JPS638367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for treating factory tail gases (exhaust gases), and in particular to generating reducing gases by burning fuel in an oxygen-limited atmosphere. The present invention relates to a heating device for mixing the reducing gas with factory exhaust gas.

For example, US Pat. No. 3,752,877 discloses a method for reducing compounds such as sulfur oxides and nitrogen oxides present in industrial exhaust gases such as tail gas from Claus plants and the like. According to that method, the tail gas is first heated to a high temperature by means of a conventional burner via a heat exchanger that prevents mixing of the tail gas and the combustion products. After heating, the tail gas is mixed with a reducing gas containing hydrogen and carbon monoxide. This reducing gas is produced by burning air and fuel in a substoichiometric combustion reaction in the presence of steam. When hydrocarbons are combusted stoichiometrically or substoichiometrically, it is difficult to avoid the formation of free carbon, or soot, which is detrimental to subsequent processing steps. It is also difficult to ensure that the undesirable free oxygen contained in the reducing gas is completely consumed by combustion.

The present invention provides a novel method and apparatus for generating a reducing gas, simultaneously preheating a factory exhaust gas using the heat generated by the production of the reducing gas, and then mixing the factory exhaust gas with the reducing gas. I will provide a. Conventionally, there is a problem in that the high operating temperatures within the reducing gas generator exceed the operating temperatures of normal metals and must be cooled. The present invention increases efficiency by utilizing factory exhaust gas as a coolant for the walls of the combustion chamber. Briefly, the device of the invention preferably has a length to diameter ratio of 2:1. It consists of an elongated metal cylinder lined with refractory material and an outer cylinder concentrically surrounding the cylinder and defining an annular passage therebetween for passage of factory exhaust gases.

At the end of the combustion chamber, a heat dissipating end wall is provided, which end wall is provided with an exit orifice of up to about 50% of its cross-sectional area. Fuel gas, preferably premixed with steam, is injected into the combustion chamber through a burner ring having a large number of injection holes. Air or oxygen is introduced into the combustion zone through a wind box located after the combustion section. Oxygen source (usually air) to the combustion zone
is introduced tangentially to form a vortex within the combustion chamber. A narrow throat at the entrance to the combustion chamber imparts a relatively high rotational speed to the airflow. This constriction throat is preferably configured to double the gas flow rate within the windbox, which is in the range of about 50-150 ft/sec. The combustion products are mixed with the plant exhaust gas after passing through the flame exit orifice.

Referring to the drawings, a combustion and mixing device 10 is shown having an inner metal cylinder 12 having a refractory lining 14. The cylinder 12 is provided with a metal wall 18 having an opening 20 inside the cylinder 12 that forms a combustion chamber 16, and the metal wall is also lined with a refractory material 22 surrounding the opening 20.
A constricted throat is formed at the inlet end of the tube. The other end 24 of the combustion chamber 16 is formed of a refractory material having an outlet opening 26 therethrough. Outlet opening 26 forms a flame exit orifice.

An annular burner or burner ring 28 is disposed around the outside of the opening 20 in the metal wall 18. As clearly shown in FIG. 5, the burner ring 28 is formed of a hollow pipe having a plurality of equally spaced holes 30 on its inner periphery for injecting fuel gas into the combustion chamber. A fuel inlet pipe 32 is connected to the burner 28 and connected to the metal cylinder 12 via a right-angled elbow 34.
Penetrate the side wall and extend to the outside. pipe 32
connects to a gaseous or liquid fuel source via a T-joint 36. As the fuel source, natural gas, hydrocarbons such as methane, fuel gases containing hydrogen, carbon monoxide, or mixtures thereof, liquid hydrocarbons, etc. are used.
T-joint 36 also connects to a steam source, thus mixing the steam and fuel and allowing the mixture to be injected through burner 28 and into the combustion chamber.

