FR2615198A1 - METHOD AND DEVICE FOR HYDRAULIC DECOKING OF OIL COKE - Google Patents

Abstract

THE INVENTION CONCERNS A PROCESS FOR COKEFACTION OF OIL FEEDS SUCH AS HEAVY DISTILLATION OR RESIDUE PRODUCTS. IT CONCERNS MORE PARTICULARLY THE SUBSEQUENT STEP OF RECOVERING THE COKE AFTER IT IS DEPOSITED IN THE COKEFACTION REACTOR. THIS PROCESS CONSISTS OF LOWERING IN THE REACTOR 1, FROM A DRUM 3 ON WHICH IT IS WINDING, A FLEXIBLE TUBE 14 OF SUFFICIENT MECHANICAL STRENGTH THE LOWER END OF WHICH IS PROVIDED WITH MEANS FOR EJECTING WATER 17 TOWARDS THE LOW OR LATERAL AND WHOSE DESCENT IS CONTROLLED BY THE DRUM FEEDING. WATER UNDER PRESSURE IS PASSED THROUGH THE TUBE AND THROUGH THE EJECTION MEANS, IN THE DIRECTION OF THE COKE, AND THE COKE PIECES WHICH HAVE BEEN DISCHARGEED ARE DRAINED. THE DRUM MAY MOVE LATERAL SO AS TO POST ABOVE EACH OF THE ROTATING REACTORS WHEN TWO OR MORE REACTORS ARE IN USE.

Description

The invention relates to a process for coking hydrocarbon feeds,

  heavy distillation products or residues. It relates more particularly to the subsequent step of recovering the coke (decoking or decoking) after it has been deposited in the reactor. Coking is a well known process of the refining industry whose objective is to valorize the heavy cuts and especially the residues of distillation by making them undergo a decomposition

thermal.

  This usually takes place in large empty reactors where the decomposition takes place in distillates which are released from the reactor and

  in coked product which is deposited on the wall of the reactor.

  The charge is most often introduced through the bottom of the reactor and, in this case, the coke is deposited first in the bottom of the reactor; he then progressively fills higher and higher parts of the

  reactor until filling completely.

  At this moment we stop the injection of the charge and we send this

  charge in a second empty reactor.

  After this first stage of coke formation, there is a second

  step of recovering the coke produced.

  For this, after having purged the reactor of all the residual hydrocarbons and having cooled it, it is opened at its upper part and

  dig a hole using appropriate tools. These are usually

  supported by a scaffold or derrick which allows to dig inside the reactor from its top. The structure of the scaffolds (one per reactor, there are at least two reactors) is installed above the reactors themselves well above the ground to allow to inject the load and especially to recover the coke product that goes down by gravity of the reactor to be then transported to a storage area or the user. The object of the invention is a method and a device which makes it possible to avoid scaffolds above the reactors in order to lighten the whole structure, to save on investment and to make

  more convenient and economical coke extraction.

  The invention consists in lowering into the reactor, from a drum on which it is wound, a flexible tube of controlled rigidity whose free end (the one which is furthest from the axis of the drum when the tube is wound) is provided with means for ejecting water downwards and / or laterally and whose descent is controlled by the rotation of the drum. The other end of the tube is connected to a source of water under pressure: the water circulates in the

  tube to the ejection means and is projected to the coke bed.

  The pieces of coke that have come off are removed.

  A device as described above can be used for each reactor; preferably, in case of use of several reactors, for example 2, 3 or 4, only one device is used which is then mobile and can move laterally to come above each

reactors in turn.

  The invention uses flexible hoses, which have properties such that they safely allow to convey water under very high pressure. In addition these hoses are very resistant to tensile stresses and have a controlled rigidity. They allow to hang large masses at their end, which allows on the one hand to introduce tools (turbine) inside the reactor and also to avoid the ballant hose when water flow

high pressure are used.

  A pipe, stored on a drum, is thus suspended over a reactor and can be introduced gradually, by rotation of the

  drum, to the bottom of the reactor.

