US2244636A - Treatment of hydrocarbons - Google Patents

Description

June 3, 1941. H. v ATwELl.

- rTREATMENT 0F HYDROCARBONS FiledApril 2, 1938 Patented June 3, 1941 'raEA'rMENT oF mmnocAnBoNs narnia v. Arwen, white rinus, N. Y., assigner to i Process Management Company, Incorporated, New York, N. Y., a corporation of Delaware Application April 2, 1938, Serial No. 199,560

lClaim.

This invention relates to treatment of hydrocarbon uids to produce low boiling hydrocarbons suitable as motor fuels.

According to this invention an oil, which does not decompose to form substantial quantities of coke or tar and winch can be substantially completely' vaporized, is mixed and burned in a gas enerator with a'limited amount of air, preferably preheated, and the oil undergoes partial combustion. As a result of the partial combustion. the temperature of the oil is raised to a relatively high temperature and the unburned oil is vaporized and cracked to produce a mixture of products containing a relatively large proportion of unsaturated or oleiin hydrocarbon gases, which may be converted into higher boiling hydrocarbons'suitable as motor fuel. This step in the process is carried out in such manner to yield the largest amount of unsaturated hydrocarbons possible. The hot products in the generator also contain. some saturated hydrocarbon gases, products of combustion, hydrogen, nitrogen, etc.

The converted hydrocarbon gases and other gaseous products from the gas generator are passed to a @cking or suitable conversion chamber wherein they are mixed with a heavy oil such as a heavy residual oil or the like and the heavy oil is raised to a conversion temperature and is converted into vapors and gases and coke or a heavy residual cil. During thisl conversion operation due to the relatively high temperatures, additional `quantities of oleflnic or unsat- .urated hydrocarbon gases are produced from the heavy oil being converted by heat derived from the pro'lucts of the gas generator. Using cheap and .dirty oils in the coking or conversion operation I can produce relatively large amounts oi' unsaturated hydrocarbons which can -be further heated and converted into valuable gasoline constituents of high antiknock value.. The unsaturated hydrocarbons formed during the coking operation are added to the unsaturated hydrocarbons formed during the partial combustion of the fuel oil and the combined amounts of unsaturated hydrocarbons are treated later in the process to produce higher boiling hydrocarbons. s

All the gases and vapors from the conversion.

chamber are passed to a fractionating tower wherein a heavy condensate oil anda light condensate oil are separated from lighter vapors and gases. The heavy condensate oil may be used as feed stock for the gas generator or for the conversion chamber or may be further treated in any desired manner. The light condensate oil may be further v,cracked by being passed through a separate conversion coil` and then further treated to separate light hydro- 'carbon oils having the desired boiling range.

The gases and lighter vapors from the fractionating tower are treated in any suitable manner to separate normally gaseous unsaturated and saturated hydrocarbons as the C: to C4 hydrocarbons, which can be liquefied fairly easily. from gases hard to liqueiy such as methane, hydrogen, nitrogen,etc. The gases and vapors may be compressed, cooled and then passed to a separator for separating liqueed constituents containing C2 to C4 hydrocarbons from unliqueed constituents containing methane, hydrogen, nitrogen, etc. Other suitable methods for separation Vmay be used. The liquefied normally gaseous hydrocarbons containing a relatively large proportion of unsaturated hydrocarbons are then passed through a conversion coil wherein they are `heated to a. conversion'ternperature to convert the gaseous constituents into higher boiling'hydrocarbon oils suitable for useas motor fuel. The converted products leaving the conversion coil are preferably cooled and passed to a separator and further treated to separate light normally liquid hydrocarbons,y such as motor fuels, from gases and vapors. Y

The drawing represents a diagrammatic flow sheet of apparatus suitable for carrying out my invention. y i

Referring now to the drawing, the reference character i0/ designates a gas generator which is used to convert fuel oil or the like into gaseous products. Any suitable oil-gas generator which in operation produces relatively large quantities of unsaturated hydrocarbon gases may be used. Oil to be treated in the gas generator I0 is passed through line i2 by pump i4' and is mixed with a limited amount of air or suitable oxygencontaining gas to only partially burn the introduced oil. The air is introduced into the gas generator throughv line I6 by pump IB, and the mixture of oil and air, preferably in atomized form, is passed through line 20 to the bottom portion of the gas generator l0. The air is preferably preheated in anyl suitable manner before being mixed with the oil fed to the gas generator. An ignition opening 22 is provided for igniting the fuel and air inthe gas generator i0.

