FR2511026A1 - MULTI-ZONE PROCESS AND REACTOR FOR CRACKING HEAVY HYDROCARBON LOADS - Google Patents

Abstract

THE FEED LOAD 10 ENTERS A TOP CRACKING ZONE 14 HAS FLUIDIZED AT 482-760C, WHERE THE TAR AND COKE ARE DEPOSITED ON AND IN A PARTICULAR BRACKET 17, WHICH RUNS THROUGH A TRAINING ZONE 18 IN A LOWER CARBONIFICATION ZONE 20 A LIT FLUIDIZED AT 927-1093C BY INTRODUCTION OF A GAS CONTAINING O AND VAPOR. THE TRAINING ZONE 18 CONTAINS A COARSE PADDING MATERIAL 19 SUPPORTED BY AN ANNULAR REFRACTORY GRILLE 34. THE DECOKEFIED SUPPORT 17 IS RECYCLED TO THE BED 15 BY A TRANSPORT GAS IN A CENTRAL DUCT 28, THE RECYCLING RATE IS REGULATED BY A VALVE 50.

Description

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  The present invention relates to a cracking process

  in a multi-zone fluidized bed for the conversion of hydro charges

  Heavy carbides to produce lighter liquid hydrocarbons and combustible gas The invention relates in particular to such a method and such a conversion apparatus using multiple zones of a fluidized bed of particulate support material to facilitate cracking of the charge in the upper zone and the gasification of the tar and coke deposited on and in the support in an area

  lower gasification lined with refractory.

  Considerable work has previously been carried out for the multi-stage gasification of heavy oil loads in fluidized beds, certain processes using a material of

  particulate support for carbon deposition and for gasification

  Multi-stage coal mining Certain characteristic corresponding patents include the patents of Et A 2 861 943 and 2 885 343 which describe the use of a circulating particulate support for the deposition of coke from crude oil feedstocks and residual oil US Patents 2,875 and 3,202,603 describe a multi-liquefied hydrogasification process for residual oils and tar feeds using particulate material for hydrocracking the oil feed heavy to produce gaseous and liquid fractions But there is

  has no description concerning the operating steps and the charac-

  important construction requirements for a reactor

  multi-zone on an industrial scale.

  There has therefore been an unmet need for a process

  convenient conversion and gasification for hydro charges

  heavy carbides such as residual oils to produce distillable liquids and combustible gases, and which would also produce the gasification of tars and coke produced from the feed in the same reactor and would produce gases and liquids

  clean fuels and would give an appropriate reactor design

  required for industrial scale operations.

  The present invention relates to a multi-zone reaction method and apparatus for cracking and conversion of heavy hydrocarbon feedstocks such as feedstocks of

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  crude oil and residual charges and mixtures of these oils with hard coal, to produce liquid hydrocarbons

  lighter lower boiling and gaseous products.

  The invention uses a multi-zone reactor comprising an upper zone

  cracking or conversion ratio and a lower gas zone

  fication or combustion, separated by an intermediate zone of

  drag which contains a particulate lining material having sufficient porosity to allow the passage of the particulate support material from top to bottom The upper and lower zones as well as the drive zone contain a particulate support material which is circulated in continuous across the three zones. Due to the high temperatures, such as 760-10930 C, required in the gasification and entrainment zones, these zones are completely lined with refractory materials so as to effectively limit the temperature of the metal walls to safety values and avoid thus an undesirable loss of resistance and also avoid corrosion and wear of the base metals. The design of the reactor is adapted to use in a unique and advantageous way the intrinsic resistance of these refractory materials at high temperatures with a view to the structure. coarse packing used in the intermediate drive zone is supported by an annular refractory grid provided with openings, which preferably has an arch section This grid is in turn supported on its outer and inner circular edges by the refractory lining structures of the room or area of

  lower annular gasification.

  The hot particulate support material is recycled

  from bottom to top of the lower gasification or combustion zone

  tion to the upper cracking or conversion zone by a vertical transfer pipe This pipe consists of a tube of a temperature-resistant metal which is lined with refractory

  to prevent wear by particles moving upwards.

