Optical process sensor, measuring head, measuring system including both and methods for calibrating and / or validating

Description

[0001] The invention relates to an optical process sensor, a matching measuring head, a measuring system comprising both, and a method for calibration and / or validation. For the purposes of this application, a "process sensor" is defined as a sensor used for the optimization, analysis, and control of manufacturing processes at the field level, such as in the chemical or pharmaceutical industries. These process sensors enable qualitative and quantitative analysis during the ongoing process. For example, physical or chemical parameters are acquired in real time and used for plant control or regulation.

[0002] DE 20 2013 101 907 U1 explains that with such process sensors, it is necessary from time to time to clean the sample chamber or the sensor itself, for which short-wave radiation such as gamma radiation or high temperatures can be used. This poses considerable risks to the comparatively sensitive optics of the measuring probes; in particular, the aggressive radiation or high temperatures can destroy the optical part of the measuring probe, so precautions must be taken to protect the sensitive optics from damage or even destruction during cleaning. DE 20 2013 101 907 U1 proposes that the part that comes into direct contact with the sample being examined be designed to be detachable, so that it can be easily removed from the sensitive parts of the sensor during cleaning.

[0003] WO 2010 / 027982 A2 discloses an adapter mechanism for portable spectral sensors that allows the use of various sample formats such as ampoules, vials, and cuvettes. The adapters are attached to the handheld device and contain optical elements such as mirrors or prisms to control the light path between the transmitter and receiver of the device. Several embodiments are described, including ampoule adapters with mirrors, prism-based adapters for vials and cuvettes, and a surface adapter for reflectance measurements.

[0004] US 2017 / 292909 A1 describes a modular optical detection system for flow cells comprising a light source, detector unit and flow cell, wherein the detector unit with the detectors is spatially separated from the light source and connected via an optical fiber.

[0005] German patent DE 101 49 879 A1 describes a handheld spectrophotometer for the analysis of liquids, which can be operated with one hand like a pipette. The device contains a light source, a monochromator, a detector, and a display unit in an ergonomic housing. For the measurement, a light guide tip with a cup-shaped recess is immersed directly into the sample; this tip can be designed as a replaceable or even a disposable module to avoid cross-contamination.

[0006] EP 3 228 999 A2 discloses a modular measuring system with a spectrometer and a light guide tube.

[0007] Optical sensors, used for example in the food and pharmaceutical industries, must be regularly validated to ensure their correct functioning. The properties to be checked are regulated, among other things, in the Pharmacopoeia, USP (USA), and a corresponding European equivalent. These include wavelength accuracy, photometric accuracy or linearity, stray light behavior, and wavelength resolution.

[0008] For the tests described above, test liquids and solid standards in cuvette form or filter sets with the corresponding certificates are available for laboratory instruments. The laboratory instruments can be easily validated using these standards. For this purpose, the cuvette standards or filters are placed in the beam path of the instrument to be validated.

[0009] This approach is not possible with process sensors because the optical beam path is inaccessible, as it is specifically protected from the harsh process environment. Process sensors often use measuring cells, which are connected to the light sources and receivers via fiber optic cables to a decoupled measuring system. To validate the measuring system, the fiber optic cables are removed from the corresponding measuring cell and connected to a cuvette holder.

[0010] Some designs feature a slot in the beam path into which mechanically adapted filters, usually solid-state filters, can be inserted. These solutions have the disadvantage that standards with certified values ​​often cannot be used.

[0011] The invention is based on the objective of validating and calibrating process sensors in a simple way.

[0012] The problem is solved by an optical process sensor for measuring at least one measurand of a medium in a container, as described in claim 1.

[0013] The advantages of the solution with the described optical sensor, especially in combination with a measuring head, which together form an optical measuring system, will be discussed further below.

[0014] One design provides that the first and second light guides are designed as optical waveguides.

[0015] The claimed invention provides that the first and second paths are designed as two separate rod-shaped, in particular cylindrical, extensions, which are connected to the housing in particular by screwing, gluing, welding or by frictional connection, wherein the first and second light guide is guided inside the extensions.

[0016] One embodiment provides that the first and second paths at the end area furthest from the process sensor each comprise an optical element, in particular a window and / or a lens, wherein the optical element is transparent to the transmitted and received light.

[0017] One embodiment provides for the sensor to be designed as a spectrometer.

