JP2000319667A - Improved residual oil fluid catalytic cracking process for increasing catalytic metal tolerance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved fluid catalytic cracking(FCC) process for treating residual oil. SOLUTION: An improved residual oil fluid catalytic cracking process which reduces the inactivation of a catalyst to be caused by vanadium and/or sodium in the treatment of a residual oil feed comprises contacting the used catalyst 14 with an oxygen-containing regenerating gas 7 in regenerators 6 and 8 under catalyst regenerating conditions which are effective for removing most of the carbonaceous deposits from the used catalyst by burning and also comprise such a combination of the oxygen level of the regenerating gas and the regenerating temperature as not to completely oxidize most of the vanadium or the sodium on this catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improved fluid catalytic cracking (FCC) process for treating residual oil. Here, the FCC unit (FCCU) design and operating conditions allow for operation at an increased level of metal on the equilibrium catalyst more than in the prior art.

[0002]

BACKGROUND OF THE INVENTION The primary objective of crude oil refining is to always produce the highest value-added products in a maximum quantity and minimize the production of low value-added products. That is. Except for special products with limited markets, the highest value added petroleum refining products with the largest markets are mobile fuels, such as gasoline, jet fuel and diesel fuel, the second is domestic Heating oil. Historically, relatively low value-added products have been associated with resids, which are defined as a portion of crude oil boiling above about 1000 ° F or 538 ° C. Historically, the petroleum refining industry has sought an economically more efficient method of converting crude oil resid to relatively high value-added products, including the viscosty breaking process, coking ( (Delays and fluids), and solvent-free processes such as solvent elimination.

[0003] A major obstacle to the resid treatment in catalytic processes such as FCC or hydrogenation type processes is the concentration of catalyst poisons such as metals, nitrogen, sulfur and asphaltenes (precursors of coke) on the catalyst. Was. These catalyst poisons are present in all resids at different levels depending on the crude oil being treated. These "catalyst poisons" promote catalyst deactivation, reduce catalyst selectivity, and increase the cost of the catalyst and other operations. Thus, in most cases, by limiting the proportion of resid in the feed to other feed components that are relatively free of catalyst poisons,
Ensure that these residua treatment methods are still economical.

Most of the world's petroleum refineries use the known fluid catalytic cracking (FCC) process as the primary process for reforming heavy gas oils into transportation fuels, thus treating relatively heavy resids. It should be understood that the FCC process should be used in However, the catalyst exchange rate required to control the metal levels in the circulating equilibrium catalyst (ECAT) to acceptable levels,
And the environmental considerations which require the introduction of SO _x (sulfur oxides) control of the FCC regenerator flue gas, the process of residual oil in the FCCU is slower. Increased cost of capital without the economic benefits required to process FCC regenerator flue gas and ECA when processing increased amounts of resid
For increased operating costs associated with the replacement rate of relatively large fresh catalyst required to control the metal level T, then the SO _x controlling method of many refineries preferably flue gases, the feed Choose to introduce hydrotreating. Hydrotreating an FCC gas oil feed beneficially increases yield. Therefore, it is economically advantageous to use this approach. However, the introduction of resid to the hydrotreater feed also increases the cost of the hydrotreating catalyst and is typically not economical, so hydrotreating FCC feeds limits the feed to gas oil. Was. Another reason that hindered the introduction of resid into the FCC feed was that many FCCUs were "aged." Due to the increased capital costs required to retrofit the FCCU, users of these units reluctantly treat the resid in the FCCU. Ironically, new environmental regulations on fuel and regenerator flue gas emissions require that all FCCUs process flue gas to remove particles and sulfur.
It appears that it is necessary to remove O _x and treat the FCC transfer fuel product to reduce sulfur and improve the distilled cetane index. This flue gas treating process, requiring for example the introduction of wet scrubbers for control of particulate and SO _x, and the introduction of hydrotreating and aromatics genus saturation process for treating a FCCU mobile fuel products.

