CA2155044A1 - Method for promoting the spalling of coke produced during the thermal cracking of hydrocarbons - Google Patents
Method for promoting the spalling of coke produced during the thermal cracking of hydrocarbonsInfo
- Publication number
- CA2155044A1 CA2155044A1 CA002155044A CA2155044A CA2155044A1 CA 2155044 A1 CA2155044 A1 CA 2155044A1 CA 002155044 A CA002155044 A CA 002155044A CA 2155044 A CA2155044 A CA 2155044A CA 2155044 A1 CA2155044 A1 CA 2155044A1
- Authority
- CA
- Canada
- Prior art keywords
- cracking
- coke
- tin
- recited
- spalling
- 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
- 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
Spalling of coke produced during the thermal cracking of hydrocarbon is promoted by contacting or treating the tubes of a thermal cracking furnace with a composition having an absence of silicon and comprising tin.
Description
21S5~ 33294CA
METHOD FOR PROMOTING THE SPALLING OF
COKE PRODUCED DURING THE THERMAL CRACKING
OF HYDROCARBONS
The present invention relates to processes for the thermal cracking of hydrocarbons. More specifically, the present invention relates to a method for promoting the spalling of coke produced during the pyrolytic cracking of hydrocarbons.
In a process for producing an olefin compound, a fluid stream containing a saturated hydrocarbon such as ethane, propane, butane, pentane, naphtha, or lui2~lules 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 m~ter1~1 being introduced into the cracking furnace.
Within the furnace, the saturated hydrocarbon is converted into an 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 ~ e of saturated hydrocarbons cont~ining ethane, propane, butane, pentane and naphtha is converted to a mixture of olefinic compounds co~ g ethylene, 5 propylene, butenes, pentenes, and n~phth~lene. Olefinic compounds are an important class of industrial chemicals. For example, ethylene is a monomer or comonnmer 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 10 product stream can also contain appreciable quantities of hydrogen, methane, acetylene, carbon monoxide, carbon dioxide, and pyrolytic products ot_er than the olefinic compounds.
During the thermal or pyrolytic cracking of hydrocarbons, a semi-pure carbon which is termed as "coke" is formed. The coke formed in the cracking 15 process normally deposits upon the surfaces of the cracking tubes of the pyrolytic cracking furnace of such process. The accumulation of coke upon the surfaces of the cracking tubes ultimately requires the shut down of the cracking furnace in order to burn off the coke deposits. The accllm~ tion of coke deposits necessitates the periodic shutdown of the cracking furnace due to the excessive 20 pressure drop across the cracking furnace tubes and the higher furnace temperatures required as a result of the therm~l insulating properties of the deposited coke.
Compositions known as antifoulants have been used to inhibit ~e formation and deposition of coke upon the surfaces of cracking furnace tubes and 5 on the metal surfaces of downstream heat exchangers and other process equipment. In spite of the inhibition in the formation of coke by use of such antifoulants, the coke buildup during the cracking of hydrocarbons still occurs but at a slower rate. It can be desirable for there to be minim~l buildup or deposition of coke upon the cracker tube surfaces. A reduction in coke accllm~ tion on the 10 cracking tubes will increase the run length of a cracking furnace between shutdowns and thereby improve the cracking operation.
It is an object of this invention to provide an illl~,roved process for cracking saturated hydrocarbons to produce olefin end-products.
Another object of this inven*on is to provide a method for limi*ng 15 the deposition or accllmlll~*on of coke upon the tube surfaces of a cracking furnace.
A still further object of this inven*on is to provide a method for promoting the spalling of coke produced during the pyrolytic cracking of coke produced during the pyrolytic cracking of hydrocarbons to prevent, limit, or 20 reduce the buildup of coke deposits upon the cracker tube surfaces to thereby increase cracker furnace run length between shutdowns.
21550~ 33294CA
In accordance with the present invention, spalling of coke produced during the pyrolytic cracking of a hydrocarbon stream is promoted by passing the hydrocarbon stream through a tube of a pyrolytic cracking furnace operated under suitable cracking conditions to thereby produce a cracked product stream. An 5 antifoulant co"~ g tin but having a substantial absence of silicon is added to the hydrocarbon stream in an amount sufficient to promote the spalling of coke produced during the pyrolytic cracking of the hydrocarbon stream.
Another embodiment of the invention includes contacting an antifoulant co,.~ g tin but having a substantial absence of silicon with a tube 10 of a pyrolytic cracking furnace under suitable treatment conditions to thereby provide a treated tube. A hydrocarbon stream is passed through the treated tube which is operated under suitable cracking conditions to thereby produce a cracked product stream having therein spalled coke.
Other objects and advantages of the invention will be apparent from 15 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~tic diagram representing the portion of an ethylene cracking process that includes pyrolytic cracking furnace means and other elements of the novel process;
FIG. 2 is a bar chart showing the amount of coke spalled during ethane cracking from an HK4M alloy tube treated with dimethylsulfide, tin, or a tin/silicon ~ e; and FIG. 3 is a bar chart showing the amount of coke spalled during 5 ethane cracking from an HP Modified alloy tube treated with dimethylsulfide, tin, or tin/silicon.
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 10 hydrocarbon stream is subjected to a severe, high-temperature ellvirol~"~ent to 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, 15 and ~ s of any two or more thereof. Naphtha can generally be described as a complex hydrocarbon mixture having a boiling range of from about 180F to about 400F as d~l~llllil~ed by the standard testing methods of the American Society of Testing M~tçri~l~ (ASTM).
