Description:FIELD OF THE INVENTION
The present invention provides a safe and reliable regenerator operation for Continuous Catalytic Reforming (CCR) Units. The present invention further provides a method for regenerating a reforming catalyst in a regenerator wherein transition from said Start-up mode to In-line mode is done smoothly by following “BITE” burn mode under specific conditions.

BACKGROUND OF THE INVENTION
Catalytic naphtha reforming is an established petroleum refinery process. It is used for improving the octane quality of hydrocarbon feeds in the naphtha boiling range. Generally, reforming refers to the total effect of molecular changes on a hydrocarbon feed, produced by a number of reactions. Numerous hydrocarbon conversion processes are widely used to alter the structure or properties of hydrocarbon streams. Such processes include isomerization from straight chain paraffinic or olefinic hydrocarbons to more highly branched hydrocarbons, dehydrogenation for producing olefinic or aromatic compounds, reforming to produce aromatics, alkylation, transalkylation, and others. The purpose of the reformer process in petroleum refinery operations is to upgrade heavy naphtha into a high-value gasoline blend stock by raising its octane number by converting linear paraffins to cyclic compounds, and also the production of aromatic petrochemicals such as BTX (Benzene, toluene and xylene). The primary product of the reformer is reformate, which is generally used in gasoline blend stock.

The reformer is a critical unit for making high-quality gasoline and avoiding production of low-octane heavy naphtha. Also, as sulfur specifications have tightened, forcing greater use of hydro-treating, the value of the hydrogen produced by the reformer has increased. The reformate from reforming is also the primary source of aromatics (such as benzene, toluene, and xylene) that are used as petrochemicals feedstocks. A reforming unit typically comprises a plurality of serially connected reactors with furnaces for supplying additional heat to the reaction stream as it passes from one reactor to the next in order to compensate for the heat utilized in the overall endothermic character of the process. Conventionally, reforming processes have been operated as semi-regenerative or cyclic processes using fixed bed reactors or as continuous processes such as UOP CCR Platforming™ (Continuous Catalytic Regeneration Platforming™) using moving bed reactors. The present art of engineering design of reforming process is the use of CCR - Newer reformers are built with continuous catalyst regeneration (CCR) capability, so they can operate at lower reactor circuit pressures with higher coke make, as the coked up catalyst is moved continuously to a regenerator section where the coke is burned off the catalyst before it is returned to the reactor section. CCR reformers can often operate for three or more years continuously between turnarounds and can produce reformate product with high octane numbers.

Reactivation or regeneration of catalyst in CCR unit can include, for example, removing coke from the catalyst by burning, re-dispersing catalytic metals such as platinum on the catalyst, oxidizing such catalytic metals, reducing such catalytic metals, replenishing catalytic promoters such as chloride on the catalyst, and drying the catalyst.

The regeneration of catalyst in the regenerator section in CCR reformers occurs by switching from Start-up mode (black burn mode) to In-line mode (white burn mode). The basic method for switching to Regenerator start-up mode (Black burn) to in-line (White-burn mode) normally is possible provided coke deposited over catalyst is evenly distributed across entire catalyst mass. In conventional methods, start-up i.e. Blackburn mode is resorted to where temperature excursions are avoided by keeping O2 concentration at lower level both at “ Burning Zone” as well as “Oxy Chlorination Zone”. In white burn mode, O2 concentration is kept at higher levels which help to regenerate catalyst and restore activity adequately and uniformly. The uniformity of coke is important to carry out the burning of coke in black burn mode. If the coke is not uniform on spent catalyst, the regenerator system operates in black burn mode for longer duration. Such Prolonged Black Burn mode (observed during Start up/ after process upset) adversely affects the quality of product in the form of RON and can also leads to temperature excursions which further adversely affects the efficiency of the catalyst. Not much of literature are available which deals in details with uneven coke distribution/healed catalyst make up issue in regenerator, especially after full catalyst charge unloading/loading activity had been performed in CCR Unit.

Moreover, some current designs may not allow metal to be dispersed in the chlorination zone or drying zone during some modes of operation. More specifically, in a “black burn” mode the catalyst has high levels of coke and only nitrogen is injected into these two zones. Additionally, no chloride is injected into the regenerator. This operation condition prohibits metal (including platinum) dispersion during the black burn mode resulting in decline in catalyst performance, loss of C5+ yield, hydrogen product yield and low activity.

Furthermore, during other operation modes, coke slippage or slightly higher coked catalyst passing into the chlorination zone, may result in poor metal dispersion, catalyst damage, catalyst fines generation, and equipment fouling. These can shorten the process turnaround interval leading to potential of a unit shutdown resulting in loss of production in the reforming unit.

