GB2105362A - Process of steam cracking heavy hydrocarbons and apparatus therefor - Google Patents
Process of steam cracking heavy hydrocarbons and apparatus therefor Download PDFInfo
- Publication number
- GB2105362A GB2105362A GB08224238A GB8224238A GB2105362A GB 2105362 A GB2105362 A GB 2105362A GB 08224238 A GB08224238 A GB 08224238A GB 8224238 A GB8224238 A GB 8224238A GB 2105362 A GB2105362 A GB 2105362A
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- United Kingdom
- Prior art keywords
- steam
- range
- steam cracking
- tubes
- heat flux
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- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 83
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 83
- 238000004230 steam cracking Methods 0.000 title claims abstract description 82
- 238000000034 method Methods 0.000 title claims abstract description 31
- 230000008569 process Effects 0.000 title claims abstract description 29
- 230000004907 flux Effects 0.000 claims abstract description 65
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 23
- 230000008021 deposition Effects 0.000 claims abstract description 7
- 238000010438 heat treatment Methods 0.000 claims description 78
- 239000004215 Carbon black (E152) Substances 0.000 claims description 29
- 239000000203 mixture Substances 0.000 claims description 26
- 239000007789 gas Substances 0.000 claims description 25
- 239000001257 hydrogen Substances 0.000 claims description 21
- 229910052739 hydrogen Inorganic materials 0.000 claims description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 15
- 239000000295 fuel oil Substances 0.000 claims description 15
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 14
- 239000008246 gaseous mixture Substances 0.000 claims description 13
- 238000002485 combustion reaction Methods 0.000 claims description 8
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 7
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 6
- 239000001569 carbon dioxide Substances 0.000 claims description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 6
- 150000002431 hydrogen Chemical class 0.000 claims description 6
- 239000000567 combustion gas Substances 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 4
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 238000011084 recovery Methods 0.000 claims description 2
- 238000005292 vacuum distillation Methods 0.000 claims description 2
- 239000002918 waste heat Substances 0.000 claims description 2
- 125000004429 atom Chemical group 0.000 claims 1
- 239000011541 reaction mixture Substances 0.000 abstract 1
- 238000004227 thermal cracking Methods 0.000 description 19
- 238000005336 cracking Methods 0.000 description 8
- 238000000151 deposition Methods 0.000 description 7
- 239000003921 oil Substances 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- -1 methane Chemical class 0.000 description 3
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000002407 reforming Methods 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 239000011369 resultant mixture Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 230000003685 thermal hair damage Effects 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 210000001364 upper extremity Anatomy 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
- C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G9/14—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
- C10G9/18—Apparatus
- C10G9/20—Tube furnaces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Combustion & Propulsion (AREA)
- General Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
- Hydrogen, Water And Hydrids (AREA)
Abstract
A process and apparatus for steam cracking of heavy hydrocarbons wherein a pair of first and second sequential steam cracking zones are utilized, the first such zone supplying a large heat flux of 10,000 to 70,000 Kcal/m<2>hr to the reaction mixture comprising heavy hydrocarbons and steam, and the second zone supplying a smaller heat flux of 1,500 to 10,000 Kcal/m<2>hr thereto. Deposition of carbon on the inside of a tubular reactor is prevented by steam cracking by the processs described. <IMAGE>
Description
SPECIFICATION
Process of steam cracking heavy hydrocarbons and apparatus therefor
This invention relates to an improved process for steam cracking heavy hydrocarbons to produce hydrogen, carbon monoxide, carbon dioxide and lower hydrocarbons, and also relates to an apparatus for performing the process.
Heavy oils (inclusive of all three grades prescribed by the Japan Industrial Standards, i.e., heavy oils A, B and C), vacuum distillation residues, tar, pitch and the like, can be employed as heavy hydrocarbon feedstocks in the present invention.
As a conventional process for producing gases from heavy oil, there is known a process as described in Japanese Laid-Open Patent Specification No. 101804/1979. In the above prior art process, a mixture of heavy oil and steam is passed through a thermal cracking zone which comprises an externally heated, high-temperature space, so as to vaporize and volatilize the heavy oil. The thusvaporized and volatilized heavy oil is passed through a catalyst-containing reforming zone so as to be converted into a gaseous mixture containing hydrogen as its principal component.According to the above process, suitable atomization of the heavy oil feedstock and provision of a thermal cracking zone are said to solve the problem that was caused in the prior art when fine liquid droplets of the heavy oil are continuously brought into contact with the catalytic layer, namely, that carbon deposits accumulate on the surface of the catalytic layer, thereby clogging the catalytic layer.
However, carbon can still be deposited in the course of heating the heavy oil to its reforming temperature, as described in Japanese Laid-Open Patent Specification No. 1 54303/1 980. Thus, the above prior art process of Japanese Laid-Open Patent Specification No. 101804/1979 induces adhesion of carbon to the inner wall of the thermal cracking zone, particularly when the atomized heavy oil is at a relatively low temperature upon contact with the inner wall of the thermal cracking zone. This carbon deposition tends to hamper long-term operation.
Accordingly, it is desired to avoid adhesion of carbon in the thermal cracking zone in order to provide steady operation of the process described in Japanese Laid-Open Patent Specification No.
101 804/1979 for long periods of time.
