Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
  • F28F21/04—Constructions of heat-exchange apparatus characterised by the selection of particular materials of ceramic; of concrete; of natural stone
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F2225/00—Reinforcing means
  • F28F2225/04—Reinforcing means for conduits
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4935—Heat exchanger or boiler making

Definitions

• the present invention relates to a fiber-reinforced body, a process for its production, and its use as a pipe or tube sheet in a heat exchanger.
• components of ceramic material such as silicon carbide tubes are often used.
• Dense silicon carbide tubes are susceptible to brittle fracture as ceramic materials, in case of mechanical failure, the tubes break catastrophically, that is, there are fragments. The tube loses its integrity.
• a heat exchanger made from such tubes can be destroyed by such a rupture as corrosive acids enter the non-corrosive service compartment of the heat exchanger. In addition, further damage can occur in the cooling system or heating system to which the heat exchanger is connected.
• Object of the present invention is to provide a material that is insensitive to catastrophic brittle fracture.
• the body according to the invention is a body comprising a ceramic material and suitable for use in a heat exchanger and for the passage of fluids.
• the outside of the body is at least partially spanned by at least two fiber bundles in the longitudinal direction and / or circumferential direction and connected to them non-positively.
• the fiber bundles are prestressed. Adjacent portions of the fiber bundles are arranged at a predetermined distance.
• the fiber reinforcement improves the properties of bodies as follows: increase of the bursting pressure, the body becomes less resistant to brittle fracture, steam blows and impermissible exceeding of the operating pressure. Even if fluids are conducted through the fiber-reinforced body during operation and a longitudinal crack occurs as a result of, for example, its age, improper use or overstress, no significant leakage occurs in this body up to a predetermined differential pressure.
• the pushing out or breaking of fragments of the body is intercepted due to the tension with fiber bundles on the body to a certain extent such that a adoptedschiebendes from the original shape of the body or piece by the surrounding fiber bundles under bias in a predetermined shape is held back. The breaking out of pieces from the body and thus the escape of large amounts of fluid are prevented.
• the heat exchanger, in which the body is used can usually continue to operate without interruption until a planned shutdown. Therefore, the body of the present invention, even in a defective state, is dense to a predetermined degree unlike the body without reinforcement.
• the body is a tubular body.
• a tubular body is understood in particular to mean a body which preferably has a circular cross-section and, in order to be suitable for conducting fluids, is open at the ends of its longitudinal extent.
• the tubular body may also have a polygonal, oval or other cross-section.
• the longitudinal extent of the tubular body is greater than its cross-section.
• the tubular body is a tube with a circular cross-section.
• the body is a lid, with a plurality of holes extending in the longitudinal direction of the lid.
• a lid in the sense of underlying invention, a body having a preferably circular cross-section understood that does not have a single cavity, but a plurality of cavities.
• the lid has a multiplicity of holes which extend in the longitudinal direction of the lid and thus represent cavities.
• the lid is considered as a tubular body whose length dimension is traversed not by a single cavity, but by a plurality of cavities, which can open into a single cavity within the longitudinal extent of the lid or continuously along the longitudinal direction of the lid can extend separately.
• the longitudinal extension of the lid is preferably smaller than its cross section.
• the lid has the shape of a round disc or plate which is traversed by holes extending in the longitudinal direction.
• the entire cross section of the lid may have a plurality of holes.
• the fiber bundles form a network.
• the at least two fiber bundles against each other for example, ⁇ 80 °, inclined to the longitudinal axis of the body.
• the density of the network depends on the type of application of the body, the load to which the body is exposed, and the strength and dimensions of the body. If the body is expected to break up into smaller fragments in the event of breakage, a dense fiber bundle network is desirable. On the other hand, increasing the cost of fiber bundles increases the costs, so that the density of used and crosslinked fiber bundles should be individually adapted to the desired effects with regard to the resulting material costs.
• the ratio between adjacent fiber bundles / diameter of the fiber bundles is 5: 1 to 10: 1. It is a function of the mechanical stress of the body. The ratio of the proportional thermal resistance of the body is only slightly changed.
• the at least two fiber bundles can partially or completely span or reinforce the body.
