Selective catalytic reduction catalyst module support system and installation method

Abstract

The heater includes a convection section having columns with tubes received in the tubesheets and tubesheets coupled to the columns. The convection section includes a space between the tubesheets associated with corresponding pairs of columns. A structural frame is coupled to the columns and positioned within the space to slidably receive one or more catalyst support beds for loading or unloading catalyst into the convection section through lateral sides of the heater convection section. The structural frame may include beams, struts, sliding plates, and other frame elements that support the catalyst support beds and allow them to slide relative to the structural frame.

Description

[Technical Field]

[0001] The present disclosure is directed generally to selective catalytic reduction, and more particularly, but not exclusively, to selective catalytic reduction systems and methods for heaters. [Background technology]

[0002] 2. Description of Related Art Selective catalytic reduction ("SCR") of nitric oxide (NOx) is known to reduce NOx emissions. SCR technology is being applied to many industries to meet stricter emissions standards introduced to combat pollution and climate change. One such industry is the petrochemical processing industry, which typically uses large heaters, among various other process equipment, to produce petrochemical products from by-products of crude oil refining processes and other feedstocks. Operation of heaters for petrochemical processes can produce many emissions, including NOx.

[0003] At a high level, SCR of NOx in a heater is performed using an SCR catalyst module and controlled ammonia injection within the flue gas temperature window. The SCR reactor is equipped with a catalyst bed for carrying large blocks of catalyst. Some treatment systems are newly constructed with conventional SCR technology. However, such conventional SCR designs have many deficiencies. For example, known SCR systems and methods for heaters occupy a significant amount of space within the treatment system, have complex support structures, and have limited space and access to the structure for loading and removing the catalyst module.

[0004] It is also known to retrofit older systems with SCR technology to reduce NOx emissions when new, more stringent NOx emission standards come into effect. The above-mentioned drawbacks of known SCR technologies are particularly pronounced when retrofitting existing systems where space is more limited and the existing systems do not have the supporting structure for the SCR improvements. As a result, retrofitting is an expensive process that can involve significant system downtime, among other drawbacks.

[0005] The prior art fails to address the above challenges with known SCR technology. For example, U.S. Patent No. 7,399,458 to Martin et al. ("Martin") appears to describe a heating equipment system and its operating process that combines stationary industrial burner technology with a catalyst bed that converts pollutants formed during combustion of fuel and air in the burner to produce a stack gas that can be emitted into the atmosphere. At a high level, Martin's system and method primarily relate to the use of a catalyst bed within a heating equipment system. However, such an arrangement does not address NOx emissions contained in the flue gas stream within existing heating heaters. Furthermore, Martin's SCR technology is installed directly as part of the burner system, thus limiting its general applicability to heating heaters, including for retrofitting existing systems.

[0006] U.S. Patent No. 7,500,437 to Lefebvre et al. ("Lefebvre") appears to describe a method and system for controlling SCR performance in a fossil-fuel boiler by developing a profile of one or more conditions that affect SCR performance. For example, a controller receives performance targets for the boiler, data values ​​corresponding to boiler control variables, and data related to boiler performance variables. These data inputs are then used to develop a desired boiler performance model. As a result, Lefebvre appears to be directed to modeling and optimization of operating parameters for fossil-fuel boilers that fails to address the deficiencies of known SCR technologies discussed above.

[0007] Lisberger's U.S. Patent No. 9,314,739 appears to describe a process and apparatus for denoxing flue gas containing carbon monoxide and / or gaseous organics, comprising at least one catalyst for catalytic reduction of NOx and a heat exchanger for heating the flue gas to a reaction temperature of 160°C to 500°C from the recovery of residual heat from the denoxed flue gas prior to catalytic reduction. For optimal denoxing of the flue gas while simultaneously minimizing the required externally supplied energy, Lisberger assumes that losses associated with heat transfer in the heat exchanger are compensated for by providing at least one stage for post-regenerative combustion of the carbon monoxide and / or gaseous organics. As a result, Lisberger appears to be directed to reducing NOx emissions through post-regenerative combustion after the SCR stage, but fails to address the challenges of known SCR systems and methods.

[0008] WIPO Published Application No. 2014 / 116929 to Novak et al. ("Novak") appears to describe the reduction of NOx emissions from a heater having a combustion air preheating furnace and using a high emission rate coating. In summary, Novak appears to be directed to combining air preheating with a high emission rate coating to increase radiant efficiency, which in turn reduces total heating and NOx emissions. As a result, Novak appears to be generally unrelated to SCR technology.

[0009] WIPO Published Application No. 2010 / 132563 to Pfeffer et al. ("Pfeffer") appears to describe a multi-stage system for removing NOx from combustion flue gases via SCR or selective non-catalytic reduction with ammonia or ammonia-forming compounds, followed by treatment with hydrogen peroxide to remove residual ammonia and, optionally, treatment with an alkaline reagent to reduce residual NOx in the flue gas stream. The NOx-depleted flue gas stream may also be subjected to desulfurization treatment for removal of SOx. However, Pfeffer similarly fails to address the problems with known SCR technology raised above.

[0010] Canadian Patent No. 2,439,866 to Mcnertney et al. ("Mcnertney") appears to describe a passive system for recovering energy and nitrogen oxides from flue gas produced by a boiler that uses a specific arrangement of economizer surfaces to ensure that the temperature of the flue gas entering the SCR reactor is maintained within a required range over a wide range of boiler loads. Such application of SCR technology to boilers with varying loads and shifting temperature ranges entering the SCR catalyst bed differs from SCR technology in the stable operation of a heating heater or decomposition heater. Furthermore, Mcnertney fails to address the problems of known SCR technology raised above.

[0011] U.S. Patent Publication No. 2012 / 0222591 ("Greenhut") to Greenhut et al. appears to describe a power boiler and a method of selective catalytic NOx reduction in a power boiler having selective catalytic NOx reduction. Fuel is combusted in a furnace of the boiler to produce a flue gas stream containing NOx. The flue gas stream is directed from the furnace to a stack along a flue gas groove. The flue gas stream is cooled in a heat recovery area including an economizer section disposed in the flue gas groove. At least a portion of the NOx is reduced to N2 in a NOx catalyst disposed in the flue gas groove downstream of the economizer section. The flue gas is further cooled, and heated air is produced in a gas-to-air furnace disposed in the flue gas groove downstream of the economizer section and upstream of the NOx catalyst. Like other examples of the prior art discussed above, Greenhut is directed to SCR technology for boilers, specifically power boilers, which fails to understand the challenges associated with SCR technology for heaters.

