EP4577791A1 - Transfer line exchanger with inlet cone with improved erosion resistance - Google Patents

Abstract

A transfer line exchanger with an inlet cone with improved erosion resistance, a process for cracking hydrocarbons utilizing the transfer line exchanger and an apparatus for cracking hydrocarbons comprising the transfer line exchanger are disclosed.

Description

Basell Polyolefine GmbH FR012/22 FR7448 TRANSFER LINE EXCHANGER WITH INLET CONE WITH IMPROVED EROSION RESISTANCE FIELD OF THE DISCLOSURE [0001] The present disclosure refers to a transfer line exchanger with an inlet cone, a process for cracking hydrocarbons utilizing the transfer line exchanger and an apparatus for cracking hydrocarbons comprising the transfer line exchanger. BACKGROUND [0002] The cracking of hydrocarbons is a well-established process for the production of ethylene and propylene which are both important building blocks for other chemicals, in particular plastics. [0003] Cracking describes the process of breaking long chains of hydrocarbons down into smaller, often unsaturated, hydrocarbons. In order to gain the desired hydrocarbons, a feedstock of more complex hydrocarbons such as ethane and naphtha is fed into a cracking furnace, in particular into a so-called cracking coils arranged inside the cracking furnace and quickly brought up to a cracking temperature of around 800 to 900 °C with heat supplied from the outside of the coils. As a result of the thermal cracking of the hydrocarbons, carbon deposition occurs on the inside of the coils. This so-called coking leads to an increase pressure drop in the coils and lowers the heat transfer efficiency, eventually causing a reduction in the operation efficiency of the thermal cracking furnace. Due to the decreased heat transfer efficiency, the temperature on the outside of the coils has to be constantly increased in order to achieve the required cracking temperatures on the inside. However, increasing the temperature is only possible up to a maximum temperature which is usually determined by the material of the coils taking into account a certain safety margin. Ultimately, the coke deposition inside the coils has to be removed, referred to as decoking, resulting in an interruption of the whole process. Once a maximum temperature has been reached, decoking must be carried out. However, during the decoking process coke deposits flow with high velocity through the transfer line exchanger and caused significant erosion issues. [0004] The gas enters the transfer line exchanger at high velocities and temperatures. In order to protect the transfer line exchanger from overheating, the transfer line exchanger is usually equipped with an inlet cone lined with refractory. However, the cracked gas usually also contains small solid particles, such as coke particles, which causes severe erosion of the refractory lining. [0005] KR 101418137 discloses a heat-resistant cone of a heat exchanger which has an inner lining, an outer wall portion formed to surround the inner cylinder at a distance from the outer circumferential surface of the inner cylinder and a refractory material filled in the space between the inner cylinder and outer wall portion. [0006] US 4,161,192 relates to an inlet cone for passing gases from the outlet side of a hydrocarbon cracking heater to the tube inside of a heat exchanger, said inlet cone comprising: a generally conical 29.11.2022 metal wall connectable around the periphery of its larger end to said heat exchanger and connectable around the periphery of its smaller end to said cracking heater, said generally conical wall having an aperture between its said larger end and its said smaller end; a pressure resistant exterior wall of metal, said pressure resistant exterior wall being spaced from said generally conical wall and having its ends connected to said generally conical wall at points above and below, respectively said smaller end and said larger end of said generally conical wall; and a castable refractory fill, said refractory fill occupying the gap between said pressure resistant exterior wall and said generally conical wall and extending inwardly to form a filled aperture, said refractory fill in said filled aperture being approximately flush with the interior of said generally conical wall. [0007] US 2021/0190435 describes a heat exchanger for use with a hot fluid stream leaving a high temperature process comprising a hot section and cold section which have no common or adjoining external surfaces wherein one or more heat pipes extend from the interior of the hot section, traverse the open space between the hot section and the cold section at an angle of inclination from 10° to 90° and extend into the cold section. [0008] US 6,464,949 B1 relates to a steam-cracking unit that comprises at least one multitube