FI58265C - REGENERERINGSFOERFARANDE FOER FLUIDISERAD KATALYSATOR - Google Patents

Description

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C (45) Patent granted 12 01 Ivöl Patent treddelat V 'V (51) K ».lk? /Lnt.CI.3 B 01 J 23/90 FINLAND —FINLAND (21) 1739/73 (22) HkkwnlsptWt —Amftknlngadtg 29 -05-73 (23) AlkupWvt — GHtl | h «tsdi« 29-05-73 (41) Tullut JulkMul - Bltvlt offmcllg 01-12-73 PKtMitCl · and registry-controlled NihtivtWp ™ j. kuuLfulk »»,

Patent- och registerstyralsan 'AiwMon uthjd och uti.tkdfMn pubik «r» d 30-09-80 - · (32) (33) (31) Privilege requested —Begird priorac 30-05-72 30-05-72, 08- 06-72 USA (US) 2580Ul, 2580I12, 263399 w '' (71) Universal Oil Products Company, Ten U0P Plaza, Algonquin & Mt. Prospect Roads, Des Plaines, Illinois 6O0l6, USA (72) Laurence Oliver Stine, Western Springs, Illinois, Algie James Conner,

This invention relates to the treatment of hydrocarbons in which a fluidized catalyst is continuously recycled to a reaction zone in which the liquid is reacted. -at it, and a separate regeneration zone where its activity is restored by removing these deposits.

In particular, this invention relates to a regeneration process suitable for the oxidative removal of hydrocarbonaceous deposits from a fluidized catalytic cracking catalyst.

^ Best regeneration can be performed by completely burning the CO generated in the regenerator in the regeneration. The temperature of the regenerated catalyst is preferably controlled. The present invention further makes it possible to completely burn carbon monoxide to carbon dioxide in a regenerator, thereby producing a catalyst with a controlled amount of carbon black.

In one known process, hydrocarbons boiling in a liquid at a relatively high temperature are catalytically cracked into lighter hydrocarbons boiling in the region of heating oil and gasoline, or lighter. In one or more reaction zones, the feed is contacted with a particulate cracking catalyst maintained in a fluidized state.

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The gases leaving the reaction zone are introduced into the product recovery zone, while the catalyst is generally introduced into the stripping zone to remove the hydrocarbons to be stripped from the particles. The stripped catalyst is then fed to a fluidized regeneration zone where the non-stripping hydrocarbon-containing substance is contacted with an oxygen-containing gas, usually air, to burn off most of the carbon on the catalyst.

Regenerations in the past have generally been performed in a single dense phase mattress on the bottom of the regenerator. The catalyst entrained in the exhaust gas leaving the dense mattress is generally recovered by passing this exhaust gas through cyclones arranged in a relatively large dense separation space above the dense mattress. Some catalyst is always physically lost from the regenerator.

Surface velocities in known regenerators are generally about 0.45-1.8 m / sec, usually 0.45-0.9 m / sec. The lag time of the catalyst in the regenerator is usually 2 to 5 minutes, preferably 2 to 3 minutes, with a gas delay time of generally about 10 to 20 seconds.

It was known to control the air flow to the regenerator in order to maintain a pre-regulated temperature difference between the gas separation space and the dense mattress to minimize excess oxygen and limit the afterburning to carbon dioxide in the carbon monoxide separation space. Generally, only about 0.1-1% oxygen was present in the exhaust gas. The exhaust gas, which contained a lot of carbon monoxide, was vented to either air or a carbon monoxide boiler and used as fuel.

Typical daily catalyst addition rates were about 0.5-2.0% of the total catalyst. The catalyst appears to be largely lost due to abrasion against the other catalyst, so the catalyst loss is almost proportional to the amount of catalyst. Catalysts are relatively expensive and attempts have been made to drastically reduce the amount of catalyst starting to reduce catalyst loss.

In addition, in prior art units, it was usually impossible to vary the temperature of the regenerated catalyst. Also, in known embodiments, it was never possible to achieve very complete CO combustion in the regenerator and at the same time allow the amount of carbon scum on the regenerated catalyst to be controlled.

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Since most of the amount of catalyst is in the regenerator, the purifiers have tried to reduce the amount of catalyst in the regenerator by using the regenerator at high carbon burning rates. Recently, higher pressures and temperatures have been used to achieve higher combustion rates. Regeneration pressures of about 3-3.7 ik and temperatures of about 620-675 ° C are now common. A slight reduction has been achieved, but at the expense of higher equipment costs due to higher pressures and increased catalyst deactivation, due to the long delay time in high temperature space regenerators.

One known process uses countercurrent regeneration, in which the spent catalyst is partially regenerated in the first fluidized bed with partially used regeneration gas, further regenerated in the transfer tube with fresh regeneration gas, and then passed to a second fluidized bed where further regeneration can take place. Preferred surface velocities are 0.75-0.9 m / sec. Preferred temperatures are about 593-635 ° C. No post-combustion of carbon monoxide to carbon dioxide is mentioned, but the "substantially complete" removal of carbon is considered to be less than 0.2% and possibly as low as 0.1%. The regenerated catalyst can then be liberated from the oxygen-rich gases in a separate stripping zone with steam or exhaust gas.