Sustained quality reformate production can be a challenge if coke removal is not adequate with in cycle time. In other words, if catalyst is not regenerated continuously or there is uneven coke distribution in regenerator, then quality reformates production on sustained basis is not possible. For ensuring CCR operation PLUG flow regime across all reactors and regenerator must exist without interruption.

Therefore, there remains a need for effective and efficient processes for regenerating catalyst. Present invention provides a process that can always smoothly shift reformer regenerator modes i.e. black burn mode (start-up mode) to white burn mode (In-line mode), wherein such shift does not allow any temperature excursions.

OBJECT OF THE INVENTION
In main object, the present invention provides a modified, safe and reliable regenerator operation for regeneration zone of the CCR Units wherein shifting from start-up mode to in-line mode is provided with no temperature excursions.

Another object of the present invention is to provide a method for quicker normalization of upset condition related to non-uniform coke formation on catalyst resulting in profitability of the unit.

Another object of the present invention is to provide a better Pt dispersion on the reloaded catalyst.

SUMMARY OF THE INVENTION
The regeneration of catalyst in regeneration zone of CCR unit occurs in two operational modes i.e. Start-up mode (Black Burn mode) and In-line mode (white burn mode). Shifting from start-up mode to in-line mode results into temperature excursions which may damage the catalyst. Present invention provides smooth shift from start-up mode to in-line mode by providing “BITE” burn mode which is a part of continuous spectrum between the two modes of operations. It provides better maintenance of catalyst health by avoiding step change between two extremes. This helps to maintain better platinum dispersion signifying sustained catalyst activity and potentially lower alfa-alumina formation.

Accordingly, in one aspect, the present invention provides a method for smooth shifting from black burn mode to white burn mode of regeneration zone of continuous catalyst regeneration (CCR) unit, wherein said method comprising:
a) providing a transition between black burn mode and white burn mode in regeneration zone through “BITE” burn mode, wherein said “BITE” burn mode includes;
i) burning of coke on catalyst in burn zone of regeneration zone, wherein said burn zone comprises of first and second radial zones operating at inlet oxygen content of 0.8 O2 mol%, and inlet temperatures of 480oC and 490-495oC respectively;
ii) providing chlorination gas to oxychlorination zone, operating with oxygen content of 0 (Start-up mode) to 4-6 vol% (In-line operating range) and circulates upwards at a temperature varies from 440 to 510oC (In-line operating range);
iii) providing calcination gas to calcination zone, operating with oxygen content of 8 to 12 vol% and circulates upwards at a temperature of 520oC; and
wherein said “BITE” burn mode is a part of continuous spectrum between black burn mode and white burn mode.

In another aspect, the present invention discloses a CCR unit for regenerating catalyst comprising of:
a) a reaction zone comprising of four reactors [202]-[205] with a catalyst lifting arrangement comprising nitrogen lift gas and hydrogen lift gas;
b) a regeneration zone comprising regenerator which contains two radial burn zone, a oxychlorination zone and a calcination zone, wherein said regenerator operates in “BITE” burn mode characterized by:
- Burning Zone 1 and Zone 2 with inlet O2 maintained at 0.8 %;
- Zone 1 inlet temperature maintained at 480oC and Zone 2 inlet temperature maintained at 490-495oC;
- Oxy chlorination/Calcination temperature kept conservatively at least 100 degrees below normal;
- coke maintained in the range of 4 to 6 %;
further comprising at least one of the following:
i) passing nitrogen gas through lift 1 between regenerator [201] and 1st reactor [202];
ii) passing nitrogen gas through lift 5 between 4th reactor [205] and the regenerator [201]; and
iii) passing hydrogen gas for lifting the catalyst through lift 3 between the 2nd reactor [203] and 3rd reactor [204]; and through lift 4 between the 3rd reactor [204] and the 4th reactor [205].

BRIEF DESCRIPTION OF DRAWINGS:
The present invention will now be described in detail with reference to the accompanying drawings.

