Process and apparatus for heating a process fluid

Abstract

A process and apparatus for heating a process fluid. The process fluid flows through a convection section and then a radiant section. The radiant section produces heat and flue gases from the combustion of a fuel. The flue gases flow into the convection section, where they provide heat. The conduits in the convection section are straight. All of the fluid passing through the convection section also passes through the radiant section.

Description

[Technical Field]

[0001] (Priority statement) This application claims priority to U.S. Provisional Patent Application No. 63 / 382,147, filed November 3, 2022, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present invention relates generally to processes and apparatus for heating process fluids, and more particularly to processes and apparatus for treating fluids containing hydrocarbons that are reactants in one or more desired chemical reactions. [Background technology]

[0003] A combustion heater is a common process unit in chemical plants that heats a process stream to a reaction temperature. The combustion heater has a radiant section with one or more burners configured to provide heat to a process fluid in tubes extending through the radiant section. The process stream is heated, allowing endothermic reactions involving hydrocarbons in the process fluid to occur.

[0004] The convection section of a fired heater is located adjacent to, and typically above, the radiant section and receives hot flue gas from the radiant section. The convection section is typically used to improve overall heater efficiency by transferring heat to water in tubes extending through the convection section for steam generation. However, heat input to the heater is based on the process heating required in the radiant section. Thus, in some heaters that generate large amounts of heat and consume large amounts of fuel, the amount of heat generated far exceeds the heat required to generate steam. This excess heat is lost or otherwise unused.

[0005] Therefore, while utilizing flue gas to generate steam improves overall heater efficiency, it is desirable to more effectively and efficiently use the convection section of a fired heater to improve primary fuel efficiency and thus reduce fuel burn. Summary of the Invention

[0006] One or more devices and processes have been invented that can utilize the heat of flue gas in the convection section for process heating instead of steam generation. It would be expected that the pressure drop associated with passing the process fluid through the convection section would not allow for such a design. Surprisingly, however, it has been discovered that a configuration exists that allows the process fluid to be heated in the convection section (and the radiant section) without being adversely affected by the pressure drop. Utilizing the convection section to heat the process fluid allows the size of the radiant section to be reduced. As will be appreciated, this reduces fuel consumption and carbon dioxide production. Such benefits can be achieved in new or retrofitted fired heaters.

[0007] Thus, in at least one aspect, the present invention can be characterized as providing an apparatus for heating a process fluid, the apparatus including: a radiant section having one or more burners configured to provide heat and flue gas; a convection section disposed adjacent to and above the radiant section and configured to receive flue gas from the radiant section; a convection conduit configured to pass through the convection section and receive and transfer heat to the process fluid; and a radiant conduit configured to pass through the radiant section and receive and transfer heat to the process fluid. The convection conduit and radiant conduit are arranged in series such that all of the process fluid passing through the convection conduit passes through the radiant conduit.

[0008] The radiation conduit may be a multi-pass coil conduit.

[0009] The convection conduit may be a straight conduit with no bends.

[0010] A plurality of parallel conduits may be provided, each convection conduit configured to pass through the convection section, receive the process fluid, and transfer heat to the process fluid.

[0011] The apparatus may also include a first convection manifold and a second convection manifold, and the plurality of parallel convection conduits may extend between the first convection manifold and the second convection manifold.

[0012] The apparatus may also include a bypass conduit configured to bypass a portion of the process fluid around the convection section. A first radiant manifold and a second radiant manifold may be provided. The radiant conduit may extend between the first radiant manifold and the second radiant manifold. The first radiant manifold may be configured to receive the process fluid from the convection conduit. The first radiant manifold may also be configured to receive the process fluid from the bypass conduit.

[0013] The radiant section may have multiple heating zones, each operating at a temperature independent of the temperatures of the other heating zones. The convection conduit may be positioned such that the inlet of the convection conduit is above a heating zone having a higher temperature compared to a heating zone below the outlet of the convection conduit.

[0014] In one or more aspects, the invention can be generally characterized as providing a method of heating a process fluid by burning a fuel in a radiant section of an apparatus to produce heat and flue gases; passing the process fluid through a convection section to heat the process fluid, the convection section receiving the flue gases from the radiant section; and passing the process fluid through the radiant section to heat the process fluid, wherein the process fluid passing through the radiant section has passed through the convection section.

