US3166621A

US3166621A - Burner tuyere arrangement for a blast furnace

Info

Publication number: US3166621A
Application number: US96171A
Authority: US
Inventors: John W Carlson
Original assignee: Colorado Fuel and Iron Corp
Current assignee: Colorado Fuel and Iron Corp
Priority date: 1961-03-16
Filing date: 1961-03-16
Publication date: 1965-01-19
Anticipated expiration: 1982-01-19

Description

Jan. 19, 1965 J. w. CARLSON 3,166,621

BURNER TUYERE ARRANGEMENT FORABLAST FURNACE Filed March 16. 1961 R% W OHM E T 0 TN .m f n o W IMW 00 United States Patent 3,166,621 BURNER TUYERE ARRANGEMENT FOR A BLAST FURNACE John W. Carlson, Pueblo, Colo., assignor' to The Coloratio Fuel and Iron Corporation, Denver, Colo., a corporation of Colorado Filed Mar. 16, 1961, Ser. No. 96,171 2 Claims. (Cl. 26641) This invention relates to blast furnace operations, and has for its object the provision of an improved combustion process for heating the. charge and effecting the reduction of the iron ore. The invention aims to eliminate at least a substantial, portion of the coke customarily used and to efiect the heating and conversion reactions with hydrocarbon. liquids and natural gas.

For many years suggestions have been made in the literature to use natural gas, other hydrocarbon gases and various petroleum products in the blast furnace either as a substitute for, or as a supplement to, the use of coke. The available hydrocarbon gases such as natural gas (methane) are so high in hydrogen that they lack the requisite thermal capacity and the water formed as a product of the reactions isobjectionable.

The petroleum liquids such as crude petroleum or distillation residues such as bunker-C are difiicult to handle in burners or tuyeres because they decompose in the burners and plug the orifices with carbon deposits.

As a result of considerable. experimentation with the use of these fluids I discovered a simple and practical process for burning an effective mixture of a heavy high carbon material such as bunker-C distillation residue and methane gas. In accordance with the process of my invention I bring together in a single nozzle the liquid hydrocarbon and natural gas and charge them as a mixture into a combustion-supporting air stream and direct the resulting high-temperature flame through the tuyeres of the blast furnace. In a preferred and advantageous adaptation of my process I discharge the liquid petroleum fuel into a surrounding stream of natural gas and accomplish not only dispersion of the liquid in the gas, but form an envelope of gas surrounding the pipe carrying the liquid which prevents over-heating of the liquid in the pipe and the deposition of carbon. I prefer to .carry the liquid through a relatively small pipe mounted within a larger gas pipe and to have their discharge openings at about the same place so that these fluids, released under pressure, become intermixed preferably just in advance of the point of combustion and are directed into the axis of the air stream.

This dispersion of the heavy oil in the gas results in a better mixing with the air and better combustion. The most important benefit is in the supply to a blast furnace of an effective blend of a liquid fuel having a high ratio of carbon to hydrogen and hence high heat capacity with the methane gas of lower heat capacity.

The invention provides a practical means of utilizing in a blast furnace a mixture of the cheap and burdensome bunker-C oil and the cheap natural gas as a substitute for the much more costly coke now widely used.

The invention provides also an improved burner including a nozzle for intermixing liquid and gaseous fuel, burning the mixture and directing the combustion products of the mixture into a blast furnace preferably through a tuyere. The burner includes means for charging the liquid and gas mixture into an air duct of a blast furnace tuyere. One feature of the improved burner is in the cooling of the nozzle through which the liquid fuel and gas are discharged to prevent carbon deposits. The nozzle preferably comprises a small tube for liquid fuel inside and surrounded by a much larger duct or pipe for gaseous fuel. The surrounding envelope of gas shields the small tube and prevents overheating and cracking of the liquid fuel with deposition of carbon. Another feature of the burner is the attachment of a bimetallic heatresponsive element to the burner and its connection to a signal device to, signal overheating of the burner.

These and other features of the invention will be better understood after considering the following discussion and accompanying drawings, in which I FIG. 1 is a side view, partly in section, of a burner of the invention installed in a blast furnace, and

FIG. 2 is a fragmentary enlargement of the burner of FIG. 1. I

The complete burner 1 of the invention illustrated in the drawings is mounted in the water cooled tuyere opening 2 in the wall 3 of a blast furnace. It is to be understood that each tuyere opening will have a similar burner. As illustrated, the burner is an adaptation of the usual tuyere system for blowing air into the blast furnace consisting of a tuyere 4 which has an annular space 5 for cooling water forced in through pipe '6 and out through pipe 7. The air duct 8, known as a blow pipe, is connected by the flanges 9 to the air supply pipe 10 which leads to the usual bustle pipetnot shown). The sighting device 11 is mounted in the pipe 10.

The fuel nozzle 15 comprises an outer pipe 16 for gas and a concentric smaller inner pipe 17 for liquid fuel. This nozzle is water cooled, advantageously by" mounting it in the water cooled tuyere 4 as shown. This may be done by welding, or by casting a copper tuyere 4 around a Monel metal or other alloy or copper pipe 16.