As an optional feature of the invention, the hydrocarbon feed being 20 charged to pyrolytic cracking furnace means can be in~im~tely mixed with a diluent prior to entering pyrolytic cracking furnace means. This diluent can serve 215S04~ 33294CA
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 necessary for obtaining the desired olefin products while reducing the amount ofundesirable reaction products such as hydrogen and methane. Also, the lower partial plC;SSUI~ res~ ing from the ll~lule of the diluent fluid helps in minimi7:ing the amount of coke deposits that form on the furnace tubes. While any suitable diluent fluid that provides these benefits can be used, the prefelled diluent fluid is steam.
The cracking reactions in(luce~ by pyrolytic cracking furnace means can take place at any suitable temperature that will provide the necessary cracking to the desirable end-products or to give a desired feed conversion. The actual cracking temperature utilized will depend upon the composition of the hydrocarbon feed stream and the desired feed conversion. Generally, the crackingtemperature can range uywaldly to about 2000F or greater 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 the range from 1500F to 1800F.
215504~ 33294CA
The cracked hydrocarbon effluent or cracked hydrocarbons or cracked product stream from pyrolytic cracking furnace means will generally be a mixture of hydrocarbons in the gaseous phase. This ~ e of gaseous hydrocarbons can comprise not only the desirable olefin compounds, such as 5 ethylene, propylene, butylene, and amylene, but also, this cracked hydrocarbon stream can contain undesirable co~ ting components that include both oxygenated compounds and acidic compounds and light ends such as hydrogen and methane.
The cracking furnace means of the i~v~nlive method can be any 10 suitable thenn~l cracking ffirn~ce 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 plerelel~ce. Such cracking filrn~ces are equipped with at least one cracking tube to which the hydrocarbon feedstock is charged or fed. The cracking tube provides 15 for and defines a cracking zone contained within the cracking furnace. The cracking furnace is lltili7e-l to release the heat energy required to provide for the necessary cracking temperature within the cracking zone in order to induce cracking reactions therein. Each cracking tube can have any geometry which suitably defines a volume in which cracking reactions can take place and, thus, 20 will have an inside surface. The term "cracking temperature" as 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 ples~ s within the cracking zone will generally be in the range of from about 0 psig to about 100 psig and, preferably from 0 psig to 5 60 psig.
The inventive method provides for or promotes the spalling of coke produced during the pyrolytic cracking of a hydrocarbon stream. It has been discovered that the treatment or treating of the tubes of a cracking furnace with a tin compound only or, more specifically, with a composition having an absence 10 of silicon but comprising tin, coke spalling is promoted. Coke spalling occurs when the coke formed in the cracking tubes during the cracking of hydrocarbon either fails to adhere to the tube surfaces thereby forming a layer of coke or when it is deposited upon the tube surfaces and thereafter chips, flakes or breaks off such surfaces.
Coke spalling for many cracking operations can be undesirable if the spalled coke results in damage or plugging of equipment located down stream from the cracking furnace. However, in situations where the downstream eqllipm~nt can handle the fr~nent~ of spalled coke or, ~lt~ tively, where means is provided which can suitably remove the spalled coke contained in a cracked 20 product stream, the promotion of coke spalling can result in increasing the length of time between decoking of the cracker furnace tubes; because, coke is removed 21~504~
from the tube surfaces by spalling, or it is pr~v~nled from depositing or adhering to the tube surfaces. By increasing the length of time between cracker tube decokings, the furnace production down time is reduced thereby ill,provi~lg cracking furnace productivity and throughput. Thus, if the eqllir)ment used to 5 process the cracker furnace product stream can handle the spalled coke without detriment, or, if suitable removal or separation means for removing at least a portion of the spalled coke contained in the cracked product stream can be provided, then coke spalling can be desired.
A critical aspect of the instant invention is the use of a composition 10 having an absence of a silicon compound but comprising a tin compound. It has been discovered that the tre~tment of the tubes of a cracking furnace in accordance with the methods described herein with a tin compound only, as opposed to a compound co~ both a tin compound and a silicon compound, unexpectedly promotes the sp~lling of coke. When a composition cont~inin~ a combination of 15 tin and silicon is used to treat cracker furnace tubes, on the other hand, excessive spalling of coke is not observed; rather, the formation and deposition of coke appears to be inhibited. Thus, by combining tin and silicon certain antifoulant benefits and properties are obtained that are different from those of an antifoulant col,l;,il~ g a tin compound only or, alternatively, a material having an absence of 20 silicon but comprising tin.
Any suitable form of tin may be utilized in the antifoulant composition having an absence of silicon and comprising tin. Element~l tin, inorganic tin compounds and organic tin compounds as well as ~ ules of any two or more thereof are suitable sources of tin. The term "tin" generally refers to 5 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 starmous sulfide and stannic sulfide; tin sulfates such as stannous sulfate and stannic sulfate; stannic acids such as metastannic acid and thiostannic acid; tin 10 halides such as stannous fluoride, stannous chloride, stannous bromide, stannous iodide, stannic fluoride, stannic chloride, stannic bromide and stannic iodide; tin phosphates such as stannic phosphate; tin oxyhalides such as stannous oxychloride and starmic oxychloride; and the like. Of the inorganic tin compounds those which do not contain halogen are plerelled as the source of tin.
