Combustion system comprising a ring shroud burner

Abstract

The present disclosure relates to systems and methods for enabling high flame temperature oxy-combustion that is cost effective to capture CO2. Part of the presently disclosed subject matter includes an annular shrouded burner that utilizes a supply of undiluted oxygen and minimal flue gas recirculation to produce high flame temperatures to maximize efficiency. The annular shrouded burner can deliver oxygen into a combustion zone where mixing of the oxygen and fuel stream occurs. Flue gas recirculated from the outlet of the combustion system serves a dual purpose: to deliver coal into the reaction zone, and to provide localized cooling and prevent high incident heat flux through a novel shroud cooling design. The annular shrouded burner can be configured to produce an axial jet flame that controls the oxygen and fuel mixing rate, thereby expanding the heat release. Oxygen and coal can be mixed at a ratio such that peak flame temperatures exceed 4,500°F (2,482°C), while adjusting the flow of recirculated flue gas to control the flame temperature and protect the burner assembly and near-burner surfaces.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to methods and systems for combustion and carbon capture, and more particularly, to methods and systems involving high flame temperature oxy-combustion of a fuel and efficient capture of carbon dioxide. BACKGROUND

[0002] Fossil fuels are the primary energy source in today's world, particularly in the power generation, industrial, and transportation industries. However, it is also considered by many to be the primary cause of global warming due to the large amount of CO2 produced associated with the use of fossil fuels. One of these fossil fuels is coal, where the future use of coal as a fuel for power generation and industrial applications depends on new, cost-effective technologies that can be used to capture and store the CO2 emitted as a product of the combustion process. These carbon capture technologies are commonly referred to as carbon capture and storage (CCS) and carbon capture utilization and storage (CCUS).

[0003] Some available technologies include air-fueled and oxy-fueled combustion technologies. In the case of air-fueled combustion (air contains approximately 79% nitrogen and approximately 21% oxygen), NOx x and other greenhouse gases such as CO2 and SO2 are produced as a result of the combustion process. The higher impurity percentage of air-fueled combustion makes carbon capture, such as CCS and CCUS, more complex and more expensive than oxy-fueled combustion. In addition to this drawback, air-fueled combustion suffers from lower fuel efficiency due to the amount of fuel required to heat the nitrogen present in air.

[0004] A more advantageous system is an oxy-fueled combustion system (or oxy-combustion). In the case of oxy-combustion, oxygen greater than 95% pure is used as the oxidizer in the combustion process instead of air. The use of high purity oxygen results in a significantly lower impurity percentage and higher concentrations of CO2 and H2O, making processes such as CCS and CCUS more cost effective than air-fueled combustion. CO2 can be easily separated from H2O and purified in a carbon purification unit (CPU), leaving high purity CO2 that can be recycled, stored, or utilized as a valuable commodity as part of the CCS or CCUS process. This reduces the amount of greenhouse gas production.

[0005] However, this process requires pure oxygen (O2), which is often obtained via cryogenic distillation. Cryogenic distillation is a very mature process that has been in operation since the 1930s, but is still an expensive process. In addition to the cost increase, traditional oxy-combustion also suffers from other drawbacks, such as high capital costs, air ingress and associated higher impurities, high oxygen requirements, and lower carbon capture, utilization, and sequestration of CO2.

[0006] Despite the drawbacks associated with traditional oxygen combustion of fuels, it is still an improvement over air-fuel combustion. Thus, it is desirable to replace air-fuel combustion burners in boilers and process heaters existing in current fuel processing plants with more environmentally friendly oxygen combustion burners.

[0007] Generally, the systems in current fuel processing plants are configured to provide optimal performance while limiting the negative consequences associated with air-fuel combustion burners. Thus, replacing one burner with another is not easily accomplished, much less replacing an air-fuel combustion process with an oxygen-fuel combustion process. Potential drawbacks associated with this type of change include a significant change in heat transfer between various systems, as well as an increased likelihood of component damage due to different heating characteristics, flow rates, and flow characteristics. One reason for this difficulty is that an oxygen combustion burner will produce hotter flame temperatures than a traditional air-fuel burner. For example, when a current air-fuel combustion burner is replaced with an oxygen combustion burner, the peak temperature will increase, increasing the amount of heat transfer (heat flux) to components surrounding the oxygen combustion burner. This requires modifications to existing portions of the plant, a process that is both time consuming and extremely costly.

[0008] Reports on previous attempts to design oxygen coal burners suitable for application to different systems include overly complex designs (see U.S. Patents Nos. 8,584,605, 7,028,622, and 6,843,185). This is caused in part by the nature of oxygen combustion, which involves the burning of fuel using pure oxygen rather than air as the oxidizer. Because the heat from the combustion does not go to heating nitrogen in the air, the flame temperature with oxygen combustion increases dramatically. Other patents describe oxygen combustion techniques that use minimal FGR and produce high temperature flames (see U.S. Patents Nos. 6,436,337 and 6,596,220 to Gross). However, the burners described in these publications have the potential to cause damage to the systems surrounding the oxygen coal burners due to the nature of their design.

[0009] Other patents moderate oxygen combustion flame temperatures by creating a synthetic air stream composed of a mixture of oxygen and flue gas recirculation (FGR) that results in lower flame temperatures (see U.S. Patent Nos. 9,243,799, 8,689,710). While the burners described in U.S. Patent Nos. 9,243,799 and 8,689,710 can operate at much lower flame temperatures and thus are not necessarily damaging to the system environment, they have other design and operational challenges. The large volume of FGR can require additional energy to heat before entering the furnace (similar to an air preheater). Air intake can also increase with the increase in FGR. More FGR results in a large volume of flue gas exiting the furnace, which requires increasing the size of downstream equipment (e.g., air pollution control devices, ductwork, fans, carbon capture and sequestration equipment).

[0010] In summary, the prior patents cited above do not have burner design features or operational methods that are suitable for effectively utilizing and moderating the heat flux reaching the burner assembly and furnace walls when utilizing high flame temperature oxygen combustion methods.

[0011] Thus, there is a need for an oxygen combustion ignition system that addresses the deficiencies of the prior art, i.e., to develop a burner design that can efficiently and cost effectively generate and maintain high flame temperature oxygen combustion conditions for coal ignition. There is also a need for an oxygen combustion ignition system that can replace the conventional air-fired combustion burners in existing fuel-fired systems while simultaneously preventing damage to the burner assembly and furnace interior surfaces caused by high heat flux. SUMMARY

[0012] In one aspect, the subject matter described herein relates to a high flame temperature oxygen combustion ignition system. More specifically, in embodiments, the high flame temperature oxygen combustion ignition system is an annular shrouded burner comprising: a quadruple concentric burner design with O2 ring in the center, followed by a fuel ring for coal, then O2, and finally an outer flue gas recirculation (FGR) ring. Positioned further outside the FGR ring is a refractory brick.

[0013] The design and method of operating the annular shrouded burner allows for the generation of a high temperature flame localized towards the center of the combustion zone with a shroud of cooler gas at the periphery of the combustion zone. Thus, the annular shrouded burner provides localized cooling while simultaneously maintaining the high flame temperature characteristics of the burner, thereby maximizing efficiency and flame stability.

[0014] In another embodiment, an annular shrouded burner having: a quadruple concentric burner design with a design comprising first, second, third, and fourth conduits, wherein each conduit separately injects a first, second, third, and fourth flow to a first, second, third, and fourth ring, wherein

[0015] The first flow comprises a first oxygen source,

[0016] The second flow comprises a mixture of fuel and a carrier gas for transporting the fuel,

[0017] The third flow comprises a second oxygen source,

[0018] The fourth flow comprises FGR,

[0019] wherein a central igniter is located in the center of the annular shrouded burner, and a fourth ring is positioned outside of the refractory bricks.

