MXPA97007925A - Heat exchanger system ceram - Google Patents

Abstract

A heat exchanger (10) provided with ceramic tubes (60) is described, to be used as a recuperator in an oven for example, which provides a seal on the tube-to-tube sheet including two pieces of tile (58, 59) which attach a ball seal (70) which holds the ends of the ceramic tubes in the assemblies of the tube sheet (51). The ball seals allow axial and angular movement of the tubes (60) relative to the tube sheet assemblies (51) to reduce tube fracture and seal failures due to differences in thermal expansion and the weakness of the tube. the ceramic tubes. The tube sheet assemblies (51) are metallic and are designed with a double wall configuration containing cooling ducts (65) to prevent casting due to high temperatures.

Description

SYSTEM EXCHANGED! OF CERAMIC HEAT DESCRIPTION OF THE INVENTION The present invention relates to high temperature heat recovery systems. More particularly, the invention is a high temperature heat exchanger made of refractory and ceramic materials which can operate in gas streams of up to about 1,500 ° C. Ovens for transferring heat to products processed at very high temperatures (such as for glass or metal melting) result in gas temperatures in the stack at approximately the temperature of the furnace bed. In addition to the fuel which must be added to the furnace to melt the product, the fuel must also be added to heat the combustion air to the average temperature in the furnace. Without some type of heat recovery system in the chimneys, the energy associated with the flue gases is lost when the gases are vented outside the system at the furnace temperature. The heat exchangers are therefore routinely used to recover the enthalpy of flue gas by transferring this heat to the incoming combustion air. However, ultra high operating temperatures create a highly erosive and destructive environment for most engineering materials including steel. There is a need in the art for a heat exchanger capable of operating efficiently at such high temperatures. All metal heat exchangers are known as described in British Patent No. 191,175, assigned to Walker, which describes a metal gas cooler having a double tube sheet design in which the gas tubes are arranged between two walls of each tube sheet. The gas process is designed to pass through the tubes and while the cooling liquid passes over the outside of the tubes. The stated purpose of the two walls is to ensure that none of the cooling liquid makes contact with the process gas. Such heat exchangers are limited in temperature due to all construction metals and are unable to operate in hot gas streams over 850 ° C for long periods of time without inevitable tube failures. Attempts have been made to develop designs for high temperature heat exchangers using tubes and sheets of tubes made of ceramics or refractories or a combination of similar materials. The known ceramic heat exchangers have had limited events due to faults in three areas. The first is in the tubes where the complications occur due to the oxidation or chemical deterioration of the ceramic materials which cause the tubes to fracture. Another mode of tube failure is a phenomenon known as thermal shock which happens if the ceramic tube is heated or cooled very quickly, at an acceptable speed. The second area of error is in the seal between the tube and the tube sheet. The ceramic heat exchangers currently available have ceramic fiber materials which form a seal between the outer surface of the tube and the inner surface of the tube sheet. In some cases the end of the tube is also designed to press against a ceramic fiber ring which in turn is maintained in a relief cut within the opening of the tube in the tube sheet. When such ceramic heat exchangers are cycled between cold and hot conditions, the tubes and sheets of the tube expand and contract. The expansion of the tubes compresses or deforms the ceramic fiber seal which has no memory of its original shape. After a few cycles, the seal material rapidly disintegrates into powder which flows out of the seal area. Some ceramic fiber materials can also melt on the seal at extreme temperatures or after the chemical exposure of the process. During the next cooling cycleAs the tube contracts and retracts from the seal, the molten seal material fills the resulting gap and hardens. When these types of ceramic heat exchangers are brought back up to the operating temperature, the tube expands before the deformed seal material can be blown out of shape. This causes the tube to fail or cause the tube to push the tube sheet out of position resulting in leakage of the tube sheet. The third failure mode comes from conventional designs of tube sheets, the most common of which requires refractory blocks or ceramic tiles stacked one on top of the other, to form the tube sheet. In some designs there are grooves or interlocking notches which have alignment keys or ceramic fiber material to seal the joints between adjacent blocks or tiles. Such tube sheets expand and contract with the hot and cold temperature cycles of the process with differential expansion from the hot side to the cold side as soon as the tubes absorb the heat from the process stream. For example, if the process flow is introduced into such heat exchangers at the bottom of the tube sheet at 1,400 ° C, it can exit the heat exchanger from the top of the tube sheet at 1,200 ° C, causing a reduced thermal expansion ratio in the upper part of the tube sheet relative to the bottom. This differential expansion can break the joints between the tiles that build the tube sheet and cause misalignment between the tube sheets of the ceramic heat exchanger which in turn can bind or break the tubes. There are also problems in the seals and seals which jointly hold the refractory blocks or ceramic tiles. Joints and seals usually have a binder to hold the tiles in place. The problem is that the tubes are much stronger than the design of the bonding material currently known. When the seals of the tube melt or degrade, the expanded tubes can push against the tube sheet and break the bond of the tile which will destroy the integrity of the sheet of the sheet and cause it to leak. The filtrations can also be caused by eutectic formations on the hot side of the gas of the tube sheet made of refractory blocks or ceramic tiles. Chemistries vaporized in the hot gas can attack the side surface of the tube sheet of the tube and cause a reduction in the melting temperature of refractory block surfaces or ceramic tiles. At hot operating temperatures, the surface of such tube sheets can melt, and this molten material from the surface can be introduced into the cracks which develop at the bond between the tiles. In the next cooling cycle, the molten material within the cracks solidifies and the tube sheet is unable to return to its original shape. Over time this will distort the tube sheet and will cause misalignment of the tube resulting in tube bonding and breakage. Attempts have been made to develop high temperature ceramic heat exchangers. For example, U.S. Patent No. 4,632,181, assigned to Graham discloses a ceramic heat exchanger of a tube design and cover with a tube sheet made of a series of stacked tiles. The Graham patent is typical of the state of the art, it describes tubes, tube seals and tube sheet walls which suffer from weakness as discussed above. U.S. Patent No. 4,449,575, assigned to Laws discloses a heat transfer system in which the ceramic tubes are mounted in a fluid bed reactor furnace. However, the design of Laws requires a means of metal lock to compress a fibrous ceramic seal against the ceramic tube which limits it to operate at temperatures below 900 ° C. The ceramic fiber seals also degrade over time and expand the tubes causing a permanent deflection of the packing as described above. British Patent Application No. GB2015146A by Laws discloses a tube and cover heat exchanger having ceramic tubes mounted within a wall made of parallel elongated ceramic tube blocks held in place by metal bolts. Metal bolts limit this system to operate in temperatures below 900 ° C, and the walls supported by the bolts develop filtrations through the seals that expand with the formation of ashes over time. U.S. Patent No. 4,122,894, assigned to Laws et al., Discloses another conventional ceramic tube and shell heat exchanger having a tube opening covered in the tube sheet into which rings can be infected. Packing of different diameter concentric with the tube. This design also requires a ceramic fiber seal which rigidly restricts the tube and which is prone to center as soon as the tube expands into the tube sheet, as indicated above. U.S. Patent