US3365387A - Off-stream decoking of a minor portion of on-stream thermal cracking tubes - Google Patents

Off-stream decoking of a minor portion of on-stream thermal cracking tubes Download PDF

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US3365387A
US3365387A US546277A US54627766A US3365387A US 3365387 A US3365387 A US 3365387A US 546277 A US546277 A US 546277A US 54627766 A US54627766 A US 54627766A US 3365387 A US3365387 A US 3365387A
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tubes
stream
steam
cracking
furnace
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US546277A
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Robert P Cahn
John A Kivlen
David K Thurlow
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ExxonMobil Technology and Engineering Co
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Exxon Research and Engineering Co
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Priority to US546277A priority Critical patent/US3365387A/en
Priority to GB38710/66A priority patent/GB1117562A/en
Priority to NO164749A priority patent/NO138287C/en
Priority to IL26518A priority patent/IL26518A/en
Priority to BE687073D priority patent/BE687073A/xx
Priority to NL666613309A priority patent/NL146871B/en
Priority to FR77382A priority patent/FR1501836A/en
Priority to DE1568469A priority patent/DE1568469C3/en
Priority to AT918066A priority patent/AT276600B/en
Priority to DK515466AA priority patent/DK116434B/en
Priority to ES0331979A priority patent/ES331979A1/en
Priority to SE13692/66A priority patent/SE353077B/xx
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    • 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
    • C10G9/16—Preventing or removing incrustation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy

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  • the present invention pertains to a method of decoking the tubes of a cracking furnace and particularly to the decoking of the coils or tubes of a steam cracking furnace.
  • Steam cracking of the hydrocarbon feed stock is effected by supplying the feed stock in vaporized or substantially vaporized form in admixture with substantial amounts of steam to suitable coils in a cracking furnace. It is conventional to pass the reaction mixture through a number of parallel coils or tubes which pass through a convection section of the cracking furnace wherein hot combustion gases raise the temperature of the reaction mixture. Each coil or tube then passes through the tired or radiant section of the cracking furnace wherein a multiplicity of Aburners supply the heat necessary to bring the reactants to the desired reaction temperature and effect the desired reaction or conversion.
  • lt is a further object of this invention to provide an improved process for thermal cracking of hydrocarbon feed stocks in the presence of steam wherein coke deposits are removed without shutting down the cracking furnace and with only a minor reduction in production throughput of the system.
  • Sufcient steam and/or water are introduced to remove the Aheat normally going to the process fluid without exceeding the tube metal temperature allowances as determined by stress or oxidation limits for the tube material.
  • the temperature of the steam entering the section of the furnace to -be decoked must be about 700 F. or higher. lf water in introduced it must be vaporized and superheated to this temperature while steam must be merely superheated.
  • the mass rate of steam entering the section of the furnace to be decoked should preferably be greater than pounds per second per square foot of tube internal cross-sectional area when the tube outlet pressure is of the order of -25 p.s.i.a. Higher mass rates at constant Itemperature reduce the time required for decoking. Higher operating pressures in the furnace tubes being decoked require higher mass rates of steam for the same decoking time.
  • a furnace pass may be decoked in l2 hours or less.
  • the same procedure may be used at any time deemed desirable to decoke additional passes, one at a time.
  • two or more passes in a multipass furnace can be decoked in this manner simultaneously, but this does tend to detract from the major advantage of this scheme, namely, minimum upset to normal operation.
  • the cracking furnace 10 comprises an upper, convection or preheat section 11 and a lower, cracking zone 12.
  • Burners 13 are provided on the side walls and/or on the bottom of the furnace to supply heat. The number of burners provided is dependent upon the heat require-d and may vary considerably.
  • the furnace contains several conduits or passes in parallel. Each pass may contain a number of connected tubular members or tubes that provide a flow path through the convection section and into the cracking section. ln the drawing, one pass is shown, with the tubes in the convection section 11 designated by the numeral 15 and the cracking coils or tubes in the cracking zone 12 designated by the numeral 16. It is to ⁇ be understood that the number of conduits or tubes in the furnace is a function of the size of the furnace and is dictated solely by design considerations.
  • Hydrocarbon feed stock is supplied to the steam cracker via supply conduit 20 and manifold or distributor conduit 21 to the several parallel cracking conduits or passes.
  • a control valve 22 is provided on each conduit 23 connecting the feed distributor 21 to each of the cracking conduits or tubes.
  • Steam, or in the decoking operation, steam and/or water are supplied Kthrough inlet line 24 and valve 25 to the conduit 23. (In some cases, steam and water are supplied through separate lines and not necessarily at the identical point in the convection section.)
  • reaction products are discharged from the coils or tubes 16 of the cracking furnace via conduits 26 into conduit or header 27 from which they are discharged into conduit 2S.
  • quenching agents such as higher boiling hydrocarbons and/or water are supplied through conduit 29 and control valve 30.
  • the mixture of quenched reaction products and quenching agent is discharged via conduit 23 into fractionating tower 31.
  • Aromatic tar product is withdrawn from the bottom of fractionating tower 31 through line 32 and product is taken overhead via line 33.
  • Other intermediate boiling range fractions may be withdrawn as product or recycled to a higher plate in the fractionating tower as one or more reflux streams.
