DE2117691A1 - Process for the delayed coking of pyrolysis fuel oils - Google Patents

Description

Dr.-lng. E. BERKENFELD · Dipl.-Ing. H. BERKENFELD, patent attorneys, Cologne

2717691

Attachment file number

for entry from March 31, 1971 vA // Name of d. Note: The Lummus Company

Process for the delayed coking of pyrolysis fuel oils

is the delayed coking of petroleum residue oils / in the petrochemical Industry well established and gives maximum recycle from the residual oils by increasing the yield of both Coke as well as more desirable liquid and gaseous products such as liquefied petroleum gas, gasoline and gas Gas oil. The process has gained particular importance because it has also been found to be an excellent way of producing it of first quality coke or needle coke, which is selected from certain selected in the production of large graphite electrodes clean starting materials is useful that have a high Have content of aromatic substances.

After the use of pyrolysis fuel oils as raw materials was known for the common method of delayed coking, it has been found that this use is in industrial Practice is associated with significant disadvantages. In particular, it has been found that various components of the system for delayed coking by the deposition of coke and / or polymer are clogged, making the plant almost inoperative made or the operational efficiency is so reduced that the process is uninteresting from an industrial point of view by greatly increasing the cost of ownership of the delayed coking process. It was for example found that plugs of coke or polymer in the lower part of the fractionator, in the heater coil, in the transfer line to the coke drums and in the steam lines leaving the coke drums.

The invention relates to the production of high quality coke from highly reactive pyrolysis fuel oils which are difficult to produce

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process are. In particular, the invention relates to a new and improved method for the delayed coking of pyrolysis fuel oils, to enable a high level of effectiveness or trouble-free operation to be achieved.

3s it has been found that the detrimental clogging previously occurring in the delayed coking of pyrolysis fuel oils due to the deposition of coke and polymer can be avoided if the delayed coking process has certain additional features. According to the invention is an effective and zv / eckmäßige production of high quality coke from Pyrolystorennstoffölen executable when the method of delayed Yerkot ken the steps _s singly or in combination, becoming added

a) that sulfur is added to the pyrolysis fuel oil before the same is introduced into a collecting container,

b) that the Pyroly ^ sebrennstofföl is maintained in the collecting container uLhrend at least five minutes on a Tsznpsratur of more than 252 C _s be '/ or dassslös la passed as coking Hsizvorrichtung i> iirä. ₉

c) that the outlet of the BeisvorrichtiiBgssGhlaEgs and the eok drum under a pressure ~ rozi not i-jszd.srar than "3.80 kp / cm

'will hold «,

Another optional SferSsiaal kana uis Izrj-Bnäxmg a cooling device ia the Ζί & £ 3'ϊτοΜίί®22λ "TS'S-'L ^ äsenüen Lampfleitiniigen be".

¥ esia dem Verfalires zum Tsr-sSger-ten Yevkoksn one or Eshrsre this step Minsugefendet ^ υΐτά ^r l ± 3 Slierung ύόιι plug as, äQii aiafäiiigeis, Stsll-sn of the plant siazn 'vsrsöjjertesi Y3TliO2s.

• The ikasgangSMaterialp that of the plant zm -jersogerten ¥ erkoi: an at L 68/5 = "- =

The embodiment of the invention is a pyrolysis fuel oil. Pyrolytic fuel oils are the remaining heavy, black oils that boil above the pyrolysis gasoline, that is, at about 190 to 218 ° C, and that along with olefins in the pyrolysis of liquid hydrocarbon feedstocks be generated. Such residual oils are known and for example in the American patents 3,326,796 and 3,451,921, as well as in the patents and publications cited therein.

In carrying out the method according to the invention, sulfur is added to the feedstock before the pyrolysis fuel Oil is fed to a collecting container, which is not provided in a conventional coking device. The sulfur can the pyrolysis fuel oil in the form of elemental sulfur or in the form of a corresponding organic sulfur compound be added, such as mercaptan. But whichever form is used, the amount used must be sufficient so that sulfur is present in the pyrolysis fuel oil in an amount not less than about 30 parts 1 million parts, preferably about 100 to 200 parts per million Parts.