Examples of some organic tin compounds which can be used incl~lde tin carboxylates such as stannous formate, stannous acetate, stannous butyrate, stannous octoate, stannous decanoate, stannous oxalate, stannous benzoate, and stannous cyclohexanecarboxylate; tin thiocarboxylates such as stannous thioacetate and stannous dithioacetate; dihydrocarbyltin bis(hydrocarbyl 20 mercaptoaL~anoates) such as dibutyltin bis(isoocylmercaptoacetate) and dipropyltin bis(butyl mercaptoacetate); tin thiocarbonates such as stannous O-ethyl 215~044 dithiocarbonate; tin carbonates such as stannous propyl carbonate;
tetrahydrocarbyltin compounds such as tetramethyltin, tetraoctyltin, tetradodecyltin, and tetraphenyltin; dihydroc~lJyllin oxides such as dipropyltin oxide; dibutyltin oxide, dioctyltin oxide, and diphenyltin oxide; dihydrocarbyltin S bis(hydrocarbyl mercaptide)s such as dibutyltin bis(dodecyl mercaptide); tin salts of phenolic compounds such as stannous thiophenoxide; tin sulfonates such as stannous ben7~neslllfonate and stannous-p-toluenesulfonate; tin carbamates such as stannous diethylcarbamate; tin thiocarbamates such as stannous propylthioc~l,~ and stannous diethyldithiocarbamate; tin phosphites such as 10 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. Organic tin compounds are 15 preferred over inorganic compounds. At present tetrabutyltin is most preferred.
21~S044 The term "silicon" as used herein refers to silicon sources such as element~l silicon, inorganic silicon compounds and organic silicon compounds as well as mixtures of any two or more thereof.
The antifoulant composition described herein is lltili7e~ in the 5 tre~tment of the surfaces of the cracking tubes of a pyrolytic cracking furnace.
The composition is contacted with surfaces of the cracking tubes either by ~eLIeaLillg the cracking tubes with the antifoulant prior to charging the tubes with a hydrocarbon feed or by adding the antifoulant to the hydrocarbon feed in an amount effective for treating the cracker tubes.
Any method can be used which suitably treats the tubes of a cracking furnace by contacting such tubes with the antifoulant under suitable treatment conditions to thereby provide treated tubes.
The prefel,ed 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 ~ t~ e in the range of from about 300F
to about 500F. The cracking furnace is fired while charging the tubes with the steam so as to provide a superheated steam 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 upwardly 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
21550~9 to 1 600F. It is desirable for the stearn to be charged to the convection section of the cracking furnace, therefore, first passing through the convection section tubes followed by p~sing through the radiant section tubes.
The antifoulant can then be ~(lmixed with the steam being charged 5 to the cracker tubes. The antifoulant can be a~lmixed with the stearn as either a neat liquid or as a mi~ e of the antifoulant with an inert diluent. In any event, it is plefe"ed to vaporize or convert into an aerosol either the neat liquid or the n~lure prior to its introduction into or a~1mixing with the steam. The amount of antifoulant a~lmixed with the stearn can be such as to provide a concentration of the antifoulant in the steam in the range of from about 1 ppmm to about 10,000 ppmm, plerelably, from about 10 ppmm to about 1000 ppmw and, most preferably, from 20 to 200 ppmm.
The ~ ;x~ e of steam and antifoulant is contacted with or charged to the cracker furnace tubes for a period of time sufficient to provide for treated 15 tubes, which when placed in cracking service, will provide or promote an amount of coke sp~lling exceeding that which occurs when the antifoulant includes silicon.
Such time period for pl~lleal~lg the cracker tubes is influenced by the specific geometry of the cracking fumace inchllling its tubes; but, generally, the pretreating time period can range upwardly to about 12 hours, and longer if required. But, 20 preferably, the period of time for the pretreating 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 antifoulant composition is directly a(lmixed with the hydrocarbon feed to the cracking furnace, it can be added in such an amount to be effective in promoting the spalling of coke produced during the pyrolytic cracking of the hydrocarbon feed. Due to the memory effect resulting 5 from the application of the antifoulant the mixing with the hydrocarbon cracker feed is con-lllcte~ r~ lly as required but, preferably, for periods up to about 12 hours. The concentration of the antifoulant in the hydrocarbon cracker feed during treating of the cracking furnace tubes can be in the range of from about 1 ppmm to about 10,000 ppmm, preferably, from about 10 ppmm to about 1000 ppmm and, most preferably, from 20 to 200 ppmm.
Now refellmg to FIG. 1, there is illustrated by schematic representation cracking fumace 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 as tubes 20.
A hydrocarbon feedstock or a mixture of steam and such hydrocarbon feedstock is conducted to the inlet of convection tubes 18 by way of 20 conduit 22 which is in fluid flow co~ lullication with convection tubes 18.
During the treatment of the tubes of cracking furnace 12, the a(lmixtllre of steam 215S0~ 33294CA
and the antifoulant composition can also be conducted to the inlet of 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 5 required tre~tment temperature. The cracked product stream from cracking furnace 12 passes downstream through conduit 24 to sep~lor 26 which defines a zone and provides means for removing at least a portion of the spalled coke contained in the cracked product stream. The spalled coke removed from the cracked product stream passes from separator 26 by way of conduit 28, and the 10 cracked product stream having at least a portion of the spalled coke contained therein removed there~iom passes from sep~lor 26 by way of conduit 30.