In another known process, the catalyst is partially regenerated in the first dense bed with the first oxygen-containing gas and further regenerated in the second dense bed with the second oxygen-containing gas. Above both dense mattresses there is a common dilute phase. The surface velocities are preferably about 0.6-1.35 m / sec. and temperatures preferably about 607-732 ° C. This process adjusts the air flow to the regenerator to ensure that only a small amount of carbon monoxide afterburning occurs.

The method of the present invention uses higher rates and higher oxygen concentrations than previously known designs. Sufficient fresh regeneration gas is added to burn the carbon monoxide almost completely. This differs from the prior art in that the amount of fresh regeneration gas was limited to that required for a limited small controlled afterburner. Thus, higher oxygen concentrations and higher temperatures as well as karstic combustion rates are obtained. without a pollution problem without a CO boiler and also reduces the need to preheat the feed.

The process of the present invention preferably provides complete combustion of the carbon monoxide and the additive to be combusted in a dilute phase transport riser to heat the regenerated catalyst to a predetermined temperature.

The present invention further allows, by separating CO oxidation (which occurs primarily in the dilute phase transport riser) from carbon black oxidation (which occurs primarily in the first dense bed), the addition of regeneration gas to control carbon black oxidation rather than limiting carbon monoxide afterburning.

Accordingly, the invention provides a process for regenerating a hardened particle from a spent catalyst removed from a hydrocarbon conversion zone, and the main features of the invention appear from the appended claim 1.

In a preferred embodiment, the carbon monoxide burns completely to carbon dioxide in the regenerator.

In another embodiment, temperature control of the regenerated catalyst is possible by adding the combustible liquid to the dilute phase transport riser or to the first sealed mattress or both.

In a further embodiment, control of the degree of scaling of the regenerated catalyst is possible by limiting the oxidation of the carbon scale in the first dense bed by still burning carbon monoxide in the dilute phase transport riser.

Other embodiments will become apparent from the detailed description below.

The invention will now be described in more detail with reference to the drawings, in which Figure 1 schematically shows a particular device suitable for carrying out the present invention and Figures 2 and 3 show alternative devices also suitable for carrying out the invention, Figure 3 shows how the invention can be applied to an existing recovery vessel.

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Figure 1 shows a regeneration device 100. The first dense mattress 1 is connected via a transfer zone 28 to the other end of the vertical dilute phase riser 2. The catalyst gas separation device 3 is connected to the outlet 7 of the transfer riser 2. The regeneration gas from the separation device 3 enters the separation space 5, then to the separation device 4 and then exits at 26 to the pressure chamber 27 · The gas exits the chamber 27 . The separated catalyst from the separators 3 and 4 is led to a second sealed mattress 6.

The spent catalyst enters the first sealed mattress "1 through the pipe 9. The surface of the mattress 1 shown in point 10 is in the transfer zone 28 between the mattress 1 and the riser 2. Fresh regeneration gas enters the mattress 1 through the distributor 12 dispersing the gas into the mattress 1. Since air is preferred, the invention will be described below in connection with the use of air, but this statement does not preclude the use of other seasonal mixtures, as the present invention also works well with oxygen-enriched or oxygen-poor air.The dispensing device 12 may be a metal plate with holes or slits, or Preferably, both types of dispensers are well known.Controlled oxidation of carbonaceous karsts takes place in the dense mattress 1. Gas and catalyst are conveyed from the mattress 1 through the transfer zone 28 to the transport riser 2 where oxidation of carbon monoxide can take place.

The riser 2 is vertical and its inlet is at the bottom and the outlet 7 is near the top. The outlet 7 may be one or more openings located at or near the upper end of the riser 2 to allow the catalyst and gas to enter the separation device 3. The separation device 3 connected to the outlet 7 is usually a cyclone separator which substantially separates the gas from the accompanying catalyst. The separator 3 may have 1 to 4 cyclones. Substantially catalyst-free gas passes through the outlet 13 as the catalyst flows through a sink pipe 14 directed towards the second sealed mattress 6. The separation device 3 can be dispensed with to allow the gas leaving the outlet 7 and the catalyst to enter the space 5. The gas can be separated to some extent from the catalyst, but not as much as with the cyclone 3 »as shown.

The separation device 4, which is usually a cyclone, has an inlet 16 which receives the regeneration gas and the accompanying catalyst from the space 5 · The gas and the accompanying catalyst are then substantially separated from each other. The gas leaves the regenerator through the outlet 26, the pressure chamber 27 and the outlets 8 and 8 '. The catalyst separated from the gas is led downwards through the immersion pipe 17 to the second sealed mattress 6. One separation device 4 is shown, but more than one can be used.

