NZ205182A - Atomizer for atomizing liquid with gas - Google Patents

Description

205182 NEW ZEALAND PATENTS ACT, 1953 No.: Date: Priority Date{s): Fl.

Complete Specification Filed: Class: JT.&itfSal9.9.^. ...

Publication Date: . :} ?. .?££.??.?' P.O. Journal, No: COMPLETE SPECIFICATION MIX ATOMIZER jd^We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V. , Carel van Bylandtlaan 30, 2596 HR The Hague, the Netherlands, a Netherlands Company hereby declare the invention for which W we pray that a patent may be granted to jcjg^us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page lei) - lc^- H s 1 *as 5 K 5624 MIX ATOMIZER ■ The invention relates to a mix atcmizer for the atonization of a liquid with gas. The invention further relates to an apparatus for the atonization of a liquid, which apparatus is provided with a plurality of such mix atcmizers.

The term liquid is taken throughout the specification and claims also to include dispersions of solid particles in a liquid and emulsions.

Atomizers are applied on a large scale in combustion engineering, especially for atonizing heavy liquid fuel, to 10 promote intensive contact of liquid with combustion air for a proper coribustian. In an atonizer liquid fuel is broken up into very small droplets which droplets may be subsequently mixed with oxygen or an oxygen-containing gas, for example air, in a combustion chamber for coribustian of the fuel. Atonization is 15 normally effected by causing a liquid to spurt under pressure frcm one or more orifices with special shape and dimensions. Addition of a gas, for example steam, to the liquid in the atonizer itself promotes the atonization of the liquid. An atonizer wherein gas is added to the liquid to be atomized is in 20 the specification and claims indicated with the expression mix atonizer. When a fuel is to be atomized it is of importance to generate sprays of liquid droplets which are substantially uniformly distributed over the outlet area of the atonizer, in order to promote an optimal combustion of the liquid in the 25 combustion chamber.

Although the elucidation of the present invention to be given hereinafter will deal mainly with steam atonization of liquid, such as oil, it is explicitly stated here that the application of the proposed atonizer is not restricted thereto. 2051o2 Steam may be replaced by, for example, air or refinery fuel gas. The steam may also be saturated to wet. Apart from application in combustion installations atomizers of the proposed type can also be used in spraying installations, for instance, for the 5 purpose of the vaporization of a volatile component.

The object of the present invention in to provide a mix atonizer for the atonization of a liquid with a gas which apparatus is so designed that the velocity and flux of the liquid leaving the atonizer during operation are substantially 10 uniformly distributed over the outlet area of the atonizer, in order to generate homogeneous liquid sprays, promoting optimal use of the liquid for combustion or other purposes.

The mix atonizer for the atonization of a liquid with gas according to the invention thereto comprises a first mixing 15 chamber provided with inlet means for supplying a liquid and primary gas to form a mixture of liquid and gas, said first mixing chamber debouching into a second mixing chamber having cross-sectional areas being substantially larger than the cross-sectional areas of the first mixing chamber, means for 20 tangentially supplying secondary gas around the mixture of liquid and gas passing through the second mixing chamber during operation, the second mixing chamber debouching into an outlet nozzle, having cross-sectional areas being substantially smaller than the cross-sectional areas of the second mixing chamber, the 25 first mixing chairiber, the second mixing chamber, and the outlet nozzle having substantially coinciding longitudinal axes.

In a suitable embodiment of the invention a plurality of the above-mentioned atcmizers are combined in a single apparatus for atonization of a liquid, said apparatus having a single 30 liquid supply and a single gas supply serving the plurality of mix atomizers.

The invention therefore further relates to an apparatus for the atonization of a liquid with gas, comprising a member having a longitudinal axis and being internally provided with a plurality 2051, of mix atcmizers according to the invention, terminating at the outer surface of a head of the member, the member being internally provided with one liquid supply channel and one gas supply channel, first passages forming fluid corrramications between the 5 liquid supply channel and the first mixing chambers of the mix atcmizers, second passages for supplying primary gas frcm the gas supply channel into said first mixing chambers, and third passages for tangentially supplying secondary gas frcm the gas supply channel into the second mixing chambers of the mix 10 atcmizers.