A flange 38 is provided at the inlet end of the metal cylinder 12 to which an end plate 40 is secured by bolts or other means. The space within the cylinder 12 between the end plate 40 and the interior wall 18 defines a wind box 42 into which a source of air, oxygen, or other oxygen-containing gas is introduced via a pipe 44. Connect. As clearly shown in FIG.
It is eccentrically arranged in the connection direction with respect to the side wall of No. 2. Thus, the air flow from pipe 44 imparts rotational motion to the air within wind box 42 .

Air from the wind box enters the combustion chamber 1 through the opening 20.
6 and the burner ring 28 inside the opening 20.
Mix with fuel and steam from. This mixture is ignited by any suitable means such as a pilot flame, electric spark, or the like.

Air is introduced through the pipe 44 at a rate of 50 to 150 ft/sec to create high turbulence within the throat zone 48 formed by the openings through the refractory material 22, thereby causing air to flow inside the wind box 42. and an even higher velocity within the throat 48, preferably from about 100 to about 300 ft/sec, or twice the airflow velocity within the wind box.
The constriction formed by the throat 48 is the narrowing of the combustion chamber 1
It is preferable to make the diameter smaller than 1/2 of the diameter of 6.

The combustion chamber 16 is provided with a cylindrical shell or jacket 50 to provide cooling to the combustion chamber 16 and preheat the plant exhaust or tail gas. The jacket 50 is supported by an end ring 52 surrounding and welded to the cylinder 12 in the same plane as the interior wall 18. Jacket 50 is provided with an annular flange 54 which is secured to end ring 52 by bolts or other means.

The outer jacket 50 extends a considerable length beyond the orificed refractory end wall 24 of the combustion chamber 16 and terminates in the end wall 56. The end wall 56 has a jacket 5
0 by welding or other means. The cross-sectional area of the orifice 26 is sized to a maximum of about 1/2 the area of the end wall 24 to maximize back radiation of heat without interfering with the flow of combustion gases. Factory exhaust gas is introduced into pipe segment 58.
and into the annular space between the cylinder 12 and the jacket 50 of the combustion chamber 16. As best seen in FIG. 4, the axis of pipe segment 58 is offset from the axis of rotation of cylinder 12 and jacket 50; A series of baffles 60, 62, 64 are disposed in close proximity to direct the factory exhaust gases tangentially to the cylinder 12. Thus, the combustion chamber 16
imparts a rotational motion component to the flow of factory exhaust gases along the outer surface of the

As the factory exhaust gases leave the outer surface of the combustion chamber in the longitudinal direction, they enter the region between the end of the combustion chamber and the end wall 56 where they meet the products of combustion that emerge from the combustion chamber through the flame exit orifice 26. Mix. This mixture is then passed through the outlet orifice 66.
derived through. Since the gases (combustion products) from the combustion chamber enter the mixing zone at a relatively high temperature,
Outlet 66 and jacket 50 are lined with a layer of refractory material 68. This layer of refractory material also serves to radiate heat back into the combustion chamber 16. The refractory material 68 of the jacket 50 is retracted rearward to a point where the temperature of the jacket is maintained at a safe level by the cooling effect of the factory exhaust gases flowing in the annular space between the jacket and the cylindrical wall 12. It has been extended (towards the left in Figure 3).

In operation, it has been found that adding steam to the fuel gas results in substantially soot-free combustion. Steam mixed with hydrocarbon gas (fuel) has the effect of reducing the thermal reactions or cracking processes that liberate carbon from hydrocarbon molecules. Even if some cracking of the hydrocarbons occurs within the combustion chamber, the intimate mixture of water molecules enhances the reaction of the liberated carbon with oxygen to form carbon monoxide and carbon dioxide. Typically, up to about 5 pounds of steam are mixed per pound of fuel.

