EP0800564B1 - Procede de vaprocraquage flexible et installation de vapocraquage correspondante - Google Patents

Procede de vaprocraquage flexible et installation de vapocraquage correspondante Download PDF

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Publication number
EP0800564B1
EP0800564B1 EP95943261A EP95943261A EP0800564B1 EP 0800564 B1 EP0800564 B1 EP 0800564B1 EP 95943261 A EP95943261 A EP 95943261A EP 95943261 A EP95943261 A EP 95943261A EP 0800564 B1 EP0800564 B1 EP 0800564B1
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EP
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Prior art keywords
particles
zone
cracking
steam cracking
steam
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German (de)
English (en)
French (fr)
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EP0800564A1 (fr
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Eric Lenglet
Paul Broutin
Jean-Pierre Burzynski
Hervé CAZOR
Roland Huin
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Procedes Petroliers et Petrochimiques
IFP Energies Nouvelles IFPEN
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Procedes Petroliers et Petrochimiques
IFP Energies Nouvelles IFPEN
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G9/14—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
    • C10G9/16—Preventing or removing incrustation
    • 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 process for steam cracking of flexible hydrocarbons, that is to say compatible with a wide variety of fillers.
  • the steam cracking process is the basic process of the petrochemical industry and consists of cracking at high temperature and then brutally cooling a load of hydrocarbons and water vapor.
  • the main operational problem results from the deposition of carbonaceous products on the internal walls of the installation. These deposits, consisting of coke or heavy tars of condensed pyrolysis and more or less agglomerated, limit the heat transfer in the cracking zone (coil with pyrolysis tubes) and the indirect quenching zone (effluent quench exchanger), requiring frequent stops to decoker the installation.
  • the conventional cycle times (operation between two complete chemical decokings of the cracking zone, in air and / or steam) are either fixed (programmed stops), or variable depending on the coking of the installation, and s typically range from 3 weeks to 12 weeks for fillers such as naphtha and liquefied petroleum gases.
  • This process consists, for a determined charge, in allowing a layer of coke to form and mature on the internal walls of the cracking coil, then to inject erosive particles (for example hard mineral particles, of diameter less than 150 micrometers, spherical , or angular) in an amount sufficient to substantially stabilize the coking state of the tubes, without completely eliminating the coke pre-layer which has a protective role for these tubes.
  • erosive particles for example hard mineral particles, of diameter less than 150 micrometers, spherical , or angular
  • the efficiency of decoking has been found to depend significantly on the charges and operating conditions (different nature of the coke).
  • the light charges: C 3 , C 4 , light Naphtha produce at the start of the reaction zone a catalytic coke much more fragile (5 to 10 times) than the asymptotic coke predominant in the middle and at the end. of the reaction zone. It is therefore desirable for these charges to limit the speed of circulation in this zone, to maintain a protective coke layer and / or to avoid the risks of erosion of the cracking tubes.
  • the geometry of the cracking reactor adapted to a given load, with respect to the prevention of the risks of erosion, is not the same as that adapted to another load having a dilution rate and a nature different coke (for which the appropriate traffic speed profile will be different).
  • the applicants therefore propose a new process, flexible steam cracking, compatible with existing steam cracking installations, making it possible to treat various loads according to variable operating conditions, without degrading the thermal balance of the installations, without significant erosion risks, and with a cost moderate investment.
  • the process according to the invention provides for an amount of particles Q + q suitable for controlling TLE fouling, the quantity q being very insufficient for carry out all the erosive decoking of the pyrolysis tubes. This decoking is therefore carried out in mostly by means of chemical gasification.
  • the quantities of particles circulating in the pyrolysis tubes will generally be limited to a level such that the entire pyrolysis bundle can be kept without modification; the installation according to the method will thus be much less costly than that of the prior method carrying out the erosive decoking of the pyrolysis tubes which required the reinforcement and therefore the replacement of all the elbows.
  • the "erosive decoking" part of the process works to assist in limiting coking at the bottleneck, that is to say indirect quenching means, which are in an area with low circulation speed and relatively cold, where the metal is typically below 400 ° C, which considerably limits the risk of erosion. Furthermore, control of the process and of the quantities of particles injected is considerably easier because it is possible to know the temperature reliably outlet of the quench exchanger, which provides a precise indication of its degree fouling. This was not the case for the skin temperatures of the pyrolysis more difficult to measure, and influenced by the operating conditions flexible in fact imposing a "blind" decoking, for the decoking process complete erosion of the pyrolysis tubes under flexible conditions.
