HYDROCARBON PRODUCTION"

TECHNICAL FIELD

[001] The present disclosure relates to refinery process including but not limited to cracking process and coking process for production of hydrocarbons. More particularly, the present disclosure relates to the refinery processes under a condition including but not limited to adiabatic condition and pseudo adiabatic condition, wherein the process provides reduction in amount of coke formed during the processes, by employing an additive comprising a catalyst, or a carrier, or a combination thereof. The present disclosure also relates to the additive per se, and accordingly the use of such an additive for reducing coke formed during processes employed for production of hydrocarbons.

BACKGROUND

[002] Thermal cracking processes maximizing the conversion of very heavy, low-value hydrocarbon/residuum feeds to produce high value hydrocarbon products/distillates and petroleum coke are known from a long time. 'Coking' is a refinery unit operation that upgrades material called bottoms from the atmospheric or vacuum distillation column into higher-value products. Two types of coking processes exist: delayed coking and fluid coking. Both are chemical processes that occur at pressures slightly higher than atmospheric and at temperatures greater than 900°F that thermally crack the feedstock into products (distillates), leaving behind the lowest valued product of refinery, petroleum coke. Standard Oil Company, Whiting Indiana started the first commercial delayed coker unit in 1929. In delayed coking process, about 20-40% of hydrocarbon residue is converted into petroleum coke. Therefore, such high coke yield reduces the profit of delayed coker. To maximize the operating profits, refiners try to manipulate the operating conditions, thus trying to minimize the coke yield. Further, seeking an improvement in vacuum residue quality by selecting better crude oils is not an economical route to reduce coke yield since good quality crude oils are very expensive. Over the past few decades, the residue content of crude oils has increased significantly which has further increased the need for efficient coking processes.

[003] US4169041 A teaches a coking process wherein use of metallic hydrogenation catalysts such as molybdenum, chromium and vanadium has shown to increase the distillate yield. [004] US4358366A teaches the use of hydrogen transfer, hydrogenation and hydrotreating catalyst along with hydrogen gas in delayed coking of shale oil and vacuum residue to increase distillate yield.

[005] US4394250A teaches use of cracking catalyst and hydrogen to improve distillate yield and reduce coke make in delayed coke.

[006] In all the above mentioned prior arts, the catalyst additive is added to the hydrocarbon residue along with the feed before entering the coke furnace. The catalyst comes in contact with the heavy hydrocarbon molecules in liquid state wherein the probability of deactivation of catalyst active sites due to pore blocking and coke deposition is very high.

[007] Therefore, there is a need for developing an improved thermal coking process which can significantly and effectively reduce coke yield thereby increasing the production of desired high-value distillates.

SUMMARY OF THE DISCLOSURE

[008] The present disclosure relates to the thermal coking process for reducing coke yield under condition including but not limited to adiabatic condition and pseudo adiabatic condition. Said reduction in coke yield results in an increase in the yield of high-value products including but not limiting to distillate(s).

[009] In an embodiment, the present disclosure relates to the thermal coking process under adiabatic condition involving catalytic cracking of feed comprising hydrocarbon based compounds in presence of additive including but not limited to a combination of catalyst and carrier, wherein said process leads to a decrease in coke yield.

[010] In another embodiment, the present disclosure relates to thermal coking process under pseudo adiabatic condition involving catalytic cracking of feed comprising hydrocarbon based compounds in the presence of additive including but not limited to a combination of catalyst and carrier, wherein said process leads to a decrease in coke yield.

[011] In an exemplary embodiment of the present disclosure, the process for reducing coke yield and increasing distillate yield comprises act of contacting the feed comprising hydrocarbon based compounds with additive comprising catalyst and carrier, wherein about 50% to about 90% of the carrier within the additive is evaporated before the additive reaches the vapour liquid interphase.

[012] In some embodiments, the additive comprising catalyst and carrier for coking process is injected into coke drum from top of a coker unit. [013] In an alternate embodiment of the present disclosure, there is provided a nozzle for injecting additive at a predetermined droplet size ranging from about 1 mm to about 10 mm, into the coke drum. The nozzle comprises an inlet which is fluidly connected to a system for receiving the additive, and an outlet for injecting the additive into the coke drum. Further, the outlet of the nozzle is housed inside the coke drum, and the outlet is configured with a plurality of openings for injecting additive into the coke drum at the predetermined droplet size.

BRIEF DESCRIPTION OF ACCOMPANYING FIGURES

[014] In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with a description below are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure where:

[015] FIGURE 1 depicts the experimental setup for carrying out coking process in commercial delayed coker unit (commercial DCU).

[016] FIGURE 2 depicts the process flow diagram of delayed coke pilot plant.

[017] FIGURE 3 : Figures 3a and 3b depict the Nozzle design used in the present disclosure.

[018] FIGURE 4: illustrates the vaporization curves of carriers having a droplet size of about 10mm at different distance from top of the coke drum.

[019] FIGURE 5 : illustrates the vaporization curves of carriers having a droplet size of about 6mm at different distance from top of the coke drum.

[020] FIGURE 6: illustrates the temperature of the vapour liquid interphase upon injection of additive having different carriers, wherein the droplet size of the additive is about 10mm.

[021] FIGURE 7: illustrates the temperature of the vapour liquid interphase upon injection of additive having different carriers, wherein the droplet size of the additive is about 6.25mm.

DETAILED DESCRIPTION

[022] The present disclosure relates to refinery process including but not limited to petroleum refining process such as cracking process and coking process for reducing coke formation and increasing yield of high value products such as distillate yield.

[023] In a non-limiting embodiment, the present disclosure relates to an improved cracking process and coking process under condition including but not limited to pseudo adiabatic condition and adiabatic condition, which results in increased distillate yield or yield of hydrocarbon based compounds and reduces the amount of coke formed (yield) during said process, wherein the distillates or hydrocarbon based compounds are hydrocarbon gases, naphtha, kerosene, gas oil and heavy gas oil. The increment in the total distillate (Gases and liquid products) yield in the instant disclosure is about 0.5wt% to about 2wt% when compared to distillate yield obtained in the conventional processes As used in the present disclosure, the term 'Adiabatic condition' refers to a thermodynamic process in which there is no heat transfer into or out of the system. In other words, under adiabatic condition, no significant heat transfer takes place between a system and its surroundings. In an embodiment of the present disclosure, 'adiabatic condition' is opposite to 'isothermal condition' and refers to the change/variation in temperature during the coking process without applying or removing heat. In another embodiment, the term 'adiabatic condition' includes complete adiabatic conditions or at or near adiabatic conditions. Further, pseudo-adiabatic condition refers to heat energy being supplied to a system at a fixed rate.

[024] In a non-limiting embodiment, the present disclosure relates to a process for reducing coke yield in refinery process such as cracking process and coking process under condition including but not limiting to adiabatic condition and pseudo adiabatic condition wherein, said processes employs an additive.

