Furnace for an analyzer, analyzer, and method for analyzing a sample in a furnace

Abstract

The invention relates to a furnace (2) for an analyzer (1) for analyzing a sample, comprising a combustion tube (4), wherein the sample can be introduced into the combustion tube (4), preferably by means of a crucible (6), and can be at least partially combusted in the combustion tube (4), preferably with the addition of an oxidizing agent. According to the invention, a guide tube (7) is provided, which surrounds at least portions the combustion tube (4), wherein a guide channel (8) for combustion products released in the combustion tube (4) is formed between the guide tube (7) and the combustion tube (4).

Description

[0001] Oven for an analyzer, analyzer and method for analyzing a sample in an oven

[0002] The present invention relates to a furnace for an analytical instrument for analyzing a sample, comprising a combustion tube, wherein the sample can be introduced into the combustion tube, preferably by means of a crucible, and can be at least partially combusted in the combustion tube, preferably with the addition of an oxidizing agent, and wherein combustion products released in the combustion tube can be transported to an analysis channel of the analytical instrument, preferably by means of a carrier gas. The combustion gases do not necessarily have to be transferred directly into the analysis channel. The combustion gases can also first be absorbed by a ballast volume and, preferably, transported from there via the aliquot into the analysis channel.

[0003] Furthermore, the present invention relates to an analytical instrument with an oven of the aforementioned type.

[0004] Finally, the invention relates to a method for providing combustion products of a sample by burning the sample in a combustion tube of a furnace for subsequent analysis of the combustion products in an analytical instrument, wherein the sample is introduced into the combustion tube, preferably by means of a crucible, wherein the sample is at least partially combusted in the combustion tube, preferably with the addition of an oxidizing agent, and wherein combustion products of the sample released in the combustion tube are transported, preferably by means of a carrier gas, in an exit direction, preferably downwards, to an outlet opening of the combustion tube. The outlet opening is preferably located at one end of the combustion tube. Depending on the geometry of the combustion tube, the outlet opening can also be located at the top or in an upper region of the combustion tube, for example in U-shaped combustion tubes.

[0005] Ovens of this type, as well as analytical instruments incorporating such an oven, are known from the prior art and are used in particular for the combustion analysis of samples. In combustion analysis, a sample is heated in an oven, for example with the addition of oxygen, so that the sample oxidizes or combusts. For this purpose, the sample is usually placed in a porous or gas-permeable crucible, which in turn is inserted into a combustion tube provided for this purpose in the oven. The combustion products formed when the sample is heated can escape through the crucible and are preferably transported from the oven to an analysis channel of the analytical instrument and through the analysis channel by means of a carrier gas. The combustion gases do not necessarily have to be transferred directly into the analysis channel. They can be absorbed by a ballast volume and from there transported via the aliquot into the analysis channel.In the analysis channel, an elemental analysis is preferably carried out, in which the concentration of certain chemical elements, e.g. hydrogen, nitrogen, carbon and / or sulfur, is determined using appropriate detectors or analyzers.

[0006] The solutions known from the state of the art have several disadvantages.

[0007] For example, components that come into contact with the combustion products, especially metallic components, are subjected to considerable stress due to the sometimes acidic or corrosive and / or highly heated combustion products. This particularly affects components located directly at the outlet of the combustion tube or downstream of it. Consequently, a comparatively high level of wear is observed in such components within the furnace. The same applies to seals or other internal components located downstream of the combustion tube, which are exposed to significant thermal and / or chemical stresses, especially at the lower end of the combustion tube.

[0008] Furthermore, it is necessary to connect the furnace, or rather its combustion tube, to an analysis channel of the combustion tube in a fluid-tight and gas-tight manner. In known solutions, this is achieved primarily by externally sealing the combustion tube with bolted components. This solution has a complex design, and handling, particularly regarding sealing and the replacement or removal of components, for example for maintenance, is very time-consuming and cumbersome. Moreover, there is a risk of coming into contact with hazardous substances in the area of ​​the furnace outlet.

[0009] The disadvantages of the prior art are to be overcome with the present invention.

[0010] The object of the present invention is to provide a furnace, an analytical instrument and a method for providing combustion products of a sample by combustion of the sample in a combustion tube of a furnace, which are characterized by low-wear and / or reliable operation and / or safe and in particular versatile handling as well as a simple structural furnace design.

[0011] Furthermore, the possibility of easily sealing the combustion tube and easily replacing or removing components should be provided.

[0012] In particular, the invention is intended to enable trouble-free analysis of acidic samples without excessive wear and tear on the oven and equipment parts involved in sample analysis.

[0013] The above problem is solved by an oven according to claim 1, an analysis device with an oven according to the invention according to claim 14 and a method according to claim 15. Advantageous further developments are the subject of the dependent claims.

[0014] The invention proposes a furnace design that differs from the prior art in the case of a furnace of the type mentioned at the outset, in particular in the lower area of ​​the combustion tube, i.e. at the outlet of the combustion tube for the combustion products.

[0015] In a furnace according to the invention, a guide tube is provided that surrounds the combustion tube at least partially and / or in sections, so that an annular gap is formed between the guide tube and the combustion tube, serving as a guide channel for combustion products released in the combustion tube. The diameter of the guide tube is dimensioned such that the combustion tube can be easily inserted into the guide tube and that sufficient distance exists between the two tubes to allow combustion products, together with any carrier gas used, to be conveyed via the guide channel formed between them. It is advantageous if the guide tube surrounds the combustion tube coaxially, so that the annular gap has a uniform clear width along the entire length of the guide channel.

[0016] In operation, after the sample is combusted in the crucible, the combustion gases initially exit the burner tube via a burner tube outlet, particularly at the lower edge of the burner tube, and then primarily in an axial direction. However, a lateral or radial exit of the combustion products at the lower edge of the burner tube is also possible. Instead of being directly routed for analysis, the combustion products are guided away from the burner tube outlet via the guide channel formed between the burner tube and the outer guide tube. They can then exit the guide tube through a corresponding outlet opening at a distance from the burner tube outlet. Subsequently, the combustion products can be forwarded via an analysis channel or line of an analytical instrument for sample analysis.The combustion gases do not necessarily have to be transferred directly into the analysis channel after exiting the guide tube. They can be absorbed by a ballast volume. From the ballast volume, the combustion gases can be transported via the aliquot into the analysis channel.