The immersion tubes 14 and 17 of cyclones 3 and 4 preferably have catalyst outlets above the dense mattress of the catalyst. Submersible outlets may include a flap valve at the catalyst outlets to prevent gas and catalyst from flowing up the downcomer. Cyclones are designed to operate with open immersion tubes, because if the immersion tubes were "closed" with a tight catalyst bed, the cyclone separation would vary with tight mattress height variations. Thus, the cyclone separation remains constant with the immersion tubes 14 and 17 even if the height of the tight mattress varies. The sinkers 14 and 17 may protrude into the sealed mattress, but this is not preferred.

A combustible fluid such as fuel gas or liquid hydrocarbon can be added to the riser 2 via a pipe 20 and a distributor 21. Combustion of such a fluid aids in initiating the process and initiating the afterburning of carbon monoxide in riser 2. Combustion of this combustible material preferably raises the temperature of the catalyst passing through the riser, allowing the temperature of the regenerated catalyst to be controlled.

The second air flow can be led to the riser 2 through the pipe 18 and the distributor 19 to supply oxygen and to maintain the combustion of the added combustible fluid or carbon monoxide.

The height of the catalyst 15 of the second dense mattress 6 is sufficient to overcome the pressure drop in any of the regenerated catalyst outlet 22, the control valve 23 and the following devices.

The tight mattress can be above, below or next to the tight mattress 1. Likewise, the entire regenerator may be above, below or on the side of the reactor using the regenerated catalyst.

The dense mattress 6 may be a stripper as in Figures 1, 2 and 3 or may simply assemble a sufficiently regenerated catalyst in a dense mattress for "pressure" and barrier purposes without stripping.

The catalyst in the mattress 6 moves downwards through a pipe 22 and through a valve 23 which controls the exit of the catalyst from the nozzle 6. The valve 23 is usually a slide valve controlled by a reactor temperature controller or height controller.

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The stripping medium can be added to the second sealed mattress 6 through the tube 24 and the distributor 25 to strip the regenerated gas adsorbed and in the intermediate spaces from the regenerated catalyst. Superheated steam is a preferred stripping medium.

Most of the catalyst in the regenerator 2 is preferably in the dense mattress 1, with a smaller part in the dense mattress 6. When steam stripping is used in the mattress 6, the catalyst delay time in this mattress should be less than 1 minute, preferably less than 30 seconds.

Figure 2 shows an alternative device 200 for practicing the present invention.

The spent catalyst enters the first sealed mattress 201 through the inlet pipe 209. The catalyst surface at 210 is in the transfer zone 228. Air is supplied through the tube 211 and distributor 212 to the dense mattress 201. Controlled oxidation of the carbonaceous karsts occurs in the dense mattress 201, allowing the amount of regenerated catalyst karst to be adjusted. The gas and catalyst exit, from the mattress 201 through the transfer zone 228 to the transport riser 202, where oxidation of carbon monoxide can occur.

The transport riser 202 is vertical, with its inlet at the bottom and near the top of its outlets 207 and 207 *. Outlets 207 and 207 * are at or near the top of riser 202 and allow catalyst and gas to escape from riser 202. Separation devices 203 and 203 ', which are usually cyclones, are connected to outlets 207 and 207'. These cyclones substantially separate gas from the catalyst. . Gas exits the cyclones through outlets 213 and 213 '. The substance in the separation space 205 is essentially a gas with some entrained catalyst. The catalyst exits the cyclones through immersion tubes 2Ih and 214 'down to a second dense mattress 206 having a surface at 215. The immersion tubes 214 and 214' may extend below surface 215, although not shown in Figure 2.

Cyclones 203 and 203 'are not required, so that the catalyst-gas separation, after leaving the riser 202, decreases slightly in efficiency. This would increase the catalyst remaining in space 205 and thus increase the load on the separation device 204.

The separator 204 is usually a cyclone. It has an inlet 216 which receives the gas and the accompanying catalyst from the separation space 205. The gas and the catalyst are substantially separated from each other. The gas exits the cyclone 204 and the regenerator 200 through an outlet 208. The catalyst exits the cyclone 204 through the immersion tube 207 down to the second sealed mattress 206.

The combustible fluid may be added externally to the riser 202 through the tube 220 and manifold 221 for start-up or to raise the temperature in zone 2 sufficiently to initiate post-combustion or possibly through the riser to raise the temperature of the falling catalyst. Air can be supplied through line 218 and manifold 219 to provide the oxygen required for combustion in riser 202. Alternatively, gas may be fed through line 218 to cool the catalyst to a predetermined temperature if desired.

The surface 215 in the mattress 206 is high enough to maintain the pressure of the regenerated catalyst high enough to overcome the pressure drops in the outlet pipe 222, the control valve 223, and subsequent devices. Surface 215 can be adjusted to provide the desired catalyst lag time in the mattress.

The catalyst in the mattress 206 moves downward and out of the regenerator 200 through the tube 222. The catalyst discharge rate control valve 223 is a spool valve controlled by a reactor temperature controller or level controller.

A stripping medium, preferably superheated steam, may be fed to the mattress 206 through tubes 224 and 224 'and through manifolds 225 and 225' to strip out the adsorbed and intermediate regeneration gas.

As shown in Figure 1, most of the catalyst in the regenerator 200 is in the first dense mattress. Likewise, if the steam stripping takes place in the second dense mattress, the catalyst has a delay time of less than 1 minute, preferably less than 30 seconds.