  The metal tubular pipe is fully supported from the interior refractory lining or the column of the annular gasification chamber In addition, the lower end

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  of the central pipe lined with refractory has a reduced diameter and constitutes the bearing surface coated with refractory of an adjustment valve, which regulates the recycling rate of the solids of

  particulate support from bottom to top from the lower area or chamber

  gasification to the cracking or conversion zone. The regulating valve also has a shutter element which is coated with a refractory to ensure protection against wear and a long service life. The recycling of particulate solids is facilitated by a transport gas which is passed from bottom to top. through the valve plug at a point above the valve seat The valve plug is also effectively cooled by the upward flow of gas which is preferably steam or a supplied process gas cycle at a temperature not exceeding about 3990 C. The invention will be better understood on reading the

  description which will follow preferred modes of implementation, in

  reference to the accompanying drawings, in which: FIG. 1 is a sectional view of the overall configuration of a multi-zone reactor showing the internal details of the

  reactor, including support details for refractory lining

  shut and the grid, FIG. 2 is an isometric view of two characteristic sectors of the refractory grid structure of annular shape provided with openings, and

  Figure 3 is a sectional view showing the configuration

  ration of the control valve and the solids recycling line.

  As seen in Figure 1, a supply current

  tation of heavy crude oil or residual oil in 10, as obtained by preliminary distillation steps, is pressurized in 12 and preheated in 13 to the necessary temperature, for example 121316 ° C. The preheated stream is introduced by an appropriate spraying device 14 a into the upper primary cracking zone 14 of the multi-zone reactor 16 Zone 14 contains a fluidized bed 15 of a particulate solid support material 17, which is maintained at a temperature of 482- 760 ° C so that the feedstock of heavy hydrocarbons is still heated there and

  subjected to thermal cracking The reactor pressure is usually

  Rely maintained at 15-57 bars, although higher pressures can be used. The bed 15 is fluidized by ascending reducing gases produced in a lower zone. A little coke produced in the cracking reaction is deposited on and in the material. of

  support 17 The resulting product gas passes with some fine

  carrier material tiles from bottom to top through a separator

  cyclone 30 and the gas leaves the reactor.

  The majority of the particulate support material in zone 14, usually containing 3-25% by weight of coke deposits and

  of heavy liquid hydrocarbons, descends through the entrainment zone

  nearby filled intermediate 18 o a little liquid is

  separated from particles by entrainment by ascending gases.

  The dry solids then descend to the lower gasification zone 20 containing the fluidized bed 21 which is maintained at a temperature of 927-1093 C. In this, the carbon black and the coke deposited on and in the support material are gasified in the presence of a gas containing oxygen and vapor introduced into the bed 21 at the nozzle 22 by the distributor 23 A little tar formed in the upper fluidized bed 15 and deposited on and in the support material 17 can be entrained towards the lower bed 21, where the tars are gasified and separated from the support A little tars can undergo a secondary cracking in liquid hydrocarbons

  light and gaseous in the training area 18.

  Choosing a particulate support material 17

  suitable for its absorption and distribution characteristics

  tion of pores is such that it collects all tar, carbon

  and the coke from the cracked products released in the upper zone

  14 and the bed 15 After the gasification of the tars, the coal and the coke in the lower fluidized bed 21, the particulate support material 17 is recycled to the upper bed using a transport gas supplied at 24, such as steam or recycled gas, and pass it through a vertical transfer line

  28 and the assembly of the adjustment valve 50.

  The lower gasification zone 20 is shaped

  annular and lined with refractory material on its outer wall

  upper 25, in the bottom 16 b and on the inner wall 26, for example the "Greencast in 94" manufactured by the Company A P Green Co. The inner refractory wall 26 is cylindrical in shape and preferably supported by the lining of refractory material

  16 b present in the bottom of the reactor.

  Multiple openings 27 are drilled in the end

  lower part of the internal refractory wall 26 for the passage of the solid support particles 17 from the gasification chamber to the lower end of the transfer pipe 28 These openings 27 are preferably provided with tubular sleeves 27 made of a material hard refractory which is more resistant to wear and erosion by the flow of solid particles 17 than the refractory structure 26 b The multiple passages 27 can also be provided in the solid refractory material in the bottom 16 b of the reactor In in any case it is essential that the orifice

  entrance to passages 27 is located at a point below the distribution

  tor 23 for the introduction of the oxygen-containing gas into the fluidized bed, to prevent the passage of the oxygen-containing gas in the vertical pipe 28, which is preferably located axially

in the reactor.