[0018] The object is further solved according to the invention by an optical process sensor designed for measuring at least one measurand of a medium in a container, the measuring head comprising: a housing designed for connecting the sensor to the container; a second optical-mechanical interface comprising a second optical section complementary to a first optical section.

[0019] In one embodiment, the second optical section is designed as a recess in the housing.

[0020] According to the invention, the second optical section comprises a third path that receives transmitted light and couples it into the interior of the housing.

[0021] In one embodiment, the third path directs the transmitted light to a deflecting element.

[0022] According to the invention, the second optical section comprises a fourth path that receives transmitted light, passes through a medium-flowing area, the transmitted light being converted into received light by the medium, and couples received light out of the housing.

[0023] According to the invention, the second optical-mechanical interface comprises a second mechanical section, complementary to a first mechanical section, which is designed as an integral part of the housing.

[0024] One embodiment provides that the measuring head includes a deflecting element in the housing, which deflects transmitted or received light from the third path to the fourth path or vice versa.

[0025] In one embodiment, the area through which the medium flows is designed as a further recess in the housing.

[0026] In one embodiment, the measuring head thus comprises an optical process sensor designed to measure at least one measurand of a medium in a container, the measuring head comprising: a housing designed to connect the sensor to the container;a second opto-mechanical interface comprising a second optical section complementary to a first optical section, which is designed as a recess in the housing, a third path that receives transmitted light, couples it into the interior of the housing and leads to a deflecting element, and a fourth path that receives transmitted light from the deflecting element, leads it through a medium-flowing region, the transmitted light being converted into received light by the medium, and the received light being coupled out of the housing, and a second mechanical section complementary to a first mechanical section, which is designed as an integral part of the housing, the deflecting element which is arranged in the housing, and the medium-flowing region which is designed as a further recess in the housing.

[0027] In one embodiment, the measuring head comprises an optical process sensor designed to measure at least one measurand of a medium in a container, the measuring head comprising: a housing designed to connect the sensor to the container;a second opto-mechanical interface comprising a second optical section complementary to a first optical section, which is designed as a recess in the housing; a third path that receives transmitted light, couples it into the interior of the housing, leads through a medium-flow area, whereby the transmitted light is converted into received light by the medium, and leads the received light to a deflecting element; a fourth path that receives received light from the deflecting element and couples it out of the housing; and a second mechanical section complementary to a first mechanical section, which is designed as an integral part of the housing, the deflecting element which is arranged in the housing, and the medium-flow area which is designed as a further recess in the housing.

[0028] The path through which the medium flows can therefore be located in the third or fourth path.

[0029] The use of an optical-mechanical interface on both the sensor and the measuring head makes it possible to decouple different types of measuring heads, such as immersion probes or flow cells, from process sensors. This allows the measuring head to remain in the process, keeping it sealed for the further validation process of the sensor.

[0030] The removed sensor with its optical-mechanical interface can now be used for the validation process. By replacing the sensor's measuring head with a validation adapter (which is considered a special type of measuring head) to accommodate certified cuvettes or filters, the sensor can be easily verified.

[0031] As with a laboratory spectrometer, this validation device and the ability to use certified standards (cuvettes, filters) enable the complete validation of the process sensor.

[0032] One embodiment provides that the deflecting element deflects the transmitted light by 180°.

[0033] One embodiment provides that the deflection element is designed as a prism.

[0034] One embodiment provides that the third and fourth paths are designed as two separate rod-shaped, in particular cylindrical, recesses.

[0035] One embodiment provides that the third and fourth paths, in particular each, comprise an optical element, especially a window and / or a lens, wherein the optical element is transparent to the transmitted and received light.

[0036] One embodiment provides that the third or fourth path includes a window to the area through which the medium flows, with the window being transparent to the transmitted and received light.

[0037] One design provides for the measuring head to be designed as a submersible probe.

[0038] One embodiment provides that the measuring head is designed as a flow probe. Another embodiment provides that the measuring head is designed as a calibration and validation device.

[0039] Here you can see the particular advantages of the optical-mechanical interface. Different measuring heads can be easily exchanged. The "actual" measuring head, e.g., a flow probe or immersion probe, remains in the process. After removing the sensor, a calibration and validation device is attached to the same optical-mechanical interface. The optical path is the same as in the process, and the sensor can be calibrated.

[0040] One embodiment provides that the calibration and validation device includes a cuvette holder with a holder for a cuvette, the holder forming the area through which the medium flows.

[0041] One design provides that the cuvette holder includes a solid-state standard.

[0042] One design provides that the calibration and validation device includes a cuvette changer.