quenching exchanger, equipped with a non-obstructive impact separator for preventing the erosion of the tubular input plate. The impact separator is at least 50% opaque when viewed from transfer pipe. It is arranged inside of an input cone in such a way that there is free passage of at least 40 mm between the periphery of the impact separator and the cone. [0009] US 2021/0123683 A1 discloses a heat exchanger including: an inlet portion having a first flow path through which a fluid is introduced; a main body including a shell and a plurality of tubes. The shell has an internal space and one surface that has a plurality of penetration holes and a cross-sectional area larger than a cross-sectional area of the first flow path. Each of the plurality of tubes allows the fluid to flow therethrough, and is positioned in the internal space of the shell. An expanded tube portion connects the inlet portion and the one surface of the shell and has a second flow path. The heat exchanger also includes a fluid flow distributor disposed in the second flow path to distribute the flow of the fluid. No other member is disposed between the inlet portion and the multiple ring members. [0010] GB 1,190,958 discusses an inlet device for connecting the output of a cracking heater with the inlet of a transfer line heat exchanger. The inlet device includes a tubular first portion of circular cross- section, a curved second portion flaring outwardly from the first portion in a smooth curve, a frusto- conical third portion extending outwardly from the second portion and a ring shaped fourth portion extending from the periphery of the third portion, the distance (h) from the point of intersection of the second portion and the third portion to the outlet end of the fourth portion being about 0.03 to 0.2 times the minimum diameter of the first portion and the distance from the periphery of the third portion to the outlet end of the fourth portion being about 0.25 to 0.5 times (h). [0011] In currently available transfer line exchangers, the inlet cones are filled with refractory for thermal protection. However, the refractory cannot effectively withstand the erosive attack of the coke particles in the gas stream and becomes brittle and breaks, generating solid fractions which can badly damage the equipment. Further, a damaged refractory causes a change in the gas distribution which may lead to plugging of the equipment. In addition, different expansion behavior of the cone material and the refractory lining leads to the refractory lining pushing the inlet cone away from the flange of the shell and tube exchanger, which in turn may result in gas leakage with the danger of immediate ignition of the outflowing gas. Therefore, refractory linings need to be completely refurbished or replaced at regular intervals causing high maintenance costs and production losses. [0012] There is therefore still the need for transfer line exchangers which overcome the drawbacks of the prior art and which show reduced wear and prolonged lifetime. SUMMARY OF THE DISCLOSURE [0013] The present disclosure provides a transfer line exchanger comprising: a) a shell and tube heat exchanger, and b) an inlet cone configured to pass gases from a cracking furnace to the shell and tube heat exchanger, wherein the inlet cone has a conically shaped wall extending in an axial direction from an inlet side to an outlet side and surrounding a gas flow passageway, the inlet cone being fixed to the shell and tube heat exchanger at the outlet side, and a baffle plate arranged in the gas flow passageway between the inlet side and outlet side, wherein the conically shaped wall comprises a radially inwards facing inner surface formed from a heat resistant metallic material, wherein the inner surface is exposed to the gas flow passageway, and wherein the baffle plate is fixed to said conically shaped wall via fixing means. [0014] In some embodiments, the heat resistant metallic material is selected from the group consisting of high temperature heat resistant cast stainless steel, solid cast iron and chromium, nickel and/or aluminum doped material. [0015] In some embodiments, the high temperature heat resistant cast may be doped with at least one of chromium, nickel and aluminum. The high temperature heat resistant cast may for example be doped with chromium and nickel or even with chromium, nickel and aluminum. In some embodiments, the inlet cone does not comprise a refractory lining, in particular concrete. [0016] In some embodiments, at least part of the inner surface further comprises an erosion protection coating. [0017] In some embodiments, the conically shaped wall is solid between the inner surface and the radially outwards facing outer surface. [0018] In some embodiments, the conically shaped wall comprises a hollow volume formed between