GB2271389A

GB2271389A - Fluidic circulation device.

Info

Publication number: GB2271389A
Application number: GB9320245A
Authority: GB
Inventors: Kenneth Herbert Haywood; Paul Christopher Haywood; Mark David Haywood; Kim Stephen Haywood
Original assignee: ZETA DYNAMICS Ltd
Current assignee: ZETA DYNAMICS Ltd
Priority date: 1992-10-01
Filing date: 1993-10-01
Publication date: 1994-04-13
Anticipated expiration: 2013-10-01
Also published as: GB9320245D0; GB2271389B

Abstract

A fluidic circulation device has a chamber containing a fluid flow device in the form of a Coanda nozzle (B). Primary fluid is supplied to the Coanda nozzle B through an inlet (A) to create fluid circulation in the chamber before discharging through an outlet (C). Thus fluid emerging from the nozzle (B) flows round the outside of an attachment surface entraining surrounding fluid present in the chamber to produce circulation round a path (K-E-F-D) including a non-return flap valve (D). The path also includes a processing zone such as a tube heat exchanger (H) having an inlet (G) and an outlet (J) for coolant. Alternatively the processing zone may be a gas scrubber Fig. 3 (not shown), a flare/combustor/incinerator, a filtration system, a catalytic reactor, mass transfer hardware, or a mixer. The device provides a fluidic circulation method of increasing efficiency and enables fluids to have a longer contact time with activating surfaces or other fluids. <IMAGE>

Description

FLUIDIC CIRCULATION DEVICE The present invention relates to a fluidic device and more particularly relates to a fluidic circulation device.

It is known that a stream of fluid emerging from the mouth of a narrow slot under pressure tends to cling to an extended lip or surface of the slot, thereby creating a pressure drop in the surrounding fluid. The pressure drop tends to cause a surrounding fluid to flow towards the low pressure region. This physical phenomenon is known as the Coanda effect. Also, it is known to use fluid flow devices as detailed in GB patent numbers 2201733, 2055726, 2243602 and 2242424.

The present invention provides a fluidic circulation device which gives relatively greater efficiency in fluidic transfer or reaction processes.

Thus according to the present invention there is provided a fluidic circulation device comprising a chamber having an inlet and an outlet, a fluid flow device having a Coanda nozzle in which a fluid emerging from the nozzle is capable of entraining a surrounding fluid, inlet means to provide fluid for driving the Coanda nozzle, a processing zone downstream of the Coanda nozzle whereby the fluid emerging from the Coanda nozzle entrains surrounding fluid and passes it into the processing zone.

The processing zone preferably comprises a heat exchanger, a gas scrubber, a flare/combustor/incinerator, a filtration system, a catalytic reactor, mass transfer hardware, or a mixer.

There are various processes where a fluid of single or multiple phases depends upon an interaction with either a chemical, a catalyst, or a surface for reactive processes. Such processes may be connected with, for example, mass transfer, phase separation, filtration, heat exchange, fluid bed, combustion, or mixing. It is desirable that within such process applications, fluid should have an extended period for fulfilling the purpose of the process, within an economic size.

The present invention provides a fluidic circulation device of increasing efficiency in hardware associated with such as the above processes. It will enable fluids to have a longer contact with activating surfaces or other fluids. The Coanda nozzle may be of the external or internal type but is preferably of the type described in our GB patents nos. 2201733 and 2055726. The invention enables a major unit involved in such as the above, to be designed or redesigned, to provide recirculation of the entering fluid or fluids within the operating phase, without necessarily any external input of energy, nor with any significant change to the flow conditions entering or leaving the unit.

The incoming fluid that is to be processed may be used to drive the Coanda unit or the driving fluid could be separately provided. The coanda unit may be a double feed unit when one feed is the incoming fluid and the other a fluid from another source for purposes of, for example, fluids for mixing, fluids with solid particles or granules, or a fluid for processing the incoming flLid.

