US1976469A - Process and appartus for converting hydrocarbon gases - Google Patents

Description

M. P. YOUKER Oct. 9, 1934.

PROCESS A ND APPARATUS FOR CONVERTING HYDROCARBON GASES Filed Feb. 23,` 1935 UNITED STATES PATENT OFFICE PROCESS AND APPARATUS FOR CONVERT- ING HYDROCARBON GASES Malcolm P. Youker, Bartlesville, Okla., assigner to Phillips Petroleum Company, Bartlesville,

Okla., a corporation of Delaware Application February 23, 1933, Serial No. 658,172

6 Claims. (Cl. 196-10) 'Ihis invention relates to a process and apparatus for converting normally gaseous hydrocarbons to heavier materials such as gasoline.

An object is to provide an improved form of apparatus whereby normally gaseous hydrocarbons from various sources such as natural gas, gases from cracking heavier hydrocarbon oils, or from distillation of oil shale, coal or other carbonaceous materials, maybe most economically converted to normally liquid hydrocarbon materials of the gasoline boiling range.

Other objects and improvements will become apparent from the following description of my process and apparatus; the latter being illustrated in the accompanying drawing, which is a diagrammatic View of the same.

Referring to said drawing:

1 is a supply tank containing normally gaseous hydrocarbons obtained, for example, from cracking stills. These hydrocarbons are under suldcient pressure to maintain them in liquid condition; a pressure release valve 2 serving to hold a predetermined pressure on the tank 1. The liqueed hydrocarbons are drawn through line 3 by pump 4, and are discharged through meter 5 and line 6 to a surge tank 7, in which they are mixed with unconverted hydrocarbon material that has passed through the process and is being returned for reprocessing. The mixture of fresh stock and material for reprocessing is drawn through line 8 by pump 9 and charged through line 10 into a heating coil 11 disposed in a furnace 12 in which the mixture of liqueed gases is maintained under pressures between 500 pounds and 3500 pounds per square inch, preferably about 2500 pounds per square inch, and are subjected to temperatures in excess of 750o F., and below 1250 F., and for a period of time suihcient to complete the conversion to heavier materials. This time element may vary, depending on the nature of the charging stock. from about two minutes to about ten minutes or longer. The products, after conversion, pass through a line 13 and a back pressure valve 14 (which serves to maintain the desired pressure on the heating zone), into a rectifying tower l5 of a conventional bubbling type, maintained at a lower pressure than that imposed on the heating coil 15. The pressure in rectifying tower 11 is, however, maintained considerably above atmospheric, usually :from about 150 pounds per square inch to about 350 pounds per square inch. The conversion products are here separated into a liquid heavier than gasoline, gasoline and material lighter than gasoline which is normally gaseous and consists principally of unconverted charging stock and some fixed gases which are unliqueable under the conditions obtaining in thisprocess.' This separation is accomplished by the expedient of pumping some of the liquid material in surgetank 7 through line 16 by means of pump 17 and line 18 to tower 15, in which it serves as reflux. The unconverted material and iixed gases leaves the tower 15 through a line 19 and are condensed in reux condenser 20 (disposed in condenser box 2l), and pass through line 22 into surge tank 7, which is maintained at about the same pressure as tower 15. The xed gases unliqueable at the temperature and pressure maintained in the surge drum 7 pass out through a line 23 and a back pressurevalve 24 which serves to maintain the desired pressure on that portion of the system which includes tower 15, condenser coil 20 and surge drum 7, and their interconnecting lines 19, 22 and 23. Gases passing through the Valve 24, enter vent gas header 25, through which they leave the system. The liquefied material entering the surge drum 7 mixes with the fresh charge and is recharged to the heating coil 11. The gasoline formed in the conversion is removed as a liquid from an intermediate point in tower 15 and passes through line 26 into a second rectifying tower 27 which is under substantially atmospheric pressure. The portion of converted material in tower 15 which is heavier than gasoline, collects in the bottom of the tower 15, and by means of the pressure in tower l5, is forced either through valve 28, line 29, a cooler 30, line 31, into a storage tank 32, or is forced through line 33 and a valve 34, into line 35, which is a portion of a reboiler system that will be later described. The liquid gasoline which enters rectifying tower 27 by means of line 26 is partially vaporized` due to the reduction in pressure from the 150 to 350 pounds obtaining in tower 15 to the substantially atmospheric pressure present in tower 27. A check valve 36 is interposed in line 26 `to permit this reduction in pressure.

