GB2137534A

GB2137534A - Spray generating apparatus

Info

Publication number: GB2137534A
Application number: GB08408651A
Authority: GB
Inventors: Eric Gates
Original assignee: KENT PROCESS CONTROL Ltd
Current assignee: KENT PROCESS CONTROL Ltd
Priority date: 1983-04-05
Filing date: 1984-04-04
Publication date: 1984-10-10
Also published as: GB8408651D0; GB2137534B

Abstract

Spray generating apparatus comprises a chamber 8, a fluid supply conduit communicating with the interior of said chamber 8, a plurality of orifices 10 extending through the chamber wall 9 and deflection surfaces 12 associated with the outlets of the orifices 10. Fluid exiting from said orifices 10 impinges on the associated deflector surface 12 to form a spray 19. A plug 14 in the chamber 8 controls the number of orifices which are open to receive fluid. The orifices are arranged in rows extending longitudinally of the chamber with the cross-sectional area of each orifice being double that of the preceding orifice in the row. <IMAGE>

Description

SPECIFICATION Spray generating apparatus This invention relates to spray generating apparatus intended particularly but not exclusively for use in cooling superheated steam.

According to the present invention there is provided spray generating apparatus comprising a chamber, fluid supply conduit communicating with the interior of said chamber, a plurality of orifices extending through the chamber wall and deflection surfaces associated with the outlets of the orifices and arranged such that fluid exiting from said orifices impinges on its associated deflector surface to form a spray.

Preferably the orifices are of circular section.

Preferably the chamber is of circular section and the orifices extend radially through the chamber wall.

Preferably the orifices are longitudinally spaced along the chamber and the apparatus includes a plug slidable within the chamber and adapted to cover and uncover the orifices to vary the amount of spray produced as required.

Preferably the orifices extend part way through the wall of the chamber and open into a recess in the outer wall of the chamber, in which recess the deflection surface is provided.

The spray generating apparatus is particularly suitable for use in cooling superheated steam. The apparatus may be designed, e.g. by appropriate angling of the deflector surfaces to the orifices, such that the spray pattern is presented to the passing steam flow such that a maximum shearing effect is obtained, thereby assisting and improving atom is tion.

The invention will be further described by way of example only with reference to the accompanying drawings, in which: Figure 1 shows a partial sectional view of a desuperheating apparatus including one embodiment of spray generating apparatus in accordance with the invention; and Figure2 is a section on line I-I of Figure 1 but omitting the plug forthe purpose of clarity.

The illustrated desuperheating apparatus 1 comprises a mount 2 with internal passageway 3, a spray generating head 4 mounted on the end of a cylindrical tube 5 the interior of which provides an extension of passageway 3, and a water inlet 6 feeding into passageway 3. Mount 2 has a radial flange 7 which may be bolted to the exterior of a superheated steam line (not shown) with the tube 7 extending through an aperture in the line whereby the head 4 is located therein.

Spray generating head 4 includes a cylindrical chamber 8 defined by an annular wall 9. This wall 9 is penetrated by radially extending, circular section orifices 10 which are provided in two diametrically opposed rows. The orifices 10 of one row are staggered with respect to the orifices 10 of the other row and it will be seen that the orifices 10 are of increasing diameter moving in a direction away from flange 7. The diameters of the orifices 10 are in fact such that, moving in a direction away from the flange 7, each orifice 10 of any one orifice row is of half the cross-sectional area of the orifice 10 in the other row which is nextmost further from the flange 7. This ensures that the spray generating head has an equal percentage characteristic.

The orifice 10 extend approximately halfway through the wall 9 and open into the apex region of a respective one of two longitudinally extending right angular recesses 11 provided in the outer part of wall 9 (see Figure 2).

Extending longitudinally within each of recesses 11 is an anvil 12 formed by a strip of suitable material which is let into that part of the wall 9 defining one limb of recess 11. The anvil 12 provides a deflection surface 13 135 to the centre line of apertures 10. The outer edge of anvil 12 may be radiussed so as effectively to be flush with the outer circumference of wall 9.

Slidable within chamber 8 is a plug 14 attached to an actuator rod 15 which extends along tube 5, passageway 3 and the top (as viewed in Figure 1) of mount 2. The rod 15 is connected, in use of the apparatus, to a suitable actuator mechanism (not shown).

Plug 14 is slidable between an upper position (as viewed in Figure 1) in which it abuts against a seat 16 and a lower position defined by a stop end 17 in chamber 8. In its upper position, plug 14 covers orifices 10 and, as it moves downwards, these orifices 10 are progressively uncovered until, at its lower position, all orifices 10 are exposed.

