US2134882A - Fractionating apparatus and method of fractionation - Google Patents

Description

Nov. 1, 1938. D, A. MONRO Y 2,134,882

FRACIIONATING APPARATUS AND METHOD OF FRACTIONATION Filed July 26., 1935 -M' i m, 47 1 Bottom Stock 2 I BOttom Jtocla "8' INVENTOR ldfi. Monro BY N5. K ATTORNEY Patented Nov. 1, 1938 umrso STATES FRACTIONATING APPARATUS AND METHOD OF FRACTIONATION Donald A. Monro, Chicago, Ill., assignor to Stand ard Oil Company, Chicago, 11]., a corporation of Indiana Application July 26, 1935, Serial No. 33,358

6 Claims.

This invention relates in general to the production of a multiplicity of grades of hydrocarbon stocks in a novel unitary fractionating or stabilizing apparatus and more especially to improvements in the manufacture of stabilized gasoline-like constituents and an apparatus therefor.

In the manufacture of gasoline it may often become desirable to produce from a fractionator or stabilizer column associated with an oil refining unit, such as a cracking unit, two or more gasolines differing from one another only in the degree of stabilization. For instance, it may bedesirable to make one grade of gasoline relatively low in butanes for use in warm climates and another grade of gasoline considerably higher in bu tanes for use in cold climates. Not only may it be desirable to produce two or more grades of gasoline, but it may also be desirable to produce two or more grades of lubricating oils having different flash points or two or more grades of asphalt from crude oil or reduced crude oil in a unitary fractionating or stabilizing apparatus.

My inventioncontemplates the manufacture of two or more different grades of hydrocarbon stocks in an apparatus particularly adapted for the production of such stocks.

An object of my invention is to provide an improved method of producing a plurality of grades of hydrocarbon stocks in a unitary fractionating or stabilizing column.

Anotherobject of my invention is the provision of a new and improved fractionating or stabilizing column with a minimum of heat loss for use in the production of a multiplicity of hydrocarbon stocks of different grades. With these and other objects in view, my in-' vention will be described with reference to the accompanying drawing which illustrates a unitary apparatus for carrying the same into practical effect, without limiting the improvements in their useful applications to the particular construction which, for the purpose of explanation, has been made the subject of illustration.

Referring to the single figure, there is shown a fractionating or stabilizing column I having a plurality of bubble plates 2 spaced therein to divide the column into a plurality of fractionating zones 3. Each of the bubble plates 2 is provided with a number of hell caps 4 through which upwardly rising vaporous products passing through the column are conducted and a reflux line 5 through which liquid products from one bubble plate, which is adapted to act as a reservoir for'liquid-products, are conducted to a similar lower bubble plate.

The lower portion of the column I in accordance with my invention is divided into sections. As shown, a division plate iiextends from the bottom of the column I to an intermediate bubble plate which has been designated 2'. The division plate 6 extends from one side of the column to the other, thus forming two completely separated sections 1 and -8 in the lower portion of the column I, the sections I and 8 extending from the bubble plate 2 to the bottom of the column.

Hydrocarbon material to be treated, such as gasoline or naphtha distillate from a cracking unit to be stabilized, may be introduced-as feed stock into a line 9 and conducted to the fractionating column I through one or more valved branch lines II. The feed stock is introduced above the bubble plate 2* definingthe top of the separated sections 1 and 8 thus making possible the collection of only a bottom stock in each of the separated sections. Vaporous constituents separated from the feed stock pass upwardly through the fractionating column and the final overhead product, which consists of undesired a light constituents, is conducted through a line I! to a condenser 13, from which it is passed to a receiver l4 having a valved gas outlet line I! and a liquid withdrawal line IS. The liquid products collected in the receiver I4 may be withdrawn through the line I6 by means of a pump' I1 and forced through a line l8 to the upper part of the column I as a refluxing medium for the upwardly rising light constituents. Automatic regulation of the liquid level in the receiver H downwardly through the reflux pipes 5 from one fractionating zone to another until they reach the intermediate bubble plate 2. The bubble plate 2 isprovided, with special reflux lines '23 and 24, one on each side of the division plate 6. with each line being provided with a flaring section extending above the intermediate plate 2, the purpose of which will now be described.

As before mentioned, it is desirable in many instances to produce two grades of bottom stocks in the same apparatus. In accordance with my invention the liquid constituents collected on the intermediate plate 2 may be divided into two portions, one portion thereof passing through the line 23 into the section I and the other portion thereof passing through the line 24 into the section 8.

The quantity of liquid passing into either of the sections'may be automatically controlled, if desired. I have shown an automatic control arrangement which comprises a liquid level regulator 25 having a float arm 26 suitably connected to a rod 21. automatically controlled valve 28, in a draw-oil? line 29 for the section 8, and a bell crank lever 3| having a shaft 32 connected thereto. A suitable brace 3| may be secured to the side of the column l for supporting the control arrangement and keeping the shaft 32 in alignment. The shaft 321s connected to another shaft 33 having arms 34 extending from opposite sides thereof. The shaft 33 may be actuated by the shaft 32 through suitable gears, not shown. Each of the arms 34 is provided at the end thereof with a valve 35 adapted to fit into the flaring portion of the pipes 23 and 24.

