WO2025217718A1

WO2025217718A1 - High temperature fluidized bed reactor

Info

Publication number: WO2025217718A1
Application number: PCT/CA2025/050468
Authority: WO
Inventors: Tuisko Moritz BUCHHOLZ; Alex KOKOURINE
Original assignee: Hatch Ltd
Current assignee: Hatch Ltd
Priority date: 2024-04-15
Filing date: 2025-04-02
Publication date: 2025-10-23
Anticipated expiration: 2026-10-15

Abstract

A fluidized bed reactor and a process for operating a fluidized bed reactor. The reactor comprises a windbox, reaction chamber, gas distribution plate, and an isolation plate. The gas distribution plate and isolation plate define an enclosed space filled with a fluid. The reactor also comprises a cooling line disposed within the space a distance from the gas distribution plate to cool the fluid within the space. The process comprises supplying hot fluid from the windbox to the gas distribution plate via tuyeres, providing a gas into the space, and cooling the gas with a cooling line to indirectly cool the gas distribution plate.

Description

HIGH TEMPERATURE FLUIDIZED BED REACTOR

FIELD

[001] The present disclosure relates generally to fluidized bed reactors.

BACKGROUND

[002] A fluidized bed reactor (FBR) is a reactor vessel used to carry out a variety of multiphase chemical reactions. In an FBR, a fluid (e.g., a gas or a liquid) is passed through a solid particulate material (solids) at a velocity that can suspend the solids such that the solids behave as though it is a fluid. This process of suspending the solids using pressurized gas is called fluidization.

[003] When an FBR uses gas as a fluidization medium (also called fluidizing gas, working gas, or process gas), the operation of the reactor generally includes the following process. The pressurized gas is supplied to the fluidized bed reactor and enters the windbox, which is located under the gas distribution plate. One purpose of the windbox is to predistribute the gas uniformly before the gas passes through the gas distribution plate into the reaction chamber, typically via tuyeres. The gas distribution plate is sealed to the walls of the reactor such that the pressurized gas is directed through the tuyeres exclusively. The tuyere stems are connected to the gas distribution plate via a sealed joint (e.g., a weld or sealed thread). The purpose of the tuyeres is to evenly distribute the pressurized fluidizing gas over the bottom of the reaction chamber to achieve the desired operating conditions for a fluidized bed reactor application. Such operating conditions may include, for example, the extent of fluidization of the solids and/or the extent of gas-solid contact.

[004] Conventional FBR operations with precise gas distribution use metal tuyeres and a metal gas distribution plate with low or moderate temperature pressurized gas (e.g., below 300°C), such that the windbox and the distribution plate are at low or moderate temperatures, relative to the hotter reaction chamber. Typical FBRs are constructed such that the distribution plate is sealed to the reactor walls with an expansion joint (e.g., a single-bellow type expansion joint), which allows moderate temperature differences between the gas distribution plate and the reactor walls that may occur during ramp up, ramp down, upsets, and operation of the fluidized bed reactor.

[005] A conventional gas distribution plate may be a large, solid, metal plate. In another conventional embodiment, the distribution plate may comprise a top and bottom portion made of metal that sandwiches another material therebetween. The other material may be insulation, for example. The distribution plate may be circular. The expansion joint(s) in a fluidized bed reactor is typically relatively rigid and thick to accommodate the high temperature of the reaction chamber and the weight of the solid material in the reaction chamber. The expansion joint allows for some expansion and contraction of the distribution plate relative to the somewhat static reactor walls that do not expand or contract as much. The expansions/contraction of the distribution plate is due to heat transfer to or from other regions in the reactor, including from the windbox, the tuyeres, and/or the reaction chamber. By contrast, the reactor walls do not expand or contract as much as the distribution plate because the reactor walls do not have as much variation in temperatures from being on the outside of the FBR. This expansion and contraction of the distribution plate can occur during the ramp up, ramp down, upsets, and/or regular operation of the fluidized bed reactor.

[006] In certain applications, such as for large FBRs, the expansion joint may have difficulty accommodating the difference in expansions/contractions between the reactor walls and the distribution plate. US5129630A teaches a distribution plate and cooling line within the distribution plate. Water is circulated through the cooling line to directly cool the distribution plate from within. This cooling reduces the thermal fluctuations of the distribution plate such that the amount of expansions and contractions it experiences is less to allow the expansion joint to accommodate for the difference with the expansions/contractions of the reactor walls (or to forego with the expansion joint entirely).

