EP0447527A1 - Hydrocarbon vapocracking installation with recycling of erosive solid particles. - Google Patents

Hydrocarbon vapocracking installation with recycling of erosive solid particles.

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Publication number
EP0447527A1
EP0447527A1 EP90914930A EP90914930A EP0447527A1 EP 0447527 A1 EP0447527 A1 EP 0447527A1 EP 90914930 A EP90914930 A EP 90914930A EP 90914930 A EP90914930 A EP 90914930A EP 0447527 A1 EP0447527 A1 EP 0447527A1
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EP
European Patent Office
Prior art keywords
solid particles
cyclone
quenching
installation according
installation
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
Application number
EP90914930A
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German (de)
French (fr)
Other versions
EP0447527B1 (en
Inventor
Eric Lenglet
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Procedes Petroliers et Petrochimiques
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Procedes Petroliers et Petrochimiques
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Publication of EP0447527A1 publication Critical patent/EP0447527A1/en
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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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
    • F28G1/00—Non-rotary, e.g. reciprocated, appliances
    • F28G1/12—Fluid-propelled scrapers, bullets, or like solid bodies

Definitions

  • the invention relates to an installation for steam cracking of hydrocarbons, for recycling erosive solid particles.
  • the object of the invention is in particular to avoid this drawback and to recycle solid particles with means of current design, or with a long service life.
  • the invention also aims to easily regulate the flow rate of solid particles recycled in the steam cracking installation, ensuring high reliability of the decoking means vis-à-vis the integrity of the equipment.
  • an installation for steam cracking of hydrocarbons comprising at least one furnace. 2 for cracking hydrocarbons, an indirect quenching exchanger for the effluents leaving the furnace, and means for direct quenching of the effluents, as well as means for injecting into the furnace a low flow rate of fine solid particles and means, such as a cyclone, placed between the indirect quenching exchanger and the direct quenching means for the separation of solid particles and gaseous steam cracking effluents, characterized in that it comprises a storage tank for solid particles, of which the inlet is connected to the solids outlet of the cyclone and the outlet of which is connected to a pipe for injecting particles into the installation, means for isolating this tank, such as valves, and a source of pressurized gas connected on the one hand to the solid particle injection pipe and on the other hand to the tank by means such as a valve for increasing the internal pressure of this tank to a value at least equal that the point of injection of the particles in the 20
  • the injection of solid particles into the oven during its operation is then discontinued.
  • the aforementioned reservoir makes it possible to store the solid particles during the phase of non-injection of particles or of non-decoking.
  • the solid particles can be brought to a sufficient pressure and easily recycled, in the form of a solid suspension in dilute phase, to the point of injection into the installation. steam cracking and without the need to use a very high speed carrier gas stream. This greatly reduces the erosion of the means for recycling solid particles.
  • 35 providing the carrier gas stream also serves to increase the pressure in the storage tank solid particles. Due to the pressure balancing which is thus obtained, an overpressure liable to compact the solid particles or to cause too sudden evacuation of the particles from the tank is avoided.
  • the installation comprises an intermediate tank mounted between the outlet of the cyclone and the inlet of the aforementioned tank, and means for isolating this intermediate tank, such as valves.
  • the installation comprises a pipe connected as a bypass to the indirect quenching exchanger, between the outlet of the cracking furnace and the aforementioned cyclone, in order to take a small fraction of the outgoing gaseous effluent flow from the oven and to dry the solid particles by direct contact with this fraction removed, at a temperature corresponding to an almost total absence of liquid on said solid particles.
  • the cracked gases leaving the indirect quench heat exchanger 1 are at a temperature generally between 350 and 600 ° C, limiting the side reactions, and yet high enough so that these gases do not contain substantially no liquid. It is however possible, when the charge to be steam cracked is heavy (diesel or heavy naphtha for example) that these gases contain a mist of very heavy hydrocarbons, or tars, or "liquid" coke.
  • the invention makes it possible to vaporize or carbonize most of these liquid traces, without using known means consisting of burning these liquids in the presence of oxygen, very delicate to carry out from the point of view of safety.
  • the increase in temperature of the solid particles leaving the indirect quenching exchanger is approximately 30 to 250 ⁇ C to vaporize or carbonize, as the case may be, traces of liquid.
  • the steam cracking installation can therefore be used with relatively heavy loads liable to lead to traces of condensed hydrocarbons leaving the indirect quench exchanger, without it being necessary to impose a too high permanent temperature at the outlet. of this indirect quenching exchanger, which would lead to energy losses during the operation of the installation.
  • the bypass can indeed only be put into service during particle injection periods.
  • This simple method of drying the solid particles also prevents them from sticking during separation in the cyclone or recycling via the aforementioned tanks.
  • this bypass pipe is connected to the conduit connecting the indirect quenching exchanger to the cyclone, upstream of the cyclone (possibly just at the outlet of the quenching exchanger). The fraction of the effluent flow rate taken off the furnace is then mixed with the effluent flow rate leaving the indirect quenching exchanger, before separation of the solid particles in the cyclone.
  • the bypass pipe is connected to the solids exit from the cyclone and lead to a secondary cyclone at high temperature, sufficient to ensure the vaporization and / or carbonization of the traces of liquid present on the solid particles.
  • the solid particles leaving the main cyclone are entrained by a small flow of gaseous effluents, which avoids their sticking before their overheating by contact with the abovementioned fraction taken from the flow of gaseous effluents leaving the oven.
  • the secondary cyclone can have much smaller dimensions than that of the main cyclone and operates at a higher temperature, which allows either vaporization or carbonization of the traces of liquid present on the solid particles.
  • the installation also comprises means for pre-quenching said fraction taken from the flow of gaseous effluents, these means being provided in the vicinity of the upstream end of said bypass pipe and comprising for example means for injecting dilution vapor.
  • the presoaked may consist of a cooling (by direct contact with a gas) of between 70 and 200 ° C leaving the furnace effluent and collected in the bypass.
  • the outputs of the indirect quenching exchangers of the ovens are connected to common means for separating and recycling solid particles, including the aforementioned cyclones and reservoirs.
  • the outputs of the indirect quench exchangers are connected to the common means of separation and recycling of solid particles by bypass pipes which are provided with isolation valves and which are connected to the pipes connecting these outlets to the direct quenching means. .
  • the isolation valves of these bypass pipes remain permanently in the open position. They then do not fulfill a sealing function and are, for example, simple, non-waterproof shutters.
  • An installation of this type has a number of important advantages: the decoking of the various steam cracking ovens can be carried out sequentially, without the need to use large-diameter isolation valves specially designed for the passage of gas. loaded with erosive particles, which are extremely expensive, - bypass pipes through which gaseous effluents pass loaded with solid particles are never connected to the atmosphere, nor to a source of oxygen-containing gas, which is a important safety factor; - The general reliability of the installation is greatly increased by the fact that the abovementioned isolation valves remain in the open position and are in principle not operated during normal operation of the installation, unlike the known methods in which completely isolates the circuit during decoking;
  • FIG. 1 is a diagrammatic representation of part of the means for recycling solid particles according to the invention, in a first state;
  • FIG. 2 represents another state of these means;
  • FIG. 3 represents a steam cracking installation according to the invention, allowing the drying of solid particles;
  • Figure 4 shows an alternative embodiment of this installation;
  • FIG. 5 represents a steam cracking installation according to the invention, of the type comprising several steam cracking ovens arranged in patallel.
  • FIGS. 1 and 2 show, by way of example, part of the means for recycling solid particles according to the invention.
  • These means comprise a cyclone 10, which is supplied by a heat exchanger carrying out an indirect quenching of the gaseous effluents leaving a hydrocarbon steam cracking furnace, and which comprises, in the upper part, an outlet 12 for gaseous effluents leading to direct quenching means and, in the lower part, an outlet 14 for solid particles separated from the gaseous effluents in the cyclone 10.
  • the outlet 14 is connected by an isolation valve 16 to the upper inlet 18 of a tank 20 comprising means 22, such as a screen, for separating and retaining coarse solid particles, as well as an orifice 24 for discharging these particles.
  • the lower part of the tank 20, in which the fine solid particles collect is connected by a motorized rotating member 26, of the rotary airlock type, screw or rotary lock, and by a valve.
  • the outlet of the reservoir 30 is connected, downstream of the valve 34, to a conduit 36 for recycling solid particles in the steam cracking installation.