The arrangement thus described makes possible the maintaining of a constant level of liquid in the lower portion of the section 8. Thus if the liquid level in this section becomes too high, the float arm 26 actuates the rod 21 which opens the valve 28 in the line 29 for withdrawing liquid from this section and at'the same time depresses the valve 35 into the flaring section of the reflux pipe 24 thereby preventing too much liquid from flowing through this section. If the level of liquid in the section 8 becomes too low, the reverse of that described will take place. It will be evident from the foregoing that a constant liquid level may always be maintained in the lower portion of the section 8.

While the quantity of liquid entering the section I through the reflux line 23 is dependent upon the setting of the valve associated with the reflux line 24, a constant liquid level may nevertheless be maintained in the lower portion of the section I. As shown. a liquid level regulator 33 having a float arm 31 is associated with the lower portion of the section 1. The arm 31 may be connected to a rod 38 which actuates an automatically controlled valve 39 in a draw-off line 4| through which liquid may be withdrawn from the lower portion of the section 1. It will thus be apparent that a constant liquid level may be maintained in each of the sections 1 and 8. The levels of liquid maintained in these sections depend upon the quantity of a particular grade of stock desired and-they may be varied within wide ranges in order to produce the desired quantity of any particular stock.

Whatever grade' stock is desired from each section may be produced by controlling the temperature of the portion of the stock introduced into each of the sections. In order to produce stocks having different compositions, I have provided a reboiler arrangement for theliquid being separately treated in each of the sections 1 and 3 thereby effecting a stripping action of the liquid in each section. The reboiler arrangement including the necessary pipes is the same for each section and like reference characters will be applied to like parts of each of the reboilers.

The litiuid collecting on the lowermost bubble plate 2 may be withdrawn through a line 42 and passedthrough a reboiler 43 where it is heated by a suitable heat carrying medium, from which it is conducted by a line 44 to the lower portion of the section from which itis withdrawn below the lowermost plate 2. The thus heated liquid is collected in a body in its respective section and the vaporized constituents, the quantity of which depends upon the degree of heating, pass upwardly through the bell caps provided in the lowermost bubble plate 2. i The heat supplied to the reboiler 43 may be steam, superheated steam, hot oil, diphenyl vvav The rod 21 is also connected to an' pors or any other suitable heat carrying medium. The heat carrying medium, steam, being indicated on the drawing, may be introduced through a line 45 and passed through the reboiler 43 where it transmits heat to the liquid passing therethrough, the spent heat carrying medium being withdrawn through a line 46. As is well understood, the heat carrying medium and the liquid being heated are passed in indirect heat exchange with each other within the reboiler 43.

In order to control the amount of, heat, imparted to the liquid passing through the reboiler I have provided a temperature regulator arrangement comprising a thermostatic, control means 41 suitably positioned in the outlet line 44 of the reboiler 43 which automatically controls a valve 49 in the line 45 through a connection 48,

. thereby admitting more or less heat carrying medium, as the case may be. into the reboiler 43 for heating the fluid passing therethrough.

While I have shown and described automatic means for regulating the liquid levels in various parts of the apparatus as well as the quantity of heat carrying medium being introduced into the reboilers, it is to be understood that manual means may be employed if desired.

Moreover, while only two sections in the lower part of the column have been shown and described, it is obvious that more than two sections may be provided thereby permitting the production of more than two grades of hydrocarbon stocks.

From the foregoing description, it will be apparent that I have provided a novel method and apparatus for simultaneously producing a multiplicity of grades of hydrocarbon stock. For instance, if it is desired to produce two grades of gasoline, the gasoline or naphtha to be stabilized is introduced into the column i and by properly adjusting the setting of the valves 35 associated with the lines 23 and 24 it is possible to regulate the quantity of liquid separately entering the sections 1 and 8. By controlling the heating of the liquid passing from each of these sections through the reboiler 43 and back into the lower portion of the section it will be-evident that different grades of gasoline may be obtained. For example, if summer grade gasoline made to certain specifications has a tendency to vapor lock, it is possible to produce a gasoline, such as a butane absorption naphtha, in one of -the sections of the column for back blending to thus obtain a final product having the desired properties. Thus such a back blending stock may be produced in the lower portion of the section I and withdrawn through the bottom withdrawal line 4| as bottom stock A. Similarly the regular summer specification gasoline may be produced in the lower portion of the section 8 and withdrawn through the bottom withdrawal line 29 as a bottom stock 13.