Some of the liquid collecting in the bottom of the tower 27 is drawn through line 37 by pump 38 and pumped through a coil 39, heated by waste heat contained in the flue gases leaving the furnace 12 on their way to stack 40. This heated material then passes through line 35 where it is commingled with hot material leaving tower 15 through valve 34 and line 33 as previously described; the hot mixture returning to the bottom of tower 27 where it acts as a reboiling medium and supplies sufficient heat to the liquid in the bottom of tower 27 to vaporize substantially all the gasoline, which passes upward through tower 27 countercurrent to'a iiow of liquid reflux, that serves to condense materials heavier than gasoline passing from the tower y27 through line 41 into line 29,where they mix with the material removed yfrom the bottom of tower 15.

The reuxed vapors leave the top of tower 27 through vapor line 42 which is divided into branch vapor lines 43 and 44. A portion or a first stream of the vapors pass through branch line 43' into treating tower 45 which may be filled with a treating agent, such as clay or fullers earth, for vapor phase treatment of the vapors, in the Well known manner. The treated vapors, after contact with the treating agent, pass through line 46 into the polymer separator 47. Any polymers formed in treating tower 45 which condense and collect in the bottom ofthe tower, pass through line 48 into polymer separator 47. By means of bubble trays or some similar contacting devices contained in the separator 47, the treated gasoline vapors are subjected to the reuxing action of a portion o f the condensed treated gasoline,.which is returned to the upper portion of the polymer separator 47 through line 49. 'The condensed polymers are drawn from the separator 47 through line 50 by pump 5l and are forced through line 52 to an intermediate portion of the fractionating tower 27 in which they serve as a portion of the reflux liquid required in this tower. The treated gasoline vapors leave polymer separator 47 through line 53 and enter condenser coil 54 disposed in condenser box 55. In coil 54, some of the vapors are condensed into liquid gasoline, and this gasoline and uncondensed xed gases pass through line 56 into accumulator 57, where the fixed gases .box 55. virtue of the fact' that they do not pass through separate and pass out through line 58 into the vent gas header 25. The treated liquid gasoline is drawn from accumulator 57 through line 59 by pump 60, which forces :a portion through line 49 to polymer separator 47 as reflux, as has been previously described, and the remainder through line 61, meter 62` and line 63 to the finished gasoline storage tank 64.

The remainder of the gasoline vapors, or a second stream, leaving fractionating tower 27 and entering, branch vapor line 44, pass through a back pressure valve 65 and a line'66, into a condenser coil 67 which is also disposed in condenser These untreated vapors, (untreated by treating tower 45), are partially condensed into liquid untreated gasoline, and this gasoline and uncondensed fixed gases pass through line 68 into an accumulator 69 where the xed gases separate and pass out through line 70 into vent gas header 25. The liquid untreated gasoline is removed from accumulator 69 through line 71 by pump 72 and is pumped through line 73 to the top of the fractionating tower 27, in which it serves as the remainder of the reflux required by tower 27. Accumulator 69 is equipped with a liquid level actuated device 74 by means of which valve 65 is operated through the medium of connecting elements 75 to regulate the proportions of vapors passing through branch vapor lines 43 and 44. If, for example, too large a volume of vapors enter branch line 44, the resulting condensate will raise the liquid level in accumulator 69 above a predetermined level, causing actuation of the device 74 which, by means of elements 75, will cause valve 65 to partly close and thus force more of the vapors through branch line 43. If a reverse condition occurs, the lowering of the level in accumulator 69 will cause valve 65 to be opened and allow more vapors Ito enter branch line 44. In this way, only those vapors not required to furnish reflux for tower 27 will pass through treating tower45, and the subsequent steps; the result being that no treating material is wasted in treating vapors which are subsequently returned to tower 27 for reux purposes.

