US1981144A - Process for the conversion of hydrocarbon oils - Google Patents

Description

Nov. 20, 1934. J. B. HEID I PROCESS FOR THE coNvEnsIoNbF HYDROCARBONIOILS Fi led March 2a, 1930 vzwrox? d cowe amm Heid wd/"Mm Patented Nov. 20,1934

I 1,981,144 I raocass roa THE CONVERSION or oFmcr:

HYDBOCARBON OILS Jacob Benjamin Heid, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., v a corporation South Dakota Application March 28, 1930, Serial No. 439,584:

4Claims.

This invention relates to a process for the treatment of hydrocarbon oils and is specifically directed to the conversion of hydrocarbons while 'in a vaporized state by both direct and indirect 8 heat transfer between hydrocarbon vapors and products of combustion. Y

Many processes have been proposed for the conversion of hydrocarbons in a vaporized state by indirect heating. It has also been proposed to subject hydrocarbon vapors to conversion temperatures by heating in direct contact with hot combustion gases. In the present invention, both methods of heating are utilized; hydrocarbon vapors being first subjected to both radiant and convection heat transmitted to the hydrocarbon vapors through a suitable separating medium such as a metallic or refractory wall, thence subjecting the vapors to further heating by direct contact with the hot combustion gases from the first or indirect heating stage. This invention 'alsoprovides a method of supplying additional heat to and effecting further conversion of the hydrocarbon vapors by their own' partial combustion. This combustion of a portion ofthe hydrocarbons undergoing treatment is accomplished by the introduction of regulated quantitles of an oxidizing gas such as air or oxygen into the hydrocarbon vapors undergoing treat-' ment. This oxidizing agent may be introduced with the combustible fuel in the form of air in quantities slightly in excess of that required for the combustion of the fuel. The quantity of excess air thus introduced is controllable and may be entirely eliminated, if desired.

As preferably practiced in this invention, the

= exact regulation of the quantity of excess air introduced with the fuel permits close control of the final conversion temperature of the hydrocarbon vapors, provides the most economical form of heating, and may bring about or assist the formation of valuable oxidation products which will' materially increase the'anti knock value of the finished product from the system. Other advantages in the form of improved operating conditions and results, as well as structural advantages, will be apparent upon reference to the attached drawing which illustrates one specific form of apparatus in'which my process may be practiced. This illustration is diagrammatic and is not drawn to scale. 4

Referring now to the drawing, the oil to be converted enters pump 3 through line 1 and valve 2, emerging therefrom through valve 4 and line 5 to be fed to the process in any or a combination of several ways. All or a portion of the raw oil maypass from line 5 through valve 6 and line 7 into the stabilizing tower 9 to be collected in the bottom thereof and supplied throughvalve 11 to line 101 All or av portion of the raw oil from line 5 may, however, passthroughvalve 12 directly into line- 10. The oil from line 10 is supplied to pump 13 through valve 14 and, by means of pump 13, may

be fed through valve 15, line 16, valve 17, line 18, and may be fed into the fractionating tower 20' through either or in part through both of the valves 21 and 21a., The raw oil thus fed into the fractionating tower 20, after assisting fractionation in this zone and being thereby pre-heated, collects in'the bottom of fractionating tower 20 together with reflux condensate, and the com- I0 bined product flows through valve 23 and line 24 back into line :16. Any portion or all of the raw oil, instead of passing through the fractionating tower 20, may pass directly through valve 26 in line 16, thereafter combining with reflux from the fractionating zone. However, the total combined feed, consisting of reflux condensate and raw oil, wheth combined within or-outsidethe fractionat" g zone 20, eventually flows through valve 33 to pump 32 from which it is fed through valve 34 and line 3, and may pass wholly or in part through valve 36 into the heating element 37, or may -by-pass the heating element through valve 42. 3 v