[0005] As the FCC process and catalysts have improved over the past 50 years, the limits on the amount of "catalyst poisons" have also improved. Feeds with up to about 7-8 wt% lance bottom carbon are being processed. Also, economy (catalyst cost) limits metals in FCC feeds to about 30 ppm. This means that the rate at which fresh catalyst is added to the feed is about 1 # / bbl. (0.45 kg / 0.16 m ³ ), and the equilibrium catalyst (ECA)
This is equivalent to maintaining the metal (Ni + V) on T) to about 11,000 ppm. This level of Ni + V is believed to be achieved in the prior art. Recent commercial improvements in FCC processes are described, for example, in U.S. Pat. No. 4,985,136 to the assignee of the present invention, "Ultra-Short Contact Time F.
The luidized Catalytic Cracking Process (commercially referred to as the Millisecond Catalytic Cracking (MSCC) process) has been developed. This process can treat resids with little restrictions on lance bottom carbon, nitrogen, and nickel levels.
The only limitations on the sulfur content of the FCC feed are the costs associated with producing an acceptable product and treating the FCC regenerator flue gas. Current fuel standards and environmental regulations eventually require the introduction of regenerator flue gas scrubbing for particulate and SO _x control in any FCC type device. These units also require that the majority of the FCC product be treated for sulfur, and that aromatics saturation equipment (cetane number improvement) and desulfurization equipment be introduced into the FCC distillation product section. In effect, regulations eliminate all restrictions on FCC feed sulfur content. It should also be noted that FCCU is a very cost effective sulfur removal process, converting about 50% of the supplied sulfur to H ₂ S without adding hydrogen.

[0006] However, despite these improvements in the FCC process, the amount of resid that a refiner can economically convert in the FCC process depends on the catalyst exchange rate required for catalyst deactivation. Limited. This catalyst deactivation is due to metals in the resid feed, especially vanadium and sodium.
Other catalyst poisons to the catalyst, such as coke precursors, nitrogen,
And accumulation of sulfur eliminates the effects of coke formation from alfalten compounds using a catalyst cooler, MS
Overcoming the problems associated with vaporization and riser coke formation in riser-type FCCs using the CC process, reducing the environmental impact of feed sulfur using regenerator flue gas and product treatment Efficient control can be achieved by eliminating and eliminating the effects of feed nitrogen and nickel using the MSCC process.

In FCCU operation, the economics of the process is due to the new catalysts containing additives, such as ZSM-5 and F
Other zeolitic materials used for specific purposes in the CCU are highly dependent on the rate at which the circulating catalyst (equilibrium catalyst) is exchanged. Equilibrium catalyst (ECAT) is FCCU
Is an FCC catalyst circulating between the reactor and the regenerator for many cycles. The amount of catalyst that needs to be added or the rate of catalyst exchange depends on the rate of catalyst exchange and catalyst loss required to maintain the desired equilibrium catalytic activity and selectivity that results in an optimal production structure. In operation with feeds containing resid, it is also necessary to add sufficient exchange catalyst to keep the metal levels in the circulating catalyst below levels where the production structure is still economically valuable. is there. In many cases, a well-active, low metal level equilibrium catalyst is added to the new catalyst to maintain a suitable level of catalytic activity at the lowest cost. At current feed and product prices, most producers are
Feed 1 processing contact operation cost in FCCU
Restricted to less than $ 1.00 per barrel (0.16m ³ ). At the average new catalyst price, the cost, including the cost of transporting and disposing of the equilibrium catalyst, is 2000.0 per ton (907 kg).
$ 0, which is about 1 # / bbl. (0.45kg / 0.16m ³ )
Is equivalent to As noted above, this rate of addition is equivalent to about 11,000 ppm of metal on the equilibrium catalyst for 30 ppm Ni + V in the feed. In the prior art, it is generally accepted that Ni + V on the equilibrium catalyst is up to 11,000 ppm to maintain the desired catalyst activity and selectivity.

