Treatment of hydrocarbons

June 2, 1936.

2,042,452

J. H. BOYD, JR

TREATMENT OF HYDROCARBONS

Filed. Sept. 8, 1933

<img file="US2042452A_D0001.tif" />

Patented June 2, 1936

2,042,452

UNITED STATES PATENT OFFICE

2,042,452 TREATMENT OF HYDROCARBONS James H. Boyd, Jr., Philadelphia, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania

Application September 8, 1933, Serial No. 688,600 (Cl. 196—9)

My process is to be distinguished from those processes of the prior art which suggest the recycling of uncondensed gases to a cracking system for the purpose of reducing gas formation by operation of the law of mass action. 5 In the cracking of hydrocarbon oils, heat must’ be supplied to effect the decomposition of the higher boiling hydrocarbons into those of lower boiling range, i. e., the cracking is an endothermic reaction. However, it has been found that the JO polymerization of unsaturated hydrocarbons to form higher boiling compounds is an exothermic reaction, i. e„ when the unsaturates are heated to a temperature sufficient to start the polymerization, the reaction takes place with the evolution 15 of heat. By introducing the relatively cool liquefied gases into the reaction chamber together with the heated products from the cracking tubes, a reduction in temperature is effected so that cracking and/or polymerization of the oil 20 from the heating tubes is effected with the formation of less carbon, and simultaneously the liquefied gas is raised to a temperature sufficient to initiate the polymerization of the components thereof. 25

For a further understanding of my invention, reference is made to the accompanying drawing which illustrates an arrangement of apparatus suitable for carrying on my process.

Hydrocarbon oil is withdrawn from storage 30 (not shown) through pipe I and is forced by means of high pressure feed pump 2 through pipe 3, heat exchange coil 4 in the top of fractionating column 10, pipe 5, heat exchange coll 6 in the top of evaporating tower 21, pipe 7 and pipe 8 into 35 reaction chamber 9. Gas oil is drawn from storage (not shown) through pipe 36 and is passed by low pressure feed pump 37 through pipe 38 into a lower bubble plate section of the fractionating tower 10. This gas oil is heated therein by con- 40 tact with the vapors of the incoming cracked products from pipe 22 of evaporator 21, and such gas oil together with reflux condensate from column 10 is withdrawn from the bottom of the column through pipe II, and valve controlled 45 pipe 12, and is passed by means of hot oil pump 13 through pipe 14 into heating tubes 15 of furnace 16. Herein the oil is heated to a temperature of the order of from about 940° F. to 960’ F. and is passed through pipe 17 and pipe 8 into re- 50 action chamber 9. Simultaneously a suitable quantity of liquefied gas is drawn from storage . (not shown) through pipe 39 and is forced by means of high pressure pump 40 through valve controlled pipe 41 and pipe 8 into reaction cham- 55

Claims.

The present invention relates to a process ofl hydrocarbon oil conversion and more particularly to the polymerization of unsaturated gaseous hydrocarbons to form liquid hydrocarbons of the 5 motor fuel boiling range.

A particular object of my invention is the polymerization of hydrocarbons containing from 2 to 5 carbon atoms to the molecule by subjecting the same to the action of heat and pressure in the 10 reaction chamber of a pressure cracking apparatus, thereby to increase the yield of motor fuel produced.

A further object of my invention is the cooling of the cracked products issuing from the cracking 15 furnace tubes during their introduction into the reaction chamber, said cooling being effected by the Injection of liquefied gaseous hydrocarbons or liquefied gases in admixture with higher boiling hydrocarbons.

2Q In many processes of pyrolytic decomposition of high boiling hydrocarbon oils to produce motor fuels, the oil is heated in tubes and rapidly raised to a cracking temperature, and subsequently the heated oil is maintained at the cracking tem25 perature for a period sufficient to permit the formation of appreciable quantities of hydrocarbons of the gasoline boiling rapge. Generally, in the operation of liquid phase cracking processes, the high boiling oil introduced from the heating tubes into the reaction chamber will be at a temperature in excess of 850° F., and under a pressure in excess of 250 Ibs./sq. in. Furthermore, in cracking processes where the oil in the heating tubes is raised to an abnormally high temperature in order^-to obtain high cracking rates, it is desirable to cool the oil to a certain extent before introducing it into the reaction chamber, to prevent the formation of relatively large amounts of carbon, which would occur at such high temperatures, e. g., when cracking at temperatures above 950° F., in the heating tubes, it is desirable to cool the oil so that the temperature in the reaction chamber is not substantially in excess of 900° F. .

