Device for sampling from an exhaust gas mass stream

Abstract

Device (1) for sampling from an exhaust gas mass flow, wherein at least one line (3) branches off from an exhaust gas mass flow line (2) with an upstream end (4) and opens either back into the exhaust gas mass flow line (2) or into an intake air line with a downstream end (5), and wherein the line (3) has at least one open-pore metal foam as an adsorber (6) between the upstream end (4) and the downstream end (5), and wherein at least one thermal conditioning unit (7) is arranged on an outer surface of the adsorber (6), wherein the temperature of the adsorber (6) can be adjusted by means of the thermal conditioning unit (7) such that the adsorber (6) cools the exhaust gas to a desired value, and wherein the line (3) has at least one heat exchanger (9) between the upstream end (4) and the adsorber (6).

Description

Technical field

[0001] The invention relates to a device for taking samples from an exhaust gas mass stream. State of the art

[0002] Exhaust gas mass flow from the combustion of hydrocarbons contains soot particles and longer-chain hydrocarbons, which promote sooting.

[0003] Knowledge of the exhaust gas mass flow composition enables both measures to influence it in a targeted manner and a reliable simulation of the exhaust gas composition and the effects that occur along the further path of the exhaust gas mass flow.

[0004] Measuring components relevant to sooting in the exhaust gas mass flow, especially long-chain hydrocarbons, is only possible to a limited extent by means of concentration measurement in the gas phase due to the insufficient sensitivity of commercially available devices.

[0005] Due to the large number of isomers in long-chain hydrocarbons, precise assignment to specific substances with corresponding boiling profiles using a mass spectrometer is currently only possible to a limited extent.

[0006] If samples are separated using conventional filters, such as fiberglass filters, the exhaust gas mass flow must be cooled down significantly beforehand; consequently, a large proportion of the substances being sought are deposited on the wall of the exhaust pipe well before the filter.

[0007] If the exhaust pipe is heated too strongly, the desired low temperature cannot be achieved in the filter, consequently too little of the substances being sought is separated.

[0008] DE 101 28 632 A1 describes a long-term sampling system for the continuous monitoring of dust and pollutant emissions and for determining dust emissions in flowing media by isokinetic sampling of a partial gas stream from the main gas stream of a pollutant emitter using a partial stream sampling probe and by separating the dusts by cake filtration on a fine filter as well as volatile, i.e. filterable, chemical components dissolved in the partial gas stream in an adsorber stage.

[0009] During continuous monitoring, the adsorber stage downstream of the fine filter is permeated by the entire partial gas flow.

[0010] The adsorber stage can be replaced by several adsorber stages connected in parallel or in series.

[0011] The partial gas flow can be fed back into the main gas flow at a point after the partial gas flow was extracted, viewed in the direction of flow.

[0012] However, selected adsorbents are used for adsorption in the adsorber stages.

[0013] DE 10 2008 051 846 A1 describes a system for sampling recirculated exhaust gas from an internal combustion engine, in particular of the diesel type, comprising an exhaust gas recirculation circuit between the exhaust of this engine and its intake manifold, wherein the circuit includes a circulation line for recirculated gas which carries a circulation control valve for the gas.

[0014] The system includes at least two sampling points on the recirculated exhaust gas circulation line and a distribution device that sends the sampled gas to at least one analysis system.

[0015] The focus here is on the adsorption of selected hydrocarbons.

[0016] DE 41 14 400 A1 describes a method and an arrangement for sampling and measuring radioactive gaseous iodine compounds in the exhaust air of nuclear power plants with light water reactors during the post-accident phase of a nuclear incident. A partial flow is extracted from a known main sampling line of an exhaust air control system and conveyed at a low flow rate through a heated and insulated pipe to a heated aerosol filter. This partial flow then enters a heated iodine filter cartridge containing Al₂O₃ with 25-50% AgNO₃ impregnation as the sorption material. The iodine isotopes contained in the partial flow are then passed through a condenser to reduce humidity and subsequently returned to the main sampling line via known components.

[0017] US 2007 / 0151449A1 describes a technology for concentrating vaporous substances.

[0018] A sorption material is arranged in a first housing which has an inlet and an outlet.

[0019] By means of a heating element arranged on the outside of the first housing, the sorption material can be heated in such a way that the substances stored in the sorption material are released.

[0020] A second housing forms a chamber within which the first housing is arranged in such a way that a gap is formed between the first housing and the second housing for a flowing gas stream.

[0021] A pump allows the gas flow to enter the first housing via the inlet, flow through the gap, and flow out of the first housing via the outlet.

[0022] EP 3 379 228 A1 describes a gas sampling probe, a gas container with such a gas sampling probe and a method for taking a gas sample from a gas of a gas container with such a gas sampling probe.

[0023] The gas sampling probe comprises a gas line, including a gas channel formed in the gas line through which a gas can flow, a gas inlet through which a gas can be introduced into the gas channel, an adsorption material arranged downstream of the gas inlet in the gas channel, and a valve through which the gas channel can be shut off between the gas inlet and the adsorption material.