No. 4,106,556, assigned to Hewym et al., Discloses a ceramic heat exchanger system where two sheets of pipe are mounted one on top of the other on the same side (top) of a gas duct hot. The Heym tube sheets must have metal plates on the surfaces exposed to the process gas and all the tubes are kept in their respective tube sheets with metal closure rings which, again, limit the design to operate at temperatures below 900 ° C. U.S. Patent No. 3,923,314 assigned to Lawler et al. describes a heat exchanger made of silicon carbide tubes mounted on a silicon carbide tube sheet. The silicon carbide exchanger is specifically designed to heat aqueous, highly corrosive streams, acid at about 205 ° C and is not suitable for high temperature heat exchange. There is a need in the art for a practical design which corrects the deficiencies indicated here above and allows a heat exchanger to operate at very high temperatures without failure of the tube, tube seal or tube sheet. Ceramic heat exchangers currently available have problems of tube and tube sheet seal due to a lack of freedom in physical mobility which, this description identifies as a requirement to protect the system against large thermal expansions and contractions experienced during the operating cycles between the operation of low and high temperatures. The present invention is a shell tube type heat exchanger which has the advantage of the high temperature characteristics of ceramic and refractory materials but at the same time provides tolerances for its limitations. The new heat exchanger consists of a rigid refractory lined cover with the tube sheets at both ends. Between the respective tube sheets, the tubes of the ceramic heat exchanger are mounted with a slide fit within the seal assemblies on the tube sheet. The ceramic exchanger tubes have textured or external and internal elongated surfaces. The space between the ball seal and the curved cavity in the tiles is filled with ceramic fiber to form a seal and to act as a mode for the ball seal. The ceramic fiber material also forms a joint which prevents gas from leaking between the two tiles of the tube sheet. The seal assemblies are designed to allow the expansion and contraction of the tube to be absorbed without displacement of the rigid tube sheet. This ability to allow free expansion or contraction of the tube is required, since even the tubes within a single heat exchanger passage have different temperatures from the top to the bottom of the tube sheet. Accordingly, the seal assemblies of the present invention allow both axial expansion and contraction of the tube as well as the angular freedom of movement to prevent the development of a moment force on the tubes of the ceramic heat exchanger. Such seal mounting means allows operation of the heat exchanger in the temperature range from about 900 ° C to about 1600 ° C, with the heat transfer achieved by a combination of convection and thermal radiation. The new seal assembly design is incorporated into the ball seal system, the ball seal is mounted on the tube sheet and allows angular freedom of movement for the ceramic tube. The known designs of metal heat exchanger have points of attachment of the rigid tube in the wall of the tube sheet which can absorb only angular deflections of the tube through the inspection of the tubes. Unlike metal tubes, the known ceramic tubes will fracture if they are forced to curl beyond the allowable pressure levels of the material. An important feature of the ball seal of the present invention is that its radius of curvature is determined from the center line of the ceramic tube in two planes in order to achieve the required angular freedom of movement. The ball seal, mounted on each tube sheet, at each end of the tube, must be able to absorb the total thermal expansion or contraction of the tube in the event that the tube takes all of its movement at one end only. The new ball seal with its angular freedom of movement solves the problem that results in most tube failures found in currently known designs. Another innovation in the design of the novel ceramic heat exchanger is in the location and design of fibrous ceramic seals. The ball seal is mounted on the tube sheet by two pieces of tile. One of the pieces of tile is the side tile of the tube, and the other is the side tile of the process. These two tiles are joined in the middle of the tube sheet by threads or a bayonet mount. At the junction of the two pieces of tiles, there is a curved surface which has a slightly larger radius in two planes than the radius of the ball seal. In this way, the two pieces of tile are joined in a joint which has a curved surface having a radius in the transverse plane which is greater than the radius of the ball seal and a radius in the longitudinal plane which is also greater than the radius of the ball seal. Additionally, each radius is formed in a shoulder to cause the longitudinal curve of the two tile pieces to approach the surface of the ball seal at each end of the curved surface of the joint. An additional innovation of the new ceramic exchanger is in the structure of the tube sheet. In order to prevent the problems associated with the tube sheets made of refractory blocks or ceramic tiles which are deflected by the expansion of the tube or the accumulation of ash deposits in the seals, the currently described ceramic heat exchanger has a double wall of stainless steel cooled by gas with both refractory sides. This wall is exceptionally rigid and strong due to the two parallel metal wall plates joined by a gap spacing means, preferably a short piece of welded pipe for both plates and concentric for the center line of each location of the ceramic pipe. This makes the two plates of the metal wall very rigid and makes the tube sheet very strong. On both sides of the double metal plates are fusible insulation refractories that protect the structure of the internal stainless steel wall. The side tiles of the tube and the side tiles of the process each have a flange on the outer end which overlaps the meltable insulation material causing the tile pieces to act as refractory anchors. Depending on the differential temperature between the gas on the process side and the hot gas stream, the thickness of the insulation refractory on both sides of the double metal wall can be adjusted to achieve an equal temperature on both sides of the metal double wall . This eliminates the pressures on the metal wall structure due to the differential temperatures between the tube sheet. The space between the double metal walls of each tube side is used as a cooling conductor, this cooling gas is pumped into the duct where it removes excess heat which flows from both sides of the tube sheet towards the central double metal walls. This cooling system allows the process gas on one side of the tube sheet and the hot gas on the other side of the tube sheet to be at much higher temperatures than the metal structural wall in the center of the tube sheet . Under operating conditions, the hot gas may be at approximately 1,500 ° C and the process gas may be approximately 1,000 ° C, while the double metal wall can be maintained between approximately 700 and approximately 800 ° C. The wall cooling gas can be either ambient air at about 25 ° C causing it to flow into the wall cooling conduit, or steam. Steam of about 100 to about 150 ° C is an excellent refrigerant since it has a specific heat which is almost twice the specific heat of the ambient air. One or more thermocouples can be installed in the double metal wall, which can be used to indicate the temperature in the wall while the unit is in operation. The output of the thermocouple can also be used as an input for an over-temperature alarm, a limit switch which can stop the process and the tube sheet overheats, or can provide an indication of the temperature to a temperature control circuit which It can be used to maintain a pre-set temperature in the tube sheet of the ceramic heat exchanger. The new ceramic heat exchanger is constructed of modules which consist of several different models depending on the number of tubes and the arrangement of the tube in the tube sheet. Depending on the application requirements, two or more modules of the exchanger can be applied in series (forming different steps) or in parallel (forming a single step) or a combination of both arrays in series and in parallel for larger applications of heat exchangers . Each module has its own tube sheet cooling system to ensure that the tube sheet at each end of the module is within the allowable temperature limit. A system suitable for the present invention may consist of a high temperature furnace in which the temperature of the exhaust