CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/239,731, filed October 9, 2015, entitled "CONVECTION SECTION HAVING A DECLINER PLATE" which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE DISCLOSURE

TECHNICAL FIELD

[0002] The present disclosure relates to a convection section having a decliner to deflect hot process gases away from a baffle and tube surface present therein, as well as a system and method for producing superheated steam employing the convection section.

DESCRIPTION OF THE RELATED ART

[0003] The "background" description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description, which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.

[0004] Convection zones or sections are primarily used in direct fired process heaters to obtain low temperature differentials between a process fluid (i.e. steam and/or a heat transfer medium) and a flue gas. Extended surface superheating tubes and baffles are often used in such convection zones as a result of the heat transfer coefficient within the convection section (flue gas side) outside of the superheating tube being much lower than that inside the superheating tubes (process fluid side). Under extreme pressure and temperature conditions, through-wall localized rupture of the superheating tubes and noticeable deformation of the baffle plate can become a chronic problem, especially near the flue gas exit of the process heater.

[0005] It is impractical to alter the operating parameters associated with a primary reforming process by, for example, reducing the flue gas or inlet steam temperatures because of the associated product loss and the necessity of redesigning the operation of upstream boilers. The conventional practice is to cut and remove any failed portions of the superheating tube and baffle plate as they occur and weld new portions into place; however, even if fully or partially replaced, failure will repeat. This type of repair is expensive due, in part, to the difficulties associated with welding upgraded metallurgy as well as the downtime and loss of production due to unplanned shutdown.

BRIEF SUMMARY OF THE DISCLOSURE

[0006] In view of the forgoing, one aspect of the present disclosure is to provide a convection section of a process heater featuring a decliner to deflect hot flue gas away from a baffle plate and a superheating tube and toward a more central area of the convection section to thereby substantially increase the functional life of these components of the convection section. The present disclosure further discloses a system and method for producing superheated steam employing the convection section. The convection section and method of the present disclosure are advantageously practical and less expensive than conventional practice and reduce the economic impact of repairs.

[0007] According to a first aspect, the present disclosure relates to a horizontally oriented convection section of a process heater having a longitudinal axis with a hot gas inlet and an opposing exhaust outlet comprising i) a superheating line comprising a superheating coil section, a superheating inlet disposed between the superheating coil section and the exhaust outlet of the convection section and a superheating outlet disposed between the superheating coil section and the hot gas inlet of the convection section ii) a baffle plate that dissects the superheating line between the superheating coil section and the superheating outlet and iii) a decliner disposed between the baffle plate and the hot gas inlet of the convection section, and wherein the decliner is attached to an inner wall of the convection section at an angle greater than 0° and less than 90° from the inner wall such that it deflects feed flow entering the hot gas inlet away from the baffle plate.

[0008] In one embodiment, the baffle plate is disposed a distance of less than 0.5-5 times the largest dimension of the decliner from the attachment of the decliner to the inner wall of the convection section. [0009] In one embodiment, the decliner comprises at least one refractory material.

[0010] In one embodiment, the decliner is anchored to the inner wall of the convection section with an anchor comprising at least one refractory material and/or high temperature resistant alloy.

[0011] In one embodiment, the decliner is reinforced with wires, strips, and/or stiffeners comprising at least one high temperature resistant alloy.

[0012] In one embodiment, the decliner is planar, convex, concave and/or corrugated. [0013] In one embodiment, the decliner is attached to an inner wall of the convection section at an angle of greater than 0° and less than 45° from the inner wall.

[0014] In one embodiment, the decliner is attached to an inner wall of the convection section such that its obtuse angle from the inner wall is oriented towards the hot gas inlet and its acute angle from the inner wall is oriented toward the exhaust outlet.

[0015] In one embodiment, the decliner has a thickness of up to 500 mm.

[0016] In one embodiment, the decliner has a surface area of up to 45% of the cross sectional area of the convection section taken perpendicular to the longitudinal axis.

[0017] In one embodiment, the convection section is rectangular in cross section taken perpendicular to the longitudinal axis and the decliner is rectangular with width of up to 90% of the width of the rectangular cross section and length of up to 90% of the length of the rectangular cross section.

[0018] In one embodiment, the convection section is cylindrical and/or circular in cross section taken perpendicular to the longitudinal axis and the decliner is circular or semicircular with a radius of up to 90% of the radius of the circular cross section and perimeter of up to 90% of the circumference of the circular cross section.

[0019] In one embodiment, the decliner has a percent porosity of less than 50%.

