Systems and processes for temperature control in fluid catalytic cracking

Abstract

A process for controlling catalyst temperature in a fluid catalytic cracking ("FCC") system includes regenerating a spent catalyst feed at a first temperature in a regenerator to produce a regenerated catalyst feed, recovering at least a portion of the regenerated catalyst feed to a reactor, and cooling the portion of the regenerated catalyst between an outlet of the regenerator and an inlet of the reactor. The fluid catalytic cracking ("FCC") system includes a catalyst regenerator configured and adapted to regenerate the spent catalyst feed at a first temperature to produce a regenerated catalyst, a reactor downstream from the outlet of the catalyst regenerator, and a catalyst cooler between the outlet of the catalyst regenerator and the inlet of the reactor. The catalyst cooler is configured and adapted to cool at least a portion of the regenerated catalyst from the catalyst regenerator. In an embodiment, the FCC system is a downer FCC system including at least one downer reactor and a spent catalyst riser regenerator.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 374,240, filed August 31, 2022, the entire disclosure of which is incorporated herein by reference. [Background technology]

[0002] 1. Field of the Invention The present disclosure relates to fluid catalytic cracking systems and processes, and more particularly to downer fluid catalytic cracking systems and processes.

[0003] 2. Description of the Prior Art The fluidized catalytic cracking (FCC) process is widely used to convert hydrocarbon feedstreams, such as vacuum gas oil and other relatively heavy oils, into lighter, more valuable hydrocarbon products. The basic components of a downer FCC system include at least one reactor, a spent catalyst riser, and a catalyst regenerator. In some cases, a catalyst cooler is installed in the catalyst regenerator to control the regenerator temperature within reasonable limits when processing heavy feedstocks. Several catalyst coolers have been installed in many FCC regenerators with conventional upflow riser reactor systems. In systems where a cooler is installed on the regenerator, the main purpose is to remove excess heat from the regenerator through steam generation. Without a catalyst cooler, the regenerator would operate at a temperature higher than the design temperature, or the throughput of the FCC unit would be reduced to maintain the regenerator temperature within the desired limits. There are other conventional processes for controlling the temperature of the catalyst entering the regenerator from the stripper. This is generally applicable to FCC units operating at very high temperatures. Cooling the catalyst in the stripper reduces the particle temperature prior to the combustion process, thus eliminating catalyst deactivation due to sintering.

[0004] These cooling techniques are described in various U.S. patents, such as U.S. Patent Nos. 5,209,287, 4,615,992, 5,571,482, 4,965,232, and 7,273,543. These patents describe systems that control either the regenerator temperature or the catalyst combustion temperature within the regenerator. Lowering the overall regenerator temperature to increase the catalyst-to-oil ratio and increase conversion can result in reduced combustion efficiency, insufficient regeneration, and the production of regenerated catalyst with a high catalytic coke content that reduces catalytic activity.

[0005] Conventional techniques have been deemed satisfactory for their intended purposes. However, there is a continuing need for improved catalyst cooling systems that improve catalyst-to-oil ratios and increase conversion while maintaining combustion efficiency. The present disclosure provides a solution to this need. Summary of the Invention

[0006] A process for controlling catalyst temperature in a fluid catalytic cracking ("FCC") system includes regenerating a spent catalyst feed at a first temperature in a regenerator to produce a regenerated catalyst feed, recovering at least a portion of the regenerated catalyst feed to a reactor, and cooling the portion of the regenerated catalyst between an outlet of the regenerator and an inlet of the reactor.

[0007] One or more embodiments include the process of any preceding paragraph, wherein the spent catalyst feed can include light feed (LF) spent catalyst and heavy feed (HF) spent catalyst.

[0008] One or more embodiments include the process of any preceding paragraph, wherein the reactor can be an HF reactor.

[0009] One or more embodiments include the process of any preceding paragraph, wherein the process can include providing a portion of the regenerated catalyst feed to a recovery well upstream from the reactor.

[0010] One or more embodiments include the process of any preceding paragraph, wherein cooling the portion of the regenerated catalyst can include cooling the portion of the regenerated catalyst in a catalyst cooler in the recovery well.

[0011] One or more embodiments include the process of any preceding paragraph, wherein the process can include providing a portion of the regenerated catalyst feed to a recovery well before the reactor; providing a second portion of the regenerated catalyst feed from the regenerator to a catalyst cooler before the reactor; and cooling the second portion of the regenerated catalyst in the catalyst cooler to produce a cooled second portion of the regenerated catalyst.

