System and method for operating a heating device

Abstract

Systems and methods for operating a heating device are disclosed. An oxygen-containing stream is first treated to produce an oxygen stream containing more than 25 vol% oxygen. The oxygen stream is then mixed with an air stream to produce a combustion gas stream containing from 21.5 vol% to 27 vol% oxygen. A fuel is combusted in the combustion gas stream to provide heat to the heating device.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 128,793, filed December 21, 2020, the entire contents of which are incorporated herein by reference. Invention Field

[0003] This invention generally relates to systems and methods for operating heating devices. More specifically, this invention relates to generating oxygen-rich combustion exhaust gases for burning fuel in a heating device. Background of the Invention

[0005] Heating is one of the most important methods in the chemical processing industry. Typically, fuel is burned in air in heating devices (e.g., furnaces, boilers, and heat exchangers) to provide heat to chemical production processes. However, many chemical production processes, including steam cracking, are carried out at high temperatures, requiring high intensity combustion. Current methods of burning fuel in air have limitations in providing sufficient heat to chemical production processes, resulting in limited production efficiency. While the capacity of most heaters can be increased simply by increasing combustion, i.e., pushing in more fuel, the demand for combustion air also increases. The furnace may be subject to one or more of the following limitations, including (1) process-side mechanical flow limitations, such as peak velocity; (2) fuel gas main pressure limitations; and (3) combustion air flow limitations. This makes the furnace a limiting device for further increasing plant production capacity. Various solutions can be explored to address furnace capacity limitations, which may include installing new furnaces, upgrading furnace design, burners or combinations thereof, using oxygen-enriched fuels for combustion, etc. However, all of these solutions are highly capital-intensive and may inhibit costs. For pure O2 combustion, the main challenges include O2 availability and cost, as well as the retrofitting costs of the furnace and burners. In cases requiring only small or medium-level increases in production, an alternative is to use O2-rich combustion instead of pure O2 combustion.

[0006] In summary, although methods for operating heating devices exist, improvements are still needed in this field due to the aforementioned drawbacks of conventional methods. Summary of the Invention

[0007] Solutions have been found to at least the aforementioned problems related to methods of operating heating devices. The solution lies in a method of operating a heating device that includes using a membrane-based separation assembly to generate oxygen-enriched air (>21 vol% O2) as a combustion gas and burning fuel in the combustion gas. This at least improves fuel energy efficiency compared to conventional methods. Furthermore, the disclosed method may also include flowing a first airflow through a membrane assembly and flowing a second airflow counter-currently through a separate air inlet to generate a counter-current sweep of air across the permeate side of the membrane assembly, thereby improving the energy efficiency of the membrane separation process. Furthermore, the disclosed method may also include using a membrane separation unit installed at the inlet of the heating device, thereby eliminating the capital expenditure of exhaust fans, blowers, and piping works. Additionally, the disclosed method may include injecting oxygen-enriched air onto the heating device (e.g., a steam cracker) via a diffuser, thereby improving the mixing efficiency of oxygen and fuel compared to conventional methods. Therefore, the systems and methods disclosed in this invention provide technical solutions to problems related to conventional systems and methods for operating heating devices.

[0008] Embodiments of the present invention include a method of operating a heating device. The method includes causing a first oxygen-containing stream to flow at a first inlet of the heating device through one or more oxygen separation membrane assemblies to generate an oxygen-enriched stream. The method includes flowing a second stream and an oxygen stream countercurrently into the heating device, such that the second stream and the oxygen stream are mixed to generate an oxygen-enriched combustion gas stream. The method further includes burning fuel in the oxygen-enriched combustion gas stream within the heating device to generate heat.

[0009] Embodiments of the present invention include a method of operating a heating device. The method includes flowing a first airflow through one or more oxygen separation membrane assemblies disposed at a first inlet of the heating device to generate an oxygen-enriched airflow. The method further includes flowing a second airflow and an oxygen flow counter-currently into the heating device to generate a counter-current sweep of air through the permeate side of the oxygen separation membrane assemblies, and mixing the second airflow with the oxygen flow to generate an oxygen-enriched combustion gas flow containing 21.5 vol% to 27 vol% O2. The method also includes burning fuel in the oxygen-enriched combustion gas flow within the heating device to generate heat.

