US2412427A - Refining of low-grade hydrocarbon oils - Google Patents

Description

E. H. RECORDS. 2,412,427

REFINING OF' LOW-GRADE HYDROCARBON OILS Filed Ndv. 1o, 1944 Dec. 10, 1946.

' INVENTOR. f/mer H. Re c OrO/5 Patented Dec. 10, 1946 UNITED HCE REFINING F LOW-GRADE HYDROCARBON OILS 6 Claims.

506,109, considered within the industry as being entirely unworkable or, at best, giving such a low yield in products of distillation as to preclude profitable rening. More especially, it is an object of the present invention to devise a process which, while it may perforce be applied' in the relining of high-grade hydrocarbon oils, peculiarly lends itself to low-grade stock and, in working same, gives a return in low-boiling high-gravity products of distillation commensurate with, if not exceeding, the recoveries obtainable from even the lightest crudes under customary cracking techniques.

The invention further aims to provide an inexpensive and eicient plant for carrying the process into effect, a plant which is quite flexible as to design, and which admits to profitable operation Whether engineered to accommodersmall or large volume runs.

According to the presentv invention there is employed a horizontal retort quite similar to the still which is embodied in the plant used to carry my said prior process into effect. This retort may be of any desired capacity and, considered in more particularity, is or may be of cylindrical form heated through the instrumentality of electrically energized bayonets received within the retort, running lengthwise thereof, and occupying positions in spaced parallel relation above the oor but below a given lling level which approximates 33% of capacity. An inlet pipe terminally litted with a nozzle extends into an end of the retort above said liquid level, and a gas take-off leads from the ceiling limit, there being also provided and connecting with the retort at its low limit a pipe which gives communication between the retort and a subjacent upright holding tank, In carrying the process into effect, the material to be treatedis brought to a pre-heated temperature of between 400 F. and

700 F. depending upon the determined vaporization point and this pre-heated oil is pumped into the retort in sufficient quantity to bring the level within the latter to said 30%, or an approximate 30%, of capacity, All outlets being closed, heat from the electric bayonets is applied to the oil body until an approximate 200 p. s. i. (pounds per square inch) vapor pressure obtains in the dome of the retort, and augmenting hot oil is then pumped through the admission nozzle to project the same in a une spray horizontally of the dome, this step of spraying an injection of mechanically broken hot oil through the lighter volatiles present in the vapor chamber being found to materially aid conversion of the heavy oil into lighter products. As this spraying step proceeds the vapor pressure is maintained at 200i p. s. i. by partially opening the discharge valve ior the gas take-oli line, the liberated gases passing to a condenser. The yield from this step will run between and 60% of total input, gravity being about l0 A. P. I.

Spray introduction of hot oil continues until the distillation conversion ceases and which is evidenced by a dropping pressure, recourse being had to a gauge-fone of three (pressure, temperature and level) necessarily carried by theretortand whereupon the pumping is stopped. The gasdischarge valve is now fully opened until the vapor pressure drops to zero. Closing this valve, heating is continued and further conversion takes place until the pressure of the light volatiles formed builds up to 850 p. s. i., the heating being then stopped and these vapors being also allowed to escape through the take-01T line to the condenser. This step of the process gives a further recovery, in light ends of around 40 A. P. I. gravity, of from 25% to 35% of the charge in the retort.

The operator now drops the stock left in the retort to the subjacent holding tank, the retort and the tank are again isolated, and the still is replenished with fresh oil stock and the described steps repeated, theresidue from a severalty of these conversion operations being successively dropped `to the holding tank which iskept at a temperature of about 600 F. Within the holding tank, the very heavy ends of the dropped charges together with contained sludge, dirt and free carbon settle into a sump and may be drawn off at intervals. This draw-oit is or may be supplied to an oil-fired burner to function, at least in part, as fuel therefor and which burner serves as the agency for pre-heating the fresh stock and maintaining the holding tank at its said 600 F. temperature.