These and other features, aspects and advantages of the present drawings will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represents like parts throughout the drawings, wherein:
Fig. 1 represents CCR unit at the centre of Naphtha management available in Refineries
Fig. 2 represents CCR catalyst and lifting arrangements
Fig. 3 represents flow chart showcasing CCR catalyst and lifting arrangements
Fig. 4 represents “BITE” burn mode
Fig. 5 represents a flow chart of method for smooth shifting of black burn mode to white burn mode in regeneration zone of continuous catalyst regeneration (CCR) unit
Fig. 6 represents difference in two modes of operation i.e. Black Burn (Start-Up) and White Burn (In-line) mode
Fig. 7 represents process flow diagram of the Continuous Catalyst Regeneration unit
Fig. 8 represents the comparison between BITE burn and Black-White Step change
Fig. 9 represents the parameter variation during the changeover

DETAILED DESCRIPTION OF THE INVENTION
For the purpose of better understanding of the invention, reference will now be made to the embodiments illustrated in the drawings. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further application of the scope of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Reference throughout this specification to “one aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrase “one embodiment”, “another embodiment” and similar language throughout this specification, may but not necessarily, all refer to the same embodiment.

Definitions:
As used herein, the term “naphtha feed” can include various hydrocarbon molecules, such as straight-chain, branched, or cyclic alkanes, alkenes, alkadienes, and alkynes. The feed can also include aromatic and non-aromatic hydrocarbons. Moreover, the hydrocarbon molecules may be abbreviated C1, C2, C3 . . .Cn where “n” represents the number of carbon atoms in the one or more hydrocarbon molecules.

As used herein, the term “zone” can refer to an area including one or more equipment items and/or one or more sub-zones.

Herein, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, to provide a thorough understanding of embodiments of the disclosed subject matter.

Referring to Fig. 1 illustrating a refinery’s naphtha from CDU/VDU, LCN from FCCU & from Tank Storage to CCR via NHT unit.
It contains a NHT unit (Naphtha Hydro Treater) [101] from which a light naphtha passes from NHT unit to isomerization unit [102] & heavy naphtha passes to CCR unit [103]. Isomerization of naphtha occurs in Isomerization unit and the final product Isomerate is part of premium gasoline is then collected at unit end [104].
Similarly, heavy naphtha stream passes from NHT unit [101] to CCR unit [103]. CCR unit passes reformate containing Reformate stream (rich in Aromatics) which is a part of premium gasoline from unit [104].

Referring to Fig. 2 and 3, that illustrates CCR catalyst and lifting arrangements. Herein, the reactors [202]-[205] are radial flow type reactors. In the 1st Reactor [202], the reactions are predominantly endothermic and therefore the reactor effluent requires reheating in the 1st Interheater [206] to the required inlet temperature of the 2nd reactor [203]. The reactions in this Reactor are comparatively less endothermic but still require reheating in 2nd interheater [207] before entering the 3rd reactor [204]. The 3rd reactor effluent is reheated in the 3rd Interheater [208] before entering the Fourth Reactor [205]. The effluent leaves the 4th reactor at approximately 450-475oC (depending on the position in the cycle and feed) and 3.5 kg/cm2g. The inlet temperatures of the four reactors are almost at same level. Herein, each reactor contains catalyst that circulates continuously, in the reactors, in the space between the scallops and the central pipe from the top to the bottom. Flow direction is from first reactor bottom to the next reactor top and so on such that catalyst enters the last (fourth) reactor from the top. From the last reactor bottom catalyst enters to the regeneration unit containing regenerator [201] for regeneration of catalyst. After regeneration, the regenerated catalyst returns to the 1st reactor [202] from unit [201]. In the regeneration unit, the catalyst is regenerated by means of an automated regeneration loop system. The reaction zone of CCR unit further contains catalyst lifting arrangement comprising nitrogen lift gas and hydrogen lift gas wherein nitrogen gas is passed through lift 1 between regenerator [201] and 1st reactor [202] and through lift 5 between 4th reactor [205] and the regenerator [201]. After regeneration of catalyst, the hydrogen gas is passed through lift 2 between the 1st reactor [202] and 2nd reactor [203]. Hydrogen gas is then passed through lift 3 between the 2nd reactor [203] and 3rd reactor [204] followed by passing through lift 4 between the 3rd reactor [204] and the 4th reactor [205]. In an implementation, the hydrogen produced in reforming reactors goes to the separator and finally to the downstream unit for purification before being routed to the refinery hydrogen network header.

