US1819729A - Apparatus for decomposition and processing of petroleum hydrocarbons - Google Patents

Description

Aug. 18, 1931. J. c. BLAK 1,819,729

APPARATUS FOR DECOMPOSITION AND PROCESSING OF PETROLEUM HYDROCARBONS Filed Aug. 29 1935 INVENTOR.

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ATTORNEY} Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE JOHN C. BLACK, OF DESTREHAN, LOUISIANA, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO GASOLINE PRODUCTS COMPANY, INC., OF WILMINGTON, DELAWARE, A CORPO- RATION OF DELAWARE APPARATUS FOR DECOMPOSITION AND PROCESSING OF PETROLEUM HYDROCARBONS Application filed August 29, 1925. Serial No. 53,334.

My invention relates more particularly to improvements in the decomposition of petro leum oils with the object of reducing the viscosity of the residuum after the distillation and for the production of an increased yield.

of the lighter or lower boiling point hydrocarbons from hydrocarbons possessing these characteristics in lesser degree.

In my previous Patent No. 1,456,419, I describe a process for the production of low boiling point hydrocarbons by using two separately fired heating elements placed in series-the first one of the series is used as apreheater to elevate the temperature of the hydrocarbons passing therethrough to a temperature where decomposition will take place and then passing the heated hydrocarbons through the second coil in the series Where the temperature of the oil is maintained at the decomposition temperature by supplying the oil with the necessary heat of reaction which is the heat absorbed by the hydrocarbons during the decomposition period, then passing the oil to a carbon precipitating chamber and finally to a pressure relief valve to be discharged for subsequent treatment.

The present invention is ,an improvement over the invention disclosed'in the above ,mentioned patent whereby the equipment isof reaction in a heatlng element with an independently controlled heating means whereby the preheated hydrocarbonselevated to the optimum decomposition temperature are supplied with the heat of reactionand maintained at substantially the optimum decomposition temperature above referred to while passing through the reaction element which is so designed as regards volumetric capacity 'due to the lowered temperature 0 that the proper time element will be insured to bring about the maximum decomposition of the hydrocarbons at the temperature employed. This is accomplished by using a larger number of tubular elements in the reaction coil than I have heretofore used in the practical application of my Patent 1,456,- 419 and I am also enabled to eliminate the carbon precipitating chamber employed in the above patent. By using a large number of tubes in the reaction coil I am enabled to extend the reaction time where the hydrocarbons are given a prolonged heat treatment Without diminution of the active supply of heat necessary to obtain the substantially maximum decomposition of the hydrocarbons for the temperature employed.

In this connection I have discovered that by heating the oil to be cracked to a temperature of active decomposition to obtain a yield of, say, 20 percent of low boiling fractions, 4

will require a temperature well above 800 F. if the oil, after passing through a heater is immediately cooled down; whereas if after heating the oil in the above mentioned heater and then passed to a secondary coil or what I denominate my reaction coil wherein heat is supplied to maintain its temperature and supply the endothermic heat of reaction, then the temperature of the oil may be reduced 50 to 100 F. and still obtain a 20 per cent yield of low boiling fraction as illustrated above. It can be readily understood by those familiar with cracking that such a reduction of temperature for a given yield very often means the difference between practical and impractical operation for the reason that at the higher temperature the tubes are more highly heated, causing coking of the tubes and also a shorter life for the tubes and increased the liability of blow-outs with its consequent danger to life and property. Furthermore the plant can be kept on stream at the lower temperature a much longertime without shutdowns for cleaning and repairs, thereby reducing the cost of the products; there is also the advantage of a saving in fuel operation. To accomplish this purpose, I use a combination of fire heaters and heat exchangaction and to maintain or approximately so,

its sensible heat. This secondary heating element or reaction coil is also of tubular form and is of such a volumetric capacity, in relation to the quantity of oil handled in any period of time, that as long a duration of time as is consistent with economy or practicability, be permitted for the passage of the oil or hydrocarbon through the heater whereby the rate of decomposition is not reduced by diminution of temperature and the optimum decomposition or cracking of the hydrocarbons be obtained thereby.

