KR20050046606A - IMPROVED FUEL STAGING PROCESS FOR LOW NOx OPERATIONS - Google Patents

Abstract

A method for diluting a fuel to reduce NOx uses a fuel dilution device, which includes: a first conduit having an inlet and an outlet, the first conduit adapted to transmit a stream of a fuel entering the inlet and exiting the outlet at a first thermodynamic state and a first fuel index; and a second conduit having an intake and an outtake, the second conduit adapted to transmit a stream of a fluid entering the intake and exiting the outtake at a second/different thermodynamic state and a second fuel index different from the first fuel index by at least about 0.1, whereby a potential for mixing exists between the two streams exiting the outlet and the outtake, and at least some of the fuel mixes with at least some of the fluid near the outlet and the outtake, thereby generating a diluted fuel stream having an intermediate fuel index. <IMAGE>

Description

IMPROVED FUEL STAGING PROCESS FOR LOW NOx OPERATIONS}

The present invention relates to fuel staging methods and systems for reducing nitrogen oxide (NO _x ) emissions, and more particularly to such methods and systems using fuel dilution tips in low NO _x burners.

One of the challenges facing the chemical process industry (CPI) is the combustion of waste fuels due to economic reasons and at the same time the need for low NO _x and CO emissions. Waste fuels contain a mixture of gases with a high C / H ratio, are burned with a very luminous flame due to carbon oxidation, and also produce soot particles and carbon in accordance with the combustion process. Typical refinery fuel compositions include various amounts of fuel and inert gases (eg, C ₁ , C ₂ , C ₃ ,... C _n , olefins, hydrogen, nitrogen, CO ₂ , water vapor). If carbon or soot particles are formed on the fuel tip, the soot structure generally grows under the desired pressure and temperature conditions present near the tip outlet. This results in fuel blow off, fuel blow deflection, overheating of tip and furnace parts such as process tubes and refinery walls, and potential shutdown of burner and furnace operation. Shutdowns of the furnace can lead to significant financial penalties, including the burden of downtime downtime.

If a fuel tip suffers from the following, dirty refined fuels consisting of higher carbon and containing gases such as acetylene, ethane, propane, butane and olefins (eg ethylene and propylene) generally produce soot particles:

Inadequate mixing in the furnace (depending on the number of ejections, ejection geometry, injection angle and injection speed) (generally classified as burner design issues)

* Lack of combustion air or oxidant near fuel jets (generally classified as burner flow composition problems)

Inadequate cooling of fuel tips (exposure to furnace emissions on a regular basis) (generally classified as fuel tip configuration and burner design issues)

* Disturbance of fuel flow (upward fuel equipment reliability) (commonly classified as a process problem)

* Low firing operation (low fuel flow rate due to process down) (generally classified as a process problem)

* Variation of carbon-containing species in refinery fuel compositions (generally classified as process requirements).

Burner or tip design affects tip overheating, soot production, tip plugging and frequent maintenance of burner equipment. These problems are compromised by changing process conditions such as low end of process down and / or disruption of fuel flow that affect the required cooling required for the fuel tip. Changes in process conditions and fuel composition are common in refinery operation.

Another challenge faced by the CPI is the need for low NO _x emissions in compliance with emission regulations. Due to NO _x regulations (under the Clean Air Act of 1990), there are many areas in the United States that require less than 10 ppm NO _x emissions from process heaters, boilers, gas turbines, and other installed combustion equipment. The most common or BACT (Best Available Control Technology) solution at CPI is to reduce NO _x contained in the exhaust stream ( _by converting NO _x to N2) using ammonia injection into the large catalytic reactor. By using SCR (Selective Catalytic Reactor) for the post-purification of the exhaust gas. This method is very capital intensive and requires a significant amount of power for ammonia, hot air and ID fan operation.

Most refineries tend to avoid SCR installations and instead use low NO _x burners to meet their NO _x requirements. However, low NO _x burners do not always produce less than 10 ppm NO _x in various process heating applications such as steam methane reformers (SMR), crude heaters, ethylene crackers or boilers. For this reason, the use of low NO _x burners has not been certified by regulatory agencies such as BACT. In other words, SCR is currently the only commercially viable solution that meets stringent NO _x levels in ozone attainment areas where ozone concentrations at ground levels exceed legal limits.

Typically, operators at CPI use an optimal blend of clean natural gas or natural gas and dirty refinery fuel, reducing maintenance penalty. However, due to the lack of natural gas and the high cost of fuel, it is not always possible to use clean natural gas for combustion in the process industry. Refineries that can burn waste fuels typically have higher productivity and relatively desirable competition compared to other refineries that can potentially use waste fuels.

With regard to NO _x reduction, conventional NO _x control methods include the use of low levels of fuel staging and low NO _x burners equipped to dilute the air / fuel with exhaust gas recirculation (FGR). By injecting non-reactive or inert species into the fuel / oxidant mixture, the average flame temperature is reduced, thereby reducing NO _x emissions. However, this method requires additional piping and energy costs associated with the transfer of exhaust gas. In addition, energy penalty exists because heating of the gas from room temperature to process temperature is required. In addition, the technical data published in the literature do not indicate that NO _x performance below 10 ppm can be obtained with this method.

Various apparatus and methods using fuel staging have been developed to reduce NO _x emissions.

US patent application 2003/0148236 (Joshi et al.) Discloses an ultra low NO _x burner using a staging fuel nozzle. This burner has eight fuel staging lances located around the main burner body. The center of the burner is used to supply 100% of the combustion air, with a very small amount of fuel (~ 10%) injected for total flame safety. The remainder of the fuel (~ 90%) is injected using multiple fuel staging lances. The fuel staging lance has a special fuel nozzle tip with two circular holes. As shown in Figures 1A-1C, these lances are accompanied by a slow mixing of combustion air and droplets of furnace gas due to relatively high blow rates (500 to 1000 feet / sec or 5 to 15 psig fuel supply pressure depending on firing rate). It has an axis divergence angle and a radius divergence angle for.

US Pat. No. 6,383,462 (Lang) discloses a method and apparatus having a mixing chamber outside of a "burner and furnace" for mixing furnace-derived exhaust gas with fuel gas, as shown in FIG. Converging divergent venturi mixers are used to further dilute the fuel gas with additional flow stimulation gas. The resulting mixture (exhaust gas and diluted fuel) is then mixed with combustion air and sent to a burner burning in the furnace. Depending on the exhaust gas dilution value, NO _x emission reductions of 26 ppm to 14 ppm can be obtained. This instrument and method does not reduce NO _x emissions below 10 ppm, and the results are not comparable to those typically obtained with SCR technology.