[007] Some emerging FBR applications require a higher temperature of the fluidizing gas (e.g., above 300°C). Under operation conditions where the fluidizing gas is hot, the gas distribution plate will be exposed to higher temperatures from the hot windbox. To accommodate the thermal expansion of the gas distribution plate, the reactor wall temperature would also have to significantly increase to compensate a significant difference in thermal expansion between the reactor walls and the gas distribution plate, otherwise the reactor walls will bulge or deform from the expansion of the gas distribution plate. Such an increase in the temperature of the reactor walls is typically not acceptable in conventional fluid bed reactors, and particularly in pressurized vessels. One method of accommodating a higher temperature fluidizing gas is to internally insulate the windbox walls using, e.g., a refractory lining and/or to fabricate the gas distribution plate from refractory materials. However, these designs have can experience other challenges, such as maintaining the uniformity of gas distribution over the bottom of the reaction chamber, maintaining the gas seal between the gas distribution plate and the reactor wall, and avoiding back-sifting of the bed material into the windbox, as well as requiring frequent maintenance.

[008] Under operating conditions where both the windbox and the reaction chamber are hot (above 300°C), such as when high temperature gas is provided to the windbox (although the windbox and reaction chamber may be at different temperatures), the distribution plate can be subject to greater heat transfer from these regions. The heat transfer from the hot windbox and the hot reaction chamber can cause the distribution plate to significantly expand and contract during ramp up, ramp down, upsets, and operation of the fluidized bed reactor such that it is well beyond the capacity of the expansion joint. For some FBR processes, the reactor walls remain cool relative to the windbox and the reaction chamber. Some FBRs are also large such that they have a high-volume reaction chamber, large diameter distribution plate, and/or a large circumference I surface area reactor walls. When combined with a hot windbox gas application, these factors can further exacerbate the difference in the amount of the expansion I contraction of the distribution plate relative to the amount of expansion/contraction of the reactor walls such that an expansion joint is unable to accommodate this difference.

[009] For such hot gas FBR applications, cooling the distribution plate from within using a cooling line can cause the distribution plate to become cold and/or be very cold in the areas through which the cooling lines run. For a fluidized bed reactor application that uses a hot pressurized gas and/or a hot windbox, the cold distribution plate and/or cold localized areas create hot and cold zones over short distances. The resulting temperature gradients can cause stresses or failure in the distribution plate or its connections to other components in the reactor. For example, components connecting to the distribution plate (e.g., the hot tuyeres, the expansion joints, the reactor walls) and/or the cooling system may detach, break, or deform. Additionally, to help maintain the gas distribution plate at the target temperatures, steam or heat transfer fluids must be used, which complicates the mechanical design of the reactor.

[0010] Accordingly, an FBR with relatively cold reactor walls and even distribution of the fluidizing gas over the reaction chamber bottom that is capable of handling hot fluidizing gas (at potentially a higher pressure) is desired. SUMMARY

[0011] The present invention is for a fluidized bed reactor capable of receiving a high- temperature gas. The reactor comprises an enclosed space adjacent to the distribution plate. The space may be a compartment. The space may be partially or completely filled with a gas. The gas within the space may be the same gas that is introduced into the windbox. The space may be a dead or congested zone such that there is minimal or no gas flow within the space relative to the flow of gas within the windbox during operation of the fluidized bed reactor. The space is cooled using cooling lines positioned within the space. The cooling lines are positioned at a select distance from the gas distribution plate. This means that the cooling lines are not in direct contact within the gas distribution plate. Cooling the space helps indirectly cool the gas distribution plate to reduce or inhibit thermal expansion of the gas distribution plate as a result of exposure to the hot gas within the FBR. Cooling the gas distribution plate indirectly and/or positioning the cooling lines a select distance away from the tuyere stems so the cooling lines do not touch the gas distribution plate also minimizes the potential cooling of the high- temperature gas so as to help avoid interfering with the reaction process in the reaction chamber.

[0012] The reactor may comprise an isolation plate that defines, with the distribution plate, the enclosed space, the space being between the isolation plate and the gas distribution plate. The space may be between the windbox and reaction chamber. Indirect cooling of the gas distribution plate (by cooling the space adjacent to the distribution plate) helps inhibit thermal expansion of the gas distribution plate. Inhibiting this thermal expansion helps inhibit thermal stresses in the distribution plate and walls, and/or inhibit deformation of any expansion joint between the distribution plate and the walls to help prevent against the failure of the expansion joint. Although indirect cooling of the distribution plate in this manner does not cool the plate as significantly as the conventional direct cooling method, such indirect cooling results in less significant temperature gradients within the distribution plate and its connected components to help inhibit failure, especially failure at or about connections between the gas distribution plate and the other components in the reactor, such other components including the expansion joint and tuyeres. The connections with such components are typically formed of welds, but may also be threads. The welds may be made of metal. The welds may be stronger or weaker than the distribution plate and/or the components such that the welds may be contributing to the temperature gradients and/or are more prone to failure due to temperature gradients about the area of the welds. The temperature gradients in the gas distribution plate and/or the connections may be caused by heat diffusion from the hot reactor chamber, and/or the tuyere stems on the one hand, and cooling action of the cooling lines and/or the colder FBR walls on the other hand. Indirectly cooling the gas distribution plate via cooling the space adjacent to the FBR helps reduce the risk of the distribution plate connections failing while still cooling the plate sufficiently so the expansion joint can accommodate the expansion/contraction differences between the plate and the reactor walls. [0013] In an embodiment of the invention, the distribution plate is sealed to the reactor walls, e.g., with the expansion joint, and the isolation plate is not sealed to the reactor walls. Sealing to the walls means the component is affixed to all of the walls in such a way as to create a seal. The gas distribution plate is also sealed at the connections with the tuyeres, and specifically the tuyere stems. The tuyere stems may be connected to the gas distribution plate with a sealed joint, such as a weld or a sealed thread.