Referring to the Fig. 4, that illustrates “BITE” burn mode shows that the regeneration unit [201] of CCR unit contains two radial burn zone (Burning Zone 1 [301] /Zone 2 [302]), a oxychlorination zone [303] and a calcination zone [304], wherein said regenerator operates in “BITE” burn mode. The “BITE” mode is neither a black burn mode nor a white burn mode. It operates with specific conditions wherein coke is removed from the reforming catalyst in burning zone [301] and [302] that operates with intlet O2 of 0.8 vol% and the reforming catalyst is contacted with oxygen and chlorine in oxychlorination zone [303] containing oxygen content of 4 to 6 vol% circulating upwards at a temperature of 510oC. The calcination in calcination zone [304] containing oxygen content of 8 to 12 vol% and circulates upwards at a temperature of 520oC occurs wherein the reformed catalyst obtained after removal of coke in burning zone [302] and dried [306] at temperature ranging between 500-520oC before introducing to oxychlorination zone. In an embodiment, the gas from the regenerator is washed in a caustic wash drum [305] and returned back to the regenerator after drying.
As discussed above, any coke that enters this zone will combust, damaging the catalyst. Accordingly, a regenerator may operate in “black burn” mode when the coke level on the catalyst is high and nitrogen may be introduced into the bottom of the unit [201] to control the exothermic reaction. However, no chloride is introduced into the regeneration burning zone [301] and [302], meaning that catalyst chloride level on the regenerated catalyst will be lower than a desired amount. Additionally, metal dispersion on the regenerated catalyst will be less than ideal. The metal dispersion, chloride treatment and contact with oxygen takes place in oxychlorination zone [303] and the activated catalyst is passed to calcination zone [304] for drying.

Referring to Fig. 6 that illustrates a method for smooth shifting of black burn mode (or Start-up Mode) to white burn mode (or In-Line Mode) through BITE burn mode in regeneration zone of continuous catalyst regeneration (CCR) unit, represented in form of a flowchart. In step 401, method provides passing a catalyst from a reaction zone to a first burn zone [301] of regeneration unit [201] of CCR unit operating at inlet oxygen content of 0.8 O2 mol %, and inlet temperatures of 480oC
At step 402, the method provides passing a catalyst from a first burn zone [301] to second burn zone [302] of regeneration unit [201] of CCR unit operating at inlet oxygen content of 0.8 O2 mol %, and inlet temperatures of 490-495oC
At step 403, the method provides passing catalyst to oxychlorination zone containing a chlorination gas operating with oxygen content of 4 to 6 vol% and circulates upwards at a temperature of 510oC
At step 404, the method provides of drying catalyst at temperature ranging between 500-520oC.
At step 405, the method provides passing catalyst to calcination zone containing a calcination gas operating with oxygen content of 8 to 12 vol% and circulates upwards at a temperature of 520oC
At step 406, the method provides recycling the catalyst from the regeneration zone back to the reaction section.
Herein, no chloride is added to regeneration burning zones [301] and [302]. The metal dispersion on the regenerated catalyst occurs followed by chloride treatment and contact with oxygen and water that takes place in oxychlorination zone [303] and then passed to calcination zone [304] for drying of catalyst.

Referring to Fig. 6, that illustrates the difference in two modes of operation i.e. Black Burn (Start-Up) and White Burn (In-line) mode with respect to Air/Water/ Chloride injection in regeneration Zone. The regeneration zone has three further zones; i.e. burning zone, oxychlorination and calcination zone. The burning zone is composed of two radial beds, physically linked by 8 descending pipes. These radial beds are crossed by the combustion gas. The temperature and oxygen content of this gas are increased as the combustion reaction advances from bed to bed. The controlling parameters are the combustion gas temperature and the oxygen content at the inlet of the burning beds.

During Start-up process, the inlet oxygen of first burning bed (zone) is 0.8 O2 mol% and of second burning bed (zone) is 0.4-0.5 O2 mol%, wherein inlet temperature is maintained at 480oC. After coke burning, the catalyst flows through another set of 8 pipes towards an axial bed where oxychlorination reactions take place. The oxychlorination gas, introduced in the oxychlorination bed and containing a small amount of chlorination agent (PCE) and water (typically the 50 % of the flowrate) contains oxygen content of 0.8% oxychlorinatiion unit operates at a temperature of 510oC. After oxychlorination, the catalyst flows towards the calcination zone. The calcination gas is introduced in the bottom part of the Regenerator and circulates upward. The calcination gas, which has crossed the calcination zone (typically 50 % of the flowrate) has oxygen content of 0.8 vol. %. The water content in the calcination zone is less than 50 vol. ppm. A minimum pressure drop is maintained between the burning zone and the oxychlorination / calcination zone to prevent the oxychlorination gas, with a high oxygen content, from mixing with burning gas.

During In-line process, the inlet oxygen of first burning bed (zone) is 0.8 O2 mol% and of second burning bed (zone) is 0.8 O2 mol%, wherein inlet temperature is maintained at 480oC. After coke burning, the catalyst flows to oxychlorination zone and then to calcination zone. The oxychlorination gas, introduced in the oxychlorination zone containing a small amount of chlorination agent (PCE) and water (typically the 50 % of the flowrate) contains oxygen content of 4 to 6%. After oxychlorination, the catalyst flows towards the calcination zone. The calcination gas is introduced in the bottom part of the Regenerator and circulates upward. The calcination gas has oxygen content of 8 to 12 vol. %. The calcination zone operates at 520oC.

