EP0021167A1 - Process and apparatus for the thermal decoking of an apparatus for the thermal cracking of hydrocarbons such apparatus comprising a cracking zone followed by a cooler for the product gas - Google Patents
Process and apparatus for the thermal decoking of an apparatus for the thermal cracking of hydrocarbons such apparatus comprising a cracking zone followed by a cooler for the product gas Download PDFInfo
- Publication number
- EP0021167A1 EP0021167A1 EP80103123A EP80103123A EP0021167A1 EP 0021167 A1 EP0021167 A1 EP 0021167A1 EP 80103123 A EP80103123 A EP 80103123A EP 80103123 A EP80103123 A EP 80103123A EP 0021167 A1 EP0021167 A1 EP 0021167A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- gas cooler
- gas
- cooler
- cracked
- cracking
- 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 52
- 238000005235 decoking Methods 0.000 title claims abstract description 36
- 238000005336 cracking Methods 0.000 title claims abstract description 22
- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 11
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 11
- 238000004227 thermal cracking Methods 0.000 title claims description 5
- 239000007789 gas Substances 0.000 claims abstract description 136
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 7
- 239000001301 oxygen Substances 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims description 22
- 230000004992 fission Effects 0.000 claims description 7
- 239000002826 coolant Substances 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 abstract description 10
- 238000010791 quenching Methods 0.000 abstract description 7
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 abstract description 2
- 239000005977 Ethylene Substances 0.000 abstract description 2
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 239000000571 coke Substances 0.000 description 14
- 238000004939 coking Methods 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 230000015556 catabolic process Effects 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000004042 decolorization Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000010327 methods by industry Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S585/00—Chemistry of hydrocarbon compounds
- Y10S585/949—Miscellaneous considerations
- Y10S585/95—Prevention or removal of corrosion or solid deposits
Definitions
- the invention relates to a method for thermal decoking of a device for the thermal cracking of hydrocarbons, the cracking tubes arranged in a cracking zone and a subsequent cracking gas cooler for cooling the cracked products by indirect heat exchange with a.
- Has cooling medium a gas stream containing water vapor and oxygen is passed through the can and the can gas cooler.
- a common decoking process for the cracked gas cooler therefore consists in cooling the system and then separating the cracked gas cooler from the cracking zone and cleaning it mechanically.
- This cleaning can be carried out by means of a water jet which emerges from a nozzle under very high pressure, for example 700-1000 bar, and causes the deposits to come off.
- This method This usually takes about three days, but is not only time-consuming, but also leads to thermal stress on the system due to the periodically repeated heating and cooling cycles, which limits the life of the can.
- the invention therefore has for its object to embody a method of the kind referred to so that the cost and time is reduced for the "decoking.
- cooling medium is passed through the cracked gas cooler even during decoking, that in a first process stage the gas stream is passed through the device in such an amount that the temperature of the deposits on the heat-exchanging surfaces of the cracked gas cooler in the area the operating temperature prevailing in the thermal fission and that in a second process stage the gas flow is amplified to such an extent that the temperature of the deposits on the heat-exchanging surfaces of the fission gas cooler is increased.
- a major disadvantage of this known cracked gas cooler can be seen in the fact that the temperature of the tubes in the cracked gas cooler is subject to large fluctuations. This is particularly important because the pipes are arranged in a high-pressure container, which has an operating pressure in the order of 100 bar, for example. If in such a container, compared to the operating temperature in the order of magnitude of 300 ° C, heating to over 700 ° C is carried out at regular intervals, special measures must be taken for the operational safety of such a cracked gas cooler. In addition, this well-known fission gas cooler deviates from the most commonly used type.
- straight heat exchange tubes In contrast to conventional cracked gas coolers, it does not use straight heat exchange tubes, but rather spirally arranged coils. A transfer of this known concept to straight tube constructions would not be possible due to the thermal expansion or shrinkage when the temperature rises or when cooling back to operating temperature. Straight tube constructions are preferred, among other things, because a corrosion-inhibiting magnetite layer is formed on the outside of the tubes during operation, which is retained in the event of larger temperature fluctuations, while in the case of tube coils this layer is chipped and thus a. increased susceptibility to corrosion occurs.
- a gas mixture containing water vapor and oxygen usually a mixture of water vapor and air, is passed through the cracking plant, the deposits in the cracking tubes being burnt off in the manner customary hitherto.
- the major part of the coke is removed from the can, while the can gas cooler is cleaned only slightly, since the temperature is too low for it to burn up.
- the second process stage follows, in which a substantially larger amount of the gas mixture is passed through the plant.
- the canned tubes are cleaned further and the coke in the cracked gas cooler is largely broken down. This is due to the fact that the gas mixture is passed through the cracked gas cooler in such an amount that the temperature of the coke deposits on the inner wall of the tubes increases to such an extent that a noticeable water gas reaction begins. This temperature increase is possible despite the cooling of the pipes because the thermal conductivity of the coke layer is very low.
- a gas mixture containing water vapor and oxygen is also used in the second stage of the process, although only water vapor is actually required for the water gas reaction.
- the presence of oxygen is advantageous for the rate at which the coke is broken down in the cracked gas cooler. This is due to the fact that the water gas reaction is catalyzed by trace components from the pipe materials, in particular chromium and nickel, which are contained in the coke by diffusion from the pipe materials. However, this catalytic effect only occurs when the sulfur components contained in the coke have always been broken down.
- the presence of oxygen in the gas stream now causes that the pivoting elspuren f are mainly converted to S0 2, so that they can no longer act as a catalyst poison.
- the temperature of the decolourization gases at the outlet from the cracked gas cooler is at least 400.degree. It has been shown that the rate of coke degradation in the cracked gas cooler is too low at lower temperatures to ensure an effective decoking treatment. If the amount of decoking gas is kept constant during the second stage of the process, it is expedient to choose the outlet temperature at the beginning of the second stage of the process considerably above the minimum temperature of approximately 400 ° C., since the outlet temperature increases as the temperature increases Decoking decreases and the minimum temperature should not be fallen below.
- the deposition layer in the tubes is continuously thinner, thereby improving the heat exchange with the refrigerant so that the outlet temperature decreases with the progress of decoking.
- a termination of the decoking process can therefore be easily determined by checking the outlet temperature, since in this case it remains practically constant.
- the high-severity fission of a heavy atmospheric gas oil resulted in a fission gas cooler outlet temperature of 634 ° C after 60 days of operation at an oven outlet temperature of 800 ° C, which indicated strong coking.
