Gas measurement chamber

Abstract

The invention relates to a recyclable measuring cell for optical measurements in a gas, the cell being defined by a gas guide tube, the input end of which is adapted to be connected to a gas flow input which introduces the gas into the cell, and the output end of which is adapted to be connected to a gas flow output. The tube ends are further adapted to be coupled to optical components, including an optical emitter which emits light into the cell and an optical receiver which is adapted to receive light which has passed through the cell, the light beam in the cell having a predetermined shape, the optical components including a light source, at least two mirrors and a light receiver, mounted in known positions in an outer frame which is covered by the tube ends. The cell has an elongated shape which corresponds to the shape of the light beam.

Description

Technical Field

[0001] This invention relates to a recyclable measuring gas chamber for gas optical measurement, and a measuring instrument using the gas chamber.

[0002] More specifically, the present invention relates to a multiple-reflection sample gas chamber for use in gas analyzers, such as infrared gas analyzers, and more particularly, to a multiple-reflection sample gas chamber that achieves a long optical path within a limited volume. Such systems are well known, as illustrated in US5726752 and US2017168275A1, and as demonstrated in US5726752, the sample gas chamber should not be larger than the envelope representing the light beam passing through it, allowing for rapid gas exchange within the chamber. However, as shown in US5726752, these solutions use specific gas samples, which slows down the measurement process. WO2015 / 069934 shows an example of a solution in which light passes through a gas chamber multiple times, while the volume outside the optical path within the gas chamber is minimized.

[0003] Furthermore, industrial exhaust gases, such as engine exhaust, may contain contaminants that pollute optical components. An example of this could be exhaust gases from combustion processes. Particulate matter and contaminants in these exhaust gases can deposit in the measuring chamber and on the optical components. After a period of use, the transmittance through the chamber decreases, necessitating cleaning of the optical components and the chamber. This maintenance is often difficult and time-consuming. Therefore, another object of the present invention is to provide a solution that allows for the quick and reliable replacement of the gas chamber unit. Background Technology

[0004] Disassembling optical instruments takes time, and optical alignment is somewhat impossible outside of a laboratory setting. This problem is solved by mounting and aligning all optical components on a frame and inserting a gas guide into the frame. The gas guide is easily removable, providing access to all optical components requiring cleaning. The gas guide can be easily replaced with a new one, or it can be cleaned and reinstalled. Such a replaceable gas chamber is discussed in US2010 / 0110437.

[0005] One of the main problems with existing gas chamber technologies is that, if continuous flow is used, it takes a long time to exchange the gas within the measuring chamber. If the gas inlet and outlet are close to each other, the new gas flowing into the chamber often mixes with the old gas, and the gas exchange follows a typical dilution method: the first injection fills 50% of the chamber volume, the second 75%, and so on. If the gas chamber is very long relative to its diameter, laminar flow can be achieved, and only one gas volume needs to be filled to exchange most of the gas. In more typical chambers, laminar flow is generated between the gas inlet and outlet, but this leaves some of the gas inside the chamber unchanged. Then, it typically takes a long time to exchange all the gas inside the chamber. Summary of the Invention

[0006] One object of the present invention is to provide a solution in which measurements can be performed continuously as the gas composition changes, thereby achieving a short response time.

[0007] The above-mentioned objective is achieved using an exchangeable gas chamber and a measuring instrument including said gas chamber, characterized as described in the independent claim.

[0008] Therefore, in order to change the gas volume as quickly as possible at a given flow rate, the wall of the gas chamber according to the invention is formed as a ray trajectory with a combined inlet for the optical measurement beam and the gas flow. This minimizes the volume inside the gas chamber. Furthermore, the gas chamber is made elongated, and preferably the optical path intersects itself to minimize the volume used. To avoid laminar flow being absent in a part of the gas chamber and other parts of the gas chamber, forced turbulence or vortices are generated during the flow. Preferably, the inlet flow is forced to begin a swirling flow, wherein the flow pattern forms a spiral through the gas chamber. This spiral flow forces all the old gas to flow in front of the new gas, leaving no old gas behind. Preferably, at the outlet, a similar structure is created to force the outlet gas into forced turbulence. Attached Figure Description

[0009] The present invention will now be described with reference to the accompanying drawings, and will be illustrated by examples.