gas is between about 800 to about 1,600 ° C. The primary furnace of this system must be part of a process which accepts the preheating of combustion gas in the furnace. The ceramic heat exchanger described here is mounted in the kiln exhaust duct and is designed to lower the exhaust gas temperature by recovering the heat. The exhaust gas passes through the cover of the heat exchanger and on the outside of the tubes. Simultaneously, a fan extracts the ambient air which passes through the tubes of the heat exchanger on the path to the furnace burners. The air starts at room temperature as it enters the ceramic heat exchanger tubes and increases in temperature until it exits the heat exchanger at about 400 and about 1,100 ° C. The preheated pre-combustion air is sent to the furnace burners where the fuel is added and burned. The heat contained in the combustion air reduces fuel consumption by the amount of fuel needed to heat the combustion air from the ambient temperature to the temperature at the outlet of the last passage of the tubes in the heat exchanger. The fuel savings in some cases can be as high as 50 percent due to the exceptionally high temperature ratio of this new ceramic heat exchanger design. A unique feature of this heat recovery process is the special cooling system for the double walls of the tube sheet. The cooling air which is absorbing heat from each tube sheet can be vented to the gas inlet of the process where the heat of the tube sheets can be recovered by the process. This invention describes the development of a novel type of high temperature ceramic heat exchanger which solves the weakness of previous designs. The improvements contained here allow the heat exchanger to present, operate at limit of materials currently available and increase the potential applications of heat recovery technology. BRIEF DESCRIPTION OF THE DRAWINGS The unique advantages of the present invention will become apparent to one skilled in the art upon reading the following specification and by reference to the drawings in which: FIGURE 1 is a vertical cross-section through the vertical center line of the ceramic heat exchanger. FIGURE 2 is a vertical cross section through the ceramic heat exchanger along section AA of FIGURE 1. FIGURE 3 is a vertical cross section through the ceramic heat exchanger along the section BB of FIGURE 1. FIGURE 4 is a sectional detail showing the details of pipe termination for adjacent pipes. FIGURE 5 is a sectional detail of the ceramic tile lateral to the tube. FIGURE 6 is a sectional detail of the ceramic tile lateral to the process. FIGURE 7 is a sectional detail of the ball seal. FIGURE 8 is a sectional detail of a ball seal plug used to replace a broken tube. FIGURE 9 is a partial sectional view along section CC of FIGURE 4. FIGURE 10 is a partial sectional view along section DD of FIGURE 4. FIGURE 11 is a partial sectional view of the duct of cooling between the walls of the sheet of the double metal tube along the section EE of FIGURE 4. FIGURE 12 is a drawing of the stile details of the sheet of the double-walled metal tube in the outer housing of the Ceramic heat exchanger. FIGURE 13 represents the upright details of the upper right corner of FIGURE 12. FIGURE 14 is a sectional view along section FF of FIGURE 13. FIGURE 15 is a schematic view of the process where the heat exchanger Ceramic provides heat recovery for a high temperature furnace. The design of this invention for the high temperature heat recovery system is best shown in the accompanying drawings. FIGURE 1 shows a vertical sectional view of the high temperature ceramic heat exchanger 10 which is a key part of the heat recovery system. FIGURE 2 and FIGURE 3 show the sections taken through the ceramic heat exchanger on the line of section A-A and the line of section B-B. The ceramic heat exchanger 10 consists of a metal cover 11 which is coated with a high temperature refractory coater 12. The refractory coater 12 is designed with suitable insulating qualities in such a way that the metallic external temperature of the ceramic heat exchanger 10 is in the range of 50 to 120 ° C. On the lower part of the metal cover is a hot gas inlet 13 which has a refractory liner 14 and is directly connected to a source of hot gas through a metal duct 31 which also has a refractory liner at the rim. 15 hot gas inlet. In the upper part of the metal cover 11 on the opposite side of the hot gas inlet 13 is the hot gae outlet 17 which also has a refractory liner 18, the hot gas outlet 17 has a connecting duct 33 which has a refractory lining 34 and is connected to the hot gas outlet 17 in the flange 19. The hot gas outlet duct 17 carries the hot gas to another step of the ceramic heat exchanger or some type of gas cleaning system before venting the gas into the environment. The hot gas inlet 13 and the hot gas outlet 17 may be in a vertical orientation shown in FIGURE 1 or may have a horizontal orientation which is not shown. Attached to the metal cover 11 of the heat exchanger is the process gas inlet duct 21 which may have a refractory liner 22 if the process gas is hot or may have a refractory liner in case the gas process is at room temperature. The process gas inlet duct 21 is attached to the metal cover 11 in the flange 23. At the opposite end of the metal cover 11 of the heat exchanger is the process gas outlet duct 24 which has a jacket 25 is refractory and is attached to the metal cover 11 of the ceramic heat exchanger in the flange 26. In both inlet 41 of process gas and process gas outlet 42 for the ceramic heat exchanger and rigidly attached to the metal cover 11 are the assemblies 51 of the inlet tube sheet. The details of the joining of the sheets of the tube to the metal cover, will be described in greater detail later. The tube sheet assembly 51 as shown in detail in FIGURE 4, consists of an internal metallic structure 52 composed of the plate 53 lateral to the process and the lateral protruding plate 54, which are parallel stainless steel plates separated by the 56 spacer tubes which are concentric to the centerline of the tubes 60 of the ceramic heat exchanger. The side of the tube sheet assembly process 51 has a moldable insulation refractory 57 which is molded onto the external surface of the plate 53 lateral to the process. The castable refractory is a lightweight mouldable refractory of Harbison-Walker or the like and is capable of a maximum temperature service of 1815 ° C. On the process side of the assembly 51 of the tube sheet and concentric, each center line of the ceramic tube 60 is the tile 58 lateral to the process which has a male thread 61 which couples the side tile 59 to the hot gas through the the female thread 62 On the hot gas side of each tube sheet assembly 51, there is a moldable insulation refractory 64 which has similar specifications to the moldable insulation refractory 57 on the process side of the tube sheet assembly 51. Also concentric to each center line of the tube 60 of the ceramic heat exchanger is a tile 59 lateral to the hot gas. Tile 58 lateral to the process and tile 59 side to hot gas have 40 ceramic fiber joints at both ends of the ceramic thread assembly to act as a gas tight seal. The tile 58 lateral to the process and the tile 59 lateral to the hot gas are made of ebony carbide ceramic materials or their equivalents. Between the tile 58 lateral to the process and the tile 59 of hot gas and concentric to the central line of the center line of the tube of the ceramic heat exchanger is the ball seal 70. The ball seal 70 has a hole 43 stratified through the center line member with the larger diameter 44 facing the hot gas side of the tube sheet assembly. The larger diameter 44 is slightly larger than the outer diameter 75 of the tube 60 of the ceramic heat exchanger allowing the tube 60 of the ceramic heat exchanger to move freely in the ball seal. An important feature of the design of the novel ceramic heat exchanger 10 is the rigid connection of the assemblies 51 of the tube sheet to the metal shell. As soon as the hot gas heats up during the start, the refractory lining 12 will heat up and isolate the metal cover 10 from most of the heat, but eventually the metal cover will absorb a temperature between 50 and 120 ° C and will expand slightly. This expansion will increase the distance between the assemblies 51 of the tube sheet by 1.5 to 4.0 millimeters, if the assemblies of the tube sheet are approximately 2 meters apart. This makes the external dimensions very stable and means that some other system must be used to take into account the expected differential expansion of the hot ceramic tubes 60. Between the two tube sheet assemblies 51 there is a number of ceramic tube 60, which