[0043] One embodiment provides that the calibration and validation device includes a filter wheel or filter changer.

[0044] This also enables automatic verification of the process sensors by means of a suitable exchange unit (e.g. filter wheel, cuvette changer).

[0045] The task is further solved by an optical measuring system comprising an optical process sensor as described above and a measuring head as described above, wherein the second optical section accommodates the first optical section to enable an optical connection with a light path from light source, first light guide, first path, third path, deflection element, fourth path, second path, second light guide and light receiver, and enables a mechanical connection between the optical process sensor and the measuring head via the first mechanical section and second mechanical section.

[0046] One embodiment provides that the mechanical connection is detachable; in particular, the first mechanical section and the second mechanical section are designed in such a way that a screw connection exists; in particular, the first mechanical section and the second mechanical section include bores and / or threads for screws.

[0047] The problem is further solved by, as defined in claim 9, a method for calibrating and / or validating an optical process sensor, comprising the steps of: removing the sensor from a measuring head configured as a flow probe or immersion probe; attaching the sensor to a measuring head configured as a calibration and validation device; calibrating and validating the sensor using the calibration and validation device; removing the sensor from the calibration and validation device; and reattaching the sensor to the flow probe or immersion probe.

[0048] This will be explained in more detail using the following figures. Figs. 1a and 1b show the claimed optical process sensor in cross-section and a side view. Figs. 2a-d show the claimed measuring system in one embodiment (submersible probe). Figs. 3a-d show the claimed measuring system in one embodiment (flow probe). Figs. 4a-e show the claimed measuring system in one embodiment (cuvette holder). Fig. 5 shows the claimed measuring system in one embodiment (LED sensor). Figs. 6a-c show the cuvette holder with and without a solid standard.

[0049] In the figures, identical features are marked with the same reference symbols.

[0050] The claimed measuring system in its entirety has the reference numeral 100 and is, for example, in Fig. 2d The diagram shows the following. First, the individual components will be discussed, namely a process sensor 1 and a measuring head 51.

[0051] Fig. 1a und Fig. 1b Figure 1 shows sensor 1 with housing 2. The sensor is an optical sensor. For example, it is a spectrometer with a light source 3 and a light receiver 4. The light source 3 emits transmitted light 5, and the light receiver 4 receives received light 6, which is generated by the conversion of the transmitted light 5 by the medium being measured (see below). The light 5 emitted by the light source 3 is thus converted by the medium, for example, absorbed, scattered, or fluorescent light is produced. This converted light 6 is received by the receiver 4 and converted into an electrical signal.

[0052] The sensor 1 comprises a first optical-mechanical interface 10, which consists of an optical section 11 and a mechanical section 21.

[0053] The mechanical section 21 serves to connect the sensor 1 to the measuring head 51, for example by screwing it in place, with appropriate devices such as holes, threads or bores 22 and 72 being provided. The mechanical section 21 is an integral part of the housing 2.

[0054] The optical section 11 projects out of the housing 2. This section comprises a first path 12 and a first optical guide 13, such as an optical fiber or a free beam path, which introduces transmitting light 5 from the light source 3 into the first path 12 and then couples the transmitted light 5 out of the housing 2. This section further comprises a second path 14 and a second optical guide 15, such as an optical fiber or a free beam path, which couples received light 6 into the interior of the housing 2 and guides it via the second optical guide 15 from the second path 14 to the light receiver 4. The paths 12 and 14 are separate, cylindrical extensions that are, for example, screwed to the housing 2, with the optical fibers 13 and 15 running inside them.

[0055] Fig. 2a shows the measuring head 51 in cross-section, Fig. 2c in a side view. Fig. 2b shows sensor 1, directly next to Fig. 2a . Fig. 2d The measuring system 100 is shown in the assembly of sensor 1 and head 51.

[0056] The measuring head 51 includes a second optical-mechanical interface 60, which consists of an optical section 61 and a mechanical section 71.

[0057] The mechanical section 71 serves to connect the measuring head 51 to the sensor 1, for example by screwing it in place, with appropriate devices such as holes, threads or bores 22 and 72 being provided. The mechanical section 71 is an integral part of the housing 52.

[0058] Furthermore, the housing 52 is designed for connection to a container. The housing 52 includes appropriate connection means for this purpose. The connection means can be, for example, a welded or flanged connection, e.g., made of stainless steel. Other configurations are also possible. The container holds the medium to be measured. The container can be, for example, a tank, boiler, pipe, pipeline, or similar.