U. S. Patent No. 6,481, 209 to Johnson et al. Discloses a fuel staging system suitable for gas turbine engines. Efficient combustion with air is achieved by dividing the fuel injection into two stages: low NO _x and CO emissions are obtained: 1) an injector installed in the swirl mixer and 2) an injector installed in the trapped vortex site of the combustor. However, this injection design is not suitable for large furnaces where trapped vortex sites are impossible due to furnace and unloading geometry.

US Pat. No. 6,558,154 (Eroglu et al.) Discloses a controlled base fuel staging strategy for aero engines in which two separate plant fuel staging nozzles are used. Adjustment of the emission and wave sensors is installed downstream of each staging zone. These sensors measure the amount of combustion products derived from each staging zone, and the control unit varies the relative amount of fuel injected into each zone according to operating and environmental conditions.

U. S. Patent No. 5,601, 424 to Bernstein et al. Discloses a method of reducing NO _x using atomizing steam injection control. The NO _x value is lowered by adding burner flame granulation steam which can be used for fuel oil granulation. For a 30% NO _x reduction, about 0.5 lb steam / lb fuel flow is required. Large amounts of steam are required to reduce the flame temperature and achieve the required NO _x reduction. In addition, if a large amount of steam is used for flame quenching, there is a possibility of flame instability and sputtering, therefore, there is an upward limitation of steam injection based on flame stability.

The gas turbine industry also uses similar steam injection techniques for NO _x regulation. However, due to insufficient steam injection schemes, many economic penalties are paid for reducing NO _x emissions. Steam consumption is very large, the technique is insufficient relative to the NO _x control, and is not high cost efficiency.

It would be desirable to have a cost effective and retrofitted apparatus and method for reducing NO _x emissions, which provides the ability to burn refinery waste gas without excessive NO _x emissions.

Due to problems such as plugging of the burner tip and overheating of the process tube, it is also desirable to have an apparatus and method for reducing equipment maintenance, which will provide additional benefits of improved fuel efficiency and furnace productivity.

It would also be desirable to have a device and method that enables current low NO _x burners consistent with SCR numerical NO _x performance and allows smelters to comply with NO _x regulations without the use of capital intensive SCR technology.

Devices and methods that comply with NO _x regulations by allowing the process industry to consume cheaper waste fuels without simultaneously penalizing maintenance issues such as tip plugging, equipment overheating, process interruptions, etc. and simultaneously releasing NO _x below 10 ppm It is also preferred to have.

It is also desirable to have a fuel combustion device and method that overcomes several problems and drawbacks of the prior art to provide better performance than the prior art and also to provide better and more advantageous results.

Summary of the Invention

The present invention is a fuel dilution method and system for reducing nitric oxide emissions through fuel staging. The present invention also includes a fuel dilution device that can be used in the method or system.

There are multiple steps in a first embodiment of the fuel dilution method that reduces nitrogen oxide emissions through fuel staging. The first step is to provide a fuel dilution device comprising a first conduit and a second conduit, the first conduit having an inlet and an outlet remote from the inlet, the inlet at the first thermodynamic state and the first fuel index. Adapted to transfer the flow of fuel into and out of the outlet, and the second conduit has a blow-in and a blow-out away from the blow-in, and a flow of fluid entering and exiting the blow-in at the second thermodynamic state and the second fuel index. And the second fuel index is at least about 0.1 different from the first fuel index, and the second thermodynamic state is different from the first thermodynamic state, whereby the fuel flow out of the outlet of the first conduit and There is a mixing potential between the flow of fluid exiting the outlet of the second conduit. The second step is to supply the flow of fuel to the inlet of the first conduit, the flow of fuel exiting the outlet of the first conduit at the first thermodynamic state and the first fuel index. The third step is to supply the flow of fluid to the intake of the second conduit, the flow of fluid coming out of the outlet of the second conduit at the second thermodynamic state and the second fuel index, whereby The flow of at least some of the fuel exiting the outlet is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate to both the outlet and the outlet, thereby providing an intermediate between the first fuel index and the second fuel index. Generate at least one diluted fuel flow having a fuel index. The fourth step is to provide an oxidant source. The fifth step is to burn a portion of the oxidant with at least a portion of at least one of the flow of fuel or the flow of fluid or the diluted fuel flow to generate a gas containing a reduced amount of nitrogen oxides, the reduced amount of Nitric oxide is less than the larger amount of nitric oxide produced by burning fuel using means other than a fuel dilution device.

There are several variations of the first embodiment of the invention. In one variation, the fluid is a fuel. In another variation, the fluid is selected from the group consisting of flow, exhaust gas, carbon dioxide, nitrogen, argon, helium, xenon, krypton, other inert fluids, and mixtures or combinations thereof.

In another variation of the first embodiment of the method, the first conduit is adjacent to the second conduit. In another variation, at least a substantial portion of the second conduit is disposed in the first conduit. In another variation, the second conduit has an equivalent diameter (D _c ) and the outlet of the second conduit is located at a distance in the range of about 2D _c to about 20D _c behind the outlet of the first conduit.

The second embodiment for a fuel dilution method of reducing nitric oxide emissions through fuel staging is similar to the first embodiment but includes two additional steps. The first additional step is to provide a swirler disposed in the second conduit. The second additional step is to transmit at least some of the flow of fluid through the swirler such that at least some of the fluid is swirled out of the second conduit.

The third embodiment of the method is similar to the first embodiment but includes two additional steps. The first additional step is to provide a zipper nozzle in fluid communication with the outlet of the first conduit. The second additional step is to transmit at least some of the diluted fuel flow through the zipper nozzle.

A fourth embodiment of the method is similar to the first embodiment, but by placing a fuel dilution device in fluid communication with the furnace containing a large amount of furnace gas, at least some of the large amount of furnace gas is combined with at least some of the diluted fuel flow. The mixing step is included as an additional step.

Another embodiment of a fuel dilution method of reducing nitric oxide emissions through fuel staging includes multiple steps. The first step is to provide a fuel dilution device comprising a first conduit and a second conduit, the first conduit having an inlet and an outlet remote from the inlet, the first pressure, the first speed and the first fuel Adapted to transmit the flow of fuel entering and exiting the inlet at the index, the second conduit has a blow-in and a discharge away from the blow-in, and enters the blow-in at the second pressure, the second speed and the second fuel index Adapted to transmit a flow of fluid exiting the outlet, the second fuel index being at least about 0.1 different from the first fuel index, at least one of the second pressure and the second speed being at least one of the first pressure and the first speed And one, whereby there is a mixing potential between the flow of fuel out of the outlet of the first conduit and the flow of fluid out of the outlet of the second conduit. The second step is to supply a flow of fuel to the inlet of the first conduit, wherein the flow of fuel exits the outlet of the first conduit at the first pressure, the first speed and the first fuel index. The third step is to supply the flow of fluid to the intake of the second conduit, wherein the flow of fluid exits the outlet of the second conduit at the second pressure, the second velocity and the second fuel index. Thereby, the flow of at least some of the fuel exiting the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, thereby providing a first fuel index and Generating at least one diluted fuel flow having an intermediate fuel index between the two fuel indexes. The fourth step is to provide an oxidant source. The fifth step is to burn a portion of the oxidant with at least a portion of at least one of the flow of fuel or the flow of fluid or the diluted fuel flow to generate a gas containing a reduced amount of nitrogen oxides, the reduced amount of Nitric oxide is a step that is less than the larger amount of nitric oxide produced by burning fuel using means other than a fuel dilution device.