transfers the heat from the hot gas side to the process side. The ceramic tubes can be made of chemical resistant ceramic materials depending on the application of ceramic heat exchanger 10. For tubes that use typical air for the application of air heat transfer, they should be constructed of an oxidation resistive ceramic such as alumina, reinforced with silicon carbide particles (SiC / Al203) which is manufactured by DuPont Lanxide Composites, Inc. or its equivalents. As soon as the temperature in the ceramic heat exchanger 10 increases during the start, these tubes 60 of the heat exchanger will expand and increase in length from 10 to 30 millimeters. The differential expansion between the metal cover of the heat exchanger and the tubes 60 of the ceramic heat exchanger at a total temperature is absorbed by the sliding fit between the external diameter 75 of the ceramic tube 60 and the larger diameter 44 of the seal 70. of ball in each location of the tubes 60 of the heat exchanger in the assemblies 51 of the tube sheet. The expansion of ceramic tubes 60 may vary within a single bundle of tubes. In FIGURE 4 the ceramic tube 60 is shown in its cold position with the end 46 of the ceramic tube separated from the step 47 in the hole 43 of the ball seal 70. As soon as the temperature of the ceramic heat exchanger 10 is increased, the ceramic tube 60 expands. Its length increases until the end 46 of the ceramic tube moves to its hot position 46A. Still in the hot position 46A, there still exists a small space 48 which prevents the ceramic tube 60 from applying any force to the assembly 51 of the tube sheet. Each tube sheet assembly 51 has a cooling conduit 65 defined by the internal surface 66 of the process side plate 53, the inner surface 67 of the plate 54 lateral to the hot gas, and the external surface 68 of the spacer tubes 56. . This cooling duct 65 is used to pass a cooling gas through each tube sheet to remove the excess heat that is transferred through the moldable refractory 57 on the process side or the molten refractory 54 on the hot gas side. The cooling gas can be air, steam or any other type of refrigerant flowing in gas. The refrigerants of the tube sheet enter the cooling conduit 65 of the tube sheet through an inlet conduit (not shown) attached to the flange 81 and through the pipe 82 to a distributor 71. The refrigerant passes over the surface 68 of the tubes 56 spacers and take heat from the inner surface 66 of the plate 53 lateral to the process and the internal surface 67 of the plate 54 from the side of the hot gas. This refrigerant is collected in the outlet manifold 72 of the refrigerant conduit where it is conducted through the outlet pipe 83 attached to the outlet conduit (not shown) in the flange 84 as soon as it exits the heat exchanger 10. ceramics. The refrigerant is used to remove the heat from the internal metallic structure 52 in the tube sheet. The assemblies 51 of the tube sheet of the ceramic heat exchanger 10 are composite structures as shown in FIGURE 4, with specific components shown in FIGS. 5, 6 and 7. The tube assembly 51 of the tube is structurally constructed around the internal metallic structure 52. On the hot gas side of each seal assembly 50 of the ceramic tube 60, is the tile 59 lateral to the hot gas embedded in the insulation castable refractory 64. The tile 59 lateral to the hot gas has a flange 91 which acts as a refractory anchor to retain the moldable refractory 64 in its place. Between the flange 91 and the moldable refractory 64 is a ceramic fiber gasket 95 which achieves a gas tight seal. The outer cylindrical surface 92 of the tile 59 lateral to the hot gas is held in alignment by the internal surface 69 of the spacer tube 56. As soon as the moldable refractory 64 is molded onto the hot side plate 54 of the internal metallic structure 52, it links to the outer surface 92 and fills four plains 94 molded on the outer surface 92 of the hot gas tile 59. The four llanoe 94 assist in the erecting of the moldable refractory 64 in that location and link the hot gas tile 59 to the moldable refractory to prevent tile 59 side to the hot gas from changing when tile 58 from the side of the process is threaded into the thread 62 female of tile 59 on the hot gas side. The hot gas tile 59 has a conical surface 96 with its large diameter 97 on the hot face 93 and its small diameter 98 in the receptacle 100 of the hot side ball seal. The conical surface 96 is concentric to the center line of the ceramic tube 60 and provides a clearance, such that the ceramic tube 60 can absorb the angular deflection in the event that the thermal expansion ratio is different between the mounts 51 of the tube sheet of the adjacent ceramic exchanger 10. The tile ball seal receptacle 100 of the warm gae side 59 also has a radius offset 102 from the center line 103 of the ball seal receptacle 100. The deflection 102 reduces the gap between the ball seal receptacle 100 and the ball seal 70 to a minimum at the edge 105 of the ball seal receptacle 100. The reduced gap at the edge 105 is designed to retain a ceramic fiber gasket 107 which is installed between the ball seal receptacle 100 and the ball seal 70 over many heating and cooling cycles - of the heat exchanger 10 ceramics. On the process side of the assembly 51 of the tube sheet, in each eello assembly 50 of the ceramic tube 60, there is a tile 58 on the side of the process which is embedded in the moldable insulation refractory 57. The tile 58 on the process side has an outer cylindrical surface 112 which is free to move in the castable insulation refractory 56. A flange 103 is molded into the tile 58 of the process side to act as a refractory anchor for the moldable insulation refractory 57. Between the rim 113 and the castable refractory 56, there is a ceramic fiber gasket 119 which achieves a gas tight seal. The castable refractory 56 is installed on the process side of the internal metallic structure 52 before the tile 58 of the process side is installed. The tile 58 on the process side has a conical surface 114 with its large diameter 115 on the hot side 117 and its small diameter 116 at the end 118 of the process of the hole 120 of hexagonal shape. The hexagonal shaped orifice 120 is designed to accept a hexagonal driver (not shown) intended to allow tile 58 of the process side to be installed in the tube sheet assembly 51 by engaging the male thread 61 in the female thread -62 in tile 59 on the side of the hot gas. The conical surface 114 and the hole 120 of hexagonal shape are concentric to the center line of seal assembly 50. The hexagonal-shaped orifice 120 terminates in the receptacle 121 of the ball seal on the process side. The receptacle 121 of the ball eello is also designed with a deviation 123 of the radius 122 from the center line 103 of the ball seal receptacle 121. This deviation 123 reduces the clearance between the ball seal receptacle 121 and the ball seal 70 at a minimum at the edge 125 of the ball seal receptacle 121. The reduced clear at the rim 125 is designed to retain a ceramic fiber gasket 107 which is installed between the ball seal receptacle 121 and the ball seal 70. The hot gas side of the tube sheet assembly 51 is usually at 200 to 300 ° C above the temperature on the side of the flow gae of the tube sheet assembly 51. At the same time the temperature in the internal metallic structure 52 of the tube sheet assembly can be 100 to 200 ° C below the temperature on the gas side of the process of mounting 51 of the tube sheet. Since the internal metallic structure 52 is manufactured from parallel stainless platesIt is desirable to keep both plates 53 on the process side and plate 54 on the hot side at the same temperature to avoid the development of thermal pressures which can cause the internal metallic structure 52 to bend. This can be achieved by adjusting the height of the moldable refractory 64 on the hot side relative to the thickness of the castable refractory 57 on the process side of the tube sheet assembly 51. As an example if the hot gas temperature is 1400 ° C and the process gas temperature is 1200 ° C with a design temperature of 800 ° C on the internal metallic structure 52, the ratio of the moldable thickness can be determined from the relationships Of temperature. The temperature of the hot gas minus the temperature of the internal metallic structure 52 is 600 ° C while the temperature of the process gas minus the temperature of the internal metallic structure 51 is 400 ° C. The difference of the hot side of 600 ° C is 1.5 times the difference of the process side, therefore the hot-meltable refractory 64 must have 1.5 times the thickness of the moldable refractory 57 on the process side. This will balance