[0020] According to a second aspect, the present disclosure relates to a system for producing superheated steam having the convection section comprising i) a combustion source of hot flue gas and a flue gas feed line that fluidly connects the combustion source of hot flue gas to the hot gas inlet of the convection section and ii) a steam source and a steam line that fluidly connects the steam source to the superheating inlet of the convection section, wherein the flow of hot flue gas through the convection section is counter to the flow of steam through the superheating line and heat is transferred from the hot flue gas to the steam to form superheated steam, and wherein the decliner deflects hot flue gas entering the hot gas inlet away from the baffle plate.

[0021] In one embodiment, localized overheating, deformation, and/or rupture of the baffle plate and/or superheating line is reduced relative to substantially the same system operated under substantially the same operating conditions without a decliner. [0022] In one embodiment, the system further comprises a reformer wherein the superheated steam is reacted with a fossil fuel to produce synthesis gas comprising hydrogen and carbon monoxide.

[0023] In one embodiment, hot flue gas enters the hot gas inlet of the convection section at a temperature of up to 1200°C and exits the exhaust outlet of the convection section at temperatures of up to 600°C. [0024] According to a third aspect, the present disclosure relates to a method for producing superheated steam using the system comprising i) firing the combustion source to generate hot flue gas ii) flowing the hot flue gas through the convection section iii) flowing the steam through the superheating line counter to the flow of hot flue gas and iv) contacting the hot flue gas with the super heating line to transfer heat from the hot flue gas to the steam to form superheated steam, wherein the decliner deflects hot flue gas entering the hot gas inlet away from the baffle plate.

[0025] In one embodiment, localized overheating, deformation, and/or rupture of the baffle plate and/or superheating line is reduced relative to substantially the same method performed under substantially the same operating conditions without the decliner. [0026] In one embodiment, the method further comprises reacting the superheated steam with a fossil fuel to produce synthesis gas comprising hydrogen and carbon monoxide.

[0027] The term "coupled" is defined as connected, although not necessarily directly, and not necessarily mechanically; two items that are "coupled" may be unitary with each other. The terms "a" and "an" are defined as one or more unless this disclosure explicitly requires otherwise. The term "substantially" is defined as largely but not necessarily wholly what is specified (and includes what is specified; e.g., substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by a person of ordinary skill in the art. In any disclosed embodiment, the term "substantially" may be substituted with "within [a percentage] of what is specified, where the percentage includes .1, 1, 5, and 10 percent. [0028] The phrase "and/or" means and or or. To illustrate, A, B, and/or C includes: A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C. In other words, "and/or" operates as an inclusive or.

[0029] Further, a device or system that is configured in a certain way is configured in at least that way, but it can also be configured in other ways than those specifically described. [0030] The terms "comprise" (and any form of comprise, such as "comprises" and "comprising"), "have" (and any form of have, such as "has" and "having"), "include" (and any form of include, such as "includes" and "including"), "contain" (and any form of contain, such as "contains" and "containing") are open-ended linking verbs. As a result, an apparatus that "comprises," "has," "includes," or "contains" one or more elements possesses those one or more elements, but is not limited to possessing only those one or more elements. Likewise, a method that "comprises," "has," "includes," or "contains" one or more steps possesses those one or more steps, but is not limited to possessing only those one or more steps.

[0031] Any embodiment of any of the apparatuses, systems, and methods can consist of or consist essentially of - rather than comprise/have/include/contain - any of the described steps, elements, and/or features. Thus, in any of the claims, the term "consisting of or "consisting essentially of can be substituted for any of the open-ended linking verbs recited above, in order to change the scope of a given claim from what it would otherwise be using the open-ended linking verb.

[0032] The feature or features of one embodiment may be applied to other embodiments, even though not described or illustrated, unless expressly prohibited by this disclosure or the nature of the embodiments.

[0033] Some details associated with the embodiments are described above, and others are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0035] FIG. 1 is a schematic diagram of a convection section. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Reference is now made to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views.