There are multiple components in a first embodiment of a fuel dilution device for fuel dilution that reduces nitrogen oxide emissions through fuel staging. The first component is a first conduit, the first conduit having an inlet and an outlet away from the inlet, adapted to transmit a flow of fuel entering and exiting the inlet at the first thermodynamic state and the first fuel index. have. The second component is a second conduit, the second conduit having an intake and an outlet away from the intake, adapted to transmit a flow of fluid entering and exiting the intake at the second thermodynamic state and the second fuel index. Wherein the second fuel index is at least about 0.1 different from the first fuel index, and the second thermodynamic state is different from the first thermodynamic state, whereby the fuel flow exiting the outlet of the first conduit and the discharge of the second conduit There is a mixing potential between the flows of negative fluid, whereby at least some of the fuel flow exiting the outlet of the first conduit is at least some fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet. And at least one diluted fuel flow having an intermediate fuel index between the first fuel index and the second fuel index. The third component is an oxidant source. The fourth component is a combustion means, the combustion means combusting a portion of the oxidant with at least a portion of at least one of the flow of fuel or the flow of fluid or the diluted fuel flow to generate a gas containing a reduced amount of nitrogen oxides and The reduced amount of nitric oxide is less than the higher amount of nitric oxide produced by burning the fuel using means other than a fuel dilution device.

There are several variations of the first embodiment of the fuel dilution apparatus. In one variation, the fluid is a fuel. In another variation, the fluid is selected from the group consisting of flow, exhaust gas, carbon dioxide, nitrogen, argon, helium, xenon, krypton, other inert fluids, and mixtures or combinations thereof.

In another variation, the first conduit is adjacent to the second conduit. In another variation, at least a substantial portion of the second conduit is disposed in the first conduit. In another variation, the second conduit has an equivalent diameter (D _c ) and the outlet of the second conduit is located at a distance in the range of about (2 × D _c ) to about (20 × D _c ) behind the outlet of the first conduit do.

In another variation of the first embodiment, the fuel dilution device is in fluid communication with a furnace containing a large amount of furnace gas such that at least some of the large amount of furnace gas is mixed with at least some of the diluted fuel stream.

The second embodiment of the fuel dilution apparatus is similar to the first embodiment but includes a swirler disposed in the second conduit. A third embodiment of the fuel dilution device is similar to the first embodiment, but includes a zipper nozzle in fluid communication with the outlet of the first conduit.

Another embodiment of a fuel dilution device for fuel dilution that reduces nitric oxide emissions through fuel staging includes multiple components. The first component is a first conduit, the first conduit having an inlet and an outlet remote from the inlet, and transmitting a flow of fuel entering and exiting the inlet at the first pressure, the first speed and the first fuel index. Has been modified to The second component is a second conduit, the second conduit having an intake and an outlet away from the intake, which transmits a flow of fluid entering and exiting the intake at the second pressure, the second speed and the second fuel index. Wherein the second fuel index is at least about 0.1 different from the first fuel index, and at least one of the second pressure and the second speed is different from at least one of the first pressure and the first speed, whereby There is a mixing potential between the flow of fuel exiting the outlet of the first conduit and the flow of fluid exiting the outlet of the second conduit, whereby at least some of the flow of fuel exiting the outlet of the first conduit is directed to both the outlet and the outlet. At least one fluid having an intermediate fuel index between the first fuel index and the second fuel index, mixed with the flow of at least some fluid exiting the outlet of the second conduit at a location proximate to Generate a fuel stream. The third component is an oxidant source. The fourth component is a combustion means, the combustion means combusting a portion of the oxidant with at least a portion of at least one of the flow of fuel or the flow of fluid or the diluted fuel flow to generate a gas containing a reduced amount of nitrogen oxides and The reduced amount of nitric oxide is less than the higher amount of nitric oxide produced by burning the fuel using means other than a fuel dilution device.

Another aspect of the invention is a system for fuel dilution that reduces nitric oxide emissions through fuel staging. The system includes multiple components. The first component is a fuel dilution device comprising a first conduit and a second conduit, the first conduit having an inlet and an outlet remote from the inlet, and entering and exiting the inlet at the first thermodynamic state and the first fuel index. Adapted to transmit the flow of fuel to the outlet, and the second conduit has a blow-in and a drain away from the blow-in, and for transferring the flow of fluid entering and entering the blow-out at the second thermodynamic state and the second fuel index. And wherein the second fuel index is at least about 0.1 different from the first fuel index and the second thermodynamic state is different from the first thermodynamic state, whereby the fuel flow and the second conduit exiting the outlet of the first conduit There is a mixing potential between the streams of fluid coming out of the outlet. The second component is a means for supplying the flow of fuel, the means for supplying the flow of fuel supplying the flow of fuel to the inlet of the first conduit, the flow of fuel being the first in the first thermodynamic state and the first fuel index. Exit the conduit outlet. The third component is a means for supplying the flow of fluid, the means for supplying the flow of fluid supplying the flow of fluid to the outlet of the second conduit, the flow of fluid being second in the second thermodynamic state and the second fuel index. Coming into the outlet of the conduit, whereby at least a portion of the fuel flow out of the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, Generate at least one diluted fuel flow having an intermediate fuel index between the first fuel index and the second fuel index. The fourth component is an oxidant source. The fifth component is a combustion means, the combustion means combusting a portion of the oxidant with at least a portion of at least one of the flow of fuel or the flow of fluid or the diluted fuel flow to generate a gas containing a reduced amount of nitrogen oxides and The reduced amount of nitric oxide is less than the higher amount of nitric oxide produced by burning the fuel using means other than a fuel dilution device.

