System and method for temperature control in fluid catalytic cracking

Abstract

A method for controlling catalyst temperature in a fluid catalytic cracking ("FCC") system includes regenerating a spent catalyst feed in a regenerator at a first temperature to produce a regenerated catalyst feed, drawing at least a portion of the regenerated catalyst feed to a reactor, and cooling the portion of the regenerated catalyst between the outlet of the regenerator and the inlet of the reactor. 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 a regenerated catalyst, a reactor downstream of an outlet of the catalyst regenerator, 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. In an embodiment, the FCC system is a downer FCC system that includes at least one downer reactor and a spent catalyst riser regenerator.

Description

[0001] Cross - Reference to Related Applications

[0002] This subject application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 374,240, filed on August 31, 2022, the entire disclosure of which is incorporated herein by reference. Background Art 1. Field of the Technology

[0003] This disclosure relates to fluid catalytic cracking systems and methods, and more particularly to downflow bed fluid catalytic cracking systems and methods.

[0004] 2. Related Technologies

[0005] Fluid catalytic cracking (“FCC”) processes are widely used to convert hydrocarbon feed streams, such as vacuum gas oil and other relatively heavy oils, into lighter and more valuable hydrocarbon products. The basic components of a downflow bed FCC system include at least one reactor, a spent catalyst riser, and a catalyst regenerator. In some cases, a catalyst cooler is installed on the catalyst regenerator to control the regenerator temperature within reasonable limits when processing heavy feeds. Several catalyst coolers have been installed on many FCC regenerators with traditional upflow riser reaction systems. The main purpose of the systems where the cooler is installed on the regenerator is to remove excess heat from the regenerator through steam generation. In the absence of 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 traditional methods for controlling the temperature of the catalyst entering the regenerator from the stripping column. This is typically applicable to FCC units operating at very high temperatures. Cooling the catalyst in the stripping column reduces the particle temperature prior to the combustion process and thus eliminates catalyst deactivation due to sintering.

[0006] These cooling techniques are described in a number of 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 for controlling the regenerator temperature or the catalyst combustion temperature in the regenerator. To increase the catalyst - to - oil ratio and improve the conversion rate, reducing the overall regenerator temperature may reduce the combustion efficiency and result in incomplete regeneration, producing a regenerated catalyst with a high catalyst coke content, which reduces the catalyst activity.

[0007] Traditional techniques have been considered to meet their intended purposes. However, there has always been a need for an improved catalyst cooling system that has an improved catalyst - to - oil ratio and increased conversion rate while maintaining the combustion efficiency. This disclosure provides a solution to this need. SUMMARY OF THE INVENTION

[0008] A method for controlling the temperature of a catalyst in a fluidized catalytic cracking (“FCC”) system includes regenerating a spent catalyst feed in a regenerator at a first temperature to produce a regenerated catalyst feed, withdrawing 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.

[0009] One or more embodiments include the method of any of the preceding paragraphs, and wherein the spent catalyst feed may include light feed (LF) spent catalyst and heavy feed (HF) spent catalyst.

[0010] One or more embodiments include the method of any of the preceding paragraphs, and wherein the reactor may be an HF reactor.

[0011] One or more embodiments include the method of any of the preceding paragraphs, and wherein the method may include providing the portion of the regenerated catalyst feed to a withdrawal well upstream of the reactor.

[0012] One or more embodiments include the method of any of the preceding paragraphs, and wherein cooling the portion of the regenerated catalyst may include cooling the portion of the regenerated catalyst with a catalyst cooler within the withdrawal well.

[0013] One or more embodiments include the method of any of the preceding paragraphs, and wherein the method may include providing the portion of the regenerated catalyst feed to a withdrawal well prior to the reactor, providing a second portion of the regenerated catalyst feed from the regenerator to a catalyst cooler prior to 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 method of any of the preceding paragraphs, and wherein cooling the portion of the regenerated catalyst may include cooling the portion of the regenerated catalyst in the withdrawal well by returning the cooled second portion from the catalyst cooler to the withdrawal well to produce a cooled regenerated catalyst.

[0015] One or more embodiments include the method of any of the preceding paragraphs, and wherein the method includes providing the portion of the regenerated catalyst feed to a withdrawal well prior to the reactor, providing a second portion of the regenerated catalyst from the withdrawal well to a catalyst cooler prior to 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.