Referring to Fig. 7, that illustrates process flow diagram of the Continuous Catalyst Regeneration unit. The figures in the round indicate stream/system pressure in kg/cm2 while the figures mentioned in the rectangle indicates the temperature profile of the stream /system in deg C. A Continuous Catalytic regeneration unit consists of a Regenerator Reactor where the coke is burnt in the first 2 zones and thereafter chloride and platinum dispersion is adjusted by injection of percholoro ethylene and water (DM water). The last part of the reactor called calcination zone is used for drying the catalyst and finally the regenerated catalyst is sent to the 1st Reforming Reactor top via lift. The temperature profile of the regenerator is usually kept at 470 -500oC in the burning zones and 510-520oC in the oxychlorination and the calcination zones. The Regenerator pressure is maintained at 5kg/cm2. The effluent gases of the regenerator is treated in a caustic washing system and then rerouted to the regenerator after drying. The loop gas compressor aids in recycling the dried gas back to the system. An air makeup compressor is used for maintaining the necessary O2 levels in the reactor. The N2 compressor is used for maintaining pressure in the N2 lifts.

Referring to Fig. 9, which illustrates the parameter variation during the changeover. Herein, Graphs 1 to 3 are temperature variation of regenerator oxy-chlorination zone. Graph 4 are flow of Per-Chloro-ethylene (PCE) i.e. C2Cl4. Graph 5 are DM water flow and Graph 6 are O2 concentration in Oxy-Calcination zone.

According to the method of the present invention, the regeneration zone of CCR unit is started in Start-up mode (Black burn mode), with specific set of parameters (generally convention method) in the Regenerator section of the unit so as to avoid thermal spikes in the form of exotherm and consequent damage to catalyst and/ or equipment. During convention start-up of Regenerator, start-up mode is initiated where temperature excursions are avoided, by keeping O2 concentration at lower level both at “Burning Zone” as well as “Oxy Chlorination Zone” as part of standard operating procedure. In White burn mode, process O2 concentration is kept at higher levels which help to regenerate catalyst and restore activity by restoring platinum dispersion adequately and uniformly across entire charge of catalyst. The uniformity of coke in Regenerator on spent catalyst must be at permissible levels i.e., 4 to 6 % by varying parameter (Catalyst circulation, oxygen levels etc.) for avoiding uncontrolled coke burning which leads to temperature excursion depending upon coke content. Moreover, reloading of used catalyst in regenerator is performed such that undue high exotherm are not encountered in Regenerator due to improper distribution while the unit is being operated. The reloading of used catalyst is performed to put back into the system a good pills that comes out along with dust. With predominantly black burn operation for more than 10 days continuing PCE (per chloro ethylene, chlorine source) dosing in feed to maintain catalyst activity, lead to low endotherm with decreasing trend (deteriorated due to continuous black burn operation).

During this period, whenever switched on to In-Line mode (White Burn mode) as per standard procedure endorsed by Licensor, abnormal temperature rise was experienced within few hours of such operation and thus had to resort to Start-up mode (Black Burn mode) only to control thermal excursions. If the entire amount of coke is not burnt off at the bottom of burning zone (in case of non-normal coke generating on catalyst for instance), the Regenerator will be automatically operated in black burning mode through temperature/ differential pressure /Oxygen interlock. The catalyst, though not free of coke, flows through the oxychlorination and calcination zones, where air injection as well as chlorination agent (PCE) and water injections are suspended. Consequently the catalyst returns to the Reactors despite a certain coke level. The Unit can continue to work under these conditions for a short period of time (a few hours), allowing to maintain the catalyst circulation while operating conditions are adjusted to recover an acceptable coke level on catalyst.

With longer Black burn mode operation, conditions further deteriorates as endotherm of CCR catalyst falls as low as 189oC which leads to lower quality reformate production. Further, serious temperature excursion is experienced in the Regenerator which resulted in catalyst lumps formation and thus inhibiting free flow of catalyst. This causes non-smooth lifting of catalyst due to presence of catalyst lumps.

Hence, to overcome such situation, a modified operating conditions is performed in the present invention which results into smooth transition from start-up mode to in-line mode without temperature excursions. This formed the trigger to “BITE” mode of operation which is neither Black Burn nor White Burn, but a set of conditions which will ensure sustained operation of the CCR unit.