Another embodiment of a system for fuel dilution that reduces nitric oxide emissions through fuel staging includes multiple components. The first component is a fuel dilution device comprising a first conduit and a second conduit, the first conduit having an inlet and an outlet remote from the inlet, the inlet at the first pressure, the first speed and the first fuel index. Adapted to transfer the flow of fuel into and out of the outlet, the second conduit has an inlet and an outlet away from the inlet, and enters into the outlet at the second pressure, the second speed and the second fuel index Adapted to transmit a flow of fluid, the second fuel index being at least about 0.1 different from the first fuel index, and at least one of the second pressure and the second speed is different from at least one of the first pressure and the first speed Thereby, there is a mixing potential between the flow of fuel exiting the outlet of the first conduit and the flow of fluid exiting the outlet of the second conduit. The second component is a means of supplying the flow of fuel, the means of supplying the flow of fuel supplying the flow of fuel to the inlet of the first conduit, the flow of fuel being the first pressure, the first speed and the first fuel index. Exits the outlet of the first conduit. The third component is a supply means of the flow of fluid, the supply means of the flow of fluid supplying the flow of fluid to the outlet of the second conduit, the flow of fluid being the second pressure, the second velocity and the second fuel index. At the outlet of the second conduit, whereby the flow of at least some of the fuel exiting the outlet of the first conduit is at least a portion of the flow of fluid from the outlet of the second conduit at a location proximate to both the outlet and the outlet. The mixture produces at least one diluted fuel flow having an intermediate fuel index between the first fuel index and the second fuel index. The fourth component is an oxidant source. The fifth component is a combustion means, the combustion means combusting a portion of the oxidant with at least a portion of at least one of the flow of fuel or the flow of fluid or the diluted fuel flow to generate a gas containing a reduced amount of nitrogen oxides and The reduced amount of nitric oxide is less than the higher amount of nitric oxide produced by burning the fuel using means other than a fuel dilution device.

Detailed description of the invention

The present invention relates to various problems encountered in the design of combustion equipment such as burners used in heating reformers, process heaters, boilers, ethylene crackers or other high temperature furnaces. The present invention relates to an improved fuel staging method. In particular, two general approaches to providing rapid dilution and mixing are as follows depending on the process target required:

I. Fuel staging with other fuels (FF): High pressure refinery waste fuels, granulated liquid fuels, etc., are injected in the vicinity of relatively clean low pressure gaseous fuels for clean and maintenance free NO _x operation.

II. Fuel staging with inert gas (FI): High pressure inert fluids such as steam, nitrogen, CO ₂ are injected in the vicinity of the low pressure gas fuel to reduce NO _x .

As used herein, the term "fuel index (FI)" is defined as the sum of the weights of the number of fuel carbon atoms in which the molecule H ₂ is assigned a carbon number of 1.3, where the weight is the mole fraction of the component: FI = ∑C _i x _i / ∑x _i , where C _i and x _i are the number of carbon atoms and the mole fraction of component i, respectively. The fuel indices of fuels and inerts are listed in Table 1. In general, fuels with a high fuel index are more easily broken down through the instant NO _x mechanism to produce more NO _x . H ₂ is a special case in this definition. Although H ₂ does not have any carbon atoms, it is well known that the addition of H ₂ to natural gas increases NO _x emissions. The literature suggests that about 30% higher NO _x emissions occur for pure H ₂ flames compared to methane flames. The increased NO _x emissions into the H ₂ flame are due to the higher flame temperatures through the thermal NO _x mechanism. Since the fuel index is used herein as an indicator for NO _x emissions, a value of 1.3 is assigned to be consistent with the NO _x emission potential of H ₂ .

Fuel Indexes of Selected Fuels and Inerts Fuel or inert Fuel index H ₂ 1.3 H ₂ O 0 CO ₂ 0 CO One N ₂ 0 CH ₄ One C ₃ H ₈ 3 ROG (1) 1.434 PSA Offgas (2) 0.57 Natural Gas (3) 1.08 Natural Gas (4) 1.14

(1) ROG: H ₂ 18%, CH ₄ 44%, C ₂ H ₂ 38%

(2) PSA offgas: H ₂ 30%, CH ₄ 18%, CO ₂ 52%

(3) natural gas: CH ₄ 91%, C ₂ H ₆ 4%, C ₃ H ₈ 3%, N ₂ 1%, CO ₂ 1%

(4) natural gas: CH ₄ 84%, C ₂ H ₆ 12%, C ₃ H ₈ 2%, N ₂ 2%

As described herein, the term "thermodynamic state" is defined as the state of existence for a substance. This definition is based on the generally known concept of thermodynamics, but extends to include speed, concentration, composition, volume fraction, flow rate, electrical potential, etc. to fully characterize flow as well as normal temperature and pressure. This definition is used to define the exact mixing of the difference of thermodynamic states between two flows.

Two approaches are described in detail below.

I. Fuel staging with other fuels (F-F):

This approach can be used to burn refined waste fuels containing a blend of hydrogen and high C / H fuels (ethane, propane, butane, olefins, etc.) with a second, relatively clean low pressure fuel gas at high feed pressures. have. Maintenance issues arise from refinery waste fuels due to pyrolysis of high C / H fuel and subsequent soot build-up at the burner fuel tip. In addition, the combustion of these fuels results in higher emissions than normal NO _x emissions.

To improve the combustion of high C / H refinery waste fuels, dirty fuels are diluted with a relatively clean (secondary) fuel stream (eg hydrogen, syngas, natural gas or low BTU fuel blends). In one embodiment shown in FIG. 3, the high pressure refinery fuel gas (containing a high C / H non-fuel gas) is injected through a central lance 32 and is a relatively clean low pressure fuel gas such as natural gas, syngas, process gas, PSA offgas (fuel gas recycled after removing product hydrogen from the PSA adsorption bed) and the like are injected through annular portion 33 between central lance 32 and external lance 34. As shown in FIG. 3, exit 36 of the central lance is located at a preferred distance from exit 38 of the outer lance. This distance is preferably 2 to 20 times the equivalent diameter D _c of the central lance. Depending on the fuel split between the high pressure refinery fuel gas and the cleaner low pressure fuel gas, this distance is preferably about 1/16 "to 1".

Those skilled in the art will understand that reference to "high pressure" in Figures 3-7 and 9 may refer to "high speed" or "high pressure or high speed." Similarly, reference to "low pressure" in these figures may refer to "low speed" or "low pressure or low speed".

The apparatus shown in FIG. 3 allows dirty high pressure refinery fuel gas to mix with clean low pressure fuel gas due to turbulent jet interactions. The speed of the high pressure refinery fuel gas through the central lance 32 is preferably about 900 to 1400 feet / second (preferably sonic or choked speed). The speed of the low pressure fuel gas through the annular portion 33 between the center lance 32 and the outer lance 34 is preferably about 100 to 900 feet / second depending on the available supply pressure of the low pressure gas. The high velocity gas flow to exit 36 of the central lance splashes with the slow gas flow approaching exit 38 of the outer lance to provide a "first stage" mixing before the flow exits through the orifice (s) 40. External lance orifice geometries, angles, etc. are designed for optimal "second stage" mixing in the furnace atmosphere. Very large amounts of furnace gas 42 are entrained in droplets for the second stage dilution, resulting in a drop in peak flame temperature and subsequent reduction of NO _x emissions.

