Apparatus and process for cooling fluid solid particles

An arrangement of apparatus and process thereof for cooling hot fluid solid particles, especially hot regenerated catalytic particles are disclosed. The apparatus comprises a substantially vertical, cylindrical and close ended heat removal vessel through the shell side passage of which is passed the fluid solid particles that flow downwardly in the form of dense phase fluidized bed, and one or more separate heat exchange tube units through the tube side passage of which the coolant is passed and vaporized, each of said heat exchange tube units comprising a supply coolant inlet tube, a supply coolant collecting chamber, one or more heat exchange tubes, a vapour collecting chamber and a resulting vapour discharge tube, all of which constitute a close type coolant-to-vapour circulation. The apparatus and process of the present invention is particularly adequate to be utilized in combination with a catalyst regeneration operation in a fluid catalytic cracking operation of heavy residual oil feedstock for the conversion thereof into lighter and more valuable products.

FIELD OF THE INVENTION 
The field of art to which the present invention pertains is heat transfer 
between fluid solid particles and a heat exchange medium. In particular, 
this invention relates to an arrangement of apparatus and process thereof 
for cooling fluid solid particles. More particularly, the invention is 
concerned with an apparatus and process for the external removal of a 
portion of heat of hot regenerated catalytic particles from a catalyst 
regeneration vessel in which the catalytic particles have been regenerated 
in a combustion zone and will be recycled to a reaction zone for the 
conversion of residual fractions of crude oils to lighter and more 
valuable hydrocarbons. 
DESCRIPTION OF THE PRIOR ART 
The fluid catalytic cracking process (hereinafter referred to as "FCC" 
process) has been universally used for the conversion of vacuum gas oil or 
more heavier materials to lighter products. The FCC process comprises the 
steps such as catalytic cracking reaction, catalyst regeneration, 
separation of the catalyst from the flue gas and recovery or removal of 
excess heat generated in the catalyst regeneration from a regeneration 
vessel. The vacuum gas oil or more heavier materials, which are used as 
feedstock of an FCC reaction vessel are brought into contact with fresh or 
regenerated catalysts wherein the cracking reactions take place under 
cracking conditions such that the heavy feedstock is catalytically broken 
down or cracked into lighter or more valuable products. In so processing, 
the heavy feedstock undergoes the cracking reactions and the resulting 
deactivating materials, such as carbonaceous deposits or coke, are 
accumulated upon the surface of the catalyst which, as a result, is 
deactivated so as not to be able to catalyze the successive cracking 
reactions further. This catalyst must be regenerated for the restoration 
of catalytic activity before it is recycled for the reuse and therefore is 
hereinafter referred to as "catalyst to be regenerated or spent catalyst". 
In order to activate the catalyst to be regenerated, it may be passed into 
a combustion chamber wherein it is admixed with air or oxygen containing 
gas. At an elevated temperature, the carbonaceous deposits accumulated 
upon the surface of the catalyst are burnt so that the activity of the 
catalyst could be restored. The catalyst from which the carbonaceous 
deposits are substantially reduced by the combustion thereof is referred 
to as "regenerated catalyst or activated catalyst". 
The admixture of regenerated catalyst and flue gas is separated in a 
cyclone. The high temperature flue gas takes over a portion of thermal 
energy exiting in the regeneration vessel and is subsequently discharged 
to an energy recovery system. The regenerated catalyst is transferred to a 
reaction zone and again brought into admixture and contact with the fresh 
feedstock, and the successive cracking reaction so begins again. The 
tendency to form the deactivating carbonaceous deposits or coke on the 
catalyst surface in an FCC operation increases when the feedstock becomes 
heavier. The quantity of heat generated in burning the so formed 
carbonaceous deposits will exceed that required for the reaction zone. It 
is then accordingly necessary to transfer at least a portion of the 
regenerated catalyst into a catalyst cooler for releasing the excess heat 
in order to maintain the thermal equilibrium in an FCC apparatus or 
process. 
