MXPA00002759A - Staged catalyst regeneration in a baffled fluidized bed - Google Patents

Abstract

Staged combustion in a single regenerator of a FCC unit is disclosed. The regenerator has a spent catalyst distributor at the top of the catalyst bed, and an air grid at the lower end of the bed. A baffle separates the catalyst bed into upper and lower stages. Excess oxygen is present in the lower bed;partial CO combustion mode is maintained in the upper bed. The baffle inhibits backmixing flux to achieve sufficient staging to burn the catalyst clean under partial CO combustion. This achieves a clean burn of the catalyst in a single regenerator vessel in the partial CO combustion operating mode. Surprisingly, the baffle also reduces catalyst entrainment in the dilute phase, thereby cutting particulate emissions from the regenerator and reducing cyclone wear.

Description

REGENERATION OF CATALYST IN STAGES IN A FLUIDIZED BED WITH DEFLECTORS FIELD OF THE INVENTION The present invention relates to the generation of catalyst in catalytic disintegration units, more particularly, with a regenerative system that uses a fluidized bed with deflectors for the regeneration of the catalyst in two stages.

BACKGROUND OF THE INVENTION Improvements in fluid catalytic disintegration (FCC) technology have continued to make this conventional draft horse process more reliable and productive. In recent years, much of the activity in the development of the FCC has focused on the lateral reaction of the process. However, the importance of improving the design of the regenerator has increased due to the fact that most of the refineries process feed materials that contain waste and as the restrictions on environmental emissions have become stricter. The continuous regeneration of catalysts is a key element of the FCC process. This resets * * * -•" TO continuously catalytic activity burning the coal deposited on the catalyst and provides the heat required by the process. In the processing of high-residue feedstocks in FCC units, the regenerator must also remove excess heat generated by the high content of coal caused by contaminants in the feed. Ideally, the regeneration system meets these goals in an environment that preserves the activity and selectivity of the catalyst, so that the supply or backfill is minimized and the reactor performances are optimized. Environmental regulations on particulate and NOx emissions impose additional restrictions. The ideal regeneration system would regenerate the uniform catalyst at low carbon levels, minimize deactivation of the catalyst, reduce vanadium mobility and limit catalyst contamination, reduce particulate emissions, provide operational flexibility, offer high mechanical reliability, and reduce minimize complexity and capital costs. An important principle in the design of the regenerator is to minimize the mechanical size and complexity of the regenerator and its internal parts, in a manner consistent with compliance with the criteria for the operation of the process. FCC units that process high-waste feedstocks need to effectively treat heavy feed components rich in nickel, vanadium, Conradson Coal Residue (CCR). Although each of these pollutants affect the operation of the unit in different ways, the last two represent significant challenges for the design of the regenerator. The CCR in the feed increases the production of coal and can lead to excessively high generator temperatures. The heat must be removed from the system to achieve acceptably high oil to catalyst ratios and to avoid exceeding the metallurgical temperature limits of the regenerator. One option is to limit the heat release in the regenerator by operating in a partial CO combustion mode. The heat of CO combustion is released in a CO boiler downstream. Another option is to install a catalyst cooler. The excess heat is removed directly from the catalyst and used to generate high pressure steam. Although nickel and vanadium are deposited both quantitatively on the catalyst, nickel forms stable compounds which remain on the external surface of the catalyst. Older catalyst particles contain the highest levels of nickel. Vanadium is much more destructive than nickel. In the presence of high temperatures, excess oxygen, and steam, the catalyst inventory is redistributed, contaminating both the new catalyst and the catalyst and destroying the catalyst activity. This phenomenon reduces the equilibrium activity of the unit inventory because most of the catalytic activity is derived from the newer catalyst particles. The reactions that characterize vanadium mobility are the following: V205 generated in the oxidizing environment: 4V + 5 02 - >; 2 V205 Migration to other particles via volatile vanady acid: V205 + 3 H20 - > 2 V0 (0H) 3 To mitigate these effects, it is prudent to design the regenerator for the partial combustion of CO when processing materials with a high content of vanadium CCR. By restricting the vanadium mode, the premature deactivation of the fresh catalyst is prevented, the catalyst is equilibrated at a higher activity for a given metal level.

Operating the regenerator in partial CO combustion mode is an attractive option because (1) it reduces the rate of supply or catalyst filling by limiting the vanadium mobility in the regenerator and the deactivation of the vanadium-induced catalyst; (2) it can eliminate the need for a catalyst cooler when processing moderately contaminated feeds, or it can reduce the size of the catalyst cooler required for heavily contaminated feeds; (3) reduce the size of the regenerator container and the air blower; and (4) reduce N0X emissions. Unfortunately, there are disadvantages too. In a partial combustion operation, it is difficult to burn all the carbon from the catalyst. The residual carbon can have a negative effect on the activity of the catalyst. (For the purposes of the present specification and the claims, we will define "cleanly burned catalyst" as that which contains <0.1% by weight of carbon). At a C02 / C0 ratio of about 3.2: 1, the regenerated catalyst of a conventional single stage regenerator can contain 0.15-0.25% carbon. Figure 1 shows the relationship between the activity of the catalyst and the regenerated catalyst on the carbon.