[0037] The fired process heaters often used in integrated chemical and manufacturing plants serve many purposes, including providing heat for distillation, fluidized catalytic cracking, alkylation, catalytic reforming, continuous catalyst regeneration, thermal cracking, coking, hydrocracking, and vaporization. In general, fired process heaters comprise two distinct heating sections: a radiant section (combustion chamber or firebox) and a convection section. Hot flue gases arising in the radiant section flow into the convection section where they circulate around a tube bundle or coils before leaving the furnace. A third heating section, known as the shield or shock section, may separate the two major heating sections. In standard practice, a process fluid (e.g., heat transfer medium) is first heated in the convection section by passage through a variety of tubes or coils displaced therein. The first heating is optionally followed by further heating in the radiant section. In both sections, heat is transferred to the process fluid by heat transfer, radiation and convection, where radiation is the dominant mode of heat transfer at the high temperatures prevalent in the radiant section, and convection predominates in the convection section where the average temperature is much lower.

[0038] According to a first aspect, referring to FIG. 1, the present disclosure relates to a convection section of a process heater having a longitudinal axis with a hot gas inlet (104) and an opposing exhaust outlet, a superheating line comprising a superheating coil section (105), a superheating inlet (106) disposed between the superheating coil section and the exhaust outlet of the convection section, a superheating outlet (107) disposed between the superheating coil section and the hot gas inlet of the convection section, a baffle plate (102) that dissects the superheating line between the superheating coil section and the superheating outlet, and a decliner (101) disposed between the baffle plate and the hot gas inlet of the convection section. The decliner is attached to an inner wall of the convection section at an angle greater than 0° and less than 90° from the inner wall such that the decliner deflects hot flue gas flow entering the hot gas inlet away from the baffle plate, thereby preventing premature deformation and/or localized rupture (103).

[0039] The extreme conditions of temperature and pressure that the superheating coil, superheating line, and baffle plate are subjected to can lead to localized overheating, deformation and/or rupture of a first tube of the superheating coil, the superheating line, and the baffle plate, especially when located proximal to the hot gas inlet of the convection section. Therefore, one object of the present disclosure is to provide a convection section featuring a decliner that at least partially shields these components from hot flue gas and deflects or redirects hot flue gas entering the hot gas inlet of the convection section away from the superheating coil, the superheating line and/or the baffle plate and towards a central area of the convection section.

[0040] The basic structure of the convection section includes a rectangular, cylindrical or similarly shaped steel chamber, optionally lined with refractory bricks. Tubes comprising the superheating line and superheating coil are arranged in fluid communication around the chamber inside the convection section, e.g., in either horizontal or vertical banks or serpentines, optionally perpendicular or parallel to the longitudinal axis of the convection section. Tubes having heat transfer features such as surface tubes, fins, studs and/or pins can be used in the convection section to improve heat transfer from hot flue gases to the process fluid. Typical tube sizes have dimensions of 50-250 mm in diameter, preferably 75-200 mm, or preferably 75-150 mm in diameter. The tube size and number of passes of tubes inside the convection section may depend on the application and process fluid flow rate and are not particularly limiting. The baffle plate is a flow directing and/or a flow obstructing vane or panel that is designed to support the tube bundles and coils and direct the flow of fluids for maximum efficiency in the heat transfer process. The baffle plate is preferably mounted such that the superheating tubes are disposed between the inner wall of the convection section and the baffle plate. [0041] In one embodiment, the convection section may have an arbitrary length of 0-100 units along the longitudinal axis, where 0 represents the location of the hot gas inlet and 100 represents the exhaust outlet. The decliner is preferably located between 0-40, preferably 2- 30, preferably 3-25, preferably 8-20, preferably 12-15, preferably 0-10, preferably 0-5 length units of the convection section, the baffle plate is preferably located between 0-60, preferably 0-50, preferably 0-40, preferably 0-30, preferably 0-25, preferably 0-20, preferably 0-15, or preferably 0-10 length units of the convection section, and the superheating coil is preferably located 0-70, preferably 0-60, preferably 0-50, preferably 0-40, preferably 0-30, preferably 0- 25, preferably 0-20, or preferably 0-15 length units of the convection section. In one embodiment, the baffle plate is disposed a distance of less than 0.5-5 times the largest dimension of the decliner from a point where the decliner is attached to the inner wall of the convection section, preferably 0.5-4 times, preferably 0.5-3 times, preferably 0.5-2.5, preferably 0.5-2, preferably 0.75-2, preferably 1-2 times the largest dimension of the decliner.

[0042] In one embodiment, the decliner is fixed and set at a single position in the convection section as described above. In another embodiment, the decliner may further comprise tracks and/or other means that permit movement between the hot gas inlet of the convection section and the baffle plate depending on the application of the convection section and current operating procedures. In one embodiment, the decliner is a single unitary piece. In another embodiment, the decliner may comprise sections (up to 10, preferably up to 5, preferably up

27578880.1 - 7 - to 3, preferably 2) that can be added or removed depending on the application of the convection section and current operating conditions. In one embodiment, the decliner may be fully inside of the convection section. In another embodiment, the decliner may further comprise an apparatus that permits at least partial retraction (up to 50%, preferably up to 40%, preferably up to 30%, preferably up to 25%) from the convection section depending on the application of the convection section and current operating conditions.