[0014] The fluid connection between the windbox and the enclosed space defined between the isolation plate and gas distribution plate allows each of the windbox and the space to equilibrate pressure during reactor operation. The isolation plate is free to thermally expand and/or contract. This configuration helps to reduce the temperature and/or pressure induced stresses in the isolation plate. While sealing the isolation plate to the reactor walls would help further reduce the amount of heat transfer between the windbox and the space, this would result in transferring more of the pressure induced stresses to the isolation plate. The fluid connection between the windbox and the space permits some heat transfer via hot gas diffusion from the windbox to the space. This heat transfer to the gas in the space may be minimal such that the temperature of the space does not reach the same temperature as the gas in the windbox during ramp up, ramp down, upsets, and operation of the fluidized bed reactor.

[0015] When the tuyeres are connected and sealed with the gas distribution plate, the isolation plate may not be rigidly connected to the tuyere stems. The tuyere stems may pass through oversized openings in the isolation plate, which allows a fluid connection between the windbox and the enclosed space. The isolation plate may have additional or other openings to allow or further increase the fluid connection between the windbox and the space. Similarly, the edges of the isolation plate may rest on gliding supports, which may allow free thermal expansion to avoid thermal stresses on the isolation plate or windbox wall and may further contribute to the fluid connection between the windbox and the space to avoid pressure differential across the isolation plate during ramp up, ramp down, upsets, and/or operation of the fluidized bed reactor.

[0016] In an aspect, the present disclosure provides a fluidized bed reactor comprising a windbox, a reaction chamber, a gas distribution plate sealed to a wall of the fluidized bed reactor with a gas tight seal, an isolation plate positioned within the bed reactor to define an enclosed space with the gas distribution plate, the enclosed space residing between the windbox and the reaction chamber, the enclosed space configured to be filled with a fluid, one or more tuyeres connecting the windbox to the reaction chamber for allowing a gas to be supplied from the windbox to the reaction chamber, and a cooling line disposed within the enclosed space a distance from the gas distribution plate to cool the fluid within the enclosed space. The fluidized bed reactor may comprise connections connecting the gas distribution plate to adjacent components. The fluidized bed reactor may comprise a gas distribution plate insulating layer positioned adjacent to the gas distribution plate, and an isolation plate insulating layer positioned adjacent to the isolation plate. The fluidized bed reactor may comprise isolation plate connections, wherein the isolation plate connections attach the isolation plate to the reactor to allow the gas to pass between the windbox and the enclosed space as the fluid. The isolation plate connections may comprise welds, the welds connecting the isolation plate with the one or more tuyeres. The fluidized bed reactor may comprise openings to allow the gas to pass between the windbox and the enclosed space as the fluid. The openings may be defined within the isolation plate to allow the tuyere stems to pass through the openings. The openings may be between the wall and the isolation plate. The cooling line may be configured to cool the fluid in the enclosed space to a temperature below a temperature of the gas in the windbox. The gas tight seal may comprise an expansion joint. The connections may comprise welds with the components adjacent to the gas distribution plate. The connections may connect the gas distribution plate to adjacent components comprising tuyeres. The cooling line may be configured to help inhibit thermal expansion of the gas distribution plate beyond the capacity of the gas tight seal and help inhibit local temperature gradients in the gas distribution plate and connections. The tuyere stems may be affixed to the gas distribution plate, and the cooling line may be disposed a distance from the gas distribution plate to provide a uniform cooling to the enclosed space and indirect cooling of the gas distribution plate to help inhibit failure of connections between the tuyeres and the gas distribution plate due to thermal stresses. The cooling line may comprise water, heat transfer fluid, or gas cooled lines. The cooling line may be supported by the gas distribution plate and/or the reactor walls. Each of the one or more tuyeres may comprise an insulated tuyere stem.