The invention will new be described by way of example only in more detail with reference to the accompanying drawings, in which Figure 1 shows a longitudinal section of a mix atomizer 15 according to the invention.

Figure 2 shows a longitudinal section of an apparatus for the atonization of a liquid provided with a plurality of mix atcmizers according to the invention, and Figure 3 shews a top view of the apparatus shown in 20 Figure 2.

Figure 1 shows a mix atomizer, generally indicated by reference numeral 1, for atomizing a liquid, such as a heavy liquid fuel, with a gas. The mix atonizer 1 has as main components a first mixing chamber 2, a second chairiber 3 being in 25 fluid ccmnunication with the first mixing chamber 2, and an outlet nozzle 4 connected with the second mixing chamber 3.

These three components have substantially coinciding longitudinal axes, while the cross-sectional areas of the second mixing chamber 3 and those of the outlet nozzle 4 are both substan-30 tially larger than the cross-sectional areas of the first mixing chamber 2. Further, the cross-sectional areas of the outlet nozzle 4 are chosen smaller than the cross-sectional areas of the second mixing chairiber 3. Channels 5 and 6 are arranged in the atomizer for supplying a liquid to be atomized and atomizing 205182 gas, respectively, into the first mixing chamber 2 at or near the free end thereof. The channels 5 and 6 are positioned at an angle with respect to one another to promote intensive break-up of the liquid flew issuing frcm channel 5 by the gasflow frcm 5 channel 6.

For supplying gas into the second mixing chamber 3 the mix atonizer is provided with a ring-shaped channel 7 with passages 8 forming fluid corrnunications between the channel 7 and said mixing chamber 3. These passages 8, being preferably uniformly distributed over the circumference of the second mixing chamber 3, are so positioned with respect to said second mixing chamber that gas frcm the ring-shaped channel 7 is tangentially introduced into said mixing chamber 3.

Downstream of the ring-shaped channel 7 the second mixing 15 chamber 3 has a substantially frusto-conically shaped side wall 9 tapering towards the outlet nozzle 4 thereby providing a smooth guiding for fluid frcm the channel 7 and the passages 8 tcwards the outlet nozzle 4.

During operation of the mix atonizer shown in Figure 1 for 20 the atcmization of liquid fuel with steam, the liquid to be atomized and steam are introduced into the first mixing chamber 2. Owing to the impact of the steam flow on the supplied liquid flew, the liquid flew is broken up into small liquid fragments in the first mixing chamber 2. The breaking up of the liquid 25 flow is promoted by causing the steam from the channel 6 to contact the liquid flow from the channel 5 at an angle. The so formed mixture of liquid fragments and steam enters the second mixing chamber 3, where secondary steam is added at sonic velocity to said mixture. Since the secondary steam is tangen-30 tially introduced at a high velocity into the second mixing chamber at a wide part thereof, the secondary steam will form an annulus around the core formed by the mixture of liquid fragments and primary steam frcm the first mixing chamber 2. The major part of the tangentially introduced steam flews substantially along 2051 r the frusto-conically shaped wall 9 of the second mixing chanter 3 and follows its way along the wall of the outlet nozzle 4, thereby preventing direct contact of liquid with said walls.

Such a contact might easily reduce the velocity of the liquid flowing close to said walls, resulting in an irregular outflow pattern of the liquid over the outlet nozzle 4.

Since the cross-sectional areas of the outlet nozzle 4 are substantially smaller than the cross-sectional areas of the second mixing chamber 3, the velocity of the mixture of steam and liquid fragments is substantially increased in the outlet nozzle 4, causing a further break-up of the liquid fragments. Ctoing to the presence of a shield of the tangentially supplied secondary steam the velocity and the density of the liquid fragments over the cross section of the outlet nozzle 4 will be substantially uniform, which feature enables an effective combustion of the liquid in a not shown combustion chamber arranged downstream of the outlet nozzle 4. Upon leaving the mix atonizer the liquid/ steam mixture will rapidly expand, resulting in the formation of a mist of very fine liquid droplets in the combustion space, where the liquid droplets are contacted with blast for the combustion of the fuel.