[0043] In one embodiment, the decliner is attached to the inner wall of the convection section at an angle of greater than 0° and less than 90° measured from the surface of the inner wall of the convection section, preferably 0° to 80°, preferably 0° to 75°, preferably 0° to 70°, preferably 0° to 65°, preferably 0° to 60°, preferably 0° to 55°, preferably 0° to 50°, preferably 0° to 45°. In a preferred embodiment, the decliner is attached to the inner wall of the convection section at an angle of greater than 0° and less than 45°, preferably 5° to 45°, preferably 10° to 45°, preferably 15° to 43°, preferably 20° to 40°, preferably 25° to 35°

[0044] The attachment of the decliner to the inner wall of the convection section at an angle that is not 90° creates two angles with the inner wall of the convection section, an acute angle (of less than 90°) and an obtuse angle (of greater than 90°). In a preferred embodiment, the decliner is attached to an inner wall of the convection section such that its obtuse angle from the inner wall is oriented towards the hot gas inlet and its acute angle is oriented toward the exhaust outlet (as shown in FIG. 1). In another embodiment, the decliner may be attached to an inner wall of the convection section such that its acute angle from the inner wall is oriented towards the hot gas inlet and its obtuse angle is oriented toward the exhaust outlet.

[0045] In one embodiment, the decliner is fixed and set at a single angle in the ranges described above. In another embodiment the attachment of the decliner to an inner wall of the convection section may further comprise a hinge, attachment means and/or bearing that allows a limited range of motion or angle of rotation between the decliner and the inner wall of the convection section. Exemplary types of hinges include, but are not limited to, barrel hinges, pivot hinges, butt/mortise hinges, case hinges, continuous (piano) hinges, concealed hinges, butterfly (parliament) hinges, flag hinges, strap hinges, H hinges, HL hinges and the like. In one embodiment, during operation of the convection section, the angle is fixed and set at a single angle within the ranges described above and can be adjusted and fixed when the convection section is not in operation. In another embodiment, during operation of the convection section, the angle may have a free range of motion of less than 15°, preferably less than 10°, preferably less than 5°, preferably less than 2°, preferably less than 1°. [0046] In other embodiments, the decliner may be oriented in a "canted angle" fashion with respect to the longitudinal axis of the convection section. When viewed as a cross section through the convection section, a first axis of the decliner rectangle may be canted relative to the longitudinal axis of the convection section by, for example, 2-35°, preferably 4-30°, more preferably, 8-25° and preferably 12-20°.

[0047] The convection section is preferably oriented horizontally and is preferably stacked on a radiant section of a process heater. Other orientations such as substantially horizontal orientations are possible. Likewise, horizontal, angled, or vertical orientations are possible depending on the orientation of a radiant section or other hot flue gas generating apparatus to which the convection section may be directly or indirectly attached.

[0048] More than one decliner may be mounted on the inner wall. For example, a plurality of decliners may be mounted concentrically around the circumference of the inner wall of the convection section. For further example, a first decliner may be mounted on a first surface in a rectangular-form convection section and a second decliner may be mounted on a surface opposing the surface on which the first decliner is attached. In some embodiments, one or more decliners are mounted to the inner wall upstream from a second or further decliner.