• Full armor is desirable for heavily loaded bodies.
• end areas which are connected to other components in an apparatus such as a heat exchanger are particularly stressed or fracture-prone areas which may require special protection in the form of the reinforcement.
• the body is a thermally stressed component, it should further be considered that body and fiber bundles may have different coefficients of thermal expansion, and the length and width of the array of fiber bundles should be adjusted accordingly.
• the fiber bundles should therefore be arranged on the at least one outer side of the body in such a way that the thermal expansion of the body from the fiber bundles can be or can be compensated and does not lead to their destruction.
• the ceramic material is preferably densely sintered silicon carbide. Its selection is due to its excellent properties such as high thermal conductivity, high strength, high corrosion resistance to acidic and basic media and high load capacity.
• the silicon carbide is pressureless sintered silicon carbide, which has an extremely high corrosion resistance to acidic and basic media, which it can also withstand very high temperatures, high thermal shock resistance, high thermal conductivity, high wear resistance and a diamond-like hardness.
• the silicon carbide may be liquid phase sintered silicon carbide made of silicon carbide and various oxide ceramics and being high in strength.
• the silicon carbide may contain at least one ceramic or mineral filler, the choice of fillers being adapted to the application.
• fillers are substances from the group of naturally occurring flake graphites, artificially produced electrographites, carbon blacks or carbon, graphite or carbon fibers or boron carbide.
• ceramic or mineral fillers in grain, platelet or fiber form such as silicates, Carbonates, sulfates, oxides, glasses or selected mixtures thereof may be used.
• the fiber bundles are carbon fiber bundles.
• a carbon fiber has good tensile strength, corrosion resistance and rigidity, low elongation at break, and is durable at the load temperature of loaded bodies. The specific behavior of the carbon fiber bundles has the effect that the prestressing of the reinforcement is maintained even in the case of strongly changing or swelling loading of the pipe.
• the reinforcement Due to the negative thermal expansion coefficients of carbon fiber bundles, the reinforcement is further biased at a temperature increase, the bursting and sealing holding pressure is greater at higher temperature than at room temperature.
• the carbon fiber reinforcement improves the properties of bodies, particularly in silicon carbide tubes, as follows: increase in bursting pressure, body becomes less sensitive to steam shocks, and inadmissible excesses of operating pressure, as the bursting pressure of the body at room temperature is 30 to 40% higher than that at room temperature unreinforced body is increased.
• Other examples of the fiber bundles are glass fiber bundles or aramid fiber bundles.
• the frictional connection between fiber bundles and the outside of the body is an adhesive system. It serves to fix the fiber bundles on the body.
• the adhesive system is selected from the group consisting of adhesives composed of phenol resin, epoxy resin or polysilazane resin base. Possibly.
• the adhesive system may contain a silicon or silicon carbide filler. It is also referred to as putty in the present invention.
• the adhesive system may include one or more of the comprising adhesive and / or putty. If necessary, the adhesive or putty may further contain a curing catalyst and / or a plasticizer. Such adhesives or putties are usually resistant to oxidation. These adhesives or putty also adhere well to both a ceramic material such as silicon carbide and fiber bundles such as carbon fiber bundles, and are able to wet a fiber well.
• the adhesive system is a phenolic resin. More preferably, the phenolic resin is a resole. Alternatively, the phenolic resin may also be a novolak.
• Suitable epoxy resins are resin systems containing bisphenol A diglycidyl ether or bisphenol F diglycidyl ether. In particular, are suitable as an epoxy resin, resin systems containing in addition to more than 50 wt .-% of bisphenol A diglycidyl ether or Bispenhol F-diglycidyl ether Methylhexahydrophthalklareanhydrid in particular in an amount of 25 to 50 wt .-%, each based on the total weight.
• a Polysilazanharzsystem can be used as an adhesive system.
• All the above-mentioned adhesives may further contain silicon or silicon carbide as a filler.
• the plasticity of the cement can be adjusted via the proportion of resin in the mixture or by adding plasticizers of the desired adhesive bond.
• the use of a putty, which contains in addition to the resin adhesive silicon or silicon carbide as a filler, is particularly suitable when it is applied to the fiber bundles. By impregnation of the fiber bundles with the putty and subsequent firing, silicon with carbon fibers can form silicon carbide, or by silicon carbide as filler, the impregnated and fired carbon fiber has silicon carbide.
