WO1991012084A1

WO1991012084A1 - Nozzle device

Info

Publication number: WO1991012084A1
Application number: PCT/SE1991/000089
Authority: WO
Inventors: Sven Johansson
Original assignee: Johansson Sven Halvor
Priority date: 1990-02-12
Filing date: 1991-02-11
Publication date: 1991-08-22
Also published as: SE9000492A; SE9000492D0; AU7301391A; SE465502B

Abstract

A nozzle device for emitting a gas/liquid mixture into a process gas so as to separate therefrom at least one constituent by means of this mixture comprises means (11, 12) for connecting the nozzle device to a gas source and a liquid source, ducts (18, 19) for carrying the gas and the liquid to a mixing region (20), in which the gas and the liquid are brought together, and an outlet arrangement (22) for emitting the mixture as a spread spray. The device comprises a chamber (23) downstream of the mixing region. The outlet arrangement is formed by a plurality of holes (24), which extend from the chamber to the outlet end of the nozzle device and the smallest total cross section area of which is smaller than the largest cross section area of the chamber.

Description

Nozzle device

TECHNICAL FIELD OF THE INVENTION AND PRIOR ART

This invention relates to a nozzle device for emitting a gas/liquid mixture into a process gas so as to separate therefrom at least one constituent by means of this mixture, said device comprising means for connecting the nozzle device to a gas source and a liquid source, ducts for carrying the gas and the liquid to a mixing region, in which the gas and the liquid are brought together, and an outlet arrangement for emitting the gas/liquid mixture as a spread spray or plume. As it will be discussed more in detail below, the process gas may consist of combustion gases or other gases in any processes, in particular in industrial ones. The constituent, or the constituents, to be separated may be contaminants but also the product aimed at in the process.

At least within the technique of separating arsenic from arsenical gas it is known to emit a gas/liquid mixture into the arsenic gas for the recovery of arsenic. The liquid catches or binds the arsenic from the arsenic gas and after that the arsenic is separated from "the liquid in a manner known per se. To this end such nozzle devices were utilized until now, in which the gas/liquid mixture resulting in the mixing region immediately leaves the proper nozzle body through one single centrally located outlet hole. The known nozzle devices are provided with a cup-like distribution member carried by support legs with respect to the nozzle body at a considerable distance in front of the outlet hole so as to obtain a .spread spray or plume. An essential drawback of the known nozzle device is constituted by its comparatively high price, which probably is caused by the complicated construction of the cup-like distribution member and an unacceptably short lifetime. The reason for the short lifetime is that the legs holding the distribution member in operation are subjected to a rapid abrasion as a consequence of the gas/liquid mixture passing it, so that the nozzle device will simply break down and has to be replaced. The abrasion will be particularly rapid in the case of arsenic, since the liquid used also contains a certain proportion of arsenic. Drastically increasing the content of material in the legs does not constitute any possible way, since that would substantially deteriorate the spreadinq characteristics of the nozzle device.

Examinations carried out in connection with the known nozzle device have also led to indications in the direction that it is neither a satisfying solution with respect to the atomization and spreading of the gas/liquid mixture.

SUMMARY OF THE INVENTION

The object of the present invention is to further develop the nozzle device defined in the introduction so that it gets a longer lifetime and at the same time improved or at least remaining mixing, atomizing and spreading characteristics.

The object according to the invention is obtained by providing the nozzle device downstream of the mixing region with a chamber and by the fact that the outlet arrangement is formed by a plurality of holes extending from the chamber to the outlet end of the nozzle device and the smallest total cross section area of which being smaller than the greatest cross section area of the chamber.

Further advantageous embodiments of the nozzle device according to the invention are objects of the dependent claims. Practical experiments have shown that the nozzle device accor¬ ding to the invention has a substantially longer lifetime than the known nozzle device discussed above. Furthermore, the nozzle device according to the invention may be manufactured to a lower cost than the comparatively complicated nozzle device already known. In these experiments carried out for recovery of arsenic from arsenious gas, a considerably improved arsenic yield could also be noticed. The latter circumstance proves that the nozzle device according to the invention is better than the known one as far as it concerns at least one of the factors mixing, atomizing and spreading or dispersing.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a specific description of an embodiment according to the inven¬ tion cited as an example.

In the drawings:

Fig 1 is a schematic, partially sectioned view illustrating a possible installation of the nozzle device,

Fig 2 is a principal section taken along the line II-II in Fig 1,

Fig 3 is an enlarged view of the nozzle device arranged on a so- called lance.

Fig 4 is a perspective exploded view of the nozzle device.