  The adjustment of the flow of the particular support material

  ring 17 in the transfer line 2 S at its lower end is obtained by the adjustment valve 50 The support material is suspended and entrained towards the upper bed 14 by the transport gas supplied to the fitting 24 The upper end of the line 28 ends in the fluidized bed 14 A little of the support material can be entrained by the effluent gas from the zone 14 to an internal cyclone separator system 30, which serves to trap the majority of the particulate support material and return it in the cracking zone 14 Top-up can be done by adding support material to the reactor if necessary, usually by a pressure-locked hopper 31 Worn support material can be

  similarly drawn off through line 32.

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  The intermediate drive zone 18 contains a coarse solid packing material 19 having a dimension of at least about 10 times that of the particulate support material 17 and includes sufficient voids to allow the passage of the particulate solids from top to bottom. packing 19 may consist of Raschig rings or ceramic saddles or similar materials and shapes This packing 19 is supported by an annular grid structure 34-provided with openings To limit the pressure drop across the intermediate drive zone 18 and to facilitate the downward flow of particulate solids 17 to

  through it, the packing material 19 may have a dimension

  relatively coarse sion, for example an effective diameter of 12.7-50.8 mm The openings 34 a in the grid 34 for the flow of gas and solids are dimensioned to avoid passage to

  the bottom of the lining 19 and can be analogously relati-

  vely large and have various shapes, for example circular, square, elongated, etc., as indicated generally in the

figure 2.

  Depending on the feedstock used, i.e. heavy oil or oil-coal suspension, the gaseous and liquid products leave the reactor, with the small amount of unprocessed coke of small particle size and a larger portion. ash into small particles, through stream 37 and pass to an external cyclone solids separation system 38 This separation step removes the remaining coke and ash particles from the product gas stream as a stream of

  waste 39 The current resulting from cyclone effluent 40 is

  usually quenched by a stream 41, for example of oil, or otherwise cooled to reduce its temperature and limit or prevent subsequent undesirable reactions The gas and the cooled liquids are then separated by conventional fractionation means 44 to give a stream of product gaseous 45, a stream of light liquid 46 and a heavier liquid fraction 47 If desired, a portion 48 of the heavy fraction 47 can be recycled to the

  cracking zone 14 for a new reaction.

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  As regards the annular grid 34 provided with openings which support the coarse lining 19 in the drive zone 18, it is made of a resistant refractory material capable of withstanding temperatures of around 10 930 C for prolonged periods, for example the product sold under the name of "Cerox 600" by the Company CE Refractories, Inc. The grid has a straight arched section to remain tight and in compression in order to prevent a loss of packing product 19 from above, even if a crack has to develop in the grid The grid is made up of multiple sectors 35; two of them are typically shown in Figure 2 The use of these radial sectors allows the grid to be installed through an opening

  in manhole like manhole 33 located at the top of the reac-

  These sectors 35 rest on the surfaces of circular shoulders.

  outside and inside areas 25 a and 26 a in the refractory lining

  25 and wall 26, respectively The sectors 35 are held in place mainly by the weight of the rough lining 19 located immediately above and of which they constitute the support The openings 34 a are dimensioned so as to pocket the passage of the lining material 19 and can have any shape, for example circular, square or elongated If desired, the

  upper surface of the grid sectors 35 may include undulations

  lations for pocketing the pieces of packing material 19 of

  plug the grid openings 34 a.

  After combustion, in the lower gasification zone

  20, coke deposited on the particulate support material 17, the hot decoked support solids are passed radially inwardly through the openings 27 and the control valve, and they are transferred from the gasification zone 20 by the

  ascending pipe 28 by means of the transport gas supplied at 24.

