US1859028A - Method of treating petroleum hydrocarbons in the vapor phase - Google Patents

Description

R. CROSS May 17, 1932.

METHOD OF TREATING PETROLEUM HYDROCAR BON S IN THE VAPOR PHASE Filed Nov. 8, 1927 INVENTOR HT Ra Cross BY W I J HWH. J MMQNQAQ .N N N WM w, h @N an M W w E ATT NEY 6 kaline and lithium,

Patented May 17, 1932 PATENT, OFFICE ROY cause, or. KANSAS crrr,

HISSOUBI, ASSIGNOR TO CROSS DEVELOPMENT COR-PORA T1011, WILMINGTON, DELAWARE, A CORPORATION 01: DELAWARE IETHOD 0F TREATING PETROLEUH HYDBOCARBONS IN THE VAPOR PHASE Application filed November 8, 1927. Serial no. 251395.

This invention relates to improvements in a process for treating hydrocarbons in a vapor phase, and refers more particularly to the treatment of hydrocarbon vapors by alearth metals such as sodium, potascalcium, magnesium, strontium, barium I the treatment being carried on at a predetermined temperature, that is, the temperature of the treating substance is regsium,

l ulated as well as the temperature of the vajected to vaporous hydrocarbons pors undergoing treatment to produce optimum conditions for the removal of objectionable materials such as sulphur compounds from the vapor.

The invention is a continuation in part of an application, Serial No. 142,016, filed Oc-- tober 16, 1926.

Among the salient objects of the invention are to provide a process in which oil is subcracking conditions of temperature and pressure in a cracking process and the vapors distilled off from the' cracked products, fractionated, and during the fractionation thereof or just subsequent thereto the are passed through a treating stage where they are brought into intimate contact in counterflow relation with an alkaline earth or alkali metal or a combination of alkaline earth metal heated to a temperature above its melting point and at an optimum temperature to produce the most efiicient and thorough purification of the hydrocarbon vapors undergoing treatment; to provide a process in which the temperature of the treating material is accurately controlled by mechanical or electrical therinostatic arrangement adapted to maintain the temperature of the treating materials within a relatively accurate range of temperatures; to provide a process in which the treating materials are continuously circulated in counterflow relationwith the vapors, additional treating material being added as the liquid becomes spent or exhausted; to provide a process from whichpolymerized products are withdrawn from the treating stage and returned to be re-distilled in a hotter zone of the system while certain of the reaction products are diverted. from the system; and in general to provide a process and apparatus hereinafter described.

The single figure is a diagrammatic side elevational view of an apparatus in which the process may be practiced, with parts in section and parts broken away.

Referring to the drawing, at 1 is shown a furnace consisting of a combustion compartment 3. In the latter compartment is positioned a heating coil 4 having a supply line 5 and a discharge line 6 communicating with a reaction chamber 7. The reaction chamber is preferably formed of a sin le ingot of forged steel, for 'ed on a man rel to size and having remova le end plates to facilitate cleaning. The forged chamber is heavily insulated to prevent loss of heat by radiation. A transfer line 8, in which is interposed a reducing valve 9, connects the chamber with an evaporator10. The evaporator has an overhead vapor line 11 'communicating with the lower portion of a dephlegmating tower 12 which is preferably of the bubble type. A draw-01f line 13 is connected into the bottom of the evaporator and is controlled by a valve 14 controlled by .a liquid level regulating device,-'diagrammatically shown at 15. A similar mechanism controls the valve 16 interposed in the draw-off pipe 17 connected into the bottom of the dephlegmating tower 12. The discharge line 13 terminates in a cooling coil positioned in the cooler 18, the discharge from the cooler being controlled by a valve 19. The discharge from the refluxing tower has connection with the tank 20, a pipe 21 leading from the tank to the suction side of the pump 22 whose discharge line 23 has connection with the supply line 5 to the heating coil.

The vapor-line 24 connected intothe top of the dephlegmator 12 serves to discharge the vapors passing off from the top of the dephlegmator into the lowerportion of the treating tower 25. This treating tower is also of the bubble type construction in which a series of pools are maintained by overflow standpipes and capped vapor risers which serve to cause the vapors passing upwardly through the tower to percolate through the pools of liquid. The top of the treating tower has a vapor connection 26 with the coil 27 in the condenser 28, the discharge end of the coil 27 terminating in a line 29 connected into the gas separator 30. This gas separator has a gas line 31 controlled by a valve 32 and a liquid draw off line 33 regulated by a valve 34. i

For the circulation of the treating material a draw off line 35 is connected into the bottom of the treating tower 25. Through this line and connections the treating material is directed to a tank 35a from which the treating material is withdrawn by the pump 36 and returned to the tower through the pipe 37. A secondary line 38, controlled by a valve 39, connected into the pipe 35, serves as a means for supplying fresh treating material to the system as the material circulated through the tower becomes exhausted or spent.