In one embodiment of the invention, the Coanda fluid flow device comprises a supply tube for a first liquid, the tube having an aperture or slot, the aperture or slot having means directing emergent fluid flow over the curved outer surface of the tube whereby surrounding second fluid is entrained into the first fluid, the means for directing emergent fluid flow comprising a movable flap between the said means and the supply tube, there also being means downstream of the aperture or slot for facilitating fluid flow away from the tube comprising a fin attached to the surface of the tube.

In another embodiment of the invention, the Coanda fluid flow device comprises a supply tube for a first liquid, the tube having an aperture or slot, the aperture or slot having means directing emergent fluid flow over the curved outer surface of the tube whereby surrounding second fluid is entrained into the first fluid, the means for directing emergent fluid flow comprising a fixed width outlet gap between the said means and the supply tube, there also being means downstream of the aperture or slot for facilitating fluid flow away from the tube comprising a fin attached to the surface of the tube.

The invention will now be described by way of example only and with reference to Figures 1 to 8 of the accompanying drawings.

Figure la shows a view in cross section of a Coanda nozzle of a fluidic circulation device and Figure lb shows a double Coanda nozzle# of a fluidic circulation device.

Figure 2 shows a section through a fluidic circulation device in the form of a liquid/liquid heat exchanger.

Figure 3 shows a section through a fluidic circulation device in the form of a gas scrubber.

Figure 4 shows a section through a fluidic circulation device in the form of a flare/combustion/incineration system.

Figure 5 shows a section through a fluidic circulation device in the form of a filtration system.

Figure 6 shows a section through a fluidic circulation device in the form of a catalytic reactor unit.

Figure 7 shows a section through a fluidic circulation device in the form of a mass transfer hardware.

Figure 8 shows a section through a fluidic circulation device in the form of a mixing unit.

Figure la and lb show the operation of the Coanda nozzle which provides the fluid drive for the fluidic circulations device. This device is described in detail in our UK patent GB 2201733, and 2055726 and patent application 9220802.4.

With reference to Figure la, the primary flow A of pressurised fluid supply leaves the tube L through slot C into the cover assembly D and leaves both sides at a gap F in a tangential direction. Due to the Coanda effect, the primary flow is directed around the tube surface where it entrains the surrounding flow M and moves it in the direction G to J and being directed by the fin or guide H.

With reference to Figure lb, the fluid flow through the Coanda device involves the use of a inner tube K feeding fluid A and an outer tube feeding fluid B. Fluid A enters a channel through a slot N in tube A and is directed to the cover assembly C and into the outer section E and leaves at F tangentially to the outer surface of tube L where due to the Coanda effect it entrains the surrounding fluid M which is directed from G to J guided by fin H.

In the outer tube L within the annulus bounded by tube K, fluid B leaves through the slot D either side of assembly C and is directed toward F where its tangential direction is guided by the Coanda effect along the outer surface of tube B and entrains the surrounding flow M. Either of the two jets of primary fluid may be pressurised or induced by the other's pressure. Alternatively, both flows may be pressurised.

The Coanda effect refers to the phenomenon of the tendency for a stream of fluid to stick to a curved surface when it is directed at it tangentially. The kinetic energy of the fluid due to its velocity, results in a drop in pressure energy, and being as it is lower than the surrounding fluid, the stream is pushed against the curved surface.

As detailed above, the Coanda nozzle has important characteristics in its ability to control and propel a much larger flow of environmental fluid by the energy of its primary Coanda flow. This is important for the operation of the invention. Other forms of driving device may possibly be used in place of the Coanda nozzle, but their characteristics would need to match those of the present driver.

Figure 2 shows an outline of a liquid/liquid heat exchanger with interface tubes H for energy exchange. The assumption of the design in the diagram is that a primary liquid which enters the heat exchanger at A is being cooled by a liquid which enters at G.

The primary liquid is the one which uses the invention in this example.

The cooling liquid enters at G and flows around the heat exchange tubes within a closed assembly H and leave at outlet J. The heat of the primary liquid is absorbed through the temperature gradient across the tubes' material into the cooling liquid and taken away through the outlet J.

