Straight Stream Nozzle

This invention relates generally to nozzles for producing a straight liquid stream and more particularly to such nozzles which produce a stream which is more cohesive at greater distances from the nozzle face.

In various instances it is desirable to utilize a liquid stream to impact upon a solid surface and thus help to remove rust, scale or other solid matter from such surface. The use of such a liquid stream may be particularly desirable in situations where it is difficult to reach the surface to be cleaned, as for instance in large tanks, furnaces and the like. With previously available nozzles a continuing or recurring problem has been a tendency of the fluid stream to fan out or spread apart as the liquid gets further from the point of discharge from the nozzle. The result of such spreading apart of the liquid stream is a reduction in the force applied when the stream impacts on the surface to be cleaned. As a result, it may be necessary to use a larger nozzle or a greater amount of time to achieve satisfactory results.

One application in which such straight stream nozzles are useful is in the cleaning of soot blowers where an elongated member commonly called a lance is provided with a plurality of nozzles and inserted into the blower through one or more openings provided for that purpose. Construction and operation of such apparatus is described in U.S. Pat. Nos. 4,209,028, 4,422,882 and others and need not be described here in further detail.

Various attempts have been made previously to provide improved nozzle designs whereby a liquid stream maintains greater integrity even at substantial distances from the point of discharge from the nozzle. One such prior design is described in U.S. Pat. No. 4,565,324 wherein a plurality of smaller streams are discharged in such a manner as to generally surround a single large central stream. Nozzles in accord with this patent produce a more concentrated and coherent fluid stream than earlier designs but still evidence some stream deterioration, especially at substantial distances from the point of discharge.

Improved performance has now been achieved by the present invention in which a nozzle is provided with concentric arrays of axially extending through ports surrounding a solid center. As liquid flows through all of the ports, the substantial number of passageways helps to produce a more laminar, less turbulent and more cohesive flow and the liquid discharged from the radially outer ports helps to shield the streams which emerge from the inner ports. As a result of the improved cohesiveness, a stream of any given volume and pressure will be more concentrated at impact upon a surface and thus impart greater force on that surface.

It is thus a primary object of the present invention to provide a nozzle which discharges a more cohesive liquid stream and more especially a stream which holds together better at a substantial distance from the point of discharge from such a nozzle.

Another object of the invention is to provide a nozzle which produces a fluid stream with less turbulence.

A further object of the invention is to provide a nozzle which accomplishes a greater amount of work in the same time as prior known nozzles.

Yet another object of the invention is to provide such a nozzle which is relatively simple in construction and which can be retrofitted into existing machinery or equipment.

These and other objects, features and advantages of this invention will be made more fully understandable to those having skill in this art by reference to the following specification and claims, and to the accompanying drawings, in which:

FIG. 1 is a sectional view of a preferred nozzle along an axial plane.

FIG. 2 is a view of a nozzle core along a transverse plane.

FIG. 3 is a sectional view of the nozzle assembly of FIG. 1 along line 3--3 of FIG. 1.

Referring now to the drawings, FIG. 1 shows in side sectional view a preferred nozzle made in accord with the invention. Thus, a nozzle 10 comprises an outer body 12 and an inner core 14. Outer body 12 preferably has a stepped bore 15-16 dimensioned to receive a stepped outer diameter of inner core 14. Preferably, body 12 also has a threaded portion 18 to allow easy connection of the nozzle to supporting equipment. As best seen in FIG. 2 inner core 14 is provided with a plurality Y of surfaces 20 on its outer periphery, each such surface being equal to one another and equally spaced from one another so as to form a regular or symmetrical pattern. Surfaces 20 may be concave, convex, straight or of other shape, as long as all are of the same form. Inner core 14 also has a solid center portion 22 around which is arrayed a plurality X of holes or ports 24 which together form a first plurality of axially extending through ports which are equally spaced and of equal diameter and thus form a regular or symmetrical pattern. The solid center portion 22 creates a hollow center in the liquid stream at the point of discharge from the nozzle and this hollow center apparently forms an area of low pressure which in turn promotes cohesion of the inner array of streams to form a more concentrated liquid stream which produces a greater impact on the target surface.

In FIG. 3, it is clearly seen that when inner core 14 is assembled with outer body 12, surfaces 20 of the inner core combine with equal portions of bore 15-16 to form therebetween a series of elongated passages or ports 26 which together form a second plurality of axially extending through ports. This second plurality of ports is arrayed radially outwardly of the first plurality of ports 24 and thus generally surrounds the first plurality or array. In the preferred nozzle as shown, the core 14 is retained in the nozzle body 12 by means of a press fit between ribs 28 and the lesser diameter portion 16 of stepped inner bore 15-16 of outer body 12. The number of ports in each array is limited only by the overall size of the finished nozzle. In a typical soot blower lance for instance, the outer diameter of the nozzle body will be on the order of 5/8 inch and thus the use of more than five or six ports in each array would be impractical.

Within the preceding parameters a number of design features are thought to be preferred. For example, it is believed that the most preferred arrangement is one in which the number of ports in each array is equal and further is one in which the total cross-sectional area of the ports in each array is substantially equal. It is also to be preferred that the array of ports formed between the nozzle core and the nozzle body (the radially outer array of ports) be of generally slotlike or elongated form in transverse section and with the major axis of each such port substantially perpendicular to a radius of the nozzle passing through the midpoint of the major axis. It is also to be preferred that the axially extending through ports in each array each be of a length at least equal to the mean diameter of such ports and more preferably several times that diameter in order to reduce turbulence and to enhance laminar flow of the liquid. Another preferred design feature would be for the outer (discharge) end of stepped bore 15-16 of the nozzle outer body 12 to have a very slight (e.g. 3 or 4 degree) inward taper to direct the liquid flow very slightly inwardly.

Comparative performance results between the nozzle of the invention and the tested nozzle of U.S. Pat. No. 4,565,324 show that a significant improvement is obtained with the new design. For example, with a pressure of 300 psig and a flow rate of 15 gallons (U.S.) per minute and at a distance of 15 feet, the prior nozzle exhibits a spray pattern somewhat more than twice the diameter of the nozzle of the invention.

While a preferred embodiment and some variations thereof have been shown and described in detail, other modifications will be readily apparent to those skilled in the art of nozzles. For example, while a two piece nozzle is presently preferred for ease of manufacture, a one piece nozzle may be equally satisfactory in some instances. Further, while a press fit of the inner core into the nozzle body is preferred, other means such as a snap ring or a threaded retainer may be used to hold the core and body in proper relative position. It is also quite likely that the nozzle of the invention will be used in combination with other types of nozzles such as spray nozzles to form a composite multi purpose nozzle assembly. Thus, the preceding specification should be interpreted as exemplary rather than as limiting and the scope of the invention is defined by the following claims.