I propose to utilize the heat available m the reaction chamber for the polymerization of the normally gaseous unsaturated hydrocarbons, particularly propylene and butylenes, or mixtures thereof occurring in or produced from liquefied 50 gases from petroleum or natural gasoline refineries, and simultaneously to effect a partial cooling of the heated oil entering the reaction chamber by the introduction of the liquefied gas either alone or in admixture with higher boiling 55' hydrocarbons, as for example, gas oil.

2,043,452 her 9. The heated oil from the tubes i 5 is thus partially cooled in the reaction chamber, and the process of cracking, and of polymerization of the unsaturated components of the liquefied gas is S effected therein at a temperature of the order of from about 865° F. to 900° F., and under a pressure of about 750 Ibs./sq. in.

The products from the reaction chamber 9 are withdrawn by means of pipe 18 and the pres10 sure is reduced from about 750 Ibs./sq. in. to about 70 Ibs./sq. in. by means of valve 19, and the liquid-vapor mixture is introduced through pipe 20 into evaporator 21. Due to the relatively low pressure, of the order of 70 Ibs./sq. in., main15 tained in the evaporator, the lower boiling components of the mixture introduced pass as vapor from the upper portion of evaporator 21 through pipe 22 into fractionating column 10. The tar and high boiling hydrocarbons which are stripped 20 from the vapors in evaporator 21 are withdrawn from the bottom of the evaporator by means of . valve controlled pipe 23. The vapors entering fractionating column 10 are stripped of their heavier components, such as, for example gas oil, 25 in passing upwardly through the column in contact with reflux condensate and gas oil introduced thereinto. The vapors passing from the top of column 10 comprises substantially the hydrocarbons of gasoline boiling range. These vapors are 30 passed through pipe 24, partial condenser 24α and pipe 25α into reflux drum 25. A portion of the cracked distillate vapors which were condensed in partial condenser 24α are withdrawn from drum 25 through valve controlled pipe 33 35 and are passed by means of reflux pump 34 and pipe 35 into column 10 to serve as reflux in such column. The remaining condensate from the bottom of drum 25 and the vapors from the top of said drum are passed to condenser 28 through 40 valve controlled pipe 27, and pipe 26 respectively.

In passing through condenser 28, substantially all the material which may be condensed, under the conditions of temperature and pressure therein, is condensed and passed through pipe 29 into 45 gas separator 30. The condensate, i. e., cracked gasoline, is separated from the uncondensed gases, the gasoline being withdrawn from the bottom of the separator by means of valve controlled pipe 32, while the gases are passed from 50 the top through valve controlled pipe 31.

It may, in some cases, be preferable to admix the liquefied gas with the oil charged to the system through pipe I and pump 2 instead of introducing said liquefied gas directly to the reaction 55 chamber through pipe 39 and pump 40. Or, it may be desirable to introduce the liquefied gas in admixture with heavier hydrocarbon oil, such as for example, gas oil, into the reaction chamber 9 by means of pipe 39, pump 40, valve 41 and 60 pipe 8.

The operating conditions, 1. e., temperature, pressure and time which may be given in the above description are merely exemplary, and I do not intend to limit myself thereto, as my proc65 ess is operable under various conditions of temperature, pressure and time depending upon the character of the oil charged, the composition of the liquefied gas and the properties of the gasoline desired. Furthermore, my process is equally 70 applicable to vapor phase as well as liquid phase systems.

Reference to the table given below shows the results obtained from actual operation of a liquid phase cracking system with and without the use 75 of liquefied gas. The liquefied gas used had the following approximate composition: propane 8%, propylene 2%, butanes 45%, butylenes 45%.

<td></td><td> Without liquefied gas</td><td> With liquefied gas ₅</td>

<td> Oil charged (bbls.)________________</td><td rowspan="8"> 11,807 6,504 3,737 7,142,000 55.08 31. 65 13. 27</td><td rowspan="8"> 13,973 7,940 4,395 8,310,000 ₁₀ 56.82 31.45 11.73</td>

<td> Products (bbls.) Motor fuel________________</td>

<td> Tar__________________</td>

<td> Gas (cu. ft.)............</td>

<td> Products (percent yield) Motor fuel________________</td>

<td> Tar______________</td>

<td> Gas_________________</td>

<td></td>

From the above table it will be seen that by _roperating in accordance with my invention the ¹⁵yield of motor fuel was increased by 1.74%, the yield of tar was decreased by 0.20% and the yield of gas was decreased by 1.54%.

For brevity, in the appended claims the term “liquefied gas” is to be understood to comprehend ²⁰low boiling hydrocarbons or mixtures of low boiling hydrocarbons containing from 2 to 5 carbon atoms to the molecule. It is also to be understood that the “liquefied gas” after introduction into the cracking system, may or may not ²⁵remain in the liquid phase, depending upon the operating conditions of temperature and pressure.