the inner surface and an outer surface. [0019] In some embodiments, the hollow volume is filled with a filling material having a lower thermal conductivity than the inner surface and/or outer surface. [0020] In some embodiments, the filling material is at least one of air, ceramic fiber or mineral wool. [0021] In some embodiments, the inlet cone further comprises at least one stabilizing bar formed at the outlet side and being arranged between a front face of the conically shaped wall and the shell and tube heat exchanger. [0022] In some embodiments, the at least one stabilizing bar is welded to the front face of the conically shaped wall. [0023] In some embodiments, a gasket is provided between the shell and tube heat exchanger and the inlet cone, wherein the gasket comprises a vermiculite sealing face bonded to a serrated metal core or a spiral wounded gasket. The gasket may preferably be a comb profile gasket. [0024] In some embodiments, a further gasket is provided between the inlet cone and a flange of a furnace and/or coil outlet, wherein the gasket comprises a vermiculite sealing face bonded to a serrated metal core or a spiral wounded gasket. [0025] In some embodiments, the conically shaped wall comprises at least one erosion protection rib projecting radially inwards into the gas flow passageway, the at least one erosion protection rib covering at least one fixing means in a top view from the inlet side. [0026] In some embodiments, the baffle plate is axially supported by the at least one erosion protection rib. [0027] In some embodiments, the tubes of the shell and tube heat exchanger are formed from a first material and the conically shaped wall of the inlet cone is formed of a second material, the first material having a lower heat resistance than the second material. [0028] In another aspect, the present disclosure relates to a process for cracking hydrocarbons, in particular a process for the production of olefins, wherein the cracked gas is passed through a transfer line exchanger of the present disclosure. [0029] In another aspect, the present disclosure relates to an apparatus for cracking hydrocarbons, in particular for the production of olefins, the apparatus comprising a cracking furnace and a transfer line exchanger of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS [0030] Figure 1 shows a transfer line exchanger of the present disclosure. [0031] Figures 2a, 2b and 2c show different embodiments of the present disclosure wherein the baffle plate is attached to the conically shaped wall by alternative fixing means. [0032] Figure 3 shows an embodiment of the inlet cone of the transfer line exchanger of the present disclosure with the conically shaped wall comprising a hollow volume as well as an enlarged view of the gasket arranged between the inlet cone and the shell and tube heat exchanger. DETAILED DESCRIPTION OF THE DISCLOSURE [0033] It has been found that by using a transfer line exchanger with a specifically designed inlet cone made of a heat resistant metallic material, the lifetime of the transfer line exchanger could be improved. Transfer line exchangers operate under high temperatures and throughput. Therefore, any leaks in the system present an enormous safety hazard as gas escaping the system is prone to spontaneous ignition. It has further been found that the problem of leakage could be greatly reduced by the transfer line exchanger of the present disclosure. In that regard, the present disclosure describes a transfer line exchanger comprising: a) a shell and tube heat exchanger, and b) an inlet cone configured to pass gases from a cracking furnace to the shell and tube heat exchanger, wherein the inlet cone has a conically shaped wall extending in an axial direction from an inlet side to an outlet side and surrounding a gas flow passageway, the inlet cone being fixed to the shell and tube heat exchanger at the outlet side, and a baffle plate arranged in the gas flow passageway between the inlet side and outlet side, wherein the conically shaped wall comprises a radially inwards facing inner surface formed from a heat resistant metallic material, wherein the inner surface is exposed to the gas flow passageway, and wherein the baffle plate is fixed to said conically shaped wall via fixing means. The baffle plate may in particular be an erosion shield. The conically shaped wall further comprises at least one erosion protection rib projecting radially inwards into the gas flow passageway, the at least one erosion protection rib covering at least one fixing means in a top view from the inlet side. [0034] As used herein, “fixing means” are mechanical components that are configured to secure the baffle plate too the remainder of the inlet cone. The fixing means may encompass complementary components that engage in at least one of a form