  • the quench oil may be withdrawn from the fractionating tower 31 through line 34 and passed through heat exchanger 35 where it is passed in indirect heat exchange relation to the hydrocarbon feed stock for preheat thereof or to water for steam formation while cooling the quench oil to a suitable temperature for discharge through line 29 and valve 30 into the reaction product stream in line 28 as described above.
  • the on-stream decoking procedure requires the closing of one of the hydrocarbon feed valves 22 and the opening of the steam water valve 25.
  • the amount of steam and Water passed through the decoking conduit 24 is adjusted so that the steam temperature inside the pass is about 700 F. or higher at the point of transition from convection tubes 15 to cracking tubes 16.
  • valve 25 is closed and valve 22 is opened.
  • a steam cracking furnace containing ten passes or conduits was decoked by slowly backing out the hydrocarbon feed to one pass at a time while adding boiler feed water and adjusting normal steam flow.
  • Three tests were carried out by varying the quantities of steam, water and time of decoking, and a fourth test was made with constant Water and steam rates in one ⁇ pass until a furnace shutdown some twenty hours later.
  • the furnace was shut down and the tubes were then removed from the furnace for examination. The following are summaries of the tests which were carried out and the condition of the tubes on examination after the furnace was shut down.
  • Feed to pass 8 backed out over a 2-hour period.
  • feed was returned to the pass D 6 801 nu 7 8 9 2 5 0 ew mu Is o 00000 0 0 o o 0 0 400 0 W 55777 7 7 7 9 9 504 8 um 1 66990 9 9 9 9 2 2 722 n u om.
  • Feed to pass 6 was backed out using After a further 30 minutes the steam a steam/Water mixture over a period of minutes. flow was reduced for a 10 second period to induce thermal shock in the tube. rlhis was repeated 5 minutes later. Feed was again returned to Nora-Large tube areas of Pass No. 6 were found to be completely free of coke when examined alter the furnace shutdown. Remaining areas had coke deposits of average thickness .OSS' (micrometer readings).

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)
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Description

Jan. 23, 1968 R. P. CAHN ET AL 3,365,387
OFF-STREAM DECOKING OF A MINOR PORTION OF' ON-STREAM THERMAL CRACKING TUBES Filed April 29, 196e CEF* N v N) ROBERT P. CAHN JOHN A. Kil/LEN mvENToRs DAV/D K. THURLOW PATENT ATTORNEY United States Patent Gtlce 3,365,33? Patented Jari. 23, i968 OFF-STREAM DECGKING F A MNOR POR- 'HN 0F ON-STREAM THERMAL CRACK- ING TUBES Robert P. Cahn, Millburn, and llohn A. Kivlen, Sparta,
NJ., and David K. Thnrlow, Brockenhurst, Hants, England, assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Apr. 29, i966, Ser. No. 546,277 8 Claims. (Cl. 208-48) ABSTRACT 0F THE DISCLGSURE Thermal cracking of hydrocarbons in admixture with steam leads to the deposition of coke on furnace tube walls, which coke must be periodically removed to maintain `cracking efliciency; said coke can now be removed by passing, through one or more tubes, a steam and/or Water feed to decoke those tubes, while maintaining the furnace on stream.
The present invention pertains to a method of decoking the tubes of a cracking furnace and particularly to the decoking of the coils or tubes of a steam cracking furnace.
Various processes have been described in the prior art on high temperature thermal cracking or steam cracking of hydrocarbons including high boiling hydrocarbons such as residual oils and gas oils, and lower boiling hydrocarbons such as naphtha and hydrocarbon gases such as ethane, propane, etc., to produce olens such as ethylene, propylene, diolens such as butadiene, isoprene, etc., and aromatic hydrocarbons such as benzene, toluene, etc. In these processes the petroleum feed stock is vaporized, diluted with steam and cracked in a coil at a temperature of about 1200 to 1600* F. Residence times are relatively short, usually in the range of about 0.1 to 5.0 seconds whereupon the reaction products are immediately quenched to arrest further reactions and minimize loss of primary conversion products.
Steam cracking of the hydrocarbon feed stock is effected by supplying the feed stock in vaporized or substantially vaporized form in admixture with substantial amounts of steam to suitable coils in a cracking furnace. It is conventional to pass the reaction mixture through a number of parallel coils or tubes which pass through a convection section of the cracking furnace wherein hot combustion gases raise the temperature of the reaction mixture. Each coil or tube then passes through the tired or radiant section of the cracking furnace wherein a multiplicity of Aburners supply the heat necessary to bring the reactants to the desired reaction temperature and effect the desired reaction or conversion.
When hydrocarbon feed stocks are subjected to the heating conditions prevalent in a steam cracking coil furnace, coke deposits tend to form on the inner walls of the tubular members forming the cracking furnace coils. The problem of coke deposition on the inner surface of such cracking furnace cos has become a major concern in the steam cracking of hydrocarbons since such coke deposits not only interfere with heat flow through the tube walls into the stream of reactants but also with the flow of the rea-ction mixture due to reduction in the cross-sectional area of the tubes.
In the cracking section of a steam cracking furnace it is necessary to heat these tubes or coils to temperatures of the order of about 1600 to 2000 F. in order to obtain reactant temperatures within the tubes of about 1200 to 1600+ F. which are necessary to give yield patterns and conversion rates which are optimum for the production of the chemicals demanded by todays industry. The insulating effect of the coke deposits makes it necessary to operate the furnace and the tube metal at higher temperatures in order to obtain the desired cracking temperatures in the gas phase. Such higher temperatures cause more rapid deterioration of the heating coils or make necessary the use, if available, of more heat resistant and more expensive metals in such coils.