the temperature on both sides of the internal metal structure 92 and will prevent any bending of the tube sheet assembly. The hot side ball seal receptacle 100 and the ball side receptacle 121 of the process side are designed to capture and retain the ball seal 70 when the hot gas side tile 59 and the process side tile 58 they are assembled in the assembly 51 of the tube sheet. The ball seal 70 is designed to provide a slide fit with the end of the ceramic tube 60. For ceramic heat exchangers 10 where high gas filtration ratio between the hot side and the process side is acceptable, the ball eel 70 can have a larger diameter 44 designed to accept the larger outer diameter of the tile 60 of ceramics as eepecific by the manufacturer of ceramic tube 60. This means that the maximum clearance between the larger diameter 44 of the ball seal 70 and the ceramic tube 60 with a minimum acceptable diameter (within tolerances allowed) will establish the filtering ratio of the ceramic heat exchanger 10. This can result in a clearance between the ball seal 70 and the outer diameter of the ceramic tube 60 which can be as large as 2 to 3 mm which can result in filtration ratios of 7 to 10 percent. In ceramic heat exchangers 10 where a minimum filtration between the process side and the hot side is acceptable, the ceramic tube 60 can be connected to a preventable external diameter. At the same time, the larger diameter 44 of the ball seal 70 can be constructed to a diameter which is 0.25 to 0.30 mm greater than the outer diameter of the ceramic tube 60. This small gap along with the friction losses between the operated surface 75 of the ceramic tube 60 and the larger diameter 44 of the ball seal 70 can achieve filtration ratios below 1 percent depending on the differential pressure between the process side and the hot gas side of the ceramic heat exchanger 10. The ball seal 70 is the end bracket for the ceramic tube 60, therefore it must be designed to absorb the differential expansion caused by heating the ceramic tube. The expansion may be different for different ceramic tubes 60 within the tube assembly member 51 of the tube sheet. As an example, the ceramic tubes 60 at the point where the hot gae makes initial contact with the ceramic heat exchanger 10 will be of the highest temperature that the ceramic tube 60 will be at the point where the hot gae leaves the heat exchanger 10 of ceramic This means that the ceramic tubes that make contact with the hot gae can grow 2 to 8 mm higher than the ceramic tubes on the cooling side of the ceramic heat exchanger 10. The ball seal 70 must absorb the expansion as well as support the ceramic tube 60. Also the ceramic tube 60 can be expanded equally in the extremes or it can remain fixed at one end while the entire expansion is absorbed by the ball seal 70 at the other end. As a result, the larger diameter 44 of the ball seal 70 must have a length which is at least 1.6 to 1.8 times the total thermal expansion expected by the hottest ceramic tube 60 in the ceramic heat exchanger. This will prevent the cooled ceramic tube 60 from being pulled freely from the ball seal 70. The ball seal 70 also has a ball seal orifice 43 which is equal to the internal diameter of the ceramic tube 60. The hole 43 of the ball seal together with the step 47 of the ball seal hole forms a stop to hold the ceramic tube 60 in place. The ball seal hole 43 must be long enough to provide a stoppage of adequate force. The length of the larger diameter 44, the hole 43 of the ball eello, and the diameter of the ceramic tube 60 establish the minimum diameter of the ball eel 70. The radius of the ball seal 70 in two planes must be calculated from the center of the ceramic tube 60 to function properly. The ceramic heat exchanger 10 described in this application has the feature that any ceramic tube 60 in the tube sheet assembly can be changed without removing the adjacent ceramic tubes 60 when the ceramic heat exchanger 10 is cooled. If a ceramic tube 60 is damaged, it can be removed by taking a hexagonal pulse (not shown) and placing it in hole 120 hexagonally in tile 58 on the process side. Using the hexagonal driver the tile 58 on the process side will unscrew from tile 59 on the hot gas side and will be removed from one of the two assemblies 51 of the tube sheet. After a metal rod or tube (unmoved) is passed through the damaged ceramic tube 60 until it comes from the tube sheet assembly 51 at the opposite end of the damaged ceramic tube 60. The ball eello 70 and the damaged ceramic tube 60 can then be removed by sliding it along the inert metal rod or tube. The replacement ceramic tube 60 is then inserted by pushing it onto the metal rod or tube until it slides within the larger diameter 44 of the ball 70 of the tube assembly 51 of the tube. Then the ball eel 70 is reinstalled in the ball eello receptacle 100 in tile 59 of the hot gas side and de-solved over the operated diameter 75 of the ceramic tube 60. The inserted metal rod or tube is removed and then the tile on the process side is reinstalled in the tube side assembly by coupling the male thread 61 on the female thread 62 in tile 59 of the hot gas side using the hex driver. In the event that a reserve ceramic tube 60 is not available, the ball seal 70 with its orifice 43 can be replaced with a solid ball seal 78 shown in Figure 8 at each end of the ceramic failure tube 60. This forms a gas-tight repair in both mounts 51 of the tube sheet and allows the ceramic heat exchanger 10 to be placed back to the line. The solid ball seal 78 can then be replaced by a new ceramic tube 60 and the two ball seals 70 in the next scheduled maintenance period. Ceramic heat exchanger 10 can operate with some of its ceramic tubes removed and blocked; However, it reduces the heat transfer efficiency. Figure 9 shows the hot side view of three ceramic tubes 60 and the ball seal assemblies 50 and Figure 10 shows the process side view of the tube sheet assembly 51 with three tile locations 58 on the side of process. Unlike the prior art, the ceramic heat exchanger 10 described herein can have any arrangement of ceramic tube 60 in the tube sheet assembly. Figure 9 and Figure 10 show the most compact arrangement where the adjacent ceramic tubes are equidistant and form the points of an equilateral triangle. A triangular model, a rectangular model or any model suitable for the particular application is viable for some person skilled in the art having the benefits of this description. Depending on the external diameter of the ceramic tubes 60 of the ceramic heat exchanger 10 and the total length of the ceramic tube 60, which has a direct relationship with the outer diameter of the ball seal 70. The minimum center line for the distance of the center line between the adjacent tubes in the same tube sheet assembly may vary from two to three times the outer diameter of the ceramic tube. The design of the tube sheet assembly 51 described in this invention gives the designer of the ceramic heat exchanger 10 greater flexibility in the design of the tube sheet than some earlier ones. If the application of the heat exchanger requires a square pattern of centers of the ceramic tube 60 or some other model, then the internal metallic structure 52 can be modified and the spacing tubes 56 located adjacently. This in turn will locate the seal assembly 50 and consequently space the ceramic tubes 60. Therefore, an infinite number of models of the ceramic tube 60 can be formed in the two tube sheet assemblies 51 required in the ceramic heat exchanger 10. The same design flexibility is possible when the size of the ceramic tube 60 is selected. If the designer wants to mix sizes of ceramic tubes 60 into an individual ceramic heat exchanger 10, this is also possible. In this case, the spacer tubes 56 in the internal metal structure 56 can be manufactured in different sizes. Then by installing the appropriately sized seal assembly 50 in the respective locations on the two tube sheet assemblies 51, a mixture of two or more diameters of ceramic tubes 60 can be installed in a single ceramic heat exchanger 10. This design can be used where the ceramic tubes of larger diameter are used as a screen wall to protect the tube 60 from small ceramic particles of ash pegajoeae or extreme radiation from a direct flame shock. The assembly 51 of the tube sheet of the ceramic heat exchanger 10 may be constructed in any form to meet the requirements of the application. In Figure 2 and Figure 3 the assembly 51 of the rectangular tube sheet is shown. Other designs of the tube sheet assembly 51 that can use the structure taught in this invention are circular, triangular, rectangular or any polygon while the two tube sheet assemblies in the