CN1616884A - Improved fuel staging method for low NOx operation - Google Patents

Abstract

A method of diluting fuel to reduce NOx using a fuel dilution device comprising: a first conduit having an inlet and an outlet for conveying fuel flowing into the inlet and out of the outlet in a first thermodynamic state and a first fuel index and a second conduit having an inlet and an outlet for conveying flow into the inlet and out of the outlet at a second/different thermodynamic state and a second fuel index that differs from the first fuel index by at least about 0.1 fluid flow, whereby there is a tendency to mix between the two streams exiting said outlet and discharge; near said outlet and discharge, at least a portion of the fuel mixes with at least a portion of the fluid, thereby producing a stream having intermediate fuel Exponential dilution of fuel flow.

Description

Improved fuel staging method for low NOx operation

Background technique

The present invention relates to fuel staging methods and systems for reducing nitrogen oxide (NOx) emissions, and more particularly to such methods and systems using fuel dilution nozzles in low NOx combustors.

One of the challenges faced by the chemical process industry (CPI) is to burn spent fuel for economical reasons while meeting low NOx and CO emission requirements. Spent fuel contains a higher C/H ratio gas mixture which burns with a very bright flame due to the formation of carbon oxides and depending on the combustion conditions also produces carbon black particles or carbon. A typical refinery fuel composition includes varying amounts of fuel and inert gases (eg Cl, C2, C3, ... Cn, olefins, hydrogen, nitrogen, CO2, water vapour). If carbon or soot particles are formed on a fuel nozzle, under the appropriate current pressure and temperature conditions, the soot structure will usually grow near the nozzle exit. This can lead to clogged fuel injection, deflected fuel jets, overheating of nozzles and furnace components such as process tubes and refractory walls, and potential shutdown of burner and furnace operation. Furnace downtime can result in huge financial losses, including losses due to disruptions in downstream production.

Impure refinery fuels consisting of high carbon and gases such as acetylene, ethane, propane, butane, and olefins (e.g. ethylene and propylene) typically produce soot particles if the fuel nozzles are subjected to:

Insufficient mixing in the furnace (due to non-optimal conditions in the number of nozzles, nozzle structure, injection angle and injection velocity) (generally classified as a burner design problem);

Lack of available air or oxidant near the fuel nozzles (generally categorized as burner flow structure problems);

Inadequate fuel nozzle cooling (often exposed to furnace heat radiation) (generally categorized as fuel nozzle construction and burner design issues);

Disruption of fuel flow (reliability of upstream fuel equipment) (generally categorized as process issues);

Low burn operation (resulting in lower fuel flow rates) (generally classified as a process issue); or

Changes in refinery fuel composition, ie, carbonaceous matter (generally classified as a process requirement issue).

Burner or nozzle design can significantly affect nozzle overheating, soot formation, and nozzle clogging, so burner equipment requires frequent maintenance. These problems can be mitigated by changing process conditions such as venting of process residues and/or interruption of fuel flow, which also affect the degree to which fuel nozzles should be cooled. Changing process conditions and fuel composition is common in refinery operations.

Another challenge facing CPI is the requirement for low NOx emissions to meet emissions regulations. NOx emissions regulations (subordinate to the 1990 Clean Air Regulations) in various regions of the United States require NOx emissions from process heaters, boilers, gas turbines, and other stationary combustion equipment to be less than 10 ppm. The most common CPI or BACT (Best Effective Control Technology) solution is to use SCR (Selective Catalytic Reactor) for after-purification of flue gas, that is, to inject ammonia water in a large catalytic reactor to reduce the NOx contained in the fuel stream ( By converting NOx to N ₂ ). This process is costly and requires large amounts of ammonia, hot air, and electricity to run the ID fans.

Most refineries do not want to install SCRs and use low NOx burners to comply with NOx requirements. However, low NOx burners are not always able to maintain NOx levels below 10ppm in various heating operations such as steam methane reformers (SMRs), crude oil heaters, ethylene crackers or boilers. For this reason, regulatory agencies have not certified the use of low NOx burners as BACT. In other words, SCR is currently the only economically viable method of meeting stringent NOx standards in ozone-reaching regions where ground-level ozone concentrations exceed legal limits.

Typically, CPI operators use clean natural gas or an optimal blend of natural gas and impure refinery fuels to minimize maintenance costs. However, due to the shortage of natural gas and the high cost of the fuel, the clean burning of natural gas is not always available to the process industry. Refineries that are able to burn spent fuel generally have higher productivity and are more competitive than other refineries that do not fully utilize the potential of spent fuel.

As for reducing NOx emissions, common NOx control methods include utilizing low NOx burners equipped with advanced fuel staging and diluting the air/fuel ratio with flue gas recirculation (FGR). Injection of non-reactive or inert chemicals into the fuel/oxidant mixture lowers the average flame temperature and therefore reduces NOx emissions. However, these methods require additional piping and energy loss for conveying the flue gas. In addition, some energy is lost due to the need to heat the gas from ambient temperature to process temperature. Additionally, field data published in the literature does not show that these methods are capable of achieving NOx emissions below 10 ppm.

To reduce NOx emissions, various devices and methods employing fuel staging have been developed. Several of these methods are discussed below.

US Patent Application 2003/0148236 (Joshi et al.) discloses an ultra-low NOx burner utilizing segmented fuel nozzles. The burner has eight fuel section nozzles mounted around the main burner body. The center portion of the burner is used to provide 100% combustion air, injecting a very small amount of fuel (~10%) to maintain overall flame stability. The remainder of the fuel (-90%) is injected using multiple fuel segment nozzles. The fuel segment nozzle has a special fuel nozzle with two circular holes. As shown in Figures 1A-1C, the angulation of these nozzles from the axial and radial direction facilitates interaction with the combustion air and due to the higher injection velocity (500-1000 ft/s or 5-15 psig depending on the combustion velocity) Fuel supply pressure) resulting in delayed mixing of entrained furnace gas.

US Patent 6383462 (Lang) discloses a method and apparatus, as shown in Figure 2, in which there is a mixing chamber outside the "burner and furnace" for mixing flue gas from the furnace with fuel gas. The fuel gas is further diluted with additional flowing excitation gas using a convergent-divergent Venturi mixer. The resulting mixture (fuel diluted with flue gas) is then sent to a burner where it is burned in a furnace together with combustion air. Depending on how diluted the fuel gas is, NOx emissions can be reduced from 26ppm to 14ppm. This device and method does not reduce NOx emissions below 10 ppm, and the results are not comparable to the general results of the SCR process.