[0020] In another embodiment is a method of combusting fuel, the method comprising:

[0021] providing an annular shrouded burner,

[0022] supplying a first O2 flow to a first ring via a first conduit,

[0023] supplying a mixture of fuel and carrier gas to a second ring via a second conduit,

[0024] supplying a second O2 flow to a third ring via a third conduit,

[0025] supplying FGR to a fourth ring via a fourth conduit, and

[0026] igniting a flame using an igniter located in the center of the annular shrouded burner.

[0027] In another embodiment is a high flame temperature oxy-combustion system comprising:

[0028] at least one annular shrouded burner,

[0029] a furnace for combustion,

[0030] an air separation unit,

[0031] at least one conduit, and

[0032] a control system, wherein the annular shrouded burner is configured to provide a peak flame temperature of at least 4,000 °F (2,204 °C) having a heat distribution profile similar to Figure 4 depicted in FIG. 1, such that radiant heat and potential damage to systems surrounding the annular shrouded burner are minimized.

[0033] In another embodiment is a method of operating a high flame temperature oxy-combustion system, wherein the method comprises:

[0034] supplying fuel, carrier gas, and substantially pure oxygen to an annular shrouded burner,

[0035] burning the fuel, carrier gas, and substantially pure oxygen to emit a flame, wherein the flame has a heat distribution profile similar toFigure 4 a plot of the depicted radiant heat distribution,

[0036] Water in a boiler is heated with a high flame temperature oxy-combustion annular shroud burner to convert the water to steam.

[0037] These and other aspects are described more fully below. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1A and Figure 1B An annular shroud burner is depicted. Figure 1A A general configuration of an annular shroud burner is depicted. Figure 1B Four specific areas of an annular shroud burner are depicted, specifically a center O2 port, a fuel ring, an outer O2 ring, and an FGR ring for localized cooling.

[0039] Figures 2A-2C Different aspects of an annular shroud burner are depicted.

[0040] Figure 3 A process flow diagram of a high flame temperature oxy-fired system is shown.

[0041] Figure 4 A gas temperature profile of an annular shroud burner is shown with a peak temperature of 4,572 °F (2,522 °C) when firing bituminous coal.

[0042] Figure 5 A gas temperature profile of an oxy-combustion burner with discrete O2 ports is shown with a peak temperature of 4,581 °F (2,527 °C).

[0043] Figure 6 A gas temperature profile of an annular shroud burner is shown with a peak temperature of 4,133 °F (2,278 °C) when firing sub-bituminous coal.

[0044] Figure 7 A model of refractory brick surface temperature is shown where the refractory bricks are in an annular shroud burner and the burner is a single burner model.

[0045] Figure 8 A model of gas temperature in a burner is shown where the burner is a single burner model. The load is turndown to 60% of full load, but the shroud FGR flow rate is maintained constant, and the peak temperature is 4,251 °F (2,344 °C).

[0046] Figure 9 A summary of energy balances for a boiler radiant section and a convection section is shown.

[0047] Figure 10 A process flow diagram of a high flame temperature oxy-combustion system firing coal is shown.

[0048] Figure 11 The furnace head layout and geometry for a furnace head unit used in a single-wall ignition subcritical boiler are shown.

[0049] Figure 12 The net heat flux for a single-wall, fire-ignition subcritical boiler is shown.

[0050] Figure 13 The tube OD surface temperature for a single-wall, fire-ignited subcritical boiler is shown.

[0051] Figure 14 The gas temperature for a single-wall, fire-ignition subcritical boiler is shown.

[0052] Figure 15 The O2 concentration for a single-wall, ignition-type subcritical boiler is shown.

[0053] Figure 16 The CO concentration for a single-wall, fire-ignition subcritical boiler is shown.

[0054] Figure 17 The NO content for a single-wall, fire-ignition subcritical boiler is shown. x Concentration of NO x The value is uncontrolled (no NOx removal occurs throughout the system).

[0055] Figure 18 The reduced net heat flux is shown. Detailed Implementation

[0056] The subjects disclosed herein include high-flame-temperature oxy-coal ignition systems designed to burn coal using undiluted oxygen and minimal flue gas recirculation (FGR). In one embodiment, the system comprises a quadruple burner capable of producing an axial jet flame with a peak temperature exceeding 4,000°F (2,204°C). In a further embodiment, the amount of FGR distributed around the combustion zone can be adjusted to ensure optimal cooling and shielding of the high-temperature flame. This FGR distribution, referred to herein as a shroud, surrounds the region of peak flame temperature. The shroud functions to prevent damage to the burner assembly and near-burner surfaces from extreme temperatures and heat flux, while minimizing the impact on the peak flame temperature.

[0057] In another embodiment, an annular shroud furnace system employing undiluted, directed oxygen combined with a complex mixing strategy is effective in generating stable, high flame temperatures. Applying this technology to various systems, such as those generating electricity through steam production, results in increased system efficiency, reduced capital costs, and improved CO2 capture and storage. This technology can also be used in greenfield applications and / or as a retrofit of existing steam power plants. The advantages of this technology are not limited to the power generation industry. Enhancing coal combustion with pure oxygen could potentially benefit any industry using coal or other fossil fuels as a fuel source.

[0058] The invention can be more readily understood by referring to the following detailed description of the invention and the examples included therein.

[0059] Before further disclosure and description of the systems, apparatuses, and / or methods, it should be understood that, unless otherwise stated, they are not limited to any particular method, as they can certainly vary. It should also be understood that the terminology used herein is for descriptive purposes only and is not intended to be limiting. Although any methods and materials similar to or equivalent to those described herein may be used in the practice or testing of the invention, exemplary systems, apparatuses, and methods are described hereafter.

[0060] While aspects of the invention may be described and claimed in specific statutory categories such as the system statutory category, this is merely for convenience, and those skilled in the art will understand that every aspect of the invention may be described and claimed in any statutory category. Unless expressly stated otherwise, it is never intended that any method or aspect set forth herein require its steps to be performed in a particular order. Therefore, unless a method claim specifically states in the claims or specification that the steps are limited to a particular order, it is never intended that an order be inferred in any aspect. This applies to any possible non-explicit basis of interpretation, including: logical questions concerning the arrangement of steps or operational procedures, the general meaning derived from grammatical organization or punctuation, and the number or type of aspects described in the specification.

[0061] Throughout this application, various publications have been cited. The disclosures of these publications are hereby incorporated in their entirety by reference to provide a more comprehensive description of the current state of the art to which this invention pertains. For material discussed in sentences upon which the documents are relied, the disclosed references are also individually and specifically incorporated herein by reference.

[0062] A. Definition

[0063] The following lists definitions of various terms used to describe the invention. These definitions apply to the terminology used throughout this specification, unless otherwise specified in a particular case, individually or as part of a larger group.

[0064] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural indicators unless the context clearly indicates otherwise.

[0065] In this document, a range can be expressed as "about" a particular value and / or "about" another particular value. When expressing such a range, the other side includes from one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation, it will be understood that the particular value forms the other side by using the antecedent "about". It should be further understood that each endpoint in a range is significant relative to and independent of the other endpoint. It should also be understood that many values ​​are disclosed herein, and each value is disclosed herein as "about" that particular value in addition to the value itself. For example, if the value "10" is disclosed, "about 10" is also disclosed. It should also be understood that each unit between two particular units is also disclosed. For example, if 10 and 15 are disclosed, 11, 12, 13, and 14 are also disclosed. Furthermore, as used herein, the term “about” when referring to a value means to cover a variation of a specific amount, which in some embodiments is ±20%, in some embodiments is ±15%, in some embodiments is ±10%, in some embodiments is ±5%, in some embodiments is ±1%, in some embodiments is ±0.5%, and in some embodiments is ±0.1%, because such variation is suitable for performing the disclosed methods or using the disclosed compositions.