Aside from subjecting the feed stocks to the abovementioned high temperatures, it is critically important to maintain high throughput rates in order to minimize the time during which the hydrocarbons are subjected to these temperatures. It is equally important in many cases to maintain relatively low pressures, i.e. pressures just high enough to insure a rapid throughput rate, it being highly desirable to crack the hydrocarbon feed at a pressure approaching atmospheric. Accordingly, the pressure drop across the furnace, i.e. from the feed inlet to the product outlet, should be minimum.
It is clear, therefore, that coke build-up eventually requires carrying out a carbon removal cycle. Many procedures for the removal of such coke deposits have been proposed such as opening tube ends and drilling or grinding the coke deposits, treating the deposits with boiling water followed by steaming and blowing with air while applying heat externally of the tubes. Chemical processes have also been suggested as where the coke deposit is first impregnated with sulfuric acid and thereafter subjected to the action of an alkali carbonate solution to generate carbon dioxide gas Within the interstices of the coke deposits and by expansion of the generated gas, causing spalling of the deposits adhering to the walls of the cracking coils or tubes. It has also been proposed to add materials su-ch as potassium carbonate to the reaction mixture in order to reduce or remove coke deposits on thermal cracking coils.
Most of the methods previously employed or suggested have required that the normal function of the furnace and the coils or tubes for cracking of hydrocarbon materials be interrupted during the cleaning or coke removal operation. Such interruption of on-strearn time of the cracking coil produces serious economic problems in view of the temperatures involved and the time required to take the unit off-stream, effect the necessary removal of the coke deposits, and again bring the unit on-stream. Normal decoking of the furnace tubes often requires a feed outage of one to three days or even longer. In addition, the
cycling of bringing furnaces on and olf increases the wear of structural members, particularly tube supports.
It is the object of this invention to provide an improved process for thermal cracking hydrocarbon feed stocks in the presence of steam.
lt is a further object of this invention to provide an improved process for thermal cracking of hydrocarbon feed stocks in the presence of steam wherein coke deposits are removed without shutting down the cracking furnace and with only a minor reduction in production throughput of the system.
These and other objects will appear more clearly from the detailed specification and claims which follow.
It has now been found that coke deposits can be effectively removed from cracking furnace tubes by introducing steam and/or water at the inlet to one pass or tube of the cracking furnace while simultaneously reducing or eliminating normal hydrocarbon feed to that Pass. The remaining passes or tubes of the cracking furnace remain in normal service. It should be understood that it is within the scope of this invention to decoke more than one tube at a time, simultaneously or successively, so long as the total number of tubes out of service at any given time represents only a minor proportion of the total number of tubes in the cracking furnace. The quantities of steam and/or water are predetermined to meet the following criteria.
Sufcient steam and/or water are introduced to remove the Aheat normally going to the process fluid without exceeding the tube metal temperature allowances as determined by stress or oxidation limits for the tube material.
The temperature of the steam entering the section of the furnace to -be decoked must be about 700 F. or higher. lf water in introduced it must be vaporized and superheated to this temperature while steam must be merely superheated.
The mass rate of steam entering the section of the furnace to be decoked should preferably be greater than pounds per second per square foot of tube internal cross-sectional area when the tube outlet pressure is of the order of -25 p.s.i.a. Higher mass rates at constant Itemperature reduce the time required for decoking. Higher operating pressures in the furnace tubes being decoked require higher mass rates of steam for the same decoking time.
After a sufficient period of time the supply of steam and/ or water for decoking can be cut off from the decoked pass of the furnace and feed simultaneously reintroduced. With reasonably optimum steam mass rates and temperatures, a furnace pass may be decoked in l2 hours or less. After decoking of one pass of the furnace is complete, the same procedure may be used at any time deemed desirable to decoke additional passes, one at a time. As noted above, if so desired, two or more passes in a multipass furnace can be decoked in this manner simultaneously, but this does tend to detract from the major advantage of this scheme, namely, minimum upset to normal operation.
This invention may be more fully understood from the following idescription when read in conjunction with the accompanying drawing wherein the flow path of the reactants through an apparatus for thermal cracking of hydrocarbon is illustrated diagrammatically.
Referring to the drawing, the cracking furnace 10 comprises an upper, convection or preheat section 11 and a lower, cracking zone 12. Burners 13 are provided on the side walls and/or on the bottom of the furnace to supply heat. The number of burners provided is dependent upon the heat require-d and may vary considerably.
Although not shown in detail in the drawing, the furnace contains several conduits or passes in parallel. Each pass may contain a number of connected tubular members or tubes that provide a flow path through the convection section and into the cracking section. ln the drawing, one pass is shown, with the tubes in the convection section 11 designated by the numeral 15 and the cracking coils or tubes in the cracking zone 12 designated by the numeral 16. It is to `be understood that the number of conduits or tubes in the furnace is a function of the size of the furnace and is dictated solely by design considerations.