While I have described a preferred application of my invention, it will be readily apparent that numerous variations can be introduced which will fall within the scope of my claims, and it is therefore my intention not to conne my invention to such a limited application. v

What I claim and desire to secure by' Letters Patent is:

l. A process for converting normally gaseous hydrocarbons to normally liquid materials, which comprises passing saidgaseous hydrocarbons in liquid condition in a conned stream through a heating zone wherein they are heated to temperatures of from 750 F. to 12.50 F. under pressures of from 500 pounds to 3500 pounds per square inch, reducing the pressure on the products resulting from said temperature and pressure conditions and passing said products into a first rectifying zone maintained under a pressure of from 150 to 350 pounds per square inch, rectifying said products in said rectifying zone to obtain a fraction lighter than gasoline, a gasoline containing fraction, and a fraction heavier than gasoline, subjecting said fraction lighter than gasoline in a condensing zone tocondensation under the pressure existing in said iirst rectifying zone, passing the resulting condensate and uncondensed xed gases from the condensing zone to a receiving zone, mixing the condensate with fresh liqueed normally gaseous hydrocarbons, returning a portion of said mixture as reflux to said i'lrst rectifying zone, withdrawing xed gases from the receiving zone, withdrawing the fraction heavierthan gasoline from the said first rectifying zone, passing said gasoline containing fraction from an interme-I diate portion of said first rectifying zone to an intermediate portion of a second rectifying zone, said second rectifying zone being maintained under lower pressure than said first rectifying zone, rectifying said gasoline containing fraction in said second rectifying zone to form a vaporous fraction comprising substantially all of said gasoline and a liquid fraction heavier than said gasoline, removing said liquid fraction from the process, withdrawing said vaporous fraction and dividing it into rst and second vapor streams, treating the rst vapor stream and thereby removing impurities therefrom, returning said impurities to said second rectifying zone, subjecting the remainder of the rst vapor stream to condensation and thereby obtaining treated gasoline, subjecting the second vapor stream to condensation, and returning the latter condensate to said second rectifying zone.

2. An apparatus for converting normally gaseous hydrocarbons to normally liquid materials, including means for maintaining said hydrocarbons in a liqueed condition, means for heating said liquefied hydrocarbons under pressure, means for rectifying products of said conversion to permit separation of said products into a fraction lighter than gasoline, a gasoline .con- 'taining fraction and a fraction heavier than gasoline, means for condensing said fraction lighter than gasoline, means for separating the resulting condensate into a liquid and a vaporous portion, means for returning said liquid portion to said heating means together with fresh charge, means for further rectifying said gasoline containing fraction, means for dividing vapors leaving said Vlast mentioned rectifying means, means for treating a part of said divided vapors, means for separating treated vapors from impurities formed in said treating means, means for returning said impurities to said last mentioned rectifying means, means for condensing said treated vapors separately from any other vapors, means for separately condensing the other part of said divided vapors, means for collecting this latter vcondensate in an apparatus having means in conjunction therewith, whereby the aforesaid division of said vapors leaving said last mentioned rectifying means is automatically accomplished, means for returning said latter condensate to said last mentioned rectifying means, means for circulating said fraction heavier than gasoline from said last mentioned rect-ifying means through a secondary heating means disposed in hot gases leaving said heating means and back to said last mentioned rectifying means, and means for withdrawing a portion of said fraction heavier than gasoline from said last mentioned rectifying means.

3. A process for converting normally gaseous hydrocarbons to normally liquid materials, which comprises passing said gaseous hydrocarbons in liquid condition in a confined stream through a heating zone wherein they are heated to temperatures of from 750 F. to 1250 F. under pressures of from 500 pounds to 3500 pounds per square inch, reducing the pressure on the products resulting from said temperature and pressure conditions and passing said products intoa first rectifying zone maintained under'a pressure of from 150 to 350 pounds per square inch, rectifying said products in said rectifying Zone to obtain a fraction lighter than gasoline, a gasoline containing fraction, and a fraction heavier than gasoline, subjecting said fraction lighter than gasoline in a condensing zone to condensation under the pressure existing in said first rectifying zone, passing the resulting condensate and uncondensed fixed gases from the condensing zone to a receivingy zone, mixing the condensate with fresh liquefied normally gaseous hydrocarbons, returning a portion of said mixture as reflux to said first rectifying zone, withdrawing fixed gases from the receiving zone, withdrawing the fraction heavier than,