My invention as before mentioned may be used' tition within said column extending from the bottom thereof to an intermediate bubble plate for dividing the lower portion of the column into two completely separated sections, means for introducing gasoline-containing oil to be treated into said column at a point above the said intermediate plate, separate conduits extending through said intermediate plate and into said separate sections for conducting a separate portion of liquid gasoline-containing oil ,collected on said intermediate plate into each of said separated sections, means associated with said conduits for regulating the quantity of gasoline-containing oil conv ducted into each of said separated sections, sepa rate means for heating the gasoline-containing oil being collected in eachsection foraltering the composition thereof to thereby produce two different grades of gasoline-containing oil, means for simultaneously controlling the level of liquid collected in one of said sections and the quantity of liquid being conducted thereinto, separate means for controlling the level of the liquid collected in the other section, and means for controlling the extent of heating of the liquid gasoline being collected in each section.

2. In a single unitary fractionating apparatus for separating liquid mixtures wherein a continuous series of contiguous fractionating elements is provided in a vertical column, the improvement comprising separate means within said column extending from the bottom thereof to an intermediate point for dividing the lower portion of said column into a plurality of completely separated fractionating sections, means for introducing hydrocarbon fluid to be treated into said column above said separated sections, means for dividing the liquid portion of the hydrocarbon fluid introduced into the column and conducting the parts thereof into each of the separate sections, means for regulating the quantity of liquid conducted into each of said separated sections, fractionating means associated with each of said sections for altering the composition of the hydrocarbon liquidbeing collected therein, and means for simultaneously controlling the level of liquid collected in one section and the quantity of liquid being conducted thereinto.

3. The method of' manufacturing a plurality of grades of hydrocarbon oil from an unrefined supply stock which comprises, introducing said supply stock into asingle fractionating column at an intermediate point thereof, vaporizing a portion of said stock and collecting unvaporized liquid constituents thereof in said column at a point below the point of introduction thereof,

" passing separate portions of said liquid constituents into completely separated stripping zones in the lower portion of said fractionating column, regulating the quantity of liquid constituents introduced into each of said stripping zones in response to the levelof liquid collected in one of said zones and separately heating the liquid constituents in each of said stripping zones to thereby produce a different grade of hydrocarbon oil in each.

4. The method of manufacturing a plurality of grades of hydrocarbon oils from an unrefined supply stock which comprises, introducing said supply stock into a single fractionating column at an intermediate point thereof, vaporizing a portion of said stock and collecting unvaporized liquid constituents thereof in said column at a point below the point of introduction thereof, passing separate portions of said liquid constituents into completely separated stripping zones in the lower portion of said fractionating column, regulating the quantity of liquid constituents introduced into each of said stripping zones in response to variations in the level of liquid collected in one of said zones, regulating the level of liquid constituents collected in another of said stripping zones by separately withdrawing liquid therefrom when the level becomes too high, and separately heating the liquid constituents in each of said stripping zones to thereby produce a different grade of hydrocarbon oil in each.

5. The method of manufacturing a plurality of grades of hydrocarbon oils from an unrefined supply stock which comprises, introducing said supply stock into a single fractionating column at an intermediate point thereof, vaporizing a portion of said stock and collecting unvaporized liquid constituentsthereof in said column at a point below the point of introduction thereof, passing separate portions of said liquid constituents into completely separated stripping zones in the lower portion of said fractionating column, regulating the quantity of liquid constituents introduced into each of said stripping zones in response to the level of liquid collected in one of said zones, regulating the level of liquid constituents collected in another of said stripping zones by separately withdrawing liquid therefrom when the level becomes too high, separately heating the liquid constituents in each of said stripping zones to thereby produce a diirerent grade of hydrocarbon oil in each, and controlling the extent of heating to maintain a constant temperature in the oil introduced into each of said stripping zones.

6. A fractionating apparatus for producing a plurality of fractions of hydrocarbon oils of different volatility or flash characteristics, which comprises a bubble tower, a large number of contiguous bubble plates within said tower, a partition within said tower extending from the bottom thereof to an intermediate bubble plate for dividing the lower portion of the tower into two completely separated fractionating sections, means for introducing the hydrocarbon oil to be fractionated into said tower at a point above said intermediate bubble plate, separate conduits extending through said intermediate bubble plate and into said separate sections for conducting a separate portion of liquid from said intermediate.

bubble plate into each of said separated sections, means associated with said conduits for regulating the quantity of liquid conductedinto each of said separated sections, separate means for heating the liquids in each section to produce finished oils of different volatility or flash point, separate means for controlling the liquid level in-each of said sections, and means for separately controlling the extent of heating of the liquid in each of said heating means.

, DONALD A. MONRO.

' CERTIFICATE OF CORRECTION. Patent No. 2,l5! ,882 November 1, 1958. DONALD A. MoNRof It is hereby certified that error appearsin the printed specification of the ebove numbered patent requiring correction as follows: Page 5, first column, line 50, claim 1, for "gasoline-containing oil" read gasoline; and that the said Letters Patent should be'read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of December, 'A. D. 1958.

Henry Van Arsdale Acting Commissioner of Patents.

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