[0024] DE 10 2012 006 542 A1 describes a methyl iodide adsorber comprising a zeolite containing at least one iodide-adsorbing metal or a compound thereof, wherein the zeolite is a hydrophobic zeolite. Object of the invention

[0025] The invention is based on the objective of providing a device for sampling from an exhaust gas mass stream, which enables a reliable determination of sooting-relevant components in the exhaust gas mass stream. Solution to the task

[0026] The problem is solved by a device for sampling from an exhaust gas mass flow according to claim 1. Advantages of the invention

[0027] In the device according to the invention for sampling from an exhaust gas mass flow, at least one line branches off from an exhaust gas mass flow line with an upstream end and opens with a downstream end either back into the exhaust gas mass flow line or into an intake air line (in this variant the line is an EGR line).

[0028] The line has at least one adsorber between the upstream end and the downstream end.

[0029] At least one thermal conditioning unit is arranged on an outer surface of the adsorber.

[0030] The conditioning unit can extend over the entire length of the adsorber or at least over a part of the adsorber.

[0031] It is possible to arrange several adsorbers with their respective conditioning units one after the other in the direction of the exhaust gas mass flow through the pipe.

[0032] The respective conditioning units can be operated at different temperatures, so that the temperatures of the individual adsorbers can be set individually.

[0033] The device according to the invention enables a thermally conditioned guidance of the exhaust gas mass flow via an adsorber.

[0034] The adsorber exhibits high heat transfer due to the use of an open-pore metal foam.

[0035] This allows the adsorber to effectively cool exhaust gas, which has been routed to the adsorber at high temperature to prevent condensation of the desired substances on the pipes, to a desired value, and thereby adsorb the hydrocarbons that precipitate in the temperature range thus achieved.

[0036] This allows the separation of sooting-relevant substances to take place at a desired temperature, for example analogous to a wall temperature in the EGR cooler.

[0037] This means that the thermal conditions in the adsorber are representative of real sooting conditions, and only those substances that become liquid at the set temperature are condensed in the adsorber.

[0038] Since for certain analyses and models the precise knowledge of the individual species is not essential, but the boiling range and the adsorbed mass are of great importance, the device according to the invention represents an effective and cost-efficient solution. Thus, with a suitable choice of adsorber material, the adsorber can be subjected directly to thermogravimetric analysis after loading.

[0039] Using this, it is possible to derive, for a specific temperature range, what proportion of the adsorbed substances have which boiling range.

[0040] An analysis in the range up to 600°C boiling point may well be possible when using aluminium foams as adsorbent material.

[0041] In addition, there are numerous other ways to analyze the adsorbed material qualitatively and quantitatively, for example by weighing or by extracting the organically soluble fraction with a suitable solvent and subsequently analyzing the extract using a gas chromatograph and mass spectrometer.

[0042] In an advantageous embodiment of the invention, the line between the adsorber and the downstream end has at least one conveying device, optionally with a pre-filter, to ensure a desired exhaust gas mass flow through the adsorber.

[0043] The pumping system can be adjusted.

[0044] Advantageously, the conveying device is arranged downstream of the adsorber in order to keep thermal loads low and to avoid losses of material to be adsorbed in the adsorber.

[0045] According to the invention, the line between the upstream end and the adsorber has at least one heat exchanger.

[0046] This heat exchanger is designed to reduce the exhaust gas temperature, especially with high exhaust gas mass flow and high exhaust gas temperature, so that a desired temperature is not exceeded in the adsorber.

[0047] In an advantageous design, the heat flow from the exhaust gas in the heat exchanger is controllable and is adjusted so that just enough heat is extracted from the exhaust gas to ensure that the outlet temperature of the exhaust gas from the heat exchanger is just high enough to achieve the desired temperature of the adsorber at maximum cooling capacity of the conditioning unit.

[0048] This should prevent the premature condensation of sought-after substances in the exhaust gas upstream of the adsorber.

[0049] In a further advantageous embodiment of the invention, the exhaust gas mass flow line has at least one flow resistance between the upstream end and the downstream end.

[0050] The flow resistance can be a non-changing element (e.g., a fixed aperture), an adjustable element (e.g., a controllable throttle valve), or a combination of at least one non-changing and at least one adjustable flow resistance.

[0051] If at least one adjustable flow resistance is present, it can advantageously be adjusted so that a desired mass flow is directed over the adsorber.

[0052] The mass flow rate through the adsorber must be measured using suitable means. Drawings

[0053] They show: Fig. 1: a longitudinal section through an exemplary device for sampling from an exhaust gas mass flow; Fig. 2: a longitudinal section through a first embodiment of the device according to the invention for sampling from an exhaust gas mass flow; Fig. 3: a longitudinal section through a second embodiment of the device according to the invention for sampling from an exhaust gas mass flow.