  This pipe 28 is preferably disposed axially in the reactor 16 and comprises a heat-resistant, pressure-tight metal tube 29 which carries a refractory lining 29 a pocketing the wear of the metal by the solids of the ascending particulate support 17 A suitable refractory lining material is sold by RESCO Products, Inc. under the name "RESCO CAST

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  na AA-22 ", which is placed inside the tube 29 The vertical pipe 28 is rigidly fixed and carried by the upper end of the inner refractory lining of the column 26, and preferably fixed to the column refractory 26 at point 28 a, for example by bolts 28 b which are molded in the refractory wall 26. Figure 3 shows a sectional view of the control valve 50, comprising a valve seat 51 coated with refractory and a shutter 54 cooled which regulates the recycling of hot decoked particulate solids 17 from the lower combustion zone 20 to the upper cracking zone 14 The central pipe 28 has a reduced diameter at its lower end 28 c sufficient to constitute the valve seat 51 If one if desired, the seat 51 can be made removable from the end 28c of the pipe, for example by means of a bolted flange seal 52, for repairs or replacement if necessary%

  The valve shutter 54 comprises a metal tube.

  lique 55 comprising a reamed portion 56 intermediate between the ends of the tube, and serves as a valve shutter structure adapting with the carrying element 51 The upper portion of

  tube 55 and the bored portion 56 are coated with a refractory material

  silent 57 The bore 56 contains a horizontal plate 58 and also multiple openings 58 a in the plate 58 and openings 55 a in the tube 55, which serve to divert the upward flow of the transport gas through the openings to cool effectively

  the metal portions of the shutter 54 The tube 55 and its coating

  refractory 57 also extend above the carrying surface 51 by a distance at least equal to the internal diameter of the seat 51, and preferably 1.5-10 times this diameter A refractory material 59 is also applied around the tube 55 below the bore 56 to prevent wear of the tube by the solids 17 flowing radially inward The gas flowing from bottom to

  high through the tube 55 and its extension 55 b facilitates recycling

  keying of hot support solids 17 from bottom to top across the

  valve seat 51 and line 28.

  The transport gas used to suspend and transfer the hot particulate solids 17 from bottom to top through line 28 is introduced through opening 24 and passes from bottom to top through tube 55 at a speed of at least 1.8 m / s and preferably at 3-12.2 m / s This gas flow is also used to cool the valve plug 54 This transport and cooling gas is preferably a manufacturing cycle gas

  such as steam or recycled combustible gas having a temperature

  initial erection not exceeding about 3990 C. A packing box 60 is provided around the tube 55 to prevent the transport gas from being derived from the tube and also to prevent the solids of the particulate support 17

  do not enter the gas inlet passage 62 around the tube 55.

  The stuffing box 60 is covered by a refractory plate 64

  for protection against wear The shutter 54 is moved axially.

  as required by means of an appropriate control device

  (not shown) to regulate the upward flow of partial solids

  17, using the control rod 66 which is connected to the tube 55 by a radial console 67 and made pressure-tight by the boot with lower trim 68 The assembly of the adjustment valve 54 can be removed from the lower end of the central pipe 28 and separated from the valve seat 51 by disconnecting the bolted flange 70 and separating the assembly downwards

for examination or repair.

  During the start-up of the multi-zone reactor 16 from cold conditions or close to ambient conditions, the central pipe 28 is heated and expands downwards. The assembly of the shutter 54 is similarly removed by the control device ( not shown) to prevent excessive compression force from developing between the valve plug 54 and the seat surface 51 The transport gas supplied at 24 flows from bottom to top through the tube 55 to facilitate the recycling the solids of the particulate support 17 from the gasification zone

  lower towards the upper cracking zone 14.

  It is understood that the invention is not limited to the preferred embodiments described above by way of illustration and that a person skilled in the art can make modifications without departing from it.

of the scope of the invention.

RE V E ND I CA T I O N S

  1 Process for the conversion of a heavy hydrocarbon feedstock to produce lighter liquid hydrocarbons and combustible gases, characterized in that it comprises the following steps: (a) the feedstock is introduced into an upper cracking zone (14) under fluidized bed pressure maintained at a temperature of 482-760 C, said zone (14) containing a fluidized bed (15) of particulate support material (17) which is fluidized by the passage of reducing gases in an updraft through said bed; (b) passing the support material (17) containing coke deposits from top to bottom through an intermediate drive zone (18) in a lower gasification zone (20) with a fluidized bed to gasify the deposits of coke and remove them from the support material in said area; (c) a gas containing oxygen and steam is injected into the lower gasification zone (20) for the reaction with said coke deposited on and in the support material (17) and to maintain a temperature of 927- 1093 C for the gasification of coke and for producing the reducing gases; (d) said reducing gases are passed successively from bottom to top through said drive zone (18) and through said fluidized bed (15) into said upper cracking zone (14) to fluidize the bed; (e) passing the particulate support material