Cracking furnaces have heretofore been used to subject naphtha to thermal cracking in order to produce ethylene. A typical example of such a cracking furnace, as shown in Japanese Patent
Publication No. 7388/1976, comprises vertical reactor tubes suspended in a heating furnace so that naphtha can be subjected to thermal cracking while itflows through the reactor tubes. If such a cracking furnace is used to subject heavy oil to thermal cracking, the inner wall of each reactor tube will become covered with carbon as a result of cracking of the heavy hydrocarbons, thereby hindering smooth passage of gas through the reactor tube and causing an increase in the temperature of the reactor tube, which shortens its service life.Furthermore, because the thermal cracking of heavy hydrocarbons requires higher temperatures than those used for thermal cracking of naphtha, such a conventional cracking furnace cannot be used to subject heavy hydrocarbons to thermal cracking in order to obtain a hydrogen-rich gas or ethylene.
The above-mentioned Japanese Laid-Open Patent Specification No. 101804/1979 proposes to produce a gas consisting principally of hydrogen by thermal cracking of heavy hydrocarbons. An apparatus which is used in the practice of the above process comprises an atomizer, thermal cracking means and a reactor. In this process, however, it is still difficult to prevent carbon sticking on the inner wall of the thermal cracking means, and, therefore, it is not possible to achieve long-term use of the materials constituting the thermal cracking means, if the atomizer and the thermal cracking means are arranged conventionally. Furthermore, the above apparatus requires certain additional facilities subsequent to the reactor.
An object of this invention is to provide a process which practically avoids the sticking of carbon on the inner wall of a reactor when heavy hydrocarbons are externally heated, without bringing them into contact with any catalyst, in order to steam crack them.
Another object of this invention is to provide an apparatus for thermal cracking of heavy hydrocarbons which is free from the problem of carbon sticking to the inner walls of tubular reactors thereof and seldom develops thermal damage of its tubular reactors.
According to the present invention, there is provided a process for steam cracking heavy hydrocarbons to form a hydrogen-containing gas, which comprises the steps of flowing a heavy hydrocarbon feedstock together with steam, through one or more catalyst-free tubular first reactors in a first steam cracking zone having a heat flux in the range of 10,000 to 70,000 Kcal/m2hr on the inner wall of the or each tubular reactor, at a flow rate of 4 to 100 m/sec and a residence time within the tubular reactor(s) of 0.05 to 3 seconds, so as to rapidly heat the heavy hydrocarbon feedstock and steam to a temperature in the range of 8000 to 1 ,0000C;; and then flowing the gaseous mixture discharged from said first steam cracking zone, through one or more catalyst-free tubular second reactors in a second steam cracking zone having a smaller heat flux in the range of 1,500 to 10,000
Kcal/m2hr, at a flow rate of 4 to 100 m/sec and a residence time within the or each second tubular reactor of 0.1 to 6 seconds so as to increase the temperature of the gaseous mixture to a temperature in
the range of 8500 to 1 ,1 000C, thereby subjecting the heavy hydrocarbons to steam cracking and
producing said hydrogen-containing gas.
The process can advantageously be so practised that the residence time in the or each second
tubular reactor is approximately twice as long as the residence time in the or each first tubular reactor,
the heat flux in the or each first tubular reactor is from 4 to 14 times larger than the heat flux in the or
each second tubular reactor and the temperature of the hydrogen-containing gas is discharged from the
second steam cracking zone from 500 to 1 000C higher than the temperature of the gaseous mixture
discharged from the first steam cracking zone.
The invention also provides an apparatus for use in steam cracking heavy hydrocarbons,
comprising a first heating furnace into which a plurality of tubes extend vertically downwardly through
an upper wall thereof, mixers provided at the upper ends of the tubes, each to feed into its respective
tube a mixture comprising heavy hydrocarbon feedstock and steam, said heavy hydrocarbons and steam
being supplied to the mixers in a given proportion from respective headers therefor, each of the tubes
extending at least once through the first heating furnace vertically downwardly and then in a reverse
direction vertically upwardly so as to allow the intratubular flow of each of said tubes to take a
predetermined residence time in passing through the first heating furnace; the said furnace having one
or more first combustion heaters arranged on its interior other than on its upper wall adapted to
radiantly heat each of the said intratubularfows to a temperature in the-range of 8000 to 1 ,0000C with
a heat flux in the range of 10,000 to 70,000 Kcal/m2hr on the inner wall of each tube, the apparatus
further comprising a second heating furnace through which each of said tubes, or further tubes
connected therewith, extend at least once vertically downwardly, then in a reverse direction vertically
upwardly so as to allow intratubular flow in the second furnace to take a predetermined residence time
therein, the second furnace having one or more second combustion heaters arranged on its interior
adapted to radiantly heat each intratubular flow to a temperature in the range of 8500 to 1,1 000C with
a heat flux in the range of 1,500 to 10,000 Kcal/m2hr, each of the said tubes further extending
outwardly through an upper wall of the second heating furnace and connecting with an external outlet
header in which all the said intratubular flows are combined together.
In the following description, the invention is explained in more detail by way of example only.