The “BITE mode” of the present invention is a set of process conditions including operating regenerator zone at specific temperature, O2 concentration, chemical / DM water injection, catalyst circulation, and coke level which allows smooth transitioning from “Black Burn” to “White Burn”. In other words, “BITE” prevents any step change and instead gradually approaches “White Burn” as part of continuous spectrum between the two modes and all adverse effects associated with conventional procedure.

Accordingly, in one embodiment, the present invention provides a method for smooth shifting from black burn mode to white burn mode of regeneration zone of continuous catalyst regeneration (CCR) unit, wherein said method comprising:
a) providing a transition between black burn mode and white burn mode in regeneration zone through “BITE” burn mode, wherein said “BITE” burn mode includes;
i) burning of coke on catalyst in burn zone of regeneration zone, wherein said burn zone comprises of first and second radial zones operating at inlet oxygen content of 0.8 O2 mol %, and inlet temperatures of 480oC and 490-495oC respectively;
ii) providing chlorination gas to oxychlorination zone, operating with oxygen content of 0 (Start-up mode) to 4-6 vol% (In-line operating range) and circulates upwards at a temperature varies from 440 to 510oC (In-line operating range);

iii) providing calcination gas to calcination zone, operating with oxygen content of 8 to 12 vol% and circulates upwards at a temperature of 520oC; and
wherein said “BITE” Burn mode is a part of continuous spectrum between black burn mode and white burn mode.

In another embodiment, the present invention provides a method for continuous regeneration of a catalyst in continuous catalyst regeneration (CCR) unit wherein said method includes starting of CCR unit in Black burn mode as per standard procedure after catalyst loading.

In another embodiment, the present invention provides a method for continuous regeneration of a catalyst in continuous catalyst regeneration (CCR) unit wherein said CCR unit operates at reactor inlet temperatures of about 518-528oC RIT (reactor inlet temperature). The total endotherm range of the reactors vary along with the reactions taking place in the reactor and is dependent on the quality of feed (napthenes and aromatic content), catalyst circulation rate. An optimum case will provide total endotherm of 270oC.

In another embodiment, the present invention provides a method for continuous regeneration of a catalyst in continuous catalyst regeneration (CCR) unit wherein said method requires catalyst circulation at 350 Kg/hr.

In another embodiment, the present invention provides a method for continuous regeneration of a catalyst in continuous catalyst regeneration (CCR) unit wherein said method requires O2 level in Oxy chlorination zone to be 10%.

In another embodiment, the present invention provides a method for continuous regeneration of a catalyst in continuous catalyst regeneration (CCR) unit wherein the coke present on the catalyst while introduction to burn zone is maintained at a level of 4-6%.

Herein, said level of coke is maintained by increasing severity/Increasing throughput/Reducing circulation rate. Catalytic circulation is tuned to 350 kg/hr for regenerator zone of CCR unit. Once circulation stabilized @ 350 kg/hr then reactor RIT is increased within the operating window (higher side) followed by increasing load marginally depending upon % coke.

In another embodiment, the present invention provides CCR unit for regenerating catalyst comprising of:
a) a reaction zone comprising of four reactors [202]-[205] with a catalyst lifting arrangement comprising nitrogen lift gas and hydrogen lift gas;
b) a regeneration zone comprising regenerator which contains two radial burn zone, a oxychlorination zone and a calcination zone, wherein said regenerator operates in “BITE” burn mode characterized by:
- Burning Zone 1 and Zone 2 with inlet O2 maintained at 0.8 %;
- Zone 1 inlet temperature maintained at 480oC and Zone 2 inlet temperature maintained at 490-495oC;
- Oxy chlorination/Calcination temperature kept conservatively at least 100 degrees below normal;
- coke maintained in the range of 4 to 6 %;
further comprising at least one of the following:
i) passing nitrogen gas through lift 1 between regenerator [201] and 1st reactor [202];
ii) passing nitrogen gas through lift 5 between 4th reactor [205] and the regenerator [201]; and
iii) passing hydrogen gas for lifting the catalyst through lift 3 between the 2nd reactor [203] and 3rd reactor [204]; and through lift 4 between the 3rd reactor [204] and the 4th reactor [205].

In another embodiment, the four reactors are radial flow type reactors containing catalyst for cracking of naphtha feed, wherein the catalyst distribution among the four reactors is about 12%, 18%, 25%, and 45% respectively.

In another embodiment, in the regeneration unit, the catalyst is regenerated by means of an automated regeneration loop system.