  • This process therefore makes it possible to treat heavy loads in an installation of steam cracking designed to crack naphtha, and to be able to change the charges to be cracked according to the "spot" prices of these charges, to also vary the severities, without taking risks for installation.
  • the particle injections can be determined so that the increase in the outlet temperature T of the indirect quenching means or less than 50 ° C per month, for example between 5 and 50 ° C per month, in particularly between 10 and 40 ° C per month, and preferably less than 30 ° C per month at during a steam cracking cycle.
  • a sufficient total quantity of particles is injected, that is to say an overall average rate [ Q + Q ] sufficient to substantially stabilize the outlet temperature of the indirect quenching means (TLE) during a steam cracking cycle.
  • no injections are made into the cracking zone, or upstream, only a small or zero amount of particles. This removes the risks of erosion of this area by letting the thickness of coke increase in this area or avoiding any significant erosion, even if, for certain loads, a layer of coke cannot be maintained at certain points in the tube bundle protective.
  • a limited quantity of particles can however be usefully injected into the tubes.
  • pyrolysis more particularly at the start of a steam cracking cycle, to eliminate a significant part of the filamentary catalytic coke which forms at the start of the cycle, and which is much more fragile.
  • the erosive efficiency strongly depends on the speed of circulation of the particles in the exchanger variable according to the types of exchangers and the installations, and on the other hand, the quantity of coke deposited, and its brittleness, strongly depend on the charges used, possible impurities (for example, traces of asphaltenes, or heavy aromatics such as ovalene, coronene for certain hydrotreated distillates), as well as operating conditions (severity of cracking, dilution).
  • This imprecision on the quantities of particles required is not a problem since the measurement of the outlet temperature of the quenching means, even under flexible conditions, allows reliable control of the process.
  • average rates will be used during a steam cracking cycle [ Q + q ] of particles injected upstream of the indirect quenching means ("TLE" exchanger) of between 20 and 1500 ppm relative to the cracked gases, in particular between 50 and 800 ppm. It is however possible for certain loads, and especially if using less aggressive particles, to inject larger quantities, for example up to 3000 ppm. Controlling the process is indeed very easy, the fouling of a quenching exchanger can be known from the simple outlet temperature of the effluents from this exchanger: this makes it possible to know whether the quantities of particles injected are adequate or s 'they must be increased, or on the contrary reduced.
  • the particles can be injected continuously, but the flow rates are then very low, which makes controlling the flow delicate. Also, it is preferable to inject the particles batchwise, sequentially, which makes it possible to use the same injection device for several quench exchangers, or several ovens, by successively feeding the particles at the different injection points in the installation.
  • the erosive particles are injected sequentially, at fixed or variable intervals of between 0.3 and 72 hours and preferably between 1 and 20 hours (for each of the quench exchangers).
  • the injections can be made at regular intervals, for example by modulating the quantity of particles injected to obtain the desired effect of controlling the fouling of the quench exchanger. It is also possible to inject the particles (for example a constant quantity) when the temperature of the indirect quenching means ("TLE" exchangers) exceeds a predetermined value.
  • TLE indirect quenching means
  • the ratio: Q + q total mass of particles injected total mass of cracked gases during a steam cracking cycle will generally be between 0.00002 and 0.0015 (which corresponds to the rate range already described, from 20 to 1500 ppm); on the other hand, the instantaneous rate of solid particles during an injection (typically carried out discontinuously during normal steam cracking operation) will be much higher, typically between 0.5 and 20% by weight, and preferably 1 and 10% weight compared to cracked gases.
  • particles comprising at least 20% by weight of angular particles, for example a mixture of two different types of particles.
  • the major part of the coke particles injected have undergone, generally before any final grinding to the particle size desired, during their manufacturing process, a temperature at least equal to 850 ° C (for example calcination at a temperature greater than or equal to 850 ° C). These particles stabilized at 850 ° C are much less likely to burst when they are introduced into the cracked gases at this temperature.
  • Particle injections are generally carried out during the operation of installation, under normal steam cracking conditions; the carrier gas particles in the quench exchanger tubes is then the cracked gas stream.
  • This change in charge allows the particles to be transported by a carrier gas composed of water vapor alone, or cracked gases of fillers such as naphtha, and to avoid potential heavy tar condensations.
  • a carrier gas composed of water vapor alone, or cracked gases of fillers such as naphtha, and to avoid potential heavy tar condensations.
  • this modification will be operated for short periods of time: For example, a circulation of water vapor alone for less than two hours, and preferably less than 1 hour and particularly 0.3 hours, this duration including the period when the particles are injected.
