CA2783884A1 - Methods and systems for improving combustion processes - Google Patents

Abstract

Methods, systems, and kits directed to improving combustion processes. In one embodiment, a method includes applying air to an internal surface of a combustion system. The air may be applied with a velocity chosen from about 50 m/s to about 300 m/s, and a volumetric flow chosen from about 50 ACFM to about 4000 ACFM. At least one FCT chemical may be optionally fed with the injected air in this embodiment.

Description

METHODS AND SYSTEMS FOR IMPROVING COMBUSTION PROCESSES
Field of Technology [0001] The present inventions relate generally to methods and systems for improving combustion processes, and more particularly to methods and systems for reducing the occurrence of at least one combustion problem chosen from ash accumulation, corrosion and incomplete combustion.
Background [0002] Combustion systems are known in the art and can include, for example, pulverized coal plants, circulated fluidized beds, gas-fired systems, oil-fired systems, waste incinerators, direct-fired process heaters, tangentially-fired boilers, wood burning systems, etc. Common elements of various combustion systems typically include a combustion chamber and a burner for igniting fuel located in the combustion chamber.
Figure 1 shows one example of a combustion system 1 including boiler 2 and combustion chamber 4. Fuel (e.g. coal) is fed through feed 5 to combustion chamber 4, where it is rapidly ignited by burners 5a to create flame 5b. The resulting flame sends heat and/or flue gas into various areas of the system, e.g. 6a, 6b, 6c, 6d, 6e, etc.
Combustion system parts can include walls 7a, boiler drum 7b, superheater 7c, reheater 7d, economizer 7e, and air heater 7f.

[0003] To briefly summarize operation of the depicted combustion system, but without limitation, boiler drum 7b is where steam produced by combustion is separated from water. Steam then travels to superheater 7c where its temperature increases rapidly.
From superheater 7c, steam is piped to a turbine (not shown). Steam from the turbine is returned to reheater 7d, where it is reheated. From reheater 7d, steam is piped to another turbine stage (not shown). Steam from this turbine stage is then condensed before being reheated in economizer 7e. From economizer 7e, steam can be fed to drum 7b to repeat the cycle. Those of ordinary skill in the art will recognize that the above description of parts and function is illustrative, and that combustion systems may come in a variety of different configurations. Regardless of the combustion system's construction, efficient operation is desirable.

[00041 Combustion, however, can create several problems that contribute to reduced efficiency or increased operating costs in systems having boilers as well as other types of combustion systems. For example, combustion may produce the accumulation of material, such as ash 8 on internal surfaces, e.g., walls 7a, boiler drum 7b, superheater 7c, reheater 7d, and economizer 7e, or other upstream or downstream parts. Ash accumulation is undesirable because it results in, inter alia, a loss of heat transfer, slag formation, fouling, pressure drop across heat transfer surfaces, clinkers, plugging, etc.
Further, corrosion 10 may occur as a result of ash accumulation, potentially requiring expensive repairs to system parts, e.g., tube surfaces of a boiler. As a result, some try to remove ash accumulation by physical means, e.g., soot blowing, detonation, or shotgunning. Some also try to remove ash accumulation by chemical injection or by sonic disruption.

[00051 Another problem sometimes present in combustion systems is the occurrence of incomplete combustion, which can result in significant amounts of unburned fuel and lost energy.

[0006] The various embodiments of the invention provide various advancements in the art.

Summary [0007] By way of summary, the disclosure is directed to, inter alia, reducing the occurrence of at least one problem chosen from ash accumulation and corrosion.
The disclosure is also directed to, inter alia, catalyzing combustion, e.g., reducing the amount of unburned fuel in a combustion system.

[0008] In some embodiments, the invention includes methods for reducing the occurrence of at least one of ash accumulation and corrosion. One embodiment includes providing a combustion system capable of emitting a flue gas and applying air to an internal surface of the combustion system (an ISCS) to reduce the occurrence of at least one of ash accumulation and corrosion. In one embodiment, the application of air to the ISCS occurs by transferring air from one or more entry points of the combustion system to the ISCS using at least one apparatus. Air is often applied with a velocity chosen from about 50 to about 300 m/s, and a volumetric flow chosen from about 50 to about actual cubic feet per minute (ACFM). In one embodiment, air application is sufficient to increase the oxygen concentration in flue gas contacting an ISCS portion of concern to about 2% or greater. In another embodiment, air application is sufficient to decrease the CO concentration in flue gas contacting the ISCS to less than 5000 ppm CO. In another embodiment, at least one fireside chemical treatment (FCT) chemical is applied into the combustion system to further reduce the occurrence of at least one of the above mentioned problems. In another embodiment, at least one FCT chemical is fed into the applied air such that the at least one FCT chemical and air are applied together, for example, via one or more apparatuses configured to apply air and at least one FCT
chemical.

[0009] The invention also includes treatment systems and methods for reducing the occurrence of at least one problem chosen from ash accumulation and corrosion. One embodiment includes at least one apparatus configured to transfer air through one or more combustion system ports. In one embodiment, an air mover, e.g. a blower or compressor, is connected to the apparatus and is configured to generate an air velocity chosen from about 50 to about 300 m/s, and a volumetric flow chosen from about 50 to about 4000 ACFM. In another embodiment, an apparatus is in communication with a chemical storage system, e.g. the apparatus is in communication with a passage for feeding at least one FCT chemical to the apparatus. In another embodiment, an apparatus is in communication with a liquid supply.

[0010] The invention also includes combustion systems having improved efficiency. One embodiment includes a combustion system having a treatment system for reducing the occurrence of at least one problem chosen from ash accumulation and corrosion.

[0011] The invention also includes kits for reducing the occurrence of at least one problem chosen from ash accumulation and corrosion. One embodiment includes an apparatus having an air mover-interface and an air mover having an apparatus-interface.
The apparatus and the air mover are configured to functionally connect through their interfaces. The air mover is configured to generate an air flow velocity of about 50 to about 300 m/s, and a volumetric flow of about 50 to about 4000 ACFM. In another embodiment, the kit includes a port-mount configured to attach to the apparatus and mount to a port of a combustion system. In another embodiment, the kit includes a chemical delivery system configured to feed at least one FCT chemical to the apparatus.