[0012] As a result, it would be advantageous to have an SCR system and method that overcomes the deficiencies and drawbacks of known SCR technology. Summary of the Invention

[0013] The disclosed concepts are generally directed to the installation of an SCR catalyst module in the convection section of a heater, such as a steam cracker, where a suitable flue gas temperature window for SCR of NOx is located. The disclosed concepts can be implemented in many forms and in other industries besides petrochemical processing. Among other advantages, the disclosed concepts allow the catalyst support structure to be an integral part of the convection section of the heater, instead of utilizing a separate, distinct structure for SCR of NOx with a catalyst module as in known SCR systems, thereby reducing plot space and equipment count. Furthermore, the catalyst support grid structure is designed with the catalyst module installed within a cavity, instead of being positioned on top of the support structure as in known systems. The disclosed concepts also allow the catalyst support structure and installed catalyst module to self-seal when the catalyst module is placed on the support structure, eliminating the commonly used sealing tape. Additionally, the concepts of the present disclosure allow for loading and unloading of SCR catalyst modules on the lateral sides of the convection section along the entire convection length, as opposed to conventionally loading or unloading catalyst modules through the ends of the convection section, to achieve the target NOx reduction.

[0014] For heaters designed and manufactured when NOx emission standards were less stringent, space and structural support for SCR catalyst modules were not considered. As a result, these heaters were not designed or equipped with large vertical spaces, access doors, and structural supports for loading and removing SCR catalyst modules. For example, in existing ethylene cracking heater designs, the convection section is typically designed with multiple coil banks for preheating process streams and boiler feedwater and steam. The vertical spacing between two coil banks may be approximately 460 mm, measured between the centerlines of two adjacent tube rows. This space was originally intended to allow for the installation of lancing doors for performing routine maintenance or to provide mechanical clearance from others. The concepts of the present disclosure enable such existing heaters, and others, to be retrofitted with SCR technology to reduce NOx emissions by utilizing a structural frame system to support the SCR catalyst module, enable loading and removal of the SCR catalyst module, and create a suitable seal for directing all flue gas flow through the catalyst. As a result, in some non-limiting examples, loading and unloading of the SCR catalyst module can be accomplished through the lateral sides of the convection section instead of through the ends of the convection section along the entire length of the convection section in a space no greater than 460 mm in height, with additional benefits and advantages described elsewhere herein.

[0015] In some non-limiting examples, the heater includes a convection section having a plurality of columns or other supports arranged in pairs spaced apart from each other in the longitudinal or lengthwise direction of the convection section. The pair of columns includes a first column and a second column spaced apart from each other in the transverse or width direction of the convection section. Tubesheets are coupled to the columns, and the pair of tubesheets is coupled to a corresponding pair of columns. The pair of tubesheets includes a first tubesheet and a second tubesheet stacked along the corresponding column in the axial or height direction of the convection section. Multiple tube bundles are coupled to the multiple tubesheets. The convection section includes a gap or space between the first tubesheet and the second tubesheet in each pair of tubesheets in the axial or height direction of the convection section.

[0016] The structural frame is positioned within the gap to support a first catalyst support bed, the first catalyst support bed being slidable relative to the columns to allow catalyst to be loaded or unloaded into or from the convection section through at least one lateral side of the convection section. More specifically, the structural frame includes a plurality of beams coupled to the columns and extending laterally of the convection section through the gap, each of the plurality of beams including a first flange with a rail and a second flange with a guide element. The first catalyst support bed includes a plurality of struts coupled together with catalyst modules received in one or more cavities defined by the struts. At least one of the plurality of struts includes a groove that interfaces with a rail on a first flange of a corresponding one of the plurality of beams to allow sliding of the first catalyst support bed relative to the plurality of beams. The structural frame also includes a support bar disposed on a second flange of a corresponding one of the plurality of beams, the support bar including a slot configured to interface with a guide element on a second flange of a corresponding one of the plurality of beams to assist sliding of the first catalyst support bed.

[0017] At least one lateral side of the convection side may be a first lateral side of the convection section. The structural frame may further include a second catalyst support bed having similar characteristics to the first catalyst support bed to allow loading or unloading of catalyst on the second catalyst support bed through a second lateral side of the convection section opposite the first lateral side. The structural frame may further include an access door frame coupled to the columns and one or more removable access doors coupled to the access door frame. The convection section further includes gaskets between the support bar and the plurality of beams, and between corresponding ones of the plurality of beams and the tubesheet, as well as a sealing plate between the first catalyst support bed and the second catalyst support bed to enable self-sealing to guide all flue gas flow through the catalyst module. In some examples, an insulating layer or insulating block may be provided between the access door and the catalyst support bed. Other features of embodiments of the present disclosure are described elsewhere.

[0018] The present disclosure will be more fully understood by reference to the following figures, which are for illustrative purposes only. In the drawings, like labels refer to like parts throughout unless otherwise specified. The figures do not describe every aspect of the teachings disclosed herein and do not limit the scope of the claims. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is an isometric view of one embodiment of a convection section of a heater according to the present disclosure. [Figure 2] FIG. 2 is an isometric view of a subsection of the convection section of FIG. 1 showing a first catalyst support bed and a second catalyst support bed. [Figure 3] FIG. 3 is an isometric view of the structural frame of the subsection of FIG. 2. [Figure 4A] FIG. 4 is a detailed view of one end of the structural frame of FIG. 3, showing additional features of the structural frame. [Figure 4B] FIG. 4 is a detailed view of one end of the structural frame of FIG. 3, showing additional features of the structural frame. [Figure 5]FIG. 3 is a detailed lateral view of a subsection of FIG. 2 showing a frame for a removable access door. [Figure 6] FIG. 3 is an isometric view of a subsection of FIG. 2 showing the sliding action of the first catalyst support bed. [Figure 7A] FIG. 3 is a detailed view of one end of a subsection of FIG. 2 showing a seal or gasket between the first and second catalyst support beds. [Figure 7B] FIG. 3 is a detailed view of one end of a subsection of FIG. 2 showing a seal or gasket between the first and second catalyst support beds. [Figure 8] FIG. 3 is a detailed view of one end of the subsection of FIG. 2 showing the seal or gasket between the structural frame and the convection section. DETAILED DESCRIPTION OF THE INVENTION

[0020] Those skilled in the relevant art will appreciate that the present disclosure is illustrative only and is not limiting in any way, and other embodiments of the presently disclosed systems and methods will readily suggest themselves to such skilled artisans given the benefit of the present disclosure.