[0010] Figure 1 A cross-section of the gas chamber according to a preferred embodiment of the present invention is shown.

[0011] Figure 2 The beam path of the optical measurement beam is shown.

[0012] Figure 3 A preferred embodiment of the invention is shown, illustrating the flow of gas within a gas chamber.

[0013] Figure 4a Figures b show the shape of the gas chamber end in a preferred embodiment of the present invention.

[0014] Figure 5 A preferred embodiment of the invention is shown, comprising a measuring instrument and a gas chamber assembly.

[0015] Figure 6 As shown above Figure 5 The components shown, as well as the connection between the air chamber and the measuring instrument, are illustrated.

[0016] Figure 7 Alternative measuring instruments suitable for gas chambers receiving the present invention are shown.

[0017] Figure 8 It shows Figure 7 Alternative instruments include gas chambers. Detailed Implementation

[0018] Figure 1 A preferred embodiment of the present invention is shown, comprising a pipe 1 having a chamber 2 through which the gas to be measured flows. The pipe has a gas inlet 3 and a gas outlet 4, and at each end are mounting portions 1a and 1b, such as screws and sealing elements 1c. Figure 8 ), so that the gas chamber can be installed in the measuring instrument 12, which includes optical elements. Figure 5 )middle.

[0019] As mentioned above and Figure 2 As shown, by calculating the trajectory shape of the beam 2a used to measure the gas, the volume of the gas chamber is reduced to a minimum. Figure 2 In the preferred embodiment shown, the optical system 5a included in the measurement system includes a light source 6, the wavelength range of which is selected according to the characteristics of the gas to be measured, as is well known to those skilled in the art. The light source 6 may include a lens for shaping or collimating the light beam propagating from the first portion 5a to the second portion 5b at the other end 1b of the conduit 1. At the second end 1b of the conduit, the corresponding portion 5b of the measuring instrument includes a mirror 8b that reflects the light beam from the gas chamber to the mirror 8a at the first end 5a of the optical system. The mirror 8a at the first end 5a reflects the light beam again through the gas chamber to the receiver 7 at the second portion 5b of the optical system. The receiver 7 and the transmitter 6 are connected to a measurement system with an analytical gas absorption spectrum known per se. The envelope of the propagating and intersecting light beam 2a is calculated, and the shape of the gas chamber 2 is determined based on this shape 2a.

[0020] Thus, in the preferred embodiment, the light beam propagates three times in the gas, thereby achieving the same effect as a measuring chamber three times longer. Figure 2 As shown, the beam can be configured to pass through the same volume at least twice, increasing the system's sensitivity.

[0021] Other configurations can also be considered, such as adding an additional reflector to each end 5a, 5b on opposite sides of the transmitter and receiver, allowing the optical signal to travel five times within the gas chamber. Furthermore, different reflector shapes and lenses can be selected for beam shaping. However, it is important that the shape of the gas chamber 2, or the internal shape of the pipe volume, corresponds to the shape of the beam to reduce the volume of the gas chamber, as described above.

[0022] Figure 3 This illustrates how the airflow 9 propagates along the air chamber 2 defined by the duct 1. By providing a spiral flow, it is ensured that even with uneven gas composition distribution, the spiral airflow passes through the beam multiple times, providing an actual gas content measurement, while forcing the old gas out of the air chamber without leaving any air pockets.

[0023] Figure 4a The method for achieving mixing is illustrated, showing the input end of the measuring gas chamber. In the figure, gas enters the gas chamber on one side of the optical element at asymmetric feature 10a, directing the gas to one side of the gas chamber. In the illustrated example, this guides the introduced gas to the upper wall of the gas chamber, thus the pressure forces the gas to circumvent the shape of the gas chamber and enter the gas conductor, achieving a vortex flow.