[0008] The manner of FCC catalyst deactivation by vanadium is not completely understood. However, if the steam is V ₂
It is believed that it reacts with O ₅ to form volatile VO (OH) ₃ vanadate. The steam here is the steam produced by the combustion of hydrogen in the coke, the entrained stripping steam and the steam in the combustion air. This is the main mechanism of the transfer of vanadium species from particle to particle. In the form of pentoxide or vanadic acid, vanadium has an affinity for zeolite crystals. Although the exact mechanism of zeolite crystal destruction is controversial, vanadium clearly results in an irreversible loss of zeolite crystallinity and surface area. The activity of the catalyst is reduced and the selectivity for gasoline and light olefins is reduced. This catalyst deactivation mechanism requires that vanadium be completely oxidized, ie, become pentoxide (not dioxide, trioxide or tetroxide). Thus, some oxidation of vanadium can occur without effecting such catalyst deactivation. The mechanism of catalyst deactivation by sodium is thought to be similar to that by vanadium.

The method of the present invention is contrary to the idea of many users of FCC technology. That is, the conventional FCC design concept used in a plurality of FCC processes is as follows:
It is a so-called two-stage regenerator. This two-stage regenerator regenerates the catalyst in two stages, the second stage of which is typically 1300 °
High temperature oxidizing atmosphere exceeding F (704 ° C). Another one
In one process, spent catalyst is distributed at the top of the regenerator bed such that the lower portion of the fluidized bed where the combustion air is introduced contacts the highest oxygen concentration and the hottest catalyst.
All of these above have the opposite of the principles of the present invention and do not allow satisfactory operation of the FCCU with a resid feed.

A first object of the present invention is an FCC process which allows for the economical treatment of resid feeds with more than 30 ppm of metal (Ni + V) in the feed. Another object is to reduce the fatal effect of vanadium on catalytic activity. Yet another object is to reduce the lethal effect of sodium on catalytic activity. Yet another object of the present invention is to reduce the exchange rate of new FCC catalysts required to compensate for the effects of catalyst deactivation caused by vanadium and sodium, thereby reducing the cost of new catalysts, transportation costs, The goal is to reduce equilibrium catalyst disposal costs and equipment catalyst losses. Other objects of the present invention will become apparent from the following description and / or practice of the present invention.

[0011]

SUMMARY OF THE INVENTION The above and other objects and advantages of the present invention are for vanadium and / or sodium deposited on the circulating catalyst used in the process, the vanadium and / or sodium resulting from the resid feed. Alternatively, it can be achieved by an improved resid fluid catalytic cracking process that reduces catalyst deactivation caused by sodium. The method comprises contacting a resid-containing feed with a hot regenerated cracking catalyst under hydrocarbon cracking conditions in a fluid catalytic cracking reactor to convert the resid-containing feed to a relatively low molecular weight hydrocarbon product vapor. Converting and obtaining a spent catalyst having a carbonaceous deposit comprising vanadium and / or sodium; separating and separating a majority of the relatively low molecular weight hydrocarbon product vapor from the spent cracking catalyst Providing a separated product vapor and a separated spent catalyst containing entrained hydrocarbon vapors; processing the separated product vapor to a desired product fraction; Stripping the catalyst to remove most of the entrained hydrocarbon vapors; removing the resulting stripped spent catalyst in a regenerator under catalyst regeneration conditions under oxygen-containing conditions. Contacting with a gas, wherein the catalyst regeneration conditions are effective for burning and removing most of the carbonaceous deposits from the spent catalyst while removing vanadium and / or sodium on the catalyst. Vanadium and / or sodium containing a combination of regeneration gas oxygen level and regeneration temperature that renders most of the catalyst completely unoxidized so that the carbon level is lower than the spent catalyst and most are not fully oxidized Providing a regenerated catalyst having; and returning the regenerated catalyst to the reactor.

[0012] In one embodiment, the present invention provides a 1300 ° F.
(704 ° C) and / or a less than complete oxidation atmos
Use an FCC process design that combines regenerator design and operating methods that maintain a phere) and / or reducing atmosphere. Incomplete oxidizing atmosphere requires at least 0.08 wt% of regenerated catalyst
Defined as regenerator process conditions that yield% carbon. That is, when treating a treated resid feed containing vanadium and / or sodium, maintaining an incompletely oxidizing and / or reducing atmosphere in the regenerator substantially reduces catalyst deactivation by vanadium and sodium. It was measured that it could be prevented. This slows down the formation of vanadic acid and vanadium pentoxide, and low melting point sodium compounds, thereby reducing the undesired effects of vanadium and sodium on catalytic activity, as described above.