In practising the present method, a feed stream mixture of heavy hydrocarbons and steam can be
passed successively through a plurality of tubular reactors in a first steam cracking zone in which a large
heat flux is applied and then successively through a plurality of tubular reactors in a second steam cracking zone in which a smaller heat flux is applied. The large heat flux transferred across the inner wall of each tubular reactor in the first steam cracking zone to the mixture of the heavy hydrocarbon and steam in that reactor will be in the range of from 10,000 to 70,000 Kcal/m2hr, and preferably 40,000 to 70,000 Kcal/m2hr. The heat flux across the inner wall of each tubular reactor in the second steam cracking zone will range from 1,500 to 10,000 Kcal/m2hr. In each steam cracking zone, the flow rate of the feed stream is 4 to 100 m/sec.The residence time of the feed stream is 0.05-3 seconds in the first steam cracking zone and 0.1-6 seconds in the second steam cracking zone. The resultant steam cracking products are at 8000 to 1 ,0000C at the outlet of the first steam cracking zone and at 8500 to 1 ,1 000C at the outlet of the second steam cracking zone. While passing through these steam cracking zones, the heavy hydrocarbons are subjected to steam cracking and are converted into a gaseous mixture consisting essentially of hydrogen, carbon monoxide, carbon dioxide, and saturated and unsaturated lower hydrocarbons.
It is particularly important, in the steam cracking of heavy hydrocarbons, rapidly to raise the temperature of the heavy hydrocarbons to the desired steam cracking temperature. For this purpose, it
is necessary to carry out the heating of the feed mixture of heavy hydrocarbons and steam by supplying
a large heat flux thereto. It is desirable simultaneously to raise the temperature of the heavy
hydrocarbons and steam as high as feasible. Therefore, it is desirable to preheat the heavy hydrocarbons to a temperature of 4500C or less, particularly 3000 to 4500 C, before feeding the heavy hydrocarbons into the first steam cracking zone. Moreover, it is preferred to employ steam that is superheated to a temperature of 6000 to 1 ,0000C, preferably 8000 to 9500C, before it is fed into the first steam
cracking zone.The ratio of the number of moles of feed steam to the carbon atoms in the heavy
hydrocarbon feedstock, namely, the steam/carbon (S/C) ratio, is preferably 2:1 or higher, for example in the range of 3:1 to 6:1. The steam can optionally contain oxygen, hydrogen and/or carbon dioxide mixed therein.
The heavy hydrocarbons supplied to the first steam cracking zone, which is externally heated so as to exhibit the stated large heat flux, are caused to pass together with the steam through the first cracking zone at a flow rate of 4 to 100 m/sec, preferably 30 to 80 m/sec, and with a residence time therein which is preferably 0.05 to 1 second. The resulting mixture reaches a temperature of 8000 to 1.0000C, preferably 8500 to 9500C, at the outlet of the first steam cracking zone. The inlet pressure of the first steam cracking zone is preferably 5 to 40 Kg/cm2G, for instance 10 to 30 Kg/cm2G. The inner diameter of each tubular reactor in the first steam cracking zone is preferably 30 to 200 mm, for example 50 to 100 mm.
If any of the parameters of heat flux, flow rate and residence time were to attain values outside the above-recited ranges for the first steam cracking zone, the heating of the heavy hydrocarbon feedstock and steam might not be carried out sufficiently promptly, thereby causing deposition of carbon, or the temperature of the first steam cracking zone might increase to an excessive level, thereby leading to the problem of damage to the tubular reactors.
As it flows through the first steam cracking zone the mixture of the heavy hydrocarbons and steam passes in a short period of time through the carbon depositing temperature range (4000 to 5000C) and then it reaches the desired higher temperature. In the course of the above heating step, part of the heavy hydrocarbon feedstock is subjected to thermal cracking and the formation of a small amount of carbon may be observed. However, the thus-produced carbon is carried away by the high-speed flow without sticking to the inner wall of each tubular reactor of the first steam cracking zone.
The resulting gaseous mixture from the first steam cracking zone is then caused to enter the second steam cracking zone which exhibits the stated small heat flux, wherein the dehydrogenation of lower hydrocarbons in the gaseous mixture and the conversion of the thus-dehydrogenated lower hydrocarbons into hydrogen, carbon monoxide and carbon dioxide by steam is completed. Therefore, it is sufficient to supply to the second steam cracking zone a quantity of heat equal to or somewhat larger than that required to complete the various endothermic reactions which take place there. The heat flux supplied to the second steam cracking zone, which is in the range of from 1,500 to 10,000 Kcal/m2hr, is preferably 5,000 to 10,000 Kcal/m2hr.The flow rate of the gaseous mixture in the second steam cracking zone can again be 4 to 100 m/sec, preferably 30 to 80 m/sec, and the residence time therein is preferably 0.1 to 2 seconds. The preferred inner diameter of each tubular reactor in the second steam cracking zone is 30 to 200 mm, for instance 50 to 100 mm. The temperature of the gas at the outlet of the second steam cracking zone can be 8500 to 1,100 C, preferably 9000 to 1 ,0000C.
If any of the parameters of heat flux, flow rate and residence time for the second steam cracking zone were to attain values outside the above-defined ranges, the thermal cracking reaction might not proceed to a satisfactory extent, or the temperature might be raised to an excessively high value, thereby decreasing the strength of the tubular reactors.
Each of the two steam cracking zones can be constructed by adjusting the arrangement or capacity of their respective combustion heaters, that is, each respective heating burner for the respective tubular reactors, in order to change the heat flux in the tubular reactors. When such an adjustment of the heat flux is achieved only by changing the locations of the heating burners, it is necessary to provide more heating burners for the tubular reactors at locations corresponding to the first steam cracking zone where the larger heat flux is needed and fewer heating burners at locations corresponding to the second steam cracking zone where the smaller heat flux is needed. An apparatus which will be described below, can advantageously be employed to achieve the required adjustment of heat flux.
