US2661093A - Refining vessel draw-off system - Google Patents

Description

Dec. 1, 1953 A. SAWYER REFINING VESSEL DRAW-OFF SYSTEM Filed Feb. 19 1951 CZLtorl L. Saw-get Cinvarzbor' rM Qbboraegs Patented Dec. 1, 1953 UNITED sTArs-s rarest OFFICE REFINING VESSEL DRAW-OFF SYSTEM Alton L. Sawyer, Morristown,.N. J. Application Februaryi19, 1951, SerialNo. 211,685

1 Claim. (CL 210-51 This invention deals with the increasing of yields in the refining of fatty oils by use of a multi-tube draw-on system. More specifically, it.

relates to a liquid phase indicating system for the drawing off of layers after multi-layer settling in therefining of fatty oils.

During the refining of fatty oils such as cottonseed oil, soy bean oil, and the like, the oil is run into a vertical tank and the reagents such as caustic soda and water are fed into the top. lhe mixture is then agitated for a certain length of time under specified temperature and pressure conditions, and allowed to settle. In the settling operation, the heavier aqueous soap stock falls to the bottom of the tank as a separate layer. There is generally an emulsion layer floating on this soap stock layer, composed of particles of refined oil and soap stock. Disposed above the emulsion layer is the refined oil layer.

In conventional drawing-off operations, it is necessary to draw off the soap stock layer and the emulsion layer. If some of the emulsion is left behind, it reduces the quality of the refined oil. However, if the emulsion layer is drawn ofi completely and some oil layer is also drawn ofi, the yield of refined oil is obviously reduced. In conventional practice, th tendency is to maintain good refined oil quality and, to insure complete removal of the emulsion layer, some of the refined oil layer is also drawn OK and wasted.

Attempts have been made to reduce this wastage of refined oil by use of sight glasses in the draw-off line at the bottom of the settling tank. However, such glasses usually become coated with emulsion layer, so that by the time this layer is cleared oii by the flowing liquid, an appreciable loss of refined oil results. Also, even if the difference in phases is observed at the proper time, there is still loss of refined oil incurred by the time the draw-ofi line valve is completely closed.

An object of the present invention is to enable visual and other examination of the fiowing mass within the tank to determine the downward progress of the various phases therein. Another object is to enable detection of the upper phase change of the emulsion layer in sufficient time to allow for shutting cit of the draw-off line valve before any wastage of refined oil takes place. Other objects will become apparent from the description which follows. lhese objects are attained by inserting into the bottom of the tank two small bleed lines, one or" which penetrates the liquid in the bottom of the tank while the other draws ofi liquid at the very bottom of the tank.

The invention will be more clearly understood by reference to the drawing in which Figure 1 shows a vertical cross sectional View of a portion of the settling tank, while Figure 2 is a similar view of the bottom portion of the tank showing a different arrangement for the bleed lines. Similar numerals refer to similar parts in the various figures.

Referring again to the drawing, numeral l represents a vertical tank having lower tapered portion 16 terminating with flanged collar 2 to which disk head 3 is bolted. Outlet or drawoff line l is inserted into head 3 to enable drawing off of contents in tank l. Valve 5 is provided in draw-01f line 4 for throttling and shutoiT purposes. In tank I (Figure I) may be observed the lower soap stock layer 8, the intermediate emulsion layer i and upper refined oil layer 6.

As shown in Figure 1, tube 42 is inserted through head 3 to enable drawing off the contents from the very bottom of tank I. Also, inserted through conical portion It of tank 1 is line 9, the upper end 10 of which extends into the liquid in the conical portion of the tank near the center thereof. Both lines l2 and 9 are provided with shut-01f valves l3 and H respectively. End E0 of tube 9 is disposed far enough within tank I to enable one, when valve 5 is completely open, emptying tank 5, to close valve 5 in sufficient time to prevent refined oil 5 from being discharged therethrough.

lhis control is accomplished by opening valves H and 13 when valve 5 is opened to discharge the contents of tank I. As the contents are discharged through discharge line 6, small streams are simultaneously discharged through lines a and i2. These small streams enable the operator to sample and inspect, as well as smell and feel the material flowing past their intake points. Thus, for example, when emulsion l reaches inlet iii of tube 9 in Figure 1, it will be immediately transferred through tube 9, so that the operator sampling the discharge at the outlet of tube 9 will immediately detect that the emulsion is entering the conical section of tank 5. Since end it is placed far enough in tank 5, the operator can then proceed to throttle valve 5 and be ready to shut off the fiow completely as soon as the refined oil phase 8 begins to discharge out of bleed line !2, thereby preventing any loss of valuable refined oil.

Figure 1 shows one modification of the placement of bleed tubes 9 and 52. Another modification is depicted in Figure 2. In this case, tube 9' is installed in head 3 of the tank, while tube l2 is mounted in the lower portion of collar 2. Although these locations in Figures 1 and 2 are preferred, there is no particular limitation as to the manner in which the tubes 9 and #2 are mounted as long as tube 8 or 9' has its upper end ID extending into the liquid drained far enough to give the operator sufficient time to close valve without losing valuable refined oil. It is also required that the tank connection of line [2 or I2 be as close to the bottom of tank I as possible. It is apparent from the drawing that the outlets of lines 9 and 12 may be drained ofi to the soap stock tank or any other suitable container.

In actual practice, draw-off line 4 is usually about 4" pipe, more or less, while lines 9 and 12 are A" pipe. If the diameter of line 9 is too small, the flow therethrough may be too slow due to the high viscosity of the fluids transferred. Conversely, if the diameter is too large, it may be necessary to throttle valve II which would then cause a physical change to take place in the case of the emulsion due to the orifice efiect which breaks the emulsion.

It is preferable to insert upper end IU of line 9 into above about to of the volume of the soapstock originally present to insure a time lag during discharge sufficient to close valve 5 without discharge of refined oil. Also, end III of pipe 9 should be far enough away from the inner wall of tank I to avoid catching therein any film or other undesirable material which may be sliding down the side of the vessel. Numeral l4 represents a conventional sight glass which is normally used and which has been mentioned previously herein.

The apparatus of the present invention also allows the operator to draw out, with accuracy, only the soapstock, thus enabling him to treat the emulsion by heat or chemicals to recover additional oil, without the complicating presence of the emulsifiable soapstock. Although soapstock is mentioned here as the bottom layer, it could also consist of wash water, clean water or the like.

I claim:

A process for discharging, with minimum oil loss, some of the contents from the bottom of a tank provided with a discharge valve and used in. settling fatty oils which had been treated with a heaver aqueous liquid, said contents being composed of a bottom aqueous layer, a supernatant top oil layer, and a supernatant intermediate emulsion layer of oil and aqueous liquid, comprising, while discharging said contents, the step of drawing a first substantially continuous bleed sample from within the liquid disposed in the bottom of the tank until a supernatant layer is observed, then closing the discharge valve gradually, drawing a second substantially continuous bleed sample from the bottom of the tank, and closing the discharge valve completely when the supernatant layer is observed in the second bleed sample, said first bleed sample being drawn from the liquid at a point separated vertically from the point of drawing of said second bleed sample by a volume equal to at least about one-fifth to onefourth of the volume of the bottom aqueous layer originally present therein, thereby allowing sufiicient time for closing the discharge valve within the time interval when the supernatant layer is first observe-:1 at the two bleed lines.

ALTON L. SAWYER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 725,363 Powter Apr. 14, 1903 864,153 De Lany Aug. 27, 1957 1,245,366 Mathesius Nov. 6, 1937 1,803,083 Wack Apr. 28, 1931

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