Method and apparatus for heating process fluid

Abstract

A method and apparatus for heating a process fluid. The process fluid flows through the convection section and then through the radiating section. The radiating section produces heat and flue gas from combustion of the fuel. The flue gas flows to the convection section to provide heat in the convection section. The conduit in the convection section is straight. All fluid passing through the convection section also passes through the radiating section.

Description

[0001] Priority Claim

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 382,147, filed on November 3, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0003] The present invention generally relates to methods and apparatus for heating process fluids, and more particularly to methods and apparatus for process fluids containing hydrocarbons that are reactants in one or more desired chemical reactions. Background Art

[0004] Flame heaters are common process units in chemical plants and heat process streams to reaction temperatures. Flame heaters have a radiant section that has one or more burners configured to provide heat to a process fluid in tubes extending through the radiant section. Heating the process stream allows endothermic reactions associated with the hydrocarbons in the process fluid to occur.

[0005] The convective section of a flame heater is positioned adjacent (usually above) the radiant section and receives hot flue gas from the radiant section. The convective section is typically used for steam generation to improve overall heater efficiency by transferring heat to water in tubes extending through the convective section. However, the heat input to the heater is based on the process heating required in the radiant section. Thus, in some heaters that generate a large amount of heat and consume a large amount of fuel, the heat generated far exceeds the heat required to generate steam. This excess heat is lost or not utilized.

[0006] Accordingly, while using flue gas to generate steam improves overall heater efficiency, it is desirable to use the convective section of a flame heater more effectively and efficiently to improve primary fuel efficiency and thereby reduce fuel combustion. Summary of the Invention

[0007] One or more devices and methods have been invented in which the heat of the flue gas in the convective section can be used for process heating rather than steam generation. It would be expected that the pressure drop associated with passing the process fluid through the convective section would not allow such a design. However, it has surprisingly been found that there are arrangements that allow the process fluid to be heated in the convective section (and the radiant section) without being adversely affected by the pressure drop. Using the convective section to heat the process fluid would allow the size of the radiant section to be reduced. It should be understood that this reduces fuel consumption and carbon dioxide production. Such benefits can be achieved in new or improved flame heaters.

[0008] Accordingly, in at least one aspect, the features of the present invention may lie in providing an apparatus for heating a process fluid. The apparatus includes: a radiant section having one or more burners configured to provide heat and flue gas; a convection section disposed above and adjacent to the radiant section and configured to receive the flue gas from the radiant section; a convection conduit passing through the convection section and configured to receive the process fluid and transfer heat to the process fluid; and a radiant conduit passing through the radiant section and configured to receive the process fluid and transfer heat to the process fluid. The convection conduit and the radiant conduit are arranged in series such that all of the process fluid passing through the convection conduit passes through the radiant conduit.

[0009] The radiant conduit may be a multi-channel coiled conduit.

[0010] The convection conduit may be a straight conduit without bends.

[0011] A plurality of parallel convection conduits may be provided, each of which passes through the convection section and is configured to receive the process fluid and transfer heat to the process fluid.

[0012] The apparatus may further include a first convection manifold and a second convection manifold. The plurality of parallel convection conduits may extend between the first convection manifold and the second convection manifold.

[0013] The apparatus may further 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 also 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.

[0014] The radiant section may have a plurality of heating zones, each of which operates at a temperature independent of the temperature of the other heating zones. The convection conduit may be arranged such that the inlet of the convection conduit is above a heating zone that has a higher temperature compared to the heating zone below the outlet of the convection conduit.

[0015] In one or more aspects, the features of the present invention generally may lie in providing a method for heating a process fluid by: burning fuel in the radiant section of the apparatus to generate heat and flue gas; passing the process fluid through the convection section to heat the process fluid, the convection section receiving the flue gas 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.

[0016] The method may further include bypassing a portion of the process fluid around the convective section. The portion of the process fluid bypassing the convective section may be combined with the process fluid being delivered to the convective section.

[0017] The method may further include adjusting the amount of the portion of the process fluid bypassing the convective section.

[0018] The convective section may include at least one convective conduit, and the at least one convective conduit may be a straight conduit. The radiant section may include a plurality of heating zones, where each heating zone operates at a temperature independent of the temperature of the other heating zones. At least one convective conduit may be arranged such that an inlet of the at least one convective conduit is above a heating zone that has a higher temperature than a heating zone below an outlet of the at least one convective conduit.

[0019] The radiant section may include at least one convective conduit, and the at least one convective conduit may be a multi-channel coil conduit.

[0020] The process fluid may be from a hydrocarbon reforming zone.