[0017] In another aspect, the present disclosure provides a process for operating a fluidized bed reactor, including: supplying a gas to a windbox, the windbox separated from a reaction chamber by a gas distribution plate, providing the gas via tuyeres from the windbox to the reaction chamber, providing a fluid to an enclosed space positioned adjacent to the gas distribution plate, and cooling the fluid in the enclosed space with a cooling line to indirectly cool the gas distribution plate. Cooling the fluid in the enclosed space may comprise providing a cooling fluid to a cooling line within the enclosed space, the cooling line positioned a distance from the gas distribution plate to cool the fluid within the enclosed space. The process may further comprise cooling the enclosed space using a cooling line to minimize temperature gradients in the gas distribution plate and one or more tuyeres. Providing the gas to the enclosed space may comprise providing the gas from the windbox to the enclosed space to allow equalization of the pressure between the enclosed space and the windbox. The process may further comprise providing the gas from the enclosed space to the windbox to allow equalization of the pressure between the enclosed space and the windbox. The process may further comprise providing the gas from the enclosed space to the winbox to allow equalization of the pressure between the enclosed space and the windbox. The process may further comprise inhibiting the gas in the enclosed space from circulating, which can further comprise inhibiting the gas from circulating within the enclosed space or entering the windbox. Cooling the fluid in the enclosed space may comprise inhibiting thermal expansion of the gas distribution plate beyond the capacity of a seal with the fluidized bed reactor wall, and inhibiting temperature gradients in the gas distribution plate. The tuyeres may comprise connections with the gas distribution plate, and the process further including inhibiting local temperature gradients above an allowable value from forming in the connections by indirectly cooling the gas distribution plate with the fluid in the enclosed space. The fluid in the enclosed space may be cooled to a select temperature that is less than the temperature in the reaction chamber and less than the temperature in the windbox.

BRIEF DESCRIPTION OF THE FIGURES

[0018] Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures. [0019] FIG. 1 depicts a perspective cross-sectional front view of a fluidized bed reactor in an embodiment of the present disclosure.

[0020] FIG. 2 depicts another cross-sectional front view of the fluidized bed reactor of FIG. 1.

[0021] FIG. 3 depicts a close up cross-sectional view of the fluidized bed reactor of FIG. 1 , illustrating the enclosed space defined by the gas distribution plate and the isolation plate.

[0022] FIGs. 4A and 4B depict a finite element analysis (FEA) of the equivalent von- Mises stress (in MPa) and the corresponding temperature distribution (in Celsius) in a fluidized bed reactor 100 under high temperature operating conditions.

DETAILED DESCRIPTION

[0023] FIGs. 1 and 2 show a cross-sectional front view of a fluidized bed reactor 100 in an embodiment of the present disclosure. The fluidized bed reactor 100 has a windbox 102, a reaction chamber 106, a gas distribution plate 108 (also sometimes referred to as a tuyere plate), an isolation plate 110, and a one or more cooling lines 112. The gas distribution plate 108 and isolation plate 110 are positioned in the fluidized bed reactor 100 to define an enclosed space 104, e.g., a congested zone or a compartment adjacent to the distribution plate 108. The enclosed space 104 is between the windbox 102 and the reaction chamber 106. During operation of the fluidized bed reactor 100, the windbox 102 receives then provides high temperature and pressurized gas to the reaction chamber 106 through one or more tuyeres 114. The gas proceeds through the tuyeres 114 and provides the high temperature pressurized gas to the reaction chamber 106.

[0024] In an embodiment, the isolation plate 110 may be constructed or configured to allow a fluid (e.g., a gas) to diffuse from the windbox 102 to the enclosed space 104. Allowing some of the working gas to transfer into the enclosed space 104 may reduce the pressure differential experienced by the isolation plate 110 and/or the gas distribution plate 108. This arrangement may help mitigate problems associated with supplying a pressurized gas to the windbox 102. In particular, when ramping up the reactor for operation (or ramping down), the pressure differential between the unpressurized enclosed space 104 and the pressurized gas in the windbox 102 (e.g., during ramp up and/or operation of the fluidized bed reactor 100) may mechanically stress the isolation plate 110 until an equilibrium or steady state operation is achieved. The fluid connection between the windbox 102 may permit the windbox 102 and the enclosed space 104 to reach a pressure equilibrium or steady state during operation of the reactor. This pressure equilibrium may reduce the mechanical stress resulting from pressure difference that is experienced by the isolation plate 110 during ramp up, ramp down, and/or regular operation of the reactor.

[0025] The equilibrated pressure between the windbox 102 and the enclosed space 104 can occur during ramp up of the fluidized bed reactor by supplying gas for a period of time until a fluid equilibrium is established. Once a fluid equilibrium is established between the enclosed space 104 and the windbox 102, regular operation of the fluidized bed reactor 100 may start, provided all other suitable ramp up activities have also completed.

