EP4669911A1

EP4669911A1 - HYBRID OVEN WITH FUEL AND/OR ELECTRICITY

Info

Publication number: EP4669911A1
Application number: EP24760871.4A
Authority: EP
Inventors: Baozhong Zhao; Aijing YIN; Marijn KAMPHUIS; Alejandro Carrillo; Marcio RAZUK
Original assignee: Lummus Technology Inc; Lummus Technology LLC
Current assignee: Lummus Technology LLC
Priority date: 2023-02-20
Filing date: 2024-02-20
Publication date: 2025-12-31
Also published as: US20240280261A1; JP2026505505A; CN121039434A; TW202434709A; WO2024178017A1; TWI906777B; KR20250135886A

Abstract

An apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burners. The apparatus includes a radiant heating section and a flue gas stack for exhausting a combustion gas to the atmosphere. The radiant section includes one or more process coils, one or more fuel-fired burners for combusting a fuel and producing the combustion gas, where the one or more fuel-fired burners are arranged to provide radiant energy to a first area of the one or more process coils, and one or more electrical heating elements arranged to provide radiant energy to a second area of the one or more process coils. The one or more electrical heating elements are configured to provide 5% or more of a combined maximum energy output of the fuel-fired burners and the electrical heating elements.

Description

HYBRID FURNACE WITH FUEL AND/OR ELECTRICITY

BACKGROUND

[0001] In the refining and petrochemical industries, heaters are predominantly fuel fired. The current fired heaters generate carbon dioxide when firing hydrocarbon fuels, which is a source of greenhouse gases that lead to global warming. Thus, there is a general desire to move away from hydrocarbon fuel-fired heaters.

[0002] Electric heaters, however, are presently limited to relatively small capacity, and only now under development for large capacity application. However, none of the heaters are designed to have co-existence of fuel fired burners and electric heating elements, a hybrid energy input with both fuel combustion and electricity.

[0003] Several challenges exist when shifting to solely electrical heating. When the electric heating elements and fuel burners are both installed in a heater, the intensive combustion from the burners tends to damage the electrical heating elements due to overheating or carburization. Further, the electric heaters do not directly combust any fuels and will not have any flue gas. The electric heater will not have convection sections, which are traditionally used to capture additional heat for steam generation and feed pre-heating, among other uses. When the electric power is lost, the electric heater will have to be shut down and the plant operation will be interrupted, or equipment damaged, due to sudden operating condition changes.

[0004] Accordingly, there exists a need in the art for heaters that provide operational continuity while also reducing greenhouse gas production.

SUMMARY

[0005] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0006] In one aspect, embodiments disclosed herein relate to an apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burners. The apparatus includes a radiant heating section and a flue gas stack for exhausting the combustion gas to the atmosphere. The radiant section includes one or more process coils, one or more fuel-fired burners for combusting a fuel and producing the combustion gas, where the one or more fuel-fired burners are arranged to provide radiant energy to a first area of the one or more process coils, and one or more electrical heating elements arranged to provide radiant energy to a second area of the one or more process coils. The one or more electrical heating elements are configured to provide 5% or more of a combined maximum energy output of the one or more fuel-fired burners and the one or more electrical heating elements.

[0007] In other aspects, embodiments disclosed herein relate to an apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burner. The apparatus includes a radiant heating section and a flue gas stack for exhausting the combustion gas to the atmosphere. The radiant section includes one or more process coils, one or more fuel-fired burners for combusting a fuel and producing the combustion gas, where the one or more fuel-fired burners are arranged to provide radiant energy to a first side of the one or more process coils, and one or more electrical heating elements arranged to provide radiant energy to a second side of the one or more process coils, where the second side is opposite the first side. The one or more electrical heating elements are configured to provide 5% or more of a combined maximum energy output of the one or more fuel-fired burners and the one or more electrical heating elements.

[0008] In yet another aspect, embodiment disclosed herein relate to an apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burners. The apparatus includes a radiant heating section, a convective heating section configured to receive a combustion gas from the radiant heating section, and a flue gas stack for exhausting the combustion gas to the atmosphere. The radiant section includes one or more process coils, one or more fuel-fired burners for combusting a fuel and producing the combustion gas, where the one or more fuel-fired burners are arranged to provide radiant energy to a first side of the one or more process coils, and one or more electrical heating elements disposed proximate a refractory material of a wall of the radiant heating section located horizontally between the one or more fuel- fired burners and the one or more electrical heating elements and arranged to provide radiant energy to a first side of the one or more process coils, wherein the second side is opposite the first side. The one or more electrical heating elements are configured to provide 5% or more of a combined maximum energy output of the one or more fuel- fired burners and the one or more electrical heating elements.

