Feed injection method to prevent coking on the walls of transfer line reactors

A hydrocarbon feed injection method is provided in which concentric inlet conduits carry hydrocarbon liquid and steam. Small nozzles located on the outer steam-carrying conduit discharge steam in the direction of the inner wall of the transfer line reactor to protect the inner wall from carbonaceous deposits. The hydrocarbon feed nozzles are staged along a line parallel to the longitudinal axis of the transfer line.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method of introducing a 
hydrocarbonaceous feed into a transfer line reactor. 
2. Description of the Prior Art 
It is known to introduce a hydrocarbonaceous feed into a transfer line 
reaction zone operated at conditions at which at least a portion of the 
hydrocarbonaceous feed cracks, thereby producing a carbonaceous material 
(coke) which may deposit on the inner wall of the transfer line reactor. 
The term "transfer line reactor" is used herein to mean an elongated 
conduit type reaction zone having a high length to diameter ratio. The 
transfer line zone may be a zone in which it is desired to conduct a 
substantial amount of cracking or the transfer line zone may be a feed 
line into a reactor where only a portion of conversion of the feed occurs 
due to the temperature and pressure conditions of the transfer line zone. 
For example, fluid coking may be conducted in a transfer line, as shown in 
U.S. Pat. No. 3,671,424. Catalytic conversion of hydrocarbonaceous oil may 
also be carried out in a transfer line reactor. It is also known to 
decarbonize heavy hydrocarbonaceous oils in a transfer line, e.g., a 
rising confined vertical column, as shown in U.S. Pat. No. 4,263,128. 
A problem in transfer line processes operated at conditions where the 
hydrocarbons may crack, is the production of carbonaceous materials, a 
substantial amount of which may deposit on the inner wall of the transfer 
line. 
U.S. Pat. No. 2,937,988 discloses a method and apparatus for preventing 
coking on the walls of a transfer line reactor. A distributor deflects a 
flowing solids stream against the inner wall of the reactor to shield the 
inner wall of the reactor and protect the wall from carbonaceous deposits. 
U.S. Pat. No. 3,152,065 discloses a method of injecting hydrocarbon feed in 
a catalytic transfer line reaction zone in which the hydrocarbon feed 
inlet conduits are horizontally spaced. The steam inlets are positioned in 
the feed conduit. 
A feed and steam injection method has now been found in which a portion of 
the steam accompanying the feed is deflected towards the inner wall of the 
transfer line conduit so as to provide a protective steam cover which will 
minimize or prevent coke from depositing on the inner wall. 
SUMMARY OF THE INVENTION 
In accordance with the invention there is provided, a method of introducing 
a hydrocarbonaceous liquid feed into a transfer line reaction zone which 
comprises: introducing said hydrocarbonaceous liquid feed and steam into 
said transfer line reaction zone as separate concentric streams, said 
hydrocarbonaceous feed being the inner stream and said steam being the 
circumferential stream, discharging a first portion of said steam as a 
stream directed towards an inner wall of said transfer line reaction zone, 
and discharging said hydrocarbonaceous liquid and a second portion of said 
steam in a direction parallel to the longitudinal axis of said transfer 
line reaction zone.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, fluidized solids are introduced by riser 1 into 
transfer line reactor 2. The solids may be inert solids, such as coke, or 
may be catalytic solids or mixtures thereof. Steam is introduced into the 
bottom portion of transfer line reactor 2 by inlets 10 and 12 to maintain 
the solids as a suspension flowing upwardly in transfer line reactor 2. 
Suitable length to the diameter ratios for transfer line reactor 2 range 
from about 20 to about 40. Inlet conduits 14, 16, 18, 20, 22 and 24 are 
disposed as three pairs of conduits which enter through the vertical wall 
of transfer line reactor 2 and are disposed in a vertically staged manner 
so that the conduits terminate parallel to the longitudinal axis of 
transfer line reactor 2 and are at a spaced vertical distance from each 
other. FIG. 2 shows a sectional view of inlet conduit 14. Referring to 
FIG. 2, it can be seen that within inlet conduit 14 is disposed in 
concentric relation smaller diameter inlet conduit 15. A liquid 
hydrocarbonaceous feed is introduced into the inner smaller conduit 15. 