The cleaner portions oi the oil contained in the holding tank, as the contents near capacity -by successive charging from the overlying retort, are now pumped back into the retort in a quan- `tity bringing the liquid level within the latter to charge.

currently returned oil from the retort, removing said given 30%, or an approximate 30%, of capacity and, closing all outlets, heat from the electric bayonets is applied until there is again developed. a vapor-pressure condition approximating 850 p. s. i. The produced volatiles from this step are also released from the retort to the condenser, and the liquid body remaining is returned to the holding tank, this operation showing afurther yield approaching 35% of the retorts The steps Of allowing settling of the the very heavy ends from the sump, re-charging the retort with cleaner portions, and again drop- Y ping the residue from the repressuring treatment of these charges is repeated until substantially all of the oil possible of conversion into volatiles is recovered. Another series of distillation conversions from fresh stock is then performed.

Where ra battery of" stills or, more properly, repressuring retorts are employed, it becomes possible to closely approximate a continuous process in that distillation conversions and pressure .conversions may be carried on simultaneously.

In- Figur 1 of the accompanying drawing I have illustrated, schematically, a plant for the working of the present process and, referring thereto, it will be seen that heat from an oillred furnace denoted by the numeral 2 is applied to `coils 3 through which fresh stock to be treated is passed, the pump indicated at el carrying this pre-heated oil through a supply pipe 5 to the retort 6 which, as shown, is placed horizontally and, by preference, overlies the furnace. Said supply line feeds into an end of the retort and is disposed proximate to the latters ceiling limit, and upon its delivery end is fitted with a .nozzle 5. The form and placement of this nozzle, as with the electrically-heated bayonets 1,

desirably follows the teachings of my said prior filing, Ser. No. 506,109. Fig. 2 is a'fragmentary vertical sectional view portraying such nozzle.

-Denoted by 8 is the valved discharge pipe for the take-off of the gases connecting with the retortat the ceiling limit of the latters vapor dome, and branching into this pipe and with the latter leading to a condenser 9 is a gas pipe I0 similarly tted with a closure valve and extending from the head end of an upright vessel I I which lies subjacent to the retort. VThis vessel is the referred-to holding tank and, given a comparay tively large capacity, is desirably placed in the path of the delivered heat of the furnace Z or, otherwise stated, in a breeching I2. There is provided a sump I3 for said holding tank, and a cllaw-off line I4 therefrom equipped with a pump Designated f I6, a valved pipe connects with the .bottom of the retort, and running from this pipe and giving a' gravity flow to the holding tank is a valved pipe I'I, there being also provided and `likewise connecting with but normally isolated by a valve from such pipeV I6 a return line I 8 equipped with a pump I9.

Giving a summation of the recoveries, and which-have been established through extensive treatment of the very heaviest stocks obtainable-` oils deemed to be practically unworkable by general consensusvof-the industry-the total yield from the process considered in terms of the oil volume treated has quite frequently approached l 90% and consistently runs better than '70%. On

a break-down basis, and whichis to say separating the process into its two component phases, the initial distillation conversion of fresh'stock and the following high pressure treatment Qf the out the same.

. 4 Y' residues therefrom, vthe low-boiling volatiles recovered by the former procedure run between 30% and 60% of the oil treated While the additional low-boiling volatiles recovered in the high pressure treatment will be between 30% and 470%.

The process can be profitably carried on whether practiced with a large or a small capacity plant, the plant being such as ltocallfor a comparatively small investment and needing but little ground area, relatively speaking, for laying Aside therefrom, however, it becomes not only possible, but highly practical, to

nworkV oil bodies which, previous to this and the continuous process of my prior filing, have found a market outlet'only as low-grade fuel oils, road Y surfacing, and the like, markets which can absorb but a small part of the available heavy oils, with the result that this class of hydrocarbons have been largely dumped.' Disregarding the fire hazard, and the unsightly and smelly conditionsY created by this dumping, the more serious consequence is an increasing depletion of petroleum crudes due to a failure to extract from the vreiinery stock anything approaching the contained quantity of volatiles. Y Y

The process perforce admits to some variations y from the particular pressures and heats hereinbefore set forth, albeit my findings show that any material departures therefrom noticeably and adversely afectreturns. no limitations be implied Yother than thosev expressly brought into the hereto annexed claims to distinguish the Yadvanced teachings y of the process, and the apparatus for practicing same.