[0009] Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

[0010] Figures 1A to 10D illustrate various heater designs according to embodiments herein.

DETAILED DESCRIPTION

[0011] In one aspect, embodiments disclosed herein relate to heaters providing a combination of both fuel-fired burners and electrical heating elements. Embodiments herein will have a fuel-fired burner and electrical heating elements in the same chamber and the heater can be operated with the fuel burner, heating elements, or both at the same time.

[0012] A heater for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation/superheat with a combination, or individual operation, of electrical heating elements and fuel-fired burners according to some embodiments herein include a radiant heating section, a convective heating section, and a flue gas stack. The radiant section includes one or more fuel-fired burners, such as including one or both of wall and floor burners, and one or more electrical heating elements, which can be metallic, non-metallic or a combination of metallic and non- metallic, where each of the burners and electric heating elements are arranged and configured to provide radiant heat to one or more process or utility streams (heating coils, radiant coils, or process coils herein) disposed within the radiant section of the heater. The convective section of the heater is configured to receive a combustion gas produced by the fuel-fired burners and, in some embodiments, is further configured to provide convective heat to one or more process or utility streams (convective coils) disposed and arranged within the convective section of the heater. The flue gas stack is configured similar to typical furnaces and receives the (heat-depleted) combustion gas from the convective heating section and for exhausting the combustion gas to the atmosphere.

[0013] In some embodiments, the one or more fuel-fired burners are arranged to provide radiant energy to a first portion or first area of the one or more process coils. Further, the one or more electrical heating elements disposed within the radiant heating section are arranged to provide radiant energy to a second portion or second area of the one or more process coils. For example, in various embodiments the fuel fired burners and electrical heating elements may be arranged to provide heat to different coils, may be arranged vertically within the heater to provide radiant heat to different elevations of the same or different coils, or may be arranged horizontally within the heater to provide radiant heat to different coils or portions different portions of a coil.

[0014] Heating at different elevations may be provided, for example, by disposing electrical heating elements at a lower elevation within the heater and disposing fuel- fired burners vertically above the electrical heating elements. In this manner, the combustion products, which preferentially exhaust upward, may not result in soot or deposition of combustion products on the electrical heating elements. Similarly, design considerations may be provided to prevent undesired interaction between horizontally arranged burners and heating elements, as will be discussed further below.

[0015] In other embodiments, the one or more fuel-fired burners are arranged to provide radiant energy to a first side of the one or more process coils. Further, the one or more electrical heating elements disposed within the radiant heating section are arranged to provide radiant energy to a second side of the one or more process coils. For example, a process coil may be disposed intermediate (between) the one or more fuel-fired burner and the electrical heating elements. Radiant energy from the fuel-fired burners may thus impact and heat the side of the process coils facing the burners, while radiant energy from the electrical heating elements may impact and heat the side of the process coils facing the electrical heating elements.

[0016] In other embodiments, the one or more fuel-fired burners and the one or more electrical heating elements may be disposed within the radiant heating section arranged to provide radiant energy to a same side of the one or more process coils. For example, a fuel-fired burner may be disposed intermediate (between) the one or more electrical heating elements and the process coils.

[0017] Embodiments herein are thus configured and arranged to provide radiant energy to process coils via radiant energy from fuel-fired burners, electrical heating elements, or both burners and heating elements. Such configurations will allow the heater to be operated with fuel firing, or partial fuel firing supplemented by electric heating, or completely with electric heating. The greenhouse gas emission can be reduced and the waste heat from combustion exhaust can be recovered by feedstock preheat or auxiliary stream via the convection section. In case carbon-free fuels like H2 or NH3 are used, there will not be any greenhouse gas emissions from the flue gas stack. More importantly, the heater and associated equipment can stay in operation in the event of a power failure, by operating the fuel-fire burners, or fuel supply shortage, by operating the electrical heating elements.