[0012] In some embodiments, methods, systems and kits can also be used to catalyze combustion.

[0013] The above summary was intended to summarize certain embodiments of the invention. Methods, systems, and kits of the invention will be set forth in more detail, along with examples, in the figures and detailed description below. It will be apparent, however, that the detailed description is not intended to limit the present invention, the scope of which should be properly determined by the appended claims.

Brief Description of the Figures [0014] Figure 1 illustrates a combustion system known in the art.

[0015] Figure 2 illustrates a combustion system according to an embodiment of the invention.

[0016] Figure 3 illustrates one embodiment of a treatment system of the invention.

[0017] Figure 4 illustrates another embodiment of a treatment system of the invention.

[0018] Figure 5 illustrates one embodiment of a kit of the invention.
[0019] Figure 6 illustrates another embodiment of a treatment system.

[0020] Figure 7 is a schematic of another embodiment of a combustion system of the invention.

[0021] Figure 8 is a schematic of one embodiment of a chemical delivery system of the invention.

Detailed Description of Certain Embodiments [0022] This disclosure is directed to methods, systems, and kits for reducing the occurrence of problems on an internal surface of a combustion system (ISCS).
Additionally, embodiments of the invention are directed to combustion systems operated with improved efficiency. The current disclosure is readily understood by one of ordinary skill in the art in light of the definitions and detailed description below.
Definitions:
[0023] As used herein:

[0024] A combustion system is any system having a chamber and an apparatus, e.g. a burner, for burning/producing an exothermic reaction of a fuel/combustion medium, e.g. a solid or liquid, located in the chamber.

[0025] A combustion system's radiant zone is any area in a combustion system that is visibly in line with a flame produced by at least one burner. It should be noted that if an object is positioned within the radiant zone, all surfaces of the object within the radiant zone are considered to be in the radiant zone. For example, surfaces of the object that face the flame, as well as surfaces of the object opposite from the flame, are considered to be in the radiant zone. Figure 2 illustrates one example of a radiant zone, zone 28a, showing a plurality of surfaces contained within zone 28a.

[0026] A downstream radiant zone is the portion of the radiant zone from the downstream-most burner to the downstream-most portion of the radiant zone.
Figure 2 illustrates one example of a downstream radiant zone, zone 28d, showing a plurality of surfaces contained within zone 28d.

[0027] An upstream radiant zone is the portion of the radiant zone from the upstream-most burner to the upstream-most portion of the radiant zone. Figure illustrates one example of an upstream radiant zone, zone 28b, showing a plurality of surfaces contained within zone 28b.

[0028] A burner zone is the portion of the radiant zone adjacent to the burner or from the downstream-most burner to the upstream-most burner. Figure 2 illustrates one example of a burner zone, zone 28c, showing a plurality of surfaces contained within zone 28c.

[0029] A combustion system's convection zone is the area of the combustion system from the downstream-most portion of the radiant zone to the combustion system exit. Figure 2 illustrates one example of a convection zone, zone 28e, showing a plurality of surfaces contained within zone 28e.

[0030] An internal surface of a combustion system or ISCS includes any surface of a combustion system located in the radiant zone or the convention zone of a combustion system.

[0031] A fireside chemical treatment chemical or FCT chemical is a chemical capable of at least one of reducing ash accumulation, reducing corrosion, or catalyzing combustion. Exemplary FCT chemicals for reducing ash accumulation include Mg, Ca, Cu, Al, K, and Mn, and their salts, as the active groups, e.g., MgO, Mg(OH)2, MgCl2, Ti02, A1203, CuC12.3Cu(OH)2 (Copper Oxychloride), MnC12, Ca(N03)2, NH4NO3. FCT
chemicals are also inclusive of FCT chemicals as described above in hydrated form, e.g., A1203(H20)X. Exemplary FCT chemicals for reducing corrosion or further reducing corrosion beyond the use of FCT chemicals capable of reducing ash accumulation include sulfur-based compounds capable of releasing SO2 or SO3, e.g., a sulfate salt, a bisulfate salt, sulfur, sulfuric acid, or ammonium sulfate ((NH4)2SO4). FCT chemicals capable of catalyzing combustion include chemicals capable of reducing the amount of unburned carbon in fuel/combustion medium burnt in the combustion chamber, e.g., by lowering the ignition temperature. Exemplary FCT chemicals for catalyzing combustion include copper, manganese, and calcium nitrate. FCT chemicals are also inclusive of FCT
chemicals as described above in combination with other elements, for example, silica in combination with MgO or CaO may be used.

[0032] Ash accumulation includes any accumulation of ash or other fuel components that occurs on surfaces in the radiant zone or convection zone. Ash accumulation is intended to be inclusive of fouling, slag, clinker, and the various other terminologies used in the art to refer to the accumulation of ash and other fuel components. Fouling, for example, can refer to the accumulation of ash or other fuel components in the convection zone. Slag, for example, can refer to the accumulation of ash or other fuel components in the radiant zone. Clinkers can refer the accumulation of slag in an amount large enough to dislodge from a surface under its own weight. A
variety of other terminologies may be used, sometimes interchangeably, depending on the location or type of combustion system, and it should be clear that ash accumulation encompasses all such terminologies unless otherwise indicated. Examples of ash accumulation include the accumulation of sodium and potassium salts of sulfates.