To provide for the heat energy necessary to operate cracking furnace 12, fuel gas is conveyed through conduit 32 to burners 34 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 antifoulant composition is conveyed to cracking furnace 12 feed stream through conduit 36 and ~(lmixed prior to the resulting mixture entering cracking furnace 12. Interposed in conduit 36 is heat exchanger 38 which provides heat exchange means for transferring heat energy and to thereby vaporize the feed 20 conversion enhancing composition.
The following example is provided to further illustrate the present invention.
EXAMPLE
The following two comparisons illustrate the promotion of coke 5 spalling by the addition of a tin compound without the addition of a silicon compound:
An expenment~l ethane cracker equipped with a HK4M alloy tube feeding 44 lb~r ethane and 13.2 lb/hr steam was fed 300 ppmw sulfur as dimethyl sulfide during cracking, a common tre~llnent in current crackers. Conversion was kept constant at 65% and residence time at 120 milliseconds. Spalled coke collected after the reactor in a dead leg zone upon completion of the 70 hour run amounted to 4 grams/day. This same tube was treated with 100 ppmm tetrabutyl tin, without silicon, for six hours prior to charging ethane. Spalled coke collected after a 70 hour run amounted to 14.5 grams/day. In a separate run, the HK4M
15 tube was treated with 100 ppmm each of tetrabutyltin and hexamethyldisiloxane for six hours prior to charging ethane. Spalled coke was collected over a 100 hour period at a rate of 2.5 grams/day. Data for each of the three experimental runs with the HK4M tube are pres~nte-l in FIG. 2. As can be observed from an analysis of the data, the tin only treatment provides for a significantly greater amount of 20 coke spalling than does the tinlsilicon or the dimethyl sulfide compounds.
An experiment~l ethane cracker equipped with HP Modified alloy tube feeding 25.3 lb/hr ethane and 7.6 lb/hr steam was fed 300 ppmw sulfilr as dimethylsulfide during cracking. Conversion was kept constant at 67% and residence time was 270 milliseconds. Spalled coke collected after the reactor in a dead leg zone upon the completion of a 55 hour run amounted to a daily rate of 2 grams/day. This same tube was treated with tetrabutyltin, without silicon, for six hours prior to charging ethane. Spalled coke collected after a 65 hour run amounted to 24 grams/day, an increase of twelve times colllpa~ed to the sulfur-treated run. In a separate run, the HP Modified tube was treated with 100 ppmm 10 each of tetrabutyltin and tetraethylsilane for six hours prior to charging ethane.
Spalled coke was collected over a three day period at a rate of 2 grams/day. Data for each of the three experimental runs are presented in FIG. 3. As can be observed from the data, the tin only treatment provides for a significantly greater amount of coke spalling than does the tin/silicon or the dimethylsulfide compounds.
Reasonable variations and modifications are possible by those skilled in the art within the scope of the described invention and the appended claims.
METHOD FOR PROMOTING THE SPALLING OF
COKE PRODUCED DURING THE THERMAL CRACKING
OF HYDROCARBONS
The present invention relates to processes for the thermal cracking of hydrocarbons. More specifically, the present invention relates to a method for promoting the spalling of coke produced during the pyrolytic cracking of hydrocarbons.
In a process for producing an olefin compound, a fluid stream containing a saturated hydrocarbon such as ethane, propane, butane, pentane, naphtha, or lui2~lules 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 m~ter1~1 being introduced into the cracking furnace.
Within the furnace, the saturated hydrocarbon is converted into an 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 ~ e of saturated hydrocarbons cont~ining ethane, propane, butane, pentane and naphtha is converted to a mixture of olefinic compounds co~ g ethylene, 5 propylene, butenes, pentenes, and n~phth~lene. Olefinic compounds are an important class of industrial chemicals. For example, ethylene is a monomer or comonnmer 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 10 product stream can also contain appreciable quantities of hydrogen, methane, acetylene, carbon monoxide, carbon dioxide, and pyrolytic products ot_er than the olefinic compounds.
During the thermal or pyrolytic cracking of hydrocarbons, a semi-pure carbon which is termed as "coke" is formed. The coke formed in the cracking 15 process normally deposits upon the surfaces of the cracking tubes of the pyrolytic cracking furnace of such process. The accumulation of coke upon the surfaces of the cracking tubes ultimately requires the shut down of the cracking furnace in order to burn off the coke deposits. The accllm~ tion of coke deposits necessitates the periodic shutdown of the cracking furnace due to the excessive 20 pressure drop across the cracking furnace tubes and the higher furnace temperatures required as a result of the therm~l insulating properties of the deposited coke.
Compositions known as antifoulants have been used to inhibit ~e formation and deposition of coke upon the surfaces of cracking furnace tubes and 5 on the metal surfaces of downstream heat exchangers and other process equipment. In spite of the inhibition in the formation of coke by use of such antifoulants, the coke buildup during the cracking of hydrocarbons still occurs but at a slower rate. It can be desirable for there to be minim~l buildup or deposition of coke upon the cracker tube surfaces. A reduction in coke accllm~ tion on the 10 cracking tubes will increase the run length of a cracking furnace between shutdowns and thereby improve the cracking operation.
It is an object of this invention to provide an illl~,roved process for cracking saturated hydrocarbons to produce olefin end-products.