Recently, there is more and more great demand for lighter oil products as 
the petrochemical industry develops. The feedstock for an FCC operation 
would involve the heavier residues, correspondingly. The chemical nature 
and molecular structure of the feedstock will affect the level of coke 
surface-deposited upon the catalyst. Generally speaking, the higher the 
molecular weight of the feedstock, the higher the level of the Conradson 
carbon (ASTM Method D189) and the larger will be the quantity of the 
deactivating carbonaceous deposits formed in an FCC operation. The larger 
amount of carbonaceous deposits accumulated upon the surface of the 
catalyst will release more thermal energy when combusted in a combustion 
zone of regeneration vessel with an oxygen containing gas. In general, the 
level of surface-deposited carbonaceous material or coke in a catalytic 
cracking reaction zone to which the vacuum gas oil is fed as feedstock is 
less than 6.5%. With this level of coke, the quantity of heat generated in 
a catalyst regeneration vessel with an oxygen containing gas will be 
absorbed in the reaction section, thereby providing the ability to 
maintain the thermal equilibrium in an FCC operation. When the feedstock 
to an FCC operation becomes heavier, the level of carbonaceous deposits or 
coke formed will exceed 6.5%, for example 6.5-15%. The quantity of heat 
generated when the catalyst to be regenerated is combusted with an 
oxygen-containing gas will be more than required for the performance of 
the cracking reaction, for example in a riser type reactor. This will then 
result in surplus of heat and an increase of the temperature in a 
reaction-regeneration system. Normal operation conditions will be 
disrupted. The release or removal of surplus thermal energy will be 
accordingly needed for the maintenance of a normal operation temperature. 
The methods for the release or removal of excess heat from the catalyst 
regeneration vessel are generally internal and/or external heat exchange 
operations vis a vis the regeneration vessel. That is to say, the heat 
removal is carried out within the means internal and/or external to the 
catalyst regeneration vessel. 
In an internal heat removal operation vis a vis the regeneration vessel, 
the cooling coils are provided within the regeneration vessel. These 
cooling coils may be substantially horizontally or vertically arranged 
inside the dense phase bed of regenerated catalyst particles. The outer 
surface of these cooling coils is directly contacted with the catalyst 
being regenerated. The supply water is passed through the cooling coils 
for the absorption of excess heat generated during the combustion of the 
carbonaceous deposits and then evaporated into steam. At the same time, 
the regenerated catalyst is cooled and thus the temperature of the 
reaction-regeneration system may be controlled as being within the 
prescribed range. In the prior art in this regard, there may be mentioned 
the present inventor's article entitled "Design of Internal Heat Remover 
Used in a Fluid Catalytic Cracking Apparatus". PETROLEUM PROCESSING, No. 5 
(1987), BEIJING, and early patents, for example U.S. Pat. No. 4,160,743 to 
Kelley and others which are incorporated herein by reference. 
The greatest disadvantage of the internal heat removal method is shown by 
the fact that the quantity of heat to be removed is difficult to be 
precisely controlled. Due to such an incontrollability of the heat 
removal, the internal heat remove method has not been applicable to an FCC 
apparatus or process in which the feedstock is usually varied. For this 
reason, there have been provided a variety of external heat remove methods 
which are proposed vis a vis the internal heat removal methods. There have 
been many prior art patents in this regard, for example U.S. Pat. Nos. 
2,395,106 to Day et al., 2,515,156 to Jahnig et al., 2,492,948 to Berger, 
2,735,802 to Jahnig, 2,862,798 to Mckinney, 2,873,175 to Owens, 2,970,117 
to Harper, 4,353,812 to Lomas et al., 4,364,849 to Vickers et al., 
4,396,531 to Lomas, 4,424,192 to Lomas et al., 4,434,245 to Lomas et al., 
4,438,071 to Vickevs et al., 4,439,533 to Lomas et al., 4,483,276 to Lomas 
et al., 4,578,366 to Cetinkaya et al., 4,582,120 to Walters et al., 
4,605,636 to Walters et al., 4,614,726 to Walters et al., 4,698,212 to 
Walters et al., 4,710,357 to Cetinkaya et al., 4,716,958 to Walters et 
al., 4,757,039 to Lomas, 4,822,761 to Walters et al., and 4,881,592 to 
Cetinkaya and others which are also incorporated herein by reference. 