In practice, I use a preliminary fire heater having'steel or alloy steel tubes of three or four inches in diameter and numbering one hundred more or less, connected in series, and the secondary or reaction coil is constructed of similar tubing of approximately the same size and number although, as previously intimated, this coil should be constructed to permit of a long time duration toobtain the optimum decomposition reaction; also to obtain a sutficiently high rate of speed to materially reduce the deposition of carbonaceous material in the tubes.

The relation of these two coils as to num-- ber of tubes may be varied over a wide range, depending upon the oil treated and the decomposition or cracking required. In genderstood that the size of the two sets of coils may be dissimilar within certain limits without material departure from good-results.

In the operation of this process I use a pump capable of developing a pressure suflicient to hold the hydrocarbons substantially in a liquid phase, this pressure is controlled by a pressure regulating valve located between the final heater and the discharge connection depending upon the method of subsequent handling; three methods being shown in the drawing appended hereto.

In my accompanying single figure of drawing, I show the above described features of my invention to ether with auxiliary apparatus to'show t e process complete and clear to any one familiar with the art of refining petroleum hydrocarbons.

I will now describe the drawingof the ap-.

5 into heat exchanger No. 2, then into the heater No. 1, thence into heater No. 2; between the two heaters, Nos. 1 and 2, is a pyrometer 5 and at the outlet of heater No. 2 is a yrometer 6. Leading from the outlet of heater No. 2 is a pipe 7 connecting with the heat exchanger No. 2 from which leads a pipe 8 connecting with a pipe 9 having two ranches, one branch controlled by valves 10 and 43 connecting to the cooler No. 1 and receiving tank 11 and the other branch connecting with the evaporator through the line 12 and valve 13. Leading from the evaporator is a residuum pipe 14 connecting with the heat exchanger No. 1 from which leads pipe 15 to the cooler No. 2 thence to the residuum tank 16. From the evaporator leads a vapor pipe 17 connecting with a fractionating tower 18. From tower 18 leads avapor pipe 19 connecting with a condenser 20 and look box 21 and receiving tank 22. From the tower 18 leads a pipe 23 and cooler 23' connecting with the Wash oil tank 24 to which is connected the pump 25 which in turn discharges through pipe 26 into the top of tower 18. From tank 24 leads an overflow pipe 27 into tank 28 from which leads a ipe 29 into the suction of the pump 30 which discharges through the pipe 31 and valve 31' into the pipe 12 connecting with the evaporator; also \hrough pipe 42 and valve 42' to the supply tank.

Connecting with pipe 12 is a bypass pipe 32 with a valve 33 to permit the oil to bypass the heat exchanger No. 2, valves 34 and 33 being used for this purpose. Connecting with the outlet-pipe of heater No. 2 is a water supply pipe 35 with a control valve 36 used for purging the heaters of oil and dischargin through pipe 37 by means of valve 38 and %lock valve 39. Into pipe 8 is connected a pressure gauge 40 to indicate the pressure at that point and also one lettered 41 in pipe 7 to indicate the pressure at the outlet of the heaters.

I will now describe the operation of the process as depicted in the drawing. The drawing is diagrammatic only but is sufli ciently clear to enable those familiar with refinery equipment to understand it; for instance, the heaters Nos. 1 and 2 are tubular elements set in a brick or other suitable setting and heated by means of a fire box situated Within the setting or forming a part of it. To show the detail of the heater would only confuse the drawing and render it less clear. Likewise, the exchangers shown in diagrammatic form may be of the well known t pes of exchangers used for this purpose an to show more detail would tend to only lessen the clearness of the drawing. Thls would apply also to the evaporator, the fractionating tower and the condensing equipment.

. The pump 1 takes its supply of petroleum from the supply tank 2, developing sufficient pressure to force the oil throughout the oil system and to maintain sufficient pressure on the hydrocarbons to substantially overcome the vapor pressure due to the temperature of the hydrocarbons while-passing through the heaters and exchangers, this pressure being regulated by the valves 10, 13 or 33, depending upon the product desired. In passing through exchanger No.' 1, heat is absorbed from the-hot residuum leaving the evaporator. and in passing through exchanger No. 2 heat is absorbed from the hot oil leaving heater No. 2. These heat exchangers are not essential to the working of the process but are employed from economical considerations and are desirable in the practical operation of the process.

