US3023764A

US3023764A - Liquid blending system

Info

Publication number: US3023764A
Application number: US728848A
Authority: US
Inventors: William P Dooley; Elvin L Coe
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1958-04-16
Filing date: 1958-04-16
Publication date: 1962-03-06
Anticipated expiration: 1979-03-06

Description

March 6, 1962 w, P. DooLEY ET AL LIQUID BLENDING SYSTEM Filed April 16, 1958 United States Patent O 3,023,764 LIQUID BLENDING SYSTEM William P. Dooley, Wallingford, Pa., and Elvin L. Coe,

Nitro, W. Va., assignors to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Filed Apr. 16, 1958, Ser. No. 728,848 9 Claims. (Cl. 137-98) The present invention relates to a system for adding a constant proportion of a low viscosity liquid to a variable stream of high viscosity liquid, and in its more particular aspects the invention is concerned with a system for adding a constant proportion of dye, delustrant or the like to a stream of high viscosity yartificial filament-forming solution such as viscose, acetate or the like.

While the invention will be described in particular reference to the spinning of viscose, it will be readily apparent that it is equally adaptable to systems for spinning other artificial fibers and that in its broader aspects the invention is applicable to lluid distribution systems generally. In the production of colored and/ or delustered viscose rayon, it is essential in commercial practice to add the color or delustrant to the main viscose stream at `a point which is fairly close to the spinning machine, and great difdculty has been experienced in the past in producing a uniform product because of the diiculties in maintaining a constant ratio between the added material and the main viscose stream due to the fact that the volume of iow changes as parts of the spinning machine are started up and shut down, and also due to the fact that the viscosity of the main viscose stream varies from time to time.

It is accordingly the primary object of the present invention to provide an improved system for injecting a constant proportion of an additive into a filament-forming spinning solution, the ilow of which is variable.

A more general object of the invention is to provide an improved system for adding a constant proportion of a low viscosity liquid, which in some cases may be abrasive, to a high viscosity liquid when the volume of flow of the high viscosity liquid is variable.

Other and further objects, features and advantages of the invention will become apparent as the description of a preferred embodiment thereof proceeds.

The FIGURE of the drawing is a diagrammatic representation of a preferred embodiment of the system.

The spinning solution or main viscose supply is contained in a tank 1() which may be located several hundred feet away from the spinning machine 11. The spinning solution is conducted from the tank 10 through a main conduit 12 to a blender or mixing apparatus 13, a portion of the solution being diverted through a shunt line 14, presently to be more particularly described, which also discharges into the blender 13. From the blender 13 the spinning solution passes through a short conduit 15 to the spinning machine.

A prime mover 16, which may take the form of large capacity, low precision constant volume pump, feeds the spinning solution under pressure through the conduit 12. The prime mover 16 is driven from a variable speed drive 17, the speed of which is controlled by a suitable electronic or hydraulic instrument 18 in accordance with the pressure sensed in the conduit 15 by a standard pressure sensing means 19 which is connected through a line 20 to the instrument 18 which in turn is connected by -a line 21 to the variable speed drive 17. It will be apparent that if one or more stations of the spinning machine are shut down the pressure in the conduit 15 will rise, Whereas when additional spinning stations are started up the prsure in the conduit 15 will decrease. The instrument 18 is so .arranged that upon an increase in pressure in the conduit 15 variable speed drive 17 is operated to decrease Mice the speed of the pump 16 which thereby decreases the flow through the conduit 12 and, conversely, when the pressure in conduit 15 decreases, the ow through conduit 12 is increased. r[hns the demand of the spinning machine controls the flow of bright viscose from the tank 10 through the

conduits

12 and 15.

A group of positive displacement pumps 22 and 23 are located in the shunt line 14 and between these pumps there is a blender 24 which will hereinafter be referred to as a preblender. Connected to the preblender 24 by a conduit 25 is a supply tank 26 containing a solution or slurry of a delustrant, -dye or the like. This solution or slurry, which will in many instances contain an abrasive material, for example TiO2, is maintained in the conduit 25 under controlled pressure by a pump 27 which may be a non-precision pump such, for example, as a screw pump, a by-pass line 28 being provided to circulate back to the tank 26 any of the additive which does not pass into the preblender 24. A manually operable needle valve 39 in the line 28 may be employed for regulating the amount of recirculation of the additive and therefore control the pressure at which the additive enters the preblender. The pump 23 has a greater demand or capacity than the pump 22 and this dilerence in demand of the two pumps is made up by the additive which is drawn into the preblender. The additive containing the abrasive material is thus thoroughly mixed with a substantial volurne of non-abrasive spinning solution in the preblender before entering the precision pump 23 and is thus so diluted that it may pass through pump 23 without producing undue wear on the pump.