[0066] Where a range of values ​​is provided, it should be understood that every intermediate value between the upper and lower limits of the range (to one-tenth of the unit of the lower limit, unless the context explicitly specifies otherwise) and any other stated or intermediate values ​​within the stated range are included. Upper and lower limits that may be independently included in smaller ranges within these smaller ranges are also included, subject to any explicitly excluded limits within the stated range. Where the stated range includes one or both limits, the range excluding any one or both of those included limits is also included.

[0067] As used herein, the terms “optional” or “optionally” mean that the event or situation described below may or may not occur, and the description includes examples of both the occurrence and non-occurrence of said event or situation.

[0068] The term “include” (and its grammatical variations) as used in this article is used in the inclusive sense of “having” or “including”, rather than in the exclusive sense of “consisting of”.

[0069] As used herein, the term "fuel" means any fuel suitable for combustion purposes. For example, this disclosure can be used with many types of fuels, including but not limited to: natural gas, hydrogen, refinery exhaust gas, refinery fuel gas, blast furnace gas, propane, fuel oil, coal (such as peat, anthracite, semi-anthracite, super anthracite, bituminous coal, sub-bituminous coal, semi-bituminous coal, and lignite); tar; bitumen; petroleum coke; papermaking sludge solids and sewage sludge solids; wood; peat; grass; and combinations and mixtures of all these fuels.

[0070] As used herein, the term "oxygen" refers to an oxidant having an O2 concentration greater than about 30 mol%, typically greater than about 90 mol%, and including oxygen FGR. As used herein, the terms oxygen / coal combustion refer to the combustion of coal in oxygen, air / coal combustion refer to the combustion of coal in air, oxygen / fuel combustion refer to the combustion of fuel in oxygen, and air / fuel combustion refer to the combustion of fuel in air.

[0071] As used in this article, the term “O2 flow” refers to an oxygen (O2) flow containing at least 90 mol% oxygen.

[0072] As used herein, the term "basic pure oxygen" refers to the oxygen purity required to provide the correct fuel-to-oxygen ratio for desired combustion and byproducts without departing from the scope of this invention. Non-limiting examples of basic pure oxygen are 90% or 99% pure.

[0073] As used herein, the term "combustion fluid" refers to a fluid formed from and / or mixed with combustion products, which can be used for radiative and convective heat transfer. The term is not limited to combustion products and may include fluids that are mixed with or otherwise pass through at least a portion of the combustion system.

[0074] As used herein, the term "recirculated flue gas" or "RFG" refers to the fluid that exits at any suitable location (including the end) along the convection section that flows back to any part of the system. If desired, oxygen may be added to the RFG at any suitable location (e.g., the RFG may contain up to 30 mol% O2 before being introduced into the burner and / or pre-combustion chamber).

[0075] As used herein, the terms "flue gas recirculation" or "FGR" refer to a configuration that allows combustion fluid to be recirculated into recirculated flue gas. While any suitable flue gas source can be used (including, but not limited to, flue gas from adjacent or different processes), typical flue gas contains combustion products from the system using the present invention.

[0076] As used herein, the term "pre-combustion chamber" refers to a device in which the burner stream is mixed and ignited before entering the burner or furnace. If present, the pre-combustion chamber may be physically located before the burner. An example of such a pre-combustion chamber is described in U.S. Patent No. 9,243,799.

[0077] As used herein, the terms “conduit” or “pipeline” are used interchangeably and refer to a passage used to transport fuel, O2 streams or other materials from one area to another.

[0078] B. Circular protective cover burner head

[0079] a. Stove head design

[0080] The present invention discloses a high-flame-temperature oxygen-fired furnace head, referred to herein as an annular shroud furnace head. (Refer to the accompanying drawings.) Figure 1A and Figure 1B An embodiment of an annular shroud furnace head is depicted. More specifically, Figure 1B An annular shroud burner with a quadruple concentric burner design is shown, comprising an inner O2 ring 301, followed by a fuel ring 302 for coal, an outer O2 ring 303, and finally an external flue gas recirculation (FGR) ring 304. The outer FGR ring 304 provides localized cooling while minimizing the negative effects from the high-temperature flame. These negative effects may include variations in flame shape or temperature. In this embodiment, the FGR ring 304 generates a gas flow, referred to herein as the shroud. The annular shroud burner also includes refractory bricks 305.

[0081] Refractory brick 305 provides a critical surface for heat diffusion during the combustion process. In embodiments, the refractory brick is designed for high-temperature operation and penetrates the furnace wall through which fuel and oxidizer are injected. The refractory brick can be a diverging conical shape extending from the furnace head face to the inner wall of the furnace. The shape of the refractory brick allows for aerodynamic flame stabilization through the recirculation zone. In embodiments, the refractory brick provides a surface for heat diffusion, resulting in a reduction in heat flux reaching near the furnace head surface. In embodiments, the refractory brick provides additional protection to the surrounding material from the high flame temperatures achieved with an annular shroud furnace head.

[0082] As disclosed in more detail herein, the multi-register annular shroud furnace head allows for extended heat release and heat flux to avoid damage to near-furnace surfaces while still providing flame stability. Specifically, the outer FGR ring 304 provides ample cooling to the furnace head and near-furnace surfaces while maintaining surface temperatures within permissible limits for materials conventionally used in industrial furnaces. This annular shroud furnace head thus provides high flame temperatures exceeding 4,000°F (2,204°C) while simultaneously preventing damage to the furnace head components and internal furnace surfaces caused by high heat flux.

[0083] The functional aspect of an annular shroud burner is that it extracts the maximum amount of energy from the combustion process (in the form of heat transfer from the combustion products) without adversely affecting the high flame temperature or the system surrounding the burner. Therefore, maximum feasible use of higher flame temperatures is achieved. For example, when compared to more conventional burner designs, the annular shroud burner provides a considerably large proportion of heat transfer from combustion products to desired areas (such as boiler tubes and / or working fluid) without unwanted radiant heat flux reaching undesirable areas.

[0084] Other advantages observed with the currently disclosed annular shroud burner include: easier introduction of fuel, oxygen, and flue gas; a simpler design than previous burner designs; easier control of many characteristics, such as gas flow rate and source; a high-temperature flame with improved radiative heat transfer and efficiency; a novel shroud cooling design that minimizes the impact of flame temperature for maximizing efficiency; reduced radiative heat flux; improved flame characteristics, such as peak flame temperature, flame shape, and stability; and the ability to utilize recycled flue gas.

[0085] It is known that radiative heat transfer is proportional to temperature (T) as temperature increases, where T = flame temperature. Therefore, as described in U.S. Patent No. 9,353,945, radiative heat transfer increases with increasing flame temperature, thereby increasing the overall system efficiency.

[0086] In an embodiment, such as Figure 2A and Figure 2B The symbol represents the annular protective cover of the furnace head. Figure 2A An embodiment of a ring-shaped shroud furnace head with four registers is shown. Figure 2B The same annular shroud burner head is shown, which has fuel 310, FGR 320, and O2 331 and O2 336. Fuel 310 flows through conduit 312 to reach fuel ring 302. O2 331 flows through conduit 330 to reach inner O2 ring 301. O2 336 flows through conduit 335 to reach outer O2 ring 303. FGR 320 flows through conduit 325 to reach FGR ring 304. Figure 2C A front view of an annular shroud burner head with outlet points for fuels 310, FGR 320, and O2331 and O2336 is shown.