According to the present invention, an end wall 24 made of refractory material is provided to create a large turbulent flow for better mixing of fuel gas and air, a high temperature in the combustion chamber, and to re-radiate energy into the combustion chamber. This, in combination with the addition of steam to the fuel gas, causes more complete oxidation, thereby removing all free oxygen from the reducing gas produced by combustion. Preferably, the combustion chamber has a length to diameter ratio of about 2:1 so as to have a volume corresponding to a gas residence time of 0.1 to 1 second. If the fuel gas contains 10% or more propane and relatively heavy hydrocarbon molecules, it is preferred that the gas residence time be 0.5 seconds. In the case of propane or a fuel gas that is relatively low in heavy components, the fuel gas only needs to be premixed with a small amount of steam. For example, it is preferred to mix about 1 pound of steam to 1 pound of fuel. For fuel gases or liquid fuels with relatively heavy components, the steam rate can be increased to 5 pounds of steam per pound of fuel. If liquid fuel is used, a steam atomizing spray nozzle can be used instead of a burner ring as a means for injecting the fuel into the combustion chamber.

Although the combustion process has been described above as producing reducing gas, this same device can be used where neutral gas is required. Whether reducing gas or neutral gas is obtained is determined by
Needless to say, it depends on the amount of oxygen supplied to the fuel gas.

[Brief explanation of the drawing]

1 is a side elevational view of the apparatus of the present invention; FIG. 2 is an end view of the apparatus; FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 2; and FIG. FIG. 5 is a partial cross-sectional view taken along line 4--4 of FIG. In the drawings, main symbols are as follows. 1
0: Combustion and mixing device, 12: Inner cylinder, 1
4: Lining, 16: Combustion chamber, 18: Internal metal wall,
20: Opening, narrow throat, 22: Refractory material, 24: End wall, 26: Exit opening, flame exit orifice, 2
8: Burner, 42: Wind box, 44: Air introduction pipe, 48: Throat band, 50: Jacket, 56: End wall, 58: Pipe segment, 60, 62, 64: Reversing plate, 66: Outlet pipe, 68: Fireproof material.

Claims (1)