Hydrocarbon feed stock is supplied to the steam cracker via supply conduit 20 and manifold or distributor conduit 21 to the several parallel cracking conduits or passes. A control valve 22 is provided on each conduit 23 connecting the feed distributor 21 to each of the cracking conduits or tubes. Steam, or in the decoking operation, steam and/or water are supplied Kthrough inlet line 24 and valve 25 to the conduit 23. (In some cases, steam and water are supplied through separate lines and not necessarily at the identical point in the convection section.)
The reaction products are discharged from the coils or tubes 16 of the cracking furnace via conduits 26 into conduit or header 27 from which they are discharged into conduit 2S. In order to stop the cracking reaction promptly and thereby prevent or minimize side reactions, quenching agents such as higher boiling hydrocarbons and/or water are supplied through conduit 29 and control valve 30. The mixture of quenched reaction products and quenching agent is discharged via conduit 23 into fractionating tower 31. Aromatic tar product is withdrawn from the bottom of fractionating tower 31 through line 32 and product is taken overhead via line 33. Other intermediate boiling range fractions may be withdrawn as product or recycled to a higher plate in the fractionating tower as one or more reflux streams. The quench oil may be withdrawn from the fractionating tower 31 through line 34 and passed through heat exchanger 35 where it is passed in indirect heat exchange relation to the hydrocarbon feed stock for preheat thereof or to water for steam formation while cooling the quench oil to a suitable temperature for discharge through line 29 and valve 30 into the reaction product stream in line 28 as described above.
The on-stream decoking procedure requires the closing of one of the hydrocarbon feed valves 22 and the opening of the steam water valve 25. The amount of steam and Water passed through the decoking conduit 24 is adjusted so that the steam temperature inside the pass is about 700 F. or higher at the point of transition from convection tubes 15 to cracking tubes 16. When sufficient time has elapsed to allow the coke to be removed from the inside of the tubes, valve 25 is closed and valve 22 is opened. There are two indications that help show the progress of the coke removal:
Decrease in pressure drop. Decrease in tube metal temperature.
As a specific example of an operation according to the present invention, a steam cracking furnace containing ten passes or conduits was decoked by slowly backing out the hydrocarbon feed to one pass at a time while adding boiler feed water and adjusting normal steam flow. Three tests were carried out by varying the quantities of steam, water and time of decoking, and a fourth test was made with constant Water and steam rates in one `pass until a furnace shutdown some twenty hours later. On completion of the several tests, the furnace was shut down and the tubes were then removed from the furnace for examination. The following are summaries of the tests which were carried out and the condition of the tubes on examination after the furnace was shut down.
In the following tables C.O.T.=Coil outlet temperature. Crossover temp.='l`emperature at point of transition from convection tubes 15 to cracker tubes 16.
T.I..- Temperature indicator.
Test No. 1
Feed to pass 8 backed out over a 2-hour period. When steady conditions were reached, feed was returned to the pass D 6 801 nu 7 8 9 2 5 0 ew mu Is o 00000 0 0 o o 0 0 400 0 W 55777 7 7 7 7 9 9 504 8 um 1 66990 9 9 9 9 2 2 722 n u om. FM n 11 1 232 2 rl.
W m Y W 5 55506 0 u 4. 4 0 0 0 000000 0 Fh 1111 11 .11 1m 11 11 1 1 11 21 2222MM 2 mem m mm e l 1. n P 24 I o T m o wn o o Wr' 0 n 2 n n 17 n wh 31 t u 21 21 112 F e 1 u um D o d d 505 5 HF @www n 11e s vn 2221 n n n 65H1 6 1 1 0 U 1.1111111111 mp rm Ce T 53758558045 o 5577 5 1. 00009 9 O00 1 8056 444.43%3Mww444 4. 34u34". 4 1 T1. LLLLLLLLLLL 1 1 1 1 1 1 ,1 1111 1 OF Time Steady Conditions Feed Returned to Pass-End or Testl om. 1B
rge areas of Pass 8 completely free of coke were found upon examination of down. Remaining areas had coke deposits oi average thick- 8" (micrometer readings). Pass N o. 9 was used as a reference, Le. was not decoked oke deposit throughout its length having an average thickness .248' (micrometer was found when examined after shutdown. Pass was typical of ell passes not Test No. 2
Feed to pass 7 backed out using a steam-water mixture over e. Ai-minute period. This condition was held for one hour and the feed again returned to the pass 1 Feed on manual.
2 Feed out.
Norm-Large areas of the tube of Pass No. 7 were completely free o coke. Remaining areas had coke deposits of average thickness .088' (micrometer readings).
Test No. 3
Feed to pass 6 was backed out using After a further 30 minutes the steam a steam/Water mixture over a period of minutes. flow was reduced for a 10 second period to induce thermal shock in the tube. rlhis was repeated 5 minutes later. Feed was again returned to Nora-Large tube areas of Pass No. 6 were found to be completely free of coke when examined alter the furnace shutdown. Remaining areas had coke deposits of average thickness .OSS' (micrometer readings).
Test No. 4
Feed to pass 5 was backed out very quickly using a stearn/ water mixture. This condition was maintained until the furnace shutdown some hours later. Examination of the tube of pass No. 5 found it to be completely free or all coke throughout its length These tests provide quite conclusively that:
(a) Removal of coke was found to be related to the time length of decoking (Tests Nos. l, 2, 3 and 4).
(b) Complete removal of coke was possible in twenty hours (Test No. 4).
