CA2152336A1 - Method for saving energy in a thermal cracking process - Google Patents
Method for saving energy in a thermal cracking processInfo
- Publication number
- CA2152336A1 CA2152336A1 CA002152336A CA2152336A CA2152336A1 CA 2152336 A1 CA2152336 A1 CA 2152336A1 CA 002152336 A CA002152336 A CA 002152336A CA 2152336 A CA2152336 A CA 2152336A CA 2152336 A1 CA2152336 A1 CA 2152336A1
- Authority
- CA
- Canada
- Prior art keywords
- cracking
- compound
- recited
- tin
- composition
- 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.)
- Abandoned
Links
Classifications
-
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
Abstract
The energy required to achieve a given conversion in the thermal cracking of hydrocarbons is reduced by contacting or treating the tubes of a thermal cracking furnace with a composition comprising tin and silicon.
Description
- 2152~36 33277CA
METHOD FOR SAVING ENERGY IN A THERMAL
CRACKING PROCESS
The present invention generally relates to processes for the therm~l cracking of hydrocarbons and, specifically, to a method for saving energy in the thermal cracking of hydrocarbons.
In a process for producing an olefin compound, a fluid stream 5 containing a saturated hydrocarbon such as ethane, propane, butane, pentane, naphtha, or mi2~ es of two or more thereof is fed into a thermal (or pyrolytic) cracking furnace. A diluent fluid such as steam is usually combined with the hydrocarbon feed material being introduced into the cracking furnace.
Within the furnace, the saturated hydrocarbon is converted into an 10 olefinic compound. For example, an ethane stream introduced into the cracking furnace is converted into ethylene and appreciable amounts of other hydrocarbons.
A propane stream introduced into the furnace is converted to ethylene and propylene, and appreciable amounts of other hydrocarbons. Similarly, a mixture 2152~36 33277CA
of saturated hydrocarbons co~ g ethane, propane, butane, pentane and naphtha is convelled to a mi~lu.e of olefinic compounds co~ g ethylene, propylene, butenes, pentenes, and naphthalene. Olefinic compounds are an important class of industrial chemicals. For example, ethylene is a monomer or 5 comonomer for m~king polyethylene and other polymers. Other uses of olefinic compounds are well known to those skilled in the art.
As a result of the thermal cracking of a hydrocarbon, the cracked product stream can also contain appreciable quantities of hydrogen, methane, acetylene, carbon monoxide, carbon dioxide, and pyrolytic products other than the 10 olefinic compounds.
The process for thermally or pyrolytically cracking saturated hydrocarbons to an olefin end-product is highly energy intensive. Typically, 70 to 95 percent of the total energy cost- of operating a cracking process unit or olefins plant is fuel consumed in the cracking furnaces of such cracking process 15 unit. Generally, depending upon the molecular weight of the feedstock and the desired feed conversion, the energy consumption per pound of olefin produced by a cracking process unit can range from about 7000 Btu per pound olefin produced upwardly to about 15,000 Btu per pound olefin produced. Typical olefin plants have annual olefin production capacities ranging upwardly to one billion pounds 20 and, in some instances, more than one billion pounds. Thus, the energy requirements for operating an olefins plant constitute a major element in the cost 21~36 33277CA
of operating and producing cracked olefins. Because the fuel requirements for operating a cracking furnace are so large, even a small increment~l improvement in the energy requirements to produce an olefin end-product can result in large cost savings in the per unit production cost of the olefins.
It is thus an object of this invention to provide an improved process for cracking saturated hydrocarbons to produce olefinic end-products.
Another object of this invention is to provide a method for improving the energy eff1ciency of a cracking process without loss of product yield.
A still further object of this invention is to provide a method of reducing the required cracking temperature to crack a hydrocarbon feed stream without a loss in the percent conversion of the hydrocarbon feed stream to olefin end-product.
In accordance with one embodiment of the invention, the tubes of a pyrolytic cracking furnace are treated with a composition Co~ g a tin compound and a silicon compound to provide treated tubes. The treated tubes are utilized in the cracking of hydrocarbons under cracking conditions. Due to the use of the treated tubes, the cracking temperature that provides for a given feed conversion is below the cracking temperature required to achieve the given feed conversion when untreated tubes of a pyrolytic cracking furnace are used.
215~336 33277CA
Another embodiment of the invention includes a method of reducing a required cracking temperature for a given feed conversion in the operation of a cracking film~ce of a tllerm~l cracking process for cracking a hydrocarbon stream.
The cracking furnace is equipped with a cracking tube having a surface. The 5 method includes contacting the surface of the cracking tube with a composition comprising a tin compound and a silicon compound so as to provide a treated cracking tube. A hydrocarbon feed stream is charged to the treated cracking tube, which is m~int~ined at a temperature so as to provide a cracking temperature below that required for the given feed conversion when the u~ al~d cracking tube 10 is used.
A final embodiment of the invention includes a method of reducing energy consumption for a given feed conversion in the operation of a thermal cracking process for cracking a hydrocarbon stream. The method includes adding to the hydrocarbon stream in an amount effective for enhancing feed conversion 15 for a given cracking temperature a composition comprising a tin compound and a silicon compound. The enhanced feed conversion at the given cracking temperature permits the reduction of the cracking temperature. This reduction in cracking temperature results in a reduction in fuel or energy consumption.
Other objects and advantages of the invention will be apparellt from 20 the description of the invention and the appended claims thereof as well as from the detailed description of the drawing in which:
METHOD FOR SAVING ENERGY IN A THERMAL
CRACKING PROCESS
The present invention generally relates to processes for the therm~l cracking of hydrocarbons and, specifically, to a method for saving energy in the thermal cracking of hydrocarbons.
In a process for producing an olefin compound, a fluid stream 5 containing a saturated hydrocarbon such as ethane, propane, butane, pentane, naphtha, or mi2~ es of two or more thereof is fed into a thermal (or pyrolytic) cracking furnace. A diluent fluid such as steam is usually combined with the hydrocarbon feed material being introduced into the cracking furnace.
Within the furnace, the saturated hydrocarbon is converted into an 10 olefinic compound. For example, an ethane stream introduced into the cracking furnace is converted into ethylene and appreciable amounts of other hydrocarbons.
A propane stream introduced into the furnace is converted to ethylene and propylene, and appreciable amounts of other hydrocarbons. Similarly, a mixture 2152~36 33277CA
of saturated hydrocarbons co~ g ethane, propane, butane, pentane and naphtha is convelled to a mi~lu.e of olefinic compounds co~ g ethylene, propylene, butenes, pentenes, and naphthalene. Olefinic compounds are an important class of industrial chemicals. For example, ethylene is a monomer or 5 comonomer for m~king polyethylene and other polymers. Other uses of olefinic compounds are well known to those skilled in the art.
As a result of the thermal cracking of a hydrocarbon, the cracked product stream can also contain appreciable quantities of hydrogen, methane, acetylene, carbon monoxide, carbon dioxide, and pyrolytic products other than the 10 olefinic compounds.