[0033] In addition to being inclusive of ash and fuel components that adhere directly to surfaces, ash accumulation is also inclusive of ash and fuel components that adhere indirectly to surfaces or that adhere both directly and indirectly, e.g., ash and fuel components whose adherence to surfaces is facilitated or further facilitated by the addition of chemistry into the combustion system. For example, in some situations chemical compounds may be added to the combustion system to improve operating efficiency, and the chemical compounds or their reaction products may accumulate on various surfaces in a manner that increases the accumulation of ash and fuel components.
For example, when a selective catalytic reduction (SCR) system is in use, ammonia or an ammonia precursor may react with SO3 in the flue gas to form ammonium bisulfate.
Ammonium bisulfate may accumulate on surfaces in a manner that causes, or increases, the accumulation of ash and fuel components. Applicants believe that indirect adherence may be more problematic in areas of the convention zone, and in particular in areas of the convection zone having temperatures less than about 800 F, and more typically in areas having a temperature chosen from about 300 to about 700 F.

[0034] Combustion problems include ash accumulation, corrosion, and incomplete combustion.

[0035] Figure 2 illustrates one example of a combustion system 20 including combustion chamber 24. Fuel is injected into chamber 24 through feed 25, where it is ignited by burners 25a, thereby producing flame 25b and flue gas 25c. The combustion process may cause at least one problem chosen from ash acumulation and corrosion on any number of the internal surfaces of a combustion system (the ISCSs).

[0036] In system 20, for example, ISCSs capable of experiencing at least one of the above mentioned problems include internal walls 27a, boiler drum 27b, superheater 27c, reheater 27d, economizer 27e, etc. In other combustion systems, ISCSs may be somewhat different, e.g., of a different size, location, or function.

[0037] In some combustion systems, it may be useful to further define physical location based on radiant zones and convection zones. For example, system 20 illustrates radiant zone 28a and convection zone 28e. Radiant zone 28a may be further divided into upper radiant zone 28b, burner zone 28c, and lower radiant zone 28d. Ash accumulation and corrosion are illustrated at 25c in lower radiant zone 28d; at 25d in burner zone 28c;
at 25e in upper radiant zone 28b, and at 25f in convection zone 28e.

[0038] Combustion system 20 also includes at least one treatment system, e.g., 32a, 32b, 32c, or 32d, for reducing the occurrence of at least one of ash accumulation and corrosion. Treatment systems may also be used to catalyze combustion, for example, in areas of the combustion system experiencing incomplete combustion. Figure 3 shows a close-up view of one embodiment of a treatment system, treatment system 32a.
Treatment system 32a is positioned adjacent to the wall of combustion chamber 24, which defines port 29. Ports may vary from embodiment to embodiment. For example, port 29 may be a preexisting viewing port, or a port added to accommodate treatment systems of the invention. A plurality of ports 29 may be seen in Figure 2.
Referring back to Figure 3, system 32a includes apparatus 34 configured to provide air through port 29.
Air mover 36 is connected to apparatus 34. As used herein, air mover is intended to include blowers and compressors. In the embodiment shown, apparatus 34 includes air mover-interface 34a, and air mover 36 includes apparatus-interface 36a, which allow the apparatus and air mover to functionally connect through their respective interfaces. In the depicted embodiment, air mover-interface and apparatus-interface are connected through flexible portion 38, which may be used to allow application apparatus 34 to achieve a sufficient range of motion for installation and operation. Flexible portions may be connected to either interface or may be distinct pieces. Other embodiments include other interface structures.

[00391 In many embodiments, the air mover is mounted directly to the apparatus, meaning it is positioned from at least one of within 5 feet of the apparatus, within 4 feet of the apparatus, within 3 feet of the apparatus, or within 2 feet of the apparatus. Such embodiments may be used to provide compact, independent systems that are readily movable and adjustable to target a variety of problems in a variety of locations.

[00401 Air movers may vary from embodiment to embodiment. In many embodiments, air movers will be configured to generate an air flow velocity of about 50 m/s to about 300 m/s. In some embodiments, air movers will be configured to generate an air flow velocity of about 100 m/s to about 150 m/s. In some embodiments, air movers are configured to generate a volumetric flow of about 50 to about 4000 actual cubic feet per minute (ACFM). Volumetric flow is often chosen from at least one of about 100 to about 3500 ACFM, about 150 to about 3500 ACFM, about 200 to about 3000 ACFM, about 250 to about 2500 ACFM, about 300 to about 2500 ACFM, about 350 to about 2500 ACFM, about 400 to about 2500 ACFM, about 450 to about 2500 ACFM, about 500 to about 2500 ACFM, about 550 to about 2500 ACFM, about 600 to about 2500 ACFM, about 650 to about 2500 ACFM, about 700 to about 2500 ACFM, about 750 to about 2500 ACFM, about 800 to about 2500 ACFM, about 950 to about 2500 ACFM, and about 1000 to about 2000 ACFM. In many embodiments, volumetric flow will be chosen from about 1000 to about 2000 ACFM. A suitable air mover, by way of example, includes a 480 VAC, 15 horsepower blower.

[0041] In many embodiments, apparatuses will also include a nozzle, e.g.
nozzle 34b, to facilitate the desired flow rate or volume or both. In one embodiment, the nozzle will be convergent, as shown.

[0042] Apparatuses may also be configured to deliver at least one FCT
chemical. For example, treatment system 32a includes an FCT delivery passage 40, e.g.
a lance, tube or pipe, which is suitable for applying at least one (FCT) chemical into application air. Passage 40 is in communication with chemical storage system 42, which may include a variety of silos or tanks of various sizes. Chemical delivery systems, e.g.
system 44, may be positioned to functionally interface storage system 42 with apparatus 34. Delivery systems include blowers, mechanical feeders, e.g., screw feeders, or pump skids, for example. In some instances, apparatuses may be gravity fed or fed through the force of the air mover. In other embodiments, the at least one FCT chemical may be delivered to other parts of the combustion system in other ways.

[0043] Storage system 42 is also representative of a storage system for a liquid source, e.g., water, such that a liquid is in communication with apparatus 34.
Storage system 42 is also representative of a dual storage system for FCT chemicals and liquids.
In such embodiments, the apparatus can inject a dual liquid/FCT stream.

