US3366469A

US3366469A - Method and apparatus for injecting liquid fuels into the blast furnace

Info

Publication number: US3366469A
Application number: US391469A
Authority: US
Inventors: Kodama Koretaka; Ogata Toshimitsu; Nakamura Masami
Original assignee: Yawata Iron and Steel Co Ltd
Current assignee: Yawata Iron and Steel Co Ltd
Priority date: 1964-08-24
Filing date: 1964-08-24
Publication date: 1968-01-30
Anticipated expiration: 1985-01-30

Description

30, 1968 KORETAKA KODAMA ET AL 3,366,469

METHOD AND APPARATUS FOR INJECTING LIQUID FUELS INTO THE BLAST FURNACE 2 Sheets-Sheet 1 Filed Aug. 24, 1964 FIG. 3

INVENTORS KORETAKA KODAMA TOSHIMITSU OGATA MASAMI NAKAMU RA ATTORNEYS Jan. 30, 1968. KORETAKA KODAMA ET AL 3,366,469

A METHOD AND APPARATUS FOR INJECTING LIQUID FUELS INTO THE BLAST FURNACE Filed Aug. 24, 1964 2 Sheets-Sheet 2 F/67A F/G'..9

! IF i30 F/G7B T J 25 15 P24 l' o D A T INVENTOR KORETAKA KODAMA TOSHIMITSU OGATA MASAMI NAKAMURA ATTORNEYS United States Patent 3,366,469 METHOD AND APPARATUS FOR INJECT- ING LIQUID FUELS INTO THE BLAST FURNACE Koretaka Kodarna and Toshimitsu Ogata, Kitakyushu, and

Masami Nakamura, Munakata-gun, Fukuoka Prefecture, Japan, assignors to Yawata Iron & Steel Co., Ltd, Tokyo, Japan, a corporation of Japan Filed Aug. 24, 1964, Ser. No. 391,469 6 Ciaims. (CI. 75-42) ABSTRACT OF THE DISCLOSURE The present invention relates to the provision of a liquid fuel burner in the blast near the tuyere of a blast furnace at an angle to the direction of flow of the blast, and injecting a jet of liquid furnace fuel into the blast, said jet of fuel being rotated or swirled and atomized by a compressed gas and issuing from the rotation-injection part of the burner, which part is at an angle to the longitudinal axis of the burner and parallel to the direction of the blast, so that the liquid fuel is injected parallel to the direction of the blast.

This invention relates, in general, to a method and an apparatus for injecting liquid fuels into a blast furnace, and more particularly to a method and a burner for injecting liquid fuels such as heavy oils and creosote oil into the combustion zone of the blast furnace through a tuyere.

In seeking for higher efficiency in the blast furnace operation and in a reduction of the production cost of pig iron, extensive efforts have been made in the research and development of the blast furnace and its accessories and operation methods. From these efforts, a highly rated method for raising operation efliciencies of the blast furnace by a substantial reduction of the coke ratio has been developed, in which such inexpensive liquid fuels as heavy oils and creosote oil are injected, in great quantities, into the blast furnace at the tuyere. However, the step of this method covering the injection of great quantities of liquid fuels into the combustion zone of the blast furnace at the tuyere, is always accompanied by the following dilficulties: Incomplete combustion of the injected fuels is caused by limited space of the combustion zone the high velocity of the high temperature blast at the tuyere, etc. Such incomplete combustion lowers the temperature in the circumference of the tuyere thus making the fuels run off from the top of the furnace as free carbons, thereby causing troubles and complications with the dust collector and other parts of the furnace such as the slip of the shelf. As for the liquid fuels the combustion of such fuels involves the process of preheating-evaporationdecompositionand the combustion of carbon particles. Thus, said combustion requires a longer time than that of gases only. It is desirable that it should be carried out in as short a time as possible and in the limited space of the combustion zone.

In order to overcome these difiiculties and ensure complete combustion, the flames of the injected liquid fuels should be as short as possible, and combustion should take place at the proper places in the combustion zone. Also, the liquid fuels should be subjected to complete atomization before injection, in order to enlarge the total surface area of particles. Particles of the fuels should be distributed uniformly in the tuyere, thus raising the oxygen concentration of and around the particles and speeding up combustion.