  (17) hot decoked resulting from the lower gasification zone

  lower (20) radially inwards by passages (27) at the lower end (28 c) of a vertical transfer pipe (28) at a point lower than the injection point (23) of the gas containing oxygen and said solids are recycled from bottom to top through an adjustment valve (50) and the line (28) in the upper cracking zone (14) at a speed adjusted using a gas

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  transport flowing in said pipe (28) at a speed sufficient to ensure the transport of said -solids; (f) separating said resulting gaseous products from said particulate material at (30) above the upper cracking zone (14) and returning said separated particulate material to the reaction zone for further use; and (g) the effluent gas and the liquid products are withdrawn

  distillable from said upper cracking zone (14).

  2 Method according to claim 1, characterized in that the recycling of the solids from the particulate support (17) decoke

  towards the upper cracking zone (14) is adjusted by the passage.

  transport gas from bottom to top through the hollow shutter portion (55) of a control valve assembly (54) and into said

  transfer line (28), and in that the velocity of the gas flowing

  Lement ascending in said pipe is at least about 1.8 m / s.

  3 Method according to claim 2, characterized in that the transport gas is supplied at a temperature not exceeding about 3990 C and in that the shutter (54) of the control valve is internally cooled by passage of the transport gas

  from bottom to top through said shutter (54).

  4 Method according to claim 1, characterized in that

  that said gases and said particulate matter are separated externally

  laughing at said reaction zones, the particulate material (17) is recycled to the reactor (16) and the stream of clean effluent is cooled and sent to a fractionation step at (44) for the

  recovery of gas and distillable liquids.

  Method according to claim 1, characterized in that the feedstock contains particles of carbon and in that the method comprises the additional step of separating the ash particles at the bottom of said zone of

gasification (20).

  6 Improved process for the conversion of heavy hydrocarbon feedstocks to produce lighter liquid hydrocarbons and combustible gases, in which the feedstock is introduced into an upper cracking zone (14) with a fluidized bed in a temperature range 482-760 C, and coke is deposited on and in the particulate support material

  (17) which is passed from top to bottom through an area of

  dragging (18) with lining and into which a gas is injected

  oxygen and vapor in a lower gas zone

  fluidized bed cation (20) for gasifying the coke deposited on and in the particulate support material (17) and producing a reducing gas which passes from bottom to top to fluidize the zones of the reactor, the improvement being characterized in that that the recycling rate of the particulate solids flowing from the lower gasification zone (20) to the upper cracking zone (14) be adjusted by passing a transport gas from bottom to top through a hollow shutter ( 54) at a point above the surface

of the valve seat (51).

  7 A method according to claim 6, further characterized in that the shutter (54) of the valve (50, 'for adjusting the recycling of solids is cooled by passing the transport gas to a temperature not exceeding approximately 3990 C from bottom to top at

  through passages (58a) in the valve plug.

  8 Multi-zone reactor for cracking and converting feeds from heavy hydrocarbons to produce lighter liquids - and gases, characterized in that it comprises (a) a metal reactor container (16) capable of be pressurized; (b) a conversion zone (14) located in the upper end of the reactor for carrying out a reaction in a fluidized bed; (c) means for introducing a charge of liquid hydrocarbons (10) into said conversion zone (14); (d) an annular gasification chamber (20) located at the lower end of the reactor for carrying out a gasification reaction in a fluidized bed; (e) a line (22) for introducing an oxygen-containing gas and water vapor into said lower gasification zone (20); (f) a drive zone (18) intermediate between the upper conversion zone (14) and the lower gasification zone (20), said drive zone (18) containing a particulate packing material (19) in large particles ;

  (g) an outer refractory lining (25) inside

  laughing of said lower annular gasification zone (20), said refractory lining (25) being adapted to allow expansion

  differential thermal tion between the lining and the outer wall

  metallic container; (h) an inner cylindrical refractory wall (26) is supported by the outer refractory lining (16b); (i) a line (28) for circulating a particulate support material (17) from the bottom to the top of the lower gasification zone (20) to the upper conversion zone (14), said line (28) being provided with refractory and supported by said interior refractory wall (26);

  (j) means (22, 23) for introducing a trans gas

  port in the lower end of said pipe (28); and (k) means for separating the resulting gases from the

  upper part of said reactor vessel.