Another object of this inven*on is to provide a method for limi*ng 15 the deposition or accllmlll~*on of coke upon the tube surfaces of a cracking furnace.
A still further object of this inven*on is to provide a method for promoting the spalling of coke produced during the pyrolytic cracking of coke produced during the pyrolytic cracking of hydrocarbons to prevent, limit, or 20 reduce the buildup of coke deposits upon the cracker tube surfaces to thereby increase cracker furnace run length between shutdowns.
21550~ 33294CA
In accordance with the present invention, spalling of coke produced during the pyrolytic cracking of a hydrocarbon stream is promoted by passing the hydrocarbon stream through a tube of a pyrolytic cracking furnace operated under suitable cracking conditions to thereby produce a cracked product stream. An 5 antifoulant co"~ g tin but having a substantial absence of silicon is added to the hydrocarbon stream in an amount sufficient to promote the spalling of coke produced during the pyrolytic cracking of the hydrocarbon stream.
Another embodiment of the invention includes contacting an antifoulant co,.~ g tin but having a substantial absence of silicon with a tube 10 of a pyrolytic cracking furnace under suitable treatment conditions to thereby provide a treated tube. A hydrocarbon stream is passed through the treated tube which is operated under suitable cracking conditions to thereby produce a cracked product stream having therein spalled coke.
Other objects and advantages of the invention will be apparent from 15 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~tic diagram representing the portion of an ethylene cracking process that includes pyrolytic cracking furnace means and other elements of the novel process;
FIG. 2 is a bar chart showing the amount of coke spalled during ethane cracking from an HK4M alloy tube treated with dimethylsulfide, tin, or a tin/silicon ~ e; and FIG. 3 is a bar chart showing the amount of coke spalled during 5 ethane cracking from an HP Modified alloy tube treated with dimethylsulfide, tin, or tin/silicon.
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 10 hydrocarbon stream is subjected to a severe, high-temperature ellvirol~"~ent to 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, 15 and ~ s of any two or more thereof. Naphtha can generally be described as a complex hydrocarbon mixture having a boiling range of from about 180F to about 400F as d~l~llllil~ed by the standard testing methods of the American Society of Testing M~tçri~l~ (ASTM).
As an optional feature of the invention, the hydrocarbon feed being 20 charged to pyrolytic cracking furnace means can be in~im~tely mixed with a diluent prior to entering pyrolytic cracking furnace means. This diluent can serve 215S04~ 33294CA
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 necessary for obtaining the desired olefin products while reducing the amount ofundesirable reaction products such as hydrogen and methane. Also, the lower partial plC;SSUI~ res~ ing from the ll~lule of the diluent fluid helps in minimi7:ing the amount of coke deposits that form on the furnace tubes. While any suitable diluent fluid that provides these benefits can be used, the prefelled diluent fluid is steam.
The cracking reactions in(luce~ by pyrolytic cracking furnace means can take place at any suitable temperature that will provide the necessary cracking to the desirable end-products or to give a desired feed conversion. The actual cracking temperature utilized will depend upon the composition of the hydrocarbon feed stream and the desired feed conversion. Generally, the crackingtemperature can range uywaldly to about 2000F or greater 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 the range from 1500F to 1800F.
215504~ 33294CA
The cracked hydrocarbon effluent or cracked hydrocarbons or cracked product stream from pyrolytic cracking furnace means will generally be a mixture of hydrocarbons in the gaseous phase. This ~ e of gaseous hydrocarbons can comprise not only the desirable olefin compounds, such as 5 ethylene, propylene, butylene, and amylene, but also, this cracked hydrocarbon stream can contain undesirable co~ ting components that include both oxygenated compounds and acidic compounds and light ends such as hydrogen and methane.
The cracking furnace means of the i~v~nlive method can be any 10 suitable thenn~l cracking ffirn~ce 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 plerelel~ce. Such cracking filrn~ces are equipped with at least one cracking tube to which the hydrocarbon feedstock is charged or fed. The cracking tube provides 15 for and defines a cracking zone contained within the cracking furnace. The cracking furnace is lltili7e-l to release the heat energy required to provide for the necessary cracking temperature within the cracking zone in order to induce cracking reactions therein. Each cracking tube can have any geometry which suitably defines a volume in which cracking reactions can take place and, thus, 20 will have an inside surface. The term "cracking temperature" as 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 ples~ s within the cracking zone will generally be in the range of from about 0 psig to about 100 psig and, preferably from 0 psig to 5 60 psig.
The inventive method provides for or promotes the spalling of coke produced during the pyrolytic cracking of a hydrocarbon stream. It has been discovered that the treatment or treating of the tubes of a cracking furnace with a tin compound only or, more specifically, with a composition having an absence 10 of silicon but comprising tin, coke spalling is promoted. Coke spalling occurs when the coke formed in the cracking tubes during the cracking of hydrocarbon either fails to adhere to the tube surfaces thereby forming a layer of coke or when it is deposited upon the tube surfaces and thereafter chips, flakes or breaks off such surfaces.