[0015] The method may also include bypassing a portion of the process fluid around the convection section. The portion of the process fluid that bypasses the convection section may be combined with the process fluid that is routed to the convection section.

[0016] The method may also include adjusting the amount of the portion of the process fluid that bypasses the convection section.

[0017] The convection section may include at least one convection conduit, which may be a straight conduit. The radiant section may include multiple heating zones, each operating at a temperature independent of the temperatures of the other heating zones. The at least one convection conduit may be positioned such that an inlet of the at least one convection conduit is above a heating zone having a higher temperature compared to a heating zone below an outlet of the at least one convection conduit.

[0018] The radiating section may include at least one convection conduit, which may be a multi-pass coil conduit.

[0019] The process fluid may be from a hydrocarbon reforming zone.

[0020] Further aspects, embodiments, advantages and details of the invention, all of which may be combined in any manner, are set out in the detailed description of the invention below. [Brief explanation of the drawings]

[0021] One or more exemplary embodiments of the invention are described below in conjunction with the following drawing figures. [Figure 1] 1 is a schematic diagram of an apparatus for heating a process fluid, in accordance with one or more embodiments of the present invention. [Figure 2] 2 is another schematic diagram of an apparatus for heating a process fluid in accordance with one or more embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] As discussed above, the present invention relates to a method and apparatus that uses both a radiant section and a convective section to heat a process fluid. This is a more direct method of heating the process fluid. In addition to improved efficiency, this allows the heater to be smaller, consume less fuel, and produce less carbon dioxide. Additionally, the apparatus and method of the present invention reduces the pressure drop associated with heating the process fluid, so that the heater can be utilized in processes with lower operating pressures (and higher temperatures). Therefore, the yield of the desired chemical reaction is not affected.

[0023] With these general principles in mind, one or more embodiments of the invention are described below with the understanding that the description is not intended to be limiting.

[0024] 1, an apparatus 10 for heating a process fluid 12, such as a fired heater or charge heater, includes a radiant section 14 and a convection section 16. While the process fluid 12 is not necessarily limited to a particular desired reaction, the present invention is believed to be particularly advantageous in reforming, dehydrogenation, isomerization, disproportionation, and transalkylation, as well as the conversion of alcohols to hydrocarbon fuels.

[0025] The radiant section includes one or more burners 18 that receive oxygen and a fuel, such as fuel gas and / or fuel oil, and enable combustion of the fuel to produce heat and flue gases (and a flame). The heat from the radiant section is used to heat the process fluid 12 contained in one or more radiant conduits 20 that pass through the radiant section 14 to provide a heated process fluid 22.

[0026] The radiant conduit comprises a multi-pass coil conduit that includes bends or turns to increase the residence time of the process fluid within the radiant section 14. For example, the multi-pass coil conduit may be a U coil, an arbor coil, an I, a double I, a W coil, a twin U, a serpentine, a spiral, or other such configuration.

[0027] The convection section 16 is positioned adjacent to the radiant section 14 such that hot flue gas from the radiant section 14 is received into the convection section 16. For example, the convection section 16 may be above or to the side of the radiant section 14.

[0028] One or more convection conduits 24 extend through the convection section 16 and, unlike conventional designs, the convection conduits 24 are configured to receive the process fluid 12, transfer heat from the flue gas to the process fluid 12, and provide preheated process fluid 25. It is contemplated that multiple parallel conduits 24 may be utilized. To reduce any pressure drop, the convection conduits 24 are preferably straight conduits without bends.

[0029] The convection conduit 24 and the radiant conduit 20 are arranged in series such that all of the process fluid 12 passing through the convection conduit 24, and therefore the convection section 16, i.e., all of the preheated process fluid 25, passes through the radiant conduit 20, and therefore the radiant section 14, before being recovered as heated process fluid 22.

[0030] The apparatus 10 may further include a first convection manifold 26 and a second convection manifold 28, with the convection conduit 24 extending therebetween. The first convection manifold 26 may be an inlet convection manifold that distributes the process fluid 12 to the convection conduit 24. The second convection manifold 28 may be an outlet convection manifold that provides the preheated process fluid 25.

[0031] A bypass conduit 30 may be provided to allow for temperature control associated with the system and also to address or reduce pressure drop issues. The bypass conduit allows a portion of the process fluid 12 to bypass the convection section 16. A valve 32 or other device, such as an orifice or turbine, may be provided to control or regulate the flow of fluid in the bypass conduit 30.

