Selective catalytic reduction catalyst module support system and method of installation

Abstract

The present disclosure relates to a heater that includes a convection section having a column and a tube sheet coupled to the column with a tube received in the tube sheet. The convection section includes a space between the tube plates associated with a corresponding pair of columns. A structural frame is coupled to the columns and positioned in the space to slidably receive one or more catalyst support beds for loading catalyst into or unloading catalyst from the convection section through lateral sides of the convection section of the heater. The structural frame may include beams, struts, skateboards, and other frame elements that assist in supporting the catalyst support bed and enable the catalyst support bed to slide relative to the structural frame.

Description

BACKGROUND OF THE DISCLOSURE Technical Field

[0001] The present disclosure generally relates to selective catalytic reduction and, more specifically but not exclusively, to selective catalytic reduction systems and methods for a fired heater.

[0002] Description of the Prior Art

[0003] It is well known that selective catalytic reduction (“SCR”) of nitrogen oxides (NOx) can reduce NOx emissions. SCR technology has been applied in many industries to meet the more stringent emission standards that have been introduced in response to pollution and climate change. One such industry is the petrochemical processing industry, which typically employs large fired heaters as well as various other process equipment to produce petrochemicals from by-products of the crude oil refining process and other feedstocks. Operation of a fired heater for petrochemical processing generates a variety of emissions, including NOx.

[0004] At high levels, SCR of NOx in a fired heater is carried out by using an SCR catalyst module and controlled ammonia injection within a flue gas temperature window. The SCR reactor is equipped with a catalyst bed for carrying a large mass of catalyst. Some processing systems are newly constructed with conventional SCR technology. However, such conventional SCR designs have many drawbacks. For example, known SCR systems and methods for fired heaters occupy a large amount of space in the processing system, have complex support structures, and access to the space and structure for loading and unloading the catalyst module is limited.

[0005] When new, more stringent NOx emission standards come into effect, it is also well known to retrofit existing systems with SCR technology to reduce NOx emissions. The above-mentioned drawbacks of known SCR technology are particularly severe for existing systems with even more limited retrofit space and that do not have a support structure for SCR improvement. Thus, retrofitting is an expensive process that, among other drawbacks, can include a significant amount of system downtime.

[0006] The prior art has failed to address the above challenges with known SCR technologies. For example, U.S. Patent No. 7,399,458 to Martin et al. (“Martin”) appears to describe a flame device system and method of operating the same, which combines fixed industrial burner technology and a catalyst bed that converts pollutants formed during the combustion of fuel and air in the burner into flue gas that can be emitted into the atmosphere. At a high level, Martin's system and method primarily involve the use of a catalyst bed within the flame device system. However, such an arrangement does not address the NOx emissions contained in the flue gas stream in existing flame heaters. Further, the SCR technology in Martin is directly installed as part of the burner system and is thus generally of limited applicability to flame heaters, including in retrofitting existing systems.

[0007] U.S. Patent No. 7,500,437 to Lefebvre et al. (“Lefebvre”) appears to describe methods and systems for controlling SCR performance in fossil fuel boilers by developing profiles 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 regarding boiler performance variables. These data inputs are then used to develop a desired boiler performance model. Thus, Lefebvre appears to aim at modeling and optimizing the operating parameters for fossil fuel boilers, but this fails to address the deficiencies of the known SCR technologies described above.

[0008] U.S. Patent No. 9,314,739 to Lisberger appears to describe a method and apparatus for denitrifying flue gas containing carbon monoxide and / or gaseous organic substances with at least one catalyst for NOx catalytic reduction and a heat exchanger for heating the flue gas to a reaction temperature of 160°C to 500°C by recovering the waste heat of the denitrified flue gas prior to catalytic reduction. In order to achieve the best possible denitrification of the flue gas while minimizing the required externally supplied energy, it is contemplated in Lisberger that losses associated with heat transfer in the heat exchanger will be compensated for by providing at least one stage of post-combustion regeneration for carbon monoxide and / or gaseous organic substances. Thus, Lisberger appears to aim at reducing NOx emissions through post-combustion regeneration after the SCR stage, but fails to address the challenges of known SCR systems and methods.

[0009] The WIPO published application number WO 2014 / 116929 granted to Novak et al. (“Novak”) appears to describe reducing NOx emissions from a flame heater by burning an air preheater and using a high emissivity coating. In summary, Novak appears to aim to combine air preheating and a high emissivity coating to increase radiation efficiency and then reduce the total combustion amount and the total NOx emissions. Therefore, Novak appears to be generally unrelated to SCR technology.

[0010] The WIPO published application number WO 2010 / 132563 granted to Pfeffer et al. (“Pfeffer”) appears to describe a multi-step system that removes NOx from combustion flue gas via SCR or selective non-catalytic reduction with ammonia or ammonia-forming compounds, then treats it with hydrogen peroxide to remove residual ammonia, and optionally, treats it with an alkaline reagent to reduce residual NOx in the flue gas stream. The lean NOx flue gas stream can also be subjected to desulfurization treatment to remove SOx. However, Pfeffer also fails to address the challenges of the above-known SCR technology.

[0011] The Canadian patent number 2,439,866 granted to McNertney et al. (“McNertney”) appears to describe a passive system for recovering energy and nitrogen oxides from the flue gas generated by a boiler, which employs a specific economizer surface arrangement to ensure that the temperature of the flue gas entering the SCR reactor remains within the required range under a wide range of boiler loads. Such applications of SCR technology to boilers with different loads and varying temperature ranges entering the SCR catalyst bed are different from SCR technology in the stable operation of flame heaters or cracking heaters. In addition, McNertney fails to address the challenges of the above-known SCR technology.

[0012] The U.S. patent publication number 2012 / 0222591 granted to Greenhut et al. (“Greenhut”) appears to describe a method for selective catalytic NOx reduction in a power boiler and a power boiler with selective catalytic NOx reduction. Fuel is burned in the furnace of the boiler and a flue gas stream containing NOx is generated. The flue gas stream is directed from the furnace along the flue gas passage to the chimney. The flue gas stream is cooled in a heat recovery area that includes an economizer section arranged in the flue gas passage. At least a portion of the NOx is reduced to N2 in a NOx catalyst arranged in the flue gas passage downstream of the economizer section. The flue gas is further cooled and heated air is generated in a gas-air heater arranged in the flue gas passage downstream of the economizer section and upstream of the NOx catalyst. Similar to other examples in the above prior art, Greenhut relates to SCR technology for boilers, particularly for power boilers, which fails to recognize the challenges associated with SCR technology for flame heaters.