To facilitate the dissolution of the elemental sulfur in the oil, it is desirable to add the sulfur to the oil at a temperature of from about 38 to 149 ° C, preferably from 65 to 93 ° C. This can be advantageously accomplished by dissolving the sulfur in a bypass flow and the resulting Solution is again mixed with the feed stream.

The pyrolysis fuel oil is then fed to the collecting container, in which the same is subjected to a collecting treatment, which consists in that the oil in the container on a Maintained temperature of about 232-315 ° C, preferably 260 ° C is for a period of about 5 to 120 minutes, usually for a period of about 15 to 25 minutes.

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At the end of this period, the pyrolysis fuel oil treated in this way is mixed with a circulating flow in a volumetric ratio of the circulating flow to the fresh supply flow of about 0.1 to about 5: 1, and then fed to the coking heater. There the feedstock is rapidly heated to a temperature of about 454 ° C before it passes to the coke drum. The coke heater outlet and the coke drum are pressurized to

'' not less than 1.80 kg / cm, advantageously from about 4.25 to 9.50 kg / cm, so that the proportion of the feed flow, which is in the liquid phase during the time it passes through the heater coil, * is a maximum.

After passing through the coking heater, will the pyrolysis fuel oil is fed to the coke drum, in which coke is formed. The coke becomes according to any of the commonly used ¥ experienced formed and discharged with the exception that - as noted above - the coke drum is kept under a pressure of not less than 1.80 kg / cm "during the coking period«

According to an optional feature, the steam from the coke drum can be subjected to cooling by means of a cooling device, which are arranged in the steam line leaving the Kokstronunel is. This feature excludes vapor phase coking and serves to keep the steam line free of any coke rinse that may have already formed.

The invention will now be made with reference to the drawings illustrated embodiment described in more detail. The drawing has been "jereiafaclit" to the description of the same. facilitate ^ and various aids, such as valves, pumps and the like, are therefore not shown in the same. the The drawing shows only one exemplary embodiment of the invention and the scope of the invention is in no way intended to be limited by the same *

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According to the drawing, a pyrolysis fuel oil such as the heavy, high-boiling fractions obtained from cracking petroleum festillates in the presence of steam, in order to produce olefins, fed to the plant via line 10. A bypass flow of this feed flow is through a Pot 2, which contains elemental sulfur. The bypass flow dissolves enough sulfur so that after mixing with the main flow the sulfur content of the feed stream is about 30 to 200 parts per million parts. The sulfur containing pyrolysis fuel oil is then passed through a heat exchanger 11 to by indirect heat transfer of heavy oil fraction, heating the pyrolysis fuel oil to effect, as will be described below, and then through a line 14 into the receiver 4, in which the pyrolysis fuel oil at a 'temperature of about 260 ° C and one Pressure of about 1.80 to 9.50 kgf / cm is maintained for a period of 5 to 120 minutes. The steam from the collecting container 4 passes through the line 3 into the fractionator 12, v / o the same mixes with the steam from the coke drum 18. The high-boiling fractions of the steam from the coke drum condense in the fractionator and are passed through the fractionator 12 the line 14 discharged so that they heated as a circulating flow Oil are mixed in, which is discharged from the collecting container 4 through the line 5 and enters the line 34.