As above described, an insucient amount of air for complete combustion is mixed with the oil fed to the gas generator so that the oil' undergoes partial combustion andY heat isgendrawn from lthe system through valved outlet erated to vaporize and crack the unburned porline 68.

tion of the oil. During this treatment a rela- The separated liquefied constituents comprise tively large percentage of unsaturated hydronormally gaseous unsaturated 1and saturated hycarbons containing C2 to C4. hydrocarbons is 5 drocarbons containing C: to C4 hydrocarbons produced. The hot gaseous products resulting and are passed through line 'l0 by pump 12 to from the partial combustion of the oil in the gas a conversion zone '|4 wherein they are raised generator together with inert constituents of to a conversion temperature and maintained unthe introduced air are passed through line 24 Y dersuch pressure to produce the desired extent to a coking or conversion chamber 28 wherein l0 of conversion into higher boiling hydrocarbons. they are intimately mixed with a relatively heavyv Generally superatmospherlc pressures are used. high boiling residual oil or the like introduced Instead of passing the gases from separator 56 into the coking chamber 28 through line 30 by to the compressor 62 and separator 66, -they may pump 32. e be passed directly to the conversion zone '|4 but The relatively heavy oil is heated to a conl I prefer to separate the permanent gases from version temperature by mixture with the-hot the rest of the gases before treatment in congaseous products from the gas generator |0 and version zone 14. Other methods of separation the heavy oil is converted into coke and ,gaseous may be used, such as absorption followed by products. During this coking treatment addistripping .the c2 to C4 hydrocarbons from the tional quantitiesA of unsaturated hydrocarbons absorbent. containing C2 to. C4 hydrocarbons are formed. The converted products leaving the conversion `While my invention is particularly applicable zone -'|4 are passed through a cooler 18 orif deto coking relatively'heavyresidual oils, lighter sired are suitably'quenched and then through condensate oils may bel cracked in .the chamber line 80 into a. high pressure separator 82 having 28, the heavy products unvaporized therein being a gas outlet 84 and a valvedlliquld outlet 86. withdrawn in any suitable manner as a liquid. In .the separator 82, gaseous hydrocarbons and AThe relatively large amount of unsaturated xed or permanent gases are separated from hydrocarbons formed in gas generator l0 and liquid and liquefied gases, The liquid whichcoklng chamber 28 are further treated as will contains gasoline constituents is withdrawn from be described hereinafter to produce valuable V30 the separator 82 through line 88 and may be furmotor fuels- While I have Shown Only one ookther treated as desired .to produce a suitable lng or conversion chamber in the drawinenlt Will motor fuel having the desired boiling range.l The be understood that .a plurality 0f cokine Cham- A separated gases are passed through une e4 to bers may be used so that onemay be cleaned a high pressure fractionating tower 90 to sepaout while another is in use. The coking chamber rate C, to C4 hydrocarbons `from xed or peris provided with a manway 34 for the removal 0 manent gases such as methane and hydrogen coke or residual oil. which are withdrawn through valved line 82. The hOt VapOrS and, gases from the coking The Cz to C4 hydrocarbons are suitable for rechamber 28 preferably after suitable cooling t0 processing and are withdrawn from the bottom a temperature belOW erking are passed through of the fractionating tower 80 and are forced line 36 to the lower portion of a fractionating through line 94 by pump 96 and is preferably tower 38 wherein a rela-tively heavy condensate recycled so .the conversion zone 14. for further oil and a relatively light condensate oil are septreatment, rated from 88868 8nd VBDOIS Which P885 Over' The light condensate oil which collects on the heady from the fraetiOnatinS tower 38. 'The 45 trapout tray 42 in the fractionating tower 38 is heavy condensate oi-l is withdrawn through .line preferably treated to produ lower bolllng hy- 40 and may be burned in generator |0 or may drocarbons and the description of this treatment be treated in any desired manner to produce will now be given. The light condensate oil is additional cracking stock or other productspassed through conversion zone 48 wherein it is 'I'lie light condensate oil collects on trap out 50 subjected to a relatively high temperature and tray 42 provided with a hood 44 in the fraction-f maintained under superatmospheric pressure to ating tower 38. The light condensate oiliswitheiiect the desired extent of conversion. The