same ceramic heat exchanger are identical. As an example, the assembly 51 of the tube sheet designed to wrap the ceramic tubes around a heat source can result in the assembly 51 of the tube sheet having the "C" or "D" shape. The wide variety of for ae of the tube sheet is a key advantage of the ceramic heat exchanger 10 described in this patent application. Pipe sheets described in the prior art that are fabricated from refractory blocks or stacked ceramic tiles can not be constructed with different pipe sizes, spacing variable tube lengths or more exotic shapes. Figure 11 is a partial cross-section through the internal metallic structure 52 of the tube sheet assembly 51 showing the inner surface 67 of the hot side plate 54. The view also shows spacer tubes 56 at the end of two adjacent lines of ceramic tubes 60. Between the spacer tube 56 at the end of each line of the ceramic tube is a plate 86 attached to the plate 54 on the hot side. The spacing 87 between the plate 86 and the adjacent spacer tube 56 should be approximately equal to the distance between adjacent spacer tubes 56. The space 88 between the plate 86 and the seal plate 89 should also be approximately equal to the distance between the adjacent spacer tubes. The length of plate 86 should not exceed 1 to 1.5 times the diameter of the spacer tube and should be installed with a space (not shown) between adjacent plates 86 equal to the space between adjacent spacer tubes 56 if more than one spacer is required. plate 86 at the end of the tube line. The plate 86 is designed to direct the cooling fluid to the space between the tubes 56 of the adjacent spacer. If they are not installed, the cooling air must bypass the separator tubes and flow to the area 90 between the end of a line of the ceramic tube 60 and the seal plate 89. The arrows 80 show the desired direction of a cooling fluid flow within the internal metallic structure 52 of the tube sheet assembly 51. The hot side plate 54 extends beyond the seal plate 89 where a surface 126 is provided which will help to form a seal with the metal cover 11 of the ceramic heat exchanger 10. The cooling of the internal metallic structure 52 of the assembly 51 of the tube sheet is key to maintaining the structural integrity of the ceramic heat exchanger 10. The system 135 for detecting the internal temperature of the tube sheet can be installed on the inner metallic structure 52 to prevent overheating of the tube sheet assembly 51. The internal temperature sensing system 135 consists of one or more high temperature thermocouple 136 mounted to either the hot side plate 54 or the side plate 53 of the process side using a screw 137. The thermocouples 136 are connected to the instrumentation externally through the wire 138 of the thermocouple which passes outside the internal metallic structure 52 through a hole 108 in the seal plate 89. Figures 12, 13 and 14 show the special features of the upright system for the internal metal structure 52 of the tube sheet assembly 51 in the metal cover 11 of the ceramic heat exchanger 10. The internal metallic structure 52 must be completely sealed to prevent leaks between the hot gae side and the process gas side at all times, so it must be designed to accommodate the expansion of the 51 tube assembly without break the seal of the internal metallic structure 52 with the metallic cover 11. Figure 12 shows a section through the internal metallic structure 52 of the assembly 51 of the tube sheet. The view is observing the inner surface 66 of the process side plate 56. The tubes 56 separators and the plates 86 are shown in their respective locations in the internal metallic structure 52. The refractory jacket of the inlet conduit 22 of the process gas is shown in the dashed line.

As soon as the ceramic heat exchanger 10 is heated, the assemblies 51 of the tube sheet will expand perpendicular to the center line of the ceramic tubes 60 in a faster ratio and a greater amount than the metal cover 11. This expansion must be absorbed by the mounting element of the tube sheet. The expansion of the tube sheet 51 will be almost uniform due to the cooling provided to the internal metal structure 52. The assembly 51 of the tube sheet will also expand and contract based on the thermal expansion ratio of plate 53 on the process side and plate 54 on the hot side, which as set forth above will be maintained at approximately the same temperature . Since the assembly 51 of the tube sheet has a uniform expansion ratio, it can be designed with a single stitch point 141 attached to a fixed point on the metal cover 11 of the ceramic heat exchanger 10. All other stitches 142 in motion will have a radial displacement from the individual stitch point 141 as shown in FIG. 12. The stitch 141 individual stile may be located at any point on the edge of the inner metal structure 52; however, it must be at the same point in the two assemblies 51 of the tube sheet in a ceramic heat exchanger 10, and must have a radial freedom of movement for the internal metallic structure 52 from the individual stile-point 141 . Figure 14 shows the details of the mounting post 51 of the tube sheet where it is attached to the metal cover 11 of the ceramic heat exchanger 10. On the side of the hot gas of the internal metallic structure 52, there is a supporting framework consisting of a support angle 144, which is attached to the inner surface 146 of the metal cover 11, either by welding or by bolts ( not shown). Between the support angle 144 and the metal cover 11 is a ceramic fiber seal 148. Between the upper part and the lower part of the upright system of the tube sheet, there is a slot 149 which provides an opening for the cooling gas to exit or enter from the tube sheet assembly 51. At the top and bottom of the groove ee replaces the support angle 144 with a plate 145 which is welded to the metal cover 11. A ceramic fiber gasket 149 is installed between the support frame 143 and the internal metal structure 52. The internal metallic structure 52 is pushed against the support frame 143, but it is not attached to the support frame. On the side of the process gas of the internal metallic structure 52 is the outer support frame 151 consisting of a support angle 152 which is joined around the entire inner surface 146 of the metal cover 11 either by welding or by bolt- (not shown). Between the support angle 152 and the metal cover 11 is a ceramic fiber seal 148. The external support frame 151 has a set of radial grooves 156 designed to accept bolts (not shown) which are welded to the side plate 53 when proceeding. When the internal metallic structure is cooled during installation, the bolts (not shown) are located at the cooling end 157 of the groove and when the tube sheet assembly 51 expands during the operation, the bolts move up the slot 156 radial towards the hot end 158. Between the outer support frame 151 and the internal metallic structure is a ceramic fiber seal 154. The lateral support frame 143 to the hot gae and the frame 150 of external lateral support to the process gae form gas-tight seals on both sides of the internal metallic structure 52 in both the hot position 160 shown in the solid lines in Figure 13 or the cooling 161 poem shown in the elongated dotted lines in Figure 13. An additional seal is achieved when the internal metal structure 52 has achieved full expansion in the metal cover 11 and is pushed towards the ceramic fiber board 148 which is attached to the inner side of the metal cover 11. The refractory liner 12 inside the metal cover 11 on both sides of the tube sheet assembly 51 protects the system 140 from the sheet of the high temperature gas tube inside the ceramic heat exchanger 10. The ceramic heat exchanger 10 described here has solved the problems indicated by the prior art. The increased freedom of movement of ceramic tubes has eliminated the curvature pressure problems encountered with current designs. The seal assembly design 50 has eliminated the destruction of the seal of the tube by the expansion and contraction of the ceramic tubes 60 within the ball seal 70. The failure of the tube sheet has also been eliminated as indicated by excessive filtration through tile joints by the fabrication of tube sheet assembly 51 with an internal metallic structure 52 which is cooled to maintain structural integrity. This tube sheet assembly prevents any filtration between the hot gas and the process gas. With this innovacionee tecnicae, and novel ceramic materials, it is possible to achieve higher operating temperatures than the previous ones. The ceramic heat exchanger 10 described herein can operate at hot gas temperatures of 1600 ° C where the ceramic heat exchanger 10 changes to a dual heat transfer mode.

