US3763262A - Process for cracking hydrocarbons - Google Patents

Process for cracking hydrocarbons Download PDF

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Publication number
US3763262A
US3763262A US00209730A US3763262DA US3763262A US 3763262 A US3763262 A US 3763262A US 00209730 A US00209730 A US 00209730A US 3763262D A US3763262D A US 3763262DA US 3763262 A US3763262 A US 3763262A
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US
United States
Prior art keywords
tubes
cooler
cracking
gases
inlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00209730A
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English (en)
Inventor
T Sato
Y Onishi
T Omori
Y Abe
K Suehiro
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Chemical Corp
Mitsubishi Heavy Industries Ltd
Original Assignee
Mitsubishi Heavy Industries Ltd
Mitsubishi Petrochemical Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Heavy Industries Ltd, Mitsubishi Petrochemical Co Ltd filed Critical Mitsubishi Heavy Industries Ltd
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Publication of US3763262A publication Critical patent/US3763262A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D51/00—Auxiliary pretreatment of gases or vapours to be cleaned
    • B01D51/10—Conditioning the gas to be cleaned
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G9/002—Cooling of cracked gases
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G9/14—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
    • C10G9/18—Apparatus
    • C10G9/20—Tube furnaces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S585/00—Chemistry of hydrocarbon compounds
    • Y10S585/919—Apparatus considerations
    • Y10S585/921—Apparatus considerations using recited apparatus structure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S585/00—Chemistry of hydrocarbon compounds
    • Y10S585/919—Apparatus considerations
    • Y10S585/921—Apparatus considerations using recited apparatus structure
    • Y10S585/922—Reactor fluid manipulating device