Figure 3 shows a possible modification of existing Regenerators to provide a device suitable for carrying out the present invention. The existing regenerator 300 is modified primarily to provide a first sealed mattress 301, a dilute phase transport riser tube 302, and a second sealed mattress 306.

The spent catalyst enters the mattress 30] through the inlet pipe 309, where the surface is at 310 in the transfer zone 328 between the mattress 301 and the riser 302. Air is supplied through line 311 and manifold 312. The oxidation of the carbon scale takes place in a dense mattress 301. The gas and the fluidized catalyst are removed from the mattress 9 58265 301 through a transfer zone 328 to a riser 302 where oxidation of carbon monoxide can take place.

The combustible fluid can be fed to the riser 302 through the manifold 321 of the pipe 320 to heat the catalyst in the riser. Additional air can be supplied to the riser 302 through the pipe 318 and the manifold 319.

The catalyst and gas exit the riser 302 through the outlet 307 to the separation space 305. The outlet 307 is not a cyclone. The outlet 307 preferably sprays the catalyst and gas downward to reduce the amount of catalyst remaining in the space 305.

The separator 304, which is usually a cyclone, has an inlet 316 and receives gas and entrained catalyst from space 305 · Gas exits the cyclone 304 and regenerator 300 through the outlet 308. The catalyst exits the cyclone 30 * 1 through a plunger tube 317 down to the second sealed mattress 306. The surface 315 defines the boundary between the second sealed mattress 306 and the separation space 305.

The catalyst in the mattress 306 moves downward and exits the regenerator 300 through a tube 322. The catalyst outlet is controlled by a valve 323 controlled by a reactor temperature or height controller.

A stripping medium, preferably superheated steam, may be added to the mattress 306 through a tube 324 and a distributor 325 to strip the regeneration gas from the regenerated catalyst.

The process of the present invention operates with well known fluidized catalytic cracking catalysts. Highly active zeolite catalysts are preferred due to their resistance to high temperatures, steam and metals in the feedstock. Amorphous catalysts can also be used, for which the present invention is particularly suitable, because the shorter catalyst delay times used in this process extend their service life.

The feedstocks used in this process may be conventional or may contain even higher amounts of impurities, such as Conradson carbon and metals such as nickel, iron and vanadium, than are found in conventional feedstocks.

The high-carbon feedstock measured by Conradson carbon analysis reduces the capacity of units constrained by regeneration capacity. Regeneration temperatures also tend to rise with carbon content. The metals in the feed also deposit with the catalyst, causing it to produce less gasoline 10,582,65 and more carbon black and light gas, and deactivate the catalyst. To minimize Conradson carbon and metals, vacuum distillation, asphalt removal, viscosity reduction, and coking are often used to make suitable feedstocks for catalytic liquid cracking.

Typical feedstocks for cracking are vacuum gas oils boiling at about 200-550 ° C or higher, depending on the Conradson carbon and metals. The feed may contain recycled materials, e.g. gasoline, light or heavy process oils, or sludge oil. The shorter catalyst lag time and lower amounts of catalyst compared to conventional regeneration methods of the process of the present invention allow more impure feeds to be charged to the reaction zone at a given air velocity (or carbon scavenging capacity) and a given catalyst addition rate.

In a typical known process, the catalyst coming from the regenerator comes into contact with the feed in the riser. As the mixture travels upward in the riser, the feed reacts to lighter products and to a carbon black deposited on the catalyst. The effluent from the riser is fed to a separation space where the reaction can continue. The entrained catalyst-containing hydrocarbon vapors then enter one or more cyclones to separate the spent catalyst from the hydrocarbon vapor. The hydrocarbon vapor is passed to a fractionator and separated into fractions such as light gases, gasoline, light process oil, heavy process oil and sludge oil. Various fractions can be recovered as products Bai recycled together with fresh feed to the ascending reactor. Light gases and gasoline are usually further processed in a gas concentrator. The separated spent catalyst flows to the bottom of the separation space and passes through a stripping zone where the stripping gas, usually steam, is contacted countercurrently with the spent catalyst to purify it of hydrocarbons. The catalyst leaves the stripping zone and enters the regenerator. Air is added to burn the carbon black and produce a regenerated catalyst with less carbon black and exhaust gas which is carbon monoxide, carbon dioxide, water, nitrogen and perhaps some oxygen. A typical spent catalyst contains 0.5-1.0% by weight of carbon black, with the regenerated catalyst containing about 0.2-0.4% by weight of carbon black, or in some prior art units as little as 0.01-0.05% by weight. carbon deposits. Exhaust gas 11,58265 is usually fed to a carbon monoxide boiler and combusted. The regenerated catalyst then comes into contact with the feed in the reaction zone.

Most of the catalytic cracking unit (FCC) catalyst volume is in the regenerator. The tendency is to have short contact time reactors, so an increasing amount of the total amount of catalyst is in the regenerator. The amount of catalyst in a standard regenerator is a function of the feed rate to the FCC unit or, in particular, the expected carbon black yield. The carbonaceous yield determines the need for fresh regeneration gas from the regenerator.