- a steam-air mixture to a ground speed of 25 kg / sm 2 is used in the cracking gas cooler, the furnace outlet temperature was 750 0 C.
- the mass velocity in the cracked gas cooler was increased to 45 kg / sm 2 and the furnace outlet temperature to 800 ° C. After a two hour induction period during which the coke breakdown rate was slow, there was a marked increase in the coke breakdown rate.
- the coke extraction rate is the lowering of the cracked gas cooler outlet temperature during decoking under completely constant conditions.
- the coke extraction rate during the induction period was 2 K / h, but then reached a maximum value of 15 K / h. This second phase of decoking was ended after 16 hours.
- the cracked gas cooler is decoked step by step, whereby in each step the gas flow is only passed through part of the heat-exchanging surface. It is essential here that the heat-exchanging surface is reduced during the decoking of the cracked gas cooler, in order in this way to achieve a temperature increase in the sections through which flow occurs.
- this can be done, for example, by passing the entire stream of decoking gas through only part of the cooling tubes while other tubes are being shut down.
- the heat supply to the individual sections of the coked cracked gas cooler can hereby be increased to such an extent that the temperatures required for a sufficiently strong water gas reaction are reached.
- this increase in temperature is not possible by exclusively increasing the mass throughput because the gas stream is then no longer heated to the required high temperature when it passes through the gap zone.
- the complete decoking of the cracked gas cooler takes place in this embodiment of the invention in that after decoking a first part of the heat-exchanging surface, the latter is shut off and the gas flow is then passed through a further part in which the process is repeated. This process is continued until the entire cracked gas cooler is decoked.
- the process according to the invention can be carried out in the cracking of heavy hydrocarbons using the cracked gas coolers usually used for this purpose.
- a modified cracked gas cooler is used, which, in addition to the usual features such as a gas inlet hood, a gas outlet hood, and cooling pipes surrounded by a coolant, also has shut-off devices that allow part of the cooling pipes to be shut down becomes. It has proven to be advantageous to arrange the shut-off elements in the area of the gas outlet hood of the cracked gas cooler. Since the shut-off elements are arranged in the colder part of the cracked gas cooler in this way, a structurally simpler design is possible.
- shut-off devices arranged in the area of the gas inlet hood must remain functional at temperatures of, for example, 850 ° C. it is sufficient to provide valves in the area of the outlet hood which are functional at temperatures up to, for example, 550 ° C.
- a particularly simple way of dividing the heat-exchanging surface of the cracked gas cooler has been found to be to split the gas outlet hood into several separate areas. Each region is associated with a 'number of cooling tubes in each compound, and has a closable gas outlet on.
- the only structural change compared to conventional cracked gas coolers is the subdivision of the gas outlet hood and can therefore be carried out at low cost even with existing systems.
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- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
Spaltöfen und nachgeschaltete Quenchkühler einer Anlage zum thermischen Spalten von Kohlenwasserstoffen, insbesondere einer Äthylenanlage. werden thermisch entkokt. Dazu wird ein Wasserdampf und Sauerstoff enthaltender Gasstrom durch die Spaltrohre und den Quenchkühler geleitet. Das Verfahren erfolgt in zwei Stufen, wobei in der ersten Stufe im wesentlichen nur ein Abbrand der Ablagerungen in der Spaltzone erfolgt. In einer nachfolgenden zweiten Verfahrensstufe wird der Gasdurchsatz soweit erhöht, daß im Quenchkühler eine merkbare Wassergasreaktion einsetzt und die Entkokung bewirkt. Die Dampferzeugung im Quenchkühler wird während der Entkokung nicht unterbrochen. Bei der Spaltung leichter Einsätze ist es günstig, den Quenchkühler in mehreren Schritten zu entkoken. Hierzu kann die Eintrittshaube des Kühlers in mehrere Sequente unterteilt werden.Cracking furnaces and downstream quench coolers of a plant for the thermal splitting of hydrocarbons, especially an ethylene plant. are decoked thermally. For this purpose, a gas stream containing water vapor and oxygen is passed through the can and the quench cooler. The process takes place in two stages, the first stage essentially only burning off the deposits in the gap zone. In a subsequent second process stage, the gas throughput is increased to such an extent that a noticeable water gas reaction begins in the quench cooler and causes decoking. The steam generation in the quench cooler is not interrupted during decoking. When splitting light inserts, it is beneficial to decoke the quench cooler in several steps. For this purpose, the inlet hood of the cooler can be divided into several sequences.
Description
Die Erfindung betrifft ein Verfahren zum thermischen Entkoken einer Vorrichtung zum thermischen Spalten von Kohlenwasserstoffen, die in einer Spaltzone angeordnete Spaltrohre und einen nachfolgenden Spaltgaskühler zur Kühlung der Spaltprodukte durch indirekten Wärmetausch mit einem. Kühlmedium aufweist, wobei ein Wasserdampf und Sauerstoff enthaltender Gasstrom durch die Spaltrohre und den Spaltgaskühler geleitet wird.The invention relates to a method for thermal decoking of a device for the thermal cracking of hydrocarbons, the cracking tubes arranged in a cracking zone and a subsequent cracking gas cooler for cooling the cracked products by indirect heat exchange with a. Has cooling medium, a gas stream containing water vapor and oxygen is passed through the can and the can gas cooler.
