Fluid sampling

Abstract

An arrangement for providing a fluid flow to a sensor, comprising a flow distributor plate (10) positioned in a flow channel, the flow distributor plate comprising a first surface (12a) and a second surface (12b) defining therebetween a fluid collection space (16); a plurality of holes (14) each forming a fluid flow channel through the flow distributor plate; and flow openings (18) in the side of each hole (14) of the plurality of holes configured to convey a part of the fluid flow in the hole (14) into the fluid collection space (16); the arrangement further comprising a sample flow guide (20) downstream of the second surface (12b) and configured to convey the fluid from the fluid collection space towards a sensor (90).

Description

[0001] FLUID SAMPLING

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to fluid sampling. The disclosure relates particularly, though not exclusively, to sampling of non-homogenous fluids. The disclosure relates particularly, though not exclusively, to sampling of a non-homogenous exhaust gas flow.

[0004] BACKGROUND

[0005] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0006] Sensors are used to measure quantities from fluid flows. For example a NOx sensor is used to measure nitrogen oxide concentration from an exhaust gas flow. Such sensors typically measure the concentration locally, i.e. from a relatively small area of the fluid flow, and accordingly in case of a non-homogenous fluid flow, the result might not always be representative of the overall flow composition.

[0007] The present disclosure aims to provide an arrangement providing the sensor with a fluid flow representative of the overall flow composition.

[0008] SUMMARY

[0009] The appended claims define the scope of protection. Any examples and technical descriptions of apparatuses, products and / or methods in the description and / or drawings not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention.

[0010] According to a first example aspect there is provided an arrangement for providing a fluid flow to a sensor, comprising a flow distributor plate positioned in a flow channel, the flow distributor plate comprising a first surface and a second surface defining therebetween a fluid collection space; a plurality of holes each forming a fluid flow channel through the flow distributor plate; and flow openings in the side of each hole of the plurality of holes configured to convey a part of the fluid flow in the hole into the fluid collection space; the arrangement further comprising a sample flow guide downstream of the second surface and configured to convey the fluid from the fluid collection space towards a sensor.

[0011] The sample flow guide may comprise a flow channel leading from the fluid collection space to or near the sensor.

[0012] The size and / or number of the flow openings in the side of the holes may increase with the distance of the hole from the sample flow guide increasing.

[0013] The sample flow guide may comprise a pipe leading from the centre-point of the flow distribution plate to the sensor.

[0014] The sample flow guide may comprise an opening between the first surface and the second surface leading from the fluid collection space to the sensor.

[0015] The flow distribution plate may be configured to convey a sample representative of the overall fluid flow to the sensor via the sample flow guide.

[0016] The size and / or number of the flow openings in the side of the holes may configured to convey to the sample flow guide a sample fluid comprising equal amount of fluid from each hole.

[0017] The fluid may comprise a non-homogenous gas.

[0018] According to a second example aspect there is provided an exhaust gas sampling and measurement system, comprising a first exhaust gas flow channel comprising an exhaust gas aftertreatment device; a flow distributor plate positioned in the first exhaust gas flow channel downstream of the exhaust gas aftertreatment device, the flow distributor plate comprising a first surface and a second surface defining therebetween an exhaust gas collection space; a plurality of holes each forming an exhaust gas flow channel through the flow distributor plate; and flow openings in the side of each hole of the plurality of holes configured to convey a part of the exhaust gas flow in the hole into the exhaust gas collection space; the system further comprising a second exhaust gas flow channel downstream of the flow distribution plate; a sensor positioned in the second exhaust gas flow channel; and a sample flow guide downstream of the second surface and configured to convey the fluid from the fluid collection space towards the sensor.

[0019] The sensor may comprise a NOx-sensor.