fit, force fit or an adhesive bond. The fixing means may for example be a bolt that connects the baffle plate to the remainder of the inlet cone, in particularly the conically shaped wall. The baffle plate may comprise a complementary formed opening or groove in which the bolt can be fittingly received. Alternatively, the conically shaped wall may comprise a protrusion protruding radially towards the baffle plate into a corresponding opening. [0035] The transfer line exchanger according to the present disclosure is located downstream of a cracking furnace and designed to receive the high-temperature gas stream expelled from the cracking furnace. The high-temperature gas stream is received by the transfer line exchanger via the inlet cone and passes through the gas flow passageway from the inlet side of the inlet cone to its outlet side which is connected to the shell and tube heat exchanger. The high-temperature gas cools down during its passage through the shell and tube heat exchanger and is further conveyed. [0036] As used herein, a “heat resistant metallic material” encompasses metallic materials, which have a solidus temperature of from 900°C to 1500°C, particularly from 1000°C to 1400°C, a specific heat capacity of 400 to 550 J/(kg K). The heat resistant metallic material may comprise a thermal conductivity of 5 to 50 W/(m K), particularly from 10 to 25 W/(m K) measured at 20°C. In some embodiments, the heat resistant metallic material may comprise a 0.2% yield strength of from 150 to 600 MPa, preferably 150 to 550 MPa, more preferably from 150 to 500 MPa measured at 20°C. The 0.2% yield strength at between 800 to 900°C may range from 70 to 400 MPa, preferably from 90 to 350 MPa, more preferably from 120 to 330 MPa. In some embodiments, the heat resistant metallic material may comprise a Vickers hardness measured at 20° of at least 100 HV up to about 1000 HV. Preferably, the Vickers hardness may range from 120 HV up to about 250 HV. about 950 HV. The Vickers hardness may be measured in accordance with DIN ISO 6507. It has been found that such heat resistant metallic materials prevent the formation of coke and fouling compared to conventional materials. [0037] In commonly used transfer line exchangers, the inlet cone is usually made of metal and comprises a refractory lining, e.g. a lining of concrete for erosion protection. However, the refractory lining becomes brittle and breaks under the constant impact of e.g. coke particles contained in the high- temperature gas stream. the cone. In the worst-case scenario, solid fragments are generated which can lead to severe damage of pipes and the connected shell and tube heat exchanger. Furthermore, due to erosion and breaking of the refractory hot-spots may be formed on the outside of the cone. Thus, such inlet cones have to be provided with a touch protection. It has been found that these drawbacks can be overcome by forming the inner surface of the inlet cone of a high-temperature resistant metallic material instead of refractory lining. In some embodiments of the present disclosure, the heat resistant metallic material is selected from the group consisting of high temperature heat resistant cast stainless steel, solid cast iron and aluminum doped material. The solid cast iron may for example be chromium, nickel and aluminum doped. In some embodiments, the inlet cone does not comprise a refractory lining, in particular concrete. The heat resistant metallic material may be the same material of the coils used in the cracking furnaces. In particular, the radially inner surface may be formed by a chromium nickel alloy. [0038] In order to further improve the erosion resistance, the inner surface of the inlet cone may additionally be at least partially coated with an erosion protection coating. Therefore, in some embodiments, at least part of the inner surface further comprises an erosion protection coating. It should be noted that as used herein, the term “the inner surface is exposed to the gas flow passageway” includes embodiments, in which the inner surface is provided with a coating of up to 1 mm. In some embodiments, the coating has a thickness of 0.1 to 0.5 mm, more preferably 0.15 to 0.3 mm. In some embodiments, the erosion protection coating may increase the Vickers hardness measured at 20°C up to about 950 HV. [0039] The erosion protection coating may be a thermal coating obtained from a spray coating material formed of Cr₃C₂ and a NiCr alloy. The spray coating material may comprise at least 50 wt.-%, at least 60 wt.-%, preferably at least 70 wt.-% of Cr₃C₂, based on the total weight of the spray coating material. The spray material may in one embodiment comprise about 75 wt.-% of Cr₃C₂. In some embodiments, the spray coating material may comprise up to 95 wt.-%, up to 90 wt.-%, preferably up to 80 wt.