[Scope of Claims] 1. A combustion and mixing device for generating molecular oxygen and soot-free hot gas by burning hydrocarbon fuel and mixing the hot gas with factory exhaust gas, comprising: A cylindrical combustion chamber having a surface is provided,
An elongated inlet opening forming a throat is provided at one end of the combustion chamber, and an outlet opening is formed in the other end wall of the chamber in axial alignment with the inlet opening; a refractory surface forming part of a radiating surface, the inlet opening and the outlet opening both having a cross-sectional area less than the cross-sectional area of the combustion chamber, coaxially surrounding the outlet end wall; A cylindrical jacket having a second planar radiant refractory end surface facing the outlet opening of the combustion chamber is provided, a portion of the jacket surrounding the cylindrical portion of the combustion chamber to form an annular portion therebetween. a mixing zone by forming a passageway and extending the jacket beyond the outlet end wall of the combustion chamber, and a windbox for introducing oxygen-containing gas surrounding said inlet opening of the combustion chamber. The oxygen-containing gas is arranged so as to be wrapped around the throat, and the oxygen-containing gas is directed into the wind box in a tangential direction to the axis of the combustion chamber so that the gas passes through the throat while rotating. means for introducing an oxygen-containing gas for guiding the fuel to form a plurality of jets of fuel and steam directed into the combustion chamber through the throat, with the oxygen-containing gas passing in a rotational motion through the throat; - A steam injection means is disposed at the throat, and a factory exhaust gas inlet for introducing factory exhaust gas into the jacket is connected to the annular passage, so that the factory exhaust gas and combustion from the combustion chamber are A combustion and mixing device characterized in that an outlet for discharging the products is formed in the jacket near the second radiating end surface. 2. In the device according to claim 1,
The oxygen-containing gas introducing means for introducing the oxygen-containing gas into the wind box is arranged in the throat.
A combustion and mixing device characterized in that it creates a gas flow with a rotational speed of 100 to 300 ft/sec. 3. In the device according to claim 2,
Combustion and mixing device, characterized in that the throat is configured to at least double the rotational speed of the gas flow in the wind box. 4. In the device according to claim 1,
The means for forming a jet of fuel includes an annular tube extending around the inlet opening forming the throat of the combustion chamber and disposed within the windbox, the annular tube comprising:
A combustion and mixing device characterized in that it is provided with a plurality of holes for injecting fuel and steam into the throat. 5. In the device according to claim 4,
A combustion and mixing device characterized in that a fuel/steam introduction means is provided for introducing a premixed mixture of steam and fuel into the annular tube. 6. In the device according to claim 1,
The factory exhaust gas inlet is extended in a tangential direction to the cylindrical jacket so that the factory exhaust gas flows circumferentially within the annular passage between the combustion chamber and the jacket. A combustion and mixing device characterized by: 7. In the device according to claim 1,
A combustion and mixing device characterized in that the cross-sectional area of the outlet opening of the other end wall of the cylindrical combustion chamber is up to 50% of the cross-sectional area of the combustion chamber. 8 In a heating device used for recovery of factory exhaust gas, etc., for heating the factory exhaust gas by mixing it with molecular oxygen formed by combustion of hydrocarbon fuel and soot-free combustion gas, an elongated cylindrical combustion chamber having a refractory surface, an inlet opening forming an elongated throat at one end of the chamber, and a planar shape forming part of the inner refractory surface at the other end of the chamber; An outlet opening is provided in the wall, the inlet opening and the outlet opening each having a cross-sectional area of 50% of the axial cross-sectional area of the combustion chamber, and a plurality of jets of fuel and steam are provided into the inlet opening of the combustion chamber. a fuel/steam injection means for introducing the oxygen-containing gas; an oxygen-containing gas introducing means for introducing a flow of oxygen-containing gas through the inlet opening; The introducing means is configured to impart a rotational motion component to the oxygen-containing gas flow to generate a vortex flow within the combustion chamber, and surrounds the combustion chamber to form an annular passage between the combustion chamber and the oxygen-containing gas flow. and an annular chamber surrounding the outlet end of the combustion chamber to form a mixing zone, the annular chamber configured to present a planar refractory surface facing the outlet opening of the combustion chamber;
Means for introducing factory exhaust gas into the annular chamber in a direction transverse to the longitudinal axis of the combustion chamber is provided on one side of the annular chamber; A heating device characterized in that it is provided with means for extracting gas from a chamber. 9. In the device according to claim 8,
A heating device characterized in that a mixing means is provided for mixing steam with the fuel before introducing the fuel into the combustion chamber. 10 In a heating device used for recovery of factory exhaust gas, etc., for heating factory exhaust gas by mixing it with combustion product gas, which is formed by combustion of hydrocarbon fuel and is free of molecular oxygen, 2:1
an elongated combustion chamber having a length/diameter ratio of and having an inner refractory surface, a plane forming an inlet opening at one end of the combustion chamber and forming a portion of the inner refractory surface at the other end of the combustion chamber; An exit opening is provided in the shaped wall,
The inlet opening and the outlet opening both have a cross-sectional area smaller than the axial cross-sectional area of the combustion chamber, the inlet opening being configured to form a constricted throat, and the outlet opening being configured to form a narrow throat. formed by an end wall, and the cross-sectional area of the outlet opening is 50% of the cross-sectional area of the end wall.
and mix the hydrocarbon fuel with steam,
an annular fuel/steam injection means for introducing the oxygen-containing gas into the combustion chamber through a plurality of holes; an oxygen-containing gas introduction means for introducing a flow of oxygen-containing gas through the inlet opening; The introducing means is configured to impart a rotational motion component to the oxygen-containing gas stream to create a vortex flow within the combustion chamber by passing the gas stream tangentially to the inner surface of the combustion chamber; An annular chamber is provided that surrounds the combustion chamber to form an annular passage between the combustion chamber and the outlet end of the combustion chamber, and the annular chamber is configured to provide the first radiation of the combustion chamber. factory exhaust gas introduction means configured to present a second refractory surface parallel to and spaced from the end wall and for introducing factory exhaust gas into the annular chamber;
The introduction means is provided with a deflector for directing the factory exhaust gases on one side of the annular chamber in a direction transverse to the longitudinal axis of the combustion chamber, and near the outlet end of the combustion chamber the annular A heating device characterized by being provided with gas derivation means for deriving gas from a chamber.