[025] In another non-limiting embodiment of the present disclosure, the additive employed in the process of the present disclosure includes but is not limited to catalyst and carrier, or a combination thereof.

[026] Accordingly, the present disclosure relates to an improved process for hydrocarbon processing, such as cracking and/or coking process, wherein the process employs a specific additive to reduce the amount of coke formed during the process. The process employing such an additive provides for an improved yield of the desired product such as distillate formed. In addition to the process, the present disclosure also relates to the additive itself, which comprises a preferred combination of catalyst and carrier. Such an additive is employed in the conventional processes of hydrocarbon processing including but not limited to cracking and coking, thereby making the processes more efficient, and providing the processes of the present disclosure. The additive of the present disclosure is employed within a reactor including but not limited to coker unit such as delayed coker unit, fluid coker unit and flexicoker unit, where processes including but not limiting to cracking and coking conventionally occur. Although the present disclosure exemplifies utility of the additive of the present disclosure inside a coker unit during the process of coking, a person of ordinary skill in the art will understand that the additive of the present disclosure is capable of being employed in any process where the amount of coke produced or yield of coke is needed to be reduced.

[027] In a non-limiting embodiment of the present disclosure, the catalyst within the additive employed in the process of the present disclosure includes any chemical element(s) or chemical compound(s) that reduces the energy of activation for the desired reactions in the refinery process such as cracking process and coking process towards feed and intermediate chemical species of the process. The catalyst is designed to preferably favour certain cracking reactions and/or provide selectivity for the cracking of specific types of hydrocarbon reactants (e.g. feed, intermediate and/or vapor products). Furthermore, the catalyst is designed to preferably favour certain coking reactions in the coking process and/or provide selectivity for the coking of specific types of hydrocarbon reactants. Alternatively, the catalyst is designed to selectively convert any heavy component (i.e. liquid, semi-liquid, or solid) of the coking process feed that tend to cause "hot spots" in the coke and 'blowouts' in decoking operations. In addition, the catalyst is designed to preferentially act in conditions including but not limiting to pseudo adiabatic reaction condition and adiabatic reaction condition, wherein the temperature of the reactor does not remain constant during catalytic cracking or coking process in the adiabatic reaction condition, and whereas in the pseudo- adiabatic condition, the heat is supplied to the reaction at a fixed rate.

[028] The catalyst employed within the additive of the present disclosure is formulated to participate in and/or enhance any one or more types of chemical reactions including but not limited to, cracking reactions, coking reactions, pyrolysis reactions, hydrogenation reactions, hydrogenolysis reactions, hydrolysis reactions, addition reactions, dehydrogenation reactions, aromatization reactions, oligomerisation reactions, isomerization reactions, or any combination thereof. In another embodiment of the present disclosure, the catalyst includes but is not limited to a material having acidic properties.

[029] In a preferred embodiment of the present disclosure, the catalyst includes but is not limited to a material which has catalytic activity for hydrocarbon cracking at a temperature ranging from about 350°C to about 500°C. In a more preferred embodiment, the catalyst includes but is not limited to alumino silicate zeolite, zeolite Y, acidic clay and ZSM-5 zeolite, wherein the catalyst is fluid catalytic cracking (FCC) catalyst. In an exemplary embodiment, the catalyst is a spent FCC catalyst.

[030] In a non-limiting embodiment, the carrier within the additive employed in the process of the present disclosure includes but is not limited to a fluid. In an exemplary embodiment, the carrier includes but is not limited to liquid, gas, hydrocarbon vapor, or any combination thereof. In another exemplary embodiment, the carrier includes a fluid such as gas oils or lighter liquid process streams.

[031] In a preferred embodiment, the carrier is devoid of coke precursors.

[032] In another preferred embodiment of the present disclosure, the carrier is a liquid medium having a final boiling point ranging from about 40°C to about 200°C.

[033] In a non-limiting embodiment of the present disclosure, the carrier includes but is not limited to, fluidized catalytic cracking unit (FCCU) oils, decanted fluidized catalytic cracking unit (FCCU) oils, fluidized catalytic cracking unit (FCCU) cycle oils, gas oils, other hydrocarbon(s), other oil(s), inorganic liquids, water, steam, nitrogen, hydrogen, or any combination thereof. In a preferred embodiment, the carrier includes but is not limited to straight run naphtha, unstabilized naphtha, FCC naphtha, heavy coke naphtha (HCN) and light coke naphtha (LCN).

[034] In an exemplary embodiment of the present disclosure, the carrier is a 'hydrocarbon stream' having final boiling point ranging from about 40°C to about 200°C and is devoid of coke precursors including but not limiting to polycyclic aromatic hydrocarbons and Conradson Carbon Residue (CCR).

[035] In another embodiment, the present disclosure illustrates reduction of heat demand inside a reactor including but not limited to coker unit such as delayed coker unit, fluid coker unit and flexicoker unit upon addition of additive comprising catalyst and carrier during the process of cracking or coking in a refinery. Alternatively, reduction of heat demand inside coke drum of the reactor also is observed.

[036] In an exemplary embodiment of the present disclosure, the process for reducing coke formation during refinery process such as cracking process and coking process comprises act of contacting feed with additive comprising catalyst and carrier, wherein about 50% to about 90% of the carrier within the additive is evaporated before the additive reaches vapour liquid interphase in a reactor including but not limiting to coker unit.

[037] In a non-limiting embodiment, the feed is a hydrocarbon residue selected from a group comprising vacuum residue, heavy coker gas oil, atmospheric residue, pitch form solvent deasphalting, sludge from effluent treatment plant, heavy fuel and clarified slurry oil, or any combination thereof.

[038] In a non-limiting embodiment, in the process of present disclosure, the carrier within the additive is devoid of coke precursor including but not limited to polycyclic aromatic hydrocarbons and Conradson Carbon Residue (CCR). Further the carrier has a final true boiling point ranging from about 40°C to about 200°C. [039] In another non-limiting embodiment, in the process of present disclosure, the carrier within the additive is at a concentration ranging from about 50% to about 98%. In a preferred embodiment, the carrier within the additive is at a concentration ranging from about 50% to about 80%.

[040] In yet another non-limiting embodiment, in the process of present disclosure, the catalyst within the additive is at a concentration ranging from about 2wt% to about 50wt%, preferably ranging from about 10wt% to about 50wt% and more preferably ranging from about 20wt% to about 50wt%.

[041] In still another non-limiting embodiment, in the process of present disclosure, the additive comprising catalyst and carrier is having a droplet size ranging from about 1mm to about 10mm. The said droplet size of the additive ranging from about 1mm to about 10mm is achieved by passing the additive through a nozzle having about 6 to about 9 slots, each having a diameter of about 1 ^χ 1/2 centimeters.

[042] In an alternate embodiment, in the process of present disclosure, the additive comprising catalyst and carrier is having an average droplet size ranging from about 1mm to about 10mm.