Die thermische Spaltung von Kohlenwasserstoffen, insbesondere die auf die Bildung von Äthylen und anderen niederen Olefinen gerichtete thermische Spaltung, ist von großer technischer Bedeutung. Bei der Durchführung derartiger Verfahren treten jedoch eine Reihe von Nebenreaktionen auf, die zu wirtschaftlich uninteressanten oder sogar zu störenden Produkten führen. Eine solche störende Nebenreaktion ist in der Verkokung der Spaltrohre und des Spaltgaskühlers zu sehen, da sie zu einer Verschlechterung des Wärmeübergangs sowohl in der von außen beheizten Spaltzone als auch im nachfolgenden Spaltgaskühler führt und im Extremfall sogar die Verstopfung einzelner Leitungselemente zur Folge haben kann. Es ist deshalb bei fortschreitender Verkokung nötig, die Spaltrohre stärker zu beheizen, um die für die Umsetzung erforderliche Aufheizung der Kohlenwasserstoffe zu gewährleisten. Diesem erhöhten Energieaufwand steht im Spaltgaskühler, in dem ein möglichst großer Anteil der Spaltgaswärme zur Erzeugung von Hochdruckdampf zurückgewonnen werden soll, eine verminderte Hochdruckdampfproduktion gegenüber. Außerdem ist natürlich aus prozeßtechnischer Sicht die verschlechterte Abkühlung unbefriedigend, weil ein schnelles Abkühlen und damit eine Unterbrechung der Spaltreaktionen im Hinblick auf eine erwünschte Produktausbeute angestrebt wird.The thermal cracking of hydrocarbons, especially the thermal cracking aimed at the formation of ethylene and other lower olefins, is of great technical importance. When such processes are carried out, however, a number of side reactions occur which lead to economically uninteresting or even disruptive products. Such a troublesome side reaction can be seen in the coking of the cracked tubes and the cracked gas cooler, since it leads to a deterioration in the heat transfer both in the cracked zone heated from the outside and in the subsequent cracked gas cooler and, in extreme cases, even blockage of individual pipe elements can result. As coking progresses, it is therefore necessary to heat the can more strongly in order to ensure the heating of the hydrocarbons required for the reaction. In the cracked gas cooler, in which as much of the cracked gas heat as possible is to be recovered for generating high-pressure steam, this increased energy expenditure is countered by a reduced high-pressure steam production. In addition, the worsened cooling is of course unsatisfactory from a process engineering point of view, because rapid cooling and thus an interruption of the cleavage reactions with a view to a desired product yield is sought.
Es ist deshalb erforderlich, die thermische Spaltung von Zeit zu Zeit zu unterbrechen und eine Entkokung der Anlage durchzuführen. Dies erfolgt üblicherweise dadurch, daß ein Gemisch aus Luft und Wasserdampf durch die weiterhin von außen beheizten Spaltrohre und den weiterhin gekühlten Spaltgaskühler geführt wird. Bei den hohen Temperaturen in den Spaltrohren, die beispielsweise zwischen 750 und 8500C liegen können, erfolgt dann ein Abbrand der Ablagerungen. Die Reinigung des Spaltgaskühlers ist auf diese Wdse jedoch nicht möglich, da bei den hier herrschenden Temperaturen kein Abbrand mehr erfolgt. Es kann höchstens im Eintrittsbereich des Spaltgaskühlers, in dem die eintretenden Gase noch die hohe Temperatur der Spaltzone aufweisen, zu einem begrenzten Abbrand kommen, der jedoch wegen der Kühlung rasch beendet wird. Ein übliches Entkokungsverfahren für den Spaltgaskühler besteht deshalb darin, daß die Anlage abgekühlt und anschließend der Spaltgaskühler von der Spaltzone abgetrennt und mechanisch gereinigt wird. Diese Reinigung kann durch einen Wasserstrahl erfolgen, der unter sehr hohem Druck, beispielsweise 700 - 1000 bar,aus einer Düse austritt und ein Abspringen der Ablagerungen hereiführt. Dieses Verfahren, das üblicherweise etwa drei Tage dauert, ist jedoch nicht nur zeitaufwendig, sondern führt darüber hinaus durch die sich periodisch wiederholenden Aufheiz- und Abkühlzyklen zu einer thermischen Belastung der Anlage, durch die die Lebensdauer der Spaltrohre begrenzt wird.It is therefore necessary to interrupt the thermal splitting from time to time and to decoke the system. This is usually done by passing a mixture of air and water vapor through the canned tubes, which are still heated from the outside, and the canned gas cooler, which is still cooled. At the high temperatures in the can, which can be between 750 and 850 ° C, for example, the deposits burn off. However, cleaning of the cracked gas cooler is not possible on these walls, since the temperatures prevailing here no longer burn up. At most, in the entrance area of the cracked gas cooler, in which the entering gases still have the high temperature of the cracking zone, a limited burn-up can occur, which, however, is quickly ended due to the cooling. A common decoking process for the cracked gas cooler therefore consists in cooling the system and then separating the cracked gas cooler from the cracking zone and cleaning it mechanically. This cleaning can be carried out by means of a water jet which emerges from a nozzle under very high pressure, for example 700-1000 bar, and causes the deposits to come off. This method, This usually takes about three days, but is not only time-consuming, but also leads to thermal stress on the system due to the periodically repeated heating and cooling cycles, which limits the life of the can.
Der Erfindung liegt deshalb die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art so auszugestalten, daß der Kosten- und Zeitaufwand für das' Entkoken verringert wird.The invention therefore has for its object to embody a method of the kind referred to so that the cost and time is reduced for the "decoking.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß das Kühlmedium auch während der Entkokung durch den Spaltgaskühler geführt wird, daß in einer ersten Verfahrensstufe der Gasstrom in einer solchen Menge durch die Vorrichtung geleitet wird, daß die Temperatur der Ablagerungen auf den wärmetauschenden Flächen des Spaltgaskühlers im Bereich der bei der thermischen Spaltung herrschenden Betriebstemperatur liegt und daß in einer zweiten Verfahrensstufe der Gasstrom so weit verstärkt wird, daß die Temperatur der Ablagerungen auf den wärmetauschenden Flächen des Spaltgaskühlers erhöht wird.This object is achieved in that the cooling medium is passed through the cracked gas cooler even during decoking, that in a first process stage the gas stream is passed through the device in such an amount that the temperature of the deposits on the heat-exchanging surfaces of the cracked gas cooler in the area the operating temperature prevailing in the thermal fission and that in a second process stage the gas flow is amplified to such an extent that the temperature of the deposits on the heat-exchanging surfaces of the fission gas cooler is increased.
Erfindungsgemäß wird damit ein Entkokungsverfahren vorgeschlagen, bei dem eine Abtrennung des Spaltgaskühlers von der Spaltzone und eine Abkühlung der Anlage nicht mehr erforderlich ist.According to the invention, a decoking process is thus proposed in which it is no longer necessary to separate the cracked gas cooler from the cracking zone and to cool the plant.
Es ist zwar schon ein Spaltgaskühler bekannt geworden, der ebenfalls auf thermischem Wege entkokt wird (Bulletin of the Japan Petroleum Institute, Vol. 13, No. 2, November 1971, Seiten 279 bis 284), wobei aber in wesentlichen Punkten von erfindungsgemäßen Verfahren abgewichen wird.While it is known already a gas cooler, which is also decoked thermally (. Bulletin of the Japan Petroleum Institute, Vol. 13, N o 2 November 1971, pages 279 to 284), but essential points of the novel process is deviated.