  • a circulation of water vapor alone for less than two hours, and preferably less than 1 hour and particularly 0.3 hours, this duration including the period when the particles are injected.
  • Such very brief interruptions in steam cracking, the oven remaining connected to the downstream sections, and swept by steam does not disturb very much the production of an installation with many ovens.
  • these very brief interruptions do not correspond, according to the definition adopted, to a new steam cracking cycle, and that a cycle of steam cracking corresponds to continuous or substantially continuous operation of the cracking of hydrocarbons, which may include very brief interruptions of the cracking, lasting less than 2 hours.
  • the carrier gas carrying the particles is therefore either a mixture hydrocarbons and water vapor (general case), i.e. water vapor only.
  • particles can be injected coke in the transfer area, at least a substantial part of which is not recovered before the effluent comes out of the oven, and therefore circulates to the downstream processing means effluents.
  • These non-recovered coke particles have an action of elimination of residual deposits in the lines downstream of the quench exchanger.
  • this operation can be modified at the time of particle injections, increasing the gas circulation speed from 10 to 50% cracked; this can be achieved by a momentary increase in the flow of hydrocarbons and water vapor or just the flow of water vapor.
  • the advantage of this provision is important because it increases the speed and therefore the erosive effect of the particles, and consequently to reduce the quantity of particles injected; this is particularly useful for non-recovered coke particles, which are trapped downstream in the fuel pyrolysis.
  • the particles injected into the transfer zone can be introduced at one or more points where the speed of circulation is reduced at least 25% compared to the speed of circulation in the terminal part of the zone cracked.
  • This has two important advantages: the particles introduced into a gas at reduced speed, acquire a lower kinetic energy, which, on the one hand greatly reduces the risk of erosion of the heat exchanger tube plate, and other part, reduces the production of 'fines' by bursting of particles on the tube plate, or on a suitable impactor.
  • the most suitable particle introduction points are generally located on the inlet cone of the quench exchanger.
  • This inlet cone by definition, is part of the transfer zone, and not indirect quenching means, these corresponding to the exchanger itself, that is to say to the cracked gas circulation tubes, which carry out indirect quenching.
  • the quantities of particles circulating in the cracking zone (2) being, according to the invention, insufficient to remove most of the coke formed in this zone, the invention provides a preponderant chemical decoking, at relatively intervals close together, or even continuous.
  • This chemical decoking can be carried out according to several variants which have in common the establishment of chemical gasification conditions accelerated coke, these conditions being accelerated compared to normal conditions steam cracking, where water vapor has a limited action of gasification of coke, in particularly by the reaction of gas with water.
  • a first variant consists in accelerating gasification by combustion of coke by circulation of air or air / water vapor mixtures; this variant is the process classic "air decoking", the oven being disconnected from downstream, and the supply of hydrocarbons interrupted.
  • a second known variant consists in interrupting the supply of the load hydrocarbon and gasify the coke by circulation of water vapor alone, or steam / hydrogen mixtures.
  • This "steam decoking" can be carried out either by leaving the oven connected with the downstream, either by disconnecting it, so as not to mix significant amounts of monoxides carbon CO with cracked gases.
  • Active compounds typically contain one or more mineral salts of elements from the group of alkaline and alkaline earth, for example a salt of an element from the potassium group, sodium, lithium, barium and strontium.
  • Active mineral salts are by example of oxide precursors of the elements considered, in particular carbonates, or carbonate precursors such as acetates.
  • salt compositions whose melting point is below 750 ° C, to promote their transfer to the walls of the pyrolysis tubes.
  • Compositions similar to eutectic for example an equimolar composition of potassium carbonate and sodium carbonate, is well suited. If we want inject incompatible compounds with each other at the level of their storage, we can use several flows and several storages.
  • These compounds can also be injected upstream of the cracking zone during “steam decoking” phases, previously described, for accelerate gasification (and only during these phases, if we fear a corrosion in the case of permanent injection).
  • the effluent can be subdivided indirect quenching means during these phases of gasification with steam, in a minor part which joins the downstream means, and a major part which is removed from the steam cracking effluent circuit.
  • the invention also provides an installation such that the particles are introduced. in the inlet cone of the quench exchanger, at at least one point, the point or points being located on the inlet cone, so that the passage section local cracked gas is at least 25% greater than the cross-section of the initial part of the transfer area, which reduces the risk of plaque erosion tubular exchanger and particle attrition.
  • the installation comprises metering means and batch injection of coke particles with an average diameter between 0.07 and 4 mm, which have good erosive efficiency and can be separated easily, connected to the transfer line for carrying out the introduction of all the coke particles injected upstream of the quench exchanger.