The primary liquid which requires cooling is controlled by the invention in the following way. The diagrams Figures la and 2 should be referred to. The primary liquid enters at A, and flows into the Coanda Unit B which is within a duct K and because of the Coanda effect, the primary liquid is directed around the tube of the Coanda Unit B and is guided towards the header volume E. The primary flow entrains the surrounding liquid occupying the heat exchanger within the duct, and both pushes the combined flow towards the header volume E, whilst sucking surrounding liquid into the duct from the outlet chamber F, thus circulating the flow through the tubes H.

The diagram shows a simple non-return flap valve D through which the surrounding liquid will pass from F into the duct K, but not in the reverse direction.

The same mass rate of the primary flow entering inlet A will leave from the outlet duct F into the outlet C. Instead of the primary flow entering the heat exchanger through the more typical inlet shown as, for example, by a 'shadow' inlet M passing through a bank of tubes similar to H, and out to the outlet C, the invention provides a recirculation through the tubes and will pass through, for example, between three and ten times normal, before leaving outlet C. The number of times is a function of the particular design setting of the Coanda Unit.

Although the valve D is shown on this example, it is not vital to the basic operation of the invention, which will operate without it. However, to explain its function, using this example, should the tubes block then a back pressure will occur, which would then close the flap valve D, thus preventing non-treated liquid to pass through to the outlet C. It could then be redirected through a pressure safety valve L to elsewhere.

Figure 3 shows an example of an application for a gas scrubber or similar requirement.

The entering gas, also called the primary gas flow, requiring treatment, enters at A into the Drive Unit B, where the surrounding gas which fills the scrubber chamber, is driven through the duct K, in a direction towards bottom chamber F when it reverses through the annulus H and to return to the inlet of duct K, influenced by the suction power of the drive unit B. The amount of gas entering at A, will leave at the outlet C through a demister unit D. The liquid spray for treating the gas is shown as two alternatives.

One is by using a traditional form of spraying liquid with a spray nozzle L, from the liquid feed G. The other is by using the double coanda feed which enables the drive unit B to mix the liquid with the surrounding flow. This is shown diagrammatically by the water inlet J, leading to the drive unit B. This technology which uses the double coanda feed is shown in Figure lb. The result is an average recirculation of approximately four to six times for improved treatment.

Figure 4 shows an example of a flare/combustor/incinerator process. In this example, the drive unit B has a dual fluid feed to the inlet of the Coanda nozzle. Both a basic gas supply and a fluid waste, either liquid or gas, enters by separate lines and leaves their individual jet nozzles of the drive unit B, and drives the surrounding fluid up the inner combustion chamber K, the sides of which are shown D. Air enters at A into the volume F and is sucked together with the surrounding flow into the inner combustion chamber K. The surrounding flow is directed into the outer combustion chamber H at deflector G where it passes down to chamber F and back into the inner combustion chamber K. The exhaust leaves at outlet C with the mass flow of the entries at J and A, the gas/waste inlet and air flow respectively.The same principle with a single coanda as in Figure la and a single feed of gas enables flaring to take place. With a double coanda, one feed can take low pressure gas and the other high pressure gas.

Figure 5 shows an example of a fluidic circulation device in the form of a filter system.

The inlet fluid enters at A into the Coanda nozzle at B where the primary flow drives the surrounding flow upwards through the duct K into the volume E. The surrounding flow enters the filter bed H and through to the chamber G, where the bulk of the fluid is sucked through the flap valve D into the duct K where the Coanda unit B propels it upwards to E to repeat the process. Leaving the chamber G is a flow through a perforated plate or similar J and which enters into the outlet chamber F and on through the outlet pipe C. The flap valve D is optional but in case of blockage can protect the outlet C by directing flow through a relief outlet L.

