US1347664A - Method of refining oil - Google Patents

Description

F. E. WELLMAN.

METHOD OF REF |N|NG OIL. APPLICATION FILED MAR 30. ms.

1,347,664. Patented J lily 27, 1920.

2 SHEETS-SHEET Prlmmm Bml'ram. PUB

. finmmssw Am TANK v Omuqniq ST TmN.

Am Emnassm,

UNITED STATES PATENT'OFFICE.

FRANK E. WELLMAN, OF- KANSAS CITY, KANSAS, ASSIGNOR T0 THE KANSAS CITY GASOLINE COMPANY, OF KANSAS CITY, KANSAS, A CORPORATION OF KANSAS.

METHOD OF REFINING OIL.

Application fil ed March so, 1918. Serial No. 225,683.

To all whom it may concern:

Be it known that I, FRANK E. WVELLMAN, a citizen of the United States, residing at Kansas City, in the county of Wyandotte and State of Kansas, have invented certain new and useful Improvements in Methods of Refining Oil, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates .to methods of refining oil and has for its object in particu-- lar the improvement of existing methods of cracking heavy hydrocarbons.

The leading and characteristic features of my present invention are as follows: (1) The use of a tubular retort operating intermittently upon measured charges; (2) discharging and condensing each charge after cracking for a determinate period and at a determinate temperature and pressure; (3) scouring out and cleaning the retort after each operation; (4) automatic control of heat, pressure, charging and discharging, preferably from a distance; (5) cracking in a horizontal tubular retort containing a determinate fractional charge, so as to leave a determinate vapor space for the maintenance and retention of the lightest products or fixed gases during each operation, whereby the quality and the percentage of converted product are raised, and rendered constant for a given grade of material operated upon.

Ancillary features and advantages will appear from the detailed description hereinafter.

Very briefly stated, 'my apparatus comprises a cracking retort in the form of a horizontal tube; means to heat the same uniformly to a high temperature; a measuring and charging device receiving the petroleum or other hydrocarbon material and delivering it to the, retort in successive charges each of such volume as to partially fill the retort, only; a discharge pipe for the retort leading to condensing apparatus; a steam inlet pipe for the retort, and valves for the charging, discharging, and steam pipes, with pneumatic piston or equivalent control for said valves, operated from a distance; and means responsive to pressure in the retort and if desired to temperature therein, for controlling the operation of the charging device and of all of said valves in proper order. 5

In the specific example hereinafter described, it is assumed that a crude oil or a distillate containing a large percentage of heavy hydrocarbons is to be cracked so as to produce conversion into lighter series within the range of what is commonly known as gasolene, that is to say products havin boiling points between. 50 C. and 175 and that for this purpose the volume of content of the charging device, or the amount of the charge, is from one-fifth to one-fourth of the capacity or volume content of the retort, the temperature to be employed is approximately 600 C. in furnace and the pressure at the end of the cracking period is from 700 to 800 pounds to the square inch. It will be understood that the invention in this case does not depend upon strict adherence to these figures, the lnventlon as such having to do with the control of charge, temperature, pressure, t me, discharge, and scouring, which I be heve have not been accurately and flexibly controlled in systems and apparatus heretofore proposed.- As a matter of fact, my apparatus can be set or adjusted so as to vary the factors mentioned, so as to produce uniform results with various crudes or distillates, and also so as to vary the products from any given primary material. I have found, however, that operating on average swept out before it has become adherent to Specification of Letters Patent. Patented J ly 2'? 1920. I

the walls of the retort, keeping the latter at normal efficiency for heat transmission and enabling me to produce a uniform and effective temperature in the contents without the necessity of raising the furnace .(or equivalent) heat to a point liable to produce burning ofthe metal and destruction of the retort.

I shall not describe herein means for.

' panying drawings in which be connected with the right hand side of the Flgure 1 is a diagrammatic view of a portion of the apparatus used in my process.

Fig. 1 is a continuation of Fig. 1 showingthe remaining portion of my apparatus. he portion ofthe apparatus shown in Fig. 1 consists mainly of the supply and control apparatus, while that portion shown in Fig. 1 consists mainly of the operating apparatus which in the interests of safety is situated more orl-less remotely from the control apparatus shown in Fig. 1.