The invention is now further described by way of example with reference to the sole accompanying drawing, which is a vertical schematic cross section through an apparatus forming one preferred embodiment of this invention.
The apparatus for use in steam cracking heavy hydrocarbons comprises a box-like first heating furnace. A group of tubes extends vertically downwardly into the first heating furnace through an upper wall thereof and a mixer is provided at the upper extremity of each of the tubes to feed a mixture of heavy hydrocarbons and steam into its associated tube, which heavy hydrocarbons are supplied in a determined proportion from a heavy hydrocarbon header and which steam is supplied from a steam header. Each of the tubes extends through the first heating furnace at least once vertically downwardly, then in a reverse direction vertically upwardly so as to allow the intratubular flow to spend a predetermined residence time in the first heating furnace.One or more combustion heaters is/are arranged on a side wall and/or bottom wall of the first heating furnace and adapted to radiantly heat each intratubular flow to temperatures within the temperature range of 8000 to 1,000 C with a heat flux in the range of 10,000 to 70,000 Kcal/m2hr on the inner wall of each tube. Each of said tubes then extends through a second heating furnace at least once vertically downwardly, then in a reverse direction vertically upwardly so as to allow the intratubular flow to spend a predetermined residence time in the second heating furnace.One or more second combustion heaters is/are arranged on a side wall and/or a bottom wall of the second heating furnace to radiantly heat each intratubular flow to temperatures within the temperature range of 8500 to 1,1 000C with a heat flux in the range of 1,500 to 10,000 Kcal/m2hr; and each tube further extending through the upper wall or bottom wall of the second heating furnace to a position outside the second heating furnace at which position each tube is connected to an outlet header in which all the intratubular flow from al of the tubes are combined together.
According to the illustrated embodiment, a first radiant heating zone A in the form of a boxlike heating furnace, and a second radiant heating zone B which is also a boxlike heating furnace, are arranged with their upper portions in communication with each other. Both of the heating zonesA and B are supported by a column 10, the exterior of which is covered by fireproof walls 9. Above the first heating zone A there is provided an inlet header 2 for heavy hydrocarbon feedstock. The inlet header 2 is connected through a plurality of feed introducing conduits 14 to the upper ends of a plurality of tubular reactors 5 in the form of continuous, elongated tubes made of a heat-resistant metallic material.
Only one tubular reactor 5 is shown in the drawing, but it will be understood that there are a plurality of such reactors arranged in parallel with each other, within the first heating zone A. A steam-introducing header 1 is provided at a location parallel to the inlet header 2 for the heavy hydrocarbon feed. The steam-introducing header 1 is coupled through a plurality of steam-introducing conduits 1 5 to the upper ends of the tubular reactors 5. Each tubular reactor 5 is provided at its upper end with a mixer 1 6, such as an injector mixer, adapted to mix the heavy hydrocarbon feedstock and steam together and to inject the thus-produced mixture downwardly into each tubular reactor 5.The mixer 1 6 serves to form a mixed flow of the heavy hydrocarbon feedstock and steam which are fed, respectively, from the inlet conduit 14 for the heavy hydrocarbon feedstock and the steam-introducing conduit 1 5. The mixer 1 6 can be of any suitable type so long as it is capable of forming a mixed flow of heavy hydrocarbons and steam. It is also possible to provide an atomizer which forms a thin layer of steam around the abovementioned mixed flow.
The tubular reactors 5 are suspended by a spring hanger 1 3. The inlet header 2 for the heavy hydrocarbon feed and the steam-introducing inlet header 1 are suspended above the upper wall of the first heating zone A of large heat flux. Each tubular reactor 5 has a first leg that extends vertically downwardly in the first heating zoneA, it is reversely bent into a U-shape at the lower portion of the heating zoneA, and it has a second leg that extends vertically upwardly in said first heating zone. The upper end of the second leg of the tubular reactor extends from the upper part of the heating zone A into the upper part of the second heating zone B of small heat flux. The first heating zone A is provided with side wall burners 4 and floor burners 8.
In the heating zone B, tubular reactors 5', each of which is integrally connected to one of the corresponding tubular reactors 5, are disposed vertically. Each of the tubular reactors 5', as shown in the drawing, has two U-shaped sections connected in series and offset sidewardly from each other.
Each U-shaped section is comprised of a vertically downwardly extending leg, a vertically upwardly extending leg and a U-shaped portion connecting the lower ends of said legs. The discharge end of each tubular reactor 5' extends upwardly to a point above the second heating zone B, at which point it communicates with an outlet header 11 for the thus-produced gases. The tubular reactors 5' and outlet header 11 are suspended respectively by spring hangers 12', 1 2. Since each of the tubular reactors 5 and 5' is suspended from above the heating zonesA and B, any thermal expansion of the tubular reactors 5, 5' will be released downwardly and no thermal stress will develop in the tubular reactors 5, 5'.
Furnace floor burners 8' are provided in the heating zone B. Inspection windows 3, 6, 3' and 6' are formed on the side walls of the heating zones A and B so as to permit observation of the interiors of the furnaces. A substantially box-shaped bridge section C is provided above the upper end of the column 10 and communicates via apertures therein with the upper ends of the heating zone A of large heat flux and the second heating zone B of small heat flux for the purpose of collecting the combustion gases produced in the heating zones A and B. The bridge section C has a flue extending upwardly from the central portion thereof. The flue contains a convection heating section 1 7 where waste-heat recovery facilities, such as a preheater 18, are provided.Manholes 7 and 7' allow operators or a maintenance crew to enter the interior of the apparatus when the heating operation has been suspended.
