Mixing chamber
United States Patent 3905395
A chamber for forceably mixing two streams of liquid under pressure comprising two continuous, parallel, pressure-resistant grid walls having an inlet means for each liquid stream to be mixed and an outlet means for the mixed liquid stream. Each grid wall is a metal screen having a grid aperture in the micron, μ, range. The distance between the grid walls is in the mm-range and is at least five times less than the diameter of each grid wall. The flow resistance of the grid walls provides uniform distribution of each liquid over each grid wall. Owing to the negligible volume of the mixing chamber, forceable mixing of the liquids, partial volume per partial volume, is achieved with minimum time delay.
US Patent References:
Mixing device
Walker - December 1945 - 2391110
Emulsifying apparatus
Brochner - May 1950 - 2509288
Spinneret mixing element
Braunlich - December 1957 - 2815532
Apparatus for introduction of fluid
Winslow, Jr. - November 1962 - 3064680
Mixing device
Walker - December 1945 - 2391110
Emulsifying apparatus
Brochner - May 1950 - 2509288
Spinneret mixing element
Braunlich - December 1957 - 2815532
Apparatus for introduction of fluid
Winslow, Jr. - November 1962 - 3064680
Application Number:
05/426417
Publication Date:
09/16/1975
Filing Date:
12/19/1973
View Patent Images:
Export Citation:
Assignee:
Hewlett-Packard GmbH (Wurttemberg, DT)
Primary Class:
Other Classes:
366/341
International Classes:
B01F5/04; B01F5/06
Field of Search:
137/604 259/4
Primary Examiner:
Nilson, Robert G.
Attorney, Agent or Firm:
Fox, Stephen P.
Claims:
I claim
1. An apparatus for mixing two separate streams of liquid flowing under pressure comprising:
2. The apparatus as in claim 1 wherein the grid walls are formed of metal frets.
3. The apparatus as in claim 1 wherein the spacing between the grids may vary from 0.5 mm to 3 mm.
4. The apparatus as in claim 1 wherein the average grid aperture size may vary from 1 micron to 10 microns.
1. An apparatus for mixing two separate streams of liquid flowing under pressure comprising:
2. The apparatus as in claim 1 wherein the grid walls are formed of metal frets.
3. The apparatus as in claim 1 wherein the spacing between the grids may vary from 0.5 mm to 3 mm.
4. The apparatus as in claim 1 wherein the average grid aperture size may vary from 1 micron to 10 microns.
Description:
BACKGROUND OF THE INVENTION
Liquid mixing apparatus is generally of use, wherever a very intensive mixing of media is of importance. This is especially true for the manufacture of agents in the biochemical or pharmaceutical industries, where highly homogeneous products are desired. It is well known that chemical reactions are accelerated with intense mixing of constituents.
A variety of devices by which liquids can be mixed are known. For example, Austrian Pat. No. 270,595 discloses an apparatus for continuously diluting a medium having a high viscosity, wherein the viscous medium and the far greater quantity of diluting liquid are continuously supplied under pressure to a first common chamber via rectangular inlet means. After sequentially passing through two grid walls the diluting medium is caused to rotate. The turbulent liquid streams are then pressed through the grid walls in order to align the macro-molecules and to avoid interlacings among them.
U.S. Pat. No. 2,509,288 discloses a mixing apparatus, wherein the liquids to be mixed are fed through opposing nozzles into a ball-shaped chamber and the mixed liquid stream is delivered through an outlet pipe connected to the chamber. U.S. Pat. No. 2,391,110 discloses a mixing chamber for liquids which includes a cascade of screens with circumferentially extending channels.
The mixing action of prior art devices is achieved by an imposed convection of the liquid streams in a chamber volume. Since a chamber of substantial volume is required to allow the convection to take place, mixing action is delayed. Furthermore, no mixing between partial volumes of both liquids can be obtained because the flow of the liquids exhibit uncontrolled flow profiles which result from turbulence.
SUMMARY OF THE INVENTION
A mixing chamber designed according to the preferred embodiment of this invention mixes two separate streams of liquid under pressure. The mixing chamber comprises two continuous, parallel, pressure-resistant grid walls between which liquid mixing occurs, an inlet means for entry of each liquid stream to be mixed into the mixing chamber through the grid walls and an outlet means for exit of the mixed liquid stream from the mixing chamber. The distance between the grid walls is in the mm-range and is at least five times less than the lateral extension of each grid wall. The grid apertures of the grid walls is in the micron, μ, range and the flow resistance of the grid walls provides uniform distribution of each liquid flowing under pressure over the cross-sectional areas of their respective grid walls.