4 shows the apparatus required for staging liquid fuel (FF). In this embodiment, high pressure (and high C / H ratio) liquid fuels (e.g., fuel oil, diesel, bunker C, waste liquid fuel, etc.) use low pressure fuel gas prior to being injected into the furnace atmosphere for further dilution. Diluted. For example, heavy fuel oil is granulated with a granulating fluid, such as steam, and diluted with low pressure fuel gas for smoke-free (clean) combustion into the furnace. This embodiment also reduces NO _x emissions due to the low peak flame temperature.

In FIG. 4, X is the distance from the exit of the center lance 32 to the rear face of the exit of the outer lance 34. D _c is the flow area-equivalent diameter of the central lance, ie the total flow area of the outlet of the central lance is equal to the circumference of the diameter D _c . D _e is the flow area-equivalent diameter of the outer lance, ie the total flow area of the outlet of this lance is equal to the circumference of the diameter D _e .

Two other embodiments of (F-F) staging are shown in Figures 5A and 5B. In FIG. 5A, a strong jet-wet jet interaction occurs between the high pressure refinery fuel gas and the low pressure fuel gas. The high pressure refinery fuel gas is injected into the high pressure lance 52 at a high speed (about 900 to 1400 feet / second), in the preferred direction, and the low pressure fuel gas is injected into the low pressure lance 54 and entrained by the high pressure refinery fuel gas.

In FIG. 5B, the high pressure refinery fuel gas is swirled at the center lance 32 using the fuel swirler 56, and the low pressure fuel gas is splashed at the collapse site (center area) of the high speed swirl. This allows for a good mixing of high pressure refinery fuel gas and low pressure fuel gas (data not shown) before they exit the outer lance 34 and into the furnace where additional dilution with the furnace gas 42 takes place. This approach is advantageous for applications requiring short flame profiles or smaller combustion spaces.

Applications for (FF) staging are found in steam methane reformer (SMR), which is a common source of natural gas or refinery offgases where high pressure fuel gases are generally classified as trim fuels. 6, the high pressure fuel gas is injected into the center lance 32. The low pressure fuel gas injected into the annular portion 33 between the central lance 32 and the outer lance 34 is typically CO ₂ (-45%), hydrogen (-30%), methane (-15%) and a fuel index of about 0.64. PSA (Pressure Swing Adsorption) offgas containing CO (-10%) or clean vent flow from PSA. PSA offgas is permeated outside the adsorptive bed after the hydrogen product has been separated. High pressure trim fuels contribute between 10% and 30% of the total energy for typical reformers with PSA for hydrogen separation.

A second advantage of this staging application is to improve PSA recovery, particularly by reducing the range of PSA pressure cycles at the low end. For FIG. 7 this is accomplished by creating a low pressure site with an external lance 34. The high velocity center jet 72 shown in FIG. 7 creates a low pressure site around the jet body in which the low moving low pressure fuel gas is splashed by a faster moving center jet. Due to the active droplet entrainment process, the supply pressure for the low pressure fuel gas is lower than the same fuel flow rate.

In one laboratory firing experiment, the feed pressure of low pressure PSA offgas decreased from 2 psig to 1.6 psig (20% decrease). This is accomplished by injecting high pressure fuel gas at 25 psig (1300 feet / second speed). The combustion energy split between the high pressure fuel gas and the low pressure fuel gas was 30:70, respectively.

For further quantification of the (FF) staging process, laboratory test results considered the use of low NO _x burners. This burner has 10 fuel lances distributed around an 18 "diameter circumference. Of the 10 fuel lances, two lances are reserved for the (FF) type staging configuration. This lance is intended to improve manual mixing. And a special fuel tip and multiple diverging slots (zipper tip 74) A schematic of a (FF) fuel staging configuration using a zipper tip 74 is shown in Figure 7. The burner was spared at 644 ° F. at a firing rate of 8 MM Btu / hr. It is carried out using heated air, which is designed to use two types of fuels The details of the two fuels are shown below:

High pressure refinery fuel gases: H ₂ (18%), natural gas (44%) and ethylene (38%). This fuel has a fuel index of 1.43 and accounts for 30% of the total energy supply.

Low pressure fuel gases: CO ₂ (52%), natural gas (18%) and H ₂ (30%). It has a fuel index of 0.57 and accounts for about 70% of the total energy supply.

For the apparatus shown in FIG. 7, the high pressure fuel gas was made from standard tubing having a 3/8 "diameter x 0.035" wall thickness (located centrally in an external lance 34 made of a 3/4 "sch 40 pipe). It is injected into the center lance 32. The zipper tip 74 is attached to the end of the pipe. The zipper tip is 0.51 "equivalent diameter, as shown in Figures 8A-8D, with four vertical slots and one horizontal slot. The divergence angles α1 and α2 of the vertical slots are 18 ° and 6 °, respectively, for the axial zipper nozzle tip geometry as follows: 1) a series of vertical structures at the intersection between adjacent major shapes; 2) downward instability induced by flow; And 3) high levels of molecular (small-scale) mixing between the first fluid (fuel) and the second fluid (no gas). The mixing is also achieved at the shortest axial distance. Low NO _x burner laboratory experiments (including zipper tip) performed with the lance-in-lance configuration of FIG. 7 show rapid axial mixing, high furnace gas droplet entrainment with a divergence angle β of 7 °.

The overall fluid process according to the apparatus of FIG. 7 results in more consistent heat transfer and ultralow (<15 ppmv) NO _x and CO emissions down to the fuel pressure of 2 psig or less. It is also noted that, without the lance-in-lance process, combustion of high pressure and high C / H specific fuels produces a visible soot rich flame. In addition, NO _x emissions are as high as 25 to 30 ppm. This experiment shows that the FF staging process dramatically lowers NO _x emissions. The FI staging process further reduces emissions to inerts.

Visible evidence for improved mixing is observed in laboratory furnaces where lance-in-lance (FF) fuel staging configurations are used for refined fuels composed of butane (C ₄ H ₁₀ ) as high as 50%. Individual flames are observed to mix more rapidly with furnace gases, resulting in extensive and flameless combustion. On the other hand, simple lances with cylindrical nozzle lances are more visible (bluish) and produce relatively longer flames (which represent less furnace gas dilution and mixing) while at the same time relatively higher at a given fuel supply pressure Generates NO _x and CO emission levels.

Table 2 provides the preferred firing range, dimensions, dimensionless ratios and implant angles for the proposed lance-in-lance configurations. Simple round tubing is used for high pressure refinery fuel, while a zipper tip is used for low pressure PSA offgas fuel. Since the reliability of burner performance directly affects the steam methane reformer when steaming, these lances are the critical components of low NO _x burners.