By maintaining the regenerator temperature below 1300 ° F. (704 ° C.), and preferably below 1250 ° F. (677 ° C.), the catalytic activity is maintained even when excess oxygen is utilized for regeneration. It has also been found that the effects of vanadium and sodium on water can also be reduced. FCCUs can be designed to operate regenerators in reducing atmospheres and / or temperatures below 1300 ° F. (704 ° C.) to minimize catalyst deactivation by vanadium and sodium, The combination results in minimal catalyst deactivation.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood by reference to the following description, taken in conjunction with the accompanying FIG. 1, which is a schematic of a preferred embodiment of the invention.

The feedstock used in the process of the present invention comprises a resid, which may be a mixture with other relatively low boiling hydrocarbons such as one or more gas oils. . The proportion of resid in the feed may vary, depending on the nature of the feed components. Typically, the resid feed contains about 5-90 vol% resid, with the balance being one or more gas oils, such as vacuum gas oil, atmospheric gas oil, or recycles, etc. .

As used herein, residual oil is about 1000 ° F.
Reference is made to a crude oil fraction boiling above (538 ° C.). As a catalyst poison as described above, the resid contains vanadium, sodium, or both.

It will be appreciated that "resid" can contain sodium and vanadium in the form of metals and / or any inorganic or organic compound. The sodium and vanadium, when deposited on the circulating catalyst, may be in the form of a metal and / or one or more compounds such as sulfur compounds or organometallic compounds. Thus, as used herein, "vanadium and sodium deposits" refers to any of the various types of vanadium and sodium containing deposits formed on the catalyst as metals or compounds.

In a preferred method of practicing the present invention, FC
In the reactor 4 of the C-type reactor, the resid feed supplied via line 1 is mixed with the regenerated catalyst supplied via line 2. The design and operation of FCC reactors are known and need not be described in detail here. Any type of FCC reactor can be used,
The MSCC facilities listed above are preferred for the above reasons.
The flow of the regenerated catalyst in the pipe 2 from the regenerator vessel 8 is
Controlled by the regenerative catalyst slide valve 3, the outlet temperature of the product vapor exiting the reactor 4 via line 10 is regulated. The resid feed is mixed with the hot regenerated catalyst to evaporate the feed and convert it to a hydrocarbon product having a lower molecular weight than the feed, and the resulting reactor vapor flowing through line 10, where Separated from spent catalyst used. Reactor vapor, essentially free of catalyst, leaves reactor 4 via line 10 and is further processed in downstream equipment by known means to the desired product fraction. The separated spent catalyst and entrained hydrocarbon vapors flow down reactor 4 into stripper section 15. In a preferred embodiment, the stripper section 15 mixes with the hot regenerated catalyst controlled by a slide valve 16 to control the stripper temperature above the reactor vapor temperature in line 10. Here, the mixture of the spent catalyst and the regenerated catalyst whose temperature has been increased is subjected to steam stripping by a stripper 15 to remove as much hydrocarbon as possible before leaving the reactor 4 through the spent catalyst slide valve 5. Remove. This used catalyst slide valve 5 controls the catalyst level of the reactor stripper 15.

In the reactor 4, the resid feed vapor is brought into intimate contact with the catalyst in the reactor 4 in cracking conditions to produce a relatively low molecular weight hydrocarbon product vapor, while at the same time A spent catalyst having a carbonaceous deposit and a metal deposit is provided. These deposits include vanadium and sodium deposits and are typically in the form of sulfides or other metal-containing compounds.