This invention relates to a method and a burner satisfying the above requirements, according to which liquid facilities. As shown in 3,366,469 Patented Jan. 30, 1968 fuels can be injected into the blast furnace in greater quantities and in better condition for combustion than by conventional methods. Said improvement is made possible by the development of a burner having a special structure for atomizing fuels by air and by properly using said burner at the tuyere.

An object of this invention is to provide a burner which is capable of atomizing liquid fuels completely or pulverizing them to a minimum; maitaining the included angle of a cone-shaped jet from the burner about 30, and producing as short a flame as possible, thereby making possible the injection of great quantities of liquid fuels, particularly heavy oils.

Another object of this invention is to provide a method and an apparatus which are capable of injecting great quantities of liquid fuels into the blast furnace in good combustion condition, and which can be operated and controlled easily and removed for use on the spot.

The invention will now be described with reference to the accompanying drawings in which:

FIG. 1 shows a cross section view of a heavy oil burner cited as an embodiment of this invention;

FIG. 2 shows an enlargement of the air part of the burner of FIG. 1;

FIG. 3 shows an enlargement of the injection head of the burner of FIG. 1;

FIG. 4 shows the detail of injection head of FIG. 3;

FIG. 5 shows a cross section View of the injection part of FIG. 4 along the line A-A;

FIG. 6 shows an embodiment of the injection method by the burner of this invention;

FIG. 7A and FIG. 7B show a comparison between the burner of this invention and a conventional burner and the jets issuing therefrom;

FIG. 8 shows a cross sectional view conventional burners;

FIG. 9 shows another embodiment of the injection method by the burner of this invention; and

FIG. 10 shows another embodiment of FIG. 4.

Referring to FIG. 1 the burner comprises three parts: a fuel pipe 1 for transmitting under pressure such liquid fuels as heavy oils and creosote oil (in the embodiment hereof heavy oils were used); a gas pipe 2 for transthe injection part of the of a sample of the mitting compressed air for atomizing the heavy oils, and

an injection head 3 for atomizing the heavy oils by the whirling motion caused by the compressed air.

The above-mentioned air pipe 2 is sheathed in the heavy oil pipe 1. The heavy oil pipe 1 is branched into two, so that the ends of these branches are connected respectively with the atomizing air source and the heavy oil source.

In FIG. 1, the branch 6 is connected with the heavy oil source and the branch 6 is connected with the atomizing air source. As shown in FIG. 2, the air pipe 2 is connected with the air source through a screw coupling 8 which can be put on and off the heavy oil pipe 1; thus, replacement of burner shafts can be made without dif ficulty. At the end of the screw coupling 8 there is set the air valve 11. The number It) refers to the retention ring of the free flange 9 fixed on the burner shaft. In the present embodiment, a free flange was used. Such a flange is convenient to control direction of the tip orifice of the burner when engaging the burner to the furnace or other FIG. 3, the injection head is connected with the heavy oil pipe by the screw 7. Such connection, using a screw, is convenient in the replacement of this part which is always subject to damage caused by high temperatures. In the rotation chamber 12 of the injection head 3 there is, positioned in the rotation chamber for jetting the fuel and gas, respectively, in an eccentric direction with respect to the axis of said nozzle, at least one compressed air inlet 4 and at least one liquid fuel inlet 5 opening into said chamber. Said rotation injection chamber is round in cross-section and the fuel and gas inlets are tangential to the wall of the rotation chamber. The heavy oils atomized by the whirling motion are expelled from the burner through the tip orifice 13.

If a shaft 12" is mounted to project from the center of the wall 12' of the rotation chamber 12 (shown in FIG. this will produce a better issue of the jet of atomized heavy oil from the tip orifice 13, and also improve the rotation condition in the chamber 12.

In this invention, it is possible to build the tip of the burner so that the direction of a jet from the tip is slanting at a certain angle (a) from that of the axis of the burner. That the jet from the burner is directed slantwise at some angle, means that the burner itself may be engaged to the furnace or other facilities slantwise at that angle. However, too great an angle of the jet from the axis of the burner is undesirable, as such angle produces high flow-resistance, causing the energy of the jet of the atomized fuels to diminish.