(c) It is perfectly in order to continue to run a steam cracking furnace with one pass having a steam/ water mixture only as the feed. There was no upset on the remaining nine parallel passes while one of the ten passes was being decoked.
It was further observed that there was no upset on any other equipment downstream of the cracking furnace during any of the above tests.
This invention is not to be limited by the illustration or examples since numerous variations are possible without departing from the scope of the appended claims.
What is claimed is:
1. In a process for thermally cracking hydrocarbon materials by passing the same in admixture with steam through a multiplicity of tubes arranged in parallel in a cracking furnace wherein said tubes are subjected to radiant heat sufficient to raise the temperature of the reactants within the tubes to about 1200-l600 F., the improvement which comprises taking a minor portion of said tubes off-stream by cutting out the flow of hydrocarbon feed and passing a deeoking feed selected from the group consisting of steam, water, and mixtures thereof through said tubes in sufficient amount to maintain the temperature within said tubes at essentially the same level as in the parallel tubes remaining on-stream and effect removal of coke accumulated on the interior of the off-stream tubes and thereafter returning said tubes to normal on-stream operation.
2. The process as defined in claim 1 wherein the feed is cut off and the decoking feed is supplied to only one of said parallel tubes at a time in order to remove coke therefrom without substantially reducing the conversion capacity of the cracking furnace as a whole.
3. The process as defined in claim 1 wherein the hydrocarbon feed is cut off and the decoking feed is supplied to several of said parallel tubes in succession, the total number of said tubes which are off-stream at any particular time representing only a minor portion of the total number of tubes in the cracking furnace.
4. In a process for thermally cracking hydrocarbon materials by passing the same in admixture with steam through a multiplicity of tubes arranged in parallel wherein said tubes are heated to an intermediate temperature in a convection section by contact with hot combustion gases and then subjected to radiant heat sufficient to raise the temperature of the reactants within the tubes to about 1200 to l600 F., the improvement which comprises taking a minor portion of said tubes at a given time off-stream by cutting out the flow of hydrocarbon feed and passing a decoking feed selected from the group consisting of steam, water, and mixtures thereof through said off-stream tubes in suicient amount to maintain the temperature of the steam within said off-stream tubes at essentially the same level as the reactants within the parallel tubes remaining on-stream in the radiant heating section, continuing the supply of the dccoking feed through said off-stream tubes for a period sucient to effect removal of coke from the interior of the off-stream tubes and thereafter returning said tubes to normal on-stream operation.
5. The process as defined in claim 4 wherein the temperature of the steam in the off-stream tubes is at least about 7200 F. as it passes from the portion of said tubes in the convection section into the portion in the radiant heating section.
6. The process as defined in claim 4 wherein the temperature of the steam in the off-stream tubes is at least about 700 F. as it passes from the portion of said tubes in the convection section into the portion in the radiant heating section, the mass rate of steam entering the section of the tube to be decoked being greater than l5 pounds per second per square foot of tube internal cross-sectional area when the tube outlet pressure is of the order of 20-25 p.s.i.a.
7. The process as defined in claim 4 wherein only one of said parallel tubes is taken off-stream at a time in order to remove coke therefrom without substantially reducing the conversion capacity of the cracking furnace as a whole, and the temperature of the steam in the off-stream tube is at least about 700 F. as it passes from the portion of said off-stream tube in the convection section into the portion of said off-stream tube in the radiant heating section.
8. The process as defined in claim 4 wherein only one of said parallel tubes is taken off-stream at a time in order to remove coke therefrom without substantially reducing the conversion capacity of the cracking furnace as a whole,
9 10 and the temperature ofthe steam in the oi-stream tube is References Cited at least abOllt 70%; F. at it paSSGS from the POIOII 0f UNITED STATES pATENTS said off-stream tu e in the convection section into the portion of said off-stream tube in the radiant heating sec- 2076847 4/1937 Jqhnston 20848 tion, the mass rate of steam entering the section of the 5 2289351 7/1'942 Dlxon et al' 208-48 tube to be decoked being greater than 15 pounds per sec- 2,3 72186 3/1945 Chapey 2%132 0nd per square foot of tube internal cross-sectional area 3268435 8/196'6 scum 208-48 when the tube outlet pressure is of the order of 20 25 P s i a HERBERT LEVINE, Primary Examiner.
US546277A 1966-04-29 1966-04-29 Off-stream decoking of a minor portion of on-stream thermal cracking tubes Expired - Lifetime US3365387A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
US546277A US3365387A (en) 1966-04-29 1966-04-29 Off-stream decoking of a minor portion of on-stream thermal cracking tubes
GB38710/66A GB1117562A (en) 1966-04-29 1966-08-30 Thermal cracking process
NO164749A NO138287C (en) 1966-04-29 1966-09-15 PROCEDURE FOR THERMAL STEAM CRACKING OF HYDROCARBON MATERIALS
IL26518A IL26518A (en) 1966-04-29 1966-09-18 Thermal cracking process with improved decoking
BE687073D BE687073A (en) 1966-04-29 1966-09-19
NL666613309A NL146871B (en) 1966-04-29 1966-09-21 PROCEDURE FOR THE CONTINUOUS THERMAL CRACKING OF HYDROCARBONS.