When heavy hydrocarbons are subjected to steam cracking in the above apparatus, the heavy hydrocarbon feedstock is supplied from the inlet header 2, then passes through the inlet conduits 14 to the mixers 1 6. Steam is supplied from the steam-introducing header 1, then passes through the steamintroducing conduits 15, to the mixers 1 6. In the mixers 16, the heavy hydrocarbon feedstock is mixed with and diluted by the steam, and the mixture is then injected into the tubular reactors 5. The heating zone A of large heat flux, which houses the tubular reactors 5, is maintained at an elevated temperature by means of the burners 4, 8.The mixture of the heavy hydrocarbons and steam is rapidly heated to 8000 to 1.0000C and is subjected to steam cracking by the large heat flux in each tubular reactor 5.
Then, the resultant mixture from each tubular reactor 5 enters the corresponding tubular reactor 5' in the heating zone B of small heat flux, where it is subjected to further steam cracking and, at the same time, is further heated to 8500 to 1,100 C. Steam cracking of the mixture is completed at the last portion of each tubular reactor 5', and the resulting gases flow into the outlet header 11 , from whence they are passed to subsequent treatment facilities.
Because the temperature of the mixed feed is low to the first heating zone A is low, it is necessary to supply a great amount of heat to the interior of the heating zone A so that the intertubular feed mixture can be provided with a large heat flux through its corresponding tubular reactor 5. On the other hand, it is necessary to make smaller the heat flux to be supplied to the mixture flowing through each tubular reactor 5' in order to protect from damage the tubular reactors 5' in the heating zone B of smaller heat flux. Thus, it is necessary to make the quantity of heat fed into the interior of the heating zone B smaller and, instead of supplying a larger quantity of heat, make the overall length of each tubular reactor 5' longer than the overall length of each of the tubular reactors 5 in the heating zone A so that the residence time of the feed mixture in the heating zone B can be prolonged. Combustion gases which are discharged at the upper ends of the heating zones A and B enter the convection heating section 1 7 and, after heat is recovered therefrom, are discharged as exhaust gas outside the apparatus.
As indicated by the disposition of the tubes 5' in the drawing, the apparatus of the invention can be built in a double arrangement with two steam cracking apparatuses as described above built in a mirror-image relationship, so that a common, enlarged double heating zone B is utilized, and the tubular reactors 5' of each apparatus connect to a common outlet header 11.
The steam-cracked mixture obtained in accordance with this invention contains hydrogen, carbon monoxide, carbon dioxide, saturated lower hydrocarbons such as methane, and unsaturated lower hydrocarbons such as ethylene, propylene and butadiene. In order to obtain a gas consisting principally of hydrogen, it is necessary to convert such hydrocarbons into hydrogen and carbon monoxide by bringing the steam-cracked mixture into contact with a catalyst which is made mainly of an oxide of an alkaline earth metal, such as calcium oxide, and alumina, but is substantially free of impurities such as silicon oxide. Needless to say, a variety of known processes other than this one can be employed to convert such a steam-cracked mixture into a gas consisting principally of hydrogen.
Since the present invention makes it possible to raise the temperature of a mixture of heavy hydrocarbons and steam to a desired steam cracking temperature rapidly, the residence time of the mixture in the carbon-depositing temperature range is very short and, therefore, the deposition of carbon can thus be minimized, thereby successfully avoiding the deposition of carbon in the tubular reactors.
In an apparatus according to this invention, a mixture of heavy hydrocarbons and steam is subjected to a large heat flux and is rapidly heated within tubular reactors in the first heating zone of the large heat flux. Thus, the inner walls of the tubular reactors can be kept free of carbon deposition, which would otherwise occur during the cracking of heavy hydrocarbons. The cracking of heavy hydrocarbons is promoted further as the above mixture passes through tubular reactors in the second heating zone of small heat flux, whereby a cracked gas of a desired composition is obtained. Since the tubular reactors are exposed to a relatively small heat flux in the second heating zone, damage to the tubular reactors due to high temperatures is extremely slight despite the high temperature of the feed gas that passes through the tubular reactors can be considerably prolonged.The apparatus according to this invention achieves an extremely high degree of overall thermal efficiency because combustion gases produced in both of the heating zones are gathered into the convection heating section and the heat content thereof can be recovered there.
The present invention will hereinafter be described in further detail with reference to the following examples and comparative examples.
EXAMPLES 1-4
Hairpin-shaped (U-shaped) tubular reactors of a predetermined inner diameter and length were disposed, as shown in the accompanying drawing, in a large heat flux heating zone A and small heat flux heating zone B of a heating furnace to form a steam cracking zone of large heat flux and another steam cracking zone of small heat flux.
Heavy hydrocarbons were supplied together with superheated steam of a predetermined temperature into the tubular reactors in the steam cracking zone of large heat flux of a steam cracking apparatus constructed as described above and as shown in the drawing.
After continuous operation for 100 hours, the reaction apparatus was then disassembled for visual inspection of the interiors of the tubular reactors to determine the amount of carbon stuck thereon.