  • An installation according to the invention advantageously uses, in the cracking zone, pyrolysis tubes connected together by elbows which for the most part at least are classic unreinforced elbows, which eliminates a very high installation cost Student.
  • the invention also provides, according to a characteristic variant, an installation which includes metering and injection means upstream of the cracking zone of chemical gasification catalyst compounds comprising at least one compound active from the group of mineral salts of an element from the group of sodium, potassium, lithium, barium and strontium. These compounds greatly increase the duration of steam cracking cycle.
  • the installation comprises a device for simplified recovery of coke particles (particles of average diameter included between 0.07 and 4 mm introduced into the transfer zone); this device can be installed on at least one line for discharging cooled steam cracking effluents, comprising at least one oven outlet valve, the device being arranged between the outlet indirect quenching means such as a quench exchanger and the outlet valve oven.
  • the evacuation line includes, according to this device, a change of direction abrupt, of the type with simple deviation of an angle between 30 and 180 °, for evacuation of at least most of the steam cracking effluents, a particle recovery chamber located at the level of the abrupt change or in downstream, connected by a narrowing to a reservoir for receiving coke particles recovered, and means for keeping this tank under an incondensable atmosphere tank conditions.
  • This device takes advantage of the inertia of particles for separate from the gas, for at least part, due to the sudden change of direction. This device is much more economical than cyclone type devices, where the flow follows a helical trajectory.
  • the installation also includes means for implementation of a circulation of non-recovered coke particles, towards the means downstream.
  • it may include means for discontinuous introduction of a current gaseous, simultaneously with at least some of the injections of coke particles, to disturb the operation of the gas / solid separation means, and cause the circulation of at least part of the injected coke particles towards the means downstream.
  • This device is much simpler than an injection of coke particles downstream separation means, because it only uses a gas introduction additional, not additional means for introducing particles.
  • This new method according to the invention is much superior to the previous method both in from the point of view of the reliability and the elimination of the risks of erosion in flexible conditions, only from the point of view of the investment cost.
  • FIG. 1 shows schematically a steam cracking installation according to the invention, comprising several devices relating to different characteristic variants according to the invention.
  • FIG. 2 schematically represents two embodiments (FIGS. 2A and 2B) part of a steam cracking installation according to one of the variants features of the invention.
  • FIG. 1 where a steam cracking furnace (20) has been shown, delimited by its enclosure, comprising a zone (1) for preheating, convection, a cracking zone (2) with pyrolysis tubes, located in the radiation zone of the oven, a transfer area (3) comprising on the one hand a transfer line located just at the exit the cracking zone and on the other hand the inlet cone of a quenching exchanger (TLE), the cracked gas circulation tubes in this exchanger constituting means (4) indirect quenching of the steam cracking effluents coming from zone (2), at through the transfer area (3).
  • TLE quenching exchanger
  • the effluents from the quench exchanger are conveyed by a line (10) to downstream means (6) for treating cooled effluents, well known to those skilled in the art, which include for example direct quenching, primary fractionation means, compression, drying, desulfurization, refrigeration and final fractionation of constituents of cracked gases, to typically produce ethylene, propylene, a C4 cut, a petrol fraction and an oil fraction of pyrolysis.
  • the line (10) for discharging the cooled effluents also includes an oven outlet valve (VF) allowing its isolation from the downstream means (6) and passes through a gas / solids separator (S) for the recovery of particles.
  • the particles recovered in the separator (S) fall into a receiving tank (12), via a conduit, forming a narrowing, which includes an isolation valve (13).
  • Means (21) such as supplying a limited flow of barrier gas (water vapor, nitrogen or fuel gas) make it possible to maintain the receiving tank (12) under an atmosphere that cannot be condensed under the conditions of the tank.
  • a decoking line (19) is also connected to this conduit, and comprises a valve (VDK) called decoking valve.
  • This line is used during air decoking phases, or in air / steam mixtures, for the evacuation of the coke combustion gases to generally a "decoking pit", not referenced here.
  • the particles contained in the reservoir 12 are evacuated and eliminated or recycled by a line 30 to injection means 7.
  • a line, connected to line 10 and comprising a valve (14) allows, optionally, to subtract a major part of the gas rich in CO, during particular phases of decoking, by steam alone or by steam / hydrogen mixtures, so to reduce the average CO content of the cracked gases in the treatment means downstream (6), when using this particular decoking arrangement, according to one of the characteristic variants of the invention.
  • Line (10) also includes means (16) for measuring the temperature of the effluents from the quench exchanger, allowing the process control according to the invention. These means 16 can be connected optionally to the means 7 for metering and injecting solid particles.