However, these external heat removal means suffer from certain serious 
disadvantages which, among others, may be generalized as stated 
hereinbelow. 
(1) A plurality of heat remove tubes are connected to one tube sheet to 
perform indirect heat exchange between hot fluid solid particles and a 
heat exchange medium. In the operation procedure, when one of these tubes 
is broken down due to, for example, wear and tear, poor welding, being 
locally overheated or tube wall metal ineffectiveness, the cooling medium 
will be spattered at a location of leakage into the shell passage of the 
external heat removal system. This type of external heat remove system is 
an integrate construction. That is to say, any effective portion thereof 
can not be isolated. In case of any breakdown occurring in a heat removal 
operation, all the external heat removal system must be stopped. It may 
be, therefore, concluded that this type heat removal system is not 
flexible or saying poor in security and reliability. 
(2) A plurality of heat exchange tubes and water supply tubes are connected 
with two tube sheets to carry out an indirect heat exchange operation. The 
tube sheet chamber bears a pressure of up to 4.5 MPa. As such, this type 
of tube sheet arrangement causes certain disadvantages which prove to be 
difficult to overcome. Firstly, the tube sheet is very thick. For example, 
an external heat removal system having a diameter of 2000 mm will be up to 
8000 kg heavy. Accordingly, there will be a considerable consumption of 
metallic material. Secondly, the sealing of the heat removal system is 
difficult to be maintained ascribable to a big tube sheet being required 
and a high pressure being maintained. Thirdly, the thickness of the tube 
sheet will be rapidly increased as the diameter of the heat removal vessel 
becomes larger. As a result, the heat exchange area of a single external 
heat removal system is limited to a certain extent. When the released 
thermal energy increases, more than one external heat removal system 
should be provided, which will give rise to the difficulty of 
installation, operation and maintenance. 
(3) U.S. Pat. Nos. 4,438,071 to Vickers et al., 4,439,533 to Lomas et al., 
4,605,636 to Walters et al., 4,716,958 to Walters et al. and 4,757,039 to 
Lomas disclose such a type of external heat removal system that the tube 
sheet chamber is located at the lower end of the external heat removal 
vessel and the nozzle conduits for fluidizing the catalyst are provided 
between the heat removal tubes. In this arrangement, since the heat 
removal tubes are spaced with a little interval, the fluid solid particles 
that are entrained with the air supplied via the nozzle conduits will wear 
and tear the heat exchange tubes. In case something is broken down at the 
heat removal tubes, the external heat remove systems will leak or spatter 
the cooling medium being passed within the tube side. 
(4) In the above mentioned external heat removal systems, the supply water 
is delivered upwardly and the mixture of steam and water flows downwardly. 
However, the local resistance will increase as the vapor bubbles 
accumulate within the downward passage because the vapor bubbles tend to 
float upwardly. The quantity of water to be passed through and evaporated 
will be importantly reduced so that the evaporation will be aggravated. 
The vicious cycle will occur and the heat exchange tubes will be locally 
overheated and rapidly broken down. The irregularity usually occurs in the 
parallel-arranged tubes. This will result in the hydraulical unreliability 
which becomes more and more important and has been remained unsolved. In 
general, these heat removal system designs and their variational 
embodiments should be avoided. 