In the supply pipe leading to heater #1 is locateda block valve 44 around which is a bypass connecting with a water or steam separator47 with inlet and outlet valves 45 and 46; the object of this apparatus is to separate any water that might be'in the oil passing to the heaters #land #2; if'the water is in the form of steam it is released through the top that the dehydrating system per'se is shown of the separator to the condenser 49 and released through valve 50 and pipe 51 to the tank 52 or it may be run to waste. If the water is in a liquid condition, it will settleto the bottom of the separator 47 and may be drawn off, through the pipe 53 and valve 54 through pipe 55 connecting with the cooler 56; on the outlet of the cooler 56 is a control valve 57 connectin into the pipe 58 which in turn-connects with the tank 59 or it may be run to waste. The object of the con-. denser 49- and cooler 56 is to condense or cool any hydrocarbons that may pass along with the steam or water. It will be understood only diagrammatically. Thepurpose of this showing is to indicate its operative association to the cracking side of the unit. Since the construction and operation of the system are well known to those skilled in the art no elaborate showing is deemed to be necessary. It will be understood that this sytsem may be provided with suitably positioned pressure and check valves so that when it is cut into the crackin unit the same degree of pressure may be maintained in the dehydrator 47 as obtains in the heated and inletline. The valves 50 and 54 may be pressure reducing valves which serve to maintain a differential pressure on their-respective sides. Pressure reducing valves may be interposed in any "other desired position in the manner well known to those skilled in the art. Similarly a pump may be interposed between the valve 46 and the first series of heating coils.

I have found that by the elimination of water or steam in the cracking reaction that increased yields of decomposition products will result and will also permit of operating at lower temperatures and pressures. If the oil has no appreciable amount of water content, it may be passed directly to the heater Without going through the water separator 47, the valves 45 and 46 being closed and valve 44 open.

The oil now passes to heater #1 where its temperature is further increased to the point of decomposition of the hydrocarbons or at least a portion of them; this temperature is observed by means of the pyrometer 5 this temperature is usually predetermined for each particular oil undergoing treatment. When the desired temperature is reached as indicated by pyrometer 5 the oil is now passed through heater No.2 and is maintained at that temperature or substantially so as indicated by pyrometer 6, and to so maintainthe oil at the maximum point of decomposition in heater No. 2 will require additional heat from an outside source; that is to say the furnace will be required to furnish a quan'ity of heat suflicient to supply the heat rendered latent by the endothermic reaction of decomposition. By this regulated means of heat supply to the hydrocarbons passing through the two heaters, a greater yield of decomposition products is obtained than if the oil had been brought to the point of decomposition and then passed to exchanger No.2 and immediately cooled off, as for instance, if the oil leaving heater No. 1 had gone directt'o the exchanger instead. of to heater No. 2, the sensible heat'attained by'theoil in both cases would be substantially the same but in undergoing decomposition, heat is renderedlatent' and the sensible heat is reduced with attendant reduction of decomposition products and I have found that 'by supplying from an outside source the heat rendered latent and maintaining the sensible heat at its maximum an increased yield of decomposition products will result.

The heated hydrocarbons leaving the heaters pass through exchanger No. 2 where a portion of the heat may be removed, thence through valve 13 and pipe 12 to the cvapo rator. To regulate the heat to the desired amount a bypass may beemployed as shown by pipe 32 and valve 33 whereby any desired amount of hot oil may be added to the cooled oil passing through the exchanger N o. 2.

