DE2923596A1 - Hydrocarbon cracking or reforming furnace - with internally subdivided ceramic tubes for gas mixt. - Google Patents

Abstract

Thermal conversion furnace for gas mixts., specially for cracking and reforming of hydrocarbons, includes at least one straight tube, made of ceramics, in which the gas mixt. is passed through the furnace space, heated by burners. The inside of each tube is subdivided by radial, parallel or concentric ribs into a great number of separate flow chambers, with walls which are coated by a catalyst if the process requires it. The tube or tubes are anchored in the furnace hearth and are free to slide in its ceiling. A helical arrangement of the chambers improves the heat exchange conditions by added turbulence. This eliminates the operational difficulties with metal tubes. The reactions can now be carried out at a higher temp. level and with a higher efficiency.

Description

Description

The invention relates to a process furnace for thermal conversion of gas mixtures, especially hydrocarbons, in which the for the expiry of the Conversion or

Refining process required heat inside the furnace by a Flue gases generated by the burner system are transferred to the gas mixture passed through the furnace will.

In known process ovens that are used for reforming or cracking gas mixtures are used, so-called SrozeR pipes are used to pass the gas mixture through the firebox of the stove. The process pipes are made of metal, so that the application limits of the pipes depending on the pressure / temperature ratio at approx. 115000 permissible pipe wall temperature liegel. At this limited temperature level, certain cracking processes can only can be carried out economically to a limited extent, and the metallic ones are subject to it Pipes of a carburization and scaling, which the economy of a furnace and especially the life cycle of the process pipes.

Fastening is also problematic according to the prior art the metal pipes in the furnace combustion chamber due to the high thermal expansion of the metals. The pipes must be made with technically complex solutions taking into account the large Thermal expansion can be suspended or supported.

Another disadvantage of the prior art is that the process tubes arranged in the furnace at certain distances from one another and towards the burner flame must be, in particular for reasons of economic heat transfer and to prevent local overheating.

This means that for comparatively small product cross-sections, a very large combustion chamber required, which not only contributes significantly to the fact that the furnace takes up a large area, but in particular also its production costs elevated.

In so-called reforming lt processes, according to the status of the Technology used catalysts in the form of lPüllkkörper with ceramic carrier bodies built up and placed in the process or reaction tubes in an ordered or disordered manner are. The pipes fitted with catalysts in reforming furnaces are due to the use of fillings on the one hand susceptible to failure (breaking, sooting, caking) and on the other hand in the case of catalytic converter supports that have been introduced in a disorderly manner, flow can only be passed from top to bottom. Therefore it can only be flown through from top to bottom because the packing is more economical Durchströmunm moved from bottom to top and thus damaged. When Damage (breaking, sooting, caking, etc.) of the packing must therefore Prior art oven can be run at reduced power, and it In extreme balls, the entire furnace and thus the entire gas refining system must taken out of service.

It is based on the aforementioned state of the art and is avoided the aforementioned disadvantages The object of the invention to provide a process furnace for a thermal To create product gas to be converted, i.e. to be split or reformed, which operated more economically with a simple structure than according to the state of the art can be.

The object on which the invention is based is achieved in that ' at least one made of ceramic for passing the gas mixture through the process furnace Existing straight pipe with an inner grid wall symmetrical to the pipe axis is provided, which axially penetrates the pipe and together with the pipe inner wall äe is coated with or without a catalyst after the conversion process.

By using suitable ceramic materials for the Process pipes of a process furnace in which the reactions can take place1 certain Processes such as cracking or reforming processes at a higher temperature level and thus run more economically. In contrast to metallic pipes according to the state of the art, the ceramic tube built according to the invention is very temperature-resistant. Operating temperatures in process ovens up to 1aD0 ° C 0 are without damage to the system possible, i.e. without disadvantageous aging of the pipes, loosening, etc .. Due to the higher temperature levels (compared to the prior art) In certain cases, the use of catalysts can be dispensed with with certain transformation processes in the lower, temperature range according to the state are an indispensable requirement of technology. The ceramic tube has little thermal expansion during operation, which causes the problem of thermal expansion even with long pipes plays a subordinate role and a pipe fastening at comparatively The lattice-like internal structure of the pipe is possible with a simple construction effort makes a decisive contribution to the fact that the comparatively fragile ceramic tube has sufficient strength in every practical operating situation.