In diesem bekannten Spaltgaskühler werden die Spaltgase in spiralförmig angeordneten Rohren abgekühlt. Der Entkokungsvorgang ist dabei praktisch der gleiche wie der in einer Spaltzone, denn das Kühlwasser wird während der Entkokungsphase aus dem Spaltgaskühler entfernt, wodurch sich die Kühlrohre auf über 700°C erhitzen und ein Abbrand der Verunreinigungen erfolgt.In this known cracked gas cooler, the cracked gases are cooled in tubes arranged in a spiral. The Ent The coking process is practically the same as that in a cracking zone, because the cooling water is removed from the cracking gas cooler during the decoking phase, causing the cooling tubes to heat up to over 700 ° C and the contaminants burn off.
Ein wesentlicher Nachteil dieses bekannten Spaltgaskühlers ist jedoch darin zu sehen, daß die Temperatur der Rohre im Spaltgaskühler großen Schwankungen unterworfen ist. Dies ist insbesondere deshalb von Bedeutung, weil die Rohre in einem Hochdruckbehälter, der beispielsweise einen Betriebsdruck in der Größenordnung von 100 bar aufweist, angeordnet sind. Wenn in einem solchen Behälter gegenüber der Betriebstemperatur in der Größenordnung von 300°C eine Aufheizung auf über 700°C in regelmäßigen Abständen durchgeführt wlrd, sind besondere Maßnahmen für die Betriebssicherheit eines solchen Spaltgaskühlers zu treffen. Darüber hinaus weicht dieser bekannte Spaltgaskühler in seiner Konstruktion von der am häufigsten verwendeten Bauart ab.A major disadvantage of this known cracked gas cooler can be seen in the fact that the temperature of the tubes in the cracked gas cooler is subject to large fluctuations. This is particularly important because the pipes are arranged in a high-pressure container, which has an operating pressure in the order of 100 bar, for example. If in such a container, compared to the operating temperature in the order of magnitude of 300 ° C, heating to over 700 ° C is carried out at regular intervals, special measures must be taken for the operational safety of such a cracked gas cooler. In addition, this well-known fission gas cooler deviates from the most commonly used type.
Er verwendet nämlich im Gegensatz zu üblichen SpaltgaskUhlern keine geraden Wärmetauschrohre, sondern spiralförmig angeordnete Rohrschlangen. Eine Übertragung dieses bekannten Konzepts auf Geradrohr-Konstruktionen wäre schon wegen der thermischen Ausdehnung bzw. Schrumpfung beim Temperaturanstieg bzw. beim Rückkühlen auf Betriebstemperatur nicht möglich. Geradrohrkonstruktionen werden unter anderem auch vorgezogen, weil sich auf der Außenseite der Rohre im Betrieb eine korrosionshemmende Magnetitschicht bildet, die bei größeren Temperaturschwankungen erhalten bleibt, während bei Rohrschlangen ein Abplatzen dieser Schicht und damit eine . erhöhte Korrosionsfälligkeit auftritt.In contrast to conventional cracked gas coolers, it does not use straight heat exchange tubes, but rather spirally arranged coils. A transfer of this known concept to straight tube constructions would not be possible due to the thermal expansion or shrinkage when the temperature rises or when cooling back to operating temperature. Straight tube constructions are preferred, among other things, because a corrosion-inhibiting magnetite layer is formed on the outside of the tubes during operation, which is retained in the event of larger temperature fluctuations, while in the case of tube coils this layer is chipped and thus a. increased susceptibility to corrosion occurs.
Erfindungsgemäß wird dagegen ein zweistufiges Verfahren vorgeschlagen, bei dem eine fortlaufende Dampfproduktion ermöglicht wird und.bei dem nur eine vergleichsweise geringe Temperaturänderung der Rohre im Spaltgaskühler erfolgt. Deshalb ist es auch möglich, dieses Verfahren bei üblichen Spaltgaskühlern mit geraden Rohren durchzuführen.According to the invention, on the other hand, a two-stage process is proposed in which continuous steam production is made possible and in which only a comparatively low one The temperature of the pipes in the cracked gas cooler changes. It is therefore also possible to carry out this process in conventional cracked gas coolers with straight tubes.
In der ersten Stufe des erfindungsgemäßen Verfahrens wird ein Wasserdampf und Sauerstoff enthaltendes Gasgemisch, üblicherweise ein Gemisch aus Wasserdampf und Luft, durch die Spaltanlage geleitet, wobei in der bisher üblichen Weise ein Abbrand der Ablagerungen in den Spaltrohren erfolgt. Während dieser schonenden Entkokungsphase wird der größte Teil des Kokses aus den Spaltrohren entfernt, während der Spaltgaskühler nur geringfügig gereinigt wird, da hier die Temperatur für einen Abbrand zu niedrig ist.In the first stage of the process according to the invention, a gas mixture containing water vapor and oxygen, usually a mixture of water vapor and air, is passed through the cracking plant, the deposits in the cracking tubes being burnt off in the manner customary hitherto. During this gentle decoking phase, the major part of the coke is removed from the can, while the can gas cooler is cleaned only slightly, since the temperature is too low for it to burn up.
Nach Abschluß dieser ersten Verfahrensstufe, die einige Stunden, beispielsweise 4 - 8 Stunden, währen kann, schließt sich die zweite Verfahrensstufe an, bei der eine wesentlich größere Menge des Gasgemisches durch die Anlage geführt wird. In dieser Verfahrensstufe werden die Spaltrohre weiter gereinigt und außerdem wird der Koks im Spaltgaskühler weitgehend abgebaut. Dies ist darauf zurückzuführen, daß das Gasgemisch in einer solchen Menge durch den Spaltgaskühler geführt wird, daß sich die Temperatur der Koksablagerungen auf der Innenwand der Rohre soweit erhöht,daß eine merkbare Wassergasreaktion einsetzt. Diese Temperaturerhöhung ist trotz der Kühlung der Rohre möglich, weil die Wärmeleitfähigkeit der Koksschicht sehr gering ist. Ein Abbrand, wie er in den Spaltrohren der Spaltzone erfolgt, findet hier jedoch nicht statt, da bei fortlaufender Kühlung des Spaltgaskühlers eine Temperaturerhöhung auf die dafür erforderlichen Werte, die über 600°C liegen, nicht erreicht werden kann. Dagegen wird der Entkokungsvorgang vermutlich durch Abplatzen von Ablagerungen aufgrund des erhöhten Massendurchsatzes begünstigt.After completion of this first process stage, which can last for a few hours, for example 4-8 hours, the second process stage follows, in which a substantially larger amount of the gas mixture is passed through the plant. In this process step, the canned tubes are cleaned further and the coke in the cracked gas cooler is largely broken down. This is due to the fact that the gas mixture is passed through the cracked gas cooler in such an amount that the temperature of the coke deposits on the inner wall of the tubes increases to such an extent that a noticeable water gas reaction begins. This temperature increase is possible despite the cooling of the pipes because the thermal conductivity of the coke layer is very low. However, there is no erosion, as occurs in the gap tubes of the gap zone, since with continued cooling of the gap gas cooler, a temperature increase to the values required for this, which are above 600 ° C., cannot be achieved. In contrast, the decoking process is presumably promoted by flaking of deposits due to the increased mass throughput.
