US2747844A - Device for mixing fluids - Google Patents

Description

May 29, 1956 R. s. SLAYTER 2,747,844

DEVICE FOR MIXING mums Filed Dec. 22, 1954 United States Patent DEVICE FOR MIXING FLUIDS Rudolf S. Slayter, Weston, Mass.

Application December 22,1954, Serial No. 476,878

2 Claims. (Cl. 259-4) This invention relates to a device for mixing two mutually miscible fluids such as oils of diiferent kinds so that the fluids are thoroughly blended. While the device can be successfully used for mixing gases or liquids of various kinds, the device hereinafter described in detail was designed for use in mixing fuel oils of different grades. Fuel oils from the refinery are supplied in various grades according to their viscosity. It is often desired to obtain an intermediate grade by mixing two grades of higher and lower viscosity, respectively, the ratio of the two oils being carefully regulated to result in a mixed oil having the desired viscosity. The device hereinafter described has no moving parts but is constructed with a number of chambers with many small connecting passages through which the fluids flow for intimate intermingling. It is an object of the invention to provide a device which is relatively simple and easy to manufacture but which is eflective for the desired purpose. For a more complete understanding of the invention reference may be had to the following description thereof and to the drawing, of which Figure 1 is an elevational view, partly in section, of a mixing device embodying the invention;

Figure 2 is a fragmentary sectional view, on a larger scale, of the device shown in Figure 1;

Figure 3 is a section on the line 33 of Figure 2; and

Figure 4 is a section on the line 4-4 of Figure 2.

The device comprises an outer cylindrical tube having heads 12 and 14 at its inlet and outlet ends respectively. An inner tube, coaxial with the outer tube 10 extends from the inlet head 12 toward the outlet end of the device. An inlet fitting 18 is centrally located on the head 12 and opens into the inlet end portion 16 of the inner tube. The inner tube is secured to the head 12 around the orifice of the fitting 18 by welding or otherwise. An outlet fitting 20 opens into the tube 10 through the head 14.

An annular partition 22 is mounted within the outer tube not far from the inlet head 12 to form a chamber 24. A second inlet fitting 26 opens into the chamber 24 through the wall of the outer tube 10. The inner edge 28 of the partition 22 is of greater diameter than the inlet portion 16 of the inner tube and is therefore spaced from the inner tube, thus forming an annular passage 30 between the inner edge of the partition and the inner tube for the escape of fluid from the chamber 24. Secured to the inner edge 28 of the partition 22 is a short tubular member 32 which extends toward the outlet end of the device and flares in diameter so that the passage between the member 32 and the inner tube increases in size toward the outlet end. Opening into this passage are a multiplicity of small apertures 34 which are preferably but not necessarily arranged in a plurality of circumferentially extending series, four such series being shown by way of example. The apertures of the several series may be arranged, as indicated in Figure 2, in a stepped or echelon array. The inlet portion 16 of the inner tube is blanked off by a diaphragm 36 at a point beyond the apertures 34 so that all the fluid entering through the inlet fitting 18 must flow out through the apertures 34 to mingle with the fluid entering through the inlet fitting 26 which must flow through the passage 30 and the clearance between the flaring member 32 and the adjacent portion of the inner tube. This arrangement of the apertures 34 results in a uniform circumferential distribution of the fluid flowing into the passage between the member 32 and the inner tube.

Just beyond the diaphragm 36 the inner tube has a mid portion which is enlarged in diameter as at 38, the inlet and mid portions being connected by a short frustoconical portion 40. Through the latter portion are a number of apertures 42 in circumferential series. As shown, the apertures 42 may be fewer in number but individually larger than the apertures 34.

The inner tube has a double-walled outlet portion adjoining the mid portion 38 and of smaller diameter. This outlet portion consists of coaxial outer and inner walls 43 and 52 mutually spaced to form a longitudinal passage 58 which increases in cross-sectional area toward the outlet end. An annular partition 44 extends from the wall of the outer tube it) inward to the extremity of the wall 48. The extremity of the inner wall 52 of the outlet portion of the inner tube is sealed by a diaphragm 54. This diaphragm and the partition 44 define an outlet chamber 46 within the outer tube 19 into which the passage 58 opens. The wall 43 has perforations 62, and the wall 52 has perforations 6i), the number and arrangement being preferably but not necessarily the same. The flow of fluid through the apertures 42 into the mid portion 38 of the inner tube is somewhat restricted by the size and number of these apertures. Hence there is a pressure difference inside and outside of the member 33 sufficient to cause the quantities of fluid to be discharged through the apertures 62 and the apertures 60 to be unequal. Thus the flow inside and outside of the enlarged portion 33 of the inner tube is unequal, and particles of fluid flowing outside of the member 38 will pass through the apertures 62 before or after adjacent particles taking the inside route reach the apertures 61?. This offsetting of the parts of the divided stream tends to iron out any small irregularities in the stream which may arise from irregularity of supply of one or both of the fluids.

