JPS61256106A - Method and device for burning fuel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for burning a mixture of fuel and air while suppressing the formation of nitrogen oxides, and to a burner device for carrying out the method.

Known combustion methods and burr pump devices are used for a wide variety of applications, such as heating process streams, generating steam, and drying materials. However, when the fuel is combusted, nitrogen oxides (NOx) can be produced which are pollutants if released into the atmosphere.

Various methods and burner devices for burning fuel-air mixtures while suppressing the formation of nitrogen oxides have been developed to meet environmental emission standards set by various public agencies. For example, the invention of U.S. Pat. No. 4,004,875 aims to provide a burner with low NOx generation, in which the fuel is first combusted in an area where there is only a sub-stoichiometric concentration of air; Thereby, the combustion zone following said zone is depleted of oxygen and a reducing atmosphere is created which suppresses the production of NOx.

Staged supply of fuel has also been used (see, e.g., U.S. Pat. No. 4,395,223), in which a portion of the fuel is delivered to the first stage where the required stoichiometric amount of parent air is supplied. area and the remaining part is burned in the second area. The presence of excess air in the first zone reduces the temperature of the combustion reaction and suppresses NOx production. The fuel reacts in the second zone with excess oxygen from the first zone mixed with surrounding combustion gases, which oxygen lowers the combustion reaction temperature and inhibits NOx formation in the second zone. do.

Such known staged combustion methods require sophisticated burner equipment, which includes multiple fuel nozzles and/or complex distribution systems for air or recirculated gas, making the equipment expensive to install and operate. including.

The method of combustion of a fuel-air mixture provided by the present invention includes a first method for ejecting a first portion of fuel from each of the one or more said nozzles through one or more first holes in said nozzles. a second step of discharging a second portion of fuel from each of the one or more nozzles through one or more second holes in the nozzles;
a third step of discharging fuel from each of the plurality of nozzles through one or more third holes, whereby the first step causes the fuel to mix with air, thereby creating an ignition zone in the vicinity of the nozzle. and the second step distributes a second portion of the fuel in a turbulent manner, so that the fuel mixes with an amount of air in excess of that required for the stoichiometric combustion of the fuel, The fuel is combusted in the combustion zone and further distributed by the third step into the primary combustion zone and downstream of the combustion zone, mixed with air from the primary combustion zone enriched with combustion products, and is Burns in a secondary combustion zone substantially protected from direct contact with incoming air.

Such a method can suppress the formation of nitrogen oxides more easily and cheaply than with prior art methods.

The invention also includes one or more fuel nozzles disposed within the chamber and a plurality of air intakes for admitting air into the chamber, the air being mixed with the fuel to form a resulting fuel-air mixture. There is also provided a burner device for combustion of a fuel-air mixture for igniting and combusting the mixture, wherein the one or more nozzles are each configured to discharge a first portion of fuel. one or more ignition holes provided and one provided for discharging a second portion of the fuel;
one or more primary combustion holes, and one or more secondary combustion holes provided inside the primary combustion hole of each of the one or more nozzles to discharge other portions of the fuel, The discharge from the ignition hole causes the fuel to mix with air;
This results in an ignition zone in the vicinity of the nozzle, and the second part of the fuel is distributed in a turbulent manner by discharge from the primary combustion hole, so that the amount of fuel exceeds that required for stoichiometric combustion of the fuel. The fuel is mixed with air in the primary combustion zone and combusted in the primary combustion zone, and by the release from the secondary combustion, the fuel is distributed within the primary combustion zone and downstream of the combustion zone, and the primary combustion zone is divided by combustion products. and combusts in a secondary combustion zone that is substantially isolated from direct contact with the incoming air by the primary combustion zone.

In order that the invention may be better understood, the invention will now be described in detail with reference to the accompanying drawings, by way of example only.

The burner drawing 10 shown in FIGS. 1 and 2 is a wall 12 of the furnace chamber.
The apparatus 10 is designed for use in the combustion of gaseous fuels such as hydrocarbon gases.

Apparatus 10 includes opening 14 with a plurality of bolt members 18.
a housing constituted by an externally mounted cylindrical outer housing member 16 and a housing 7 lining the wall 12;
A member 20 made of a heat-resistant fire-resistant material is installed in a frontage provided in a heat-insulating layer 22 made of a human-resistant material. The member 20 may include the furnace chamber wall 12 and/or the refractory material 2 as shown.
2 or alternatively to a cylindrical housing member 16 as appropriate.

The housing member 16 serves as an air conditioning unit and for this purpose includes a plurality of air intakes 26 spaced apart from each other around the periphery. A cylindrical damper 28 with a wall 24 extending from the end of the housing member 16 and a plurality of air inlets (not shown) complementary to the air inlets 26 of the housing member 16 is attached to the housing. It is rotatably arranged to cover the member 16.