[0010] Embodiments of the present invention include a method of operating a heating device. The method includes passing an oxygen-containing stream through one or more membrane-based oxygen separation components to generate an oxygen-enriched stream. The method includes mixing the oxygen stream with a gas stream to form a combustion gas stream containing more than 21% by weight of oxygen. The method includes injecting the combustion gas stream upstream of the air inlet of the heating device through one or more diffusers, such that the combustion gas stream is mixed with fuel. The method further includes burning the fuel in the combustion gas within the heating device to generate heat.

[0011] The following includes definitions of various terms and phrases used in this specification.

[0012] The terms “approximately” or “about” are defined as close to what is understood by one of ordinary skill in the art. In one non-limiting embodiment, the term is defined as a deviation of less than 10%, preferably less than 5%, more preferably less than 1%, and most preferably less than 0.5%.

[0013] The terms “weight%”, “volume%”, or “molar%” refer to the weight, volume, or molar percentage of a component based on the total weight, volume, or number of moles of the material containing the component, respectively. In a non-limiting example, 10 moles of a component in 100 moles of material is 10 molar% of the component.

[0014] The term “substantially” is defined as including deviations within 10%, 5%, 1%, or 0.5%.

[0015] The terms “suppress” or “reduce” or “prevent” or “avoid” or any variations thereof, when used in the claims and / or description, include any measurable reduction or complete suppression in order to achieve the desired result.

[0016] The term “effectively” when used in the claims and / or description means sufficient to achieve the desired, anticipated, or contemplated result.

[0017] When used in conjunction with the terms “comprising,” “including,” “containing,” or “having” in the claims or specification, the absence of a number before an element may indicate “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more.”

[0018] The words “contain,” “include,” “have,” or “contain” are inclusive or open-ended and do not exclude other unmentioned elements or methods or steps.

[0019] The method of the present invention may "comprising" the specific materials, ingredients, compositions, etc. disclosed throughout this specification, or may "consist substantially of" or "composed of" the specific components, compositions, ingredients, etc. disclosed throughout this specification.

[0020] When used in the claims and / or description, the term "primarily" means any of 50% by weight, 50% by mol%, and 50% by volume. For example, "primarily" can include all values ​​and ranges from 50.1% by weight to 100% by weight, 50.1% by mol% to 100% by mol%, or 50.1% by volume to 100% by volume.

[0021] Other objects, features, and advantages of the present invention will become apparent from the following accompanying drawings, detailed descriptions, and embodiments. However, it should be understood that while the drawings, detailed descriptions, and embodiments illustrate specific embodiments of the invention, they are given by way of illustration only and are not intended to be limiting. Furthermore, changes and modifications within the spirit and scope of the invention are expected to become apparent to those skilled in the art based on these detailed descriptions. In other embodiments, features from a particular embodiment may be combined with features from other embodiments. For example, a feature from one embodiment may be combined with features from any other embodiment. In other embodiments, additional features may be added to the particular embodiments described herein.

[0022] Brief description of the attached figures

[0023] For a more complete understanding, please refer to the following description in conjunction with the accompanying drawings, in which:

[0024] Figures 1A to 1D A schematic diagram of a system for operating a heating device according to an embodiment of the present invention is shown; Figure 1A A schematic diagram of a system for operating a heating device is shown, the system including a membrane separation assembly at the inlet of the heating device; Figure 1B A schematic diagram of a system for operating a heating device is shown, the system comprising multiple membrane separation components; Figure 1C It shows that it can be used Figure 1B A schematic diagram of the diffuser in the system shown; Figure 1D A burner with a heating device for an optimal inlet for oxygen-enriched gas is shown according to an embodiment of the invention;