[0018] As outlined above, embodiments herein may include providing radiant energy directly from an electrical heating element to a process coil. Proper design of a heater may limit or prevent undesired overheating or carburization of the electrical heating elements. Exposure of the electrical heating elements to radiant energy from the burners, as well as exposure of the electrical heating elements to combustion products, may be limited, for example, by design considerations such as: disposal of process coils intermediate the electrical heating elements and burners; proper exhaust funneling (relative arrangement of the burners with the convection section and flue gas stack, flow directing features, etc.); vertical arrangement of heating elements and burners; partial or total shielding of the electrical heating elements via shield walls, shield tiles, or shield tubes; or various combinations of two or more of these design considerations.

[0019] In some embodiments, the heater may not be equipped with a convection section, and may just exhaust combustion gas directly through the flue gas stack. In other embodiments, the hot flue gas may be routed to other heat recovery units such as external gas-fluid heat exchangers or waste heat boilers.

[0020] For example, in some embodiments, the burners and the heating elements are separated by a heating surface where the fuel combustion will be completed before the combustion exhaust can reach the heating surface. As another example, in other embodiments, the heating elements are shielded by a high temperature material where the combustion and its exhaust will not be in direct contact with the heating elements. As another example, the electrical heating elements may be configured to provide varying amounts of heating from one element, or group of elements, to another. In such examples, the heat profile of the heating elements may be non-uniform across either or both the width or height of the furnace. The heating elements may provide uniform heat flux or may be arranged to provide heat in a selected heat flux pattern to meet process requirements. The heating elements disposed throughout areas (floor, lower wall, or upper wall, for example) in a heater may have the same or different mechanical configurations. The heating elements may be installed evenly or in a selected pattern throughout the heater. Embodiments herein may thus provide unique and advantageous arrangements of the fuel-fired burners and electrical heating elements, providing for excellent flexibility in operation of heating by electrical energy, combustion, or both.

[0021] Referring now to the Figures, exemplary embodiments of various configurations of hybrid heaters, including electrical heating elements and fuel-fired burners, are illustrated. In the Figures, like numerals represent like parts.

[0022] Figures 1A (side view) and IB (top view) illustrate a design of a hybrid vertical cylindrical (VC) heater 10 according to embodiments herein. In this embodiment, the heater 10 includes a radiant section 12, a convection section 14, and a flue gas stack (not illustrated). Within radiant section 12, process coils 16 are disposed intermediate floor burners 18 and electrical heating elements 20. The process coil is kept at clearance to (a distance from) the refractory wall 22 of the fire box (radiant section 12). Electric heating elements 20 are installed next to, or on, the refractory wall 22. The fuel-fired burner 18 may include multiple burners, such as 1, 2, 3, 4, or more, such as up to 10, 12, or 16 burners, are installed in the central region of the fire box. The process coils 16 separate the electric heating elements 20 from the burners 18.

[0023] In a typical fuel-fired only VC heater, the process coils are next to the internal insulating material. The combustion energy is transferred to the process coil and the refractory material behind the coil by direct radiation. The energy received by the refractory material is then re-radiated to the side of the coil opposite the burner. The heat transfer intensity by re-radiation is less than the direct radiation from the flame. The front side (flame side) of the coil may thus reach a maximum acceptable tube metal temperature or process fluid film temperature, while the back side is at a much lower temperature.

[0024] In contrast, embodiments herein may provide radiant energy from the electric heating elements to balance the heat input to the process coils, so that both the front side and back side can be under close process and mechanical conditions. In other words, the electrical heating elements may provide sufficient energy such that the front and back sides of the process coils may have similar temperatures and the average heat flux to the coil can be increased. This means, for a given duty to the process, the max tube metal temperature will be reduced, and if the heater is operated near the max tube metal temperature, the heat pickup by the coil can be increased. Further, for the same process duty, less heating surface will be needed because of the optimized heat distribution to the coil. With reduced heating surface area requirements, it may also reduce the process side pressure drop, i.e., the heater may allow a higher capacity compared to a typical VC heater.

[0025] Similar arrangements may also be provided for hybrid box or cabin heaters according to embodiments herein, as illustrated in Figures 2A and 2B. Figure 2A is a single fired box heater, with the coil 16 arranged vertically, while Figure 2B is a single fired cabin heater with the coil 16 arranged horizontally. Similar to the embodiments of Figures 1A and IB, the process coils 16 are disposed intermediate floor burners 18 and electrical heating elements 20. The process coil is kept at clearance to (a distance from) the refractory wall 22 of the fire box (radiant section 12). Electric heating elements 20 are installed next to, or on, the refractory wall 22. Similar advantages in coil heating (front and back), reduction in needed surface area, and reduced pressure drop may also be achieved for box and cabin heaters according to embodiments herein.