Dimensional Variables for Lance-in-Lance Fuel Staging Tips Low pressure zipper tips High pressure cylindrical tips (H) (W) (R ₀ / R ₁ ) (H / R ₀ ) (α1, α2) (β) L / D _e D _c X / D _c Burner firing force (MM Btu / hr) Slot height (inches) Slot Width (Inches) Slot End Radius to Center Radius Ratio Slot Height to Corner Radius Ratio Axis divergence angle (°) Radius divergence angle (°) Zipper Tip Thickness to Corresponding Diameter Ratio Tube diameter (inches) Rear distance of the zip tip inlet 8 (1 / 32-1) (1 / 4-2) 1.6 (1-3) 3.7 (2-6) 15 (0-30) 7 (0-30) 0.625 (0.05-3) 0.305 (1 / 16-2) 4 (2-20) 5.2 (1 / 32-1) (1 / 4-2) 1.6 (1-3) 3.7 (2-6) 15 (0-30) 7 (0-30) 0.625 (0.05-3) 0.277 (1 / 16-2) 4 (2-10)

The dimension range is valid for several fuels such as natural gas, propane, refinery offgas, low BTU fuel and the like. The nozzle is optimally sized depending on the fuel composition, flow rate (or firing rate) and supply pressure available at the burner inlet. In Table 2, the dimensions, ratios and ranges are estimated at 2 to 10 MM Btu / hour burner firing rates. However, these dimensions and ranges are scaled up for higher firing rate burners (> 10 MM Btu / hr) using standard engineering practices that maintain similar flow rate ranges.

II. Staging Fuel with Inert Gas (F-I):

Improved fuel staging with high pressure inert gas such as steam (dry or saturated), CO ₂ , exhaust gas, nitrogen or other inert gas is performed with low pressure fuel gas to reduce NO _x emissions. Staging fuels that can be used include natural gas; Low BTU process gas (composed of hydrogen and other refinery fuels); And PSA offgass, including but not limited to. The injection tip configuration is similar to those shown in FIGS. 3-7. The main aim is to further reduce NO _x emissions. Preferred specific examples are shown in FIG. 9.

For FIG. 9, high pressure (30-100 psig) saturated or dry steam is sent through the center lance 32 at a rate of about 900 to 1400 feet / second, and the low pressure fuel gas is annular region 33 between the center lance 32 and the outer lance 34. Is passed through. The high velocity steam jet 92 is entrained with fuel gas to the annular site for the first stage dilution (and mixing). The resulting mixture then exits through the zipper tip 74 at high speed (about 600-1400 feet / second) for a second dilution in the furnace with furnace gas (data not shown). The second stage dilution is very efficient due to the high steam velocity, and the droplet entrainment loop is set up with individual flames formed by the zipper tip. Thanks to the zipper tip geometry and the help of steam, improved fuel dilution is obtained. The peak flame temperature is further reduced and ultra low NO _x emissions are obtained. Table 3 shows the predicted steam consumption for larger steam methane reformer furnaces.

Steam consumption economics using the proposed (F-I) staging method Steam injection rate lb_steam / lb_fuel 0.02 0.05 Firing rate mmbtu / hr LHV 850 850 Fuel heating figures btu / scf, LHV 1000 1000 Fuel cost $ / mmbtu, LHV 6 6 Fuel molecular weight 18 18 Steam Required lb / hr 8060.408 2,0161.02 Energy required to generate 100 psia and 400 ℉ steam in 60 ℉ water btu / scfbtu / lb 57.11203.2 57.11203.2 Steam cost $ / Day $ / year 14050,992 349127,480

As shown in Table 3, due to the only method of fuel staging with an inert gas such as steam, the amount of steam required for fuel dilution is very low. The amount of steam required for (F-I) staging is about 2% to 10% in lbs per lb compared to low pressure fuels. High speed steam is used for two dilution processes: 1) inside the lance tube using steam and low pressure fuel gas, and 2) in the furnace space using the high speed fuel-steam mixture and furnace gas.

Laboratory experiments with an inert gas such as nitrogen show a NO _x reduction of about 30% to about 40%, which is a simple prior art lance configuration (zip or round tip alone without lance-in-lance device) and the lance of FIG. 9. It is based on a comparison of the in-lance configurations. For example, using a low NO _x burner, at 5 MM btu / hr firing rate, using ambient combustion air, furnace operation at an average temperature of 1600 ° F., exhaust gas of 2000 ° F., nitrogen flow rate of 10% on a weight basis. Using, the NO _x emission was reduced by about 10 ppm at the center without inert gas (corrected at 3% O ₂ ) and by about 7 ppm at the center when nitrogen gas was present (3 Corrected in% CO ₂ ).

In each of the embodiments described above, the preferred result achieved by the present invention is due to two differences in the flow out of the two conduits. The first difference is the difference in the thermodynamic state of each flow, and the second difference is the difference in the fuel index of each flow. In particular, there must be a difference in the thermodynamic state of the two flows so that there is a mixing potential between the two flows coming out of the two conduits, at least 0.1 difference between the fuel indices of the two flows, and preferably at least 0.2 The difference must be present for a significant NO _x reduction.

In the embodiments shown in the figures and described above, the difference between the thermodynamic states of the two flows is expressed as a pressure potential (ie, "high pressure" fluid in one conduit and "low pressure" fluid in another conduit). However, one of ordinary skill in the art will appreciate that differences in thermodynamic states can also be represented by differences in speed, temperature, concentration, composition, volume fraction, flow rate, electron potential, and the like, and their consequences.

Accordingly, the present invention includes many other embodiments and variations thereof, which are not shown in the drawings and are not described in the detailed description of the invention. These embodiments are within the scope of modifications, but the appended claims and equivalents thereof.

Those skilled in the art will understand that the embodiments and variations shown in the drawings and described in the detailed description of the invention are not intended to represent all possible devices of the invention and other devices are possible. Accordingly, all such other devices are encompassed by the present invention and are within the scope of the present invention. For example, in each of the embodiments shown in FIGS. 3-7 and 9, the device of low pressure and high pressure flow may be reversed (ie, the low pressure lance may be an internal lance and the high pressure lance may be an external lance).

In addition to reduced NO _x emissions, the present invention has the following advantages and advantages:

The proposed fuel staging method enables active tip cooling due to (F-F) staging or (F-I) staging. For fuel tips having a relatively large tip exit area, the nozzle tip is actively cooled by venting a high velocity fuel gas or inert stream. This is an important improvement over conventional circular nozzles.

Due to the relatively low droplet entrainment efficiency and higher operating temperatures, the conventional tips used high C / H fuel to have serious maintenance problems and soot plugging problems. In comparison, the present invention has the following advantages:

Reduction in the tendency to coke while using fuels with higher carbon content

-The ability to use lower flow rates or higher heated numerical fuels

The ability to use cheaper fuel nozzle materials (stainless steel 304 or 310 is suitable)

Thermal grinding is a major problem for many refinery furnaces where the fuel composition contains hydrocarbons in the C ₁ to C ₄ range. Pulverized carbon plugs the burner nozzles and results in overheating of the burner components, resulting in reduced productivity and low thermal efficiency. Thus, having free operation in maintenance (FF or FI staging) is a decisive advantage for refinery operation.