In this example, the fall of the carbon level from 0.25% to 0.10% increases the activity in the MAT by approximately 3-4% by volume (by ASTM D-3907). One way to achieve the goal of clean burning the catalyst in a partial combustion operation is to use what is known in the art as two-step regeneration. In this type of design, multiple regenerator containers are operated in series with combustion gas trains either cascaded or separately. The first stage operates in partial combustion and the second stage operates in complete combustion. Although they can achieve low levels of catalyst on carbon, these two-stage designs are mechanically more complex, more expensive and more difficult to operate than a single-stage regenerator. U.S. Patent No. 4,615,992 to Murphy discloses a horizontal baffle device or underground grid 2 to 4 feet below the level of the catalyst bed in a regenerator operating in the full combustion mode. It is said that the deflection device limits the need for a distribution passage of the catalyst and aerators. Other US Patents of interest include 3,785,620 Huber; 4,051,069 to Bunn, Jr. Et al .; 4,150,090 to Murphy et al .; 4,888,156 Johnson; ,156,817 to Luckenbach; 5,635,140 to Miller et al .; and 5,773,378 to Busey et al. EPA 94-201,077 describes the radial distribution of fluid in a catalyst bed in a regenerator container.

BRIEF DESCRIPTION OF THE INVENTION We have invented a regeneration system which achieves the complete removal of carbonaceous deposits from the catalyst of catalytic disintegration of fluids used in a single regeneration container while operating in an incomplete combustion environment which could be achieved only in the technique previous using multiple regenerator containers. In addition, our system reduces the catalyst input in the diluted regenerator phase, thereby reducing particulate emissions and mechanical wear on regenerator cyclones. These benefits are achieved by placing a baffle in the regenerator to reduce back-mixing between the upper and lower sections of the fluidized bed. A distributor of the used catalyst, which evenly distributes the catalyst through the upper part of the upper bed is also an important part of the invention. In one aspect, the present invention provides a catalyst regenerator to remove - carbon from the catalytic fluid disintegration catalyst (FCC) circulated in a FCC unit. The regenerator includes a container comprising a dilute phase and a bed of dense phase fluidized catalyst placed in the respective upper and lower regions of the container. A catalyst distributor used to distribute the feed of the used catalyst is preferably provided radially outward from a tube or by its central, to the container adjacent to the upper part of the dense phase fluidized catalyst bed. An air grating is placed adjacent to the bottom of the fluidized bed of the dense phase catalyst to introduce oxygen-containing air fluid into the container. A baffle is placed between the catalyst distributor used in the air grille. The deflector can divide the dense phase bed into upper and lower stages, where the aeration fluid leaving the upper stage contains CO and is essentially free of molecular oxygen and the aeration fluid leaving the lower stage contains molecular oxygen and is essentially free of CO. Preferably, at least 40 percent, and more preferably at least 60 percent, of the catalyst in the fluidized bed of the dense phase catalyst is positioned above the vertical midpoint of the baffle. The back-mixing flow of the catalyst up through the baffle is preferably approximately equal to less than the slow or volumetric flow of the catalyst down through the baffle. The line is connected to an upper region of the container to discharge the aeration fluid from the diluted phase. A line is connected to a lower region of the container to remove regenerated catalyst from the dense bed. Preferably the discharged aeration fluid contains CO and is essentially free of molecular oxygen. The catalyst distributor used may include a plurality of aerated arms that radiate outward from the tube or central. The deflector is preferably a structured deflector made of angularly deformed, corrugated metal sheets. The baffle is preferably at least 6 inches (13.0 cm) thick, more preferably 2 feet (6 cm). In another aspect, the present invention provides a method for regenerating recirculated FCC catalyst in an FCC unit. The method includes supplying used FCC catalyst containing carbon deposited to the used catalyst distributor of the catalyst regenerator described above, and operate the catalyst regenerator in partial CO combustion mode. The midpoint of the deflector can divide the dense phase catalyst bed into upper and lower stage, where the lower stage is operated in an oxygen excess condition and the upper stage is operated in the partial combustion mode of CO, of so that the discharged air fluid contains CO sequentially free of molecular oxygen. The baffle and catalyst distributor preferably used inhibit backmixing between the upper and lower stages by at least 80 percent. The operation of the catalyst regenerator can be essentially free of catalyst cooling. The regenerated catalyst removed from the container preferably contains less than 0.05 weight percent carbon. In a further aspect, the present invention provides a method for converting an FCC unit catalyst regenerator comprising (1) a container comprising a dilute phase and a catalyst bed. dense phase fluidized placed in the respective upper and lower regions of the container, (2) a catalyst distributor used to distribute the used catalyst feed to the container adjacent to the top of the dense phase bed, (3) a air grille placed adjacent to the bottom of the bed of *** - -. «W» * "t i dense phase for introducing the oxygen-containing aeration fluid into the container, (4) the line connected to an upper region of the container for removing aeration fluid, and (5) a line connected to the lower region of the container for removing regenerated catalyst. The reconversion method includes installing a baffle in the dense phase bed below the used catalyst distributor and above the air grille, and operating the catalyst regenerator with at least 40 percent, preferably at least 60 percent, of the catalyst in the dense phase bed above the vertical midpoint of the baffle. The catalyst regenerator can be operated in the complete combustion mode of the retrofit and in the partial CO combustion mode subsequently. The catalyst regenerator can be operated in conjunction with a catalyst cooler before reconversion and without the catalyst cooler subsequently. The catalyst regenerator can be operated before and after reconversion to obtain regenerated catalyst containing less than 0.05 weight percent carbon. The rate of supply or catalyst filling is preferably lower after reconversion. The NOx in the discharged aeration fluid is preferably lower after reconversion. The catalyst input in the diluted phase is preferably lower after reconversion. The method may also include installing a downstream CO burner to convert the CO in the aeration fluid removed to C02. The feed material supplied to the FCC unit may have a high residue content after reconversion.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph of catalyst activity (MAT) as a function of the remaining carbon on the regenerated catalyst. Figure 2 (prior art) discloses a lower portion of a typical regenerator for burning coal from a used FCC catalyst. Figure 3 (prior art) is a plan view of the regenerator of Figure 2. Figure 4 shows the regenerator of Figure 2 modified to include the baffle according to one embodiment of the present invention. Figure 5 is an enlarged plan view of a section of the baffle of Figure 4. Figure 6 (prior art) shows a simplified flow diagram of the catalyst regeneration by kinetic modeling of the catalyst regenerator of the prior art. Figure 7 is a simplified flow chart of catalyst regeneration for the kinetic modeling of the two-stage deflector regenerator according to one embodiment of the present invention. Figure 8 shows FCC unit with a regenerator placed directly below the modified separator with a regenerator deflector according to an embodiment of the invention. Figure 9 shows an FCC unit with the regenerator placed on a modified separator with a regenerator deflector according to an alternative embodiment of the invention. Figure 10 shows an example of n solids mixing data if you, which graphs the indicator concentration in the bottom regenerator bed of the present invention as a function of time. Figure 11 graphs the regenerated catalyst over carbon versus the backmixed flow for different bed division ratios. Figure 12 graphs the relative input of catalyst to the diluted phase of the regenerator as a function of the surface evaporation rate with the catalyst distributor alone (SCD) alone (^ - -), and the deflector only (__¡-B-ß ) and deflector / SCD together (AAA).