US Patent 6481209 (Johnson et al.) discloses a fuel staging system suitable for gas turbine engines. Efficient combustion with air with low NOx and CO emissions is achieved by splitting the fuel injection stream into: 1) injectors installed in the swirl mixer, and 2) installed in the entrapment vortex area of the combustion chamber injectors inside. However, this injection scheme is not suitable for large furnace blocks, where it is not possible to create entrapped vortex regions due to the furnace and load structure.

US Patent 6,558,154 (Eroglu et al.) discloses a method of controlled fuel staging for aeroengines in which two separately mounted fuel staging nozzles are used. A set of emission and fluctuation sensors is installed downstream of each segmented area. These sensors measure the quality of the combustion products produced by each segmented zone, and the control unit then varies the corresponding amount of fuel injected into each zone by changing operating and environmental conditions.

US Patent 5601424 (Bernstein et al.) discloses a method for reducing NOx using atomizing steam injection control. The amount of NOx is reduced by adding atomized steam to the burner flame that can atomize fuel oil. A 30% reduction in NOx requires approximately 0.5 lb steam/lb fuel flow. Large quantities of steam are required to lower the flame temperature and achieve the desired NOx reduction. Also, if the flame is quenched due to the use of large amounts of steam, the flame may become unstable and sputter. Therefore, in order to ensure flame stability, the amount of steam injected has an upper limit.

The gas turbine industry also uses a similar steam injection process for NOx control. However, there is a huge economic price to be paid for reducing NOx emissions due to the inefficient steam injection mode. The steam consumption is very large and the process is inefficient and economically uneconomical for NOx control.

It would be desirable to have cost-effective, improved equipment and methods for reducing NOx emissions that are capable of combusting refinery off-gases without excessive NOx emissions.

It would further be desirable to have an apparatus and method that would reduce equipment maintenance due to problems such as burner nozzle plugging and process tube overheating, as well as improve fuel efficiency and furnace productivity among other benefits.

It is further desirable to have an apparatus and method that can bring existing low NOx burners to SCR levels of NOx, enabling refineries to comply with NOx regulations without resorting to costly SCR processes.

It is further desirable to have an apparatus and method that would allow the process industry to consume inexpensive spent fuel without incurring maintenance costs such as nozzle clogging, equipment overheating, process interruptions, etc., while maintaining NOx emissions below 10 ppm to comply with NOx regulations.

It is also desired to have a device and method for burning fuel, which has better combustion performance than the prior art, and can also overcome many difficulties and shortcomings of the prior art to produce better and more favorable effects.

Summary of the invention

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

The first embodiment of the method for reducing nitrogen oxide emissions by fuel staged dilution of the fuel includes a number of steps. The first step is to provide a fuel dilution device comprising: a first conduit having an inlet and an outlet separate from the inlet, the first conduit for delivering a fuel flow of a first thermodynamic state and a first fuel index flow into the inlet and out of the outlet; a second conduit having an inlet and an outlet separate from the inlet for conveying a fluid flow into the inlet and out of the outlet having a second thermodynamic state and a second fuel index, the second fuel index being the same as the first The fuel index differs by at least about 0.1, and the second thermodynamic state is different from the first thermodynamic state, whereby there is a tendency for mixing between the fuel flow out of the first conduit outlet and the fluid flow out of the second conduit outlet. The second step is to supply the inlet of the first conduit with a flow of fuel that flows out of the outlet of the first conduit in a first thermodynamic state and a first fuel index. The third step is to supply the inlet of the second conduit with a fluid flow that exits the outlet of the second conduit in a second thermodynamic state and a second fuel index, whereby, at a location near the outlet and the outlet, from At least a portion of the fuel flow from the outlet of the first conduit mixes with at least a portion of the fluid flow from the outlet of the second conduit to produce at least one diluted fuel flow having a fuel index between the first fuel index and the second fuel index between. The fourth step is to provide a source of oxidant. The fifth step is to combust 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, thereby producing a gas having a reduced nitrogen oxide content relative to In terms of higher NOx levels from burning fuel using methods other than the fuel dilution device.

There are several variations of the first embodiment of the method. One variation is that the fluid is the fuel. In another variation, the fluid is selected from water vapor, flue 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. Another variation is that at least the majority of the second conduit is disposed within the first conduit. In another variation, the second conduit has an equivalent diameter (D _c ), and the outlet of the second conduit is located a distance behind the outlet of the first conduit, said distance being about (2D _c ) to about (20D _c ).

The second embodiment of the present method of reducing nitrogen oxide emissions by fuel staged dilution of fuel is similar to the first embodiment but includes two additional steps. The first additional step is to install a cyclone in the second pipe. A second additional step is sending at least a portion of the fluid flow through the swirler, thereby swirling at least a portion of the fluid exiting the second conduit.

A third embodiment of the method is similar to the first embodiment but includes two additional steps. A first additional step is to provide a zipper spout for fluid transfer with the first conduit outlet. A second additional step is delivering at least a portion of the diluted fuel flow through the zip spout.

A fourth embodiment of the method is similar to the first embodiment, but includes the additional step of placing the fuel dilution device in the flow channel of a furnace with a large amount of furnace gas, so that at least a portion of the furnace gas Mixed with at least a portion of the diluted fuel stream.

Another embodiment of a method of reducing nitrogen oxide emissions by fuel staging for fuel dilution includes multiple steps. The first step is to provide a fuel dilution device comprising: a first conduit having an inlet and an outlet separate from the inlet for delivering flow into the inlet at a first pressure, a first velocity and a first fuel index and A fuel flow out of the outlet; a second conduit having an inlet and an outlet separate from the inlet for conveying a fluid flow into the inlet and out of the outlet at a second pressure, a second velocity, and a second fuel index , the second fuel index differs from the first fuel index by at least about 0.1, and at least one of the second pressure and the second velocity differs from at least one of the first pressure and the first velocity, so that There will be a tendency to mix between the fuel flow of the fuel flow and the fluid flow exiting the outlet of the second conduit. The second step is to supply the inlet of the first conduit with a flow of fuel that flows out of the outlet of the first conduit at a first pressure, a first velocity, and a first fuel index. The third step is to supply a fluid flow to the inlet of the second conduit, the fluid flow flows out of the discharge of the second conduit at a second pressure, a second velocity and a second fuel index, thereby, at a position near the outlet and the discharge , at least a portion of the fuel flow from the outlet of the first conduit is mixed with at least a portion of the fluid flow from the outlet of the second conduit to produce at least one diluted fuel flow having a fuel index between the first fuel index and the second fuel index between indices. The fourth step is to provide a source of oxidant. The fifth step is to combust a portion of the oxidizer with at least a portion of at least one of the fuel stream, or the fluid stream, or the diluted fuel stream, thereby producing a gas having a reduced nitrogen oxide content by Relative to higher NOx levels from burning fuel using methods other than this fuel dilution device.