[043] In still another non-limiting embodiment, in the process of present disclosure, the feed includes but is not limited to residual oil from vacuum distillation column or atmospheric distillation column. Long chain hydrocarbon molecules are the constituents of said residual oil feed. In an embodiment, any conventionally known feed stock comprising hydrocarbons can be employed in the process of the present disclosure.

[044] In an exemplary embodiment, in the process of present disclosure, the carrier alongside the catalyst within the additive prevents vapour liquid interphase temperature shift during the refinery process including but not limited to cracking process and coking process, thereby leading to reduction in coke yield and increase in distillate yield. The prevention of the vapour liquid interphase temperature shift in the process of present disclosure is achieved by-

(i) employing a carrier having a final true boiling point ranging from about 40 °C to about 200°C and wherein the carrier is devoid of coke precursor;

(ii) employing the carrier at a concentration ranging from about 50% to about 98% with respect to the total amount of additive. In a preferred embodiment, the concentration of carrier in the additive is ranging from about 50% to about 80%;

(iii) evaporation of about 50% to about 90% of the carrier within the additive before the additive reaches vapour liquid interphase; (iv) employing additive having a droplet size ranging from about 1 mm to about 10 mm.

[045] In an embodiment, in the process of the present disclosure, a pseudo-adiabatic condition is provided, wherein the heat input to the reactor is fixed for all experiments so that the effect of any extra heat demand during refinery process including but not limited to cracking process and coking process due to injection of additive can be measured. Addition of the additive comprising catalyst and carrier in the pseudo-adiabatic condition prevents vapour liquid interphase temperature shift, resulting in significant reduction in coke yield and increase in distillate yield.

[046] In an alternate embodiment, in the process of the present disclosure, an adiabatic condition is provided, wherein there is no heat transfer and there is a change/variation in the temperature during the refinery process including but not limiting to cracking process and coking process without applying or removing heat. However, injection of the additive comprising catalyst and carrier prevents vapour liquid interphase temperature shift during the process and thereby results in significant reduction in coke yield and increase in distillate yield.

[047] In a preferred embodiment of the present disclosure, the refinery process including but limited to cracking process and coking process is carried out in a coker unit, preferably delayed coker unit (DCU) including but not limiting to lab-scale or bench-scale delayed coker unit, pilot delayed coker unit and commercial delayed coker unit, wherein the delayed coker unit comprises catalyst tank, tank, educator, nozzle and coke drum In a non-limiting embodiment, the experimental set-up of a commercial delayed coker unit of the present disclosure is depicted in Figure 1.

[048] In an exemplary embodiment of the present disclosure, the additive comprising catalyst and carrier is injected from top of the coker unit. In other exemplary embodiments as described above, the carrier has a final true boiling point ranging from about 40°C to about 200°C and is devoid of any coke precursor. Further, the carrier is at a concentration ranging from about 50% to about 98%, and the process ensures that about 50% to about 90% evaporation of the carrier is achieved before the additive reaches vapour liquid interphase in the coke drum. In a non-limiting embodiment, employing the above said conditions negates the quenching effect and subsequently prevents vapor liquid interphase temperature shift and thereby, reduction in coke yield and increase in distillate yield is achieved.

[049] In another exemplary embodiment, the coker unit employed for performing the process with the additive of the present disclosure for reducing coke yield and increasing distillate yield is set under a condition including but not limiting to adiabatic condition and pseudo-adiabatic condition.

[050] In a non-limiting embodiment, the reduction of coke yield achieved by the process of the present disclosure is ranging from about 0.5 wt% to about 2.0wt% of total feed.

[051] In another non-limiting embodiment, increase in distillate yield achieved by the process of the present disclosure is ranging from about 0.5wt% to about 2.0wt% of the total feed when compared to the distillate yield obtained by the conventional process.

[052] In the present disclosure, the reduction in the production (yield) of coke ranging from about 0.5 wt% to about 2.0wt% during refinery process such as coking process and cracking process is with respect to the conventional process of cracking or coking, whereby the catalyst or carrier is employed individually. In other words, the present disclosure reduces the yield of coke when compared to any conventional process that does not employ the additive of the present disclosure, viz. catalyst and carrier in combination.

[053] In a non-limiting embodiment, the process of the instant disclosure prevents the vapour liquid interphase temperature shift of more than 10 °C inside the reactor, such as coke drum, preferably preventing the vapour liquid interphase temperature shift of more than 5°C and more preferably preventing the vapour liquid interphase temperature shift of more than PC.

[054] In an alternative embodiment of the present disclosure, the additive is in a form including but not limiting to slurry. In a preferred embodiment of the present disclosure, the additive comprises dry solid catalyst in a carrier, wherein the carrier is a fluid. In an exemplary embodiment, the additive includes a catalyst having catalytic activity for hydrocarbon cracking at a temperature ranging from about 350°C to about 500°C, and a carrier having a true final boiling point ranging from about 40°C to about 200°C and devoid of coke precursor(s).

[055] In a non-limiting embodiment of the present disclosure, concentration of the carrier in the additive ranges from about 50 wt% to about 98 wt%, preferably less than about 80 wt%. In another non-limiting embodiment, concentration of the catalyst in the additive ranges from about 2 wt% to about 50 wt%, preferably ranges from about 10 wt% to about 50 wt%, and more preferably ranges from about 20 wt% to about 50 wt%.

[056] In an exemplary embodiment of the present disclosure, the process for reducing coke yield under condition including but not limiting to adiabatic condition and pseudo-adiabatic condition comprises injection of additive comprising catalyst and carrier into the reactor, preferably the coke drum whereby quenching effect of the carrier within the additive is negated. Subsequently vapour liquid interphase temperature shift is prevented due to said introduction of additive comprising catalyst and carrier, thereby leading to a reduction in coke yield and increase in distillate yield, wherein the coke yield is reduced in the range of about 0.5wt% to about 2.0wt% and increment in the distillate yield is in the range of about 0.5wt% to about 2.0wt%.

[057] In an alternate embodiment of the present disclosure, the refinery process including but not limited to cracking process and coking process for reducing coke formation comprises steps of:

a) heating feed comprising hydrocarbon residue to a temperature ranging from about 450°C to about 500°C;

b) injecting the feed, followed by injecting additive comprising catalyst and carrier, wherein the additive has a droplet size ranging from about 1mm to about 10mm; c) allowing evaporation of carrier within the additive to a range of about 50% to about 90%, before said additive reaches the feed or vapour liquid interphase; and

d) allowing chemical reaction to occur for a duration of about 2hours to about 10 hours, for production of desired products along with a reduction in coke yield, compared to any process where such an additive is not employed.

