US1616515A - Cracking liquid hydrocarbons - Google Patents

Description

b 8 H. o. swoBoDA SET AL CRCKING LIQUID. HYDROC'RB'ONS Filed 'July 6, 1922 4 'Sheets-Sheet f2 INVENTOR Feb 8h,

H. O. SWOB-ODA ET AL CRACKING LYIQUID HYDROCARBONS Filed July 6, 1922 4 Sheets-Sheet 4 gNvENron Patented Feb. l8, 1927. A

UNITED STATES x i 1,616,515 PATENT oFFICE.

HANS o. sWoBoDA4v AND EARL M. RICHARDS; or PITTSBURGH, PENNSYLVANIA, AssIeNoRs To H. o. sWoBoDA, INC., or PITTSBURGH, PENNSYLVANIA, A CoRPoRA- TION 0F PENNSYLVANIA.

cRAcKINe LIQUID HYDRoARBo'Ns.

Application led July 6, 1922. Serial No. 573,080.

Figure. 1 is a diagrammatic sectional side elevation showing one form of Yapparatus for carrying out ourinvention; and

' Figures 2 to 4 are diagrammatic views showing other forms of our apparatus.

Our'invention relates to the-cracking of hydrocarbons into hydrocarbons having a lower boiling point, and is designed to'provide a new andimprovedl apparatus and method therefor.

In a long series of experiments, we have found that in a cracking system where oil is continuously fed through a pipe or conduit and vaporized and cracked throughits passage, the percentage of lower. boiling point product produced in the higher percentages of yield depends quite largely on the temperature, particularly that in the hottest portion of the tube or conduit. Small variations in temperature in the cracking zone proper, as wellpas in the conduit leading to the cracking zone, are found to produce large variations in yield.

In carrying out our invention, we' ,preferably utilize the metallic tube or "conduit itself as an electric resistance and by supplying electric heat to a Zone portion or portions of the. tube, We are enabled to regulate the temperature thereof accurately and force in heat quickly after cracking begins, and thus obtain large yields. i

Our invention also relates to recovering a portion of the heat of the cracked vapors and returning this heat to the heating zones of the conduit, thus greatly reducing the amount of heat energy supplied and greatly improving the economyA of the system. It

also relates toa system of. automatic temperature regulation hereinafter described.

We have also foundthat by dropping the oil to be cracked into a steam current passing tln'ough the cracking tube or conduit and insuring aconsider'able velocity of-the steam. the carbon which -is freed in cracking will be swept through and out of the crack-- ing conduit, thus avoiding its being clogged up. So far as we can determi-ne, the steam pci-forms the mechanical lfunction of sweeping out this freed carbon When the steam is maintained under suilicient velocity.

' In Figure 1 of the drawings, we show one .'form of apparatus'for carrying out our iii-- vention. In this form. 2 is the receptacle for untreated oil which is pumped into the "the converter through oil-preheating pipe 4 by a pump 3 .provided with a governor. he pump is shown as driven by a motor 6 andl the amount of oilpumped is indicated'by a flow meter 7 connected to the-pipe leading to the pump. A pressure gage is preferably connected to the oil-preheating p-ipe 4 to indicate the pressure of oil inthe preheater. 8 is a thermocouple arranged to measure the temperature of the untreated oil leaving the oil preheatcr, and

9 is an automatically controlled valve which.'4 regulates the flow of the heat transfer medium to the jacket space around the oil preheater 4 to maintain constant the temperature indicated by the thermocouple- 8. The valve 9 is operated by motor 10, Which'is electrically connected to the control board 11 to which the thermocouple 8 is also connected to vgive automatic control. Such an autoinatic valve control system is available in the open market. From the oil preheater 4, the'preheated oil flows through pipe or duct 12 into the converterpipe 26, entering this pipe beyond the point Where steam is introduced into the converter through a duct 13.