[0026] Figures 3A and 3B illustrate hybrid box or cabin heaters according to embodiments herein, where the hybrid heater includes a partition wall 24. The burners 18 can be installed next to the partition wall 24. The partition wall 24 will allow the heat transfer to be conducted differently on different sides of the wall, i.e., the firing can be different on each side of the wall without major impact on the process. Similar to the hybrid designs of Figures 1A/B and 2A/B, in the hybrid design the electric heating elements 20 are installed on the opposite side of the coil, such that the electric heating elements 20 can provide energy as needed. Similar advantages in coil heating (front and back), reduction in needed surface area and reduced pressure drop may also be achieved for box and cabin heaters according to Figures 3 A and 3B.

[0027] While the configurations of Figures 1A-3B provide for use of central floor burners, embodiments herein may also use a combination of floor and wall burners, or just wall burners, as illustrated in Figures 4A-7B. Figures 4A and 4B are each a hybrid design where one side of the coil will be heated by fuel firing, while the other side is by electric heating. Figures 5A and 5B are respectively a box or cabin design with an offset convection section. The radiant coil can be in either vertical arrangement (Figure 5A) or horizontal arrangement (Figure 5B). Similar advantages in coil heating (front and back), reduction in needed surface area, and reduced pressure drop may also be achieved for the embodiments of Figures 4A-5B.

[0028] Figures 6 A and 6B are double fired hybrid designs. If there is a need to have heat input with hybrid heating from both sides (both electrical and fired heating on both sides of a coil), the one or more burners 18 may be installed at a higher elevation and the one or more electrical heating elements 20 at a lower elevation to minimize the possibility of flame impingement to the one or more electrical heating elements 20. The one or more burners 18 are arranged on both sides of the process coil 16, as are the one or more electric heating elements 20. A similar vertical electric heater - burner arrangement may also be provided for a VC heater, as illustrated in Figures 7A (side view) and 7B (top down view), where an interior arrangement of electrical heating elements 20 and burners 18 may be provided around an inner heater casing 28, and an exterior arrangement of electrical heating elements 20 and burners 18 may be provided within an outer heater casing 30. While illustrated with the burners 18 and heating elements 20 a similar distance from the process coil 16, embodiments herein may have the casing associated with the electrical heating elements closer to the process coils than the burners.

[0029] Embodiments herein may also include disposing the electric heaters and burners on the same side of a process coil, such as illustrated for the double fired heater of Figure 8. The burners 18 and the electric heating elements 20 are separated by a mechanical barrier 32, such as a partition wall, tiles, or an enclosure where heating elements reside on the inside. Such mechanical barrier 32 prevents flame impingement on the electrical heating elements 20.

[0030] Further, the electric heating elements and the burners can be on the same side of the heater wall, but separated by partition walls, as shown in Figures 9A-9C (top down views). As illustrated in Figures 9A-9C, the heater may include one or multiple sections with electric heating elements 20 and one or multiple sections with burners 18, where one or both electrical heating elements 20 and burners 18 may be located next to a wall on the same side of the heater. The sections with electric heating element and sections with burners can vary from one section to multiple sections and at different locations on the same side. Partition walls 32 may be provided between the electric heating element sections and the burner sections. The partition wall 32 may extend partially into the heating chamber or may extend from one side to the opposite side and physically separate the heating elements and the burners. The separate chambers may, or may not, have openings on the partition wall to allow furnace atmosphere exchange and balance the pressure among the chambers. Further, the burners may be installed only on one side, Figure 9C. Similar designs as shown in Figures 9A-9C can be applied to any other type of double fired design, including the VC heater as shown in Figures 1A and IB.

[0031] Figures 10A-10D show a few manners in which the electric heating elements may be separated from the burners and the burner flame. As illustrated in Figure 10A, protection tiles 32A may be provided intermediate the burner (not illustrated) and the heating elements 20. The protective tiles 32A may be attached to using tile supports 34A, which may be connected to the refractory insulation 36 or the casing (heater shell) 38, or both. As illustrated in Figure 10B, as opposed to individual protective tiles associated with each heating element, a shielding wall 32B may be provided intermediate the burner (not illustrated) and the heating elements 20, where shielding wall 32B may be held in place with one or more shielding wall supports 34B, such as located at a top and a bottom wall (not illustrated) of the heater. Figures 10C and 10D illustrate similar concepts, where the heating elements 20 are disposed within a shielding tube 32C (Figure 10C) or sectional shielding tubes 32D (Figure 10D).