[0017] The conveyance of the combustion products from the combustion tube outlet via a guide channel to an outlet point of the guide channel spaced apart from the combustion tube outlet, as provided for in the invention, is associated with a number of advantages:

[0018] In particular, the conveyance or diversion of the hot, especially gaseous, combustion products from the combustion tube outlet via the guide channel, as provided for in the invention, allows for a novel furnace design in the lower region of the combustion tube in which no acid-sensitive, especially metallic, components come into contact with hot combustion products immediately after exiting the combustion tube. Thus, a novel design is possible that permits the trouble-free examination of acidic samples without subjecting the furnace and its periphery to excessive wear. The same applies to the seals used, which, in furnace designs known from the prior art, are additionally subjected to considerable thermal stress at the lower end of the combustion tube.Furthermore, in particular, according to the invention a furnace construction that deviates from the prior art is possible in which the lower end of the combustion tube does not have to be sealed with tightly clamped outlet elements.

[0019] Furthermore, it is advantageous that the conveyance of the combustion products from the burner tube outlet via the guide channel allows for at least a certain degree of cooling of the combustion products. This cooling of the combustion products can slow down or prevent corrosive effects, particularly hot gas corrosion. In addition, a more advantageous furnace design is possible, allowing for significantly simplified handling during furnace operation.

[0020] The term "guide tube" is preferably to be understood broadly and is not limited in particular to tubes with a circular cross-section. However, a design of the guide tube with a circular cross-section is preferred.

[0021] In the context of the present description of the invention, position designations such as "top" or "bottom" and the like refer in particular to an operating state of the furnace in which the combustion tube is at least substantially vertically oriented.

[0022] The combustion tube can have a preferably axial outlet opening at one end for the combustion products. The combustion products flow from the combustion site inside the combustion tube in an outlet direction, preferably downwards, to the outlet opening and, after passing through the outlet opening and being deflected, enter the guide channel. In the guide channel, the combustion products can then be conveyed in a guide direction opposite to the outlet direction, preferably upwards.

[0023] In particular, deflecting the combustion products after they have passed through the combustion tube outlet and directing them via the guide channel against the outlet direction can lead to the advantages described above.

[0024] Accordingly, the inventive method proposes to redirect the combustion product flow after it has passed through the outlet opening of the combustion tube, particularly at the outer edge of the combustion tube end, from the outlet direction in which the combustion products flow towards the combustion tube outlet, and then to direct it away or further in a guide direction against the outlet direction, preferably upwards, in the guide channel.

[0025] Preferably, the combustion products are guided parallel to the combustion tube. In particular, the guide tube and the combustion tube form a tube-within-a-tube arrangement with an annular gap between them serving as a guide channel. This results in a simple structural design and simplified handling of the furnace according to the invention.

[0026] In particular, the combustion products are guided in the guide channel along an outer surface of the side wall of the combustion tube and / or along an inner surface of the side wall of the guide tube.

[0027] According to a particularly preferred embodiment of the invention, a furnace design is provided in which no internal components or parts restricting the clear cross-section of the combustion tube are provided in the area of ​​the outlet opening of the combustion tube. The outlet area of ​​the discharge opening can then correspond at least substantially to the inner, clear cross-sectional area of ​​the combustion tube.

[0028] In particular, no tightly clamped outlet elements are provided at the combustion tube outlet. This prevents direct contact between the hot combustion products at the combustion tube outlet and metallic internals and / or components.

[0029] Particularly preferably, the combustion tube is open axially at the combustion tube outlet, and the guide tube is closed at one end adjacent to the combustion tube outlet, preferably at the lower end. This results in a structurally simple and maintenance-friendly design, with the guide tube being closed at one end to prevent combustion products from escaping into the environment adjacent to the combustion tube outlet.

[0030] The guide tube can have an axial end wall or base at the end adjacent to the combustion tube outlet, which closes the guide tube axially or in the direction of combustion product discharge. In particular, a side wall of the guide tube and the end wall are formed as a single piece. However, it is also possible for the guide tube end to have a removable or openable closure to provide access to the interior of the guide tube, for example, for cleaning purposes.

[0031] A further preferred embodiment provides that a dead space is formed within the guide tube, below the combustion tube. The volume of the dead space depends on the axial arrangement of the guide tube relative to the combustion tube, in particular on the axial distance of the combustion tube end from an axial end wall that closes the guide tube at the end. The dead space forms a receiving and collecting space for the combustion products after they have passed through the combustion tube outlet.

[0032] In this context, according to the invention, a receiving space for a functional material and / or a functional element can be provided and / or formed, which is arranged downstream of the outlet opening of the combustion tube in the outlet direction of the combustion products, in particular wherein the receiving space is formed between an end wall of the guide tube and the adjacent end of the combustion tube.

[0033] In particular, the receiving space may contain a reaction reactant for the reaction with corrosive, especially acidic, components of the combustion products, for example steel wool, and / or a catalyst material and / or a filter material as a functional material.

[0034] This can lead to a reaction and / or filtration of the combustion products, especially gaseous ones, in the presence of the functional material and / or in reaction with the functional material, even before the combustion products, especially gaseous ones, are conveyed into the guide channel.

[0035] For example, steel wool can be used as a functional material to react with acidic components of the combustion products.

[0036] A functional element can also enable particle filtration of the combustion products. For example, particle filtration using glass wool or quartz wool is possible.

[0037] A mixture or combination of different functional materials and / or the use of a multi-stage filter element as a functional element may also be provided.

[0038] It is advantageous if the receiving chamber is sufficiently far removed from the point of sample combustion so that the effectiveness of the functional material and / or functional element is largely prevented by high temperatures in the combustion tube. For example, if steel wool as a functional material or a functional element containing steel wool is positioned too close to the combustion site, for instance too far upstream in the combustion product stream, this can lead to the steel wool melting.