  • Others means such as a line (25) allow the supply of a greater flow of gas to disturb the operation of the separation means (S) and allow circulation of coke particles to the downstream means (6), according to a variant of the process allowing to decoker the line (10) and the lines downstream of the line (10).
  • At least 70% by weight of the particles are introduced into the transfer area (3).
  • the particles are injected into the inlet cone of this exchanger, at a level such that the section of local passage of cracked gases is greater by at least 25%, for example by 40% to 400%, relative to the cross section of these gases in the initial part of the transfer area (3).
  • This limitation of the gas speed at the points of introduction particles is very beneficial because it greatly reduces the risk of erosion of the exchanger tube plate.
  • This tubular plate can also particularly advantageous to be protected by an impactor, not shown, located in the TLE inlet cone, just downstream of the particle introduction points, by example by a substantially opaque impactor, or at least 70% opaque seen from the arrival of gases in this inlet cone.
  • a gas permeable impactor consisting of several baffles, or rows of surfaces offset from each other to others will both protect the tubular plate of the TLE, and improve the distribution of the particles injected into the different tubes of this exchanger.
  • Such impactor will be shown diagrammatically in FIG. 2.
  • the particles are transported from the means (7) to their points of introduction, by pneumatic transport by means of a carrier gas, for example steam, or fuel gas, or nitrogen.
  • a carrier gas for example steam, or fuel gas, or nitrogen.
  • the installation includes means (15) for metering and injecting catalyzing chemical compounds gasification of coke by water vapor.
  • means (15) for metering and injecting catalyzing chemical compounds gasification of coke by water vapor For example, we could use dilute aqueous solutions of active mineral salts, e.g. solutions dilute aqueous sodium carbonate and potassium carbonate, especially compositions close to the eutectic such as a composition at 50 mol% of these two carbonates.
  • acetates of active compounds from the group of alkalis and alkaline earth, for example an equimolar composition of sodium acetate, acetate potassium, lithium acetate and barium acetate.
  • active compounds have shown surprising efficacy in accelerating the gasification of coke with water vapor, making it possible to reduce very strongly, or even to stop the coking of the pyrolysis tubes.
  • the installation described in Figure 1 also provides for injecting by means (15), in mixture or separately, of other types of chemical anti-smoking compounds, in particular of compounds making it possible to reduce the CO content in cracked gases, or having anti-coking activities (for example radical neutralization, with or without catalysis of gasification by steam).
  • other types of chemical anti-smoking compounds for example of compounds making it possible to reduce the CO content in cracked gases, or having anti-coking activities (for example radical neutralization, with or without catalysis of gasification by steam).
  • DMDS dimethyldisulfide
  • a suitable solvent such as water, hydrocarbons, hydrocarbon / alcohol, for example benzyldiethylphosphite
  • active compounds of phosphorus from the group of organic compounds (triethylphosphite, triphenylphosphite, and soluble phosphates or phosphites of sodium, potassium, lithium, barium, and preferably the compounds also having a catalyst effect gasification and / or anticorrosion action.
  • FIG. 1 also includes other means for establishing conditions for accelerated gasification of coke in the cracking zone (2): these means include introduction means (for example example the valve (18) for decoking air (AIR), and means for interrupting the supply of hydrocarbon (for example the valve (17)), allowing the circulation of decoking water vapor alone (possibly supplemented with hydrogen by means not shown).
  • introduction means for example the valve (18) for decoking air (AIR)
  • means for interrupting the supply of hydrocarbon for example the valve (17)
  • the installation includes means for introducing a hydrocarbon charge (HC), and means for introducing dilution water vapor (H 2 O) into the cracking zone. It also includes means making it possible to increase the volume flow rate of cracked gases in the quench exchanger from 10% to 50%, at the time of the particle injections, for example means (24) for supplying steam additional. One could also increase during the injections, the flow of hydrocarbons. This increase in the volume flow of the particles increases the speed, therefore the erosive effect, which makes it possible to reduce the quantities injected. This is particularly useful when injecting unrecovered and / or non-recycled coke. It is also possible to close off 4 to 30% of the cracked gas circulation tubes of the quench exchanger in order to increase the circulation speed and the erosive efficiency.
  • HC hydrocarbon charge
  • H 2 O dilution water vapor
  • FIG. 2A represents a quenching exchanger with cracked gas cooling tubes (4), with its cone input into which a quantity is introduced during a steam cracking cycle mean, Q, of solid particles from means (7) for metering, transporting and injection of solid particles.