[0032] The hybrid heaters described herein can be operated with electric power while the burners are in off status, while the electric power is turned off and the burners are fired, or where both the electric and burners are operated at the same time. Further, embodiments herein including multiple burners or multiple electrical heating sections can be operated with less than a total amount of the burners fired, less than a total amount of the electrical heating sections powered, or both burners and heating elements operating at a reduced number. In various embodiments, the burners can be fired at the design capacity or reduced capacity. The burners can also be fired selectively, i.e., different burners are fired differently, or some burners are in off conditions. Further, the heating elements can all be on, or partially on, or powered differently, for optimum heat balance.

[0033] The electrical heating elements may be used, as described above, to supplement and provide additional heat to the back side of process coils. As some energy may still be re-radiated by the refractory material, the number, size, spacing and location of the electrical heating elements may be appropriately designed for a particular heater and process coil arrangement to provide the intended effect of enhanced heating using the hybrid heater.

[0034] Hybrid heaters according to embodiments herein may, as noted above, provide for heating of the process fluid via electrical heat, fuel-fired heat, or both. The amount of heat input via each source may depend upon operating conditions, where during upset, turndown, or maintenance conditions, 100% of heating may be provided via combustion, or 100% of the heating may be provided via electric. During normal operations, however, the total heat input will be provided by a combination of electrical heating elements and fuel fired burners. For such hybrid heating, the electrical heating elements of hybrid heaters herein are designed to provide 5% or more of the combined maximum energy output of the fuel fired burners and heating elements. For example, the electrical heating elements of hybrid heaters herein may provide 5% or more, 8% or more, 10% or more, 15% or more, 20% or more, 30% or more, 40% or more, or even 50% or more of the combined maximum energy output, and up to 15% or less, 20% or less, 25% or less, 30% or less, 40% or less, 50% or less, 60% or less, 70% or less, or 80% or less of the combined maximum energy output, where any lower limit may be combined with any mathematically compatible upper limit.

[0035] Tables 1 and 2 compare conventional heaters to hybrid designs according to embodiments herein. Table 1

Table 2

[0036] As illustrated by the comparisons in Tables 1 and 2, the radiant heat surface can be reduced by about 20-30%, and the CO2 reduction is about 42% on average. Should more electric power be applied to the heater, more CO2 will be reduced. With more electric energy input and reduced fuel firing requirement, the associated operating plant may also become self-sufficient on non-carbon bearing fuel and can operate the heater with zero CO2 emissions. [0037] Embodiments herein also envision revamping existing heaters to provide hybrid heating capability. For example, for heaters in which a coil is disposed proximate refractory material, electrical heating elements may be disposed intermediate the process coil and the refractory material. The process coil may be moved, if necessary, to provide room for the electrical heating elements.

[0038] As described above, embodiments herein provide hybrid heaters, allowing for hybrid heating by fuel and electricity. Embodiments herein may also provide for operational flexibility for operating with fuel or electricity independently. Embodiments of the present disclosure may thus provide advantages in one or more of increased heater capacity, reduced heater surface area, reduced process fluid pressure drop, reduced CO2 emissions, process continuity during fuel or electricity upsets, among other advantages. Further, embodiments herein may provide adaptability to operate more effectively at turndown conditions.

[0039] Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

Claims

CLAIMS What is claimed:

1. An apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burners comprising: a radiant heating section and a flue gas stack for exhausting a combustion gas to the atmosphere; one or more process coils disposed within the radiant heating section; one or more fuel-fired burners disposed within the radiant heating section, the one or more fuel-fired burners configured for combusting a fuel and producing the combustion gas, wherein the one or more fuel-fired burners are arranged to provide a first radiant energy to a first area of the one or more process coils; and one or more electrical heating elements disposed within the radiant heating section, the one or more electrical heating elements arranged to provide a second radiant energy to a second area of the one or more process coils; wherein the one or more electrical heating elements are configured to provide 5% or more of a combined maximum energy output of the one or more fuel-fired burners and the one or more electrical heating elements.