The process for thermally or pyrolytically cracking saturated hydrocarbons to an olefin end-product is highly energy intensive. Typically, 70 to 95 percent of the total energy cost- of operating a cracking process unit or olefins plant is fuel consumed in the cracking furnaces of such cracking process 15 unit. Generally, depending upon the molecular weight of the feedstock and the desired feed conversion, the energy consumption per pound of olefin produced by a cracking process unit can range from about 7000 Btu per pound olefin produced upwardly to about 15,000 Btu per pound olefin produced. Typical olefin plants have annual olefin production capacities ranging upwardly to one billion pounds 20 and, in some instances, more than one billion pounds. Thus, the energy requirements for operating an olefins plant constitute a major element in the cost 21~36 33277CA
of operating and producing cracked olefins. Because the fuel requirements for operating a cracking furnace are so large, even a small increment~l improvement in the energy requirements to produce an olefin end-product can result in large cost savings in the per unit production cost of the olefins.
It is thus an object of this invention to provide an improved process for cracking saturated hydrocarbons to produce olefinic end-products.
Another object of this invention is to provide a method for improving the energy eff1ciency of a cracking process without loss of product yield.
A still further object of this invention is to provide a method of reducing the required cracking temperature to crack a hydrocarbon feed stream without a loss in the percent conversion of the hydrocarbon feed stream to olefin end-product.
In accordance with one embodiment of the invention, the tubes of a pyrolytic cracking furnace are treated with a composition Co~ g a tin compound and a silicon compound to provide treated tubes. The treated tubes are utilized in the cracking of hydrocarbons under cracking conditions. Due to the use of the treated tubes, the cracking temperature that provides for a given feed conversion is below the cracking temperature required to achieve the given feed conversion when untreated tubes of a pyrolytic cracking furnace are used.
215~336 33277CA
Another embodiment of the invention includes a method of reducing a required cracking temperature for a given feed conversion in the operation of a cracking film~ce of a tllerm~l cracking process for cracking a hydrocarbon stream.
The cracking furnace is equipped with a cracking tube having a surface. The 5 method includes contacting the surface of the cracking tube with a composition comprising a tin compound and a silicon compound so as to provide a treated cracking tube. A hydrocarbon feed stream is charged to the treated cracking tube, which is m~int~ined at a temperature so as to provide a cracking temperature below that required for the given feed conversion when the u~ al~d cracking tube 10 is used.
A final embodiment of the invention includes a method of reducing energy consumption for a given feed conversion in the operation of a thermal cracking process for cracking a hydrocarbon stream. The method includes adding to the hydrocarbon stream in an amount effective for enhancing feed conversion 15 for a given cracking temperature a composition comprising a tin compound and a silicon compound. The enhanced feed conversion at the given cracking temperature permits the reduction of the cracking temperature. This reduction in cracking temperature results in a reduction in fuel or energy consumption.
Other objects and advantages of the invention will be apparellt from 20 the description of the invention and the appended claims thereof as well as from the detailed description of the drawing in which:
FIG. 1 is a schem~lic diagram representing the portion of an ethylene cracking process that includes pyroltyic cracking furnace means; and FIG. 2 includes plots of the cracking tube coil outlet temperatures at a substantially fixed ethane conversion for an unlleal~d cracking tube and a 5 cracking tube treated in accordance with the novel methods described herein.
The process of this invention involves the pyrolytic cracking of hydrocarbons to produce desirable hydrocarbon end-products. A hydrocarbon stream is fed or charged to pyrolytic cracking furnace means wherein the hydrocarbon stream is subjected to a severe, high-temperature ellvilol~llent to 10 produce cracked gases. The hydrocarbon stream can comprise any type of hydrocarbon that is suitable for pyrolytic cracking to olefin compounds.
Preferably, however, the hydrocarbon stream can comprise paraffin hydrocarbons selected from the group consisting of ethane, propane, butane, pentane, naphtha, and mi~ s of any two or more thereof. Naphtha can generally be described as 15 a complex hydrocarbon n~ e having a boiling range of from about 180F to about 400F as delelll~ ed by the standard testing methods of the American Society of Testing Materials (ASTM).
The pyrolytic cracking of a higher molecular weight hydrocarbons to a lower molecular weight hydrocarbons can be referred to as conversion. The 20 terms "conversion", "feed conversion", and similar such terminology, as used throughout this specification, are defined as the ratio of the difference between the 21s2336 33277CA
mass of saturated hydrocarbons charged to a cracking zone and the mass of unconverted saturated hydrocarbons leaving, as an effluent, such cracking zone divided by the mass of saturated hydrocarbons charged to the cracking zone. The numerical value for conversion can be reported as a fraction (ratio) or as a 5 percentage. Conversion can also be reported on an individual compound basis such as, for e~mple, ethane conversion, propane conversion, butane conversion, and the like.
As an optional feature of the invention, the hydrocarbon feed being charged to pyrolytic cracking furnace means can be inhm~tely mixed with a 10 diluent prior to ent~ring pyrolytic cracking furnace means. This diluent can serve several positive functions, one of which includes providing desirable reaction conditions within pyrolytic cracking furnace means for producing the desired reactant end-products. The diluent does this by providing for a lower partial pressure of hydrocarbon feed fluid thereby enhancing the cracking reactions 15 necessary for obtaining the desired olefin products while reducing the amount of undesirable reaction products such as hydrogen and methane. Also, the lower partial pressure resulting from the ~ e of the diluent fluid helps in minimi7:in~;
the amount of coke deposits that form on the furnace tubes. While any suitable diluent fluid that provides these benefits can be used, the preferred diluent fluid 20 is steam.
The cracking reactions induced by pyrolytic cracking furnace means can take place at any suitable temperature that will provide the necessary cracking to the desirable end-products or the desired feed conversion. The actual cracking temperature ~ 7e~ will depend upon the composition of the hydrocarbon feed 5 stream and the desired feed conversion. Generally, the cracking temperature can run u~w~ly to about 2000F or great er depending upon the amount of cracking or conversion desired and the molecular weight of the feedstock being cracked.
Preferably, however, the cracking temperature will be in the range of from about 1200F to about l900F. Most preferably, the cracking temperature can be in 10 the range from 1500F to l~OOF.
The cracked hydrocarbon effluent or cracked hydrocarbons or cracked hydrocarbon stream from pyrolytic cracking furnace means will generally be a mixture of hydrocarbons in the gaseous phase. This mixture of gaseous hydrocarbons can comprise not only the desirable olefin compounds, such as 15 ethylene, propylene, butylene, and amylene, but also, this cracked hydrocarbon stream can contain undesirable co"~ hng components that include both oxygenated compounds and acidic compounds and light ends such as hydrogen and methane.
