THERMOMETER FOR CRYOGENIC APPLICATIONS

Abstract

A securement insert for securing a thermometer in a nipple of a tube comprises a holding element for securing the thermometer to the securement insert, and a stop that is embodied to prevent rotary movement relative to the tube. An arrangement having a thermometer and a securement insert is also disclosed. At least one component of the securement insert is embodied and/or arranged in such a manner that the securement insert is movable in the direction of a longitudinal axis of the nipple.

Claims

1-16. (canceled)

17. A securement insert for securing a thermometer in a nipple of a tube, comprising: a holding element for securing the thermometer to the securement insert; and a stop embodied to prevent rotary movement relative to the tube, wherein at least one component of the securement insert is embodied and/or arranged such that the securement insert is movable in the direction of a longitudinal axis of the nipple.

18. The securement insert as claimed in claim 17, further comprising: a basic body having a passageway for receiving the thermometer, wherein an exterior of the basic body is fitted to geometric dimensions of an interior of the nipple.

19. The securement insert as claimed in claim 18, wherein the basic body is embodied in the form of a hollow cylinder.

20. The securement insert as claimed in claim 18, further comprising: a circular spring element that is releasable insertable into the nipple or basic body.

21. The securement insert as claimed in claim 20, wherein the stop includes an elongated guide element secured to a wall of the nipple or basic body, and the stop engages in a component of the securement insert when the securement insert is introduced into the nipple.

22. The securement insert as claimed in claim 21, wherein the spring element includes an elongated slot, and wherein the guide element is secured in such a manner to a wall of the nipple or basic body that the guide element engages in the slot when the spring element is arranged in the nipple or basic body.

23. The securement insert as claimed in claim 18, wherein the stop comprises a screw threaded bolt.

24. The securement insert as claimed in claim 23, wherein the basic body has a circularly shaped floor on which is mounted a tube with an internal screw thread for receiving the screw threaded bolt.

25. The securement insert as claimed in claim 18, wherein the holding element includes a circularly shaped element in which the thermometer is securable.

26. The securement insert as claimed in claim 24, wherein the holding element is embodied in the form of a cylindrical element having a central, first passageway in which the thermometer is securable, and wherein an outer diameter of the cylindrical element is fitted to an inner diameter of the nipple or basic body.

27. The securement insert as claimed in claim 26, wherein the holding element includes a second passageway for producing a fluid contact between an internal volume of the tube and an internal volume of the thermometer.

28. The securement insert as claimed in claim 20, wherein the holding element is connected by force securement and/or by material bonding with the nipple, the basic body, or the circularly shaped spring element.

29. The securement insert as claimed in claim 28, wherein the holding element includes a strut that connects the holding element and the spring element.

30. The securement insert as claimed in claim 28, wherein the basic body and the holding element are connectable with one another by means of a screwed connection, wherein the holding element has a third passageway, and wherein the holding element and the basic body are connectable with one another by means of the screw threaded bolt of the stop, by means of a screw, or by means of an additional screw threaded bolt.

31. An arrangement for determining and/or monitoring temperature of a medium in a containment, comprising: a measuring insert with a temperature sensor for determining and/or monitoring temperature of the medium, and a protective tube for receiving the measuring insert, wherein the arrangement further includes a securement insert, including: a holding element for securing the temperature sensor to the securement insert; and a stop embodied to prevent rotary movement relative to the tube, wherein at least one component of the securement insert is embodied and/or arranged such that the securement insert is movable in the direction of a longitudinal axis of the nipple.

32. The arrangement as claimed in claim 31, further comprising: a pressure take off nipple.

Description

[0036] The invention and its advantageous embodiments will now be explained in greater detail based on the appended drawing, the figures of which show as follows:

[0037] FIG. 1 the source of vortex induced vibrations,

[0038] FIG. 2 a thermometer having a protective tube and a mechanical support,

[0039] FIG. 3 a first embodiment of a thermometer having a securement insert of the invention, and

[0040] FIG. 4 a second embodiment of a thermometer having a securement insert of the invention.

[0041] In the figures, equal elements are provided with equal reference characters.

[0042] FIG. 1 shows how vortices are shed from a cylindrical, conically tapering thermometer 1 exposed to a medium M flowing in a tube 2. Tube 2 is shown here by its wall. There develops in flow direction v of the medium M behind the thermometer 1 a comb-shaped pattern of the flow profile. As a function of the flow velocity v of the medium M, such can lead to vortex shedding, which can, in turn, cause the thermometer 1 to oscillate.

[0043] The vibrations are brought about mainly by two forces acting on the thermometer 1: a shear force in the y direction and a lifting force in the x direction, which add to form the flow-determined, total force F.sub.flow. The shear force causes oscillations with a frequency fs, while the lifting force causes oscillations with a frequency 2 fs. The frequency fs depends on the flow velocity v of the medium M and on various physical or chemical properties of the medium M such as its viscosity and density as well as on the geometry of the thermometer 1, such as its diameter, its length and the thickness of the wall of the protective tube. The closer the frequency fs is to the eigenfrequency of the thermometer 1 and the higher the flow velocity v of the medium M, the greater are the oscillation producing forces resulting therefrom. The thermometer 1 can be damaged by the action of these forces and the occurrence of vortex shedding. In the worst case, a complete failure of the thermometer 1 can occur. Such is referred to as a so-called resonance condition.