  • a source 38 of pressurized gas supplies the conduit 36 with a gas flow at medium or relatively low speed.
  • a three-way valve 40 makes it possible to connect the reservoir 30 either to the source of pressurized gas 38, or to the conduit 12 for the gas outlet from the cyclone. Stop valves 42 are provided in the conduits connecting the valve 40 to the source of pressurized gas 38 and to the conduit 12 respectively.
  • An independent reservoir 44 filled with solid particles of determined average particle size allows, by means of a motorized rotating member 46 and an isolation valve 48, to inject an addition of solid particles into the recycling conduit 36
  • the upper part of the reservoir 44 is connected to the outlet of this reservoir by a pressure equalization conduit 50.
  • the rotating member 46 makes it possible to regulate the flow of make-up particles.
  • the reservoir 20 may be provided, in the lower part, with a purge duct 52, making it possible to withdraw a certain quantity of solid particles.
  • a barrier gas inlet pipe 53 opens into the upper part of the reservoir 20.
  • the barrier gas is free of heavy aromatics and may be water vapor. It avoids coking of the tank 20 and the sieve 22.
  • the downstream isolation valve 34 of this reservoir is open, the rotating member 32 is rotated and the internal volume of the reservoir 30 is connected to the source of pressurized gas 38 via the valve 40, the corresponding stop valve 42 being open.
  • the gas delivered by the source 38 is at a pressure which is at least equal to or slightly greater than the pressure at the point of injection of the solid particles in the steam cracking installation and which is greater than the pressure in the outlet conduit 12 of the cyclone 10.
  • the internal pressure of the reservoir 30 is therefore increased relative to that of the upper reservoir 20 and is in equilibrium with the pressure in the recycling conduit 36.
  • the source 38 delivers in this conduit a gas flow at relatively low speed between 5 and 25 m / s, for example between 10 and 20 m / s, which makes it possible to transport the solid particles in dilute suspension up to at least one injection point in the steam cracking installation.
  • the low speed of the carrier gas stream prevents significant erosion of the recycling conduit.
  • the isolation valve 34 is closed and the reservoir 30 is connected to the cyclone outlet conduit 12 via the valve 40.
  • the reservoir 30 is then at the same pressure as the upper reservoir 20, and it it suffices to open the isolation valve 28 and to drive the rotating member 26 so that the solid particles contained in the reservoir 20 can be transferred to the reservoir 30.
  • the pressures between these two reservoirs could be equalized, not at the pressure of the cyclone 10, but at the pressure of the gas source 38, after having isolated the tank 20, and having connected it to the gas source 38
  • the purge duct 52 makes it possible to remove an excess of solid particles from the tank 20, an excess consisting of a mixture of abrasive particles coming from the auxiliary tank and coke particles detached from the internal walls of the installation. steam cracking. Regular purging of the tank 20 makes it possible to avoid the accumulation of solid particles of medium size in the flow of recycled particles in the installation, and to reduce the coke concentration there.
  • the make-up tank 44 makes it possible to add the desired quantity of solid particles having the desired particle size into the flow of recycled particles.
  • the motorized rotating members which are interposed between the tank outlets and their downstream isolation valves, make it possible to regulate the flow of solid particles leaving the tanks and to avoid obstruction or blockage of the downstream valves.
  • the reservoirs 20, 30 can be arranged in parallel and not in series. Referring now to Figure 3, in which there is shown schematically means' of drying solid particles used for decoking the installation.
  • This plant comprises a steam cracking furnace, generally designated by the reference 54, the output gaseous effluent is connected to the input r of a heat exchanger 56 indirect quenching.
  • the outlet of this exchanger is connected to the inlet of cyclone 10, whose gas outlet 12 is connected to the means 58 for direct quenching of the gaseous effluents, and whose solids outlet 14 is connected to the aforementioned means 20, 30 for storage solid particles.
  • the invention provides a bypass pipe 60, the upstream end of which is connected to the outlet pipe of the furnace 54, upstream of the quench exchanger 56, and the downstream end of which is connected to the pipe of outlet of the quench exchanger 56 upstream of the inlet of the cyclone 10.
  • This bypass pipe 60 comprises a calibrated orifice 62, making it possible to take a small fraction of the flow of gaseous effluents leaving the oven 54.
  • means 64 for indirect quenching such as means for injecting a certain quantity of steam dilution.
  • the gaseous effluents which leave the oven 54 at a temperature of approximately 850 ° C. are cooled to approximately 700 ° C. in the pipe 60.
  • the gases leaving the indirect quench exchanger 56 are for example at a temperature of about 400 ° C and are heated by direct contact with the waste gas supplied by the bypass line 60 at a temperature for example of about 480 ° C. This rise in temperature is in principle sufficient to vaporize the traces of liquid present in the flow of gaseous effluents entering the cyclone 10.
  • FIG. 4 represents an alternative embodiment of these means for drying solid particles.
  • the bypass pipe 60 is connected to the solids outlet 14 of the cyclone 10 and leads to the inlet of an auxiliary cyclone 70 having dimensions considerably smaller than those of the above-mentioned cyclone 10.
  • the gas outlet 72 cyclone 70 is connected to the inlet of the direct quenching means 58, by means of an ejector 74 or similar means.
  • the exit of solids from auxiliary cyclone 70 leads to storage tanks 20, 30 mentioned above.
  • the operation of this variant is as follows.
  • a small fraction of the flow of gaseous effluents leaving the oven 54 is sampled by the bypass pipe 60 and mixed with a small flow of gaseous effluents leaving with the solid particles of the main cyclone 10, to be introduced into the auxiliary cyclone 70.
  • the hot gases leaving the cyclone 70 are returned via the ejector 74 to the means 58 for direct quenching.
  • the valve 66 of Figures 3 and 4 must be designed to operate at high temperature and resist the erosive particles which pass through it. This type of valve is expensive. It can be eliminated by connecting to the pipe 60, upstream from calibrated orifices 62, a conduit 75 for supplying a relatively cold barrier gas which prevents the removal of effluents from the oven, outside from decoking periods. Such a barrier gas can be taken from outlet 12 of cyclone 10 and recompressed, for example by an ejector, as shown in the drawing. This barrier gas can also be used for the pre-quenching of the gaseous effluents sampled during the decoking periods. Under these conditions, the means 64, 68 can be omitted. Finally, as shown in Figure 4, the embodiments of Figures 3 and 4 can be combined.
  • FIG. 5 schematically shows a steam cracking installation according to the invention, comprising several cracking ovens arranged in parallel.
  • This installation is of the sequential decoking type of cracking ovens and comprises conduits 36 for injecting solid particles connecting the aforementioned storage means 20, 30 to the points of injection of particles into the ovens 54, each of these conduits 36 comprising a small shut-off valve 78 immediately upstream from the point of injection into each furnace 54.
  • the outputs of the indirect quenching exchangers 56 are moreover connected, by bypass pipes 80 comprising isolation valves 82, to common means for separating solid particles comprising at least one cyclone 10 of the aforementioned type.
  • the solids outlet 14 of this cyclone is connected to the aforementioned storage means 20, 30, and the gas outlet 12 of the cyclone is connected, with the conduits 76, to the inlet of the direct quenching means 58.
  • conduits 76 include isolation valves 84, provided downstream of the branching of the branch pipes 80.
  • This installation can be used in the following manner: When the decoking of a cracking oven has to be carried out, for example that of the oven 54 l the isolation valve 84 of its conduit 76 is closed while the valve 82 of the corresponding bypass pipe 80 is open. The injection of solid particles into the oven 54-L is carried out by opening the corresponding stop valve 78.
  • valves 84 of the conduits 76 of the other ovens are open, and the valves 82 of the bypass pipes 80 of these other ovens are closed, so that the flow of gaseous effluents and solid particles leaving the oven 54 x passes through the cyclone 10, while the flow rates of gaseous effluents leaving the other ovens directly reach the means 58 for direct quenching.
  • the corresponding valve 78 is closed, the valve 84 is opened and the valve 82 associated with this oven is closed, then the operations already described for the oven 54 2 are repeated. decoking the oven 54 x . -
  • valves 82 of the bypass lines 80 are operated relatively frequently.
  • these valves are extremely expensive, since they are designed to be traversed by large flows of gas charged with erosive particles. It is therefore preferable to operate this installation as follows: all the valves 82 are left open at all times.
  • the associated valve 84 is closed and an injection of erosive solid particles is carried out in this oven, by opening the corresponding valve 78.
  • the valves 84 associated with the other ovens are open, as are the valves 82 of the corresponding bypass pipes.
  • valves 82 remain permanently in the open position.
  • valves 82 it is possible to use much less expensive valves than in the previous case, for example non-watertight means such as shutters, to regulate the flow rates of gaseous effluents which pass through the pipes 80, during the periods of decoking and outside these periods.
  • the invention also applies to the sequential decoking of different passes of the same oven opening into indirect quench exchangers, the outlets of which are connected by branches to common means of separation and recycling of solid particles.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Thermal Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Organic Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Cyclones (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Fertilizers (AREA)