Fig 5 is a longitudinal section through the nozzle device in the assembled state thereof, and

Fig 6 is a front view of the outlet end of the nozzle device. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The nozzle device according to invention will hereinafter be described for the application to recovery of arsenic from an arsenious gas. A process structure 1 (in the practice termed cooling tower) defining a process room 2 is illustrated in Fig 1. The arsenious gas is received in an inlet tube 3 at an upper part of the structure 1 and is after that led downwardly into the process room 2. Nozzle devices 4 according to the invention are arranged in the upper region thereof for emitting a spray or plume of a gas/liquid mixture into the arsenic gas. In this case the gas of the mixture is air while the liquid is water. The emitted, atomized or nearly fog-like mixture catches or binds the arsenic in the arsenic gas and the mixture of arsenic and water obtained is collected in a way known per se in the lower regions of the process room 2 not further shown so as to separate the arsenic, whereupon the water may be returned into the process. It appears from Fig 2 that in this example three nozzle devices 4 according to the invention are arranged angularly uniformly distributed so as to cooperate for emitting sprays or plumes making contact with the arsenic gas as completely as possible.

It appears from Fig 1 that the nozzle devices 4 are so directed that they emit the air/water mixture in the flow direction of the arsenic gas. It appears from Fig 3 how a nozzle device 4 according to the invention is arranged on a so called lance 5, at the rear end of which supply ducts 6, 7 for air and water, respectively, are indicated. It appears from Fig 3 how the corresponding ducts 6, 7 at the front end of the lance 5 deliver the air and the water, respectively, to the very nozzle device 4. The ducts 6, 7 communicate with suitable air and water sources, i.e. in the practice pump assemblies being able to deliver the air and the water, respectively, with the pressures required. It should be mentioned that it in the practice was found to be suitable to deliver .the air with a pressure of about 6 bars and the liquid with a pressure of about 16 bars to the nozzle device 4.

The very nozzle device 4 will now be described by means of the Figs 4-6. The main components of the nozzle device 4 are a mixing means 8 and a proper nozzle means 9. It is advantageous that these two means are loosenably connected to each other, e.g. by a threaded connection, since the nozzle means 9 is worn out most rapidly and has to be changed more often than the mixing means 8. The nozzle device 4 has also means 10 for connection to the ducts 6, 7. The means 10 has the character of an adapter or a connector, which is, suitably loosenably „ connected with the mixing means 8. The connection means 10 comprises connection members 11, 12 (Fig 5), e.g. in the form of internally threaded bores, for interconnecting it with externally threaded nipples of the ducts 6, 7. The connection bore 11 located slightly excentrically turns into a centrically located transmitting hole 13 for the air. The connection bore 12 for the water supply communicates with an annular room 14 surrounding the transmitting hole 13.

The nozzle device 4 does further comprise a washer 15 provided with holes and clamped between the mixing means 8 and the connection means 10 in the assembled state of the nozzle device. The connection means comprises an internally threaded end portion 16 cooperating interconnectingly with an external thread on the mixing means 8. In the assembled state according to Fig 5 a peripheral crown of holes 16 in the washer 15 will be located exactly opposite the annular room 14 in the connec¬ tion means 10, while a central hole 17 in the washer will be located exactly opposite the transmitting hole 13 of the connection means.

The mixing means 8 comprises ducts 18 and 19, respectively, for conducting the air and the water to the mixing region 20, in which the air and the water are brought together. From the manufacturing point of view it is in the practice suitable to make the mixing means 8 as two parts, namely an outer envelope and an insert received therein, said water duct 19 located externally to the air duct 18 consisting of the space between the envelope and the insert. The water duct 19 is preferably continuously annular apart from angularly separated supports 21 mutually locating the envelope and the insert and being a part of the insert in this example. Thus, there is a space allowing water to pass between adjacent supports 21.

The device comprises also an outlet arrangement 22 for emitting the gas/liquid mixture as a spread spray or plume. Furthermore, the device comprises a chamber 23 downstream of the mixing region 20. The outlet arrangement 22 is formed by a plurality of holes 24 extending from the chamber 23 to the outlet end of the nozzle device and the smallest total cross section area of which being smaller than, the greatest cross section area of the chamber 23. Expressed in another way, if the holes 24 have different areas along there length the smallest cross section area of each different hole has to be used so as to obtain the area which is called the total cross section area above. In an analogous way, should the chamber 23 have a varying cross section area only the greatest area is to be considered. With the expression "cross section" in this situation the dimension substantially transversal to the main flowing direction through the nozzle device is intended.