Die zweistufige Verfahrensweim ist im Hinblick auf die Lebensdauer der Spaltrohre erforderlich. Würde nämlich bereits zu Beginn der Entkokung der Gasstrom so stark gewählt werden, daß im Spaltgaskühler die Wassergasreaktion einsetzt, dann bestünde die Gefahr, daß in der Spaltzone abplatzende Koksteile eine Erosionswirkung auf die Spaltrohre ausüben und diese beschädigen würden.The two-stage process is necessary with regard to the service life of the can. That would be too At the beginning of decoking the gas flow should be chosen so strongly that the water gas reaction starts in the cracked gas cooler, there would be the danger that coke parts flaking off in the cracking zone would have an erosive effect on the cracked tubes and would damage them.
Von Bedeutung für die Durchführung des erfindungsgemäßen Verfahrens ist, daß auch in der zweiten Verfahrensstufe ein Wasserdampf und Sauerstoff enthaltendes Gasgemisch verwendet wird, obwohl für die Wassergasreaktion eigentlich nur der Wasserdampf erforderlich ist. Für die Abbaugeschwindigkeit des Kokes im Spaltgaskühler ist die Anwesenheit von Sauerstoff jedoch von Vorteil. Dies hängt damit zusammen, daß die Wassergasreaktion durch Spurenbestandteile aus den Rohrmaterialien, insbesondere von Chrom und Nickel, die durch Diffusion aus den Rohrmaterialien im Koks enthalten sind, katalysiert wird. Dieser katalytische Effekt tritt jedoch erst dann ein, wenn die im Koks stets auch enthaltenen Schwefelbestandteile abgebaut sind. Die Anwesenheit von Sauerstoff im Gasstrom führt nun dazu, daß die Schwefelspuren vorwiegend in S02 umgewandelt werden, so daß sie nicht mehr als Katalysatorgift wirken können.It is important for the implementation of the method according to the invention that a gas mixture containing water vapor and oxygen is also used in the second stage of the process, although only water vapor is actually required for the water gas reaction. However, the presence of oxygen is advantageous for the rate at which the coke is broken down in the cracked gas cooler. This is due to the fact that the water gas reaction is catalyzed by trace components from the pipe materials, in particular chromium and nickel, which are contained in the coke by diffusion from the pipe materials. However, this catalytic effect only occurs when the sulfur components contained in the coke have always been broken down. The presence of oxygen in the gas stream now causes that the pivoting elspuren f are mainly converted to S0 2, so that they can no longer act as a catalyst poison.
Bei der Durchführung des erfindungsgemäßen Verfahen hat es sich als günstig erwiesen, den Gasstrom in der zweiten Verfahrensstufe soweit zu erhöhen, daß die Temperatur der Entkolcungsgase am Austritt aus dem Spaltgaskühler mindestens 400°C beträgt. Es hat sich nämlich gezeigt, daß.die Koksabbaugeschwindigkeit im Spaltgaskühler bei tieferen Temperaturen zu gering ist, um eine effektive Entkokungsbehandlung zu gewährleisten. Wird die Entkokungsgasmenge während der zweiten Verfahrensstufe konstant gehalten, ist es günstig, die Austrittstemperatur zu Beginn der zweiten Verfahrensstufe beträchtlich über der minimalen Temperatur von etwa 400° C zu wählen, da die Austrittstemperatur mit fortschreitender Entkokung sinkt und die Mindesttemperatur nicht unterschritten werden sollte.When carrying out the process according to the invention, it has proven advantageous to increase the gas flow in the second process stage to such an extent that the temperature of the decolourization gases at the outlet from the cracked gas cooler is at least 400.degree. It has been shown that the rate of coke degradation in the cracked gas cooler is too low at lower temperatures to ensure an effective decoking treatment. If the amount of decoking gas is kept constant during the second stage of the process, it is expedient to choose the outlet temperature at the beginning of the second stage of the process considerably above the minimum temperature of approximately 400 ° C., since the outlet temperature increases as the temperature increases Decoking decreases and the minimum temperature should not be fallen below.
Während der Entkokung des Spaltgaskühlers wird die Ablagerungsschicht in den Rohren laufend dünner, wodurch der Wärmetausch mit dem Kühlmittel verbessert wird, so daß die Austrittstemperatur mit fortschreitender Entkokung absinkt. Eine Beendigung des Entkokungsvorganges läßt sich deshalb durch Überprüfung der Austrittstemperatur leicht feststellen, da sie in diesem Fall praktisch konstant bleibt.During the E ntkokung of the quench cooler, the deposition layer in the tubes is continuously thinner, thereby improving the heat exchange with the refrigerant so that the outlet temperature decreases with the progress of decoking. A termination of the decoking process can therefore be easily determined by checking the outlet temperature, since in this case it remains practically constant.
Nachfolgend wird das erfindungsgemäße Verfahren anhand eines Beispiels verdeutlicht.The method according to the invention is illustrated below using an example.