[0054] The Fig. Figure 1 shows an exemplary device. 1. An exhaust gas mass flow flows in the direction of arrow P1 within an exhaust gas mass flow line. 2.

[0055] A line 3 has an upstream end 4 and a downstream end 5. The exhaust gas mass flow can flow from exhaust gas mass flow line 2 into line 3 via the upstream end 4 in the direction of arrow P2. The exhaust gas mass flow can also flow from line 3 into exhaust gas mass flow line 2 via the downstream end 5 in the direction of arrow P3.

[0056] The line 3 has an adsorber 6 between the upstream end 4 and the downstream end 5.

[0057] The adsorber 6 is preferably an open-pore metal foam.

[0058] Preferably, the adsorber 6 has a smaller flow cross-section compared to its length, but a large length compared to its flow cross-section, so that very good heat transfer can take place between the adsorber 6 and a surrounding thermal conditioning unit 7.

[0059] The thermal conditioning unit 7 borders the outer surface of the adsorber 6, so that the adsorber 6 is arranged inside the thermal conditioning unit 7.

[0060] The desired temperature is set via the thermal conditioning unit 7, for example via active cooling using a pelletizing element or cooling medium; heating is also possible if required.

[0061] The adsorber 6 is designed with appropriate dimensions and tolerances to ensure good heat transfer to the thermal conditioning unit 7, while at the same time preventing damage to the thermal expansion of the components.

[0062] The walls of the supplying sample line, i.e. the section of line 3 between the upstream end 4 and the adsorber 6, have a higher temperature compared to the adsorber 6, so that the substances sought, which are only to be absorbed in the adsorber 6, do not already accumulate there.

[0063] The adsorber 6 is interchangeably inserted into the thermal conditioning unit 7.

[0064] For a trial operation, a quick change of the adsorber 6 is helpful, therefore a revolver solution is proposed in which several adsorbers 6 conditioned by means of the thermal conditioning unit 7 are successively brought into operative connection with the line 3 (corresponding to P2 and P3).

[0065] The line 3 has a conveying device 8 between the adsorber 6 and the downstream end 5.

[0066] The conveying unit 8, optionally with pre-filter (not included) Fig. 1 shown), ensures a desired exhaust gas mass flow through the adsorber 6.

[0067] In Fig. Figure 2 shows a first embodiment of the device according to the invention. In comparison to the one in Fig. In the second embodiment, the line 3 between the upstream end 4 and the adsorber 6 has a heat exchanger 9 as shown in the first embodiment 1.

[0068] At very high exhaust gas temperatures, it may be necessary to connect the heat exchanger 9 upstream to cool the exhaust gas sample so that the temperature in the adsorber 6 can be set.

[0069] Advantageously, the exhaust gas mass flow through line 3 is cooled in this heat exchanger 9 only to the extent that the desired adsorber temperature is reached at the maximum possible inlet temperature of the exhaust gas mass flow into the adsorber 6.

[0070] In Fig. Figure 3 shows a second embodiment.

[0071] Compared to the one in Fig. In the embodiment shown in Figure 2, the exhaust gas mass flow line 2 has a flow resistance 10 between the upstream end 4 and the downstream end 5.

[0072] The flow resistance 10 is, for example, a heat exchanger, in particular an EGR cooler, which can also be supplemented by a throttling device, for example a throttle valve or a valve.

[0073] Furthermore, in the third embodiment, the [missing information] is omitted. Fig. 1 and Fig. 2. Conveyor facility shown 8.

[0074] The exhaust gas mass flow line 2, the line 3 and the individual components each have a circular cross-section.

[0075] Furthermore, other cross-sectional shapes are also possible. Reference symbol list 1 Device 2 Exhaust gas mass flow line 3 lines 4 upstream end 5 downstream end 6 Adsorbers 7 Conditioning unit 8 Support facility 9 heat exchangers 10 Flow resistance P1 Arrow P2 arrow P3 Arrow

Claims

[1] Device (1) for sampling from an exhaust gas mass flow, wherein at least one line (3) branches off from an exhaust gas mass flow line (2) with an upstream end (4) and opens either back into the exhaust gas mass flow line (2) or into an intake air line with a downstream end (5), and wherein the line (3) has at least one open-pore metal foam as an adsorber (6) between the upstream end (4) and the downstream end (5), and wherein at least one thermal conditioning unit (7) is arranged on an outer surface of the adsorber (6), wherein the temperature of the adsorber (6) can be adjusted by means of the thermal conditioning unit (7) such that the adsorber (6) cools the exhaust gas to a desired value, and wherein the line (3) has at least one heat exchanger (9) between the upstream end (4) and the adsorber (6). [2] Device (1) according to claim 1, characterized by, that the line (3) between the adsorber (6) and the downstream end (5) has at least one conveying device (8). [3] Device (1) according to at least one of the preceding claims, characterized by , that the exhaust gas mass flow line (2) has at least one flow resistance (10) between the upstream end (4) and the downstream end (5).

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