[0021] Each of the features and teachings disclosed herein can be used separately or in conjunction with other features and teachings to provide SCR devices, systems, and methods. Representative examples utilizing many of these additional features and teachings, both separately and in combination, are described in further detail with reference to the accompanying figures. This detailed description is intended merely to teach those skilled in the art further details for implementing aspects of the present teachings and is not intended to limit the scope of the claims. Thus, the combinations of features disclosed in the detailed description are not necessary to implement the teachings in their broadest sense, but instead may be taught only to specifically illustrate representative examples.

[0022] Furthermore, various features of the representative examples and dependent claims may be combined in ways not specifically and explicitly recited to provide additional useful embodiments of the present teachings. It is also particularly noted that all value ranges or representations of groups of entities disclose all possible intermediate values ​​or intermediate entities for purposes of the original disclosure and for purposes of limiting the claimed subject matter. It is also particularly noted that the dimensions and shapes of components shown in the figures are designed to aid in understanding how the present teachings may be implemented, but in some embodiments are not intended to limit the dimensions and shapes shown in the examples. In some embodiments, the dimensions and shapes of components shown in the figures are precisely scaled and are intended to limit the dimensions and shapes of the components.

[0023] As described in more detail below, the concepts of the present disclosure are generally directed to SCR technology provided in a structural frame form factor that is self-supporting and can be attached to existing columns in the convection section of the furnace. Such an arrangement can allow for both vertical and horizontal thermal expansion movement while providing access to the catalyst blocks through the lateral sides of the convection section for loading and unloading SCR catalyst modules.

[0024] The concepts of the present disclosure are particularly useful for reducing NOx emissions from existing heaters, including, but not limited to, existing steam crackers, without significant structural modifications. In other words, the concepts of the present disclosure are advantageous for retrofitting existing process technology, providing a low-cost method for installing SCR catalyst modules to reduce NOx emissions in existing facilities. The technology can also be installed as a new design option, providing partial NOx emission reduction at low cost, without the major structural installation of catalyst modules, as in current systems.

[0025] In some non-limiting examples, methods are disclosed for increasing the radiative efficiency of existing furnaces, particularly, but not exclusively, steam cracking furnaces for producing bulk chemicals such as ethylene, propylene, butadiene, and others, whereby air, fuel, or both are preheated using energy recovered from the flue gas. Such preheated air and / or fuel mixtures result in higher NOx in the flue gas, and the concepts of the present disclosure assist in reducing such NOx emissions.

[0026] While the present disclosure proceeds to describe specific examples of technology applied to the convection section of a steam cracker, which may be particularly advantageous in petrochemical processing and refining, it will be understood that the concepts of the present disclosure may be applied to a wide range of technologies and industries. In particular, the concepts of the present disclosure may be equally applicable to any industry or technology that utilizes heaters, such as at least the offshore, refinery, power, petrochemical, or paper and food industries, among others. Furthermore, the concepts of the present disclosure may be applied to technologies and industries where it is advantageous to reduce NOx emissions generally. Therefore, the concepts of the present disclosure are not limited to the examples provided below.

[0027] FIG. 1 illustrates one or more embodiments of a convection section 100 of a heater according to the present disclosure. For clarity regarding the concepts of the present disclosure, the convection section 100 is illustrated without additional components of the heater, such as at least a shell. The convection section 100 is oriented in FIG. 1 with its length (i.e., largest dimension) extending longitudinally, its width (i.e., inside and outside the page) extending laterally, and its height (i.e., from bottom to top, according to the ordinary meaning of those terms) extending axially. Unless otherwise provided herein, the directional indicators “longitudinal,” “lateral,” and “axial” merely provide a frame of reference for describing the concepts of the present disclosure and are not intended to limit the present disclosure to any particular configuration. For example, although the convection section 100 is oriented generally horizontally with its longitudinally extending length in FIG. 1 , in some embodiments, the convection section 100 may also be oriented perpendicular to its axially extending length.

[0028] The convection section 100 may be approximately 15 meters long by 3 meters wide, among other things, and includes a support system including a plurality of columns 102 (which may also be referred to herein as supports 102), a plurality of tubesheets 104 coupled to the plurality of columns 102, and a plurality of tubes or tube bundles coupled to the plurality of tubesheets 104. In embodiments of the present disclosure in which the convection section is retrofitted with SCR technology in accordance with the concepts herein, the support system including the columns 102, tubesheets 104, and tubes 106 may be part of an existing heater structure. Alternatively, such a support system may be constructed as part of a new system installation. The plurality of columns 102 are arranged in pairs 102P, with the pairs 102P spaced apart from one another along the length of the convection section. Each pair 102P includes a first column 102A and a second column 102B, with the first column 102A laterally spaced apart from the second column 102B in each pair 102P.

[0029] The plurality of tubesheets 104 are coupled to the plurality of columns 102 and include pairs of tubesheets 104P coupled to corresponding pairs of columns 102P. In one embodiment, the pairs of tubesheets 104P are axially arranged along the pairs of columns 102P, and each pair of tubesheets 104P includes a first tubesheet 104A and a second tubesheet 104B. The first tubesheet 104A may be the upper tubesheet 104A, while the second tubesheet 104B may be the lower tubesheet 104B in each pair of tubesheets 104P, or vice versa. Thus, in some non-limiting examples, the first tubesheet 104A may be positioned axially above the second tubesheet 104B. The plurality of tubes 106 may be arranged in bundles coupled to the plurality of tubesheets 104. 1 illustrates only one tube 106 coupled to one of the first tube sheets 104A and one of the second tube sheets 104B, with the tube 106 illustrated schematically as a dashed line to avoid obscuring features of the present disclosure, it should be understood that the tube 106 may include a significantly larger number of tubes 106 or tube bundles 106 than illustrated in FIG. 1, and that the tube 106 generally extends along all, or at least a majority, of the length or longitudinal direction of the convection section 100, with support provided by the tube sheet 104. Furthermore, the tube sheet 104 may instead be a tube support in some embodiments.