Abstract

PCT No. PCT/FR90/00711 Sec. 371 Date May 30, 1991 Sec. 102(e) Date May 30, 1991 PCT Filed Oct. 5, 1990 PCT Pub. No. WO91/05031 PCT Pub. Date Apr. 18, 1991.An installation for steam cracking hydrocarbons comprises at least one hydrocarbon cracking furnace, an indirect quench heat exchanger for the effluents leaving the furnace, direct quench means for said effluent, and means (36, 38) for injecting erosive solid particles into the installation for decoking purposes. The installation also includes a cyclone (10) placed at the outlet from the indirect quench heat exchanger to separate the solid particles from the gaseous effluent, with the solid particle outlet (14) from said cyclone being connected to storage tanks (20, 30) connected in series with isolating valves (16, 28, 34), a source (38) of gas under pressure being provided to raise the pressure in one of the tanks and to inject the solid particles into the installation.

Description

INSTALLATION DE VAPOCRAQUAGE D'HYDROCARBURES, A RECYCLAGE DE PARTICULES SOLIDES ERQSXVES. HYDROCARBON VAPOCRACKING PLANT, WITH RECYCLING OF ERQSXVES SOLID PARTICLES.
L'invention concerne une installation de vapocraquage d'hydrocarbures, à recyclage de particules solides érosives.The invention relates to an installation for steam cracking of hydrocarbons, for recycling erosive solid particles.
On a déjà proposé de réaliser le décokage d'une installation de vapocraquage d'hydrocarbures, au moyen de particules solides érosives de fine granulométrie, qui sont injectées dans la charge d'hydrocarbures à craquer et qui sont séparées, par centrifugation dans un cyclone, des effluents gazeux sortant d'un four de craquage ou d'un échangeur de trempe indirecte placé lui-même à la sortie du four de craquage. On remonte ensuite le niveau des particules solides ainsi récupérées, pour les réinjecter en amont de la zone de craquage, au moyen d'un éjecteur produisant un courant de gaz à vitesse élevée. Il peut donc en résulter une érosion relativement rapide et importante des moyens de recyclage des particules solides, qui impose l'utilisation d'équipements de conception spéciale (revêtement anti-abrasion) qui sont onéreux et ont une durée de vie éventuellement courte.It has already been proposed to decoke an installation for steam cracking of hydrocarbons, by means of erosive solid particles of fine particle size, which are injected into the charge of hydrocarbons to be cracked and which are separated, by centrifugation in a cyclone, gaseous effluents leaving a cracking furnace or an indirect quenching exchanger itself placed at the outlet of the cracking furnace. The level of the solid particles thus recovered is then raised, in order to reinject them upstream of the cracking zone, by means of an ejector producing a stream of gas at high speed. This can therefore result in relatively rapid and significant erosion of the means for recycling solid particles, which requires the use of specially designed equipment (abrasion-resistant coating) which is expensive and has a possibly short lifespan.
L'invention a notamment pour but d'éviter cet inconvénient et de réaliser le recyclage des particules solides avec des moyens de conception courante, ou à longue durée de vie.The object of the invention is in particular to avoid this drawback and to recycle solid particles with means of current design, or with a long service life.
L'invention a également pour but une régulation facile du débit de particules solides recyclées dans l'installation de vapocraquage, assurant une grande fiabilité des moyens de décokage vis-à-vis de 1'intégrité des équipements.The invention also aims to easily regulate the flow rate of solid particles recycled in the steam cracking installation, ensuring high reliability of the decoking means vis-à-vis the integrity of the equipment.
Elle a également pour but d'empêcher le collage des particules solides, sous l'effet de traces de liquide, au moment de la séparation ou du recyclage de ces particules solides.It also aims to prevent the sticking of solid particles, under the effect of traces of liquid, at the time of separation or recycling of these solid particles.
Elle propose à cet effet une installation de vapocraquage d'hydrocarbures, comprenant au moins un four 2 de craquage des hydrocarbures, un échangeur de trempe indirecte des effluents sortant du four, et des moyens de trempe directe des effluents, ainsi que des moyens d'injection dans le four d'un faible débit de fines 5 particules solides et des moyens, tels qu'un cyclone, placés entre 1'échangeur de trempe indirecte et les moyens de trempe directe pour la séparation des particules solides et des effluents gazeux de vapocraquage, caractérisée en ce qu'elle comprend un 10 réservoir de stockage des particules solides, dont l'entrée est raccordée à la sortie des solides du cyclone et dont la sortie est raccordée à un conduit d'injection des particules dans l'installation, des moyens d'isolement de ce réservoir, tels que des vannes, et une 15 source de gaz sous pression reliée d'une part au conduit d'injection de particules solides et d'autre part au réservoir par des moyens tels qu'une vanne pour augmenter la pression interne de ce réservoir à une valeur au moins égale à celle du point d'injection des particules dans le 20 four.To this end, it offers an installation for steam cracking of hydrocarbons, comprising at least one furnace. 2 for cracking hydrocarbons, an indirect quenching exchanger for the effluents leaving the furnace, and means for direct quenching of the effluents, as well as means for injecting into the furnace a low flow rate of fine solid particles and means, such as a cyclone, placed between the indirect quenching exchanger and the direct quenching means for the separation of solid particles and gaseous steam cracking effluents, characterized in that it comprises a storage tank for solid particles, of which the inlet is connected to the solids outlet of the cyclone and the outlet of which is connected to a pipe for injecting particles into the installation, means for isolating this tank, such as valves, and a source of pressurized gas connected on the one hand to the solid particle injection pipe and on the other hand to the tank by means such as a valve for increasing the internal pressure of this tank to a value at least equal that the point of injection of the particles in the 20 oven.
L'injection des particules solides dans le four pendant son fonctionnement est alors discontinue. Le réservoir précité permet de stocker les particules solides pendant la phase de non-injection de particules 25 ou de non-décokage. Ensuite, grâce à une augmentation de pression statique dans le réservoir, les particules solides peuvent être portées à une pression suffisante et recyclées facilement, sous forme d'une suspension solide en phase diluée, jusqu'au point d'injection dans 30 l'installation de vapocraquage et sans qu'il soit nécessaire d'utiliser un courant de gaz vecteur à vitesse très élevée. On réduit ainsi largement l'érosion des moyens de recyclage des particules solides.The injection of solid particles into the oven during its operation is then discontinued. The aforementioned reservoir makes it possible to store the solid particles during the phase of non-injection of particles or of non-decoking. Then, thanks to an increase in static pressure in the tank, the solid particles can be brought to a sufficient pressure and easily recycled, in the form of a solid suspension in dilute phase, to the point of injection into the installation. steam cracking and without the need to use a very high speed carrier gas stream. This greatly reduces the erosion of the means for recycling solid particles.
Par ailleurs, la source de gaz sous pressionIn addition, the source of gas under pressure
35 fournissant le courant de gaz vecteur sert également à l'augmentation de pression dans le réservoir de stockage des particules solides. Du fait de l'équilibrage de pression qui est ainsi obtenu, on évite une surpression susceptible de compacter les particules solides ou de provoquer une évacuation trop brutale des particules du réservoir.35 providing the carrier gas stream also serves to increase the pressure in the storage tank solid particles. Due to the pressure balancing which is thus obtained, an overpressure liable to compact the solid particles or to cause too sudden evacuation of the particles from the tank is avoided.
Selon une autre caractéristique de l'invention, l'installation comprend un réservoir intermédiaire monté entre la sortie du cyclone et l'entrée du réservoir précité, et des moyens d'isolement de ce réservoir intermédiaire, tels que des vannes.According to another characteristic of the invention, the installation comprises an intermediate tank mounted between the outlet of the cyclone and the inlet of the aforementioned tank, and means for isolating this intermediate tank, such as valves.
Ce réservoir intermédiaire permet de stocker les particules solides sortant du cyclone, pendant qu'une injection de particules solides dans l'installation est réalisée à partir du premier réservoir cité. Selon une autre caractéristique de l'invention, l'installation comprend une canalisation branchée en dérivation sur 1'échangeur de trempe indirecte, entre la sortie du four de craquage et le cyclone précité, pour prélever une faible fraction du débit d'effluents gazeux sortant du four et pour sécher les particules solides par contact direct avec cette fraction prélevée, à une température correspondant à une absence quasi-totale de liquide sur lesdites particules solides. Les gaz craqués sortant de l1échangeur de trempe indirecte sont à une température comprise en général entre 350 et 600*C, limitant les réactions secondaires, et suffisamment haute cependant pour que ces gaz ne contiennent sensiblement pas de liquide. Il se peut toutefois, lorsque la charge à vapocraquer est lourde (gazole ou naphta lourd par exemple) que ces gaz contiennent un brouillard d'hydrocarbures très lourds, ou des goudrons, ou du coke "liquide".This intermediate tank makes it possible to store the solid particles leaving the cyclone, while an injection of solid particles into the installation is carried out from the first tank mentioned. According to another characteristic of the invention, the installation comprises a pipe connected as a bypass to the indirect quenching exchanger, between the outlet of the cracking furnace and the aforementioned cyclone, in order to take a small fraction of the outgoing gaseous effluent flow from the oven and to dry the solid particles by direct contact with this fraction removed, at a temperature corresponding to an almost total absence of liquid on said solid particles. The cracked gases leaving the indirect quench heat exchanger 1 are at a temperature generally between 350 and 600 ° C, limiting the side reactions, and yet high enough so that these gases do not contain substantially no liquid. It is however possible, when the charge to be steam cracked is heavy (diesel or heavy naphtha for example) that these gases contain a mist of very heavy hydrocarbons, or tars, or "liquid" coke.
