US3235182A

US3235182A - Apparatus for thermally working minerals

Info

Publication number: US3235182A
Application number: US310598A
Authority: US
Inventors: John W Ross; Donald R Boynton; Frederick R Gallus
Original assignee: Union Carbide Canada Ltd
Current assignee: Union Carbide Canada Ltd
Priority date: 1963-09-23
Filing date: 1963-09-23
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15
Also published as: NO118544B; BE653463A; GB1010407A

Description

J. W. ROSS ETAL APPARATUS FOR THERMALLY WORKING MINERALS Filed Sept. 25, 1963 INVENTORS n70/79V M 055 l Arran/5y A d; A.

VI ummm;

Q\ m\\ RS NL MISS VGRIGNG This invention relates to apparatus for thcrmaliy working minerals and more particularly to apparatus for removing rock with a high thrust, high-temperature llame produced by the combustion of a liquid hydrocarbon and compressed air.

Conventional apparatus for producing7 jet flames for thermally working minerals utilize pure oxygen and liquid hydrocarbon fuels to produce the high temperature, high velocity llame. Such conventional apparatus is not capable of being utilized with air as the oxidant.

Accordingly, it is the main object of this invention to provide an apparatus for thermally working minerals which can be operated with a liquid hydrocarbon and air.

Other objects are to provide a jet burner which will operate stably on air and liquid fuel over a wide range of air fuel ratios; to provide apparatus which can be easily and reliably ignited; to provide a burner which can be used with a closed circuit water cooling system; to provide a device for producing low cost heat energy for chambering mechanically drilled or jet pierced blastholes.

These and other objects will `become apparent from the following description and drawings in which:

FIGURE l is a broken cross-sectional view of the apparatus of the invention;

FIGURE 2 is a section taken along the line 2-2 of FIGURE l;

FIGURE 3 is a section taken along the line 3 3 of FGURE l; and

FIGURE 4 is a partial cross-sectional view of an alternative fuel atomizer. i

Generally, the above objects are achieved by apparatus comprising a blowpipe for thermally working minerals and mineral like materials with a high velocity jet flame produced by the combustion of air and a liquid hydrocarbon comprising a casing member; a cylindrical combustion chamber made of refractory metal located in said case and having an upstream end and a downstream end; a back plate forming a closure for the upstream end of said chamber; a liquid fuel atomizer carried on said back plate for introducing atomized fuel into said chamber; rearwardly directed clusters of air metering ports located in each quadrant around the circumference of the chamber at a first section immediately downstream from said back plate; additional rearwardly directed air metering ports located in each quadrant around the circumference of said chamber at several other sections,` each section being further downstream than the previous section and liquid fuel and air conduit means in said casing for supplyfuel to said atomizer and air to said combustion charnber.

For purposes of this disclosure the word section means a plane taken perpendicularly to the longitudinal axis of the combustion chamber.

Oxygen-fuel flames have been used for many years for piercing and/or removing minerals such as rock. It has been discovered that air can be substituted for the oxygen, especially on the so-called good spalling rocks, with rock removal rates similar to those obtained with oxygen.

The advantages of an air fuel jet burner obviously rests in the elimination of large volumes of high pressure, high purity oxygen required by present apparatus. Oxygen being relatively expensive tends to offset the advantages of higher drilling speeds. In addition, the production and/ or storage of large quantities of oxygen at the drilling site is not always feasible. The present compressed air-fuel burner provides a tool which greatly improves the economics of conventional thermal rock working.

The design of a burner which will operate successfully on air and heavy liquid fuels such as, for example, diesel oil or bunker C over a wide range of air fuel ratios, is not a mere matter of substitution in conventional oxygen burners. It was discovered that in order to ignite and maintain an air-liquid fuel flame in a stable condition the manner of introduction of the air into the combustion chamber is critical. v

It is important with air-fuel burners to attain the maximum possible flame temperature. This necessitates the use of straight bore exit nozzles rather than the conventional DeLaval nozzle used in the oxygen-fuel burner.