[0030] The above-described arrangement of the tubesheets 104 and tubes 106 in the support system of the convection section 100 creates spaces or gaps 108 in the axial direction between the tubes 106. The gaps 108 between the tubes 106 are larger than the spaces between the outer frames of the tubesheets 104, allowing for the installation of larger catalyst modules and improving SCR performance and NOx reduction while utilizing the maximum amount of available space. The gaps 108 are occupied by a structural frame for the SCR module of FIG. 1 , described further elsewhere, with the gaps 108 and additional tubes 106 more clearly shown in FIG. 5 . In some embodiments, the vertical or axial distance between the two tube bundles above and below the gap 108 is approximately 460 mm, measured between the centerlines of the tube rows adjacent to the gap 108, such as that illustrated in FIG. 5 . Thus, the gap 108 may be approximately 460 mm in the axial direction in some embodiments, or may be as small as approximately 300 mm or 200 mm, as further non-limiting examples of convection sections having different configurations. The arrangement of the support system of the convection section 100 defines subsections 100S between pairs of columns 102P and pairs of tubesheets 104P. As shown in FIG. 1 , the convection section 100 includes, but is not limited to, at least six subsections 100S. The convection section 100 also includes end faces 110 at opposite longitudinal ends of the convection section 100, such that the length of the convection section 100 may be defined as being between the end faces 110. Lateral sides 112 of the convection section 100 extend between the end faces 110, and the lateral sides 112 generally refer to the front and rear in the orientation of FIG. 1 and in accordance with the conventional meaning of "front" and "rear."

[0031] In typical convection sections known in the art, the vertical space between tubesheets may allow for the installation of lancing doors or provide mechanical clearance for performing routine maintenance. Furthermore, catalyst modules for SCR technology are typically loaded and removed through the ends (i.e., end faces 110) of the convection section, with a typical convection section conventionally including a single catalyst support bed spanning the entire longitudinal length of the convection section (i.e., a single bed between the end faces 110). Such an arrangement inherently makes catalyst modules less accessible for loading and removal (among other options), particularly for catalyst modules toward the center of the convection section, among other drawbacks. Additionally, the space for loading and removing catalyst modules at the end faces of a typical convection section limits the height or size of the catalyst module to the space between the tubesheets, which also limits the overall effectiveness of SCR for NOx reduction. The present disclosure contemplates mounting SCR catalyst modules using a gap 108 larger than the space between tubesheets 104 to overcome the above-mentioned deficiencies of the prior art related to lack of space, structural support, and module access when building a new convection section or retrofitting an existing convection section. As described in more detail below, the disclosed concept allows for loading and unloading of SCR catalyst modules through the lateral sides 112 of the convection section instead of around the end faces 110 as is typical in the art, allowing for larger SCR catalyst modules to be loaded and unloaded into the system, among other advantages described herein, and also allowing for more efficient retrofitting of existing systems, improving unloading or removal operations while maximizing available space. Additionally, the disclosed concept does not rely on a single catalyst support bed throughout the longitudinal length of the convection section, but rather utilizes one or more catalyst support beds (which may also be referred to herein as “SCR modules” carrying one or more catalyst modules) in each distinct and separate subsection 100S of the convection section 100, improving loading and unloading operations, among other advantages.In other words, the disclosed concepts provide an SCR module that can carry one or more catalyst modules in each of one or more subsections 100S of the convection section 100, with the subsections 100S spanning less than the entire longitudinal length of the convection section, to provide the advantages described herein. Thus, the disclosed concepts provide multiple independent, parallel sections, each containing a respective SCR module (or catalyst support bed), that can be installed from the lateral side of the respective section, instead of the end face of the entire convection section. Furthermore, the disclosed concepts provide various seals that direct all flue gas flow through the catalyst block. As a result, the disclosed concepts enable loading and unloading of catalyst modules through the lateral side 112 of the convection section 100 in spaces, such as gaps 108, that are significantly smaller than conventional SCR technology, such as spaces or gaps 460 mm or less in height, in some embodiments. These concepts may be implemented via structural frame embodiments coupled to multiple columns 102, as described in more detail below.

[0032] FIG. 2 illustrates a representative subsection 100S of the convection section 100 in more detail, and FIG. 3 illustrates a representative subsection 100S without a catalyst module. As described above, each subsection 100S may be defined between consecutive pairs of columns 102 and tubesheets 104 within the convection section 100. Furthermore, unless otherwise provided herein, each subsection 100S may have the same or similar features. With reference to FIGS. 2 and 3, the subsection 100S includes a structural frame 114 coupled to the columns 102. The structural frame 114 is configured to support one or more catalyst modules 116. The catalyst modules 116 may be sized and shaped to be received within the gaps or spaces 108 between the tubes 106 without interfering with the tubes 106 (FIG. 1). For example, in some embodiments, the height of the modules 116 in the axial direction may be less than 460 mm. In one embodiment, repositioning the heating surfaces (or tubes 106) above and / or below the structural frame 114 may allow for installation of catalyst modules 116 greater than 460 mm in height within the gap 108. Or, in other words, the space or gap 108 may be greater than 460 mm by repositioning the tubes around the gap 108. Increasing the available space and installing larger catalyst modules 116 increases the residence time of the effluent flow through the catalyst module 116, and therefore increases NOx reduction for compliance with NOx emission standards. Thus, in some embodiments, the gap or space 108 may have an axial height greater than 460 mm, such as 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, or more.

[0033] In the non-limiting example illustrated in FIG. 2 , eight catalyst modules 116 are arranged side by side and received on the structural frame 114. Specifically, the catalyst modules 116 may be arranged in two longitudinal rows of four catalyst modules 116 each. Other configurations are possible and contemplated herein, such as three or more rows of catalyst modules 116, or in the simplest arrangement, a single row and one catalyst module 116 per row. The catalyst modules 116 can be loaded or removed through at least one lateral side 112 via a removable access door 117. The access door 117 may include a single door or several doors coupled together to allow selective access to portions of the catalyst module 116 or to aid in manipulating the door 117 during removal.

