US 3169161 A
Description (OCR text may contain errors)
Feb. 9, 1965 E. F. KURZINSKI OXYGEN-FUEL PROBE 2 Sheets-Sheet l INVENTOR. EDWARD F. KURZINSKI Filed April 5. 1961 A TTORNE YS E. F. KURZINSKI OXYGEN-FUEL. PROBE 2 Sheets-Sheet 2 Feb. 9, 1965 Filed April 5. 1961 3,lfi9,l6l Patented Feb. 9, 1965 assignments, to Air Products and Chemicals, line,
Trexlertown, Pa, a corporation of Delaware Filed Apr. 5, 1961, Ser. No. 161,012 4 Claims. (Cl. 266-41) The invention relates generally to means for introducing reactants into a metallurgical furnace and more particularly to apparatus provided with a cooling system which permits introducing oxygen or a combination of reactants directly to the high temperature reaction zone of a metallurgical furnace.
The steel industry provides a typical environment for application of the invention. For example, in an open hearth furnace, heat must be supplied to scrap and/ or molten metal in the hearth to raise it to the proper reaction temperature and oxygen or other reactants must be supplied for refining purposes. The invention provides apparatus which is uniquely suitable for either or both purposes.
One of the objects of the invention is the provision of novel apparatus which will increase the production rates and capacity of metallurgical furnacesby providing higher heat-input rates and greater heating efficiency while improving combustion control.
Another object of the invention is the provision of novel apparatus for improving metal refining processes by providing more effective control of the addition of reactants.
In describing the invention reference will be had to the accompanying drawings in which:
FIG. 1 is a longitudinal view, partially in section, of apparatus embodying the invention;
FIG. 2 is a lateral cross-sectional View of the apparatus of FIG. 1 taken along the lines 2--2;
FIG. 3 is an end view of the apparatus of FIG. 1;
FIG. 4 is a longitudinal view, partially in section, of apparatus embodying the invention;
FIG. 5 is an enlarged longitudinal cross-sectional view of a port-ion of FIG. 4;
FIG. 6 is a lateral cross-sectional view taken along the lines 6-6 of FIG. 5; and
FIG. 7 is a lateral cross-sectional view taken along the lines 77 of FIG. 5.
The embodiment of FIG. 1 includes fluid inlet means, designated generally 9, at one end of an elongated probe structure and, at the opposite longitudinal end thereof, a nozzle structure, designated generally 10, for discharging a fluid or mixture of fluids into a furnace. Intermediate the fluid inlet means 9 and nozzle structure 10, elongated tubular means are provided for conveying fluids, pre-mixing fluids, and providing temperature control for the entire structure.
The fluid inlet means includes a conduit 12 for a first fluid, such as oxygen, and conduit 14, for a second fluid, such as natural gas. The fluid inlet means may also include valving and measuring apparatus on each conduit such as that shown schematically at 15. Within the elongated probe structure itself, conduits 12 and 14 may extend in substantially coaxial relationship. The probe structure includes a hollow outer member 16 in surrounding relationship to conduit 14 so as to define an elongated hollow annular chamber 17.
Temperature control of the structure is effected by a cooling system including a cooling inlet means 18, a coolant inlet manifold 19 and a coolant outlet means 20. A baffle plate 21 closes one end of the coolant inlet manifold 19. A plurality of coolant inlet tubes 22 penetrate the b aille plate 21 to communicate with the coolant inlet manifold 19. The total cross-sectional area of the plurality of coolant inlet tubes 22 is substantially less than the total cross-sectional area of the hollow chamber 17. A coolant return passageway is provided by the portion of annular chamber 17 exterior to the coolant inlet tubes 22. The coolant return passageway may be equal or substantially equal in cross-sectional area to the total cross-sectional area of the coolant inlet tubes 22.
At the nozzle end of the structure the coolant inlet tubes 22 empty into a coolant receptacle 25 defined by the nozzle structure 10. The coolant receptacle 25 communicates with both the coolant inlet tubes 22 and the coolant return passageway surrounding the tubes so that coolant entering the nozzle structure It circulates within such structure and passes out through the coolant return passageway. At their discharge end the coolant inlet tubes 22 are shaped to direct coolant to particular portions of the nozzle structure 10. A portion of the coolant inlet r tubes 22 are slanted as at 26 to direct coolant onto the joint between the nozzle structure 10 and the hollow outer member 16; another portion of the coolant inlet tubes 22 extend into the nozzle structure a greater distance and are slanted inwardly as at 27 to direct coolant onto the inner surface 28 of the nozzle structure 10. In practice alternate coolant tube ends can be slanted outwardly and inwardly.
Longitudinally intermediate the fluid inlet means 9 and the nozzle structure 19 an injector means 30 is provided for mixing the fluids supplied through conduits 12 and 14 and developing the proper velocity for injection into the furnace. The injector means 30 includes an injector nozzle 31, a venturi throat 32, and delivery tube 33. The fluid from conduit 12 passes within injector nozzle 31.
- The fluid from conduit 12 passes through passage means 36 and is drawn inwardly into the main flow path. The
two fluids are mixed and pass through the venturi throat 32 into the delivery tube 33 where mixing continues. The mixed fluid stream passes out of the nozzle structure 10 through divergent ports 38 and is discharged into the reaction zone.