[058] In a preferred embodiment of the present disclosure, the refinery process including but not limited to cracking process and coking process for reducing coke formation comprises steps of:

a) heating feed comprising hydrocarbon residue in a furnace to a temperature ranging from about 450°C to about 500°C;

b) injecting the feed of step a) into coke drum for a duration of about 12 hours, wherein the coke drum is maintained at pressure ranging from about 2kg/cm ² to about 4kg/cm ² ; injecting an additive comprising catalyst and carrier into the coke drum for a duration of about 9 hours through a nozzle having about 6 to about 9 slots of 1 X ½" diameter, so that the droplet size of the additive is ranging from about 1 mm to about 10 mm, wherein the additive is injected after about lhour of injection of the feed into the coke drum;

c) allowing about 50% to about 90% evaporation of carrier from the additive before the additive reaches vapour liquid interphase, wherein true boiling point of the carrier is ranging from about 40°C to about 200°C; and

d) allowing chemical reaction between the feed and additive having about 0.01% to about 10%) carrier to occur in the coke drum for a duration of about 2hours to about lOhours, wherein coke formation is reduced in the coke drum when compared to any process where such an additive is not employed.

[059] In an alternate preferred embodiment of the present disclosure, the refinery process including but not limited to cracking process and coking process for reducing coke formation comprises steps of:

a) injecting feed comprising hydrocarbon residue into coke drum for a duration of about 12hours, wherein the feed is at a temperature ranging from about 450°C to about 500°C and wherein the coke drum is maintained at pressure ranging from about 2kg/cm ² to about 4kg/cm ² ;

b) injecting an additive comprising catalyst and carrier into the coke drum for a duration of about 9 hrs through a nozzle having about 6 to about 9 slots of 1 X ½" diameter, so that the droplet size of the additive is ranging from about 1mm to about 10mm, wherein the additive is injected after about lhour of injection of the feed into the coke drum;

c) allowing about 50% to about 90% evaporation of carrier from the additive before the additive reaches vapour liquid interphase, wherein true boiling point of the carrier is ranging from about 40°C to about 200°C; and

d) allowing chemical reaction between the feed and additive having about 0.01% to about 10%) carrier to occur in the coke drum for a duration of about 2 hours to about 10 hours, wherein coke formation is reduced in the coke drum when compared to any process where such an additive is not employed.

[060] In a non-limiting embodiment, the duration of additive injection is based on the coke drum cycle (time required to fill the coke drum). For instance, for a coke drum cycle of about 12 hours the additive injection is started after about 1 hour of feed injection to the coke drum and stopped at least one hour before feed cut-off to the coke drum. Therefore the total duration of additive injection is about 10 hours. For instance, the drum cycle is about 16 hours then the additive injection is carried for about 14 hours. In exemplary embodiment, the duration of the additive injection is about 2hours lesser than the coke drum cycle.

[061] In an embodiment, in the process of the present disclosure, the carrier is at a concentration ranging from about 50 wt%> to about 98 wt%; has a final true boiling point ranging from about 40°C to about 200°C; and is devoid of any coke precursor.

[062] In another embodiment, in the process of present disclosure, evaporation of about 50% to about 90%) of the carrier within the additive avoids undesirable quenching of vapour liquid interphase temperature inside the coke drum. In another embodiment, in the process of present disclosure, the catalyst is at a concentration ranging from about 2wt% to about 50wt% in the additive.

[063] In an embodiment of the present disclosure, there is provided a nozzle for injecting the additive of the present disclosure at a predetermined droplet size ranging from about 1 mm to about 10mm, during the refinery process including but not limited to cracking process and coking process. The nozzle comprises an inlet which is fluidly connected to a system for receiving the additive, and an outlet for injecting the additive into the reactor. Further, the outlet of the nozzle is housed inside the reactor, preferably inside the coke drum of the coker unit and the outlet is configured with a plurality of openings for injecting additive into the reactor at a predetermined droplet size ranging from about 1mm to about 10mm.

[064] Figures 3a and 3b are exemplary embodiments of the present disclosure illustrating the nozzle of the present disclosure. The nozzle comprises an inlet which is fluidly connected to a reactor [Figure 2] for receiving the additive, and an outlet for injecting the additive into the reactor, preferably coke drum of the coker unit. Further, the outlet of the nozzle is housed inside the reactor, preferably coke drum of the coker unit, and the outlet is configured with a plurality of openings such as but not limiting to slots, holes, perforation, and combinations thereof for injecting additive into the reactor at the predetermined droplet size. In one embodiment, shape of the openings includes but is not limited to rectangular, circular, elliptical, square and triangular, or any combination thereof. Further, the nozzle of the present disclosure is configured to inject the additive at predetermined droplet size ranging from about 1 mm to 10 mm into the reactor.

[065] In one embodiment of the present disclosure, the outlet of the nozzle comprises six openings such as slots for injecting the additives into the reactor as shown in FIG. 3a. In an alternate embodiment of the present disclosure, the nozzle comprises six or nine openings such as slots for injecting additives into the reactor as shown in Figures 3a and 3b, respectively. However, it should be noted that the number of openings should not be construed as a limitation, and the number of openings may vary based on the design of the nozzle and the desired application.

[066] In an exemplary embodiment, about 50% to about 90% of evaporation of the carrier is achieved by injecting the additive comprising catalyst and carrier at a droplet size ranging from about 1mm to about 10 mm, preferably at less than about 7 mm, and more preferably at less than about 5 mm, with the help of the nozzle of the present disclosure.

[067] In an alternate exemplary embodiment, about 50% to about 90% evaporation of the carrier is achieved by injecting the additive comprising catalyst and carrier at an average droplet size ranging from about 1mm to about 10mm, preferably at less than about 7mm, and more preferably at less than about 5mm with the help of the nozzle.

[068] In a non-limiting embodiment of the instant disclosure, the additive is prepared using a system comprising components including but not limited to 'catalyst tank' and 'eductor'. The additive is formed inside the injection line which connects the said system to the reactor, preferably coke drum top of the coker unit. In an embodiment, the catalyst tank is connected to the eductor via suction line.

[069] In a preferred embodiment of the system as described above, location of the catalyst tank and the eductor is selected such that the flow path of additive is minimized.

[070] In a non-limiting embodiment of the system as described above, the formation of additive inside the injection line occurs as follows: a carrier in the eductor is passed through a nozzle at velocity of about 50 m/sec to about 200 m/sec) and the vacuum created due to the venture effect facilitates the flow of solid catalyst (from the catalyst tank) into this stream. The velocity of the additive inside the injection line keeps the solid suspended till it enters the reactor, preferably coke drum of the coker unit, thereby avoiding plugging of injection line.

[071] In another non-limiting embodiment of the system as described above, the catalyst tank has a provision of nitrogen purging for fluidization of catalyst inside the tank. The dry catalyst is maintained at minimum fluidization velocity to facilitate free flow of catalyst to the eductor. In a preferred embodiment, the fluidized catalyst is easily sucked by the eductor and mixed with the motive fluid (carrier) to form the additive in the injection line. In an exemplary embodiment, the diameter of the injection line is about linch to about 3inch which is designed according to the flow rate of the carrier fluid, which is about 5 m ³ /hr to about 30 m ³ /hr of the carrier fluid, to keep the additive velocity higher than saltation velocity (1.5m/sec) to avoid sedimentation of catalyst particles. In another embodiment, length of the injection line is about 50m from eductor to coke drum top, which is kept as small as possible to maintain the velocity.