Current designs show heat exchangers where the mode of heat transfer is convective. In the case of the new design, the ability to operate successfully at high temperatures allows the ceramic heat exchanger 10 to transfer heat through both convective heat transfer and radiant heat transfer. At 1600 ° C the radiant components approach 25% of the total heat transferred from the hot gas to the process gas. The ceramic tubes 60 in the ceramic heat exchanger can be manufactured with elongated surfaces (not shown) in the future. The elongated surfaces may be external fins or highly textured surfaces on the ceramic tubes 60. On the inner surface of the ceramic tubes 60 the elongated surface may be an internal fin, a highly textured surface, or an ineertor pulled inside the tube which has a closed contact with the inner surface of the ceramic tube 60. The elongated surfaces improve the convective and radiant heat transfer of the ceramic heat exchanger 10. For purposes of this description, the design of the ceramic heat exchanger 10 shows the side of the hot gas to be the side of the cover while the process gas passes through the ceramic tubes 60. The ceramic heat exchanger 10 will also operate successfully with the process gas on the side of the cover while the hot gas passes through the ceramic tubes. The ceramic heat exchanger 10 is an important element in a high temperature heat recovery system 170 shown in Figure 15. The 170 high temperature heat recovery 170 is designed to improve energy efficiency and reduce the impact environmental of any oven 172 high temperature. High-temperature furnaces 172 are found in metal melting, glass, refining, chemical and waste incineration industries. Specific applications include remelting of steel, refinery heaters and black carbon furnaces. In all these systems a high temperature furnace 172 has an exhaust gas stream 174 which exits at a temperature in the range of 900 to 1500 ° C. The heat can be recovered from this stream of exhaust gas which can be re-routed to the process which will reduce the use of fuel. Downstream of the high temperature furnace 172, one or more ceramic heat exchangers 10 may be mounted in the hot gas stream 174. Ceramic heat exchangers 10 can be assembled in parallel or in series (as shown in Figure 15) or both. The gas stream 175 leaves the ceramic heat exchanger 10 at a temperature in the range of 250 to 550 ° C having some heat returned to the process gas and enters the environmental cleaning system 177, where the combustion products are cleaned of dangerous materials. The clean gae stream 178 is then vented to the chimney 179 of the system. The heat which is recovered from the exhaust gas stream 174 is transferred to the stream 181 of the process gas. The process gas fan 182 sends the process gas stream 181, which may be at temperatures in the ambient range to 450 ° C, to the process gas inlet 41 of the first ceramic heat exchanger 10. The process gas 181 absorbs approximately half of the available heat in the exhaust gas stream 174 (if two heat exchangers are used as the sample) and exits the ceramic heat exchanger 10 at the output 42 of the process gas. The partially heated process gas 183 continues to the process inlet 41 of the second heat exchanger 10 of ceramic where the gas 183 of the partially heated process absorbs the remaining heat from the exhaust gas stream 174. The gas 185 of the fully heated process leaves the ceramic heat exchanger 10 at the process gas outlet 42 in a temperature range between 500 to 1100 ° C, where this proceeds to the burners 186 mounted on the high temperature furnaces 172. The high temperature heat recovery system 170 can recover up to 50 percent of the total heat required by the high temperature furnace 172 using the ceramic heat exchanger 10 described in this invention. The 50 percent reduction in the composition of hazardous chemicals in the fluid gas stream reduces the environmental impact. In addition to the flow of the exhaust gas stream 174 and the process stream 181, the ceramic heat exchangers 10 require a refrigerant to be pumped through the internal metal structure 52 of each tube sheet assembly 51. . With reference to Figure 15 a cooling fan 188 or in the case of steam, a steam supply 189 provides cooling fluid through an inlet conduit 190 for each of the assemblies 51 of the tube sheet over the two exchangers 10 ceramic heat. On the inlet conduit 190 for each tube sheet assembly there is either a manual control valve 192 or a motorized control valve 193. The coolant fluid takes the excess heat from the assembly 51 of the tube sheet and exits the two ceramic heat exchangers 10 through the outlet conduit 195. If the refrigerant is air or the same as the process gas, then the outlet conduit 195 can vent the cooling fluid to the process gas stream 181 through the vent conduits 196. If the refrigerant is not compatible with the process gas, then the quench fluid may be vented from the outlet conduit 195 through the coolant vents 197. As described above, it is possible to install one or more thermocouples 136 in each of the internal metal structures 52 of the tube sheet assembly 51. The thermocouple signal 136 may be sent to a temperature indicator 201 which can give the operator an indication of the temperature of the internal metallic structure 52, to allow the operator to manually fix the control valves 192 to the correct position, such as so that the cooling fluid can maintain the appropriate temperature in the internal metallic structure 52. Along with the temperature indicator 201, there can also be a temperature switch 202 which can operate as an inter-racking process and stops the process if the temperature in the internal metallic structure 52 exceeds the safety limits. In a more sophisticated process or in a process where the valves for the tube sheet refrigerant are remote, a control panel may be installed. The thermocouple signal 136 can be sent to a temperature transmitter 203 and then to a temperature indicator controller 204. The operator can set the temperature to be maintained in the internal metal structure 52 and the temperature indicator controller 204 will send the appropriate signal to the motorized control valve 192 to maintain the appropriate temperature of the internal metallic structure 52. The description of the preferred embodiment described herein is not intended to limit the scope of the invention which is properly indicated in the claims.

Claims (32)

1. CLAIMS 1. A ceramic heat exchanger for a heat recovery system, characterized in that it comprises: a cover having a first tube sheet at a first end and a second tube sheet at a second extreme; at least one tube of the ceramic heat exchanger die between the first tube sheet and the second tube sheet, the ceramic heat exchanger tube mounted on the seal mounting means on each of the tube sheets; and each of the seal mounting means that allows both the expansion and contraction of the axial tube as well as an angular freedom of movement to prevent the development of a moment force on the ceramic heat exchanger tube.
2. 2. The ceramic heat exchanger according to claim 1, characterized in that the heat exchanger is capable of operating in the temperature range from about 900 ° C to about 1600 ° C, and wherein the heat transfer is achieved by a combination of convective media and radiant media.
3. 3. A ceramic heat exchanger for a heat recovery system, characterized in that it comprises: a cover having a first tube sheet at a first end and a second tube sheet at a second extreme; at least one tube of the ceramic heat exchanger disposed between the first sheet of the tube and the second sheet of the tube, the tube of the ceramic heat exchanger mounted in the seal assemblies on the sheets of the tube; and each of the eello assemblies comprises a ball seal mounted on the tube sheets, the ball seal to allow expansion and contraction of the tube without displacing the tube sheets, the ball seal having a centered radius of curvature from the center line of the ceramic exchanger tube in two planes which allows an angular freedom of movement for the tube of the ceramic heat exchanger.
4. 4. The ceramic heat exchanger according to claim 3, characterized in that the cover is a refractory coated cover having a plurality of tubes of the ceramic heat exchanger disposed between the first sheet of the tube and the second sheet of the tube.
5. 5. The ceramic heat exchanger according to claim 3, characterized in that the ball seal is mounted on each of the sheets of the tube by a first piece of tile and a second piece of tile, the first piece of tile which is a tile of the side of the tube and the second piece of tile that is a lateral tile to the proceeo, the first and second azulejoe united in a union that retains the ball eello and has a slightly higher radius in doe planoe than the radius of the ball seal .