Figure 6 shows an example of a catalytic reactor unit in which a gas enters and makes contact with a catalyst to accelerate an enhanced reaction, such as that of exhaust catalytic converter on a car. A gas is fed through an inlet pipe A into a coanda unit B which is within a duct K. The inlet gas leaves the coanda unit B and drives the surrounding gas either side of the guide fin R which fills the reactor volume through the duct K into the header chamber E. The gas flow reverses to enter the catalyst lattice framework, which is coated with a catalyst, with the combined effect of both the driving flow from the coanda unit B upstream, and the suction of the coanda unit B downstream from the chamber F. The diagram shows the non-return valve D through which the gas flow will pass but not in the reverse direction. The same mass rate of flow enters inlet A, then leaves outlet C.Within the reactor the gas circulates through the lattice at between three and ten times depending on design specification.

Figure 7 shows an example of a mass transfer hardware. The entering gas, also called the primary flow, requires contact with granules which are shown in the annulus H outside of the duct K. The gas enters at A into coanda unit B and the resultant coanda effect directs the gas as the primary fluid. To drive the surrounding gas through the duct K to chamber E where the flow reverses into the granule bed H by virtue of the propulsion by the coanda unit B towards E and the suction of the gas from F.

Recirculation of the surrounding gas takes place with an amount of processed gas equal to that of the inlet at A leaves at outlet C.

Figure 8 shows an example of a mixing unit in which a fluid may be mixed with another fluid for processing. The first fluid in particular, could be water and the second fluid could contain solids in the form of granules which would for example be hydrophobic and absorb during mixing an immersible fluid within the water. The chamber with which the process takes place may either be one in which the only inlet flow is that from the the coanda unit B for mixing or it could be within a process system in which the main inlet flow G is directly into the chamber and passes through to outlet L with the coanda acting as the main driving force for the incoming main flow. Alternatively, the assembly could be incorporated into a skimmer.

The first coanda flow of water enters at A and the second flow enters at J and both leave their respective nozzles of coanda unit B. The main flow enters at G and is directed into duct K by the action of coanda unit B. The composite flow is driven through duct K and recirculated by means of propulsion and suction of coanda unit B thus mixing thoroughly. The combined flow leaves at L.

Claims

Claims

A fluidic circulation device comprising a chamber having an inlet and an outlet, a fluid flow device having a Coanda nozzle in which a fluid emerging from the nozzle is capable of entraining a surrounding fluid, inlet means to provide fluid for driving the Coanda nozzle, a processing zone downstream of the Coanda nozzle whereby the fluid emerging from the Coanda nozzle entrains surrounding fluid and passes it into the processing zone.
2 A fluidic circulation device according to claim 1 in which the processing zone comprises a heat exchanger, a gas scrubber, a flare/combustor/incinerator, a filtration system, a catalytic reactor, mass transfer hardware, or mixer.
3 A fluidic circulation device according to claim 1 or 2 having a baffle downstream end of the Coanda nozzle adapted to encourage fluid flow through the processing zone.
4 A fluidic circulation device according to any of claims 1 to 3 in which the Coanda nozzle is of the internal or external type.
5 A fluidic circulation device according to claim 1 in which the fluid flow device comprises a supply tube for a first liquid, the tube having an aperture or slot, the aperture or slot having means directing emergent fluid flow over the curved outer surface of the tube whereby surrounding second fluid is entrained into the first fluid, the means for directing emergent fluid flow comprising a movable flap between the said means and the supply tube, there also being means downstream of the aperture or slot for facilitating fluid flow away from the tube comprising a fin attached to the surface of the tube.
6 A fluidic circulation device according to claim 1 in which the fluid flow device comprises a supply tube for a first liquid, the tube having an aperture or slot, the aperture or slot having means directing emergent fluid flow over the curved outer surface of the tube whereby surrounding second fluid is entrained into the first fluid, the means for directing emergent fluid flow comprising a fixed width outlet gap between the said means and the supply tube, there also being means downstream of the aperture or slot for facilitating fluid flow away from the tube comprising a fin attached to the surface of the tube.
7 A fluidic circulation device according to claim 6 in which the Coanda nozzle comprises a pair of inlets for primary fluids, the fluids emerging from the nozzle on opposite sides of the movable flap.
8 A fluidic circulation device as herein before described and with reference to Figures 1 to 8 of the accompanying drawings.