[0026] The isolation plate 110 may have one or more openings 126 to allow for passage of the tuyere stems 130 though the isolation plate 110. The fluid connection between the windbox 102 and the enclosed space 104 may be achieved by a variety of means, for example, through the oversized holes that the tuyere stems 130 pass through additional holes in isolation plate 110, or by using an isolation plate 110 that is smaller than the inner circumference or perimeter of the reactor walls 116, or by using one or more isolation plates separated by a separation distance or spacers. These arrangements may help achieve the fluid connection between the windbox 102 and the enclosed space 104. These arrangements may also help mitigate the heat transfer from the windbox fluid/gas to the space fluid/gas. The isolation plate may be made of metal or any other material suitable for a particular fluidized bed reactor process.

[0027] The isolation plate 110 may also have isolation plate connections that permit a fluid connection between the windbox 102 and the enclosed space 104 and/or to support the isolation plate 110 in the fluidized bed reactor 100. For example, the isolation plate 110 may rest on a support that is welded or otherwise affixed to the reactor walls 116. The isolation plate connections may be connections (e.g., welds or threads) with the tuyere stems 130, the tuyere heads 128 / tuyere inlets. The isolation plate connection may be a connection between the isolation plate insulation (e.g., the isolation plate insulating layer 122) and the tuyere stem insulation 132. The isolation plate connections may be unsealed or partially sealed. The isolation plate connections may not be gas tight so as to allow fluid to pass from the windbox to the space. Some isolation plate connections may be sealed while other isolation plate connections may be not sealed, for example, to control the degree to which fluidizing gas may enter the enclosed space 104 from the windbox 102. [0028] In an embodiment, the gas distribution plate 108 is being heated by heat diffusion from the hot reactor chamber 106 and from the tuyere stems 130, and being cooled by cooling lines 112. This complex heat exchange process causes localized temperature gradients which induce localized thermal stresses in the plate 108. Indirect cooling of the distribution plate 108 does not cool the plate as intensely as the conventional direct cooling, and thus results in less significant temperature gradients in the distribution plate 108. A temperature gradient is the difference in temperature between two points having a select distance therebetween. This configuration reduces the risk of the distribution plate 108 failing while still cooling the plate sufficiently so the expansion joint 120 can accommodate the expansion/contraction differences between the plate and the reactor walls 116. In an embodiment, a cooling line 112 is positioned in the enclosed space 104 a distance away from the gas distribution plate 108. The cooling lines 112 may indirectly cool the gas distribution plate 108.

[0029] The cooling lines 112 may cool down the enclosed space 104 to a temperature in between or below the temperatures of the windbox 102, the reaction chamber 106, the reactor walls 116, and distribution plate 108. Cooling the enclosed space 104 using cooling lines 112 creates a smaller temperature gradient (i.e., a smaller difference in temperatures between two points a select distance apart) across the gas distribution plate 108, which helps reduce the local thermal stresses within the gas distribution plate 108 and inhibit failure of the gas distribution plate 108 and its connections to other elements in the fluidized bed reactor 100. This arrangement may help mitigate problems associated with cooling the gas distribution plate 108 directly, i.e., by using cooling lines 112 in direct contact with or embedded within the gas distribution plate 108, which can lead to elevated local thermal stresses on the gas distribution plate 108 and its connections. In addition, cooling the gas distribution plate 108 indirectly may also mitigate cooling the hot fluidized gas passing through the one or more tuyeres 114 to the reaction chamber 106. Cooling the hot gas is undesirable. Cooling the hot gas may interfere with and/or will reduce the energy efficiency of the process in the reaction chamber 106, and would further waste resources spent to heat the fluidized gas in the first place. For fluidized bed reactor applications using a hot fluidized gas, it is preferable to avoid cooling the gas before it reaches the reaction chamber 106, for example where the gas enters the tuyeres 114, in the enclosed space 104 and regions around the tuyere stems 130, and at the tuyere heads 128 where the gas is supplied to the reaction chamber 106. [0030] In an embodiment, the cooling line(s) 112 may be arranged in the enclosed space 104 to provide uniform cooling of the enclosed space 104 and to indirectly cool down the gas distribution plate 108, helping to inhibit failure in the gas distribution plate 108 and its connections due to thermal stresses. Gas distribution plate 108 connections typically comprise local discontinuities, which are variations in adjacent materials. Those discontinuities have a propensity to crack (e.g., fail) when exposed to significant temperature gradients.

[0031] The cooling line(s) or cooling pipe(s) 112 may be arranged in the enclosed space 104 in a variety of configurations to accommodate different applications or processes. There may be more than one cooling line 112 in some embodiments. The cooling line(s) 112 may be water, heat transfer fluid, or gas (including air) cooled lines. The cooling line(s) 112 may comprise, in whole or in part, a commercially available cooling system. The cooling line(s) 112 may comprise, in whole or in part, one or more customized components, such as cooling fins.