[0013] Therefore, it would be advantageous to have SCR systems and methods that overcome the deficiencies and drawbacks of known SCR technology. SUMMARY OF THE INVENTION

[0014] The concepts of the present disclosure generally relate to installing an SCR catalyst module in the convective section of a fired heater (such as a steam cracker) where a suitable flue gas temperature window for SCR of NOx is located. The concepts of the present disclosure can be implemented in various forms and can be implemented in industries other than petrochemical processing. Among other benefits, the concepts of the present disclosure enable the catalyst support structure to be an integral part of the convective section of the fired heater, rather than utilizing a separate and distinct structure for SCR of NOx with a catalyst module as in known SCR systems, to reduce floor space and the number of equipment. Further, the catalyst support grid structure is designed with catalyst modules installed in cavities, rather than being located above the support structure as in known systems. The concepts of the present disclosure also enable the catalyst support structure and the installed catalyst modules to be self-sealing, eliminating the commonly used sealing tape when the catalyst modules are placed on top of the support structure. Additionally, the concepts of the present disclosure enable the loading and unloading of SCR catalyst modules along the lateral sides of the convective section over the entire convective length to achieve the target NOx reduction, rather than loading or unloading the catalyst modules through the ends of the convective section as in previous practice.

[0015] For fired heaters designed and constructed when NOx emission standards were less stringent, no consideration was given to the space and structural support for SCR catalyst modules. Therefore, these fired heaters were not designed or equipped with large vertical spaces, access doors, and structural supports for loading and unloading SCR catalyst modules. For example, in existing ethylene cracking heater designs, the convective section is typically designed with multiple coil groups for preheating the process stream as well as boiler feed water and steam. The vertical spacing between two coil groups measured between the centerlines of two adjacent tube rows can be approximately 460 mm. The original purpose of this space was to install sootblowing doors for regular maintenance or to provide mechanical clearances, etc. The concepts of the present disclosure enable such existing heaters and other heaters to be retrofitted with SCR technology to support the SCR catalyst modules by utilizing a structural frame system, to enable the loading and unloading of the SCR catalyst modules, and to create suitable seals to direct all flue gas flows through the catalyst, thereby reducing NOx emissions. Thus, in some non-limiting examples, the loading and unloading of the SCR catalyst modules can be achieved through the lateral sides of the convective section, rather than through the ends of the convective section over the entire length of the convective section in a space with a height of 460 mm or less. Additional benefits and advantages are described elsewhere herein.

[0016] In some non-limiting examples, a flame heater includes a convection device with a plurality of columns or other supports arranged in pairs, each pair being spaced apart from one another along the longitudinal or lengthwise direction of the convection section. The paired columns include a first column and a second column spaced apart from one another in the transverse or widthwise direction of the convection section. A tube sheet is coupled to the columns, wherein paired tube sheets are coupled to corresponding paired columns. The paired tube sheets include a first tube sheet and a second tube sheet stacked along the axial or heightwise direction of the corresponding columns in the convection section. A plurality of tube bundles are coupled to the plurality of tube sheets. The convection section includes a gap or space between the first tube sheet and the second tube sheet in each pair of tube sheets in the axial or heightwise direction of the convection section.

[0017] A structural frame is positioned in the gap to support a first catalyst support bed that is capable of sliding relative to the columns to enable loading or unloading of catalyst 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 plurality of columns and extending across the gap in the transverse direction of the convection section, wherein each of the plurality of beams includes a first flange with a track and a second flange with a guiding element. The first catalyst support bed includes a plurality of struts coupled together, wherein catalyst modules are received in one or more cavities defined by the struts. At least one of the plurality of struts includes a channel that interfaces with the track of the first flange of the corresponding beam of the plurality of beams to enable the first catalyst support bed to slide relative to the plurality of beams. The structural frame further includes a support rod disposed on the second flange of the corresponding beam of the plurality of beams, the support rod including a slot configured to interface with the guiding element of the second flange of the corresponding beam of the plurality of beams to assist in the sliding of the first catalyst support bed.

[0018] At least one lateral side of the convection side may be the first lateral side of the convection section. The structural frame may further include a second catalyst support bed having features similar to the first catalyst support bed to enable loading or unloading of catalyst onto or from the second catalyst support bed through a second lateral side of the convection section opposite the first 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. Further, the convection section includes gaskets between the support rod and the plurality of beams and between the plurality of beams and the corresponding tube sheet of the plurality of tube sheets, and a seal plate between the first catalyst support bed and the second catalyst support bed to achieve a self-seal that guides all flue gas flows through the catalyst modules. In some examples, a thermal insulation layer or thermal insulation block may be provided between the access door and the catalyst support bed. Other features of embodiments of the present disclosure will be described elsewhere. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present disclosure will be more fully understood by reference to the following drawings, which are for illustrative purposes only. In the drawings, like reference numerals always denote like components unless otherwise indicated. The drawings do not depict every aspect of the teachings disclosed herein and do not limit the scope of the claims.

[0020] Figure 1 is an isometric view of a convective section of a flame heater according to an embodiment of the present disclosure.

[0021] Figure 2 is Figure 1 an isometric view of a sub-section of the convective section, showing a first catalyst support bed and a second catalyst support bed.

[0022] Figure 3 is Figure 2 an isometric view of the structural frame of the sub-section.

[0023] Figure 4A and Figure 4B is Figure 3 a detailed view of one end of the structural frame, showing additional features of the structural frame.

[0024] Figure 5 is Figure 2 a detailed view of the lateral side of the sub-section, showing a frame for a removable access door.

[0025] Figure 6 is Figure 2 an isometric view of a sub-section, showing the sliding operation of the first catalyst support bed.

[0026] Figure 7A and Figure 7B is Figure 2 a detailed view of one end of the sub-section, showing a seal or gasket between the first catalyst support bed and the second catalyst support bed.

[0027] Figure 8 is Figure 2 a detailed view of one end of the sub-section, showing a seal or gasket between the structural frame and the convective section. Detailed Description

[0028] Those of ordinary skill in the relevant art will understand that the present disclosure is illustrative only and not limiting in any way. Other embodiments of the systems and methods of the present disclosure will be readily apparent to those skilled in the art with the assistance of the present disclosure.

[0029] Each of the features and teachings disclosed herein can be used alone or in combination with other features and teachings to provide SCR devices, systems, and methods. Representative examples that utilize many of these additional features and teachings, either alone or in combination, are described in further detail with reference to the accompanying drawings. This detailed description is only intended to teach those skilled in the art further details for practicing 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 may not be necessary for practicing the teachings in the broadest sense but are merely taught to describe particularly representative examples.

[0030] In addition, the various features of the representative examples and the dependent claims can be combined in ways not specifically and explicitly recited to provide additional useful embodiments of the present teachings. It is also expressly noted that for the purposes of the original disclosure and for the purpose of limiting the claimed subject matter, all value ranges or indications of entity groups disclose each possible intermediate value or intermediate entity. It is also expressly noted that the dimensions and shapes of the components shown in the drawings are designed to aid in understanding how to practice the present teachings but are not intended to limit the dimensions and shapes shown in the examples in some embodiments. In some embodiments, the dimensions and shapes of the components shown in the drawings are drawn to scale and are intended to limit the dimensions and shapes of the components.

[0031] As will be described in more detail below, the concepts of the present disclosure generally relate to SCR technology provided in the form factor of a structural frame that can be self-supporting and attached to an existing column of a convective section of a heater. Such an arrangement can allow thermal expansion movement in both the vertical and horizontal directions while also providing access from the lateral sides of the convective section to the catalyst blocks for loading and unloading SCR catalyst modules.