The cracking furnace means of the inventive method can be any 20 suitable thermal cracking furnace known in the art. The various cracking furnaces are well known to those skilled in the art of cracking technology and the choice of a suitable cracking furnace for use in a cracking process is generally a matter of plerelellce. Such cracking furnaces, how~v~r, are equipped with at least one cracking tube to which the hydrocarbon feedstock is charged or fed. The cracking tube provides for and defines a cracking zone contained within the cracking 5 furnace. The cracking furnace is utilized to release the heat energy required to provide for the necessary cracking temperature within the cracking zone in order to induce the cracking reactions therein. Each cracking tube can have any geometry which suitably defines a volume in which cracking reactions can take place and, thus, will have an inside surface. The term "cracking temperature" as 10 used herein is defined as being the temperature within the cracking zone defined by a cracking tube. The outside wall temperature of the cracking tube can, thus, be higher than the cracking temperature and possibly substantially higher due to heat transfer considerations. Typical pressures within the cracking zone will generally be in the range of from about 5 psig to about 25 psig and, preferably 15 from 10 psig to 20 psig.
The inventive method includes the treatment or treating of the tubes of a cracking furnace by contacting the surface of such tubes with a feed conversion enhancing composition. The use of the feed conversion enhancing composition provides for or induces an increase in the conversion of the 20 hydrocarbon feedstock to a cracking furnace for a given cracking temperature.
This enhancement in feed conversion permits the reduction in the cracking 2 1S2 33 ~ 33277CA
temperature below that required to give the feed conversion which results from tili~ing untreated cracker tubes. The feed conversion enhancing composition is a combination or n~ e of tin and silicon, thus the composition will comprise, consist essentially of, or consist of tin and silicon.
Any suitable form of silicon may be utilized in the feed conversion enhancing composition comprising tin and silicon. Element~l silicon, inorganic silicon compounds and organic silicon compounds as well as ~ es of any two or more thereof are suitable sources of silicon. The term "silicon" generally refers to any one of these silicon sources.
Examples of some inorganic silicon compounds that can be used include the halides, nitrides, hydrides, oxides and sulfides of silicon, silicic acids and alkali metal salts thereof. Of the inorganic silicon compounds, those which do not contain halogen are pr~relled.
Examples of organic silicon compounds that may be used include compounds of the formula Rl-Si-R3 wherein Rl, R2, R3, and R4 are selected independently from the group consisting of hydrogen, halogen, hydrocarbyl, and oxyhydrocarbyl and wherein the compound's bonding may be either ionic or covalent. The hydrocarbyl and 215233~ 33277CA
oxyhydrocarbyl radicals can have from 1-20 carbon atoms which may be substituted with halogen, nitrogen, phosphorus, or sulfur. Exemplary hydrocarbyl radicals are aLkyl, alkenyl, cycloaLkyl, aryl, and combinations thereof, such as alkylaryl or aLkylcycloaLkyl. Exemplary oxyhydrocarbyl radicals are alkoxide, 5 phenoxide, carboxylate, ketocarboxylate and diketone (dione). Suitable organic silicon compounds include trimethylsilane, tetramethylsilane, tetraethylsilane, triethylchlorosilane, phenyltrimethylsilane, tetraphenylsilane, ethyltrimethoxysilane, propyltriethoxysilane, dodecyltrihexoxysilane, vinyltriethyoxysilane, tetramethoxyorthosilicate, tetraethoxyorthosilicate, 10 polydimethylsiloxane, polydiethylsiloxane, polydihexylsiloxane, polycyclohexylsiloxane, polydiphenylsiloxane, polyphenylmethylsiloxane, 3-chloropro~yltrimethoxysilane, and 3-aminopropyltriethoxysilane. At present hexamethyldisiloxane is preferred. Organic silicon compounds are particularly pler~ d because such compounds are soluble in the feed material and 15 in the diluents which are preferred for preparing ~relle&~ ent solutions as will be more fully described hereinafter. Also, organic silicon compounds appear to have less of a tendency towards adverse effects on the cracking process than do inorganic silicon compounds.
Any suitable form of tin may be utilized in the feed conversion 20 enhancing composition comprising tin and silicon. Elemental tin, inorganic tin compounds and organic tin compounds as well as mixtures of any two or more thereof are suitable sources of tin. The term "tin" generally refers to any one of these tin sources.
Examples of some inorganic tin compounds which can be used include tin oxides such as stannous oxide and stannic oxide; tin sulfides such as 5 stannous sulfide and stannic sulfide; tin sulfates such as stannous sulfate and stannic sulfate; stannic acids such as metastannic acid and thiostannic acid; tin halides such as stannous fluoride, stannous chloride, stannous bromide, stannous iodide, stannic fluoride, stannic chloride, st~nnic bromide and stannic iodide; tin phosphates such as stannic phosphate; tin oxyhalides such as stannous oxychloride 10 and stannic oxychloride; and the like. Of the inorganic tin compounds those which do not contain halogen are preferred as the source of tin.
Examples of some organic tin compounds which can be used include tin carboxylates such as stannous formate, stannous acetate, stannous butyrate, stannous octoate, stannous decanoate, stannous oxalate, stannous benzoate, and 15 stannous cyclohexanecarboxylate; tin thiocarboxylates such as stannous thioacetate and stannous dithioacetate; dihydrocarbyltin bis(hydrocarbyl mercaptoalkanoates) such as dibutyltin bis(isoocylmercaptoacetate) and dipropyltin bis(butyl mercaptoacetate); tin thiocarbonates such as stannous O-ethyl dithiocarbonate; tin carbonates such as stannous propyl carbonate;
20 tetrahydrocarbyltin compounds such as tetramethyltin, tetraoctyltin, tetradodecyltin, and tetraphenyltin; dihydrocarbyltin oxides such as dipropyltin 215233~ 33277CA
oxide; dibutyltin oxide, dioctyltin oxide, and diphenyltin oxide; dihydrocarbyltin bis(hydrocarbyl mercaptide)s such as dibutyltin bis(dodecyl mercaptide); tin salts of phenolic compounds such as stannous thiophenoxide; tin sulfonates such as stannous benzenesulfonate and stannous-p-toluenesulfonate; tin carbamates such as stannous diethylcarbamate; tin thiocarbamates such as stannous propylthiocarbamate and stannous diethyldithiocarbamate; tin phosphites such as stannous diphenyl phosphite; tin phosphates such as stannous dipropyl phosphate;tin thiophosphates such as stannous O,O-dipropyl thiophosphate, stannous O,O-dipropyl dithiophosphate and stannic O,O-dipropyl dithiophosphate, dihydrocarbyltin bis(O,O-dihydrocarbyl thiophosphate)s such as dibutyltin bis(O,O-dipropyl dithiophosphate); and the like. At present tetrabutyltin is preferred. Again, as with silicon, organic tin compounds are preferred over inorganic compounds. Any of the listed sources of tin may be combined with any of the listed sources of silicon to form the feed conversion enhancing composition comprising tin and silicon.
The feed conversion enhancing composition can have any molar ratio of tin to silicon which suitably provides for the cracker tube treatment or enhanced cracker feed conversion as required hereunder. Generally, however, the molar ratio of tin to silicon of the composition can be in the range of from about 1:100 to about 100:1. Preferably, the molar ratio can be from about 1:10 to about 10:1 and, most preferably, it can be from 1:4 to 4:1.