• the choice of the adhesive system depends on the desired binding and essentially on the nature of the field of use of the body according to the invention.
• an epoxy resin as an adhesive system, which is applied to the body or with which the fiber bundles impregnated and cured, for example, due to the brittleness of the cured layer greater stress relief is rather not possible, it will be a rigid connection between fiber bundles and get body.
• plasticizers this compound can be made more malleable, for example, to intercept possible shear stresses or different extents of fiber bundles and body in temperature changes.
• the body and fiber bundles may be fixed by means of an adhesive system wherein the adhesive system has been applied to either the body, the fiber bundles or both and then cured or fired.
• the body and the fiber bundles can each be provided with an adhesive system independently of each other and fixed together.
• the adhesive system applied in each case can be identical or different in this case. The choice depends on the desired adhesiveness and can be suitably selected and adjusted by the person skilled in the art.
• the adhesive system may be arranged selectively or in sections between the body and the fiber bundle so that a number of predetermined locations of the fiber bundles are fixed to the body.
• the fiber bundles may be completely fixed to the body by gluing. Preferably, the fiber bundles are completely fixed to the body.
• the fiber bundles can be in the form of a yarn, this is the case in particular if the fiber bundles are wound onto bodies and if necessary fixed.
• the yarn is a fiber bundle of a variety of filaments.
• the yarn may have straight, diagonal and / or curved portions.
• To form a network at least one, preferably two, yarns intersect at predetermined locations at a desired angle, preferably ⁇ 80 °.
• Yarn sections may also be sleeved, meshed or otherwise cross-linked.
• the fiber bundles can also be present as a braid, scrim, knitted fabric, woven or knitted fabric, preferably woven or knitted fabric, which is pushed onto the body under prestressing and possibly fixed.
• a braid is understood to mean a flat structure which, by crossing, runs diagonally in opposite directions Flecht thread systems are created, whereby the braiding threads intersect at an adjustable angle to the edge of the fabric.
• a scrim is understood as a sheet of one or more stretched, superimposed yarn systems of different orientation directions without or with fixation of the intersection points.
• a knit fabric is a fabric in which the stitches are formed from a horizontally submitted thread individually and successively, in addition, further thread systems can be integrated for reinforcement.
• a fabric is considered to be a fabric which contains at least two thread systems, which generally intersect at right angles.
• a knitted fabric is a fabric made from one or more yarns by simultaneously forming stitches in the longitudinal direction, in addition to reinforcement, of course, other yarns may be incorporated.
• the thread here is at least one fiber bundle of predetermined length. Under a thread system several threads are understood.
• the woven or knitted fabric has a greater length than the body, so that the woven or knitted fabric, if appropriate, the connection of the body to another component by its arrangement on the same protects.
• the body according to the invention can be produced by the following method, which comprises the steps
• a body comprising a ceramic material and suitable for use in a heat exchanger and for the passage of fluids
• the pressure resistance of the body which is generally required in apparatus construction, is achieved by reinforcing the body with fiber bundles.
• the bias voltage used according to the invention can be selected by the person skilled in the art be adjusted according to the fiber material and the field of application of the body.
• step b) comprises re-clamping at least portions of the outside of the body with at least two fiber bundles so that the fiber bundles are in the form of a network.
• fiber bundles can be suitably wound around bodies.
• step b) is carried out such that the ratio between adjacent fiber bundles / diameter of the fiber bundles is 5: 1 to 10: 1. Increasing the strength of the body is thus achieved with a relatively small coverage of the outside of the body.
• an adhesive system is at least partially applied to the fiber bundles and / or the body prior to step b) and then cured or fired.
• the adhesive system used for fixing is preferably selected from the group consisting of adhesives, which are composed of phenolic resin, epoxy resin or Polysilazanharzbasis and optionally mixed with silicon and silicon carbide filler.
• adhesives are well mouldable and conformable to the shape of the body, or are well suited for impregnating a fiber, have good adhesiveness to a ceramic material such as silicon carbide and many types of fibers and especially to a carbon fiber after heat curing or firing.