(5) U.S. Pat. Nos. 4,353,812 to Lomas et al. and 4,424,192 to Lomas et al., 
describe an external heat removal system comprising a tube plate disposed 
at the upper portion thereof. In this type of external heat removal 
system, the fluidizing gas is supplied via an inlet at the lower portion 
thereof, and passed through the shell side passage and then recycled to 
the upstream regeneration vessel at the upper portion thereof. In order to 
keep an effective height of fluidized bed of solid catalytic particles and 
to prevent a significant portion of the fluid solid catalytic particles 
from being backmixed into the regeneration vessel without being heat 
exchanged or cooled, there should be maintained a predetermined spare 
height called "TDH" (transport disengaging height) above the bed of the 
fluidized solid catalytic particles. Accordingly, the utilization factor 
of heat removal tubes in this type external heat removal system is too low 
to be economically used in, for example, the petrochemical industry. In a 
favorable embodiment, in general, the utilization factor of the heat 
removal tubes disposed within this type of external heat removal system is 
only about 2/3. 
The problem the present invention has been endeavored to solve is to 
provide a heat exchange arrangement of apparatus for the recovery or 
removal of at least a portion of thermal energy from hot fluidizable solid 
particulate material, particularly the regenerated catalytic particles 
exiting the regeneration vessel schemed in an FCC operation for the 
processing of the heavy feedstock. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention is directed to an arrangement of 
apparatus and process for cooling hot fluid solid particulate material, 
for example catalytic particles that are being worldwide employed in the 
petrochemical industry, in particular in a fluid catalytic cracking (FCC) 
for the conversion of the heavy or high molecular weight feedstock or 
straight material into lighter or more desirable low molecular weight 
products. It is particularly concerned with a process and apparatus for 
the cooling or rather removal of a portion of thermal energy from the hot 
fluidizable solid particles, especially the hot heavy oil feedstock 
cracking catalytic particles contaminated with carbonaceous deposits being 
produced in an FCC operation and combusted with an oxygen containing gas 
in upstream zones, which process and apparatus can be reliably brought 
into operation in absence of the aforementioned disadvantages of the prior 
art internal and external heat removal systems. Exactly speaking, the 
process and apparatus according to the present invention may be 
characterized as stated herein after. 
(1) The temperature of the fluidized bed of catalytic particles contained 
in the regeneration vessel can be flexibly, effectively and economically 
controlled by the variation of the opening of a slide valve and the supply 
of a fluidizing gas. The thermal loadage that is removed or exchanged may 
be varied in an extensive range, for example within a range of from 0 to 
100%. The process and apparatus in accordance with the present invention 
may be adapted as a step for the processing of catalytic particles having 
a carbonaceous deposit or coke of from 6.5% to 15% or higher. That is to 
say, the process and apparatus in accordance with the present invention 
may to the greatest extent meet the heat removal or recover requirements 
for the treatment of various feedstock or starting materials that are 
different in chemical nature, composition and quantity thereof to be 
processed. 
(2) The external heat removal system employed for cooling the hot fluid 
solid particulate material and in particular the hot catalytic particles 
in accordance with the present invention, are peculiar in design and 
unique in construction thereof. In fact, it comprises a plurality of heat 
exchange tube units or bundles and a shell. Each of the heat exchange tube 
units comprises a supply water tube, a water collecting chamber, one or 
more elongated heat exchange tubes, a vapor collecting chamber and a vapor 
discharge tube, all of which constitute a separate water-vapor 
circulation. At the inlet and outlet conduits of the circuit are disposed 
valves which may be optionally opened or closed at any time. The supply 
water is transported through the internal or tube side passage of 
individual heat exchange tube units and heat indirectly exchanged with the 
high temperature fluid catalytic particles being passed through the shell 
side passage. The supply water absorbs the thermal energy and evaporizes, 
thereby forming the mixture of steam/water which is then discharged into 
the steam drum per the vapor discharge tube. At the same time, the hot 
catalytic fluid-like particles flow downwardly in the form of a dense 
phase fluidized bed and is gradually cooled. 
(3) The external fluid solid particles especially catalytic particles heat 
removal arrangement in accordance with the present invention is 
essentially composed of individual or separate heat exchange tube units. 