[0016] One or more embodiments include the method of any of the preceding paragraphs, and wherein cooling that portion of the regenerated catalyst can include cooling that portion of the regenerated catalyst in the draw well by returning the cooled second portion from the catalyst cooler to the draw well to produce cooled regenerated catalyst.

[0017] One or more embodiments include the method of any of the preceding paragraphs, and wherein the regenerator can be a common regenerator.

[0018] One or more embodiments include the method of any of the preceding paragraphs, and wherein the regenerated spent catalyst feed can include regenerating LF spent catalyst and HF spent catalyst in a common regenerator at a first regenerator operating temperature.

[0019] One or more embodiments include the method of any of the preceding paragraphs, and wherein cooling that portion of the regenerated catalyst can include cooling that portion of the regenerated catalyst to a second temperature that is lower than the first regenerator operating temperature.

[0020] 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 a regenerated catalyst, a reactor downstream of 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.

[0021] One or more embodiments include the system of any of the preceding paragraphs, and wherein the reactor can be an HF reactor and wherein the outlet of the catalyst regenerator can be a first outlet.

[0022] One or more embodiments include the system of any of the preceding paragraphs, and wherein the system can include a second reactor downstream of a second outlet of the catalyst regenerator.

[0023] One or more embodiments include the system of any of the preceding paragraphs, and wherein the second reactor can be an LF reactor.

[0024] One or more embodiments include the system of any of the preceding paragraphs, and wherein the spent catalyst outlets of the LF reactor and the HF reactor can each be in fluid communication with a respective inlet of the catalyst regenerator, which can be a common regenerator.

[0025] One or more embodiments include the system of any of the preceding paragraphs, and wherein the reactor can be an HF reactor.

[0026] One or more embodiments include the system of any of the preceding paragraphs, and wherein the system can include a draw well downstream of the catalyst regenerator and upstream of the reactor.

[0027] One or more embodiments include the system of any of the preceding paragraphs, and wherein the system may include a slide valve between the outlet of the catalyst regenerator and the inlet of the draw well to control the entry of regenerated catalyst into the draw well.

[0028] One or more embodiments include the system of any of the preceding paragraphs, and wherein the catalyst cooler may be separate from the catalyst regenerator.

[0029] One or more embodiments include the system of any of the preceding paragraphs, and wherein the catalyst cooler may be downstream of the draw well.

[0030] These and other features of the systems and methods of the present disclosure will become more apparent to those skilled in the art from the following detailed description of the preferred embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Thus, 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. Certain preferred embodiments herein will be described in detail below with reference to certain drawings, wherein:

[0032] Figure 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 in a draw well;

[0033] Figure 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 of the regenerator; and

[0034] Figure 3 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 of the draw well. DETAILED DESCRIPTION

[0035] Reference will now be made to the accompanying drawings, in which like reference numerals identify similar structural features or aspects of the present disclosure. For purposes of explanation and illustration, and not limitation, a schematic illustration of an exemplary embodiment of a fluid catalytic cracking (FCC) system with a catalyst cooler in accordance with the present disclosure is shown in Figure 1 and is generally designated by reference numeral 100. As will be described, in Figures 2 to 3Other embodiments of an FCC system in accordance with the present disclosure or aspects thereof are provided. The systems and methods described herein can be used to decouple regenerator operation from the temperature of the regenerated catalyst entering the heavy feed downcomer bed and allow for optimization of the catalyst / oil in the heavy downcomer bed while still operating the regenerator at the optimal temperature for the light feed system

[0036] As Figure 1 shown, a fluid catalytic cracking (FCC) system 100 (e.g., a high severity FCC (HS-FCC)) includes a catalyst regenerator 102 that is configured and adapted to regenerate a spent catalyst feed at a first temperature to produce a regenerated catalyst. The system 100 includes a draw well 104 downstream of a first outlet 106 of the catalyst regenerator 102, a plurality of downcomer beds 108 in series that process a heavy feed (HF) hydrocarbon feedstock in combination with the regenerated catalyst from the regenerator 102, and a reactor 110 downstream of the downcomer bed series 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 an LF hydrocarbon feedstock in combination with the regenerated catalyst from the regenerator 102. The second reactor 111 is downstream of a second outlet 105 of the catalyst regenerator 102. In some embodiments, a draw well 109 is located 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 the catalyst regenerator 102, which is a common regenerator. The system 100 includes a catalyst cooler 112 integrated into the draw 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 in the draw 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 regenerated catalyst downstream of the regenerator 102, the regenerator 102 is allowed to operate at a high temperature to meet the heat demand for cracking the LF while reducing the temperature of the regenerated catalyst to the HF downcomer bed 108