[072] In a non-limiting embodiment, the design of the eductor system for preparing additive is depicted in Figure 1. The said figure illustrates a commercial delayed coker unit comprising the present system for preparing additive (catalyst and carrier).

[073] In alternate embodiment, the present disclosure relates to an additive comprising catalyst and carrier, wherein the additive is a composition. The catalyst within the additive is at a concentration ranging from about 2wt% to about 50wt% and is selected from a group comprising alumino silicate zeolite, zeolite Y, acidic clay and ZSM-5 zeolite, or any combination thereof, wherein the catalyst is fluid catalytic cracking (FCC) catalyst. The carrier within the additive is at a concentration ranging from about 50% to about 98% and is selected from a group comprising straight run naphtha, unstabilized naphtha, FCC naphtha, heavy coke naphtha and light coke naphtha, or a combination thereof, and wherein the carrier is devoid of coke precursor.

[074] In an exemplary embodiment, the additive is in a form selected from a group comprising slurry, solid, semi-solid, or a combination thereof.

[075] In an another exemplary embodiment, the additive of the present disclosure leads to about 0.5wt% to about 2.0wt% reduction in the coke formation and leads to a about 0.5wt% to about 2.0wt% increment in the hydrocarbon (distillate) formation when compared to the conventional process, wherein the hydrocarbon is selected from a group comprising gases, naphtha, kerosene, gas oil and heavy gas oils, or any combination thereof.

[076] In another alternate embodiment, the present disclosure relates to a process for preparing additive comprising catalyst and carrier, wherein the process comprising the step of mixing the additive with the catalyst. The additive prepared by this process is having a droplet size ranging from about 1mm to about 10mm. The mixing of the additive is carried out by means including but not limiting to agitator.

[077] The carrier described in the present disclosure is in a form selected from a group comprising fluid, solid, semi-solid and gaseous, or any combination therefore. The carrier is preferably in the fluid form.

[078] Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples provided herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the following examples should not be construed as limiting the scope of the embodiments herein.

EXAMPLES

Experimental setup/Materials employed for arriving at the examples of the present disclosure

[079] Experiments are carried out in two different 'delayed coker pilot plants' and one block having two coke drums in one of world's largest 'commercial delayed coker unit' . [080] Preliminary Isothermal experiment in semiautomatic delayed coker pilot: Preliminary experiments are conducted under isothermal conditions in a delayed coker pilot plant having feed rate of about 4kg/h. This pilot plant has manual controllers for controlling the temperature, pressure and feed rate. [081] Detailed Isothermal and Adiabatic experiment in fully automatic delayed coker pilot plant:

Detailed isothermal and adiabatic experiment is conducted in PLC based (Programmable Logic Controller) fully automatic delayed coker pilot plant. This pilot plant has precise control over temperature, pressure and flow rates. It is equipped with nucleonic gauge for online coke drum level monitoring. The feed is pumped with a gear pump and the feed rate is precisely monitored with a Corriolis flow meter. The pilot plant has provision for injecting velocity steam through a static mixture before feed preheater furnace inlet. The preheater furnace is a nine zone electrically heated furnace. The temperatures of all 9 furnace zones, furnace tube and process stream are constantly monitored and controlled by the PLC. Coke drum of the pilot plant is a cylindrical reactor having 1.5 meter length and 10 inch diameter. The coke drum is divided in to five zones namely: bottom flange, bottom zone, middle zone, top zone and top flange. Temperature of each zone is monitored and controlled by five independent temperature indicators and controllers (TIC). The pilot plant is equipped with a tank with stirrer and pump for precise injection of catalyst from a nozzle provided at the coke drum top flange. Figure 1 shows a process flow diagram of the delayed coker pilot plant.

[082] In isothermal experiment, the temperatures of all five zones of coke drum are controlled in auto mode. Hence, the temperatures are constant throughout the entire coking cycle. In this mode, the heat demand by the coke drum is automatically fulfilled by increasing/decreasing the heater power output by the PID controller.

[083] In pseudo-adiabatic experiment, the temperatures of all five zones of coke drum are controlled in manual mode. Coke drum heater power outputs are fixed after one hour of feed cut in. In pseudo-adiabatic mode, the coke drum temperatures are not constant throughout the coking cycle and any extra heat demand in coke drum resulted in decreasing the coke drum temperature.

[084] Detailed Adiabatic experiment in Commercial Delayed Coker Unit (DCU)

Commercial delayed coker unit used in the present disclosure has a capacity of 160KBPSD (Kilo Barrels Per Stream Day) which is one of the largest commercial delayed coker unit in the world. There are four blocks of two coke drum each in this commercial DCU. At any moment in time, four drums, one from each block, are in line for coking process whereas the other four drums, one from each block, are in various stages of emptying the filled coke. A setup comprising of a catalyst tank and an eductor system is installed on top of one of the coke drum for carrying out the experiments. The other coke drum of this block is used as base case. Figure 2 shows the process flow diagram of this experimental setup.

Example 1: Coking process (Base case) in semiautomatic coker pilot plant under isothermal conditions

[085] This experiment is conducted in delayed coker pilot plant under isothermal condition. The coke drum heater output is varied to maintain constant drum temperature during the experiment. The feed used in this experiment is a mixture of about 40 wt% vacuum residue (VR) and about 60 wt% clarified slurry oil (CSO). The properties of feed are shown in 'Table 1 ' below. The operating conditions such as feed rate, steam rate, furnace outlet temperature and coke drum pressure are maintained as about 4 Kg/h, about 0.04 Kg/h, about 496°C and about 1.8 kg/cm ² (g), respectively. This experiment is conducted by injecting Light Coker Gas Oil (LCGO) at a rate of about 0.11 Kg/h as carrier. The experiment is carried out for duration of about 3 hours. The yields are shown in 'Table 2' below, in comparison with yields obtained when an additive is employed, in example 2.

Table 1 : Feed properties

[086]

Example 2: Additive injection in semiautomatic coke pilot plant under isothermal conditions [087] The setup mentioned in Example 1 is used with identical operating conditions except that in place of carrier, additive comprising catalyst (FCC) and carrier is injected from the top of coke drum at a rate of about 0.1 Kg/h. The yields are shown in 'Table 2' .

Table 2: Effect of additive under isothermal condition

[088] As observed from Table 2, there is a decrease of about 1.5 wt% in coke yield when additive comprising LCGO and catalyst is injected into coke drum when compared to the injection of LCGO alone under isothermal conditions (as per example 1). The negative effect of carrier is not visible in these experiments as the extra heat energy required for evaporation of the carrier (LCGO) is supplied by the electrical heaters of the coker pilot plant furnace. There is no information provided by the prior art methods regarding the extent of quenching of vapour liquid interphase in coke drum due to heat removal by the carrier.