Downstream of the spent catalyst slide valve 5, the spent catalyst 14 is mixed with an oxygen-containing combustion gas, for example air, supplied via a line 7 of a combustion riser 6. In the riser 6, the mixture flows upward and is put into the regenerator vessel 8. The flow rate of the combustion air used to burn the carbon of the spent catalyst is controlled to reduce the oxygen in the regenerator flue gas exiting the regenerator via line 9 to less than 1 mol%, more preferably 0.5 mol%. It is adjusted to less than 0.1 mol%, even more preferably less than 0.1 mol%. By lowering the temperature of the regenerated catalyst, it is possible to operate the flue gas leaving the regenerator 8 via line 9 with a higher oxygen content. As the exit temperature of the combustion riser 6 decreases, the rate of carbon combustion decreases, even with oxygen coming out of the combustion riser 6, thereby maintaining the carbon level on the regenerated catalyst using an incompletely oxidizing or reducing atmosphere. It becomes possible to do.

This regeneration method using a combustion riser
Compared to a conventional fluidized bed regenerator or a fast fluidized regenerator, it minimizes the partial pressure of oxygen and minimizes backmixing that can reduce the carbon on the regenerated catalyst and oxidize metals on the catalyst surface. preferable. In combustion risers, high speeds, preferably 10 ft / sec (3.048 m / sec), and short residence times, preferably less than 20 seconds, more preferably less than 15 seconds, are used. The use of the high speed short riser regenerator 6 allows operation at relatively high regenerated catalyst temperatures without complete regeneration or complete combustion of carbon from the catalyst surface, as compared to other regeneration methods. In addition, this does not completely oxidize most metals. This results in less coke and increased product yield. When using more common fluidized bed regenerators or high speed fluidized bed regenerators, the regenerator temperature must be reduced to reduce the degree of oxidation of vanadium and sodium. After mixing the air and the spent catalyst, the combustion of carbonaceous deposits on the spent catalyst begins. As the fluidized mixture flows upward through the combustion riser 6, oxygen is consumed by burning the surface carbon. This reduces the partial pressure of oxygen,
This has the effect of limiting the oxidation driving force of carbon combustion or metal oxidation. Since the metals are mainly present on the surface of the catalyst and the carbon deposited in the reactor 4 covers these metals, the metal is exposed and oxidized only when the carbon is uncovered at high temperatures. There is. The use of a cocurrent regeneration facility as described above minimizes or substantially prevents oxidation of the metal. However, operating in accordance with these techniques, any type of regenerator can be used to reduce the catalytic deactivation effect of sodium and vanadium.

The exit temperature of the combustion riser is 1300 ° F. (70
4 ° C.), more preferably less than 1250 ° F. (667 ° C.) to reduce the carbon level on the regenerated catalyst
less than 0.3 wt%, more preferably less than 0.3 wt%
Keep above t%. This is achieved by the catalyst cooler 11 mixing the cooled regenerated catalyst with the upwardly flowing spent catalyst and combustion air at predetermined locations in the combustion riser 6. Here, the temperature of the resulting mixture is
Less than 1250 ° F (677 ° C), preferably 1200 ° F (649 ° C)
° C) to minimize carbon combustion and metal oxidation due to the surface of the cooled regenerated catalyst flowing through line 13. The proportion of the cooled regenerated catalyst is controlled by a slide valve 12 to reduce the regenerated catalyst temperature to less than 1300 ° F (704 ° C), more preferably
Adjust to less than ° F (677 ° C). In the regenerator vessel 8, the combustion products (flue gas in the pipe 9) are separated from the regenerated catalyst and the cooled regenerated catalyst. Regenerator flue gas further performs heat recovery process, also released to the atmosphere after performing control processing of the particles and SO _x. The regenerated catalyst is returned to the reactor 4 and
The regenerated catalyst temperature is controlled by contacting and evaporating the resid feed of the reactor 4 and recirculating it to the combustion riser 6 through the catalyst cooler 11 and the slide valve 5.

Thus, in accordance with the present invention, the conditions for regenerating the spent catalyst in the regenerator, ie, the combustion riser 6 and the regenerator vessel 8, are maintained so that most of the vanadium and sodium deposits are not oxidized or low It effectively burns most of the carbonaceous deposits from spent catalyst while oxidizing. Preferably, the carbon level of the regenerated catalyst is about 0.4 wt%
Less than about 0.08 wt% or more substantially prevents oxidation of vanadium and sodium deposits. This can be achieved by controlling the regenerator temperature and atmosphere as described above.