[0037] Continuing reference to Figure 1, System 100 includes downcomer trains 107 and 108, each of which processes a different type of hydrocarbon feedstock: light feed (LF) and heavy feed (HF). Downcomer train 107 supplies the LF to LF reactor 111, and downcomer train 108 supplies the HF to HF reactor 110. The paraffin content of the LF is very high and requires operation under very severe conditions, such as a catalyst-to-oil ratio of 30 - 40 (e.g., 30) and a reactor outlet temperature (ROT) of 1160°F - 1200°F. On the other hand, the HF behaves like a typical vacuum gas oil (VGO) or mild residue feedstock and requires operation at a lower severity catalyst-to-oil ratio of 30 - 40 (e.g., 30) and a ROT of 1150°F - 1160°F. Due to the low total coke makeup and high catalyst-to-oil ratio, the regenerator 102 operates at below 1300°F. Typically, supplementary quench oil injection is used to maintain the regenerator temperature optimized for LF cracking. Thus, installing a catalyst cooler on the regenerator itself to cool the catalyst within the desired inlet temperature of the HF reactor 110 will overcool the regenerator and reduce its regeneration efficiency.

[0038] Now referring to Figure 2 , another embodiment of the FCC system 200 (e.g., HS-FCC) is the same as the Figure 1 FCC system 100, except that the fluid catalytic cracking (FCC) system 200 includes a separate catalyst cooler 212. System 200 includes downcomer trains 107 and 108, which are the same as the downcomer trains in system 100. Similar to system 100, system 200 includes a catalyst regenerator 102, a draw well 104 downstream of the outlet 106 of the catalyst regenerator 102, a plurality of downcomer trains 108 that process the feedstock from the regenerator 102, and a reactor 110 downstream of the downcomer trains 108. In an embodiment of system 200, the catalyst cooler 212 is separate from the draw well 104. The catalyst cooler 212 includes catalyst cooling tubes 216.

[0039] The inlet 217 of the catalyst cooler 212 receives a second portion of the regenerated catalyst feed from the regenerator 102 and cools this second portion. Once cooled, the cooled second portion returns from the outlet 219 of the catalyst cooler 212 to the draw well 104 for mixing with a first portion of the regenerated catalyst feed that enters the draw well 104 from the outlet 106 of the regenerator 102 to achieve the desired catalyst temperature, thereby controlling the catalyst-to-oil ratio.

[0040] Continuing to refer to Figure 2, the system 200 includes a control valve 218, such as a slide valve, between the regenerator 102 and the draw well 104. The slide valve 218 is installed to control the flow of hot catalyst into the draw well 104. Compared with the embodiment of the system 100, the system 200 provides greater flexibility because a slide valve 218 is used at the inlet of the draw well 104 to meter the amount of catalyst bypassing the catalyst cooler 212 to achieve the desired catalyst temperature in the downcomer bed 108. This configuration achieves a high degree of flexibility, resulting in an almost infinite control of the catalyst-to-oil ratio. Similar to the system 100, cooling is provided to the HF regenerated catalyst downstream of the regenerator 102 via the catalyst cooler 212, allowing the regenerator 102 to operate at a high temperature to meet the heat demand for cracking LF while reducing the temperature of the regenerated catalyst in the HF downcomer bed 108.

[0041] As Figure 3 shown, another embodiment of an FCC system 300 (such as an HS-FCC) is the same as the Figure 1 FCC system 200, except that a separate catalyst cooler 312 of the fluid catalytic cracking (FCC) system 300 receives a second portion (such as hot catalyst) of the HF regenerated catalyst from the draw well 104 at the inlet 317 of the catalyst cooler 312 rather than a second portion of the HF regenerated catalyst directly from the regenerator 102. Once cooled, the cooled second portion returns from the outlet 319 of the catalyst cooler 312 to the draw well 104 for mixing with the first portion of the regenerated catalyst feed entering the draw well 104 from the outlet 106 of the regenerator 102 to achieve the desired regenerated catalyst temperature at the desired operating set point, thereby controlling the catalyst-to-oil ratio.