[0012] One or more embodiments include the process of any preceding paragraph, wherein cooling the portion of the regenerated catalyst can include cooling the portion of the regenerated catalyst in the recovery well by returning the cooled second portion from the catalyst cooler to the recovery well to produce cooled regenerated catalyst.

[0013] One or more embodiments include the process of any of the preceding paragraphs, including providing a portion of the regenerated catalyst feed to a recovery well before the reactor; providing a second portion of the regenerated catalyst from the recovery well to a catalyst cooler before the reactor; and cooling the second portion of the regenerated catalyst in the catalyst cooler to produce a cooled second portion of the regenerated catalyst.

[0014] One or more embodiments include the process of any preceding paragraph, wherein cooling the portion of the regenerated catalyst can include cooling the portion of the regenerated catalyst in the recovery well by returning the cooled second portion from the catalyst cooler to the recovery well to produce cooled regenerated catalyst.

[0015] One or more embodiments include the process of any preceding paragraph, wherein the regenerator can be a common regenerator.

[0016] One or more embodiments include the process of any preceding paragraph, wherein regenerating the spent catalyst feed can include regenerating the LF spent catalyst and the HF spent catalyst in a common regenerator at the first regenerator operating temperature.

[0017] One or more embodiments include the process of any preceding paragraph, wherein cooling the portion of the regenerated catalyst can include cooling the portion of the regenerated catalyst to a second temperature that is lower than the first regenerator operating temperature.

[0018] According to another aspect, a fluid catalytic cracking ("FCC") system includes a catalyst regenerator configured and adapted to regenerate a spent catalyst feed at a first temperature to produce regenerated catalyst, a reactor downstream from an outlet of the catalyst regenerator, and a catalyst cooler between the outlet of the catalyst regenerator and an inlet of the reactor. The catalyst cooler is configured and adapted to cool at least a portion of the regenerated catalyst from the catalyst regenerator.

[0019] One or more embodiments include the system of any preceding paragraph, wherein the reactor can be an HF reactor and the outlet of the catalyst regenerator can be the first outlet.

[0020] One or more embodiments include the system of any preceding paragraph, wherein the system can include a second reactor downstream from the second outlet of the catalyst regenerator.

[0021] One or more embodiments include the system of any preceding paragraph, wherein the second reactor can be an LF reactor.

[0022] One or more embodiments include the system of any preceding paragraph, wherein both the spent catalyst outlet of the LF reactor and the spent catalyst outlet of the HF reactor can be in fluid communication with respective inlets of a catalyst regenerator, which can be a common regenerator.

[0023] One or more embodiments include the system of any preceding paragraph, wherein the reactor can be an HF reactor.

[0024] One or more embodiments include the system of any preceding paragraph, wherein the system can include a collection well downstream of the catalyst regenerator and upstream of the reactor.

[0025] One or more embodiments include the system of any preceding paragraph, wherein the system can include a slide valve between the outlet of the catalyst regenerator and the inlet of the collection well to control the regenerated catalyst entering the collection well.

[0026] One or more embodiments include the system of any preceding paragraph, wherein the catalyst cooler can be separate from the catalyst regenerator.

[0027] One or more embodiments include the system of any preceding paragraph, wherein the catalyst cooler can be downstream from the collection well.

[0028] These and other features of the systems and methods of the present disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings. [Brief explanation of the drawings]

[0029] Preferred embodiments of the present disclosure are described in detail herein below with reference to specific figures so that those skilled in the art to which the present disclosure pertains will readily understand how to make and use the devices and methods of the present disclosure without undue experimentation. [Figure 1] FIG. 1 is a schematic plan view of a fluid catalytic cracking system with catalyst cooling according to an embodiment of the present disclosure, showing catalyst cooling tubes within a recovery well. [Figure 2] FIG. 2 is a schematic plan view of a fluid catalytic cracking system with catalyst cooling according to another embodiment of the present disclosure, showing a catalyst cooler unit downstream from the regenerator. [Figure 3] FIG. 2 is a schematic plan view of a fluid catalytic cracking system with catalyst cooling according to another embodiment of the present disclosure, showing a catalyst cooler unit downstream from the recovery well. DETAILED DESCRIPTION OF THE INVENTION

[0030] Reference is now made to the drawings, in which like reference numerals identify like structural features or aspects of the present disclosure. For purposes of explanation and illustration, and not limitation, a schematic diagram of an exemplary embodiment of a fluid catalytic cracking (FCC) system having a catalyst cooler according to the present disclosure is shown in FIG. 1 and is designated generally by the reference numeral 100. Other embodiments of FCC systems according to the present disclosure, or aspects thereof, as illustrated, are provided in FIGS. 2 and 3. Using the systems and methods described herein, the operation of the regenerator can be decoupled from the temperature of the regenerated catalyst entering the heavy feed downer, allowing the regenerator to operate at the optimum temperature for the light feed system while still optimizing the catalyst / oil in the heavy downer.