Definitions

  • FIG. 1 PROCESS FOR CRACKING HYDROCARBONS 2 Sheets-Sheet 1 Filed Dec. 20, 1971 FIG. 1
  • This invention relates to a process for cracking hydrocarbons and an apparatus adapted for practicing the same.
  • material gases are thermally decomposed to form cracked gases in two heating tubes B B within a quick heater (cracking furnace) A.
  • the flows of cracked gases are merged into a single flow through an inverted Y-shaped tube joint C, and the combined flow enters an inlet gas chamber F of a cooler E via a straight inlet tube D.
  • From the inlet chamber F the flow of cracked gases is branched off into a plurality of cooling tubes G, wherein the gases are rapidly cooled with a coolant, as water.
  • the inlet tube and inlet gas chamber of the cooler heretofore employed for the conventional process have been so designed that, as shown in FIG. 1, the inlet tube D is a straight tube having a circular cross section while the inlet gas chamber F has a simple axially-symmetrical shape in the form of an elliptoid of revolution or a cone.
  • Variations of the arrangement just described include a vertical type as shown in FIG. 2(I) in which tubes H H each generally megaphone-shaped with the bore gradually increased toward the front end, are connected to the rear ends of heating tubes B B which in turn are joined together with a two-inlet-port, inverted-Y tube joint C, and a horizontal type as in FIG. 2(II) which uses a threeinlet-port tube joint C within a horizontal heater A.
  • the conventional process for preparing useful olefins by the equipment of the constructions above described has the 3,763,262 Patented Oct. 2, 1973 following disadvantages.
  • the pressure loss of the gas flow in the tube joint C is so great and the internal pressure of the equipment is so high that the yields of useful olefins are low.
  • Extended periods of gas retention in the tube joint C, inlet gas chamber F, etc. lead to excessive cracking and hence reduced yields of objective olefins.
  • Coking due to the flow conditions or thermal conditions in the tube joint C becomes more and more serious and eventually hampers the smooth operation of the apparatus.
  • Since the tube joint C is complicated in construction and large in size, it tends to have a structure with thermally and mechanically insuflicient strength.
  • the solid carbides (coke) which flow into the inlet gas chamber F are not accumulated on the bottom of that chamber but deposited On the inner walls of the inlets of cooling tubes G, thus clogging the tubes.
  • the foregoing disadvantages are eliminated because the tube joint C is omitted, the gases from the heating tubes B B are separately led into the inlet gas chamber, upwardly expanded tubes are communicated to the inlet gas chamber, a dead spacer is provided within the gas chamber to eliminate any wasteful swirl, ensure uniform distribution of flow quantities of the gases among the individual cooling tubes, and shorten the retention time of the gases in the gas chamber, a horizontal stepped bottom is provided in the gas chamber (said stepped portion accounting for at least 10 percent, preferably between 30 and 60 percent of the cross-sectional area of the chamber as measured at right angles to the flow direction of the gases) so as to collect and accumulate the coke particles carried away from the heating tubes and thereby avoid any choking of the inlets of the cooling tubes with the coke or any backfiow of the coke to the heating tubes.
  • the apparatus according to the invention makes possible the manufacture of useful olefins in high yields.
  • FIGS. 1 and 2(1), (II) are schematic views of a cooler and connections between the cooler and heating tubes for the conventional process for cracking of hydrocarbons;
  • FIG. 3 is a sectional view of connections between a cooler and cracking tubes in one embodiment of the present invention.
  • FIGS. 4(1), (H) are fragmentary sectional views of diiferent step-like bottoms of a cooler according to the invention.
  • FIG. 3 there is shown an arrangement wherein cracked gases 2 heated in a cracking furnace 1 is allowed to flow therefrom into a cooler 4 through heating tubes (which may also be called cracking tubes) 3.
  • heating tubes which may also be called cracking tubes
  • the cooler 4 has an inlet gas chamber 8 in its lower portion, which chamber is formed by casings 5, 6, heat insulation 7, etc.
  • This chamber 8 is formed by casings 5, 6, heat insulation 7, etc.
  • tubes 10 which are radually increased in the bore toward the outlets and are separately supported with sleeves 9.
  • These tubes 10 have flanges 11 at the rear ends for connection with the flanges 12 of the heating tubes 3. They form two flow passages in the embodiment shown.
  • a space 13 defined between the casings 5, 6 is an annular space of a concentric circle or ellipse with respect to the center axis of the cooler.
  • a horizontal stepped bottom 14 is provided as part of the casing 5 which defines the inlet gas chamber 8. Also a dead spacer 15 is located in the center of the inlet gas chamber 8. As already mentioned, the surface area of the stepped bottom 14 accounts for at least 10 percent of the cross-sectional area of the chamber 8 as measured at right angles to the flow direction of the gases.
  • cracked gases 2 flow into cooling tubes 16 by way of the upwardly expanded tubes 10, space 13, and inlet gas chamber 8. The gases are then cooled through heat exchange with a fluid coolant in a shell 17.
  • stepped bottom 14 is shown horizontally in the embodiment of FIG. 3, it is usually possible to adopt a step either horizontal with an angle to the horizontal line of approximately zero or outwardly inclined with a negative angle or the both, provided that the step surface permits stable deposition of the solid coke thereon.