It also requires a refractory metal combustion chamber to conserve heat energy in the combustion zone and promote good fuel combustion. This combustion chamber attains a temperature in excess of 2,000c F.

In a rock piercing apparatus designed to pierce a new blast hole or chamber an existing one, the outside diameter of the apparatus governs the maximum diameter of the combustion chamber. Accordingly, the space wherein combustion can take place is severely limited. An airfuel flame has a lower rate of flame propagation than an oxygen-fuel flame. Therefore, at high gas velocities, the rate of flame propagation in air-fuel flame is too slow to maintain the flame within the combustion chamber space. We have discovered that` if an initial quantity of air is introduced into the combustion chamber in a rearwardly direction from air metering ports, the slug of air creates vortex flow patterns with the incoming fuel which produces local eddy currents which act as flameholders and keep the flame within the chamber. By progressively introducing more air ina rearward direction further along the combustion chamber, combustion is completed and the flame velocity at each port is further slowed so that the design is capable of being utilized over a broad range of air-fuel ratios. It has been found that the air-fuel llame will remain within the combustion chamber when at least about 20% of the total air enters the combustion chamber through the cluster of orifices 8 with the remainder of the air being introduced through the orifices 8a and 8b spaced further along the combustion chamber. The design of the present invention can operate at air-fuel ratios of from 4:1 to 25: 1, the preferred range being from about 12:1 to 17:1 with the stoichiometric ratio ybeing 15:1.

Referring now to the drawings, FIGURE l shows a v blowpipe B consisting of an outer casing C having a cylindrieal combustion chamber D located therein. The charnber D has an upstream or inlet end I and downstream or outlet end O. A back plate 1 forms a closure means for the upstream end of the chamber D and an outlet nozzle 3 is carried by the downstream end of the chamber. Nozzle 3 is water cooled and is designed to give required mass ffow and a chamber pressure of to 75 p.s.i. The nozzle 3 may be a straight bore nozzle for maximum tcmperature or for exceptionally high velocity a DeLaval nozzle may be incorporated. A fuel atomizer 5 is mounted on the back plate and communicates with a supply of liquid hydrocarbon fuel through fuel conduit 7. Also provided in back plate 1 is a passage means 9 through which oxygen or oxygen enriched air is provided from conduit 11 and bleeds into chamber D in order to ignite the blowpipe by flashing combustion back into the chamber D from an outside open llame.

The design of chamber D is critical for the reasons given above. in the particular design shown, a cluster of five orifices 8 are arranged to form a truncated triangle pattern and located in each quadrant around the circumference of the chamber D ata first section along the length of such chamber. The ports are directed rearwardlyuat preferably an angle of about 45 degrees. The number of orifices in each cluster may vary so long as the truncated triangle arrangement is maintained. Thus, a cluster may consist of 7, 9, etc. A cluster cannot consist of so many orifices such that the spacing between quadrants is lost. Additional orifices are located in each quadrant around the circumference at other sections 8A and 8B along the length of the chamber D. The orifices in each successive section are preferably staggered with respect to the orifices in the previous section. Preferably, the orifices are located at sections along the entire length of the chamber.

The triangle arrangement of the primary nir ports and the spacing between the quadrants is critical to maintaining a stable flame, that is one which will not blow out over a wide range of air-fuel ratios. The truncated triangle port arrangement gives a common focal point on the asis of the burner. The spacing between quadrants permits void areas between the iets of primary air entering the chamber. This arrangement permits standing vortices which circulate in a vertical plane between the clusters of ports thus providing a continuons source of ignition and n means for holding the flame for the fuel rich mixture as it passes into the area where secondary air enters and further combustion takes place.

The distance from the baci: plate 1 to the center line of the first orifice at the first section is critical. A preferred distance is about ll/s inch for a combustion eliamber diameter to 2V: inches. As the distance is made smaller, ignition becomes more difficult. As the distance is made larger, operation over the range of flammability limits is limited.