FR77382A FR1501836A (en) 1966-04-29 1966-09-23 Thermal cracking process with decoking of cracking furnace tubes
DE1568469A DE1568469C3 (en) 1966-04-29 1966-09-28 Process for thermal steam cracking of hydrocarbons
AT918066A AT276600B (en) 1966-04-29 1966-09-30 Process for removing coke deposited in the thermal cracking of hydrocarbons
DK515466AA DK116434B (en) 1966-04-29 1966-10-05 Process for thermal cracking of hydrocarbon products.
ES0331979A ES331979A1 (en) 1966-04-29 1966-10-06 A procedure to terminally craquize hydrocarbon materials. (Machine-translation by Google Translate, not legally binding)
SE13692/66A SE353077B (en) 1966-04-29 1966-10-10

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BE (1) BE687073A (en)
DE (1) DE1568469C3 (en)
DK (1) DK116434B (en)
ES (1) ES331979A1 (en)
FR (1) FR1501836A (en)
GB (1) GB1117562A (en)
IL (1) IL26518A (en)
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US3433731A (en) * 1967-03-01 1969-03-18 Monsanto Co Coil decoking in steam cracking by intermittent switch to ethane feed
DE2028913A1 (en) * 1969-07-28 1971-02-11 Esso Research and Engineering Co Linden, NJ (V StA) Process for the thermal cracking of hydrocarbons
DE2026319A1 (en) * 1970-05-29 1972-01-13 Esso Research And Engineering Co., Linden, N.J. (V.Sta.) Cracking petroleum-steam mixture - with addn of phosphorus or bismuth cpd to suppress coking and carbon monoxide formation
US4046869A (en) * 1976-02-11 1977-09-06 Texaco Inc. Steam reforming process
EP0021167A1 (en) * 1979-06-08 1981-01-07 Linde Aktiengesellschaft Process and apparatus for the thermal decoking of an apparatus for the thermal cracking of hydrocarbons such apparatus comprising a cracking zone followed by a cooler for the product gas
EP0143486A2 (en) * 1983-10-31 1985-06-05 Union Carbide Corporation Method for on-line decoking of flame cracking reactors
US4828681A (en) * 1984-12-24 1989-05-09 Exxon Research & Engineering Company Process of thermally cracking hydrocarbons using particulate solids as heat carrier
US4917787A (en) * 1983-10-31 1990-04-17 Union Carbide Chemicals And Plastics Company Inc. Method for on-line decoking of flame cracking reactors
US5078857A (en) * 1988-09-13 1992-01-07 Melton M Shannon Delayed coking and heater therefor
US5186815A (en) * 1989-04-14 1993-02-16 Procedes Petroliers Et Petrochimiques Method of decoking an installation for steam cracking hydrocarbons, and a corresponding steam-cracking installation
US5190634A (en) * 1988-12-02 1993-03-02 Lummus Crest Inc. Inhibition of coke formation during vaporization of heavy hydrocarbons
US5906728A (en) * 1996-08-23 1999-05-25 Exxon Chemical Patents Inc. Process for increased olefin yields from heavy feedstocks
US6179993B1 (en) 1996-02-23 2001-01-30 Exxon Chemical Patents Inc. Process for obtaining olefins from residual feedstocks
US6406613B1 (en) 1999-11-12 2002-06-18 Exxonmobil Research And Engineering Co. Mitigation of coke deposits in refinery reactor units
US6585883B1 (en) 1999-11-12 2003-07-01 Exxonmobil Research And Engineering Company Mitigation and gasification of coke deposits
US6852294B2 (en) 2001-06-01 2005-02-08 Conocophillips Company Alternate coke furnace tube arrangement
US20050038304A1 (en) * 2003-08-15 2005-02-17 Van Egmond Cor F. Integrating a methanol to olefin reaction system with a steam cracking system
US20060188417A1 (en) * 2005-02-23 2006-08-24 Roth James R Radiant tubes arrangement in low NOx furnace
US20090152172A1 (en) * 2006-05-10 2009-06-18 United Technologies Corporation In-situ continuous coke deposit removal by catalytic steam gasification
US20100006478A1 (en) * 2008-07-11 2010-01-14 Spicer David B Process for the On-Stream Decoking of a Furnace for Cracking a Hydrocarbon Feed
WO2010077461A1 (en) 2009-01-05 2010-07-08 Exxonmobil Chemical Patents Inc. Process for cracking a heavy hydrocarbon feedstream
US20100191031A1 (en) * 2009-01-26 2010-07-29 Kandasamy Meenakshi Sundaram Adiabatic reactor to produce olefins
US20100252072A1 (en) * 2009-04-06 2010-10-07 Synfuels International, Inc. Secondary reaction quench device and method of use
WO2013093640A2 (en) 2011-12-21 2013-06-27 Hyl Technologies, S.A. De C.V. Method and apparatus for production of direct reduced iron (dri) utilizing coke oven gas
US20130239999A1 (en) * 2011-09-13 2013-09-19 Vasant Lotu Bhirud Ethylene Furnace Decoking Method
WO2014005998A1 (en) 2012-07-05 2014-01-09 Shell Internationale Research Maatschappij B.V. Integrated process for the preparation of olefins
EP3040325A1 (en) 2014-12-31 2016-07-06 Shell Internationale Research Maatschappij B.V. Process for preparing ethylene, propylene and isoprene