Coke spalling for many cracking operations can be undesirable if the spalled coke results in damage or plugging of equipment located down stream from the cracking furnace. However, in situations where the downstream eqllipm~nt can handle the fr~nent~ of spalled coke or, ~lt~ tively, where means is provided which can suitably remove the spalled coke contained in a cracked 20 product stream, the promotion of coke spalling can result in increasing the length of time between decoking of the cracker furnace tubes; because, coke is removed 21~504~
from the tube surfaces by spalling, or it is pr~v~nled from depositing or adhering to the tube surfaces. By increasing the length of time between cracker tube decokings, the furnace production down time is reduced thereby ill,provi~lg cracking furnace productivity and throughput. Thus, if the eqllir)ment used to 5 process the cracker furnace product stream can handle the spalled coke without detriment, or, if suitable removal or separation means for removing at least a portion of the spalled coke contained in the cracked product stream can be provided, then coke spalling can be desired.
A critical aspect of the instant invention is the use of a composition 10 having an absence of a silicon compound but comprising a tin compound. It has been discovered that the tre~tment of the tubes of a cracking furnace in accordance with the methods described herein with a tin compound only, as opposed to a compound co~ both a tin compound and a silicon compound, unexpectedly promotes the sp~lling of coke. When a composition cont~inin~ a combination of 15 tin and silicon is used to treat cracker furnace tubes, on the other hand, excessive spalling of coke is not observed; rather, the formation and deposition of coke appears to be inhibited. Thus, by combining tin and silicon certain antifoulant benefits and properties are obtained that are different from those of an antifoulant col,l;,il~ g a tin compound only or, alternatively, a material having an absence of 20 silicon but comprising tin.
Any suitable form of tin may be utilized in the antifoulant composition having an absence of silicon and comprising tin. Element~l tin, inorganic tin compounds and organic tin compounds as well as ~ ules of any two or more thereof are suitable sources of tin. The term "tin" generally refers to 5 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 starmous sulfide and stannic sulfide; tin sulfates such as stannous sulfate and stannic sulfate; stannic acids such as metastannic acid and thiostannic acid; tin 10 halides such as stannous fluoride, stannous chloride, stannous bromide, stannous iodide, stannic fluoride, stannic chloride, stannic bromide and stannic iodide; tin phosphates such as stannic phosphate; tin oxyhalides such as stannous oxychloride and starmic oxychloride; and the like. Of the inorganic tin compounds those which do not contain halogen are plerelled as the source of tin.
Examples of some organic tin compounds which can be used incl~lde tin carboxylates such as stannous formate, stannous acetate, stannous butyrate, stannous octoate, stannous decanoate, stannous oxalate, stannous benzoate, and stannous cyclohexanecarboxylate; tin thiocarboxylates such as stannous thioacetate and stannous dithioacetate; dihydrocarbyltin bis(hydrocarbyl 20 mercaptoaL~anoates) such as dibutyltin bis(isoocylmercaptoacetate) and dipropyltin bis(butyl mercaptoacetate); tin thiocarbonates such as stannous O-ethyl 215~044 dithiocarbonate; tin carbonates such as stannous propyl carbonate;
tetrahydrocarbyltin compounds such as tetramethyltin, tetraoctyltin, tetradodecyltin, and tetraphenyltin; dihydroc~lJyllin oxides such as dipropyltin oxide; dibutyltin oxide, dioctyltin oxide, and diphenyltin oxide; dihydrocarbyltin S bis(hydrocarbyl mercaptide)s such as dibutyltin bis(dodecyl mercaptide); tin salts of phenolic compounds such as stannous thiophenoxide; tin sulfonates such as stannous ben7~neslllfonate and stannous-p-toluenesulfonate; tin carbamates such as stannous diethylcarbamate; tin thiocarbamates such as stannous propylthioc~l,~ and stannous diethyldithiocarbamate; tin phosphites such as 10 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. Organic tin compounds are 15 preferred over inorganic compounds. At present tetrabutyltin is most preferred.
21~S044 The term "silicon" as used herein refers to silicon sources such as element~l silicon, inorganic silicon compounds and organic silicon compounds as well as mixtures of any two or more thereof.
The antifoulant composition described herein is lltili7e~ in the 5 tre~tment of the surfaces of the cracking tubes of a pyrolytic cracking furnace.
The composition is contacted with surfaces of the cracking tubes either by ~eLIeaLillg the cracking tubes with the antifoulant prior to charging the tubes with a hydrocarbon feed or by adding the antifoulant to the hydrocarbon feed in an amount effective for treating the cracker tubes.
Any method can be used which suitably treats the tubes of a cracking furnace by contacting such tubes with the antifoulant under suitable treatment conditions to thereby provide treated tubes.
The prefel,ed 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 ~ t~ e in the range of from about 300F
to about 500F. The cracking furnace is fired while charging the tubes with the steam so as to provide a superheated steam 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 upwardly 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
21550~9 to 1 600F. It is desirable for the stearn to be charged to the convection section of the cracking furnace, therefore, first passing through the convection section tubes followed by p~sing through the radiant section tubes.
The antifoulant can then be ~(lmixed with the steam being charged 5 to the cracker tubes. The antifoulant can be a~lmixed with the stearn as either a neat liquid or as a mi~ e of the antifoulant with an inert diluent. In any event, it is plefe"ed to vaporize or convert into an aerosol either the neat liquid or the n~lure prior to its introduction into or a~1mixing with the steam. The amount of antifoulant a~lmixed with the stearn can be such as to provide a concentration of the antifoulant in the steam in the range of from about 1 ppmm to about 10,000 ppmm, plerelably, from about 10 ppmm to about 1000 ppmw and, most preferably, from 20 to 200 ppmm.