^ The maximum surface velocity of the steam is selected for a dense mattress, usually less than about 1 m / sec., In previously known units, in order to prevent excessive amounts of catalyst from entraining with the exhaust gas. When the gas flow and steam surface velocities are determined, the smallest possible cross-sectional area of the regenerator is also determined. The height of the dense mattress for a given cross-sectional area determines the catalyst delay time for a given catalyst flow rate, assuming that the density of the dense mattress is reasonably constant. The catalyst delay time shall be long enough for the specified regenerator geometry, temperature and oxygen concentration to ensure the removal of the desired amount of carbon black from the catalyst. For known units, the catalyst delay times are generally about 2-5 minutes.

Instead, the present invention is directed to a process in which a spent catalyst containing carbon black is regenerated in a regenerator having a first dense mattress, a dilute phase transport riser, and a second dense mattress. The spent catalyst and fresh regeneration gas enter the first dense mattress, where the carbon black is oxidized to produce a gas containing carbon monoxide. This gas and the entrained catalyst pass from the first dense mattress to the dilute phase transport riser, where further oxidation of the carbon scale takes place. The catalyst and regeneration gas leaving the riser are separated and the regenerated catalyst is passed to another dense bed. Depending on the operating conditions, the carbon monoxide can be oxidized in the first dense mattress or in the dilute phase riser, or both. In a preferred embodiment, the oxidation of the carbon scale takes place primarily in the first dense mattress and the oxidation of the carbon monoxide takes place primarily in the dilute phase conveyed snow tube.

When carbon monoxide oxidation occurs in the present invention! At 12,58265 this heat of combustion is transferred to the catalyst, which considerably raises its temperature. If higher catalyst temperatures are required, this can exceptionally be achieved in accordance with one aspect of the present invention by burning the combustible material in a dilute phase riser. Combustion in it results in a very efficient heat transfer to the catalyst in this zone. In the present invention, it is also an unusual possibility that carbon monoxide can be burned in a regenerator and at the same time the amount of carbon scum can be controlled by the regenerated catalyst. This can be accomplished by supplying stoichiometrically insufficient air to the first dense mattress so that substantial amounts of carbon black remain on the catalyst or by maintaining a low temperature in the first dense mattress to limit combustion of the carbon black. When this catalyst enters the dilute phase riser, additional air is preferably added, resulting in the combustion of carbon monoxide in the regeneration gas from the dense bed. Oxidation of gaseous carbon monoxide in the riser occurs very rapidly, so that although the gas delay time in the riser is short, almost all of the carbon monoxide present burns to carbon dioxide. A small combustion of the remaining carbon scale also occurs in the riser, but the catalyst lag time in this riser is so short that much of the residual karst in the catalyst entering the riser remains on the catalyst as it passes through the riser despite the high temperatures in the riser.

Some truffles need to be mentioned.

The combustion of carbon black is obviously never perfect, i.e. the catalyst will always contain some carbon black even after regeneration, although perhaps only 0.01 wt.% or even less. If carbon black and oxygen are in contact, oxidation occurs, very very slowly at low temperatures and faster at higher temperatures. Combustion of carbon monoxide also occurs whenever oxygen is present. Carbon black and carbon monoxide each react in the first dense mattress and in the dilute phase transport riser, each competing for oxygen. Relative reaction rates are affected by temperatures and yield of reactants. The phrases “burning of coal sludge” or “afterburning” should not be considered as mutually exclusive, but rather as simplistic descriptive phrases referring to reactions occurring at a substantial rate.

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Most refiners want a regenerated catalyst with as little carbon waste as possible, so that in the practice of the present invention, most refiners will place almost all of the regeneration gas in the first dense mattress. The dense catalyst mattress generally acts as a heat sink and generally keeps the temperatures in this mattress low enough that no significant afterburning of carbon monoxide to carbon dioxide occurs in this mattress. There is less catalyst in contact with the gas in the riser, so that afterburning of carbon monoxide takes place. If the catalyst is not hot enough from the afterburning of carbon monoxide, a combustible substance may be added to the dilute phase riser to cause additional combustion therein and to heat the catalyst. For most, the catalyst temperatures generated by the complete combustion of the carbonaceous carbon dioxide are sufficient without the need to add a combustible fluid to the riser.

Likewise, if a catalyst with a very low scaling content is not desired, some scaling can still be maintained with this catalyst while the heat of carbon monoxide combustion is recovered in the transport riser of the regenerator. This can be used to deactivate the catalyst, e.g. to change the production from the largest amount of Bentin to the largest amount of fuel oil.

Since the catalyst does not have to remain in the first dense bed, the surface velocity of the fresh regeneration gas is not limited to the low velocities of the previously known processes. Thus, about 0.9-3 m / sec. surface velocities are tolerable so that the catalyst can be carried from the first dense mattress to the dilute phase transport riser. The velocities in the dilute phase transport riser are about 3-7.5 m / sec.