The pumps 22 and 23 are driven from a common drive shaft 29 so that the ratio of the speeds or the two pumps and consequently the relative demands of said pumps remain constant even though the speeds are varied in the manner presently to be described. Of course there may be more than one pump 22 and more than one pump 23 so long as the demand of the pumps following the preblender is greater than the demand of the pumps located upstream of the preblender.

For controlling the speeds of the pumps 22 and 23 in accordance with the amount of bright viscose passing through conduit 12, it is irst necessary to provide means for determining the amount of said flow, and since, as previously mentioned, the viscosity of the viscose changes from time to time, the ordinary means for measuring the flow of Newtonian liquids are not suiiicient and it is therefore necessary to provide a special means for measuring this ilow. Two factors are involved in this changing viscosity of the viscose. One is that the viscose solution in the tank 10 is made up in batches and all batches are not v the same, and the other and more important factor is that the viscosity changes with the rate of shear, viscose being a thixotropic substance, and the varying speeds of the prime mover 16 of course effects changes in the rate of shear. Located in the conduit 12 upstream from the shunt line 14 are a pair of pressure measuring cells 30 and 31. These cells are located fairly close together and would indicate the same pressure were it not for the fact that a pump 32 is located in the conduit between the cells. The pump 32 need not be a precise metering pump but when it is driven at the speeds necessary to maintain pressures at the cells 30 and 31 substantially equal, itis doing no Work on the viscose and its speed can be used as an indication of the amount of liquid owing through the conduit 12. The pump 32 is driven from the output of a variable speed drive 33 the torque output of which should remain at' a high level over the entire range'of speeds from substantially zero speed to maximum. A suitable form of variable speed drive 33 is known as the Specon drive which is manufactured by the Speed Control Division of Fairchild Engine and Airplane Corporation. The input of the variable speed drive may be driven by a motor 34. The pressure measuring cells 30 and 31 are connected toY a suitable standard instrument 35 which in turn controls the output speed of the variable speed drive 33 and regulates such output speed to whateverrextent is necessary to balance the pressures in the cells 30 and 31. For example, when the pump 16 is slowed down due to a decrease in demand of the spinning machine, theY pressure at the cell 30 will drop below the pressure at cell 31 and the instrument 35 will thereupon cause the variable speed drive 33 to slow down pump 32 in order to balance the pressures on opposite sides of the pump. Likewise, a speeding up of the pump 16 will cause the pressure at cell 30 to rise above the pressure at cell 31 and the pump 32 will thereupon be speeded up torebalance these pressures. Y Y

The output shaft 36 of the variable speed drive 33 is directly connected as by means of a chain drive 37 to a variable speed changer 38 for the aforementioned common drive shaft 29. Thus an increase in the volume of flow through the conduit 12, as indicated by the increased speed of the pump 32, necessary to maintain the pressures in the cells 30 and 31 the same, will result in an increased speed of the common drive shaft 29 since this drive shaft is mechanically connected to the output of variable speed drive 33 which drives the pump 32. Therefore, when the volume of flow through the conduit 12 increases, an increased amount of spinning solution is drawn through the shunt line 14 by the pump 22 and since the pump 23 is also driven by the shaft 29 an increased amount of additive will be drawn through the line 25, the ratio of additive to the total ow through shunt 14 remaining constant as previously mentioned.

The ratio of the output speed of the variable speed changer 38 to its input speed is varied manually only when itis desired to change the ratio between the amount of additive and the amount of solution owing through the conduit. In the case of adding a dye to a viscose spinning solution, for example, the setting of variable speed drive 38 will be determined by the desired hue of the iilaments produced by the spinning machine.

Since the present invention is concerned with the overall system andnot with the particular instrumentation employed forrautomatically operating the various speed change devices nor with the details of the speed change device per se, these have been illustratedY only diagrammatically. Likewise, the pumps, blenders, the spinning machine, etc., may all be of standard construction and therefore there is no need to describe these elements in detail.

Having thus described a preferred form of the inven# tion, what is claimed is:

1. A system for supplying spinning solution to Ia spinning machine comprising a main line for conveying spinning solution to a spinning machine, a shunt in said main line, means for pumping a portion of the spinning solution owing in said main line through said shunt, means for introducing an additive into said shunt, means for maintaining constant the ratio between the amount of additive introduced into said shunt and the amount of spinning solution owing through said shunt, means for maintaining constant the proportion between the amount of spinning solution pumpedv through said shunt and the amount owing through said main line, and means controlled by the pressure in said main line downstream from said shunt for Iautomatically `regulating the flow of spinning solution through said main line.

2. The system according -to claim `1 wherein the means for introducing the additive into the shunt'comprises a pair of tandemly arranged positive displacement pump means in said shunt, the downstream one of said pump means having a greater capacity than the other, and an additive line feeding into said shunt between said pair ofl pump means.

t 3. The system according to claim 2wherein said additive line discharges directly into a blender located in said shunt.