The damper 28 is moved by the handle 30 to a position where the air inlet 26 is closed by the body of the damper 28, and the air inlet of the damper 28 is aligned with the air inlet 26, as shown in FIG. can be rotated between positions.

A guide tube 32 is disposed within the housing member 16 coaxially with the housing member 16, the outer end of the guide tube 32 being connected to the wall 2.
4, for example by welding, and a protective cone 34 is attached to its inner end. A fuel supply conduit 36 extends through the guide tube 32 and has a fuel discharge nozzle 38 at its inner end.
is installed. The outer end of the conduit 36 is threaded for connection to a fuel source, and the conduit 36 is tightly attached to a plate 39 which is removably attached to the wall 24 by bolt members 40.

A pilot 42 is coupled to a supply conduit 44 extending through an opening provided in the wall 24 to which an opening member 46 is removably attached.

The outer end of supply conduit 44 is coupled to a pilot fuel-air mixer 48 configured to couple with a source of pilot fuel.

3 and 4 show that the protective cone 34 is dish-shaped and includes a plurality of openings 50 that allow a limited amount of air to pass through. Protective cone 34 functions to create a protected area near nozzle 38 as incoming air flows in the direction indicated by arrow 52 in FIG. Of course, creating a protected area in the vicinity of the nozzle 38 can also be achieved with various types and shapes of devices other than the protective cone 34.

Nozzle 38 extends through the central opening of protective cone 34 and has a first set of one or more holes 56 in its hemispherical end wall 54 . When two or more holes 56 are provided,
The holes 56 preferably all have the same diameter and are preferably aligned with the nozzle 38 in a plane perpendicular to the axis of the nozzle 38, i.e. at an angle of 90°, indicated by the symbol C in FIG.
Spaced evenly around the perimeter.

The axis of the nozzle 38 is parallel to the axis of the housing member 16, so the axis of the hole 56 is parallel to the axis of the housing member 16.
6 is located in a plane substantially perpendicular to the direction of inflow of the airflow passing through it. The first set of holes 56 discharge a first portion of the fuel supplied to the nozzle 38, and the discharged first fuel portion mixes with a portion of the incoming air, thereby causing the C-nozzle 38 to be An ignition zone appears.

A second set of one or more holes 58 is also provided in the wall portion 54 of the nozzle 38 . If more than one hole 58 is provided, the holes 58 preferably all have the same dimensions and are equally spaced around the wall 54 inboard of and above the ignition hole 56. Ru.

The axes of the holes 58 are preferably inclined at the same angle b (FIG. 3) relative to the direction of air inflow, and the angle b is preferably between 15 and 70''. A second portion of the fuel supplied to the nozzle 38 is discharged, said second portion being agitated and distributed outwardly.

The wall portion 54 of the nozzle 38 further includes a third set of one or more holes 60 inboard of and above the primary combustion holes 58.
It is equipped with Again, when two or more holes 60 are provided, the holes 60 preferably all have the same dimensions and are spaced apart from each other on the circumference of the nozzle 38 . The axis of the hole 60 may be parallel to the axis of the nozzle 38 as well as to the direction of air inflow 52, or alternatively, as shown in FIG. good.

It should be noted that angle a can be determined to be approximately equal to or even smaller than angle s, but must not exceed angle s.

The holes 60 discharge the remaining portion of the fuel supplied to the nozzle 38 such that substantially all of said remaining portion is in the primary space created by the ejection of the second portion of fuel from the holes 58. It burns within the combustion zone as well as in a secondary combustion zone located downstream of the combustion zone.

The method of functioning of the device according to the invention described above will now be explained with reference to FIG. Fuel is supplied to conduit 36 under pressure, typically from 0.2 to about 2 bar gauge.

Pilot fuel at a pressure of 0.2 to 1 bar gauge is supplied to an air mixer 48 where it is mixed with air and the resulting fuel-air mixture is discharged from the pilot 42 and ignited for combustion. The flame from pilot 42 serves to ignite the fuel expelled from nozzle 38. However, it should be noted that other ignition means may be used and the use of a pilot burner is optional.

The pressurized fuel supplied to the conduit 36 flows to the nozzle 3
8 and is discharged into the furnace chamber through holes 56, 58 and 60 provided in the nozzle 38. The ignition hole 56 is connected to this hole 5.
The first portion of fuel discharged from nozzle 6 is sized and/or numbered such that the first portion of fuel discharged from nozzle 38 is about 1% to about 25% of the total fuel discharged from nozzle 38.

Said first fuel portion discharged from the ignition hole 56 enters the ignition area 6 near the nozzle 38 protected by the cone 34.
At 2, it is mixed with air and ignited by a flame from a pilot 42 or other means and combusted.