Referring to the drawings in detail, 1 indicates the supply or storage tank for containing material to be treated, which tank is connected through a pipe 2 to the inlet end of a force pump 3, the outlet of which pump connects through a pipe 4, three-way cock 5, and inlet pipes 6 and 7 to opposite ends ,of a measuring cylinder 8, This measuring cylinder is provided with a free piston 9 and is so proportioned as to hold a predetermined volume of the oil to be cracked. The lower ends of the measuring cylinder 8 are provided with discharge pipes 10 and 11 which connect througha three-way cock 12 to the still-charging pipe line 13. The three-way cocks 5 and 12 are controlled by suitable levers 14 and 15 respectively, the master lever 14 being connected to the lever 15 by means of a suitable link connection 16 or otherwise so that both levers may be operated simultaneously, the three-way cocks 5 and 12 being so set that the pipe line 13 will cylinder 8 when the pipe 4 is connected with the left-hand side of the cylinder and vice versa. The pipe line 13 connects through a common inlet and. discharge pipe 17 with the retort or cracking tube 18 which is mounted in a suitable furnace 19 provided with a suitable source of heat as indicated at 20. A block'valve 21 is included in the pipe .line 13-between the measuring cylinder 8 and the cracking tube 18, and between this a block valve and the common pipe 17 is connected a check valve 22 set to permit the flow of oil in the direction indicated by the arrow. A pressure gage line 23 connects with the pipe line 13 between the check valve and the cracking tube and extends therefrom to the control station Where t. terminates in a suitable pressure gage 24. A dischargeline 25' connects with the. still 18 through the common inlet and discharge pipe 17 and leads therefrom to a cooling coil or condenser 26 which discharges through a pipe 27 into a receiving tank 28, the receiving tank being provided with a suitable relief valvev such as 29. A block valve 30 is connected in the discharge line 25 1between the cracking coil and cooling coi For the purpose of cleaning out the cracking tube between charges, I provide a novel arrangement which consists of a steam supply pipe 31, connected at the left-hand end of the cracking tube and through which the passage of steam is controlled by the block valve 32. The right-hand end of the tube is adapted to be connected with atmosphere through the pipe 33 containing block valve 34. The block valves 21, 30, 32 and 34 are actuated by pneumatic piston cylinders 35, 36, 37 and 38 respectively, operated by compressed air supplied from a reservoir 39 situated at, the control station. The reservoir 39 is kept charged b a suitable compressor 40 and is connecte through the supply pipe 41 and four- way cocks 42, 43, 44 and 45 to the piston cylinders 35, 36, 37 and 38 respectively, one of the side openings of each of the four-way cocks connecting through pipes 46, 47, 48 and 49 to the bottom ends of the piston cylinders 35, 36, 37 and 38 respectively, and the other side openings leading through pipes 50, 51, and 53 to the upper ends of the piston cylinders 35,

36, 37 and 38 respectively. Theupper openings of the four-way cocks communicate with the atmosphere and the core of each cock is so adjusted that when its leveris thrown into the position indicated in Fig. 1,

the upper end of its associated piston cylinder will be connected with the compressed air supply and the lower end with the atmosphere, the reverse condition obtaining when the lever is thrown to the left. The force pump 3 is arranged .to automatically maintain a constant pressure in the pipe 4 by means of a branch connection 54 connecting the pipe 4 with a diaphragm-valve 55 arranged to be actuated upon the increase of pressure to close the steam supply 56 of the driving end of the pump, and to release upon a decrease of pressure so as to permit steam to .pass to the driving end of the pump] I The operation is as follows:

Heat is applied to the furnace by the burner 20 until the tube 18 has been brought to a temperature somewhat above that required for the contents during cracking,

atmosphere, thus permitting compressed air to enter the piston cylinder 35 from the bottom which raises the piston therein and opens the block valve 21 in the supply pipe 13. The master lever 14 is then swung downwardly which operates the three-way cocks 5 and 12 to connect the pump discharge pipe 4 to the right-hand end of the measuring cylinder. The pressure now being relieved from the pipe 4 and the branch pipe 54, the diaphragm valve 55 is released, permitting steam to flow through the steam supply pipe 56 of the force pump 3 which immediately begins to operate, forcing oil into the right-hand end of the measuring cylinder 8 through pipe 4, three-way cock 5 and inlet pipe 7, which forces the piston 9 over to the left and drives the charge already contained in the cylinder, between the piston and the left-hand end, out through discharge pipe 10, three-way cock 12, supply pipe 13, valves 2l and 22, pipe 17 into the cracking tube 18, lVhen the piston 9 reaches the left-hand end of the measuring tank, the flow of oil from the pump is stopped, thus raising the pressure in the pipes 4 and 54 which again operates the diaphragm valve 55 to shut off the steam supply through 56, thus stopping the force pump. The cracking tube is preferably charged to about onefifth to one-fourth of its capacity, the measuring cylinder 8 being suitably proportioned to obtain this result.