-% of Cr₃C₂. [0040] In some embodiments, the content of Ni in the spray coating material may be around 15 to 25 wt.-%, preferably, the content of Ni in the spray coating material may be about 20 wt.-%. Additionally, or alternatively, the content of C in the spray coating material may be less than 15 wt.-%. In some embodiments, the C content in the spray coating material may be 10 wt.-%. [0041] In order to assist in the stability of the inlet cone, in some embodiments, the conically shaped wall is solid between the inner surface and the radially outwards facing outer surface. [0042] In other embodiments, the conically shaped wall comprises a hollow volume formed between the inner surface and an outer surface. The hollow volume may be filled with a filling material having a lower thermal conductivity than the inner surface and/or outer surface. In some embodiments, the filling material is at least one of air, ceramic fiber or mineral wool. It was found that the hollow volume for one serves as thermal insulation and secondly, the hollow volume leads to a reduction of weight while retaining the material in the outer area and at the cone outlet flange of the transfer line exchanger. [0043] The inlet cone is exposed to high-temperature gas, so the temperature on the inside of the inlet cone is much higher than the one outside of the inlet cone, which puts additional strain on the inlet cone itself, but also on the baffle plate and respective fixing means. In order to provide further support and stabilization, in some embodiments, the inlet cone further comprises at least one stabilizing bar formed at the outlet side and being arranged between a front face of the conically shaped wall and the shell and tube heat exchanger. In some embodiments, the at least one stabilizing bar is welded to the front face of the conically shaped wall. [0044] Usually a flange is used to secure the inlet cone to the flange of the shell and tube heat exchanger. However, that flange connection, in particular the sealing between the flanges is known to fail in case a refractory lining is provided. This may be caused by the growth of the refractory at higher temperatures and/or due to tiny coke particles penetrating between the inlet cone and the main body of the shell and tube heat exchanger which causes the refractory lining to "float up" and push against the flange. A loose flange, however, causes gas leakage. It was found that by changing the commonly used inlet cone to an inlet cone according to the disclosure with a flange made of a high-temperature application material, the risk of gas leakage could be significantly reduced. In case, the inlet cone is formed as a solid component, i.e. without a hollow volume between the radial inside facing wall and the radial outside facing wall of the inlet cone, it is preferred that the flange of the inlet cone is formed of a high-alloy material, in particular a high-alloy material on a chromium and nickel basis. [0045] Accordingly, in some embodiments, a comb profile gasket is provided between the shell and tube heat exchanger and the inlet cone, wherein the gasket comprises a vermiculite sealing face bonded to a serrated metal core or a spiral wounded gasket. In particular, the gasket may be compressed between the flange of the shell and tube heat exchanger and the flange of the inlet cone. The gasket may be arranged in the flange joint via a main load connection (German: Krafthauptschluss) or an off load connection (German: Kraftnebenschluss). In a main load connection, the gasket floats between the flange plates such that a direct contact between the flange plates is prevented. The force acts directly on the gasket, allowing a targeted application of the surface pressure. An off load connection refers to a flanged joint, in which the gasket is located in a recess within the joint so that it is compressed until the flange plates are in direct contact with each other. The flanged joint may be secured by bolts. Thus, the gasket may be compressed by bolt loads. [0046] In some embodiments, a further gasket may be provided between a lower flange of the inlet cone and a flange of a furnace and/or coil outlet. The gasket may be a comb profile gasket comprising a vermiculite sealing face bonded to a serrated metal core or a spiral wounded gasket. Usually the lower flange of an inlet cone and/or the flange of a furnace and/or coil outlet are formed as ring type joint flanges. Ring type joint flanges are formed as metallic plates having a deep groove cut into its face. Metallic ring type joint gaskets sit in the groove to seal the flange pair. When the connecting bolts of the flanges are tightened, the gasket is compressed and the flange pair creates a leak-proof tight seal. However, often such gasket material is harder than the material of the flange. Thus, permanent