[0049] The decliner functions to direct and orient hot flue gas flow away from the inner wall of the convection section and towards the central axis of the convection section without substantially disrupting heat transfer to the superheating coil through which steam and/or a heat transfer medium is flowing. In one embodiment one or more decliners form an eddy in the hot flue gas flow inside the convection section. The eddy, in which flow has decreased velocity relative to the average velocity of the hot flue gas flow in the convection section, results in less deformation and/or less stress on any device, apparatus or structure present proximal to the decliner and generally situated in the eddy. [0050] In one embodiment, the convection section of the present disclosure is rectangular in cross section taken perpendicular to the longitudinal axis, and the decliner is rectangular with a width of up to 90% of the width of the rectangular cross section, preferably up to 80%, preferably up to 70%, preferably up to 60%, preferably up to 50%, preferably up to 45%, preferably up to 40%, preferably up to 35%, preferably up to 30%, preferably up to 25%, preferably up to 20% of the width of the rectangular cross section and a length of up to 90% of the length of the rectangular cross section, preferably up to 80%, preferably up to 70%, preferably up to 60%, preferably up to 50%, preferably up to 45%, preferably up to 40%, preferably up to 35%, preferably up to 30%>, preferably up to 25%, preferably up to 20% of the length of the rectangular cross section. In another embodiment, the convection section is rectangular in cross section, and the decliner is circular or semicircular with a radius of up to 90% of the width and/or length of the rectangular cross section. [0051] In one embodiment, the convection section of the present disclosure is cylindrical and/or circular in cross section taken perpendicular to the longitudinal axis, and the decliner is circular or semicircular with a radius of up to 90% of the radius of the circular cross section, preferably up to 80%>, preferably up to 70%, preferably up to 60%, preferably up to 50%), preferably up to 45%, preferably up to 40%, preferably up to 35%, preferably up to 30%), preferably up to 25%, preferably up to 20% of the radius of the circular cross section and/or a perimeter of up to 90% of the radius of the circular cross section, preferably up to 80%), preferably up to 70%, preferably up to 60%, preferably up to 50%, preferably up to 45%), preferably up to 40%, preferably up to 35%, preferably up to 30%, preferably up to 25%), preferably up to 20% of the radius of the circular cross section. In another embodiment, the convection section is cylindrical and/or circular in cross section, and the decliner is rectangular with a width of up to 90% of the radius of the circular cross section and/or a length of up to 90% of the radius of the circular cross section.

[0052] In a preferred embodiment, the decliner (e.g., a side thereof, whether facing the hot gas inlet or the exhaust outlet) has a surface area of up to 45% of the cross sectional area of the convection section taken perpendicular to the longitudinal axis, preferably up to 40%, preferably up to 35%, preferably up to 30%, preferably up to 25%, preferably up to 20%, preferably up to 15%, preferably up to 10%.

[0053] In a preferred embodiment, the decliner has an average thickness of less than 50 mm, preferably less than 40 mm, preferably less than 35 mm, preferably less than 30 mm, preferably less than 25 mm, preferably less than 20 mm.

[0054] In one embodiment, the decliner is planar. In another embodiment, the decliner may be convex or concave and the convex or concave face of the decliner may be oriented towards the hot gas inlet or towards the exhaust outlet. The topology and morphology of the decliner may also be varied to fit the application and is not viewed as particularly limiting. In one embodiment, the surface of the decliner is smooth. In another embodiment, the surface of the decliner is ridged, threaded and/or corrugated such that, for example, the surface defines a series of (e.g., parallel) ridges or furrows. The height of the ridges from the basal plane of the decliner is preferably less than 10 cm, preferably less than 8 cm, preferably less than 5 cm, preferably less than 3 cm. In another embodiment, one surface or side of the decliner may be smooth and a second face or side of the decliner may be corrugated. In this case, the corrugated side is preferably oriented towards the hot gas inlet, and the smooth side is preferably oriented towards the exhaust outlet, but the inverse may also be sufficient.

[0055] In a preferred embodiment, the decliner is made of or comprises at least one refractory material, such as silicon carbide. As used herein, "refractory" or "refractory material" refers to a material, preferably non-metal, having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above 500 °C and that retain their strength at high temperatures. Refractory materials must be chemically and physically stable at high temperatures and, depending on the operating environment, must be resistant to thermal shock, be chemically inert and/or have specific ranges of thermal conductivity and coefficients of thermal expansion. Exemplary refractory materials for the decliner of the present disclosure may include, but are not limited to, graphene (C), graphite (C), thoria (Th0 ₂ ), magnesia (MgO), zirconia (Zr0 ₂ ), lime (CaO), beryllia (BeO), silicon carbide (SiC), chromite (Cr ₂ 0 ₃ , FeO- Cr ₂ 0 ₃ ), chromium oxide (CrO), alumina (A1 ₂ 0 ₃ ), alumina fused bauxite, titania (Ti0 ₂ ), silica (Si02), kaolin (Al ₂ Si ₂ 05(OH) ₄ ), fire clay (mineral aggregates composed of hydrous silicates of aluminum, A1 ₂ 0 ₃ 2Si0 ₂ 2H ₂ 0), tungsten carbide, boron nitride, tantalum hafnium carbide and mixtures thereof. In another embodiment, the decliner may comprise a core of metal and/or metal alloy such as carbon steel, stainless steel, special alloy steels or special metallurgies, lined, coated and/or covered by a refractory material.