A first embodiment of a fuel dilution device for reducing nitrogen oxide emissions by fuel-staging fuel dilution has several elements. The first element is a first conduit having an inlet and an outlet separate from the inlet for conveying a flow of fuel flowing into the inlet and out of the outlet in a first thermodynamic state and a first fuel index. The second element is a second conduit having an inlet and an outlet separate from the inlet for conveying a fluid flow into the inlet and out of the outlet in a second thermodynamic state and a second fuel index, the second fuel The index differs from the first fuel index by at least about 0.1, and the second thermodynamic state is different from the first thermodynamic state, whereby there is a mixing gap between the flow of fuel flowing out of the outlet of the first conduit and the flow of fluid flowing out of the outlet of the second conduit Tendency whereby at least a portion of the fuel flow from the outlet of the first conduit mixes with at least a portion of the fluid flow from the discharge of the second conduit at a location proximate to the outlet and the discharge to produce at least one dilute fuel flow , whose fuel index is between the first fuel index and the second fuel index. The third element is the source of oxidant. The fourth element is a method of 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, thereby producing a gas with reduced nitrogen oxide content, said small amount of nitrogen oxide The emissions reductions are relative to the higher NOx levels produced by burning fuel using methods other than the fuel dilution device.

There are many variations of the first embodiment of the fuel dilution device. One change is that the fluid is a fuel. In another variation, the fluid is selected from water vapor, flue 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. Another variation is that at least a substantial portion of the second conduit is disposed within the first conduit. Another change is that the second pipeline has an equivalent diameter (D _c ), and the discharge port of the second pipeline is located at a distance behind the outlet of the first pipeline, and the distance is about (2×D _c )-about (20× D _c ).

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

A second embodiment of the fuel dilution device is similar to the first embodiment, but with a swirler installed 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 fluid at the outlet of the first conduit.

Another embodiment of a fuel dilution device for reducing nitrogen oxide emissions by fuel staging dilution of fuel includes a number of elements. The first element is a first conduit having an inlet and an outlet separate from the inlet for delivering a flow of fuel flowing into the inlet and out of the outlet at a first pressure, a first velocity, and a first fuel index. The second element is a second conduit having an inlet and a discharge separate from the inlet for carrying a fluid flow into the inlet and out of the discharge at a second pressure, a second velocity, and a second fuel index, para. The second fuel index is different from the first fuel index by at least about 0.1, and at least one of the second pressure and the second velocity is different from at least one of the first pressure and the first velocity, so that the fuel flowing out of the outlet of the first conduit There will be a tendency to mix between the flow and the fluid flow exiting the outlet of the second conduit, whereby at least a portion of the flow of fuel flowing from the outlet of the first conduit is the same as that exiting the outlet of the second conduit near the outlet and the outlet. At least a portion of the outgoing fluid streams are mixed to produce at least one dilute fuel stream having a fuel index between the first fuel index and the second fuel index. The third element is the source of oxidant. The fourth element is 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, thereby producing a gas with reduced nitrogen oxides content This is relative to the higher NOx levels produced by burning fuel using methods other than this fuel dilution device.

Another aspect of the present invention is to provide a system for reducing nitrogen oxide emissions by fuel staging dilution of fuel. The system includes several elements. The first element is a fuel dilution device comprising: a first conduit having an inlet and an outlet separate from the inlet for conveying a flow of fuel flowing into the inlet and out of the outlet at a first thermodynamic state and a first fuel index; a second conduit having an inlet and an outlet separate from the inlet for conveying a fluid flow into the inlet and out of the outlet in a second thermodynamic state and a second fuel index, the second fuel index being the same as the first fuel index The exponents differ by at least about 0.1 and the second thermodynamic state is different from the first thermodynamic state such that there is a tendency to mix between the fuel flow exiting the first conduit outlet and the fluid flow exiting the second conduit outlet. The second element is a method of supplying the inlet of the first conduit with a flow of fuel that flows out of the outlet of the first conduit in a first thermodynamic state and a first fuel index. The third element is a means of supplying the inlet of the second conduit with a flow of fluid which flows out of the outlet of the second conduit in a second thermodynamic state and a second fuel index, whereby, at a location close to the outlet and the outlet, At least a portion of the fuel flow from the outlet of the first conduit mixes with at least a portion of the fluid flow from the outlet of the second conduit to produce at least one diluted fuel flow having a fuel index between the first fuel index and the second fuel index. between indices. The fourth element is the source of the oxidizing agent. The fifth element is a means of combusting a portion of the oxidizer with at least a portion of at least one of the fuel stream, or the fluid stream, or the diluted fuel stream, thereby producing a gas with reduced nitrogen oxide content The reduction is relative to the higher NOx levels produced by burning fuel using methods other than the fuel dilution device.

Another embodiment of a system for reducing nitrogen oxide emissions by fuel-staging fuel dilution includes a number of elements. The first element is a fuel dilution device comprising: a first conduit having an inlet and an outlet separate from the inlet for conveying fuel flow into the inlet and out of the outlet at a first pressure, a first velocity, and a first fuel index a fuel flow; a second conduit having an inlet and an outlet separate from the inlet for conveying a fluid stream flowing into the inlet and out of the outlet at a second pressure, a second velocity, and a second fuel index, the second The fuel index differs from the first fuel index by at least about 0.1, and at least one of the second pressure and the second velocity differs from at least one of the first pressure and the first velocity such that the flow of fuel exiting the outlet of the first conduit There will be a tendency to mix with the fluid flow exiting the outlet of the second conduit. The second element is a method of supplying the inlet of the first conduit with a flow of fuel that flows out of the outlet of the first conduit at a first pressure, a first velocity, and a first fuel index. The third element is a means of supplying a fluid flow to the inlet of the second conduit, said fluid flow exiting the outlet of the second conduit at a second pressure, a second velocity, and a second fuel index, whereby, in proximity to the outlet and the outlet at a position where at least a portion of the fuel flow from the outlet of the first conduit mixes with at least a portion of the fluid flow from the outlet of the second conduit to produce at least one diluted fuel flow having a fuel index between the first fuel index and Between the second fuel index. The fourth element is the source of the oxidizing agent. The fifth element is a means of combusting a portion of the oxidizer with at least a portion of at least one of the fuel stream, or the fluid stream, or the diluted fuel stream, thereby producing a gas with reduced nitrogen oxide content The reduction is relative to the higher NOx levels produced by burning fuel using methods other than the fuel dilution device.