[0059] The second optical-mechanical interface 60 initially comprises a second optical section 61, complementary to a first optical section 11, which is designed as a recess in the housing 52. This includes a third path 62, which receives transmitted light 5, couples it into the interior of the housing 52, and leads to a deflecting element 67. This further includes a fourth path 64, which receives transmitted light 5 from the deflecting element 67, leads it through a medium-flow region 68, whereby the transmitted light 5 is converted into received light 6 by the medium in the medium-flow region 68, and finally couples the received light 6 back out of the housing 52.

[0060] The deflecting element 67 deflects the transmitting light 5 by 180° and is designed as a prism.

[0061] The third and fourth paths 62, 64 are designed as two separate rod-shaped, in particular cylindrical, recesses. The third and fourth paths 62, 64 are designed to be complementary to the first and second paths 12, 14, so that the extensions fit precisely into the recesses. When the sensor 1 and the head 51 are assembled and mechanically fixed via the mechanical sections 11, 61, the two optical sections 11, 51 are positioned such that the transmitting light 5 and the receiving light 6 are ideally guided from the sensor 1 to the head 51 and vice versa. There are embodiments with lenses 16 (as shown) or windows.

[0062] The transmitting light 5 briefly exits the measuring head 51, passes through the medium-flow area 68, and then re-enters the housing 52 at the corresponding location. Transparent windows 66 separate the interior from the medium (for clarity, the reference symbol only refers to the left window). The medium-flow path 68 can be located in the third or fourth path 62, 64.

[0063] The Fig. 2a-2d Figure 51 shows the design of the measuring head as a submersible probe. The measuring head 51 is located in the medium to be measured and remains there. However, the measuring head 51 can be removed from the process and the sensor, for example, for maintenance purposes such as replacing seals.

[0064] Fig. 3a-3d They are systematically constructed in the same way, with the measuring head 51 designed as a flow probe. The medium flows through an inlet 69a and exits the flow probe at the outlet 69b. The area 68 through which the medium flows is located inside.

[0065] If validation or calibration of sensor 1 is required, it can be easily removed from the measuring head 51 in the process (e.g., in the form of a flow probe) by loosening the screw connection.

[0066] The measuring head 51 can be designed as a calibration and validation device.

[0067] This is shown by the Fig. 4a-e , whereby the Fig. 4a-d They are initially structured systematically in the same way as Fig. 2a-e.

[0068] The sensor 1 is therefore removed and the measuring head 51, in the configuration as a calibration and validation device, which also has a second optical-mechanical interface 60, is attached to the sensor 1.

[0069] One embodiment of the calibration and validation device is a cuvette holder. The holder 80, into which a cuvette 81 is inserted, is located at the medium-flow area 68. The cuvette 81 can be a standard, for example, a solid-state standard. The assembled state is shown. Fig. 4d , although the cuvette holder is not yet fully assembled.

[0070] Fig. 4e Figure 51 shows the configuration as a cuvette holder with an inserted sensor, with only the first optical section 11 visible. Some components are shown transparently to illustrate the assembly, especially of the optical sections 11 and 61. The sensor 1 can be calibrated, validated, and adjusted, if necessary, using the cuvette holder 51.

[0071] The calibration and validation device can also be designed as a cuvette changer, filter wheel, or filter changer. Different absorption values ​​can be set on the filter wheel, allowing various situations to be simulated by rotating it.

[0072] Finally, sensor 1 is removed from the calibration and validation device and can be reconnected to the other measuring head, for example the immersion probe or the flow probe. Bezugszeichenliste

[0073] 1 Process sensor 2 Housing of 1 3 Light source 4 Light receiver 5 Transmitting light 6 Receiving light 10 First optical-mechanical interface 11 First optical section 12 First path 13 First light guide 14 Second path 15 Second light guide 16 Lens 21 First mechanical section 22 Hole / thread for screws 51 Measuring head 52 Housing of 51 60 Second optical-mechanical interface 61 Second optical section 62 Third path 64 Fourth path 66 Window 67 Deflection element 68 Medium flow area 69a Inlet flow 69b Outlet flow 71 Second mechanical section 72 Hole / thread for screws 80 Mount 81 Cuvette 100 Measuring system