L'invention permet de vaporiser ou de carboniser l'essentiel de ces traces liquides, sans recourir à des moyens connus consistant en un brûlage de ces liquides en présence d'oxygène, très délicat à réaliser du point de vue de la sécurité.The invention makes it possible to vaporize or carbonize most of these liquid traces, without using known means consisting of burning these liquids in the presence of oxygen, very delicate to carry out from the point of view of safety.
L'augmentation de température des particules solides sortant de l'échangeur de trempe indirecte est d'environ 30 à 250βC pour vaporiser ou carboniser, selon les cas, les traces de liquide.The increase in temperature of the solid particles leaving the indirect quenching exchanger is approximately 30 to 250 β C to vaporize or carbonize, as the case may be, traces of liquid.
L'installation de vapocraquage peut donc être utilisée avec des charges relativement lourdes susceptibles de conduire à des traces d'hydrocarbures condensés en sortie de l'échangeur de trempe indirecte, sans qu'il soit nécessaire d'imposer une température permanente trop élevée en sortie de cet échangeur de trempe indirecte, qui conduirait à des pertes d'énergie pendant le fonctionnement de l'installation. La dérivation peut en effet n'être mise en service que lors des périodes d'injection de particules.The steam cracking installation can therefore be used with relatively heavy loads liable to lead to traces of condensed hydrocarbons leaving the indirect quench exchanger, without it being necessary to impose a too high permanent temperature at the outlet. of this indirect quenching exchanger, which would lead to energy losses during the operation of the installation. The bypass can indeed only be put into service during particle injection periods.
Ce mode simple de séchage des particules solides évite par ailleurs leur collage lors de la séparation dans le cyclone ou du recyclage par l'intermédiaire des réservoirs précités.This simple method of drying the solid particles also prevents them from sticking during separation in the cyclone or recycling via the aforementioned tanks.
Dans une première forme de réalisation deIn a first embodiment of
1'invention, cette canalisation de dérivation est raccordée au conduit reliant l'échangeur de trempe indirecte au cyclone, en amont du cyclone (éventuellement juste en sortie de l'échangeur de trempe). La fraction du débit d'effluents prélevée en sortie du four est alors mélangée au débit d"effluents sortant de 1*échangeur de trempe indirecte, avant séparation des particules solides dans le cyclone. En variante, la canalisation de dérivation est raccordée au conduit de sortie de solides du cyclone et mène à un cyclone secondaire à température élevée, suffisante pour assurer la vaporisation et/ou la carbonisation des traces de liquide présentes sur les particules solides. Dans ce cas, les particules solides sortant du cyclone principal sont entraînées par un petit débit d'effluents gazeux, ce qui évite leur collage avant leur surchauffe par contact avec la fraction précitée prélevée du débit d'effluents gazeux en sortie du four. Le cyclone secondaire peut avoir des dimensions beaucoup plus faibles que celle du cyclone principal et fonctionne à température plus élevée, ce qui permet soit une vaporisation, soit une carbonisation des traces de liquide présentes sur les particules solides.1'invention, this bypass pipe is connected to the conduit connecting the indirect quenching exchanger to the cyclone, upstream of the cyclone (possibly just at the outlet of the quenching exchanger). The fraction of the effluent flow rate taken off the furnace is then mixed with the effluent flow rate leaving the indirect quenching exchanger, before separation of the solid particles in the cyclone. As a variant, the bypass pipe is connected to the solids exit from the cyclone and lead to a secondary cyclone at high temperature, sufficient to ensure the vaporization and / or carbonization of the traces of liquid present on the solid particles. In this case, the solid particles leaving the main cyclone are entrained by a small flow of gaseous effluents, which avoids their sticking before their overheating by contact with the abovementioned fraction taken from the flow of gaseous effluents leaving the oven. The secondary cyclone can have much smaller dimensions than that of the main cyclone and operates at a higher temperature, which allows either vaporization or carbonization of the traces of liquid present on the solid particles.
Ces deux variantes peuvent être coinbinées. Avantageusement, l'installation comprend également des moyens de pré-trempe de ladite fraction prélevée du débit d'effluents gazeux, ces moyens étant prévus au voisinage de l'extrémité amont de ladite canalisation de dérivation et comprenant par exemple des moyens d'injection de vapeur de dilution.These two variants can be coinbiné. Advantageously, the installation also comprises means for pre-quenching said fraction taken from the flow of gaseous effluents, these means being provided in the vicinity of the upstream end of said bypass pipe and comprising for example means for injecting dilution vapor.
La prétrempe peut consister en un refroidissement (par contact direct avec un gaz) compris entre 70 et 200*C des effluents sortant du four et prélevés dans la dérivation.The presoaked may consist of a cooling (by direct contact with a gas) of between 70 and 200 ° C leaving the furnace effluent and collected in the bypass.
On évite ainsi un surcraquage de la fraction prélevée d'effluents gazeux, dans la canalisation de dérivation. Selon encore une autre caractéristique de l'invention, relative à une installation comprenant plusieurs fours de craquage et leurs échangeurs de trempe indirecte, agencés en parallèle et reliés à des moyens de trempe directe des effluents gazeux, les sorties des échangeurs de trempe indirecte des fours sont raccordées à des moyens communs de séparation et de recyclage de particules solides, comprenant les cyclones et réservoirs précités.This avoids overcracking of the fraction taken off of gaseous effluents in the bypass pipe. According to yet another characteristic of the invention, relating to an installation comprising several cracking ovens and their indirect quenching exchangers, arranged in parallel and connected to means for direct quenching of the gaseous effluents, the outputs of the indirect quenching exchangers of the ovens are connected to common means for separating and recycling solid particles, including the aforementioned cyclones and reservoirs.
On réduit ainsi le coût d'une installation de vapocraquage selon l'invention. Avantageusement, les sorties des échangeurs de trempe indirecte sont reliées aux moyens communs de séparation et de recyclage de particules solides par des canalisations de dérivation qui sont munies de vannes d'isolement et qui sont branchées sur les canalisations reliant ces sorties aux moyens de trempe directe.This reduces the cost of a steam cracking installation according to the invention. Advantageously, the outputs of the indirect quench exchangers are connected to the common means of separation and recycling of solid particles by bypass pipes which are provided with isolation valves and which are connected to the pipes connecting these outlets to the direct quenching means. .
De préférence, les vannes d'isolement de ces canalisations de dérivation restent en permanence en position d'ouverture. Elles ne remplissent alors pas de fonction d'étanchéité et sont par exemple des volets simples non étanches.Preferably, the isolation valves of these bypass pipes remain permanently in the open position. They then do not fulfill a sealing function and are, for example, simple, non-waterproof shutters.
Une installation de ce type présente un certain nombre d'avantages importants : les décokages des différents fours de vapocraquage peuvent être réalisés séquentiellement, sans qu'il soit nécessaire d'utiliser des vannes d'isolement de grand diamètre conçues spécialement pour le passage de gaz chargé en particules érosives, qui sont extrêmement coûteuses, - les canalisations de dérivation par lesquelles passent des effluents gazeux chargés de particules solides ne sont jamais reliées à l'atmosphère, ni à une source de gaz contenant de l'oxygène, ce qui est un facteur important de sécurité; - la fiabilité générale de 1'installation est largement augmentée du fait que les vannes d'isolement précitées restent en position d'ouverture et ne sont en principe pas manoeuvrées pendant le fonctionnement normal de l'installation, contrairement aux procédés connus où l'on isole totalement le circuit en décokage;An installation of this type has a number of important advantages: the decoking of the various steam cracking ovens can be carried out sequentially, without the need to use large-diameter isolation valves specially designed for the passage of gas. loaded with erosive particles, which are extremely expensive, - bypass pipes through which gaseous effluents pass loaded with solid particles are never connected to the atmosphere, nor to a source of oxygen-containing gas, which is a important safety factor; - The general reliability of the installation is greatly increased by the fact that the abovementioned isolation valves remain in the open position and are in principle not operated during normal operation of the installation, unlike the known methods in which completely isolates the circuit during decoking;
- l'efficacité de la séparation des particules solides des effluents gazeux peut être extrêmement élevée à coût réduit, ce qui évite tout risque de pollution des moyens de trempe directe ou de l'environnement. L'invention sera mieux comprise et d'autres caractéristiques, détails et avantages de celle-ci apparaîtront plus clairement à la lecture de la description qui suit, faite à titre d'exemple en référence aux dessins annexés, dans lesquels : la figure 1 représente sché atiquement une partie des moyens de recyclage de particules solides selon l'invention, dans un premier état; la figure 2 représente un autre état de ces moyens; la figure 3 représente une installation de vapocraquage selon l'invention, permettant le séchage des particules solides; la figure 4 représente une variante de réalisation de cette installation; la figure 5 représente une installation de vapocraquage selon l'invention, du type comprenant plusieurs fours de vapocraquage agencés en patallèle.- The efficiency of the separation of solid particles from gaseous effluents can be extremely high at reduced cost, which avoids any risk of pollution of the direct quenching means or of the environment. The invention will be better understood and other characteristics, details and advantages thereof will appear more clearly on reading the description which follows, given by way of example with reference to the appended drawings, in which: FIG. 1 is a diagrammatic representation of part of the means for recycling solid particles according to the invention, in a first state; FIG. 2 represents another state of these means; FIG. 3 represents a steam cracking installation according to the invention, allowing the drying of solid particles; Figure 4 shows an alternative embodiment of this installation; FIG. 5 represents a steam cracking installation according to the invention, of the type comprising several steam cracking ovens arranged in patallel.