By using higher speeds in the regenerator according to the invention, more turbulent flow, better mixing and more efficient regeneration are obtained. This improved gas-solid contact, higher oxygen partial pressures, and higher temperatures accelerate the burning rate of the carbon scale. Because the carbon scale is removed more quickly, the catalyst delay time can be shortened from the former 2-5 minutes to less than 2 minutes for the catalyst and from about 20 seconds to less than 10 seconds for gas compared to previously known solutions. The shorter exposure time of the catalyst to higher temperatures also prolongs the activity of the catalyst to reduce the addition of catalyst. The shorter catalyst delay time also reduces the total amount of catalyst.

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The amounts of catalyst used in the process of the invention are about 40-60% of current single or multi-stage regeneration processes. A reasonably sized FCC can contain about 140 metric tons of catalyst. By using the present invention, an initial cost of about 70 metric tons of catalyst can be saved. Catalyst addition rates also decrease as losses tend to be as a percentage of the amount of catalyst. In other words, heavier and more impure feeds can be used without the need to add catalyst at a rate that exceeds the rate currently approved for the FCC process using conventional regeneration techniques. Raw material inputs are no longer limited to relatively pure vacuum gas oils that contain limited amounts of Conradson carbon, metals, and nitrogen compounds. High molecular weight feeds containing more impurities can now be tolerated.

Due to the new flow of catalyst and regeneration gas according to the invention, stripping of the regenerated catalyst, in particular steam stripping, is now possible. Although steam deactivates the catalyst, steam is preferred because the steam is easily separated from the hydrocarbon products in subsequent process steps. Steam stripping of the deactivated catalyst is possible because the small amounts used and the short catalyst delay times as well as the low reactor temperatures minimize any deactivation. Likewise, steam stripping of the exhaust gas from the regenerated catalyst prior to the catalyst entering the reactor is desirable to prevent exhaust gas from entering the hydrocarbon product. Vapor stripping of the regenerated catalyst has generally not been used due to the longer lag time of the catalyst in the regenerator. Exposing this catalyst to steam for short periods of time lowers the activity of the catalyst. The present invention allows steam regeneration of the regenerated catalyst by minimizing the catalyst lag time in the second dense bed of the regenerator. In addition, the vapors from the steam stripping do not come into contact with the catalyst in the first sealed mattress, nor in the dilute phase transport riser, so that vapor decatitation in these zones is eliminated.

Steam stripping of the regenerated catalyst is desirable because the regenerated catalyst contains about 1-3 parts by weight of exhaust gas components per 1000 parts by weight of the catalyst. In a reasonably sized FCC unit, about 1,350,000 kg of catalyst is recycled per hour, which is accompanied by about 2,000 kg of exhaust gas to the identification reactor. The reactor effluent thus contains about 1600 m 2 of exhaust gas components per hour at normal temperature and pressure. The effluent from the reaction zone is optionally separated into gas and unstabilized gasoline by distillation. To recover the light hydrocarbons and separate them from the gasoline, these substances are sent to a gas concentration unit equipped with a compressor, an abstraction device and fractionation columns. A typical gas analysis of the last absorber is as follows:

Table No. 1

Absorption device exhaust gas Component Mole%

Carbon dioxide 3.8

Oxygen + argon 0.3

Nitrogen 22.8

Carbon monoxide 4.5

Hydrogen 8.9

Methane 23.6

Ethylene 11.8

Ethane 12.5

Propylene 4.8

Propane 1.4

Isobutylene + 1-butene 0.7

Sis-2-butene 0.4

Trans-2-butene 0.5

Isobutane 1.7 ^ Normal butane 0.5

Isopentane 0.7

Normal pentane 0.2 _ Total C8 and C4 olefins 0.9 100.0

The entrained gas N2, CO and CO2 make up 31.1 mol% of this product stream. Steam stripping of the regenerated catalyst can remove most of the psart from this material in the regenerator. Removal of the exhaust gas from the reactor exhaust stream results in significant savings, i. smaller compressors and absorbers can be used and the absorber exhaust gas has a higher heat content.

In the process of the present invention, the oxidation of the carbon board may occur in the first dense mattress or in the dilute phase riser, or both. CO oxidation can also occur either in the first sealed mattress or in the transport riser 58265, or both. The carbon black is preferably oxidized for the most part in the first dense mattress and the main carbon monoxide oxidation takes place in the transport riser. This minimizes the time the catalyst is exposed to very high temperatures.

The temperatures associated with CO oxidation are higher than those required for simple oxidation of carbon black. Therefore, it is preferred that the high temperatures due to CO oxidation occur in a transport riser with a very short catalyst lag time. To minimize the oxidation of carbon monoxide in a dense mattress, the temperature should be about 620-675 ° C. At temperatures of about 675 ~ 695 ° C, some post-combustion of carbon monoxide occurs in the presence of oxygen, but for complete post-combustion, temperatures of about 695 ~ 760 ° C are preferred.

Almost complete oxidation of carbon monoxide in the regenerator avoids the air pollution problem of the CO boiler. The process of the present invention further makes it possible to transfer the heat of combustion of carbon monoxide to the catalyst in the transport riser to provide a hotter regenerated catalyst.