  • Q a quantity is introduced during a steam cracking cycle mean, Q, of solid particles from means (7) for metering, transporting and injection of solid particles.
  • the impactor (23) positioned just downstream of the points of introduction of particles consists of two levels of impaction surfaces, offset, such so that it is both gas permeable and at least 70% opaque, and preferably substantially 100%, seen from the cracked gas inlet pipe.
  • This impactor provides a very effective additional protection of the tube plate against erosion, and also distribute the particles more evenly in the different tubes of the exchanger.
  • the cracked gases are conveyed by the line (10), comprising means (16) for measuring the temperature of the effluents from the exchanger quenching.
  • These means (16) effectively provide information on the degree of fouling of the exchanger and allow the process control, by modulating the quantities of particles injected or injection frequencies, so that the increase in exchanger outlet temperature does not exceed 100 ° C per month, and preferably 50 ° C per month.
  • this drift in temperature will be limited below 30 ° C per month, or inject the appropriate amounts of particles so that the outlet temperature of the exchanger remains substantially constant.
  • the cooled steam cracking effluents discharged by line 10 pass through the chamber (11) separation comprising a baffle imposing a change of direction abrupt to gas flow. This sudden change in direction causes the separation of a significant part of the particles conveyed by the gas, in particular of fragments of coke detached from the walls of the cracking zone (2) or particles injected according to the process.
  • the recovered particles fall into the reception (12), through a constriction comprising a valve (13); means (21) allow an inert gas to be injected (more precisely, a very bottom), i.e. a gas from the group consisting of water vapor, fuel gas, nitrogen, or condensation temperature less than or equal to 100 ° C., at atmospheric pressure. Thanks to the shrinking in accordance with a characteristic of the invention, the inert gas makes dam, going back into the chamber (11), which keeps the particles recovered in the tank (12) without condensation, keeping this tank at a sufficient temperature.
  • the tank By closing the valve (13), located at the narrowing, the tank can be isolated (12) and drain the particles which it contains, by means (22) of evacuation, gravitational, mechanical (especially screws), or pneumatic, comprising in particular a valve.
  • the decoking line (19), comprising the decoking valve (V DK ), which is used during air decoking phases of the cracking zone (2) is connected directly or indirectly to the line (10), upstream of the oven outlet valve (VF) to allow the evacuation of air decoking effluents.
  • the assembly formed by the chamber (11), the reservoir (12) and their narrowing connection conduit is disposed substantially at the connection between the evacuation line (10) and the decoking line (19).
  • Figure 2-B represents the same part of the installation but with a variant in the simplified solid particle recovery device: the recovery chamber (11) is not crossed by the flow of cracked gases circulating in the line (10), but is located immediately after the sudden change of direction (e.g. at a distance not exceeding 1.5 m, and preferably less than 0.8 m) Particles solids carried by the flow tend to continue straight, without realizing sudden change of direction, so that they are collected in the room (11) and recovered in the tank (12).
  • the sudden change of direction e.g. at a distance not exceeding 1.5 m, and preferably less than 0.8 m
  • FIGS. 2-A and 2-B are much more economical than a cyclic recovery from disaster.
  • the classic cyclone recovery mode with very high recovery efficiency, will be preferred when injecting mineral particles (therefore non-combustible), can cause significant pollution of the downstream processing means (6) and especially pyrolysis fuel; in such a case, almost total recovery of particles is desirable.
  • the particles injected into zone (3), and particularly at a point in the cone at slow speed of cracked gas circulation, are both more effective for decoking, and appreciable recoverable, for example at 60% by simplified means, particularly for coke particles of significant diameter, between 0.07 and 4 mm provided for this characteristic variant of the invention.
  • the invention is therefore characterized by steam cracking using jointly decoking essentially by erosion of the quench exchangers (TLE) and a essentially chemical decoking of the tubes of the cracking zone, with simple and reliable means of process control, and economical means of implementing in action.
  • TLE quench exchangers
  • the method according to the invention which provides for injecting at least 70% by weight of the particles in the transfer zone, these particles then circulate at reduced speed (compared to the speed in the pyrolysis tubes), with low wall temperatures and in substantially straight tubes without bends, no longer poses a risk of erosion important.
  • the installation and its characteristic variants operate as follows, detailed in the description which follows, and illustrated and explained by a series of practical examples:
  • the solid particles, which can be stored in a large capacity tank, of "new" particles, or in a tank in particular of smaller capacity containing a dose of particles having already circulated in a part of the installation, are dosed, by example by weighing, and sent discontinuously, sequentially to different parts of the installation (for example sequentially in the inlet cones of the different quench exchangers).