[0021] Additional aspects, embodiments, advantages, and details of the present invention (all of which can be combined in any way) are set forth in the following detailed description of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] One or more exemplary embodiments of the present invention will be described below in conjunction with the following drawings, in which:

[0023] Figure 1 is a schematic diagram of an apparatus for heating a process fluid according to one or more aspects of the present invention; and,

[0024] Figure 2 is another schematic diagram of an apparatus for heating a process fluid according to one or more aspects of the present invention. DETAILED DESCRIPTION

[0025] As described above, the present invention relates to methods and apparatuses for heating a process fluid using both a radiant section and a convective section. This is a more direct way of heating a process fluid. In addition to improving efficiency, this allows the heater to be smaller, consume less fuel, and produce less carbon dioxide. Additionally, the present apparatus and method reduce the pressure drop associated with heating the process fluid, such that the heater can be used in processes with lower operating pressures (and higher temperatures). Thus, the yield of the desired chemical reaction is not affected.

[0026] With these general principles in mind, one or more embodiments of the present invention will be described with the understanding that the following description is not intended to be limiting.

[0027] As Figure 1As shown, the apparatus 10 for heating a process fluid 12 (such as a fired heater or a charge heater) includes a radiant section 14 and a convection section 16. Although the process fluid 12 need not be limited to a particular desired reaction, the present invention is considered to be particularly advantageous in reforming, dehydrogenation, isomerization, disproportionation, and transalkylation, as well as the conversion of alcohols to hydrocarbon fuels.

[0028] The radiant section includes one or more burners 18 that receive oxygen and fuel (such as fuel gas and / or fuel oil), permit combustion of the fuel, and generate heat and flue gas (as well as flames). The heat in the radiant section is used to heat the process fluid 12 (which is contained within one or more radiant conduits 20 passing through the radiant section 14) and provide a heated process fluid 22.

[0029] Wherein the radiant conduits include multi-channel coil conduits that include bends or turns to increase the residence time of the process fluid within the radiant section 14. For example, the multi-channel coil conduits can be U-shaped coils, mandrel coils, I-shaped, double I-shaped, W-shaped coils, double U-shaped, serpentine, helical, or other such configurations.

[0030] The convection section 16 is disposed adjacent to the radiant section 14 such that the hot flue gas from the radiant section 14 is received within the convection section 16. For example, the convection section 16 can be above or laterally beside the radiant section 14.

[0031] 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 and transfer heat from the flue gas to the process fluid 12 and provide a preheated process fluid 25. The use of multiple parallel convection conduits 24 is contemplated. To reduce any pressure drop, the convection conduits 24 are preferably straight conduits that do not include bends.

[0032] The convection conduits 24 and the radiant conduits 20 are arranged in series such that all of the process fluid 12 passing through the convection conduits 24 and thus through the convection section 16 (i.e., all of the preheated process fluid 25) passes through the radiant conduits 20 and thus through the radiant section 14 before being recovered as the heated process fluid 22.

[0033] The apparatus 10 may also include a first convection manifold 26 and a second convection manifold 28, with the convection conduits 24 extending therebetween. The first convection manifold 26 can be an inlet convection manifold that distributes the process fluid 12 to the convection conduits 24. The second convection manifold 28 can be an outlet convection manifold that provides the preheated process fluid 25.

[0034] To allow for temperature control associated with the system and to further address or reduce pressure drop issues, a bypass conduit 30 can be provided. The bypass conduit allows a portion of the process fluid 12 to bypass the convective section 16. A valve 32 or other device (such as an orifice or turbine) can be provided to control or adjust the fluid flow in the bypass conduit 30.

[0035] The apparatus 10 can also include a first radiant manifold 34 and a second radiant manifold 36, with radiant conduits 20 extending therebetween. The first radiant manifold 34 can be an inlet radiant manifold that allows the process fluid 12 from the bypass conduit 30 and the preheated process fluid 25 from the convective section 16 to mix and be distributed to the radiant conduits 20. The second radiant manifold 36 can 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 can be adjusted to reduce the thermal volume and reduce the need for auxiliary heaters.

[0036] Diversion Figure 2 , the radiant section 14 of the apparatus 10 includes a plurality of heating zones 40a, 40b, 40c. It should be understood that the number of the depicted heating zones 40a, 40b, 40c is merely exemplary. Each heating zone 40a, 40b, 40c has a radiant conduit 20 that receives the process fluid 12; however, the process fluids can be different. For example, one heating zone 40a can be a charge heater, and the process fluid 12 flowing into it can be a feed stream. The second heating zone 40b can be a first inter-stage heater, and the process fluid 12 flowing into it can be the effluent from the first reactor. The third heating zone 40c can be a second inter-stage heater, and the process fluid 12 flowing into it can be the effluent from the second reactor. Each heating zone 40a, 40b, 40c operates at a temperature independent of the temperatures of the other heating zones 40a, 40b, 40c. Thus, all the heating zones 40a, 40b, 40c can have different operating temperatures. To reduce concerns about metal-catalyzed coking in the convective conduit 24, the convective conduit 24 is arranged such that the inlet 42 of the convective conduit 24 is above the heating zone 40a, which has a higher temperature compared to the heating zone 40c below the outlet 44 of the convective conduit 24. In other words, the flow through the convective section 16 is arranged from hot to cold relative to the heating zones 40a, 40b, 40c below the convective conduit 24. In such a radiant section, all the preheated process fluid 25 is typically transferred to one of the heating zones 40a, 40b, 40c in the radiant section 14.