Heating element 37 is located in a suitable furnace 38, and oil passing through the heating element 37 may be subjected to any desired temperature and pressure conditions ranging from 'subatmospheric to high super-atmospheric pressures and from, say, 500 FQto 1000" F., more or'less. Ordinarily, however, in this process the oil is subjected in passing through heating element 37 only to such conditions as will cause vaporization of a substantial portion of the oil. Cracking conditions may or may not prevail in heating element 37, dependingupon the type of oil undergoing treatment and the desired results. Heated products from heating element 37 emerge through valve 39 into line 40. The pre-heated combined feed from line 35 may, when heating element 37 is not used, by-pass the heating element and enter line 40 through valve 42. From line 40 the products may pass through valve 67'and line 68 into reaction chamber 69. Here the vaporous and liquid portions of the material maybe separated,

the vapors passing through line 70 and valve'll ,back into line 40, and the unvaporized portions heating. In any case, chamber 69 may be maintained at substantially the same pressure as that employed in the heating element 37 or at a reduced pressure.

The substantially vaporized products from line 40 are fed into the vapor phase cracking apparatus 41 through a suitable means, such as spray coil 51. Apparatus 41 is, in this case, composed of an outer refractory wall lined in its lower 01' hottest, portion with a super-refractory material 47, such as carborundum. Wall 46 is so constructed that an annular space-is provided between wall 46 and lining 4'7'of the external furnace wall. It islbetween the super-refractory surfaces of walls 46 and 47 that a major portion of the combustionof fuel introduced for heating takes place, andv the flame is preferably confined primarily to this portion of apparatus 41. Wall 46 may also be constructed of carborundum brick sothat it will become incandescent upon heating and will transmR radiant heat to the refractory or metallic liner 48. A reaction zone 49 is located within the vapor phase cracking zone 41 and its lower portion at least is surrounded by the metallic or refractory wall 48. There are then three concentric annular spaces provided within apparatus 41. One of these, formed between walls 46 and, 47 and designated as 47a, forms primarily the combustion"or radiant heat zone. The second annular space, formed between walls 46 and 48 and.

designated as 46a, forms primarily the convection heat zone. The third annular space, between wall 48 and the outer surface of reaction chamber 49, is designated as 48a, and is the space into which the hydrocarbon vapors are' introduced and in which these hydrocarbon vapors may be heated by both convection and radiant heat transmitted 'through wall 48.

The degree of conversion of the hydrocarbons which may take place in zone 48a is entirely controllable by regulation of the furnace conditions within apparatus 41 as well as by the temperature of the products introduced thereto through line 40. It will be readily understood that any conversion in zone 48a is accomplished by indirect heat transfer between the combustion products and the hydrocarbons.

As the process is preferably operated, 'all of the conversion does not take place nor does all of the heating occur in space 48a, but the hydrocarbon products and combustion gases are allowed to mix in space 490,, and the hydrocarbon products passing up through reaction zone 49 are further heated and undergo further conversion by direct contact with the combustion products from space 46a mixed therewith in space 49a. If desired,,this heating and. reconversion may be furtheraugmented by the direct combustion of a portionof the hydrocarbons undergoing treatment in zone 49.

This is accomplished by permitting regulated portions of excess air to enter .with the combustible products introduced to zone 'mospheric or super-atmospheric pressure, and the pressure employed my be substantiallythe same as that employed in heating element 37' or cham- 1 ber 69, or' it may be a diifereritial pressure.

The products from zone 49 may pass through line 53 and valve 53a into the fractionating tower 20 where their lighter portions may be separated from their heavier portions by fractionation and partial condensation. portions of the vapors together with the unvaporized raw oil introduced to" tower 20, as above described, return through valve '23,. lines 24 and 16, valve 33 and pump 32 to the system forretreatment, as already described.- A portion of this product from line 24 may, however, be re-cycled back to the fractionating tower 20 The heavier condensed to further assist fractionation therein. This recycling is accomplished by passing the desired portion of the oil from line 24 through valve 28 and line 27 to pump 29 which feeds the product through valve 30, lines 31, 16 and valve 17 into line 18 from which the re-cycled products may be. fed to tower 20 through valve 21 or valve 21a, or in part through both.