At the inlet side of the injector means 30 a check valve mechanism 35 is provided in conduit 12. This check valve may be of conventional structure and is for the purpose of preventing blow back of fluids in the event of inadvertent pro-ignition of the mixture within the probe structure and also to prevent the mixing of combustible and combustion supporting fluids within the probe structure and supply lines in the event of blocking by solidified metal or slag of one or more of the discharge ports. Conventional check valves may also be included in each of the conduits 12 and 14 at the fiuid inlet means 9. It is important to have the mixed fluid velocity in the passages considenably greater than the rate of flame propagation to overcome the possibility of pre-ignition when introducing a combustible mixture. Other factors have been found to be critical in preventingpre-ignition such as the lengthdiameter (L/ D) ratio of the ports 38; this ratio should not be reduced below 1.5 :l.
'The end view of nozzle structure 1@ in FIGURE 3 shows the disposition of the ports 38. The angle of di vergence of the ports from the probe center line may exceed 20 in order to increase the area of contact during melt down operations; however, the maximum desirable angle is approximately 30. A further increase reduces the effectiveness of the nozzle structure when operating with oxygen only for refining purposes.
An important feature of the invention for oxy-fuel burner applications is the pre-mixing of fuel and oxygen within the probe structure made possible by injector means 3t). This feature has particular advantages at plant sites where fuel pressures are low since the energy of the oxygen streams can be used to aspirate the fuel. Other important advantages of the pre-mix design of the invention are improved mixing of fuel and oxygen which provides improved flame characteristics and better control of the combustion products.
In practice the discharge ports may be counterbored to control the distance beyond the end of the nozzle at which ignition occurs. The maximum distance at which ignition can occur is determined by the velocity of the combustible mixture. The point of ignition can be brought closer to the nozzle by enlarging the diameter of the counter-bore of the port. The point of ignition should not be brought into contact with the nozzle structure as the cooling effect of the mixed gases is lost thereby. Typical counterbore dimensions are a 1%" diameter with a W depth for a discharge port with a mixed gas volume of about 12,000 cubic feet per hour per discharge port.
Other furnace additions, such as ore, mill scale, and fluxes may be introduced into a furnace using the oxygen stream to aspirate additions. Excellent control of additions, considering quantity, time, and placement in the furnace, is obtained. It should be noted that the oxygen stream keeps the orifices free from clogging when additions are not being introduced.
A particular advantage resulting from extending coolant inlet tubes into the nozzle structure is that coolant is guided to the hottest areas of the nozzle structure and adequate cooling of such surfaces as the point of probenozzle juncture and the tip of the nozzle structure is assured. The advantage of having the crosssectional area of the coolant inlet tubes 22 substantially equal to the cross-sectional area of the coolant return passage, or hearing a known ratio, is that velocity of coolant along the entire length of the probe can be readily selected and controlled effecting better temperature control since the heat transfer is a function of such velocity.
Referring to FIG. 4 the probe structure includes a fluid inlet means designated generally 39 and a nozzle structure designated generally 40. The fluid inlet means includes a conduit 42 for a combustible fluid such as natural gas and a conduit 44 for a combustion supporting fluid such as oxygen. The fluid of conduit 42 passes through check valve mechanism 45 and into the cross-over and injector structure 46. This structure is shown in greater detail in FIG. the fluid in conduit 42 passes outwardly through the passageways 47 and oxygen in conduit 44 passes inwardly through passageways 48. The oxygen passes through injector nozzle 50 and draws fluid from the conduit 42 and passageways 47 into the main stream. The fluids are mixed and pass through venturi throat 51, delivery tube 52, and outwardly through discharge ports 54.
In FIG. 4, a check valve 45 for the fuel conduit 42 is located immediately prior to the crossover and injector structure 46. A combination of the apparatus of FIGS. 1 and 4 may be employed to provide a check valve in both the fuel and oxygen conduits. To accomplish this end, a check valve may be located in the chamber 49 immediately prior to the injector nozzle 50.
The oxygen and fuel passages referred to in describing the invention are not to limit the invention; oxygen as used herein includes air or oxygen enriched air; fuel includes any suitable hydrocarbon gaseous, liquid, or pul verized solid. Also, other reactants than fuel may be added with oxygen. Many variations of the present invention are possible in the light of the teachings of the disclosure, for example the incoming and return coolant passageways may be reversed with certain modifications; it is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically disclosed.
1. An oxy-fuel probe for premixing and introducing oxygen and fuel to the reaction zone in a metallurgical furnace comprising an elongated hollow outer tubular member in overlapping relationship with an elongated 1 hollow inner tubular member; fluid inlet means, coolant inlet means, and coolant outlet means located at one end of the fluid transfer device and nozzle structure located at the opposite longitudinal end of the device; means located intermediate the elongated hollow outer tubular member and the hollow inner tubular member defining coolant inlet and coolant outlet passageway means connected to the coolant inlet and coolant outlet means respectively at one end of the device and communicating with the nozzle structure at the longitudinally opposite end of the device; conduit means within the hollow inner member dividing such member into an oxygen passageway means and a fuel passageway means; injector means longitudinally intermediate the fluid inlet means and the nozzle structure arranged and adapted to interconnect the oxygen and fuel passageway means, said injector means having a venturi throat and means for aspirating the fuel stream into the oxygen stream, so as to admix the same before entering the venturi throat and to develop the desired nozzle velocity; a plurality of fluid discharge ports defined by the nozzle structure; and an elongated delivery tube connecting the venturi throat with the discharge ports for completing internal premixing of the fuel and ox gen streams.
2. Apparatus as in claim 1 in which said discharge ports are arranged to discharge divergent fluid streams at an angle of 2030 from the center line of the probe.
3. Apparatus as in claim 2 in which said discharge ports have a length-diameter ratio. of at least 1.5 to 1.
4. Apparatus as in claim 3 in which said discharge ports are counterbored at the discharge end.
References Cited in the file of this patent UNITED STATES PATENTS Belgium May 12, 1955