Reference is now made to Figures 2 and 3 showing an apparatus for atomizing liquid, which apparatus is provided with a plurality of mix atcmizers of a type discussed in the above with reference to Figure 1.

This atonization apparatus comprises a member 10 provided with a central channel 11 for the supply of atonization fluid to a plurality of mix atcmizers 12, and with a concentrically positioned annular channel 13 for the supply of liquid, such as oil, to be atcmized. The mix atonizers 12 are arranged in a head 14 of the apparatus 10.

The distance between the outlet nozzles of adjacent mix atomizers 12 should be chosen sufficiently large to prevent interference between adjacent outflowing streams of liquid droplets. A suitable arrangement of the mix atonizers 12 is the one shown in Figure 3, wherein the centres of the outlet nozzles of the mix atcmizers 12 are positioned in a circular pattern, and wherein adjacent outlet nozzles are spaced apart frcm one another at 120 degrees. As shewn in Figure 2 the head 14 of the apparatus 10 is frusto-conically shaped whereas the mix atcmizers 12 are arranged perpendicular to the outer surface of said head 14. This arrangement enables the application of more mix atcmizers without the risk of interference between adjacent mix atcmizers than possible when using an apparatus having a flat head and the mix atcmizers being arranged perpendicular to the flat outer surface of the head.

Each mix atcmizer 12 is provided with a first mixing chamber 15, a second mixing chamber 16 and an outlet nozzle 17, wherein the second mixing chamber 16 is substantially wider than the first mixing chanter 15. The first mixing chamber 15, the second mixing chamber 16 and the outlet nozzle 17 of each mix atcmizer 12 have coinciding longitudinal axes, positioned perpendicular to the frusto-conically shaped outer surface of head 14.

For supplying primary atonization fluid to the mix atcmizers 12, a plurality of passages 18 are provided forming fluid communications between the central channel 11 and the first mixing chambers 15. Secondary atonization fluid is supplied via tangentially arranged passages 19 to the second mixing chambers 16 of the mix atcmizers 12. These passages 19 form fluid connunications between the mix atcmizers 12 and a substantially ring-shaped channel 20 connected to the central channel 11 via a passage 21. For the supply of secondary atonization fluid to the mix atcmizers 12 via tangentially arranged passages 19 as shown in Figure 2, the ring-shaped channel 20 surrounds the mix atonizers 12.

Fluid to be atomized is supplied to the first mixing chambers 15 of the mix atcmizers 12 via a plurality of passages 22 forming a fluid conmunication between the annular liquid 2 0 51 5: 2 channel 13 and the first mixing chambers 15.

The operation of the apparatus shewn in Figures 2 and 3 is substantially the same as discussed with reference to the separate mix atcmizer shewn in Figure 1. When using the apparatus 5 shewn in Figures 2 and 3 for the atcmization of oil with steam, the mix atcmizers 12 are supplied with oil and steam via a camion liquid supply, viz. annular channel 13, and a common steam supply, viz. central channel 11, respectively.

It should be noted that the present invention is not 10 restricted to mix atcmizers having second mixing chambers with frusto-conically shaped walls downstream of the secondary steam inlets. Instead thereof, other shapes of tapering walls may be applied, provided that there is a smooth passage for the secondary steam frcm the secondary steam inlets to the outlet 15 nozzle of the mix atcmizer, guaranteeing that the secondary steam will form a shield flcwing along the walls of the second mixing chamber and the outlet nozzle.

Although in the embodiments shewn the mix atcmizers are provided with central primary steam inlets in ccntoination with 20 side inlets for liquid, these inlets may also be otherwise arranged, for example a combination of central liquid inlets with side primary steam inlets may be chosen for.