This reduces the need to preheat the feed.

The regenerator pressures used in the invention may be about 4.5 ik, preferably 2-3.5 ik, of atmospheric pressure. Thanks to better gas-solids contact, higher temperatures, and higher oxygen concentrations, lower pressures can be used without sacrificing carbon-scale combustion capacity. Cheaper containers and compressors can now be used.

"Spent catalyst" means the catalyst removed from the reaction vessels due to the lower activity provided by the carbon scaffolds. The spent catalyst entering the first sealed mattress may contain from a few tenths to about 5% by weight of carbon black, but will usually contain about 0.5 to 1.5% by weight of carbon black. A regenerated catalyst is a catalyst from which no carbon scale is removed. The regenerated catalyst usually contains less than about 0.5% by weight of carbon stocks and possibly less than 0.05% by weight of carbon stocks, depending on the operating conditions in the regenerator and the conversion required by the reactor. A partially regenerated catalyst is one from which part of the carbon scale to be removed has been removed.

Regeneration gas means any gas intended to contact the catalyst in the regenerator, such as air or oxygen-enriched or oxygen-poor air. Fresh 17,58265 regeneration gas enters the regenerator's first sealed mattress from the catalyst used to burn the coal scale. The partially used regeneration gas is a gas that has been in contact with the catalyst in the first dense bed and contains less free oxygen. The partially used regeneration gas usually contains water, nitrogen, oxygen, carbon monoxide and carbon dioxide. The regeneration gas used is a gas which contains practically no carbon monoxide, which contains from a few tenths to 15 moles of oxygen, as well as carbon dioxide, nitrogen and water.

Gas-solid separation devices can be used to separate the regeneration gas from the accompanying regenerated catalyst. Preferred separation devices are well known cyclone separation devices. One or more cyclones may be used in parallel or in series.

The example below compares the method of the present invention with a known method. The commercial molecular sieve catalyst was regenerated with air after contact with the vacuum gas oil in the reactor and after steam stripping. The catalyst used contained about 0.9% by weight of carbon black and the carbon black contained 10.1% by weight of hydrogen. A conventional regenerator had a single dense mattress with a large dilute phase separation space above the dense mattress.

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Table 2

Regeneration process comparison

At issue

Prior art invention

Temperatures, ° C

Tight mattress 6 * 13 677

Dilute phase 6 * 41

Transport riser - 7 * 41

Exhaust gas 67 * 4 738

Another dense mattress - 727

Paine, ik. 2.67 2.36

Dry air entering the regenerator, net kg / hour 105,600 105,100

Dry air / carbon black, kg / kg 11.3 1 * 4.51

Carbon black yield, weight # from fresh feed (75% reaction zone conversion) 6.6l 5.05

Carbon black with regenerated catalyst, weight # 0.2 0.02

Container size, diameter, m. 7.5 * 1.8

Catalyst delay time, min. 3 0.9

Gas delay time, sec. 15.5 5.5

Surface speed, m / sec.

Tight mattress 0.72 1.5

Dilute phase 0.72 6.0

Exhaust gas analysis, molar # C0? 9.2 1 * 1.9

Argon 1.1 1.0 N? 79.2 82.3 CO 10.2 (270 ppm vol.) O 2 0.2 1.8 CH 2 O 0 0

Stripping of regenerated catalyst no

Feed preheating, to ° C. 211 136

Total amount of catalyst, metric tons 5 * 1 32

Air is the regeneration gas in both processes, however, in the process of the present invention a higher oxygen concentration is maintained in the regenerator as in the higher exhaust lightness, 1.8 moles of O2 is obtained when comparing the previously known solution to 0.2 moles of Op. The regenerated catalyst of the present invention is hotter, which allows for a lower catalyst cycle and thus a lower carbon black yield from 6.61 wt.% To 5.05 wt.% To carbon black. This also increases the yield. The new process used less air at lower pressure, but gave a regenerated catalyst with less i9,58265 carbon black and gave an exhaust gas with virtually no carbon monoxide. Combustion of carbon monoxide in the regenerator thus eliminates the air pollution problem and reduced the required feed preheating by about 75 ° C. The total amount of catalyst is about 40% smaller than in the conventional process, so the size of the regenerator is smaller. Although not shown, it has been found that a lower total amount of catalyst and a shorter delay time result in lower catalyst addition rates. The regenerated catalyst according to the invention is stripped, which reduces the size of the equipment required in the gas concentration auxiliaries.

The present invention also makes it possible to control the temperature of the regenerated catalyst. The importance of the recovery temperature of the regenerated catalyst as a reactor variable in fluid catalytic cracking is generally not understood. Concerns about regenerator temperatures have been primarily focused on regenerator metallurgy or maintaining a satisfactory coal burning rate. In short contact time systems, where thermal equilibrium between the catalyst and hydrocarbon vapors may not be achieved, the high temperature and activity of the catalyst promotes rapid and efficient cracking of the feedstock. The cracked products return after separation from the hot catalyst to a colder oil vapor environment where secondary cracking is greatly reduced. Thus, the primary cracking can be controlled by the catalyst delivery temperature and the secondary cracking by the carbon-hydrogen delay time. From the point of view of better yield distribution and product quality, it is therefore advantageous to control the thermal state of the regenerated catalyst.