[0032] The concepts of the present disclosure are particularly useful for reducing NOx emissions from existing flame heaters, which include but are not limited to existing steam crackers without significant structural modifications. In other words, the concepts of the present disclosure facilitate retrofitting existing process technologies and provide a lower-cost method of installing SCR catalyst modules to reduce NOx emissions in existing facilities. The technology can also be installed as a new design option, thereby providing partial NOx emissions reduction at a lower cost without the need for major structural installation of catalyst modules as in current systems.

[0033] In some non - limiting examples, methods for increasing the radiant efficiency of existing furnaces are disclosed, particularly but not exclusively, for steam cracking furnaces used in the production of bulk chemicals such as ethylene, propylene, butadiene, and other chemicals, where air, fuel, or both are pre - heated using energy recovered from flue gas. Such pre - heated air and / or fuel mixtures would result in higher NOx in the flue gas, and the concepts of the present disclosure assist in reducing such NOx emissions.

[0034] While the present disclosure will continue to describe certain examples of techniques applied to the convection section of a steam cracker, which may be particularly advantageous for petrochemical processing and refining, it should be understood that the concepts of the present disclosure can be applied to a wide range of technologies and industries. Specifically, the concepts of the present disclosure can be equally applied to any industry or technology that utilizes a fired heater, such as at least in the marine, refinery, power, petrochemical, or paper and food industries, among others. Further, the concepts of the present disclosure can be applied to technologies and industries where reducing NOx emissions is generally beneficial. Thus, the concepts of the present disclosure are not limited to the examples provided below.

[0035] Figure 1 One or more embodiments of the convection section 100 of a fired heater according to the present disclosure are shown. For the sake of clearly illustrating the concepts of the present disclosure, the convection section 100 is shown without additional components of the fired heater, such as at least the casing. The convection section 100 is arranged in Figure 1 such that it has a length (i.e., the maximum dimension) of the convection section 100 extending in the longitudinal direction, a width (i.e., into and out of the page) extending in the transverse direction, and a height (i.e., from bottom to top in accordance with the normal meaning of these terms) in the axial direction. Unless otherwise specified herein, the directional indicators "longitudinal", "transverse", and "axial" only provide a reference frame for interpreting the concepts of the present disclosure and do not limit the present disclosure to a particular configuration. For example, while in Figure 1 the convection section 100 is generally horizontally arranged and the length direction extends in the longitudinal direction, in some embodiments the convection section 100 can also be vertically arranged and the length direction extends in the axial direction.

[0036] Among other possibilities, the convective section 100 can be approximately 15 meters long by 3 meters wide and include a support system that includes a plurality of columns 102 (which may also be referred to herein as supports 102), a plurality of tube sheets 104 coupled to the plurality of columns 102, and a plurality of tubes or tube bundles coupled to the plurality of tube sheets 104. In embodiments of the present disclosure for retrofitting a convective section with SCR technology in accordance with the concepts herein, the support system including columns 102, tube sheets 104, and tubes 106 can be part of an existing heater structure. Alternatively, such a support system can be constructed as part of the installation of a new system. The plurality of columns 102 are arranged in pairs of columns 102P, where the pairs of columns 102P are spaced apart from each other along the longitudinal direction of the convective section. Each pair of columns 102P includes a first column 102A and a second column 102B, where in each pair of columns 102P, the first column 102A is spaced apart from the second column 102B in the transverse direction.

[0037] The plurality of tube sheets 104 are coupled to the plurality of columns 102 and include pairs of tube sheets 104P coupled to corresponding pairs of columns 102P. In one embodiment, the pairs of tube sheets 104P are arranged axially along the pairs of columns 102P, where each pair of tube sheets 104P includes a first tube sheet 104A and a second tube sheet 104B. In each pair of tube sheets 104P, the first tube sheet 104A can be the upper tube sheet 104A, while the second tube sheet 104B can be the lower tube sheet 104B, or vice versa. Thus, in some non-limiting examples, the first tube sheet 104A can be located above the second tube sheet 104B in the axial direction. The plurality of tubes 106 can be arranged in a bundle coupled to the plurality of tube sheets 104. Figure 1 Only one tube 106 coupled to one of the first tube sheets in the first tube sheet 104A and one of the second tube sheets in the second tube sheet 104B is shown, where the tube 106 is schematically shown in dashed lines to avoid obscuring the features of the present disclosure, but it should be understood that the tube 106 can include a significantly greater number of tubes 106 or tube bundles 106 than those shown, where the tubes 106 extend substantially along all or at least most of the length or longitudinal direction of the convective section 100 under the support provided by the tube sheets 104. Further, in some embodiments, the tube sheets 104 can be replaced with tube supports. Figure 1

[0038] Figure 1 The above-described arrangement of the tube sheets 104 and tubes 106 in the support system of the convective section 100 creates a space or gap 108 between the tubes 106 in the axial direction. The gap 108 between the tubes 106 can be greater than the space between the outer frames of the tube sheets 104 to enable the installation of larger catalyst modules and improve SCR performance and NOx reduction while also utilizing the maximum amount of available space. The gap 108 is Figure 1occupied by the structural framework of the SCR module therein, which structural framework is further described elsewhere, where the gap 108 and the additional tube 106 are Figure 5 more clearly shown in. In some embodiments, the vertical or axial distance between the two tube bundles above and below the gap 108 is measured between the centerlines of the tube rows adjacent to the gap 108 to be about 460 mm, such as Figure 5 those shown. Thus, in some embodiments, the distance of the gap 108 in the axial direction can be about 460 mm, or can be as small as about 300 mm or 200 mm in a further non-limiting example of a convection section with a different configuration. The arrangement of the support system of the convection section 100 defines a sub-section 100S between the pair of columns 102P and the pair of tube sheets 104P. As Figure 1 shown, the convection section 100 includes at least 6 sub-sections 100S, but the present disclosure is not limited thereto. The convection section 100 also includes end faces 110 at the opposite longitudinal ends of the convection section 100, such that the length of the convection section 100 can be defined between the end faces 110. The lateral sides 112 of the convection section 100 extend between the end faces 110, where the lateral sides 112 generally refer to Figure 1 the front side and the rear side in the orientation of, and according to the ordinary meaning of "front" and "rear".

