Oven insulation arrangement

Abstract

An analytical device has an oven arrangement (1) with an oven (2), an insulation system, a ventilation system and a housing. The ventilation system has a first convection system that uses natural convection, arranged to keep the housing cool, as well as a second convection system that uses forced convection, arranged to reduce the temperature in the oven (2). In particular, the analytical device is a component of a Karl Fischer titration instrument.

Claims

1. An analytical device having an oven arrangement that comprises: an oven, a housing comprising a bottom, a wall element and a cover; where the wall element of the housing comprises bottom apertures that allow air to pass between the external environment and the lower region of the outer air chamber, and top apertures that allows air to pass between the upper region of the outer air chamber and the external environment; an insulation system, comprising: a base insulation, arranged in the housing, comprising a support system that supports the oven and having apertures; a lateral insulation jacket, that surrounds the oven and is in contact with the base insulation; and an inner capping, arranged on the oven to thermally decouple the oven and the cover of the housing, and a ventilation system comprising: a first convection system that is a natural convection system, configured to cool the housing; and a second convection system that is a forced convection system, configured to reduce the temperature within the oven, the second convection system comprising a bottom air chamber that is defined by the base insulation, the bottom of the housing and the wall element, an inner air chamber, arranged between the oven and the lateral insulation jacket, the inner air chamber connected with the bottom air chamber through the apertures of the base insulation, an intermediate air chamber, arranged between the lateral insulation jacket and the inner capping, the intermediate aft chamber connected with the inner air chamber and with the top apertures of the housing, and a ventilation device, arranged to draw aft into the bottom air chamber, such that an aft stream, driven by the ventilation device, moves from the bottom air chamber through the inner air chamber and the intermediate aft chamber towards the top apertures of the housing.

2. The analytical device of claim 1, wherein: the first convection system comprises an outer air chamber, arranged between the lateral insulation jacket and the wall element of the housing.

3. The analytical device of claim 2, wherein the outer air chamber surrounds the lateral insulation jacket, without contact between the lateral insulation jacket and the wall element.

4. The analytical device of claim 2, wherein the bottom apertures, the top apertures, or both, are each arranged aligned on horizontal lines in relation to the top and the bottom of the housing.

5. The analytical device of claim 1, wherein the ventilation device is connected with the bottom air chamber through an air connector, the ventilation device being arranged either inside the housing, outside the housing, or both.

6. The analytical device of claim 1, wherein the oven is separated from the lateral insulation jacket.

7. The analytical device of claim 1, wherein the base insulation comprises protuberances, arranged to support the oven.

8. The analytical device of claim 1, wherein the lateral insulation jacket surrounding the oven is a prefabricated piping system with an outer conduit insulated with at least one of: polyurethane foam, a filament wound fiberglass, extruded high-density polyethylene (HDPE) and combinations thereof.

9. The analytical device of claim 1, wherein the base insulation comprises hydrous phyllosilicate mineral.

10. The analytical device of claim 1, wherein the housing comprises polybutylene terephthalate or polypropylene.

11. The analytical device of claim 1, wherein the cover of the housing comprises thermoplastic.

12. The analytical device of claim 1, wherein the inner capping for thermal decoupling comprises polytetrafluoroethylene.

13. A Karl Fischer titration system comprising an analytical device according to claim 1.

14. The analytical device of claim 1 wherein the oven is used to evaporate a sample being analyzed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described in more detail hereinafter with reference to exemplary embodiments. However, the invention is not limited to these exemplary embodiments.

(2) FIG. 1 is a three dimensional view of a sampling system for an analytical device with an oven arrangement according to the invention;

(3) FIG. 2 is a three dimensional view of an oven arrangement according to the invention;

(4) FIG. 3 illustrates a three dimensional view of another oven arrangement according to the invention;

(5) FIG. 4 is a horizontal cross sectional view of the oven arrangement according to the invention; and

(6) FIG. 5 is a vertical cross sectional view of an oven arrangement according to the invention.

DETAILED DESCRIPTION

(7) The illustrations shown in the figures are schematics and similar or identical elements are provided with the same reference signs.

(8) FIG. 1 shows an analytical device 23 suitable to be used as part of a Karl Fischer titration system with an oven arrangement 1. It comprises a sample changer 25 that is here configured to hold and move up to thirty vials. The vials are not visible on this figure. By turning about its vertical central axis the sample changer 25 transfers each vial towards the oven arrangement 1. A lift system 24 transfers each vial individually downwards into the oven arrangement 1 which allows each sample to be heated within the oven arrangement 1. In a first step a first line brings a carrier gas in the oven and the oven is heated so that the sample can be evaporated and transferred via a second line 232 to a titration cell, in particular a Karl Fischer titration cell of a Karl Fischer titration system 233.

(9) FIG. 2 illustrates an oven arrangement 1 comprising a ventilation system and an insulation system within a housing 18. The housing 18 comprises a wall element 20, a bottom 19 and a cover 17, wherein the bottom 19 is connected with an air connector 4. The air connector 4 is connected with the housing 18, so as to provide a hermetically closed connection.

(10) The air connector 4 allows the connection of a ventilation device such as a fan or a pump and thus the drawing of an environmental air stream into respective from a bottom air chamber, located beneath a base insulation and an oven 2 (see also FIGS. 4 and 5).