13 21S~36 The feed conversion enhancing composition is lltili7ed in the treatment of the surfaces of the cracking tubes of a cracking furnace. The composition is contacted with surfaces of the cracking tubes either by pretreating the cracking tubes with the composition prior to charging the tubes with a 5 hydrocarbon feed or by adding the composition to the hydrocarbon feed in an amount effective for t~nh~ncin~ feed conversion for a given cracking tempe,alure.
Any method can be used which suitably treats the tubes of a cracking furnace by contacting such tubes with the feed conversion enhancing composition under suitable treatment conditions to thereby provide treated tubes.
10 The treated tubes will provide for a lower required cracking temperature for a given cracker feed conversion.
The preferred procedure for pretreating the tubes of the cracking furnace, includes charging to the inlet of the cracking furnace tubes a saturated or slightly superheated steam having a temperature in the range of from about 300F
15 to about 500F. The cracking furnace is fired while charging the tubes with the steam so as to provide a superheated stearn which exits the tubes at a temperature exceeding that of the steam introduced into the inlet of the tubes. Generally, the steam effluent will have a temperature u~w~-dly to about 2000F. Thus, the treating temperature can be in the range of from about 300F to about 2000F, preferably, from about 400F to about 1800F and, most preferably, from 500F
2i5~336 33277CA
to 1600F. It is desirable for the steam to be charged to the convection section of the cracking furnace, therefore, first passing through the convection section tubes followed by passing through the radiant section tubes.
The feed conversion enhancing composition can then be ~lmixed 5 with the steam being charged to the cracker tubes. The feed conversion enhancing composition can be admixed with the steam as either a neat liquid or as a ~ e of the feed conversion enhancing composition with an inert diluent. It is plerelled, however, to first vaporize either the neat liquid or the llli~ e prior to its introduction into or ~llmixing with the steam. The amount of feed conversion 10 enhancing composition ~(lmixed with the steam can be such as to provide a concentration of the feed conversion enhancing composition in the steam in the range of from about 1 ppmw to about 10,000 ppmw, preferably, from about 10 ppmw to about 1000 ppmw and, most preferably, from 20 to 200 ppmw.
The ~l,,,;X~ of steam and feed conversion enhancing composition 15 is contacted with or charged to the cracker tubes for a period of time sufficient to provide for treated tubes, which when placed in cracking service, will require a cracking temperature for a given feed conversion below that for untreated tubes.
Such time period for pretreating the cracker tubes is influenced by the specific geometry of the cracking furnace including its tubes; but, generally, the pretreating 20 time period can range upwardly to about 12 hours, and longer if required. But, 21~233~ 33277CA
preferably, the period of time for the p~ ea~ g can be in the range of from about 0.1 hours to about 12 hours and, most preferably, from 0.5 hours to 10 hours.
In the case where the feed conversion enhancing composition is directly admixed with the hydrocarbon cracker feed, it can be added in such an 5 amount to be effective in enhancing the feed conversion above that which occurs when no feed conversion enhancing composition is added. Due to the memory effect resulting from the application of the feed conversion enhancing composition, the mixing with the hydrocarbon cracker feed is conducted int~ e~ly as required but, preferably, for periods up to about 12 hours. The 10 concentration of the feed conversion enhancing composition in the hydrocarbon cracker feed during treating of the cracker tubes can be in the range of from about 1 ppmw to about 10,000 ppmw, preferably, from about 10 ppmw to about 1000 ppmw and, most preferably, from 20 to 200 ppmw.
Now referring to FIG. 1, there is illustrated by schematic 15 representation cracking furnace section 10 of a pyrolytic cracking process system.
Cracking furnace section 10 includes pyrolytic cracking means or cracking furnace 12 for providing heat energy required for inducing the cracking of hydrocarbons.
Cracking furnace 12 defines both convection zone 14 and radiant zone 16.
Respectively within such zones are convection coils as tubes 18 and radiant coils 20 as tubes 20.
A hydrocarbon feedstock or a n~ e of steam and such hydrocarbon feedstock is conducted to the inlet of convection tubes 18 by way ofconduit 22 which is in fluid flow coll"llullication with convection tubes 18.
During the treatment of the tubes of cracking furnace 12, the a-lmi~lre of steamand the feed conversion enhancing composition can also be conducted to the inletof convection tubes 18 through conduit 22. The feed passes through the tubes of cracking furnace 12 wherein it is heated to a cracking temperature in order to induce cracking or, in the situation where the tubes are undergoing treatment, to the required treatment temperature. The effluent from cracking furnace 12 passesdownstream through conduit 24. To provide for the heat energy necessary to operate cracking furnace 12, fuel gas is conveyed through conduit 26 to burners 28 of cracking furnace 12 whereby the fuel gas is burned and heat energy is released.
During the treatment of convection tubes 18 and radiant tubes 20, the feed conversion enhancing composition is conveyed to cracking furnace 12 feed stream through conduit 30 and admixed prior to the resulting n~ e entering cracking furnace 12. Interposed in conduit 30 is heat exchanger 32 which provides heat e~ch~nge means for transferring heat energy and to thereby vaporize the feed conversion enhancing composition.
The following example is provided to further illustrate the present invention.
EXAMPLE
This example lPmon.ctrates the energy savings of a tube treated with tin and silicon compared to an u~ eated tube.
A 1.52" I.D. HP-Modified tube that was 12 feet in length was treated with 500 ppmw dimethylsulfide for four hours at 1250F. dimethylsulfide was introduced with 26.4 lb/hr steam and 3.5 lb/hr nitrogen at 400F and 40 psig several feet upstream of an electric furnace which enclosed the reactor tube. The feed rate was then changed to 25.3 lb/hr ethane and 7.6 lb/hr steam at 12 psig and the temperalu.es in the furnace were brought up to cracking conditions in a period of one hour. R~sid~nce time in the reactor tube was held at 270 milliseconds. The dimethylsulfide injection was reduced to 125 ppmw at twenty hours after the ethane charge was introduced and injection was continllçd for the remainder of the 56 hour test run. The steady-state coil outlet temperature was m~int~ined at 1770F to hold ethane conversion constant at 67% throughout the test run.
A pretreatment of six hours with 100 ppmm tetrabutyltin and 50 ppmm hexamethyl disiloxane at temperatures from 1200F to 1500F and 40 psig was done on the same tube described above. This mixture was also injected at the same location as the dimethylsulfide with 26.4 lb/hr steam and 3.5 lb/hr nitrogen. The feed was then changed to 25.3 lb/hr ethane and 7.6 lb/hrsteam and the temperatures in the furnace were brought up to cracking conditionsin a period of one hour. Residence time in the reactor tube was held at 270 milliseconds. Four hours after the ethane charge was brought in, the concentration of the tin/silica mixture was reduced to 50 ppmm tetrabutyltin and25 ppmm hexamethyl disiloxane. Eight hours after the ethane charge was brought in, the injection of the tin/silica n~ e was discontinued for the remainder of the 103 hour test run. The steady state coil outlet temperature was m~int~ined at 1615F to hold ethane c onversion constant at 67% throughout the test run. This is 155F lower than the test run with the untreated tube which clearly demonstrates the energy savings that can be obtained by treating an ethane pyrolysis tube with a tin/silica composition.