Although the preferred embodiment of the present invention has been described above, it is apparent from the description and the implementation of the present invention that various modifications are included in the essence of the present invention. It is to be understood that the scope of the invention is to be determined by the appended claims and equivalents thereof.

[Brief description of the drawings]

FIG. 1 is a schematic flow chart of a preferred method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Residual oil feed stream 3, 5, 12, 16 ... Sliding valve 4 ... Reactor 6 ... Combustion riser 7 ... Oxygen-containing gas stream 8 ... Regenerator vessel 9 ... Regenerator flue gas stream 10 ... Product vapor 11 ... Catalyst cooler 14 ... Spent catalyst flow 15 ... Stripper compartment

Claims (12)

[Claims] 1. Vanadium and / or deposited on a circulating catalyst used in the treatment of a resid feed due to the resid feed.
Or an improved resid fluid catalytic cracking process to reduce catalyst deactivation caused by sodium, comprising: (a) regenerating a resid-containing feed at elevated temperature in hydrocarbon cracking conditions in a fluid catalytic cracking reactor. Contacting with a cracking catalyst converts the feed to a hydrocarbon product vapor having a lower molecular weight than the feed and provides a spent catalyst that retains vanadium and / or sodium deposits and carbonaceous deposits. (B) separating a majority of the relatively low molecular weight hydrocarbon product vapor from the spent cracking catalyst to provide a separated spent catalyst comprising the separated product vapor and entrained hydrocarbon vapor (C) treating the separated product vapor to a desired product fraction; and (d) subjecting the separated spent catalyst to a stripping treatment. Removing the majority of the entrained hydrocarbon vapors; (e) contacting the stripped spent catalyst obtained with an oxygen-containing regeneration gas in a regenerator under catalyst regeneration conditions; While regeneration conditions are effective to burn most of the carbonaceous deposits away from the spent catalyst, regeneration that does not completely oxidize most of the vanadium and / or sodium on the catalyst. Including a combination of a gas oxygen level and a regeneration temperature, resulting in a regenerated catalyst having vanadium and / or sodium that has a lower carbon level than the spent catalyst and is largely not fully oxidized; and (f) And b) returning the regenerated catalyst to the reactor. 2. The method of claim 1, wherein said stripping is performed at a temperature higher than the temperature of the product vapor exiting said reactor.
An improved resid fluid catalytic cracking process for reducing catalyst deactivation according to claim 1. 3. The improved fluid catalytic cracking process of claim 1 wherein said regeneration temperature is less than 1300 ° F. (704 ° C.). 4. The improved fluid catalytic cracking process of claim 1 wherein said regeneration temperature is less than 1250 ° F. (677 ° C.). 5. The improved resid fluid catalytic cracking process of claim 1 wherein said regeneration results in a flue gas having an oxygen content of less than 1.0 mol%. 6. The improved resid fluid catalytic cracking process of claim 1 wherein said regeneration results in a flue gas having an oxygen content of less than 0.5 mol%. 7. The improved resid fluid catalytic cracking process of claim 1 wherein said regeneration results in a flue gas having an oxygen content of less than 0.1 mol%. 8. The improved resid fluid catalytic cracking process of claim 1, wherein the carbon level on the regenerated catalyst is 0.4 wt% or less. 9. The carbon level on the regenerated catalyst is 0.08 wt%.
2. The improved resid fluid catalytic cracking method of claim 1 which reduces catalyst deactivation. 10. The improved fluid catalytic cracking of claim 1 wherein the regeneration temperature is less than 1300 ° F. (704 ° C.) and the regeneration is performed in a reducing atmosphere. Method. 11. The method of claim 1, wherein the regeneration conditions are effective to substantially prevent complete oxidation of vanadium and / or sodium on the catalyst during regeneration. Improved resid fluid catalytic cracking process to reduce. 12. The reduced catalyst deactivation of claim 1, wherein the stripped spent catalyst is mixed with an oxygen-containing combustion gas in a combustion riser and the riser is moved upward to a regenerator. An improved resid fluid catalytic cracking process.