Bei der High-Severity-Spaltung eines schweren atmosphärischen Gasöls ergab sich nach 60 Tagen Betrieb bei einer Ofenaustrittstemperatur von 800°C eine Spaltgaskühler-Austrittstemperatur von 634°C, was auf eine starke Verkokung schließen ließ. In einer ersten Phase der Entkokung wurde 8 Stunden lang ein Dampf-Luft-Gemisch mit einer Massengeschwindigkeit von 25 kg/s m2 im Spaltgaskühler verwendet, wobei die Ofenaustrittstemperatur 7500C betrug. Anschließend wurde die Massengeschwindigkeit im Spaltgaskühler auf 45 kg/s m2 und die Ofenaustrittstemperatur auf 800°C erhöht. Nach einer zweistündigen Induktionsperiode, in der die Koksabbaugeschwindigkeit klein war, trat eine merkliche Erhöhung der Koksabbaugeschwindigkeit ein. (Als Koksabbaugeschwindigkeit wird die Absenkung der Spaltgaskühleraustrittstemperatur während des Entkokens bei völlig konstanten Bedingungen bezeichnet.) Die Koksabbaugeschwindigkeit während der Induktionsperiode betrug 2 K/h, während sie anschließend einen maximalen Wert von 15 K/h erreichte. Diese zweite Phase der Entkokung wurde nach 16 Stunden beendet.The high-severity fission of a heavy atmospheric gas oil resulted in a fission gas cooler outlet temperature of 634 ° C after 60 days of operation at an oven outlet temperature of 800 ° C, which indicated strong coking. In a first phase of the decoking 8 hours long, a steam-air mixture to a ground speed of 25 kg / sm 2 is used in the cracking gas cooler, the furnace outlet temperature was 750 0 C. Then the mass velocity in the cracked gas cooler was increased to 45 kg / sm 2 and the furnace outlet temperature to 800 ° C. After a two hour induction period during which the coke breakdown rate was slow, there was a marked increase in the coke breakdown rate. (The coke extraction rate is the lowering of the cracked gas cooler outlet temperature during decoking under completely constant conditions.) The coke extraction rate during the induction period was 2 K / h, but then reached a maximum value of 15 K / h. This second phase of decoking was ended after 16 hours.
Nach einer Gesamtentkokungszeit von 24 Stunden betrug die Austrittstemperatur der Entkokungsgase aus dem Spaltgaskühler etwa 4000C. Hier wurde der Entkokungsvorgang beendet.After a total decoking time of 24 hours, the Outlet temperature of Entkokungsgase from the gas cooler 400 0 C. Here, the decoking operation has ended.
Nach Wiederinbetriebnahme-des Spaltofens mit schwerem Gasöl stellte sich eine Spaltgaskühleraustrittstemperatur von etwa 4700C ein. Dies bedeutet, daß der Spaltgaskühler praktisch vollständig gereinigt wurde. In der anschließenden Laufzeit konnten ebenfalb wieder 60 Tage erreicht werden, was darauf hinweist, daß die Verkokungsgeschwindigkeit des erfindungsgemäß gereinigten Spaltgaskühlers nicht größer ist als bei einem mechanisch gereinigten Spaltgaskühler.After restarting the cracking furnace with heavy gas oil, a cracked gas cooler outlet temperature of about 470 ° C. was reached. This means that the cracked gas cooler has been almost completely cleaned. In the subsequent running time, 60 days could also be reached again, which indicates that the coking rate of the cracked gas cooler cleaned according to the invention is not greater than that of a mechanically cleaned cracked gas cooler.
Das erfindungsgemäße Verfahren in seiner bisher beschriebenen Form hat sich bei der Entkokung einer Anlage zum Spalten von schweren Kohlenwasserstoffenwie Gasöl oder Vakuumgasöl-als günstig erwiesen. Es hat sich jedoch gezeigt, daß eine wirksame Entkokung für Spaltgaskühler einer Anlage zum Spalten von leichteren Einsätzen, wie beispielsweise Naphtha oder Äthan auf diese Weise nicht erreicht werden kann. Dies ist in erster Linie darauf zurückzuführen, daß die Spaltgaskühler bei der Spaltung derartiger Einsätze so ausgelegt sind, daß die Spaltgastemperatur unterhalb der Temperatur liegt, bei der noch eine merkbare Wassergasreaktion erfolgt. Diese verstärkte Kühlung, die beispielsweise durch Verwendung längerer Kühlrohre erreicht werden kann, ist bei der Spaltung leichterer Kohlenwasserstoffe möglich, da diese weniger zur Verkokung neigende Bestandteile im Spaltgas enthalten. Während beispielsweise bei der Abkühlung eines aus Gasöl gewonnenen Spaltgases eine Kühlung auf weniger als etwa 470 °C zu einer raschen Verkokung des Spaltgaskühlers führt, kann bei einem aus Naphtha gewonnenen Spaltgas die Abkühlung auf Temperaturen von etwa 350 bis 370 °C durchgeführt werden, ohne stärkere Verkokungsneigungen befürchten zu müssen. Das aus dem Spaltgaskühler austretende Gas wird dann üblicherweise durch direkten Wärmetausch mit einem Quenchöl weiter abgekühlt.The process according to the invention in the form described so far has proven to be advantageous in decoking a plant for splitting heavy hydrocarbons such as gas oil or vacuum gas oil. However, it has been shown that effective decoking for cracked gas coolers of a plant for splitting lighter uses, such as naphtha or ethane, cannot be achieved in this way. This is primarily due to the fact that the cracked gas coolers are designed such that the cracked gas temperature is below the temperature at which a noticeable water gas reaction occurs. This increased cooling, which can be achieved, for example, by using longer cooling tubes, is possible when lighter hydrocarbons are split, since these contain fewer constituents which tend to coke in the cracked gas. For example, while cooling a cracked gas obtained from gas oil to less than about 470 ° C leads to rapid coking of the cracked gas cooler, with cracked gas obtained from naphtha, the cooling to temperatures of about 350 to 370 ° C can be carried out without more Fear of coking tendencies. The end The gas emerging from the cracked gas cooler is then usually further cooled by direct heat exchange with a quench oil.