What I claim is: 1. The new method of refining low-grade Vhydrocarbon oils and which comprises the steps of pre-heating the oil to a temperature of between 400 F. and 700 F. depending upon the determined vaporization point and supplying this prefheated stock to a retort in quantity sufficient to charge the latter to approximately one-third of its tota] capa-city; sealing the charge and applying heat to develop a pressure condition ofVv approximately 200 p. s. i. and then injecting a spray of supplementing hotY oil through the'produced gases while passing off and condensing such-portion of the evolved vapors as becomes'necessaryV to maintain said given pressureV condition; terminating the spray injection as pressurer drops on, and passing off and condensing the remaining vapors while continuing to' apply heat; again sealing the oil contained in the retort and allowing pressure to buildup to approximately 850 p. s. i., whereupon vapors evolved from Vsuch high-pressure treatment are passed off and condensed and the residue dropped to a subjacent holding tank held at a temperature approximating 600 F.; performing the described steps repetitivelyand, from the aggregate of the dropped pre-heating the oil to a temperature of 400i" 1l'.` or better and charging same to a retort in a quan- Y tity suiicient to lill the latter to approximately a third of total capacity; sealing the charge 'and It is my intention that applying heat to develop a pressure condition of approximately 200 p. s. i. and thereafter spraying an injection of supplementing hot oil through the produced gases while coincidently passing 01T and condensing such portion of the evolved vapors as becomes necessary to maintain said pressure condition; terminating the spray injection as pressure drops off, and passing 01T and condensing the remaining vapors while continuing to apply heat; again sealing the residue of the charge and repressuring to an approximate 850 p. s. i.; passing oir" and condensing the vapors evolved in this high-pressure step; and treating the residue by withdrawing the same from and thereafter returning lighter portions to the retort in successively performed operations during which the returned lighter portions are repressured to said 850 p. s. i., the evolved vapors passed 01T and condensed, and the very heavy ends of the withdrawn residues allowed to settle out.

3. The method of claim 2 in which the residue from the repressuring treatments is maintained -at an approximate 600 F. temperature throughout the period of its cyclic withdrawal from and return to the retort. j

4. The new method of rening low-grade hydrocarbon oils and which comprises the steps of charging the oil to a retort in such a quantity as will leave a vapor dome of relatively large Capacity above the liquid level therein, and sealing :J

the charge and applying heat to develop a pressure condition approximating 200 p. s. i.; passing off and condensing the vapors evolved from this heat-and-pressure step; sealing the remaining liquid of the charge within the retort and by continued application of heat stepping upthe pressure condition to an approximate 850 p. s. i.; passing off and condensing the vapors evolved from the repressuring step; taking the residue from this and corresponding treatment performed upon other charges of oil and, while maintaining in a hot state, allowing the very heavy portions to settle out; and subjecting the lighter portions of the aggregate of these residues to repetitive cyclic treatment in which the said lighter portions are again made subject to said repressuring, the evolved vapors passed off and condensed, and the residues in each instance returned for the settling out of the very heavy ends.

5. The new method` of refining low-grade hy'-v drocarbon oils and which comprises the steps of charging a body of the oil into a retort to approximately a third of the latters capacity and, applying heat while sealing the retort against escape of the produced vapors, creating a pressure condition of approximately 200 p. s. i.; spraying hot oil into the retort to have the augmenting oil traverse the vapor dome which lies above the liquid level and coincidently passing off and condensing such portion of the produced gases as becomes necessary to maintain said pressure condition; terminating the spray injection as pressure drops 01T, and releasing and condensing the remaining vapors; and continuing the application of heat'while again closing the retort until a high-pressure condition of approximately 850 p. s. i. is developed, thereupon passing oi and condensing the additional vapors evolved thereby,

6. In a system for reiining low-gradefhydrocarbon oils, Ithe plant therefor comprising, in combination: a furnace having a breeching; a coil pressure-fed from a supply of the oil and 0ccupying a position within the breeching to act as a pre-heater for the oil passed therethrough; an upright holding tank of comparatively large capacity likewise disposed within the breeching,

kformed with a sump for oil settlings, and having a draw-01T line for removal of the latter; a retort of extended length disposedhorizontally in elevated relation to the tank, and arranged to be charged with oil to approximately one-third of capacity leaving a vapor dome above the liquid level therein; an oilsupply pipe from the coil into the vapor dome of the retort fitted upon its delivery end with a nozzle arranged to project the hot oil longitudinally and inthe form of a spray; a heating instrumentality functional Ato the oil -contained in the retort; a condenser; a valved connection from the ceiling limit of the vapor dome to the condenser; a valved gravity-

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