On se réfère d'abord aux figures 1 et 2, qui représentent à titre d'exemple une partie des moyens de recyclage de particules solides selon l'invention. Ces moyens comprennent un cyclone 10, qui est alimenté par un échangeur de chaleur réalisant une trempe indirecte des effluents gazeux sortant d'un four de vapocraquage d'hydrocarbures, et qui comprend, en partie supérieure, une sortie 12 d'effluents gazeux menant à des moyens de trempe directe et, en partie inférieure, une sortie 14 de particules solides séparées des effluents gazeux dans le cyclone 10. La sortie 14 est reliée par une vanne d'isolement 16 à l'entrée supérieure 18 d'un réservoir 20 comprenant des moyens 22, tels qu'un tamis, de séparation et de retenue des particules solides grossières, ainsi qu'un orifice 24 d'évacuation de ces particules.Reference is first made to FIGS. 1 and 2, which show, by way of example, part of the means for recycling solid particles according to the invention. These means comprise a cyclone 10, which is supplied by a heat exchanger carrying out an indirect quenching of the gaseous effluents leaving a hydrocarbon steam cracking furnace, and which comprises, in the upper part, an outlet 12 for gaseous effluents leading to direct quenching means and, in the lower part, an outlet 14 for solid particles separated from the gaseous effluents in the cyclone 10. The outlet 14 is connected by an isolation valve 16 to the upper inlet 18 of a tank 20 comprising means 22, such as a screen, for separating and retaining coarse solid particles, as well as an orifice 24 for discharging these particles.
La partie inférieure du réservoir 20, dans laquelle se rassemblent les particules solides fines, est reliée par un organe tournant motorisé 26, du type sas rotatif, vis ou écluse rotative, et par une vanne d'isolement 28 à l'entrée d'un autre réservoir 30 dont la sortie, en partie inférieure, comporte un organe tournant motorisé 32 et une vanne d'isolement 34 qui sont identiques à l'organe 26 et à la vanne 28 précités. La sortie du réservoir 30 est reliée, en aval de la vanne 34, à un conduit 36 de recyclage des particules solides dans l'installation de vapocraquage. Une source 38 de gaz sous pression alimente le conduit 36 par un débit de gaz à vitesse moyenne ou relativement faible.The lower part of the tank 20, in which the fine solid particles collect, is connected by a motorized rotating member 26, of the rotary airlock type, screw or rotary lock, and by a valve. isolation 28 at the inlet of another tank 30, the outlet of which, in the lower part, comprises a motorized rotating member 32 and an isolation valve 34 which are identical to the member 26 and to the aforementioned valve 28. The outlet of the reservoir 30 is connected, downstream of the valve 34, to a conduit 36 for recycling solid particles in the steam cracking installation. A source 38 of pressurized gas supplies the conduit 36 with a gas flow at medium or relatively low speed.
Une vanne à trois voies 40 permet de relier le réservoir 30 soit à la source de gaz sous pression 38, soit au conduit 12 de sortie de gaz du cyclone. Des vannes d'arrêt 42 sont prévues dans les conduits reliant la vanne 40 à la source de gaz sous pression 38 et au conduit 12 respectivement.A three-way valve 40 makes it possible to connect the reservoir 30 either to the source of pressurized gas 38, or to the conduit 12 for the gas outlet from the cyclone. Stop valves 42 are provided in the conduits connecting the valve 40 to the source of pressurized gas 38 and to the conduit 12 respectively.
Un réservoir indépendant 44 rempli de particules solides de granulométrie moyenne déterminée, permet, par l'intermédiaire d'un organe tournant motorisé 46 et d'une vanne d'isolement 48, d'injecter un appoint de particules solides dans le conduit de recyclage 36. Pour cela, la partie supérieure du réservoir 44 est reliée à la sortie de ce réservoir par un conduit 50 d'équilibrage de pression. L'organe tournant 46 permet de régulariser le débit de particules d'appoint.An independent reservoir 44 filled with solid particles of determined average particle size, allows, by means of a motorized rotating member 46 and an isolation valve 48, to inject an addition of solid particles into the recycling conduit 36 For this, the upper part of the reservoir 44 is connected to the outlet of this reservoir by a pressure equalization conduit 50. The rotating member 46 makes it possible to regulate the flow of make-up particles.
Le réservoir 20 peut être muni, en partie inférieure, d'un conduit de purge 52, permettant de soutirer une certaine quantité de particules solides. Un conduit 53 d'entrée de gaz de barrage débouche en partie supérieure du réservoir 20. Le gaz de barrage est exempt d'aromatique lourd et peut être de la vapeur d'eau. Il permet d'éviter le cokage du réservoir 20 et du tamis 22.The reservoir 20 may be provided, in the lower part, with a purge duct 52, making it possible to withdraw a certain quantity of solid particles. A barrier gas inlet pipe 53 opens into the upper part of the reservoir 20. The barrier gas is free of heavy aromatics and may be water vapor. It avoids coking of the tank 20 and the sieve 22.
Ces moyens de recyclage fonctionnent de la façon suivante : on suppose tout d'abord que la vanne amont 16 du réservoir 20 est ouverte, que l'organe de sortie 26 de ce réservoir ne tourne pas, et que la vanne d'isolement 28 est fermée. Dans ces conditions, les particules solides qui sortent du cyclone 10 sont collectées dans le réservoir 20, après avoir été filtrées par le tamis 22 qui retient les particules de plus grande taille. Le gaz de barrage amené par le conduit 53 s'oppose à toute entrée d'aromatiques lourds dans ce réservoir. Pendant cette phase, le réservoir inférieurThese recycling methods work as follows: it is first assumed that the upstream valve 16 of the tank 20 is open, that the outlet member 26 of this tank does not rotate, and that the isolation valve 28 is closed. Under these conditions, the solid particles leaving the cyclone 10 are collected in the tank 20, after having been filtered by the screen 22 which retains the larger particles. The barrier gas brought in through line 53 opposes any entry of heavy aromatics into this tank. During this phase, the lower tank
30, qui a été précédemment rempli de particules solides provenant du réservoir supérieur 20, est progressivement vidé de ses particules solides, qui sont injectées dans le conduit 36. Pour cela, la vanne d'isolement aval 34 de ce réservoir est ouverte, l'organe tournant 32 est entraîné en rotation et le volume interne du réservoir 30 est relié à la source de gaz sous pression 38 par l'intermédiaire de la vanne 40, la vanne d'arrêt 42 correspondante étant ouverte. Le gaz délivré par la source 38 est à une pression qui est au moins égale ou légèrement supérieure à la pression au point d'injection des particules solides dans l'installation de vapocraquage et qui est supérieure à la pression dans le conduit de sortie 12 du cyclone 10. La pression interne du réservoir 30 est donc augmentée par rapport à celle du réservoir supérieur 20 et se trouve en équilibre avec la pression dans le conduit de recyclage 36. La source 38 délivre dans ce conduit un débit de gaz à vitesse relativement faible comprise entre 5 et 25 m/s, par exemple entre 10 et 20 m/s, qui permet de transporter les particules solides en suspension diluée jusqu'en au moins un point d'injection dans l'installation de vapocraquage. La faible vitesse du courant gazeux porteur évite une érosion importante du conduit de recyclage. Lorsque le réservoir 30 est vide ou sensiblement vide, on cesse d'entraîner l'organe tournant30, which has previously been filled with solid particles from the upper reservoir 20, is gradually emptied of its solid particles, which are injected into the conduit 36. For this, the downstream isolation valve 34 of this reservoir is open, the rotating member 32 is rotated and the internal volume of the reservoir 30 is connected to the source of pressurized gas 38 via the valve 40, the corresponding stop valve 42 being open. The gas delivered by the source 38 is at a pressure which is at least equal to or slightly greater than the pressure at the point of injection of the solid particles in the steam cracking installation and which is greater than the pressure in the outlet conduit 12 of the cyclone 10. The internal pressure of the reservoir 30 is therefore increased relative to that of the upper reservoir 20 and is in equilibrium with the pressure in the recycling conduit 36. The source 38 delivers in this conduit a gas flow at relatively low speed between 5 and 25 m / s, for example between 10 and 20 m / s, which makes it possible to transport the solid particles in dilute suspension up to at least one injection point in the steam cracking installation. The low speed of the carrier gas stream prevents significant erosion of the recycling conduit. When the reservoir 30 is empty or substantially empty, it ceases to drive the rotating member
32, on ferme la vanne d'isolement 34 et on relie le réservoir 30 au conduit 12 de sortie du cyclone par l'intermédiaire de la vanne 40. Le réservoir 30 se trouve alors à la même pression que le réservoir supérieur 20, et il suffit d'ouvrir la vanne d'isolement 28 et d'entraîner l'organe tournant 26 pour que les particules solides contenues dans le réservoir 20 puissent être transférées dans le réservoir 30.32, the isolation valve 34 is closed and the reservoir 30 is connected to the cyclone outlet conduit 12 via the valve 40. The reservoir 30 is then at the same pressure as the upper reservoir 20, and it it suffices to open the isolation valve 28 and to drive the rotating member 26 so that the solid particles contained in the reservoir 20 can be transferred to the reservoir 30.
Ensuite, on cesse d'entraîner l'organe tournant 26, on ferme à nouveau la vanne d'isolement 28, on relie le réservoir 30 à la source de gaz sous pression 38, on entraîne l'organe tournant 32 et on ouvre la vanne 34 pour injecter à nouveau les particules solides dans l'installation de vapocraquage.Then, we stop driving the rotating member 26, we close the isolation valve 28 again, we connect the reservoir 30 to the source of pressurized gas 38, we drive the rotating member 32 and we open the valve 34 to re-inject the solid particles into the steam cracking installation.
En variante, pour transférer les particules, du réservoir 20 vers le réservoir 30, on pourrait égaliser les pressions entre ces deux réservoirs, non pas à la pression du cyclone 10, mais à la pression de la source de gaz 38, après avoir isolé le réservoir 20, et l'avoir relié à la source de gaz 38Alternatively, to transfer the particles from the reservoir 20 to the reservoir 30, the pressures between these two reservoirs could be equalized, not at the pressure of the cyclone 10, but at the pressure of the gas source 38, after having isolated the tank 20, and having connected it to the gas source 38
