4) leads to a pump (3) for sucking the aerosol, the saturation section (S) has at least one saturation body (10) with at least one flow path (9, 20) for the flow of the particle-laden aerosol,

characterized in that

at least one level sensor element (81, 82) is arranged in a region of the saturation section (S) facing the inlet section (E).

2. Condensation particle counter (1) according to claim 1,

characterized in that

the fill level sensor element (81, 82) is arranged within the outer diameter of the at least one saturation body (10), preferably in the centroid of its base surface.

3. Condensation particle counter (1) according to claim 1 or 2,

characterized in that

the level sensor element (81, 82) is arranged in the longitudinal axis (100) of the saturation body (10).

4. Condensation particle counter (1) according to one of claims 1 to 3, characterized in that

the saturation body (10) is a hollow cylinder (5) whose cylindrical interior forms the flow path (9) for the flow of the particle-laden aerosol and the fill level sensor element (81, 81) is arranged within an inner surface of the hollow cylinder (5).

5. condensation particle counter (1) according to one of claims 1 to 3, characterized in that

the saturation body (10) is a hollow cylinder (5) with an inner cylinder (6) arranged concentrically therewith, the inner cylinder (6) being either solid or with an inner bore (7) and a gap (9) between the two cylinders At least one level sensor element (81, 82) is arranged at at least one of the following positions: Between an inner surface of the hollow cylinder (5) and an outer surface of the inner cylinder (6) or within the inner bore (7) of the inner cylinder (6).

6. condensation particle counter (1) according to claim 5,

characterized in that

the axial extent in the direction of the longitudinal axis (100) of the inner cylinder (6) is greater than the axial extent of the hollow cylinder (5), wherein the inner cylinder (6) preferably extends further into the inlet portion (E) than the hollow cylinder (5) ,

7. condensation particle counter (1) according to one of claims 1 to 3, characterized in that

the saturation section (S) has at least one saturation body (19) with at least two boreholes (20) passing through it for the passage of the particle-laden aerosol.

8. Condensation particle counter (1) according to one of the preceding claims,

characterized in that

in the inlet section (E) a working medium trough (80) is formed and the at least one filling level sensor element (81, 82) in the operating trough (80), in the flow direction (110) in the direction of the measuring section (M), preferably parallel to the longitudinal axis (100) of the saturable body (10), extending.