In case any breakdown or leakage or spattering occurs at any tube or any 
portion thereof the operation of the heat exchange tube unit that is 
concerned with is then stopped and the normal performance of other heat 
exchange tube units are by no means affected. The normally operative 
reliability and feasibility or flexibility of the external heat removal 
apparatus and process as a whole operation in accordance with the present 
invention are substantially increased so that the desired fluid catalytic 
cracking (FCC) operation will undoubtedly become more effective and 
stable. Accordingly, this type of arrangement of external fluid solid 
particulates heat exchange system is surprisingly novel and non-obvious. 
(4) The external fluid solid particles heat removal process and apparatus 
in accordance with the present invention are performed in the form of 
dense phase fluidization wherein by the term "dense phase" as used herein 
is meant that the mixture of hot catalytic particles and the fluidizing 
gas has a density of from 100 to 600 kg/m.sup.3. The apparent velocity 
that is attainable in the dense phase fluidized bed of hot catalytic 
particles ranges from 0.1 m/s to 1.0 m/s and the heat exchange performance 
will be excellent. The overall heat transfer coefficient will be up to 550 
W/ m.sup.2. K. In other words, these heat exchange performance results 
that may be obtained in a normal FCC operation using the arrangement of 
apparatus in accordance with the present invention as cooling means of the 
regenerated catalyst are much better than those of the conventional FCC 
operations. 
(5) The external heat removal apparatus of the present invention is 
operated under conditions such that the hot regenerated and substantially 
carbonaceous deposits free catalytic fluid-like particles flow downwardly 
in the form of dense phase fluidized bed wherein the rate of flow of the 
fluid solid particulates, especially the FCC catalytic particles and the 
apparent velocity of the gas are very low so that the attrition that the 
fluid solid particles causes upon the heat removal tubes could be 
minimized. This will result in a service life that is substantially longer 
than those of the aforementioned conventional FCC arrangements. 
(6) The supply water and the resulting vapor collecting chambers provided 
at the uppermost and lowermost ends of heat exchange tube units extending 
through the external heat removal vessel according to the present 
invention are in the form of collecting cylinder conduits which provide 
the ability to thoroughly utilize the advantages shown by the fact that 
the cylindrical conduit shell has an excellent pressure resistance, 
thereby avoiding the problematic manufacture and sealing of plane 
tubeplate construction. In one embodiment, the vapor discharge tubes 
associated with individual heat exchange tube units are directly suspended 
from the top in a manner such that the vapor discharge tubes serve at the 
same time as the suspension supports of individual heat exchange tube 
units or bundles. That is to say, the vapor discharge tubes have double 
functions. Since this type of construction is properly arranged, the 
consumption of the construction materials, in particular metallic material 
used for the manufacture of the external heat removal vessel and its 
associates in accordance with the present invention will be remarkably 
reduced, for example by approximately 30%, on the basis of the above 
mentioned U.S. patents. 
The other objects and advantages of the present invention will become 
apparent from the following description and illustrative representation of 
non-limitative embodiments with reference to the attached drawings, all of 
which encompass the details for the carrying out of the present invention.

DETAILED DESCRIPTION OF THE INVENTION 
In one aspect, the present invention provides an arrangement of apparatus 
for the removal of a portion of thermal energy from hot fluid solid 
particles, especially the fluid solid catalytic particles upon which have 
been surface-deposited deactiating carbonaceous materials when used in a 
fluid catalytic cracking (FCC) operation and then regenerated in a 
regeneration vessel by the combustion of carbonaceous deposits with an 
oxygen containing gas, said apparatus comprising in combination: 
a. a substantially vertical cylindrical external heat remove vessel, 
b. one or more individual or separate heat exchange tube units being housed 
in said cylindrical heat removal vessel, each of said heat exchange tube 
units comprising a supply water inlet tube, a supply water collecting 
chamber, one or more heat removal tubes, a steam collecting chamber and a 
steam discharge tube, 
c. valves provided at the supply coolant or heat exchange medium, for 
example water inlet and steam discharge outlet conduits, said valves being 
optionally opened or closed at any time, 
d. hot fluid solid particles, in particular catalytic particles inlet and 
outlet conduits being provided at the upper and lower portion of said heat 
removal vessel respectively and equipped with valves which function to 
control the thermal loadage of the external heat removal system within a 
range of from 0% to 100%. 