[0044] As mentioned, Figure 2 shows several treatment systems, for example, treatment systems 32a, 32b, 32c, etc. Figure 4 shows a close up view of system 32b, which is configured for air application. In this embodiment, system 32b includes apparatus 54 and air mover 56, both of which may be similar to the embodiments previously described. System 32 does not contain an FTC passage or storage system.
Additionally, system 32a is shown with port-mount 60. Port-mounts may have a variety of structural configurations, but are typically configured to help stabilize the apparatus for application of air. In the embodiment shown, the port-mount is attached to the wall in an area adjacent to the port, but in other embodiments, port mounts may attach at other places, e.g., the floor. In some embodiments, the port-mount will be configured to allow the injector to inject in a plurality of directions. In the embodiment shown, for example, injector 54 pivots about axis 60a to allow for injection in a plurality of directions.

[0045] In some instances, it may be desirable to include a control system, e.g., CPU 50, that is functionally interfaceable with one or more treatment systems or the various components of treatment systems. Control systems may be used to control, for example, air flow, volumetric flow, chemical injection, liquid injection, or any combination thereof. In some embodiments, systems may be remotely controlled or may be controlled by a switch, valve, or dial.

[0046] The current disclosure is also directed to methods. Many embodiments are directed to methods of operating a combustion system to reduce at least one problem chosen from ash accumulation and corrosion. Embodiments may also be directed to catalyzing combustion. Although methods may be explained, at least in part, in light of the systems described above, methods are not limited by the system descriptions, which are used simply to facilitate an understanding of the invention.

[0047] In many embodiments, methods include providing a combustion system capable of emitting a flue gas and applying air to an internal surface of the combustion system (an ISCS) to reduce the occurrence of at least one combustion problem, e.g., at least one of ash accumulation, corrosion and incomplete combustion. Providing a combustion system may vary from embodiment to embodiment. In some embodiments, providing includes constructing a combustion system. In other embodiments, providing includes locating a combustion system. In other embodiments, providing includes gaining access to a combustion system, e.g. for the purpose of installing a treatment system. In other embodiments, providing is achieved by operating a combustion system.

[0048] The application of air to the ISCS occurs by transferring air from one or more entry points of the combustion system to the ISCS using at least one apparatus.
Entry points include, for example, the various ports described above, which can be used or created to gain access to a combustion chamber or an ISCS. Apparatuses include any structure capable of achieving the desired air transfer, e.g., any of the apparatuses shown or described herein. Some apparatuses are configured to point in a variety of directions by being adjustably positioned within a given port, e.g., pivotally mounted.
In some embodiments, a plurality of ports may also be used to inject into the system at various locations or to point at particular ISCSs. Further, in some embodiments it may be necessary to apply air through a port that is upstream from an ISCS of concern to allow the applied air to contact the ISCS.

[0049] Air velocity and volumetric flow may vary from embodiment to embodiment. For example, air may be applied with a velocity chosen from about 50 to about 300 m/s, more typically, chosen from about 100 m/s to about 150 m/s. In many embodiments, air will be applied with a volumetric flow chosen from about 50 to about 4000 ACFM. In some embodiments, volumetric flow will be chosen from at least one of about 100 to about 3500 ACFM, about 150 to about 3500 ACFM, about 200 to about 3000 ACFM, about 250 to about 2500 ACFM, about 300 to about 2500 ACFM, about 350 to about 2500 ACFM, about 400 to about 2500 ACFM, about 450 to about 2500 ACFM, about 500 to about 2500 ACFM, about 550 to about 2500 ACFM, about 600 to about 2500 ACFM, about 650 to about 2500 ACFM, about 700 to about 2500 ACFM, about 750 to about 2500 ACFM, about 800 to about 2500 ACFM, about 950 to about 2500 ACFM, and about 1000 to about 2000 ACFM.

[0050] In some embodiments, application of air will be sufficient to raise the ash-fusion temperature of ash in the flue gas that contacts the ISCS. Not to be limited to any particular mechanism, applicants believe that ash-fusion temperature may be increased by, inter alia, increasing the oxygen concentration of the flue gas contacting the ISCS or by decreasing the CO concentration, or by a combination of both. For example, applicants believe that when the flue gas oxygen concentration is about 0.5%
or lower, the ash-fusion temperature is lower and the propensity of ash to accumulate and cause corrosion increases. Raising the ash-fusion temperature may be advantageous in both the radiant zone and in the convection zone, but applicants believe it to be particularly advantageous in the radiant zone.

[0051] To determine if the ash-fusion temperature is increased, a pre-treatment measurement of ash-fusion temperature can be obtained by molding a sample of ash into the form of a cone having a given dimension and placing that sample into an oven along with a temperature probe at a given temperature. Temperature in the oven is then increased. The sample can then be viewed through an observation window to record the deformation temperature (temperature where the tip of the cone first become rounded). A
treatment measurement is then obtained by following the same procedure, while exposing the treatment sample to a treatment as described herein.

[0052] In some embodiments, applied air is sufficient to increase the oxygen concentration in flue gas contacting the ISCS portions of concern to about 2%
or greater, typically greater, e.g., 2.5%, 3%, 3.5%, 4%, 4.5%, etc. In some embodiments, air is applied by pulling ambient air using a blower or other device positioned outside of the combustion chamber. As a result, oxygen concentrations of the injected air may range from about 10% to about 30%, more commonly about 20%. In some embodiments, the oxygen concentration may be increased, for example, with 02 or 02 enriched air.

[0053] In some embodiments, the applied air is sufficient to decrease the CO
concentration in flue gas contacting the ISCS from above 5000 ppm CO to less than 5000 ppm CO. As a result, localized areas of lower CO concentration adjacent to the ISCS
may be created. In some instances, CO concentration may be lowered to at least one of below about 4000 ppm, below about 3000 ppm, below about 2000 ppm, or below about 1000 ppm CO. In other embodiments, CO concentration may be lowered to at least one of below about 500 ppm, below about 400 ppm, below about 300 ppm, below about ppm, or below about 100 ppm.