[0034] FIG. 3 illustrates subsection 100S without catalyst modules 116 to provide further detail regarding aspects of the structural frame 114. With continued reference to FIG. 2 , structural frame 114 includes a plurality of beams 118 coupled to a plurality of columns 102. In one embodiment, structural frame 114 may include one beam 118 coupled to a corresponding pair of columns 102P at each end of subsection 100S, with each beam 118 extending laterally through gap 108. In one embodiment, beams 118 may be coupled to individual columns 102 and at least partially received within brackets 120, described in more detail below. One or more catalyst support beds 122 are removably coupled to the plurality of beams 118 and positioned within gap 108. More specifically, one or more catalyst support beds 122 are slidably received on the plurality of beams 118 to enable loading and unloading of catalyst modules 116 through at least one lateral side 112 of convection section 100.

[0035] In one embodiment, each subsection 100S of the convection section 100 includes two catalyst support beds 122A, 122B adjacent to each other within the gap or space 108. The enclosed figures illustrate two catalyst support beds in each subsection 100S as an illustrative and non-limiting example of the concepts of the present disclosure. In some embodiments, each subsection 100S may include three or more catalyst support beds for a laterally wide convection section or only one bed for a laterally narrow convection section. Each catalyst support bed 122 is longitudinally disposed and may receive one or more catalyst modules 116, such as, in a non-limiting example, the row of catalyst modules 116 described with reference to FIG. 2 . As such, the catalyst modules 116 may be loaded and removed through opposite forward and / or aft lateral sides 112 of the convection section 100 via sliding the catalyst support beds 122A, 122B relative to beams 118 positioned at opposite longitudinal ends of the catalyst support beds 122A, 122B. The catalyst support beds 122 may each include a plurality of struts 124 extending between successive beams 118 to receive and support the catalyst modules 116 within the structural frame 114 .

[0036] 4A and 4B are detailed views of one longitudinal end of subsection 100S. Starting with FIG. 4A, each strut 124 of one or more catalyst support beds 122 may include a generally flat, planar web or sidewall 128A extending longitudinally and a flange 128B extending perpendicularly (i.e., laterally) from the bottom of web 128A into receiving space 126. Flange 128B may support the bottom surface of catalyst module 116 (FIG. 3) and distribute the weight of catalyst module 116 to web 128A and to the structural frame 114 and the entire support system of convection section 100. Furthermore, FIG. 4A illustrates that when subsection 100S includes two catalyst support beds 122, the struts 124 of each bed may be positioned adjacent to one another, or in some cases, may be positioned in contact with one another along a longitudinal centerline through subsection 100S. Such placement of the struts 124 helps to provide a seal between the catalyst support bed 122 and other aspects of the subsection 100S to ensure that all flue gas flows through the catalyst module 116.

[0037] 4A also provides additional details regarding the brackets 120. The brackets 120 may be coupled directly to a respective one of the columns 102 and may be configured to receive at least a portion of a corresponding one of the beams 118. In one embodiment, there are two brackets 120 coupled to each column 102 above and below each beam 118. Each bracket 120 may include a groove 130 formed by spaced-apart sidewalls of the bracket 120 that receives a portion of the web 132 of the beam 118, such as an axial extension of the web 132 of the beam 118. The brackets 120 may generally have an "L-shape" with the groove 130 formed in a first extension of the "L" and a second extension 134 of the "L" perpendicular to the first extension welded to the column 102 to provide a flange extension supporting the sidewall of the bracket 120 that defines the groove 130. In one embodiment, the axially upper bracket 120 of the beam 118 is structured to axially align the beam 118 and limit any longitudinal displacement of the beam 118. However, the beam 118 may not be coupled to the axially upper bracket 120 of the beam 118; rather, the beam 118 may be free to slide (i.e., unrestricted in any direction) inside the axially upper bracket 120 of the beam 118 due to thermal expansion during operation. The axially lower bracket 120 of the beam 118 is configured to provide load-bearing support to the beam 118 as well as axially align the beam 118 and limit longitudinal displacement. As a result, the beam 118 may be free to slide longitudinally, laterally, and axially inside the upper bracket 120 due to thermal expansion during operation, but is restricted from downward axial displacement by the lower bracket 120 such that thermal expansion during operation occurs in an upward axial direction (i.e., vertically upward).

[0038] 4B, the plurality of beams 118 includes a web 132, a first flange 136A, and a second flange 136B that extend generally axially through the gap 108 (FIG. 3). Each of the flanges 136A, 136B may be orthogonal to the web 118, meaning that the flanges 136A, 136B are perpendicular to the web 132 of the beam 118 and extend longitudinally. The first flange 136A may be an upper flange that includes a rail 138 that extends orthogonally or perpendicularly to the first flange 136A in an upward direction away from the first flange 136A. The plurality of struts 124 of the catalyst support bed 122 may include longitudinal ends 140 including grooves 142 that interface with rails 138 of the first flanges 136A of the plurality of beams 118 to help guide the catalyst support bed 122 relative to the beams 118 and columns 102 during sliding and / or loading or unloading operations. The rails 138 are received in the grooves 142 of the ends 140 of the struts 124, which also define hooks 144 at the ends 140 of the struts 124 that extend opposite the rails 138 of the first flanges 136A that face the web 132 of the beams 118. Thus, the upper portion of each strut 124 of the catalyst support bed 122 may be guided by the first flanges 136A of the beams 118. In some embodiments, the rails 138 on the first flange 136A and the grooves 142 on the ends 140 of the struts 124 limit longitudinal movement of the catalyst support bed 122 while allowing thermal expansion in at least one direction (i.e., longitudinal and / or axial) to aid in aligning and sliding the catalyst support bed 122 relative to the beam 118. The bottom of the struts 124 may be disposed on a support bar 146 that interfaces with the second flange 136B of the beam 118, as described in more detail below.