  9 Reactor according to claim 8, characterized in that

  that the coarse packing material (19) in the entrainment area

  Intermediate ment (18) is supported by an annular grid (34), provided with openings, hunger in refractory material and located at

  the upper end of the gasification zone (20).

  Reactor according to claim 9, characterized in that said grid (34) has an arch shape and comprises several radial sectors (35) which are each supported by the refractory lining of the lower annular gasification zone (20),

  said sectors being able to be removed from the reactor.

  Reactor according to claim 8, characterized in that each zone contains a particulate support material which is fluidized and recycled from top to bottom from the upper conversion zone (14) through said drive zone (18) to said zone lower gasification (20), then recycled from bottom to top through an adjustment valve (50) and a central pipe (28) lined with refractory to said upper reaction zone

(14).

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  12 Reactor according to claim 8, characterized in that a phase separation device (30) provided with a refractory is provided above the conversion zone to separate the material

  of particulate support (17) and return it to the reactor.

  13 Reactor according to claim 11, characterized in that the recycled particulate support material (17) passes from bottom to top through an adjustment valve (50) provided with a refractory

  located at the lower end (28 c) of the central pipe (28).

  14 Reactor according to claim 11, characterized in that the carrying surface (51) of the adjustment valve (50) is formed by the lower end of the central pipe (28) and in that said lower end (28 c ) of the pipe (28) is coated with

  refractory (29) on both the inner and outer faces.

  Reactor according to claim 14, characterized in that the carrying portion of the valve is removable from said

central pipe (28).

  16 Reactor according to claim 11, characterized in that the shutter (54) of the solids control valve (50) (17)

  is coated with refractory material (57) and has steps

  internal flow wise (55 a, 58 a) for cooling said

  shutter by the upward transport gas.

  17 Reactor according to claim 16, characterized in that said refractory lining (57) of the valve shutter extends above the surface of the shutter by a distance

  at least equal to the inside diameter of the valve seat (51).

  18 Multi-zone reactor for cracking and converting feedstocks of heavy hydrocarbons to produce lighter liquids and gases, characterized in that it comprises (a) a metallic reactor container (16) which can be pressurized; (b) a conversion zone (14) located at the end

  upper part of the reactor and containing a particular support material

  water (17) for carrying out a reaction in a fluidized bed;

  (c) means (14 a) for introducing a feedstock

  mentation of liquid hydrocarbons (10) in said conversion zone

(14);

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  (d) an annular gasification chamber (20) located at the lower end of the reactor and containing a material of

  particulate support (17) for carrying out a gasification reaction

  cation in fluidized bed; (e) a line (22) for introducing a gas containing oxygen and water vapor into said lower gasification zone (20); (f) a drive zone (18) intermediate between the upper conversion zone (14) and the lower gasification zone (20), said drive zone (18) containing a particulate packing material in large particles (19 ), supported by an annular grid (34) of refractory material located at the upper end of the gasification zone (20);

  (g) an outer refractory lining (25) inside

  of said lower annular gasification zone (20), said

  refractory lining (25) being adapted to allow expansion

  differential thermal tion between the lining and the outer metal wall of the container; (h) an inner cylindrical refractory wall (26) which is supported by the outer refractory lining; (i) a pipe (28) for the circulation of a material

  of particulate support (17) from top to bottom from the lower area

  gasification (20) towards the upper conversion zone (14), said pipe (28) being lined with refractory and supported by the internal refractory wall (26) and comprising an adjustment valve (50) located at the lower end of said conduct

(28);

  (j) means (23) for introducing a transport gas into the lower end of said pipe (28); and (k) means for separating the resulting gases from the

  upper portion of said reactor vessel.