4. The system according to claim 2 wherein the means controlled by the pressure in said main line downstream from said shunt comprises pressure sensing means in said main line at a point downstream from said shunt, a prime mover for the spinning solution located upstream from said shunt, and means controlled by said pressure sensing means for regulating said prime mover inversely with the pressure sensed by said pressure sensing means.

5. The system according to claim 1 wherein the means controlled by the pressure in said main line downstream from said shunt comprises pressure sensing means in said main line at a point downstream from said shunt, a prime mover for the spinning solution located upstream from said shunt, and means controlled by said pressure sensing means for regulating said prime mover in inverse proportion to the pressure sensed by said pressure sensing means.

6. The system according to claim l wherein a blender is located in the main line at the point where said shunt rejoins said main line. v

7. A constant ratio liquid injection system comprising a source of spinning solution, a main conduit for conveying spinning solution from said source to a spinning machine, a prime mover for forcing spinning solution through said conduit under pressure, a blender in said conduit downstream from said prime mover, a shunt line leading from said main conduit at a point upstream from said blender and discharging into said blender, a pair of positive displacement pumps located in tandem in said shunt line, means for introducing an additive under pressure into said shunt line between said pumps, drive means for driving said pumps at constantly related speeds, the downstream one of said pumps having a greater demand than the other, the difference in demand being made up by the additive drawn into said shunt line, flow measuring means for measuring the flow of spinning solution through said main conduit at a point upstream from said shunt line, means operatively connecting said flow measuring means to said drive means whereby said drive means is varied in direct proportion to the flow of spinning solution through said main conduit to thereby maintain constant the ratio of the ow through said shunt to the flow through said main conduit, means for measuring the pressure in said main conduit at a point downstream from said blender, and means controlled by said last-mentioned means to vary the effective force of said prime mover in inverse proportion to the pressure.

8. A constant ratio liquid injection system comprising a source of spinning solution; a main conduit for conveying spinning solution from said source to a spinning machine, pressure supplying means for forcing spinning solution through said conduit under pressure, a blender in said conduit downstream from said pressure supplying means, a secondary conduit leading from said main conduit at a point between said pressure supplying means and said blender, a metering pump means and a preblender in said secondary conduit, means for. introducing an additive under controlled pressure to said preblender, a third conduit leading from said preblender to said blender, metering pump means in said third conduit, said last-mentioned metering pump means having a greater demand than said first-mentioned metering pump means whereby a predetermined proportion of additive will be drawn into said preblender to satisfy the demand of said second-mentioned metering pump means, a common drive for both said metering pump means whereby the ratio of additive to spinning solution passing through said third conduit will remain constant evenkwhen the volume of ow is varied, flow measuring means for measuring the ow through said main conduit at a point upstream from said secondary conduit, means controlled by said flow measuring means for varying the speed of said common drive in proportion to the dow through said main conduit whereby the ratio of ow through said secondary conduit to the ow through said main conduit will remain constant, and means for Varying the effective force of said pressure supplying means in accordance With the pressure in said main conduit at a point downstream from said blender.

9. A constant ratio liquid injection system comprising a source of spinning solution, a main conduit for conveying spinning solution from said source to a spinning machine, pressure supplying means for forcing spinning solution through said conduit under pressure, a blender in said conduit downstream from said pressure supplying means, a secondary conduit leading from said main conduit at a point between said pressure supplying means and said blender, a metering pump means and a preblender in said secondary conduit, means for introducing an additive under pressure to said preblender, a third conduit leading from said preblender to said blender, metering pump means in said third conduit, said lastmentioned metering pump means having a greater demand than said rst-mentioned metering pump means whereby a predetermined proportion of additive will be drawn into said preblender to satisfy the demand of said second mentioned metering pump means, a common drive for both said metering pump means whereby the ratio of additive to spinning solution passing through said third conduit will remain constant even when the volume of flow is varied, ow measuring means for measuring the dow through said main conduit at a point upstream from said secondary conduit, said dow measuring means comprising a pair of pressure sensing means in said main conduit for sensing the pressure in said conduit at closely spaced points, pump means in said main conduit between said pressure sensing means, means controlled by said pressure sensing means for regulating the speed of said pump means to produce the same pressure at the two pressure sensing means, said last-named means being connected to said common drive for varying the speed of said common drive in proportion to the flow through said main conduit whereby the ratio of flow through said secondary conduit to the ilow through said main conduit will remain constant, and means for varying the effective force of said pressure supplying means in accordance with the pressure in said main conduit at a point downstream from said blender.

References Cited in the file of this patent UNTED STATES PATENTS 1,496,377 Harvey Feb. 14, 1922 1,522,120 Halder Ian. 6, 1925 2,650,168 Van Dijk et al Aug. 25, 1953 2,861,440 Bauer Aug. 6, 1957 2,837,102 Bauer .lune 3, 1958 2,838,792 Keight et al June 17, 1958 2,929,731 De Vries Mar. 22, 1960