[0087] In an embodiment, Figure 3The diagram depicts a flow pattern in an annular shroud burner. An igniter 315 is located at the center of the burner. In one embodiment, fuel 310, such as coal, is combined with carrier gas 311 and introduced into the burner via conduit 312 feeding to a fuel ring 302. In another embodiment, the carrier gas 311 is recirculated flue gas. In a further embodiment, the recirculated flue gas is treated recirculated flue gas, wherein the treated recirculated flue gas has been dehydrated and impurities removed as part of a CO2 capture process. In the separated portion of the annular shroud burner, FGR 320 is fed through FGR conduit 321, which in turn feeds to an FGR ring 304 via conduit 325. In a further embodiment, oxygen is mixed with the flue gas.

[0088] In this embodiment, the O2 conduit supplies two separate paths. One path feeds undiluted O2 into the inner O2 ring 301 via conduit 330. In the other path, undiluted O2 is delivered via conduit 335 to the outer O2 ring 303, immediately adjacent to the fuel conduit 312 (leading to the fuel ring 302). In this embodiment, the O2 flow is delivered from the same source. In another embodiment, the O2 flow is delivered from an alternative source. In this embodiment, the outer O2 ring 303 is located between the fuel ring 302 and the FGR ring 304. In a preferred embodiment, the O2 flow is on both sides of the fuel 310 leading to the fuel ring 302. This configuration provides enhanced flame stability and control. In contrast to the diluted O2 flow, the undiluted O2 flow used in this embodiment allows peak flame temperatures exceeding 4,000°F (2,204°C).

[0089] In this embodiment, fuel 310 may be a fossil fuel. Fossil fuels include oil, coal, and natural gas. In this embodiment, fuel 310 may be coal. Coal may be peat, anthracite, semi-anthracite, super anthracite, bituminous coal, sub-bituminous coal, semi-bituminous coal, or lignite. For reference, 2010 U.S. coal production is further described by coal type. Production per tonne comprises 45% bituminous coal, 47% sub-bituminous coal, 7% lignite, and 0.2% anthracite. Production per total energy comprises 54% bituminous coal, 41% sub-bituminous coal, 4.7% lignite, and 0.3% anthracite. In this embodiment, the fuel is bituminous coal or sub-bituminous coal.

[0090] Fuel, oxygen, and recirculated flue gas are connected and supplied to their respective ducts or pipes according to conventional equipment and methods. Each flow is fed directly to the combustion zone 350, where the fuel reacts with the oxidizer, and the shroud FGR acts as a temperature shield. Fuel is burned as oxygen and fuel react in the annular shroud burner head. The oxygen and fuel reaction can be initiated by heat absorbed from an external source or by a different energy source such as an igniter or an ignition flame. In an embodiment, the oxygen and fuel reaction is initiated by an igniter 315. In an embodiment, the igniter 315 is located at the center of the annular shroud burner head.

[0091] In addition to powering fuel transport, the FGR 320 can be directed to the FGR ring 304, which protects the burner interior and near-burner surfaces from the high heat flux generated. The inlet of each flow entering the furnace is configured such that the resulting flame is an axial jet, which extends the mixing rate of fuel and O2 within the furnace. Compared to other burner designs configured for rapid mixing of fuel and oxidizer (involving vortices and / or blunt bodies), the resulting heat release distribution is extended. This extended heat release distribution provides protection against the strong radiative flux generated by the high-temperature flame.

[0092] In a further embodiment, the annular shroud burner head includes a control scheme that individually adjusts the fuel flow rate, FGR flow rate, and O2 flow rate as required to control the ratio of FGR flow rate to fuel flow rate and the ratio of fuel flow rate to O2 flow rate.

[0093] The flow rate of the O2 stream is controlled such that it is in the range of approximately 25 ft / s to approximately 125 ft / s. In embodiments, the flow rate is in the range of 30 to 110 ft / s, 40 to 90 ft / s, or 50 to 70 ft / s. In embodiments, the flow rate is greater than approximately 30 ft / s, approximately 40 ft / s, approximately 50 ft / s, approximately 60 ft / s, approximately 70 ft / s, approximately 80 ft / s, approximately 90 ft / s, or approximately 100 ft / s. In the embodiments, the flow rates are approximately 30 ft / s, approximately 35 ft / s, approximately 40 ft / s, approximately 45 ft / s, approximately 50 ft / s, approximately 55 ft / s, approximately 60 ft / s, approximately 65 ft / s, approximately 70 ft / s, approximately 75 ft / s, approximately 80 ft / s, approximately 85 ft / s, approximately 90 ft / s, approximately 95 ft / s, approximately 100 ft / s, approximately 105 ft / s, or approximately 110 ft / s.

[0094] In some embodiments, the percentage of oxygen in the O2 stream can be at least 90%. In some embodiments, the O2 stream can be at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, at least about 99.6%, at least about 99.7%, at least about 99.8%, or at least about 99.9% oxygen. The O2 stream can contain oxygen between 90% and 100%, 95% and 100%, 97% and 100%, 98% and 100%, or 99% and 100%. In some embodiments, the O2 stream can contain oxygen between 91% and 99.5%, between 92% and 99%, between 93% and 98%, or between 94% and 97%.

[0095] The percentage of oxygen in the O2 stream can be adjusted to control the flame temperature. In this embodiment, using an undiluted O2 stream allows for a peak flame temperature greater than 4,000°F at the annular shroud burner. In contrast, peak flame temperatures greater than 4,000°F can be achieved when the O2 stream is diluted with other gases or contains less than 90% oxygen.

[0096] The flow rate of the primary fuel is controlled such that it is in the range of approximately 20 ft / s to approximately 150 ft / s. In embodiments, the flow rate is in the range of 30 to 125 ft / s, 40 to 100 ft / s, or 50 to 75 ft / s. In embodiments, the flow rate is greater than approximately 30 ft / s, approximately 40 ft / s, approximately 50 ft / s, approximately 60 ft / s, approximately 70 ft / s, approximately 80 ft / s, approximately 90 ft / s, approximately 100 ft / s, approximately 110 ft / s, approximately 120 ft / s, approximately 130 ft / s, or approximately 140 ft / s. In the embodiments, the flow rate is approximately 30 ft / s, approximately 35 ft / s, approximately 40 ft / s, approximately 45 ft / s, approximately 50 ft / s, approximately 55 ft / s, approximately 60 ft / s, approximately 65 ft / s, approximately 70 ft / s, approximately 75 ft / s, approximately 80 ft / s, approximately 85 ft / s, approximately 90 ft / s, approximately 95 ft / s, approximately 100 ft / s, approximately 105 ft / s, approximately 110 ft / s, approximately 115 ft / s, approximately 120 ft / s, approximately 125 ft / s, approximately 130 ft / s, approximately 135 ft / s, approximately 140 ft / s, approximately 145 ft / s, or approximately 150 ft / s. In the embodiments, the fuel flow rate is directly related to the type of fuel used. In the embodiments, the fuel flow rate may cause a change in the flame initiation position. In one embodiment, the flame initiates at the burner head face. In another embodiment, the flame initiates at a location moved away from the burner head face. When an annular shroud burner is installed near the fuel processing plant and boiler, this is considered to be the point where the flame initiation point moves away from the burner face toward the boiler.