' 14 is a water tank containing the water which is to be passed into the converter to mix with the oil, the Water from reservoir 14 being pumped by a pump 15 into boiler 16. The pump 15 is driven by motor 17,

and 18 is a pressure gage on the boiler to show the pressure of the steam in the boiler.

is circulated around the feed pipe-a portionv of the heat transfer mediunriiovving vfrom Y 'l ipe 25 to the i e 59 and pump 60. p

The converter has an inner tube 26, to lconvey the oil and Water introduced from the oil preheater and the boiler 16, and this converter tube leads to a catalyzer tube 27. Jacket tubes 28 and 29 surround the converter tube 26 to convey the vheat transfer medium which passes from the upper end of the jacket space Within pipe 28 through a bypass or detlecting device 31,which leads the heat transfer medium to the lower part of the jacket tube 29. This detlecting or vbypass device is `heated by a. differential te1n mocouple 36, located in the adjacent portionv of the'tube 26 below the battle or partition separating the jacket spaces.

The catalyzer or cracking tube 27, which may be provided with any of the ordinary catalytic material, such as molybdenum, vanadium, etc., or may be without any such -material, is provided with electrical taps 38 and 39, connected to transformer 40, with tap-ofi'l changer 41, through which electrical energy is supplied to the catalyzer tube. This portion of the conduit is preferably electrically insulated from the jacket tubes of the converter and condenser by insulating joints 42 and 43. The entire cracking conduit, including the oil preheater, converter, catalyzer or cracking tube and condenser,

is preferably formed of one continuous pipe' or tube which is mechanically and electrically continuous. A thermocouple 44,

.located in the catalyzer tube, in cooperation with other instrumentalities regulates the temperature of the vaporsv passing therethrough. A sample pipe 45 of small diameter also connects the catalyzer tube to sample equipment 46, which may contain a coil of pipe in a tank containing a cooling medium with a tap-off, as shown.

The condenser comprises a tube 50, forming a continuation of the catalyzer tube, and Iis surrounded by a jacket tube 51, the heat transfer medium being carried in the. jacket space thus formed. The tube 50 has ya tar trap 86, located in its intermediate portion to receive tar and similarly condensed heavy hydrocarbons, and the jacket space around tube. 50 has an outlet tube 52, connected to the jacket space of tube 28 of the converter through pipe 58. 53 is a differential temperature and heating burner receiving gas 'through pipe 54, from gas tank 20, the gas supply being automatically controlled by motor-operated valve 55, actuated by thermocouple 56 in the converter tube just short of the catalyzer tube. A motor 57 operates valve 55. The -heat transfer medium delivered through pipe v58 to the jacket space around. the converter tube is Withdrawn from the jacket around the oil preheater;

l through tube 59 by a pump 60, driven by a motor 61. This pump is provided with a pressure gage 62, and with a safety valve A with valve 69 is shown as arranged to feed gas into the gas tank from other sources of gas sup-ply, if needed.

From the tank 66 the treated oil may pass through pipe 71 to evaporator 70 having a heater '72 supplied 'by gas drawn from gas tank 20 through pipe 73. This pipe may have the automatically controlled motoroperated valve74, driven by motor 75, controlled from the control board 11 and actuated by thermocouple 76 inserted in the upper part of the evaporator 70. From the evaporator, the vapors pass through pipe 78 to a condensing tank 77.

On the control board are preferablyy mounted .meters 79 to indicate the volts,

amperes and Watts used by thev electric material as shown.

In starting the operation, the valve v69 is opened to admit gas from 'an external Source to the gas tank and its interconnected pipes. The proper switch of group 84 on the control board is then thrownin to start motor 17. Whichthereupon drives the pump 15 to deliver Water from the Water tank into the boiler. The valve 19 is then opened and the burner 22 lighted and another switch of group 84 on the board is thrown in to start motor 23 into operation. Steam is thus developed, the pressure of Which is shown on the pressure gage 18. W'hen a predetermined 4pressure is developed by this steam, the gage hand operates a contact mechanism which, inturn. operates a relay of group 83,. on the switch board which causes the motor 23 to reduce the supply of gas through the valve 19. thus producing a drop yin pressure, lVhen the pressure drops a small amount, the gage hand operates anotherl contact. causing the motor 23 to admit an increasedflow of gas. In this Wajby, means of these the valve 19 will vary the gas How and automatically maintain the steam pressure inthe boiler 16 substantially constant.