6. 6. The ceramic heat exchanger according to claim 3, characterized in that the ball seal has a first radius and is mounted on each of the sheets of the tube by a first piece of tile and a second piece of tile, the first piece of tile that is a tile on the side of the pipe and the second piece of tile that is a side tile of the process; the first and second tile pieces joined in a joint, the joint having a curved surface, the curved surface having a second radius in the transverse plane which is greater than the first radius of the ball seal, and the curved surface which it has a third radius in the longitudinal plane which is greater than the first radius of the ball seal; and each radius formed in an offset to cause the longitudinal curve of the first and second piece of tile to approach the surface of the ball seal at each end of the curved surface of the joint.
7. The ceramic heat exchanger according to claim 5, characterized in that the joint having a curved surface is filled with ceramic fiber to form a seal and to act as a mode for the ball seal.
8. 8. The ceramic heat exchanger according to claim 3, characterized in that each of the sheets of the tube is comprised of parallel metallic wall panels having two sides, the two sides each having a refractory material arranged thereon, the parallel wall plates arranged between them. a metal pipe which is concentric to the center line of the ceramic heat exchanger tube.
9. 9. The ceramic heat exchanger according to claim 7, characterized in that each of the sheets of the tube is comprised of two parallel metal wall plates having two sides, each side having a surface thereon. refractory material, the parallel wall plates joined by a metal pipe, the concentric pipe to the center line of the ceramic heat exchanger tube; and the tile of the side of the tube and the tile of the side of the process that each have a flange which overlaps the refractory material disposed on both sides of the plates and parallel.
10. 10. The ceramic heat exchanger according to claim 9, characterized in that the pipe arranged between the parallel wall plates, form a cooling conduit whereby a cooling gas is pumped therethrough.
11. 11. The ceramic heat exchanger according to claim 9, characterized in that the location of the center line of the ceramic heat exchanger tube within the tubesheets forms a triangular model or a rectangular model.
12. 12. The ceramic heat exchanger according to claim 9, characterized in that the tubesheets can be circular, triangular, rectangular or polygonal in shape.
13. 13. The ceramic heat exchanger according to claim 9, characterized in that each of the sheets of the tube is comprised of parallel wall plates joined by the metal pipe, the pipe concentric to the center line of the heat exchanger pipe ceramic and plates disposed at the line end comprised of at least the ceramic heat exchanger tube, the plates separating to provide a flow of coolant between the parallel wall plates.
14. 14. The ceramic heat exchanger according to claim 9, characterized in that the parallel wall plate has at least one thermocouple means disposed in a cooling duct formed therebetween.
15. 15. The ceramic heat exchanger according to claim 9, characterized in that each of the sheets of the tube has a single fixed stile in the cover and at least one movable stile point to allow expansion in a radial direction from the fixed stile point.
16. 16. The ceramic heat exchanger according to claim 9, characterized in that each of the sheets of the tube has full seal contact with the cover during any deflection due to thermal expansion and contraction.
17. 17. A ceramic heat exchanger for a heat recovery system, characterized in that it comprises: a cover having a refractory liner, the cover having a first mounting of the tube sheet at a first end and a second mounting of the sheet of the tube at substantially an opposite end; each of the tube sheet assemblies comprising a plate of the hot side and a plate of the side of the process, the plate of the hot side and the plate of the side of the process which are substantially parallel to each other and which have between them a gap spacing means; at least one tube of the ceramic heat exchanger mounted between the first tube sheet assembly and the second tube sheet assembly, each tube of the ceramic heat exchanger having a center line, the tube spacing means gap between the parallel plates of the laminae of the tube that is concentric to the center line; and at least one ball eelloe holding at least one tube of the ceramic heat exchanger in the tube sheet assemblies, each ball seal having a radius of curvature centered from the centerline of each tube of the exchanger Ceramic heat in flat doe which allows an angular freedom of movement for the tube of the ceramic heat exchanger.
18. 18. The ceramic heat exchanger according to claim 17, characterized in that the cover has a hot gas inlet and a hot gas outlet between the tube sheet assemblies, each of the tube sheet assemblies comprised of parallel steel plates having a refractory material covering both sides, the gap spacing means disposed between the side plates for passing a cooling gas therethrough, and a process gas inlet and outlet chamber at each end outside the tube sheet assembly.
19. 19. The ceramic heat exchanger according to claim 17, characterized in that the cover has a process gas inlet and a process gas outlet between the laminae assemblies of the tube, each of the assemblies of the sheet of the tube comprised of parallel steel plates having a refractory material covering both sides, the gap spacing means disposed between the parallel plates to pass a cooling gas therethrough, and a hot gas inlet and an outlet chamber of hot gas on each external side to each assembly of the tube sheet.
20. 20. The method for using the ceramic heat exchanger according to claim 18, characterized in that the cooling gas can be ambient air, or steam at about 100 to about 150 ° C.
21. 21. The ceramic heat exchanger according to claim 18, characterized in that the ball seal is clamped in each tube sheet assembly between a hot surface tile and a cold surface tile, and a refractory material is molded on the surface of the hot surface tile and the cold surface tile.
22. 22. The ceramic heat exchanger according to claim 21, characterized in that the ratio of the thickness of the refractory material molded onto the surface of the hot surface tile for the thickness of the molded refractory material on the surface of the cold surface tile is adjusted to the same ratio as well as the temperature of the hot side and the temperature of the cold side over the cold temperature of the tube sheet assembly.
23. 23. The ceramic heat exchanger according to claim 21, characterized in that the cold surface tile has a hexagonal shaped opening on the centerline to allow an adapter tool means to engage threads on the cold surface tile in the threads on the hot surface tile.
24. 24. The ceramic heat exchanger according to claim 21, characterized in that the outer diameter of the tube of the ceramic heat exchanger is increased to a diameter which allows a sliding fit with the internal diameter of the ball seal.
25. 25. The ceramic heat exchanger according to claim 21, characterized in that each of the tubes of the ceramic heat exchanger is independently removable.
26. 26. The ceramic heat exchanger according to claim 21, characterized in that each of the tubes of the ceramic heat exchanger can be blocked in the event of failure of the pipes of the ceramic heat exchanger.
27. 27. The ceramic heat exchanger according to claim 21, characterized in that the assemblies of the tube sheet can accommodate two or more tube sizes of the ceramic heat exchanger.
28. 28. The ceramic heat exchanger according to claim 21, characterized in that the assemblies of the tube sheet can accommodate the tubes of the heat exchanger having the spacing of the center line between the adjacent tubes of two to three times the external diameter of an exchanger tube.
29. 29. A high temperature heat recovery system, characterized in that it comprises: a high temperature furnace in which the exhaust gas is between approximately 900 and 1,500 ° C; a high temperature ceramic heat exchanger medium having ceramic tube and tube sheets, which transfers the heat from a hot gae to a gae stream of the process; a means of environmental cleaning of hot gae; a chimney means for venting the exhaust gas to the atmosphere; a means of pumping process gas to pass the process gas through the medium of the high temperature ceramic heat exchanger where the heat is recovered from the hot gas; a combustor means for mixing the preheated process gas with fuel on its introduction to the high temperature furnace; and a means for providing cooling gas to the tube sheets in the middle of the high temperature ceramic heat exchanger.
30. 30. The high temperature heat recovery system according to claim 29, characterized in that the high temperature ceramic heat exchanger means comprises two or more heat exchangers in series.
31. 31. The high temperature heat recovery seventh according to claim 29, characterized in that the high temperature ceramic heat exchanger means comprises doe or more heat exchangers in parallel.
32. 32. The high temperature heat recovery seventh according to claim 29, characterized in that the high temperature ceramic heat exchanger means comprises two or more heat exchangers in a combination in series and parallel arrangements.