[0025] Figure 2A and Figure 2B A schematic flowchart of a method for operating a heating device according to an embodiment of the present invention is shown; and

[0026] Figure 3A and Figure 3B A schematic diagram of various ventilation schemes for operating a heating device is shown according to an embodiment of the present invention; Figure 3A A schematic diagram of induced ventilation for a heating device is shown; Figure 3B A schematic diagram of balanced ventilation for a heating device is shown. Detailed Implementation

[0027] Currently, fuel and air mixtures are burned to provide heat to heating units, which in turn provide heat to production processes. However, the heating and / or fuel efficiencies of conventional methods are relatively limited. Combustion of fuel in pure oxygen can improve fuel efficiency due to the higher flame temperatures. However, retrofitting existing air-fired furnaces with pure oxygen requires significant capital expenditure. For example, most furnaces used in ethylene production are naturally aspirated or induced aspirated. These require conversion to forced or balanced aspiration via flue gas recirculation to operate under pure oxygen combustion. Burner configurations also need to be altered for pure oxygen. Pure oxygen combustion optimized with flue gas recirculation can minimize changes to burners and convection sections, but this is often used as an opportunity for CO2 capture. This invention provides solutions to at least some of these problems. The premise of this solution is a method for providing heat to heating units, including the use of membrane-based separation components to generate oxygen-enriched combustion gases (O2 volume% > 21 volume%), resulting in higher fuel efficiency. Furthermore, the disclosed method does not significantly reduce flue gas production, mitigating the heat distribution problems associated with combustion in pure oxygen. Furthermore, the disclosed method enables a countercurrent sweep on the permeate side of the membrane module, thereby reducing the energy consumption of membrane-based oxygen separation. These and other non-limiting aspects of the invention will be discussed in further detail in the following sections.

[0028] A. A system for operating a heating device

[0029] In embodiments of the invention, the system for supplying heat to the heating device uses oxygen-enriched gas (O2 volume% > 21 volume%) to achieve higher fuel efficiency. Notably, this method generates sufficient flue gas to maintain heat distribution within the heating device while maintaining higher combustion efficiency than conventional methods. (See also...) Figure 1A A schematic diagram of a system 100 for supplying heat to a heating device is shown.

[0030] According to embodiments of the present invention, the heating device may include a furnace, a boiler, a vacuum distillation unit heater, a crude oil distillation unit heater, a sulfuric acid regeneration heater, or a combination thereof. In an embodiment of the present invention, system 100 includes a first heating device 101 configured to burn fuel in combustion gases therein. The first heating device 101 may include a boiler or a furnace including one or more burners. The furnace may be a conventional steam cracking unit furnace.

[0031] In an embodiment of the invention, system 100 further includes a membrane separation unit 102 configured to separate oxygen from a first stream 11 to produce a gas containing 28% to 35% oxygen by weight. The first stream 11 may contain air. According to an embodiment of the invention, membrane separation unit 102 may include a plurality of membrane separation components 103. Membrane separation components 103 may include ceramic-based membranes, polymer-based membranes, metal complex-reinforced membranes, or combinations thereof. Membrane separation components 103 may include compressor components, turbine expander components, membrane components in series (i.e., stacked configuration), and filter components.

[0032] According to an embodiment of the invention, the membrane separation unit 102 may include additional inlets configured to receive other streams 13 therein, such that oxygen separated from the first stream 11 is mixed with the other streams 13 to form a first combustion gas stream 14. The first combustion gas stream 14 may contain more than 21% by volume of oxygen, preferably 25% to 35% by volume of oxygen. In an embodiment of the invention, the other streams 13 may contain air. In an embodiment of the invention, the membrane separation unit 102 is installed at the first inlet of the burner of the heating device 101.