Operation conditions and inspection results are shown respectively in Table 1 and Table 2.
TABLE 1
Example No. 1 2 3 4 Steam cracking zone A of large heat flux: inner diameter (mm) 70 70 70 70 Tubular reactors, length (mm) ' 22 22 22 22 Heat flux (Kcal/m2hr) 65,000 45,000 68,000 15,000 Flow rate (m/sec) 47 j 33 50 15 Outlet temp. ( C) 890 890 890 890 Steam cracking zone B of small heat flux: Tubular reactors, inner diameter (mm) 70 70 70 70 Tubular reactors, length (m) 44 44 44 44 Heat flux (Kcal/m2hr) 8,000 5,600 8,400 2,500 Flow rate (m/sec) 52 38 55 20 Outlet temp. ( C) 940 940 940 940 Heavy hydrocarbon Heavy Heavy Heavy Heavy feed oilC oil C oil C oil C Amount of heavy hydrocarbon feed supplied (kg/hr) 350 250 370 110 Temperature of heavy oil feed supplied ( C) 350 350 350 350 Amount of steam supplied (kg/hr) 2,240 1,570 2,350 700 Temperature of steam supplied ( C) 900 900 900 900 Reaction pressure (kg/cm2G) 18 18 18 18 TABLE 2
Example No. 1 2 3 4 Presence of carbon stuck in tubular reactors: Steam cracking zone A of large heat flux none none none none Steam cracking zone B of small heat flux none none none none Composition of gas at the outlet of the steam cracking zone B of small heat flux: H2 (vol. %) 43.6 46.8 41.4 51.0 CO (vol. %) 13.5 15.3 13.0 15.7 CO2 (vol. %) 9.4 12.9 8.5 14.0 C2H4 (vol. %) 23.2 20.6 24.6 16.4 C3H6 (vol. %) 4.5 1.9 5.0 1.2 CH4 (vol. %) 3.5 0.8 3.8 0.5 Other gases (vol. %) 2.3 1.7 3.7 1.2 COMPARATIVE EXAMPLES 1-4
The procedures of Examples 1-4 were repeated under operation conditions outside the ranges of the present invention. After continuous operation for 24 hours, the interior of each tubular reactor was visually checked to determine the amount of carbon stuck on the interior of the tubular reactors. The operation conditions and experimental results are summarized respectively in Table 3 and Table 4.
TABLE 3
Comparafive Example No. 1 2 3 4 Steam cracking zone A of large heat reflux: Tubular reactors, inner diameter (mm) 70 70 70 70 Tubular reactors, length (m) ~ 22 22 22 22 Heat flux (Kcal/m2hr) 8,000 90,000 5,000 100,000 Flow rate (m/sec) 47 33 - 3.3 120 Outlet temp. (OC) 750 1,070 900 770 Steam cracking zone B of small heat flux: Tubular reactors, inner diameter (mm) 70 70 70 70 Tubular reactors, length (m) 44 44 44 44 Heat flux (Kcal/m2hr) 8,000 8,000 1,000 12,000 Flow rate (m/sec) 52 38 3.6 130 Outlet temp. (OC) 800 1,130 960 830 Heavy hydrocarbon Heavy Heavy Heavy Heavy feed oil C oil C oil C oil C Amount of heavy hydrocarbon feed supplied (kg/hr) 350 350 35 900 Temperature of heavy oil feed supplied ( C) 350 350 350 350 Amount of steam supplied (kg/hr) 2,240 2,240 1 57 5,720 Temperature of steam supplied (OC) 900 900 900 900 Reaction pressure (kg/cm2G) 18 18 18 18 TABLE 4
Comparative Example No. 1 2 3 4 Presence of carbon stuck in tubular reactors: Steam cracking zone A of large heat flux stuck stuck stuck stuck Steam cracking zone B of small heat flux stuck stuck stuck stuck Composition of gas at the outlet of the steam cracking zone B of small heat flux: H2 (vol. %) 22.0 56.0 54.0 27.0 CO (vol. %) 4.1 12.6 12.7 6.5 C (vol. %) 1.5 14.3 13.0 5.1 C2H4 (vol. %) 28.0 14.1 16.4 25.2 C3H6 (vol. %) 26.0 1.0 1.5 24.6 CH4 (vol. %) 10.0 0.5 0.7 6.5 Other gases (vol. %) 8.4 1.5 1.7 5.1
Claims (20)
1. A process for steam cracking heavy hydrocarbons to form a hydrogen-containing gas, which comprises the steps of flowing a heavy hydrocarbon feedstock together with steam, through one or more catalyst-free tubular first reactors in a first steam cracking zone having a heat flux in the range of 10,000 to 70,000 Kcal/m2hr on the inner wall of the or each tubular reactor, at a flow rate of 4 to 100 m/sec and a residence time within the tubular reactor(s) of 0.05 to 3 seconds, so as to rapidly heat the heavy hydrocarbon feedstock and steam to a temperature in the range of 8000 to 1 ,0000C;; and then flowing the gaseous mixture discharged from said first steam cracking zone, through one or more catalyst-free tubular second reactors in a second steam cracking zone having a smaller heat flux in the range of 1,500 to 10,000 Kcal/m2hr, at a flow rate of 4 to 100 m/sec and a residence time within the or each second tubular reactor of 0.1 to 6 seconds so as to increase the temperature of the gaseous mixture to a temperature in the range of 850" to 1 ,1000C, thereby subjecting the heavy hydrocarbons to steam cracking and producing said hydrogen-containing gas.