The combined feed flow in line 34 is converted into a Coking heater 15 of known type introduced, which is operated so that an outlet temperature of about 440 to 538 ° C, usually from about 440 to 510 ° C will. This heater coil is also under one

Outlet pressure of not less than 1.80 kp / cm, preferably un-

under a pressure of about 4.25 to 9 »50 kgf / cm. To the To prevent premature coking in the coking heater, the feed flow to the coil becomes more common Way kept fluid at high speed. When the oil is heated, the temperature and pressure in the heater will increase partial evaporation of the feed flow

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act, thereby increasing the flow rate and preventing the coking problems caused by a slow moving feed flow. In this case, however, what is most desirable is such a large group to keep this feed flow in the liquid phase, as is practically compatible with the strong turbulence. Occasionally Controlled amounts of steam can be introduced into the coking heater 15 at appropriate points in order to to achieve the required high speed,

The heated feed stream is withdrawn from the coking heater 15 through line 17 and introduced into a coke drum 18 of known type in which the heavier components of the feed stream are converted to coke and lighter components. The Koksti * ommeln are under a pressure of not less than 1.80 kg / cm, preferably of about 4? 25 to 9.50 kp / cm, and at a temperature of eti / a 427 to 496 ° C, preferably from about 440 to 482 ° C operated. The coke is discharged from the eokstroinmel 18 through the line 19 after the drum is filled. During this Ähtuh approximate period, the other Eokstroismel 18a is switched on ^ to be filled with coke.

With the optional equipment in which a cooling device is used, the steam discharged to the drum 18 through the line 21 is cooled to less than 399 ° C, preferably to about 315 Ms 371 ° C =, if it contains steam

■ "• ο *

The light distillates discharged from the fractionator 12 are brought into contact with the light distillates discharged from the conduit 32 and discharged from the Eokstronael / JS.

Bar drain from the EokstroEEss! is in Fralrtionator 12 Is, ver different products ait ^ s ^ sehiedenen Siedebsrsichen gsssMsäsa and containing g wotiilict 2222sin _s easy Gasölj, scliwsrsss Gssöl and UmlaiifstrSEyaago -las gasoline is filtered at the upper end and has nacii the IConösasatioa a Sn ^ siedepuBlct of 177 Ms £ iS °

Ij Th / j - * j "^ ³¹

C on, The light gas oil that boils above the gasoline becomes taken on the side «t and has an initial boiling point from 163 to 204 ° C and a final boiling point of 232 to 375 ° C, but usually about 343 ° C. The heavier boiling point Gas oil is taken from the side and has an initial boiling point of 218 to 343 ° C, usually about 329 ° C, and a Final boiling point of 260 to 399 ° CV. The final boiling point of the heavy gas oil is determined by the ratio of the overflow flow to the * fresh feed flow determines that of the coking heater's is fed. The initial boiling point of the recirculating flow is 246 to 385 ° C, and it contains all of them higher-boiling components in the effluent of the coking device.

The heavy gas oil that passed the fractionator 12 through the line 22 is discharged, is cooled in the heat exchanger 11 by indirect heat transfer from the supply flow in the line 10. The same is further cooled in the heat exchanger 23 to a temperature that is necessary for the introduction of the required circulating flow in the fractionator 12 is suitable, generally to a temperature of about 177-315 ° C, by indirect Heat transfer from an appropriate coolant, such as boiler feed water, part of this flow of the cooled heavy gas oil from the heat exchanger 23 is in the fractionator 12 through 'the line 25 or 26 with a regulated Velocity introduced to have a volumetric ratio of recirculating flow to fresh feed flow of about 0: 1 to about 5: 1. The entire overflow flow consists of the heavy fraction of the heavy gas oil which is carried by the Line 25 or 26 is introduced from the condensed heavy oil vapors from the coke drums introduced through line 21 are, and from decondensed heavier vapors introduced through line 3. The condensation will caused by direct contact with the cooled heavy gas oil fraction, as well as the lighter overflow current from the top of the tower. The net amount of heavy gas oil from the coker is removed from the heat exchanger 23 and discharged through the line 27 into a storage container.