[0056] Refractories may be classified based on their chemical composition. Acidic refractories consist of mostly acidic materials and generally are not attacked by acidic materials (e.g. alumina, silica). Neutral refractories are chemically stable to both acids and base (e.g. alumina, chromia, carbon). Basic refractories refer to those that are stable to alkaline materials (e.g. magnesia, dolomite, chrome-magnesia, periclase). In terms of the present disclosure, the refractory material may be an acidic refractory, a neutral refractory, a basic refractory or mixtures thereof. [0057] Refractories may be classified based on their fusion temperature. Normal refractories have a fusion temperature of 1580-1780 °C (e.g. fire clay), high refractories have a fusion temperature of greater 1780-2000 °C (e.g. chromite) and super refractories have a fusion temperature of greater than 2000 °C (e.g. zirconia). In terms of the present disclosure, the refractory material may be a normal refractory, a high refractory, a super refractory or mixtures thereof.

[0058] In a preferred embodiment, the decliner is anchored to the inner wall of the convection section with at least one anchor, preferably a plurality of anchors, and preferably, the anchor comprises at least one refractory material or heat resistant alloy. Refractories generally require anchorage systems such as wire formed anchors, formed metal or ceramic tiles to support the refractory linings. The anchorage used for refractory on roofs and vertical walls must remain able to support the weight of the refractory even at elevated temperatures, durations and operating conditions. In a preferred embodiment, the refractory anchorages have circular or rectangular cross sections. In most cases, circular cross sectional anchorage is used for low thickness refractory, and rectangular cross sectional anchorage is used for high thickness refractory. The number of anchors to be used depends on the operating conditions and the refractory materials. The choice of anchors, including material, shape, numbers and size, has impact on the useful life of the refractory, but is not envisioned to be particularly limiting in terms of the present disclosure. Exemplary types and shapes of anchorage include, but are not limited to, round bars, flat bars, plates, round wire, brick linings (brick staples, scissor clips, brick claws, tie back anchors, brick supports), ceramic fiber linings (hooked, plain, threaded, stud weldable), concrete linings (Y-shaped, A-shaped, winged, corrugated, V-shaped, reversed leg, hooked, threaded wavy, bullhorn, round, notched) and mixtures thereof.

[0059] In a preferred embodiment, the decliner is reinforced with wires, strips, and/or stiffeners that increase the mechanical properties of the decliner and decrease vibrations of the decliner, while enhancing mechanical integrity to stop buckling or collapse. In a preferred embodiment, the reinforcement and/or stiffener comprises at least one heat resistant alloy. As used herein "reinforcement" and/or "stiffener" refer to mechanical additions to the decliner or its anchorage that prevent deformation, movement and/or vibration. A stiffener may provide anti-buckling, anti-wrinkling, desired shaping, reinforcement, repair, strength, enhanced function, extended utility or longer life to the decliner and/or its anchorage. Mechanical methods of stiffening may include, but are not limited to, tension stiffening, bracing, superstructure bracing, substructure bracing, straightening, strain stiffening, stress stiffening, damping vibrations, swelling, pressure increasing, drying, cooling, interior reinforcing, exterior reinforcing, wrapping, surface treating or mixtures thereof.

[0060] Heat resistant alloys refer to alloys that have high creep resistance and strength at high temperatures. Heat resistant alloys may also refer to composite materials, or alloys strengthened by disperse particles such as refractory oxides, high strength fibers, etc. Heat resistant alloys can be classified according to their base metal which may include, but is not limited to, nickel, iron, titanium, beryllium and the like. Heat resistant alloys generally have an operating temperature of 0.3-0.9 of the melting point of their base metal. In a preferred embodiment, the decliner, its anchorage, its reinforcement and/or its stiffener comprises a heat resistant alloy, preferably an Inconel alloy, an Incoloy alloy, or a Haynes alloy, most preferably Inconel 600, Incoloy 800HT, or Haynes 214.