Chaque fois que nécessaire, le conduit 52 de purge permet de retirer un excédent de particules solides du réservoir 20, excédent constitué par un mélange de particules abrasives provenant du réservoir d'appoint et de particules de coke détachées des parois internes de l'installation de vapocraquage. La purge régulière du réservoir 20 permet d'éviter l'accumulation de particules solides de taille moyenne dans le débit de particules recyclées dans l'installation, et d'y diminuer la concentration en coke. Le réservoir d'appoint 44 permet d'ajouter la quantité voulue de particules solides ayant la granulométrie souhaitée dans le débit de particules recyclées. Les organes tournants motorisés qui sont interposés entre les sorties du réservoir et leurs vannes d'isolement aval, permettent de réguler le débit de particules solides sortant des réservoirs et d'éviter l'obstruction ou le blocage des vannes aval.Whenever necessary, the purge duct 52 makes it possible to remove an excess of solid particles from the tank 20, an excess consisting of a mixture of abrasive particles coming from the auxiliary tank and coke particles detached from the internal walls of the installation. steam cracking. Regular purging of the tank 20 makes it possible to avoid the accumulation of solid particles of medium size in the flow of recycled particles in the installation, and to reduce the coke concentration there. The make-up tank 44 makes it possible to add the desired quantity of solid particles having the desired particle size into the flow of recycled particles. The motorized rotating members which are interposed between the tank outlets and their downstream isolation valves, make it possible to regulate the flow of solid particles leaving the tanks and to avoid obstruction or blockage of the downstream valves.
En variante, et comme déjà décrit dans la demande internationale PCT/FR90/00272 des demandeurs, les réservoirs 20, 30 peuvent être agencés en parallèle et non en série. On se réfère maintenant à la figure 3, dans laquelle on a représenté schématiquement des moyens 'de séchage des particules solides utilisés pour le décokage de l'installation.As a variant, and as already described in the international application PCT / FR90 / 00272 of the applicants, the reservoirs 20, 30 can be arranged in parallel and not in series. Referring now to Figure 3, in which there is shown schematically means' of drying solid particles used for decoking the installation.
Cette installation comprend un four de vapocraquage, désigné généralement par la référence 54, dont la sortie d'effluents gazeux est reliée à lrentrée d'un échangeur 56 de trempe indirecte. La sortie de cet échangeur est reliée à l'entrée du cyclone 10, dont la sortie de gaz 12 est reliée aux moyens 58 de trempe directe des effluents gazeux, et dont la sortie de solides 14 est reliée aux moyens précités 20, 30 de stockage de particules solides.This plant comprises a steam cracking furnace, generally designated by the reference 54, the output gaseous effluent is connected to the input r of a heat exchanger 56 indirect quenching. The outlet of this exchanger is connected to the inlet of cyclone 10, whose gas outlet 12 is connected to the means 58 for direct quenching of the gaseous effluents, and whose solids outlet 14 is connected to the aforementioned means 20, 30 for storage solid particles.
Il peut arriver, notamment lorsque les charges à craquer sont relativement lourdes, que les effluents gazeux sortant de l'échangeur de trempe indirecte 56 contiennent des traces de liquide, telles que des hydrocarbures condensés. Ces traces de liquide se déposent sur les particules solides et risquent d'entraîner leur collage. Pour éviter cet inconvénient, l'invention prévoit une conduite de dérivation 60 dont l'extrémité amont est raccordée au conduit de sortie du four 54, en amont de l'échangeur de trempe 56, et dont l'extrémité aval est raccordée au conduit de sortie de l'échangeur de trempe 56 en amont de l'entrée du cyclone 10. Cette canalisation de dérivation 60 comprend un orifice calibré 62, permettant de prélever une faible fraction du débit d'effluents gazeux sortant du four 54.It can happen, especially when the charges to be cracked are relatively heavy, that the gaseous effluents leaving the indirect quench exchanger 56 contain traces of liquid, such as condensed hydrocarbons. These traces of liquid are deposited on the solid particles and risk causing them to stick. To avoid this drawback, the invention provides a bypass pipe 60, the upstream end of which is connected to the outlet pipe of the furnace 54, upstream of the quench exchanger 56, and the downstream end of which is connected to the pipe of outlet of the quench exchanger 56 upstream of the inlet of the cyclone 10. This bypass pipe 60 comprises a calibrated orifice 62, making it possible to take a small fraction of the flow of gaseous effluents leaving the oven 54.
Pour éviter tout surcraquage des effluents dans cette canalisation 60, qui peut avoir une longueur relativement importante, on prévoit, au voisinage de son extrémité amont, des moyens 64 de trempe indirecte, tels que des moyens d'injection d'une certaine quantité de vapeur de dilution. Ainsi, par exemple, les effluents gazeux qui sortent du four 54 à une température de 850°C environ sont refroidis jusqu'à 700'C environ dans la canalisation 60. Les gaz sortant de l'échangeur de trempe indirecte 56 sont par exemple à une température d'environ 400*C et sont réchauffés par contact direct avec les effluents gazeux amenés par la conduite de dérivation 60, à une température par exemple d'environ 480°C. Cette élévation de température est en principe suffisante pour vaporiser les traces de liquide présentes dans le débit d'effluents gazeux entrant dans le cyclone 10.To avoid any overcracking of the effluents in this pipe 60, which can have a relatively long length, provision is made, near its upstream end, means 64 for indirect quenching, such as means for injecting a certain quantity of steam dilution. Thus, for example, the gaseous effluents which leave the oven 54 at a temperature of approximately 850 ° C. are cooled to approximately 700 ° C. in the pipe 60. The gases leaving the indirect quench exchanger 56 are for example at a temperature of about 400 ° C and are heated by direct contact with the waste gas supplied by the bypass line 60 at a temperature for example of about 480 ° C. This rise in temperature is in principle sufficient to vaporize the traces of liquid present in the flow of gaseous effluents entering the cyclone 10.
Bien entendu, le prélèvement d'une faible fraction du débit d'effluents gazeux à la sortie du four 54 n'a d'intérêt que pendant les périodes de décokage du four 54 au moyen des particules solides érosives. En dehors de ces périodes, une vanne d'arrêt 66 prévue dans la canalisation de dérivation 60. permet d'éviter ce prélèvement. Les moyens 64 de pré-trempe sont également pourvus d'une vanne d'isolement 68.Of course, the removal of a small fraction of the flow of gaseous effluents at the outlet of the oven 54 is only of interest during the decoking periods of the oven 54 by means of the erosive solid particles. Outside these periods, a stop valve 66 provided in the bypass line 60. makes it possible to avoid this sampling. The pre-quenching means 64 are also provided with an isolation valve 68.
La figure 4 représente une variante de réalisation de ces moyens de séchage des particules solides. Dans cette variante, la canalisation de dérivation 60 est reliée à la sortie de solides 14 du cyclone 10 et mène à l'entrée d'un cyclone auxiliaire 70 ayant des dimensions nettement plus faibles que celles du cyclone précité 10. La sortie de gaz 72 du cyclone 70 est reliée à l'entrée des moyens 58 de trempe directe, par l'intermédiaire d'un éjecteur 74 ou moyen analogue. La sortie de solides du cyclone auxiliaire 70 mène aux réservoirs de stockage 20, 30 précités. Le fonctionnement de cette variante est le suivant.FIG. 4 represents an alternative embodiment of these means for drying solid particles. In this variant, the bypass pipe 60 is connected to the solids outlet 14 of the cyclone 10 and leads to the inlet of an auxiliary cyclone 70 having dimensions considerably smaller than those of the above-mentioned cyclone 10. The gas outlet 72 cyclone 70 is connected to the inlet of the direct quenching means 58, by means of an ejector 74 or similar means. The exit of solids from auxiliary cyclone 70 leads to storage tanks 20, 30 mentioned above. The operation of this variant is as follows.
Pendant les périodes de décokage du four 54, une faible fraction du débit d'effluents gazeux sortant du four 54 est prélevée par la canalisation de dérivation 60 et mélangée à un petit débit d'effluents gazeux sortant avec les particules solides du cyclone principal 10, pour être introduite dans le cyclone auxiliaire 70.During the decoking periods of the oven 54, a small fraction of the flow of gaseous effluents leaving the oven 54 is sampled by the bypass pipe 60 and mixed with a small flow of gaseous effluents leaving with the solid particles of the main cyclone 10, to be introduced into the auxiliary cyclone 70.
Même si le courant d1effluents gazeux sortant de l'échangeur de pré-trempe 56 contient des traces d'hydrocarbures condensés qui se déposent sur les particules solides, celles-ci sont entraînées dans le conduit de sortie 14 du cyclone 10 par le petit débit d'effluents gazeux et ne s'agglomèrent pas à l'intérieur du cyclone ou dans le conduit de sortie 14. Ces particules solides sont réchauffées par contact direct avec les effluents gazeux fournis par la canalisation de dérivation 60, avant d'être introduits dans le cyclone auxiliaire 70. La température qui règne dans ce cyclone est suffisamment élevée (par exemple entre 500 et 730*C environ) pour que les traces de liquide portées par les particules solides soient vaporisées et/ou carbonisées.Even if the stream of 1 gaseous effluents leaving the pre-quench exchanger 56 contains traces of condensed hydrocarbons which are deposited on the solid particles, these are entrained in the outlet pipe 14 of the cyclone 10 by the small flow of gaseous effluents and do not agglomerate inside the cyclone or in the outlet duct 14. These solid particles are heated by direct contact with the gaseous effluents supplied by the bypass pipe 60, before being introduced in the auxiliary cyclone 70. the temperature prevailing in the cyclone is sufficiently high (for example between 500 and 730 * C.) so that the traces of liquid carried by the solid particles are vaporized and / or carbonized.
Les gaz chauds sortant du cyclone 70 sont ramenés par l'intermédiaire de l'éjecteur 74 aux moyens 58 de trempe directe .The hot gases leaving the cyclone 70 are returned via the ejector 74 to the means 58 for direct quenching.
La vanne 66 des figures 3 et 4 doit être conçue pour fonctionner à température élevée et résister aux particules érosives qui la traversent. Ce type de vanne est coûteux. Elle peut être supprimée grâce au raccordement à la canalisation 60, en amont dès orifices calibrés 62, d'un conduit 75 d'amenée d'un gaz de barrage relativement froid qui s'oppose au prélèvement des effluents en sortie du four, en dehors dés périodes de décokage. Un tel gaz de barrage peut être prélevé en sortie 12 du cyclone 10 et recomprimé, par exemple par un éjecteur, comme représenté au dessin. Ce gaz de barrage peut également servir à la pré-trempe des effluents gazeux prélevés pendant les périodes de décokage. Dans ces conditions, les moyens 64, 68 peuvent être supprimés. Enfin, comme représenté sur la figure 4, les réalisations des figures 3 et 4 peuvent être combinées.The valve 66 of Figures 3 and 4 must be designed to operate at high temperature and resist the erosive particles which pass through it. This type of valve is expensive. It can be eliminated by connecting to the pipe 60, upstream from calibrated orifices 62, a conduit 75 for supplying a relatively cold barrier gas which prevents the removal of effluents from the oven, outside from decoking periods. Such a barrier gas can be taken from outlet 12 of cyclone 10 and recompressed, for example by an ejector, as shown in the drawing. This barrier gas can also be used for the pre-quenching of the gaseous effluents sampled during the decoking periods. Under these conditions, the means 64, 68 can be omitted. Finally, as shown in Figure 4, the embodiments of Figures 3 and 4 can be combined.