By using the above device, the jet of the atomized heavy oils issuing from the injection head 3 is always set in the same direction as that of the blast from the tuyre. In case the burner is to be inserted into the tuyre other than slantwise the injection head 3 should be made without slant or with a slant to some other extent than mentioned herein. In any case, it is necessary to determine the angle of slant so as not to damage the tuyre by the injection of the atomized heavy oils.

The appropriate angle of the slant of the jet is about 20, and the angle used for this embodiment is 18.

The process of the atomization of the heavy oils in the injection head 3 will now be considered. Referring to FIG. 4 and FIG. 5, the rotation chamber 12 is partitioned from the heavy oil pipe by the wall 12', and the compressed gas inlet 4 opens into the rotation chamber 12 in a direction eccentric, preferably tangential, to the center of the chamber, whereby the compressed :air passing into the chamber and whirling at high velocity mixes with the heavy oils instantly, giving rotation to and atomizing the heavy oils and expelling jets of the atomized heavy oils from the tip orifice 13. As mentioned above and also below in an embodiment, the heavy oils are pulverized into very small particles by a small volume of compressed air due to the particular structure of the rotation chamber. Thus the oxygen concentration around the heavy oil particles and the combustion velocity are raised, and the included angle of the jet from the tip orifice 13 is narrowed and maintained at about 30 irrespective of the volumes of heavy oils used, thus making possible the combustion of heavy oils of great quantity in the limited space of the tuyre. Also, the flame is shortened considerably.

As compared with conventional burners, the burner of this invention is advantageous because the heavy oils of great quantity which are injected into the blast furnace turn into reforming gas without producing free carbons.

An embodiment of the burner of this invention on such a small scale as shown in FIG. 6, in comparison with a conventional burner is:

In FIG. 6-, 14 refers to the tuyre (outer diameter: 115 mm.) 15 the heavy oil burner; 16 the blast pipe; 17 the blast valve; 18 the heavy oil valve; 19 the compressed air valve; 20 the heavy oil pump; 21 the heavy oil heater; and 22 the blast fan.

Example Blast: Volume 32 m. /min.; pressure 0.2 kg./m. velocity at tuyre 6'5 m./min.

Heavy oil: L.S.C. heavy oil, temperature 90 C. (When using it, .it is convenient to heat it to this temperature.)

Burner of this invention: Outer diameter of tip 30 mm., diameter of the rotation chamber 20 mm., diameter of the inner portion of the tip orifice (13) 8 mm., angle at which it is inserted into the tuyre (a) 18, diameter of the outer portion 13a of the tip orifice (vessel) 10 mm. (The structure of the tip is shown in FIG. 4; the included angle of the jet therefrom is (a) 18 the volume of atomizing air is 0.3 m. /rnin.)

Conventional burner: Outer diameter of the tip 30 mm., diameter of the inner portion of the tip orifice 13' 4 mm., diameter of outer portion of the tip orifice (vessel) 7 mm.

(The structure of the tip is shown in FIG. 8; the angle at which it is inserted into the tuyere (a is 18.)

The results of applying heavy oils to both burners in respective volumes of 3 liters, 5 liters and 7 liters per min. are as follows:

The burner of this invention produced jets of such narrow angles as 30 for 3 liters, 35 for 5 liters and 30 for 7 liters, which means that there were no remarkable.

variations depending on the volumes of heavy oils; it also produced no irregular atomization even when a greater volume of heavy oils were used. (See FIG. 7A.) On the other hand, the conventional burner produced jets of such angles as 48 for 3 liters, 56 for 5 liters and 59 for 7 liters, the cone-shape of the jets being deformed and the flame distribution was not uniform.

As mentioned above, the burner of this invention is capable of producing jets of narrow angles and of carrying out complete atomization even when using heavy oils of great quantity due to a strong shelving force resultheavy oils do not contact the water cooling part of the tuyere. This makes it possible to carry out combustion of great quantities of heavy oils quickly in-the limitedspace of the tuyere.