DETAILED DESCRIPTION OF THE INVENTION The present invention is an apparatus and process for used catalyst regenerator. With reference to Figures 2-4, both regenerators of the prior art and of the present invention include a vertical tube 10 and a shut-off valve 12. The catalyst used in a conventional separator (see Figures 7 and 8) flows down the vertical pipe 10 and passes through the catalyst shut-off valve 12. After passing through the shut-off valve 12, the catalyst changes direction and flows up through the ring of the used central catalyst well 14 using air as the medium of fluidization. The catalyst is then evenly distributed over the top of the dense phase catalyst bed 16 via a multiple used catalyst distributor through the arms 18. The dense fluidized bed 16 is aerated by the air provided by the combustion air grids. 20, which are conventional in the art. When the aeration air moves towards '- X above the grids 20 through the dense phase bed 16, the carbon on the catalyst is burned to form CO and / or C02. The discharge gases are conventionally recovered in the upper part of the regenerator 22 via cyclones separators and a line of vapors projecting from the upper part (see Figures 7 and 8). Typically, when the regenerator 22 is operated in a partial combustion mode of C02, the line will be connected to a conventional CO burner (not shown) to convert the CO to C02 before discharging it to the atmosphere. According to the principles of the present invention, a baffle 24 is positioned to divide the catalyst bed 16 into an upper stage 26 and a lower stage 28. (See Figure 4). The operating differences between the regeneration of single-stage catalyst in the regenerator of the prior art 22 of Figure 2, compared to the two-stage regeneration in Figure 4, is observed by comparing the flow diagrams of Figures 6. and 7. In Figure 6, the catalyst used is introduced to the catalyst bed 16 which is generally modeled as a continuous stirred tank reactor (CSTR). The combustion gases are obtained in the upper part. The air is introduced into the bottom of the catalyst bed 16 and the regenerated catalyst is removed therefrom. In the I6" Two-stage operation according to the present invention (Figure 7), the used catalyst is introduced in the upper part of the upper stage 26, which is separated from the lower stage 28 by the deflector 24 see Figure 4). The combustion gases are obtained in the upper part of the upper stage 26. The regenerated catalyst is removed from the lower part of the lower stage 28 and the air is introduced to the lower part of the lower stage 28 as a version without deflectors. However, the upper stage 26 is separated from the lower bed by the deflector 24. The catalyst moves from the upper stage 26 to the lower stage 28, and the air moves from the lower stage 28 to the upper stage 26 through the deflector 24. The model includes retromixing the catalyst allowing some of the catalyst to move from the lower stage 28 back to the upper stage 26. The combination of the baffle 24 and the catalyst distributor used through the arms 18, preferably inhibits the back-mixing of the catalyst from the lower stage 28 to the upper stage 26 approximately at least 80 percent compared to the bed with baffles. This produces a true step combustion. The configuration l Counter current of the conventional regenerators provides a sufficient step effect to minimize the increase in the temperature of the catalyst particles and the associated deactivation, but the back-mixing between the upper and lower portions of the bed is too high to allow combustion by stages. With reference to Figure 6, as the backmixed flow approaches infinity, the regenerator 22 approaches a single-stage CSTR operation (see Figure 5). When the back-mixing flow of the catalyst approaches zero, the regenerator 22 approaches a true two-stage operation (see Figure 6). Any suitable baffle construction for the baffle 24 can be used, provided that it sufficiently inhibits back-mixing to obtain a two-stage operation of the regenerator 22, such as, for example, simple deflectors, separation plates or the like. As used in the present specification and claims, "inhibiting backmixing" means that the backmixing is reduced in relation to the operation of the regenerator 22 and in the baffle 24, but still using the used catalyst distributor and through the arms 18. A particularly preferred construction of the baffle 24 employs one or more "? 8" elements. packaging composed of corrugated sheets wherein the corrugations of the adjacent sheets are oriented in different directions, preferably more 45 degrees and less than 45 degrees from the vertical, as seen in Figure 5. These preferred deflection materials are used for conventional way for static mixing and are described in US Patent 3,785,620 to Huber which is incorporated herein by reference in its entirety. The baffle 24 is preferably at least 6 inches (15.24 cm) thick, more preferably at least 1 foot thick (30.48 cm) and especially at least 2 feet (61 cm) thick. The thicker baffle helps inhibit the backmixing of the catalyst in the regenerator. Generally, a larger regeneration bed needs a thicker baffle. The deflector regenerator bed should be designed for a surface vapor velocity between 0.5 and 7 feet / second (0.15 and 2.13 m / sec), preferably between 2 and 5 ft / second (0.61 and 1.54 m / sec) , and especially between 2.5 and 3.5 feet / second (0.76 and 1.07 m / sec). A higher surface vapor velocity would increase the vertical back-mix rate and could result in the catalyst not being burned cleanly. _- •. ** The catalyst distributor used can be any conventional device used for this purpose, but is preferably an aerated catalyst distributor. A particularly preferred autoairred catalyst