[0032] The apparatus 10 may also include a first radiant manifold 34 and a second radiant manifold 36, with the radiant conduit 20 extending therebetween. The first radiant manifold 34 may be an inlet radiant manifold that allows the process fluid 12 from the bypass conduit 30 and the preheated process fluid 25 from the convection section 16 to mix and distribute to the radiant conduit 20. The second radiant manifold 36 may be an outlet radiant manifold that provides the heated process fluid 22 from the apparatus 10. Additionally, the sizes of the radiant manifolds 34, 36 may be adjusted to reduce the high temperature volume and reduce the need for auxiliary heaters.

[0033] Referring to FIG. 2, the radiant section 14 of the apparatus 10 includes multiple heating zones 40a, 40b, and 40c. It should be understood that the number of heating zones 40a, 40b, and 40c shown is merely exemplary. Each of the heating zones 40a, 40b, and 40c has a radiant conduit 20 that receives a process fluid 12. However, the process fluids may be different. For example, one heating zone 40a may be a charge heater, and the process fluid 12 passed therethrough may be a feed stream. The second heating zone 40b may be a first interstage heater, and the process fluid 12 passed therethrough may be an effluent from a first reactor. The third heating zone 40c may be a second interstage heater, and the process fluid 12 passed therethrough may be an effluent from a second reactor. Each heating zone 40a, 40b, and 40c operates at a temperature that is independent of the temperatures of the other heating zones 40a, 40b, and 40c. Thus, the heating zones 40a, 40b, 40c may all have different operating temperatures. To reduce concerns about metal catalyst coking in the convection conduit 24, the convection conduit 24 is positioned such that the inlet 42 of the convection conduit 24 is above the heating zone 40a having a higher temperature compared to the heating zone 40c below the outlet 44 of the convection conduit 24. In other words, the flow through the convection section 16 is positioned from hot to cold relative to the heating zones 40a, 40b, 40c below the convection conduit 24. In such a radiant section, all of the preheated process fluid 25 is typically routed to one of the heating zones 40a, 40b, 40c within the radiant section 14.

[0034] An exemplary process for heating a process fluid 12 will now be described with reference to both Figures 1 and 2 .

[0035] A fuel, such as fuel gas and / or fuel oil, is combusted in the radiant section 14, and the apparatus 10 produces heat and flue gas. At least a portion of the process fluid 12 passes through the convection section 16 to provide preheated process fluid 25. The convection section 16 receives flue gas from the radiant section 14 to provide heat to the process fluid within the convection section 16. All of the process fluid that passes through the convection section 16, i.e., the preheated process fluid 25, is sent to the radiant section 14.

[0036] A portion of the process fluid 12 may be bypassed around the convection section 16 in a bypass conduit 30. Thus, the portion of the process fluid 12 that bypasses the convection section 16 may be combined with the preheated process fluid 25. The amount of process fluid 12 passing through the bypass conduit 30 may be adjusted, for example, by adjusting a valve 32 in the bypass conduit 30.

[0037] As mentioned above, these provide benefits by more efficiently utilizing the heat generated by the combustion of fuel in the radiant section, which can result in a smaller heater and reduced fuel consumption and carbon dioxide output. Additionally, a further feature of the present invention reduces concerns regarding pressure drop and metal catalyst coking.

[0038] experiment In a theoretical comparison based on using a convection section to heat the process stream for an 87,000 BPSD process, the process and apparatus using the present invention demonstrated a 21% reduction in carbon dioxide emissions. In a process having 50% of the 87,000 BPSD, the present process demonstrated a 22.5% reduction in carbon dioxide reduction.

[0039] Those skilled in the art should appreciate and understand that various other components, such as valves, pumps, filters, coolers, etc., are not shown in the drawings because their details are well within the knowledge of those skilled in the art and their description is not necessary to practice or understand embodiments of the present invention.

[0040] Any of the above lines, conduits, units, devices, vessels, ambient environments, zones, or the like may be equipped with one or more monitoring components, including sensors, measurement devices, data acquisition devices, or data transmission devices. Signals, process, or condition measurements and data from the monitoring components may be used to monitor conditions in, around, and on the process equipment. Signals, measurements, and / or data generated or recorded by the monitoring components may be collected, processed, and / or transmitted over one or more networks or connections, which may be private or public, general or specific, direct or indirect, wired or wireless, encrypted or unencrypted, and / or combinations thereof. This specification is not intended to be limiting in this respect.