Compressed air to be introduced into the chamber D through the arrangement of ports just described enters the blowpipe through a flexible hose and passed down the blowpipe and along the outside of chamber D in an annular passage formed between the walls of chamber D and a water jacket 17. Water as well as the services, e.g. oxygen for ignition and fuel enter the blowpipc through a series of hoses H located within the air hose and indicated as Hw. Hl, and Ho, respectively. Water enters the jacket 17 and passes down through passages 10 and 12 (see FIGURE 3) and returns through passages 14 and 16 to exit ports 19. Water exists from the blowpipe at ports 19. ln the embodiment shown, a reamcr shell 21 surrounds the outlet nonle 3.

The particular design of the fuel atomizer is not critical to the present invention. That is, any fuel atomizer may be utilized so long as it provides a very fine degree of atomization. An alternative atomizter is shown in FIG- URE 4. In this atomizer, the fuel is passed through yoke shaped tube into two

nozzle units

33 and 35, the outlet of -which are directly opposite one another. In this ar. rangement, the two fuel streams are impinging on each other and in atomizing the total fuel.

In operation, in order to ignite the burner oxygen at about 150 to 200 s.e.f.h (standard cubic feet per hour) at 70 p.s.i. is bled into the chamber D for about 2O seconds while the fuel is being injected. The fuel flames and flashes back into the chamber by an outside open pilot flame.

The following data is provided to illustrato typical operating conditions for the device of the invention.

.The burner was ignited as described above. The combastion chamber was provided with 4 clusters of 5 holes each in the first section. Then 6 rows of 4 holesleach were provided at subsequent sections along the length of the chamber. The exit nozzle diameter was 1% inch. The back plate was l inch from the center linev of the first row holes ln the first section. Compressed air was supplied in proportion to the engine r.p'm. of the compressor. The burner was operated at the following flow conditions:

Alt Flow Fuel Flow Alr/ Alr Press Fuel l.s.i. l I/llr. Ratio Comb. inlet 17.5 400 tl. 8:1 mi 78 37.5 1` 3: l tiT Tl) 100 350 ll:l titi T8 200 32.5 12:1 liti 'lll 210 lill) 1'1. 5:1 (ii Hl) :20 '2T-'i lli. Url til Hf) 230 '2.50 lli. 2:1 tlT hl) 133 'J'.Ji 1T. l: l titi Til '245 200 1U. 5:1 Uli TT 230 ll'. il

While the above invention is described with reference to one embodiment thereof, it is to be understood that modifications may occur to one skiilcd in the art with out departing from the spirit and scope of the invention.

For example. in cases where the ambient air temperature becomes extremely low, it will be desirable to preheat the fuel in any of n number of methods which will naturally occur to the skilled artisan. Graphite liners can be used inside the combustion chamber for promoting fuel vaporization.

What is claimed is:

1. A blowpipe for thermally working minerals and mineral-like materials with a high velocity jet amc produced by the combustion of air and a liquid hydrocarbon comprising a casing member; a wall defining a cylindrical combustion chamber located in said casing member and having an upstream end and a downstream end; n back plate forming a closure for the upstream end of said chamber; a liquid fuel ntomzer c'arried on said back plate and extending into the combustion chamber for introducing atomized fuel into said chamber; rearwardly directed clusters of primary air metering ports located in each quadrant around the circumference of the wall defining said chamber at a first section immediately downstream from said back plate, said clusters being spaced from each other; additional rearwardly directed air me` tering ports located in each quadrant around the circumference of the wall defining said chamber at several other sections, each section being further downstream than the previous section and liquid fuel and air conduit means in said easing for supplying fuel to said atomizer and air to said combustion chamber through said air metering ports.

2. Apparatus according to claim 1 wherein the ports in alternating sections are staggered with respect to the ports in the sections on either side thereof.

3. Apparatus according to claim 1 wherein the ports are inclined rearwardly at an angle of about 45.

4. Apparatus according to claim 1 wherein the ports in said first section pass at least about 20% of the total air introduced into the combustion chamber.