[0061] Inconel alloys are a family of austenite nickel chromium based super alloys. Inconel alloys are oxidation and corrosion resistant materials well suited to service in extreme environments subjected to pressure and heat, where steel and aluminum would succumb to thermal creep from thermally induced crystal vacancies. Inconel forms a thick, stable, passivating oxide layer when heated that protects the surface from further attack. In a preferred embodiment, the decliner, its anchorage, its reinforcement and/or its stiffener comprises an Inconel alloy, preferably Inconel 600. Available in numerous grades, the Inconel alloys exhibit shifting characteristics with slight variation in their chemistry. It is envisaged that the present disclosure may be adapted to incorporate additional Inconel alloys including, but not limited to, Inconel 617, Inconel 625, Inconel 690, Inconel 718, Inconel X- 750 and alloys or mixtures thereof. [0062] In a preferred embodiment, the decliner, its anchorage, its reinforcement and/or its stiffener comprises an Incoloy alloy, preferably Incoloy 800HT. It is envisaged that the present disclosure may be adapted to incorporate additional Incoloy alloys including, but not limited to Incoloy 020, Incoloy DS, Incoloy MA956, Incoloy 800, Incoloy 800H and alloys or mixtures thereof. [0063] Haynes alloys are nickel-chromium-aluminum-iron alloys designed to include small amounts of rare earth metals and provide optimal high temperature and high temperature oxidation resistance for wrought austenitic materials, while allowing for conventional forming and joining. In a preferred embodiment, the decliner, its anchorage, its reinforcement, and/or its stiffener comprises a Haynes alloy, preferably Haynes 214. It is envisaged that the present disclosure may be adapted to incorporate additional Haynes alloys including, but not limited to, Haynes HR-120 alloy, Haynes 230 alloy, Haynes 556 alloy, Hasteeloy X alloy [0064] Refractory metals refer to a class of metals that are extraordinarily resistant to heat and wear. The most common definition includes five elements: niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W), and rhenium (Re), but refractory metals can be more generally described as having a melting point above 1850 °C, a high hardness at room temperature, and a high stability against creep deformation at very high temperatures and can include titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), hafnium (Hf), ruthenium (Ru), rhodium (Rh), osmium (Os) and iridium (Ir). In a preferred embodiment, the decliner, its anchorage, its reinforcement and/or its stiff ener may comprise a refractory metal and mixtures or alloys thereof. [0065] Porosity is a measure of the effective open pore space in the decliner and/or refractory into which or through which process fluids (e.g., slag, flues, vapors, fluxes) can penetrate (e.g., and thereby contribute to the degradation of the structure) or pass. Porosity provides a means of ventilation for the decliner and/or refractory. Porosity is defined and expressed as the percentage of the total surface area of the decliner that represents passages and/or the ratio (in percentage) of the volume of interstices of the decliner to the volume of the mass of the decliner. In a preferred embodiment, the decliner of the present disclosure and its refractory components have a percent porosity of less than 50%, less than 40%, less than 30%), preferably less than 25%>, preferably less than 20%>, preferably less than 15%>, preferably less than 10%>, preferably less than 8%>. The passages through the decliner may be oriented perpendicular to the surface of the decliner or at an angle.

[0066] According to a second aspect, the present disclosure relates to a system for producing superheated steam using the convection section of the present disclosure in any of its embodiments including a hot flue gas from a combustion source, a flue gas feed line that fluidly connects the combustion source of the hot flue gas to the hot gas inlet of the convection section, and a steam/water source and a steam line that fluidly connects the steam/water source to the superheating inlet of the convection section, such that the flow of hot flue gas through the convection section is counter to the flow of steam through the superheating line and heat is transferred from the hot flue gas to the steam to form superheated steam and wherein the decliner deflects hot flue gas entering the hot gas inlet away from the baffle plate.

[0067] In one embodiment, the combustion source may be an oven, furnace, boiler or steam generator. The composition of the flue gas will depend on what is being burned, but will typically contain mostly nitrogen (e.g., > 60%>), carbon dioxide, water vapor and oxygen. It may also include particulate matter (soot), carbon monoxide, nitrogen oxides and sulfur oxides. In one embodiment, the combustion source generates hot flue gas that enters the hot gas inlet of the convection section at temperatures of up to 1200 °C, preferably 700-1200 °C, preferably 800-1200 °C, preferably 850-1150 °C, preferably 900-1100 °C, preferably 950- 1050 °C or 1000 °C and is then cooled down. The resultant cooled flue gas exits the convection section via the exhaust outlet at temperatures below 600 °C, preferably below 500 °C, preferably below 400 °C, preferably below 350 °C, preferably below 325 °C, preferably below 300 °C, preferably below 275 °C, preferably below 250 °C. In one embodiment, hot flue gas enters the hot gas inlet of the convection section with a pressure of up to 150 bar, preferably up to 100 bar, preferably up to 50 bar, preferably up to 25 bar, preferably up to 15 bar, preferably up to 10 bar, preferably up to 5 bar.