[0054] In some embodiments, the oxygen concentration of the applied air will be sufficient to raise the oxygen concentration of the flue gas contacting the ISCS, e.g., to about 2% or greater, and will be sufficient to lower the CO concentration of the flue gas contacting the ISCS to at least one of less than about 5000, less than about 4000, less than about 3000, less than about 2000, or less than about 1000 ppm.

[0055] The determination of CO and oxygen levels may be performed using any of the various measurement probes known in the art, for example, a water cooled extraction probe, such as an HVT probe available from Grace Consulting, Inc.
For making the measurements referenced herein the probe may be placed within three feet of the ISCS of concern. As used herein, flue gas traveling within three feet of a ISCS is considered to contact the ISCS or considered to contain ash capable of contacting the ISCS. In some situations, probe positioning may be difficult to achieve due to, for example, port location or combustion system configuration. In such situations, measurements may be taken from the closest available port and CO and oxygen levels at the ISCS of concern may be estimated using computational fluid dynamics (CFD) modeling software, e.g., FLUENT software available from Fluent, Inc. of Lebanon, NH.

[0056] Some embodiments also include applying an effective amount of at least one fireside chemical treatment (FCT) chemical into the combustion system. FCT
chemicals may be applied in a variety of ways. In some embodiments, FCT
chemicals will be fed into the applied air, e.g., using apparatuses, feeders and passages previously described, such that FCT chemicals and air are applied simultaneously. Feeding an FCT
chemical into the applied air may be useful for, inter alia, allowing the FCT
chemical to be delivered to a localized area of lower CO concentration created by the applied air. In other embodiments, FCT chemicals may be applied in other ways, e.g., using other devices in other locations, such as, upstream or downstream from the applied air.

[0057] As used herein, an effective amount of at least one FCT chemical is any amount sufficient to reduce at least one of ash accumulation and corrosion relative to applied air alone, or any amount sufficient to catalyze combustion in a manner that reduces the quantity of unburned fuel relative to applied air alone. FCT
chemicals may be applied at a variety of rates depending on the combustion system parameters. Suitable rates may include, for example, at least one rate chosen from 5 to 100 pph.
Suitable rates may also include higher rates, e.g., at least one rate chose from 100 to 200 pph or 200 to 300 pph may be used. Still, higher rates may be required in some situations, e.g., large boilers may require higher rates exceeding 300 pph or exceeding 400 pph.

[0058] As illustrated in Figure 2, ISCSs of concern may be located in a variety of locations, e.g., in an upstream radiant zone, in a burner zone, in a downstream radiant zone, in a convection zone, or any combination thereof. As such, methods include positioning the at least one application apparatus in a variety of locations.
Suitable locations include positioning the apparatus to apply through at least one port positioned in the wall of the combustion system. Walls may be a wall surrounding an upstream radiant zone, a wall surrounding a burner zone, a wall surrounding a downstream radiant zone, or a wall surrounding a convection zone. In many embodiments, positioning may be in any combination of the above mentioned walls. Commonly, ISCSs of concern will be in an area having a sub-stoichiometric air-fuel ratio (AFR), e.g., where there is less oxygen than is required for full combustion. In some systems, areas having a sub-stoichiometric AFR are more likely to accumulate ash or corrode, and may be readily effected by systems and methods according to the instant disclosure.

[0059] Some embodiments of the invention also include applying over-fired air (OFA) into the combustion system. OFA includes applying an amount of air sufficient to bring an air-fuel ratio (AFR) in a combustion system to at least stoichiometric.
Oftentimes OFA is applied at about 1 to about 40% excess combustion air.
Excess combustion air is the percentage of air in excess of the theoretical amount of air required for a stoichiometric mixture based on the amount of fuel being fed into the combustion system. It should be clear from the description contained herein that applying air into a combustion system through at least one application apparatus to treat an ISCS
is not applying OFA.

[0060] In embodiments where OFA is applied, applying air into the system through at least one application apparatus to treat an ISCS may include, for example, applying in the radiant zone at a location upstream from where the OFA is applied and downstream from where the OFA is applied.

[0061] Methods may also include applying at least one reducing agent into the combustion system in an amount sufficient to lower NOx emissions. Suitable reducing agents include, for example, at least one of urea, methylol urea, methylol urea-urea condensation product, dimethylol urea, methyl urea, dimethyl urea, urea analogs, urea hydrolysis products, urea pills, ammonia, ammonia salts, ammonium carbamate, ammonium carbonate, ammonium bicarbonate, ammonium formate, ammonium oxalate, hexamethylenetetramine, ammonium salts of organic acids, 5-membered heterocyclic hydrocarbons having at least one cyclic nitrogen, 6-membered heterocyclic hydrocarbons having at least one cyclic nitrogen, hydroxy amino hydrocarbons, cyanuric acid, amino acids, proteins, monoethanolamine, guanidine, guanidine carbonate, biguanidine, guanylurea sulfate, melamine, dicyandiamide, calcium cyanamide, biuret, or 1,l'-azobisformamide. Reducing agents may be applied through apparatuses described above, for example, in combination with applied air, or by other methods, e.g., injectors positioned to inject into the radiant zone or the convection zone.

[0062] Some embodiments also including identifying an ISCS exhibiting at least one of the aforementioned problems and pointing at least one application device in the direction of the identified portion of the ISCS. ISCS identification may vary from combustion system to combustion system and within individual combustion systems.
The identification of ISCSs of concern may be performed in a variety of ways, for example, by visual inspection, e.g., by spotting ash accumulation or corrosion; by decreased boiler efficiency; or by historical knowledge of system performance.
Identification may also be facilitated by the use of a probe to determine surfaces or locations where oxygen concentration may be below a certain threshold (e.g., less than about 1% or less than about 0.5%), or where CO concentration may be greater than a certain threshold (e.g., greater than about 2000 ppm, about 3000 ppm, about x4000 ppm, about 5000 ppm, or about 6000 ppm).

[0063] In many embodiments, methods of the invention will also include injecting a liquid with the injected air, thereby creating a dual liquid/air stream.
Typically, the liquid will be water. In other embodiments, injecting may include air, liquid, and at least one FCT chemical, e.g., creating a slurry or suspension of FCT

chemical, which may further facilitate applying air and at least one FCT
chemical to an ISCS of concern.