[0039] FIG. 5 shows one of the lateral sides 112 of subsection 100S. In particular, FIG. 5 is provided to illustrate details of access door frame 148. Access door frame 148 includes a plurality of frame elements 150 extending longitudinally and axially at lateral side 112 of subsection 100S (and convection section 100 generally) and defining access openings 152 through which catalyst modules 116 can be loaded into or removed from subsection 100S, or both. Access doors 117 (FIG. 2) are removably coupled to access door frame 148 and, in some non-limiting examples, selectively provide access to catalyst modules 116 via removal of door 117 or selectively cover and seal access opening 150, relative to one another. Each of frame elements 150 may be "L" shaped to receive door 117 (FIG. 2) and provide a flange for securing door 117 to frame element 150 using fasteners. In one embodiment, the frame elements 150 are coupled with fasteners to a plurality of posts 102. The access door frame 148 may also be welded to a convection module protection plate (not shown) coupled to the posts 102.

[0040] FIG. 6 illustrates the sliding operation of one of the catalyst support beds 122B. The support bars 146 may include multiple support bars 146, with at least one support bar 146 associated with each beam 118. The support bars 146 are configured to slide on the second flanges 136B of the beams 118, as conceptually illustrated in FIG. 6. During operation, the support bars 146 may initially rest on the second flanges 136B of the beams 118, and the catalyst support beds 122A, 122B are initially supported at the bottom by the support bars 146. The support bars 146 and catalyst support beds 122A, 122B then slide through access openings 152 in the access door frames 148 at the corresponding lateral sides 112 of the subsection 100S (or convection section 100). FIG. 6 further illustrates that in some embodiments, the struts 124 supporting the catalyst modules 116 may include struts across the lateral end faces of the catalyst modules 116, but rather the modules 116 may be self-supporting in position within the catalyst support beds 122A, 122B, or may be coupled to each other to provide a seal, or both.

[0041] 7A and 7B are cross-sectional views of one end of subsection 100S. Specifically, FIG. 7A is a longitudinal cross-sectional view, and FIG. 7B is a transverse cross-sectional view. Starting with FIG. 7A, the struts 124 of one or more catalyst support beds 122 can be bonded together with a sealing plate 154. The sealing plate 154 can be provided in the form of a metal plate with a gasket or gasket bonded to the bottom of the strut 124 at the interface between one or more catalyst support beds 120 to direct all effluent flow through the catalyst module 116. Alternatively, the sealing plate 154 can be part of one of the struts 124. 7A, one of the struts 124 of the first catalyst support bed 122A may include a plate-like extension that overlaps a portion of the bottom of one of the struts 124 of the second catalyst support bed 122B in a self-sealing arrangement when the second catalyst support bed 122B slides into contact with the first catalyst support bed 122A. A gasket may also be disposed on the plate-like extension and contact the bottom of the strut 124 of the second catalyst support bed 122B to further improve sealing.

[0042] In one embodiment, subsection 100S of convection section 100 further includes an insulating layer 155, which may be provided in the form of multiple insulating blocks that directly contact end struts 124 of catalyst support beds 122A, 122B, access door 117, and access door frame 148. The wall insulation hot surface of insulating layer 155 may face inward toward the operating space of subsection 100S. Insulating layer 155 may serve a dual purpose: retaining heat inside subsection 100S while providing a seal around the edges of catalyst support beds 122A, 122B (i.e., filling the space between support beds 122A, 122B, access door frame 148, and access door 117). In one embodiment, insulating layer 155 is attached to access door 117 such that during operation, both door 117 and insulating layer 155 are removed to provide access to catalyst support beds 122A, 122B and catalyst module 116.

[0043] 7B , the catalyst support beds 122A, 122B may further include crossbars 156 extending laterally between the struts 124 and positioned below the catalyst modules 116 to further support the catalyst modules 116. Specifically, the crossbars 156 may be positioned at regular intervals across the catalyst support beds 122A, 122B to accommodate small spaces between the catalyst modules 116 within the catalyst support beds 122A, 122B to also provide a self-sealing function. In one embodiment, the crossbars are provided in the form of interlocking seal plates 156 that engage the catalyst modules 116 on either side of the spaces between the modules 116 (the spaces are represented by dashed lines 158 in FIG. 7B ). The crossbars 156 or interlocking seal plates 156 further help ensure that all effluent flows pass through the catalyst modules 116.

[0044] In addition to other components described herein, such as sealing plates 154 and crossbars 156, which help ensure that the effluent flow passes through the catalyst module 116, subsection 100S may include other sealing material(s), such as pumpable refractory material and / or ceramic fiber material, to seal gaps, such as between adjacent SCR modules and / or adjacent catalyst support beds 122A, 122B, to further help ensure that the effluent or flue gas passes through, rather than bypasses, the catalyst module 116. As one specific example, such materials may be used to fill gaps between adjacent SCR modules, such as between pillars 102A and 102B and between the upper and lower tubesheets 104.

[0045] FIG. 8 is a cross-sectional view of one end of subsection 100S in the lateral direction, with a different perspective and orientation than FIG. 7B. FIG. 8 provides more detail regarding beam 118, as well as additional features of subsection 100S generally. For example, FIG. 8 shows first flange 136A of beam 118 and rail 138 on first flange 136A in more detail. Beam 118 further includes second flange 136B, which includes guide element 160 extending perpendicular to second flange 136B and in the opposite direction from rail 138 on first flange 136A. Support bar 146 includes slot 162 that interfaces with guide element 160 on second flange 136B of beam 118. Guide element 160 and slot 162 may function similarly to rail 138 on first flange 136A and groove 142 on strut 124, described above. More specifically, slots 162 in the support bar 146 receive and interface with guide elements 160 on the second flange 136B of the beam 118 to assist in sliding and / or guiding the support bar 146 and catalyst support bed 122 ( FIGS. 4A and 6 ) relative to the beam 118. The support bar 146 is not intended to restrict longitudinal displacement of the catalyst support bed 122, but rather may allow for longitudinal thermal expansion during operation. The support bar 146 allows the catalyst support bed 122 to be installed on top of the second flange 136B of the beam 118, while carrying a first gasket 164 to improve sealing and support of the catalyst support bed 122 and catalyst module 116 and distribute loads to the second flange 136B.