  • the powders are injected in doses, discontinuously.
  • a dose may typically comprise from 2 to 300 kg of particles, and preferably from 5 to 100 kg of particles.
  • the value of Q (Quantity of particles injected into the transfer zone, compared to the cracked gases during a steam cracking cycle) is 300 ppm: on average 3 Kg / h of particles per 10,000 Kg / h of cracked gas.
  • the value of q is 12 ppm (0.12 Kg / h of particles, as an average value over the entire steam cracking cycle, for 10,000 Kg / h of cracked gas). This example is therefore in accordance with the invention for the injection of particles, Q representing 96% of [ Q + q ].
  • this condition is not necessarily sufficient: the operator must in fact, depending on the load treated, adapt the quantities of particles so that the fouling of the quench exchanger remains moderate (more precisely than the increase in effluent temperature is less than 100 ° C per month, and preferably 30 ° C per month, or even is zero).
  • the operator will monitor the outlet temperature of the exchanger, by observing the temperature indicator (16), and may have to modify the quantities of particles injected, in particular Q . It could for example increase Q by injecting doses of particles over 30 Kg, and / or increasing the frequency of injections, or on the contrary decreasing Q if the value used appears excess. This observation can typically be made once a day, for a known load, and at shorter intervals during each change of operating conditions.
  • Another possible function is to inject a dose as soon as the temperature reaches a predetermined value (for example 430 ° C, if the admissible temperature limit is 450 ° C). These operations can be performed by the operator, manually or automated.
  • the powder doses can be conveyed by pneumatic transfer, using of a gas carrying a boiling temperature not exceeding 100 ° C at pressure atmospheric, typically water vapor, fuel gas (methane or methane / hydrogen) or nitrogen, in the diluted or dense phase depending on known techniques.
  • a gas carrying a boiling temperature not exceeding 100 ° C at pressure atmospheric typically water vapor, fuel gas (methane or methane / hydrogen) or nitrogen, in the diluted or dense phase depending on known techniques.
  • the process with erosion coke removal at the cracking zone and the quench exchanger is used to achieve substantially continuous operation.
  • the implementation of this process requires the change of all the elbows of the cracking zone of each of the ovens, and their replacement by special reinforced elbows (modified geometry, increased thickness, possibly change of materials).
  • a layer of coke is allowed to form, for example by steam cracking for 48 hours, under naphtha charge, then by injecting amounts of erosive particles with an average diameter of less than 150 micrometers, at the entrance to the zone. (2) in an amount sufficient to remove at least most of the coke formed.
  • angular corundum with an average diameter of 70 micrometers is used, injected entirely at the entrance to the cracking zone (2), by injections spaced 2 to 5 hours apart.
  • This quantity can be modulated, for example raised to 5500 ppm when heavy loads are cracked (diesel, vacuum distillate), and also modulated from the indications provided by the pyrometers measuring the skin temperatures of the tubes.
  • This installation does not carry out a substantially steam cracking continuous, but allows to operate with great security with regard to problems technological (erosion), under flexible load conditions. Moreover, the equipment to equip an existing oven is much more economical than in Example 2, where changing the elbows involves an additional cost greater than 30%.
  • This installation makes it possible to operate in flexible mode, with cycle times generally exceeding 60 days for the loads considered.
  • We can also inject a small amount q angular silicon carbon with an average diameter of 70 micrometers, for example q 15 ppm at the entry of zone (2), to increase the cycle time (from 5 to 20%). This injection is performed during the first 72 hours of the cycle.
  • the particle injections are carried out during the normal steam cracking operation.
  • Coke can be injected from 20 to 400 ppm, by injections spaced 8 to 12 hours apart, for example, to limit the drift of the outlet temperature to 30 ° C per month maximum.
  • the efficiency of the particles can be increased by increasing, by means of injections, the volume flow rate of cracked gases by 20 to 30% by addition of additional water vapor.
  • the decoking of the pyrolysis tubes in zone (2), for examples 4 and 5 can be made with steam, or with air / steam mixtures, or else use additives chemical gasification catalysts, either during steam cracking or during steam decoking phases.
  • the invention therefore makes it possible to operate with flexibility significant expense, in a manner compatible with existing installations, in particular by retaining existing quench exchangers which give a balance favorable energy, economically and technologically reliable, which could not be achieved by any of the known methods.