The principal object of this invention therefore is to provide an improved apparatus of simple design for mixing two liquids substantially without delay and with increased efficiency, wherein each partial volume of the one liquid is mixed with the partial volume of the other liquid.
DESCRIPTION OF THE DRAWING
FIG. 1 is a cross-sectional view of the preferred embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, the mixing apparatus 3 comprises essentially two metal screens 5 and 6 having a mesh size of 3μ and a surface of 20 mm 2 each. Since the distance between the metal screens is 1 mm, the volume of the mixing chamber volume is 20 μl. The apparatus casing 7 is closed by means of bolts 8a, b. Two solvent A and B, respectively, are pumped in parallel relation via inlet means 1 and 2 into a mixing apparatus 3. The mixed homogeneous solvent is exited via outlet means 4. The connecting line between pumps and the mixing apparatus have an interior cross-section of typically 0.5 mm with a larger cross-section at the point of connection to the mixing apparatus.
During the operation of the device, liquid pumps which do not necessarily operate in timed relation, press liquids to be mixed, A and B, intermittently through metal screens 5 and 6 respectively, thus forming a plurality of intermeshing, thin separate jets of liquid. Additional mixing is provided by the turbulence resulting from the transverse forces acting among the jet streams between the internal screen faces. Thus, a homogeneous solvent liquid is obtained by intense mixing within a very confined space.
The size and shape of the device described can be varied without parting from the scope and nature of the present invention. Preferably, however, the screens consist of metal frets, separated by a distance not greater than one fifth of the fret diameter. The said distance may be 0.5 to 3 mm and adjustable according to the volumes of the liquids to be mixed. The aperture size of the screen mesh must be sufficiently fine and the distance between screens must be sufficiently small to create a flow resistance in the mixing chamber that will ensure the uniform distribution of the liquids to be mixed over the entire area of the chamber. Finally, several such arrangements may be joined in cascade so that the mixed flow leaving one stage is divided into partial flows and fed to the next stage and achieve a still more thorough mixed of the liquids.
The mixing chamber, as described above, has a minimum dead volume and a maximum active mixing area. The liquids to be mixed are uniformly distributed over the grid walls so that a build-up of flow profile, as would be observed with convection flows, is avoided. Thus, a more homogeneous mixing operation is obtained. Extremely narrow grid apertures provide uniform quantization or division of the oppositely directed liquid flows. Because of the small space between the grid walls, which limit the volume of the mixing chamber, the liquid particles of both streams, after passing through the grid walls, directly impact against each other and, without convection flow, are mixed with each other. This result is obtained without any additional equipment, such as additional mixing chambers, stirring or the like.
The preferred embodiment of this invention has been used for the gradient elution in a liquid chromatography system, wherein two solvents are pumped through it in a discontinuous fashion in order to become intensely mixed without substantial time delay during the mixing operation. The amount of the one solvent may be increased and the amount of the other solvent decreased proportionately, thus keeping the total volume of both solvents constant, while the mixing operation takes place within the small volume of the mixing chamber. Alternatively, where desirable, the amount of the one solvent having a high dissolving power, for example methyl alcohol, is continuously varied, the quantity of the other solvent, for example octane, may also be proportionately varied to correspond with the variations in the quantity of the first solvent.
Using the preferred embodiment of this invention, in a gas chromatography, a time-programmed separation of the applied substances is obtainable in accordance with temperature programming. Dead volumes are minimized and thus undue time delays are avoided which would tend to distort the exact time programming and preclude reproducible results.
Liquid mixing apparatus is generally of use, wherever a very intensive mixing of media is of importance. This is especially true for the manufacture of agents in the biochemical or pharmaceutical industries, where highly homogeneous products are desired. It is well known that chemical reactions are accelerated with intense mixing of constituents.
A variety of devices by which liquids can be mixed are known. For example, Austrian Pat. No. 270,595 discloses an apparatus for continuously diluting a medium having a high viscosity, wherein the viscous medium and the far greater quantity of diluting liquid are continuously supplied under pressure to a first common chamber via rectangular inlet means. After sequentially passing through two grid walls the diluting medium is caused to rotate. The turbulent liquid streams are then pressed through the grid walls in order to align the macro-molecules and to avoid interlacings among them.
U.S. Pat. No. 2,509,288 discloses a mixing apparatus, wherein the liquids to be mixed are fed through opposing nozzles into a ball-shaped chamber and the mixed liquid stream is delivered through an outlet pipe connected to the chamber. U.S. Pat. No. 2,391,110 discloses a mixing chamber for liquids which includes a cascade of screens with circumferentially extending channels.