[089] To further assess the effectiveness of additive comprising catalyst and carrier, experiments are performed in commercial delayed coker unit. This delayed coker unit has four blocks having two coke drums in each block. The experiment is carried out in one block where one of the coke drums is fitted with an additive injection system and the other drum is used as base case for measurement of change in coke yield. Overall gas and liquid product yields are not compared during this experiment due to the fact that these products from all 4 inline coke drums are combined before routing to fractionator. Therefore, the overall change in gaseous and liquid products will be one fourth of the actual change occurring due to the additive. However, as the coke yield in each drum can be measured separately it is used for measuring the change in coke yield for base case and additive injection cases.

Example 3: Heavy Carrier (true boiling point ranging from about 343 °C to about

560°C) injection in commercial delayed coker unit under adiabatic conditions [090] Reaction Condition: The furnace outlet temperature is maintained at about 498°C and coke drum pressure is maintained at about 2kg/cm ² (g). The temperature of the bottom, middle and top zones of the coke drum is maintained at about_460°C, at about 455°C and at about 440°C, respectively. The coking cycle is carried out for duration of 12hrs.

[091] A) The experiment is conducted in a commercial delayed coker unit having a feed rate of about 300 ton/H and steam injection of about 3 ton/H without injection of additive or carrier.

[092] B) The experiment is conducted in a commercial delayed coker unit having a feed rate of about 300ton/H and steam injection of about 3 ton/H along with injection of about 2 wt% heavy carrier, i.e., heavy coker gas oil (HCGO) from coke drum top, wherein the carrier is having a true boiling point ranging from about 343°C to about 560°C.

[093] The coke yields of this example are summarized in Table 3 below, along with comparison of base case with additive in example 4 below.

Example 4: Additive (Heavy Carrier (343°C- 560°C) and Catalyst) injection in commercial delayed coker unit under adiabatic conditions

[094] Reaction Condition: The furnace outlet temperature is maintained at about 498°C and coke drum pressure is maintained at about 2kg/cm ² (g). The temperature of the bottom, middle and top zones of the coke drum is maintained at about 460°C, about 455°C and about 440°C, respectively. The coking cycle is carried for a duration of 12hrs.

[095] A) The experiment is conducted in a commercial delayed coker unit having a feed rate of about 300 ton/H and steam injection of about 3 ton/H without injection of additive or carrier.

[096] B) The experiment is conducted in a commercial delayed coker unit having a feed rate of about 300 ton/H and steam injection of about 3 ton/H along with injection of about 2 wt% additive from top of coke drum, wherein additive comprises catalyst (FCC) in carrier heavy coker gas oil (HCGO) which is having a true boiling point ranging from about 343°C to about 560°C. Example 4 is repeated to assess the coke yield reduction. The concentration of catalyst and carrier in the additive is about 8.3 wt% and about 91.7wt%, respectively. [097] The coke yields of Examples 3 and 4 are summarized in Table 3 below.

Table - 3 : Variation of Coke Yield in Commercial DCU with Heavy Carried Fluid coke yield (wt%)

Example 3A(base case) 32.17

Example 3B (carrier fluid) 35.23

Example 4A 1 (base case) 33.85

Example 4B 1 (additive slurry ) 34.77

Example 4A 2 (base case) 33.70

Example 4B_2(additive slurry ) 34.77

Example 4A 3 (base case) 32.93

Example 4B_3(additive slurry ) 33.70

[098] As seen from Table 3, the coke yield is consistently higher in the experiments where additive is injected (Example 4) or carrier is injected (Example 3) in comparison to base case. These results show that there is no benefit of coke yield reduction with additive injection in commercial delayed coker unit when heavy hydrocarbon carrier having a true boiling point ranging from about 343°C to about 560°C is used in the coking process.

[099] Further, Table 3 shows that the average coke yield increase in Example 4 is about 0.92 wt%, whereas in Example 3 the increase is about 3 wt%. These results suggest that although the catalyst is helping in coke yield reduction, the coke yield increase due to carrier is much higher. Thus, the overall coke yield does not show a significant decrease with additive injection.

Example 5: Coking process (Base case) in fully automatic coker pilot plant under pseudo adiabatic condition

[100] This experiment is conducted under pseudo-adiabatic condition by providing constant heat energy to coke drum bottom, middle and top zone with fixed output by the proportional- integral-derivative controller (PID controller). The vacuum residue (VR) feed rate of about 9 Kg/H is maintained. About 2 wt% steam is also injected at the furnace inlet for increasing the velocity of feed inside furnace tube. Coke drum pressure is maintained precisely by a pressure control valve at about 2 Kg/cm ² (g). The furnace outlet temperature is maintained at about 498°C. Coking cycle for duration of 12 hours is maintained. Physico-chemical properties of the VR feed are tabulated in Table 4. The yields of various products are summarized in Table 5, in comparison with results from examples 6 to 9, given below.

[101] Table 4: Properties of Vacuum Residue

Example 6: Heavy Carrier (true boiling point of about 343 °C to about 560°C) injection in fully automatic coker pilot plant under pseudo adiabatic conditions

This experiment is conducted under identical conditions of Example 5 along with injection of heavy carrier having a true point ranging from about 343°C to about 560°C. Heavy coker gas oil (HCGO) from the top of coke drum at a rate of about 2 wt% of the VR (vacuum residue) feed of table 4 provided previously. The yields of various products are summarized in Table 5, in comparison with results from example 5 above and example 7 to 9, given below.

Example 7: Light Carrier (true boiling point of about 21°C to about 110°C) injection in fully automatic coker pilot plant under pseudo adiabatic conditions

This experiment is conducted under identical conditions of Example 5 along with injection of light carrier fluid, i.e., Light Coker Naphtha (LCN) having a true boiling point ranging from about 21°C to about 110°C from the top of coke drum at a rate of about 2 wt% of the VR (vacuum residue) feed. The yields of various products are summarized in Table 5, in comparison with results from examples 5 and 6 above and examples 8 to 9, given below.

Example 8: Additive (Heavy Carrier + catalyst) injection in fully automatic coker pilot plant under pseudo adiabatic conditions

[102] This experiment is conducted under identical conditions of Example 5 along with injection of about 10% additive comprising catalyst (FCC) in heavy carrier (HCGO) having a true boiling point ranging from about 343 °C to about 560°C from the top of coke drum at a rate of about 2 wt% of the VR (vacuum residue) feed. The yields of various products are summarized in Table 5, in comparison with results from examples 5 to 7 above and example 9, given below.

Example 9: Additive (Light Carrier + catalyst) injection in fully automatic coker pilot plant under pseudo adiabatic conditions

[103] This experiment is conducted under identical conditions of Example 5 along with injection of about 20% additive comprising catalyst (FCC) in light carrier (LCN) having a true boiling point ranging from about 21 to about 110°C from the top of coke drum at a rate of about 2 wt% of the VR (vacuum residue) feed. The yields of various products are summarized in Table 5, in comparison with results from examples 5 to 8, given above.