[0033] According to an embodiment of the invention, the burner of the heating device 101 includes a second inlet configured to receive a second stream 12 into the burner. The second inlet is configured such that the second stream 12 and the first stream 11 flow countercurrently into the burner to generate a countercurrent sweep of air through the permeate side of the membrane separation assembly 103. In an embodiment of the invention, the countercurrent sweep can reduce the energy consumption for oxygen separation in the membrane separation unit 102. In an embodiment of the invention, oxygen generated by the membrane separation unit 102 or the first combustion gas stream 14 is combined with the second stream 12 to form an oxygen-enriched combustion gas stream 15. The second stream 12 may contain air. The oxygen-enriched combustion gas stream 15 may contain 21.5 vol% to 27 vol% oxygen. The heating device 101 can be operated using induced ventilation and / or natural ventilation. In an embodiment of the invention, forced ventilation is generated by placing an exhaust fan at the bottom of the heater (e.g., the heating device 101), which results in overpressure to drive air into the heater through the burner air inlet. Figure 3A As shown, balanced ventilation is achieved by adjusting forced ventilation and induced ventilation to reach atmospheric pressure within the burner, thereby preventing accidental inflow of other air into the heating unit. Figure 3B As shown, induced ventilation is generated by drawing air into the heater (e.g., heating device 101) using an axial fan placed on top of the heater. The induced ventilation is configured to generate a low pressure within the heater, which draws air in through the heater's burner air inlet.

[0034] Reference Figure 1BA schematic diagram of a system 200 for providing heat to a heating device is shown. According to an embodiment of the invention, system 200 includes a second heating device 201. The second heating device 201 may include a furnace, boiler, reboiler, heat exchanger, or a combination thereof. In an embodiment of the invention, system 200 includes a compressor 204 configured to compress a first oxygen-containing stream 21 to form a compressed oxygen-containing stream 23. The first oxygen-containing stream 21 may contain air.

[0035] According to an embodiment of the invention, the outlet of compressor 204 may be in fluid communication with the inlet of second membrane separation unit 203, such that compressed oxygenated stream flows from compressor 204 to second membrane separation unit 203. Second membrane separation unit 203 may include one or more parallel-operating second membrane modules 206. Second membrane modules 206 may include ceramic-based membranes, polymer-based membranes, metal complex-reinforced membranes, or combinations thereof. The second membrane modules 206 of second membrane separation unit 203 may include a compressor, a turbine expander, membrane modules in series (i.e., stacked configuration), and filters of various types. Second membrane separation unit 203 may be configured to process compressed oxygenated stream 23 to produce a second oxygen-enriched stream 22. The second oxygen-enriched stream 22 may contain 25% to 30% by volume of oxygen. As an alternative to or supplement to separating compressed oxygenated stream 23, second membrane separation unit 203 may be configured to process oxygenated stream 21 to produce the second oxygen-enriched stream 22.

[0036] According to an embodiment of the invention, the outlet of the membrane separation unit 203 is in fluid communication with the central duct 202. The centrally located membrane module is configured for use in a forced draft furnace or a balanced draft furnace. The membrane module of the membrane separation unit 203 may be located near a blower configured to supply combustion air to the furnace. The diffuser 305 is configured to inject a second oxygen-enriched stream 22 (25% to 35% oxygen by weight) into the central combustion air duct, such that the second oxygen-enriched stream 22 flows from the membrane separation unit 203 to the central duct 202. Figure 1C As shown, each diffuser 205 may include multiple slots for releasing gases. The diffuser 205 is also configured to mix a second oxygen-enriched stream 22 with a second air stream 24 containing air from a central conduit 202 to form a third combustion gas stream 25. The third combustion gas stream 25 may contain 21.5 vol% to 27 vol% oxygen.

[0037] According to an embodiment of the invention, a central conduit 202 is connected to a second heating device 201, such that a second oxygen-enriched stream 22 released in the central conduit 202 flows into one or more burners of the second heating device 201. The second heating device 201 may include a steam cracking furnace, a steam reformer, a boiler, a vacuum distillation unit heater, a crude oil distillation unit heater, a sulfuric acid regeneration heater, or a combination thereof. In an embodiment of the invention, the second heating device 201 can operate under forced ventilation or balanced ventilation conditions.