distributor is disclosed in U.S. Patent 5,635,140 to Miller et al., Which is incorporated herein by reference in its entirety briefly, the Miller et al. Distributor includes a plurality of perforated arms at its 18 that radiate outward from the central well 14, where the through arms 18 have contiguous lips projecting downward to capture the aeration air and the floating forces force the aeration air captured through the perforations towards the passageway. We prefer to use 6-8 through arms 18. The bed separation ratio, ie the catalyst ratio in the upper stage 26 to the lower stage 28, using the vertical midpoint of the baffle 24, should be at least 40%. percent in the upper stage / 60 percent in the lower stage, preferably at least 60 percent in the upper stage / 40 percent in the lower stage, and especially 65 percent in the upper stage / 35 percent in the lower stage. In general, with an inventory in the upper stage 26 the regenerator 22 is more easily operated and has the flexibility to handle transient or sudden variations in the catalyst feed rate using the regenerator 22. The inventory of catalyst in the upper stage needs to be high enough to sustain the catalyst burning rate; If the inventory of catalyst in the upper stage is too low, it is more difficult to maintain combustion. Beyond this, we have also found that the higher the inventory in the upper stage, the less backmixing inhibition is usually required to obtain cleanly burned catalyst. For example, at a bed split ratio of 50 percent in the upper stage / 50 percent in the lower stage, a back-mixing flow inhibited by 90 percent may be required to burn the catalyst cleanly, whereas with a of 65 percent bedding in the upper stage / 35 percent in the lower stage, an inhibited backmixing flow of 73 percent can be tolerated. In the operation of the regenerator 22, a low C02 / C0 ratio in the combustion gases from the upper stage 26 is advantageous because it reduces the release of heat and consequently reduces the temperatures of the regenerator. On the other hand, operate the regenerator 22 in the partial combustion mode, a lower CO 2 / CO ratio can result in an increase in the amount of residual carbon left on the catalyst. In general, the lower the CO 2 / CO ratio, the lower the required catalyst cooling. In the preferred embodiment, the catalyst cooler can be removed all. On the other hand, the higher the CO 2 / CO ratio, the greater the backmixing flow that can be tolerated through the deflector 24 to obtain even a clean combustion. Typically the CO 2 / CO ratios range from 2 or less to approximately 6, more preferably from 2.5 to 4. We have also found that by increasing the inventory of catalyst in the regenerator 22, and using a deeper bed 16 with a diameter of Minor cross section helps achieve clean combustion. Regenerator 22 can be operated with or without a CO promoter, typically a catalyst such as platinum, which is commonly added to promote the conversion of CO to C02. Preferably the regenerator 22 is operated without a CO promoter in the catalyst to provide a regenerated low carbon catalyst. We have found that operation without a CO promoter allows higher backmixing flows to be tolerated and / or a smaller inventory / bed height of catalyst 16 possible. It is also possible in the present invention, as mentioned above, to completely eliminate the need for a catalyst cooler to cool the catalyst in the regenerator 22. We have found that the catalyst can easily be burned clean in the two-step operation of the regenerator 22 to a duty cycle with a low content or a catalyst cooler. On the other hand. The cooling of the catalyst helps reduce the temperature of the bed 16 as well as the rate of supply or catalyst fill. The cooling of the catalyst can also help to reduce the temperature difference between the upper stage 26 and the lower stage 28. Typically, the regenerator is operated from 1250 to 1350 ° C (676.7 to 732 ° C), preferably from 1275 to 1325 ° F (691 to 718 ° C). In general, the catalyst cooler is not necessary to process feed materials that produce a medium or low carbon delta (e.g. < 1% by weight of coal delta), but it would be desirable to process feed materials that would produce a high carbon delta (e.g. 1. 4% by weight). The "carbon delta" is understood in the art as the change in the carbon content on the £. * __) regenerated catalyst of the used catalyst fed to the regenerator 22, expressed as a weight percentage of the catalyst. We have also found that the baffle 24 does not interfere with the catalyst flow from the upper stage 26 to the lower stage 28, but restricts the backmixing, ie the flow from the lower stage 28 to the upper stage 26. There are no indications of that the deflector 24 causes flooding or any other catalyst flow problems. Furthermore, the density profiles are not affected by the baffle 24. The use of the baffle 24 allows a clean combustion of the catalyst in the partial combustion operation without an increase in the catalyst inventory. This clean combustion of the catalyst is achieved in a single container of simple regenerator, an achievement not possible with the previous regeneration technologies. The use of the baffle 24 also reduces the catalyst input, reducing the particle emissions of the regenerator 22 and reducing wear on the regenerator cyclones. The use of baffle 24 also has the advantage of minimizing the redistribution of vanadium over the catalyst because the bed temperature can be maintained around 1300 ° F (704 ° C) or n Minor and residence time in the presence of excess oxygen are minimized. Also, the inhibition of backmixing between the upper stage 26 and the lower stage 28 minimizes the presence of water vapor in the environment with excess oxygen from the lower stage 28.