Description of drawings

The present invention is described by way of embodiment in conjunction with accompanying drawing, wherein:

Fig. 1A is the cross-sectional plan view of the fuel segmentation nozzle used in the ultra-low NOx burner in the prior art;

Fig. 1B is a cross-sectional vertical projection view of the fuel segmented nozzle in the prior art of Fig. 1A;

Figure 1C is a side view of the fuel segment nozzle in the prior art of Figure 1B;

Fig. 2 is a cross-sectional vertical projection view of a mixing chamber used for mixing fuel gas, flow excitation gas and fuel gas in the prior art;

Figure 3 is a schematic cross-sectional view of an embodiment of the present invention;

Figure 4 is a schematic cross-sectional view of another embodiment of the present invention;

Figure 5A is a schematic diagram of another embodiment utilizing strong jet-weak jet entrainment in the present invention;

Figure 5B is a schematic cross-sectional view of another embodiment of entrainment induced by swirling in the present invention;

Figure 6 is a schematic cross-sectional view of another embodiment of the present invention;

Figure 7 is a schematic cross-sectional view of another embodiment of the present invention comprising a zippered nozzle or nozzle;

Figure 8A is a schematic front view of a zipper nozzle or nozzle;

Figure 8B is a schematic side view of a zipper nozzle or nozzle mounted on a nozzle such as that shown in Figure 7;

Figure 8C is a schematic plan view of a zipper nozzle or nozzle;

Figure 8D is a detailed schematic illustration of a portion of the front view of the zipper nozzle or nozzle in Figure 8A to indicate its dimensions; and

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

Detailed description of the invention

The present invention solves a series of problems faced in the design of combustion equipment, such as burners for heating reformers, thermal processors, boilers, ethylene cracking furnaces or other high temperature furnaces. The present invention relates to an improved fuel staging process. In particular, two general methods to achieve rapid dilution and blending according to the desired processing purpose are:

I. Use another fuel to segment fuel (F-F): inject high-pressure refinery waste fuel, atomized liquid fuel, etc. into the vicinity of cleaner low-pressure gaseous fuel to achieve clean, maintenance-free, low NOx working conditions ;and

II. Fuel staging (FI) with inert gas: Injection of high pressure inert fluids such as water vapor, nitrogen, CO2 _, etc. near low pressure gaseous fuels to reduce NOx.

As used herein, the term "fuel index" (FI) is defined as the weighted total number of carbon atoms in a fuel, where _H2 is assigned 1.3 carbon numbers, and the weights are the mole fractions of the components: 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 for some fuels and noble gases are shown in Table I. In general, fuels with a higher fuel index are more likely to crack and also produce more NOx through the transient NOx mechanism. In this definition, H2 is a special case. Although H2 does not contain any carbon atoms, H2 additions in natural gas are known to increase NOx emissions. It is pointed out in the literature that compared with methane combustion, pure H2 combustion emits about 30% more NOx. The increase of NOx emitted by H2 combustion helps to increase the flame temperature through thermal NOx mechanism. Since the fuel index is used here to indicate NOx emissions, the weighted value of H2 is set at 1.3, which is consistent with its potential NOx emissions.

Table I: Fuel Index for Selected Fuels and Inert Gases fuel or inert gas fuel index H ₂ 1.3 H ₂ O 0 CO ₂ 0 CO 1 N ₂ 0 CH ₄ 1 C ₃ H ₈ 3 ROG(1) 1.434 PSA exhaust (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 waste gas: H ₂ 30%, CH ₄ 18%, CO ₂ 52%.

(3) Natural gas: CH ₄ 91%, C ₂ H ₆ 64%, 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 used herein, the term "thermodynamic state" is defined as a state of existence of a substance. This definition is based on the generally known concept of thermodynamics, and is extended to include not only the usual temperature and pressure, but also speed, concentration, composition, volume fraction, flow velocity, potential, etc., to fully describe the characteristics of the stream. This definition is used to precisely define the mixing that occurs between two streams due to the difference in thermodynamic state.

These two methods are described in detail below.

I. Fragmenting the fuel with another fuel (F-F):

The method can be used to combust refinery waste fuels including hydrogen and higher C/H ratio fuels (ethane, propane, butane, olefins, etc.) mixture. This refinery off-gas combustion can cause maintenance problems due to thermal cracking of high C/H ratio fuels and subsequent soot growth at the burner fuel nozzles. Additionally, burning this fuel results in higher than normal NOx emissions.

To improve the combustion performance of high C/H ratio refinery spent fuels, the unclean fuels are diluted with cleaner (secondary) fuel streams such as hydrogen, syngas, natural gas or low BTU fuel blends. In one embodiment shown in Figure 3, a high-pressure refinery fuel gas (fuel gas containing a high C/H ratio) is injected through the central nozzle 32, The annular region injects a cleaner low-pressure fuel gas such as natural gas, syngas, industrial waste gas, PSA waste gas (recycle fuel gas after hydrogen product is removed from the PSA absorber bed), etc. As shown in Figure 3, the outlet 36 of the central nozzle is recessed a preferred distance from the outlet 38 of the outer nozzle. This distance is preferably 2-20 times the equivalent diameter (D _c ) of the central nozzle. Depending on the degree of fuel dispersion between the high pressure refinery fuel gas and the cleaner low pressure fuel gas, this distance is preferably from about 1/16" to 1".

Those skilled in the art will appreciate that references to "high pressure" in Figures 3-7 and 9 can also mean "high speed" or "high pressure or high speed". Similarly, references to "low pressure" in the above figures could mean "low speed" or "low pressure or speed".

The configuration shown in Figure 3 allows mixing of unclean high pressure refinery fuel gas with clean low pressure fuel gas due to turbulent jet interaction. The velocity of the high pressure refinery fuel gas through the center nozzle 32 is preferably about 900-1400 ft/sec (preferably sonic or throttling). The velocity of the low pressure fuel gas through the annular region 33 between the central nozzle 32 and the outer nozzle 34 is preferably about 100-900 ft/sec, depending on the available supply pressure of the low pressure gas. The high velocity gas stream exiting the central nozzle outlet 36 entrains the lower velocity gas stream near the outer nozzle outlet 38 to form a "first stage" mixing before these streams exit through the orifice 40 . Design The structure, angle, etc. of the nozzle holes of the outer nozzle are designed to obtain the best "second stage mixing" in the furnace atmosphere. A large amount of furnace gas 42 is entrained for the second stage of dilution, thereby reducing the peak flame temperature, thereby reducing NOx emissions.