Um dennoch eine Ausweitung des erfindungsgemäßen Entkokungsverfahrens auch auf Spaltgaskühler mit niedriger Austrittstemperatur, wie sie bei der Spaltung von unter etwa 200 °C siedenden Kohlenwasserstoffen eingesetzt werden, zu ermöglichen, wird in weiterer Ausgestaltung der Erfindung vorgeschlagen, daß der Spaltgaskühler schrittweise entkokt wird, wobei in jedem Schritt der Gasstrom nur durch einen Teil der wärmetauschenden Fläche geführt wird. Wesentlich ist dabei, daß während der Entkokung des Spaltgaskühlers die wärmetauschende Fläche verringert wird, um auf diese Weise eine Temperaturerhöhung in den durchströmten Abschnitten zu erreichen. Dies kann bei Verwendung eines Spaltgaskühlers mit einem Rohrbündelwärmetauscher beispielsweise dadurch geschehen, daß der gesamte Strom des Entkokungsgases nur durch einen Teil der Kühlrohre geführt wird, während andere Rohre stillgelegt werden. Die Wärmezufuhr zu den einzelnen Abschnitten des verkokten Spaltgaskühlers kann hierdurch soweit erhöht werden, daß die für eine hinreichend starke Wassergasrekation erforderlichen Temperaturen erreicht werden. Dagegen ist durch ausschließliche Erhöhung des Massendurchsatzes diese Temperaturerhöhung nicht möglich, weil der Gasstrom dann beim Durchlaufen der Spaltzone nicht mehr auf die erforderliche hohe Temperatur erhitzt wird. Die vollständige Entkokung des Spaltgaskühlers erfolgt in dieser Ausgestaltung der Erfindung dadurch, daß nach der Entkokung eines ersten Teils der wärmetauschenden Fläche diese abgesperrt wird und der Gasstrom dann durch einen weiteren Teil geleitet wird, in dem sich der Vorgang wiederholt. Dieses Verfahren wird solange fortgesetzt, bis der gesamte Spaltgaskühler entkokt ist.In order to enable an expansion of the decoking process according to the invention also to cracked gas coolers with a low outlet temperature, such as are used in the cracking of hydrocarbons boiling below approximately 200 ° C., it is proposed in a further embodiment of the invention that the cracked gas cooler is decoked step by step, whereby in each step the gas flow is only passed through part of the heat-exchanging surface. It is essential here that the heat-exchanging surface is reduced during the decoking of the cracked gas cooler, in order in this way to achieve a temperature increase in the sections through which flow occurs. When using a cracked gas cooler with a tube bundle heat exchanger, this can be done, for example, by passing the entire stream of decoking gas through only part of the cooling tubes while other tubes are being shut down. The heat supply to the individual sections of the coked cracked gas cooler can hereby be increased to such an extent that the temperatures required for a sufficiently strong water gas reaction are reached. On the other hand, this increase in temperature is not possible by exclusively increasing the mass throughput because the gas stream is then no longer heated to the required high temperature when it passes through the gap zone. The complete decoking of the cracked gas cooler takes place in this embodiment of the invention in that after decoking a first part of the heat-exchanging surface, the latter is shut off and the gas flow is then passed through a further part in which the process is repeated. This process is continued until the entire cracked gas cooler is decoked.
Als günstig hat es sich erwiesen, den Spaltgaskühler in zwei Schritten zu entkoken. Es hat sich nämlich gezeigt, daß bei Halbierung der wärmetauschenden Fläche des Spaltgaskühlers bereits die für eine ausreichende Wassergasreaktion erforderliche Temperatur erreicht wird. Die Begrenzung auf möglichst wenige Entkokungsschritte ist natürlich erstrebenswert, um die Entkokungsdauer möglichst gering zu halten, doch muß dabei berücksichtigt werden, daß die Temperatur für eine ausreichende starke Wassergasreaktion in jedem einzelnen Schritt erreicht wird.It has proven to be advantageous to decoke the cracked gas cooler in two steps. It has been shown that by halving the heat-exchanging surface of the cracked gas cooler, the temperature required for a sufficient water gas reaction is already reached. Limiting to as few decoking steps as possible is of course desirable in order to keep the decoking time as short as possible, but it must be taken into account that the temperature for a sufficiently strong water gas reaction is reached in each individual step.
Günstig ist es weiterhin., die schrittweise Entkokung des Spaltgaskühlers nur während der zweiten Verfahrensstufe, d.h. bei erhöhtem Massendurchsatz des Entkokungsgases, durchzuführen. Allerdings kann es in einigen Fällen auch zweckmäßig sein, während der ersten Verfahrensstufe, in der eine Entkokung der Spaltrohre erfolgt, den Gasstrom durch einen kleinen Bereich des Spaltgaskühlers-zu führen.It is also favorable., The gradual decoking of the cracked gas cooler only during the second process stage, i.e. with increased mass flow rate of the decoking gas. In some cases, however, it may also be expedient to guide the gas flow through a small area of the cracked gas cooler during the first process stage, in which the can is decoked.
Das erfindungsgemäße Verfahren kann bei der Spaltung schwerer Kohlenwasserstoffe unter Verwendung der hierfür üblicherweise verwendeten Spaltgaskühler durchgeführt werden. Bei der Spaltung von unter 200 °C siedenden Kohlenwasserstoffen wird dagegen ein modifizierter Spaltgaskühler eingesetzt, der neben den üblichen Merkmalen wie eine Gaseintrittshaube, eine Gasaustrittshaube, dazwischen verlaufende, von einem Kühlmittel umgebene Kühlrohre noch Absperrorgane aufweist, durch die die Stillegung eines Teils der Kühlrohre ermöglicht wird. Als günstig hat sich dabei erwiesen, die Absperrorgane im Bereich der Gasaustrittshaube des Spaltgaskühlers anzuordnen. Da auf diese Weise die Absperrorgane im kälteren Teil des Spaltgaskühlers angeordnet sind, ist eine baulich einfachere Ausführung möglich. Während im Bereich der Gaseintrittshaube angeordnete Absperrorgane bei Temperaturen von beispielsweise 850 °C funktionsfähig bleiben müssen, genügt es, im Bereich der Austrittshaube Ventile vorzusehen, die bei Temperaturen bis zu beispielsweise 550 °C funktionsfähig sind.The process according to the invention can be carried out in the cracking of heavy hydrocarbons using the cracked gas coolers usually used for this purpose. In contrast, when hydrocarbons boiling below 200 ° C are split, a modified cracked gas cooler is used, which, in addition to the usual features such as a gas inlet hood, a gas outlet hood, and cooling pipes surrounded by a coolant, also has shut-off devices that allow part of the cooling pipes to be shut down becomes. It has proven to be advantageous to arrange the shut-off elements in the area of the gas outlet hood of the cracked gas cooler. Since the shut-off elements are arranged in the colder part of the cracked gas cooler in this way, a structurally simpler design is possible. While shut-off devices arranged in the area of the gas inlet hood must remain functional at temperatures of, for example, 850 ° C. it is sufficient to provide valves in the area of the outlet hood which are functional at temperatures up to, for example, 550 ° C.
Als eine besonders einfache Art der Unterteilung der wärmetauschenden Fläche des Spaltgaskühlers hat sich eine Aufteilung der Gasaustrittshaube in mehrere, voneinander getrennte Bereiche erwiesen. Dabei steht jeder Bereich mit einer'Zahl von Kühlrohren in Verbindung und weist jeweils eine absperrbare Gasableitung auf. Die einzige bauliche Änderung gegenüber üblichen Spaltgaskühlern besteht damit in der Unterteilung der Gasaustrittshaube und ist deshalb mit geringen Kosten auch bei bereits bestehenden Anlagen durchführbar.A particularly simple way of dividing the heat-exchanging surface of the cracked gas cooler has been found to be to split the gas outlet hood into several separate areas. Each region is associated with a 'number of cooling tubes in each compound, and has a closable gas outlet on. The only structural change compared to conventional cracked gas coolers is the subdivision of the gas outlet hood and can therefore be carried out at low cost even with existing systems.