[0037] Reference Figure 1 and Figure 2 Both, an exemplary process for heating the process fluid 12 will be described.

[0038] Fuel (such as fuel gas and / or fuel oil) is burned in the radiant section 14 of the apparatus 10 to generate 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. To provide heat to the process fluid in the convection section 16, the convection section 16 receives flue gas from the radiant section 14. All of the process fluid passing through the convection section 16 (i.e., the preheated process fluid 25) is transferred to the radiant section 14.

[0039] A portion of the process fluid 12 can bypass the convection section 16 in the bypass conduit 30. Thus, the portion of the process fluid 12 that bypasses the convection section 16 can be combined with the preheated process fluid 25. The amount of process fluid 12 passing through the bypass conduit 30 can be adjusted by, for example, adjusting the valve 32 in the bypass conduit 30.

[0040] As described above, there is a benefit provided by more effectively utilizing the heat generated by the combustion of fuel in the radiant section. This can result in a smaller heater and reduced fuel consumption and carbon dioxide output. Additionally, other features of the present invention reduce concerns regarding pressure drop and metal-catalyzed coking.

[0041] Experiment

[0042] In a theoretical comparison based on using a convection section to heat the process stream of an 87,000 BPSD process, using the method and apparatus of the present invention shows a 21% reduction in carbon dioxide emissions. In 50% of the 87,000 BPSD process, the method of the present invention shows a 22.5% reduction in carbon dioxide.

[0043] One of ordinary skill in the art should recognize and understand that various other components such as valves, pumps, filters, coolers, etc. are not shown in the drawings because it is believed that their specific details are entirely within the knowledge of one of ordinary skill in the art and their description is not necessary for the implementation or understanding of the embodiments of the present invention.

[0044] Any of the above pipelines, conduits, units, equipment, containers, surroundings, zones, or the like can be equipped with one or more monitoring components, including sensors, measuring devices, data capture devices, or data transmission devices. Signals, methods, or state measurements, and data from the monitoring components can be used to monitor conditions in, around, and related to the method equipment. Signals, measurements, and / or data generated or recorded by the monitoring components can be collected, processed, and / or transmitted through one or more networks or connections, which can be private or public, general or dedicated, direct or indirect, wired or wireless, encrypted or unencrypted, and / or combinations thereof; this specification is not intended to be limiting in this regard.

[0045] Signals, measurements, and / or data generated or recorded by monitoring components may be transmitted to one or more computing devices or systems. The computing device or system may include at least one processor and a memory storing computer-readable instructions that, when executed by the at least one processor, cause the one or more computing devices to perform a method that may include one or more steps. For example, one or more computing devices may be configured to receive data related to at least one device associated with the method from one or more monitoring components. The one or more computing devices or systems may be configured to analyze the data. Based on the data analysis, 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 of the methods described herein. The one or more computing devices or systems may be configured to transmit encrypted or unencrypted data that includes one or more recommended adjustments to one or more parameters of one or more of the methods described herein.

[0046] Specific implementation plan

[0047] While the following is described in conjunction with specific embodiments, it should be understood that the description is intended to illustrate and not limit the scope of the foregoing description and the appended claims.

[0048] A first embodiment of the present invention is a device for heating a process fluid, the device comprising: 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 the flue gas from the radiant section; a convection conduit passing through the convection section and configured to receive the process fluid and transfer heat to the process fluid; and a radiant conduit passing through the radiant section and configured to receive the process fluid and transfer heat to the process fluid, wherein the convection conduit and the radiant conduit are 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 to the previous embodiments of this paragraph, wherein the radiant conduit comprises a multi-channel coiled conduit. An embodiment of the present invention is one, any, or all of the first embodiment to the previous embodiments of this paragraph, wherein the convection conduit comprises a straight conduit without bends. An embodiment of the present invention is one, any, or all of the first embodiment to the previous embodiments of this paragraph, the device comprising a plurality of parallel convection conduits, each convection conduit passing through the convection section and configured to receive the process fluid and transfer heat to the process fluid. An embodiment of the present invention is one, any, or all of the first embodiment to the previous embodiments of this paragraph, the device further comprising a first convection manifold and a second convection manifold, the plurality of parallel convection conduits extending 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 embodiments of this paragraph, the device 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 to the previous embodiments of this paragraph, the device further comprising a first radiant manifold and a second radiant manifold, the radiant conduit extending between the first radiant manifold and the second radiant manifold. An embodiment of the present invention is one, any, or all of the first embodiment to the previous embodiments of this paragraph, wherein 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 to the previous embodiments of this paragraph, wherein the first radiant manifold is further configured to receive the process fluid from the bypass conduit.Embodiments of the present invention are one, any, or all of the first embodiment of this paragraph to the previous embodiments of this paragraph, wherein the radiation section has a plurality of heating zones, each heating zone operating at a temperature independent of the temperature of the other heating zones. Embodiments of the present invention are one, any, or all of the first embodiment of this paragraph to the previous embodiments of this paragraph, wherein the convection duct is arranged such that the inlet of the convection duct is above a heating zone that has a higher temperature than a heating zone below the outlet of the convection duct.