[0044] In order to reduce the sensitivity of thermometers to such vortex formation, such as above described, the design of the protective tube can be modified. However, the actions, which serve for optimizing the geometry of the thermometer 1 with respect to vortex shedding, and those, which serve for optimizing the thermometer 1 as regards temperature effects, especially temperature effects brought about by undesired heat drains, run basically in opposite directions.

[0045] Another way of preventing vortex induced oscillations of the thermometer 1 is using a mechanical support 4, such as shown in FIG. 2. The support 4 is introduced into a nipple 3 of the tube 2 and increases the eigenfrequency of the thermometer 1 by decreasing the free length of the thermometer 1.

[0046] Problematic in the case of such mechanical supports 4 is, however, that an effective mechanical coupling to the thermometer 1 cannot be assured at all times. Especially, mechanical expansions of the different components of the arrangement occurring upon temperature changes as a result of different coefficients of thermal expansion have made such solutions unreliable to this point in time.

[0047] The invention solves this problem using a securement insert 6, which is movable in parallel with a longitudinal axis L of the nipple 3. As a result of this movement in the direction of the longitudinal axis, temperature effects can be compensated, without influencing the mechanical coupling to the thermometer 1.

[0048] FIGS. 3 and 4 show two especially preferred embodiments of a securement insert 6 of the invention and an arrangement 7 of the invention. Tube 2 and nipple 3 are, in each case, embodied, by way of example, for application at low temperatures T and include, for example, in such case, a vacuum insulation (not separately shown).

[0049] In the case of the embodiment of FIG. 3, the securement insert 6 comprises a stop 8 in the form of an elongated guide element, which is welded to the interior of the nipple 3, as shown, for example, in FIG. 3a. Securement insert 6 further includes a circularly shaped spring element 9, whose geometric dimensions are likewise fitted to the dimensions of the nipple 3. The spring element 9 has a slot 9a, in which the stop 8 engages, when the spring element 9 is arranged in the nipple 3. The spring element 9 is, furthermore, connected via the strut 10 with the circularly shaped holding element 11, which serves for securing the thermometer 1. Stop 8 blocks rotary movement of the securement insert 6 in the nipple.

[0050] Movement S.sub.therm in the direction of a longitudinal axis L of the nipple is, in contrast, possible and serves for compensating temperature effects in the form of thermally induced forces F.sub.therm otherwise acting on the thermometer 1 and the securement insert 6. This is illustrated in FIG. 3b. The forces F.sub.therm result from different coefficients of expansion of the different components and the associated different mechanical expansions as a result of temperature changes. The forces F.sub.hold effected by the wall of the nipple 3 and the spring element serve for securing the holding element 11 against the thermometer 1, in order that thermometer 1 experiences, in turn, a reduced sensitivity to the forces F.sub.flow caused by the flow, such as described above in connection with FIG. 1.

[0051] A second example of an especially preferred embodiment of a securement insert 6 of the invention and an arrangement 7 of the invention is shown in FIG. 4 with views rotated 90° relative to one another. As evident from FIG. 4a, the securement insert includes a basic body 13 in the form of a hollow cylinder, which is fixed in the nipple 3. For example, the basic body 13 is welded to the nipple 3. The basic body 13 has, furthermore, a circularly shaped floor 14, in which is mounted an internally screw threaded tube 15 for receiving the screw threaded bolt 16, which is part of the stop 8. By means of the screw threaded bolt 16, the basic body 13 is connected by force securement, e.g. frictional securement, with the holding element 11, which is embodied in such case in the form of a cylindrical element. The holding element 11 has, such as shown in FIG. 4b, a first passageway 12a for receiving the thermometer 1, a second passageway 12b for producing a fluid contact between an internal volume of the tube 2 and an internal volume of the thermometer 1, as well as a third passageway 12c for securing the holding element 11 with the basic body 13 by means of the screw threaded bolt 15.

[0052] Also for this second variant of a securement insert, a movement in the longitudinal direction of the nipple 3 is possible, while a rotary movement is prevented by the stop 8. Correspondingly, as in the case of the embodiment of FIG. 3, forces F.sub.therm resulting from temperature effects and flow related forces F.sub.flow can be compensated.

[0053] In the embodiment of FIG. 4, the arrangement 7 further includes a pressure take off nipple 17 for measuring a pressure of the medium M. Such is enabled by the fluid contact between an internal volume of the tube 2 and an internal volume of the thermometer 1, which for the shown case is assured by the second passageway 12b.

REFERENCE CHARACTERS

[0054] 1 thermometer

[0055] 2 tube

[0056] 3 nipple

[0057] 4 mechanical support

[0058] 5 vacuum insulation

[0059] 6 securement insert

[0060] 7 arrangement

[0061] 8 stop

[0062] 9 spring element

[0063] 10 strut

[0064] 11 holding element

[0065] 12 passageways

[0066] 13 basic body

[0067] 14 floor of the basic body

[0068] 15 tube

[0069] 16 screw threaded bolt

[0070] 17 pressure take off nipple