Retractable assembly for immersion, flow and mounted measuring systems in analytical process technology

Abstract

The present disclosure discloses a retractable assembly for immersion, flow and mounted measuring systems in analytical process technology for receiving a sensor which is designed to measure at least one measurement variable of a medium in a container, comprising: a substantially hollow-cylindrical housing comprising a housing wall, a service chamber which is formed in the interior in a region of the housing, and a dip tube which is axially movable in the housing between a service position moved out of the medium and a process position moved into the medium, the dip tube being positioned in the service chamber in the service position, the sensor being receivable in the dip tube, wherein at least one optical window is arranged in the housing wall in the region of the service chamber.

Claims

1. A retractable assembly for immersion, flow and mounted measuring systems in analytical process technology for receiving a sensor which is designed to measure at least one measurement variable of a medium in a container, comprising a substantially cylindrical housing with a housing wall, a service chamber which is formed in the interior in a region of the housing, and a dip tube which is movable axially in the housing between a service position moved out of the medium and a process position moved into the medium, the dip tube being positioned in the service chamber in the service position, the sensor being receivable in the dip tube, wherein at least one optical window is arranged in the housing wall in the region of the service chamber.

2. The retractable assembly of claim 1, wherein the window is joined to the housing wall using gluing, flanging, pressing, clamping, welding or screwing.

3. The retractable assembly of claim 1, wherein the window is made of glass.

4. The retractable assembly of claim 1, wherein the window is lens-shaped or comprises a lens.

5. The retractable assembly of claim 1, wherein two windows arranged opposite one another are mounted in the housing wall.

6. The retractable assembly of claim 1, wherein the service chamber comprises interior lighting.

7. The retractable assembly of claim 1, wherein the service chamber comprises a sensor for fill level detection.

8. The retractable assembly of claim 1, wherein the window is circular.

9. The retractable assembly of claim 8, wherein the diameter of the window is 1 to 3 cm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) What was described above is explained in more detail based on the following figures.

(2) FIG. 1 shows the claimed retractable assembly.

(3) FIG. 2 shows the claimed retractable assembly in cross-section.

(4) FIGS. 3 a/b show the claimed retractable assembly in cross-section, with FIG. 3a showing the overview and FIG. 3b showing an enlarged view.

DETAILED DESCRIPTION

(5) In the figures, the same features are identified by the same reference signs.

(6) “Top,” “above,” and related terms within the meaning of this present disclosure mean facing away from the measuring medium 14. “Bottom,” “below,” and related terms within the meaning of this present disclosure mean facing the medium 14.

(7) The claimed retractable assembly is denoted in its entirety by reference sign 1 and is shown in FIGS. 1 to 3. The retractable assembly 1 consists of a substantially cylindrical housing 2 which can be connected to a container 15 by means of a connecting means 13. The housing 2 is formed by the housing wall 2a. The connecting means 13 can be, for example, designed as a flange connection, made of, for example, stainless steel. However, other embodiments are possible. The measuring medium 14 to be measured is located in the container. The container 15 can be, for example, a tank, boiler, tube, pipeline or the like.

(8) FIG. 1 shows the retractable assembly 1 in the process position. This is explained in more detail below. FIG. 2 shows the retractable assembly 1 in the service position.

(9) A dip tube 3 is guided inside the housing 2. A sensor 16 is arranged inside the dip tube 3. The sensor 16 is connected to the dip tube 3 by a receptacle, which is not described in greater detail, for example by way of a screw connection. The sensor 16 within the meaning of this present disclosure includes sensors for measuring one or more physical or chemical process variables. These are, for example, the pH value, also via an ISFET, redox potential, absorption of electromagnetic waves in the medium 14, for example with wavelengths in the UV, IR, and/or visible ranges, oxygen, conductivity, turbidity, concentration of metal and/or non-metal materials, or temperature. The sensor 16 has access to the medium 14 via an opening 8 in the dip tube 3. In this case, the opening 8 is designed in such a way that it is open in the flow direction, that is, that the measuring medium 14 optimally flows to the sensor 16, such as, when the retractable assembly 1 is used in a pipeline.