When the pressure in the tube has reached 700 to 800 pounds to the square inch, as will be indicated by the pressure gage 24 at the control station, the lever of thefourway cock 43 is thrown to the left, causing the piston cylinder 36 to operate to open the valve 30, permitting the contents of the crackingtube to be blown out through the pipe 63, discharge pipe 25, cooling coil 26 into receiving tank 28, said tank being closed to atmosphere as shown, for the purpose of maintaining a portionof the discharge pressure therein'and in the cooling coil. The levers'of the four- way cocks 45 and 44 are,

now thrown over to the left, causing their associated piston cylinders 38 and 37 to be operated to open the valves 34 and 32 respectively, which permits superheated steam under pressure to be blown through the pipe .31 into the cracking tube and out by way' of 33 to the atmosphere, which scours 'and cleans the cracking tube of the carbon formed during cracking of the last charge. I have found in practice that where the cooling coil is of sufiicient size and comparatively free of sharp bends, the branch connection 33 to atmosphere and its associated valve control may be done away with as under such conditions the flow of steam will not be unduly restricted or cut down and will pass through the cracking tube swiftly enough to clean it of any deposit that might have formed during the cracking of the last charge.

I haveshown a pyrometer at 60, in Fig. 1, with electrical circuit Wires leading to the indicator dial 61 in Fig. 1. The two dials of the pyrometer and the pressure gage 24 are, of course, located at or near the switchboard containing the various levers of the cocks 42, 43, 44 and 45, and the controlling lever 14. The heat in the retort is supposed to' be maintained constant, at a temperature predetermined for each grade of oil and according to the product desired. Similarly, the pressure is predetermined and regulated by means of the valves 32, 30 and 34. An ordinary stillman can handle the apparatus with ease, Working from a'table of temperatures-and pressures and times of heat, which can be accurately worked out for each product and for each grade of oil desired. 'Where I use the word product, it

is of course to be understood that 'I include in this a more or less expanded range of hydrocarbon series.

While I have described this apparatus as used entirely for cracking in the liquid phase, I contemplate applying it also to cracking in the vapor phase, excluding any liquid from the retort except such as may be incidentally condensed or produced in the cracking operation. For this purpose, I may employ either a supplemental still feeding the pump 3 instead of the oil tank 1, so that the pump would carry and compress vapor only into the retort 18, or I may connect. a still to the pipe 17 or to the upper part of the retort 18, in a position similar to that of the pyrometer 60. With such a branch connection to the pipe 17 or its equivalent, the retort may be employed alternatively with either the oil measuring device or pump, to crack the liquid oil, or to crack vapor received direct from the still. Additionally, and without change in the apparatus, the oil mav be shut off at the valve 21 or both oil and vapors may be shut off (assuming a vapor still to beadded) and oil vapors may be fed through a branch pipe into the pipe 31', so that the oil vapors will be injected into the retort mingled with superheated steam. I do not claim such injection or such mingling as of my own invention, but describethem herein in order to fully illustrate the possibilities of my apparatus.

It goes without saying, that sincethe apparatus is available for either liquid phase or vapor phase cracking, it wouldalso be available for two-phase cracking. In fact to a certain extent, the process hereinbefore described may be calleda two-phase process,

although it is my opinion that the effective work is done in the liquid and not in the vapors, which are mostly made up of very low boiling non-condensable gases serving mainly to keep the pressure, and having once been generated, serving also to prevent a further generation of higher boiling vapors in the benzin series, whereby equilibrium is maintained but cracking goes on actively within the liquid. This is most important because it enables me to produce a very superior product, containing a very low percentage of unsaturated hydrocarbons. For the purpose of maintaining a condition of equilibrium, while controlling the pressure for any temperature, it is only necessary to partially open either valve 30 or 34, and permit the escape of some of the heavier hydrocarbons in the retort 18, which w1ll naturally escape at the bottom, while the lighter non-condensable and permanent gases will remain in the retort until it is discharged, and to some extent even after that. The retention of these gases according to the-laws of chemical equilibrium, serves to prevent the formation of vapors non-condensable at ordinary atmospheric temperatures as already stated.