[0039] Gaseous combustion products can have a temperature at the burner tube outlet in the range of 500 to 1,000°C, preferably 600 to 800°C, more preferably 700 to 750°C, and particularly preferably approximately 720°C. These temperatures are to be understood in particular in relation to a gas flow rate in the range of 100 to 300 l / h, preferably 200 to 280 l / h, and particularly approximately 260 l / h.

[0040] In particular, the guide tube is designed to have an inwardly curved, preferably radially symmetrical, shape or end wall with a convex curvature preferably directed inwards towards the combustion tube outlet at one end of the guide tube and adjacent to an outlet opening of the combustion tube. The combustion products or combustion gases exiting the combustion tube or the outlet opening thus encounter the curvature, particularly in the center, and can be deflected radially and towards an inner surface of the guide tube. This can promote the formation of turbulence and lead to a homogenization of combustion products, especially gaseous ones.

[0041] With regard to the high thermal and chemical resistance of the furnace construction according to the invention, it is advantageous if the guide tube is made of glass, in particular quartz glass, and / or comprises such a material. A guide tube made of quartz glass is characterized by high acid resistance. In principle, the guide tube could also be made of metal, but this would result in lower acid resistance and higher heat dissipation from the furnace compared to a guide tube made of quartz glass.

[0042] It may also be advantageous if the guide tube and the burner tube are made of the same material or have the same material composition.

[0043] It is advantageous if the guide tube extends over a large portion of the length of the combustion tube, preferably over more than 80% of its length, and more preferably over more than 90%. This allows for an advantageous extension of the combustion product flow path in the guide channel while requiring minimal space. Alternatively or additionally, the combustion tube can extend beyond the guide tube at an end facing away from the outlet opening, preferably at the upper end, in a direction opposite to the combustion product exit direction, preferably upwards. This provides a structurally simple method for sealing and / or supporting the combustion tube and / or the guide tube.

[0044] The guide tube can extend beyond the outlet opening of the combustion tube at its end facing the outlet opening, preferably at the lower end, in the direction of combustion product discharge. This provides a simple way to deflect the combustion products after they exit the combustion tube on an inner surface of the guide tube and to create a receiving area for the functional material.

[0045] The guide tube can be sealed against the environment at the end opposite the combustion tube outlet. This prevents combustion products from escaping into the environment in this area.

[0046] In particular, the guide tube can be mounted and / or fixed to the furnace via one end of the guide tube, especially an upper end. For this purpose, the furnace can have a mounting component connected to it with a corresponding mounting geometry. The end of the guide tube can then be sealed against the environment in the area of ​​the mounting geometry and clamped against the mounting component, especially by means of at least one sealing element.

[0047] To convey the combustion products from the guide tube to an analyzer, in particular into an analysis channel, the guide tube can have at least one, in particular radial, outlet opening for the combustion product stream. Preferably, the outlet opening is located in a side wall of the guide tube. As already explained above, the combustion gases can also first be absorbed by a ballast volume and from there transported via the aliquot into the analysis channel.

[0048] Preferably, the outlet opening of the guide tube is provided at the end of the guide tube opposite the outlet opening of the combustion tube and / or above a crucible inserted into the combustion tube and / or above a crucible holder in the combustion tube. This allows for an advantageous length of flow path for the combustion products in the guide channel while requiring minimal space.

[0049] In particular, the guide tube is designed for connection to the analysis channel in the area of ​​the outlet opening, and in particular, the guide tube is sealed against the environment in the area of ​​the outlet opening and / or in the area of ​​a tube opening at the end of the guide tube, in particular by means of at least one sealing element. The combustion gases can also be absorbed by a ballast volume and transported from there into the analysis channel.

[0050] According to another preferred embodiment, a cooling geometry, in particular cooling fins, is provided in the area of ​​the outlet opening of the guide tube, especially in the upper section of the guide tube. A cooling gas flow can surround the cooling fins. This further reduces the temperature of the combustion products at the outlet of the guide channel.

[0051] A cooling device may also be provided for cooling the guide tube, in particular by rinsing it with a cooling fluid.

[0052] To assist the gas exit from the guide tube via the outlet opening and / or to lengthen the flow path and / or to influence the flow conditions in the guide channel, a surface structuring of at least one tube wall of the guide tube and / or the combustion tube, in particular a recess introduced into the tube wall, such as a groove, and / or a projection and / or at least one flow element inserted and / or arranged in the guide channel, in particular a spiral ring element, may be provided in the area of ​​the guide channel.

[0053] Particularly preferred is the insertion of the combustion tube and / or elements or internal components engaging in the combustion tube, such as a feed lance for crucibles and / or samples, into the guide tube via a guide tube end arranged opposite the outlet opening of the combustion tube, particularly an upper one, especially wherein the guide tube is already in an inserted and / or permanently installed state with the furnace. The furnace according to the invention can thus preferably be loaded and maintained completely or almost completely via the guide tube end, particularly from above. In particular, the insertion or removal of the combustion tube and the elements engaging in the combustion tube, for example a feed lance for crucibles and / or samples, can be carried out through an opening in the guide tube or via the guide tube end. This eliminates the need to disassemble the furnace.the furnace arrangement for removing the combustion tube and elements that engage with the combustion tube, for example for maintenance or cleaning purposes.

[0054] According to a particularly preferred embodiment, the guide tube has an inwardly projecting support for the burner tube, preferably wherein the burner tube rests on the support or is supported via the support when inserted into the guide tube.

[0055] In an advantageous embodiment, the design of the outer guide tube can include a plurality of projections in its lower region, which extend radially inwards from the inner wall into the interior of the guide tube. During assembly, the combustion tube is then inserted into the guide tube until it abuts against or rests on the projections.

[0056] In particular, stop pins and / or stop ribs are provided in the guide tube to hold the combustion tube; these are surrounded by the combustion product stream as it enters the guide channel. This can contribute to the formation of advantageous flow conditions in the guide channel.