[0049] A second embodiment of the present invention is a method for heating a process fluid, the method comprising: burning fuel gas and / or fuel oil in a radiant section of a device to generate heat and flue gas; passing the process fluid through a convection section to heat the process fluid, the convection section receiving the flue gas from the radiant section; 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. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiments of this paragraph, the method further comprising bypassing a portion of the process fluid around the convection section. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiments of this paragraph, the method further comprising combining the portion of the process fluid bypassing the convection section with the process fluid being delivered to the convection section. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiments of this paragraph, the method further comprising adjusting the amount of the portion of the process fluid bypassing the convection section. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiments of this paragraph, wherein the convection section comprises at least one convection conduit, the at least one convection conduit comprising a straight conduit. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiments of this paragraph, wherein the radiant section has a plurality of heating zones, each heating zone operating at a temperature independent of the temperature of the other heating zones. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiments of this paragraph, wherein the at least one convection conduit is arranged such that an inlet of the at least one convection conduit is above a heating zone that has a higher temperature than 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 to the previous embodiments of this paragraph, wherein the radiant section comprises at least one convection conduit, the at least one convection conduit comprising a multi-channel coil conduit. An embodiment of the present invention is one, any, or all of the second embodiment to the previous embodiments of this paragraph, wherein the process fluid is from a hydrocarbon reforming zone.

[0050] Although no further elaboration is provided, it is believed that those skilled in the art can make the most of the present invention by using the foregoing description and can easily determine the basic features of the present invention without departing from the essence and scope of the present invention to make various changes and modifications to the present invention and adapt it to various uses and conditions. Therefore, the foregoing preferred specific embodiments should be understood as merely illustrative and not in any way limiting the remainder of the disclosure, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0051] In the foregoing, all temperatures are shown in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

[0052] Although at least one exemplary embodiment has been presented in the foregoing specific embodiments of the present invention, it should be understood that there are numerous variations. It should also be understood that one exemplary embodiment or multiple exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or construction of the present invention in any way. On the contrary, the foregoing specific embodiments will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiments of the present invention. It should be understood that various changes can be made to the functions and arrangements of the elements described in the exemplary embodiments 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), the apparatus (10) comprising: a radiation section (14) having one or more burners (18) configured to provide heat and flue gas; a convection section (16) disposed adjacent to the radiation section (14), the convection section (16) being configured to receive the flue gas from the radiation section (14); a convection conduit (24) passing through the convection section (16) and configured to receive the process fluid (12) and transfer heat to the process fluid (12); and, a radiation conduit (20) passing through the radiation section (14) and configured to receive the process fluid (12) and transfer heat to the process fluid (12), wherein the convection conduit (24) and the radiation conduit (20) are arranged in series such that all of the process fluid (12) passing through the convection conduit (24) also passes through the radiation conduit (20).

2. The apparatus (10) according to claim 1, wherein the radiation conduit (20) comprises a multi-channel coiled conduit.

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

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

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

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

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

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

9. The apparatus (10) according to any one of claims 1 to 8, wherein the radiation section (14) has a plurality of heating zones (40a, 40b, 40c), each heating zone (40a, 40b, 40c) operating at a temperature independent of the temperature of the other heating zones (40a, 40b, 40c), and wherein the convection duct (24) is arranged such that the inlet (42) of the convection duct (24) is above a heating zone (40a, 40b, 40c) which has a higher temperature than the heating zone (40a, 40b, 40c) below the outlet (44) of the convection duct (24).

10. A method for heating a process fluid (12), the method comprising: burning fuel in a radiation section (14) of an apparatus (10) to generate heat and flue gas; passing the process fluid (12) through a convection section (16) to heat the process fluid (12), the convection section (16) receiving the flue gas from the radiation section (14); passing the process fluid (12) through the radiation section (14) to heat the process fluid (12), wherein the process fluid (12) passing through the radiation section (14) has passed through the convection section (16).

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