  • the omission of the merging tube joint which has hitherto been employed eliminates any possibility of a loss of gases pressure due to merging of gas streams, reduces the pressure loss between the outlets of the heating tubes 3 and the cooler 4, and greatly shortens the distance therebetween and hence the retention time between the two, with the consequence that any undesirable secondary reaction can be avoided.
  • the pressure loss of the gases before their entry into the inlet gas chamber 8 is remarkably reduced because the flow velocity of the gases drops for the first time in the upwardly expanded tubes 10 in communication with the inlet gas chamber.
  • tubes similar to the tubes 10 are employed within the heater A in the conventional apparatus shown in FIG. 2(1), the arrangement is disadvantageous because the gases take much retention time after passage through the megaphone tubes and cannot be cooled rapidly.
  • the inlet gas chamber according to the present invention is so constructed that the velocity of the cracking gases in the chamber space can be reduced to a suitable level.
  • the spacer may take any adequate shape to ensure uniform distribution of the gas flow rates to the individual cooling tubes 16.
  • the provision of the horizontal stepped bottom 14, which accounts for at least 10 percent, and preferably between and 60 percent, of the cross-sectional area of the gas chamber 8 as measured at right angles to the flow direction of the gases, enables the coke particles that fly from the heating tubes to drop out of the gas stream and deposit on the sepped portion for subsequent collection, instead of being mixed again into the gas stream.
  • Still another advantage associated with the omission of a tube joint resides in the great mechanical strength that is attained.
  • Ordinarily structures havea number of problems attributable to the thermal conditions for the tube joint.
  • the tube joints of cast metal are easily cracked by thermal strains.
  • the present invention possess no such problem and reduces the manufacturing cost of the apparatus with the omission of such a casting.
  • the yields of cracked gases are adversely affected by the pressure rise in the heating tubes corresponding to a high rate of pressure rise in the outlet of the cracking furnace, or in the inlets of the cooling tubes due to deposition of coke thereon. Furthermore, the decoking intervals are shortened because of the increase of the coking velocity on the heat transfer tubes and therefore the increase of the rate at which the surface temperature of the reaction tubes climbs.
  • the process of the present invention reduces both the rates of increase of the pressure at the outlet of the cracking furnace and the surface temperature of the heating tubes, and extends the decoking intervals to a value more than twice as long as the usual intervals.
  • the process makes it possible to increase the yields of C H C H and 1,3butadiene by about 15, 8 and 16percent, respectively.
  • the process of the invention was confirmed to have very significant advantages over the conventional process.
  • a process for producing useful olefins by thermally cracking hydrocarbons through a plurality of cracking tubes and cooling the resulting cracked gas in a single multitubular, vertical type cooler comprising the steps of passing individual streams of cracked gas'from said cracking tubes upwardly into corresponding individually connected tubes of gradually increasing diameter without mixing said streams, causing said gas from said gradually increasing diameter tubes to flow through an inlet chamber connection into an inlet chamber having a steppedbottom extending from said inlet connection, said tubes of gradually increasing diameter and said inlet chamber being located in the lower portion of said cooler, and passing said gas from said inlet chamber to said cooler.
  • Apparatus for producing useful olefins comprising a plurality of thermal cracking tubes, a gradually increasing diameter tube connected to each of said thermal cracking tubes whereby individual streams of gas pass from said thermal cracking tubes to a respective gradually increasing diameter tube without mixing with one another, a multi-tubular, indirect cooler having generally vertically disposed cooling tubes for cooling said cracked gas, and an inlet gas chamber in the lower portion of said cooler communicating with said cooler tubes, said gradually increasing diameter tubes being connected to the bottom of said inlet gas chamber, said bottom of said inlet gas chamber having means defining a step extending from the inlet connection of said gradually increasing diameter tubes.
  • said inlet gas chamber is defined at least in part by an inner wall disposed generally in the center of said inlet gas chamber, said inner wall also defining the outer boundary of a dead space disposed centrally of said inlet gas chamber, said gradually increasing diameter tubes being connected to the bottom of said inlet gas chamber to open into the latter adjacent to said inner wall.
  • both of said cross-sectional areas being measured at right angles to the flow direction of the cracked gases.
  • step defining means is formed as a ledge disposed beneath said cooler tubes for collecting coke particles carried by said gas.
  • step defining means is disposed radially outwardly of said gradually increasing diameter tubes.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
US00209730A 1970-12-29 1971-12-20 Process for cracking hydrocarbons Expired - Lifetime US3763262A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45128035A JPS4811682B1 (enrdf_load_stackoverflow) 1970-12-29 1970-12-29