plastic deformation of the flange plates potentially causing leaks. The threat of leaks due to plastic deformation may be resolved by replacing the common ring type joint gasket with the comb profile gasket or a spiral wounded gasket with vermiculite as described herein. [0047] In order to shield the tubes of the tube and shell heat exchanger from heavy impact with solid particles contained in the high-temperature gas stream, the inlet cone is equipped with a baffle plate arranged in the gas flow passageway between the inlet side and the outlet side of the inlet cone. The baffle plate is intended to slow down the solid content of the high-temperature gas stream, thereby minimizing the erosion caused by said high-velocity particles hitting the tube sheets and tubes of the shell and tube heat exchanger. In an exemplary embodiment of the present disclosure, the baffle plate is made of a solid base on which a number of concentric rings with increasing diameter are stacked spaced apart from each other. The base plate and the rings may be made of a high-temperature resistant metallic material. The baffle plate is fixed to the conically shaped wall of the inlet cone via fixing means. For example, anchor bolts may be provided, which are either screwed or welded to the conically shaped wall. In some embodiments, the fixing means, e.g. bolts, may be arranged in a radial pattern extending from the conically shaped wall of the inlet cone to the baffle plate. The number of fixing means may be chosen according to need. However, in an exemplary embodiment, the baffle plate is attached to the conically shaped wall by at least two, preferably 3 or more fixing means. [0048] Due to their exposed position in the gas flow passageway of the inlet cone, the fixing means for fixing the baffle plate to the conically shaped wall are also affected by the impact with high-velocity solid particles present in the gas stream entering the inlet cone. Accordingly, the fixing means are also endangered by erosion which might result in loosening or even detachment of the baffle plate. In order to protect the fixing means, for example bolts, the conically shaped wall of the inlet cone comprises at least one erosion protection rib projecting radially inwards into the gas flow passageway and arranged to cover at least one fixing means. In particular, each fixing means may be covered by an erosion protection rib. Preferably, a separate erosion protection rib is provided for each fixing means. The at least one erosion protection rib may in one embodiment be arranged below and in support of the fixing means in the direction of flow of the high-temperature gas entering the inlet cone. In an exemplary embodiment of the present disclosure, the at least one erosion protection rib is welded to the conically shaped wall of the inlet cone. In an alternatively exemplary embodiment, the at least one erosion protection rib forms an integral part of the conically shaped wall of the inlet cone. [0049] The at least one erosion protection rib may be connected to the fixing means by way of welding or with the help of screws. In an alternative embodiment, the at least one erosion protection rib and the respective fixing means are an integrally formed part attached to the baffle plate by way of tongue and groove. In these embodiments, the integral part comprises an extension part which is configured to fit into a corresponding groove of the baffle plate. [0050] In some embodiments, the baffle plate is axially supported by the at least one erosion protection rib. [0051] The inlet cone is fixed to the shell and tube heat exchanger. In particular, the flange at the outlet side of the inlet cone may be fixed to a corresponding flange of the shell and tube heat exchanger. To account for the differences in temperatures of the gas entering the inlet cone and passing on to the tubes of the heat exchanger, in some embodiments, the tubes of the shell and tube heat exchanger are formed from a first material and the conically shaped wall of the inlet cone is formed of a second material, the first material having a lower heat resistance than the second material. This allows for adaptation of the materials in view of their thermal capacity. [0052] The transfer line heat exchanger of the present disclosure is intended to be employed in cracking processes. Therefore, in another aspect, the present disclosure relates to a process for cracking hydrocarbons, in particular a process for the production of olefins, wherein the cracked gas is passed through a transfer line exchanger of the present disclosure. It was found that the transfer line heat exchanger of the present disclosure enables uniform gas flow in the tubes. The risk of tubes clogging due to fouling is minimized. [0053] In another aspect, the present disclosure relates to an apparatus