FEED NOZZLE ASSEMBLY FOR A CATALYTIC CRACKING REACTOR

Abstract

Reactor vessel and a feed nozzle assembly for feeding a gas and a liquid into such reactor vessel. The feed nozzle assembly comprises an outer tube supplying a first liquid feed, such as oil, an inner tube supplying a dispersion gas, such as steam, a third tube supplying a second liquid feed, such as biomass, and a nozzle end. A catalytic cracking process wherein two or more hydrocarbon liquids are jointly dispersed into a dispersion gas and jetted via the same feed nozzle assembly into a catalytic cracking reactor.

Claims

1. A catalytic cracking reactor comprising one or more feed nozzle assemblies, wherein at least one of the feed nozzle assemblies comprises: an outer tube extending between a first liquid feed inlet and a nozzle outlet; an inner tube comprising purging orifices in an upstream half of the inner tube and with a downstream section having a gas outlet, the downstream section of the inner tube being arranged within the outer tube to define an annular conduit, wherein the nozzle outlet of the outer tube is downstream in line with the gas outlet of the inner tube; a third tube with one end connected to a second liquid feed inlet and an opposite end with an outlet, at least the outlet being positioned within the annular conduit upstream the gas outlet.

2. A catalytic cracking reactor according to claim 1, wherein at least one of the feed nozzle assemblies is a side entry feed nozzle assembly.

3. A catalytic cracking process wherein a first liquid hydrocarbon fraction is dispersed into a dispersion gas and jetted via one or more feed nozzle assemblies into a catalytic cracking reactor, wherein one or more further hydrocarbon fractions are also fed to the feed nozzle assembly and jointly dispersed with the first hydrocarbon fraction.

4. A catalytic cracking process according to claim 3, wherein the first liquid hydrocarbon feed is oil and the one or more further hydrocarbon fractions include at least one biomass fraction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention will now be described by way of example in more detail with reference to the accompanying drawings, wherein:

[0022] FIG. 1 shows a longitudinal section of the feed nozzle assembly of the invention;

[0023] FIG. 2 shows schematically a fluid catalytic cracking reactor comprising the feed nozzle of FIG. 1.

DETAILED DESCRIPTION

[0024] FIG. 1 shows a feed nozzle assembly 1 for feeding steam, crude oil and biomass into a catalytic cracking reactor. The feed nozzle assembly 1 comprises a cylindrical inner tube 2 and a cylindrical outer tube 3. The inner tube 2 defines a gas conduit and extends between a dispersion gas inlet 4 and a dispersion gas outlet with one or more orifices 5. The outer tube 3 extends between a liquid inlet 6 and a nozzle outlet 7 aligned with the one or more gas orifices 5 of the inner tube 2. The one or more gas orifices 5 are arranged upstream the nozzle outlet 7.

[0025] The outer end of the outer tube 3 is bordered by a semispherical end wall 8 comprising the nozzle outlet 7. Similarly, the outer end of the inner tube 2 is bordered by a semispherical end wall 9 comprising the dispersion gas orifice 5. The two semispherical end walls 8, 9 define a chamber 11.

[0026] The inner tube 2 is coaxially arranged within the outer tube 3 to define an annular liquid conduit 13. An array of equidistantly arranged parallel tubes 14 is positioned within the annular conduit 13. The tubes 14 are fixed in an annular plate 16 extending perpendicularly to the longitudinal axis of the inner and outer tubes 2, 3. The annular plate 16 comprises a central opening 17 holding the inner tube 2 and a circular array of openings 18 holding the tubes 14.

[0027] The inner tube 2 has an upstream end connected via a tube bend 19 to the radially extending dispersion gas inlet 4. The tube bend 19 crosses the wall 21 of the outer tube 3. Such a radial side-entrance of the dispersion gas inlet 4 into the feed nozzle assembly 1 allows better access to the inside of the feed nozzle assembly 1. In an alternative embodiment, the liquid inlet 6 can be arranged radially while the dispersion gas inlet 4 is coaxially in line with the nozzle.

[0028] The tubes 14 include muffler tubes 22 allowing passage of the flow of liquid hydrocarbon fraction through the annular conduit 13, and at least one biomass tube 23 connected by a tube bend 24 to a radially extending inlet 26 for biomass. The tube bend 24 crosses the wall 21 of the outer tube 3. The biomass tube 23 has an outlet 27 within the annular conduit 13 upstream the outlets 5, 7.

[0029] The nozzle outlet 7 can comprise one or more openings or orifices of any suitable outline, for instance an elongated slit. The steam outlet 5 can for instance be provided with one or more rows of orifices or openings, more specifically of from 1 to 8 rows or from 1 to 6 rows.

[0030] The inner tube 2 comprises purging orifices 28. These purging orifices 28 ensure that part of the dispersion gas flows through the annular conduit 13 in case the supply of hydrocarbon liquid stops for example in case of emergency. In order to make maximum use of the dispersion gas added, the purging orifices 28 can be located in the upstream half of the inner tube 2 located inside the outer tube 3.

[0031] FIG. 2 shows a schematic representation of a fluidized catalytic cracking reactor 30 comprising the feed nozzle assembly 1 of FIG. 1. The reactor 30 comprises a riser reactor 31. In the riser reactor 31 an atomized liquid feed is contacted with a particulate solid catalyst catalyzing the desired cracking reactions. Used catalyst is fed via a line 32 to a regenerator 33, where the catalyst is regenerated. The regenerated catalyst is returned via a return line 34 to the riser reactor 31 for re-use. Feed nozzle assemblies 1 of the type as shown in FIG. 1 are mounted as side entry feed nozzles on the wall of the riser reactor 31. The feed nozzle assemblies 1 are directed upwardly under an acute angle with the vertical riser reactor wall. In order to provide an even distribution of the oil over the riser, multiple side entry feed nozzles can be located on the riser circumference at the same or different levels. A further advantage of placing the nozzles around the riser circumference is that this tends to off-set the tendency of the catalyst to migrate to the riser walls.

[0032] During normal operation of the feed nozzle assembly 1 dispersion gas, generally steam, is supplied from the dispersion gas inlet 4 through the inner tube 2 while hydrocarbon feed, generally crude oil, is supplied via the inlet 6 to the annular liquid conduit 13. A feed of a second hydrocarbon liquid, such as biomass, is supplied via the third tube 23. Steam, exiting the steam orifice 5 jointly disperses the crude oil with the biomass. The joint hydrocarbon feed is atomized at the nozzle outlet 7 into the fluid catalytic cracking reactor.

[0033] In the riser 31 of the fluid catalytic cracking reactor the hydrocarbon feed is vaporized and cracked into smaller molecules under the action of a regenerated hot catalyst. The catalyst may for example have a temperature of at least 600 C. Cracked product vapours are separated from spent catalyst with the help of cyclones. The hydrocarbon feed generally is heated, preferably to a temperature of from 150 to 300 C., before being fed to the feed nozzle and the riser reactor.