[0057] The aspects and features mentioned above, as well as other aspects and features arising from the requirements and the following description, can be implemented independently of each other and in various combinations.

[0058] Further advantages, features, properties and aspects of the present invention will become apparent from the claims and the following description of a preferred embodiment with reference to the drawings. The drawings show:

[0059] Fig. 1 is a schematic representation of an analytical instrument according to the invention; Fig. 2 is a sectional view of an oven according to the invention;

[0060] Fig. 3 shows an enlarged lower section of the furnace from Fig. 2, in which a combustion tube of the furnace is shown with a guide tube surrounding the combustion tube, closed on the underside to form a guide channel;

[0061] Fig. 4 shows a cross-section of the guide channel formed between the combustion tube and the guide tube from Fig. 3;

[0062] Fig. 5 shows an enlarged section of the furnace from Fig. 2 in the area of ​​an upper guide tube end of the guide tube and an inlet opening of the combustion tube;

[0063] Fig. 6 shows an exploded view of the furnace according to the invention, including the combustion tube and the guide tube.

[0064] Fig. 7 shows a further exploded view of the furnace according to the invention, including a lock and a holding component of the furnace.

[0065] In the figures, which are sometimes not to scale and merely schematic, the same reference symbols are used for identical or similar parts, whereby corresponding or comparable properties and advantages can be achieved even if a repeated description is omitted.

[0066] Fig. 1 schematically shows an analytical device 1 according to the invention for analyzing a sample P.

[0067] Furthermore, a furnace 2 is shown schematically in Fig. 2. A more detailed representation of furnace 2 is shown in Fig. 2.

[0068] The analyzer 1 preferably includes the oven 2. However, the oven 2 represents an aspect that can be implemented independently of the analyzer 1.

[0069] The furnace 2 is specifically designed for the oxidation and / or combustion of sample P. The oxidation or combustion preferably produces an analyte or a combustion product of sample P, which is then analyzed or analyzable using the analyzer 1.

[0070] In particular, the analyzer 1 is designed for combustion analysis of sample P and / or for determining the quantity and / or concentration of certain chemical elements, especially carbon, hydrogen, nitrogen and / or sulfur, in sample P. In other words, the analyzer 1 is preferably designed for elemental analysis.

[0071] Sample P is preferably an organic sample, but can also be an inorganic sample.

[0072] The analyzer 1 preferably has an analysis channel 3 for analyzing the sample P or an analyte of the sample P.

[0073] Preferably, the sample P or the analyte or the combustion products generated therefrom is passed through the analysis channel 3 by means of a carrier gas, for example helium or argon, and detected in the analysis channel 3 by means of a detector, in particular to determine the concentration of certain chemical elements.

[0074] The following use of the term "combustion products" refers in particular to a gas stream formed from combustion products and a carrier gas.

[0075] The furnace 2 has a combustion tube 4, which is arranged in particular inside the furnace 2 or in an interior or combustion chamber of the furnace 2.

[0076] The combustion tube 4 is preferably made of a heat-resistant material, in particular glass.

[0077] The combustion tube 4 is preferably at least substantially hollow-cylindrical. Preferably, the combustion tube 4 is straight and / or free of curvature.

[0078] Preferably, the combustion tube 4 is vertically oriented. In particular, the combustion tube 4 has an inlet opening 19 at an upper combustion tube end 4A and an outlet opening 5 at a lower combustion tube end 4B. The combustion tube 4 preferably extends straight or without curvature between the inlet or upper combustion tube end 4A and the outlet or lower combustion tube end 4B.

[0079] Position designations such as "top", "bottom", "horizontal", "vertical" and the like refer in particular to the position shown in Fig. 2 in which the furnace 2 is operated.

[0080] The combustion tube 4 can preferably be removed from the furnace 2 and / or inserted into the furnace 2 by a linear movement.

[0081] The combustion tube 4 is preferably designed to accommodate a crucible 6 for the sample P.

[0082] Preferably, the furnace 2 includes the crucible 6 for the sample P. In particular, during operation of the furnace 2, the sample P is arranged in the crucible 6 and the crucible 6 is arranged or held in the combustion tube 4.

[0083] The crucible 6 preferably has at least the essential form of a hollow cylinder closed at one end. The crucible 6 preferably consists of a porous, gas-permeable and / or sintered material.

[0084] In the combustion tube 4, the sample P is preferably oxidized or burned, in particular wherein the sample P is arranged in the crucible 6.

[0085] The furnace 2 has a guide tube 7. The guide tube 7 surrounds the combustion tube 4 coaxially.

[0086] An annular gap, forming a guide channel 8 for the combustion products, is located between the guide tube 7 and the combustion tube 4. The combustion products are guided through the guide channel 8 after exiting the combustion tube 4 and away from the combustion tube outlet. The guide channel 8 extends the flow path during the transport of the combustion products for sample analysis. As shown in Fig. 4, the combustion products are guided in the guide channel 8 along an outer surface 9 of the combustion tube 4 and an inner surface 10 of the guide tube 7.

[0087] As can also be seen from Fig. 2, the guide tube 7 extends over a large part of the length of the combustion tube 4, preferably over more than 80% of the length, and more preferably over more than 90% of the length.

[0088] The transport or flow path of the combustion products from the outlet opening 5 of the combustion tube 4 via the guide channel 8 is explained below with reference to Fig. 3.

[0089] The combustion products pass through the outlet opening 5 at the lower, or free, end of the combustion tube 4. This is schematically illustrated by an axially downward directed outlet direction A in Fig. 3. After exiting the outlet opening 5, the combustion products enter the guide channel 8 and are transported upwards and laterally towards the combustion tube 4 in a guide direction F that is opposite to the outlet direction A. In other words, the combustion products are transported back towards the combustion tube 4, or upwards, in the guide channel 8 in the opposite direction.