[0064] Figure 2 may be used to illustrate some method embodiments according to the invention. For example, in one embodiment, visual inspection through port 29 reveals the accumulation of ash 25c1 on a surface of superheater 27c. System 32a, including apparatus 34 (e.g., shown in Figure 3), is positioned to transfer air from outside of the combustion chamber to superheater 27c. Air x is applied through system 32a at 150 m/s and 1500 ACFM downstream from OFA in a manner sufficient to effectuate a reduction in ash accumulation 25c1. Reduction is effectuated, at least in part, by raising the ash-fusion temperature of ash contained in flue gas 25c, which contacts superheater 27c. This method further decreases corrosion of superheater 27c.

[0065] In another embodiment, decreased heat transfer and historical knowledge of system performance indicates the accumulation of ash 25c2 on another surface of superheater 27c. Air y is applied through system 32a at 200 m/s and 2500 ACFM, thereby creating a localized area of lower CO concentration z in flue gas contacting the superheater. Mg(OH)2 is co-administered at 30 pph with the applied air y such that it travels into area z and reduces the accumulation of ash 25c2. Other embodiments are readily understandable in light of the disclosure contained herein. For example, system 32 may be positioned to treat ash accumulation or corrosion 25f on reheater 27d in convection zone 28e. Treatment may be achieved by the application of air or by the application of air in combination with an FCT chemical. Additionally, system 32c may be used to apply air and an FCT chemical for catalyzing combustion into an area of the combustion chamber experiencing incomplete combustion, e.g., adjacent to walls.

[0066] The current invention also includes kits for applying air and optionally chemical to an ISCS to reduce the occurrence of at least one problem chosen from ash accumulation and corrosion. Kits may also be used for catalyzing combustion.
Figure 5 illustrates components and optional components of one embodiment of a kit 70.
Kit 70 includes apparatus 72 configured to connect with air mover 74. Connection may be achieved by connecting air mover-interface 72b to apparatus-interface 74a through flexible portion 79. Air movers and apparatuses used in the various kit embodiments may be any of those of the treatment systems described above. \

[0067] Kits will also commonly include a port-mount, e.g. port-mount 80, configured to stabilize apparatuses for application through a port, sometime in a plurality of directions.

[0068] Kit 70 may also include any or all of FCT passage 82, chemical delivery system 84 (depicted as a screw feed having housing 84a and screw 84b), or chemical storage system 86. These components are all configured to assemble, e.g., to make treatment systems similar to those described above.

[0069] Kits may also include a control system (e.g., system 50 of Figure 2) that is functionally interfaceable with the treatment system. In many embodiments, it may be desirable to control, for example, air flow, volumetric flow, chemical injection, liquid injection, or any combination thereof, for example.

[0070] Figure 6 shows a partial view of another embodiment of a treatment system 90. System 90 includes apparatus 92 configured to inject through one of the ports previously described. An air mover (not shown in this figure) connects to apparatus 92 through air mover-interface 92a through flexible portion 94, such as, 3 inch hose having a high temperature resistance. The air mover in this embodiment may be any of those previously described.

[0071] Treatment system 90 also includes FCT delivery passage 96 feeding to the apparatus. In this embodiment, a plurality of feed tubes, 100a, 100b, and 100c feed to passage 96. The feed tubes could be used to feed a variety of different FCT
chemicals or liquids. For example, tube 100a could be in communication with any of the FCT
chemicals described above; tube 100b could be in communication with another of the FCT chemicals described above; and tube 100c could be in communication with a liquid source, e.g., water, thereby potentially creating a dual chemical/liquid stream for injection. Valves 102a, 102b, and 102c can be used to optionally control flow of any ingredient. System 90 is also readily adapted to create kits of the instant invention, as described above.

[0072] Figure 7 shows a schematic of one embodiment of combustion system according to the invention. Combustion system 110 shows apparatuses 112a and 112b positioned to transfer air into combustion chamber 114. Apparatuses 112a and 112b are in communication with water regulator 116, compressed air regulator 118, and chemical pump skid 120 through passage assemblies 122a, 122b, 122c. Passage assemblies 122a, 122b, 122c include gate valves G and 20 psi check valves C. Portions 115 illustrate the combination passage-apparatus assembly.

[0073] Apparatuses 112a and 112b are also in communication with 480 VAC, 15 HP blower motor 124, having air inlet 124a and air outlet 124b. Blower is flexibly connected to manifold 126 through 6 inch low temperature blower hose 128.
Manifold 126 is flexibly connected to apparatuses 112a and 112b through 3 inch low temperature blower hose 130a and 3 inch high temperature blower hose 130b. Waste gate 132 is also connected to manifold 126.

[0074] Figure 8 shows a schematic of one embodiment of a chemical delivery system of the invention. Delivery system 140 is configured to deliver chemicals from chemical storage 142 to passage assemblies 144 via lines 146 and 148. Passage 144 may be any of the passages previously described as feeding FCT chemicals to apparatuses of the invention. Variable torque pump 150 is used to vary chemical feed based on load input 152, e.g., analog 4-2OmA load following. Input 154 is used to remotely start and stop pump 150. A pressure reducing valve 156 set at 300 psi and a 50 psi check valve 158 are used to additionally regulate pressure. A 1,000 ml calibration column 160 is used to calibrate chemical injection as needed. Bucket strainer 162 is used to strain chemicals prior to injection. Gate valves G and drains D are also used to facilitate flow control.
Lines Lure 1 inch stainless steel header assemblies. The schematics of Figure 7 and 8 may also be useful for performing additional embodiments of the invention, e.g., other method or system embodiments.