(11) An inner capping 16 is arranged beneath the cover 17 of the housing 18 and in contact with the cover 17. The inner capping 16 prevents any direct contact between the oven 2 and the housing 18. The cover 17 and the inner capping 16 each comprise an aperture for introducing a sample vial into the oven 2.

(12) The wall element 20 comprises bottom and top apertures 21, 22. Bottom apertures 21 are aligned horizontally in relation to the bottom 19 of the housing 18, around the housing 8 in the lower part of the wall element 20, close to the bottom 19 of the housing 8. Top apertures 22 are aligned around the housing 18 in the upper part of the wall element 20, close to the cover 17.

(13) The bottom apertures 21 and the top apertures 22 are connected with an outer air chamber 8 (see FIGS. 4 and 5). The bottom apertures 21 allow an air exchange between the environmental air and the outer air chamber 8, for the natural air stream. The top apertures 22 allow air exchange between an outer air chamber 8 and an intermediate air chamber 9 and the environmental air for the natural and respectively the forced air stream (see FIGS. 4 and 5).

(14) FIG. 3 illustrates another oven arrangement 1 according to the invention. This oven arrangement 1 differs from the one shown in FIG. 2 in particular through the shape and form of the top and the bottom apertures 121, 122 of the housing 18. The top apertures 122 are oblong and arranged continuously on a horizontal line in respect to the bottom of the housing 18.

(15) The bottom apertures 121 are aligned on a horizontal line in respect to the bottom 19 of the housing 18 and have a round or oval shape.

(16) It is understood, that the top and/or bottom apertures of an oven arrangement in accordance with the invention can have any shape or form, in particular any combination of the shapes and forms shown in FIGS. 2 and 3.

(17) FIG. 4 shows a horizontal cross-sectional view of an oven arrangement 1. The oven 2 comprises a space for holding a sample or sample vial. The space between the lateral insulation jacket 11 and the oven 2 represents a base insulation 12 on which rests the oven 2. The base insulation 12 comprises apertures 15 allowing air passage from the bottom up.

(18) An outer air chamber 8 surrounds the lateral insulation jacket 11 and is in direct contact with the same. A wall element 20 closes off the outer air chamber 8, thereby leaving an inlet and an outlet opening for the air to enter and exit the outer air chamber. The wall element 20 rests on the bottom 19 of the housing 18, to which it is connected by material bridges as shown in FIGS. 2 and 3. The bottom 19 and the wall element 20 of the housing 18 can also be made as a single piece.

(19) An air connector 4 is configured to let air pass beneath the base insulation 12.

(20) FIG. 5 shows a vertical cross-sectional view of an oven arrangement 1 with a ventilation system and an insulation system, both of which are arranged within a housing 18. The housing 18 comprises a bottom 19, a wall element 20 and a cover 17. The insulation system comprises a lateral insulation jacket 11 resting on a base insulation 12. An oven 2 is arranged approximately over the middle of the base insulation 12. The base insulation comprises protuberances 14 creating a space 141 between the oven 2 and the base insulation 12.

(21) The ventilation system comprises a forced convection system, which comprises a ventilation device 3, a bottom air chamber 10, an inner air chamber 7, an intermediate air chamber 9 and an outer air chamber 8. The forced air stream 5 is illustrated with filled in arrows and streams moved by the ventilation device 3 from the bottom air chamber 10 through the inner air chamber 7 and the intermediate air chamber 9 into the outer air chamber 8, which comprises top apertures 22 through which the heated up air can exit outer air chamber 8.

(22) The base insulation 12 is arranged in the bottom 19 of the housing 18. The base insulation 12 is in continuous contact with the wall element 20. The base insulation 12 comprises a support system 13 letting a free room between the base insulation 12 and the bottom 19 of the housing 18. The free room is defined by the bottom 19, the wall element 20 and the insulation base forms the bottom air chamber 10. Due to minimal contact between the support system 13 and the bottom 19 of the housing 18, the support system 13 prevents heating up of the bottom of the housing 19.

(23) The oven 2 rests on the base insulation 12 and is surrounded by the lateral insulation jacket 11. The oven 2 is cylindrical and rests on protuberances 14 rising up from the top of the base insulation 12, so that the bottom surface of the oven 2 is only partially in contact with the base insulation 12 and a space 141 is created beneath the bottom of the oven 2. This allows the forced and/or natural air stream to circulate through said space, thereby taking away the heat dissipating from the oven into said space. The oven 2 is surrounded with the lateral insulation jacket 11, in such a way that the lateral insulation jacket 11 and the oven 2 are separated by the inner air chamber 7.

(24) The ventilation device 3 is arranged outside the housing and is connected to the housing through an air connector 4. The air connector 4 is arranged below the base insulation 12, so that the ventilation device 3 draws and directs environmental air from underneath the base insulation 12 into the bottom air chamber 10, which is delimited by the bottom 19, the wall element 20 and the base insulation 12. The base insulation 12 comprises apertures 15 allowing the air stream to flow from the bottom air chamber 10 into the inner air chamber 7.

(25) The natural air stream 6 is illustrated with the contoured arrows, for which environmental air flows through the lower apertures 21 into the outer air chamber 8, which it exits through the top apertures 22. The air movement of the natural air stream 6 is facilitated by heat dissipating from the oven 2 into the outer air chamber 8, which is there taken up by the passing natural air stream 6, which thereby removes the heat from the oven arrangement.