The mixing action of prior art devices is achieved by an imposed convection of the liquid streams in a chamber volume. Since a chamber of substantial volume is required to allow the convection to take place, mixing action is delayed. Furthermore, no mixing between partial volumes of both liquids can be obtained because the flow of the liquids exhibit uncontrolled flow profiles which result from turbulence.
SUMMARY OF THE INVENTION
A mixing chamber designed according to the preferred embodiment of this invention mixes two separate streams of liquid under pressure. The mixing chamber comprises two continuous, parallel, pressure-resistant grid walls between which liquid mixing occurs, an inlet means for entry of each liquid stream to be mixed into the mixing chamber through the grid walls and an outlet means for exit of the mixed liquid stream from the mixing chamber. The distance between the grid walls is in the mm-range and is at least five times less than the lateral extension of each grid wall. The grid apertures of the grid walls is in the micron, μ, range and the flow resistance of the grid walls provides uniform distribution of each liquid flowing under pressure over the cross-sectional areas of their respective grid walls.
The principal object of this invention therefore is to provide an improved apparatus of simple design for mixing two liquids substantially without delay and with increased efficiency, wherein each partial volume of the one liquid is mixed with the partial volume of the other liquid.
DESCRIPTION OF THE DRAWING
FIG. 1 is a cross-sectional view of the preferred embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, the mixing apparatus 3 comprises essentially two metal screens 5 and 6 having a mesh size of 3μ and a surface of 20 mm 2 each. Since the distance between the metal screens is 1 mm, the volume of the mixing chamber volume is 20 μl. The apparatus casing 7 is closed by means of bolts 8a, b. Two solvent A and B, respectively, are pumped in parallel relation via inlet means 1 and 2 into a mixing apparatus 3. The mixed homogeneous solvent is exited via outlet means 4. The connecting line between pumps and the mixing apparatus have an interior cross-section of typically 0.5 mm with a larger cross-section at the point of connection to the mixing apparatus.
During the operation of the device, liquid pumps which do not necessarily operate in timed relation, press liquids to be mixed, A and B, intermittently through metal screens 5 and 6 respectively, thus forming a plurality of intermeshing, thin separate jets of liquid. Additional mixing is provided by the turbulence resulting from the transverse forces acting among the jet streams between the internal screen faces. Thus, a homogeneous solvent liquid is obtained by intense mixing within a very confined space.
The size and shape of the device described can be varied without parting from the scope and nature of the present invention. Preferably, however, the screens consist of metal frets, separated by a distance not greater than one fifth of the fret diameter. The said distance may be 0.5 to 3 mm and adjustable according to the volumes of the liquids to be mixed. The aperture size of the screen mesh must be sufficiently fine and the distance between screens must be sufficiently small to create a flow resistance in the mixing chamber that will ensure the uniform distribution of the liquids to be mixed over the entire area of the chamber. Finally, several such arrangements may be joined in cascade so that the mixed flow leaving one stage is divided into partial flows and fed to the next stage and achieve a still more thorough mixed of the liquids.
The mixing chamber, as described above, has a minimum dead volume and a maximum active mixing area. The liquids to be mixed are uniformly distributed over the grid walls so that a build-up of flow profile, as would be observed with convection flows, is avoided. Thus, a more homogeneous mixing operation is obtained. Extremely narrow grid apertures provide uniform quantization or division of the oppositely directed liquid flows. Because of the small space between the grid walls, which limit the volume of the mixing chamber, the liquid particles of both streams, after passing through the grid walls, directly impact against each other and, without convection flow, are mixed with each other. This result is obtained without any additional equipment, such as additional mixing chambers, stirring or the like.
The preferred embodiment of this invention has been used for the gradient elution in a liquid chromatography system, wherein two solvents are pumped through it in a discontinuous fashion in order to become intensely mixed without substantial time delay during the mixing operation. The amount of the one solvent may be increased and the amount of the other solvent decreased proportionately, thus keeping the total volume of both solvents constant, while the mixing operation takes place within the small volume of the mixing chamber. Alternatively, where desirable, the amount of the one solvent having a high dissolving power, for example methyl alcohol, is continuously varied, the quantity of the other solvent, for example octane, may also be proportionately varied to correspond with the variations in the quantity of the first solvent.
Using the preferred embodiment of this invention, in a gas chromatography, a time-programmed separation of the applied substances is obtainable in accordance with temperature programming. Dead volumes are minimized and thus undue time delays are avoided which would tend to distort the exact time programming and preclude reproducible results.