  The other end of the hose is connected to a pump that injects

water under high pressure.

  The operation is carried out in two phases - the first is to dig a hole in the axis of the reactor by introducing from above the lower end of the pipe, supporting the water ejection device. The water is ejected under pressure of 600 bar or more, from orifices arranged at the lower end of the device and facing downwards. Preferably, a device rotating about its axis such as a turbine is used, and the rotation of the turbine may result from the particular orientation of one or more ejection orifices (component at

  less partially tangential of one or more jets).

  When the device reaches the bottom of the reactor, the pipe and the ejection device are progressively raised by rewinding the pipe on the drum, and the water ejection device is modified in such a way that the ejection can be done from now on. laterally, with a tangential component, and no longer only downward. Preferably, we completely eliminate

the ejection down.

  in the second phase, the flexible tube and the ejection device are introduced again through the previously drilled passage. The water pressure in a lateral direction, with tangential component is then set to 100-600 bar or more, preferably -400 bar, which crushes the coke escaping through the base and pieces driven by the water . The fact of using a high pressure, for example 150-400 bar or more, makes it possible to obtain relatively large pieces of coke and to avoid too much dust.

  which would be difficult to separate later.

  According to another embodiment, the stop of the vertical water ejection, downwards, and the start of the lateral water ejection can be remotely controlled by any suitable device (using, for example, to remote control conductors incorporated in the hose), which avoids having to reassemble the hose. The drum that carries the hose can be mobile; it can move for example on rails and can thus be placed above the reactor to be decoked while the other reactors are

  in service or waiting for decoking.

  The flexible tubes that can be used in the invention will consist of superimposed layers that may comprise one or more sealed plastic sleeves, at least one internal pressure resistance frame, which may consist, for example, of at least one spiral winding with a short pitch. , and at least one tensile strength and torsion strength frame, for example, may be

  consisting of two crossed windings with a long pitch.

  They advantageously meet the following characteristics: Flexibility sufficient to be able to be wound on a drum of

  radius between 0.5 and 5 meters.

  Internal resistance to pressure of at least 100 bar, preferably

150 to 1000 bars.

  Elongation tensile strength of 10 to 10 daN, preferably

4 5

2.10 to 5.10 daN.

  Torque limit torque: 100 to 10000 m. daN, preferably 500 to

5000 m.daN.

2 2

  Stiffness at 20 C: 50 to 1000 daNm, preferably 100 to 500 daN.m2.

  Preferably one operates with a weight suspended from the tube (ejector + weighting mass) of 103 to 5.104 daN; this weight must obviously be chosen compatible with the resistance to

break.

2615 1 98

  Tubes of this type have been studied at the INSTITUT FRANCAIS DU PETROLE

  and are currently marketed by SOCIETE COFLEXIP, FRANCE.

  Figures 1 and 2 illustrate the implementation of the invention.

  Figure 1 is an overview of the installation.

  FIGS. 2a and 2b illustrate a particular embodiment of the water ejection device, respectively in lateral view and in

  BB section perpendicular to the axis, at the nozzle 22.

  The plant comprises two coking reactors 1 and 2. The reactor 1 is in the process of emptying the coke and the reactor 2 is in the process of depositing coke (coking). The inlet lines of the hydrocarbon feedstock and the withdrawal of the volatile products have not been represented for the sake of simplification. A winding drum or drum 3 is disposed above the reactors. Its rotation shaft is hollow and serves to supply water, brought under pressure by the pipe 4, via a rotating joint connecting the rotation shaft of the drum to the pipe. The axis of the drum is supported by two rigid flanges of which only one (5) is visible. The two flanges are supported on a chassis provided with wheels such as 7 and 8, allowing the assembly to be moved on the raceway 9. The assembly is carried by a scaffolding, or superstructure, comprising in particular the beams 10 to 13. A flexible tube of high mechanical strength 14 is wound on the drum. It is connected to the pipe 4 by a not shown coupling part which allows feeding whatever the position of the drum. The other end wears one. turbine capable of rotating on itself under the effect of jets of water coming out of nozzles such as 17 and 22 whose orientation comprises a tangential component. If the turbine is not heavy enough, a relatively heavy additional mass 16 increases the weight hanging from the tube. A pulley 18 makes it possible to guide the flexible tube and thus to keep it in the axis of the reactor, whatever

  the degree of unwinding of the tube on the drum.