(10) The sensor 16 is connected to the channel 19. The cable, in turn, is connected to a transmitter, which is not shown.

(11) The dip tube 3 can be produced from various materials. The prior art discloses dip tubes 3 made of steel or stainless steel. However, applications, in which highly resistive materials are used, are common, such as, in the chemical industry. The dip tube 3 can thus also be made of a plastic, such as polyether ether ketone (PEEK), polytetrafluorethylene (PTFA), a perfluoroalkoxy polymer (PFA), another plastic or resistant metals, such as Hastelloy. A ceramic may also be used. Another option is the use of one or more coatings of the aforementioned polymers. The same is true for the housing 2.

(12) The dip tube 3 is mounted so as to be axially displaceable in the direction of the medium 14, or in the direction facing away from the medium 14, along the central axis L. The dip tube 3 can be moved between the service position (shown in FIG. 2) retracted into the housing 2 and the process position (shown in FIG. 1) extended out of the housing 2. The measurement takes place in the process position. The sensor 16 has access to the medium 14 through the cage-like opening 8 in the dip tube 3. A wide variety of service tasks, such as cleaning or calibration, are performed in the service position. Flushing/cleaning/calibration and/or sterilization medium can be admitted into the service chamber 11 through the connection 7, see below). The flushing/cleaning/calibration and/or sterilization medium can be liquid or gaseous. The liquid can drain again through the corresponding connection 22, which can be positioned at both an axial and radial offset from the connection 7. The flushing direction can also be reversed.

(13) The displacement of the dip tube 3 is performed by a drive device 18 located above the service chamber 11. The drive 18 is part of the housing 2. The housing 2 comprises a housing interior 12. The movement is carried out, for example, by an automatic drive, such as by supply energy. If supply energy is introduced through the connection 4, the dip tube 3 moves from the service position into the process position. The connection 5 then serves as an outlet. If supply energy is introduced through the connection 5, the dip tube 3 moves from the process position into the service position. The connection 4 then serves as an outlet. Pneumatic, hydraulic or electric drives are, for example, known from the prior art. The shown retractable assembly uses a pneumatic drive. A manual movement is likewise possible. The process of displacing the dip tube 3 is explained in more detail below by means of a pneumatic drive.

(14) A piston 24 (see FIG. 3a) is firmly connected to or an integral part of the dip tube 3. The piston 24 is designed, for example, as an annular piston and forms part of the drive 18. The piston 24 divides the drive portion of the housing interior 12 into an upper region and a lower region. The dip tube 3 can be moved via the connection 4 into the upper region and via a connection 5 into the lower region above or below the piston: When compressed air is brought into the upper region through the connection 4, the dip tube 3 moves in the direction of the medium 14, wherein air from the lower region simultaneously flows through the connection 5. Air can also be actively drawn from the lower region in order to support the movement in the direction of the medium 14. When compressed air is brought into the lower region through the connection 5, the dip tube 3 travels away from the medium 14, wherein air from the upper region simultaneously flows through the connection 4. Air can also be actively drawn from the upper region in order to support the movement.

(15) Corresponding seals (not shown) can be used to ensure that compressed air does not escape and is only conducted through the connections 4, 5.

(16) The connections 4, 5 are attached laterally to the housing 2. The connection 4 can be located above the piston (dip tube 3 in service position), the connection 5 can be located below the piston (dip tube 4 in process position). It is conceivable for both inlets 4, 5 to be located on the housing 2 above or below the piston and, for proper functioning, for a line to be guided into the respective other region in the interior of the housing 2. FIG. 1 shows that connections 4, 5 are arranged next to one another above the piston (service position). FIG. 2 shows them arranged one above the other. A corresponding line for guiding the connection 5 into the lower region is located in the interior of the housing 2. The connections 4, 5 do not necessarily have to be located in the same frontal plane.

(17) The service chamber 11 is located in the interior 12 of the housing 2 and is formed by the wall 2a. The service chamber 11 is located directly above the connecting means 13 in the example. There is an inlet 7 and an outlet 22 to the service chamber 11.