[0097] In embodiments, the percentage of oxygen in the carrier gas is between 0% and 30%. In embodiments, the percentage of oxygen can be from 0% to 3%, from 3% to 10%, from 10% to 20%, or from 20% to 30%. In alternative embodiments, the percentage of oxygen is from about 3% to about 25%, from about 5% to about 20%, from about 10% to about 15%, or from about 10% to about 23.5%. In embodiments, the percentage of oxygen is about 0%, 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 23.5%, 25%, or 30%. In some embodiments, the percentage of oxygen is at least about 1%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, or at least about 23.5%. In embodiments, the percentage of oxygen is less than about 30%, less than about 23.5%, less than about 20%, less than about 15%, less than about 10%, less than about 5%, less than about 3%, or less than about 1%. The amount of oxygen present has an effect on the target peak flame temperature. In embodiments, the percentage of oxygen is variable, for example, the percentage of oxygen may be 23.5% for a period of time and then the percentage of oxygen may decrease, where such a decrease may reach about 0% oxygen.

[0098] Using high-purity oxygen (>95%) has several advantages compared to air-fired burners. One advantage is that when incorporated into a boiler system, oxygen-fuel combustion allows for a physically smaller boiler compared to conventional boilers. That is, because oxygen is used instead of air as the oxidant (fuel), the total oxidant available for combustion is reduced, and the volume of gas input to the boiler is less than that required when using air as the oxidant (at most 21%). Therefore, the boiler can be considerably smaller due to the use of high-purity oxygen instead of air.

[0099] The flow rate of the FGR flow 320, with or without additional O2 flow, is controlled such that the flow rate is in the range of approximately 10 ft / s to approximately 75 ft / s. In embodiments, the flow rate is in the range of 10 to 30 ft / s, 30 to 50 ft / s, or 50 to 75 ft / s. In embodiments, the flow rate is greater than approximately 10 ft / s, approximately 20 ft / s, approximately 30 ft / s, approximately 40 ft / s, approximately 50 ft / s, or approximately 60 ft / s. In embodiments, the flow rate is approximately 10 ft / s, approximately 15 ft / s, approximately 20 ft / s, approximately 25 ft / s, approximately 30 ft / s, approximately 35 ft / s, approximately 40 ft / s, approximately 45 ft / s, approximately 50 ft / s, approximately 55 ft / s, approximately 60 ft / s, approximately 65 ft / s, approximately 70 ft / s, or approximately 75 ft / s.

[0100] In an embodiment, the percentage of FGR in the FGR stream 320 may be at least 90%. In an embodiment, the FGR may be at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, at least about 99.6%, at least about 99.7%, at least about 99.8%, or at least about 99.9%. The FGR stream may contain oxygen between 90% and 100%, 95% and 100%, 97% and 100%, 98% and 100%, or 99% and 100%. In some embodiments, the FGR stream may contain between 91% and 99.5%, between 92% and 99%, between 93% and 98%, or between 94% and 97%.

[0101] In embodiments, the oxygen to fuel ratio can be varied. This ratio can depend on the purity of the oxygen supply and the nature of the fuel. For example, in an embodiment where the oxygen is 100% pure, the oxygen / fuel ratio can be about 2:1. Those skilled in the art will understand that this ratio can vary depending on the purity of the fuel and oxygen, and can be adjusted accordingly. In embodiments, the oxygen to fuel ratio is about 1:1, about 1.5:1, about 2:1, about 2.5:1, or about 3:1.

[0102] The oxygen-to-fuel ratio offers numerous advantages. For example, an approximate stoichiometric ratio ensures complete combustion of the fuel, thus resulting in significantly smaller volumes of impurities, such as NO. x Other harmful emissions. In addition, accurately controlling the oxygen-to-fuel ratio contributes to the complete combustion of fuel.

[0103] In embodiments, conduits 312, 325, 330, and 335 may contain flows different from those described above. For example, fuel conduit 312 may contain an O2 flow instead of a fuel flow. In alternative embodiments, O2 conduit 330 may contain a fuel flow. Such examples are not intended to be limiting, as it is possible to supply alternative flows via various conduits in an annular shroud burner head.

[0104] The annular shroud furnace head disclosed herein offers advantages not only in simplicity but also in the uniformity of O2 and FGR distribution. In embodiments, this design simplifies O2 and FGR delivery by replacing separate O2 and FGR ports with an annular register. Therefore, in embodiments, the annular shroud furnace head can be described as a multi-register axial jet furnace head, which allows for extended heat release and heat flux to avoid damage to the near-furnace surface while still producing a stable flame. Furthermore, the outer ring 304 of the FGR provides sufficient cooling for the furnace head and near-furnace surfaces, thereby keeping surface temperatures within permissible limits for materials conventionally used in industrial furnaces.

[0105] In a further embodiment, the annular shroud burner does not include a pre-combustion chamber.

[0106] In an alternative embodiment, FGR can be added to either O2 stream.

[0107] In a further embodiment, streams 310, 320, 331, and / or 336 avoid including nitrogen associated with air. In embodiments, streams 310 and 320 may contain less than about 20%, less than about 15%, less than about 10%, less than about 5%, or less than about 1% air. In embodiments, streams 310, 320, 331, and / or 336 contain about 0% air.

[0108] b. Flame characteristics of the annular shroud burner head

[0109] Ignition systems designed to generate flame temperatures exceeding 4,000°F (2,204°C) must be configured to prevent damage to the burner assembly and internal surfaces caused by high heat flux. Currently disclosed annular shroud burners achieve this by surrounding the high flame temperature region with a stream of cooler gas, known as a shroud. Compared to conventional burner designs, the presence of the shroud reduces the exposure of the surrounding system to high heat flux and thus reduces the risk of damage.

[0110] As described in further detail in this paper, heat flux data for undiluted oxygen input under oxy-coal combustion conditions are required. Design considerations for atmospheric oxy-coal systems using directional undiluted oxygen with minimized FGR must include an understanding of the appropriate radiative heat transfer distribution as a function of the furnace aerodynamics.

[0111] This paper describes models for accurately predicting heat transfer and surface temperature in high-flame-temperature oxy-coal combustion units. Heat transfer and surface temperature are key parameters relevant to oxy-coal combustion applications. These predictive models allow for evaluation of multi-scale experiments combined with mechanism development and computational fluid dynamics (CFD) modeling. The models were used to characterize and predict flame behavior, heat transfer, ash deposition, and ash chemical composition during high-flame-temperature oxy-coal combustion at atmospheric pressure.

[0112] Predictive CFD models have been used to evaluate burner designs for 30MWt burners applied in varied arrangements. In one embodiment, the arrangement comprises a front-wall ignition steam boiler equipped with four such burners. The heat release distribution of annular shroud burners differs from that of burners with discrete ports.

[0113] Figure 4 and Figure 5 An annular shroud furnace head is shown. Figure 4 ) and more traditional burners with discrete ports ( Figure 5A detailed comparison of the flame shapes. (e.g.) Figure 4 As can be seen, the annular shroud burner head produces an extended heat release distribution because the concentric registers of O2, fuel, and FGR result in a slower mixing rate between the fuel and O2, while the outer register of the flue gas recirculation creates a relatively cool outer envelope. The resulting heat distribution plot shows discrete bands with different flame temperatures, depending on the source. For example, in this embodiment, the inner O2 flow flame produces flame zone 361, the fuel produces flame zone 362, the outer O2 flow produces flame zone 363, and the FGR flow produces flame zone 364 (shroud). The peak flame temperature in this embodiment is 4,572°F (2,522°C). The temperature of shroud 364 is significantly lower, ranging between approximately 2,000°F (1,093°C) and 3,000°F (1,649°C). Shroud 364 surrounds the high-temperature flame zones 361, 362, and 363, thereby primarily exposing any surrounding material only to the cooler shroud flame zone 364. Therefore, when compared with the furnace heads currently known in the art, the exposure of such surrounding materials to high heat flux is thus greatly reduced.