It is anticipated that the large blast furnaces will be used for the productionof an increasing amount of pig iron per tuyere in the future, which will requiry heavy oils weighing more than 30 kg. for the production of one ton of pig iron. Conventional burners will hardly meet these requirements, but the burnerof this invention will bring them into realization.

The burner of this invention is capable of producing much smaller particles of heavy oils when a tip orifice having a smaller diameter is used, and also it can be used as a combination burner for heavy oils and coke oven gas or as a pulverized coal and oil burner.

The above-mentioned is one embodiment of the burner of this invention used for the injection of liquid fuels into the blast furnace, the process of which is illustrated in FIG. 6. FIG. 9 shows an example in which the burner of this invention was put into practice with the blast furnace. In this figure, 1 refers to the burner of this invention; 23 the heavy oil pipe; 24 the atomizing air pipe; 25 the ring-shaped pipe for high temperature blast; 26 the blast nozzle; and 27 the tuyere. The burner of this invention is so engaged to the blast furnace that only the tip of the burner is inserted, at an appropriate angle, into the tuyere or the nozzle 26 near the tuyere. Such place was chosen atfer taking into consideration the included angle of the jets and the place where the combustion of liquid fuels takes place. In such cases, it is taken for granted that the injection part of the injection head 3 is built slantwise at the same or an appropriate angle.

Liquid fuels which are economically available for the burner of this invention are heavy oils, creosote oil, etc. and their mixtures with pulverized coal. As for atomizing gases, there are available, in addition to compressed air, such gases as oxygen and steam and their mixtures. It is not necessary to water-cool the injection head 3 though it is at the top of the burner, but in such cases when the burner is applied at places of high temperature, the water-cooling system is not objectionable.

Although we have described our invention with a certain degree of particularity and one desirable example, it is understood that the present disclosure has been made only by Way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to Without departing from the spirit and the scope of the invention as hereinafter claimed.

What we claim is:

1. A burner for injecting a liquid fuel into the combustion zone of the blast furnace at a tuyere, which comprises a fuel pipe for carrying the liquid fuel, a gas pipe within the fuel pipe for carrying a compressed gas, and an injection head on the free end of the fuel pipe and having an end face of the injection head being at an angle perpendicular to the axis of said fuel pipe, said injection head having a rotation chamber therein and an injection nozzle extending through said end face on an axis perpendicular to said end face, said rotation chamber having at least one liquid fuel inlet opening into it from said fuel pipe and at least one compressed gas inlet coupled to said gas pipe, said inlets being p0- sitined in the rotation chamber for jetting the fuel and gas respectively in an eccentric direction with respect to the axis of said nozzle.

2. A burner as claimed in claim 1 wherein the rotation injection chamber is round in cross-section and the fuel and gas inlets tangential to the wall of the rotation chamber.

3. A burner as claimed in claim 1 wherein the I0- tation chamber has a projection at the center thereof projecting from the back of the chamber toward the nozzle and aligned with said nozzle.

4. A method of injecting a liquid fuel into the combustion zone of a blast furnace at a tuyere, which comprises supplying a stream of liquid fuel and a stream of gas to the tuyere, mixing the stream of gas and liquid fuel by swirling the streams in a plane which is at an angle perpendicular to the direction of flow of the streams to the mixing zone, and then ejecting the mixed gas and liquid fuel through a nozzle extending substantially perpendicularly to the plane of rotation along the axis of the tuyere into the blast furnace.

5. A method as claimed in claim 4 in which the liquid fuel is at least one fuel taken from the group consisting of heavy oils, creosote oil, tars, and mixtures thereof.

6. A method as claimed in claim 4 in which the gas is a compressed gas taken from the group consisting of air, oxygen, steam, and mixtures thereof.

References Cited UNITED STATES PATENTS 325,293 9/1885 Weber 42 434,706 8/ 1890 Eckert 75-42 1,393,749 10/1921 Carstens 26629 X 1,433,255 10/1922 Binks 15873 2,044,720 6/1936 Fletcher 239--399 HYLAND BIZOT, Primary Examiner. DAVID L. RECK, Examiner.

H. W. TARRING, Assistant Examiner.