The operation of the device is as follows. The two fluids to be blended enter respectively through the inlets 13 and 26. The first fluid flows into the inner tube and on account of the stop 36 must escape through the apertures 34 into the passage between the member 32 and the inner tube.

The second fluid enters the chamber 24 through the inlet 26 and escapes through the passage 3%? to mingle with the fine streams of the first fluid flowing out of the apertures 34. The size of the apertures 34 is calculated with reference to the area of the passage 34) so that in order to mix the two fluids in a predetermined ratio it will be necessary to supply the first fluid under a suflicient pressure to cause it to flow through the apertures 34 at a much higher velocity than the flow of the second fluid through the passage 3d. These small jets create turbulence throughout the space between the member 32 and the adjacent portion of the inner tube. The mingled fluids flow toward the outlet end, the stream dividing into two streams one of which enters the enlarged portion 33 of the inner tube through the apertures 42. The other branch stream flows outside of the member 33 but out of step with the inner branch stream and enters the extension 48 through the apertures 62 to mingle intimately with a different portion of the inner branch stream which flows outward through the apertures 66.

i claim:

1. A fluid mixing device comprising a cylindrical outer tnbe with a head at each end, an axial inlet fitting opening through one said head, an axial outlet fitting opening through the other said head, an inner tube coaxial with the outer tube, one end ofthe inner tube being secured to the head at the inlet end around the orifice of said inlet fitting, the other end-.of said inner tube being spaced from said other head, an annularpartition in theouter tube forming a chamber attheinlet-end of the outer tube, the inner edge of said partition being spaced radially from said inner tube, a second inlet fitting openingthrough the wall of. said outer tube between its. inlet end and said-partition, alshortfiaringtubularmember extending from the inner edge of said partition toward the outlet endof'thedevice and forming with the adjacent portion of the. inner tube-alongitudinally extending passage, said inner tube hav-ing a multiplicity of small apertures in its wall openinginto said passage, a diaphragm secured Withinsaid inner tube at a point-beyond said apertures, saidinner tube also having small apertures therethrough beyond but near to said diaphragm, and a second annular partition in saidouter tube near'fhe outlet end thereof, the outlet endportion of said inner-tubehaving twovcoaxial walls spaced from each other and'perforated, the outerof said two walls being secured to the inneredge of said second partition, the: inner ofsaid two wallsbeing closed at its extremity.

2. A. fluid mixing device comprising an outertubewith an inlet head and an outlet head at the respective ends thereof, an axial inlet fitting opening through said inlet head, an axial outlet fitting opening through said outlet head, a second inlet fitting'opening through the side of said outer tube near the inlet end thereof, an inner tube within said outer tube and coaxial therewith, the inlet end of said inner tube being secured to said inlet head around said inlet fitting, said inner tube having an inlet portion, a double-walled outlet portion and a mid portion of greater diameter than either of the other two portions, an annular partition in the outer tube forming a chamber into which said second inlet fitting opens, the inner edge of said partition being spaced radially from said inner tube, a short flaring tubular member extending from the inner edge of said partition toward the outlet end of the device and forming with the adjacent portion of the inner tube a longitudinally extending passage, 'said inner tubehavinga multiplicity of. small holes in its Wall opening into said passage, a diaphragm within the inlet portion of said inner tube beyond said holes, said mid portion of the inner tube having holes near the inlet end thereof, said outlet portion of the inner tube having coaxial inner and outer perforated walls extending from said mid portion of the inner tube, an annular partition member extending inward from the-wallof-theouter tube to=the extremity of the outer wallof saidoutlet portion of the inner tube, and a-diaphragmclosing-the outlet end ofthe'inner wall of SaidLinner-tube;

References Cited in the file of this patent UNITED STATES PATENTS 2,085,132 Underwood June 29, 1937 2,252,076 Juterbock Aug. 12, 1941 2,618,539 Conta etal; V Nov. 18, 1952 2,651,322 Hendry- Sept. 8, 1953

Images