The quality of the light vapors withdrawn from fractionating tower 20 is controlled by the temperature maintained at the top of this tower, and

in this embodiment of the process is preferably such that these vapors correspond in boiling range to motor fuel. These vapors are'withdrawn from tower 20 through line 54 and valve 55, are subjected to condensation and cooling in condenser 22, thereafter passing through valve 56 tobe collected in receiver 57. The separation of the condensed distillate and uncondensed gas is effected in receiver 57. The distillate is withdrawn to storage or elsewhere through line 59, controlled by valve 60. The uncondensed gases may be withdrawn from receiver 5'7 and from the system, if desired; by means not shown, but are preferably subjected to further treatment to effect separation therefrom of any entrained liquid or 'easily absorbed vapors therein. This is accomplished by passing the gas through line 58'and valve 62 into pump 61 which forces the gas through line 63 into absorption tower 9.- In tower .9 the gas, thus introduced may be subjected to the absorbent action of raw oil introducedto tower 9 through line 7, as already described,.or by contact with any other suitable absorbent material introduced to tower 9 by means not shown. The 2 final dry gas is released through line 64, controlled by valve 65. Y

As a. specific example of one of the many operations possible by the use of my process and in an apparatus similar to that above shown, a 24 A. P. I. gravity Mid-Continent fuel oil is subjected in heating element3'7 to mild cracking conditions under an imposed pressure of approxie mately pounds per square inch and an outlet temperature of about 750 F.

All of the heated products, in this case, pass through reaction chamber '69 which is maintained at a reduced pressure of approximately 60 pounds per square inch. This reduced pressure on chamber 69 will serve to vaporize the major portion of 5 1,981,144 .the hot products introduced thereto. The unvaporized portion of the products introduced to chamber 69, which may amount to some of the .total raw oil charged to the process, may be removed as the residual product from the system through line 72 and valve 73. This product represents the heaviest portions of the lightly cracked fuel oil which, if subjected to vapor phase treatment, may form objectionable compounds, but if separated and removed at the stage in the process already indicated, this need not be a waste product but may be utilized as fuel oil, or may be blended with charging stock for a liquid phase Process.

The vapors from chamber 69 are subjected in' the vapor phase cracking zone 48a to a temperature of approximately 950 F. by indirect heat transfer from the combustion products and are further heated in reaction zone 49 to a temperature of approximately 1100 F. by direct contact with the combustion products and by their own partial combustion brought about by the introduction of a small amount of excess air introduced together with the fuel into the vapor phase combustion zone 41.

All of the raw oil introduced to the process is fed overhead to the fractionating tower 20 and the thus pre-heated raw oil, together with the reflux condensate from this zone, is re-cycled to the heating element 37.. The distillate collected in receiver 5'7 may fall within the boiling range of commercial motor fuel, may show an anti-knock rating equivalent to a blend of 70% benzol and 30% straight-run .gasoline, and may amount to as much as 55% of the oil processed. Of the remaining 25%, a large portion is gas of high calorific value which may be utilized as fuel in the refinery, may be blended with producer gas for enrichment of the latter, or may be utilized for a number of other industrial purposes. The proportion of oil consumed by direct combustion in reaction zone 49 is usually relatively small and I is compensated for in part by a reductionin the amount of fuel required to be burned in zone 47a.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises initially distilling the oil and separating resultant vapors from unvaporized oil, thereafter passing the separated vapors in indirect heat exchange relation with a gaseous heating medium while simultaneously heating the vapors by a substantial degree of radiation and then combining the vapors with the heating medium while the latter is at cracking temperature, cracking the vapors by the heat of said medium, and condensing the cracked vapors.

2. A hydrocarbon oil cracking process which comprises initially distilling the oil and separating resultant vapors from unvaporized oil, thereafter passing the separated vapors in indirect heat exchange relation with a gaseous heating medium and then combining the vapors with the heating medium while the latter is at cracking temperature, burning a portion of the vapors while admixed with the heating medium to supply additional heat for the cracking, and condensing the cracked vapors.

3. A hydrocarbon oil cracking process which comprises initially distilling the oiland separating resultant vapors from unvaporized oil, thereafter indirectly heating the separated vapors by a substantial degree of radiation .and convection and then combining the same with a gaseous heating medium at cracking temperature, and condensing the cracked vapors.

.4. A hydrocarbon oil cracking-process which comprises initially distilling the on and separat ing resultant vapors from unvaporized oil, thereafter indirectly heating the separate vapors and then combining the same with a gaseous heating medium at cracking temperature, burning a por- JACOB BENJAIVIDI HEID;

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