2. A process according to Claim 1, wherein the heat flux in the first zone is in the range of 40,000 to 70,000 Kcal/m2hr, the heavy hydrocarbons and steam pass through the said first tubular reactor(s) at a flow rate of 30 to 80 m/sec with a residence time therein of 0.05 to 1 second, and said heavy hydrocarbons and steam are thereby heated to a temperature in the range of 8500 to 9500C; and the said smaller heat flux is in the range of 5,000 to 10,000 Kcal/m2hr, the said gaseous mixture passes through the second tubular reactor(s) at a flow rate of 30 to 80 m/sec with a residence time therein of 0.1 to 2 seconds, and the said gaseous mixture is thereby heated to a temperature in the range of 9000 to 1,0000C.
3. A process according to Claim 1 or Claim 2, wherein the heavy hydrocarbon feedstock and steam are injected at a pressure of 5 to 40 Kg/cm2G at the inlet of the or each first tubular reactor, the latter being an elongated, continuous metallic tube having an inner diameter in the range of 30 to 200 mm.
4. A process according to Claim 3, wherein the said pressure is 10 to 30 Kg/cm2G, and the said inner diameter is in the range of 50 to 100 mm.
5. A process according to Claim 1, wherein the ratio of the gram molecules of said steam to the gram atoms of carbon in said heavy hydrocarbon feedstock is in the range of 3:1 to 6:1.
6. A process according to any of Claims 1 to 5, wherein the heavy hydrocarbon feedstock is
selected from heavy oil, vacuum distillation residue, tar and pitch.
7. A process according to Claim 6, wherein the hydrocarbon feedstock is heavy oil C.
8. A process according to any of Claims 1 to 7, which is performed to yield a hydrogen-containing
gas consisting essentially of hydrogen, carbon monoxide, carbon dioxide, saturated lower hydrocarbons
and unsaturated lower hydrocarbons.
9. A process according to any of Claims 1 to 8, wherein said heavy hydrocarbon feedstock and
steam are heated in said first steam cracking zone so as to pass sufficiently rapidly through the
temperature range of 4000 to 5000C that deposition of carbon on the inner wall of the or each first
tubular reactor is minimized.
10. A process according to Claim 1 in which the residence time in the or each second tubular
reactor is approximately twice as long as the residence time in the or each first tubular reactor, the heat
flux in the or each first tubular reactor is from 4 to 14 times larger than the heat flux in the or each
second tubular reactor and the temperature of the hydrogen-containing gas is discharged from the
second steam cracking zone from 500 to 1 000C higher than the temperature of the gaseous mixture discharged from the first steam cracking zone.
11. An apparatus for use in steam cracking heavy hydrocarbons, comprising a first heating furnace into which a plurality of tubes extend vertically downwardly through an upper wall thereof, mixers provided at the upper ends of the tubes, each to feed into its respective tube a mixture comprising heavy hydrocarbon feedstock and steam, said heavy hydrocarbons and steam being supplied to the mixers in a given proportion from respective headers therefor, each of the tubes extending at least once through the first heating furnace vertically downwardly and then in a reverse direction vertically upwardly so as to allow the intratubular flow of each of said tubes to take a predetermined residence time in passing through the first heating furnace; the said furnace having one or more first combustion heaters arranged on its interior other than on its upper wall adapted to radiantly heat each of the said intratubular flows to a temperature in the range of 8000 to 1 ,0000C with a heat flux in the range of 10,000 to 70,000
Kcal/m2hr on the inner wall of each tube, the apparatus further comprising a second heating furnace through which each of said tubes, or further tubes connected therewith, extend at least once vertically downwardly, then in a reverse direction vertically upwardly so as to allow intratubular flow in the second furnace to tal < e a predetermined residence time therein, the second furnace having one or more second combustion heaters arranged on its interior adapted to radiantly heat each intratubularflow to a temperature in the range of 8500 to 1,1 000C with a heat flux in the range of 1,500 to 10,000
Kcal/m2hr, each of the said tubes further extending outwardly through an upper wall of the second heating furnace and connecting with an external outlet header in which all the said intratubular flows are combined together.
12. An apparatus as claimed in Claim 11 further comprising a bridge section in communication with the two heating furnaces, such that the tubes, at the end of each of the vertically upwardly extending sections thereof in the first heating furnace then extend laterally through the bridge section into the second heating furnace to communicate with the uppermost ends of each of said vertically downwardly extending sections of the tubes in the second heating furnace.
13. An apparatus as claimed in Claim 12, wherein the bridge section is a substantially box-shaped structure having apertures at opposing lower sides thereof, which apertures allowing communication with said first and second heating furnaces, the apparatus further having means positioned above said apertures for recovery of waste heat from combustion gas produced by the said first and second combustion heaters.
14. An apparatus as claimed in Claim 11, 12 or 13, further comprising spring hangers from which the said tubes are supportedly suspended such that thermal expansion of the tubes only occurs downwardly.
1 5. An apparatus as claimed in any of Claims 11 to 14, wherein each of the tubes in the second furnace extends twice vertically downwardly then vertically upwardly to form two parallel, U-shaped tube sections therein connected by a laterally extending tube section in communication with the uppermost end of the vertically upwardly extending section of the first of the two U-shaped sections and the uppermost end of the vertically downwardly extending section of the second of the two U-shaped sections.