[0041] Signals, measurements, and / or data generated or recorded by the monitoring components may be transmitted to one or more computing devices or systems. The computing devices or systems may include at least one processor and memory storing computer-readable instructions that, when executed by the at least one processor, cause the one or more computing devices to perform a process, which may include one or more steps. For example, the one or more computing devices may be configured to receive data related to at least one piece of equipment associated with the process from one or more monitoring components. The one or more computing devices or systems may be configured to analyze the data. Based on the analysis of the data, the one or more computing devices or systems may be configured to determine one or more recommended adjustments to one or more parameters of one or more processes described herein. The one or more computing devices or systems may be configured to transmit encrypted or unencrypted data including one or more recommended adjustments to one or more parameters of one or more processes described herein.

[0042] Specific Embodiments While the following will be described in conjunction with specific embodiments, it will be understood that this description is illustrative, but not intended to limit the scope of the preceding description and appended claims.

[0043] A first embodiment of the present invention is an apparatus for heating a process fluid, the apparatus including: a radiant section having one or more burners configured to provide heat and flue gas; a convection section disposed adjacent to the radiant section and configured to receive flue gas from the radiant section; a convection conduit passing through the convection section and configured to receive and transfer heat to the process fluid; and a radiant conduit passing through the radiant section and configured to receive and transfer heat to the process fluid, the convection conduit and the radiant conduit being arranged in series such that all of the process fluid passing through the convection conduit passes through the radiant conduit. An embodiment of the present invention is one, any, or all of the first embodiment through the previous embodiment of this paragraph, wherein the radiant conduit further comprises a multi-pass coil conduit. An embodiment of the present invention is one, any, or all of the first embodiment through the previous embodiment of this paragraph, wherein the convection conduit further comprises a straight conduit without bends. An embodiment of the present invention is one, any, or all of the first embodiment to the previous embodiment of this paragraph, further comprising a first convection manifold and a second convection manifold, wherein the plurality of parallel convection conduits extend between the first convection manifold and the second convection manifold.An embodiment of the present invention is one, any, or all of the first embodiment to the previous embodiment of this paragraph, further comprising a bypass conduit configured to bypass a portion of the process fluid around the convection section. An embodiment of the present invention is one, any, or all of the first embodiment in this paragraph to the previous embodiment in this paragraph, further comprising a first radiation manifold and a second radiation manifold, and the radiation conduit extends between the first radiation manifold and the second radiation manifold.An embodiment of the present invention is one, any, or all of the first embodiment through the previous embodiment of this paragraph, in which the first radiant manifold is configured to receive the process fluid from the convection conduit. An embodiment of the present invention is one, any, or all of the first embodiment through the previous embodiment of this paragraph, in which the first radiant manifold is further configured to receive the process fluid from the bypass conduit. An embodiment of the present invention is one, any, or all of the first embodiment through the previous embodiment of this paragraph, in which the radiant section has multiple heating zones, each heating zone operating at a temperature independent of the temperatures of the other heating zones. An embodiment of the present invention is one, any, or all of the first embodiment through the previous embodiment of this paragraph, in which the convection conduit is positioned such that an inlet of the convection conduit is above a heating zone having a higher temperature compared to a heating zone below an outlet of the convection conduit.

[0044] A second embodiment of the present invention is a method of heating a process fluid, the method comprising: combusting fuel gas and / or fuel oil in a radiant section of an apparatus to generate heat and flue gas; passing the process fluid through a convection section to heat the process fluid, the convection section receiving flue gas from the radiant section; and passing the process fluid through the radiant section to heat the process fluid, the process fluid passing through the radiant section having passed through the convection section. An embodiment of the present invention is any one, any, or all of the second embodiment through the previous embodiment of this paragraph, further comprising bypassing a portion of the process fluid around the convection section. An embodiment of the present invention is any one, any, or all of the second embodiment through the previous embodiment of this paragraph, further comprising combining a portion of the process fluid that bypassed the convection section with the process fluid sent to the convection section. An embodiment of the present invention is any one, any, or all of the second embodiment through the previous embodiment of this paragraph, further comprising adjusting the amount of the portion of the process fluid that bypassed the convection section. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiment of this paragraph, where the convection section includes at least one convection conduit, and where the at least one convection conduit includes a straight conduit.An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiment of this paragraph, where the radiant section has multiple heating zones, each heating zone operating at a temperature independent of the temperatures of the other heating zones.An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiment of this paragraph, where the at least one convection conduit is positioned such that an inlet of the at least one convection conduit is above a heating zone having a higher temperature compared to a heating zone below an outlet of the at least one convection conduit.An embodiment of the present invention is one, any, or all of the second embodiment of this paragraph through the preceding embodiment of this paragraph, where the radiant section includes at least one convection conduit, and the at least one convection conduit includes a multi-pass coil conduit.An embodiment of the present invention is one, any, or all of the second embodiment of this paragraph through the preceding embodiment of this paragraph, where the process fluid is from a hydrocarbon reforming zone.

