Oxygen-fuel-blowing Multihole Nozzle

Abstract

A multinozzle lance in which a central fuel pipe is surrounded by an outer pipe through which an oxygen containing gas is fed under pressure. A plurality of angularly displaced nozzles extend downwardly and outwardly inclined from the lower end of the outer pipe and the lower end of the central pipe communicates with the nozzle through fuel passages having axes extending transverse to the respective nozzle axis. Each of the nozzles has intermediate its ends a throat portion and flares outwardly to opposite sides of the throat portion, and each of the fuel passages communicates with the respective nozzle downstream of the throat portion thereof.

Description

This invention relates to an improvement of a multinozzle lance for blowing-in of oxygen and fuel. In an open-hearth furnace or a converter in iron or steel industry, it is desired to melt cold charge, such as solid pig iron and scrap, of high load in a short time. To this end, various kinds of oxygen-fuel-blowing nozzles have recently been studied and developed by engineers of this field. However such nozzles mainly depend on blowing-in of fuel with a single-hole nozzle. This method of blowing-in requires a high temperature and a large heating surface flame while the expansion of flame is limited single-hole nozzle. The present invention which adopts an appropriately formed multihole nozzle is intended to enlarge the expansion of the flame and thereby its heating area, for improving its thermal efficiency.

The basic object of the present invention is to provide a multinozzle lance for blowing-in of oxygen and fuel, which is capable of melting cold charge of high load in a vessel in a short time, thereby increasing productive efficiency. A multinozzle lance of the present invention is provided with a plurality of nozzles around the axis of the lance at approximately equal angles thereby enlarging the expansion of the flame so as to increase the heating surface. Further when such a multinozzle lance is used, flames coming from respective parts show an indentical distribution of blowing speed so that flames run at a high speed even at position away from the axis of the lance. This increases the amount of heat transmitted to a cold charge to permit the melting thereof in a short time.

Another object of the present invention is to blow oxygen or air and fuel with a single lance at the same time, In operating a converter or an open hearth, it is used to charge said cold material such as solid pig iron and scrap appropriately in correspondence to the process of refining. Accordingly in refining it is generally required to blow oxygen, oxygen-enriched air, or argon-oxygen mixture or the like accompanied by fuel blown when said material is charged. Such blowing oxygen or the like and fuel with separate nozzles has disadvantages that not only separate nozzles must be prepared but also the operations for handling these nozzle becomes troublesome, eventually requiring the discontinuity of refining work. According to the present invention which carries out these blows with a single lance, a fuel pipe, an oxygen pipe and a cooling jacket are concentrically arranged. The oxygen pipe is provided in its lower end portion with a plurality of outward-expanding Laval-type nozzles extending radially and obliquely downward. The fuel pipe is provided in its lower end portion with an appropriate number of fuel passages, which respectively open downstream of the portions of the nozzle's throat, obliquely and downwardly inclined in the injection position. Such construction of the present invention permits to blow fuel, as oil, through a fuel pipe. When the feed of fuel is stopped, a nozzle of the present invention can be used for blowing only oxygen or the like without difficulties. This curtails equipment expenses, simplifies handling operation and smoothens refining works.

Many other concrete features and construction details of the present invention will be clear from the following descriptions of the embodiments of the invention, made in connection with the accompanying drawings, in which:

FIG. 1 is a partially sectioned side view of a multihole nozzle lance of the present invention:

FIG. 2 is an enlarged side view of the lower part of said nozzle;

FIG. 3 is a bottom view of the same nozzle;

FIG. 4 is a diagram showing the distribution of flow rate of a nozzle (A) of a multihole nozzle of the present invention. (B) shows the distribution of flow rate of a well-known single-hole nozzle.

The lance of the present invention comprises an oxygen-blowing pipe 1. In the illustrated embodiment, the oxygen-blowing pipe 1 is curved in inversed L-shape in the upper portion to form an oxygen inlet 1'. A fuel blowing pipe 2 extends through the center of the main portion of said inlet to the end of the oxygen-blowing pipe 1. 3 is a cooling jacket concentrically enclosing the main portion of said oxygen-blowing pipe 1, and a cooling water supply socket 4 is provided in a portion near the upper end of the cooling jacket in FIG. 1. 5 is a mantle jacket further provided concentrically so as to surround most part of said cooling jacket 3, and an inlet chamber 5a thereof communicates with a water chamber 3a of said cooling jacket 3 in the lower end portion of lance. A cooling water exhaust socket 6 is connected to a portion near the upper end portion of said mantle jacket. A stuffing box comprising a pair of members 16 and 17 clamped together by a screw 9 to compress a packing 10 sandwiched between these members is provided about a portion of pipe 2, where the latter enters into the curved portion of pipe 1.