e. means for the introduction and distribution of a fluidizing gas into the 
hot fluid solid particles bed, said means being located at the lower 
portion of said heat removal vessel, and 
f. a fluidizing gas discharge outlet conduit being located at the upper 
portion of the external heat removal vessel. 
In another aspect, the present invention provides a process for the removal 
of a portion of thermal energy from hot fluid solid particles, in 
particular the fluid solid catalytic particles upon which have been 
surface-deposited deactivating carbonaceous materials when used in a fluid 
catalytic cracking (FCC) operation and then regenerated in a regeneration 
vessel by the combustion of carbonaceous deposits or coke with an oxygen 
containing gas, said process comprising the steps of: 
a. introducing into an external heat removal vessel via an inlet conduit at 
the upper portion of said vessel hot fluid solid particles, in particular 
the hot catalytic particles from a dense phase bed of said particles that 
have been regenerated in a regeneration vessel by the combustion of 
carbonaceous deposits or coke accumulating on the surface thereof, and 
then discharging the same via an outlet conduit at the lower portion of 
said vessel, said inlet and outlet conduits being provided with valves 
which serve as controlling the thermal loadage of the external heat 
removal vessel within a range of 0% to 100%. 
b. introducing a fluidizing gas into said heat removal vessel via a gas 
inlet conduit at the lower portion of said vessel, thereby forming a dense 
phase fluidized bed of said catalytic particles fluid-like flowing 
downwardly, and then discharging the catalytic particles via an outlet 
conduit at the lower portion of said vessel, and 
c. introducing the supply water into said external heat removal vessel via 
an inlet conduit provided with a valve at the upper portion of said 
vessel, and then discharging the steam formed by indirect heat exchange of 
said water with the hot particles downwardly flowing in the form of dense 
phase along one or more separated heat exchange tube units which are 
substantially vertically suspended from the top and embedded in a dense 
phase fluidized bed of said hot particles. 
The external heat removal apparatus and process thereof in accordance with 
the present invention may utilize as many external heat removal tube units 
or bundles independent of one another as required for the maintenance of 
thermal equilibrium or a constant operation temperature in the 
catalysis-regeneration cycle of the fluid catalytic cracking (FCC) 
catalyst. Therefore, the apparatus and process thereof are particularly 
adequate to an FCC operation. In a preferred embodiment of the present 
invention, the high temperature regenerated catalytic particles are 
introduced through an opening at the upper portion of the external heat 
removal vessel and fluid-like flow downwardly through the shell side 
passage of said vessel in the form of fluidized dense phase bed which is 
caused by a fluidizing gas introduced through an opening at the lower 
portion of said vessel. These particles are cooled and then discharged 
through an opening at the lower portion of the external heat removal 
vessel. The catalytic particles inlet and outlet conduits are provided 
with slide valves which function to control the thermal loadage of the 
external heat removal system within a range of from 0% to 100%. The heat 
exchange medium or coolant, preferably water is passed through the tube 
side passage of as many heat exchange tube units as the heat removal load 
requires and at the same time the supply water is vaporized into steam 
during the absorption of a portion of thermal energy from the hot 
regenerated catalytic particles by indirect heat exchange therewith. The 
formed steam is discharged through an outlet tube associated with the 
various heat exchange tube units. 