On se réfère maintenant à la figure 5, qui représente schématiquement une installation de vapocraquage selon l'invention, comprenant plusieurs fours de craquage agencés en parallèle.Referring now to Figure 5, which schematically shows a steam cracking installation according to the invention, comprising several cracking ovens arranged in parallel.
Ces fours de craquage, désignés par les références 54lf 542...54n, sont associés à des échangeurs de trempe indirecte 56lΛ 562,...., 56n respectivement, dont les sorties sont reliées par des canalisations 76 à des moyens 58 de trempe directe des effluents gazeux.These cracking ovens, designated by the references 54 lf 54 2 ... 54 n , are associated with indirect quench exchangers 56 lΛ 56 2 , ...., 56 n respectively, the outputs of which are connected by pipes 76 to means 58 for direct quenching of the gaseous effluents.
Cette installation est du type à décokage séquentiel des fours de craquage et comprend des conduits 36 d'injection de particules solides reliant les moyens de stockage 20, 30 précités aux points d'injection de particules dans les fours 54, chacun de ces conduits 36 comprenant une vanne d'arrêt 78 de faible dimension immédiatement en amont du point d'injection dans chaque four 54. Les sorties des échangeurs 56 de trempe indirecte sont par ailleurs reliées, par des canalisations de dérivation 80 comprenant des vannes d'isolement 82, à des moyens communs de séparation de particules solides comprenant au moins un cyclone 10 du type précité. La sortie de solides 14 de ce cyclone est reliée aux moyens de stockage 20, 30 précités, et la sortie de gaz 12 du cyclone est reliée, avec les conduits 76, à l'entrée des moyens 58 de trempe directe. Par ailleurs, les conduits 76 comprennent des vannes d'isolement 84, prévues en aval des branchements des canalisations de dérivation 80. Cette installation peut être utilisée de la façon suivante : 15 lorsque le décokage d'un four de craquage doit être réalisé, par exemple celui du four 54l la vanne d'isolement 84 de son conduit 76 est fermée tandis que la vanne 82 de la conduite de dérivation correspondante 80 est ouverte. L'injection de particules solides dans le four 54-L est réalisée par ouverture de la vanne d'arrêt 78 correspondante. Les vannes 84 des conduits 76 des autres fours sont ouvertes, et les vannes 82 des canalisations de dérivation 80 de ces autres fours sont fermées, de telle sorte que le débit d'effluents gazeux et de particules solides sortant du four 54x passe par le cyclone 10, alors que les débits d*effluents gazeux sortant des autres fours gagnent directement les moyens 58 de trempe directe. Lorsque le décokage du four 541 a été réalisé, on ferme la vanne 78 correspondante, on ouvre la vanne 84 et on ferme la vanne 82 associées à ce four, puis on répète, pour le four 542, les opérations déjà décrites pour le décokage du four 54x. -This installation is of the sequential decoking type of cracking ovens and comprises conduits 36 for injecting solid particles connecting the aforementioned storage means 20, 30 to the points of injection of particles into the ovens 54, each of these conduits 36 comprising a small shut-off valve 78 immediately upstream from the point of injection into each furnace 54. The outputs of the indirect quenching exchangers 56 are moreover connected, by bypass pipes 80 comprising isolation valves 82, to common means for separating solid particles comprising at least one cyclone 10 of the aforementioned type. The solids outlet 14 of this cyclone is connected to the aforementioned storage means 20, 30, and the gas outlet 12 of the cyclone is connected, with the conduits 76, to the inlet of the direct quenching means 58. In addition, the conduits 76 include isolation valves 84, provided downstream of the branching of the branch pipes 80. This installation can be used in the following manner: When the decoking of a cracking oven has to be carried out, for example that of the oven 54 l the isolation valve 84 of its conduit 76 is closed while the valve 82 of the corresponding bypass pipe 80 is open. The injection of solid particles into the oven 54-L is carried out by opening the corresponding stop valve 78. The valves 84 of the conduits 76 of the other ovens are open, and the valves 82 of the bypass pipes 80 of these other ovens are closed, so that the flow of gaseous effluents and solid particles leaving the oven 54 x passes through the cyclone 10, while the flow rates of gaseous effluents leaving the other ovens directly reach the means 58 for direct quenching. When the decoking of the oven 54 1 has been carried out, the corresponding valve 78 is closed, the valve 84 is opened and the valve 82 associated with this oven is closed, then the operations already described for the oven 54 2 are repeated. decoking the oven 54 x . -
Il en résulte que les vannes 82 des canalisations de dérivation 80 sont manoeuvrées de façon relativement fréquentes. En outre, ces vannes sont extrêmement coûteuses, puisqu'elles sont conçues pour être traversées par des débits importants de gaz chargé de particules érosives. II est donc préférable de faire fonctionner cette installation de la façon suivante : toutes les vannes 82 sont laissées ouvertes en permanence. Lorsque 1'on souhaite réaliser le décokage d'un four, par exemple du four 54 l r on ferme la vanne 84 associée et on réalise une injection de particules solides érosives dans ce four, par ouverture de' la vanne 78 correspondante. Les vannes 84 associées aux autres fours sont ouvertes, de même que les vannes 82 des canalisations de dérivation correspondantes. Il en résulte que le débit total d'effluents gazeux, véhiculant des particules solides érosives, sortant du four 56-^, gagne le cyclone 10, ainsi qu'une fraction des débits d'effluents gazeux, non chargés de particules solides, qui sortent des autres fours 562, .. • .56n. Les autres fractions des débits d'effluents gazeux sortant de ces fours gagnent directement les moyens 58 de trempe directe. La séparation des particules solides dans le cyclone 10 est excellente et peu affectée par la dilution des effluents gazeux chargés en particules solides par les effluents gazeux non chargés en particules solides. II faut bien entendu que le cyclone soit dimensionné de façon à accepter ce débit supérieur d'effluents gazeux. Cependant, ce surdimensionnement est largement compensé par le fait que les vannes 82 restent en permanence en position ouverte. Il en résulte que l'on peut utiliser des vannes beaucoup moins coûteuses que dans le cas précédent, par exemple des moyens non étanches tels que des volets, pour régler les débits d'effluents gazeux qui passent par les canalisations 80, pendant les périodes de décokage et en dehors de ces périodes.As a result, the valves 82 of the bypass lines 80 are operated relatively frequently. In addition, these valves are extremely expensive, since they are designed to be traversed by large flows of gas charged with erosive particles. It is therefore preferable to operate this installation as follows: all the valves 82 are left open at all times. When one wishes to decoke an oven, for example from oven 54 lr, the associated valve 84 is closed and an injection of erosive solid particles is carried out in this oven, by opening the corresponding valve 78. The valves 84 associated with the other ovens are open, as are the valves 82 of the corresponding bypass pipes. It follows that the total flow of gaseous effluents, carrying erosive solid particles, leaving the oven 56- ^, wins cyclone 10, as well as a fraction of the flow rates of gaseous effluents, not loaded with solid particles, which leave other ovens 56 2 , .. • .56 n . The other fractions of the gaseous effluent flows leaving these furnaces directly gain the means 58 for direct quenching. The separation of the solid particles in cyclone 10 is excellent and little affected by the dilution of the gaseous effluents loaded with solid particles by the gaseous effluents not loaded with solid particles. It is of course necessary for the cyclone to be dimensioned so as to accept this higher flow rate of gaseous effluents. However, this oversizing is largely compensated by the fact that the valves 82 remain permanently in the open position. As a result, it is possible to use much less expensive valves than in the previous case, for example non-watertight means such as shutters, to regulate the flow rates of gaseous effluents which pass through the pipes 80, during the periods of decoking and outside these periods.
On remarquera également que, dans ce cas, toutes les canalisations de dérivation 80 sont parcourues en permanence par un courant d'effluents gazeux. Elles restent donc à une température constante, ce qui évite des refroidissements, des points froids, des collages de particules, etc. Par ailleurs, ces canalisations de dérivation 80 ne sont jamais reliées à l'atmosphère ou à une source de gaz contenant de l'oxygène, ce qui constitue un facteur de sécurité important. Pour que le cyclone 10 puisse accepter un débit important de gaz et le renvoyer ensuite vers les moyens 58 de trempe indirecte, il est avantageux de maintenir dans le cyclone 10 une dépression par rapport à la pression des effluents gazeux à la sortie des échangeurs de trempe indirecte 56. Pour cela, on peut utiliser un éjecteur 86, comme représenté schématiquement en figure 5 ou des moyens de mise en communication du cyclone avec un réseau de plus basse pression, ou tout autre moyen analogue approprié.It will also be noted that, in this case, all the branch pipes 80 are continuously traversed by a stream of gaseous effluents. They therefore remain at a constant temperature, which avoids cooling, cold spots, particle bonding, etc. Furthermore, these bypass lines 80 are never connected to the atmosphere or to a source of oxygen-containing gas, which constitutes an important safety factor. So that the cyclone 10 can accept a large flow of gas and then send it back to the indirect quenching means 58, it is advantageous to maintain a vacuum in the cyclone 10 relative to the pressure of the gaseous effluents at the outlet of the quench exchangers indirect 56. For this, an ejector 86 can be used, as shown diagrammatically in Figure 5 or means for communicating the cyclone with a lower pressure network, or any other similar suitable means.
L'invention s'applique également au décokage séquentiel de différentes passes d'un même four débouchant dans des échangeurs de trempe indirecte dont les sorties sont raccordées par des dérivations à des moyens communs de séparation et de recyclage des particules solides. The invention also applies to the sequential decoking of different passes of the same oven opening into indirect quench exchangers, the outlets of which are connected by branches to common means of separation and recycling of solid particles.