In another embodiment, the present invention provides method for regenerating a reforming catalyst in a regeneration reactor operating in “BITE” burn mode, comprising: (referring to fig. 8)
(a) removing coke from the reforming catalyst in burning zone [301] and [302];
(b) Here the gases are obtained after removing of coke from burning zone. Gases are contacting the reforming catalyst with oxygen and chlorine in oxychlorination zone [303] containing oxygen content from 0.17 Vol% to 7.32 vol % (Refer 505AI1701.pv trend line in Fig 8)
(c) Oxy-Chlorination bed inlet temperature were operated at 403 to 448 degrees C (refer figure 8 trend line 505TI1908.pv) whereas in line ( normal white burn mode) it operated at 500 degrees C.
d) Oxy-Chlorination bed temperature varies from 341 degrees C to 446 degrees C (refer fig 8 trend line 505TI1906A.pv, 505TI1906F.pv) whereas in normally it is operated in range of 500 degrees C. As inlet temperature ( 505TI1908.pv) is reduced so bed temperature are also reduced.

In another embodiment, there is provided a quench line between two burning zone [301] and [302] to inject a small amount of cooling gas between the two burning zones, in addition of the air make-up flow. This injection will decrease the second burning zone inlet temperature and will allow proper control of this temperature. The catalyst is considered as free of coke at the bottom of the second burning bed if oxygen consumption is complete and if no temperature increase occurs.

In another embodiment, the method of regenerating reforming catalyst includes removing coke from the catalyst by burning in burning zone, re-dispersing catalytic metals such as platinum on the catalyst, oxidizing such catalytic metals, reducing such catalytic metals, replenishing catalytic promoters such as chloride on the catalyst in oxychlorination zone, and drying the catalyst in calcination zone.

In another embodiment, the process of regeneration of catalyst in CCR unit is carried out by starting with black burn mode (start-up mode) and smoothly shifting to white burn mode (In-line mode) wherein said smooth shifting is achieved by introduction of “BITE” burn mode that operates at specific temperature, O2 content, water conditions. “BITE” burn mode of operation is aggressive in one way as it does not allow the system to remain longer in Black Burn mode. At the same time it is conservative too as it allows the system in White Burn mode only after ensuring that coke burning is in order.

RESULTS:
A comparison between BITE burn and Black-White Step change was performed. The period taken for the trend is from 3rd march 2021 to April 10th 2021. Referring to Fig. 8, the left hand side of the Hairline 1, shows spikes caused due to the shift change from Black Burn mode to White Burn mode. It can be observed that there are numerous spikes in the trends of the Tags. The step change caused temperature of the regenerator beds/zones to rise sharply thereby leading back to Black Burn mode operation.
Post Hairline 2 in the trend, the trends are smoothened out as gradual increase in temperature was applied as per the BITE burn procedure. It was observed that the entire disturbance created due to frequent shifting from Black to White and vice versa was thus avoided.

Similar observation can be seen in Fig 9 also from 5th March to 30th March also.
a) Here clear cut there is variation in Oxychlorination bed temperature (refer trend line 505TI1906F.pv) from 443 C to 481 C & bed inlet temperature (refer trend line 505TI1908.pv).
b) Oxygen inlet flow increased from 0.31 vol% to 8.22 vol% (refer trend line 505AI1701.pv)
ADVANTAGES
1. Present invention provides safe set of operating condition which allow a CCR Unit to operate without much temperature excursion for handling abnormal situation.
2. Present invention provides method for quicker normalization of upset condition related to non- uniform coke formation on catalyst resulting in profitability of the unit. It provides Quicker transitioning with from Black Burn to White Burn leading to quicker stable unit and profitability of the unit.
3. “BITE” burn mode of the present invention enhances platinum dispersion over CCR catalyst. “BITE” burn mode conditions (temperature, oxygen concentration, catalyst circulation rates etc.) are more towards White Burn mode and thus are more favourable for better platinum dispersion.
4. Better maintenance of catalyst health by avoiding step change between two extremes (In-Line mode & Start-up mode refer fig 6.). This helps to maintain better platinum dispersion signifying sustained catalyst activity and potentially lower alpha-alumina formation. Possibility of formation of alpha-Alumina on platinum catalyst reduces significantly as sudden temperature excursions are avoided.
5. The method of the present invention has the potential to restore the Regenerator internal life due to more conservative operating conditions.
6. The method of regenerating catalyst of the present invention can be used in regenerator during start-up and normal running situations where coke burning is difficult to handle.
7. The “BITE” mode operation avoids major temperature fluctuation in Regenerator which is good for Regenerator internals. Regenerator being single line equipment of CCR Unit, any abnormality will hamper the unit operation adversely and Reformate production on sustained basis will not be feasible at all.
8. BITE” operation improves controllability on normal Regenerator parameters over conventional process significantly.