Although the invention has been described and described herein in particular embodiments, the invention is not limited to the details shown. Moreover, various modifications may be made in detail without departing from the spirit of the invention within the spirit and scope of the corresponding claims.

The staging method and system of the present invention uses a fuel dilution tip in a low NO _x burner to reduce nitrogen oxide (NO _x ) emissions.

The invention will now be described by way of example with reference to the accompanying drawings.

1A is a cross-sectional top view of a prior art fuel staging nozzle used for an ultra low NO _x burner.

1B is a cross-sectional elevation view of the prior art fuel staging nozzle of FIG. 1A.

1C is a side view of the prior art fuel staging nozzle of FIG. 1B.

FIG. 2 is a cross sectional elevational view of a prior art mixing chamber for mixing a furnace-derived flue gas and a flow stimulating gas with a fuel gas. FIG.

3 is a schematic view showing a cross-sectional view of one embodiment of the present invention.

4 is a schematic view showing a cross-sectional view of another embodiment of the present invention.

5A is a schematic representation of another embodiment of the present invention using strong jet-soft jet droplet entrainment.

5B is a schematic diagram illustrating a cross-sectional view of another embodiment of the present invention using swirl-induced droplet entrainment.

6 is a schematic view showing a cross-sectional view of another embodiment of the present invention.

7 is a schematic diagram illustrating a cross-sectional view of another embodiment of the present invention including a zipper tip or nozzle.

8A is a schematic diagram illustrating a front view of a zipper tip or nozzle.

FIG. 8B is a schematic diagram illustrating a side view of a zipper tip or nozzle attached to a lance as shown in FIG. 7.

8C is a schematic view showing a top view of a zipper tip or nozzle.

8D is a schematic diagram detailing a portion of the front view of the zipper tip or nozzle of FIG. 8A for dimensioning.

9 is a schematic diagram illustrating a cross-sectional view of another embodiment of the present invention including a zipper tip or nozzle.

Claims (22)