Reference is now made to the attached drawings representing a preferred 
illustrative embodiment of the present invention. In FIG. 1 is shown a 
specifically preferential mode of the present invention wherein the hot 
regenerated catalytic particles are cooled. This type of arrangement shown 
in accordance with the present invention comprises a shell (6), one or 
more heat exchange tube units and means for the introduction and 
distribution of a fluidizing gas. Apart from the unique heat exchange tube 
units of the present invention and their associations, other parts may be 
in the conventional forms or provided by the modifications thereof which 
will be apparent to those skilled in the art. The number of heat exchange 
tube units to be employed depends on the quantity of thermal energy to be 
removed or recovered from the hot regenerated catalytic particles. 
Each unitary heat exchange tube bundle or heat removal unit comprises a 
supply water inlet tube (1), a water collecting chamber or cylinder 
conduit (2), a central casing heat removal tube (4-2) and one or more 
sideline heat removal tubes (4-1), a steam collecting chamber or cylinder 
conduit (3) and a steam discharge tube (5), all of which constitute a 
water-to-steam circulation. These heat exchange tube units may be 
optionally brought into operation or closed by means of the valves located 
at the supply water inlet tubes. The shell (6) is made of, for example, 
steel, closed-ended at the top and bottom and lined with an 
erosion-resistant refractory and insulating refractory on its interior 
surface. On this shell are also provided the hot catalytic particles inlet 
and outlet openings or conduits (7, 8) and the fluidizing gas inlet and 
outlet openings or conduits (11, 12). In order to maintain a substantially 
constant circulating flow rate of the water/steam mixture in the various 
sideline heat removal tubes of each heat removal unit, the ratio of 
effective flow cross-sectional area Al of a sideline heat remove tube 
(4-1) to effective flow circular and cross-sectional area A2 of a central 
casing heat exchange tube (4-2) should be appropriately selected so that 
the ratio A1/A2 ranges from about 0.5 to 1.5. Every heat removal tube unit 
is fixed to the top (10) of shell (6) using a self-supporting construction 
of a vertical water-cooled wall. The steam discharge tubes are securely 
weld-fixed to the uppermost portion of the top (10) of the external heat 
removal vessel. In this preferred arrangement, the steam discharge tube 
serves as a portion of heat removal unit and at the same time as a 
supporting means. At an appropriate position of the cylindrical vessel are 
welded some fixing means or guiding spacers (9) of any suitable forms for 
limiting any transverse displacement that may occur in a heat exchange 
operation. A fluidizing gas distributor means (13) is located at an 
appropriate level of the lower portion of said vessel, said level being 
able to be conventionally determined by those skilled in the art. 
As shown in the attached FIGS. 1-5, the high temperature catalytic 
particles flow downwardly in the form of a fluidized dense phase bed that 
is formed by means of a fluidizing gas being upwardly passed through the 
shell side passage of said external heat exchange vessel. The supply water 
is passed downwardly through an inlet tube (1) into the water collecting 
chamber (2) and then flows upwardly through the heat removal tubes (4-1) 
and (4-2). At the same time, the supply water is transformed into the 
collecting cylinder conduit chamber (3) in the form of steam. The 
resulting steam is discharged from the chamber (3) via a discharge tube 
(5). Up to this moment, all the heat removal operation becomes terminated. 
The fluidizing gas, which may be air or any other suitable gases, 
preferably air, is introduced via the inlet opening (11) and enters the 
external heat removal vessel after being distributed through the 
fluidizing gas distributor means (13). The solid catalytic particles are 
fluidized in the form of dense phase by this fluidizing gas which is then 
discharged via an outlet conduit (12) disposed at the upper portion of the 
external heat removal vessel. The so-called dense phase is apparent to 
those skilled in the art. 
It is now contemplated that the present invention is particularly utilized 
in combination with a catalyst regeneration vessel in a fluid catalytic 
cracking (FCC) operation of heavy straight feedstocks. The cracking 
reaction vessel, for example a riser type reactor is operated at a 
pressure in a range of from about 0.08 MPa to about 0.35 MPa and a 
temperature in a range of from about 450.degree. C. to about 550.degree. 