[0046] Subsection 100S further includes a first gasket 164 between support bar 146 and strut 124 of one or more catalyst support beds 122, and a second gasket 166 between second flange 136B of beam 118 and the top of tubesheet 104 below beam 118. In one embodiment, second gasket 166 is configured to compress in response to expansion of tubesheet 104 under the operating temperatures of convection section 100 to further improve sealing. Thus, gaskets 164, 166 also help direct effluent flow through catalyst module 116.

[0047] As a result, the disclosed concept allows for the catalyst support structure to be an integral part of the heater's convection section, instead of utilizing a separate, distinct structure for SCR of NOx using a catalyst module, as in known SCR systems, thereby reducing plot space and equipment count. Furthermore, the catalyst support grid structure is designed with the catalyst module installed within a cavity, instead of being positioned on top of the support structure as in known systems. The disclosed concept also allows for self-sealing of the catalyst support structure and installed catalyst module when the catalyst module is placed on the support structure, eliminating the commonly used sealing tape. Furthermore, the disclosed concept allows for loading and unloading of the SCR catalyst module on the lateral side of the convection section along the entire convection length, as opposed to conventional loading or unloading of the catalyst module through the end of the convection section, to achieve the target NOx reduction. While such benefits can be achieved in new installations, they are particularly advantageous for retrofitting existing heaters where SCR was not originally considered in the design. The relatively small space (i.e., less than 460 mm) occupied by the structural frame and catalyst module allows the technology discussed herein to be applied to a wide range of existing equipment. Additionally, utilizing the heater's existing support system significantly reduces the downtime and costs associated with retrofitting a heater to include SCR technology for reduced NOx emissions.

[0048] The concepts of the present disclosure may be particularly useful and advantageous in combination with the devices, systems, and methods described in U.S. Provisional Patent Application No. 63 / 269,754, filed with the U.S. Patent and Trademark Office on March 22, 2022, the entire contents of which are incorporated herein by reference. Additionally, the concepts of the present disclosure may be advantageous for use with any technology for reducing carbon dioxide emissions that may result in increased NOx emissions. Thus, adding or retrofitting technology for carbon dioxide reduction using SCR technology as discussed herein may enable the reduction of both carbon dioxide and NOx emissions in a single design.

[0049] The above physical embodiments can also be provided or implemented as one or more steps of a method for reducing NOx emissions. For example, the method may include, among other things, building a new heater or retrofitting an existing heater by placing a structural frame in the space between tubesheets and sliding a catalyst support bed carrying a catalyst module onto the structural frame. Therefore, methods embodying the present invention are within the scope of this disclosure. While the description herein applies to techniques for reducing NOx emissions, it may also be applied to other techniques, systems, and / or methods, such as those used for CO reduction. In any of these embodiments, the catalyst may be provided in modules, pellets, and / or baskets.

[0050] In the above description, certain specific details are set forth to provide a thorough understanding of various embodiments of the present disclosure. However, those skilled in the art will understand that the present disclosure may be practiced without such specific details. In other instances, well-known structures associated with the technology have not been described in detail to avoid unnecessarily obscuring the description of the embodiments of the present disclosure.

[0051] Certain words and phrases used herein are described below. As used throughout this specification, including the claims, the singular forms "a," "an," and "the" include plural references unless otherwise indicated. Any of the features and elements described herein may be singular, for example, a shell may refer to one shell. The terms "include" and "comprise," and their derivatives, mean inclusion, but are not limited to. The phrases "associated with" and "associated therewith," and their derivatives, may mean including, contained within, interconnected, containing, contained within, connected to or connected with, coupled to or coupled with, capable of communicating with, associated with, interconnected, juxtaposed, adjacent to, affixed to or affixed with, having, having the property of, and the like. Other definitions of certain words and phrases are provided throughout this disclosure.

[0052] The use of ordinal numbers such as first, second, third, etc. does not necessarily convey a sense of ranked order, but rather may only distinguish between multiple instances of acts or similar structures or materials.

[0053] Throughout this specification, claims, and drawings, the following terms have the meanings expressly associated therewith unless the context clearly dictates otherwise. The term "herein" refers to the specification, claims, and drawings associated with the current application. The phrases "in one embodiment," "in another embodiment," "in various embodiments," "in some embodiments," "in other embodiments," and other derivatives thereof refer to one or more features, structures, functions, limitations, or characteristics of the present disclosure and are not limited to the same or different embodiments unless the context clearly dictates otherwise. As used herein, the term "or" is an inclusive "or" operator and is equivalent to the phrases "A or B, or both," or "A or B or C, or any combination thereof," and lists with additional elements are treated similarly. The term "based on" is not exclusive and allows for additional features, functions, aspects, or limitations not described unless the context clearly dictates otherwise.

[0054] Generally, unless otherwise indicated, materials for making the present invention and / or its components may be selected from suitable materials such as composites, ceramics, plastics, metals, polymers, thermoplastics, elastomers, plastic compounds, catalysts, and ammonia compounds, either alone or in any combination.

[0055] For purposes of explanation, the foregoing description uses specific nomenclature and formulas to provide a thorough understanding of the disclosed embodiments. It should be apparent to those skilled in the art that specific details are not required to practice the present invention. The embodiments have been chosen and described to best explain the principles of the disclosed embodiments and their practical application, thereby enabling those skilled in the art to utilize the disclosed embodiments, as well as various embodiments with various modifications as may be suited to the particular use contemplated. Therefore, the foregoing disclosure is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

[0056] The terms "top," "bottom," "upper," "lower," "up," "down," "above," "below," "left," "right," and other similar derivatives take on a common meaning as referring to a direction facing west when facing north in the cardinal orientation scheme, such as when gravity pulls objects downward and to the left. These terms are not limited to the possible orientations explicitly disclosed, implicitly disclosed, or inherently disclosed in this disclosure, and any of the aspects of the embodiments of this disclosure can be positioned in any orientation unless the context clearly dictates otherwise.

[0057] As used herein, the term "substantially" is intended to include normal error ranges or manufacturing tolerances due to slight variations and variations in manufacturing. Unless the context clearly dictates otherwise, relative terms such as "approximately," "substantially," and other derivatives, when used to describe a value, amount, quantity, or dimension, generally refer to a value, amount, quantity, or dimension that is within plus or minus 5% of the stated value, amount, quantity, or dimension. It should be further understood that any specific dimensions of components or features provided herein are for illustrative purposes only with reference to the various embodiments described herein, and as such, including dimensions greater or less than the stated dimension is expressly contemplated by this disclosure unless the context clearly dictates otherwise.