There is also arranged on the side of the tower and adjacent the lower liquid pool, a sight, or liquid gauge glass 40, in order that the level of the) liquid can be seen.

A draw ofl' line 41, controlled by a valve 42, is connected into the bottom of a treating tower in the form of a standpipe 42a. This standpipe arrangement is for the purpose of drawing ofi reaction products from the surface of the treating material. A second standpipe 43 in the bottom of the treating tower, has a continuation in the form of a draw off line 44, which is connected to the suction side of the pump 45. By means of this pump polymers withdrawn from the top of the liquid body in the treating tower are pumped through the pipe 46 and discharged into the bottom of the evaporator 10, where they are redistilled and the unvaporized material drawn off with the heavy bottom through the line 13.

In operation the oil is supplied fromany convenient source through the pipe 47 and pump 48, and pass through the line 49 and a coil 50 positioned in the top of the tower 12, where it is subjected to the heat of the vapors in the tower. After being preheated in this manner it is directed to the line'51, which communicates with the supply line 5, and is circulated thence through the heating coils of the furnace 1. 'In the furnace it is raised to a cracking temperature and in this condition is passed to the reaction chamber where the cracking reaction instituted in the coils is completed. The temperature and pressure maintained upon the coils and reaction chamber will vary according to the oil undergoing treatment. Normally temperatures ranging from 650 F. to 1000 F., and pressures from 500 pounds to 1000 pounds per square inch are usual. The oil on being discharged from the reaction chamber is introduced at reduced pressure into the evaporator 10. The reduction of pressure, together with the contained heat of the oil, distills oil the lighter fractions which pass overhead through the line 11 to the dephlegmating tower 12. The bottom from the evaporator is diverted from the system after being cooled in the cooler 18.

V In the dephlegmating tower the vapors are subjected to a refluxing action, the unvaporized material automatically withdrawn and recycled for retreatment by means of the pump 22, while the vapors discharged from the top of the bubble tower are introduced into the lower portion of the treating tower. In the treating tower the vapors rise and are percolated through a plurality of pools of treating liquid, thereby being brought in intimate contact with the liquid treating material. This treating material is introduced to the system at a temperature sufliciently high to maintain it in liquid state through the pipe 38.

A bypass line 55, between the vapor pipes 24 and 26, serves to cut out the tower from the system when desirable, the vapors then passing directly from the tower 12 to the condenser 28. Valves 53, 54 and54a govern the use of the bypass line 55.

Connected into the upper portion of the tower 12 is a pipe 56 controlled by a valve 59, by means of which materials may be added to the refluxing tower. In bringing the system on stream, normally the treating tower is cut out until the apparatus has been brought to temperature and during this period a considerable quantity of distillate will have been produced. This distillate is returned and introduced into the refluxing stage, through the pipe 56, when the treating tower 25 is cut in order that the products will all be uniform in character.

Returning to the method of treating, when sufficient treating material has been introduced to the system the valve 39 in the line 38 is closed. pipe 61 to thetank 35a which is insulated and heated by a steam coil 62.

As suggested, the heated liquid treating material is picked up by the pump 36 and forced throughthe line 37 into the treating tower at a point sufficiently high thereon to permit the accumulation of the material on a plurality of trays but at the same time leaving a fractionatin zone beyond the treating stage.. It may be esirable to have the treating stage and final fractionating stage in separate towers.

In the event it is necessary to isolate-the tank 35a from the system for cleaningpurposes or otherwise, the valve in the line 61 and the valve 63 in the line between the tank 35a and the pump 36 are closed and the treating material diverted directly from the draw oil line 35 through the pipe 59 to the suction of the pump 36.