[0031] As shown in FIG. 1 , a fluid catalytic cracking (FCC) system 100, e.g., a high severity FCC (HS-FCC) system, includes a catalyst regenerator 102 configured and adapted to regenerate a spent catalyst feed at a first temperature to produce a regenerated catalyst. The system 100 includes a recovery well 104 downstream from a first outlet 106 of the catalyst regenerator 102, a plurality of downer trains 108 that process a heavy feed (HF) hydrocarbon feedstock in combination with the regenerated catalyst from the regenerator 102, and a reactor 110 downstream from the downer train 108. The reactor 110 is a heavy feed (HF) reactor. The system 100 includes a second reactor 111, e.g., a light feed (LF) reactor, that processes the LF hydrocarbon feedstock in combination with the regenerated catalyst from the regenerator 102. The second reactor 111 is downstream from a second outlet 105 of the catalyst regenerator 102. In some embodiments, the recovery well 109 is positioned between the second outlet 105 and the LF reactor 111. The spent catalyst outlet 120 of the LF reactor 111 and the spent catalyst outlet 122 of the HF reactor 110 are both in fluid communication with a common regenerator, the catalyst regenerator 102. The system 100 includes a catalyst cooler 112 integrated into the recovery well 104 between the outlet 106 of the catalyst regenerator 102 and the inlet 114 of the reactor 110. In an embodiment of the system 100, the catalyst cooler 112 includes catalyst cooling tubes 116 within the recovery well 104. The catalyst cooler 112 is configured and adapted to cool at least a portion of the regenerated catalyst from the catalyst regenerator 102. By providing cooling to the HF regeneration catalyst downstream from the regenerator 102, the regenerator 102 is allowed to operate at a higher temperature to meet the heat demand for cracking the LF, while reducing the regenerated catalyst temperature to the HF downer 108.

[0032] Continuing with FIG. 1 , system 100 includes downer trains 107 and 108, each processing a different type of hydrocarbon feedstock, a light feed (LF) and a heavy feed (HF), respectively. Downer train 107 supplies LF to LF reactor 111, and downer train 108 supplies HF to HF reactor 110. LF is highly paraffinic and requires operation at high severity conditions, such as a catalyst-to-oil ratio of 30-40, e.g., 30, and a reactor outlet temperature (ROT) of 1160-1200°F. HF, on the other hand, behaves more like a typical vacuum gas oil (VGO) or mild resid feedstock and requires operation at lower severity, such as a catalyst-to-oil ratio of 30-40, e.g., 30, and a ROT of 1150-1160°F. Due to the low overall coke production and high catalyst-to-oil ratio, the regenerator 102 is operated below 1300°F. Typically, make-up injection of torch oil is used to maintain the regenerator temperature optimal for LF cracking. Therefore, installing a catalyst cooler on the regenerator itself to cool the catalyst to within the desired inlet temperature of the HF reactor 110 would overcool the regenerator and reduce its regeneration efficiency.

[0033] Referring now to Figure 2, another embodiment of an FCC system 200, e.g., an HS-FCC, is the same as the FCC system 100 of Figure 1, except that the fluid catalytic cracking (FCC) system 200 includes a separate catalyst cooler 212. System 200 includes the same downer trains 107 and 108 as system 100. Like system 100, system 200 includes a catalyst regenerator 102, a recovery well 104 downstream from the outlet 106 of the catalyst regenerator 102, multiple downer trains 108 that process the feed from the regenerator 102, and a reactor 110 downstream from the downer train 108. In an embodiment of system 200, the catalyst cooler 212 is separate from the recovery well 104. The catalyst cooler 212 includes catalyst cooling tubes 216.

[0034] An inlet 217 of the catalyst cooler 212 receives a second portion of the regenerated catalyst feed from the regenerator 102 and cools the second portion. Once cooled, the cooled second portion is returned to the recovery well 104 through an outlet 219 of the catalyst cooler 212 and mixed with the first portion of the regenerated catalyst feed entering the recovery well 104 through the outlet 106 of the regenerator 102 to achieve a desired catalyst temperature for controlling the catalyst-to-oil ratio.