Figure 4 depicts a liquid fuel (F-F) segmented structure. In this embodiment, when high pressure (and high C/H ratio) liquid fuel (such as fuel oil, diesel, heavy fuel oil, waste liquid fuel, etc.) Dilute it. For example, heavy oil can be atomized with an atomizing fluid such as water vapor and subsequently diluted with low pressure fuel gas so that it burns in the furnace without producing soot. This embodiment also reduces NOx emissions due to the lower peak flame temperature.

In FIG. 4 , X is the distance from the outlet of the central nozzle 32 to the back of the outlet of the outer nozzle 34 . D _c is the flow area-equivalent diameter of the outlet of the central nozzle, that is, the total flow area of the outlet of the central nozzle is equal to a circle with D _c as the diameter. D _e is the flow area-equivalent diameter of the outer nozzle, that is, the total flow area at the outlet of the nozzle is equal to the circle with D _e as the diameter.

The other two (F-F) fuel stage embodiments are shown in Figures 5A and 5B. In Figure 5A, a strong jet-weak jet interaction occurs between high pressure refinery fuel gas and low pressure fuel gas. High pressure refinery fuel gas is injected at high velocity (approximately 900-1400 ft/s) in a preferred direction in high pressure nozzle 52 and the low pressure fuel gas injected in low pressure nozzle 54 is entrained by the high pressure refinery fuel gas.

In Figure 5B, high pressure refinery fuel gas is swirled in central lance 32 using fuel swirler 56, the low pressure fuel gas being entrained in the collapsed region (central region) of the high velocity swirl. This allows for good mixing of the high pressure refinery fuel gas and low pressure fuel gas before they exit the outer lance 34 and enter the furnace (not shown), where make-up dilution with the furnace gas 42 can also occur. This method is advantageous for applications requiring a shorter flame profile or smaller combustion space.

The (F-F) stage would be applied in a Steam Methane Reformer (SMR) where the high pressure fuel gas is typically fed natural gas or refinery off-gas, these fuels are usually classified as trim fuels. According to FIG. 6 , high-pressure fuel gas is injected in the central nozzle 32 . The low pressure fuel gas injected in the annular region 33 between the central nozzle 32 and the outer nozzle 34 is usually PSA (pressure swing adsorption) off-gas or a clean exhaust stream of PSA containing CO2 (~45%) , hydrogen (~30%), methane (~15%) and CO (~10%) with a fuel index of about 0.64. After the hydrogen product is separated, the PSA off-gas is permeated through the absorber bed. For a typical reformer with a PSA for hydrogen separation, high pressure trim fuel accounts for 10%-30% of the total energy.

A second advantage of this staging application is the ability to facilitate PSA recovery by extending the range of PSA pressure cycles, especially at the low end. Referring to FIG. 7 , this is accomplished by creating a low pressure zone within the outer nozzle 34 . The high velocity central jet shown in Figure 7 creates a low pressure region around the jet body around which the slower moving low pressure fuel gas is entrained by the faster moving central jet. As an efficient entrainment process occurs, the supply pressure of the low-pressure fuel gas is reduced to maintain the same fuel flow rate.

In a laboratory combustion test, the supply pressure of the low pressure PSA exhaust was reduced from 2 psig to 1.6 psig (a 20% reduction). This is accomplished by injecting the high pressure fuel gas at 25 psig (1300 ft/sec velocity). The combustion energy between the high-pressure fuel gas and the low-pressure fuel gas is 30:70, respectively.

To further define the details of the (F-F) staged process, laboratory test results were considered as obtained using a low NOx burner. The burner has 10 fuel nozzles distributed on a circle with a diameter of 18". Among the 10 fuel nozzles, two nozzles are reserved for (F-F) type segmented structure. The nozzles have special fuel nozzles and multiple diverging slots (zipper nozzles 74) to facilitate passive mixing. A schematic diagram of the (F-F) fuel staging configuration using the The burn rate is 8MM Btu/hr, and it is designed to use two types of fuel. The details of the two types of fuel are as follows:

High pressure refinery fuel gases: _H2 (18%), natural gas (44%) and ethylene (38%). The fuel has a fuel index of 1.43 and accounts for 30% of the total energy input.

Low pressure fuel gases: _CO2 (52%), natural gas (18%) and _H2 (30). Its fuel index is 0.57, accounting for 70% of the total energy input.

With reference to the structure shown in Fig. 7, the high-pressure fuel gas is injected in a central nozzle 32 made of a standard pipe having a diameter of 3/8″×a wall thickness of 0.035″, concentrically arranged at a distance of 3/4 The outer spray gun 34 pipe that is made of " sch40 pipe. Zipper type nozzle 74 is installed on the end of this pipe. As shown in Fig. 8A-8D, the equivalent diameter of zipper type nozzle is 0.51 ", and has four vertical grooves and one horizontal groove . The divergence angles (α1 and α2) of the vertical slots are 18° and 6°, respectively, and the structure of the axial zipper nozzle nozzle is as follows: 1) There are a series of vertical structures in the intersecting plane between adjacent basic shapes; 2) The flow induces downstream Instability; and 3) High levels of molecular (miniature) mixing between the first fluid (fuel) and the second fluid (furnace gas). The above-mentioned mixing can also take place within the shortest axial distance. The low NOx burner laboratory experiment with the nozzle shown in Figure 7 in the nozzle structure shows that rapid axial mixing occurs and a large amount of entrainment occurs in the furnace gas at a divergence angle β of 7°.

The overall flow process according to the configuration shown in Figure 7 results in a more uniform heat transfer to the load with ultra-low NOx and CO emissions (<15 ppmv) at fuel pressures below 2 psig. It was also found that the combustion of high pressure, high C/H ratio fuel without the nozzle-in-nozzle process produced a significantly soot-rich flame. And NOx emissions are as high as 25-30ppm. This experiment proves that the F-F subsection process can significantly reduce NOx emissions. Using inert gases, the F-1 staged process results in lower emissions.

Whenever the lance-in-nozzle staged process is used for refinery fuels containing up to 50% butane ( _C4H10 ), clear evidence of _enhanced mixing can be found in laboratory furnaces. It was found that the individual flames mixed more rapidly with the furnace gases and produced extensive or flameless combustion. On the other hand, using a simple nozzle with a cylindrical nozzle lance produces a more pronounced (bluish), longer flame, indicating poor dilution and mixing of the furnace gases and, at a given fuel supply Under pressure, higher amounts of NOx and CO are also produced.