Providing a fuel dilution device comprising a first conduit and a second conduit, The first conduit has an inlet and an outlet remote from the inlet and is adapted to transmit the flow of fuel entering and exiting the inlet at the first thermodynamic state and the first fuel index, The second conduit has an intake and an outlet away from the intake, and is adapted to transmit the flow of fluid entering and exiting the intake at the second thermodynamic state and in the second fuel index, the second fuel index being the first fuel Differing from the index by at least about 0.1, and the second thermodynamic state is different from the first thermodynamic state, whereby a mixed potential exists between the flow of fuel out of the outlet of the first conduit and the flow of fluid out of the outlet of the second conduit To do; Supplying a flow of fuel to the inlet of the first conduit, wherein the flow of fuel exits the outlet of the first conduit at the first thermodynamic state and the first fuel index; Supplying a flow of fluid to the intake of the second conduit, wherein the flow of fluid exits the outlet of the second conduit at the second thermodynamic state and the second fuel index, Thereby, the flow of at least some of the fuel exiting the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, thereby providing a first fuel index and Generating at least one diluted fuel flow having an intermediate fuel index between the two fuel indexes; Providing an oxidant source; And Combusting a portion of the oxidant with at least a portion of at least one of the fuel stream or the fluid stream or the diluted fuel stream to produce a gas containing a reduced amount of nitrogen oxides, the reduced amount of nitrogen oxide being fuel Less than the greater amount of nitric oxide produced by burning fuel using means other than a dilution device A fuel dilution method for reducing nitrogen oxide emissions through fuel staging comprising. The method of claim 1, wherein the fluid is a fuel. The method of claim 1, wherein the fluid is selected from the group consisting of flow, exhaust gas, carbon dioxide, nitrogen, argon, helium, xenon, krypton, other inert fluids, and mixtures or combinations thereof. The method of claim 1, wherein the first conduit is adjacent to the second conduit. The method of claim 1, wherein at least a substantial portion of the second conduit is disposed in the first conduit. The method of claim 1, Providing a swirler disposed in the second conduit; And Transmitting at least some of the flow of fluid through the swirler such that at least some of the fluid is swirled and exits to the second conduit A fuel dilution method comprising the additional step of. The method of claim 1, Providing a zipper nozzle in fluid communication with an outlet of the first conduit; And At least a portion of the diluted fuel flow is transmitted through the zipper nozzle A fuel dilution method comprising the additional step of. The method of claim 1 wherein the second conduit has an equivalent diameter (D _c ) and the outlet of the second conduit is at a distance in the range of about (2 × D _c ) to about (20 × D _c ) behind the outlet of the first conduit. Fuel dilution method. The method of claim 1 further comprising the step of mixing at least a portion of the furnace gas with at least a portion of the diluted fuel stream by placing a fuel dilution device in fluid communication with the furnace containing the furnace gas. A fuel dilution method comprising the step. Providing a fuel dilution device comprising a first conduit and a second conduit, The first conduit has an inlet and an outlet remote from the inlet, and is adapted to transmit a flow of fuel entering and exiting the inlet at the first pressure, the first speed and the first fuel index, The second conduit has an intake and an outlet away from the intake, and is adapted to transmit the flow of fluid entering and exiting the intake at the second pressure, the second speed and the second fuel index, the second fuel index being Differ from the first fuel index by at least about 0.1, and at least one of the second pressure and the second speed is different from at least one of the first pressure and the first speed, whereby the fuel flow exits the outlet of the first conduit and There is a mixing potential between the flow of fluid exiting the outlet of the second conduit; Supplying a flow of fuel to the inlet of the first conduit, the flow of fuel exiting the outlet of the first conduit at a first pressure, a first speed, and a first fuel index; Supplying a flow of fluid to the inlet of the second conduit, wherein the flow of fluid exits the outlet of the second conduit at a second pressure, a second speed, and a second fuel index, Thereby, the flow of at least some of the fuel exiting the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, thereby providing a first fuel index and Generating at least one diluted fuel flow having an intermediate fuel index between the two fuel indexes; Providing an oxidant source; And Combusting a portion of the oxidant with at least a portion of at least one of the fuel stream or the fluid stream or the diluted fuel stream to produce a gas containing a reduced amount of nitrogen oxides, the reduced amount of nitrogen oxide being fuel Less than the greater amount of nitric oxide produced by burning fuel using means other than a dilution device A fuel dilution method for reducing nitrogen oxide emissions through fuel staging comprising. A fuel dilution device for fuel dilution that reduces nitrogen oxide emissions through fuel staging comprising a first conduit, a second conduit, an oxidant source, and combustion means, comprising: The first conduit has an inlet and an outlet remote from the inlet and is adapted to transmit the flow of fuel entering and exiting the inlet at the first thermodynamic state and the first fuel index, The second conduit has an intake and an outlet away from the intake, and is adapted to transmit the flow of fluid entering and exiting the intake at the second thermodynamic state and in the second fuel index, the second fuel index being the first fuel Differing from the index by at least about 0.1, and the second thermodynamic state is different from the first thermodynamic state, whereby a mixed potential exists between the flow of fuel out of the outlet of the first conduit and the flow of fluid out of the outlet of the second conduit and, Thereby, the flow of at least some of the fuel exiting the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, thereby providing a first fuel index and Generate at least one diluted fuel flow having an intermediate fuel index between the two fuel indexes, The combustion means burns some oxidant with at least a portion of at least one of the fuel stream or the fluid stream or the diluted fuel stream to generate a gas containing a reduced amount of nitrogen oxides, the reduced amount of nitrogen oxides being A fuel dilution device that is less than the greater amount of nitric oxide produced by burning fuel using means other than the fuel dilution device. 12. The fuel dilution device of claim 11, wherein the fluid is a fuel. 12. The fuel dilution device of claim 11, wherein the fluid is selected from the group consisting of flow, exhaust gas, carbon dioxide, nitrogen, argon, helium, xenon, krypton, other inert fluids, and mixtures or combinations thereof. The fuel dilution device of claim 11, wherein the first conduit is adjacent to the second conduit. The fuel dilution device of claim 11, wherein at least a substantial portion of the second conduit is disposed in the first conduit. 12. The fuel dilution device of claim 11, further comprising a swirler disposed in the second conduit. 12. The fuel dilution device of claim 11, further comprising a zipper nozzle in fluid communication with the outlet of the first conduit. The method of claim 11, wherein the second conduit has an equivalent diameter (D _c ) and the outlet of the second conduit is at a distance in the range of about (2 × D _c ) to about (20 × D _c ) behind the outlet of the first conduit. The fuel dilution device being located. 12. The fuel dilution device of claim 11, wherein the fuel dilution device is in fluid communication with a furnace containing a large amount of furnace gas such that at least some of the large amount of furnace gas is mixed with at least a portion of the diluted fuel stream. A fuel dilution device for fuel dilution that reduces nitrogen oxide emissions through fuel staging comprising a first conduit, a second conduit, an oxidant source, and combustion means, comprising: The first conduit has an inlet and an outlet remote from the inlet, and is adapted to transmit a flow of fuel entering and exiting the inlet at the first pressure, the first speed and the first fuel index, The second conduit has an intake and an outlet away from the intake, and is adapted to transmit the flow of fluid entering and exiting the intake at the second pressure, the second speed and the second fuel index, the second fuel index being Differ from the first fuel index by at least about 0.1, and at least one of the second pressure and the second speed is different from at least one of the first pressure and the first speed, whereby the fuel flow exits the outlet of the first conduit and There is a mixing potential between the flow of fluid exiting the outlet of the second conduit, Thereby, the flow of at least some of the fuel exiting the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, thereby providing a first fuel index and Generate at least one diluted fuel flow having an intermediate fuel index between the two fuel indexes, The combustion means burns some oxidant with at least a portion of at least one of the fuel stream or the fluid stream or the diluted fuel stream to generate a gas containing a reduced amount of nitrogen oxides, the reduced amount of nitrogen oxides being A fuel dilution device that is less than the greater amount of nitric oxide produced by burning fuel using means other than the fuel dilution device. A fuel dilution device comprising a first conduit and a second conduit, a means for supplying a flow of fuel, a means for supplying a flow of fluid, a fuel dilution for reducing nitrogen oxide emissions through fuel staging comprising a source of oxidant and a combustion means As a system, The first conduit has an inlet and an outlet remote from the inlet and is adapted to transmit the flow of fuel entering and exiting the inlet at the first thermodynamic state and the first fuel index, The second conduit has an intake and an outlet away from the intake, and is adapted to transmit the flow of fluid entering and exiting the intake at the second thermodynamic state and in the second fuel index, the second fuel index being the first fuel Differing from the index by at least about 0.1, and the second thermodynamic state is different from the first thermodynamic state, whereby a mixed potential exists between the flow of fuel out of the outlet of the first conduit and the flow of fluid out of the outlet of the second conduit and, The means for supplying the flow of fuel supplies the flow of fuel to the inlet of the first conduit, the flow of fuel exiting the outlet of the first conduit at the first thermodynamic state and the first fuel index, The means for supplying the flow of fluid supplies the flow of fluid to the outlet of the second conduit, the flow of fluid coming out of the outlet of the second conduit at the second thermodynamic state and the second fuel index, Thereby, the flow of at least some of the fuel exiting the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, thereby providing a first fuel index and Generate at least one diluted fuel flow having an intermediate fuel index between the two fuel indexes, The combustion means burns some oxidant with at least a portion of at least one of the fuel stream or the fluid stream or the diluted fuel stream to generate a gas containing a reduced amount of nitrogen oxides, the reduced amount of nitrogen oxides being Less than the greater amount of nitric oxide produced by burning fuel using means other than a fuel dilution device. A fuel dilution device comprising a first conduit and a second conduit, a means for supplying a flow of fuel, a means for supplying a flow of fluid, a fuel dilution for reducing nitrogen oxide emissions through fuel staging comprising a source of oxidant and a combustion means As a system, The first conduit has an inlet and an outlet remote from the inlet, and is adapted to transmit a flow of fuel entering and exiting the inlet at the first pressure, the first speed and the first fuel index, The second conduit has an intake and an outlet away from the intake, and is adapted to transmit the flow of fluid entering and exiting the intake at the second pressure, the second speed and the second fuel index, the second fuel index being Differ from the first fuel index by at least about 0.1, and at least one of the second pressure and the second speed is different from at least one of the first pressure and the first speed, whereby the fuel flow exits the outlet of the first conduit and There is a mixing potential between the flow of fluid exiting the outlet of the second conduit, The means for supplying the flow of fuel supplies the flow of fuel to the inlet of the first conduit, the flow of fuel exiting the outlet of the first conduit at the first pressure, the first speed and the first fuel index, The means for supplying the flow of fluid supplies the flow of fluid to the outlet of the second conduit, the flow of fluid coming out of the outlet of the second conduit at a second pressure, a second velocity and a second fuel index, Thereby, the flow of at least some of the fuel exiting the outlet of the first conduit is mixed with the flow of at least some of the fluid exiting the outlet of the second conduit at a location proximate both the outlet and the outlet, thereby providing a first fuel index and Generate at least one diluted fuel flow having an intermediate fuel index between the two fuel indexes, The combustion means burns some oxidant with at least a portion of at least one of the fuel stream or the fluid stream or the diluted fuel stream to generate a gas containing a reduced amount of nitrogen oxides, the reduced amount of nitrogen oxides being Less than the greater amount of nitric oxide produced by burning fuel using means other than a fuel dilution device.