[0042] Embodiments of the present disclosure, such as Figures 1 to 3 those shown in

[0043] According to Figures 1 to 3An embodiment for controlling the catalyst temperature in an FCC system (such as system 100, 200, or 300) includes regenerating a spent catalyst feed in a regenerator (such as regenerator 102) at a first temperature to produce a regenerated catalyst feed, withdrawing at least a portion of the regenerated catalyst feed to a reactor (such as reactor 110), and cooling this portion of the regenerated catalyst in a catalyst cooler (such as catalyst cooler 112, 212, or 312) between the outlet of the regenerator (such as outlet 106) and the inlet of the reactor (such as inlet 114). The regenerator is a common regenerator and the spent catalyst feed includes regenerating a light feed (LF) spent catalyst and a heavy feed (HF) spent catalyst in the common regenerator at a first temperature. The method includes providing this portion of the regenerated catalyst feed to a draw well (such as draw well 104) upstream of the reactor. Cooling this portion of the regenerated catalyst includes cooling this portion of the regenerated catalyst to a second temperature below the first regenerator operating temperature. According to Figure 1 An embodiment, cooling this portion of the regenerated catalyst includes cooling this portion of the regenerated catalyst with a catalyst cooler (such as catalyst cooler 112) within the draw well.

[0044] According to Figure 2 An embodiment, the method includes providing a second portion of the regenerated catalyst feed from the regenerator to a catalyst cooler (such as catalyst cooler 212) 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. According to Figure 2 An embodiment, cooling this portion of the regenerated catalyst includes cooling this portion of the regenerated catalyst in the draw well by returning the cooled second portion from the catalyst cooler to the draw well to produce a cooled regenerated catalyst.

[0045] According to Figure 3 An embodiment, the method includes providing a second portion of the regenerated catalyst from the draw well to a catalyst cooler (such as catalyst cooler 312) 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. According to Figure 3 An embodiment, cooling this portion of the regenerated catalyst includes cooling this portion of the regenerated catalyst in the draw well by returning the cooled second portion from the catalyst cooler to the draw well to produce a cooled regenerated catalyst.

[0046] The methods and systems of the present disclosure as shown and illustrated in the accompanying drawings provide an FCC system and method with excellent performance, including improved catalyst temperature control, allowing optimization of the catalyst-to-oil ratio in the HF downcomer bed while still operating the regenerator at the optimal temperature of the LF system. The systems and methods of the present invention can be applied to HS-FCC dual downcomer bed systems, HS-FCC single downcomer bed systems, etc. Although the devices and methods of the present subject matter have been shown and described with reference to preferred embodiments, those skilled in the art will readily understand that changes and / or modifications can be made thereto without departing from the scope of the present subject matter.

Claims

1. A method for controlling the temperature of a catalyst in a fluid catalytic cracking ("FCC") system, the method comprising: regenerating a spent catalyst feed in a regenerator at a first temperature to produce a regenerated catalyst feed; withdrawing 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.

2. The method according to claim 1, wherein the spent catalyst feed comprises a light feed (LF) spent catalyst and a heavy feed (HF) spent catalyst.

3. The method according to claim 1, wherein the reactor is an HF reactor.

4. The method according to claim 1, the method further comprising providing the portion of the regenerated catalyst feed to a draw well upstream of the reactor, wherein cooling the portion of the regenerated catalyst comprises cooling the portion of the regenerated catalyst with a catalyst cooler within the draw well.

5. The method according to claim 1, the method further comprising providing the portion of the regenerated catalyst feed to a draw 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 draw well by returning the cooled second portion from the catalyst cooler to the draw well to produce a cooled regenerated catalyst.

6. The method according to claim 1, the method further comprising providing the portion of the regenerated catalyst feed to a draw well before the reactor, providing a second portion of the regenerated catalyst from the draw 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 draw well by returning the cooled second portion from the catalyst cooler to the draw well to produce a cooled regenerated catalyst.

7. The method according to claim 1, wherein the regenerator is a common regenerator, wherein 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 a first regenerator operating temperature.

8. The method according to claim 7, wherein cooling the portion of the regenerated catalyst comprises cooling the portion of the regenerated catalyst to a second temperature below the first regenerator operating temperature.

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

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

11. The system according to claim 10, wherein the second reactor is an LF reactor, wherein the spent catalyst outlet of the LF reactor and the spent catalyst outlet of the HF reactor are each in fluid communication with a corresponding inlet of the catalyst regenerator, and the catalyst regenerator is a common regenerator.

12. The system according to claim 9, wherein the reactor is an HF reactor.

13. The system according to claim 9, the system further comprising a draw well downstream of the catalyst regenerator and upstream of the reactor.

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

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

16. The system according to claim 13, wherein the catalyst cooler is downstream of the draw well.

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