GB2273248A

GB2273248A - Mixing liquids

Info

Publication number: GB2273248A
Application number: GB9325159A
Authority: GB
Inventors: Georg Donauer; Ralph-Michael Schmidt
Original assignee: MTU Friedrichshafen GmbH; MTU Motoren und Turbinen Union Friedrichshafen GmbH
Current assignee: Rolls Royce Solutions GmbH
Priority date: 1992-12-10
Filing date: 1993-12-08
Publication date: 1994-06-15
Anticipated expiration: 2013-12-08
Also published as: GB2273248B; DE4241603C1; FR2699092A1; GB9325159D0

Description

2273248 1 Device for producing a mixture of fuel and additional liquid The

present invention relates to a device for producing a mixture of liquid fuel and additional liquid, according to the pre-characterizing part of claim 1, physical mixing being effected without the use of an emulsifying agent. As a result of using the mixture instead of pure fuel, the emission of undesired exhaust gas constituents is reduced.

EP-A 0 392 545 discloses a generic device which, owing to the elongate mixing chamber design and as a result of the arrangement of two mixing chambers one behind the other,-has a long structural length, which makes accommodation in internal combustion engines difficult. However, the long structural length also results in the device being filled with a large volume of mixture. On altering the mixing ratio, the volume of mixture in the device first has to be consumed before the mixture with the altered mixing ratio is available at the consumer.

2 As a result, the response behaviour of the device on alterations in mixing is sluggish, which restricts the range of use. An object of the present invention is to provide a device for producing a mixture of fuel and additional liquid with a short structural length and a small volume and with a high degree of mixing of the mixture.

The invention provides a device as claimed in claim 1.

Prefered embodiments of the invention are claimed in the sub claims.

The advantages achieved by the invention consist in particular in the fact that the compact mixing chamber, in conjunction with the multipath supply of the mixture to the pump and the small-volume pre-mixing chamber, results in a very small mixing volume which ensures short response times on alterations in mixing, that the base of the mixing chamber which can be matched to the jet design of the injection nozzle for the additional liquid results in a very short structural length of the device, that the multipath supply of the mixture out of the mixing chamber to the suction opening of the pump counteracts dissociation, and that by using injection nozzles with different injection characteristics the I JP, c 3 device can also be used for applications at high fuel and mixture pressure.

Two embodiments of the invention will now be described with reference to the accompanying drawing, wherein:

Fig. 1 shows in longitudinal section a device for producing a mixture of fuel and additional liquid, with a single-jet injection nozzle, and Fig. 2 shows in longitudinal section a device for producing a mixture of fuel and additional liquid, with a conical jet injection nozzle.

In Figs. 1 and 2, a device for producing a mixture of fuel and additional liquid for combustion in a consumer 17, 117, which can be for example a burner or an internal combustion engine, comprises a pump drive housing 11, 111, having a drive (not shown) for a centrifugal pump 14, 114, a mixing chamber housing 12, 112 and a nozzle carrier cover 13, 113. The centrifugal pump 14, 114 feeds the mixture produced in the device through a mixture outlet 15, 115 and a consumption line 16, 116 to the consumer 17, 117. Mixture which has not been consumed by the consumer 17, 117 passes by way of a return line 18, 118 and a return connection 19, 119 to a 4 pre-mixing chamber 20, 120. The fuel is also supplied to the pre-mixing chamber 20, 120 via a fuel line 21, 121 and a fuel connection 22, 122. Here, a pre-mixture with an increased proportion of fuel is formed in the pre-mixing chamber 20, 120.

The feed rate of the centrifugal pump 14, 114 is greater than the mixture rate supplied to the consumer 17, 117.

For recirculating the difference, a recirculation channel 31, 131 leading from the mixture outlet 15, 115 to the pre-mixing chamber 20, 120 is arranged in the mixing chamber housing 12, 112.

The additional liquid required for the mixture, e.g. water, is introduced by means of an injection nozzle 23, 123 secured in the nozzle carrier cover 13, 113 into the mixing chamber 24, 124 constructed in the mixing chamber housing 12, 112. The diameter of the mixing chamber is constructed to be equal to or greater than its axial length, which results in a compact construction of the device. Additional liquid is fed to the injection nozzle 23, 123 via a feed line 25, 125 and a time valve 26, 126 inserted in the feed line 25, 125 ensuring an intermittent flow of the additional liquid. Altering the frequency of the time valve 26, 126 regulates the h flow rate of the additional liquid supplied.