Claims

1. Optical measurement system (100) for measuring at least one measured variable of a medium in a container, wherein the optical measuring system (100) comprises: - an optical process sensor (1) for measuring the at least one measured variable of the medium, wherein the optical process sensor (1) comprises: ▪ a housing (2) of the optical process sensor (1), ▪ a light source (3) in the housing (2) of the optical process sensor (1) for emitting transmitted light (5), ▪ a light receiver (4) in the housing (2) of the optical process sensor (1) for receiving received light (6), and ▪ a first optical-mechanical interface (10), comprising ∘ a first optical section (11) that protrudes from the housing (2) of the optical process sensor (1), wherein the first optical section (11) comprises: a. a first path (12) and a first light guide (13), wherein the first light guide (13) is configured such that transmitted light (5) is guided via the first light guide (13) from the light source (3) into the first path (12), and transmitted light (5) is guided out of the housing (2) of the optical process sensor (1), wherein the first path (12) is configured as a rod-shaped extension that protrudes from the housing (2) of the optical process sensor (1), and b. a second path (14) and a second optical fiber (15), wherein the second light guide (15) is designed such that received light (6) is coupled into the interior of the housing (2) of the optical process sensor (1) and is coupled via the second light guide (15) from the second path (14) to the light receiver (4), wherein the second path (14) is configured as a rod-shaped extension that extends from the housing (2) of the optical process sensor (1) , wherein the first path (12) and the second path (14) are separate, side-by-side extensions, and ∘ a first mechanical section (21) that is an integral part of the housing (2) of the optical process sensor (1); and - a measuring head (51) comprising ▪ a housing (52) of the measuring head (51) that defines an interior space and is configured such that the optical process sensor (1) can be connected to the container, and ▪ a second optical-mechanical interface (60) comprising ∘ a second optical section (61) complementary to the first optical section (11) of the optical process sensor (1), comprising a. a third path (62) that transmits transmitted light (5) from received by the optical process sensor (1) and coupled into the interior of the housing (52) of the measuring head (51), wherein the third path (62) is configured as a rod-shaped recess that is complementary to and optical connection with the first path (12), and b. a fourth path (64) that receives transmitted light (5) and directs it into a region (68) where the medium is located, wherein the transmitted light (5) passes through the medium into received light (6), and wherein the fourth path (64) is configured to decouple the received light (6) from the housing (52) of the measuring head (51), wherein the fourth path (64) is formed as a rod-shaped recess that is complementary to and in optical communication with the second path (14), and wherein the region (68) in which the medium is located is configured as a further recess of the housing (52) of the measuring head (51) , and ∘ a second mechanical section (71) complementary to the first mechanical section (21) of the optical process sensor (1), which is an integral part of the housing (52) of the measuring head (51) is configured, wherein the second optical section (61) accommodates the first optical section (11) to establish an optical connection with a light path from a light source, a first light guide, a first path, a third path, a deflection element, a fourth path, a second path, a second light guide, and a light receiver and enables a mechanical connection between the optical process sensor (1) and the measuring head (51) via the first mechanical section (21) and the second mechanical section (71).

2. Optical measurement system (100) according to claim 1, wherein the optical process sensor (1) is a spectrometer.

3. Optical measurement system (100) according to claim 1, wherein the measuring head (51) is configured as an immersion probe.

4. Optical measuring system (100) according to claim 1, wherein the measuring head (51) is configured as a flow probe.

5. Optical measuring system (100) according to claim 1, wherein the measuring head (51) is configured as a calibration and validation device6. Optical measuring system (100) according to claim 5, wherein the calibration and validation device comprises a cuvette holder with a mounting for a cuvette, wherein the mounting comprises the region (68) in which the medium is located.

7. An optical measurement system (100) according to claim 5, wherein the calibration and validation device comprises a cuvette changer, filter wheel, or filter changer.

8. An optical measurement system (100) according to claim 1, wherein the mechanical connection is detachable, wherein the first mechanical section (21) and the second mechanical section (71) are configured such that a screw connection exists, wherein the first mechanical section (21) and the second mechanical section (71) comprise bores and / or threads for screws.

9. Method for calibrating and / or validating the optical process sensor (1) of the optical measurement system (100) according to claim 1, comprising the steps - removing the optical process sensor (1) from the measuring head (51), which is configured as a flow-through probe or immersion probe; - attaching the optical process sensor (1) to the measuring head (51), which is configured as a calibration and validation device; - calibrating and validating the optical process sensor (1) using the calibration and validation device; - Removing the optical process sensor (1) from the calibration and validation device; and - Reattaching the optical process sensor (1) to the flow probe or immersion probe.