Claims (10)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT80103123T ATE734T1 (en) | 1979-06-08 | 1980-06-04 | METHOD AND APPARATUS FOR THERMAL DECOKING OF AN APPARATUS FOR THERMAL CLEAVING OF HYDROCARBONS, CONSISTING OF A CRACKING ZONE AND A SUBSEQUENT RELAPE GAS COOLER. |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2923326 | 1979-06-08 | ||
| DE19792923326 DE2923326A1 (en) | 1979-06-08 | 1979-06-08 | Cracked gas cooler decarbonising - by flushing in two stages at rising flow-rate with air and steam mixt. |
| DE2934570 | 1979-08-27 | ||
| DE19792934570 DE2934570A1 (en) | 1979-08-27 | 1979-08-27 | METHOD FOR THERMALLY DECOKING A DEVICE FOR THERMALLY CLEAVING HYDROCARBONS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0021167A1 true EP0021167A1 (en) | 1981-01-07 |
| EP0021167B1 EP0021167B1 (en) | 1982-03-03 |
Family
ID=25779465
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP80103123A Expired EP0021167B1 (en) | 1979-06-08 | 1980-06-04 | Process and apparatus for the thermal decoking of an apparatus for the thermal cracking of hydrocarbons such apparatus comprising a cracking zone followed by a cooler for the product gas |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4376694A (en) |
| EP (1) | EP0021167B1 (en) |
| DE (1) | DE3060219D1 (en) |
| IN (1) | IN153444B (en) |
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| EP0036151A1 (en) * | 1980-03-15 | 1981-09-23 | BASF Aktiengesellschaft | Process for thermally decoking coolers for cracked gases |
| EP0143486A2 (en) * | 1983-10-31 | 1985-06-05 | Union Carbide Corporation | Method for on-line decoking of flame cracking reactors |
| EP0591856A1 (en) * | 1992-10-05 | 1994-04-13 | Stone & Webster Engineering Corporation | Pulsed air decoking |
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| FR2743007B1 (en) * | 1995-12-27 | 1998-01-30 | Inst Francais Du Petrole | CONTINUOUS PYROLYSIS AND DECOKING PROCESS APPLICABLE IN PARTICULAR TO THE PRODUCTION OF ACETYLENE |
| FR2748273B1 (en) | 1996-05-06 | 1998-06-26 | Inst Francais Du Petrole | METHOD AND DEVICE FOR THE THERMAL CONVERSION OF HYDROCARBONS INTO ALIPHATIC HYDROCARBONS MORE UNSATURATED THAN THE STARTING PRODUCTS, COMBINING A STAGE OF STEAM CRACKING AND A STAGE OF PYROLYSIS |
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| CN100425940C (en) * | 2005-10-21 | 2008-10-15 | 中国石油化工股份有限公司 | High temperature cracking descaling set and method for tube bundle in large shell-and-tube heat exchanger |
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| MX2009011979A (en) * | 2007-05-07 | 2009-12-15 | Lummus Technology Inc | Ethylene furnace radiant coil decoking method. |
| US8137476B2 (en) | 2009-04-06 | 2012-03-20 | Synfuels International, Inc. | Secondary reaction quench device and method of use |
| WO2014039694A1 (en) * | 2012-09-06 | 2014-03-13 | Ineos Usa Llc | Medium pressure steam intervention in an olefin cracking furnace decoke procedure |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2289351A (en) * | 1939-04-06 | 1942-07-14 | Texas Co | Method of cleaning heater tubes |
| US3365387A (en) * | 1966-04-29 | 1968-01-23 | Exxon Research Engineering Co | Off-stream decoking of a minor portion of on-stream thermal cracking tubes |
| FR1532127A (en) * | 1966-07-25 | 1968-07-05 | Idemitsu Petrochemical Co | Advanced process for removing carbon deposits from thermal crackers |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2405364A (en) * | 1942-10-05 | 1946-08-06 | Phillips Petroleum Co | Hydrocarbon conversion process and apparatus |
| JPS503268B1 (en) * | 1966-07-25 | 1975-02-01 |
-
1980
- 1980-06-04 EP EP80103123A patent/EP0021167B1/en not_active Expired
- 1980-06-04 DE DE8080103123T patent/DE3060219D1/en not_active Expired
- 1980-07-28 IN IN863/CAL/80A patent/IN153444B/en unknown
-
1981
- 1981-07-08 US US06/281,344 patent/US4376694A/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2289351A (en) * | 1939-04-06 | 1942-07-14 | Texas Co | Method of cleaning heater tubes |
| US3365387A (en) * | 1966-04-29 | 1968-01-23 | Exxon Research Engineering Co | Off-stream decoking of a minor portion of on-stream thermal cracking tubes |
| FR1532127A (en) * | 1966-07-25 | 1968-07-05 | Idemitsu Petrochemical Co | Advanced process for removing carbon deposits from thermal crackers |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0036151A1 (en) * | 1980-03-15 | 1981-09-23 | BASF Aktiengesellschaft | Process for thermally decoking coolers for cracked gases |
| EP0143486A2 (en) * | 1983-10-31 | 1985-06-05 | Union Carbide Corporation | Method for on-line decoking of flame cracking reactors |
| EP0143486A3 (en) * | 1983-10-31 | 1986-04-16 | Union Carbide Corporation | Method for on-line decoking of flame cracking reactors |
| EP0591856A1 (en) * | 1992-10-05 | 1994-04-13 | Stone & Webster Engineering Corporation | Pulsed air decoking |
| FR2711374A1 (en) * | 1993-10-20 | 1995-04-28 | Schmidt Sche Heissdampf | Method of thermal decoking of a cracking furnace and the downstream cracking gas cooler. |
| EP2048217A2 (en) | 2007-10-12 | 2009-04-15 | Linde Aktiengesellschaft | Method for decarbonising cracking furnaces |
| EP2048217A3 (en) * | 2007-10-12 | 2012-06-06 | Linde AG | Method for decarbonising cracking furnaces |
Also Published As
| Publication number | Publication date |
|---|---|
| US4376694A (en) | 1983-03-15 |
| DE3060219D1 (en) | 1982-04-01 |
| IN153444B (en) | 1984-07-14 |
| EP0021167B1 (en) | 1982-03-03 |
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