In the embodiment according to Fig. 1, the injection nozzle 23 produces a concentrated injection jet 29. On hitting the jet divider tip 27 constructed at the base of the cylindrical mixing chamber 24, the injection jet 29 is fanned out and deflected by the annular, rounded jet deflector recess 28, so that a wall flow 30 of the additional liquid along the mixing chamber wall, opposite to the direction of injection, is formed.

The opening 32 for the flow of pre-mixture from the pre-mixing chamber 20 to the mixing chamber 24 is constructed as an annular slot in the manner of an ejector nozzle, taking into account the direction of the flow 30 along the mixing chamber wall.

For the removal of mixture formed in the mixing chamber 24, there are arranged on the base in the vicinity of the outer edge of the jet deflector recess 28 a plurality of axial openings 33 which lead to the centrifugal pump 14. Separation of the mixture is counteracted by this multipath supply of the mixture to the centrifugal pump 14.

To stabilize the mixture, a rotating swirl plate 34 is 6 mounted upstream of the centrifugal pump 14, 114, 134 and creates an intensified mixing effect by means of its plurality of adjacent holes.

The device according to the second embodiment shown in Fig. 2 operates at a higher pressure of the additional liquid than the device according to Fig. 1. The higher pressure of the additional liquid enables an injection nozzle having a hollow-conical injection jet 129 to be used.

The mixing chamber 124 is matched to the conical shape of the injection jet 129, the diameter of the mixing chamber 124 again being greater than its length. The injection jet shape of the injection nozzle 123 produces a flow 130 of the additional liquid injected which is directed along the mixing chamber wall to the jet deflector recess 128 and is there deflected towards the centre axis of the mixing chamber 124.

The pre-mixture comprising recirculated mixture and fuel enters the mixing chamber 124 with a flow which is directed approximately perpendicularly to the wall flow 130, through an opening 132 leading from the pre-mixing chamber 120 to the mixing chamber 124. This cross stream causes an intensive swirl formation in the mixing 1 7 chamber 124, as a result of which the intimate continuous mixing of pre- mixture and additional liquid is effected.

The opening 132 for the entry of premixture from the pre-mixing chamber 120 into the mixing chamber 124 is constructed as an annular slot in the manner of an ejector nozzle, taking into account the direction of the flow 130 along the mixing chamber wall.

For removing the prepared mixture from the mixing chamber 124, an axial opening 133 is arranged at the base in the centre of the jet deflector recess 128, and radial grooves 135 leading to the centrifugal pump 114 radiate from the axial opening 133. Separation is counteracted by this multipath supply of the mixture to the centrifugal pump 114.

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Claims

1. A device for producing a mixture of liquid fuel and additional liquid for combustion in a burner or in an internal combustion engine, the device comprising a pump for supplying part-of the mixture for combustion and recirculating the remaining part of the mixture, a mixing chamber arranged coaxially upstream of the pump, an injection nozzle for the additional liquid having an outlet opening into the mixing chamber, a pre- mixing chamber arranged upstream of the mixing chamber and in flow connection therewith for feeding a pre-mixture comprising fuel and recirculated mixture from the pre-mixing chamber to the mixing chamber, characterized in that the mixing chamber has a base with an annular, rounded jet deflector recess, the diameter of the mixing chamber is equal to or greater than the axial length thereof, and at least one flow connection leads from the base of the mixing chamber to the inlet of the pump.

2. A device as claimed in Claim 1, wherein the injection nozzle is a single-jet nozzle.

3. A device as claimed in Claim 2, wherein the mixing chamber is barrelshapea.

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4. A device as claimed in Claim 3, wherein the jet deflector recess on the base of the mixing chamber has a jet divider tip arranged to be coaxial with the injection jet from the injector nozzle.

5. A device as claimed in Claim 2, wherein a plurality of axial openings are constructed in the base of the mixing chamber spaced from the jet divider tip.

6. A device as claimed in Claim 1, characterized in that the injection nozzle is a conical jet nozzle.

7. A device as claimed in Claim 6, wherein the mixing chamber has a conical shape is matched to the injection cone formed by the injection nozzle.

8. A device as claimed in Claim 6, wherein the annular jet deflector recess is radially spaced from a central axial opening.

9. A device as claimed in Claim 8, wherein the flow path for the mixture between the central opening and the pump comprises a plurality of radial grooves.

10. A device as claimed in any one of the preceding claims, wherein the opening for the flow of pre-mixture h into the mixing chamber is an annular slot constructed in the manner of an ejector nozzle.

11. A device as claimed in any one of the preceding claims, wherein a rotating swirl plate is arranged upstream of the pump in the flow path of the mixture.

12. A device for producing a mixture of fuel and additional liquid for combustion in a burner or an internal combustion engine substantially as herein described and shown in Fig. 1 or Fig. 2 of the accompanying drawing.

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