Publications (1)

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US3763262A true US3763262A (en) 1973-10-02

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US (1) US3763262A (enrdf_load_stackoverflow)
JP (1) JPS4811682B1 (enrdf_load_stackoverflow)
DE (1) DE2163988C3 (enrdf_load_stackoverflow)
FR (1) FR2120113B1 (enrdf_load_stackoverflow)
GB (1) GB1332426A (enrdf_load_stackoverflow)
HU (1) HU165830B (enrdf_load_stackoverflow)
IT (1) IT945836B (enrdf_load_stackoverflow)
NL (1) NL170431C (enrdf_load_stackoverflow)
PL (1) PL90338B1 (enrdf_load_stackoverflow)
RO (1) RO69722A (enrdf_load_stackoverflow)
SU (1) SU670232A3 (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1979000395A1 (en) * 1977-12-15 1979-07-12 Atlantic Richfield Co System for preventing gas decomposition in pipelines
US4192658A (en) * 1978-07-03 1980-03-11 Atlantic Richfield Company Pipeline flame arrestor
US4457364A (en) * 1982-03-18 1984-07-03 Exxon Research & Engineering Co. Close-coupled transfer line heat exchanger unit
US4544030A (en) * 1983-08-15 1985-10-01 American Standard Inc. Shell nozzle
US5147511A (en) * 1990-11-29 1992-09-15 Stone & Webster Engineering Corp. Apparatus for pyrolysis of hydrocarbons
US5464057A (en) * 1994-05-24 1995-11-07 Albano; John V. Quench cooler
US20090280448A1 (en) * 2008-05-12 2009-11-12 Coprecitec, S.L. Multiple gas pilot burner

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI65275C (fi) * 1982-06-14 1984-04-10 Neste Oy Foerfarande foer termisk krackning av kolvaeteolja
JPS62118146U (enrdf_load_stackoverflow) * 1986-01-16 1987-07-27
EP0387377A1 (de) * 1989-03-16 1990-09-19 VIA Gesellschaft für Verfahrenstechnik mbH Rohrbündelwärmetauscher

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1528383A (fr) * 1966-06-24 1968-06-07 Lummus Co Dispositif de raccordement d'un réchauffeur et d'un échangeur de chaleur

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1979000395A1 (en) * 1977-12-15 1979-07-12 Atlantic Richfield Co System for preventing gas decomposition in pipelines
US4192656A (en) * 1977-12-15 1980-03-11 Atlantic Richfield Company Method and apparatus for halting the advancement of accidental ethylene decomposition in a gas pipeline
US4192658A (en) * 1978-07-03 1980-03-11 Atlantic Richfield Company Pipeline flame arrestor
US4457364A (en) * 1982-03-18 1984-07-03 Exxon Research & Engineering Co. Close-coupled transfer line heat exchanger unit
US4544030A (en) * 1983-08-15 1985-10-01 American Standard Inc. Shell nozzle
US5147511A (en) * 1990-11-29 1992-09-15 Stone & Webster Engineering Corp. Apparatus for pyrolysis of hydrocarbons
US5464057A (en) * 1994-05-24 1995-11-07 Albano; John V. Quench cooler
US20090280448A1 (en) * 2008-05-12 2009-11-12 Coprecitec, S.L. Multiple gas pilot burner
US8137098B2 (en) * 2008-05-12 2012-03-20 Coprecitec, S.L. Multiple gas pilot burner

Also Published As

Publication number Publication date
NL7118072A (enrdf_load_stackoverflow) 1972-07-03
FR2120113B1 (enrdf_load_stackoverflow) 1975-02-07
NL170431B (nl) 1982-06-01
IT945836B (it) 1973-05-10
DE2163988A1 (de) 1972-07-20
GB1332426A (en) 1973-10-03
SU670232A3 (ru) 1979-06-25
JPS4811682B1 (enrdf_load_stackoverflow) 1973-04-14
RO69722A (ro) 1981-08-17
DE2163988C3 (de) 1978-09-07
FR2120113A1 (enrdf_load_stackoverflow) 1972-08-11
HU165830B (enrdf_load_stackoverflow) 1974-11-28
NL170431C (nl) 1982-11-01
PL90338B1 (enrdf_load_stackoverflow) 1977-01-31
DE2163988B2 (de) 1976-05-06

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