The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims. , Claims:1. A method for smooth shifting from black burn mode to white burn mode of regeneration zone of continuous catalyst regeneration (CCR) unit, wherein said method comprising:
a) providing a transition between black burn mode and white burn mode in regeneration zone through “BITE” burn mode, wherein said “BITE” burn mode includes;
i) burning of coke on catalyst in burn zone of regeneration zone, wherein said burn zone comprises of first and second radial zones operating at inlet oxygen content of 0.8 O2 mol %, and inlet temperatures of 480oC and 490-495oC respectively;
ii) providing chlorination gas to oxychlorination zone, operating with oxygen content of 0 (Start-up mode) to 4-6 vol% (In-line operating range) and circulates upwards at a temperature varies from 440 to 510oC (In-line operating range);
iii) providing calcination gas to calcination zone, operating with oxygen content from 0 to 8 - 12 vol% ( i.e In-line operating range) and circulates upwards at a temperature 440( Start-up mode) to 520oC( i.e In-line operating zone) ; and
wherein said “BITE” Burn mode is a part of continuous spectrum between black burn mode and white burn mode.

2. The method as claimed in claim 1, wherein said method includes starting of CCR unit in Black burn mode as per standard procedure after catalyst loading, and wherein said CCR unit operates at about 518-528oC RIT (reactor inlet temperature).

3. The method as claimed in claim 1, wherein said catalyst circulates at 350 Kg/hr, and wherein said coke present on the catalyst is maintained at a level of 4-6%.

4. A system comprising CCR unit for regenerating catalyst, wherein said CCR unit comprising of:
a) a reaction zone comprising of four reactors [202]-[205] with a catalyst lifting arrangement comprising nitrogen lift gas and hydrogen lift gas;
b) a regeneration zone comprising regenerator which contains two radial burn zone, a oxy-chlorination zone and a calcination zone, wherein said regenerator operates in “BITE” burn mode characterized by:
- Burning Zone 1 and Zone 2 with inlet O2 maintained at 0.8%;
- Zone 1 inlet temperature maintained at 480oC and Zone 2 inlet temperature maintained at 490-495oC;
- Oxy chlorination/Calcination temperature kept conservatively at least 100 degrees below normal;
- coke maintained in the range of 4 to 6 %;
further comprising at least one of the following:
i) passing nitrogen gas through lift 1 between regenerator [201] and 1st reactor [202];
ii) passing nitrogen gas through lift 5 between 4th reactor [205] and the regenerator [201]; and
iii) passing hydrogen gas for lifting the catalyst through lift 3 between the 2nd reactor [203] and 3rd reactor [204]; and through lift 4 between the 3rd reactor [204] and the 4th reactor [205].

5. The system as claimed in claim 4, wherein said reactors in step a) are radial flow type reactors, and wherein said reactors contains catalyst wherein the catalyst in 1st reactor [202] is about 12%.

6. The system as claimed in claim 4, wherein said reactors contains catalyst wherein the catalyst in 2nd reactor [203] is about 18%, and wherein said reactors contains catalyst wherein the catalyst in 3rd reactor [204] is about 25%, and wherein said reactors contains catalyst wherein the catalyst in 4th reactor [205] is about 45%.

7. The system as claimed in claim 4, wherein said regeneration zone of CCR unit operating in “BITE” burn mode, provides regeneration of catalyst by a process comprising:
(a) removing coke from the reforming catalyst in burning zone [301] and [302];
(b) contacting the reforming catalyst with oxygen and chlorine in oxychlorination zone [303] containing oxygen content of 4 to 6 vol% circulating upwards at a temperature of 510oC; and
(c) performing calcination in calcination zone [304] containing oxygen content of 8 to 12 vol% and circulates upwards at a temperature of 520oC;
wherein the gases obtained after removal of coke in burning zone [302].

8. The system as claimed in claim 4, wherein the two burning zone [301] and [302] are provided with quench line to inject a small amount of cooling gas between the two burning zones, in addition of the air make-up flow.

9. The system as claimed in claim 4, wherein said CCR catalyst is required to be unloaded in a definitive manner, sieved and loaded back with requisite quantity of fresh catalyst in order to eliminate undersized catalyst below 1.4mm of size.

10. The system as claimed in claim 4, wherein said regeneration of catalyst in CCR unit is carried out by starting with black burn mode (start-up mode) and smoothly shifting to white burn mode (In-line mode) wherein said smooth shifting is achieved by introduction of “BITE” burn mode.