(18) If the dip tube 3 is in the service position, a portion of the dip tube 3, for example, the sensor 16, is located in the service chamber 11 for flushing, cleaning, calibrating, sterilizing, etc. The closure element 9 for process separation is located at the lower end of the dip tube 3. The closure element 9 seals off the service chamber 11 from the process, and thus from the measuring medium 14. The measuring medium may be hot, toxic, caustic, carcinogenic or otherwise harmful to humans and the environment. Combinations of these medium properties are also usually present in chemical plants. It must therefore be ensured that the closure element 9 seals reliably and permanently. For this purpose, various sealing devices are attached to the housing 2; such as, for example, one or more medium seals 10 are used. In the depicted embodiment, the medium seal 10 is arranged on the housing 2. Alternatively, the medium seal 10 may be arranged on the lower end region of the dip tube 3 (not shown).

(19) At least one seal 17, in the example two seals 17, 23, is arranged on the upper region of the dip tube 3. The seal 17, 23 seals off the service chamber 11 from the drive device 18, particularly when moving from the service position to the process position and vice versa. In the service position, the upper seal 17 is arranged above the connection 22 and the lower seal 23 is arranged at the same height or below the connection 22.

(20) FIGS. 3a and 3b show a retractable assembly 1 in cross-section and, in comparison with FIG. 2, in a view rotated about the axis L. The connections 7, 22 cannot be seen here.

(21) The retractable assembly 1 with the service chamber 11 comprises one or more windows 6 in the wall 2a. “Window” shall be understood to mean not only plane-parallel plates but also prismatic, spherical, aspherical or free-formed transparent bodies, e.g. also matched to the optical refractive index of the medium 14. The window 6 is mounted at the level of the sensitive element of the sensor 16. If the sensor 16 is designed as a pH sensor, the window 6 is arranged so as to be at the level of the pH-sensitive membrane.

(22) The window 6 is joined to the wall 2a by gluing, flanging (flange-mounting), pressing, clamping, welding and/or screwing. It is circular and has a diameter of 1.5 cm, for example. The maximum size of the window 6 is adapted to the available installation space of the service chamber 11.

(23) The window 6 is made, for example, of glass, more precisely of a borosilicate glass, soda lime glass, aluminosilicate glass, one or more plastic materials, such as, PA, PC or PMMA, or window glass.

(24) The window 6 must be transparent to the radiation to be transmitted through it. For example, if the user wishes to check the content of the service chamber 11 by a simple visual inspection, the window must be transparent to visible light. This is illustrated in FIG. 3b by the eye.

(25) Alternatively, a camera can also be connected to the window 6. This may be advantageous if the assembly 1 is attached in locations that are difficult to access. The camera can be designed as an infrared camera, the choice depending on the corresponding medium 14, and the window 6 must then accordingly be transparent to infrared radiation.

(26) If the service chamber 11 is to be examined by a simple visual inspection, additional illumination 20 in the service chamber is expedient. This may be an LED mounted in the wall 2a.

(27) In one embodiment, a sensor for detecting the fill level is mounted in the service chamber 11, in a simple embodiment as a float 21 which is, for example, ball-shaped.

(28) It is also possible for more than one window to the service chamber 11, for example two windows, to be mounted. These are then arranged at an angle of 90° or 180° with respect to each other.

(29) A variant with three windows (angle of 120° with respect to each other) or four windows (angle of 90° with respect to each other) is also possible.

(30) In one embodiment, multiple windows, for example two windows arranged opposite one another, are mounted in the wall 2a.

(31) When a window is located on the opposite side of the chamber 11, an LED is mounted behind it.

(32) At least one of the windows is lens-shaped or comprises a lens and thus provides an enlarged view. This allows an even more detailed observation of the sensor surface.

(33) In one embodiment, one or more windows are also arranged on a rotatable ring.

(34) In one embodiment, one of the windows 6 comprises a reflection light barrier. A reflection element, which is introduced in a defined manner and located in front of the reflection light barrier in the service position, is provided on the sensor 16. It can thus be automatically established whether the sensor 16 has been correctly extended, the sensor head is basically still there (sensor breakage), and/or whether excessive contamination (possibly after the flushing process) is present.