[0032] The active cooling line 112 may be supported, suspended, or otherwise arranged within the enclosed space 104 in any configuration suitable for a fluidized bed reactor application or process. The cooling lines 112 may be suspended by a wire under tension or supported by a structure. The cooling lines 112 may be arranged in a single horizontal plane or multiple planes in the enclosed space 104. The cooling lines 112 may be arranged to weave or snake around the tuyere stems 130. The cooling lines 112 may be arranged so as not to come into contact with the tuyere stems 130. The cooling lines 112 may be arranged uniformly or non-uniformly in the volume of the enclosed space 104. The cooling lines 112 may have a denser arrangement in some parts of the enclosed space 104 and/or a less dense arrangement in other parts of the enclosed space 104. One example of such an arrangement may include having more cooling lines 112 near the gas distribution plate 108 and fewer cooling lines 112 near the isolation plate 110, or vice versa. For some fluidized bed reactor applications or processes, the cooling lines 112 may be arranged to provide additional or reduced cooling to other components in the enclosed space 104 (or cool regions near those components in the enclosed space 104), including, e.g., the reactor walls 116 in the enclosed space 104, the tuyere stems 130, the tuyere stem connection with the gas distribution plate 108. For some fluidized bed reactor applications, it may be preferable to position the cooling lines 112 away from the tuyere stems 130 to minimize cooling of the hot fluidized gas.

[0033] FIG. 3 shows a close up cross-section view of a fluidized bed reactor 100, illustrating embodiments of the gas distribution plate 108 and isolation plate 110 in accordance with an embodiment of the present disclosure. The gas distribution plate 108 is connected to the reactor walls 116 using an expansion joint 120, e.g., a single-bellow type expansion joint. This expansion joint 120 allows for some expansion and contraction of the gas distribution plate 108 when its temperature changes, relative to the expansions/contraction experienced by the reactor walls 116. The reactor walls 116 can remain cooler during operations and may not expand and contract as significantly as the gas distribution plate 108, e.g., during ramp up, ramp down, upsets, and/or regular operation of the fluidized bed reactor 100. The reactor walls 116 may be actively cooled or heated according to the requirements of a particular fluidized bed reactor application or process.

[0034] In an embodiment, the gas distribution plate 108 may also be supported by supports 124. The gas distribution plate 108 may be supported by other means, such as structural beams and/or brackets in multiple arrangements.

[0035] In an embodiment, the gas distribution plate 108 is sealed to the walls 116 of the fluidized bed reactor 100 with an expansion joint 120. This seal can prevent gas from diffusing or moving into the reaction chamber 106 by any means other than through the tuyeres 114. A gas distribution plate insulating layer 118 (e.g., a refractory layer) may be positioned adjacent to the gas distribution plate 108. The gas distribution plate insulating layer 118 may comprise multiple layers of insulation of the same or different material. The gas distribution plate insulating layer 118 may reduce heat transfer from the hot reaction chamber 106 into the enclosed space 104. The gas distribution plate insulating layer 118 may be positioned above the gas distribution plate 108 to minimize heat transfer from the reaction chamber 106 to the gas distribution plate 108. Additional insulating layers may be positioned below the gas distribution plate 108 in some applications. The insulating layer 118 may be composed of a refractory material or other suitable insulating material. The refractory material may be the same or different as the reactor insulation layers 134 in the reaction chamber 106.

[0036] In an embodiment of the invention, an isolation plate insulating layer 122 is positioned adjacent to the isolation plate 110. The isolation plate insulating layer 122 provides insulation to reduce heat transfer from the hot windbox 102 to the enclosed space 104. The isolation plate insulating layer 122 may comprise multiple layers of insulation of the same or different material. The isolation plate insulating layer 122 may be positioned above or below the isolation plate 110 to minimize heat transfer from the windbox 102 to the enclosed space 104. The insulating layer 122 may be composed of a refractory material, board, wool type insulation, or any other suitable insulating material. [0037] In the fluidized bed reactor 100, the windbox 102 may be insulated with windbox insulation 136, and the reaction chamber 106 may be insulated with reactor insulation 134. The walls 116 of the fluidized bed reactor 100 may also be insulated in some or all parts of the fluidized bed reactor 100. For example, the walls defining the enclosed space or compartment may be insulated with any suitable insulating material for the fluidized bed reactor application. [0038] In an embodiment, a combination of active cooling and insulating means used in and/or around the enclosed space 104 may result in the fluid within the enclosed space 104 being at a temperature below the temperature of the fluid in the windbox 102. In some fluidized bed reactor applications, the cooling lines 112 cool the enclosed space 104 to a temperature significantly lower than the windbox temperature and the reaction temperature. This low gas temperature in the enclosed space 104 may help result in smaller local temperature gradients in the gas distribution plate 108 due to convective nature of the heat transfer from the distributor plate 108 to the colder gas of the enclosed space 104, comparing with the more aggressive direct cooling by conduction, while still effectively cooling the gas distribution plate 108 and reducing its thermal expansion.