The tank 35a is equipped with a draw off line 64, controlled by a valve 65. The equipment including the The material is directed through tank and the tower 25,

which is circulated from the tank a by means of the pump 36 through the line 37 and through the treating tower 25 is controlled by a pyrometer 66 interposed in the line 37 near the tower 25. This pyrometer is set at a predetermined temperature which is the temperatureat which it is desired to maintain the treating material. The temperature chosenis that temperature at whichOthe vapors of a certain hydrocarbon which is un-' dergoing treatment in the tower 25 will be treated most efliciently. In other words, the temperature of the different hydrocarbons will vary according to the optimum temperatures of treatment: The 'pyrolneter through electric connections designated as 67 controls a'valve 68 interposed in the steam ipe sup plying the coil 62 in the tank 35a. y regulating the amount of steam introduced to the coil the temperature of the liquid body in the tank 35a is accurately control ed and thus the temperature of the liquid introduced to the tower 25 is maintained within a narrow .range by the functioning of the mechanism controlled'by the pyrometer 66. The character and quality of the oil, the amount of sulphur contained in the oil and the amount of sulphur to be removed as well as the particular quality of distillate to be recovered will all constitute factors necessary to be considered'in arriving at the temperature of the treating material.- Vapors of a mid-continent oil-of 54 Baum gravity were treated under satisfactory operating conditions when the temperature of the treating material was maintained at 450 or thereabouts.

It is understood that the temperature selected is that which is the best used withthe oil undergoing treating and the ,type of processing which is being carried on. It is the control of the temperature of the treating material to provide optimum conditions for treatment. which is the novelty of the present invention rather than any particular range of temperatures when using difi'erent types of oil. I

Another factor of importance in connection with the treatment herein is that the oil is immediately treated before it is permitted to cool or set after it has passed through the cracking or distillation system. Radically difieren't results are oftentimes obtained when the distillate has been allowed to cool or stand and the polymers separated-out from the liquid body. In other words, a distillate grecove iiy from a crackin the polymers which is permitted to get old or age to any extent whatsoever reacts differently than a used as typical, although it is understood a that either of the other alkali or alkaline earth metals or mixtures thereof can be as I well employed.

As previously suggested, the sight lass 40 is used for determining; the liquid evel in the-bottom of the tower. From time to time withdrawn through the line41 and diverted from the system or recycled to the evaporator for redistillation. Y

The treated'vapor passing off from the top of the tower is subjected to a final condensing or reaction products may be action and collected in the gas separator from which the treated liquid is withdrawn through the valve 34, and the gaseous material'through the valve 32.

In actual practice hydrocarbon vapors treated with metallic sodium, or other alkaline earth metals have been effectively puri fied to produce a water white sweet hydrocarbon distillate. The alkali metals particularly sodium, have an aflinity for the sulphur compounds in the oil, and efiectively rcmove these compounds with a very low perceptage of loss of the volume of the treated 01 Actual tests in which cracked distillates from the mid-continent and Californian fields, in which the oils were vaporized and the vapors passed through successive pools of liquid sodium, produced a clear water "white product which did not discolor on standing and passed both the doctor and copper corrosion tests.

- As to sulphur removal, the alkali metals, such as potassium and sodium, are very active, though magnesium and calcium are more effective quantitativel In soine'instances it is desirableto use .t e combination of the metals in place of a single 'metal, the peculiar characteristics of the oils being treated more or lessdetermining the metals most advantageously'used as an efiective, purifier.

As suggested, the losses with this type of treatment are much less than those resulting from the usual methods of refining, particularly the acid and caustic treatment which is common .to most refiners.

4 mucosa straight distillation cracking or rerunning equipment.

The ipes pump and apparatus through which t e treating material is circulated are heavily insulated to prevent heat by radiation and to prevent any considerable variation of the temperature of the treating material during its travel throu h the circuit from the tank to. and through t e treating tower 1 and back to the tank.

I claim as m invention: 1. A metho of treating troleum hydrocarbons, comprising intro1 cing vapors of cracked hydrocarbons into a treating tower, l "introducin liquid metallic sodium into said tower to ow countercurrent to the Va ors, separating the metalfrom the hydrocarn, heating t e metal to an optimum temperature for treating the hydrocarbon vapor and recirculating it in contact with the hydro carbon vapors.

2. A process for treating hydrocarbon vapors consisting in the steps of establishing a cyclic flow of metallic sodium in liquid form including a heating stage in the 0 do to maintain the temperature of the 'um at an optimum. temperature for treating the vapors, passing the hydrocarbon vapors in contact with the liquid sodium, said contact effected by counterflowi the vapors with the liquid sodium in a stage included in the cycle.

ROY CROSS.

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