As it appears from Fig 4 and 5 the proper nozzle means 9 possesses said holes 24. The nozzle means has further a portion internally threaded in this example and cooperating with an external thread on the mixing means 8 so as to obtain faste¬ ning. An annular portion of the nozzle means 9 will in the assembled state of the device bear against the outer end portion of the mixing means 8. In this example the chamber 23 is defined by surfaces of the nozzle means <.10 as well as surfaces, more exactly radial ones, of the mixing means 8. Thus, the chamber 23 is in this example created when the nozzle means 9 and mixing means 8 are assembled, more exactly because the nozzle means 9 has a recess. A recess participating in the formation of the chamber 23 could also be arranged in the mixing means 8.

The chamber 23 has a cross section area at least partially decreasing in the flowing direction of the mixture. As it appears from Fig 5 the downstream portion of the chamber has a substantially conical shape. Thus, the chamber 23 has in the preferred case a revolution symmetry. Furthermore, the chamber 23 has in the direction of the mixing means 8 a substantially cylindrical portion.

The duct 18 in the mixing means 8 is through a constriction 26 transformed into the mixing region 20, which is so designed and arranged that the mixture obtained almost immediately passes into the chamber 23. The mixing region 20 is accordingly arranged exactly opposite the chamber 23 and comparatively close thereto. In this example there is an immediate proximity, since the mixing region 20 has a mouth directly communicating with the chamber 23.

The mixing region 20 has a cross section area being at least in the transition to the chamber smaller than the greatest cross section area of the chamber 23. As it appears from Fig 5 it is accordingly meant that it shall be a cross section increase in the flowing direction in- the transition between the mixing region 20 and the chamber 23.

The mixing region 20 is arranged to bring air and water to¬ gether in flowing directions making an angle with each other. More exactly, the mixing region 20 comprises a room 27 arranged to let the air flow axially therethrough, and a number of outlet openings 28 for water arranged in the wall of the room. These openings 28 communicate with transverse ducts 29 being in connection with the longitudinal water duct 19. As it appears from Fig 5 the holes 28 are mutually displaced in the circumferential direction as well as in the axial direction. Furthermore, it appears that the room 28 suitably has a cross section area increasing in the flowing direction.

The mixing region 20 and the chamber 23 are substantially coaxially arranged.

The holes 24 in the nozzle means are suitably arranged in an annular configuration (Fig 6). Furthermore, the outlet ends of the holes 24 have emerging portions 30 widening outwardly. These emerging portions are advantageously substantially conical and the cone angle amounts suitably to 60-120°. A cone angle within the range 80-100° is particularly suitable. An optimum has turned out to be located at about 90°.

The holes 24 diverge with respect to each other in the outlet direction of the mixture. This divergence is related to the direction of the main extension of the holes 24. Accordingly, a diverging flow pattern of the emitted mixture arises on one hand as a consequence of the principal divergence of the holes 24 and on the other as a consequence of the widened emerging portions 30, which leads to a divergence concerning the volume emitted from a single hole. The result is accordingly a well distributed and very uniformly diverging spray or plume from the nozzle device.

In this example the holes 24 have except for the widened emerging portions 30 a substantially rectilinear extension and cylindrical shape. The longitudinal direction of each hole 24 makes suitably an angle between 5° and 45° with the longi¬ tudinal axis of the nozzle device. An angle range of 10 to 30° is here preferred. An angle of about 15-20° has turned out to be particularly preferable. This means accordingly that the divergence angle of the holes is about 30-40°. The holes 24 emerge into an outer nozzle surface 31, which forms an end portion of the nozzle means 9 converging in the outlet direction. It has been found to be suitable that the holes 24 extend substantially perpendicularly to the nozzle surface 31, which preferably is substantially conical with the cone point substantially coinciding with the longitudinal axis of the nozzle device. The cone angle of the surface 31 is advantageously located within the range 100-160°. The cone angle is suitably 130-150° and mostly preferred about 140°.

The inlet ends of the holes 24 join the chamber 23 at locations between the smallest and greatest cross section area thereof. The chamber 23 has a central portion 32 surrounded by the inlet ends of the holes and forming a concave recess in the chamber. This recess is arranged right opposite the mixing region 20. It is preferred that the substantially conical portion of the chamber 23 has a cone angel between 100 and 170°. A cone angle between 130 and 150° is particularly suitable.