[0090] At the same time, the guide tube 7 preferably extends beyond the outlet opening of the combustion tube 4 in the exit direction A, thus having a greater length than the combustion tube 4 and is led downwards beyond the combustion tube 4.

[0091] In particular, it is provided that the guide tube 7 is designed to be closed at a guide tube end 11 arranged adjacent to the outlet opening 5 of the combustion tube 4.

[0092] The guide tube 7 can be single-walled and / or made in one piece.

[0093] In particular, the guide tube 7 cannot be opened non-destructively at the guide tube end 11 and is therefore permanently closed. However, it is also possible for the guide tube end 11 to be reversibly closed, in particular by means of a releasable locking element. This allows access to the guide tube end 11 from the inside, for example for cleaning purposes. A receiving chamber 12 can be formed between the outlet opening 5 of the burner tube 4 or the lower edge of the burner tube 4 and the closed guide tube end 11, which is bounded downwards by an end wall 13 of the guide tube 7.

[0094] Preferably, the bottom wall 13 has a shape that is curved towards the combustion tube 4, preferably radially symmetrical. In other words, the guide tube end 11 can be convex on the inside or in the direction of the combustion tube 4.

[0095] The volume of the receiving chamber 12 is determined by the axial position of the combustion tube 4 relative to the guide tube 7.

[0096] The combustion products exit the outlet opening 5 in the direction A and strike the curved bottom wall 13 of the guide tube 7 at the guide tube end 11. The combustion products are deflected radially outwards at the bottom wall 13 towards the guide tube 7 and flow upwards along the inside of the guide tube 7 in the opposite direction, F, to the guide channel 8. The combustion products enter the guide channel 8 and are transported away via the guide channel 8.

[0097] As can be seen from Fig. 3, the guide tube 7 has a holder 14 on its inside for the burner tube 4. In particular, when inserted into the guide tube 7, the burner tube 4 rests on the holder 14, especially with its outer edge at the lower burner tube end 4B. The holder 14 is preferably formed by several projections and / or retaining pins spaced apart from one another in the circumferential direction of the guide tube 7.

[0098] The clear cross-section of the outlet opening 5 corresponds to the clear cross-section of the combustion tube 4. No internal components or components reducing the clear cross-section are provided in the area of ​​the outlet opening 5.

[0099] The width S of the annular gap formed between the guide tube 7 and the burner tube 4 can correspond to between 2 and 20%, preferably between 5% and 15%, in particular approximately 10%, of the inner diameter of the burner tube 4.

[0100] The annular gap can have a width S in the range of 0.5 to 5 mm, preferably 1 to 3 mm. In particular, the combustion tube 4 extends in a direction opposite to the exit direction A of the combustion products, i.e., especially upwards, beyond the guide tube 7, as can be seen from the enlarged view in Fig. 5.

[0101] Not shown in Fig. 5 is that the guide tube 7 may have an outlet opening for combustion products. The outlet opening may, in particular, be formed radially in a wall of the guide tube 7. In particular, the outlet opening may be located adjacent to the end 17 of the guide tube.

[0102] Combustion products can also exit axially from the guide tube 7 via the upper end of the guide tube 17. The combustion products can be discharged via the retaining element 21. The retaining element 21 could have a through-opening for this purpose.

[0103] In particular, an outlet opening can be arranged above the crucible 6 and / or a crucible holder relative to the burner tube 4.

[0104] The guide tube 7 can be configured with an outlet opening for connection to the analysis channel 3. The combustion gases do not necessarily have to be transferred directly into the analysis channel 3; they can also first be introduced into a ballast volume and from there transported via the aliquot into the analysis channel 3.

[0105] It is not shown that in the area of ​​an outlet opening of the guide tube 7 at least one cooling geometry, in particular cooling fins, and / or a cooling device for cooling the guide tube 7, in particular by flushing with a cooling fluid, may be provided.

[0106] Furthermore, a surface texture can be provided on the inside of the guide tube 7 and / or the outside of the combustion tube 4 to advantageously influence the flow of the combustion products in the guide channel 8, in particular to further extend the flow path. For example, the surface texture can be formed by a depression and / or, in particular, a spirally extending groove in the surface. To prevent unwanted escape of the combustion products from the guide tube 7, the guide tube 7 can be sealed against the environment in the area of ​​an outlet opening and / or a pipe opening at the upper end 17 of the guide tube.

[0107] For this purpose, at least one sealing element 18, preferably an O-ring, is provided. The sealing element 18 seals the guide tube 7 circumferentially.

[0108] The combustion tube 4 is sealed against the environment, particularly in the area of ​​an inlet opening 19 and / or opposite the outlet opening 5 and / or at the upper end of the guide tube 17 of the guide tube 7.

[0109] For this purpose, at least one further sealing element 20, preferably an O-ring, is provided. The further sealing element 20 seals the combustion tube 4 circumferentially. The further sealing element 20 is preferably arranged and / or designed to be radially offset inwards relative to the sealing element 18.

[0110] The furnace 2 has a retaining component 21 with a retaining geometry for holding or fastening the guide tube 7 and / or the combustion tube 4 to the furnace 2 via the upper tube ends 17, 4A. In addition, the guide tube 7 and the combustion tube 4 are fixed and / or aligned radially to each other by means of the retaining component 21 and the sealing elements 18, 20.

[0111] In particular, the retaining component 21 rests against the upper guide tube end 17 of the guide tube 7, possibly also via a further sealing element, in order to close off the guide channel 8 at the top.

[0112] In particular, the retaining component 21 has a shoulder 22 with a radial boundary surface 23 and an axial boundary surface 24. Below the shoulder 22, the retaining component 21 has a sealing recess 27 in which the sealing element 18 is received. The guide tube 7 is clamped against the retaining component 21 via the sealing element 18 and held in a fixed position on the furnace.

[0113] Furthermore, the retaining element 21 has a sealing recess 28 on its upper side for the additional sealing element 20. For simplified furnace handling, the combustion tube 4 can be inserted or slid axially from above into the guide tube 7. In this process, the combustion tube 4 is guided and / or held between a further axial limiting surface 25 of the retaining component 21.