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Numerous modifications of the invention are possible without departing from the scope of the invention. For example, the feed stream can be treated to cause evaporation of the material below the final boiling point of the light gas oil recovered from the delayed coking process in a device other than the fractionator or receiver. The starting material can be fractionated separated in a distillation tower to the lighter fractions excrete, and in such a case in which the stay is in a reboiler of sufficient duration would 4 actually carried out a rescue treatment that is equivalent to that which the collection vessel takes place. Similarly, holding the oil in a separate container under pressure and at a sufficient temperature would also effect a treatment equivalent to that which takes place in the receiver. Such modified embodiments must be viewed as falling under the designation "that the sulfur-containing pyrolysis fuel oil is directed into a collection zone in which the oil is maintained at a temperature and for a period of time sufficient to remove the highly unsaturated constituents present in the oil to polymerize ". Likewise, the various heat transfer steps can be carried out in other ways than described above. For example, the feed stream to the fractionator can be heated in the convection section of the coking heater or in another heater.

The invention is illustrated by the following example, which does not limit the scope of the invention will.

EXAMPLE

A pyrolysis fuel oil derived from the steam cracking of naphtha for the production of olefins and which contains the

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Belle I has specified properties, is coked under the conditions specified in Table II.

TABLE I.

Specific gravity 1.0404

Viscosity SUS at 38 ° C 53.6

Conradson carbon weight percent 9.44

5 % boiling point 199 ° C

Dien value. 9.3

TABLE II

Pressure kp / cm flow rate kg / h

management Temperature C 10 21st 13th 260 3 260 5 260 14th 343 17th 454 21st 371 32 21st

15.40

15.40

8.15

7.25

12.96

5.30 20.20

5.30 25.78

8.65

The circulating oil from line 14 from the bottom of the fractionator results in a ratio of the circulating flow to the fresh feed flow of 1.8: 1 percent by weight «,

The fractionator 12 is operated at the upper end at a temperature of about 93 ° C. and under a pressure of 0 kgf / cm. Additionally the gas product discharged at the top becomes the following liquid products from the total feed stream regained η »

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TABLE III * /> .Component Weight- ^
mung 1.63
4.76
5.39 Petrol (C ₅ - 180 ° C)
Kerosene (180 - 230 ° C)
Gas oil (+ 230 ° C) 10.6
30.9
35.0 11.78 Entire liquid product 76.5

Coke at a rate of 3.08 kg / h produced (19.9 wt -.% Of the fresh feed flow) and has the following characteristics: *

TABLE IV

Ash 0.0 wt .- #

Sulfur 0.02 wt .-? 6

Volatile substances 6.2 wt .- #

Fixed carbon 93.8 wt %

Apparent density 1.00 g / cm ³

The above procedure is repeated using as the starting material the pyrolysis fuel oils which are those shown in Table V have specified properties.

C. TABEL V 1.0703 C. 21 ° C 575.8 at 93.2 0 0

Specific gravity at 21 ^u C 1.0703 1.1752 Viscosity SUS at 60 ^c

Viscosity SUS at 99 ° ^C

Viscosity SFS at 121 ° C 93.5

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Conradson carbon, wt % 16.3 31.1 sulfur, wt% Si 1.6 2.77

The coke produced from the above raw materials has the same general properties as that from the raw material the example produced coke »

According to the invention, the supplied pyrolysis fuel oils are subjected to a process for delayed coking without the coking plant being adversely clogged, so that an excellent coke yield is obtained. With pyrolysis fuel oils, which are low in sulfur and high in aromatics, the coke produced is of prime quality. When the coke is calcined and processed into a pressed electrode and graphitized, it is characterized by a satisfactory thermal expansion coefficient in the longitudinal direction of less than 1.1 x ^10/0 C, measured at 30 to 100 ° C.