Table II shows the preferred combustion range, size, dimensionless coefficient and injection angle of the nozzle-in-nozzle e structure proposed by the present invention. Simple annular tubes are used for high pressure refinery fuels, while zip line nozzles are used for low pressure PSA exhaust fuels. These nozzles are critical components of the low NOx burner because the reliability of the burner performance directly affects the steam performance of the steam methane reformer. Table II: Dimensional Parameters for Nozzle-in-Nozzle Fuel Segmented Nozzles Low pressure zipper nozzle High pressure cylindrical nozzle (H) (W) (R ₀ /R ₁ ) (H/R ₀ ) (α1,α2) (β) L/D _e D _c X/D _c Burner combustion capacity (MMBtu/Hr) Groove height (In) Groove width (In) Ratio of groove end radius to center diameter Ratio of groove height to fillet radius Axial divergence angle (°) Radial divergence angle (°) Zipper nozzle thickness to equivalent diameter ratio Pipe Diameter (inches) Distance after Zipper Nozzle 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 above size ranges are valid for a variety of fuels such as natural gas, propane, refinery off-gas, low BTU fuels, etc. The nozzle size is optimally sized based on fuel composition, flow velocity (or burn velocity) and supply pressure available at the burner inlet. In Table II, sizes, ratios and ranges are estimated for a burner firing rate of 2-10MM Btu/Hr. However, for higher firing velocity burners (>10MMBtu/Hr), these dimensions and ranges can be scaled up using standard engineering practice of maintaining a similar flow velocity range.

II. Fragmentation of fuel with inert gas (F-I):

This modified fuel staging process using high pressure inert gases such as water vapor (dry or saturated), CO2, flue gas, nitrogen or other inert gases is performed with low pressure fuel gas to reduce NOx emissions. Staging fuels that may be used include, but are not limited to: natural gas, low BTU process gas (consisting of hydrogen and other refinery fuels), and PSA off-gas. The nozzle structure is similar to that shown in Figure 3-7. The main purpose of this process is to further reduce NOx emissions. A preferred embodiment is shown in FIG. 9 .

Referring to Fig. 9, high pressure (30-100 psig) saturated or dry water vapor passes through the central nozzle 32 at a speed of about 900-1400 feet per second, and the low-pressure fuel gas passes through the annular region between the central nozzle 32 and the outer nozzle 34 33 teleportation. The high velocity steam jet 92 entrains fuel gas for first stage dilution (and mixing) within the annular region. The resulting mixture is then passed through a zip nozzle 74 at high velocity (approximately 600-1400 ft/sec) for a second stage of mixing within a furnace (not shown) using furnace gas (not shown). The second stage mixing is very efficient due to the high steam velocity and the entrainment loop created by the individual flames created by the zip nozzle. Fuel dilution is improved due to the zipper nozzle structure and the assisted action of steam. The peak flame temperature is further reduced, resulting in ultra-low NOx emissions. Table III provides estimates of steam consumption in large steam methane reformer furnaces.

Table III: Economics of steam consumption using the (FI) staged process proposed by the present invention steam injection speed lb_stm/lb fuel 0.02 0.05 burning rate mmbtu/hrLHV 850 850 Calorific value of fuel btu/scf, LHV 1000 1000 fuel cost $/mmbtu, LHV 6 6 fuel molecular weight 18 18 required steam lb/hrmmscfd 8060.408 20161.02 Energy required to generate steam from water at 60F at 100psia and 400F btu/scfbtu/lb 57.11203.2 57.112032 steam cost $/day$/year 14050992 349127480

As shown in Table III, the amount of steam required for fuel dilution is extremely low due to the unique fuel staging method using an inert gas such as water vapor. The amount of steam required for the (F-I) stage is about 2%-10% lb/lb of the required low pressure fuel compared to low pressure fuel. High velocity steam is used in a two-stage dilution process: 1) using steam and low pressure fuel gas in the lance, and 2) using high velocity fuel-steam mixture and furnace gas in the furnace space.

Comparing simple existing nozzle configurations (using only zipper or cylindrical nozzles rather than nozzle-in-nozzle arrangements) to the nozzle-in-nozzle configuration in Figure 9, it has been shown that the use of an inert gas such as nitrogen Laboratory experiments conducted were able to reduce NOx by about 30%-40%. For example, using a low NOx burner at a firing rate of 5MM btu/Hr, using ambient combustion air, operating at an average temperature of 1600°F, with a furnace exhaust temperature of 2000°F, using a nitrogen flow of 10% by weight Speed, NOx emissions drop from 10ppm ( ₃ % O2 conversion) with no inert gas in the center to about 7ppm ( ₃ % O2 conversion) with nitrogen in the center.

In each of the embodiments described above, the beneficial effects achieved by the present invention are driven by two differences that exist between the streams leaving the two pipelines. The first difference is the difference in the thermodynamic state of each stream, and the second difference is the difference in the fuel index of each stream. In particular, in order for a mixing potential to exist between the two streams exiting the two pipes, there must be a difference in the thermodynamic states of the two streams, and there must be a difference between the fuel indices of the two streams of at least 0.1, preferably at least 0.2, to be effective Reduce NOx.

In the embodiments depicted in the drawings and described above, the difference between the thermodynamic states of the two streams is represented by a pressure difference (i.e., a "high pressure" fluid in one pipeline and a "low pressure" fluid in the other pipeline) fluid). However, those of ordinary skill in the art will appreciate that differences in thermodynamic states can also be expressed in, and result from, factors such as differences in velocity, temperature, concentration, composition, volume fraction, flow velocity, potential, and the like.

Accordingly, the present invention includes many other embodiments and modifications thereof, not shown in the drawings, or described in the detailed description of the invention. However, these embodiments and modifications fall within the scope of protection of the following claims and their corresponding terms.

Those of ordinary skill in the art will appreciate that the embodiments and variations shown in the drawings and described in the detailed description do not disclose all possible aspects of the invention and that others are possible. Therefore, all such schemes are within the expectation of the present invention, and are also within the protection scope of the present invention. For example, in each of the embodiments described in FIGS. 3-7 and 9, the low-pressure and high-pressure streams can be interchanged (i.e., the low-pressure nozzle can be an inner nozzle and the high-pressure nozzle can be an outer nozzle. ).

In addition to reducing NOx emissions, the present invention has other advantages and benefits, some of which are described below:

The fuel staging method proposed by the present invention enables effective nozzle cooling due to (F-F) staging or (F-I) staging. Due to the large nozzle exit area of the fuel nozzle, the lance nozzle is effectively cooled by the outflowing high velocity fuel gas or inert flow. This is a significant improvement over existing round nozzles.