[0114] In comparison, such as Figure 5 As can be seen, in designs with discrete ports, the alternating zones of high-speed and low-speed gases at the same radial distance from the centerline of a conventional burner head accelerate the mixing rate. Specifically, flame zone 373 is a high-temperature zone that extends radially away from the flame center. This radial extension increases the heat flux reaching the surrounding system, thus increasing the potential damage to these systems.

[0115] The experiments described in this paper are the first to provide heat flux data for undiluted oxygen input under oxy-coal combustion conditions. This was achieved under well-defined conditions to allow it to be used to validate heat transfer correlations in a CFD simulation code. CFD model predictions were confirmed by radiative heat flux data for selected test conditions in the program, demonstrating that aerodynamic staging using axial flame with slow mixing adequately expands the heat released in the furnace to avoid excessive heat flux reaching the furnace walls and burner assemblies. It has also been found that delayed mixing and high peak flame temperatures are not necessarily mutually exclusive. In other words, heat release can be expanded to distribute heat flux over a larger area of ​​the furnace while simultaneously achieving flame temperatures exceeding 4,000°F (2,204 °C).

[0116] Accordingly, methods for modeling larger-scale systems include the quantification of radiative heat flux to establish designs suitable for applications of technologies to be used at scales far exceeding that of the test furnace. Sensitivity analyses have been performed to assess the impact of the burner head design on flame behavior and the associated distribution of heat release and heat flux. Several design configurations with varying complexities have been simulated. In one case, the design is based on an axial jet burner head with an O2-rich kinetic fuel gas flow generator (FGR) for fuel delivery and discrete ports for O2 introduction. In this system, the heat flux reaching the burner head and furnace walls is unacceptably high.

[0117] In contrast, as described herein, it has been found that by introducing a non-powered supplemental FGR using a novel shroud design, the target peak temperature above 4,000°F (2,204°C) can be maintained simultaneously with reduced heat flux. The supplemental FGR is introduced into the burner shroud to provide localized cooling and prevent the burner surface temperature from exceeding permissible limits. The ring is sized to achieve a relatively low-velocity flow that keeps the recirculated gas close to the burner and absorbs heat radiated from adjacent hot spots.

[0118] In the embodiments, the peak flame temperature is in the range of about 4,000°F (2,204°C) to about 5,000°F (2,760°C), about 4,100°F (2,260°C) to about 4,900°F (2,704°C), about 4,200°F (2,316°C) to about 4,800°F (2,649°C), about 4,300°F (2,371°C) to about 4,700°F (2,593°C), or about 4,400°F (2,427°C) to about 4,600°F (2,538°C). In other embodiments, the peak flame temperature is between about 4,000°F (2,204°C) and about 4,100°F (2,260°C), between about 4,100°F (2,260°C) and about 4,200°F (2,316°C), between about 4,200°F (2,316°C) and about 4,300°F (2,371°C), between about 4,300°F (2,371°C) and about 4,400°F (2,427°C), between about 4,400°F (2,427°C) and about 4,500°F (2,4... The range is approximately 82°F (2,482°F) to approximately 4,600°F (2,538°F), approximately 4,600°F (2,538°F) to approximately 4,700°F (2,593°F), approximately 4,700°F (2,593°F) to approximately 4,800°F (2,649°F), approximately 4,800°F (2,649°F) to approximately 4,900°F (2,704°F), and approximately 4,900°F (2,704°F) to approximately 5,000°F (2,760°F). In other embodiments, the peak flame temperature is at least about 4,000°F (2,204°C), at least about 4,100°F (2,260°C), at least about 4,200°F (2,316°C), at least about 4,300°F (2,371°C), at least about 4,400°F (2,427°C), at least about 4,500°F (2,482°C), at least about 4,600°F (2,538°C), at least about 4,700°F (2,593°C), at least about 4,800°F (2,649°C), or at least about 4,900°F (2,704°C).In some embodiments, the peak flame temperature is approximately 4,000°F (2,204°C), approximately 4,050°F (2,232°C), approximately 4,100°F (2,260°C), approximately 4,150°F (2,288°C), approximately 4,200°F (2,316°C), approximately 4,250°F (2,343°C), approximately 4,300°F (2,371°C), approximately 4,350°F (2,399°C), approximately 4,400°F (2,204°C), approximately 4,450°F (2,454°C), approximately... 4,500°F (2,482°C), approximately 4,550°F (2,510°C), approximately 4,600°F (2,538°C), approximately 4,650°F (2,566°C), approximately 4,700°F (2,593°C), approximately 4,750°F (2,621°C), approximately 4,800°F (2,649°C), approximately 4,850°F (2,677°C), approximately 4,900°F (2,704°C), approximately 4,950°F (2,732°C), or approximately 5,000°F (2,760°C). In the embodiments, the peak flame temperature is about 4,572°F (2,522°C), about 4,581°F (2,527°C), about 4,133°F (2,278°C), about 4,251°F (2,344°C), or 4,033°F (2,223°C).

[0119] c. Physical characteristics of the annular shroud furnace head

[0120] The annular shroud burner disclosed herein is configured in terms of size and composition suitable for use in systems employing it. The dimensions and compositions described below are provided merely as examples and are not intended to limit the annular shroud burner disclosed herein.

[0121] Igniter 315 has an outer diameter ranging from about 2 to about 6 inches. In this embodiment, the igniter has an outer diameter of about 4 inches.

[0122] The O2 inner ring 301 has an inner diameter and an outer diameter. In an embodiment, the outer diameter is specified to be larger than the inner diameter, the inner diameter being in the range of about 4 to about 6 inches, and the outer diameter being in the range of about 5 to about 7 inches. In an embodiment, the inner diameter is about 5 or 5.3 inches, and the outer diameter is about 6 or 6.3 inches.

[0123] The fuel ring 302 has an inner diameter and an outer diameter. In an embodiment, the outer diameter is specified to be larger than the inner diameter, the inner diameter being in the range of about 10 to about 15 inches, and the outer diameter being in the range of about 12 to about 17 inches. In an embodiment, the inner diameter is about 13, 13.5, 13.6, or 14 inches, and the outer diameter is about 14, 14.5, 14.6, or 15 inches.

[0124] The O2 outer ring 303 has an inner diameter and an outer diameter. In an embodiment, the outer diameter is specified to be larger than the inner diameter, the inner diameter being in the range of about 15 to about 19 inches, and the outer diameter being in the range of about 16 to about 20 inches. In an embodiment, the inner diameter is about 17 inches and the outer diameter is about 18 inches.

[0125] The FGR ring 304 has an inner diameter and an outer diameter. In an embodiment, the outer diameter is specified to be larger than the inner diameter, with the inner diameter ranging from about 18 to about 22 inches and the outer diameter ranging from about 19 to about 23 inches. In another embodiment, the inner diameter is about 20 inches and the outer diameter is about 21 inches.

[0126] In any of the above embodiments, the sizes of the igniter and the rings follow the order from smallest to largest diameter: igniter 315 < O2 inner ring 301 < fuel ring 302 < O2 outer ring 303 < ring 304.

[0127] In this embodiment, the annular shroud burner head has a specified length. This length can be configured to fit the dimensions used in the system employing it.

[0128] The size of the burner head is related to the flow rates of fuel, O2, and FGR. Specifically, the higher the fuel flow rate, the larger the burner head.