Selected data points obtained from the two test runs described in this Example are presented in Table I. These data are presented in the plot of FIG. 2.
A comparison of the data obtained from the two test runs shows the benefit of a significantly reduced coil outlet temperature that results from the use of the novel cracker tube treatment method.
~152336 33277CA
. 19 TABLE I
Comparative Data for Conventional Dimethylsulfide (DMS) Treatment of Cracker Tubes Versus the Illv~nliv~ Treatment of Cracker Tubes With Tin/Silicon (Sn/Si) ComPound I RunTime (Hrs) I DMS Run I Sn/SiRun T Difference Reasonable variations and modifications are possible by those 20 skilled in the art within the scope of the described invention and the appended clairns.
The process of this invention involves the pyrolytic cracking of hydrocarbons to produce desirable hydrocarbon end-products. A hydrocarbon stream is fed or charged to pyrolytic cracking furnace means wherein the hydrocarbon stream is subjected to a severe, high-temperature ellvilol~llent to 10 produce cracked gases. The hydrocarbon stream can comprise any type of hydrocarbon that is suitable for pyrolytic cracking to olefin compounds.
Preferably, however, the hydrocarbon stream can comprise paraffin hydrocarbons selected from the group consisting of ethane, propane, butane, pentane, naphtha, and mi~ s of any two or more thereof. Naphtha can generally be described as 15 a complex hydrocarbon n~ e having a boiling range of from about 180F to about 400F as delelll~ ed by the standard testing methods of the American Society of Testing Materials (ASTM).
The pyrolytic cracking of a higher molecular weight hydrocarbons to a lower molecular weight hydrocarbons can be referred to as conversion. The 20 terms "conversion", "feed conversion", and similar such terminology, as used throughout this specification, are defined as the ratio of the difference between the 21s2336 33277CA
mass of saturated hydrocarbons charged to a cracking zone and the mass of unconverted saturated hydrocarbons leaving, as an effluent, such cracking zone divided by the mass of saturated hydrocarbons charged to the cracking zone. The numerical value for conversion can be reported as a fraction (ratio) or as a 5 percentage. Conversion can also be reported on an individual compound basis such as, for e~mple, ethane conversion, propane conversion, butane conversion, and the like.
As an optional feature of the invention, the hydrocarbon feed being charged to pyrolytic cracking furnace means can be inhm~tely mixed with a 10 diluent prior to ent~ring pyrolytic cracking furnace means. This diluent can serve several positive functions, one of which includes providing desirable reaction conditions within pyrolytic cracking furnace means for producing the desired reactant end-products. The diluent does this by providing for a lower partial pressure of hydrocarbon feed fluid thereby enhancing the cracking reactions 15 necessary for obtaining the desired olefin products while reducing the amount of undesirable reaction products such as hydrogen and methane. Also, the lower partial pressure resulting from the ~ e of the diluent fluid helps in minimi7:in~;
the amount of coke deposits that form on the furnace tubes. While any suitable diluent fluid that provides these benefits can be used, the preferred diluent fluid 20 is steam.
The cracking reactions induced by pyrolytic cracking furnace means can take place at any suitable temperature that will provide the necessary cracking to the desirable end-products or the desired feed conversion. The actual cracking temperature ~ 7e~ will depend upon the composition of the hydrocarbon feed 5 stream and the desired feed conversion. Generally, the cracking temperature can run u~w~ly to about 2000F or great er depending upon the amount of cracking or conversion desired and the molecular weight of the feedstock being cracked.
Preferably, however, the cracking temperature will be in the range of from about 1200F to about l900F. Most preferably, the cracking temperature can be in 10 the range from 1500F to l~OOF.
The cracked hydrocarbon effluent or cracked hydrocarbons or cracked hydrocarbon stream from pyrolytic cracking furnace means will generally be a mixture of hydrocarbons in the gaseous phase. This mixture of gaseous hydrocarbons can comprise not only the desirable olefin compounds, such as 15 ethylene, propylene, butylene, and amylene, but also, this cracked hydrocarbon stream can contain undesirable co"~ hng components that include both oxygenated compounds and acidic compounds and light ends such as hydrogen and methane.
The cracking furnace means of the inventive method can be any 20 suitable thermal cracking furnace known in the art. The various cracking furnaces are well known to those skilled in the art of cracking technology and the choice of a suitable cracking furnace for use in a cracking process is generally a matter of plerelellce. Such cracking furnaces, how~v~r, are equipped with at least one cracking tube to which the hydrocarbon feedstock is charged or fed. The cracking tube provides for and defines a cracking zone contained within the cracking 5 furnace. The cracking furnace is utilized to release the heat energy required to provide for the necessary cracking temperature within the cracking zone in order to induce the cracking reactions therein. Each cracking tube can have any geometry which suitably defines a volume in which cracking reactions can take place and, thus, will have an inside surface. The term "cracking temperature" as 10 used herein is defined as being the temperature within the cracking zone defined by a cracking tube. The outside wall temperature of the cracking tube can, thus, be higher than the cracking temperature and possibly substantially higher due to heat transfer considerations. Typical pressures within the cracking zone will generally be in the range of from about 5 psig to about 25 psig and, preferably 15 from 10 psig to 20 psig.
The inventive method includes the treatment or treating of the tubes of a cracking furnace by contacting the surface of such tubes with a feed conversion enhancing composition. The use of the feed conversion enhancing composition provides for or induces an increase in the conversion of the 20 hydrocarbon feedstock to a cracking furnace for a given cracking temperature.
This enhancement in feed conversion permits the reduction in the cracking 2 1S2 33 ~ 33277CA
temperature below that required to give the feed conversion which results from tili~ing untreated cracker tubes. The feed conversion enhancing composition is a combination or n~ e of tin and silicon, thus the composition will comprise, consist essentially of, or consist of tin and silicon.
Any suitable form of silicon may be utilized in the feed conversion enhancing composition comprising tin and silicon. Element~l silicon, inorganic silicon compounds and organic silicon compounds as well as ~ es of any two or more thereof are suitable sources of silicon. The term "silicon" generally refers to any one of these silicon sources.
Examples of some inorganic silicon compounds that can be used include the halides, nitrides, hydrides, oxides and sulfides of silicon, silicic acids and alkali metal salts thereof. Of the inorganic silicon compounds, those which do not contain halogen are pr~relled.