for cracking hydrocarbons, in particular for the production of olefins, the apparatus comprising a cracking furnace and a transfer line exchanger of the present disclosure. The transfer line exchanger is connected to the cracking furnace via its inlet cone. After entering the inlet cone coming from the cracking furnace, the high- temperature gas stream passes through the tubes of the shell and tube heat exchanger before being further processed. [0054] The present disclosure will be explained in more detail with respect to the following drawings, which by no means are to be understood as limiting the scope or spirit of the disclosure. NON-LIMITING EMBODIMENTS [0055] Figure 1 shows a transfer line exchanger 1 of the present disclosure comprising an inlet cone 2 having an inlet side 2a and outlet side 2b. The outlet side 2b is fixed to a shell and tube heat exchanger 3. The inlet cone 2 is equipped with a conically shaped wall 4 extending in an axial direction from the inlet side 2a to the outlet side 2b of the inlet cone 2. A baffle plate 5 is arranged in the gas flow passageway formed by the conically shaped wall 4. High-temperature gas from a cracker furnace enters the inlet cone 2 at the inlet side 2a, passes through the gas flow passage formed by the conically shaped wall 4 and enters the shell and tube heat exchanger 3. [0056] Figure 2 shows different embodiments of the inlet cone 2 attached to the shell and tube heat exchanger 3 (not fully shown). [0057] With reference to Figure 2a an embodiment of the present disclosure is described wherein the baffle plate 5 is attached to the conically shaped wall 4 of the inlet cone 2 by fixing means, in particular a bolt 6a, which bolt projects radially from the baffle plate and is screwed into the conical shaped wall. The fixing means may covered by an erosion protection rip 7a which may be welded to the conically shaped wall 4. Alternatively, the bolt may be fixed to the erosion protection rip, e.g. by screwing or even by welding. The erosion protection rip 7a may, in an alternative embodiment, be monolithically formed with the conical shaped wall as a unitary component. [0058] With reference to Figure 2b an embodiment of the present disclosure is described wherein the baffle plate 5 is attached to the conically shaped wall 4 of the inlet cone 2 and by fixing means in the form of a plate 6b fittingly received in a radial opening of the baffle plate 5 and radially projecting out of the opening. The plate 6b is covered by an erosion protection rib 7b which is fixed to the plate 6b by way of screw 8. [0059] With reference to Figure 2c an embodiment of the present disclosure is described wherein the baffle plate 5 is attached to the conically shaped wall 4 of the inlet cone 2 and by fixing means formed integrally together with the erosion protection rib 9. The erosion protection rib 9 comprises an extension part 9a, which is configured to fit into a corresponding groove of the baffle plate 5. [0060] Figure 3 refers to an embodiment of the transfer line exchanger 1 of the present disclosure wherein the inlet cone 2 comprises a hollow volume 10. The hollow volume may be filled with a filling material having a lower thermal conductivity than the inner surface and/or outer surface. In some embodiments, the filling material is at least one of air, ceramic fiber or mineral wool. Also shown is a comb profile gasket 11 which connects the inlet cone 2 to the shell and tube heat exchanger 3 and runs around the perimeter of the inlet cone 2, as shown in the enlarged view. The comb profile gasket 11 is arranged in a main load connection meaning that the gasket floats between the flange plates such that a direct contact between the flange plates is prevented and a gap extends between the flange plates adjacent to the gasket 11. The force acts directly on the gasket, allowing a targeted application of the surface pressure. [0061] In a not shown alternative embodiment, the gasket may be arranged in an off load connection, in which the gasket is received in a recess and compressed until the flange plates are in direct contact with each other. [0062] The force for compressing the gasket and securing the flanges to one another may be applied by connection bolts arranged radially further outside than the gasket. The bolt connections are indicated in the figures with the evenly dashed lines. Multiple bolt connections may be circumferentially distributed on the flanges such that an even compression force is applied and leakage is prevented. [0063] Correspondingly, a further comb profile gasket as described above may be provided for the flange arranged at the inlet side 2a. Said comb profile gasket may seal the flange connection between the flange of the inlet cone 2 at the inlet side 2a and a flange of a furnace and/or coil outlet (not shown).