• the body and the fiber bundles may be fixed by means of an adhesive system, wherein the adhesive system is applied either to the body, the fiber bundles or both and then cured or fired.
• An adhesive system that does not contain silicon or silicon carbide as a filler is cured while an adhesive system containing silicon or silicon carbide as a filler is fired.
• the curing is preferably carried out at temperatures of 120 to 180 ° C within up to two hours, without pressure or at pressures of 0.5 to 1, 5 bar. At high temperatures, ie at 170 to 180 ° C, a curing time of up to 15 minutes is generally sufficient. The higher the temperature, the better ringer is the cure time. If the adhesive system contains a curing catalyst, the cure may also be at room temperature.
• the firing is preferably carried out at temperatures of over 1500 ° C within up to 2 hours, without pressure or at pressures of 0.5 to 1, 5 bar. After curing of the adhesive or firing of the cement, the fiber bundles are placed on the outside of the body.
• the body and the fiber bundles can be provided with an adhesive or putty independently of each other and then fixed.
• the adhesive or putty applied in this case may be identical or different in this case.
• the person skilled in the art can select suitable adhesives or putties which adhere well to one another.
• the fiber bundles are impregnated with an adhesive or cement, then hardened or fired and subsequently arranged on the body.
• the adhesive system can be arranged selectively or in sections between the body and fiber bundles so that a number of predetermined locations of the fiber bundles are fixed to the body.
• the fiber bundles can be completely fixed to the body by means of glue or putty.
• the fiber bundles are completely fixed to the body.
• the body used in the method according to the invention is a tubular body or lid, wherein a plurality of holes extend in the longitudinal direction of the lid.
• the ceramic material used in the process according to the invention is sintered silicon carbide optionally containing at least one ceramic or mineral filler.
• the fiber bundles preferably represent carbon fiber bundles.
• the carbon fiber bundles can be wound around the body under a predetermined pretension in the form of a yarn.
• the carbon fiber bundles are in the form of a braid, Geleges, knitted fabric, fabric or knitted fabric, preferably woven or knitted fabric, before and are pulled over the at least one outer side of possibly provided with a cured adhesive or baked cement body.
• the carbon fiber bundles are used in the inventive method as provided with a cured adhesive or fired cement fiber bundles.
• the use of a filler with silicon as a filler is suitable, since by the firing process silicon can react with the carbon fiber to form silicon carbide and thus a firmer bond between the carbon fiber and the cement is achieved.
• the body according to the invention is particularly suitable for use as a pipe, for example for heat exchangers with increased mechanical stress and / or extremely corrosive media and solvents, as well as all other components subjected to pressure and temperature.
• it is an ideal material for the construction of heat exchangers, because it is highly thermally conductive, pressure-resistant and insensitive to brittle fracture.
• the body according to the invention is particularly preferably used as a tube in a heat exchanger because it is resistant to erosion and permits high flow velocities and therefore a self-cleaning effect of the tube can be achieved by rapidly flowing media, which may be loaded with particles.
• the inventive body is preferably used as a tube sheet in a heat exchanger. In combination, a plurality of tubular bodies and lids according to the invention are used as a shell-and-tube heat exchanger.
• a heat exchanger comprising a body according to the invention, for example, the following structure according to DE 197 14 423:
• the heat exchanger comprises a shell, a bottom with nozzle, a spacer to create a distribution space, a distributor base with the inner and outer tube sheets and in arranged the bores of the tubesheets and sealed by means of a seal therein pipes.
• the bottom and the mantle are usually screwed, the spacer being interposed to create the distributor space.
• the inner tube bottom of the distributor base is smaller in diameter than the sheath inner diameter is formed.
• the outer tube sheet is formed larger in diameter and thus takes over the sealing function between shell and distribution space.
• the tubes represent the body according to the invention in the form of a tube of pressureless sintered silicon carbide, the outside of which is spanned by carbon fiber bundles under pretension.
• the bias of the reinforcement is advantageously increased by the negative thermal expansion coefficient of the carbon fiber.
• the heat exchanger now works more reliably and safely.