Examples of organic silicon compounds that may be used include compounds of the formula Rl-Si-R3 wherein Rl, R2, R3, and R4 are selected independently from the group consisting of hydrogen, halogen, hydrocarbyl, and oxyhydrocarbyl and wherein the compound's bonding may be either ionic or covalent. The hydrocarbyl and 215233~ 33277CA
oxyhydrocarbyl radicals can have from 1-20 carbon atoms which may be substituted with halogen, nitrogen, phosphorus, or sulfur. Exemplary hydrocarbyl radicals are aLkyl, alkenyl, cycloaLkyl, aryl, and combinations thereof, such as alkylaryl or aLkylcycloaLkyl. Exemplary oxyhydrocarbyl radicals are alkoxide, 5 phenoxide, carboxylate, ketocarboxylate and diketone (dione). Suitable organic silicon compounds include trimethylsilane, tetramethylsilane, tetraethylsilane, triethylchlorosilane, phenyltrimethylsilane, tetraphenylsilane, ethyltrimethoxysilane, propyltriethoxysilane, dodecyltrihexoxysilane, vinyltriethyoxysilane, tetramethoxyorthosilicate, tetraethoxyorthosilicate, 10 polydimethylsiloxane, polydiethylsiloxane, polydihexylsiloxane, polycyclohexylsiloxane, polydiphenylsiloxane, polyphenylmethylsiloxane, 3-chloropro~yltrimethoxysilane, and 3-aminopropyltriethoxysilane. At present hexamethyldisiloxane is preferred. Organic silicon compounds are particularly pler~ d because such compounds are soluble in the feed material and 15 in the diluents which are preferred for preparing ~relle&~ ent solutions as will be more fully described hereinafter. Also, organic silicon compounds appear to have less of a tendency towards adverse effects on the cracking process than do inorganic silicon compounds.
Any suitable form of tin may be utilized in the feed conversion 20 enhancing composition comprising tin and silicon. Elemental tin, inorganic tin compounds and organic tin compounds as well as mixtures of any two or more thereof are suitable sources of tin. The term "tin" generally refers to any one of these tin sources.
Examples of some inorganic tin compounds which can be used include tin oxides such as stannous oxide and stannic oxide; tin sulfides such as 5 stannous sulfide and stannic sulfide; tin sulfates such as stannous sulfate and stannic sulfate; stannic acids such as metastannic acid and thiostannic acid; tin halides such as stannous fluoride, stannous chloride, stannous bromide, stannous iodide, stannic fluoride, stannic chloride, st~nnic bromide and stannic iodide; tin phosphates such as stannic phosphate; tin oxyhalides such as stannous oxychloride 10 and stannic oxychloride; and the like. Of the inorganic tin compounds those which do not contain halogen are preferred as the source of tin.
Examples of some organic tin compounds which can be used include tin carboxylates such as stannous formate, stannous acetate, stannous butyrate, stannous octoate, stannous decanoate, stannous oxalate, stannous benzoate, and 15 stannous cyclohexanecarboxylate; tin thiocarboxylates such as stannous thioacetate and stannous dithioacetate; dihydrocarbyltin bis(hydrocarbyl mercaptoalkanoates) such as dibutyltin bis(isoocylmercaptoacetate) and dipropyltin bis(butyl mercaptoacetate); tin thiocarbonates such as stannous O-ethyl dithiocarbonate; tin carbonates such as stannous propyl carbonate;
20 tetrahydrocarbyltin compounds such as tetramethyltin, tetraoctyltin, tetradodecyltin, and tetraphenyltin; dihydrocarbyltin oxides such as dipropyltin 215233~ 33277CA
oxide; dibutyltin oxide, dioctyltin oxide, and diphenyltin oxide; dihydrocarbyltin bis(hydrocarbyl mercaptide)s such as dibutyltin bis(dodecyl mercaptide); tin salts of phenolic compounds such as stannous thiophenoxide; tin sulfonates such as stannous benzenesulfonate and stannous-p-toluenesulfonate; tin carbamates such as stannous diethylcarbamate; tin thiocarbamates such as stannous propylthiocarbamate and stannous diethyldithiocarbamate; tin phosphites such as stannous diphenyl phosphite; tin phosphates such as stannous dipropyl phosphate;tin thiophosphates such as stannous O,O-dipropyl thiophosphate, stannous O,O-dipropyl dithiophosphate and stannic O,O-dipropyl dithiophosphate, dihydrocarbyltin bis(O,O-dihydrocarbyl thiophosphate)s such as dibutyltin bis(O,O-dipropyl dithiophosphate); and the like. At present tetrabutyltin is preferred. Again, as with silicon, organic tin compounds are preferred over inorganic compounds. Any of the listed sources of tin may be combined with any of the listed sources of silicon to form the feed conversion enhancing composition comprising tin and silicon.
The feed conversion enhancing composition can have any molar ratio of tin to silicon which suitably provides for the cracker tube treatment or enhanced cracker feed conversion as required hereunder. Generally, however, the molar ratio of tin to silicon of the composition can be in the range of from about 1:100 to about 100:1. Preferably, the molar ratio can be from about 1:10 to about 10:1 and, most preferably, it can be from 1:4 to 4:1.
13 21S~36 The feed conversion enhancing composition is lltili7ed in the treatment of the surfaces of the cracking tubes of a cracking furnace. The composition is contacted with surfaces of the cracking tubes either by pretreating the cracking tubes with the composition prior to charging the tubes with a 5 hydrocarbon feed or by adding the composition to the hydrocarbon feed in an amount effective for t~nh~ncin~ feed conversion for a given cracking tempe,alure.
Any method can be used which suitably treats the tubes of a cracking furnace by contacting such tubes with the feed conversion enhancing composition under suitable treatment conditions to thereby provide treated tubes.
10 The treated tubes will provide for a lower required cracking temperature for a given cracker feed conversion.
The preferred procedure for pretreating the tubes of the cracking furnace, includes charging to the inlet of the cracking furnace tubes a saturated or slightly superheated steam having a temperature in the range of from about 300F
15 to about 500F. The cracking furnace is fired while charging the tubes with the steam so as to provide a superheated stearn which exits the tubes at a temperature exceeding that of the steam introduced into the inlet of the tubes. Generally, the steam effluent will have a temperature u~w~-dly to about 2000F. Thus, the treating temperature can be in the range of from about 300F to about 2000F, preferably, from about 400F to about 1800F and, most preferably, from 500F
2i5~336 33277CA
to 1600F. It is desirable for the steam to be charged to the convection section of the cracking furnace, therefore, first passing through the convection section tubes followed by passing through the radiant section tubes.
The feed conversion enhancing composition can then be ~lmixed 5 with the steam being charged to the cracker tubes. The feed conversion enhancing composition can be admixed with the steam as either a neat liquid or as a ~ e of the feed conversion enhancing composition with an inert diluent. It is plerelled, however, to first vaporize either the neat liquid or the llli~ e prior to its introduction into or ~llmixing with the steam. The amount of feed conversion 10 enhancing composition ~(lmixed with the steam can be such as to provide a concentration of the feed conversion enhancing composition in the steam in the range of from about 1 ppmw to about 10,000 ppmw, preferably, from about 10 ppmw to about 1000 ppmw and, most preferably, from 20 to 200 ppmw.
The ~l,,,;X~ of steam and feed conversion enhancing composition 15 is contacted with or charged to the cracker tubes for a period of time sufficient to provide for treated tubes, which when placed in cracking service, will require a cracking temperature for a given feed conversion below that for untreated tubes.
Such time period for pretreating the cracker tubes is influenced by the specific geometry of the cracking furnace including its tubes; but, generally, the pretreating 20 time period can range upwardly to about 12 hours, and longer if required. But, 21~233~ 33277CA
preferably, the period of time for the p~ ea~ g can be in the range of from about 0.1 hours to about 12 hours and, most preferably, from 0.5 hours to 10 hours.