Claims

CLAIMS 1. A transfer line exchanger (1) comprising: a) a shell and tube heat exchanger (3), and b) an inlet cone (2) configured to pass gases from a cracking furnace to the shell and tube heat exchanger, wherein the inlet cone (2) has a i) conically shaped wall (4) extending in an axial direction from an inlet side (2a) to an outlet side (2b) and surrounding a gas flow passageway, the inlet cone (2) being fixed to the shell and tube heat exchanger (3) at the outlet side (2b), and ii) a baffle plate (5) arranged in the gas flow passageway between the inlet side (2a) and outlet side (2b), wherein the conically shaped wall (4) comprises a radially inwards facing inner surface formed from a heat resistant metallic material, wherein the inner surface is exposed to the gas flow passageway, and in that the baffle plate (5) is fixed to said conically shaped wall (4) via fixing means (6, 9), characterized in that conically shaped wall (4) comprises at least one erosion protection rib (7) projecting radially inwards into the gas flow passageway, the at least one erosion protection rib (7) covering at least one fixing means (6) in a top view from the inlet side (2a).

2. The transfer line exchanger (1) of claim 1, characterized in that at least the inner surface is formed from a high temperature heat resistant material selected from the group consisting of solid cast iron and aluminum doped material.

3. The transfer line exchanger (1) of any one of claims 1 or 2, characterized in that the inlet cone (2) does not comprise a refractory lining.

4. The transfer line exchanger (1) of any one of claims 1 to 3, characterized in that the inner surface further comprises an erosion protection coating.

5. The transfer line exchanger (1) of any one of claims 1 to 4, characterized in that the conically shaped wall (4) is solid between the inner surface and a radially outwards facing outer surface.

6. The transfer line exchanger (1) of any one of claims 1 to 5, characterized in that the conically shaped wall (4) comprises a hollow volume (10) formed between the inner surface and an outer surface.

7. The transfer line exchanger (1) of claim 6, characterized in that the hollow volume (11) is filled with a filling material having a lower thermal conductivity than the inner surface and/or outer surface.

8. The transfer line exchanger (1) of one any one of claims 6 or 7, characterized in that the filling material is at least one of air, ceramic fiber or mineral wool.

9. The transfer line exchanger (1) of any one of claims 1 to 8, characterized in that the inlet cone (4) further comprises at least one stabilizing bar formed at the outlet side (2b) and being arranged between a front face of the conically shaped wall (4) and the shell and tube heat exchanger (3).

10. The transfer line exchanger (1) of any one of claims 1 to 9, characterized in that a comb profile gasket (11) is provided between the shell and tube heat exchanger (3) and the inlet cone (2), wherein the gasket (11) comprises a vermiculite sealing face bonded to a serrated metal core or a spiral wounded gasket.

11. The transfer line exchanger (1) of any one of claims 1 to 10, characterized in that the heat resistant metallic material comprises a Vickers hardness measured at 20°C of at least 100 HV up to 1000 HV measured in accordance with DIN ISO 6507.

12. The transfer line exchanger (1) of claim 11, characterized in that the baffle plate (5) is axially supported by the at least one erosion protection rib (7).

13. The transfer line exchanger (1) according to any one of claims 1 to 12, characterized in that tubes of the shell and tube heat exchanger (3) are formed from a first material and the conically shaped wall (4) of the inlet cone (2) is formed of a second material, the first material having a lower heat resistance than the second material.

14. A process for cracking hydrocarbons, in particular a process for the production of olefins, wherein the cracked gas is passed through a transfer line exchanger of any one of claims 1 to 13.

15. An apparatus for cracking hydrocarbons, in particular for the production of olefins, the apparatus comprising a cracking furnace and a transfer line exchanger of any one of claims 1 to 13.