[0039] The cooling lines 112 and/or the insulating means may be arranged to cool the enclosed space 104 such that a gradual temperature gradient forms in the enclosed space 104 between hot tuyere stems 130 and the walls 116 of the fluidized bed reactor 100. The cooling lines 112 and/or insulation (e.g., on the reactor walls 116, the isolation plate 110, below the gas distribution plate 108 and/or around the tuyere stems 130) may reduce the magnitude of the temperature gradient occurring between the hotter and cooler components in the enclosed space 104, including the tuyere stems 130 (hotter), the isolation plate 110, the reactor walls 116 (cooler), and the gas distribution plate 108.

[0040] Referring again to the fluidized bed reactor 100 of FIG. 1 , the one or more tuyeres 114 may have a tuyere stem 130, a tuyere head 128, and/or tuyere stem insulation 132. The tuyeres 114 supply hot and pressurized gas to the reaction chamber 106 via tuyere stems 130 and tuyere heads 128. The tuyeres 114 may be composed of metal. Since metal is thermally conductive, some heat may transfer from the tuyeres 114 into the enclosed space 104. The tuyere stem insulation 132 reduces heat transfer from the tuyeres 114 into the enclosed space 104. The tuyere stem insulation 132 may be composed of any insulating material compatible with the fluidized bed reactor process. The tuyeres 114 may be welded, threaded with a sealed thread (e.g., a National Pipe Thread (NPT)), or otherwise affixed to the gas distribution plate 108 and/or the isolation plate 110. [0041] Referring again to FIG. 2, an inlet 138 provides pressurized gas to the windbox 102. The gas may be supplied through the inlet 138 at a hot temperature. The inlet 138 may be configured and arranged according to the requirements of a particular fluidized bed reactor application. For example, the inlet 138 may comprise multiple inlets to supply multiple gases to the windbox 102 and/or reaction chamber 106 (e.g., the upper reactor). The inlet 138 or multiple inlets may supply one or more pressurized gasses of different composition and/or properties (e.g., temperature or pressure).

[0042] In an embodiment, a process for operating a fluidized bed reactor 100 is disclosed where a hot fluid (i.e. , the fluidizing gas for a high temperature fluidized bed reactor process) is supplied to the windbox 102. The fluidized bed reactor 100 is arranged to allow the hot fluid to flow into an enclosed space 104 between the windbox 102 and the gas distribution plate 108 to equalize the pressure between the enclosed space 104 and the windbox 102 such that a fluid pressure equilibrium is established. The process further includes inhibiting or reducing the circulation of the hot fluid in the space. The reactor 100 may comprise an isolation plate 110 to help inhibit the fluidizing gas from circulating in the space. By inhibiting circulation of the fluidizing gas in the enclosed space 104, this helps avoid reducing the temperature of the hot fluidizing gas within the windbox 102. The process may include cooling the space to reduce a temperature gradient between the gas distribution plate, the cool side of the fluidized bed reactor walls 116 and the hot side of one or more tuyeres 114, where the tuyeres connect the windbox 102 to the reaction chamber 106. The cooling lines may further be configured to help minimize temperature gradient between the regions, while keeping the heat losses low. The cooling lines may be configured to minimize cooling of the hot gas being supplied to the reaction chamber 106.

[0043] FIGs. 4A and 4B depict a finite element analysis (FEA) of the equivalent von- Mises stress (in MPa) and the corresponding temperature distribution (in Celsius) in a fluidized bed reactor 100 under high temperature operating conditions in accordance with an embodiment of the present disclosure. In Figures 4A and 4B, the tuyeres 114 pass through and are connected by welds to a gas distribution plate 108. This example shows the temperature-induced stresses that are below an allowable value for the material (Fig. 4A) in accordance with an embodiment of the present invention. These stresses result from temperature gradients (Fig. 4B) induced in the connections with the gas distribution plate in the scenario where an isolation plate 110 defines an enclosed space 104 and there are cooling lines 112 positioned in this space 104 a distance away from the gas distribution plate 108. In this example, the connections are welds connecting the gas distribution plate with components, where the components are the tuyere stems. Without installation of the isolation plate 110 and cooling lines 112, which provides indirect cooling to the gas distribution plate 108, the local stresses may be above an allowable value for the materials used in e.g., the gas distribution plate 108, welds, tuyeres 114, and/or tuyere stems 130. Indirect cooling of the gas distribution plate 108 may help prevent significant heat loss from the tuyere stems 130 that may otherwise occur from overcooling the gas distribution plate 108. Indirect cooling may also prevent thermal expansion of the distribution plate 108 to the extent that it may cause a failure of the expansion joint 120 in the case of insufficient cooling of the gas distribution plate 108. [0044] The embodiments described herein are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein but should be construed in a manner consistent with the specification as a whole.