Distilled water is then admitted to the differential temperature and starting heater 52 and/the valve 55 is opened to permit flow `of gas from the gas tank to the burner 53 which is lighted'. At the same time, a swift/ch of group 84 is thrown in on the control board to start motor T into operation. By means of a relay of group 83 on the conftrol board and the corresponding pyrometer of group 82,- the motor will cause the valve. 55 to vary the gas flow according to the temperature registration of the thermocouple 56. The heat transfer medium being converted into steam Hows up through the tube 58, into the jacket space of the converter, thence through the check valve 32 and the differential temperature andstartlng heater 31. At this time, a switch of group 84 is operated on the board to start the gas heater 33. The gas to this heater is automatically regulatec from thermocouple ThI .other motors are correspondingly controlled by pyrometers, relays and switchesy'l The steam passing through the heater V431 conveys4 additional `heat to the converter and burners53 and 33 function as starting heaters to supply heat to the heat transfer medium until such time Cil as this medium-will receive most of its heat from the operation of the apparatus. The jacket steam flows to the upper end of the converter and thence passes .down the restricted pipe 25 and also u through valve 9 into the jacket space of tie oil preheater. Another switch should then be thrown jin to control valve 9 through its motor, pyrometer, relay and switch so that the heat transfermedium flowing through valve 9 will maintain a predetermined temperature at the thermocouple 8.v From the jacket space of the oil preheater, the heat transfer medium flows into pipe 59 .and at this point the steam acting as a heat transfer medium has been condensed into water, and in this form is delivered by pump 6() to the tube 51 of the condenser, lwhence it passes to the `heater 52and the cycle is then repeated.

mined temperature, as regulated by valve 9 through the action of thermocouple 8. This preheated oil ows through duct 12 into the cog-.verter tube 26, where 'it drops into the under the desired velocity, will carry out the carbon formed. The temperature of the oil and steam is preferably about 350 to 45001?. The mixtureof steam and oil vapor yis then progressively heated as it passes through the converter tube 26 by t-he heated steam flowing in thc counter direction in the jacket. The rate of progressive heating or raising of the temperature, however, is reduced after the mixture lof, oil and steam enters the lower portion of the converter tube surrounded by the jacket tube 23; since al lower rate of heat increase in this portion of the converter has here been found byexperiment to produce' the most satisfactory results in cracking.l Hence, more heat per unit area should be delivered into the portion of the converter tube surrounded by jacket tube 29, as comparedwith that surrounded by jacket tube 28. This is effected' by the differential temperature land starting heater 31 and the quantity of heat thus added is automatically controlledl by the thermocouple valve 34, motor 35,'pyrometer on the control board, and relay=on the control board.

to preferably from 1000.F. to 1100io F. by

the tap changer 41. A smaller' portion of the lUl) cracked oil vapor passes down through pipe 45 to coil 47 and is cooled land withdrawn-so that continuous samples maybe taken to determine the results 'in the apparatus. The cracked mixturethenl flows down within condenser tube 50 ina direction counter to that of the water and steam of the surrounding jacket. In this condenser, the mixture is cooled preferably to substantially atmospheric temperature, while the heat transfer' medium is reheated. The heat transfer medium will, of course, be heated no higher than the temperature of the oil vapor, and a difference in temperature is necessary to force heat from the steam into the oil of the converter, so .that it is necessary yto raise the temperature of the steam .medium to obtain the desired heat transfer-in the converter. This additional -heat supply, however, is not 10st,. since it is' absorbed inthe oil preheater 4 and water preheater 24,-' where the steam becomes liquid. In case sufiicicnt-heat is not carried to the oil preheater and the water preheater in this manner, the furnace or burner 22. operates to supply the difference above referred to. v

In the tub'e50 the condensed product flows toward the cool end, the tar trap receiving the t-ar and similar heavy hydrocarbons. The remaining oils and water which arestill in gaseous condition `continue down the tube,

ordinary atmospheric temperature continuesl to they gas tank 20. The gas in this tank may be utilized .in the heaters already described, ormay be withdrawn for any desired purpose, it' an excess amouutis' produced.

vThe oil in tank 66 is delivered through pipe 71 to the evaporator and a Suitable switch is thrown in on t-he control board to allow feed of gas to the furnace 72, controlled by valve 74, operated by motor 75, actuated by thermocouple 76, connected with .pyro'meten relay and switch on the control board.