drawn from trap out tray 42 and preferably is converted products leave the conversion zone passed through line 48 and conversion coil 48 through line |02 having a pressure reducing by pump 50, wherein it is subjected to relatively` valve |04. A line |05 is preferably used through high temperature and-pressure conditions to vefwhich a quenchoil may be introduced into the feet the desired extent of conversion as will be conversion products leaving the conversion zone later described in greater detail. 48. Y The vapors and gases which pass' fromthe The converted products are-then passed to a top of fractionating -tower .38 are passed through 6o separating or evaporator zone |08 wherein liquid line 52 and condenser 54 and then .to o, sepa,- residue is separated from vapors, the liquid resirator 58 for separating liquid gasoline constitdue being withdrawn through line |08. The liquents from normally gaseus hydrocarbons' hyuid residue may be used ,as charging stock for drogen and nitrogem The separatoris provided the conversion chamber 28. The vapors pass with a. veivea liquid outlet 5s for withdrawing 65 Overhead through line H0 t0 o fractionatins liquid constituents ,The gases leave the wp of l tower ||2 which may be of bubble tower conthe separator 56 through une su are compressed .struction wherein theyare fractionated to sepby a suitable compressor 62 and after suitable 'amate colfirnsa ou nomi lighter hydmrbon cooling m cooler 64 are mtmduced um) a Sepa vapors. e condensate od is withdrawn from the bottom of the fractionating tower -||2 and rator 88, which may be a fractlonating column, passed through une I" b um "s d is for separating liquefied constituents from uny p p an preferably recycled through the conversion zone liquefied constituents. The unliqueed @Onstiii- 48 for further conversion thereof. The vapors uents contain .so-called permanent gases as niremaining after fraction-ation leave the top of trocen, hydrogen. methaneetc.. which are withthe fractionating tower` H2 through line |20 and are condsensed by being passed .through condenser |22, and then passed to a separator |24 wherein gases-.are separated from liquid. The liquid which contains hydrocarbon constituents suitable for use as a motor fuel is withdrawn through line |26. Thegases leaving the top of the separator |24 may be passed togas storage but are preferably passed through line |28 by pump |30 to line 60 for compression with the other gases prior to fractionation in separator 68 wherein hydrogen, methane and other diluents are separated prior to the Vconversion of the higher molecular Weight gases.

A typical operation contemplated by my invention will now be given but it is to be understood that it is by way of example only and various changes and modifications maybe made in the practice of my invention. The operating conditions may change,.if necessary, when different oil stocks are used. vThe generator I is preheated to a temperature of about 1000 F. in any suit- ,able manner before starting the operation of generating gas. An oil which can be vaporized without substantial decomposition to'ake or tar and which has a gravity of about 30 to 33 A. P.I. is mixed with an insuilicient amount of air to support complete combustion and the mixture is atomized and introduced into the preheated gas generator I0 wherein partial combustion of the oil takes place to produce hot gaseous products containing products of combustion, unsaturated hydrocarbon constituents, saturated hydrocarbon constituents, hydrogen, nitrogen, etc. The air is preferably preheated in any suitable manner to about 700 F. While I prefer to use an oil as described above, in some instances heavier oils may be used, relatively heavy distillates may be used, or a distillate stock may be used which is too refractory for cracking to gasoline. The gaseous products from the gas generator contain about 16% by volume of unsaturated hydrocarbons but with diluents such as hydrogen, methane and nitrogen removed from the gaseous products, the percentage by volume of the unsaturated hydrocarbons then becomes about 50%.

The products leaving the gas generator |0 after the partial combustion are at a temperature of about 1350 to 1575 F. depending on the ratio of air to oil, preferably about 1350 F., and they are introduced into the coking or conversion chamber 28 wherein they contact relatively heavy residual oil, preferably preheated, introduced into the coking chamber through line 30. The coking chamber is also preferably preheated to a coking temperature for the heavy oil when the operation is started. The heavy oil which is charged to the coking chamber may be a dirty residual oil. l. am able to use cheap and dirty residual oils for the reason that the coking Athereof is done in a separate chamber without interrupting the operation of the process.

Due to the high temperature of the products introduced into the coking chamber 28, the heavy oil is heated to a cracking temperature and cracked to produce gases and vapors and coke. the coke collecting in the coking chamber 28. The coking chamber is preferably maintained under atmospheric pressure or slightly greater than atmospheric pressure up to about 60 pounds per square inch. AThe heavy oil undergoing cracking in the coking chamber is maintained at a temperature of about 830 to 975 F. During the coking -operation additional quantities of unsaturated hydrocarbons are formed in the coking chamber to increase the total unsaturated hydrocarbons in the products of conversion.