Claims

WHAT IS CLAIMED IS:

1. A fluidized bed reactor comprising: a windbox; a reaction chamber; a gas distribution plate sealed to a wall of the fluidized bed reactor with a gas tight seal; an isolation plate positioned within the bed reactor to define an enclosed space with the gas distribution plate, the enclosed space residing between the windbox and the reaction chamber, the enclosed space configured to be filled with a fluid; one or more tuyeres connecting the windbox to the reaction chamber for allowing a gas to be supplied from the windbox to the reaction chamber; and a cooling line disposed within the enclosed space a distance from the gas distribution plate to cool the fluid within the enclosed space.

2. The fluidized bed reactor of claim 1 , further comprising connections connecting the gas distribution plate to adjacent components.

3. The fluidized bed reactor of claim 1 , further comprising a gas distribution plate insulating layer positioned adjacent to the gas distribution plate, and an isolation plate insulating layer positioned adjacent to the isolation plate.

4. The fluidized bed reactor of claim 1 , further comprising isolation plate connections, wherein the isolation plate connections attach the isolation plate to the reactor to allow the gas to pass between the windbox and the enclosed space as the fluid.

5. The fluidized bed reactor of claim 4, wherein the isolation plate connections comprise welds, the welds connecting the isolation plate with the one or more tuyeres.

6. The fluidized bed reactor of claim 1 , further comprising openings to allow the gas to pass between the windbox and the enclosed space as the fluid.

7. The fluidized bed reactor of claim 6, wherein the openings are defined within the isolation plate to allow the tuyere stems to pass through the openings.

8. The fluidized bed reactor of claim 6 or 7, wherein the openings are between the wall and the isolation plate.

9. The fluidized bed reactor of claim 1 , wherein the cooling line is configured to cool the fluid in the enclosed space to a temperature below a temperature of the gas in the windbox.

10. The fluidized bed reactor of claim 1 , wherein the gas tight seal comprises an expansion joint.

11. The fluidized bed reactor of claim 2, wherein the connections comprise welds with the components adjacent to the gas distribution plate.

12. The fluidized bed reactor of claim 2, wherein the connections connect the gas distribution plate to adjacent components comprising tuyeres.

13. The fluidized bed reactor of claim 2, wherein the cooling line is configured to help inhibit thermal expansion of the gas distribution plate beyond the capacity of the gas tight seal and help inhibit local temperature gradients in the gas distribution plate and connections.

14. The fluidized bed reactor of claim 1 , wherein the tuyere stems are affixed to the gas distribution plate, and wherein the cooling line is disposed a distance from the gas distribution plate to provide a uniform cooling to the enclosed space and indirect cooling of the gas distribution plate to help inhibit failure of connections between the tuyeres and the gas distribution plate due to thermal stresses.

15. The fluidized bed reactor of claim 1 , wherein the cooling line comprises water, heat transfer fluid, or gas cooled lines.

16. The fluidized bed reactor of claim 1 , wherein the cooling line is supported from the gas distribution plate and/or the reactor walls.

17. The bed reactor of claim 1 , wherein each of the one or more tuyeres comprises an insulated tuyere stem.

18. A process for operating a fluidized bed reactor, comprising: supplying a gas to a windbox, the windbox separated from a reaction chamber by a gas distribution plate; providing the gas via tuyeres from the windbox to the reaction chamber; providing a fluid to an enclosed space positioned adjacent to the gas distribution plate; and cooling the fluid in the enclosed space with a cooling line to indirectly cool the gas distribution plate.

19. The process of claim 18, wherein cooling the fluid in the enclosed space comprises providing a cooling fluid to a cooling line within the enclosed space, the cooling line positioned a distance from the gas distribution plate to cool the fluid within the enclosed space.

20. The process of claim 18, further comprising cooling the enclosed space using a cooling line to minimize temperature gradients in the gas distribution plate and one or more tuyeres.

21. The process of claim 18, wherein providing the gas to the enclosed space comprises providing the gas from the windbox to the enclosed space to allow equalization of the pressure between the enclosed space and the windbox.

22. The process of claim 21 , further comprising providing the gas from the enclosed space to the windbox to allow equalization of the pressure between the enclosed space and the windbox.

23. The process of claim 18, wherein cooling the fluid in the enclosed space comprises inhibiting thermal expansion of the gas distribution plate beyond the capacity of a seal with the fluidized bed reactor wall, and inhibiting temperature gradients in the gas distribution plate.

24. The process of claim 20, wherein the tuyeres have connections with the gas distribution plate, and further comprising inhibiting local temperature gradients above an allowable value from forming in the connections by indirectly cooling the gas distribution plate with the fluid in the enclosed space.

25. The process of claim 18, wherein the fluid in the enclosed space is cooled to a select temperature that is less than the temperature in the reaction chamber and less than the temperature in the windbox.