[0114] The retaining component 21 ensures precise radial positioning and support of the guide tube 7 and the burner tube 4 relative to each other.

[0115] In particular, the retaining component 21 can have a central through-opening 26 (Fig. 7) through which the burner tube 4 can be inserted into the guide tube 7 with minimal play. The through-opening 26 is limited in the radial direction by the further radial retaining surface 25 of the retaining component 21.

[0116] The furnace 2 can have a feed lance 29 that can be inserted into the combustion tube 4 from above. The feed lance 29 is shown in particular in Fig. 2.

[0117] The feed lance 29 is preferably designed for feeding or introducing the sample P into the combustion tube 4 or the crucible 6. Furthermore, the feed lance 29 is preferably designed for feeding or introducing oxygen into the combustion tube 4. The oxygen serves in particular for the oxidation or combustion of the sample P in the furnace 2 or the combustion tube 4.

[0118] The feed lance 29 preferably has or consists of an at least substantially hollow cylindrical section 30 and a stop 31 arranged particularly at the end of the hollow cylindrical section 30.

[0119] The stop 31 preferably projects radially and / or outwards from the hollow cylindrical section 30.

[0120] In the operating position, the feed lance 29 preferably extends into the crucible 6 to a defined penetration depth. This is shown in particular in Fig. 2.

[0121] The outer diameter of the feed lance 29 is preferably approximately the same size as, or slightly smaller than, the inner diameter of the crucible 6, in particular such that the feed lance 29 can be inserted into the crucible 6 and, in the operating position or when inserted into the crucible 6, rests against the crucible 6 – in particular sealingly. Preferably, the feed lance 29 rests fluid-tight against the crucible 6 in the operating position, in particular so that no fluid or gas can pass between the feed lance 29 and the crucible 6.

[0122] The feed lance 29 can only extend into the crucible 6 to a defined length and still has some play, so that the two components are not sealed against each other.

[0123] The feed lance 29 is preferably made of glass and / or metal.

[0124] The burner tube 4, the crucible 6 and / or the feed lance 29 are preferably arranged coaxially.

[0125] The feed lance 29 can be inserted into the combustion tube 4 from above, in particular via the inlet opening 19 of the combustion tube 4.

[0126] In the operating state or in the installed state, the feed lance 29, in particular with the stop 31, rests on the top of the burner tube 4 or its inlet opening 19.

[0127] The retaining component 21 is preferably arranged on or supported by a support bracket 32. The support bracket 32 ​​is preferably sheet-metal and / or has a U-shaped cross-section, at least in sections.

[0128] Furthermore, the oven 2 preferably has an oven body 33 with an upper oven plate 34 and a lower oven plate 35, see Fig. 6. The oven structure is supported on the upper oven plate 34.

[0129] Preferably, the guide channel 7 with both guide tube ends 11, 17 protrudes from the furnace body 33 or extends beyond the furnace plates 34, 35.

[0130] The retaining component 21 is preferably screwed to the support bracket 32 ​​from above.

[0131] Furthermore, a lock 36 is provided for passing the sample P. The lock 36 is connected to the holding component 21, in particular via an intermediate piece 37. The intermediate piece 37 can be connected to the holding component 21 from above, in particular by screws.

[0132] Preferably, the intermediate piece 37 has a sealing element 38 for sealing against the lock 36. The intermediate piece 37 is preferably ring-shaped.

[0133] As can be seen from Fig. 5, the lock 36 preferably has a lock chamber 39 and a sample holder 40 arranged in the lock chamber 39 for receiving the sample P. The sample holder 40 is preferably displaceable within the lock chamber 39.

[0134] The lock 36 or the lock chamber 39 is preferably fluidically connected or connectable to the burner tube 4.

[0135] The sample holder 40 preferably has a receiving chamber 41 for the sample P. The receiving chamber 41 is preferably designed as an opening in the sample holder 40 and / or preferably extends vertically. Preferably, the receiving chamber 41 completely penetrates the sample holder 40.

[0136] In a first position, the sample receptacle 40 is preferably accessible from outside the lock 36, in particular so that the sample P can be introduced into the sample receptacle 40 or the receiving chamber 41.

[0137] In a second position, shown in Fig. 5, the sample holder 40, in particular the receiving chamber 41, is preferably fluidically connected to the combustion tube 4.

[0138] The sample holder 40 is preferably movable from the first position to the second position and / or vice versa, in particular by a straight-line movement.

[0139] The lock 36 preferably has a closing plate 42 by which the lock chamber 39 is at least partially closed or covered. The closing plate 42 is preferably arranged on a top side and / or on the side of the lock chamber 39 facing away from the burner tube 4. The closing plate 42 preferably has an opening 43 through which the sample P can be inserted into the sample holder 40 or the sample chamber. In particular, the opening 43 is aligned with the sample chamber 41 in the first position of the sample holder 40.

[0140] In the second position of the sample holder 40, the receiving chamber 41 is preferably fluidically connected to the combustion tube 4, in particular arranged in alignment with the combustion tube 4.

[0141] Preferably, the furnace 2 has a displacement device 44 for moving or shifting the sample holder 40 between the first and second positions. The displacement device 44 can be moved manually or automatically, in particular pneumatically, by motor, hydraulically, or magnetically.

[0142] The lock 36 preferably has a closing device 45 for closing the lock chamber 39. In particular, the opening 43 in the closing plate 42 can be closed or covered by means of the closing device 45.

[0143] The lock 36 or lock chamber 39 is preferably sealed or sealable to the outside by means of a seal. It is preferred that the seal is designed as an O-ring and / or surrounds the opening 43. Preferably, the seal is held or arranged in the closure plate 42.

[0144] The locking device 45 preferably comprises a plunger 46 and a traversing device 47 for traversing the plunger 46. The plunger 46 is preferably arranged coaxially with the opening 43 and / or the seal and / or is movable.