[0039] In a typical convective section known in the art, the vertical space between tube sheets may allow for the installation of sootblower doors for performing regular maintenance or provide mechanical clearance. Further, in conventional instances, catalyst modules for SCR technology are typically loaded and unloaded through the ends of the convective section (i.e., end face 110), where a typical convective section includes a single catalyst support bed spanning the entire longitudinal length of the convective section (i.e., a single bed between end faces 110). Among other drawbacks, such an arrangement inherently makes it more difficult to access the catalyst modules for loading and unloading (and other options), and particularly for catalyst modules towards the center of the convective section. Additionally, the loading and unloading space for the catalyst modules at the end faces of a typical convective section limits the height or size of the catalyst modules to the space between the tube sheets, which also limits the overall effectiveness of SCR for NOx reduction. The present disclosure contemplates using a gap 108 greater than the space between tube sheets 104 for installing SCR catalyst modules to overcome the above-mentioned deficiencies of the prior art regarding lack of space, structural supports, and access to the modules when constructing a new convective section or when retrofitting an existing convective section. As will be described in more detail below, the concept of the present disclosure enables the loading and unloading of SCR catalyst modules through the lateral sides 112 of the convective section, rather than loading and unloading around the end faces 110 as is typical in the art, which allows larger SCR catalyst modules to be loaded into and unloaded from the system, and also improves the unloading or loading operations, while enabling more effective retrofitting of existing systems and maximizing the available space, as well as other benefits described herein. Additionally, the concept of the present disclosure does not rely on a single catalyst support bed for the entire longitudinal length of the convective 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 different and separate sub-section 100S of the convective section 100 to improve the loading and unloading operations and other benefits. In other words, the concept of the present disclosure provides an SCR module that can carry one or more catalyst modules in each sub-section of one or more sub-sections 100S of the convective section 100, where the sub-section 100S is less than the entire longitudinal length of the convective section to provide the benefits described herein. Thus, the concept of the present disclosure provides multiple independent and parallel sections, each of which includes a corresponding SCR module (or catalyst support bed) that can be installed from the lateral side of the corresponding section rather than from the end faces of the entire convective section. Further, the concept of the present disclosure provides various seals for guiding all flue gas flows through the catalyst blocks. Thus, the concept of the present disclosure enables the loading and unloading of catalyst modules through the lateral sides 112 of the convective section 100 and in a much smaller space (such as gap 108) than conventional SCR technology, such as a space or gap having a height of 460 mm or less in some embodiments.These concepts can be implemented via embodiments of a structural framework coupled to a plurality of columns 102, as described in further detail below.

[0040] Figure 2 A representative sub-section 100S of the convective section 100 is shown in more detail, and Figure 3 a representative sub-section 100S without a catalyst module is shown. As described above, each sub-section 100S may be defined between a consecutive pair of columns 102 and tube sheets 104 in the convective section 100. Further, unless otherwise specified herein, each sub-section 100S may have the same or similar characteristics. Referring to Figure 2 and Figure 3 , the sub-section 100S includes a structural framework 114 coupled to the column 102. The structural framework 114 is configured to support one or more catalyst modules 116. The catalyst module 116 may have dimensions and a shape that are received within the gaps or spaces 108 between the tubes 106 without interfering with the tubes 106 ( Figure 1 ). For example, in some embodiments, the height of the module 116 in the axial direction may be less than 460 mm. In one embodiment, the heating surface (or tubes 106) may be rearranged above and / or below the structural framework 114 to allow the installation of a catalyst module 116 having a height greater than 460 mm within the gap 108. Or, in other words, by rearranging the tubes around the gap 108, the space or gap 108 may be greater than 460 mm. Increasing the available space and installing a larger catalyst module 116 will increase the residence time of the effluent stream passing through the catalyst module 116 and thus increase NOx reduction to meet NOx emission standards. In some embodiments, the gap or space 108 may thus have a height greater than 460 mm in the axial direction, such as 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm or greater.

[0041] In Figure 2 the non-limiting example shown, there are eight catalyst modules 116 arranged side by side and received on the structural framework 114. Specifically, the catalyst modules 116 may be arranged in two rows in the longitudinal direction, with four catalyst modules 116 in each row. Other configurations are possible and contemplated herein, such as three or more rows of catalyst modules 116, or a single row and one catalyst module 116 in the row in the simplest arrangement. The catalyst modules 116 may be loaded or unloaded via removable access doors 117 through at least one lateral side 112. The access doors 117 may include a single door or a number of doors coupled together to allow selective access to portions of the catalyst module 116 or to assist in manipulating the doors 117 during removal.

[0042] Figure 3Sub-section 100S without the catalyst module 116 is shown to provide more details regarding aspects of the structural frame 114. Continuing reference is made to Figure 2 , the structural frame 114 includes a plurality of beams 118 coupled to a plurality of columns 102. In one embodiment, the structural frame 114 may include one beam 118 coupled to a corresponding pair of columns 102P at each end of the sub-section 100S, wherein each beam 118 extends transversely through the gap 108. In one embodiment, the beam 118 may be at least partially received in brackets 120 coupled to separate columns 102 and is described in more detail below. One or more catalyst support beds 122 are removably coupled to the plurality of beams 118 and positioned within the 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 the catalyst module 116 through at least one lateral side 112 of the convection section 100.

[0043] In one embodiment, each sub-section 100S of the convection section 100 includes two catalyst support beds 122A, 122B adjacent to each other within the gap or space 108. The drawings show two catalyst support beds in each sub-section 100S as illustrative and non-limiting examples of the concepts of the present disclosure. In some embodiments, each sub-section 100S may include three or more catalyst support beds for a relatively wide convection section in the transverse direction, or only one bed for a relatively narrow convection section in the transverse direction. Each catalyst support bed 122 may receive one or more catalyst modules 116, such as a row of catalyst modules 116 arranged in the longitudinal direction and described by way of non-limiting example with reference to Figure 2 . Thus, the catalyst module 116 can be loaded and unloaded by sliding the catalyst support beds 122A, 122B relative to the beams 118 positioned at the opposite longitudinal ends of the catalyst support beds 122A, 122B through the front lateral side and / or the rear lateral side 112 on opposite sides of the convection section 100. Each catalyst support bed 122 may each include a plurality of struts 124 extending between consecutive beams 118 to receive and support the catalyst module 116 within the structural frame 114.

[0044] Figure 4A and Figure 4B is a detailed view of one longitudinal end of the sub-section 100S. Starting from Figure 4A , each of the struts 124 in one or more catalyst support beds 122 may include a generally flat and planar web or sidewall 128A extending in the longitudinal direction and a flange 128B extending perpendicularly (i.e., in the transverse direction) from the bottom of the web 128A into the receiving space 126. The flange 128B may support the bottom surface of the catalyst module 116 ( Figure 3) At the same time, the weight of the catalyst module 116 is also distributed onto the web 128A and throughout the structural frame 114 and the support system of the convective section 100. Further, Figure 4A Illustrated is a case where the sub-section 100S includes two catalyst support beds 122, and the struts 124 of each bed can be positioned adjacent to each other, or in some cases, in contact with each other along the longitudinal centerline passing through the sub-section 100S. Such an arrangement of the struts 124 aids in providing a seal between the catalyst support beds 122 and other aspects of the sub-section 100S to ensure that all flue gas flows through the catalyst module 116.

[0045] Figure 4A Additional details regarding the brackets 120 are also provided. The brackets 120 can be directly coupled to the respective columns in the columns 102 and are configured to receive at least a portion of a corresponding one of the plurality of beams 118. In one embodiment, there are two brackets 120 coupled to each column 102 above and below each beam 118. Each bracket 120 can include a channel 130 formed by spaced sidewalls of the bracket 120 that receives a portion of the web 132 of the beam 118, such as an extension of the web 132 of the beam 118 in the axial direction. The brackets 120 can generally have an "L shape", where the channel 130 is formed in the first extension of the "L", and the second extension 134 of the "L" is perpendicular to the first extension and is welded to the column 102 to provide a flange extension that supports the sidewalls of the bracket 120 defining the channel 130. In one embodiment, the bracket 120 axially located above the beam 118 is structured to axially align the beam 118 and limit any longitudinal displacement of the beam 118. However, instead of being axially coupled to the bracket 120 above the beam 118, the beam 118 can freely slide axially within the bracket 120 above the beam 118 (i.e., without any restrictions in any direction) to allow for thermal expansion during operation. The bracket 120 axially located below the beam 118 is structured to provide load-bearing support for the beam 118, as well as axially align the beam 118 and limit longitudinal displacement. Thus, the beam 118 can freely slide in the longitudinal, lateral, and axial directions within the upper bracket 120 to allow for thermal expansion during operation, but downward axial displacement is restricted by the lower bracket 120 such that thermal expansion during operation occurs in the upward axial direction (i.e., vertically upward).