The automatic equipment is so regulated that the feed to this burner will be controlled so as to hold the temperature of the boiler at the desireddistillation temperature. The distilled gases pass up into the pipe 78, and thence down mto the condenser tank 77 where the motor spirit iscondensed ready for use.

In operating the apparatus, the temperature of the continuously moving current of oil vapor and steam is preferably'raised with considerable rapidity in the first portion of the converter and moregradually 1n the latter portion ofl the converter, its temperature preferably being such that when it enters the` cracking orvcatalyzer portion of the tube, it will just be reaching cracking temperature, which is usually somewhere between 800 and 900 F., depending upon the particular oil treated. It will be understood that-the current moves continuously through the apparatus with a continuousfeed of oil and steam, and that the -heatl interchanger operates continuously, absorbing heat from the condenser portion of the apparatus and returning it to the preheater and converter portions of the tube. The velocity which we have employed is over seven feet per second, and We have found that this `prevents deposits of carbon in the tube. In any event, the current should be maintained at such lvelocity that any freed carbon is swept along and carried out; and We conslder ourselves the first to discover this feature of the operation, namely, that with suicient velocity of steam flow, the free carbon will be removed and prevented from deposit-ing, where the oil is dropped into the steam. This oil is thus prevented from creeping along the applied thereto, the distilling system and the electric control system not being shown. In

heat interchanger is retained in this form,

the same as inthe forni of Figure 1, and the lagging or heat-insulating covering is omitted for the sake ofy clearness.

In Figure 3 we show diagrannnatically a form similar to that of Figure 2, except that the4 'steam heater is applied to only a part f the converter. In this case, there are three electric leads 100, to the cracking l'tube andto the latter part of the converter tube, these being connected to a suitable transformer system, utilizing the tubes as heaters to successively step up the temperature. In this case` no differential temperature starting heaters are shown. and in fact,

there is no external sour-:e of heat shown i' or supplying heat to the heat transfer system. arts similar to -those of Figure 1 are designated by similar numerals with the letter b affixed thereto. Hand regulation or automatic regulation may be used, as desired. i

In Figure 4, we show a form similar to that of Figure 2, except that no electric heating is supplied, a steam jacket being employed around the catalyzer or cracking portion of the conduit, as well as around the converter and oil'preheater. In this case, a partition 101 is preferably employed between the catalyzer portion of the conduit and the converter portion, and the steam from the differential temperature and starting heater 52c is carried through tube 102 to the jacket 103 around the catalyzcr portion of the tube and thence through tube 104 to the heater 31. similar. to that of Figure 2. A portion of the steam from this jacket 103 is preferably led through tube 105 direct to the jacket portion 29, encasing the first portion of the converter tube.

The other parts of the apparatus am generally similar to those of Figure 2, and are designated by similar numerals with the letter c applied.' In this case, the heater should be operated in such a manner as to raise the temperature of the cat'alyzer portion of the tube to the desired cracking temperature, usually from 1000 to 1100 F., supplemental heat being-continuously supplied to the heat interchange system for this purpose. i

The advantages of our invention will be obvious to those skilled in the art, since a simple and effective continuous cracking. method is provided by Which high percentages of cracked product may be obtained. The cracking zones are. under close regulation which/[we have found very important in obtaining high yields. If electric heat is used, the amount of this heat supplied is greatly reduced by the heat interchange system, if this is employed, thus greatly reducalso makes the conduit much more accessible.

As the conduit pipe tends to deteriorate rapidly under the temperatures which We employ, we prefer to provide a conduit of much higher heat resistance than ordinary iron or steel. For this purpose, We propose to use either a calorized steel pipe or a pipe. of a special alloy, such, Afor example, as nichrome. This feature gives longer life to the pipe. The use of a material having a specific electrical resistance higher than iron' or steel, such, for example, as 'nichrome, enables us .to use higher voltage and less current to reach the same temperature and also reduces heat losses. The higher -voltage perm-its the use of Asmaller leads, and therefore aords less opportunity for the conduction of heat from the converter out along the leads.

Pipe of calorized steel, or other material' l which is less susceptible to the formation of carbon deposits than ordinary steel andiron pipe is preferably employed. v Calorized pipe is much less susceptible to the forniation of carbon deposits than is the ordinary -iron and steel pipe. Apparently, the iron alumina alloy has less affinity for carbon than ironalone. orl other pipe having less affinity for carbon than ordinary steel or iron pipe, .will permit the reduction of steam velocity or the use of less steam than would be the case in using ordinary steel or' iron pipe for the converter tube.