[0058] The various embodiments described above can be combined to provide further embodiments. All U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, and non-patent publications mentioned herein and / or listed in the Application Data Sheets, including U.S. Provisional Patent Application No. 63 / 404,883, filed September 8, 2022, are incorporated herein by reference in their entirety. Aspects of the embodiments can be modified, as needed, to employ concepts from the various patents, applications, and publications to provide still further embodiments.

[0059] These and other changes can be made to the embodiments in light of the above detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments, along with the full range of equivalents to which such claims are entitled. Accordingly, the claims are not limited by this disclosure.

Claims

1. It is a heater, It comprises a convection section, and the convection section is Multiple supports, A plurality of tube sheets bonded to the plurality of supports, A plurality of tubes bonded to the plurality of tube sheets, The space above or below at least one of the plurality of tube sheets, A structural frame in the aforementioned space, wherein the structural frame is Multiple beams coupled to the multiple supports, and A structural frame including a plurality of struts configured to slide along the plurality of beams, Includes a heater.

2. The heater according to claim 1, wherein the plurality of supports are arranged in pairs of supports spaced apart from each other along the longitudinal direction of the convection section, and each pair of supports includes a first support and a second support spaced apart from each other in the lateral direction of the convection section.

3. The heater according to claim 2, wherein the plurality of tube sheets include pairs of tube sheets bonded to a corresponding pair of supports, each pair of tube sheets including a first tube sheet and a second tube sheet, and the space is between the first tube sheet and the second tube sheet.

4. The heater according to claim 1, wherein the plurality of struts include a web and a flange extending perpendicularly from the web.

5. The heater according to claim 1, wherein the structural frame further includes at least one gasket configured to compress in response to the expansion of the corresponding tube sheet among the plurality of tube sheets during operation.

6. The heater according to claim 1, wherein the plurality of struts form a first catalyst support bed that is slidable relative to the plurality of beams, allowing catalysts to be loaded into or removed from the convection section by passing through the lateral surfaces of the convection section.

7. The heater according to claim 1, wherein the plurality of struts form a second catalyst support bed, which is positioned within the space and configured to allow loading or removing the catalyst into the convection section by passing through the opposite lateral side of the convection section.

8. The heater according to claim 7, wherein the plurality of struts of the second catalyst support base include grooves configured to interface with the plurality of beams in order to assist the sliding of the second catalyst support base with respect to the plurality of beams.

9. The heater according to claim 1, further comprising support bars arranged on the plurality of beams to assist the sliding of the plurality of struts.

10. The heater according to claim 7, further comprising a connecting sealing plate between the first catalyst support bed and the second catalyst support bed.

11. The aforementioned structural frame, An access door frame coupled to the plurality of supports on the lateral side of the convection section, The system further includes an access door detachably coupled to the access door frame, The heater according to claim 1, further comprising a heat insulating layer in contact with the end face of the first catalyst support floor and the inner surface of the removable access door.

12. The heater according to claim 1, wherein the structural frame further includes a plurality of brackets coupled to the plurality of supports, each of the plurality of brackets receiving at least a portion of a corresponding beam among the plurality of beams.

13. It is a heater, It comprises a convection section, and the convection section is The space above or below at least one of the multiple tube sheets connected to multiple columns, A structural frame in the aforementioned space, wherein the structural frame is A structural frame comprising a first catalyst support floor, which is removably connected to the plurality of columns and positioned within the space, wherein the first catalyst support floor is slidable relative to the plurality of columns in the lateral direction of the convection section, allowing catalysts to be loaded into or removed from the convection section through at least one lateral side of the convection section, Includes a heater.

14. The heater according to claim 13, further comprising a structural frame connected to the plurality of columns and positioned within the space, wherein the first catalyst support floor is slidable relative to the structural frame.

15. The heater according to claim 14, wherein the structural frame includes a plurality of frame elements, and the first frame element among the plurality of frame elements includes a first guide element and a second guide element.

16. The first catalyst support base includes at least one groove that interfaces with the first guide element of the plurality of frame elements in order to assist the sliding of the first catalyst support base relative to the plurality of columns, The aforementioned heater is To assist in sliding the first catalyst support base against the plurality of columns, a plurality of sliding supports interface with the second guide elements of the plurality of frame elements, The present invention further includes at least one gasket between the plurality of sliding supports and the structural frame, The heater according to claim 15, wherein at least one gasket between the structural frame and the plurality of tube sheets is configured to compress during the operation of the convection section.

17. A frame connected to the plurality of columns on at least one lateral side surface of the convection section, An access door detachably attached to the frame, The heater according to claim 13, further comprising an insulating layer between the access door and the first catalyst support floor.

18. The at least one lateral surface of the convection section is the first lateral surface of the convection section, and the structural frame is A second catalyst support bed, detachably coupled to the plurality of columns and positioned within the space, further comprising a second catalyst support bed slidably relative to the plurality of columns in the lateral direction of the convection section, such that the second catalyst support bed is slidable relative to the plurality of columns in the lateral direction of the convection section, allowing catalysts to be loaded into or removed from the convection section by passing through the second lateral side of the convection section opposite to the first lateral side, The heater according to claim 13, further comprising a sealing plate between the first catalyst support bed and the second catalyst support bed.

19. It is a heater, A convection section including at least one lateral surface, A heater comprising: at least one catalyst support bed that is slidable relative to the convection section so as to allow loading or removing a catalyst into the convection section through at least one lateral surface of the convection section.

20. The at least one catalyst support bed is a first SCR module that is slidable with respect to a first subsection of the convection section, passing through at least one lateral surface of the first subsection, wherein the first subsection has a length less than the entire longitudinal length of the convection section. The aforementioned heater is A second subsection of the convection section having a length less than the entire longitudinal length of the convection section, The present invention further comprises a second SCR module that is slidable relative to the second subsection of the convection section through at least one lateral surface of the second subsection, The heater according to claim 19, wherein the first subsection and the second subsection are separated by the support of the convection section.

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