C. The quantity of carbonaceous deposits or coke formed on the surface of 
the catalytic particles during the cracking reactions ranges from about 
6.5% to about 15%. The downstream regeneration vessel remotely connected 
with the reaction vessel is operated at a pressure in a range of from 
about 0.08 MPa to about 0.35 MPa, a temperature of the dense phase 
fluidized bed of catalytic particles in a range of from about 650.degree. 
C. about 760.degree. C. and a density of the dense phase fluidized bed of 
catalytic particles in a range of from about 200 kg/m.sup.3 to 600 
kg/m.sup. 3. The still downstream external heat removal apparatus also 
remotely connected with the regeneration vessel is operated at a pressure 
of shell side passage thereof in a range of from about 0.2 MPa to about 
0.5 MPa, a temperature of shell side passage thereof in a range of from 
about 500.degree. C. to about 750.degree. C. and a density of the mixture 
of catalytic particles/fluidizing gas being downwardly passed through the 
shell side passage thereof in a range of from about 200 kg/m.sup.3 to 600 
kg/m.sup.3. The apparent velocity of the fluidizing gas being passed 
through the shell side passage of the external heat removal apparatus 
ranges from about 0.1 m/s to about 1.0 m/s. The inlet temperature of hot 
catalytic particles being introduced from the catalyst regeneration vessel 
into the external heat removal vessel ranges from about 500.degree. to 
about 750.degree. C. The outlet temperature of cooled catalytic particles 
ranges from about 460.degree. to about 700.degree. C. The steam formed by 
the evaporization of the supply water ranges from about 0.6 MPa to about 
4.2 MPa. 
ILLUSTRATIVE EMBODIMENT OF THE INVENTION 
The following shows a typically preferred embodiment of the present 
invention which is employed in an FCC operation for the external remove of 
thermal energy from the regeneration vessel. The heat removal arrangement 
of apparatus is essentially shown in the attached FIGS. 1-5. The operating 
parameters prevailing in the illustrative embodiment specifically 
representing the external heat removal apparatus and process thereof of 
the present invention are listed below. 
______________________________________ 
Thermal Loadage, W 2700 .times. 10.sup.4 
Inlet temperature of Catalyst, .degree.C. 
750 
Outlet Temperature of Catalyst, .degree.C. 
650 
Apparent Velocity of Fluidizing Gas, m/s 
0.4 
Pressure of Shell Side Passage, MPa 
0.33 
Density of Fluidized Bed, kg/m.sup.3 
400 
Pressure of Steam, MPa 4.2 
Overall Heat Transfer Coefficient, W/m.sup.2.K 
370 
Area of Heat Transfer, m.sup.2 
170 
Number of Tube Units 22 
Area of a Tube Unit, m.sup.2 
7.7 
Length of Heat Remove Tube, m 
6 
______________________________________ 
As described hereinbefore, the external heat remove apparatus and process 
thereof having an excellent heat removal capacity in accordance with the 
present invention can be utilized to effectively, stably and flexibly 
control the operation temperature of fluid catalytic cracking (FCC) 
effected with heavy feedstock. Due to the use of a plurality of separate 
heat exchange tube units each of which may be optionally opened and closed 
at any time, the apparatus and process thereof in accordance with the 
present invention can be flexibly regulated according to the requirements 
of different thermal energy removal loads. The attrition upon the heat 
exchange means and the service life of operation can be substantially 
improved since the fluid solid particles slowly flow downwardly through 
the shell side passage of the external heat removal arrangement in the 
form of dense phase fluidized bed in accordance with the present 
invention. The high pressure resistance of the unitary heat exchange tubes 
and the application of self-supporting construction of water-cooled wall 
as the supporting means thereof result in the economy of the metallic 
materials and manufacture costs. 
It should be understood that the above provided general description and 
illustrative exemplification of the present invention would not constitute 
any limitation to the present invention in its broadest sense. In fact, 
the present invention could be adapted to cool any type fluid solid 
particles with some modifications which are of course within the extent of 
protection defined herein below.