When the nozzle device according to the invention is in opera¬ tion air and water flow under high pressure into the same and reach by means of the channelization described above the mixing region 20, in which a mixing function is achieved by spraying the water laterally into the air stream. The mixture obtained then enters into the chamber 23, in which violent turbulence is created as a consequence of the cross section increase and the retaining function of the chamber, said turbulence contributing in a favourable way to atomize the water further in the air and achieve a uniform mixture. The conical shape of the chamber 23 has a favourable influence thereon thanks to the compressing function arising. When the mixture after that flows into the holes 24 a pressure and velocity increase is achieved owing to the decreasing cross section area, said increase being followed by an almost explosive effect when the mixture (or primarily the air) expands in the emerging portions 30 widening outwardly. The result is an eminently atomized and uniform spray or fog from the nozzle. It has turned out that the nozzle device according to the invention permits most varying proportions concerning the amounts of supplied air and supplied water while still main¬ taining an excellent atomization and uniformity. Thus, the proportion of water may be carefully adjusted in dependence of the circumstances. Varying circumstances may for the rest necessitate adaptations of the nozzle device, for instance concerning the divergence, diameter and number of the holes 24.

It has been described above how the nozzle device is utilized to separate a product, namely arsenic, from a gas containing the product. Several other applications lie within the scope of the invention. It may for instance be mentioned that successful experiments have been carried out so as to separate zinc or zinc containing compounds from gases containing ' zinc. Other process gases which may be treated by means of the nozzle device according to the invention are combustion gases from power and heating plants, industrial plants etc. so as to separate constituents, such as ashes, soot, sulphur dioxide and so on. It should be understood that in all applications dis¬ cussed other gases and liquids than exactly air and water may be used. In for example flue gas desulphurizing a lime or soda containing liquid may be used for obtaining a chemical reaction binding sulphur dioxide and releasing carbon dioxide and water.

The nozzle device according to the invention is of course not restricted to the embodiment described, but several modifica¬ tions will be possible within the scope of the spirit of the invention.

Claims

1. A nozzle device for emitting a gas/liquid mixture into a process gas so as to separate therefrom at least one consti¬ tuent by means of this mixture, said device comprising means (10) for connecting the nozzle device (4) to a gas source and a liquid source, ducts (18, 19) for carrying the gas and the liquid to a mixing region (20), in which the gas and the liquid are brought together, and an outlet arrangement^' (22) for emitting the gas/liquid mixture as a spread spray or plume, c h a r a c t e r i z e d i n t h a t it comprises a chamber (23) downstream of the mixing region (20) and that the outlet arrangement (22) is formed by a plurality of holes (24) which extend from the chamber (23) to the outlet end of the nozzle device and the smallest total cross section area of which is smaller than the largest cross section area of the chamber.

2. A device according to claim 1, c h a r a c t e r i z e d i n t h a t the chamber (23) at least partially has a cross section area decreasing in the flowing direction of the mixture.

3. A device according to claim 1 or 2, c h a r a c t e r i z e d i n t h a t the mixing region (20) has a cross section area being at least at the transition into the chamber (23) smaller than the largest cross section area thereof.

4. A device according to any of the preceding claims, c h a r a c t e r i z e d i n t h a t the mixing region (20) is arranged for bringing the gas and the liquid together in flowing directions making an angle with each other.

5. A device according to claim 4, c h a r a c t e r i z e d i n t h a t the mixing region (20) comprises a room (27) arranged to have the gas..axially flowing therethrough, and one or several outlet openings (28) for the liquid arranged in the wall of the room.

6. A device according to any of the preceding claims, c h a r a c t e r i z e d i n t h a t the mixing region (20) and the chamber (23) are substantially coaxially arranged.

7. A device according to any of the preceding claims, c h a r a c t e r i z e d i n t h a t the holes (24) of the outlet arrangement are arranged in an annular configuration.

8. A device according to any of the preceding claims, c h a r a c t e r i z e d i n t h a t the outlet ends of the holes (24) have orifice portions (30) widening outwardly.

9. A device according to any of the preceding claims, c h a r a c t e r i z e d i n t h a t the holes (24) diverge with respect to each other in the outlet direction.

10. A device according to any of the preceding claims, c h a r a c t e r i z e d i n t h a t the outlet ends of the holes (24) emerge into an outer nozzle surface (31) forming an end portion of the nozzle device converging in the outlet direction.

11. A device according to any of the preceding claims, c h a r a t e r i z e d i n t h a t the inlet .ends of the holes (24) are connected to the chamber (23) at locations between the smallest and largest cross section areas thereof.

12. A device according to any of the preceding claims, c h a r a c t e r i z e d i n t h a t the chamber (23) has a portion (32) surrounded by the inlet ends of the holes (24) and forming a central recess in the chamber.