With respect to the space relation and its effect on cracking in the liquid phase or vapor phase, I may further hazard a theoretical statement, as follows:

If the space relation is properly selected so that the oil will crack at some given pressure, then the fixed and non-condensed gases in this space will hold the heavy hydrocarbons in the liquid state until they crack. After they crack their constituents will vaporize and create more pressure which in turn will tend to preventsecondary cracking. Taking the cracking tube about one quarter full is. simply a commercial convenience as that relation seems to give the best results where the cracking pressure is not allowed to go much above eight hundred pounds. If the tube were filled one half full, just as good results might be obtained but the pressure would go much higher, while if much less than one quarter of the space is filled, the pressure will not build up fast enough to prevent overcracking with production of an excessive amount of fixed gases.

The history of an intermittent charge or batch treated as described is probably as follows:

As the temperature rises the batch of oil is'first vaporized. Possibly some cracking, either in the liquid or vapor phase, accompanies th'e vaporization. The pressure increases and after a time becomes so great that the heavier hydrocarbons are forced back into the liquid phase. The temperature is further increased and cracking proceeds. When 'a heavy molecule is split up into lighter ones, the pressure heretofore great enough to hold it in the liquid phase, will not hold it down any longer so. its constituents vaporize. This process goes on until the batch of oil approaches a state of equilibrium at the temperature and pressure maintained.

It will be apparent, after reading this description that my apparatus may be used without modification for vapor phase cracking, as follows:

After the retort has been scoured, the valves 30 and 34-being closed and the retort heated as described to'a temperature in excess of 600 C. and as high as may be necessary to vaporize the oil in its entirety, oil is admitted gradually and in small quantities to be vaporized and cracked. Special spraying or divided surface heating means may be provided at the inlet to secure complete vaporization if desired. hen a state of equilibrium is reached inthe retort, the pressure and temperature are maintained constant and the valve 30 is opened slightly from time to time to draw off condensable vapors from the bottom of the retort, also drawing off any heavier condensate or tar which may pass into a suitable trap to protect the condenser. If the latter has large pipes and easy bends, however, and particularly if it has drainage means at its lowest point to trap out tars, etc., by gravity, it will not choke. r

The valve 21 is of course manipulated to admit more oil as required, and at the end of a run the valves 21 and 30 are closed and 82 and 34 opened to blow out 'carbon and tar as before described.

For two-phase cracking, the oil is admitted in quantity to one fifth or one fourth ill the retort, and then when equilibrium is reached, more oil is admitted, and cracked oil and vapors are removed, through valves 21 and 30, from time to time, without releasing the no-n-condensable or permanent gases held in the upper part of the retort. For this reduction of gases and pressure my form of horizontal retort is eminently suitable, as shown.

Pipe connection 17' may be omitted if desired a'ndfeed may be had in that case through pipe 63 or the connection 17 may be omitted. p e

Mention has been previously made herein of the use of heat to 600 C. temperature. That is the heat that I use in the furnace, but the temperature of the oil in the tube ranges from 370 to 454 C. while the lighter low boiling oils require 454 C. or more to crack at a commercial speed.

Having thus described'my invention, what I claim and desire to secure by Letters Pat- .ent is: Y 1

ing any desired portion of the charge from the lower part ot the chamber, while retaining the low boiling vapors and permanent gases during the cracking operation during successive intermittent additions of liquid hydrocarbons, discharging at the end of each operation, and maintaining a portion of the pressure upon the product while cooling the same.

v 2. The process of cracking hydrocarbon liquids which consists in first measuring a charge so that each charge will be the same in volume relatively to the cracking area, then feeding the charges intermittently into 15 the lower part of a highly heated chamber,

exposing them therein to heavy pressure each charge from the lower part of the chamber, while retaining the low boiling vapors and permanent gases during the cracking operation during successive intermittent additions of liquid hydrocarbons, dischargingeach charge at the end of its cracking operation, and maintaining a portion of the pressure upon the product While cooling the same.

In testimony whereof I afiix my signature.

FRANK E. WELLMAN.

Images