[0020] According to a second example aspect there is provided a method for providing a fluid flow to a sensor, comprising providing a flow distributor plate in a flow channel, the flow distributor plate comprising a first surface and a second surface defining therebetween a fluid collection space and a plurality of holes each forming a fluid flow channel through the flow distributor plate; the method further comprising convey a part of the fluid flow in each hole through flow openings in the side of each hole into the fluid collection space; and conveying the fluid from the fluid collection space towards a sensor via a sample flow guide downstream of the second surface.

[0021] Different non-binding example aspects and embodiments have been illustrated in the foregoing. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in different implementations. Some embodiments may be presented only with reference to certain example aspects. It should be appreciated that corresponding embodiments may apply to other example aspects as well.

[0022] BRIEF DESCRIPTION OF THE FIGURES

[0023] Some example embodiments will be described with reference to the accompanying figures, in which:

[0024] Fig. 1 schematically shows an example of an arrangement according to an example embodiment;

[0025] Fig. 2A shows a schematic view of a detail of an arrangement according to an example embodiment;

[0026] Fig. 2B shows a schematic view of a detail of an arrangement according to an example embodiment;

[0027] Fig. 3 shows a schematic view of a detail of an arrangement according to an example embodiment;

[0028] Fig. 4 shows a schematic view of an arrangement according to an example embodiment;

[0029] Fig. 5 shows a schematic view of an arrangement according to an example embodiment;

[0030] Fig. 6 shows a schematic view of an arrangement according to an example embodiment;

[0031] Fig. 7 shows a flow chart of a method according to an example embodiment; Fig. 8 schematically shows an example of an arrangement according to an example embodiment; and

[0032] Fig. 9 schematically shows an example of an arrangement according to an example embodiment;

[0033] DETAILED DESCRIPTION

[0034] In the following description, like reference signs denote like elements or steps.

[0035] Fig. 1 schematically shows an example of an arrangement according to an example embodiment applied in exhaust gas aftertreatment.

[0036] Fig. 1 shows a first exhaust gas flow channel 200 in which exhaust gas from an exhaust gas after treatment device 100, such as a selective catalyte reaction, SCR, device, flows.

[0037] The fluid flow, i.e. the exhaust gas flow, in the first flow channel 200 is non-homogenous, i.e. the concentration of various components of the gas varies within the flow. In an example embodiment, the NOx concentration is different on the sides of the flow channel and in the middle of the flow channel. The flow directions of the fluid flow have been schematically shown with dashed arrows in Fig. 1.

[0038] The fluid flow is conveyed from the first flow channel 200 to a second flow channel 300. A sensor 90 is positioned in the second flow channel 300. In an example embodiment, the sensor 90 comprises a NOx sensor for measuring nitrogen oxide concentration. In a further example embodiment, the sensor 90 comprises an ammonia sensor. The sensor is measuring locally, i.e. the sensor reading is representative of the quantity being measured at the area of the tip of the sensor. Accordingly, if the fluid flow on or around the sensor is not representative of the overall flow in case of a non-homogenous fluid, the result of the measurement could be biased.

[0039] In a further example embodiment, the arrangement comprises a particulate sampler instead of or in addition to the sensor 90.

[0040] The arrangement according to an example embodiment further comprises a flow distribution plate 10 positioned in the first flow channel 200. The flow distributor plate, as will be explained in more detail hereinafter, comprises an upstream, or first, surface 12a and a downstream, or second surface 12b. The flow distributor plate further comprises holes forming fluid flow channels through the plate configured to allow the flow in the first flow channel 200 to pass through the plate. The flow distribution plate 10 further comprises a fluid collection space 16 formed between the opposing surfaces of the flow distribution plate 10. Each hole through the flow distribution plate 10 comprises flow openings on the side of the hole configured to convey a part of the fluid flow through said hole to the fluid collection space 16 within the flow distribution plate 10.