Catalyst envelopes or bulk catalysts according to the prior art Technology are no longer used in the invention, so that the pipe in operation can be flown through regardless of direction. The inner grid-like wall structure a tube also creates inner chambers or through-flow sections, which at In the event of a pipe burst, only allow part of the product gas to escape. Gas losses are thereby minimized, especially in the case of poisonous or otherwise dangerous Product gases is a particular advantage of the invention.

The one with an integral inner symmetrical grid structure Tube with or without a catalyst creates internal heat conduction webs when the system is in operation and consequently a large thermal active area, which is economical in operation of a furnace. The pipes can be comparatively close to each other and be arranged at a distance from the burner flame, without local overheating points in the Operation due to pipe material and structure.

This enables a particularly compact furnace with high economic efficiency being constructed.

An advantageous development of the invention provides that through the grid wall in the pipe interior are formed in chambers of approximately the same size.

In particular, it can be provided that the grid is like a spoke over is designed to be evenly distributed around the circumference of the pipe.

In an advantageous embodiment of the invention, the grid has at least one inner ring concentric to the pipe jacket.

Alternatively, however, the grid can also be constructed in the manner of a cross be.

A particularly high level of turbulence in a gas mixture flowing through it for the purpose of optimal heat absorption through the pipe for a thermal conversion of the Medium is achieved when the tube is designed with a grid wall that the inside of the pipe penetrates helically in the bxial direction.

An advantageous embodiment of a process furnace provides that the pipe arranged vertically in the furnace is supported at the bottom outside of the furnace and is slidably guided at the top of the furnace ceiling. This is the static load on the pipe is minimal, and it can use simple fasteners Find use.

A particularly economical and compact freezing furnace characterizes in that at least one made of sintered, in particular ceramic material existing block with a large number of closely spaced pairs of passageways is provided, with gas mixture and flue gas through each channel pair for the purpose of Vlärmetausch conducted in the company and the passage channels for the gas mixture each are coated with or without a catalyst after the conversion process. According to this embodiment are therefore not process tubes, but one or more so-called process blocks Used in a F + oprocess furnace that meet the V! ärmetauscherfuriition. The block advantageously has a cross grating, in which with regard to the grating width alternating, different sized grid spacing is provided. It will be on In this way, closely adjacent through-channel rows created, and it flows in the through-ducts with a larger cut-out during operation the (heat-emitting) Flue gas, while through the flow channels with smaller waste the (heat-absorbing) He 'odukt gas is passed in countercurrent or cocurrent. The through channels for the product gas to be converted are coated with a catalyst if the thermal process catalysts required.

A particularly advantageous development of the invention is then given when several identically formed blocks are aligned with respect to the through channels and these are arranged connecting one another and / or placed close to one another are, the furnace chamber of a process furnace completely filled or by the Blocks the furnace space is formed.

This block arrangement in a process furnace enables optimal he The furnace geometry is an extremely compact furnace unit with considerable simplification and cheaper of a furnace compared to the prior art, in which not only the thermal and especially the static components are extremely advantageous in terms of construction is resolved.

Furthermore, it can be provided that adjacent associated blocks are arranged fixed with respect to their passage channels. Bixierungshilfe can Shoulders, grooves or the like be. The fixation of neighboring Associated blocks can also be created using inclined surfaces in the case of blocks with a roof-like structure take place.

The blocks are advantageously by means of ceramic glue or ceramic masses connected, as well as the process tubes of a tubular (process) furnace can be connected by means of such ceramic means. This makes it possible Blocks or tubes of ceramic materials safely in relatively small units and use it for a furnace that requires larger units.

The invention is explained below using exemplary embodiments Referring to the drawing explained in more detail; It shows: Fig. 1 a cross section of a tube according to the invention, wherein an integrated spoke mesh is provided Fig. 2 shows another tube in cross section with a cross-like grid structure, Fig. 3 shows a pipe cross-section similar to FIGS. 1 and 2 with inner radial struts and a concentric inner ring as a grid, FIG. 4 is a schematic longitudinal view of a pipe section constructed according to the invention with an integrated catalyst, FIG. 5 shows a cross section of the pipe according to FIG. 4, FIG. 6 shows a pipe cross section similar to FIG with an integrated catalytic converter, FIG. 7 is a schematic vertical view of an arrangement of tubes according to FIGS. 1-6 in a process furnace, the tubes being serpentine are connected to one another, FIG. 8 shows a cross section through the process furnace according to FIG 7, 9 show a further embodiment of an arrangement of tubes in one Process furnace similar to FIG. 7, with all tubes connected in parallel and have separate feed and discharge lines, FIG. 10 shows a cross section by a freezing furnace according to FIG. 9, FIG. 11 another embodiment of one according to the invention built-up building element in the form of a block with closely adjacent ducts, which fulfills the heat exchanger function during operation, Fig. 12 is a cross section through the block according to FIG. 11 with an integrated catalyst, FIG. 13 a schematic Vertical view of an arrangement of blocks according to FIGS. 11 and 12 in a process furnace, 14 is a schematic vertical view of two adjacent blocks with one inclined roof-like 'ixierungshilfe, and Fig. 15 is a vertical view similar 14 with step-like fixation.