The hydrocarbonaceous feed may be any hydrocarbonaceous oil in liquid 
phase suitable for the specific process to be conducted in the transfer 
line reactor. Steam is introduced into the annulus formed by the outer 
wall of inner conduit 15 and the inner wall of conduit 14. The steam 
surrounds the inner conduit circumferentially. This steam acts as 
insulator to prevent or minimize coking inside the feed nozzle. Conduit 14 
has a gas outlet nozzle 38 disposed in a diagonal direction set at an 
angle such that steam will emerge from nozzle 38 and be directed towards 
the inner wall of transfer line reactor 2, thereby forming a layer of 
steam that will cover at least a portion of the inner wall. The steam 
cover will shield the inner wall of the transfer line reactor from 
carbonaceous deposits which result from cracking of the hydrocarbon feed. 
Concentric conduits 15 and 14 terminate in outlet nozzle 26 disposed 
vertically and upwardly so that the hydrocarbon liquid and the remaining 
portion of the steam emanate as an upwardly directed stream. Although no 
detail is shown on the nozzle tip, there are various well-known designs 
that permit the steam to provide good feed atomization. The hydrocarbon 
liquid may mix with the steam at the exit of the nozzle or the tip of the 
nozzle or the inner conduits may be shorter than the outer conduit so that 
the liquid and steam may mix before exiting from nozzle 26. Preferably, 
the transfer line reactor comprises more than one pair of concentric inlet 
conduits disposed in spaced relation parallel to the longitudinal axis of 
transfer line reactor so as to stage the introduction of the 
hydrocarbonaceous feed into the transfer line reactor. Returning to FIG. 
1, conduits 16, 18, 20, 22 and 24 are each comprised of a smaller inner 
concentric conduit and similar nozzle systems as the ones described for 
conduit 14. Although six pairs of inlet conduits are shown in FIG. 1, the 
number of pairs of inlet conduits is not critical and they may be more or 
less inlet conduits disposed around the circumference of the transfer line 
reactor. Gas outlet nozzles 38, 40, 42, 44, 46 and 48 are each disposed in 
a diagonal direction set at an angle such that steam will emerge from the 
nozzles and be directed towards the inner wall of transfer line reactor 1. 
Nozzles 26, 28, 30, 32, 34 and 36 are disposed vertically and upwardly 
parallel to the longitudinal axis of transfer line reactor 2 so that the 
liquid hydrocarbons and a portion of the steam emanate as an upwardly 
directed stream. the atomized hydrocarbonaceous feed, upon contact with 
the upflowing fluidized solids which are generally hot, will be vaporized. 
The suspension of solids and vaporized hydrocarbon flows out of transfer 
line reactor 2 as shown at 50. The suspension may be introduced into a 
dense fluidized bed of inert solids or catalytic solids for additional 
conversion of the hydrocarbons or the suspension may be separated in a 
gas-solid separation zone in a conventional way. 
The feed injection method of the present invention is suitable for use in a 
fluid coking process, in a catalytic cracking process, or in any process 
wherein carbon or coke is formed in a transfer line by desired or 
undesired cracking of a hydrocarbonaceous feed. 
Transfer line coking conditions vary widely and depend on the feed used and 
the desired amount of conversion. Any known transfer line coking 
conditions and feed may be used in the transfer line of the present 
invention, with or without added catalyst. 
Transfer line catalytic conversions of hydrocarbonaceous feeds such as 
catalytic cracking are also well known. Any known transfer line catalytic 
conversion conditions and feeds may be used in the transfer line of the 
present invention. The method of the present invention may also be used in 
transfer line processes to decarbonize and/or demetallize heavy 
hydrocarbonaceous oils in the presence of inert solids.