EXAMPLE 1 A small scale cold flow regenerator model having a height of 5 feet (1.5 m) and a diameter of 8 inches (20.3 cm) was used to test the effect of the deflector of the static mixing element. Qualitatively, the small scale test showed that the baffle did not interfere with the catalyst flow from the upper stage to the lower stage, but restricted the backmixing. The small-scale test also indicated that there was no flood or other catalyst flow problem, and that the density profiles were not affected by the deflector.

EXAMPLE 2 A large FCC cold flow model was constructed and operated to show the functioning of the regenerator. The regenerator had a diameter of 5 feet (1.5 m), a bed height of 13 feet to 17 feet (3.97 m to 5.2 m), which had a catalyst inventory of approximately 20 tons, and required an air velocity of approximately 10,000 scfm. The mixing of solids in itself was measured by injecting an indicator into the top of the used rinser and measuring its concentration in the lower stage as a function of time. A typical data example is shown in Figure 8, which graphs the indicator concentration in the lower stage of the regenerator as a function of time. The raw data was analyzed in a 2-CSTR mathematical model to calculate the back-mixing flow. As shown in Figure 9, the 2-CSTR model provided an excellent fit of the data, verifying our assumptions of the hydrodynamic characteristics of the bed with deflectors. The particle velocity was measured by means of a cross-correlation technique of dual friberoptic probe. Mixing of the gas was measured using a helium indicator injected for 1-2 seconds in the aeration air grid at approximately 0.3% by volume. The catalyst input in the diluted phase was measured by the rate of accumulation in the deep part of the cyclone, as well as by the pressure transducer system. The density of the bed and the density profile were also measured by means of the pressure transducer system. r € The present baffle provided an unexpected result; reduced the catalyst input in the diluted phase. Repeated studies confirmed that the input was reduced by 57% compared to the catalyst distributor only without the baffle. It can be expected that this significant drop in the catalyst inlet will reduce the losses of the regenerator catalyst and the wear of the regenerator cyclone. Although the mechanism for the reduction of the entrance is not completely understood, we observed that the bubbles that belch on the surface of the bed were significantly smaller with the baffle installed. Smaller bubbles can decrease the amount of catalyst released to the diluted phase. The catalyst density profiles in the regenerator bed showed that the deflector did not interfere with the catalyst circulation. This was tested on a wide range of catalyst circulation speeds and surface air velocities. The deflection had no effect on the catalyst density profiles, confirming the observations in the small-scale model. Even at catalyst circulation speeds well above those found in the commercial service, we were unable to flood or overflow the deflector or disturb the flow of catalyst in some way. Although this unique design effectively restricts backmixing and limits bubble size, the preferred baffle has a very high percentage of open area (greater than 90%), giving excellent flow characteristics. Additional tests were conducted to simulate and abruptly interrupt the air blower. Under these conditions, the catalyst quickly entered through the baffle. The reflowing of the bed was achieved without incident in the repeated tests. The baffle is mechanically robust and can be easily mounted inside the regenerator.