Claims

18 REVENDICATIONS 18 CLAIMS
1. Installation de vapocraquage d'hydrocarbures, comprenant au moins un four (54) de craquage des hydrocarbures, un échangeur (56) de trempe1. Installation for steam cracking of hydrocarbons, comprising at least one hydrocarbon cracking oven (54), a quenching exchanger (56)
5 indirecte des effluents sortant du four, et des moyens5 indirect effluents leaving the furnace, and means
(58) de trempe directe des effluents ainsi que des moyens(58) direct quenching of effluents and of the means
(36, 38) d'injection dans le four d'un faible débit de fines particules solides et des moyens, tels qu'un cyclone (10) , de séparation des particules solides et des(36, 38) injection into the furnace of a low flow rate of fine solid particles and means, such as a cyclone (10), of separation of the solid particles and
10 effluents gazeux de vapocraquage, qui sont placés entre l'échangeur (56) de trempe indirecte et les moyens (58) de trempe directe, caractérisée en ce qu'elle comprend un résevoir (30) de stockage des particules solides, dont l'entrée est raccordée à la sortie (14) des solides du10 gaseous steam cracking effluents, which are placed between the indirect quenching exchanger (56) and the direct quenching means (58), characterized in that it comprises a tank (30) for storing solid particles, including the inlet is connected to the outlet (14) of the solids of the
15 cyclone (10) et dont la sortie est raccordée à un conduit15 cyclone (10) and the outlet of which is connected to a conduit
(36) d'injection des particules dans l'installation, des moyens (28, 34) d'isolement de ce réservoir (30) tels que des vannes, et une source (38) de gaz sous pression, reliée au conduit (36) d'injection des particules, et au(36) for injecting particles into the installation, means (28, 34) for isolating this reservoir (30) such as valves, and a source (38) of pressurized gas, connected to the conduit (36 ) particle injection, and
20 réservoir (30) par des moyens (40) tels qu'une vanne pour augmenter la pression interne de ce réservoir à une valeur au moins égale à celle du point d'injection des particules dans le four (54) .20 reservoir (30) by means (40) such as a valve for increasing the internal pressure of this reservoir to a value at least equal to that of the point of injection of the particles into the furnace (54).
2. Installation selon la revendication 1,2. Installation according to claim 1,
25 caractérisée en ce qu'elle comprend un réservoir intermédiaire (20) monté entre la sortie du cyclone (10) et l'entrée du premier réservoir cité (30), et des moyens (16, 28), tels que des vannes, d'isolement de ce réservoir.25 characterized in that it comprises an intermediate tank (20) mounted between the outlet of the cyclone (10) and the inlet of the first tank mentioned (30), and means (16, 28), such as valves, d isolation of this tank.
30 3. Installation selon la revendication 2, caractérisée en ce que le réservoir intermédiaire (20) comprend des moyens (22) de retenue des grosses particules solides.30 3. Installation according to claim 2, characterized in that the intermediate tank (20) comprises means (22) for retaining large solid particles.
4. Installation selon la revendication 3,4. Installation according to claim 3,
35 caractérisée en ce que le réservoir intermédiaire (20) comprend à sa partie supérieure des moyens (53) d'introduction d'un gaz de barrage exempt d'aromatiques lourds, tel par exemple que de la vapeur d'eau.35 characterized in that the intermediate tank (20) comprises at its upper part means (53) introduction of a barrier gas free of heavy aromatics, such as for example steam.
5. Installation selon l'une des revendications précédentes, caractérisée en ce qu'elle comprend une canalisation (60) branchée en dérivation sur l'échangeur de trempe indirecte (56) , entre la sortie du fctor rie craquage et le cyclone (10) précité, pour prélever une faible fraction du débit d'effluents sortant, du four et sécher les particules solides par contact direct avec cette fraction prélevée, à une température correspondant à une absence quasi-totale de liquide sur les particules solides. • ^-#5. Installation according to one of the preceding claims, characterized in that it comprises a pipe (60) connected in bypass to the indirect quenching exchanger (56), between the outlet of the cracked fctor rie and the cyclone (10) mentioned above, to take a small fraction of the flow of effluent leaving the oven and dry the solid particles by direct contact with this sampled fraction, at a temperature corresponding to an almost total absence of liquid on the solid particles. • ^ - #
6. Installation selon la revendication 5, caractérisée en ce que la canalisation ,de dérivation (60) est raccordée au conduit reliant l'édi-angeur de trempe indirecte (56) au cyclone (10) .6. Installation according to claim 5, characterized in that the bypass pipe (60) is connected to the conduit connecting the indirect quench edi-anger (56) to the cyclone (10).
7. Installation selon la revendication 5, caractérisée en ce que la canalisation de dérivation (60) est raccordée au conduit (14) de sortie de solides du cyclone (10) et mène à un cyclone secondaire (70) à température élevée suffisante pour assurer la vaporisation et/ou la carbonisation des traces de liquide présentes sur les particules solides.7. Installation according to claim 5, characterized in that the bypass pipe (60) is connected to the conduit (14) for leaving the cyclone solids (10) and leads to a secondary cyclone (70) at a high temperature sufficient to ensure the vaporization and / or carbonization of the traces of liquid present on the solid particles.
8. Installation selon la revendication 7, caractérisée en ce que le conduit (72) de isortie de gaz du cyclone secondaire (70) est raccordé au conduit d'effluents (12) reliant le premier cyclone (10) aux moyens (58) de trempe directe, par l'intermédiaire d'un éjecteur (74) ou analogue. 8. Installation according to claim 7, characterized in that the conduit (72) of the gas outlet of the secondary cyclone (70) is connected to the effluent conduit (12) connecting the first cyclone (10) to the means (58) of direct quenching, via an ejector (74) or the like.
9. Installation selon l'une des revendications9. Installation according to one of claims
5 à 8, caractérisée en ce qu'elle comprend des moyens (64) de pré-trempe de ladite fraction prélevée du débit d1effluents, ces moyens étant prévus au voisinage de l'extrémité amont de ladite canalisation (6Q) et comprenant par exemple des moyens d'injecϋibn de vapeur de dilution. 5 to 8, characterized in that it comprises means (64) for pre-quenching said fraction taken from the flow of 1 effluent, these means being provided in the vicinity of the upstream end of said pipe (6Q) and comprising by example of the ways of injecting dilution vapor.
10. Installation selon la revendication 6 ou 7, caractérisée en ce qu'un conduit (75) d'amenée d'un gaz de barrage relativement froid est raccordé à la canalisation de dérivation (62) pour s'opposer au prélèvement d'effluents gazeux en sortie du four (54) par la canalisation de dérivation (62) en dehors des périodes de décokage, et/ou pour réaliser une pré-trempe de ces effluents pendant les périodes de décokage.10. Installation according to claim 6 or 7, characterized in that a conduit (75) for supplying a relatively cold barrier gas is connected to the bypass pipe (62) to oppose the removal of effluents gaseous at the outlet of the furnace (54) by the bypass pipe (62) outside of the decoking periods, and / or to carry out a pre-quenching of these effluents during the decoking periods.
11. Installation selon l'une des revendications précédentes, comprenant plusieurs fours et leurs échangeurs de trempe indirecte, agencés en parallèle et reliés à des moyens de trempe directe des effluents, caractérisée en ce que les sorties des échangeurs (56) de trempe indirecte des fours sont raccordés à des moyens communs (10, 20, 30) de séparation et de recyclage de particules solides, comprenant les cyclone(s) et réservoir(s) précités.11. Installation according to one of the preceding claims, comprising several ovens and their indirect quenching exchangers, arranged in parallel and connected to means for direct quenching of the effluents, characterized in that the outputs of the exchangers (56) of indirect quenching ovens are connected to common means (10, 20, 30) for separating and recycling solid particles, comprising the aforementioned cyclone (s) and tank (s).
12. Installation selon la revendication 11, caractérisée en ce que les sorties des échangeurs de trempe indirecte sont reliées aux moyens communs (10, 20, 30) de séparation et de recyclage de particules solides par des canalisations de dérivation (80) qui sont munies de vannes d'isolement (82) et qui sont branchées sur les canalisations (76) reliant ces sorties aux moyens (58) de trempe directe.12. Installation according to claim 11, characterized in that the outputs of the indirect quenching exchangers are connected to the common means (10, 20, 30) of separation and recycling of solid particles by bypass pipes (80) which are provided isolation valves (82) which are connected to the pipes (76) connecting these outputs to the means (58) of direct quenching.
13. Installation selon la revendication 12, caractérisée en ce que les vannes d'isolement (82) des canalisations de dérivation (80) restent en permanence en position d'ouverture. 13. Installation according to claim 12, characterized in that the isolation valves (82) of the bypass pipes (80) remain permanently in the open position.
14. Installation selon l'une des revendications 11 à 13, caractérisée en ce que la sortie de gaz (14) des moyens communs (10, 20, 30) de séparation et de recyclage de particules solides est reliée aux moyens de trempe directe (58) par des moyens tels qu'un éjecteur (86) ou un réseau basse pression, assurant une dépression dans le ou les cyclones par rapport à la pression des effluents en sortie des échangeurs (56) de trempe indirecte. 14. Installation according to one of claims 11 to 13, characterized in that the gas outlet (14) of the common means (10, 20, 30) for separation and recycling of solid particles is connected to the direct quenching means ( 58) by means such as an ejector (86) or a low pressure network, ensuring a vacuum in the cyclone (s) relative to the pressure of the effluents at the outlet of the indirect quenching exchangers (56).
EP90914930A 1989-10-06 1990-10-05 Hydrocarbon vapocracking installation with recycling of erosive solid particles Expired - Lifetime EP0447527B1 (en)

Applications Claiming Priority (3)

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FR8913070A FR2652817B1 (en) 1989-10-06 1989-10-06 PROCESS AND PLANT FOR VAPOCRACKING HYDROCARBONS, WITH RECYCLING OF EROSIVE SOLID PARTICLES.
FR8913070 1989-10-06
PCT/FR1990/000711 WO1991005031A1 (en) 1989-10-06 1990-10-05 Hydrocarbon vapocracking installation with recycling of erosive solid particles

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Also Published As

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FR2652817A1 (en) 1991-04-12
JP2898091B2 (en) 1999-05-31
JPH04502175A (en) 1992-04-16
DK0447527T3 (en) 1994-11-28
FR2652817B1 (en) 1993-11-26
ATE109195T1 (en) 1994-08-15
DE69011084D1 (en) 1994-09-01
ES2063376T3 (en) 1995-01-01
WO1991005031A1 (en) 1991-04-18
EP0447527B1 (en) 1994-07-27
US5183642A (en) 1993-02-02
DE69011084T2 (en) 1994-11-10

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