In the case where the feed conversion enhancing composition is directly admixed with the hydrocarbon cracker feed, it can be added in such an 5 amount to be effective in enhancing the feed conversion above that which occurs when no feed conversion enhancing composition is added. Due to the memory effect resulting from the application of the feed conversion enhancing composition, the mixing with the hydrocarbon cracker feed is conducted int~ e~ly as required but, preferably, for periods up to about 12 hours. The 10 concentration of the feed conversion enhancing composition in the hydrocarbon cracker feed during treating of the cracker tubes can be in the range of from about 1 ppmw to about 10,000 ppmw, preferably, from about 10 ppmw to about 1000 ppmw and, most preferably, from 20 to 200 ppmw.
Now referring to FIG. 1, there is illustrated by schematic 15 representation cracking furnace section 10 of a pyrolytic cracking process system.
Cracking furnace section 10 includes pyrolytic cracking means or cracking furnace 12 for providing heat energy required for inducing the cracking of hydrocarbons.
Cracking furnace 12 defines both convection zone 14 and radiant zone 16.
Respectively within such zones are convection coils as tubes 18 and radiant coils 20 as tubes 20.
A hydrocarbon feedstock or a n~ e of steam and such hydrocarbon feedstock is conducted to the inlet of convection tubes 18 by way ofconduit 22 which is in fluid flow coll"llullication with convection tubes 18.
During the treatment of the tubes of cracking furnace 12, the a-lmi~lre of steamand the feed conversion enhancing composition can also be conducted to the inletof convection tubes 18 through conduit 22. The feed passes through the tubes of cracking furnace 12 wherein it is heated to a cracking temperature in order to induce cracking or, in the situation where the tubes are undergoing treatment, to the required treatment temperature. The effluent from cracking furnace 12 passesdownstream through conduit 24. To provide for the heat energy necessary to operate cracking furnace 12, fuel gas is conveyed through conduit 26 to burners 28 of cracking furnace 12 whereby the fuel gas is burned and heat energy is released.
During the treatment of convection tubes 18 and radiant tubes 20, the feed conversion enhancing composition is conveyed to cracking furnace 12 feed stream through conduit 30 and admixed prior to the resulting n~ e entering cracking furnace 12. Interposed in conduit 30 is heat exchanger 32 which provides heat e~ch~nge means for transferring heat energy and to thereby vaporize the feed conversion enhancing composition.
The following example is provided to further illustrate the present invention.
EXAMPLE
This example lPmon.ctrates the energy savings of a tube treated with tin and silicon compared to an u~ eated tube.
A 1.52" I.D. HP-Modified tube that was 12 feet in length was treated with 500 ppmw dimethylsulfide for four hours at 1250F. dimethylsulfide was introduced with 26.4 lb/hr steam and 3.5 lb/hr nitrogen at 400F and 40 psig several feet upstream of an electric furnace which enclosed the reactor tube. The feed rate was then changed to 25.3 lb/hr ethane and 7.6 lb/hr steam at 12 psig and the temperalu.es in the furnace were brought up to cracking conditions in a period of one hour. R~sid~nce time in the reactor tube was held at 270 milliseconds. The dimethylsulfide injection was reduced to 125 ppmw at twenty hours after the ethane charge was introduced and injection was continllçd for the remainder of the 56 hour test run. The steady-state coil outlet temperature was m~int~ined at 1770F to hold ethane conversion constant at 67% throughout the test run.
A pretreatment of six hours with 100 ppmm tetrabutyltin and 50 ppmm hexamethyl disiloxane at temperatures from 1200F to 1500F and 40 psig was done on the same tube described above. This mixture was also injected at the same location as the dimethylsulfide with 26.4 lb/hr steam and 3.5 lb/hr nitrogen. The feed was then changed to 25.3 lb/hr ethane and 7.6 lb/hrsteam and the temperatures in the furnace were brought up to cracking conditionsin a period of one hour. Residence time in the reactor tube was held at 270 milliseconds. Four hours after the ethane charge was brought in, the concentration of the tin/silica mixture was reduced to 50 ppmm tetrabutyltin and25 ppmm hexamethyl disiloxane. Eight hours after the ethane charge was brought in, the injection of the tin/silica n~ e was discontinued for the remainder of the 103 hour test run. The steady state coil outlet temperature was m~int~ined at 1615F to hold ethane c onversion constant at 67% throughout the test run. This is 155F lower than the test run with the untreated tube which clearly demonstrates the energy savings that can be obtained by treating an ethane pyrolysis tube with a tin/silica composition.
Selected data points obtained from the two test runs described in this Example are presented in Table I. These data are presented in the plot of FIG. 2.
A comparison of the data obtained from the two test runs shows the benefit of a significantly reduced coil outlet temperature that results from the use of the novel cracker tube treatment method.
~152336 33277CA
. 19 TABLE I
Comparative Data for Conventional Dimethylsulfide (DMS) Treatment of Cracker Tubes Versus the Illv~nliv~ Treatment of Cracker Tubes With Tin/Silicon (Sn/Si) ComPound I RunTime (Hrs) I DMS Run I Sn/SiRun T Difference Reasonable variations and modifications are possible by those 20 skilled in the art within the scope of the described invention and the appended clairns.
Claims (20)
1. A method comprising the steps of:
contacting a tube of a cracking furnace with a composition containing a tin compound and a silicon compound to thereby provide a treated tube;
thereafter, operating said treated tube under cracking conditions and at a cracking temperature suitable for achieving a given conversion, said cracking temperature being below that required to achieve said given conversion with said tube.
contacting a tube of a cracking furnace with a composition containing a tin compound and a silicon compound to thereby provide a treated tube;
thereafter, operating said treated tube under cracking conditions and at a cracking temperature suitable for achieving a given conversion, said cracking temperature being below that required to achieve said given conversion with said tube.
2. A method as recited in claim 1 wherein said tin compound is an organotin compound and said silicon compound is an organosilicon compound.
3. A method as recited in claim 2 wherein in said composition the molar ratio of said tin compound to said silicon compound is in the range of from 1:100 to 100:1.
4. A method as recited in claim 3 wherein the contacting step further includes utilizing said composition in an admixture with steam at a concentration in the range of from about 1 ppmw to about 10,000 ppmw.
5. A method as recited in claim 4 wherein the contacting step is conducted at a temperature in the range of from about 300F to 2000F.
6. A method as recited in claim 5 wherein the contacting step is conducted for a time period upwardly to about 12 hours.
7. A method as recited in claim 6 wherein said organotin compound is tetrabutyltin and said organosilicon compound is hexamethyldisiloxane.
8. A method of reducing a required cracking temperature for a given feed conversion in the operation of a cracking furnace of a thermal cracking process for cracking a hydrocarbon stream said cracking furnace being equipped with a cracking tube having a surface, said method comprises:
contacting said surface of said cracking tube with a composition comprising a tin compound and a silicon compound so as to provide a treated cracking tube;
charging said hydrocarbon stream to said treated cracking tube; and maintaining a cracking temperature below said required cracking temperature for said given feed conversion.
contacting said surface of said cracking tube with a composition comprising a tin compound and a silicon compound so as to provide a treated cracking tube;
charging said hydrocarbon stream to said treated cracking tube; and maintaining a cracking temperature below said required cracking temperature for said given feed conversion.