EXAMPLE 3 On the basis of the solid and hydrodynamic mixing data obtained in the large scale model, we used the regenerator model described in "FCC Regenerator Flow Model", Chemical Engineering Science, vol. 45, no. 8, pp. 2203-2209 (1990) to simulate the operation of regenerator combustion with deflectors. This "rigorous kinetic model allowed us to divide the regenerator into any number of stages or" cells "and provide the complete specification of the flow of gas and catalyst between the cells Comparisons of model predictions with commercial operation have shown that the model is a useful tool for both regenerator design and analysis Once the experimentally determined back-mixing flows and other operating data were fed, the model was suitable for predicting key parameters such as carbon regenerated catalyst, bed temperatures and Diluted phase, and combustion gas compositions The results obtained in the large-scale model show that the deflector of the present invention reduced backmixing in a partial combustion regenerator with a bed temperature of 1300 ° F (704 ° C). ) and a C02 / CO ratio of 2.66, by more than 81% At this level of retromezclad or, the kinetic model of the regenerator verifies that the system achieves the combustion in stages in a single regenerator and that the catalyst burned cleanly in a partial CO combustion environment. An unexpected result was the reduction of NOx in the combustion gas discharged from the regenerator. The operation with the baffle reduced the NOx emissions by more than 50% in relation to the regenerator if baffle.

EXAMPLE 4 The large scale regenerator model of Example 2 was operated with and without a 2 foot (61 cm) thick baffle at different surface gas velocities to determine the backmixing flow in the regenerator. The results are presented in Table 1.

TABLE 1 TABLE 1 (continued) The data show that the vertical back-mix velocity of solids for the regenerator bed without deflector was 100 'percent of the base at the regenerator design operating conditions (3.3 ft / s (1.0 m / s); deflector), but dropped to 79 percent of the base when the surface gas velocity was reduced to 1.6 ft / s (0.49 m / s). Is It is possible that the data of the regenerator without baffle were more dispersed than in the regenerator with baffle due to the greater fluctuation of bubbles and pressure, greater. The back-mixing in the regenerator with deflector was around 18-19 percent of the base on the gas surface velocity range of the design of 1.8-3 ft / s (0.5-0.91 m / s), and was in the same order as the volumetric or net flow of the catalyst down, through the regenerator bed . The only slight decrease in back-mix flow in the baffled regenerator while the velocity shifted from 3 ft / s (0.91 m / s) to 1.8 ft / s (0.5 m / s) can be explained by the speed of the damping effect of the baffle of the mixing of the gas on the back-mixing of the solids. The increase in backmixing as the gas velocity increases is consistent with other data reported in the art.

EXAMPLE 5 To verify the "robust" behavior of the 24"(61 cm) baffle in the regenerator, a" robustness "test was conducted in the large regenerator model of Example 2. Under the normal operating conditions of the design, the Air to the regenerator bed with the baffle with a 24"(61 cm) baffle depth was instantly interrupted. After the bed was completely defluidized (approximately 10 minutes), the bed was ripped off again at the normal operating surface velocity of 3 feet per second (0.91 m / s). The densities of the bed in the regenerator were recorded before lowering the bed and after restarting the compressor.

It was found that most of the catalyst drained from the upper stage to the lower stage during defluidization of the bed. The density profiles of the axial bed are the same, indicating that the bed can be complemented defluidized, and that the system is robust in this regard. It was also confirmed that neither in the 5-foot (1.5 m) large unit of Example 2 nor in the 8-inch (20.3 cm) small unit of Example 1, there were flow problems, such as flooding, channeling or obstruction with the baffle .

EXAMPLE 6 Two different bed split ratios were simulated, 50% at the top / 50% at the bottom and 65% at the top / 35% at the bottom, using the simulator model of Example 3. The The regenerator geometry and the operating conditions used for the simulation are listed in Table 2 below: TABLE 2 ? TABLE 2 (continued) Figure 11 illustrates the level of CRC (regenerated catalyst on carbon) simulated versus the rate of backmixing in the regenerator. At a bed splitting ratio of 50% at the top / 50% at the bottom, an inhibition of the back-mixing flow of 90% was required to clean the catalyst cleanly (with a CRC level of <0.1% in weight) . However, I can only tolerate a 73 percent inhibition of the backmixing flow to cleanly burn the catalyst at a C02 / CO ratio of 6.33 when the inventory of catalyst in the upper bed reached 65%. So, the baffle is more preferably installed in the place that has more than 65% catalyst in the upper bed to burn the catalyst cleanly.