According to the drawing, pipes with integrated cross-sectional shapes are made according to 1 to 6 in process furnaces according to FIGS. 7-10 for the purpose of thermal conversion used by product gases. The product gas flows through it vertically in the combustion chamber a process furnace arranged tube, the temperatures up to at least 1400 ° C each after process and ceramic material is exposed.

Due to the supply of heat, the product gas is refined, i.e.

cracked or reformed.

The arranged in a process furnace 1 tube 2 consists of ceramic and runs in a straight line through the interior of a furnace. The tube has an integrated inner ceramic grid wall 6, which is axially symmetrical to the pipe axis is and penetrates the tube over the entire length and thereby creates chambers 8. The product or cracked gas to be converted flows through all of the chambers during operation 8 of a tube which can have lattice configurations as shown in FIGS. 1-3 is shown. In particular, a spoke lattice according to FIG. 1, a cross lattice according to FIG. 2 or a radial grille with a concentric inner ring according to FIG. 3 is provided be.

Due to the lattice design, in the case of a single tube 2 of a process furnace 1 increased security against pipe bursts while minimizing pool losses through Chamber training, also increased strength due to the inner stiffening ribs of the Rohrs and especially an optimal heat transfer to the product gas by A large Tjirkfläche created, and it can, as filler catalysts according to the state the technology is not used, each individual pipe regardless of direction with the same high efficiency without damaging the pipe.

The tube shapes are depending on the application, i.e. depending on the outer Requirements for the can or reformer tubes with regard to free cross-section, Pressure and temperature defined and dimensioned.

4-6 are tube configurations with catalyst coating shown. The catalyst coating on the active surface of the inside of the pipe is through Immersing a tube in a liquid catalyst bath is made. Possibly the outer pipe jacket is covered with a protective layer for the immersion process, which is removed after the immersion process and causes only the inside of the tube with is coated with a catalyst.

Alternatively, for the purpose of applying a catalyst inside the pipe the single tube can be flowed through with liquid catalyst material, so that on this way the catalyst material is fixed to the porous wall of the pipe interior.

As can be seen from Figs. 7 and 8, the reaction part consists of one Cracking furnace from process or cracking tubes 1, the äe after to be cleaved product gas Via fittings 12 lying outside of the combustion chamber 16 one or more times to form one Kind of snake connected through which the cracked gas flows. Because tensile stresses arise If the ceramic tubes are to be kept as small as possible, the tubes are in the furnace floor outside of the furnace 16 by a support 20 statically supported and in the Firebox ceiling fixed laterally in a displaceable guide 22. Through this Fastening arrangement, the thermal stresses during operation on the pipe on the required PEnimum reduced.

Burner 18 according to FIG Fig0 7 may be provided. Other burner arrangements are also conceivable. The smoke outlet can be up or down re the combustion chamber be provided.

The embodiment of a reaction part shown in FIGS. 9 and 10 a reforming furnace with parallel catalyst tubes 1, which in one Beuer space 16 are arranged, is also according to process pressure, reforming gas product and temperature can be designed according to the individual application. the The tubes are supported in the aforementioned manner.

A particularly advantageous embodiment of the invention is shown in Figs. 11-13 are shown.

Instead of the tubes 1, a process furnace 1 according to FIG. 13 now has blocks 4 with passage channels 30 and 32 for a cracked gas and a flue gas. The tight adjacent through channels 30, 32 are by an integrated cross-like Inner lattice in the hollow block according to Fig. 12 created the same as the hollow block exterior In particular, ceramic consists of binter material and therefore the Erozebofen 1 can be operated at a very high operating temperature.

The cross-like structure of the inner wall 5 of the block 4 points with regard to the grid width b has an alternating grid spacing of different sizes al or a2, creating rows of passage channels for a flue gas with a large flow cross-section and rows of through-channels for a product gas with a comparatively small flow cross-section develop. The passage channels 30 with a smaller flow cross-section can be connected to the inner wall with a catalyst similar to the aforementioned embodiments be coated.