[0046] Turning to Figure 4B , the plurality of beams 118 includes those that generally extend axially through the gap 108 ( Figure 3) the web 132, the first flange 136A and the second flange 136B. Each of the flanges 136A, 136B can be normal to the web 118, which means that the flanges 136A, 136B are perpendicular to the web 132 of the beam 118 and extend in the longitudinal direction. The first flange 136A can be an upper flange that includes a track 138 that extends normal to or perpendicular 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 can include longitudinal ends 140 that include channels 142 that interface with the tracks 138 of the first flanges 136A of the plurality of beams 118 to assist in guiding the catalyst support bed 122 relative to the beams 118 and columns 102 during sliding operations and / or loading or unloading operations. The track 138 is received in the channel 142 at the end 140 of the strut 124, where the channel 142 also defines a hook 144 at the end 140 of the strut 124 that extends to the opposite side of the track 138 of the first flange 136A facing the web 132 of the beam 118. Thus, the top of each of the struts 124 of the catalyst support bed 122 can be guided by the first flange 136A of the beam 118. In some embodiments, the track 138 of the first flange 136A and the channel 142 of the end 140 of the strut 124 limit the movement of the catalyst support bed 122 in the longitudinal direction while also allowing thermal expansion in at least one direction (i.e., the longitudinal direction and / or the axial direction) and assisting in aligning and sliding the catalyst support bed 122 relative to the beam 118. The bottom of the strut 124 can be disposed on a support rod 146 that interfaces with the second flange 136B of the beam 118, as described in more detail below.

[0047] Figure 5 Shows one of the transverse sides 112 of the sub-section 100S. Specifically, Figure 5 is provided to show details of the access door frame 148. The access door frame 148 includes a plurality of frame elements 150 that extend in the longitudinal and axial directions at the transverse side 112 of the sub-section 100S (and generally the convection section 100) to define an access opening 152 through which the catalyst module 116 can be loaded into or unloaded from the sub-section 100S, or both. The access door 117 ( Figure 2 ) is removably coupled to the access door frame 148 and, in some non-limiting examples, to each other to selectively provide access to the catalyst module 116 via removal of the door 117, or to selectively cover and seal the access opening 150. Each of the frame elements 150 can be "L"-shaped to provide for receiving the door 117 ( Figure 2) and fasten the door 117 to the flange of the frame element 150 using fasteners. In one embodiment, the frame element 150 is coupled to a plurality of columns 102 using fasteners. The access door frame 148 can also be welded to a convection module outer panel (not shown) that is coupled to the columns 102.

[0048] Figure 6 The sliding operation of one of the catalyst support beds 122B in the catalyst support bed is shown. The support rods 146 can include a plurality of support rods 146, with at least one support rod 146 associated with each beam 118. The support rods 146 are configured to slide on the second flange 136B of the beam 118, as Figure 6 conceptually shown. In operation, the support rods 146 can first be placed on the second flange 136B of the beam 118, where the catalyst support beds 122A, 122B are initially supported by the support rods 146 at the bottom. Then, the support rods 146 and the catalyst support beds 122A, 122B slide through the access opening 152 in the access door frame 148 in the corresponding lateral side 112 of the sub-section 100S (or the convection section 100). Figure 6 Further shown, in some embodiments, the struts 124 that support the catalyst module 116 may not include struts across the lateral end faces of the catalyst module 116, but rather the module 116 can be self-supporting in place in the catalyst support beds 122A, 122B, or can be coupled to seals with each other, or both.

[0049] Figure 7A and Figure 7B is a cross-sectional view of one end of the sub-section 100S. Specifically, Figure 7A is a cross-sectional view in the longitudinal direction, and Figure 7B is a cross-sectional view in the lateral direction. Starting from Figure 7A , the struts 124 of one or more catalyst support beds 122 can be joined together with a sealing plate 154. The sealing plate 154 can be provided in the form factor of a gasket or a metal plate with a gasket, which is coupled to the bottom of the struts 124 at the junction between one or more catalyst support beds 120 to direct all the effluent flow through the catalyst module 116. Alternatively, the sealing plate 154 can be a part of one of the struts 124. For example, as Figure 7A shown, one of the struts 124 of the first catalyst support bed 122A can include a plate-like extension that overlaps a part 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 is slid into contact with the first catalyst support table 122A. A gasket can also be provided on the plate-like extension and contact the bottom of the struts 124 of the second catalyst support bed 122B to further improve the seal.

[0050] In one embodiment, the sub-section 100S of the convection section 100 further includes a thermal insulation layer 155, which can be provided in the form factor of a plurality of thermal insulation blocks that are in direct contact with the end struts 124 of the catalyst support beds 122A, 122B, the access door 117, and the access door frame 148. The heat-insulating hot surface of the thermal insulation layer 155 can face inward towards the operating space of the sub-section 100S. The thermal insulation layer 155 can serve a dual purpose, namely providing a seal around the edges of the catalyst support beds 122A, 122B (i.e., filling the space between the support beds 122A, 122B, the access door frame 148, and the access door 117), while also retaining the heat inside the sub-section 100S. In one embodiment, the thermal insulation layer 155 is attached to the access door 117 such that during operation, the door 117 and the thermal insulation layer 155 are removed together to provide access to the catalyst support beds 122A, 122B, and the catalyst module 116.

[0051] Turning Figure 7B , the catalyst support beds 122A, 122B may further include crossbars 156, which extend laterally between the struts 124 and are positioned below the catalyst module 116 to further support the catalyst module 116. Specifically, the crossbars 156 can be positioned at regular intervals across the catalyst support beds 122A, 122B, which correspond to the small spaces between the catalyst modules 116 in the catalyst support beds 122A, 122B, so as to also provide a self-sealing function. In one embodiment, the crossbars are provided in the form factor of interlocking seal plates 156, which engage the catalyst module 116 on either side of the space between the modules 116 (the space is Figure 7B represented by the dashed line 158 in). The crossbars 156 or the interlocking seal plates 156 further assist in ensuring that all the effluent streams pass through the catalyst module 116.

[0052] In addition to other components (such as the seal plate 154 and the crossbars 156) described herein that assist in ensuring that the effluent streams pass through the catalyst module 116, the sub-section 100S may further include other sealing materials, such as pumpable refractory materials and / or ceramic fiber materials, to seal the gaps between adjacent SCR modules and / or adjacent catalyst support beds 122A, 122B, to further assist in ensuring that the effluent or flue gas passes through the catalyst module 116 rather than bypassing them. As a specific example, such materials can be used to fill the gaps between adjacent SCR modules, such as the gaps between the columns 102A and 102B and between the upper tube sheet and the lower tube sheet 104.