[0041] The arrangement according to an example embodiment further comprises a sample flow guide 20 configured to convey the fluid from the fluid collection space 16 towards the sensor 90. In an example embodiment, the sample flow guide 20 comprises a pipe upstream of the flow distribution plate leading towards the sensor 90. In an example embodiment, the sample flow guide 20 ends before the sensor 90, extends up to the sensor 90 or extends beyond the sensor 90 so that the sensor 90 effectively resides inside the sample flow guide 20. In a further example embodiment, the sample flow guide is positioned in such a way that it forms a separate side flow channel outside of the first 200 and second 300 flow channel. In an example embodiment, the sample flow guide comprises a larger opening in the downstream surface 12b of the flow distribution plate configured to guide the fluid from the fluid collection space 16 towards the sensor 90.

[0042] Fig. 1 shows the upstream end of the sample flow guide 20 positioned at the centrepoint of the flow distribution plate 10. In further example embodiment, the sample flow guide 20 is positioned at a different position on the downstream side of the flow distribution plate 10.

[0043] In an example embodiment, the sample flow guide comprises a mixer element (not shown) at the upstream end thereof configured to mix the fluid flow entering the sample flow guide 20 from the fluid collection space in the flow distribution plate.

[0044] The flow openings on the sides of the holes of the flow distribution plate 10 are arranged in such a way that the fluid collected in the fluid collection space 16 is representative of the overall fluid composition. For that purpose, the flow openings are arranged in such a way that the fluid flow from each part of the flow channel experiences a similar flow resistance in reaching the sample flow guide 20. That is, the flow distribution plate 10 conveys a representative sample to the sample flow guide 20.

[0045] In an example embodiment, the sample flow guide 20 has a diameter of 10 to 50 mm, in an example embodiment about 30 mm. In an example embodiment, the second flow channel 300 has a diameter of 50 to 150 mm, in an example embodiment about 100 mm.

[0046] In an example embodiment, the pressure in the first flow channel 200 is higher and the flow speed lower than in the second flow channel 300.

[0047] In an example embodiment, the sensor 90 is positioned in the fluid collection space substantially on the same position as the upstream end of the sample flow guide 20. In an example position, the senor is positioned at the side of the first flow channel 200 in the space 16 and the sample flow guide 20 is configured accordingly to convey the fluid in the fluid collection space 16 towards or past the sensor and onwards.

[0048] In an example embodiment, the arrangement comprises more than one sensor and the sample flow guide 20 is configured to configured accordingly to convey the fluid in the fluid collection space 16 towards and / or past each sensor.

[0049] In an example embodiment, the flow distribution plate is not perpendicular to the flow in the flow channel in which it is placed. In a further example embodiment, the flow distribution plate 10 does not have a uniform thickness, i.e. the first and second surface thereof have a different distance from each other at different parts of the flow distribution plate. In such a situation the fluid collection space would have different heights at different parts of the plate 10 thus allowing different flow resistances.

[0050] While an example embodiment of Fig. 1 has been explained with reference to sampling and measuring an exhaust gas flow, the disclosure is equally applicable to sampling and measuring any fluid flow.

[0051] Figs. 2A and B show schematic views of a detail of an arrangement according to an example embodiment.

[0052] Fig. 2A shows a schematic view of the flow distribution plate 10. Fig. 2A shows the downstream surface 12b of the flow distribution plate. The flow distribution plate 10 comprises a plurality of holes 14 forming fluid flow channels through the plate 10 configured to allow a flow to pass through the plate. In an example embodiment, the holes 14 have a circular shape. The number and position of the plurality of holes 14 is in an embodiment chosen in accordance with the situation in such a way that the holes 14 allow a flow through the flow distribution plate without an excessive increase to the flow resistance. While the flow distribution plate 10 increases the flow resistance in the channel in which it is placed, the distribution and / or design of the holes is configured to minimize the increase.

[0053] Fig. 2B shows an enlarged view of the flow distribution plate. Fig. 2B shows the holes 14 with flow openings 18 on their sides. In an example embodiment, the number, alignment and / or size of the flow openings of a hole 14 depends on the distance of said hole 14 from the sample flow guide. In Fig. 2B the sample flow guide 20 would be positioned at the centrepoint of the flow distribution plate 10 and the holes 14 nearer to the centrepoint accordingly have fewer and / or smaller flow openings 18.