[0035] Continuing to refer to FIG. 2 , system 200 includes a control valve 218, e.g., a slide valve, between the regenerator 102 and the recovery well 104. The slide valve 218 is installed to control the flow of hot catalyst into the recovery well 104. Compared to the embodiment of system 100, system 200 offers greater flexibility because the slide valve 218 is used on the inlet of the recovery well 104 to meter the amount of catalyst bypassing the catalyst cooler 212 to achieve the desired catalyst temperature to the downer 108. This configuration achieves a high degree of flexibility and provides nearly infinite control of the catalyst-to-oil ratio. As with system 100, providing cooling to the HF regeneration catalyst downstream from the regenerator 102 via the catalyst cooler 212 allows the regenerator 102 to operate at a higher temperature to meet the heat demand for cracking LF, while reducing the regeneration catalyst temperature to the HF downer 108.

[0036] 3, another embodiment of an FCC system 300, e.g., an HS-FCC, is the same as FCC system 200 of FIG. 1, except that a separate catalyst cooler 312 of fluid catalytic cracking (FCC) system 300 receives a second portion of the HF-regenerated catalyst, e.g., high-temperature catalyst, from recovery well 104 at inlet 317 of catalyst cooler 312 rather than directly from regenerator 102. Once cooled, the cooled second portion is returned to recovery well 104 at outlet 319 of catalyst cooler 312 and mixed with the first portion of the regenerated catalyst feed entering recovery well 104 at outlet 106 of regenerator 102 to achieve a desired regenerated catalyst temperature at a desired operating setpoint for controlling the catalyst-to-oil ratio.

[0037] 1-3 each include a catalyst cooler between the catalyst regenerator outlet and the reactor inlet, thereby decoupling the regenerator operation from the temperature of the catalyst entering the HF downer, allowing the catalyst-to-oil ratio in the HF downer to be optimized while still operating the regenerator at the LF system optimum temperature. While the embodiments herein are shown and described for a dual downer unit, they are equally applicable to HS-FCC single downer systems.

[0038] According to the embodiment of Figures 1-3, a process for controlling catalyst temperature in an FCC system, e.g., system 100, 200, or 300, includes regenerating a spent catalyst feed at a first temperature in a regenerator, e.g., regenerator 102, to produce a regenerated catalyst feed; recovering at least a portion of the regenerated catalyst feed to a reactor, e.g., reactor 110; and cooling the portion of the regenerated catalyst in a catalyst cooler, e.g., catalyst cooler 112, 212, or 312, between an outlet, e.g., outlet 106, of the regenerator and an inlet, e.g., inlet 114, of the reactor. The regenerator is a common regenerator, and regenerating the spent catalyst feed includes regenerating a light feed (LF) spent catalyst and a heavy feed (HF) spent catalyst at the first temperature in the common regenerator. The process includes providing a portion of the regenerated catalyst feed to a recovery well, e.g., recovery well 104, upstream from the reactor. Cooling the portion of the regenerated catalyst includes cooling the portion of the regenerated catalyst to a second temperature lower than the first regenerator operating temperature. According to the embodiment of FIG. 1, cooling the portion of the regenerated catalyst includes cooling the portion of the regenerated catalyst using a catalyst cooler, such as catalyst cooler 112, in the recovery well.

[0039] According to the embodiment of Figure 2, the method includes providing a second portion of the regenerated catalyst feed from the regenerator to a catalyst cooler before the reactor, e.g., catalyst cooler 212, and cooling the second portion of the regenerated catalyst in the catalyst cooler to produce a cooled second portion of the regenerated catalyst. According to the embodiment of Figure 2, cooling the portion of the regenerated catalyst includes cooling the portion of the regenerated catalyst in the recovery well by returning the cooled second portion from the catalyst cooler to the recovery well to produce cooled regenerated catalyst.

[0040] According to the embodiment of Figure 3, the method includes providing a second portion of the regenerated catalyst from the recovery well to a catalyst cooler before the reactor, such as catalyst cooler 312, and cooling the second portion of the regenerated catalyst in the catalyst cooler to produce a cooled second portion of the regenerated catalyst. According to the embodiment of Figure 3, cooling the portion of the regenerated catalyst includes cooling the portion of the regenerated catalyst in the recovery well by returning the cooled second portion from the catalyst cooler to the recovery well to produce cooled regenerated catalyst.