[0038] According to embodiments of the present invention, for system 100 and / or system 200, oxygen-enriched gas, including oxygen-enriched air, can be generated in a central location and / or central device. For example... Figure 1D As shown, oxygen-enriched gas generated in the central location and / or central equipment can be injected into the burner of the heating device at the air chamber of the burner. The oxygen-enriched gas can be injected into the burner through one or more diffusers.

[0039] B. Method of operating the heating device

[0040] A method for operating the heating device has been discovered. Compared to conventional methods, this method may be able to improve fuel combustion efficiency. Figure 2A As shown, an embodiment of the present invention includes a method 300 for operating a heating device. Method 300 can be implemented by system 100.

[0041] According to an embodiment of the invention, as shown in block 301, method 300 includes flowing a first stream 11 through one or more membrane separation components 103 of a membrane separation unit 102 disposed at a first inlet of a heating device 101 to generate an oxygen stream. In an embodiment of the invention, the first stream 11 is an oxygen-containing stream. The oxygen-containing stream may contain air. In an embodiment of the invention, the oxygen stream generated by the membrane separation unit 102 contains an oxygen content of 28% to 35% by volume. In an embodiment of the invention, at block 301, one or more membrane separation components 103 operate at an operating pressure of 3 bar to 15 bar. One or more membrane separation components 103 can operate at an operating temperature of 10°C to 50°C, preferably 25°C to 30°C.

[0042] According to an embodiment of the invention, as shown in block 302, method 300 includes countercurrently flowing the second stream 12 and the oxygen stream to generate a countercurrent sweep of gas through the permeate side of one or more separation membrane modules 103. In an embodiment of the invention, the countercurrent sweep is configured to reduce the energy consumption of separating oxygen from the first stream 11 using one or more membrane separation modules 103. In an embodiment of the invention, the second stream 12 comprises air. In an embodiment of the invention, as shown in block 303, method 300 includes mixing the oxygen stream with the second stream 12 to generate a combustion gas stream 15. The combustion gas stream 15 may comprise oxygen-enriched air containing 21.5 vol% to 27 vol% oxygen. Blocks 302 and 303 may be performed simultaneously.

[0043] As an alternative or supplement to mixing the oxygen stream with the second stream 12 to form the combustion gas stream 15, as shown in block 304, method 300 may include allowing another stream 13 to flow through a first inlet passing through the heating device 101, such that the oxygen stream and the other stream 13 form a first combustion gas stream 14. The other stream 13 may contain air. In an embodiment of the invention, the first combustion gas stream 14 may contain 25 vol% to 30 vol% oxygen. In an embodiment of the invention, as shown in block 305, method 300 includes mixing the first combustion gas stream 14 with the second stream 12 to form the combustion gas stream 15. Blocks 302 and 305 may be performed simultaneously. The combustion gas stream 15 may contain an oxygen-enriched air stream containing 21.5 vol% to 27 vol% oxygen.

[0044] According to an embodiment of the invention, as shown in block 306, method 300 includes burning fuel in combustion gas stream 15 in heating device 101 to generate heat. In embodiments of the invention, exemplary fuels may include natural gas, ethane, propane, CH4, or combinations thereof. In embodiments of the invention, method 300 is performed without recirculating flue gas. The first heating device 101 may operate with balanced ventilation and / or forced ventilation.

[0045] like Figure 2B As shown, embodiments of the present invention include a method 400 for operating a heating device. Method 400 can be implemented by system 200. According to an embodiment of the present invention, as shown in block 401, method 400 includes causing a first oxygen-containing stream 21 to flow through one or more second membrane modules 206 to generate a second oxygen-enriched stream 22. The second oxygen-enriched stream 22 may contain 25 vol% to 30 vol% oxygen. In an embodiment of the present invention, in block 401, the operating pressure of one or more second membrane modules 206 is from 3 bar to 15 bar. One or more second membrane modules 206 can be operated at an operating temperature from 10°C to 50°C.