WO2020159719A1 (en) 2019-01-30 2020-08-06 Exxonmobil Chemical Patents Inc. Process and system for processing asphaltenes-rich feed
US20210222073A1 (en) * 2018-06-12 2021-07-22 Sabic Global Technologies B.V. Naphtha splitter integration with hncc technology
US11072749B2 (en) 2019-03-25 2021-07-27 Exxonmobil Chemical Patents Inc. Process and system for processing petroleum feed
WO2021230917A2 (en) 2019-12-30 2021-11-18 Exxonmobil Chemical Patents Inc. Hydrocarbon pyrolysis with less exhaust emission
WO2022155035A1 (en) 2021-01-18 2022-07-21 Exxonmobil Chemical Patents Inc. Methods and systems for cracking hydrocarbons
WO2023114623A1 (en) 2021-12-16 2023-06-22 Exxonmobil Chemical Patents Inc. Duty recovery system and process for steam cracking furnace
WO2023114633A1 (en) 2021-12-16 2023-06-22 Exxonmobil Chemical Patents Inc. Steam cracking furnace and process
US11807820B2 (en) 2019-03-20 2023-11-07 Exxonmobil Chemical Patents Inc. Processes for on-stream decoking
US11932816B2 (en) 2019-02-15 2024-03-19 Exxonmobil Chemical Patents Inc. Coke and tar removal from a furnace effluent

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EP0986621B1 (en) 1997-06-05 2002-11-27 ATF Resources, Inc. Method and apparatus for removing and suppressing coke formation during pyrolysis
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Cited By (56)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3433731A (en) * 1967-03-01 1969-03-18 Monsanto Co Coil decoking in steam cracking by intermittent switch to ethane feed
DE2028913A1 (en) * 1969-07-28 1971-02-11 Esso Research and Engineering Co Linden, NJ (V StA) Process for the thermal cracking of hydrocarbons
DE2026319A1 (en) * 1970-05-29 1972-01-13 Esso Research And Engineering Co., Linden, N.J. (V.Sta.) Cracking petroleum-steam mixture - with addn of phosphorus or bismuth cpd to suppress coking and carbon monoxide formation
US4046869A (en) * 1976-02-11 1977-09-06 Texaco Inc. Steam reforming process
EP0021167A1 (en) * 1979-06-08 1981-01-07 Linde Aktiengesellschaft Process and apparatus for the thermal decoking of an apparatus for the thermal cracking of hydrocarbons such apparatus comprising a cracking zone followed by a cooler for the product gas
US4376694A (en) * 1979-06-08 1983-03-15 Linde Aktiengesellschaft Method of decoking a cracking plant
EP0143486A2 (en) * 1983-10-31 1985-06-05 Union Carbide Corporation Method for on-line decoking of flame cracking reactors
EP0143486A3 (en) * 1983-10-31 1986-04-16 Union Carbide Corporation Method for on-line decoking of flame cracking reactors
US4917787A (en) * 1983-10-31 1990-04-17 Union Carbide Chemicals And Plastics Company Inc. Method for on-line decoking of flame cracking reactors
US4828681A (en) * 1984-12-24 1989-05-09 Exxon Research & Engineering Company Process of thermally cracking hydrocarbons using particulate solids as heat carrier
US5078857A (en) * 1988-09-13 1992-01-07 Melton M Shannon Delayed coking and heater therefor
US5190634A (en) * 1988-12-02 1993-03-02 Lummus Crest Inc. Inhibition of coke formation during vaporization of heavy hydrocarbons
US5186815A (en) * 1989-04-14 1993-02-16 Procedes Petroliers Et Petrochimiques Method of decoking an installation for steam cracking hydrocarbons, and a corresponding steam-cracking installation
US6179993B1 (en) 1996-02-23 2001-01-30 Exxon Chemical Patents Inc. Process for obtaining olefins from residual feedstocks
US5906728A (en) * 1996-08-23 1999-05-25 Exxon Chemical Patents Inc. Process for increased olefin yields from heavy feedstocks
US6585883B1 (en) 1999-11-12 2003-07-01 Exxonmobil Research And Engineering Company Mitigation and gasification of coke deposits
US6406613B1 (en) 1999-11-12 2002-06-18 Exxonmobil Research And Engineering Co. Mitigation of coke deposits in refinery reactor units
US6852294B2 (en) 2001-06-01 2005-02-08 Conocophillips Company Alternate coke furnace tube arrangement
US20050098477A1 (en) * 2001-06-01 2005-05-12 Doerksen Brian J. Alternate coke furnace tube arrangement
US7524411B2 (en) 2001-06-01 2009-04-28 Conocophillips Company Alternate coke furnace tube arrangement
US20050038304A1 (en) * 2003-08-15 2005-02-17 Van Egmond Cor F. Integrating a methanol to olefin reaction system with a steam cracking system
US20060188417A1 (en) * 2005-02-23 2006-08-24 Roth James R Radiant tubes arrangement in low NOx furnace
US20090152172A1 (en) * 2006-05-10 2009-06-18 United Technologies Corporation In-situ continuous coke deposit removal by catalytic steam gasification
US7883674B2 (en) * 2006-05-10 2011-02-08 United Technologies Corporation In-situ continuous coke deposit removal by catalytic steam gasification