The ~ ;x~ e of steam and antifoulant is contacted with or charged to the cracker furnace tubes for a period of time sufficient to provide for treated 15 tubes, which when placed in cracking service, will provide or promote an amount of coke sp~lling exceeding that which occurs when the antifoulant includes silicon.
Such time period for pl~lleal~lg the cracker tubes is influenced by the specific geometry of the cracking fumace inchllling its tubes; but, generally, the pretreating time period can range upwardly to about 12 hours, and longer if required. But, 20 preferably, the period of time for the pretreating 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 antifoulant composition is directly a(lmixed with the hydrocarbon feed to the cracking furnace, it can be added in such an amount to be effective in promoting the spalling of coke produced during the pyrolytic cracking of the hydrocarbon feed. Due to the memory effect resulting 5 from the application of the antifoulant the mixing with the hydrocarbon cracker feed is con-lllcte~ r~ lly as required but, preferably, for periods up to about 12 hours. The concentration of the antifoulant in the hydrocarbon cracker feed during treating of the cracking furnace tubes can be in the range of from about 1 ppmm to about 10,000 ppmm, preferably, from about 10 ppmm to about 1000 ppmm and, most preferably, from 20 to 200 ppmm.
Now refellmg to FIG. 1, there is illustrated by schematic representation cracking fumace 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 as tubes 20.
A hydrocarbon feedstock or a mixture of steam and such hydrocarbon feedstock is conducted to the inlet of convection tubes 18 by way of 20 conduit 22 which is in fluid flow co~ lullication with convection tubes 18.
During the treatment of the tubes of cracking furnace 12, the a(lmixtllre of steam 215S0~ 33294CA
and the antifoulant composition can also be conducted to the inlet of 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 5 required tre~tment temperature. The cracked product stream from cracking furnace 12 passes downstream through conduit 24 to sep~lor 26 which defines a zone and provides means for removing at least a portion of the spalled coke contained in the cracked product stream. The spalled coke removed from the cracked product stream passes from separator 26 by way of conduit 28, and the 10 cracked product stream having at least a portion of the spalled coke contained therein removed there~iom passes from sep~lor 26 by way of conduit 30.
To provide for the heat energy necessary to operate cracking furnace 12, fuel gas is conveyed through conduit 32 to burners 34 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 antifoulant composition is conveyed to cracking furnace 12 feed stream through conduit 36 and ~(lmixed prior to the resulting mixture entering cracking furnace 12. Interposed in conduit 36 is heat exchanger 38 which provides heat exchange means for transferring heat energy and to thereby vaporize the feed 20 conversion enhancing composition.
The following example is provided to further illustrate the present invention.
EXAMPLE
The following two comparisons illustrate the promotion of coke 5 spalling by the addition of a tin compound without the addition of a silicon compound:
An expenment~l ethane cracker equipped with a HK4M alloy tube feeding 44 lb~r ethane and 13.2 lb/hr steam was fed 300 ppmw sulfur as dimethyl sulfide during cracking, a common tre~llnent in current crackers. Conversion was kept constant at 65% and residence time at 120 milliseconds. Spalled coke collected after the reactor in a dead leg zone upon completion of the 70 hour run amounted to 4 grams/day. This same tube was treated with 100 ppmm tetrabutyl tin, without silicon, for six hours prior to charging ethane. Spalled coke collected after a 70 hour run amounted to 14.5 grams/day. In a separate run, the HK4M
15 tube was treated with 100 ppmm each of tetrabutyltin and hexamethyldisiloxane for six hours prior to charging ethane. Spalled coke was collected over a 100 hour period at a rate of 2.5 grams/day. Data for each of the three experimental runs with the HK4M tube are pres~nte-l in FIG. 2. As can be observed from an analysis of the data, the tin only treatment provides for a significantly greater amount of 20 coke spalling than does the tinlsilicon or the dimethyl sulfide compounds.
An experiment~l ethane cracker equipped with HP Modified alloy tube feeding 25.3 lb/hr ethane and 7.6 lb/hr steam was fed 300 ppmw sulfilr as dimethylsulfide during cracking. Conversion was kept constant at 67% and residence time was 270 milliseconds. Spalled coke collected after the reactor in a dead leg zone upon the completion of a 55 hour run amounted to a daily rate of 2 grams/day. This same tube was treated with tetrabutyltin, without silicon, for six hours prior to charging ethane. Spalled coke collected after a 65 hour run amounted to 24 grams/day, an increase of twelve times colllpa~ed to the sulfur-treated run. In a separate run, the HP Modified tube was treated with 100 ppmm 10 each of tetrabutyltin and tetraethylsilane for six hours prior to charging ethane.
Spalled coke was collected over a three day period at a rate of 2 grams/day. Data for each of the three experimental runs are presented in FIG. 3. As can be observed from the data, the tin only treatment provides for a significantly greater amount of coke spalling than does the tin/silicon or the dimethylsulfide compounds.
Reasonable variations and modifications are possible by those skilled in the art within the scope of the described invention and the appended claims.