[0053] Figure 8 is a cross-sectional view of one end of the sub-section 100S in the lateral direction shown from a different viewpoint and orientation. Figure 7B Figure 8 ​More details regarding the beam 118 and additional features of the sub-section 100S in general are provided. For example, Figure 8 The first flange 136A and the track 138 on the first flange 136A of the beam 118 are shown in more detail. The beam 118 further includes a second flange 136B, wherein the second flange 136B includes a guiding element 160 that is normal or perpendicular to the second flange 136B and extends in a direction opposite to the track 138 of the first flange 136A. The support rod 146 includes a slot 162 that interfaces with the guiding element 160 on the second flange 136B of the beam 118. The functions of the guiding element 160 and the slot 162 may be similar to those of the track 138 of the first flange 136A and the channel 142 of the support post 124 described above. More specifically, the slot 162 of the support rod 146 receives and interfaces with the guiding element 160 on the second flange 136B of the beam 118 to assist in sliding and / or guiding the support rod 146 and the catalyst support bed 122 relative to the beam 118 ( Figure 4A and Figure 6 ). The support rod 146 may not be intended to limit the longitudinal displacement of the catalyst support bed 122, but rather to allow for thermal expansion in the longitudinal direction during operation. The support rod 146 allows the catalyst support bed 122 to be mounted on top of the second flange 136B of the beam 118 while also carrying a first gasket 164 to improve sealing and support the load of the catalyst support bed 122 and the catalyst module 116, and distribute the load to the second flange 136B.

[0054] The sub-section 100S further includes a first gasket 164 between the support rod 146 and the support post 124 of one or more catalyst support beds 122, and a second gasket 166 between the top of the second flange 136B of the beam 118 and the top of the tube sheet 104 below the beam 118. In one embodiment, the second gasket 166 is configured to be compressed in response to the expansion of the tube sheet 104 at the operating temperature of the convection section 100 to further improve the seal. Thus, the gaskets 164, 166 also assist in guiding the effluent flow through the catalyst module 116.

[0055] Accordingly, the concepts of the present disclosure enable a catalyst support structure to be an integral part of the convective section of a flame heater, rather than utilizing a separate and distinct structure for SCR of NOx with catalyst modules as in known SCR systems, to reduce floor space and the number of devices. Further, the catalyst support grid structure is designed with catalyst modules installed in cavities, rather than being located above the support structure as in known systems. The concepts of the present disclosure also enable the catalyst support structure and the installed catalyst modules to be self-sealing, eliminating the need for sealing bands commonly used when catalyst modules are placed on top of the support structure. Additionally, the concepts of the present disclosure enable the SCR catalyst modules to be loaded and unloaded along the lateral sides of the convective section over the entire convective length to achieve the target NOx reduction, rather than loading or unloading the catalyst modules through the ends of the convective section as in previous practices. Such benefits can be achieved with new installations, but are particularly advantageous for retrofitting existing heaters, as SCR was not initially considered in the design. The space occupied by the structural frame and the catalyst modules is relatively small (i.e., less than 460 mm), enabling the technologies discussed herein to be applied to a wide range of existing equipment. Additionally, the use of the existing support system of the heater significantly reduces the downtime and cost associated with retrofitting the heater to include SCR technology for reducing NOx emissions.

[0056] 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 on March 22, 2022, with the United States Patent and Trademark Office, the entire content of which is incorporated herein by reference. Additionally, the concepts of the present disclosure may be advantageous for use with any technology for reducing carbon dioxide emissions, which would thus increase NOx emissions. Accordingly, adding or retrofitting a technology for reducing carbon dioxide through the SCR technology discussed herein may enable both carbon dioxide emissions and NOx emissions to be reduced in a single design.

[0057] The physical embodiments described above may also be provided or practiced as one or more steps of a method for reducing NOx emissions. For example, the method may include constructing a new heater or retrofitting an existing heater by placing a structural frame in the space between tube sheets, and sliding a catalyst support bed carrying catalyst modules into the structural frame, among other steps. Accordingly, practicing the method of the present invention is included within the scope of the present disclosure. While the description herein is applicable to technologies for reducing NOx emissions, it may also be applicable to other technologies, systems, and / or methods, such as those for CO reduction. In any of these embodiments, the catalyst may be provided in the form of modules, pellets, and / or baskets.

[0058] In the foregoing description, certain specific details have been set forth in order to provide a thorough understanding of the various embodiments of the present disclosure. However, one of ordinary skill in the art will understand that the present disclosure may be practiced without these specific details. In other instances, well-known structures associated with the technology have not been described in detail in order to avoid unnecessarily obscuring the description of the embodiments of the present disclosure.

[0059] Certain words and phrases used in this specification are set forth below. Unless otherwise indicated, as used throughout this document (including the claims), the singular forms "a", "an", and "the" include plural references. Any feature and element of the features and elements described herein may be singular, e.g., a housing may refer to one housing. The terms "comprising" and "including" and their derivatives mean including but not limited to. The phrases "associated with" and "associated therewith" and their derivatives may mean: including, being included within, interconnected with, containing, being contained within, connected to or connected with, coupled to or coupled with, communicable with, cooperating with, interleaved, juxtaposed, adjacent, being bound to or bound with, having, having the characteristics of, and so on. Other definitions of certain words and phrases are provided throughout the present disclosure.

[0060] The use of ordinal numbers such as first, second, third, etc. does not necessarily imply a sense of order of ranking, but may only distinguish multiple instances of an action or similar structure or material.

[0061] Throughout this specification, the claims, and the drawings, unless the context clearly dictates otherwise, the following terms have the meanings expressly associated herein. The term "herein" refers to the specification, the claims, and the drawings associated with this application. The phrases "in one embodiment", "in another embodiment", "in various embodiments", "in some embodiments", "in other embodiments", and their other derivatives refer to one or more features, structures, functions, limitations, or features of the present disclosure that 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 phrase "A or B, or both" or "A or B or C, or any combination thereof", and a list with additional elements is 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.

[0062] In general, unless otherwise specified, the materials used to manufacture the present invention and / or its components may be selected from suitable materials such as composite materials, ceramics, plastics, metals, polymers, thermoplastics, elastomers, plastic compounds, catalysts, and ammonia compounds, etc., either individually or in any combination.

[0063] For purposes of explanation, the foregoing description uses specific terms and formulas to provide a thorough understanding of the disclosed embodiments. It will be apparent to those skilled in the art that practicing the present invention does not require specific details. The embodiments have been selected and described in order to best explain the principles of the disclosed embodiments and their practical applications, thereby enabling other skilled persons in the art to utilize the disclosed embodiments and various embodiments with various modifications suitable for the particular purposes contemplated. Accordingly, 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.

[0064] The terms “top,” “bottom,” “upper,” “lower,” “above,” “below,” “over,” “under,” “left,” “right,” and other similar derivatives have their common meaning as direction or position indicators, such as, for example, gravity pulls an object downward and left refers to the direction west when facing north in a basic direction scheme. These terms do not limit the possible orientations that are explicitly, implicitly, or inherently disclosed in the present disclosure, and unless the context otherwise clearly indicates, any aspect of the embodiments of the present disclosure can be arranged in any orientation.