[0075] Systems, kits and methods of the present invention are believed to impart a number of advantages in the art. In particular, they are believed to improve the efficiency of combustion systems, for example, by increasing heat exchange efficiency by reducing at least one of ash formation and corrosion. Embodiments may also be used to catalyze combustion. In addition, some embodiments can reduce the number of treatment location sites needed to treat the various problems mentioned.
Systems, kits and methods can also be used to reduce FCT chemical use. Systems, kits and methods may also provide additional advantages. For example, they are readily portable and allow for rapid testing and easy adjustment for tuning to create the desired air flow and optional chemical injection. Kits of the invention are useful because, inter alia, they allow for easy transport and storage of systems as described herein.

[0076] Although ash accumulation, corrosion, and combustion efficiency may vary from combustion system to combustion system, embodiments of the invention can readily be practiced by one of ordinary skill in the art using the teachings contained herein. By way of example, one could: (1) determine the location of problematic ash accumulation or corrosion on an ISCS; (2) assess the location of available ports or locations for creating ports on the combustion system that could receive the air flow and likely have a positive impact (e.g., make more oxidizing) on the atmosphere around the ash accumulation or corrosion when the air is transferred through the port at a specific volumetric flow rate and velocity, e.g., any of the flow rates or velocities described above; (3) perform-a computational fluid dynamics (CFD) model of the combustion system to confirm that this has the desired effect on the atmosphere around the ash accumulation, e.g., using FLUENT software available from Fluent, Inc. of Lebanon, NH;
(4) repeats steps 1-3 as necessary to determine the optimum design requirements; and (5) specify the required air movers(s), air conveying duct system(s), and application device(s) to achieve the requirements of the design. A similar design can be coupled with the optional application of at least one FCT chemical as necessary. A similar design can also be used to practice embodiments for catalyzing combustion.

[0077] The table below illustrates exemplary combustion system operating conditions. Example 1 is a baseline case utilizing traditional slag reduction control technology. Example 2 is similar to the baseline case with the addition of an over-fired air (OFA) system for reducing NOx emissions. Example 3 is a hypothetical illustration according to one embodiment of the invention. Example 4 is another hypothetical illustration according to one embodiment of the invention.

Ex.1 Ex.2 Ex.3 Ex.4 Baseline Over-Fired Ex. Ex.
Unit Air Embodiment Embodiment MW
System load gross 122 122 122 122 Net load MW net 109 109 109 109 MM Btu/
System firing rate hr 1226 1226 1226 1226 System excess 02 %-wet 2.6 2.6 2.6 2.6 System excess Air % 14.9 14.9 14.9 14.9 System coal flow kpph 187 187 187 187 Primary air flow rate through bed grid kpph 607 476 476 476 Primary air flow rate through 14 ports kpph 313 182 182 182 Primary air temperature Deg F 434 434 434 434 Secondary air flow rate through 18 injection devices for over-fired air NOX
emissions reduction kpph 0 262 262 262 Secondary air through 4 start-up burners kpph 104 104 104 104 Secondary air through 4 coal feeders kpph 65 65 65 65 EMBODIMENT INJECTION
VOLUMETRIC FLOW through 4 injectors (cumulative) ACFM NA NA 1200 1200 EMBODIMENT INJECTION
VELOCITY through 4 injectors (average) m/s NA NA 100 100 EMBODIMENT INJECTION

Air flow rate through FCT
Chemical injection kpph 11.5 11.5 11.5 11.5 Secondary air temperature Deg F 401 401 401 401 FCT Chemical injection rate pph 40 40 30 35 [0078] Numerous characteristics and advantages have been set forth in the foregoing description, together with details of structure and function. The disclosure, however, is illustrative only and changes may be made in detail, especially in matters of shape, size, and arrangement of parts, within the principle of the invention, to the full extent indicated by the broad general meaning of the terms in which the general claims are expressed.

[0079] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein, and every number between the end points. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. Ito 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10, as well as all ranges beginning and ending within the end points, e.g. 2 to 9, 3 to 8, 3 to 9, 4 to 7, and finally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 contained within the range.
Additionally, any reference referred to as being "incorporated herein" is to be understood as being incorporated in its entirety.

[0080] It is further noted that, as used in this specification, the singular forms "a," "an," and "the" include plural referents unless expressly and unequivocally limited to one referent. Nor or any embodiments intended to be mutually exclusive, unless expressly and unequivocally indicated as so.

Claims (31)

1. A method of operating a combustion system, said method comprising:
providing a combustion system that emits a flue gas; and applying air to an internal surface of said combustion system (ISCS), wherein said application of air to said ISCS occurs by transferring air from one or more entry points of said combustion system to said ISCS through at least one apparatus, which is capable of transferring air from one point in the combustion system to another point in the combustion system, wherein said application of air to said ISCS
comprises applying air at a velocity chosen from about 50 m/s to about 300 m/s, and a volumetric flow chosen from about 50 ACFM to about 4000 ACFM, and wherein said amount of said air effectuates a reduction of at least one combustion problem.

2. The method of Claim 1, wherein said applied air oxidizes CO in said flue gas contacting said ISCS, thereby creating a localized area of lower CO
concentration.

3. The method of Claim 2, wherein said localized area of lower CO
concentration has a concentration chosen from at least one of less than about 5000 ppm, less than about 4000 ppm, less than about 3000 ppm, less than about 2000 ppm, less than about ppm CO, less than about 500 ppm, less than about 400 ppm, less than about 300 ppm, less than about 200 ppm, and less than about 100 ppm.

4. The method of Claim 1, wherein said applied air raises the oxygen concentration of said flue gas contacting said ISCS to about 2% or greater.

5. The method of Claim 1, wherein said applied air has an oxygen concentration sufficient to raise the oxygen concentration of said flue gas contacting said ISCS to about 2%
or greater, and lower the CO concentration of said flue gas contacting said ISCS to less than about 1000 ppm.

6. The method of Claim 1, wherein said applied air raises an ash-fusion temperature of ash in said flue gas contacting said ISCS.

7. The method of Claim 1, further including applying an effective amount of at least one fireside chemical treatment (FCT) chemical into said combustion system.