Claims (12)
1. A method for promoting the spalling of coke produced during the pyrolytic cracking of a hydrocarbon stream, said method includes the steps of:
passing said hydrocarbon stream through a tube of a pyrolytic cracking furnace operated under suitable cracking conditions to thereby produce a cracked product stream; and adding an antifoulant containing tin but having a substantial absence of silicon to said hydrocarbon stream in an amount sufficient to promote the spalling of coke produced during the pyrolytic cracking of said hydrocarbon stream to thereby provide said cracked product stream having therein spalled coke.
passing said hydrocarbon stream through a tube of a pyrolytic cracking furnace operated under suitable cracking conditions to thereby produce a cracked product stream; and adding an antifoulant containing tin but having a substantial absence of silicon to said hydrocarbon stream in an amount sufficient to promote the spalling of coke produced during the pyrolytic cracking of said hydrocarbon stream to thereby provide said cracked product stream having therein spalled coke.
2. A method as recited in claim 1, further comprising removing at least a portion of said spalled coke from said cracked product stream.
3. A method as recited in claim 2 wherein the tin is an organotin compound.
4. A method as recited in claim 3 wherein the amount of said antifoulant added to said hydrocarbon stream in the cooling step is such as to give a concentration in said hydrocarbon stream in the range of from about 1 ppmm to about 10,000 ppmm.
5. A method as recited in claim 4 wherein said organotin compound is tetrabutyltin.
6. A method of promoting the spalling of coke produced during the pyrolytic cracking of a hydrocarbon stream, said method includes the steps of:
contacting an antifoulant containing tin but having a substantial absence of silicon with a tube of a pyrolytic cracking furnace under suitable treatment conditions to thereby provide a treated tube; and passing said hydrocarbon stream through said treated tube which is operated under suitable cracking conditions to thereby produce a cracked product stream having therein spalled coke.
contacting an antifoulant containing tin but having a substantial absence of silicon with a tube of a pyrolytic cracking furnace under suitable treatment conditions to thereby provide a treated tube; and passing said hydrocarbon stream through said treated tube which is operated under suitable cracking conditions to thereby produce a cracked product stream having therein spalled coke.
7. A method as recited in claim 6, further comprising:
removing at least a portion of said spalled coke from said cracked product stream.
removing at least a portion of said spalled coke from said cracked product stream.
8. A method as recited in claim 7, wherein the tin is an organotin compound.
9. A method as recited in claim 8, wherein the contacting step further includes utilizing said antifoulant in an admixture with a diluent at a concentration in the range of from about 1 ppmm to about 10,000 ppmm.
10. A method as recited in claim 9, wherein the contacting step is conducted at a temperature in the range of from about 300 F to about 2000 F.
11. A method as recited in claim 10, wherein the contacting step is conducted upwardly to about 12 hours.
12. A method as recited in claim 11, wherein said organotin compound is tetrabutyltin.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29629894A | 1994-08-25 | 1994-08-25 | |
| US08/296,298 | 1994-08-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2155044A1 true CA2155044A1 (en) | 1996-02-26 |
Family
ID=23141439
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002155044A Abandoned CA2155044A1 (en) | 1994-08-25 | 1995-07-31 | Method for promoting the spalling of coke produced during the thermal cracking of hydrocarbons |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0698654A1 (en) |
| JP (1) | JPH08170083A (en) |
| KR (1) | KR100352923B1 (en) |
| CN (1) | CN1072254C (en) |
| AU (1) | AU672943B2 (en) |
| BR (1) | BR9503796A (en) |
| CA (1) | CA2155044A1 (en) |
| TW (1) | TW311147B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100746583B1 (en) * | 2006-09-05 | 2007-08-06 | 엘지석유화학 주식회사 | Coke removal method for reducing cokes generated in the thermal cracking process of hydrocarbon |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4404087A (en) * | 1982-02-12 | 1983-09-13 | Phillips Petroleum Company | Antifoulants for thermal cracking processes |
| US4692234A (en) * | 1986-04-09 | 1987-09-08 | Phillips Petroleum Company | Antifoulants for thermal cracking processes |
| US5284994A (en) * | 1993-01-13 | 1994-02-08 | Phillips Petroleum Company | Injection of antifoulants into thermal cracking reactors |
| WO2012135942A1 (en) * | 2011-04-04 | 2012-10-11 | Litens Automotive Partnership | Clutch mechanism and decoupler device with same |
-
1995
- 1995-07-31 CA CA002155044A patent/CA2155044A1/en not_active Abandoned
- 1995-08-11 AU AU28512/95A patent/AU672943B2/en not_active Ceased
- 1995-08-24 KR KR1019950026388A patent/KR100352923B1/en not_active IP Right Cessation
- 1995-08-24 EP EP95113302A patent/EP0698654A1/en not_active Withdrawn
- 1995-08-24 CN CN95116675A patent/CN1072254C/en not_active Expired - Fee Related
- 1995-08-24 BR BR9503796A patent/BR9503796A/en not_active Application Discontinuation
- 1995-08-24 JP JP7216112A patent/JPH08170083A/en active Pending
- 1995-10-04 TW TW084110365A patent/TW311147B/zh active
Also Published As
| Publication number | Publication date |
|---|---|
| CN1123824A (en) | 1996-06-05 |
| KR100352923B1 (en) | 2002-12-28 |
| EP0698654A1 (en) | 1996-02-28 |
| AU2851295A (en) | 1996-03-28 |
| BR9503796A (en) | 1996-04-16 |
| AU672943B2 (en) | 1996-10-17 |
| JPH08170083A (en) | 1996-07-02 |
| CN1072254C (en) | 2001-10-03 |
| KR960007735A (en) | 1996-03-22 |
| TW311147B (en) | 1997-07-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20040802 |