EXAMPLE 7 The results of studies of more than 20 cases using the kinetic model of the regenerator of Example 3 provided sufficient quantitative data to arrive at the conclusion that the deflector system can successfully achieve the technical goals of a catalyst regeneration with a container of the single regenerator / FCC in two stages, simple, in partial CO combustion mode. With the deflector regenerator of this invention, the catalyst can be burned cleanly and the regenerator operated in the partial CO combustion mode at the same time. The diameter of the lower bed used for the following simulations was 24 feet (7.3 m) and the level of the bed was 17 feet (5.2 m). However, a typical conventional full combustion regenerator bed may have a bottom bed diameter of 27 feet (8.2 m) and a level of of bed of 13 feet (4 m). Table 17 presents the preferred regenerator configurations and the operating conditions used to design regenerators with deflectors (partial combustion) and without deflectors (complete combustion): TABLE 3 TABLE 3 (continued) EXAMPLE 8 In this example, the large cold flow model of Example 2 was operated with a surface vapor velocity ranging from 1.5 (0.45 m / s) to about 3.5 ft / s (1.06 m / s). Catalyst entry in the diluted phase was measured by manometer readings near the regenerator cyclone inlets. The regenerator model was operated with a used catalyst distributor (SCD) only, with the baffle 24 inches (61 cm) only and with a deflector and the SCD. The results are presented graphically in Figure 12. When both the deflector and the SCD are used, the input is surprisingly reduced much more than can be obtained with either the deflector or the SCD alone.

EXAMPLE 9 In this example, we simulated the operation of the regenerator in the partial combustion mode (C02 / CO ratio of 2.66) using the kinetic model of the regenerator of Example 3 to compare the operation with a deflector and a used catalyst distributor (SCD). ) together, with the baffle only, and with the SCD only. The level of the catalyst bed, the catalyst inventory, the combustion air velocity, the surface vapor velocity, the bed division ratio in the cases of deflector / SCD and baffle only (65% in the top / 35% in the lower part), and the speed of catalyst circulation were the same in the three simulations. No catalyst cooler required. The deflector / SCD simulation was able to burn the catalyst cleanly to a regenerated catalyst on carbon (CRC) of 0.05% by weight, while the cases with baffle only and SCD only resulted in CRC levels of 0.11% by weight and 0.20% by weight, respectively. The regenerated catalyst for the cases of deflector only and SCD could only, correspondingly, have decreased much more the activity (MAT) than the regenerated catalyst with baffle / SCD (see Figure 1).

EXAMPLE 10 In this example, the kinetic simulator of Example 3 was used to study an existing FCC regenerator originally designed to process a VGO feed material. The used catalyst distributor regenerator (SCD), but not the baffle. The regenerator operated in full combustion mode to obtain cleanly burned catalyst. After the FCC unit was built the refiner increased the Conradson Carbon content of the feed material from 1% to 3%, and the air blowers were increased to their maximum limit. This operation of the base case is shown in the first column of Table 4 below. 39 TABLE 4 To increase the content of Conradson Coal, anything additional, say up to 5%, would require the unit to change from a complete CO combustion mode to a partial combustion mode. In the second column of Table 4, we show what would be expected if a heavier feed material were processed and the unit fell into a partial combustion mode. The catalyst regenerated on carbon would be increased to about 0.20% by weight. This would reduce the catalytic activity of the regenerated catalyst by about 4% by volume - a significant loss of activity that would adversely affect the yields of the desired products such as gasoline. In the last column of Table 4 we show what would be expected if a deflector were added to the unit and the unit was operated at the same conditions shown in the middle column. The addition of the deflector allows the catalyst to be burned at the same level of the coal that was previously achieved with the lightest feed material modeled in the first column. The description . and previous examples are merely illustrative of the invention and should not be construed as limiting the scope of the invention. Various modifications will be apparent to those skilled in the art in view of the above description. It is intended that all those modifications that fall within the scope and spirit of the appended claims will be encompassed hereby. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (23)

2 CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A catalyst regenerator for removing spent fluid catalytic disintegration catalyst (FCC) coal, circulated in an FCC unit, characterized in that it comprises: a container comprising a dilute phase and a bed of dense phase fluidized catalyst placed in the upper and lower regions. respective bottoms of the container; a catalyst distributor used to distribute the spent catalyst feed to the adjacent container in the upper part of the dense phase fluidized catalyst bed; an air grating placed adjacent the bottom of the fluidized bed of the dense phase catalyst to introduce oxygen-containing aeration fluid to the container; a deflector placed between the spent catalyst distributor and the air grille, where at least 40 percent of the catalyst in the bed of 13 • * Íßr * dense phase fluidized catalyst is placed above the vertical midpoint of the baffle; a line connected to an upper region of the container for discharging the aeration fluid from the diluted phase; a line is connected to a lower region of the container to remove regenerated catalyst from the dense bed.