The second set of holes, or primary combustion holes 58, are sized such that the second portion of the fuel ejected from the holes 58 is about 1% to about 60% of the total amount of fuel ejected from the nozzle 38. and/or formed into a number. A second portion of the fuel is distributed in a turbulent manner as it spreads outwardly from the nozzle 38, so that the fuel mixes with the air entering the housing of the burner 10 through the air inlet 26 of the housing member 16. By adjusting the position of a damper 28 disposed over the housing member 16, the total amount of air is directed to the nozzle 3.
The amount of air is adjusted to be substantially equal to or greater than the amount of air required for stoichiometric combustion of the total amount of fuel released from the air. The mixture of the second portion of fuel and air produced is directed outwardly from the nozzle 38 into the primary combustion zone 6.
Burns at 4. As the second portion of the fuel mixes with air in excess of the amount required for stoichiometric combustion of the fuel, the temperature of the primary combustion zone 64 is reduced and the formation of NOx in the primary combustion zone 64 is suppressed. Ru.

The remaining portion of the fuel supplied to nozzle 38 is
It is discharged from a third set of holes provided at 8, namely secondary combustion holes 60. A portion of the fuel discharged from the holes 60 enters the primary combustion zone 64 as well as the secondary combustion zone 6 downstream of the combustion zone 64.
6, and this secondary combustion zone 66 is divided into the primary combustion zone 6
4, it is substantially protected from direct contact with incoming air. In the secondary combustion zone 66, the fuel is transferred to the primary combustion zone 6.
4, which is diluted with combustion products from primary combustion zone 64.

The fuel portion released from the secondary combustion hole 60 is the primary combustion area 6
4 and a secondary combustion zone 66 located downstream of the combustion zone 64.
Because the combustion occurs at a relatively low temperature, and because the air that mixes with the fuel portion is diluted with combustion products, combustion is achieved at relatively low temperatures, thus suppressing the formation of NOx.

When using the method of the present invention, combustion in the primary combustion zone is realized in excess air, so that the temperature of the flame in the combustion zone is reduced;
This suppresses the generation of NO and X. Combustion in the secondary combustion zone is delayed because the combustion zone is prevented from direct contact with the incoming air by the primary combustion zone. This delay, or delay in the mixing of fuel and air, allows the air to be diluted with combustion products from the primary combustion zone as well as the combustion chamber, resulting in a lower combustion temperature and a lower combustion temperature in the secondary combustion zone. NOx production is suppressed.

Although the present invention has been described herein as relating to a natural draft burner arrangement, the present invention may be applied to a wide variety of burner designs including the use of forced draft. A fuel discharge nozzle according to the present invention may also be described, for example, in U.S. Pat.
Multiple burner devices may be used in one burner device, such as that disclosed in US Pat. No. 3,273. Additionally, both the fuel discharge nozzle and the protective cone may take on a variety of other forms and shapes that fulfill the functions defined above.

To aid in a clear understanding of the method and apparatus of the present invention,
The following example is presented.

1 Emperor 1 A burner V41110 designed to generate 1756.8 - of the heat by burning natural gas with a calorific value of 9.615 k14·hr/rIt is operated toward the inside of the furnace chamber. The nozzle 38 has six holes 56 each having a diameter of 1.59° as a first set of holes and six holes 56 having a diameter of 3° as a second set of holes.
．． There are four holes 58 with a diameter of 57 m5+ and a third set of holes 60 with a diameter of 4.76 mra. Hole 56
．． The axes 58 and 60 have angles of 90', 40'' and 10@, respectively, with respect to the axis of nozzle 38.

Fuel is applied to nozzle 38 at a pressure of 1 s psig, approximately 185
It is supplied at the rate of 1/hr. The amount of the first fuel portion released from the ignition hole 56 is about 16.9 TIL/hr, and the amount of the second fuel portion released from the primary combustion hole 58 is about 56 TIL/hr.
．． 2 Td/hr, and the other fuel portion 61 released from the secondary combustion hole 60 is approximately 109.67 d/hr.