The use of high C/H ratio fuels with existing nozzles presents serious maintenance issues and carbon black plugging problems due to weak entrainment and higher operating temperatures. In contrast, the present invention has the following advantages:

- Reduced coking tendency when using fuels with high carbon content

- Possibility to use fuel with lower flow velocity or higher calorific value

-Cheaper fuel nozzle materials can be used (stainless steel 304 or 310 will do the trick)

Thermal cracking is a major consideration for many refinery furnaces using fuels containing C1-C4 hydrocarbons. Cracked carbon was found to clog burner nozzles, overheat burner components, reduce productivity, and result in poor thermal efficiency. Therefore, maintenance-free operation (using F-F or F-I sections) is a very important advantage for refinery operators.

Although illustrated and described herein in terms of particular embodiments, the invention is not intended to be limited to those described. Rather, various modifications may be made in the details within the scope and latitude of the corresponding words of the claims without departing from the spirit of the invention.

Claims (22)

1. one kind is diluted the method that fuel reduces discharged nitrous oxides by the fuel segmentation, comprises the steps:

The fuel dilution device is provided, and it comprises

Have the inlet and first pipeline of the outlet that separates with inlet, this first pipeline be used to carry with first thermodynamic state and the first fuel index flow to inlet and flow out outlet fuel stream and

Second pipeline with import and the outlet that separates with import, this second pipeline is used to carry the fluid stream that flows to import and outflow outlet with second thermodynamic state and the second fuel index, the second fuel index differs at least about 0.1 with the first fuel index, and second thermodynamic state different with first thermodynamic state, the trend of thus can existence between the fuel stream that flows out first pipe outlet and the fluid stream that flows out the outlet of second row of conduits mixing;

Supply with fuel stream to the inlet of first pipeline, described fuel stream flows out the outlet of first pipeline with first thermodynamic state and the first fuel index;

Supply with fluid stream to the import of second pipeline, described fluid flows the outlet that flows out second pipeline with second thermodynamic state and the second fuel index,

Thus, in position near outlet and outlet, at least a portion that the fuel that flows out from first pipe outlet flows is mixed with at least a portion of the fluid stream that flows out from the outlet of second row of conduits, thereby produce at least a dilution fuel stream, its fuel index is between the first fuel exponential sum, the second fuel index;

Oxidizer source is provided; And

The part of oxidant is flowed, maybe should dilute at least a portion burning at least a in the fuel stream with this fuel stream or this fluid, thereby produce the gas that amount of nitrogen oxides reduces, it is with respect to using for the higher amount of nitrogen oxides that the method combustion fuel this fuel dilution device is produced that described amount of nitrogen oxides reduces.

2. the method for claim 1, wherein said fluid is a fuel.

3. the method for claim 1, wherein said fluid is selected from water vapour, flue gas, carbon dioxide, nitrogen, argon, helium, xenon, krypton, other inert fluid and composition thereof or combination.

4. the method for claim 1, wherein contiguous second pipeline of first pipeline.

5. the method for claim 1, wherein the essential part of at least the second pipeline is placed in first pipeline.

6. the method for claim 1 further comprises the steps:

Provide and be placed in the second ducted cyclone; And

Carry at least a portion fluid stream by this cyclone, thereby make at least a portion generation eddy flow in the fluid that flows out second pipeline.

7. the method for claim 1 further comprises the steps:

The zip mode jet pipe that can realize the fluid transmission with first pipe outlet is provided;

Carry at least a portion dilution fuel stream by this zip mode jet pipe.

8. the method for claim 1, wherein second pipeline has equivalent diameter (D _c), the outlet of second pipeline is positioned at the segment distance behind first pipe outlet, and described distance is about (2 * D _c)-Yue (20 * D _c).

9. the method for claim 1 further comprises step: settle this fuel dilution device in the fluid passage that has the stove that contains a large amount of furnace gases, thereby make at least a portion in this furnace gas mix with at least a portion in this dilution fuel stream.

10. one kind is diluted the method that fuel reduces discharged nitrous oxides by the fuel segmentation, comprises the steps:

The fuel dilution device is provided, and this device comprises

First pipeline with inlet and the outlet that separates with inlet, this first pipeline are used to carry the fuel stream that flows to inlet and outflow outlet with first pressure, first speed and the first fuel index;

Second pipeline with import and the outlet that separates with import, this second pipeline is used to carry the fluid stream that flows to import and outflow outlet with second pressure, second speed and the second fuel index, the second fuel index differs at least about 0.1 with the first fuel index, and second in pressure and the second speed at least one different with in first pressure and first speed at least one, thereby the trend of can existence between the fuel stream that flows out first pipe outlet and the fluid stream that flows out the outlet of second row of conduits mixing;

Supply with this fuel stream to the inlet of first pipeline, described fuel stream flows out the outlet of first pipeline with first pressure, first speed and the first fuel index;

Supply with this fluid stream to the import of second pipeline, described fluid flows the outlet that flows out second pipeline with second pressure, second speed and the second fuel index,

Thus, in position near described outlet and outlet, at least a portion that the fuel that flows out from first pipe outlet flows is mixed with at least a portion of the fluid stream that flows out from the outlet of second row of conduits, thereby produce at least a dilution fuel stream, its fuel index is between the first fuel exponential sum, the second fuel index;

Oxidizer source is provided;

The part of oxidant is flowed, maybe should dilute at least a portion burning at least a in the fuel stream with this fuel stream or this fluid, thereby produce the gas that amount of nitrogen oxides reduces, it is with respect to using for the higher amount of nitrogen oxides that the method combustion fuel this fuel dilution device is produced that described nitrogen oxide reduces.

11. one kind is diluted the fuel dilution device that fuel reduces discharged nitrous oxides by the fuel segmentation, comprises

First pipeline with inlet and the outlet that separates with inlet, this first pipeline are used to carry the fuel stream that flows to inlet and outflow outlet with first thermodynamic state and the first fuel index; With

Second pipeline with import and the outlet that separates with import, this second pipeline is used to carry the fluid stream that flows to import and outflow outlet with second thermodynamic state and the second fuel index, the second fuel index differs at least about 0.1 with the first fuel index, and second thermodynamic state different with first thermodynamic state, between the fuel stream that flows out first pipe outlet is with the fluid stream that flows out the outlet of second row of conduits, can have the trend of mixing thus;

Thus, in position near described outlet and outlet, at least a portion that the fuel that flows out from first pipe outlet flows is mixed with at least a portion of the fluid stream that flows out from the outlet of second row of conduits, thereby produce at least a dilution fuel stream, its fuel index is between the first fuel exponential sum, the second fuel index;

Oxidizer source; And

The part of oxidant is flowed, maybe should dilute the method for at least a portion burning at least a in the fuel stream with this fuel stream or this fluid, thereby produce the gas that amount of nitrogen oxides reduces, it is with respect to using for the higher amount of nitrogen oxides that the method combustion fuel this fuel dilution device is produced that described nitrogen oxide reduces.