Further, the invention is not restricted to an apparatus with mix atcmizers having the particular arrangement of a 25 central steam channel and an annular liquid channel as shown in Figure 2. Any other suitable arrangement may be applied, provided that the mix atcmizers can be supplied with steam and liquid frcm a carman steam channel and a carmon liquid channel, respectively.

Finally, it is noted that the invention is not restricted to an apparatus for atcmization of a liquid having a frusto-conically shaped head. Instead thereof the apparatus can be provided with a flat-shaped head. With such a head the mix atcmizers are preferably arranged at an acute angle with respect 2 0 51 8 to the outer surface of the head having their outlet nozzles pointing away frcm one another to enable the positioning of a relatively large number of mix atcmizers in the apparatus without the risk of interference between the fluid flows issuing frcm the atcmizers during operation.

Claims (10)

205182 - 9 - I-JirYT WE CLAIM IS:

1. Mix atcmizer for the atcmization of a liquid (as herein defined) with gas, comprising a first mixing chamber provided with inlet means for supplying a liquid and primary gas to form a mixture of liquid and gas, said first mixing chamber debouching into a second mixing chamber having cross-sectional areas being substantially larger than the cross-sectional areas of the first mixing chamber, means for tangentially supplying secondary gas around the mixture of liquid and gas passing through the second mixing chamber during operation, the second mixing chamber debouching into an outlet nozzle having cross-sectional areas being substantially smaller than the cross-sectional areas of the second mixing chamber, the first mixing chamber, the second mixing chanter and the outlet nozzle having substantially coinciding longitudinal axes.

2. Mix atcmizer as claimed in claim 1, wherein the first mixing chairiber is provided with separate inlet means for the liquid and primary gas, the inlet means being inclined tcwards one another.

3. Mix atcmizer as claimed in claim 1 or 2, wherein the second mixing chanter is provided with a tapering wall portion for smoothly guiding secondary gas to the outlet nozzle.

4. Mix atcmizer as claimed in any one of the claims 1-3, wherein the mix atcmizer is provided with a plurality of tangentially disposed passages for tangentially supplying secondary gas into the second mixing chanter, said passages being substantially uniformly distributed over the circumference of the second mixing chanter.

5. Mix atcmizer as claimed in any one of the claims 1-4, wherein the cross-sectional areas of the outlet nozzle are substantially larger than the cross-sectional areas of the first mixing chamber. 205182 - 10 -

6. Apparatus for the atcmization of a liquid (as herein defined) with gas, canprising a member having a longitudinal axis and being internally provided with a plurality of mix atcmizers as claimed in any one of the claims 1-5, terminating at the outer surface of a head of the 5 member, the member being internally provided with one liquid supply channel for liquid and one gas supply channel, first passages forming fluid ccmnunications between the liquid supply channel and the first mixing chambers of the mix atcmizers, second passages for supplying primary gas frcm the gas supply 10 channel into said first mixing chambers and third passages for tangentially supplying secondary gas frcm the gas supply channel into the second mixing chambers of the mix atcmizers.

7. Apparatus as claimed in claim 6, wherein the centres of the outlet nozzles are positioned in a circular pattern substantially 15 equally spaced apart frcm one another.

8. Apparatus as claimed in claim 6 or 7, wherein the head of the member has a substantially frusto-conically shaped outer surface, the mix atcmizers being arranged substantially perpendicular to said outer surface. 20

9. Apparatus as claimed in claim 6 or 7, wherein the head of the member has a substantially flat outer surface, the mix atcmizers being arranged at an acute angle with respect to the outer surface of the head and having their outlet nozzles pointing away frcm one another. 25

10. Apparatus as claimed in- any one of the claims 6-9, wherein one of the supply channels is substantia 1 ly centrally arranged in the member, and the other supply channel is ring-shaped, the supply channels having substantially coinciding longitudinal axes. DATED THIS DAY OF A. J. PARK & SON PER AGENTS FOR THE A*PLlCANTS*