[0129] In this embodiment, the annular shroud furnace head is made of a material suitable for use in the system employing it. In this embodiment, the annular shroud furnace head may be made of stainless steel. Stainless steel is typically classified according to a standard alloy numbering system for steel grades maintained by SAE International. Stainless steel grades are separated into separate series, including the 100, 200, 300, 400, 500, 600, and 900 series. Each series has designated variations, referred to as stainless steel designations. For example, in the 200 series are designations 201, 202, 205, 253, and 254. Non-limiting examples of suitable stainless steels include designations 253, 309, and 310.

[0130] In one embodiment, the size of the annular shroud burner head is modified to obtain desired characteristics, such as flame characteristics, ignition rate, velocity, or flow rate that can vary with fuel type and calorific value. In another embodiment, the size of the annular shroud burner head can be varied based on the burner head's ignition rate, fuel type, and calorific value.

[0131] In an embodiment, as disclosed herein, is an annular shroud burner head having a quadruple concentric burner head design, wherein the quadruple concentric burner head design includes first, second, third, and fourth conduits, wherein each conduit separately injects first, second, third, and fourth flow rates into the first, second, third, and fourth annexes, wherein

[0132] The first flow rate includes the first oxygen source.

[0133] The second flow contains a mixture of fuel and carrier gas.

[0134] The third flow rate includes the second oxygen source.

[0135] The fourth flow includes FGR.

[0136] The igniter is located at the center of the annular furnace head, and...

[0137] The outer edge of the fourth ring is made of refractory bricks.

[0138] As in any of the above embodiments of the annular shroud burner head, wherein the first oxygen source and the second oxygen source are undiluted oxygen sources.

[0139] As in any of the above embodiments, the annular shroud burner head, wherein the first oxygen source and the second oxygen source have an oxygen content of at least about 90%.

[0140] As in any of the above embodiments, the annular shroud burner head, wherein the carrier gas is FGR.

[0141] As in any of the above embodiments, the annular shroud burner head, wherein the shroud cooling design minimizes damage to the burner head components and the area near the burner head surface when compared to a conventional burner head configuration.

[0142] Such as the annular shroud burner head of any of the above embodiments, wherein the annular shroud burner head is made of stainless steel.

[0143] The annular shroud furnace head, as in any of the above embodiments, is made of stainless steel of the 200 or 300 series.

[0144] The annular shroud burner head, as in any of the above embodiments, further includes a combustion zone on the surface of the annular shroud burner head.

[0145] As in any of the above embodiments, the annular shroud burner head has a peak flame temperature of at least 4,000°F (2,204°C). In a further embodiment, the annular shroud burner head has a peak flame temperature of at least about 4,300°F (2,371°C).

[0146] As in any of the above embodiments, the annular shroud burner head has, as in... Figure 4 The depicted thermal distribution map. In a further embodiment, the thermal distribution map has an outer cooler layer. In a further embodiment, the thermal distribution map has one, two, or more high-temperature regions surrounded by cooler regions. In a further embodiment, there are two high-temperature regions surrounded by cooler regions.

[0147] As in any of the above embodiments of the annular shroud furnace head, the fuel conduit contains at least one fuel selected from the group consisting of: natural gas, hydrogen, refinery exhaust gas, refinery fuel gas, blast furnace gas, propane, fuel oil, anthracite, bituminous coal, sub-bituminous coal and lignite, tar, bituminous pitch, petroleum coke, papermaking sludge solids and sewage sludge solids, wood, peat and straw. In a further embodiment, the fuel is selected from the group consisting of bituminous coal, sub-bituminous coal and lignite.

[0148] Such as the annular shroud burner of any of the above embodiments, wherein the size of the burner is sufficient to achieve a fuel flow rate in the range of about 20 ft / s to about 150 ft / s.

[0149] d. Method of using a ring-shaped protective cover for the burner head

[0150] In one aspect, a method for burning fuel using an annular shroud burner as described herein is disclosed. Variations in flow rate, fuel mixture, oxygen content, fuel type, and many other variables are disclosed herein and are not intended to be limiting.

[0151] In a further embodiment, the method for burning fuel includes the steps of:

[0152] Provides a ring-shaped protective cover for the burner head.

[0153] The first O2 flow is supplied to the first ring through the first conduit.

[0154] A mixture of fuel and carrier gas is supplied to the second ring through the second conduit.

[0155] The second O2 flow is supplied to the third ring through the third conduit.

[0156] FGR is supplied to the fourth ring via the fourth catheter, and

[0157] Use the igniter located in the center of the annular burner head to ignite the flame.

[0158] In an embodiment, the method further includes the step of:

[0159] Control the flow rate of the O2 stream to a range of approximately 25 ft / s to approximately 125 ft / s, and

[0160] Control the flow rate of the primary fuel so that it is in the range of approximately 20 ft / s to approximately 150 ft / s.

[0161] As in any of the above embodiments, the method produces a peak flame temperature of at least about 4,000°F (2,204°C).

[0162] As in any of the above embodiments, the method produces a peak flame temperature of at least about 4,300°F (2,371°C).

[0163] As in any of the methods described in the above embodiments, wherein the flame has such Figure 4 The depicted heat distribution map.

[0164] C. Combustion and Recirculation System

[0165] The annular shroud burner described herein can be incorporated into a boiler unit, which can also be part of a technical system such as a fossil fuel power plant. In embodiments, the annular shroud burner design provides a heat release distribution in conventional front-wall ignition steam boiler configurations, substantially reducing the maximum incident heat flux on the burner assembly and reaching the front wall. The annular shroud burner further modulates the amount of FGR distributed to the combustion zone to prevent damage to the burner assembly and near-burner surfaces from extreme temperatures and heat fluxes, while minimizing the impact on peak flame temperature.

[0166] Advantages associated with systems incorporating the annular shroud burner described herein include: significantly higher flame temperatures than conventional air / fuel and other patented oxygen / fuel systems; a more directional heat release distribution with less radiant heat; a novel shroud cooling design that eliminates damage to components surrounding and near the burner surface; and ease of replacing previously existing air-fired burners with the annular shroud burner.

[0167] Figure 10 The diagram depicts a process flow illustration of an embodiment of a single-walled, fire-ignition subcritical boiler plant including the annular shroud burner disclosed herein. Figure 10 As can be seen, fuel 202 flows through the mill 206 and enters the annular shroud burner head 207 connected to the furnace 201. Water 208 flows into the furnace 201 and flows out as steam 209.

[0168] Additional components may also flow into the burner head. For example, primary FGR (PRI FGR) 204 may flow into mill 206, where it is mixed with fuel 202 before being introduced into burner head 207. Oxidant 203 (which may be essentially pure oxygen) may flow along several different paths. In one embodiment, oxidant 203 flows into mill 206, where it may be mixed with fuel 202 and / or PRI FGR 204 before being introduced into burner head 207. Oxidant 203 may also flow into burner head 207 or furnace 201. An alternative source of FGR may also be present, referred to as secondary FGR (SEC FGR) 205. SEC FGR 205 may flow into burner head 207 or furnace 208.

[0169] There are at least two output streams from the furnace: steam 209 and hot flue gas (FG) 210. Steam 209 flows from the furnace to other parts of the system, such as turbines / generators (not described here), which function to provide power generation. Another possible output stream is hot FG 210 flowing into air heater 211. In one capability, cold FG 212 flows into air heater 211, which heats the cold FG 212 and provides hot FG 213. In another capability, air heater 211 provides an output of hot FG 214 flowing into coil 215.