12. fuel dilution device as claimed in claim 11, wherein said fluid is a fuel.

13. fuel dilution device as claimed in claim 11, wherein said fluid is selected from water vapour, flue gas, carbon dioxide, nitrogen, argon, helium, xenon, krypton, other inert fluid and composition thereof or combination.

14. fuel dilution device as claimed in claim 11, wherein contiguous second pipeline of first pipeline.

15. fuel dilution device as claimed in claim 11, wherein the essential part of at least the second pipeline is placed in first pipeline.

16. fuel dilution device as claimed in claim 11 further comprises cyclone, is placed in second pipeline.

17. fuel dilution device as claimed in claim 11 wherein further comprises the zip mode jet pipe in the fluid passage with first pipe outlet.

18. fuel dilution device as claimed in claim 11, wherein second pipeline has equivalent diameter (D _c), the outlet of second pipeline is positioned at the segment distance behind first pipe outlet, and described distance is about (2 * D _c) pact (a 20 * D _c).

19. fuel dilution device as claimed in claim 11, wherein this fuel dilution device in the fluid passage of the stove that contains a large amount of furnace gases, thereby make at least a portion in this furnace gas mix with at least a portion in this dilution fuel stream.

20. one kind is diluted the fuel dilution device that fuel reduces discharged nitrous oxides by the fuel segmentation, comprises

First pipeline with inlet and the outlet that separates with inlet, this first pipeline are used to carry the fuel stream that flows to inlet and outflow outlet with first pressure, first speed and the first fuel index;

Second pipe with import and the outlet that separates with import; This second pipe is for delivery of the fluid stream that flows to import and outflow outlet with the second pressure, second speed and the second fuel index; The second fuel index differs about at least 0.1 with the first fuel index; And second in pressure and the second speed at least one different from the first pressure and the First Speed at least one; Thereby between the fuel stream that flows out the first pipe outlet is with the fluid stream that flows out the second pipe outlet, can there be the trend of mixing

Thus, in position near described outlet and outlet, at least a portion that the fuel that flows out from first pipe outlet flows is mixed with at least a portion of the fluid stream that flows out from the outlet of second row of conduits, thereby produce at least a dilution fuel stream, its fuel index is between the first fuel exponential sum, the second fuel index;

Oxidizer source; And

The part of oxidant is flowed, maybe should dilute at least a portion burning at least a in the fuel stream with this fuel stream or this fluid, thereby produce the gas that amount of nitrogen oxides reduces, it is with respect to using for the higher amount of nitrogen oxides that the method combustion fuel this fuel dilution device is produced that described nitrogen oxide reduces.

21. one kind is diluted the system that fuel reduces discharged nitrous oxides by the fuel segmentation, comprising:

The fuel dilution device comprises:

Have the inlet and first pipeline of the outlet that separates with inlet, this first pipeline be used to carry with first thermodynamic state and the first fuel index flow to inlet and flow out outlet fuel stream and

Second pipeline with import and the outlet that separates with import, this second pipeline is used to carry the fluid stream that flows to import and outflow outlet with second thermodynamic state and the second fuel index, the second fuel index differs at least about 0.1 with the first fuel index, and second thermodynamic state different with first thermodynamic state, between the fuel stream that flows out first pipe outlet is with the fluid stream that flows out the outlet of second row of conduits, can have the trend of mixing thus;

Supply with the means that this fuel flows to the inlet of first pipeline, described fuel stream flows out the outlet of first pipeline with first thermodynamic state and the first fuel index;

Supply with the means that this fluid flows to the import of second pipeline, described fluid stream flows out the outlet of second pipeline with second thermodynamic state and the second fuel index;

Thus, in position near described outlet and outlet, at least a portion that the fuel that flows out from first pipe outlet flows is mixed with at least a portion of the fluid stream that flows out from the outlet of second row of conduits, thereby produce at least a dilution fuel stream, its fuel index is between the first fuel exponential sum, the second fuel index;

Oxidizer source; And

The part of oxidant is flowed, maybe should dilute the method for at least a portion burning at least a in the fuel stream with this fuel stream or this fluid, thereby produce the gas that amount of nitrogen oxides reduces, it is with respect to using for the higher amount of nitrogen oxides that the method combustion fuel this fuel dilution device is produced that described nitrogen oxide reduces.

22. one kind is diluted the system that fuel reduces discharged nitrous oxides by the fuel segmentation, comprising:

The fuel dilution device comprises

First pipeline with inlet and the outlet that separates with inlet, this first pipeline are used to carry the fuel stream that flows to inlet and outflow outlet with first pressure, first speed and the first fuel index; With

Second pipeline with import and the outlet that separates with import, this second pipeline is used to carry the fluid stream that flows to import and outflow outlet with second pressure, second speed and the second fuel index, the second fuel index differs at least about 0.1 with the first fuel index, and second in pressure and the second speed at least one different with in first pressure and first speed at least one, thereby between the fuel stream that flows out first pipe outlet is with the fluid stream that flows out the outlet of second row of conduits, can have the trend of mixing;

Supply with the means that this fuel flows to the inlet of first pipeline, described fuel stream flows out the outlet of first pipeline with first pressure, first speed and the first fuel index;

Supply with the means that this fluid flows to the import of second pipeline, described fluid flows the outlet that flows out second pipeline with second pressure, second speed and the second fuel index,

Thus, in position near described outlet and outlet, at least a portion that the fuel that flows out from first pipe outlet flows is mixed with at least a portion of the fluid stream that flows out from the outlet of second row of conduits, thereby produce at least one kind of dilution fuel stream, its fuel index is between the first fuel exponential sum, the second fuel index;

Oxidizer source; And

The part of oxidant is flowed, maybe should dilute the method for at least a portion burning at least a in the fuel stream with this fuel stream or this fluid, thereby produce the gas that amount of nitrogen oxides reduces, it is with respect to using for the higher amount of nitrogen oxides that the method combustion fuel this fuel dilution device is produced that described nitrogen oxide reduces.

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