16. An apparatus as claimed in any of Claims 11 to 1 5, wherein the said tubes each comprise elongated, continuous, heat resistant metallic tubing having an inner diameter in the range of 30-200 mm.
17. An apparatus as claimed in Claim 16, wherein the said inner diameter is in the range of 50 -100 mm.
1 8. An apparatus for steam cracking of heavy hydrocarbons comprising a pair of apparatuses as claimed in any of Claims 11 to 1 7 and utilizing a single, common enlarged second heating furnace and being in a mirror image relationship such that the tubes of each of said apparatuses connect to a single, common outlet heater.
1 9. A process for steam cracking heavy hydrocarbons to form a hydrogen-containing gas, substantially as herein described by way of example with reference to the accompanying drawing.
20. Apparatus for steam cracking heavy hydrocarbons to form a hydrogen-containing gas, substantially as herein described with reference to and as shown in the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56136003A JPS5837086A (en) | 1981-08-29 | 1981-08-29 | Method and apparatus for steam cracking of heavy hydrocarbon |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2105362A true GB2105362A (en) | 1983-03-23 |
| GB2105362B GB2105362B (en) | 1985-04-11 |
Family
ID=15164912
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08224238A Expired GB2105362B (en) | 1981-08-29 | 1982-08-24 | Process of steam cracking heavy hydrocarbons and apparatus therefor |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5837086A (en) |
| CS (1) | CS235962B2 (en) |
| DD (1) | DD203067A5 (en) |
| FR (1) | FR2512049A1 (en) |
| GB (1) | GB2105362B (en) |
| IN (1) | IN157304B (en) |
| IT (1) | IT1153179B (en) |
| PL (1) | PL238062A1 (en) |
| RO (1) | RO89083A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2125430A (en) * | 1982-08-13 | 1984-03-07 | Toyo Engineering Corp | Process for thermal cracking of heavy oil |
| US6033555A (en) * | 1997-06-10 | 2000-03-07 | Exxon Chemical Patents Inc. | Sequential catalytic and thermal cracking for enhanced ethylene yield |
| WO2000037587A1 (en) * | 1998-12-22 | 2000-06-29 | Technip Benelux B.V. | Method for operating a cracking furnace and cracking furnace |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4762958A (en) * | 1986-06-25 | 1988-08-09 | Naphtachimie S.A. | Process and furnace for the steam cracking of hydrocarbons for the preparation of olefins and diolefins |
| FR2600667B1 (en) * | 1986-06-25 | 1989-06-02 | Naphtachimie Sa | PROCESS AND OVEN FOR VAPOCRACKING LIQUID HYDROCARBONS FOR THE MANUFACTURE OF OLEFINS AND DIOLEFINS |
| US8496786B2 (en) * | 2009-12-15 | 2013-07-30 | Stone & Webster Process Technology, Inc. | Heavy feed mixer |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3268435A (en) * | 1963-09-30 | 1966-08-23 | Sellin Jan | Process and apparatus for admission to tubes in tube heaters |
| GB1163893A (en) * | 1965-11-03 | 1969-09-10 | Wellmann Incandescent Furnace | Improvements relating to the production of Hydrocarbon Gases |
| US3405691A (en) * | 1966-08-26 | 1968-10-15 | Pullman Inc | Zoned furnace |
| US3385269A (en) * | 1967-01-26 | 1968-05-28 | Selas Corp Of America | Tube heating furnace |
| US3677234A (en) * | 1970-01-19 | 1972-07-18 | Stone & Webster Eng Corp | Heating apparatus and process |
-
1981
- 1981-08-25 RO RO81108508A patent/RO89083A/en unknown
- 1981-08-29 JP JP56136003A patent/JPS5837086A/en active Pending
-
1982
- 1982-08-17 IN IN957/CAL/82A patent/IN157304B/en unknown
- 1982-08-24 GB GB08224238A patent/GB2105362B/en not_active Expired
- 1982-08-24 CS CS826175A patent/CS235962B2/en unknown
- 1982-08-27 IT IT23011/82A patent/IT1153179B/en active
- 1982-08-27 PL PL23806282A patent/PL238062A1/en unknown
- 1982-08-27 DD DD82242850A patent/DD203067A5/en unknown
- 1982-08-30 FR FR8214752A patent/FR2512049A1/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2125430A (en) * | 1982-08-13 | 1984-03-07 | Toyo Engineering Corp | Process for thermal cracking of heavy oil |
| US6033555A (en) * | 1997-06-10 | 2000-03-07 | Exxon Chemical Patents Inc. | Sequential catalytic and thermal cracking for enhanced ethylene yield |
| WO2000037587A1 (en) * | 1998-12-22 | 2000-06-29 | Technip Benelux B.V. | Method for operating a cracking furnace and cracking furnace |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1153179B (en) | 1987-01-14 |
| GB2105362B (en) | 1985-04-11 |
| JPS5837086A (en) | 1983-03-04 |
| IN157304B (en) | 1986-02-22 |
| IT8223011A0 (en) | 1982-08-27 |
| PL238062A1 (en) | 1983-03-28 |
| CS235962B2 (en) | 1985-05-15 |
| FR2512049A1 (en) | 1983-03-04 |
| DD203067A5 (en) | 1983-10-12 |
| RO89083A (en) | 1986-04-30 |
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| PCNP | Patent ceased through non-payment of renewal fee |