[0170] Coil 215 can receive cold feed water (FW) 216, heat the water, and provide hot FW 217 as a result. This flow can continue from coil 215 to electrostatic precipitator (ESP) 218, reaching flue gas desulfurization (FGD) 220. After flue gas desulfurization, FGD output 221 can flow as secondary FGR 222 to air heater (AH) or into direct contact cooler polishing scrubber (DCCPS) 223. From DCCPPS 223, FGR can flow as primary FGR 224 to air heater or as FG to CO2 processing 225.

[0171] Because the annular shroud burner generates high flame temperatures, heat transfer in the overall system is highly efficient. Further modifications to the overall system can further increase this efficiency. Such modifications include changes to the boiler's geometry (e.g., direct flame exposure of the boiler tubes), which further increases heat transfer by maximizing the metal surface area for heat transfer from flame to metal that occurs thereon. As a result, the boiler used can be physically smaller than a conventional boiler with a conventional burner.

[0172] Figures 11-18 The results of an annular shroud burner model operating in a single-wall ignition subcritical boiler system were further disclosed.

[0173] In one embodiment, as described herein, is a high flame temperature oxygen combustion system comprising:

[0174] At least one annular shroud furnace head,

[0175] Furnaces used for combustion

[0176] Space separation unit,

[0177] At least one catheter, and

[0178] The control system, wherein the annular shroud furnace head is configured to provide a peak flame temperature of at least 4,000°F (2,204°C), which has a similar characteristic to... Figure 4The heat distribution map depicted in the diagram minimizes radiant heat and potential damage to the system surrounding the annular shroud furnace head.

[0179] In an embodiment, as described herein, is a method of operating an oxygen combustion system, wherein the method comprises:

[0180] Fuel, carrier gas, and basic pure oxygen are supplied to the annular shroud furnace head.

[0181] It burns fuel, carrier gas, and essentially pure oxygen to produce a flame, which has a similar characteristic to... Figure 4 The radiative heat distribution map depicted in the image.

[0182] The water in the boiler is heated by a high-temperature oxygen-burning annular shroud furnace head to convert the water into steam.

[0183] D. Example

[0184] The following preparations and examples are given to enable those skilled in the art to better understand and practice the invention. They should not be considered as limiting the scope of the invention, but are merely illustrative and representative.

[0185] Example 1: Comparison of air-ignition combustion and oxygen-ignition combustion

[0186] Air-fired Total MW 112.0 Net MW 105.67 Light-off rate (heat input HHV), MMBtu / hr 1138.6 Net heat rate, Btu / kWh 10775 Coal flow, lb / hr 140302 Total air flow, lb / hr 93669θ Overall stoichiometric ratio 1.1036 Excess O2 in FG at furnace exit, vol% wet 1.72 Excess O2 in FG at furnace exit, vol% dry 2.0 FG economizer outlet temperature (AH inlet), F 688 AH outlet FG temperature, F 283 Atmospheric pressure, psia 12.1 Operating furnace header 12 Operating mill 8，10，11，12 Primary gas / coal 1.95 Primary gas flow, lb / hr 273590 Primary gas temperature into mill, F 582 Primary temperature into boiler, F 135 Evaporated coal moisture in mill, % 60 Secondary temperature into boiler, F 580

[0187]

[0188]

[0189] The following steam conditions were used to set the tuning parameters in the modeling of the air-ignition SGE process. Once set, the parameters remained unchanged to predict the steam conditions during oxygen ignition.

[0190] Air-fired SH flow, lb / hr 752646 SH final pressure, psig 1449 SH final temperature, F 1004 SH spray, lb / hr 23881 Primary SH outlet temperature, F 706 Roller pressure, psig 1615 Saturation temperature, F 607 Economizer output temperature, F 537 FW temperature to economizer, F 471 Economizer inlet and spray pressure, psig 1826 RH flow, lb / hr 671539 RH final pressure, psig 472 RH final temperature, F 1000 RH spray, lb / hr 86732 RH inlet temperature, F 731 RH inlet pressure, psig 513 Spray temperature, F 303

[0191] The overall results were compared between air-ignition and oxygen-ignition burners.

[0192]

[0193] *The furnace outlet is located between the SSH pressure plate and the RH hanger.

[0194] 1 From process modeling

[0195] It will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. Other aspects of the invention will be apparent to those skilled in the art in light of the description and practice of the invention disclosed herein. The description and examples are intended to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

Claims

1. A ring-shaped protective cover for a furnace head, comprising: Refractory brick having a divergent conical shape, the divergent conical shape being positioned to extend along a central axis and radially inward and define a combustion zone downstream of the radially inner surface of the refractory brick, the refractory brick extending from the furnace head face to the furnace inner wall; A first conduit, positioned to extend along the central axis and configured to provide a first oxygen flow into the combustion zone at the burner face; The second conduit is positioned to extend radially outward along the central axis from the first conduit and is configured to provide a mixed flow of fuel and carrier gas to the combustion zone reaching the burner face; A third conduit is positioned to extend radially outward along the central axis from the second conduit and is configured to provide a second oxygen flow to the combustion zone at the burner head surface; as well as A fourth conduit is positioned to extend radially outward along the central axis of the third conduit and is configured to provide a recirculated flue gas flow in the form of a conical shroud extending along the inner surface of the refractory brick from the furnace head face to the inner wall of the furnace, the recirculated flue gas flow surrounding the peak flame temperature zone within the combustion zone.

2. A method for burning fuel in an annular shroud furnace head having a refractory brick having a diverging conical shape, the diverging conical shape being positioned to extend along a central axis and radially inward and define a combustion zone downstream of the radially inner surface of the refractory brick, the refractory brick extending from the furnace head face to the furnace inner wall, the method comprising: A first oxygen flow is provided into the combustion zone via a first conduit, the first conduit being positioned to extend along the central axis and configured to lead to the refractory brick at the furnace head face; A mixed flow of fuel and carrier gas is provided to the combustion zone via a second conduit, the second conduit being positioned to extend radially outward along the central axis from the first conduit and configured to lead to the refractory brick at the furnace head face; A second oxygen flow is provided to the combustion zone via a third conduit, the third conduit being positioned to extend radially outward along the central axis of the second conduit and being configured to lead to the refractory brick at the furnace head surface; as well as A portion of the recirculated flue gas flow is provided via a fourth duct, which is positioned to extend radially outward from the third duct along the central axis and is configured to provide the recirculated flue gas flow in the form of a conical shroud extending along the inner surface of the refractory brick from the furnace head to the inner wall of the furnace, the recirculated flue gas flow surrounding the peak flame temperature region within the combustion zone.

3. The method of claim 2, wherein the first oxygen stream and the second oxygen stream comprise undiluted oxygen.

4. The method of claim 2, wherein the first oxygen stream and the second oxygen stream contain at least 90% oxygen content.

5. The method of claim 2, wherein the carrier gas comprises recirculated flue gas.

6. The method of claim 2, wherein the first oxygen stream and the second oxygen stream contain at least 95% oxygen content.

7. The method of claim 2, wherein the peak flame temperature within the combustion zone is at least 2,204°C.

8. The method according to claim 2, wherein the fuel is selected from the group consisting of: natural gas, hydrogen, refinery exhaust gas, refinery fuel gas, blast furnace gas, propane, fuel oil, anthracite, bituminous coal, sub-bituminous coal and lignite, tar, bituminous pitch, petroleum coke, papermaking sludge solids and sewage sludge solids, wood, peat and grass.

9. The method according to claim 2, wherein the fuel is selected from the group consisting of bituminous coal, sub-bituminous coal and lignite.

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