In Fig. 13 is a process furnace in a schematic vertical section 1, in which the combustion chamber 16 is completely covered with blocks 4 according to FIGS. 11 and 12 is filled out. The blocks 4 are in an aligned manner with respect to the Through channels layered on top of one another and arranged side by side so that perpendicular running through channels 30 and 32 for the gap gas or

the flue gas are created. The cracked or product gas 28 is by one or more lateral connections 40 to the furnace 16 in a heat exchanger arrangement supplied or discharged, while the burner arrangement 36 according to the described embodiment is attached to the furnace ceiling or floor and the flue gas 34 the blocks 4 flows through from top to bottom or bottom to top and through the lower side Outlet 38 is discharged.

The weight of the blocks is either in the furnace steel structure or supported by supports 42 from the furnace floor.

As shown in FIGS. 14 and 15, fixation aids can be a rule adjacent blocks 4 may be provided in order to provide through channels associated with one another 30 and 32 to align or

to connect the grid wall of neighboring elements with each other, namely by means of ceramic compounds or adhesives, which ensure a high-quality connection between the components due to a sintering or firing process before the actual one Create operation of the process furnace.

It can be seen that the arrangement and size of the individual components as well Direction of flow of product and flue gas according to an individual application can be freely designed.

Illit the help of the aforementioned block construction of a furnace can extremely compact furnace configurations with comparatively high economic efficiency realize.

L e r s e i t e

Claims (11)

Process furnace for the thermal conversion of gas mixtures, in particular Hydrocarbons Patent Claims 1. Process furnace for thermal conversion of Gas mixtures, in particular hydrocarbons, in which the or refining process required noise inside the furnace by a burner system generated flue gases is transferred to the gas mixture passed through the furnace, thereby g e k e n n -z e i c h n e t that for passing the gas mixture through the process furnace (1) with at least one straight tube 2) made of ceramic to the pipe axis symmetrical inner grid wall (6) is provided, which the pipe axially penetrated and together with the inner wall of the pipe, depending on the conversion process or is coated without a catalyst (14). 2. Process furnace according to claim 1, thereby g e k e n n z e i c h -n e t, to date, through the grille wall (6) inside the pipe, roughly pale-sized chambers (8) are formed. 3. RozeSoSen according to claim 1 or 2, characterized in that g e k e n n -z e i c It should be noted that the grid is designed to be evenly distributed over the length of the pipe in a spoke-like manner is (Fig. 1). 4. Process furnace according to one of claims 1 to 3, thereby g e -k e n It is not indicated that the grid is at least one concentric to the pipe jacket Has inner ring (Fig. 3). 5. Process furnace according to one of claims 1 or 2, characterized @ It is evident that the grid is constructed like a cross (FIG. 2). 6. Tube according to one of claims 1 to 5, characterized in that g e k e n n -z e i c h n e t that the lattice wall (6) the pipe interior is helical in the axial direction interspersed. 7. process furnace according to one of the preceding claims, characterized g e it is not indicated that the pipe (2) arranged vertically in the ErozeB oven (1) Supported below outside the combustion chamber (at 20) and above in the combustion chamber ceiling (at 22) of the furnace is slidably guided (Fig. 7-10). 8. Process furnace according to + & nspruch 1, thereby g e k e n n z e i c h -n e t that at least one made of sintered, in particular ceramic material Block (4) with a large number of closely spaced pairs of passage channels (30 resp. 32) is provided, with å each pair of channels gas mixture and Flue gas passed for the purpose of heat exchange during operation and the passage channels (30) for the gas mixture is coated with or without a catalyst (14) depending on the conversion process are (Fig. 11 to 13). 9. Process furnace according to claim 8, characterized in that g e k e n n z e i c h -n e t that several identically formed blocks (4) with respect to the through channels (30, 32) aligned and connecting them to one another and / or close to one another set +) generic term of are arranged, wherein the furnace chamber (16) of a process furnace (1) completely filled or the furnace chamber through the blocks (16) is formed (Fig. 13). 10. Process furnace according to claim 9, characterized in that it is e k e n n z e i c h -n e t that adjacent associated blocks (4) with respect to their through channels (30, 32) are arranged in a fixed manner. 11. I> process furnace according to claim 9 or 10, characterized g e k e n n -z e i c h n e t that the blocks (4) by means of ceramic glue or ceramic masses are connected.