2. The apparatus of claim 1, wherein the one or more fuel-fired burners include one or more floor burners, one or more wall burners, or a combination of floor and wall burners.

3. The apparatus of claim 1, wherein the one or more fuel-fired burners are wall burners disposed vertically above the one or more electrical heating elements.

4. The apparatus of claim 1, further comprising a shielding wall disposed intermediate the one or more fuel-fired burners and the one or more electrical heating elements.

5. The apparatus of claim 4, wherein the shielding wall comprises one or more shielding walls disposed intermediate a section of one or more fuel-fired burners and a section of one or more electrical heating elements.

6. The apparatus of claim 5, wherein the one or more shielding walls are disposed on one side of a radiant heating section and extend partially from an outer wall of the radiant heating section toward an interior of the radiant heating section.

7. The apparatus of claim 5, wherein the one or more shielding walls are disposed on both sides of the radiant heating section and extend partially from an outer wall of the radiant heating section toward an interior of the radiant heating section.

8. The apparatus of claim 5, wherein the one or more shielding walls are disposed on both sides of radiant heating section and extend from a first side of an outer wall of the radiant heating section to a second side of the outer wall of the radiant heating section, the one or more shield walls comprising a plurality of holes extending through the one or more shielding walls.

9. An apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burners comprising: a radiant heating section and a flue gas stack for exhausting a combustion gas to the atmosphere; one or more process coils disposed within the radiant heating section; one or more fuel-fired burners disposed within the radiant heating section, the one or more fuel-fired burners configured for combusting a fuel and producing the combustion gas, wherein the one or more fuel-fired burners are arranged to provide a first radiant energy to a first side of the one or more process coils; and one or more electrical heating elements disposed within the radiant heating section, the one or more electrical heating elements arranged to provide a second radiant energy to a second side of the one or more process coils, wherein the second side is opposite the first side, wherein the second radiant energy is 5% or more of a combined maximum energy output of the one or more fuel-fired burners and the one or more electrical heating elements.

10. The apparatus of claim 9, wherein the one or more fuel-fired burners include one or more floor burners, one or more wall burners, or a combination of floor and wall burners.

11. The apparatus of claim 9, wherein the one or more fuel-fired burners are wall burners disposed vertically above the one or more electrical heating elements.

12. The apparatus of claim 11, further comprising a shielding wall disposed intermediate the one or more fuel-fired burners and the one or more electrical heating elements.

13. The apparatus of claim 9, wherein the one or more process coils are disposed in a circular arrangement in the radiant heating section, the one or more electrical heating elements are disposed between the one or more process coils and a refractory wall of the radiant heating section, and the one or more fuel-fired burners are disposed proximate a center of the radiant heating section.

14. The apparatus of claim 13, wherein the one or more process coils are oriented vertically within the radiant heating section.

15. The apparatus of claim 13, wherein the one or more process coils are oriented horizontally within the radiant heating section.

16. The apparatus of claim 13, further comprising a partition wall disposed proximate a center of the radiant heating section and the one or more fuel-fired burners disposed circumferentially around the partition wall.

17. An apparatus for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation with a combination, or individual operation, of electrical elements and fired burners comprising: a radiant heating section and a flue gas stack for exhausting the combustion gas to the atmosphere; one or more process coils disposed proximate a center of the radiant heating section; one or more fuel-fired burners disposed within the radiant heating section and circumferentially around the one or more process coils, the one or more fuel-fired burners configured for combusting a fuel and producing the combustion gas, wherein the one or more fuel-fired burners are arranged to provide a first radiant energy to a first side of the one or more process coils; and one or more electrical heating elements disposed within the radiant heating section and proximate a refractory material of a wall of the radiant heating section located horizontally between the one or more fuel-fired burners and the one or more electrical heating elements, the one or more electrical heating elements arranged to provide a second radiant energy to the first side of the one or more process coils, wherein the second side is opposite the first side; wherein the one or more electrical heating elements are configured to provide 5% or more of a combined maximum energy output of the one or more fuel-fired burners and the one or more electrical heating elements.

18. The apparatus of claim 17, further comprising a shielding wall disposed intermediate the one or more fuel-fired burners and the one or more electrical heating elements.

19. The apparatus of claim 17, wherein the one or more process coils are oriented vertically within the radiant heating section.