[0065] As used herein, the term “substantially” is interpreted to include the ordinary error range or manufacturing tolerances resulting from minor differences and variations in manufacturing. Unless the context clearly dictates otherwise, relative terms such as “about,” “substantially,” and other derivatives, when used to describe a value, quantity, amount, or dimension, generally refer to a value, quantity, amount, or dimension within plus or minus 5% of the specified value, quantity, amount, or dimension. It should be further understood that any specific dimensions provided herein for components or features are for illustrative purposes only with reference to the various embodiments described herein, and thus, unless the context otherwise clearly dictates, the present disclosure expressly contemplates dimensions greater than or less than the stated dimensions.

[0066] The various embodiments described above can be combined to provide additional embodiments. All U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, and non-patent publications cited in this specification and / or listed in the application data sheet, including U.S. Provisional Patent Application No. 63 / 404,883, filed on September 8, 2022, are hereby incorporated by reference in their entirety. Aspects of the embodiments may be modified, if necessary, to employ the concepts of various patents, applications, and publications to provide yet further additional embodiments.

[0067] In view of the foregoing detailed description, these and other changes may be made to the embodiments. In general, in the following claims, the terms used should not be construed as limiting the claims to the specific embodiments disclosed in this specification and the claims, but should be construed to include all possible embodiments and the full scope of equivalents to which the ownership of this claim is entitled. Accordingly, the claims are not limited by the present disclosure.

Claims

1. A heater, comprising: a convection section, comprising: a plurality of columns arranged in pairs of columns spaced apart from each other in the longitudinal direction of the convection section, and the pairs of columns comprising a first column and a second column spaced apart from each other in the transverse direction of the convection section; a plurality of tube sheets coupled to the plurality of columns, including pairs of tube sheets coupled to corresponding pairs of columns, each of the pairs of tube sheets comprising a first tube sheet and a second tube sheet; a plurality of tube bundles coupled to the plurality of tube sheets; a gap located between the first tube sheet and the second tube sheet in each pair of tube sheets; and a structural frame located in the gap, comprising: a plurality of beams coupled to corresponding pairs of the plurality of columns and extending through the gap; and a first catalyst support bed removably coupled to the plurality of beams and positioned in the gap, the first catalyst support bed being capable of sliding relative to the plurality of beams to enable loading or unloading of catalyst into or from the convection section through at least one lateral side of the convection section.

2. The heater according to claim 1, wherein a first beam of the plurality of beams comprises a first flange with a track and a second flange with a guiding element.

3. The heater according to claim 2, wherein the first flange and the second flange are each normal to a web of the first beam of the plurality of beams.

4. The heater according to claim 3, wherein the track is normal to the first flange and extends from the first flange in a first direction, and the guiding element is normal to the second flange and extends from the second flange in a second direction opposite to the first direction.

5. The heater according to claim 2, wherein the first catalyst support bed comprises a plurality of struts coupled together, and a first strut of the plurality of struts comprises a channel that interfaces with the track of the first flange of the first beam of the plurality of beams to assist in sliding of the first catalyst support bed relative to the plurality of beams.

6. The heater according to claim 5, wherein the structural frame further comprises a support rod disposed on the second flange of the first beam of the plurality of beams and comprising a slot configured to interface with the guiding element of the second flange of the first beam of the plurality of beams to assist in sliding of the first catalyst support bed relative to the plurality of beams.

7. The heater according to claim 6, wherein the support rod is configured to prevent movement of the first catalyst support bed in the longitudinal direction of the convection section.

8. The heater according to claim 5, wherein the convection section further comprises a first gasket located between the support rod and at least one of the plurality of struts of the first catalyst support bed, and a second gasket located between the second flange of the first beam of the plurality of beams and at least the first tube sheet of the plurality of tube sheets.

9. The heater according to claim 8, wherein the second gasket is configured to be compressed in response to the expansion of at least a corresponding one of the plurality of tube sheets at the operating temperature of the convection section.

10. The heater according to claim 1, wherein the structural frame includes the first catalyst support bed, and the first catalyst support bed is slidable to enable loading or unloading of the catalyst into or from the convection section through a first lateral side of the convection section. The heater further includes: A second catalyst support bed positioned in the gap and configured to enable loading or unloading of the catalyst into or from the convection section through a second lateral side of the convection section opposite the first lateral side.

11. The heater according to claim 10, wherein each of the plurality of beams includes a first flange with a track and a second flange with a guiding element, and the second catalyst support bed includes a plurality of struts joined together. A first strut of the plurality of struts includes a channel that interfaces with the track of the first flange of a corresponding one of the plurality of beams to assist in sliding of the second catalyst support bed relative to the plurality of beams.

12. The heater according to claim 11, which further includes: A support rod disposed on the second flange of the corresponding one of the plurality of beams and including a slot configured to interface with the guiding element of the second flange of the corresponding one of the plurality of beams to assist in sliding of the second catalyst support bed.

13. The heater according to claim 1, which further includes: An interlocking seal plate located between the modules of the catalyst on the first catalyst support bed.

14. The heater according to claim 1, wherein the gap between the first tube sheet and the second tube sheet is less than 460 mm, and the structural frame has a height of less than 460 mm.

15. The heater according to claim 1, wherein the structural frame further includes: A plurality of frame elements coupled to the plurality of columns at at least one lateral side of the convection section; And A removable access door coupled to the plurality of frame elements.

16. The heater according to claim 15, which further includes: A heat insulating layer located between an end face of the first catalyst support bed and an inner face of the removable access door.

17. The heater according to claim 15, wherein the structural frame further includes a plurality of brackets coupled to the plurality of columns. Each of the plurality of brackets has a channel that receives at least a portion of a corresponding one of the plurality of beams to assist in coupling the plurality of beams to the plurality of columns.

18. The heater according to claim 17, wherein the plurality of brackets are coupled to the plurality of frame elements to assist in coupling the plurality of frame elements to the plurality of columns.

19. A heater, which includes: A convection section, which includes: A plurality of supports; A plurality of tube sheets coupled to the plurality of supports; Multiple tubes, which are connected to the multiple tube sheets; A space, which is located above or below at least one of the multiple tube sheets; A structural frame, which is located in the space and includes: Multiple beams, which are connected to the multiple supports and extend through the space in the transverse direction of the convection section, and each beam of the multiple beams includes a first flange with a track and a second flange with a guiding element; A first support rod, which is arranged on the second flange of the corresponding beam of the multiple beams and includes a slot, and the slot is configured to engage with the guiding element of the second flange of the corresponding beam of the multiple beams to assist the sliding of the first catalyst support bed.

20. The heater according to claim 19, wherein the multiple supports are arranged in pairs of supports spaced apart from each other in 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 transverse direction of the convection section.

21. The heater according to claim 20, wherein the multiple tube sheets include pairs of tube sheets connected to corresponding pairs of supports, each pair of tube sheets includes a first tube sheet and a second tube sheet, and the space is located between the first tube sheet and the second tube sheet.