Table 5 : Effect of carrier & additive under isothermal and pseudo-adiabatic conditions

[104] As observed from Table 5, under identical experimental conditions of constant feed properties and operating parameters, injection of heavy carrier (Example 6) and additive comprising catalyst in heavy carrier (Example 8) resulted in net increase in coke yield when compared to base case (Example 5), i.e. from 33.1wt% to 34.1wt% and 33.3wt%, respectively. Injection of lighter carrier (Example 7) also increased the coke yield when compared to base case (Example 5), i.e. from 33.1wt% to 33.7wt%. However, the increase is much lower in comparison to Example 6. Further, when additive comprising catalyst in lighter carrier is injected (Example 9), a net decrease of about 0.6 wt% in coke yield is observed. Hence, these results depict that carrier liquid plays a very crucial role in determining the overall coke yield reduction when all other parameters like operating conditions, feed and catalyst properties are kept constant. From this it can be concluded that additive comprising carrier having a true boiling point ranging from about 40°C to about 200°C is one of the important factors along with other factors such as about 50% to about 90% evaporation of the carrier before the additive reaches the vapour liquid interphase and the presence of carrier in the range of about 50% to about 98% within additive, in achieving coke yield reduction in the refinery process including but not limited to coking process and cracking process.

Example 10: Light Carrier (true boiling point ranging from about 21°C to about 187°C) injection in commercial delayed coker unit under adiabatic conditions [105] Reaction Condition: The furnace outlet temperature is maintained at about 498°C and coke drum pressure is maintained at about 2kg/cm ² (g). The temperature of the bottom, middle and top zones of the coke drum is maintained at about_460°C, about 455°C and about 440°C, respectively. The coking cycle is carried for a duration of 12hrs.

[106] A) This experiment is conducted in a commercial delayed coker unit having feed rate of about 300 ton/H and steam injection of about 3 ton/H without injection of additive or carrier.

[107] This experiment is conducted in a commercial delayed coke unit having feed rate of about 300 ton/H and steam injection of about 3 ton/H along with injection of about 2 wt% light carrier having a true boiling point ranging from about 40°C to aboutl87°C from coke drum top. The coke yields of this example are summarized in Table 6 below, in comparison with yields from additive in example 11 below.

Example 11: Additive (catalyst and light carrier) iniection in commercial delayed coker unit under adiabatic conditions

[108] Reaction Condition: The furnace outlet temperature is maintained at about 498°C and coke drum pressure is maintained at about 2kg/cm ² (g). The temperature of the bottom, middle and top zones of the coke drum is maintained at about_460°C, about 455°C and about 440°C, respectively. The coking cycle is carried for duration of 12hrs.

[109] A) This experiment is conducted in a commercial delayed coker unit having feed rate of about 300 ton/H and steam injection of about 3 ton/H without injection of additive or carrier.

[110] B) This experiment is conducted in a commercial delayed coker unit having feed rate of about 300 ton/H and steam injection of about 3 ton/H carrier along with injection of about 2 wt% of additive comprising catalyst in light carrier having a true boiling point ranging from about 40°C to about 187°C from top of the coke drum. This experiment is conducted in two sets: in set-1, the catalyst concentration in additive is about 2.8 wt% and in set-2, the catalyst concentration in additive is about 5.5 wt%.

[Ill] The coke yields of examples 10 and 11 are summarized in Table 6 below, wherein the Table 6 illustrates the coke yield reduction observed when an additive comprising catalyst and light carrier having a true boiling point ranging from about 40°C to about 200°C is employed. Table - 6: Variation of Coke Yield in Commercial DCU with Light Carrier Fluid

Table 7: Effect of carrier on coke yield under adiabatic conditions

[112] As seen from Table 7, with only injection of light carrier having a true boiling point ranging from about 40 °C to about 200°C, the increase in coke yield is only about 0.76 wt% against 3.06 wt% observed in case of injecting Heavy Carrier having a true boiling point ranging from about 343°C to about 560°C. Further, when additive having about 2.8 wt% catalyst along with the light carrier having true boiling point ranging from about 40 °C to about 200°C is injected from the top of coke drum, there is a decrease in coke production, which is about 0.46% coke when compared to 0.76 wt% in case of injection of only light carrier having a true boiling point ranging from about 40 °C to about200°C alone. Further, a net reduction of 0.46wt% in coke yield is observed with injection of about 5.5wt% catalyst along with light carrier having a true boiling point ranging from about 40 °C to about 200°C. Thus, in this case, the negative effect of carrier is completely outweighed by the catalyst. Therefore, selection of carrier and catalyst concentration play very crucial role in achieving actual coke yield reduction in commercial coker plant under adiabatic conditions.

[113] In an embodiment, the additive comprising catalyst and carrier employed in the examples 1 to 11 has a droplet size ranging from about 1mm to about 10mm. Example 12: Additive (Catalyst and light carrier) injection in commercial delayed coker unit under adiabatic conditions without nozzle

[114] Reaction Condition: The furnace outlet temperature is maintained at about 498°C and coke drum pressure is maintained at about 2kg/cm ² (g). The temperature of the bottom, middle and top zones of the coke drum is maintained at about_460°C, about 455°C and about 440°C, respectively. The coking cycle is carried for duration of about 12hrs.

[115] This experiment is conducted in a commercial delayed coker unit having feed rate of about 300 ton/H and steam injection of about 3 ton/H along with injection of about 2 wt% additive comprising catalyst in light carrier having a true boiling point ranging from about 40°C to about 190°C from coke drum top. However, the nozzle used for atomization of additive is removed and the additive is injected through an open pipe having a diameter of about 3". The coking cycle is maintained for duration of about 12hours.

[116] In this experiment, it is observed that there is an increase in coke yield by about 4.5wt%. Thus inferring that injecting the additive through a nozzle of the present disclosure, wherein additive is having a specific size ranging from about 1mm to about 10mm is one of the important parameters in the process of present disclosure for reducing coke yield along with other parameters such as additive comprising a carrier having a true boiling point ranging from about 40°C about 200°C; evaporation of greater than about 50% to about 90% of carrier in the process, before the additive reaches vapour liquid interphase; and concentration of carrier in the additive in the process is about 50% to about 98%, preferably less than about 80%.

Example 13: Assessing the size of the additive (catalyst and carrier):

[117] Computational fluid Dynamics (CFD) study is carried out to find out the initial size of the droplet which is generated from a nozzle having single slot of 3" diameter. Volume of fluid (VOF) model is used in 2-D simulation of drum. The time required for droplet to reach the bottom of the drum form CFD is equated to time required for the particular droplet to reach the bottom of the drum using force balance calculations around the droplet. Based on the CFD analysis it is observed that droplet size of less than about 10mm is formed from a nozzle having single opening of 3" diameter. Similar CFD analysis is carried out for a nozzle having 6 slots of l"xl/2" size, from the analysis it is observed that 6 slot results in a droplet size of about 6mm.

[118] Based on the CFD analysis it is observed that by reducing the nozzle opening, droplet size can be reduced below 10mm. the droplet size established from the CFD is used to calculate the vaporization of different carrier liquids and resultant quenching of liquid pool in coke drum.