The hot oil on being discharged into the evaporator will separate into a vaporand a residuum, the vapor passing over into a finetionating tower 18 to he fractionated, the light fractions passing to a condenser and receiving tank; the heavier iractions passing out of tower 18 at the bottom and through a cooler 23 to the wash oil tank 24; a ortion of this oil is recirculated by pump 25 t rough the tower by means of pipe 26 and is used as a condensing medium therein, the increment in the amount of wash oil due to the condensation products overflows from tank 24 through pipe 27 into tank 28 from which it is drawn by pump 30 through pipe 29 and discharged through pipe 31 into the hot oil flowing in pipe 12 into the evaporator; in this way any light fractions absorbed by the wash oil may be re-evaporated and recovered as a.

part of the light fraction going to the condenser, or it may be discharged to the supply tank 2 by means of pipe 42 and 'valve 42'.

The residuum collecting in the lower. por-' tion of the evaporator is discharged through pipe 14 to the exchanger No. 1 from which it passes by pipe 15 to cooler No. 2 and re siduum tank 16. I

By this method of procedure, hydrocarbons may be decomposed, forming new hydrocarbons which could not be obtained by ordinary distillation processes. For instance, I can take a heavy residuum containing practically no low boiling fractions and heat it to a temperature of 700 F. or above and a pressure sufiicient to overcome its vapor pressure and obtain therefrom new hydrocarbons having low boiling fractions of the gasoline series and also obtain a residuum having a low viscosity, and, if so desired, the viscosity of the new residuum may be made lower than the original oil used lif a heavy crude or viscous residuum had been used as the original stock. As an illustrat on, I can take a heavy Mexican crude oil containing four to five percent of gasoline, the residuum from which after the extraction of the gaso-' line would have aviscosity of 2000 at122 F. taken in a Furol viscosimeter and having a gravity of less than 10 Baum, and run it through my heaters and distilling apparatus and obtain a. yield of ten to twelve percent of low boiling hydrocarbons and the residuum will have a viscosity of 300 or less as comparedto the 2000 of the original residuum and the gravity of the new residuum will be 11 Baum or above.

To obtain this result a temperature of 750 F. to 800 F. is used and a pressure at the puinp of 600 or 700 pounds is used. If a high grade residuum is required, the temoerature should not be much above 800 F. but if a larger yield of light products is desired, a temperature as high as 900 F. may be used, but such a temperature will cause too much decomposition of the heavy oils and the residuum would be more or less granular and would not make a suitable fuel oil for the market.

The temperature and pressure must be properly regulated for each class of oil processed and varies according to the class of products desired. If a gas oil distillate were used as the raw stock and if gasoline hydrov carbons were the desired products then a temperature of 750 F. to 950 F. should be used; in this case the pressure should be in excess of 500 ounds although-lower pressures may be used? For cracking "gas oil for instance, I call roduce from-30 to 40 percent of gasoline oiling point hydrocarbons by a once through operation and as high as per cent by re-.

circulating the heavy ends or condensation products from the fractionating tower, in the latter case a somewhat higher temperature is required than if a fresh or uncracked gas oil were used.

To make the handling of the heaters more easy, I install a water supply pipe 35 with control valve 36 and also a blow down line 37 with a valve 38 sothat water may be forced into the heaters to displace the 011 and also coil, a dehydrator in said connection, means in said connection whereby the dehydrator may be by-passed, an evaporator, a transfer line connecting the coil and evaporator, a fractionating tower, means for passing vapor .from said evaporator to said tower, means for removing vapor from the fractionating tower, means for removing condensate from said fractionatin tower, and means for collecting said con ensate, a connection from said collecting means to the transfer line, and a conduit connecting said last named connection with the first mentioned supply tank.

nace, a connection between said tank and the coil, primary and secondary heat exchangers and a dehydrator interposed in said connection, fsa1d heat exchangers being positioned between the supply tank and the dehydrator, means in the connection between the supply tank and'coil whereby said dehydrator may be by-passed, an evaporator, a

n apparatus for cracking oil compris- I ing a supply tank, a crackin coil in a fun transfer line for passing oil from the coil through said secondary heat exchanger to the evaporator in heat exchange relationship with the oil passing to the coil, means for removing unvaporized residue from the evaporator, means for passing said residue through the prima heat exchanger in heat exchange with the 011 passing to the coil, a fraction- JUHN 6. BLACK.

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