9. A method as recited in claim 8 wherein said tin compound is an organotin compound and said silicon compound is an organosilicon compound.
10. A method as recited in claim 9 wherein in said composition the molar ratio of said tin compound to said silicon compound is in the range of from 1:100 to 100:1.
11. A method as recited in claim 10 wherein the contacting step further includes utilizing said composition in an admixture with steam at a concentration in the range of from about 1 ppmw to about 10,000 ppmw.
12. A method as recited in claim 11 wherein the contacting step is conducted at a temperature in the range of from about 300F to 2000F.
13. A method as recited in claim 12 wherein the contacting step is conducted for a time period upwardly to about 12 hours.
14. A method as recited in claim 13 wherein said organotin compound is tetrabutyltin and said organosilicon compound is hexamethyldisiloxane.
15. A method of reducing energy consumption for a given feed conversion in the operation of a cracking furnace of a thermal cracking process for cracking a hydrocarbon stream, comprising the steps of:
adding to said hydrocarbon stream in an amount effective for enhancing feed conversion for a given cracking temperature a composition comprising a tin compound and a silicon compound; and thereafter, reducing said given cracking temperature to thereby reduce energy consumption.
adding to said hydrocarbon stream in an amount effective for enhancing feed conversion for a given cracking temperature a composition comprising a tin compound and a silicon compound; and thereafter, reducing said given cracking temperature to thereby reduce energy consumption.
16. A method as recited in claim 15 wherein said tin compound is an organotin compound and said silicon compound is an organosilicon compound.
17. A method as recited in claim 16 wherein in said composition the molar ratio of said tin compound to said silicon compound is in the range of from 1:100 to 100:1.
18. A method as recited in claim 17 wherein said amount of said composition added to said hydrocarbon stream is such as to provide a concentration in the range of from 1 to 10,000 parts by weight of said composition per parts by weight of said hydrocarbon stream.
19. A method as recited in claim 18 wherein said cracking temperature is in the range of from 1200F to 2000F.
20. A method as recited in claim 19 wherein said organotin compound is tetrabutyltin and said organosilicon compound is hexamethyldisiloxane.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29596894A | 1994-08-25 | 1994-08-25 | |
| US08/295,968 | 1994-08-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2152336A1 true CA2152336A1 (en) | 1996-02-26 |
Family
ID=23140009
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002152336A Abandoned CA2152336A1 (en) | 1994-08-25 | 1995-06-21 | Method for saving energy in a thermal cracking process |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0698653A1 (en) |
| JP (1) | JPH0892570A (en) |
| KR (1) | KR960007737A (en) |
| CN (1) | CN1123307A (en) |
| AU (1) | AU670527B2 (en) |
| BR (1) | BR9503793A (en) |
| CA (1) | CA2152336A1 (en) |
| MX (1) | MX9503583A (en) |
| TW (1) | TW367361B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060219598A1 (en) * | 2005-01-10 | 2006-10-05 | Cody Ian A | Low energy surfaces for reduced corrosion and fouling |
| US8201619B2 (en) | 2005-12-21 | 2012-06-19 | Exxonmobil Research & Engineering Company | Corrosion resistant material for reduced fouling, a heat transfer component having reduced fouling and a method for reducing fouling in a refinery |
| US8037928B2 (en) | 2005-12-21 | 2011-10-18 | Exxonmobil Research & Engineering Company | Chromium-enriched oxide containing material and preoxidation method of making the same to mitigate corrosion and fouling associated with heat transfer components |
| US20080073063A1 (en) * | 2006-06-23 | 2008-03-27 | Exxonmobil Research And Engineering Company | Reduction of fouling in heat exchangers |
| US8349267B2 (en) | 2007-10-05 | 2013-01-08 | Exxonmobil Research And Engineering Company | Crude oil pre-heat train with improved heat transfer |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4692234A (en) * | 1986-04-09 | 1987-09-08 | Phillips Petroleum Company | Antifoulants for thermal cracking processes |
-
1995
- 1995-06-21 CA CA002152336A patent/CA2152336A1/en not_active Abandoned
- 1995-08-17 AU AU28569/95A patent/AU670527B2/en not_active Ceased
- 1995-08-18 TW TW084108648A patent/TW367361B/en active
- 1995-08-21 MX MX9503583A patent/MX9503583A/en not_active Application Discontinuation
- 1995-08-24 KR KR1019950026385A patent/KR960007737A/en not_active Application Discontinuation
- 1995-08-24 JP JP7216113A patent/JPH0892570A/en active Pending
- 1995-08-24 EP EP95113300A patent/EP0698653A1/en not_active Withdrawn
- 1995-08-24 CN CN95116668A patent/CN1123307A/en active Pending
- 1995-08-24 BR BR9503793A patent/BR9503793A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| KR960007737A (en) | 1996-03-22 |
| BR9503793A (en) | 1997-05-27 |
| EP0698653A1 (en) | 1996-02-28 |
| CN1123307A (en) | 1996-05-29 |
| MX9503583A (en) | 1997-05-31 |
| AU670527B2 (en) | 1996-07-18 |
| TW367361B (en) | 1999-08-21 |
| JPH0892570A (en) | 1996-04-09 |
| AU2856995A (en) | 1996-03-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0733693B1 (en) | Method for providing a tube having coke formation and carbon monoxide inhibiting properties when used for the thermal cracking of hydrocarbons | |
| US5656150A (en) | Method for treating the radiant tubes of a fired heater in a thermal cracking process | |
| EP0241020B1 (en) | Antifoulants for thermal cracking processes | |
| AU672942B2 (en) | Method for improving the yield of heavy hydrocarbons in a thermal cracking process | |
| NO171022B (en) | PROCEDURE FOR REDUCING COCOAL CREATION ON METAL SURFACES TO BE CONNECTED WITH A HYDROCARBONOUS CURRENT IN A THERMAL CRACKING PROCESS | |
| EP0242693A1 (en) | Antifoulants for thermal cracking processes | |
| AU670527B2 (en) | Method for reducing temperature in thermal cracking of hydrocarbons | |
| EP0391620B1 (en) | Method for reducing fouling in ethylene cracking furnaces | |
| CA2154809C (en) | Method of promoting the decomposition of silicon compounds in a process for depositing silicon upon a metal surface | |
| PL180515B1 (en) | Method of reducing carbon deposit building up on heat exchange surfaces | |
| CA2263043C (en) | Method for reducing carbon monoxide in the cracking of hydrocarbon gas streams | |
| EP0770665B1 (en) | Pyrolytic cracking of desulfurised hydrocarbons in tubes treated with tin and silicon | |
| AU672943B2 (en) | Method for promoting the spalling of coke produced during the thermal cracking of hydrocarbons | |
| KR100352921B1 (en) | How to treat the radiation tube of the combustion heater in the pyrolysis process |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20030623 |