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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)
EP95943261A 1994-12-26 1995-12-22 Procede de vaprocraquage flexible et installation de vapocraquage correspondante Expired - Lifetime EP0800564B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9415743 1994-12-26
FR9415743A FR2728578A1 (fr) 1994-12-26 1994-12-26 Procede de vapocraquage flexible et installation de vapocraquage correspondante
PCT/FR1995/001717 WO1996020255A1 (fr) 1994-12-26 1995-12-22 Procede de vaprocraquage flexible et installation de vapocraquage correspondante

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EP0800564A1 EP0800564A1 (fr) 1997-10-15
EP0800564B1 true EP0800564B1 (fr) 1998-10-21

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US (1) US5972206A (enrdf_load_stackoverflow)
EP (1) EP0800564B1 (enrdf_load_stackoverflow)
DE (1) DE69505563T2 (enrdf_load_stackoverflow)
ES (1) ES2128801T3 (enrdf_load_stackoverflow)
FR (1) FR2728578A1 (enrdf_load_stackoverflow)
TW (1) TW364011B (enrdf_load_stackoverflow)
WO (1) WO1996020255A1 (enrdf_load_stackoverflow)

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FR2750139B1 (fr) * 1996-06-25 1998-08-07 Inst Francais Du Petrole Installation et procede de vapocraquage a injection unique controlee de particules solides dans un echangeur de trempe
FR2750138B1 (fr) * 1996-06-25 1998-08-07 Inst Francais Du Petrole Procede et dispositif de vapocraquage comprenant l'injection de particules en amont d'un echangeur de trempe secondaire
US6585883B1 (en) * 1999-11-12 2003-07-01 Exxonmobil Research And Engineering Company Mitigation and gasification of coke deposits
US6406613B1 (en) 1999-11-12 2002-06-18 Exxonmobil Research And Engineering Co. Mitigation of coke deposits in refinery reactor units
US6821411B2 (en) * 2001-08-16 2004-11-23 Chevron Phillips Chemical Company Lp Steam injection system on the TLE cones of a hydrocarbon cracking furnace
CN1219851C (zh) * 2004-02-10 2005-09-21 郝继武 加热、裂解废塑料、橡胶、石蜡、重油的化工设备
US7513260B2 (en) 2006-05-10 2009-04-07 United Technologies Corporation In-situ continuous coke deposit removal by catalytic steam gasification
US20090022635A1 (en) * 2007-07-20 2009-01-22 Selas Fluid Processing Corporation High-performance cracker
US7964090B2 (en) * 2008-05-28 2011-06-21 Kellogg Brown & Root Llc Integrated solvent deasphalting and gasification
WO2013004544A1 (en) * 2011-07-07 2013-01-10 Ineos Europe Ag Process and apparatus for producing olefins with heat transfer from steam cracking to alcohol dehydration process.
CN103131458A (zh) * 2011-12-05 2013-06-05 洛阳瑞泽石化工程有限公司 常减压装置
ITRM20120162A1 (it) 2012-04-16 2013-10-17 Marcello Ferrara Metodo e impianto per il trattamento di apparecchiature petrolifere
CA3166744A1 (en) * 2020-01-22 2021-07-29 Nova Chemicals Corporation High gas velocity start-up of an ethylene cracking furnace

Family Cites Families (6)

* Cited by examiner, † Cited by third party
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DE3010000A1 (de) * 1980-03-15 1981-09-24 Basf Ag, 6700 Ludwigshafen Verfahren zur thermischen entkokung von spaltgaskuehlern
US5415816A (en) * 1986-01-28 1995-05-16 Q2100, Inc. Method for the production of plastic lenses
EP0361651B1 (en) * 1988-08-30 1995-12-06 Mitsubishi Denki Kabushiki Kaisha Optical element and method of modulating light by using the same
ATE109194T1 (de) * 1989-04-14 1994-08-15 Procedes Petroliers Petrochim Verfahren zum dampfkracken von kohlenwasserstoffen.
FR2652817B1 (fr) * 1989-10-06 1993-11-26 Procedes Petroliers Petrochimiqu Procede et installation de vapocraquage d'hydrocarbures, a recyclage de particules solides erosives.
ATE114705T1 (de) * 1989-04-14 1994-12-15 Procedes Petroliers Petrochim Verfahren und apparat zur entkoksung von dampfkrackanlagen.

Also Published As

Publication number Publication date
DE69505563D1 (de) 1998-11-26
EP0800564A1 (fr) 1997-10-15
WO1996020255A1 (fr) 1996-07-04
FR2728578B1 (enrdf_load_stackoverflow) 1997-02-07
ES2128801T3 (es) 1999-05-16
FR2728578A1 (fr) 1996-06-28
US5972206A (en) 1999-10-26
DE69505563T2 (de) 1999-03-11
TW364011B (en) 1999-07-11

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