The effect of catalyst feed temperature at constant reactor outlet temperature on product yields is shown in Table 3 · 20 58265 below.

Table 3 Application Prior Art_ Invention

Reactor outlet temperature, ° C 536 536

Catalyst feed temperature, ° C 677 732

Preheating the feed to 364,316 ° C

Gasoline yield, liquid volume # (C5 distills 90 # at 193 ° C) 67.1 67.0

Alkylation feed precipitate, (O 2 -C 2) liquid volume-; <25.1 27.1

Total circulating oil yield, ~ liquid volume- # 21.3 23.5

Carbon black yield, weight # 5.3 3.8

Conversion, liquid volume- # 78.7 76.5

Gasoline octane number (research + 0 cc TEL) 93.0 93.3

The example shows that the higher the catalyst feed temperature, the lower the conversion, but the higher the product value. The hotter catalyst has roughly the same gasoline yield, but a higher octane number. The decisive advantage is a higher yield of 2.0% by volume of the alkylation feed and a 2.3% by volume higher yield of total circulating oil with the hotter catalyst.

This higher alkylation feed yield represents a latent high octane alkylate. Process oils are not as valuable as alkylation feed or gasoline, but are more valuable than coal tar. The required preheating of the feed is reduced by the hotter catalyst. -

The present invention also makes it possible to control the amount of residual carbon scum on the catalyst. When the catalyst and reactor temperatures are constant, the increase in carbon black with the regenerated catalyst reduces conversion and gasoline yield and increases the yield of process oil (fuel oil). The reduction in residual carbon increases the conversion at the expense of fuel oil yield.

If there is very little residual carbon black in the regenerated catalyst, it is possible to increase the gas yield (LPG) at the expense of gasoline yield.

Table 4 shows an example of these possibilities with a constant catalyst feed temperature.

21 58265

Table "Residual Coal Scale Impact Combustion LPG FCC Operating Type LPG Gasoline Oil for Conditions

Reactor temperature, ° C 521 521 521 521

Feed preheating temperature, ° C 191 316 316 191

Regenerated catalyst feed temperature, ° C 732 732 732 732 Residual carbon black with regenerated catalyst, weight <<0.02 0.11 0.62 0.62

Yield distribution from liquid-volume- # fresh feed

Conversion 85.7 75.0 64.4 77.0

C 1 -C 6 (LPG) 38.2 26.3 20.4 31.4

Gasoline (90 # distilled at 193 ° C) 52.0 62.3 48.3 58.3

Light process oil 11.4 20.0 30.6 18.0

Clarified sludge oil 5.0 5.0 5.0 5.0

Carbon black, weight # 6.8 3.8 5.3 6.8

The highest possible LPG yield is produced under these operating conditions using a regenerated catalyst with very little residual carbon black by weight. A catalyst with 0.02 wt.% Carbon black gives a higher conversion and crackes even gasoline to produce LPG. A catalyst with 0.11 wt.% Carbon black is less active, so conversion and LPG yield are reduced, but gasoline yield is increased. As the amount of residual carbon black continues to increase, as shown in LCO operation to about 0.6 wt% carbon black, the catalyst becomes less active, so the conversion and yields of both LPG and gasoline decrease, but the yield of light process oil (fuel oil) increases. The effect of residual carbon scar on product yields is best seen by comparing the first and last columns of Table 4. The operating conditions are the same, except for the amount of carbon black. The conversion and LPG yield are lower for a catalyst with 0.62 wt.% Carbon black because the catalyst is less active at a higher residual rate.

The process of the present invention allows direct and convenient control and optimization of the yields 22,58265 and grades by adjusting the catalyst feed temperature or by adjusting the amount of residual carbon scale or both. Thus, fuel oil production can be maximized or gasoline yield or LPG production can be maximized.

Claims (5)

23 58265 A process for regenerating a spent coke-contaminated hydrocarbon cracking catalyst removed from the reaction zone, comprising the steps of: and to form a partially used regeneration gas containing CO; the regenerated catalyst and the partially used regeneration gas from step a) are passed upwards through a dilute phase transport riser connected to the first stage and located above it, the conversion conditions in the riser are adjusted to further oxidize the coke and convert CO to CO 2 to form the regenerated catalyst and spent regeneration gas before being separated in step b). A method according to claim 1, characterized in that the total residence time of the regeneration gas in the first dense mattress and in the dilute phase transport riser is less than 10 seconds. Method according to Claim 1 or 2, characterized in that the temperature in the dilute phase transport riser is 650 to 800 ° C and the surface velocity of the gas is 3> 0 to 7.5 m / sec. 1. A regenerative method for regenerating coke batches and reactants obtained from the reaction process, comprising the following alternatives to the regenerative process, which comprises the above-mentioned regenerative process Having regard to this Regulation, the oxide mixture may be mixed with a batch regeneration catalyst and a batch regeneration catalyst, CO