Provided in plug 14 are a plurality of annular grooves 18. These grooves reduce the area of contact of plug 14 with the wall of chamber 8 thereby lowering friction and also serve to provide a labyrinth seal as later described.

In use of the desuperheating apparatus 1 the actuator rod 5 is moved by the actuator mechanism (not shown) in response to a process signal which is dependent on the temperature of the superheated steam and the degree of cooling required.

Additionally, in use of the apparatus, a supply of water is established to the inlet 6.

If no cooling of the superheated steam is required, the plug 14 will be at its upper position such that all orifices 10 are covered. If cooling is required, the plug 14 is lowered to expose one or more orifices 10 as required.

Water may now pass into and through any such exposed orifice 10 along arrow A and impinge on deflector surface 13. The impingement of the round water jet issuing from orifice 10 on deflector surface 13 results in a fan shaped spray of water 19 which issues into the superheated steam. The fan shaped spray 19 is readily torn apart by the superheated steam passing the head 4thereby assisting pressure jet atomisation. It will of course be appreciated that the greater the amount of cooling required for the steam the greater will be the number of orifices 10 exposed by the plug 14. As explained previously, the cross-sectional areas of the orifices 10 are such that the unit exhibits an equal percentage characteristic.

It should be noted that, in the illustrated construction, the spacing between adjacent orifices 10 in each orifice row is such that, when two adjacent orifices 10 of a row are uncovered, the fan-shaped water sprays 19 issuing from those orifices overlap (as shown in Figure 1) providing an unbroken spray curtain for cooling the steam.

If any water seeps between the plug 14 and the wall 19 of chamber 8, it will collect in the grooves 18 ratherthan pass immediately along the length of the plub 4 and will act as a hydraulic seal. In this way, the grooves 18 provide a labyrinth seal arrangement.

It will thus be appreciated that the invention provides a simple and effective apparatus for use in the cooling of superheated steam.

It should also be appreciated that a number of modifications may be made to the illustrated construction of spray generating apparatus, for example as follows: (1) The surface and contour of the anvil 12 onto which the jets impinge may be shaped and profiled to optimise generation of spray. Such modifications made to the anvil 12 improve atomisation when the holes 10 are only part open since, without such modifications, the spray may tend to the edge of the anvil 12. Marking of the surface, of the anvil could also introduce striations into the flow which will improve the atomisation characteristics of the spray.

(2) More than two rows of orifices 10 may be provided for the apparatus. Increasing the number of orifice rows may be used to give greater continuity of the flow supply from the spray and to enable a smoothing of the flow pressure characteristics.

(3) The orifices 10 need not have cross-sectional areas providing equal percentage characteristics.

(4) The deflection surfaces 13 may be at an angle of other than 135 to the center line of the orifices 10.

(5) The illustrated construction includes a nonbalanced solid plug arrangement. It is however possible to use a balanced plug which would be effective with or without a labyrinth seal.

Claims

1. Spray generating apparatus comprising a chamber, fluid supply conduit communicating with the interior of said chamber, a plurality of orifices extending through the chamber wall and deflection surfaces associated with the outlets of the orifices such that fluid exiting from said orifices impinges on the associated deflector surface to form a spray.

2. Apparatus as claimed in claim 1 wherein the chamber is of circular section.

3. Apparatus as claimed in claim 1 or 2 wherein the orifices extend radially through the chamber wall.

4. Apparatus as claimed in any one of claims 1 to 3 wherein the orifices are of circular section.

5. Apparatus as claimed in any one of claims 1 to 4 wherein the orifices are longitudinally spaced along the chamber.

6. Apparatus as claimed in any of claims 1 to 4 wherein two opposed longitudinal rows of orifices are provided in the chamber wall and wherein the orifices of one row are staggered with respect to those of the other row.

7. Apparatus as claimed in claim 6 wherein an orifice of any one of said rows is of half the cross-sectional area of that orifice of the opposed row which is nextmost further from the inlet of the fluid supply conduit.

8. Apparatus as claimed in any one of claims 1 to 6 wherein the orifices extend part way through the wall of the chamber and open into a recess in the outer wall of the chamber and wherein said deflection surface is provided in said recess.

9. Apparatus as claimed in any one of claims 1 to 8 wherein a plug is slidable within the chamber and is adapted to cover and uncover the orifices to vary the amount of spray produced.

10. Apparatus as claimed in claim 9 when dependant on claim 5 wherein the plug has annular grooves to provide a labyrinth seal.

11. Spray generating apparatus substantially as hereinbefore described with reference to the accompanying drawings.