22. The heater according to claim 19, wherein the first support rod is configured to prevent the first catalyst support bed from moving in the longitudinal direction of the convection section.

23. The heater according to claim 19, wherein the first flange and the second flange are normal to the web of each beam of the multiple beams, the track is normal to the first flange, and the guiding element is normal to the second flange.

24. The heater according to claim 19, wherein the track extends away from the guiding element.

25. The heater according to claim 19, wherein the convection section further includes a first gasket located between the support rod and at least some of the multiple struts of the first catalyst support bed, and a second gasket located between the second flange of the multiple beams and the corresponding tube sheet of the multiple tube sheets.

26. The heater according to claim 25, wherein the second gasket is configured to be compressed in response to the expansion of the corresponding tube sheet of the multiple tube sheets during operation.

27. The heater according to claim 19, wherein the structural frame includes the first catalyst support bed, and the first catalyst support bed can slide so that the catalyst can be loaded into or unloaded from the convection section through the first lateral side of the convection section.

28. The heater according to claim 27, which further includes: A second catalyst support bed, which is positioned in the space and is configured to enable the catalyst to be loaded into or unloaded from the convection section through the second lateral side of the convection section opposite to the first lateral side.

29. The heater according to claim 28, wherein the second catalyst support bed comprises a plurality of struts joined together, and a first strut of the plurality of struts of the second catalyst support bed comprises a channel that interfaces with the track of the first flange of the corresponding beam of the plurality of beams to assist in the sliding of the second catalyst support bed relative to the plurality of beams.

30. The heater according to claim 19, further comprising: A second support rod disposed on the second flange of the corresponding beam of the plurality of beams and comprising a slot configured to interface with the guiding element of the second flange of the corresponding beam of the plurality of beams to assist in the sliding of the second catalyst support bed.

31. The heater according to claim 28, further comprising: An interlocking seal plate located between the first catalyst support bed and the second catalyst support bed.

32. The heater according to claim 19, wherein the structural frame has a height of less than 460 mm.

33. The heater according to claim 19, wherein the structural frame has a height of greater than 460 mm.

34. The heater according to claim 19, wherein the structural frame further comprises: An access door frame coupled to the plurality of supports at at least one lateral side of the convection section; and An access door removably coupled to the access door frame.

35. The heater according to claim 34, further comprising: A heat insulation layer in contact with the end face of the first catalyst support bed and the inner face of the removable access door.

36. The heater according to claim 1 or claim 34, wherein the structural frame further comprises a plurality of brackets coupled to the plurality of supports, and each of the plurality of brackets receives at least a portion of the plurality of beams.

37. The heater according to claim 36, wherein the plurality of brackets are coupled to the access door frame.

38. A heater comprising: A convection section comprising: A space located above or below at least one of a plurality of tube sheets coupled to a plurality of columns; A structural frame located in the space and comprising: A first catalyst support bed removably coupled to the plurality of columns and positioned in the space, the first catalyst support bed being capable of sliding relative to the plurality of columns in the lateral direction of the convection section to enable loading or unloading of catalyst into or from the convection section through at least one lateral side of the convection section.

39. The heater according to claim 38, further comprising: A structural frame coupled to the plurality of columns and positioned in the space, the first catalyst support bed being capable of sliding relative to the structural frame.

40. The heater according to claim 39, wherein the structural frame comprises a plurality of frame elements, and a first frame element of the plurality of frame elements comprises a first guiding element and a second guiding element.

41. The heater according to claim 40, wherein the first catalyst support bed includes at least one channel that interfaces with the first guiding element of the plurality of frame elements to assist in sliding the first catalyst support bed relative to the plurality of columns.

42. The heater according to claim 41, further comprising: a plurality of sliding supports that interface with the second guiding element of the plurality of frame elements to assist in sliding the first catalyst support bed relative to the plurality of columns.

43. The heater according to claim 42, further comprising: at least one gasket located between the plurality of sliding supports and the structural frame.

44. The heater according to claim 39, further comprising: at least one gasket located between the structural frame and the plurality of tube sheets, the at least one gasket being configured to be compressed during operation of the convection section.

45. The heater according to claim 38, further comprising: a frame coupled to the plurality of columns at at least one lateral side of the convection section; an access door removably coupled to the frame; and a thermal insulation layer located between the access door and the first catalyst support bed.

46. The heater according to claim 38, wherein the at least one lateral side of the convection section is a first lateral side of the convection section, and the structural frame further includes: a second catalyst support bed removably coupled to the plurality of columns and positioned in the space, the second catalyst support bed being capable of sliding relative to the plurality of columns in the lateral direction of the convection section so that catalyst can be loaded into or unloaded from the convection section through a second lateral side of the convection section that is opposite the first lateral side.

47. The heater according to claim 46, further comprising: a sealing plate located between the first catalyst support bed and the second catalyst support bed.

48. A heater comprising: a convection section including at least one lateral side; and at least one catalyst support bed capable of sliding relative to the convection section so that catalyst can be loaded into or unloaded from the convection section through the at least one lateral side of the convection section.

49. The heater according to claim 48, wherein the at least one catalyst support bed is a first SCR module, the first SCR module being capable of sliding relative to a first sub-section of the convection section through at least one lateral side of the first sub-section, the first sub-section having a length less than the entire longitudinal length of the convection section.

50. The heater according to claim 49, further comprising: a second sub-section of the convection section having a length less than the entire longitudinal length of the convection section; and a second SCR module capable of sliding relative to the second sub-section of the convection section through at least one lateral side of the second sub-section.

51. The heater according to claim 49 or claim 50, wherein the first sub-segment and the second sub-segment are separated by a support member of the convection segment.

52. A heater comprising: a convection segment including a plurality of sub-segments arranged in parallel along the entire longitudinal length of the convection segment, wherein the plurality of sub-segments are separated from each other by a support member of the convection segment, and each of the plurality of sub-segments includes at least one corresponding lateral side corresponding to at least one lateral side of the convection segment; a plurality of tubes coupled to the support member of the convection segment; a gap located between outer tubes of the plurality of tubes; and a plurality of SCR modules positioned in the gap and each configured to carry one or more catalyst modules, the plurality of SCR modules being associated with corresponding sub-segments of the plurality of sub-segments of the convection segment and configured to be mounted in parallel through the at least one corresponding lateral side of the plurality of sub-segments.

53. The heater according to claim 52, wherein each of the plurality of sub-segments includes a single SCR module of the plurality of SCR modules that is slidable relative to the convection segment.

54. The heater according to claim 52, wherein each of the plurality of sub-segments includes at least two SCR modules of the plurality of SCR modules, and each of the at least two SCR modules is slidable relative to the convection segment.

55. The heater according to claim 54, wherein the at least two SCR modules are slidable relative to a front lateral side and a rear lateral side of each corresponding sub-segment of the plurality of sub-segments.

56. A method of retrofitting a heater, comprising: coupling a structural frame to a plurality of columns in a space between a plurality of tube sheets of the plurality of tubes coupled to a convection segment; and sliding a catalyst support bed along the structural frame through a lateral side of the convection segment to load or unload a catalyst on the catalyst support bed into or from the convection segment.

57. The method according to any one of claims 1 to 55.

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