Many changes may be made in the apparatus employed; certain featuresof our invention may be used Without other features; and changes in the steps may be made without departing from the invention involved in our broader claims.

We claim:

1. In a cracking system, a concentric tubular conduit, means for circulating steam through an inner tube, means fordropping hydrocarbon into the steam, electric heating means employing a portion of the conduit as resistance, and a heat interchanger utilizing a heat exchangev medium other than hydro- The use of calorized pipecarbon to Withdraw heat from the cracked material and supply it to the heating portion of the system, substantially as described.

2. In a cracking system, a tubular conduit comprising first and second portions and having means forprogressively heating the same, said means comprising a heatinterchanging system utilizing a heat eX- change medium other than hydrocarbon to Withdraw heat from the Cracked material, means for further heating said medium, means for supplying said further heated medium to the second portion of said conduit, means for additionally heating said further heated medium 'after -leaving the second portion and' supplying the same to the vfirst portion of said conduit.

3. In a cracking apparatus, a continuous tubular conduit comprising a heating portion and a condensing portion, means for continuously feeding oil vapor therethrough, and a heat interchanger varranged to return heat from the condensing portion of the conduit to the heating portion thereof, and means to controllably increase the heat supu plied to the heating portion, substantially as described. 1

4. In a cracking apparatus, a.- system of double concentric conduits, comprising cracking and condensing portions and a water heating portion, means to pass oil and steam through the inner conduit and therein cracking and later condensing the same, means to conduct cooled Huid from'the water heating portion through the outer conduit in the condensing portion, then increasing the temperature of said fluid, and

passing it through a section of the cracking portion, and further increasing itsjtemperaturc and passing` it through a diifergnt section of the cracking portion and through the Water heating portion.

5. In a cracking apparatus,` a concentric system of conduits, means to supply oil to the inner of said conduits, means to supply a preheating agent to the outer of said conduits,' means to deliver a current of steam under pressure into said inner conduit, automatic means to maintain the preheatin agent at predetermined temperatures at di ferent sections of the concentric conduits, a catalyzer in said inner conduit, and means to maintain said catalyzer at a predetermined teinperature.

6. In a cracking apparatus, a concentric system of conduits, means to supply oil to dependently heat said catalyzer, anda valved discharge outlet to deliver a controlled portion of the cracked oil from said catalzer. Y

7. 11 a cracking apparatus, a concentric system of conduits, one of said conduits conlieating agent at predetermined temperatures at different sections of the concentric conduits, a catalyzer, controllable means to independently heat the catalyzer, a valved discharge outlet to deliver a controlled portion of the cracked oil from the catalyzer, a Water jacketed condenser leading from said catalyzer, means including a differential heater connecting the Water discharge end of the condenser to theo'uter conduit of the concentric conduits, thermostats located in said inner conduit, electrical governing devices, said thermostats cooperating with said elecl trical governing devicesto control the automatic means and the d'erential heater.

00 8. In the cracking of oils, the steps comprising subjecting the oil to increasing predetermined temperatures in contact With a rapid current lof steam and under noncarbon .depositing conditions, passing said heated oil and steam in contact with a heated catalyzer, recovering` the heat from the oil stream after it leaves the catalyzer, controllably increasing said heat, and utilizing said increased heat to prehcat said oil and steam.

9. In the cracking ol oils, the steps comprising subjecting the oil to`increasing predetermined temperaturcs in contact with a rapidcurrent ot' steam ander non-carbon depositing v conditions, controlling the temperatures of the oil and steam at different sections of its vtravel by automatically adding heat to said oil and steam, passing said -oil and steam in contact with a catalyzer,main taining sald catalyzer at a high temperature,

and conveying the treated oil stream from the catalyzer through a heat exchange condensing system, raising the temperature of the cooling agent of the condenser after it leaves said condenser system and transferring the heat from said cooling agent to the oil and steam stream to preheat the same.

In testimony whereof We have hereunto set our hands.

HANS O. SWOBODA. EARL M. RICHARDS.

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