[0024] Figure 4b A similar feature 10b is shown at the output end of the gas conductor or gas chamber, ensuring that the vortex flow is maintained until it leaves the gas chamber. Small features that maintain the vortex flow along the gas chamber tube can also be considered, as long as they do not interfere with the optical path or the movement of the gas within the gas chamber.

[0025] Other gas mixture solutions can be considered, but the beam must not be obstructed by any features in the duct. The illustrated example relates to a preferred embodiment, including asymmetric features, but other features, such as inserts or similar elements, can also be used, for example, to position the gas before it enters the beam path.

[0026] Figure 5 The components of a preferred embodiment of the invention are shown, wherein a replaceable measuring chamber is installed within the measuring unit 12. As described above, the measuring unit includes optical components 7, 8 that emit, reflect, and receive a measuring beam passing through the chamber. When the chamber is removed, the optical components can be easily cleaned, and the chamber itself can be easily replaced.

[0027] The measuring instrument 12 also includes a gas inlet 13 and an outlet 14, which, as described above, are located near the input end of the optical element, so that the flow preferably enters the same opening of the measuring gas chamber along with the measuring beam. This allows measurements to be obtained along or against the airflow vortex.

[0028] The gas chamber is secured and sealed to the measuring instrument using a suitable device 11 available to those skilled in the art.

[0029] Figure 6 The measuring instrument 12, as seen from above, is shown, with sections AA and BB illustrating the connection areas of the gas chamber ends 1a and 1b. It can be seen that the gas chamber ends cover and surround the optical elements 7 and 8, as well as the gas input 13a or output 14a connected to the inlet 13 and outlet 14, respectively. As shown, the gas chamber shape on the input side 1a introduces gas into the rotating flow channel 9 at both the input and output ends.

[0030] Thus, the present invention provides a multi-reflection type measuring gas chamber in which incident light is reflected multiple times. A sample for analyzing the sample in the sample gas chamber includes:

[0031] - An external frame 12, all optical components such as light source 6, detector 7, reflector 8, and any windows or lenses are mounted in the correct position on the measuring instrument and aligned and fixed so that the instrument can function fully.

[0032] - An easy-to-install and replaceable gas guide device 1, which functions as a wall of the gas chamber and a fluid conductor from the input to the output side, and reduces the gas volume required for analysis.

[0033] As shown in the figure, this invention is mainly aimed at measuring waste gases such as exhaust gases, but within the scope of this invention, it can also be modified to provide measurements of liquids.

[0034] Preferably, the gas guiding volume occupies the space immediately outside the envelope region, where incident light passes through the sample gas chamber, and has the means described above to generate forced turbulence or mixing, so that no old gas pockets are left behind when new gas enters the sample gas chamber in continuous flow. Preferably, this flow pattern forms a spiral shape in the gas chamber. To provide effective gas exchange, the length of the gas chamber is at least four times the diameter of the device. This is to avoid leaving some old gas behind, as well as mixing of new and old gases.

[0035] Figure 7 and 8 Another instrument housing 15 is shown, wherein an eccentric bolt 16 is used to secure the gas chamber inside the instrument. As is well known to those skilled in the art, in the illustrated example, the gas chamber is locked in place by inserting the bolt into the appropriate opening 1e of the instrument and the gas chamber and rotating the bolt 180 degrees. Figure 8 As shown, the preferred embodiment of the gas chamber has sealing devices at both ends, represented in this case by a sealing ring 1c and a pressure plate 1d. Therefore, when installed in the instrument cavity, the gas chamber seals the end of the cavity to ensure that the gas in the system does not escape.

[0036] Preferably, the fluid measuring chamber is made of a rigid material, and the device has a mechanism at each end that allows the user to force a gasket to seal the fluid between the gas guide and the frame, thus creating a seal for the fluid. Preferably, the chamber material is a polymer such as POM (polyoxymethylene), polytetrafluoroethylene, PE (polyethylene), or PP (polypropylene).

[0037] In summary, the present invention relates to a retrievable measuring gas chamber for optical measurements in a gas. The gas chamber is defined by a gas guide tube, the inlet of which is adapted to be connected to a gas flow inlet for introducing gas into the gas chamber, and the outlet of which is adapted to be connected to a gas flow outlet.