The vapors and gases leaving the coking chamber 28 are passed to the fractionating tower v38 to separate heavy condensate oil and light-con densate oil from gases and vaporsy which pass overhead from the fractionating tower 38. These gases and vapors contain the so.ca11,ed permanent gases and also. unsaturatedy hydrocarbonv gases formedin the partial combustionk ofthe fuel oil in the gas generator and also during the coking f of the heavy oil in the coking chamber 28. These last-mentioned gases and vapors are treated in any suitable manner to separate the so-called permanent gases such as hydrogen, nitrogen. methane, etc., from the normally gaseous hydrocarbon constituents. The normally gaseous constituents containing unsaturated and saturated hydrocarbons including Cz to C4 hydrocarbons are then passed through the conversion zone 14 wherein they are maintained under suitable temperature and pressure conditions with or without the aid of catalyst to produce the desired conversion thereof into higher boiling liquid hydrocarbons including gasoline constituents.

For example, the normally gaseous hydrocarbons including the unsaturated and saturated hydrocarbons may be heated to a temperature of about 750 to 1300 F. while under a pressure of about 400 to 3000 pounds per square inch to effect polymerization of the normally gaseous hydrocarbons into normally liquid hydrocarbons. Where a predominantly aromatic liquid product is desired, higher temperatures, lower pressures and a shorter time of reaction may be used, as

"for example, a temperature of about 12001750 F., and a pressure from atmospheric to about 200 pounds per square inch. Lower temperatures of from 200 to 60'0" F. and pressures of from 200 to 1000 pounds per square inch may be employed when catalysts are used.

During the treatment in the conversion zone 14, the normally gaseous hydrocarbons are converted into higher boiling normally liquid hydrocarbons and the converted products are passed to the separator 82 to` separate a liquid fraction containing gasoline constituents from gaseous constituents.

The light condensate oil withdrawn from the trapout tray 42 and passed through the conversion zone 48 is raised to a temperature of about 925 to 1100 F. and maintained under a super- Iatmospheric pressure of about 200 to 1000 pounds per square inch while it is being passed therethrough. The conversion products are passed to the separator |06 under lower pressure and the vapors separated4 therein are further fractionated in the fractionating tower ||2 to separate lower boiling hydrocarbons which are withdrawn through line |216.

VWhile I have given an example for practicing my invention, it is to be understood that this is by way of 'illustration only and various changes l,and modifications may be made where different stocks or different operating conditions are used zlvithout departing from the spirit of my inveny ion.

I claim:

A process for treating hydrocarbons .that comprises mixing a condensate oil with less than the total amount of oxygen-containing gas necessary for complete combustion so that the odl undergoes vaporization and partial combustion with conversion into lower boiling hydrocarbons containing unsaturated hydrocarbons, ln-

troducing a residual charging stock into a singlepass cracking zone, directing the resultant hot products formed by .the partial combustion of 2,244,ese

resultant cracked products from the recycling cracking aone into residue and vapors and gases,

the condensate oil into said single-'pass' cracking zone in contact with the residual chargingv stock to thereby maintain it atacoking temperature and effect conversion into a coke residue-A' and vapors andv gases comprisingadditionaily formed unsaturated hydrocarbons, fractionating said vapors and gases to form fractions comprising light distillate, higher boiling reflux con-'1 densate and Va normally gaseous fraction' including unsaturated hydrocarbons, passing said reflux condensate to a recycling cracking-zone wherein it is subjected to cracking conditions of temperature and pressure to effect conversion into lower boiling hydrocarbonsv including additionally formed unsaturated hydrocarbons, separatlnglthe' fractionating the latter vapors and gases to form fractions comprising light distillate, higher boiling reflux condensate and a normally gaseous fraction including unsaturated hydrocarbons, directing the latter reux condensate to said recycling cracking zone. combining said normally gaseous fractions and directing the mixture to a conversion zone wherein it is subjected to conversion conditions of temperature and pressure to eiect conversion into higher boiling normally liquid hydrocarbons, 'fractionating the resultant products of conversion to separate out a fraction comprising unconverted normally gaseous hydrocarbons and directing the `latter fraction to said conversion zone. HAROLD V. ATWELL.

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