[0054] In an example embodiment, the number and / or size of the openings increases with the distance from the sample flow guide 20 increasing so that the fluid having the farthest route to the sample flow guide 20 has less flow resistance so that fluid from each hole 14 is conveyed to the sample flow guide 20 from the fluid collection space 16 substantially in equal proportions.

[0055] In an example embodiment, the holes 14 forming fluid flow channels through the plate 10 are formed by one of the downstream 12b or upstream 12b surface comprising holes having on their edges protrusions substantially cone shaped, i.e. tapering in a direction towards the other surface, and the other surface comprising holes configured to receive in a friction fitting manner the narrower end of the protrusion to form the flow channels and to hold the flow distribution plate together as well the distance between the upstream 12a and downstream 12b surface substantially constant.

[0056] Fig. 3 shows a schematic view of a detail of an arrangement according to an example embodiment.

[0057] Fig. 3 shows an enlarged cross-sectional side view of the flow distribution plate 10. The flow distribution plate 10 comprises a first surface 12a at the upstream side thereof and a second surface 12b at the downstream side thereof. The flow distribution plate 10 comprises holes 14 allowing a fluid flow through the flow distribution plate 10. The holes 14 comprise on their side flow openings 18 conveying a part of the fluid flow through the holes into the fluid collection space 16 between the first 12a and second 12b surface.

[0058] Fig. 3 shows the sample flow guide 20 downstream of the second surface 12b. In an example embodiment, the sample flow guide 20 comprises a pipe curving towards a sensor (not shown) and conveying the fluid from the fluid collection space towards the sensor.

[0059] Figs. 4 to 6 show schematic views of an arrangement according to example embodiments.

[0060] Fig. 4 shows an example embodiment akin to the example embodiment of Fig. 1. In the example embodiment of Fig. 3 the first 200 and second 300 flow channel have a substantially parallel direction.

[0061] The arrangement for providing a fluid flow to a sensor according to the example embodiment comprises a fluid distribution plate 10 in a first fluid flow channel 200 as described hereinbefore and a sample flow guide 20 configured to convey fluid from the fluid collection space of the fluid distribution plate 10 towards a sensor 90 in a second flow channel 300. In an example embodiment of Fig. 4 the sample flow guide 20 comprises a curved pipe extending from the flow distribution plate past the sensor 90 in such a way that the sensor 90 resides inside the sample flow guide 20, so that the sensor substantially measures only the fluid flowing in the sample flow guide 20.

[0062] In a further example embodiment, the sample flow guide 20 ends well before the sensor, so that the sensor then measures a mixture of the fluid flow in the sample flow guide 20 and in the second flow channel 300. In a still further example embodiment, the sample flow guide 20 ends at the sensor level, so that the sensor then measures a turbulent flow emerging from the downstream end of the sample flow guide 20.

[0063] Fig. 5 shows an example embodiment in which the structure of the main flow channel is slightly different so that the second flow channel 300 is substantially perpendicular with the first flow channel 200.

[0064] The arrangement for providing a fluid flow to a sensor according to the example embodiment comprises a fluid distribution plate 10 in a first fluid flow channel 200 as described hereinbefore and a sample flow guide 20 configured to convey fluid from the fluid collection space of the fluid distribution plate 10 towards a sensor 90 in a second flow channel 300.

[0065] In an example embodiment of Fig. 5 the sample flow guide 20 comprises a curved pipe extending from the flow distribution plate past the sensor 90 in such a way that the sensor 90 resides inside the sample flow guide 20, so that the sensor substantially measures only the fluid flowing in the sample flow guide 20. In the example embodiment of Fig. 5 the sample flow guide 20 has a 90 degree bend as the second flow channel is perpendicular to the first flow channel 200.

[0066] Fig. 6 shows an example embodiment in which the structure is slightly different so that the sensor 90 is positioned in the first flow channel 200 directly after the flow distribution plate 10.