  The turbine 15 has nozzles 17, 21 and 25 directed downwards and nozzles 22 to 24 directed laterally with a component tangential to the rotation of the turbine. This is independent of the mass 16 which normally is not rotated (the connection between the turbine 15 and the mass 16 is

  achieved through bearings).

  The operation may be for example as follows: the tool 15/16 being initially raised above the reactor 1, the upper ends 19 and lower 20 of the reactor filled with coke are opened and the assembly is lowered (14, 15, 16), by unwinding the pipe 14 on its drum. The pressurized water supplying the hose 14 is ejected from the downwardly directed lower ejectors, such as 17 and 21, and the descent of the pipe into the reactor continues as a well is drilled through a well. the jets in the coke bed. As soon as the tool has arrived at the bottom of the reactor, the coke is entrained by the lower opening 20 and falls under the reactor where it is evacuated.

  by known type of transport devices.

  The tool is then removed from the reactor, then the lower ejectors 17, 21 and 25 of the turbine are closed (except when the effect of driving the coke) is to be increased, and the lateral ejectors 22 to 24 are opened. The coke is detached from the walls of the reactor, and is

evacuated through the opening 20.

  When the operation is complete, remove the tool. of the reactor 1, the drum 3 and its supports are moved on the rails such as 9 and after opening of the reactor 2, the hose and the tool are lowered so as to carry out the decoking of the reactor 2. The reactor 1 is used to

a new coking operation.

  Instead of a single turbine 15 having downward and sideward openings, two separate turbines may also be employed, one with downward openings and the other with

lateral openings.

Claims (8)

  1.- Process for emptying coke from a coke-producing reactor, in which water under pressure is sprayed in the direction of the coke, first from top to bottom and then laterally towards the periphery, characterized in that use is made of water ejection means suspended from a flexible tube, supported at a point situated above the reactor, said tube being wound at rest on a drum whose rotation makes it possible to lower or raise the tube , said tube being provided with pressure resistance fittings   internal and tensile and torsional stresses.   2. A process according to claim 1, wherein the resistance to the internal pressure of the flexible tube is at least 100 bar and this tube has sufficient flexibility to allow its successive windings and unwindings on a drum with a radius of between 0, 5 and 5 meters.   3. A process according to claim 1 or 2, wherein the flexible tube has a stiffness at 20 C of 50 to 1000 daNm, a tensile strength at elongation of 104 to 10 daN and a torque 2 4   torsion limit of 10 to 10 m.daN.   4. Process according to any one of Claims 1 to 3, in   which the tube has an internal pressure resistance of 150 to 4 5   1000 bar, a breaking strength of 2.10 to 5.10 daN, a torsion limit torque of 500 to 5000 m.daN and a rigidity at 20 C of 100 to 500 daN.m2   5. Method according to one of the preceding claims, wherein the   water ejection pressure is 150-400 bar when ejected   lateral direction towards the periphery of the reactor.   6. Method according to one of the preceding claims, wherein the   weight suspended from the tube is 10 to 5.10 daN.   7.- Device for implementing the method of any one   Claims 1 to 6, characterized in that it comprises at least   two coking reactors, at least one drum movable about its axis, at least one flexible tube as defined in said   claims, wound at rest on said drum and connected on the one hand   fluid supply means and on the other hand a device for ejecting said fluid, and means for guiding said tube as it unfolds, said drum being disposed at a level higher than that of the coking reactors and guiding means being adjusted   to allow the descent of the tube into at least one of the reactors.   8.- Device according to claim 7, further comprising means for moving the drum, to place it   successively above each of the coking reactors.