The nozzle pipe 16 is connected to the natural gas supply pipes 18 and 19. The pipe 18 has an attached packing gland 20 through which the liquid fuel supply pipe 21 passes and is either connected to, or is continuous with, the pipe 17. In an effective burner construction, the pipes 18 and 19 are preferably about in diameter and pipe 16 may be the same size or a little smaller. These pipes may be of steel or copper. The pipes 17 and 21 may be A" copper tubing. The gland 20 may be a pipe union having the copper tube 21 welded to the union half, as shown, to form a tight connection. It will be noted that the end of the nozzle 15 is so constructed that it projects into the space Within the tuyere 4 and in the air stream in such a manner that the mixture is directed into the center of the air stream. The pipe 17 preferably ends short of the end of pipe 16.

The aforementioned nozzle is effective for carrying out a preferred process of the invention. However, I may change the construction of the burner by eliminating the small tubes 17 and 21. With this burner I may introduce the liquid fuel through the pipe 19 and the gas fuel through the pipe 18 or I may reverse the order and introduce the liquid fuel through pipe 18 and the gas fuel through pipe 19, but in each case I effect intermixing of the fuels at place 24.

The bimetallic element 22 is preferably in the form of a band attached to the air pipe 8 and the electric wires 23 lead to a suitable temperature recording or signal device (not shown).

In carrying out a blast furnace combustion process of the invention with the burner illustrated, I prefer to use bunker-C distillation residue because of its high carbon content and low cost. However, I may use other liquid hydrocarbon fuels. When using bunker-C fuel it should be heated to decrease its viscosity and facilitate its flow and dispersion into the natural gas when it issues from pipe 17. I prefer to heat this liquid to a temperature of from 120 F. to 250 F. and to discharge it at a pressure varying from 30 to psi. The preferred ratio of bunker-C fuel to natural gas is from 0.5 to 4 pounds of bunker-C fuel per pound of natural gas.

The methane or natural gas is passed through pipes 19, 18 and 16 as an envelope surrounding pipe 17. This gas is preferably used at normal temperatures and under a preferred pressure of from 30 to 100 p.s.i. The liquid and gas impinge upon each other at the end of nozzle and this results in an effective dispersion and intermixing with the air in tuyere 4. The liquid oil is accordingly atomized and this results in eifective combustion. This heavy oil can be supplied to the burner over long periods without plugging the nozzle 15 because the surrounding layer of cooler natural gas in pipe 16 serves as a thermal barrier and prevents the heating of pipe 17 to a point where the oil is cracked with resulting carbon deposits which can plug the nozzle.

Changes in the furnace operation, which occur frequently, are noticed by visually observing the iron and slag and by analysis of furnace gas. If correction be necessary, it can be started immediately by varying the flow of gas and liquid fuels through the nozzle and into the air stream and into the furnace hearth in but a few seconds or less. Not only can the amounts and proportions of gas and liquid fuel be varied, but also with respect to the other three control measures. Moreover, these can take effect immediately instead of the usual ten to sixteen hours required to change a coke charge and have it arrive in the hearth.

The gas and liquid fuel mixture can be used to replace all or a part of the coke presently used, and can be used in connection with charges including briquets of iron oxide fines and carbon or coke, or when coal char or other forms of solid carbon fuel are used.

I claim:

1. A burner for a blast furnace comprising a tuyere formed as a unitary member having an inner air passage and a cooling jacket for cooling water, means for circulating cooling water in and through said cooling jacket, said cooling jacket having an inner wall defining the air passage and a rearward wall which closes the cooling jacket for cooling water, and a nozzle for burning liquid fuel comprising a pipe for the discharge of a cooling gas passing through the rearward wall and the inner wall of the cooling jacket and extending into the air passage, and a tube mounted inside the pipe for charging liquid fuel into the inner air passage.

2. A burner as defined in claim 1 in which the tuyere is formed as a unitary casting and the metal of the tuyere is cast over the pipe forming tight joints therewith.

References Cited by the Examiner UNITED STATES PATENTS 325,293 9/85 Weber 42 370,251 9/87 Field 26641 X 502,482 8/93 Dauber 26629 XR 966,704 8/06 Pickles 266-41 1,393,749 10/21 Carstens 266-41 1,718,732 6/29 Danforth 7-543 1,873,996 8/32 Cunningham 266-41 1,962,593 6/34 Henry 266--41 2,446,511 8/48 Kerry et al. 26641 2,582,615 1/52 Wolfe et al. 266-41 XR FOREIGN PATENTS 679,755 8/39 Germany.

MORRIS O. WOLK, Primary Examiner.

MARCUS U. LYONS, DAVID L. RECK, JAMES H.

TAYMAN, JR., Examiners.

Claims

1. A BURNER FOR A BLAST FURNACE COMPRISING A TUYERE FORMED AS A UNITARY MEMBER HAVING AN INNER AIR PASSAGE AND A COOLING JACKET FOR COOLING WATER, MEANS FOR CIRCULATING COOLING WATER IN AND THROUGH SAID COOLING JACKET, SAID COOLING JACKET HAVING AN INNER WALL DEFINING THE AIR PASSAGE AND A REARWIND WALL WHICH CLOSES THE COOLING JACKET FOR COOLING WATER, AND A NOZZLE FOR BURNING LIQUID FUEL COMPRISING A PIPE FOR THE DISCHARGE OF A COOLING GAS PASSING THROUGH THE REARWARD WALL AND THE INNER WALL OF THE COOLING JACKET AND EXTENDING INTO THE AIR PASSAGE, AND A TUBE MOUNTED INSIDE THE PIPE FOR CHARGING LIQUID FUEL INTO THE INNER AIR PASSAGE.