As clearly illustrated in the enlarged vertical section view of FIG. 2, the lower end of the fuel-blowing pipe 2 reaches a distribution chamber 12 provided centrally in the lower portion of the lance. Several fuel passages 7 are provided extending obliquely downwardly from this distribution chamber 12 and communicate with Lavallike nozzles 8 in radial direction 6. (Refer to FIG. 3.) The number of said fuel passage 7 and Lavallike nozzle 8 is optionally selected. In the illustrated embodiment, they are three respectively.

The fill passages 7 communicate with the nozzles downstream of throat portions 18 thereof. To explain more concretely, each nozzle 8 expands at one end upwardly in a trumpetlike manner toward the interior of the oxygen pipe 1, and also expands at the other end downwardly toward the end of the lance. Between both ends of each nozzle is formed a throat portion 18 constituting parallel straight sidewalls of appropriate length, whereby oxygen jets are given desirable flow rate and appropriate direction or rectilinear propagation. Above stated fuel passages 7 open downstream of the throat portion 18.

When a lance with multinozzle of the present invention is manufactured, a body portion and lower end member are manufactured separately and then jointed for example by welding. So despite multilaminate construction, said nozzles and oxygen-blowing pipe 1 can be manufactured relatively easily and simply. Moreover the lower end member can be easily mounted to a multinozzle lance body after long use, requiring at best an exchange of said member if necessary.

Now an explanation will be given on the function of the blowing nozzle according to the present invention. When high-pressure oxygen or the like is blown from the oxygen pipe 1, it is jetted from several nozzle 8 with supersonic velocities. On the other hand, fuel is conveyed through the fuel-blowing pipe 2 concentrically with the oxygen-blowing pipe 1 to the end of the lance and then fed into the distribution chamber 12 formed between nozzles, and through the distribution chamber 12 the fuel is blown through the fuel passages 7 opening in the respective nozzles where it is atomized and simultaneously well mixed with oxygen.

Thus gas consisting of fuel and oxygen shows a distribution of flow rates as shown in FIG. 4 (A). By using a multinozzle as lance the present invention, distributions of flow rates jetted from each Lavallike nozzle 8 are not only identical respectively but also shows a flow rate distribution similar to a single-hole nozzle as shown in FIG. 4 (B). This permits to obtain a sufficiently high flow rate even at a position away from axis of a nozzle. Moreover the whole expansion of blowing fluid obtained by this multinozzle lance is evidently larger than that obtained by a single nozzle lance. Accordingly when burning in the same condition, a multinozzle lance of the present invention not only improves combustion efficiency but also increases thermal conductivity to high-load cold charge as comparing with conventional single-hole nozzle. Further when the heating is stopped for performing ordinary oxygen blow refining, this multinozzle lance of the present invention can also be used as an ordinary oxygen-blowing lance by stopping the feed of heavy oil as fuel, and if necessary, by feeding some stream into a fuel-blowing pipe to prevent counterflow of heavy oil. In consequence, a multinozzle lance of the present invention can serve in an open hearth or a converter very effectively as a high-load cold charge melting nozzle as well as an ordinary oxygen-blowing lance.

Claims

We claim:

1. A multinozzle lance comprising a first pipe having an axis, a lower closed end and an upper end adapted to be connected to a supply of an oxygen-containing gas under pressure; a plurality of nozzles communicating with said closed end of said first pipe, said nozzles being angularly displaced from each other about the axis of said first pipe and each having an axis extending downwardly and outwardly inclined to said axis of said first pipe from the closed end of the latter, each of said nozzles having a cylindrical throat portion intermediate opposite ends thereof and flares from said throat portion outwardly toward said opposite ends; a second pipe extending through said first pipe and having a closed end in the region of said closed end of said first pipe and an opposite end adapted to be connected to a supply of fuel fluid; and a plurality of fluid passages communicating with said second pipe in the region of the closed end thereof and with said nozzles, respectively, downstream of the respective throat portions, but upstream of the outer ends thereof, each of said passages having an axis extending transverse to the axis of the respective nozzle.

2. A multinozzle lance as defined in claim 1, and including water jacket means surrounding said nozzles and at least part of said first pipe.

3. A multinozzle lance as defined in claim 2, wherein said water jacket comprises an inner jacket substantially concentrically arranged about and extending from said closed end of said first pipe over a major portion of the latter and forming between the inner surface of said inner jacket and the outer surface of said first pipe a first elongated cooling chamber of annular cross section, an outer jacket surrounding said inner jacket and forming therewith a second cooling chamber of annular cross section communicating with said interior of said first cooling chamber in the region of said closed end of said first pipe, cooling fluid inlet means communicating with the interior of said first cooling chamber in the region of the latter opposite from said closed end of said first pipe, and cooling fluid outlet means communicating with the interior of said second cooling chamber in the region of said fluid inlet means.