[0145] In particular, the plunger 46 is movable towards the opening 43 to close and / or seal the lock chamber 39, especially so that the plunger 46 rests against and / or presses against the seal, so that the lock chamber 39 is sealed to the outside or no gas can enter the lock chamber 39 through the opening 43 when the plunger 46 is in sealing contact with the seal. To introduce the sample P into the furnace 2, the sample holder 40 is preferably positioned in the first position and the sample is inserted into the sample holder 40 or arranged in the receiving space 41.

[0146] Subsequently, the sample holder 40 is moved into the second position, which is shown in particular in Fig. 5, in particular by means of the displacement device 44.

[0147] Preferably, the sample P falls into the combustion tube 4 or into the crucible 6 arranged in the combustion tube 4 when the sample holder 40 is in the second position or the receiving chamber 41 is located above the combustion tube 4.

[0148] After or during the movement of the sample holder 40 into the second position, the plunger 46 is preferably moved against the opening 43 and / or seal, in particular by means of the traversing device 45, so that the lock chamber 39 is sealed.

[0149] Afterwards, a desired atmosphere can be set in the furnace 2, the combustion tube 4 and / or the lock chamber 39, for example by supplying gas, especially oxygen, and / or by setting a desired pressure and / or a specific desired temperature.

[0150] If necessary, the sample holder 40 can be moved out of the second position before or during the establishment of the desired atmosphere in order to release the burner tube 4 and / or to enable and / or facilitate the supply of gas to the burner tube 4. However, this is not mandatory.

[0151] The sluice gate 36 allows for easy and safe handling.

[0152] The general structure of furnace 2 can be seen from the exploded view shown in Fig. 6.

[0153] The guide tube 7 can be inserted axially into a particularly complementary opening in the furnace body 33 of the furnace 2. The upper furnace plate 34 and the lower furnace plate 35 can be attached to the upper side of the furnace body 33.

[0154] The support bracket 32 ​​is preferably connected to the top of the furnace body 33 or to the upper furnace plate 34 by its downward-pointing legs, for example by screws. The retaining component 21 and / or the lock 36 are preferably arranged or supported on a web connecting the legs of the support bracket 32, preferably by screws.

[0155] Preferably, the retaining component 21 and the lock 36 are detachable from the support bracket 32. This allows the combustion tube 4 to be accessed axially from the furnace body 33 or the guide tube 7. In other words, the combustion tube 4 and / or the feed lance 29 are freely accessible from above. This simplifies the maintenance and loading of the furnace 2 according to the invention.

[0156] In particular, the support bracket 32 ​​has an access opening 48 on its upper side (Fig. 6). The feed lance 29 and, preferably, the burner tube 4 are accessible from above and / or can be removed axially from above via the access opening 48.

[0157] The exploded view shown in Fig. 7 illustrates the connection of the retaining component 21 with the lock 36.

[0158] The retaining component 21 is preferably connected to the support bracket 32 ​​via fastening means 49, such as screws.

[0159] The retaining component 21 is preferably connected to the lock 36, in particular via further fastening means 50.

[0160] Specifically, lock 36 can have a lock body 51. The lock chamber 39 can be at least partially formed in the lock body 51.

[0161] The additional fastening elements 50 pass through the lock body 51 and into the retaining component 21.

[0162] The additional fastening elements 50 enter the lock body 51 essentially entirely from the top. For this purpose, corresponding shallow recesses are provided in the lock body 51 for the additional fastening elements 50.

[0163] The lock body 51 is screwed to the retaining component 21. In the illustrated and preferred embodiment, the lock body 51 is preferably connected to the retaining component 21 via the intermediate piece 37. In particular, the further fastening means 50 first penetrate the intermediate piece 37 and finally the retaining component 21.

[0164] Preferably, the fastening means 49 engage with their fastening heads on the underside and / or in a form-fitting manner in the intermediate piece 37, in particular so that the intermediate piece 37 rests on the upper side at least substantially precisely and / or directly and / or without gaps on the holding component 21. This is shown in Fig. 5. This design makes it possible, in particular, for the lock 36 or the lock body 51 to be removable from the holding component 21 by releasing the further fastening means 50, in particular whereby the holding component 21 continues to be held or fixed by the fastening means 49. The feed lance 29 and the burner tube 4 are then accessible via the fixed holding component 21 or the through-opening 26 and, in particular, can be removed axially.

[0165] Reference symbol list:

[0166] 1 analyzer 29 feed lance

[0167] 2 Oven 30 Section

[0168] 3 Analysis channel 31 Stop

[0169] 4 Burn tube 35 32 Support bracket

[0170] 4A Burn tube end 33 Furnace body

[0171] 4B Burn tube end 34 Oven tray

[0172] 5 Outlet opening 35 Oven tray

[0173] 6 crucibles 36 lock

[0174] 7 Guide tube 40 37 Intermediate piece

[0175] 8 Guide channel 38 Sealing element

[0176] 9 Exterior area 39 Lock chamber

[0177] 10 Inner surface area 40 Sample intake

[0178] 11 Guide tube end 41 Receiving chamber

[0179] 12 Recording chamber 45 42 Closure plate

[0180] 13 Floor wall 43 Opening

[0181] 14 Bracket 44 Sliding device

[0182] 15 Bracket 45 Locking device

[0183] 17 Guide tube end 46 Punch

[0184] 18 Sealing element 50 47 Traction device

[0185] 19 Entrance opening 48 Access opening

[0186] 20 Sealing element 49 Fasteners

[0187] 21 Mounting component 50 Fasteners

[0188] 22 Shoulder 51 Lock body

[0189] 23 Holding surface 55

[0190] 24 Stop surface A Exit direction

[0191] 25 Holding surface F Guide direction

[0192] 26 Passage opening P Sample

[0193] 27 Sealing recess S width

[0194] 28 Sealing recess

Claims

Patent claims:

1. Oven (2) for an analytical instrument (1) for analyzing a sample, comprising a combustion tube (4), wherein the sample can be introduced into the combustion tube (4), preferably by means of a crucible (6), and can be combusted at least partially in the combustion tube (4), preferably with the addition of an oxidizing agent, characterized in that a guide tube (7) is provided that surrounds the combustion tube (4) at least section by section, wherein a guide channel (8) for combustion products released in the combustion tube (4) is formed between the guide tube (7) and the combustion tube (4).