[0045] Without further elaboration, it is believed that, using the preceding description, one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of the present invention, and can make various changes and modifications to the present invention to adapt it to various uses and conditions, without departing from the spirit and scope of the present invention. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0046] Above, all temperatures are set forth in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

[0047] While at least one exemplary embodiment has been presented in the foregoing detailed description of the present invention, it should be understood that numerous variations exist. It should also be understood that the exemplary embodiment(s) are merely examples and are in no way intended to limit the scope, applicability, or configuration of the present invention. Rather, the foregoing detailed description provides those skilled in the art with a convenient guide for implementing exemplary embodiments of the present invention, and it should be understood that various changes can be made in the functions and arrangement of elements described in the exemplary embodiment without departing from the scope of the present invention as set forth in the appended claims and their legal equivalents.

Claims

1. An apparatus (10) for heating a process fluid (12), comprising: a radiant section (14) having one or more burners (18) configured to provide heat and flue gases; a convection section (16) disposed adjacent to the radiant section (14) and configured to receive the flue gas from the radiant section (14); a convection conduit (24) configured to pass through the convection section (16) and receive the process fluid (12) and transfer heat to the process fluid (12); a radiant conduit (20) configured to pass through the radiant section (14) and receive the process fluid (12) and transfer heat to the process fluid (12); The convection conduit (24) and the radiant conduit (20) are arranged in series such that all of the process fluid (12) passing through the convection conduit (24) passes through the radiant conduit (20).

2. The apparatus (10) of claim 1, wherein the radiation conduit (20) comprises a multi-pass coil conduit.

3. The apparatus (10) of claim 1, wherein the convection conduit (24) comprises a straight conduit without bends.

4. 2. The apparatus (10) of claim 1, comprising a plurality of parallel convection conduits (24), each convection conduit (24) configured to pass through the convection section (16), receive the process fluid (12), and transfer heat to the process fluid (12).

5. 5. The apparatus (10) of claim 4, further comprising a first convection manifold (26) and a second convection manifold (28), wherein the plurality of parallel convection conduits (24) extend between the first convection manifold (26) and the second convection manifold (28).

6. The apparatus (10) of claim 1, further comprising a bypass conduit (30) configured to bypass a portion of the process fluid (12) around the convection section (16).

7. 7. The apparatus (10) of claim 6, further comprising a first radiant manifold (34) and a second radiant manifold (36), the radiant conduit (20) extending between the first radiant manifold (34) and the second radiant manifold (36).

8. 8. The apparatus (10) of claim 7, wherein the first radiant manifold (34) is configured to receive the process fluid (12) from the convection conduit (24), and the first radiant manifold (34) is further configured to receive the process fluid from the bypass conduit (30).

9. the radiant section (14) has a plurality of heating zones (40a, 40b, 40c), each of which operates at a temperature independent of the temperatures of the other heating zones (40a, 40b, 40c); 9. The apparatus (10) of claim 1, wherein the convection conduit (24) is positioned such that an inlet (42) of the convection conduit (24) is above a heating zone (40a, 40b, 40c) having a higher temperature compared to a heating zone (40a, 40b, 40c) below an outlet (44) of the convection conduit (24).

10. A method of heating a process fluid (12), comprising: Combusting fuel in a radiant section (14) of the apparatus (10) to produce heat and flue gases; Passing a process fluid (12) through a convection section (16) to heat the process fluid (12), the convection section (16) receiving the flue gas from the radiant section (14); Passing the process fluid (12) through the radiant section (14) to heat the process fluid (12), the process fluid (12) passing through the radiant section (14) has passed through the convective section (16).

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