2. The catalyst regenerator according to claim 1, characterized in that the discharged aeration fluid contains CO and is essentially free of molecular oxygen.

3. The catalyst regenerator according to claim 1, characterized in that the catalyst distributor used comprises a plurality of arms aerated therethrough which radiate outwardly from the central well tube.

4. The catalyst regenerator according to claim 1, characterized in that at least 60 percent catalyst in the dense phase catalyst bed is placed above the midpoint of the baffle.

5. The catalyst regenerator according to claim 1, characterized in that the baffle comprises a structured baffle made of corrugated, angularly deformed metal sheets. The catalyst regenerator according to claim 5, characterized in that the baffle is at least 6 inches (15.24 cm). The catalyst regenerator according to claim 5, characterized in that the baffle has a thickness of 2 feet (61 cm) or more. A method for regenerating fluid catalytic disintegration catalyst (FCC) circulated in an FCC unit, characterized in that it comprises: supplying used FCC catalyst containing carbon deposited in the catalyst distributor used of the catalyst regenerator according to claim 1; operate the catalyst regenerator in partial CO combustion mode. The method according to claim 8, characterized in that the midpoint of the deflector divides the dense phase catalyst bed into upper and lower stages, where the lower stage is operated by a condition with excess oxygen and the lower stage is operated in a partial CO combustion mode, so that the aeration fluid of "415 discharge contains CO and is essentially free of molecular oxygen. The method according to claim 9, characterized in that the deflector and the catalyst distributor used inhibit the backmixing between the upper and lower stages at least about 80 percent. The method according to claim 9, characterized in that the operation of the catalyst regenerator is essentially free of catalyst cooling. The method according to claim 9, characterized in that the regenerated catalyst removed from the container contains less than 0.05 weight percent carbon. 13. A method for converting a catalyst regenerator from a catalytic decay unit (FCC), compris(1) a container comprisa dilute phase and a dense phase fluidized catalyst bed placed in the respective upper and lower regions of the container, (2) a catalyst distributor used to distribute the used catalyst feed to the container adjacent to the top of the dense phase bed, (3) an air gratplaced adjacent to the bottom of the dense phase bed to introduce the oxygen-containaeration fluid to the container, (4) a line connected to an upper region of the container for dischargaeration fluid, and (5) a line connected to the lower region of the container for removregenerated catalyst, characterized in that it comprises: installa baffle in the dense phase bed under the used catalyst distributor and on top of the air; operate the catalyst regenerator with at least 40 percent of the catalyst in the dense phase bed above the vertical midpoint of the baffle. The method according to claim 13, characterized in that the regenerator of the catalyst is operated in the complete combustion mode before reconversion and the CO partial combustion mode subsequently. 15. The method according to claim 13, characterized in that the regenerator of the catalyst is operated in conjunction with a catalyst cooler before reconversion and without the catalyst cooler thereafter. 1

6. The method according to claim 13, characterized in that the catalyst regenerator is operated before and after the conversion '41 to obtain regenerated catalyst containing less than 0.05 weight percent carbon. 1

7. The method according to claim 13, characterized in that the rate of supply or filling of catalyst is lower after reconversion. 1

8. The method according to claim 13, characterized in that the NOx in the removed aeration fluid is smaller after reconversion. 1

9. The method according to claim 13, characterized in that the catalyst entry into the fluid of the diluted phase is lower after reconversion. 20. The method according to claim 13, characterized in that it further comprises installing a downstream CO burner to convert the CO in the aeration fluid withdrawn to C02. 21. The method according to claim 13, characterized in that the feedstock supplied to the FCC unit has a higher residue content after reconversion. 22. A catalyst regenerator to remove carbon from catalytic decay catalyst (FCC) ** fluid, used, circulated in an FCC unit, characterized in that it comprises: a container comprising a diluted phase and a bed of dense phase fluidized catalyst placed in the respective upper and lower regions of the container; a catalyst distributor used to distribute the spent catalyst feed to the adjacent container in the upper part of the dense phase fluidized catalyst bed; an air grating placed adjacent to the bottom of the fluidized bed of the dense phase catalyst to introduce aeration fluid containing oxygen into the container; a baffle placed between the spent catalyst distributor and the air grating that divides the dense phase bed into upper and lower stages, where the aeration fluid leaving the upper stage contains C02 and is essentially free of molecular oxygen and the aeration leaving the lower stage contains molecular oxygen and is essentially free of C02; a line connected to an upper region of the container for discharging the aeration fluid from the diluted phase; a line is connected to a lower region of the container to remove regenerated catalyst from the dense bed. The regenerator according to claim 22, characterized in that the back-mix flow through the baffle is approximately equal to or less than the net flow of the catalyst passing down through the baffle. * "