[0041] The methods and systems of the present disclosure, as described above and shown in the drawings, provide FCC systems and methods with superior properties, including improved catalyst temperature control that allows for optimizing the catalyst-to-oil ratio in the HF downer while still operating the regenerator at the LF system optimum temperature. The systems and methods of the present invention may be applied to HS-FCC dual downer systems, HS-FCC single downer systems, or the like. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily understand that changes and / or modifications may be made therein without departing from the scope of the subject disclosure.

Claims

1. 1. A process for controlling catalyst temperature in a fluid catalytic cracking ("FCC") system, comprising: regenerating the spent catalyst feed at a first temperature in a regenerator to produce a regenerated catalyst feed; recovering at least a portion of the regenerated catalyst feed to a reactor; and cooling said portion of said regenerated catalyst between an outlet of said regenerator and an inlet of said reactor.

2. 10. The process of claim 1, wherein the spent catalyst feed comprises a light feed (LF) spent catalyst and a heavy feed (HF) spent catalyst.

3. 10. The process of claim 1, wherein the reactor is an HF reactor.

4. 2. The process of claim 1, further comprising providing said portion of said regenerated catalyst feed to a recovery well upstream from said reactor, and wherein cooling said portion of said regenerated catalyst comprises cooling said portion of said regenerated catalyst using a catalyst cooler in said recovery well.

5. 2. The process of claim 1, further comprising: providing the portion of the regenerated catalyst feed to a recovery well before the reactor; providing a second portion of the regenerated catalyst feed from the regenerator to a catalyst cooler before the reactor; and cooling the second portion of the regenerated catalyst in the catalyst cooler to produce a cooled second portion of the regenerated catalyst, wherein cooling the portion of the regenerated catalyst comprises cooling the portion of the regenerated catalyst in the recovery well by returning the cooled second portion from the catalyst cooler to the recovery well to produce cooled regenerated catalyst.

6. 2. The process of claim 1, further comprising: providing the portion of the regenerated catalyst feed to a recovery well before the reactor; providing a second portion of the regenerated catalyst from the recovery well to a catalyst cooler before the reactor; and cooling the second portion of the regenerated catalyst in the catalyst cooler to produce a cooled second portion of the regenerated catalyst, wherein cooling the portion of the regenerated catalyst comprises cooling the portion of the regenerated catalyst in the recovery well by returning the cooled second portion from the catalyst cooler to the recovery well to produce cooled regenerated catalyst.

7. 2. The process of claim 1, wherein the regenerator is a common regenerator, and regenerating the spent catalyst feed comprises regenerating a light feed (LF) spent catalyst and a heavy feed (HF) spent catalyst in the common regenerator at the first regenerator operating temperature.

8. 8. The process of claim 7, wherein cooling the portion of the regenerated catalyst comprises cooling the portion of the regenerated catalyst to a second temperature that is lower than the first regenerator operating temperature.

9. 1. A fluid catalytic cracking ("FCC") system comprising: a catalyst regenerator configured and adapted to regenerate the spent catalyst feed at a first temperature to produce a regenerated catalyst; a reactor downstream from the outlet of the catalyst regenerator; a catalyst cooler between the outlet of the catalyst regenerator and the inlet of the reactor, the catalyst cooler configured and adapted to cool at least a portion of the regenerated catalyst from the catalyst regenerator.

10. 10. The system of claim 9, wherein the reactor is an HF reactor, the outlet of the catalyst regenerator is a first outlet, and the system further comprises a second reactor downstream from a second outlet of the catalyst regenerator.

11. 11. The system of claim 10, wherein the second reactor is an LF reactor, and both the spent catalyst outlet of the LF reactor and the spent catalyst outlet of the HF reactor are in fluid communication with respective inlets of the catalyst regenerator, which is a common regenerator.

12. 10. The system of claim 9, wherein the reactor is an HF reactor.

13. 10. The system of claim 9, further comprising a collection well downstream of the catalyst regenerator and upstream of the reactor.

14. 14. The system of claim 13, further comprising a slide valve between the outlet of the catalyst regenerator and the inlet of the collection well to control the regenerated catalyst entering the collection well.

15. The system of claim 13 , wherein the catalyst cooler is separate from the catalyst regenerator.

16. The system of claim 13 , wherein the catalyst cooler is downstream from the collection well.

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