8. The method of Claim 7, wherein said at least one FCT chemical is chosen from one or more of chemicals capable of at least one of the following of reducing ash accumulation, reducing corrosion, and catalyzing combustion.

9. The method of Claim 7, wherein said application of said at least one FCT
chemical includes feeding said FCT chemical into said applied air.

10. The method of Claim 9, wherein said application of air creates a localized area of lower CO concentration within said flue gas contacting said ISCS, and wherein said at least one FCT chemical is delivered to said localized area of lower CO

concentration.

11. The method of Claim 1, wherein said ISCS is in an area chosen from an upstream radiant zone, a burner zone, a downstream radiant zone, and a convection zone.

12. The method of Claim 1, wherein said ISCS is in an area having a sub-stoichiometric air-fuel ratio (AFR).

13. The method of Claim 12, wherein said sub-stoichiometric area is in an area chosen from at least one of an upstream radiant zone, a burner zone, a downstream radiant zone, and a convection zone.

14. The method of Claim 1, wherein said at least one application apparatus is positioned to apply through at least one wall chosen from a wall in an upstream radiant zone, a wall in a burner zone, a wall in a downstream radiant zone, and a wall in a convection zone.

15. The method of Claim 1, wherein said velocity is chosen from about 50 m/s to about 150 m/s.

16. The method of Claim 1, wherein said volumetric flow is chosen from at least one of about 100 to about 3500 ACFM, about 150 to about 3500 ACFM, about 200 to about 3000 ACFM about 250 to about 2500 ACFM, about 300 to about 2500 ACFM, about 350 to about 2500 ACFM, about 400 to about 2500 ACFM, about 450 to about 2500 ACFM, about 500 to about 2500 ACFM, about 550 to about 2500 ACFM, about 600 to about 2500 ACFM, about 650 to about 2500 ACFM, about 700 to about 2500 ACFM, about 750 to about 2500 ACFM, about 800 to about 2500 ACFM, about 950 to about 2500 ACFM, and about 1000 to about 2000 ACFM.

17. The method of Claim 1, wherein said volumetric flow is chosen from about 1000 to about 2000 ACFM.

18. The method of Claim 1, further including applying at least one reducing agent into the combustion system in an amount sufficient to lower NOx emissions;
optionally, wherein said reducing agent is sprayed into an over-fired air (OFA) stream in said combustion system.

19. The method of Claim 18, wherein said at least one reducing agent is chosen from at least one of urea, methylol urea, methylol urea-urea condensation product, dimethylol urea, urea pills, methyl urea, dimethyl urea, urea analogs, urea hydrolysis products, ammonia, ammonia salts, ammonium carbamate, ammonium carbonate, ammonium bicarbonate, ammonium formate, ammonium oxalate, hexamethylenetetramine, ammonium salts of organic acids, 5-membered heterocyclic hydrocarbons having at least one cyclic nitrogen, 6-membered heterocyclic hydrocarbons having at least one cyclic nitrogen, hydroxy amino hydrocarbons, cyanuric acid, amino acids, proteins, monoethanolamine, guanidine, guanidine carbonate, biguanidine, guanylurea sulfate, melamine, dicyandiamide, calcium cyanamide, biuret, and 1,1'-azobisformamide.

20. The method of Claim 1, further including applying OFA into the combustion system, wherein said OFA includes an amount of air sufficient to bring an air-fuel ratio (AFR) in said combustion system to at least stoichiometric.

21. The method of Claim 20, wherein said OFA is applied at about 1 to about 40% excess combustion air.

22. The method of Claim 20, wherein said applying air into said system through at least one application apparatus to target said ISCS includes applying in the radiant zone at a location upstream from where said OFA is applied.

23. The method of Claim 20, wherein said applying air into said system through at least one application apparatus to target said ISCS includes applying in the radiant zone at a location downstream from where said OFA is applied.

24. The method of Claim 1, wherein said step of applying air into said system through at least one application apparatus to target said ISCS is not OFA.

25. The method of Claim 1, further including identifying a portion of said ISCS
exhibiting at least one of said problems and pointing said at least one application apparatus in the direction of said identified portion of said ISCS.

26. The method of Claim 1, further including injecting a liquid through said at least one application apparatus.

27. The method of Claim 1, wherein said combustion problem is chosen from at least one of ash accumulation, corrosion and incomplete combustion.

28. A combustion system that emits a flue gas, said combustion system comprising:
an internal surface (ISCS) located in at least one of a radiant zone and a convection zone;
an entry point for establishing communication with said ISCS;
at least one treatment system comprising an apparatus configured to transfer air from one point in the combustion system to another point in the combustion system, and an air mover connected to said apparatus, wherein said air mover is in communication with an air supply and is configured to generate an air flow velocity of about 50 m/s to about 300 m/s, and a volumetric flow of about 50 ACFM to about 4000 ACFM, wherein said apparatus is positioned such that application of air through said apparatus increases an oxygen concentration in said flue gas contacting said ISCS
and reduces the occurrence of at least one combustion problem chosen from ash accumulation, corrosion, and incomplete combustion.

29. The combustion system of Claim 28, further including an FCT delivery passage configured to interface with said apparatus and apply an FCT chemical into said applied air, and an FCT chemical supply in communication with said FCT delivery passage.

30. A treatment system for use with a combustion system that emits a flue gas, said combustion system having an internal surface (ISCS) located in at least one of a radiant zone and a convection zone, and an entry point for establishing communication with said ISCS, said treatment system comprising:
an apparatus configured to transfer air from one point in the combustion system to another point in the combustion system, and an air mover connected to said apparatus, wherein said air mover is in communication with an air supply and is configured to generate an air flow velocity of about 50 m/s to about 300 m/s, and a volumetric flow of about 50 ACFM to about 4000 ACFM, whereby application of air through said apparatus increases an oxygen concentration in flue gas contacting said ISCS.

31. The treatment system of Claim 30, further including an FCT delivery passage configured to interface with said apparatus and apply an FCT chemical into said applied air, and an FCT chemical supply in communication with said FCT delivery passage.