[119] The vaporization curves for different carriers including but not limiting to heavy coke gas oil (HCGO) having a boiling point of about 370°C to about 560°C, light coke gas oil (LCGO) having a boiling point of about 210°C to about 370°C, heavy coke naphtha (HCN) having a boiling point of about 120°C to about 200°C and light coke naphtha (LCN) having a boiling point of about 35°C to about 120°C, are provided herein.

[120] Figure 4 illustrates the vaporization curves of carriers having a droplet size of about 10mm at different distance from top of the coke drum. From the figure 4, it can be deciphered that LCN (boiling point 35°C to 120°C) evaporates fastest in the coke drum and about 90% of the carrier is vaporised at about 35m distance from the top of the coke drum/point of injection. On the other hand, HCGO (boiling point 370°C to 560°C) has not evaporated even after reaching the distance of about 38m from the point of injection.

[121] Figure 5 illustrates the vaporization curves of the carrier within the additive having a droplet size of about 6mm at different distance from top of the coke drum. From the figure 5 it can be deciphered that evaporation of all the carriers has increased. However, only LCN and HCN have reached 50% evaporation at a distance of about 15m from the point of injection.

From the above analysis it is construed that vaporization of the carrier within the coke drum takes place between 1 lm and 30m from the coke drum top. This helps in keeping the catalyst soaked with carrier fluid when it is nearing the vapour outlet line (top of coke drum) and prevents its carry over to fractionator. On the other hand about 50 % to about 90% evaporation of the carrier fluid before reaching the vapor liquid interphase helps in minimization of the quenching effect. Example 14: Assessing the temperature of the Vapour liquid interphase:

[122] Based on the amount of residual carrier coming in contact with the vapour liquid interphase after vaporization, the resultant temperature of the vapour liquid interphase is calculated at 15m, 20m and 30m height, considering a temperature of about 450°C as the original temperature of vapour liquid interphase.

[123] The concentration of catalyst in the additive is 10% and the concentration of the carrier in the additive is 90%.

[124] Figure 6 illustrates the temperature of the vapour liquid interphase upon injection of additive having different carriers, wherein the droplet size of the additive is about 10mm. [125] Figure 7 illustrates the temperature of the vapour liquid interphase upon injection of additive having different carriers, wherein the droplet size of the additive is about 6.25mm

[126] It is observed that the carrier become lighter when the vaporization is at the highest. Thus the resultant liquid pool temperature increases as the carrier boiling point decreases. The decrease in liquid pool temperature is more at 15m as compared to 30m due to lesser vaporization of the carrier at 15m as compared to 30m.

Table 8 below demonstrates the vaporization of the carrier and temperature shift at the vapour liquid interphase with different carriers, wherein the additive is having a droplet size of about 10mm and 6.25mm, respectively.

Table 8: illustrates percentage vaporization and temperature variation at vapour liquid interphase with difference carriers at 10mm and 6.25mm droplet size.

From table 8 it can be deciphered that the temperature drop in vapour liquid interphase at 30m from the point of injection is absent with LCN and HCN carrier, wherein the droplet size of the additive is at 6.25mm.

[127] Further, the effect of catalyst concentration on the temperature of the vapour liquid interphase is assessed. The initial droplet size is kept at 6.25mm and amount of carrier liquid reaching the vapour liquid interphase in coke drum is estimated to calculate resultant temperature. Higher catalyst concentration in the additive leads to lower mass of the carrier for same mass of catalyst hence less quenching of vapour liquid interphase in coke drum. The effect of catalyst concentration is tabulated in the table 9 below.

Table 9: Illustrates temperature variation at vapour liquid interphase at the 10%, 20% and 30%) concentration of the catalyst respectively.

Carrier Resultant temperature at vapor liquid Resultant temperature at vapor liquid interphase in coke drum at 15m interphase in coke drum at 30m

10% 20% 30% 10% 20% 30% catalyst catalyst catalyst catalyst catalyst catalyst cone. cone. cone. cone. cone. cone.

HCGO 442.5 446.7 448.1 445.6 448.0 448.9

LCGO 446.7 448.5 449.5 448.9 449.2 449.7

HCN 448.7 449.4 449.7 450.0 450.0 450.0

LCN 449.2 449.6 449.8 450.0 450.0 450.0

From table 9, it can be deciphered that there is no drop in the temperature of the vapour liquid interphase at 30m with LCN and HCN even at 10% catalyst concentration in additive slurry.

Example 15: Analysing carryover of Catalyst Particles to Fractionator

[128] In all experiments conducted in commercial DCU, the liquid products from fractionator are collected during injection and analyzed for filterable solid material having a droplet size greater than 0.8 μ, to assess if there is any carryover of the catalyst from the additive to the fractionator. It is observed that the filterable solids both in the base case experiment and trial experiment are below about 50 ppm suggesting that no carryover of catalyst occurred upon injection of additive comprising catalyst and carrier in the coking process, wherein both heavy coke naphtha (HCN) having a boiling point of about 120°C to about 200°C and light coke naphtha (LCN) having a boiling point of about 35°C to about 120°C, independently are used as carrier. In other words, there is no rise in the filterable solids in any liquid product suggesting that the catalyst has not escaped with hydrocarbon vapours to fractionator. Thus inferring that the additive injection in the process of present disclosure apart from reducing coke yield and increasing distillate yield prevents carryover of the catalyst into the fractionator. In a preferred embodiment, in the process of present disclosure, the carryover of the catalyst from the additive is less than about 0.5wt%. In an alternate preferred embodiment, in the process of present disclosure, the carryover of the catalyst from the additive to the fractionator is less than about 0.5wt%.

Example 16: Effect of Carrier on Quench Flow

[129] In commercial DCU, the hot vapors coming out from coke drum are quenched with a cold hydrocarbon stream in order to avoid cracking and coking in vapor line. The flow rate of quench liquid is determined by the temperature of vapors in vapor line downstream of quench injection. In base case i.e., no carrier/ injection, a quench liquid flow of 19 m ³ /hr is required to bring down the vapor temperature to desired level whereas in case of heavy and light carrier the quench flow rate decreased to 16 m ³ /hr and 13 m ³ /hr, respectively. The 13 m ³ /hr decrease in flow rate of quench liquid in case of light carrier vis-a-vis 16 m ³ /hr in case of heavy carrier suggests that lighter carrier took more heat from coke drum vapors due to higher vaporization in comparison to heavier carrier which took more heat from the vapor liquid interphase due to much lower vaporization.

[130] The present disclosure in view of the above described illustrations and various embodiments, is thus able to successfully overcome the various deficiencies of prior art and provide for an improved process for reduction of coke yield which in turn leads to the increase in yield of high-value distillates coking processes.

[131] Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.

[132] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

[133] Throughout this specification, the word "comprise", or variations such as "comprises" or "comprising" wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[134] The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

[135] Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or are common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application. [136] While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.