WO2010005633A1 (en) * 2008-07-11 2010-01-14 Exxonmobil Chemical Patents Inc. Process for the on-stream decoking of a furnace for cracking a hydrocarbon feed
CN102083944B (en) * 2008-07-11 2016-05-04 埃克森美孚化学专利公司 The method of the on-stream decoking of the stove of cracking hydrocarbon feed
US20100006478A1 (en) * 2008-07-11 2010-01-14 Spicer David B Process for the On-Stream Decoking of a Furnace for Cracking a Hydrocarbon Feed
CN102083944A (en) * 2008-07-11 2011-06-01 埃克森美孚化学专利公司 Process for the on-stream decoking of a furnace for cracking a hydrocarbon feed
US8864977B2 (en) 2008-07-11 2014-10-21 Exxonmobil Chemical Patents Inc. Process for the on-stream decoking of a furnace for cracking a hydrocarbon feed
WO2010077461A1 (en) 2009-01-05 2010-07-08 Exxonmobil Chemical Patents Inc. Process for cracking a heavy hydrocarbon feedstream
US20100174130A1 (en) * 2009-01-05 2010-07-08 Spicer David B Process for Cracking a Heavy Hydrocarbon Feedstream
US8684384B2 (en) 2009-01-05 2014-04-01 Exxonmobil Chemical Patents Inc. Process for cracking a heavy hydrocarbon feedstream
US20100191031A1 (en) * 2009-01-26 2010-07-29 Kandasamy Meenakshi Sundaram Adiabatic reactor to produce olefins
US8815080B2 (en) * 2009-01-26 2014-08-26 Lummus Technology Inc. Adiabatic reactor to produce olefins
US20100252072A1 (en) * 2009-04-06 2010-10-07 Synfuels International, Inc. Secondary reaction quench device and method of use
US8434505B2 (en) 2009-04-06 2013-05-07 Synfuels International, Inc. Secondary reaction quench device and method of use
US8137476B2 (en) 2009-04-06 2012-03-20 Synfuels International, Inc. Secondary reaction quench device and method of use
US20130239999A1 (en) * 2011-09-13 2013-09-19 Vasant Lotu Bhirud Ethylene Furnace Decoking Method
US9127211B2 (en) * 2011-09-13 2015-09-08 Sbt Technology, Inc. Ethylene furnace decoking method
WO2013093640A3 (en) * 2011-12-21 2013-12-27 Hyl Technologies, S.A. De C.V. Method and apparatus for production of direct reduced iron (dri) utilizing coke oven gas
CN104245963A (en) * 2011-12-21 2014-12-24 伊尔技术有限公司 Method and apparatus for production of direct reduced iron (dri) utilizing coke oven gas
WO2013093640A2 (en) 2011-12-21 2013-06-27 Hyl Technologies, S.A. De C.V. Method and apparatus for production of direct reduced iron (dri) utilizing coke oven gas
CN104245963B (en) * 2011-12-21 2016-11-16 伊尔技术有限公司 Utilize the method and apparatus that oven gas prepares DRI (DRI)
US9725778B2 (en) 2011-12-21 2017-08-08 Hyl Technologies, S.A. De C.V. Method and apparatus for production of direct reduced iron (DRI) utilizing coke oven gas
WO2014005998A1 (en) 2012-07-05 2014-01-09 Shell Internationale Research Maatschappij B.V. Integrated process for the preparation of olefins
US9732011B2 (en) 2012-07-05 2017-08-15 Shell Oil Company Integrated process for the preparation of olefins
EP3040325A1 (en) 2014-12-31 2016-07-06 Shell Internationale Research Maatschappij B.V. Process for preparing ethylene, propylene and isoprene
US20210222073A1 (en) * 2018-06-12 2021-07-22 Sabic Global Technologies B.V. Naphtha splitter integration with hncc technology
WO2020159719A1 (en) 2019-01-30 2020-08-06 Exxonmobil Chemical Patents Inc. Process and system for processing asphaltenes-rich feed
US11932816B2 (en) 2019-02-15 2024-03-19 Exxonmobil Chemical Patents Inc. Coke and tar removal from a furnace effluent
US11807820B2 (en) 2019-03-20 2023-11-07 Exxonmobil Chemical Patents Inc. Processes for on-stream decoking
US11072749B2 (en) 2019-03-25 2021-07-27 Exxonmobil Chemical Patents Inc. Process and system for processing petroleum feed
WO2021230917A2 (en) 2019-12-30 2021-11-18 Exxonmobil Chemical Patents Inc. Hydrocarbon pyrolysis with less exhaust emission
WO2022155035A1 (en) 2021-01-18 2022-07-21 Exxonmobil Chemical Patents Inc. Methods and systems for cracking hydrocarbons
WO2023114623A1 (en) 2021-12-16 2023-06-22 Exxonmobil Chemical Patents Inc. Duty recovery system and process for steam cracking furnace
WO2023114633A1 (en) 2021-12-16 2023-06-22 Exxonmobil Chemical Patents Inc. Steam cracking furnace and process

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ES331979A1 (en) 1967-07-16
NO138287C (en) 1978-08-09
AT276600B (en) 1969-11-25
DK116434B (en) 1970-01-12
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DE1568469C3 (en) 1982-09-16
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NL146871B (en) 1975-08-15
NO138287B (en) 1978-05-02
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DE1568469B2 (en) 1977-03-10
NL6613309A (en) 1967-10-30
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SE353077B (en) 1973-01-22
DE1568469A1 (en) 1972-02-24

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