gasoline from the said first rectifying zone, passing said gasoline containing fraction 4,from an intermediate portion of said first rectifying zone to an intermediate portion of a second rectifying Zone, said second rectifying zone being maintained under lower pressure than said first rectifying Zone,rectiiying said gasoline containing fraction in said second rectifying zone to form a vaporous fraction comprising substantially all of said gasoline and a liquid fraction heavier than said gasoline, removing said liquid fraction from the process, withdrawing said vaporous fraction and dividing it into first and second vapor streams, passing one of said streams through a vapor phase treating zone and purifying the same therein, separating purified vapors from uncondensed impurities, condensing said purified vapors, passing the other stream of said gasoline vapors directly to a second condensing zone, subjecting the last mentioned stream in the second condensing zone to condensation and passing the resulting condensate to an accumulating Zone, and utilizing the liquid level of the last mentioned condensate in said accumulating zone to' automatically divide lsaid gasoline vapors into two streams.

4. In a process for converting normally gaseous hydrocarbons to normally liquid hydrocarbons, passing said gaseous hydrocarbons in liquid condition in a restricted stream through a heating zone, wherein they arc heated to temperatures of from '750 to 1250c F; under pressures of from 500 pounds to`3500 pounds per square inch, reducing the pressure on the products resulting from said temperature and pressure conditions and passing said products into a first rectifying zone maintained under superatmospheric pressure but at pressures below that existing in the heating zone, rectifying said products in said rectifying zone to obtain a fraction lighter than gasoline, a gasoline containing fraction, and a fraction heavier than gasoline, subjecting said fraction lighter than gasoline to condensation under the pressure existing in said first rectifying zone, mixing the resulting condensate with fresh liquefied normally gaseous hydrocarbons, and returning a portion of said mixture as refiux to said first rectifying zone.

5. In a process for converting normally gaseous hydrocarbons to normally liquid hydrocarbons, passing said gaseous hydrocarbons in liquid condition in a restricted stream through a heating zone, wherein they are heated to temperatures of from 750 to 1250u F. under pressures of from 500 pounds to 3500 pounds per square inch, reducing the pressure on the products resulting from 'said temperature and pressure conditions.V

and passing said products into a first rectifying zone maintained under superatmospheric pressure but at pressures below that existing in the heating zone, reetifying said products in said rectifying zone to obtain a fraction lighter than gasoline, a gasoline containing fraction, and a fraction heavier than gasoline, subjecting said fraction lighter than gasoline in a condensing zone to condensation under the pressure existing in said first rectifying zone, passing the resulting condensate and uncondensed fixed gases from the condensation zone to a receiving zone, mixing the condensate with fresh liquefied normally gaseous hydrocarbons, returning a portion of said mixture as reflux to said first rectifying zone, withdrawing fixed gases from the receiving zone, withdrawing the fraction heavier than gasoline from said first rectifying zone, passing said gasoline containing fraction from an intermediate portion of said first rectifying zone to an 'intermediate portion of a second rectifying zone maintained under lower pressure than said first rectifying zone, rectifying said gasoline fraction in said second rectifying zone to form a vaporous fraction comprising substantially all of said gasoline, and a liquid fraction heavier than said gasoline, removing said liquid fraction from the process, and subjecting said vaporous fraction to condensation.

6. In a process for converting normally gaseoushydrocarbons to normally liquid hydrocarbons, passing said gaseous hydrocarbons in a liquid condition in a restricted stream through a heating zone, wherein they are heated to a temperature of` from 750 F. to 1250 F. under pressures of from 500 pounds to 3500 pounds per square inch, reducing the pressure on the products resulting from said temperature and pressure conditions and passing said products into a first rectifying zone maintained under superatmospheric pressure but at pressures below that existing in the heating zone, rectifying said proddensate with fresh liquefied normally gaseous hydrocarbons, and returning a portion of said mixture as reux to said first rectifyng Zone and another portion of said mixture to the said restricted lstream. MALCOLM P. YOUKER.

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