Claims

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Claims (13)

Dr.-lng. E. BERKENFELD · Cipl.-lng. H. BERKENFELD, patent attorneys, Cologne sntanwalt. K < 2117601 Attachment file number from March 31, 1971 vA // Name d. Anni. The Lummus Company PATENT CLAIMS A method for producing petroleum coke, characterized in that sulfur is dissolved in a pyrolysis fuel oil, that the sulfur-containing pyrolysis fuel oil is passed into a collecting zone in which the oil is kept at a temperature and for a period of time which is sufficient to keep the oil in the oil high to polymerize unsaturated constituents that the treated oil is passed into a heating zone in which the oil is heated to a coking temperature under a pressure of not less than 1.80 kgf / cm, and that the oil is then passed into a coking zone, wherein a liquid part of the oil in this zone is kept at the coking temperature and converted into coke, "S, 2. The method according to claim 1, characterized in that the sulfur dissolved in the pyrolysis fuel oil by heating will. 3. The method according to claim 2, characterized in that the sulfur is added in the form of elemental sulfur. 4. The method according to claim 2, characterized in that dor sulfur is added in the form of an organic sulfur compound will. 5. The method according to claim 1, characterized in that the pyrolysis fuel oil in the collection zone at a temperature of about 232-315 ° C for a period of about Is held for 5 to 120 minutes « 6 "The method according to claim 1, characterized in that L 68/5 - 12 - 109848/1185 the pyrolysis fuel oil the heating zone at one temperature from about 440 to 538 ° G and under a pressure of about 1.80 leaves up to 20 kp / cm. 7. The method according to claim 1, characterized in that the coking zone is under a pressure of not less than 1.80 kp / cm is maintained, 8. The method according to claim 7, characterized in that the coking zone under a pressure of about 1.80 to 9.50 kp / 2
cm is held. 9. The method according to claim 8, characterized in that the coking zone is at a temperature of about 440 to 527 ° C is held. 10. Process for producing petroleum coke from pyrolysis fuel oil, characterized in that sulfur is in the form of elemental sulfur or an organic sulfur compound is dissolved in a pyrolysis fuel oil by subjecting the mixture of oil and sulfur to a temperature of about 38 to 149 ° C is that the sulfur-containing oil is passed into a collecting zone in which the oil is at a temperature of about 232 to 315 ° C is maintained for a period of about 5 to 120 minutes, that the treated oil is passed into a heating zone in which the oil is heated to a temperature of about 440 to 538 ° C is heated under a pressure of about 1.80 to 20 kgf / cm, and that then the oil in a coking zone is passed, in which the oil at a temperature of about 440 to 527 ° C and under a pressure of about 1.80 to 9.50 kp / 2
cm is coked. 11. Method of producing first quality coke, thereby characterized in that sulfur is dissolved in a pyrolysis fuel oil that the sulfur-containing pyrolysis fuel oil in a collecting zone is passed in which the oil is at a temperature and is held for a period of time that is sufficient L 68/5 - 13 - 109848/1185 to add to the unsaturated constituents present in the oil polymerize that the treated oil is passed into a heating zone in which the oil is under a pressure of not less than 1.80 kp / cm is heated to a coking temperature, that then the oil is passed into a coking zone, wherein a liquid part of the oil in this zone is kept at the coking temperature and converted into coke, and that the steam emerging from the coking zone is subjected to cooling before it is condensed and recirculated. 12. A method of producing petroleum coke in which a pyrolysis fuel oil is subjected to preheating, after which the preheated oil is passed into a heating zone, in which the oil is heated to the coking temperature and then coked, the improvement being that sulfur is dissolved in the pyrolysis fuel oil before the same is preheated. 13. A method for producing petroleum coke, characterized in that that a pyrolysis fuel oil is passed into a collection zone in which the oil is at a temperature and during is held for a period of time sufficient to polymerize the highly unsaturated constituents present in the oil, that the treated oil is passed into a heating zone in which the oil is under a pressure of not less than 1.80 kp / cm is heated to a coking temperature, and that the oil is then passed into a coking zone, a liquid Part of the oil in this zone is kept at the coking temperature and converted into coke. L 68/5 - 14 - 109848/1185