[0046] According to an embodiment of the invention, as shown in block 402, method 400 includes injecting a second oxygen-enriched stream 22 upstream of the air inlet of the second heating device 201 through one or more diffusers 205. In an embodiment of the invention, the second oxygen-enriched stream 22 is injected into a central conduit 202. According to an embodiment of the invention, as shown in block 403, method 400 includes mixing the second oxygen-enriched stream 22 with a second air stream 24 to form a third combustion gas stream 25. The third combustion gas stream 25 may contain 21.5 vol% to 27 vol% oxygen. Blocks 402 and 403 may be performed simultaneously in the central conduit 202. In block 403, the volumetric flow rate ratio of the second oxygen-enriched stream 22 to the second air stream 24 may be 0.3 to 0.65.

[0047] According to an embodiment of the invention, as shown in block 404, method 400 includes burning fuel in a third combustion gas stream 25 in a second heating device 201 to generate heat. In embodiments of the invention, exemplary fuels may include natural gas, H2, CH4, ethane, propane, or combinations thereof. In embodiments of the invention, method 400 is performed without recirculated flue gas. In embodiments of the invention, the second heating device 201 operates under forced ventilation or balanced ventilation. In embodiments of the invention, method 300 and / or method 400 can be performed by injecting oxygen-enriched air into a central location or a central device connected to the heating device.

[0048] Although reference Figure 2A and Figure 2B The boxes in the diagram describe embodiments of the present invention. It should be understood that the operation of the present invention is not limited to... Figure 2A and Figure 2B The specific method blocks and / or specific method block order shown. Therefore, embodiments of the present invention can use different methods than those shown. Figure 2A and Figure 2B Different method boxes arranged in a specific order are used to provide the functionality described in this article.

[0049] The systems and methods described herein may also include various devices, not shown, that are well known to those skilled in the art of chemical processing. Examples may include controllers, pipes, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, etc., which may not be shown.

[0050] Although the embodiments and advantages of this application have been described in detail, it should be understood that various changes, substitutions, and modifications can be made without departing from the spirit and scope of the embodiments as defined by the appended claims. Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, material compositions, means, methods, and steps described in the specification. As will be readily understood by those skilled in the art based on the foregoing disclosure, existing or future processes, machines, manufactures, material compositions, means, methods, or steps that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, means, methods, or steps within their scope.

Claims

1. A method of operating a heating device, the method comprising: A first airflow is made to pass through one or more oxygen separation membrane assemblies operating at a temperature of 10°C to 50°C to generate an oxygen-enriched flow, the oxygen separation membrane assemblies being disposed at the first inlet of the heating device. Other airflows are allowed to flow through the first inlet of the heating device, so that the other airflows and the oxygen-enriched flow form the first combustion gas flow; The second airflow and the oxygen-enriched flow flow into the heating device in a countercurrent manner, thereby generating a countercurrent sweep of air through the permeate side of the oxygen separation membrane assembly; The second air stream is mixed with the first combustion gas stream to produce an oxygen-rich combustion gas stream; and In a heating device, fuel in an oxygen-rich combustion gas stream is burned to generate heat.

2. The method of claim 1, wherein the oxygen-enriched combustion gas stream comprises 21.5 vol% to 27 vol% O2.

3. The method according to claim 1 or 2, wherein countercurrent sweeping is configured to reduce energy consumption for separating oxygen.

4. The method according to claim 1 or 2, wherein the heating device is capable of operating under forced ventilation and / or balanced ventilation.

5. The method according to claim 1 or 2, wherein the oxygen-enriched stream comprises 28% to 35% by volume of oxygen.

6. The method according to claim 1 or 2, wherein the heating device operates without recirculating flue gas.

7. The method of claim 1 or 2, wherein the membrane of the membrane module comprises a ceramic-based membrane, a polymer-based membrane, a metal complex-reinforced membrane, or a combination thereof.

8. The method according to claim 1 or 2, wherein the fuel comprises CH4, H2, propane, ethane, or a combination thereof.

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