2. Furnace (2) according to claim 1, characterized in that the combustion tube (4) has an outlet opening (5) for the combustion products, wherein the combustion products in the combustion tube (4) are transportable in an outlet direction (A), preferably downwards, to the outlet opening (5) and after exiting the outlet opening (5) enter the guide channel (8) and are transportable in a guide direction (F) preferably opposite to the outlet direction (A), further preferably upwards.

3. Oven (2) according to claim 1 or 2, characterized in that the combustion products are guided in the guide channel (8) along a tube wall (9) of the combustion tube (4) and / or along a tube wall (10) of the guide tube (7) and / or that the clear cross-sectional area of ​​the combustion tube (4) at the outlet opening (5) corresponds to the clear cross-sectional area of ​​the combustion tube (4) above the outlet opening and / or that the combustion tube (4) is free of internal components in the area of ​​the outlet opening (5).

4. Oven (2) according to one of the preceding claims, characterized in that the guide tube (7) is formed in a closed manner at a guide tube end (11) adjacent to an outlet opening (5) of the combustion tube (4), preferably lower.

5. Oven (2) according to one of the preceding claims, characterized in that a receiving chamber (12) for a functional material is provided in the outlet direction (A) of the combustion products are provided and / or formed downstream of the outlet opening (5) of the combustion tube (4), in particular formed between an end wall of the guide tube (7) and the adjacent end of the combustion tube, in particular wherein a reaction reactant for the reaction with corrosive, in particular acidic, components of the combustion products, for example steel wool, and / or a catalyst material and / or a filter material is provided in the receiving chamber (12).

6. Oven (2) according to one of the preceding claims, characterized in that the guide tube (7) has an inwardly curved, preferably radially symmetrical, shape at a guide tube end (11) and adjacent to an outlet opening (5) of the combustion tube (4) and / or that the guide tube (7) is made of glass, in particular quartz glass, or metal and / or that the guide tube (7) and the combustion tube (4) are made of the same material.

7. Oven according to one of the preceding claims, characterized in that the guide tube (7) extends over a large part of the length of the combustion tube (4), preferably over more than 80% of the length, more preferably over more than 90% of the length, and / or that the combustion tube (4) extends beyond the guide tube (7) in a direction opposite to the exit direction (A) of the combustion products, preferably upwards, and / or that the guide tube (7) extends, preferably downwards, beyond the outlet opening (5) of the combustion tube (4) in the exit direction (A).

8. Oven (2) according to one of the preceding claims, characterized in that a guide tube end (17) of the guide tube (7) opposite an outlet opening (5) of the combustion tube (4), preferably upper, is held on a retaining component (21) of the oven (2) and is, preferably, sealed and / or fixed against the environment, in particular by means of at least one sealing element (18, 20).

9. Oven (2) according to one of the preceding claims, characterized in that the guide tube (7) has an outlet opening for the combustion products, wherein, preferably, the outlet opening of the guide tube (7) is provided adjacent to one of the guide tube ends (11) opposite the outlet opening (5) of the combustion tube (4), preferably in the region of an upper guide tube end (17), and / or above a crucible (6) inserted into the burner tube (4) and / or above a crucible holder in the burner tube (4).

10. Oven (2) according to claim 9, characterized in that the guide tube (7) is designed in the area of ​​the outlet opening for connection to an analysis channel (3) of an analysis device or for connection to a ballast volume and / or that the guide tube (7) is sealed against the environment in the area of ​​the outlet opening and / or in the area of ​​a pipe opening of one of the guide tube ends (17) opposite the outlet opening (5) of the combustion tube (4), in particular the upper one, in particular by means of at least one sealing element (18, 20), and / or that a cooling geometry, in particular cooling fins, and / or a cooling device for cooling the guide tube (7), in particular by flushing with a cooling fluid, is provided in the area of ​​the outlet opening of the guide tube (7).

11. Oven (2) according to one of the preceding claims, characterized in that, to support the gas exit from the guide tube (7) via the outlet opening and / or to extend the flow path in the guide channel (7) in the area of ​​the guide channel (8), a surface structuring of at least one tube wall of the guide tube (7) and / or the combustion tube (4), in particular a recess, in particular a groove, and / or a projection, is provided and / or that at least one flow element, in particular a spiral ring element, is inserted and / or arranged in the guide channel (8).

12. Oven (2) according to one of the preceding claims, characterized in that the combustion tube (4) and / or an element engaging in the combustion tube (4), such as a feed lance (29), can be inserted into the guide tube (7) via a guide tube end (17) opposite the outlet opening (5) of the combustion tube (4), in particular an upper one.

13. Oven (2) according to one of the preceding claims, characterized in that the guide tube (7) has at least one inwardly projecting support (14) for the combustion tube (4), wherein, preferably, the combustion tube (4) rests on the support (14) in the state inserted into the guide tube (7).

14. Analytical apparatus (1) for analyzing a sample (P) with an oven (2) according to one of the preceding claims.

15. Method for providing combustion products of a sample (P) by combustion of the sample (P) in a combustion tube (4) of a furnace (2), preferably a furnace (2) according to any one of the preceding claims 1 to 13, for subsequent analysis of the combustion products in an analyzer (1), wherein the sample (P) is introduced into the combustion tube (4), preferably by means of a crucible (6), wherein the sample (P) is at least partially combusted in the combustion tube (4), preferably with the addition of an oxidizing agent, and wherein combustion products of the sample (P) released in the combustion tube (4) are transported, preferably by means of a carrier gas, in an outlet direction (A), preferably downwards, to an outlet opening (5) of the combustion tube (4), characterized in that the combustion products, after passing the outlet opening (5), in particular at an outer edge of the combustion tube (4), are deflected and guided in a direction (F) opposite to the outlet direction (A).preferably forwarded upwards.

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