5. Apparatus according to claim 1 wherein the distance from the back plate to the center line of the air metering ports in the first s ection is about 1% inch.

6. A blowplpc for thermally working minerals and mineral-like materials with a high velocity jet flame produced by the combustion of air and a liquid hydrocarbon into said combustion chamber for igniting atomized fuel injected into said chamber from said fuel atomizer; rearwardly directed primary air metering ports located in cach quadrant around the circumference ofthe wall defining said cylindrical combustion chamber at a first section immediately downstream from said back plate; additional rearwardly directed air metering ports located in each quadrant around the circumference of the wall defining said cylindrical combustion chamber at several other sections, eaeh section being progressively further downstream than the previous section; a series of conduit means connecting with said fuel atomizer, said oxygenenriched passage means and said air metering ports for supplying liquid fuel, oxygen, and air respectively thereto; a water jacket in said easing; means for circulating water through saidwatcr jacket; and a fluid cooled outlet nozzle 6 for discharging a high velocity llame at the downstream end of said combustion chamber.

7. Apparatus according to claim 6 wherein the liquid hydrocarbon is diesel oil.

8. Apparatus according to claim 6 wherein the liquid hydrocarbon is bunker C.

References Cited by the Examiner UNITED STATES PATENTS 2,712,351 7/1955 Roth et al. 15S- 27.4 2,896,914 7/1959 Ryan 15S- 27.4 2,923,348 2/1960 Fraser 158-76 FREDERICK L. MATTESON, JR., Primary Examiner.

MEYER PERLIN, JAMES W. WESTHAVER.

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,235,182 February 15, 1966 John W. Ross et a1.

error appears in the above numbered pat- It is hereby certified that at the said Letters Patent should read as ent requiring correction and th corrected below.

Column 4, in the table, under the sub-hleading "Ratio", line 2 thereof, for 1.3:1" read 10.321

(SEAL) Attest:

ERNEST W. SWIDER Attesting Gffoer EDWARD J. BRENNER Commissioner of Patents

Claims

1. A BLOWPIPE FOR THERMALLY WORKING MINERALS AND MINERAL-LIKE MATERIALS WITH A HIGH VELOCITY JET FLAME PRODUCED BY THE COMBUSTION OF AIR AND A LIQUID HYDROCARBON COMPRISING A CASING MEMBER; A WALL DEFINING A CYLINDRICAL COMBUSTION CHAMBER LOCATED IN SAID CASING MEMBER AND HAVING AN UPSTREAM END AND A DOWNSTREAM END; A BACK PLATE FORMING A CLOSURE FOR THE UPSTREAM END OF SAID CHAMBER; A LIQUID FUEL ATOMIZER CARRIED ON SAID BACK PLATE AND EXTENDING INTO THE COMBUSTION CHAMBER FOR INTRODUCING ATOMIZED FUEL INTO SAID CHAMBER; REARWARDLY DIRECTED CLUSTERS OF PRIMARY AIR METERING PORTS LOCATED IN EACH QUADRANT AROUND THE CIRCUMFERENCE OF THE WALL DEFINING SAID CHAMBER AT A FIRST SECTION IMMEDIATELY DOWNSTREAM FROM SAID BACK PLATE, SAID CLUSTERS BEING SPACED FROM EACH OTHER; ADDITIONAL REARWARDLY DIRECTED AIR METERING PORTS LOCATED IN EACH QUADRANT AROUND THE CIRCUMFERENCE OF THE WALL DEFINING SAID CHAMBER AT SEVERAL OTHER SECTIONS, EACH SECTION BEING FURTHER DOWNSTREAM THAN THE PREVIOUS SECTION AND LIQUID FUEL AND AIR CONDUIT MEANS IN SAID CASING FOR SUPPLYING FUEL TO SAID ATOMIZER AND AIR TO SAID COMBUSTION CHAMBER THROUGH SAID AIR METERING PORTS.