The discharged fuel is mixed with air and combusted in the burner device 10, thereby generating approximately 1756.8 mm of heat within the furnace chamber. The flue emissions from the furnace chamber contain concentrations of NOx below about 30 ppm. When a conventional burner with a conventional nozzle is operated under similar conditions and in a similar manner towards the interior of the furnace chamber, the NOx concentration in the fi-way effluent is once around 70 ppn+.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of one embodiment of the device according to the invention;
The figure is a plan view of the device shown in FIG. 1, FIG. 3 is an enlarged partial cross-sectional view of the part of the device shown in FIG. 1 including the fuel discharge nozzle, FIG. 4 is a plan view of the device part shown in FIG. 3, and FIG. 2 is a side sectional view showing how the burner device of FIG. 1 functions; FIG. 10...Burner device, 16...Housing member, 20...Refractory material member, 26...
... Air intake, 28 ... Damper, 32.
...Guide pipe, 34 ...Protection cone, 36
...Fuel supply conduit, 38...Fuel discharge nozzle, 42...Pilot, 48...
- Pilot fuel-air mixer, 50...opening, 54...end wall, 56.58.60...
... Hole, 62... Ignition area, 64...
・Primary combustion area, 66...Secondary combustion area. 〜・１・ 〜・２・

Claims (12)

[Claims] (1) discharging fuel from one or more nozzles disposed within a burner housing, mixing the fuel with air introduced into the housing, igniting the resulting mixture of fuel and air; a method for combusting a fuel-air mixture, the first step of discharging a first portion of fuel from each of the one or more nozzles through one or more first holes in the nozzles; and a second step of discharging a second portion of fuel from each of the one or more nozzles through one or more second holes in the nozzles, and a remaining portion of the fuel through one or more of the nozzles. a third step of discharging the fuel from each of the nozzles through one or more third holes, the first step causing the fuel to mix with air, thereby creating an ignition zone in the vicinity of the nozzles; The second step also distributes a second portion of the fuel in a turbulent manner;
As a result, the fuel is mixed with an amount of air in excess of that required for stoichiometric combustion of the fuel and combusted in the primary combustion zone; characterized by being distributed downstream and mixed with air from the primary combustion zone diluted with combustion products and combusted in a secondary combustion zone substantially protected from direct contact with incoming air by the primary combustion zone. combustion method. (2) The first portion of the fuel is ejected at a rate of 1 to 25% of the total amount of fuel ejected from each of the one or more nozzles. Method. (3) Claim 1 or 2, characterized in that the second portion of fuel is ejected at a rate of 1 to 60% of the total amount of fuel ejected from each of the one or more nozzles. The method described in section. (4) the total amount of air introduced into the burner housing is substantially equal to or greater than the amount of air required for stoichiometric combustion of the total amount of fuel discharged from the one or more nozzles; A method according to any one of claims 1 to 3, characterized in: (5) A second portion of fuel is distributed outwardly by said second holes, so that said primary combustion zone is funnel-shaped. The method described in any of the paragraphs. (6) one or more fuel nozzles disposed within a chamber and a plurality of air intakes for admitting air into the chamber, the air being mixed with fuel to ignite the resulting fuel-air mixture; , a burner device for combustion of a fuel-air mixture, wherein the one or more nozzles each include one or more ignition holes configured to eject a first portion of the fuel; one or more primary combustion holes provided to discharge a second portion of the fuel; and one or more primary combustion holes provided inside the primary combustion hole of each of the one or more nozzles to discharge the remaining portion of the fuel. The discharge from the ignition hole causes the fuel to mix with air, thereby creating an ignition area near the nozzle, and the discharge from the primary combustion hole causes the fuel to mix with air. The portions are distributed in a turbulent manner so that the fuel is mixed with an amount of air in excess of that required for the stoichiometric combustion of the fuel, burns in the primary combustion zone, and further discharges from the secondary combustion holes. The discharge distributes fuel within the primary combustion zone as well as downstream of the combustion zone;
A burner device characterized in that it is mixed with air from a primary combustion zone diluted with combustion products and combusted in a secondary combustion zone that is substantially isolated from direct contact with the incoming air by the primary combustion zone. (7) each of one or more nozzles and one of each of these nozzles;
7. The device of claim 6, further comprising means for creating a protected area in the vicinity of one or more ignition holes. (8) one or more ignition holes, wherein the flow rate of fuel passing through the ignition holes to form the first portion is 1 to 25% of the total flow rate of fuel discharged from each of the one or more nozzles; The device according to claim 6 or 7, characterized in that the device has a size such that: (9) The one or more primary combustion holes are configured such that the flow rate of fuel passing through the primary combustion holes to form the second portion of fuel is at least one of the first combustion holes.
1 of the total flow rate of fuel discharged from each of the or more nozzles
9. A device according to any one of claims 6 to 8, characterized in that it has a size of ~60%. (10) A device according to any one of claims 6 to 9, characterized in that the axis of the one or more ignition holes is substantially perpendicular to the axis of the nozzle. (11) The axis of one or more primary combustion holes is inclined at 15 to 70 degrees with respect to the axis of the nozzle, and the axis of one or more secondary combustion holes is parallel to the axis of the nozzle. 11. Device according to any one of claims 6 to 10, characterized in that it is tilted at an angle of 1 to 30[deg.]. (12) Claims 6 to 11, characterized in that the portion with holes of one or more nozzles is hemispherical.
Apparatus according to any of paragraphs.