[0067] The arrangement for providing a fluid flow to a sensor according to the example embodiment comprises a fluid distribution plate 10 in a first fluid flow channel 200 as described hereinbefore and a sample flow guide 20 configured to convey fluid from the fluid collection space of the fluid distribution plate 10 towards the sensor 90.

[0068] In an example embodiment of Fig. 6 the sample flow guide 20 comprises a curved pipe extending from the flow distribution plate parallel with the flow distribution plate to the sensor 90 in such a way that the sensor 90 resides inside the sample flow guide 20, so that the sensor substantially measures only the fluid flowing in the sample flow guide 20. In the example embodiment of Fig. 6 the sample flow guide 20 has a 90 degree bend substantially at the downstream end thereof as the sensor resides next to the flow distribution plate.

[0069] The example embodiments of Figs. 1 to 6 disclose various structures and details. It is to be noted that the combinations disclosed are not limiting, i.e. the exact combinations of features of the depicted examples are not essential and various single features explained in view of the example embodiments can be combined in different example embodiments.

[0070] Fig. 7 shows a flow chart of a method according to an example embodiment.

[0071] At step 710, a flow distributor plate is provided in a flow channel with a fluid flow, the flow distributor plate comprising a first surface 12a and a second surface 12b defining therebetween a fluid collection space 16.

[0072] At step 720, the fluid flows through a plurality of holes 14 in the flow distribution plate 10 forming a fluid flow channel through the flow distributor plate.

[0073] At step 730, a part of the fluid flow in each hole 14 is conveyed through flow openings 18 in the side of each hole 14 into the fluid collection space 16.

[0074] At step 740, the fluid from the fluid collection space 16 is conveyed towards a sensor 90 via a sample flow guide 20 downstream of the second surface 12b.

[0075] At step 750, a quantity of interest is measured with the sensor 90.

[0076] Figs. 8 and 9 schematically show an example of an arrangement according to an example embodiment. Figs. 8 and 9 show an example embodiment in which the structure is slightly different so that the sensor 90 is positioned next to the flow distribution plate 10.

[0077] The first 200 and the second 300 flow channel are at an angle to each other in the example embodiment of Figs. 8 and 9, for example at a 90 degree angle, so that the exhaust gas flow makes a turn.

[0078] The arrangement for providing a fluid flow to a sensor according to the example embodiment comprises a fluid distribution plate 10 in a first fluid flow channel 200 as described hereinbefore and a sample flow guide 20 configured to convey fluid from the fluid collection space 16 of the fluid distribution plate 10 towards the sensor 90.

[0079] In an example embodiment, the flow distribution plate 10 is positioned at an angle with respect to the flow direction in the first flow channel 200.

[0080] In an example embodiment of Figs. 8 and 9 the sample flow guide 20 comprises an opening between the first surface 12a and the second surface 12b leading from the fluid collection space 10 towards the sensor 90.

[0081] In an example embodiment, the opening is positioned at the edge of the fluid distribution plate downstream of the second surface 12b, i.e. at the downstream side of the bend between the first 200 and second 300 flow channel.

[0082] In an example embodiment, the sample flow guide 20 further comprises an extension 22 to the second surface 12b configured to further guide the fluid from the fluid collection space 16 of the fluid distribution plate 10 towards the sensor 90.

[0083] Without in any way limiting the scope of the appended claims, some technical effects of the arrangement and method according to example embodiment are explained in the following.

[0084] The arrangement and method according to example embodiments is configured to provide a sample flow to a sensor, the sample flow being representative of the overall flow of non- homogenous fluid. The exhaust gas sampling and measurement system according to example embodiments is configured to provide a representative measurement of a quantity of interest of the exhaust gas flow.

[0085] Accordingly, a technical effect of example embodiments is enabling a measurement result representative of the overall fluid flow composition. A further technical effect of the example embodiments is to provide a representative sample flow. A still further technical effect of the example embodiments of the invention is to enable a measurement result corresponding to average value of the quantity ion the fluid flow. A still further technical effect of the example embodiments of the invention is to enable a representative measurement with a simple, robust and space saving structure.