• the outer and / or inner tubesheet can furthermore consist of pressurelessly sintered silicon carbide, which is spanned by carbon fiber bundles under prestressing.
• the tubes besides the silicon carbide tube and the network of carbon fiber bundles for fixing the two elements furthermore have an adhesive system described above. If the adhesive system is resistant to oxidation, oxidizing media for cooling or heating can also be used in the service area of the heat exchanger constructed therefrom.
• Figure 1 is a schematic side view of a body according to the invention.
• Figure 2 is a further schematic side view of the body according to the invention shown in Figure 1, in which a partial cross-section is shown;
• Figure 3 is an enlarged detail of Figure 2, which is circled in Figure 2 with a dash-dot line and marked as III-III;
• FIG. 1 shows a schematic side view of a body 1 according to the invention.
• Body 1 comprises a smooth-walled tube 3 of pressureless sintered silicon carbide. At its two ends 5, 7, the tube 3 in each case has an opening in order to be suitable for the passage of fluids.
• the tube 3 is with yarns 9 wrapped carbon fiber bundles, which are under high bias and serve as a reinforcement of the tube 3.
• the yarns 9 have a phenolic resin layer (not shown) which acts as an adhesive layer.
• the yarns 9 are wound around the pipe 3 so as to cross each other at predetermined positions so as to form a network.
• FIG. 2 shows a further schematic side view of the body 1 according to the invention shown in FIG. 1, in which a cross section is partially shown.
• the smooth-walled tube 3 is also shown with the tube ends 5, 7, which is wrapped by yarns 9 of carbon fiber bundles with phenolic resin under tension.
• the part of the cross-sectional view further shows a tube wall 13 of the tube 3, which has an inner side 14 and an outer side 15.
• the inner side 14 defines the cavity 1 1 of the tube 3, which is unlimited in the longitudinal direction and ends at the tube ends 5, 7 in each case an opening. By the limited by the inside 14 cavity 1 1, a fluid can be passed.
• the yarns 9 are arranged on the outside 15 of the pipe wall 13.
• FIG. 3 shows an enlarged detail from FIG. 2, which is circled in FIG. 2 with a dash-dot line and identified as III-III.
• the same reference numerals as in FIG. 2 are used for the same elements. Due to the enlarged view can be seen that the yarns 9 are arranged on the outer side 15 of the tube wall 13, while through the inner side 14 of the tube wall 13 of the cavity 1 1 is formed.
• FIG. 4 shows a cross section through a partial region of a further body 41 according to the invention.
• the body 41 according to the invention represents a smooth-walled tube 43 made of silicon carbide sintered without pressure.
• the tube 43 has a tube wall 413 which has an inner side 414 and an outer side 415.
• a phenolic resin adhesive 417 is disposed, on which yarns 49 of carbon fibers are arranged.
• the adhesive 417 is located only in areas of the outside 415 of the tube 413, in which the Yarns 49 are arranged.
• the adhesive 417 serves to fix the yarns 49 on the outside 415 of the pipe wall 413.
• the pipe has a cavity 41 1 which is delimited by the inside 414 of the pipe wall 413 of the pipe 43.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Ceramic Products (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

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Citations (6)

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• 2009
  • 2009-12-17 DE DE102009054910A patent/DE102009054910A1/de not_active Withdrawn
• 2010
  • 2010-11-10 CA CA2783126A patent/CA2783126C/en not_active Expired - Fee Related
  • 2010-11-10 RU RU2012130063/06A patent/RU2012130063A/ru unknown
  • 2010-11-10 JP JP2012543555A patent/JP2013514512A/ja active Pending
  • 2010-11-10 KR KR1020127018279A patent/KR101426631B1/ko not_active IP Right Cessation
  • 2010-11-10 EP EP10784732A patent/EP2513589A1/de not_active Withdrawn
  • 2010-11-10 BR BR112012014847A patent/BR112012014847A2/pt not_active IP Right Cessation
  • 2010-11-10 CN CN2010800574519A patent/CN102713493A/zh active Pending
  • 2010-11-10 WO PCT/EP2010/067211 patent/WO2011082866A1/de active Application Filing
• 2012
  • 2012-06-18 US US13/525,856 patent/US20120267087A1/en not_active Abandoned

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