[0068] As used herein, "superheated steam" refers to steam at a temperature higher than its vaporization point at the absolute pressure where the temperature is measured. The internal energy value of superheated steam can be used for kinetic reaction through mechanical expansion, e.g., against turbine blades. In one embodiment, steam enters the superheating inlet of the convection section at temperatures below 400 °C, preferably below 350 °C, preferably below 300 °C, preferably below 250 °C, preferably below 225 °C, preferably below 200 °C, preferably below 175 °C, preferably below 150 °C, preferably below 125 °C and is then heated and steam exits the convection section via the superheating outlet at temperatures of up to 700 °C, preferably up to 650 °C, preferably up to 600 °C, preferably up to 550 °C, preferably up to 525 °C, preferably up to 500 °C, preferably up to 475 °C, preferably up to 450 °C, preferably up to 400 °C, preferably up to 350 °C, preferably up to 300 °C. In one embodiment, steam enters the superheating inlet of the convection section with a pressure of less than 50 bar, preferably less than 40 bar, preferably less than 30 bar, preferably less than 25 bar, preferably less than 20 bar, preferably less than 15 bar, preferably less than 10 bar and exits the convection section via the superheating outlet with a pressure of up to 175 bar, preferably up to 150 bar, preferably up to 125 bar, preferably up to 100 bar, preferably up to 95 bar, preferably up to 90 bar, preferably up to 85 bar, preferably up to 80 bar, preferably up to 75 bar, preferably up to 70 bar, preferably up to 60 bar. [0069] In one embodiment, the convection section system of the present disclosure prevents and/or reduces the occurrence of localized overheating, deformation and/or rupture of the baffle plate, superheating coil and/or superheating line in comparison to substantially the same system operated under substantially the same operating conditions without the decliner. The baffle plate and superheating lines may have a substantially extended functional life compared to the same components in a convection section lacking a decliner.

[0070] In a preferred embodiment, the system may further comprise a reformer, wherein the superheated steam is reacted with a fossil fuel to produce synthesis gas (syngas) comprising hydrogen and carbon monoxide. The reformer may be a single or multiple fired furnace. The reformer may be a top fired, bottom fired or a Terrace Wall reformer and the convection section may be a unit of the reformer or separate, free standing entity.

[0071] Steam reforming is a method for producing hydrogen, carbon monoxide, or other useful products from hydrocarbon fuels such as natural gas. This is achieved in a processing device called a reformer, which reacts steam at high temperature with a fossil fuel. The steam methane reformer is widely used in industry to make hydrogen. Steam reforming of natural gas, often referred to as steam methane reforming (SMR), is the method of producing commercial bulk hydrogen used in the industrial synthesis of ammonia and other chemicals. At high temperatures (700-1100 °C) and in the presence of a metal-based catalyst (e.g., nickel), steam reacts with methane to yield carbon monoxide and hydrogen (formula I). Additional hydrogen can be recovered by a lower temperature gas shift reaction with the carbon monoxide produced (formula II):

(I) : CH ₄ + H ₂ 0 CO + 3 H ₂

(II) : CO + H ₂ 0 C0 ₂ + H ₂

[0072] According to a third aspect, the present disclosure relates to a method for producing superheated steam using the system of the present disclosure in any of its embodiments comprising firing the combustion source to generate hot flue gas, flowing the hot flue gas through the convection section, flowing the steam through the superheating line counter to the flow of hot flue gas and contacting the hot flue gas with the super heating line to transfer heat from the hot flue gas to the steam to form superheated steam, wherein the decliner deflects hot flue gas entering the hot gas inlet away from the baffle plate, preferably to a more central area of the convection section, as described herein. In one embodiment, the localized overheating, deformation and/or rupture of the baffle plate and/or superheating line is reduced relative to substantially the same method performed under substantially the same operating conditions without the decliner, as described herein. In one embodiment, the method further comprises reacting the superheated steam with a fossil fuel to produce synthesis gas comprising hydrogen and carbon monoxide, as described herein. [0073] The above specification and examples provide a complete description of the structure and use of illustrative embodiments. Although certain embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. As such, the various illustrative embodiments of the methods and systems are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and embodiments other than the one shown may include some or all of the features of the depicted embodiment. For example, elements may be omitted or combined as a unitary structure, and/or connections may be substituted. Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples having comparable or different properties and/or functions, and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments.

[0074] The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) "means for" or "step for," respectively.