[0086] Various embodiments have been presented. It should be appreciated that in this document, words comprise; include; and contain are each used as open-ended expressions with no intended exclusivity.

[0087] The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention.

[0088] Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.

Claims

CLAIMS1 . An arrangement for providing a fluid flow to a sensor, comprising a flow distributor plate (10) positioned in a flow channel, the flow distributor plate comprising a first surface (12a) and a second surface (12b) defining therebetween a fluid collection space (16); a plurality of holes (14) each forming a fluid flow channel through the flow distributor plate; and flow openings (18) in the side of each hole (14) of the plurality of holes configured to convey a part of the fluid flow in the hole (14) into the fluid collection space (16); the arrangement further comprising a sample flow guide (20) downstream of the second surface (12b) and configured to convey the fluid from the fluid collection space towards a sensor (90).

2. The arrangement for providing a fluid flow to a sensor of claim 1 , wherein the sample flow guide (20) comprises a flow channel leading from the fluid collection space (16) to or near the sensor (90).

3. The arrangement for providing a fluid flow to a sensor of claim 1 or 2, wherein the size and / or number of the flow openings (18) in the side of the holes (14) increases with the distance of the hole from the sample flow guide (20) increasing.

4. The arrangement for providing a fluid flow to a sensor of any preceding claim, wherein sample flow guide (20) comprises a pipe leading from the centre-point of the flow distribution plate (10) to the sensor (90).

5. The arrangement for providing a fluid flow to a sensor of any preceding claim 1 to 3, wherein sample flow guide (20) comprises an opening between the first surface (12a) and the second surface (12b) leading from the fluid collection space (1 ) to the sensor (90).

6. The arrangement for providing a fluid flow to a sensor of any preceding claim, wherein the flow distribution plate (10) is configured to convey a sample representative of the overall fluid flow to the sensor (90) via the sample flow guide (20).

7. The arrangement for providing a fluid flow to a sensor of any preceding claim, wherein size and / or number of the flow openings (18) in the side of the holes (14) is configured to convey to the sample flow guide a sample fluid comprising equal amount of fluid from each hole (14).

8. The arrangement for providing a fluid flow to a sensor of any preceding claim, wherein the fluid comprises a non-homogenous gas.

9. An exhaust gas sampling and measurement system, comprising a first exhaust gas flow channel (200) comprising an exhaust gas aftertreatment device (100); a flow distributor plate (10) positioned in the first exhaust gas flow channel downstream of the exhaust gas aftertreatment device, the flow distributor plate comprising a first surface (12a) and a second surface (12b) defining therebetween an exhaust gas collection space (16); a plurality of holes (14) each forming an exhaust gas flow channel through the flow distributor plate; and flow openings (18) in the side of each hole (14) of the plurality of holes configured to convey a part of the exhaust gas flow in the hole (14) into the exhaust gas collection space (16); the system further comprising a second exhaust gas flow channel (300) downstream of the flow distribution plate (10); a sensor (90) positioned in the second exhaust gas flow channel (200); and a sample flow guide (20) downstream of the second surface (12b) and configured to convey the fluid from the fluid collection space towards the sensor (90).

10. The exhaust gas sampling and measurement system of claim 8, wherein the sensor (90) comprises a NOx-sensor.11 . A method for providing a fluid flow to a sensor, comprising providing a flow distributor plate (10) in a flow channel, the flow distributor plate comprising a first surface (12a) and a second surface (12b) defining therebetween a fluid collection space (16) and a plurality of holes (14) each forming a fluid flow channel through the flow distributor plate; the method further comprising convey a part of the fluid flow in each hole (14) through flow openings (18) in the side of each hole (14) into the fluid collection space (16); and conveying the fluid from the fluid collection space towards a sensor (90) via a sample flow guide (20) downstream of the second surface (12b).

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