[0038] The tube end of the gas chamber is also adapted to couple to optical components, including an optical emitter that emits light into the gas chamber and an optical receiver adapted to receive light passing through the gas chamber. The optical components include a light source, at least two mirrors, and a light receiver, which are mounted in known locations on an outer frame covered by the tube end, and thus define a known beam shape.

[0039] The first end of the tube is adapted to connect to a transmitter and at least one reflector, and the second end of the tube is adapted to connect to a receiver and the same number of reflectors as the first end. Then, depending on the number of reflectors, the beam will pass through the gas chamber at least three times, wherein the gas chamber has an elongated shape corresponding to the beam shape. The beam shape can be defined using beam shaping mirrors, lenses, etc.

[0040] Preferably, the air chamber at the inlet of the pipe has an asymmetrical shape, suitable for forcing rotating airflow or turbulence through the pipe, ensuring that the gas passing through the air chamber is mixed. Features in the flow path can also be used, as long as they do not interfere with the gas throughput.

[0041] The conduit may include a sealing device connected to a measuring instrument, which is connected to an optical component including the fluid input and output, as well as the light emitter, receiver, and reflector.

[0042] The present invention also relates to a measuring instrument for receiving a recyclable measuring gas chamber within a defined space. The instrument includes a fluid input section adapted to provide a sealed connection for a fluid input conduit within a frame at a first end of the space, and a fluid output section adapted to provide a sealed flow output connection for the output end of the conduit at a fluid output point. The measuring instrument further includes optical elements for emitting and receiving light from the gas chamber at the sealed connection.

[0043] All optical elements are mounted in known positions covered by the tube end and aligned and fixed in predetermined positions on an external frame consisting of measuring instruments, so that the optical elements can function fully regardless of whether there is an air chamber.

Claims

1. A retrievable measuring gas chamber for optical measurements in a gas, the gas chamber being defined by a gas guide tube, the inlet of the gas guide tube being adapted to connect to a gas flow inlet for introducing gas into the gas chamber, and the outlet of the gas guide tube being adapted to connect to a gas flow outlet, the inlet and outlet being further adapted to couple to an optical component, the optical component comprising an optical emitter for emitting light into the gas chamber and an optical receiver adapted to receive light that has passed through the gas chamber, the light beam in the gas chamber having a predetermined shape, the optical component comprising a light source, at least two mirrors, and a light receiver, mounted at different known locations on an external frame covered by the tube ends, wherein, The first end of the input and output terminals is adapted to be connected to a transmitter and at least one individual reflector, and the second end of the input and output terminals is adapted to be connected to a receiver and the same number of reflectors as the first end, so that the light beam passes through the gas chamber at least three times, wherein the gas chamber has an elongated shape corresponding to the shape of the light beam, wherein the gas chamber at the pipe input end is adapted to force rotating airflow or turbulence in the airflow through the pipe; the light path itself crosses to minimize the volume used; the light beam is configured to pass through the same volume at least twice to increase the sensitivity of the system; the gas chamber at the pipe input end has an asymmetrical shape to provide rotating gas flowing through the pipe.

2. The measuring chamber according to claim 1, characterized in that, The conduit includes a sealing device for connection to a measuring instrument, which includes the airflow inlet and outlet, as well as a light emitter, a receiver, and a reflector.

3. A measuring instrument comprising a space for accommodating a recyclable measuring chamber according to any one of the preceding claims, comprising an airflow input portion adapted to provide a sealed connection at a first end of the space to an end of an airflow input pipe and an airflow output portion adapted to provide a sealed connection at the output end of the pipe to an airflow output portion, the measuring instrument further comprising the optical component at the sealed connection, transmitting and receiving light in the chamber.

4. The measuring instrument according to claim 3, characterized in that, All optical elements mounted at known locations covered by the tube end are aligned and fixed in predetermined positions on an external frame consisting of measuring instruments, so that the optical elements can function fully with or without the air chamber.

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