Catalytic cracking system with bio-oil processing

Abstract

A catalytic cracking system in which liquid hydrocarbons and bio-oil are guided by separate feed spray nozzle assemblies into the reactor riser of a fluid catalytic cracking unit. To protect the liquid bio-oil guided through the liquid bio-oil feed nozzle assembly from high-temperature degradation, an insulating layer is provided between the central bio-oil feed pipes in concentrically enclosed atomizing gas passages. Cooling channels may also be provided in the spray tip of the bio-oil feed nozzle assembly.

Description

[0001] Cross-reference to related applications This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 872,965, filed July 11, 2019, which is incorporated herein by reference. Technical Field

[0002] The present invention generally relates to catalytic cracking systems, and more specifically, to spray nozzle assemblies suitable for atomizing and injecting liquid bio-oil feed into fluidized catalytic cracking reactors. Background Technology

[0003] Fluid catalytic cracking (FCC) is important in the petroleum refining industry and is used worldwide to convert heavy hydrocarbons into products such as liquefied petroleum gas (LPG), gasoline, and diesel fuels. Renewable energy sources, such as bio-oils produced by the rapid pyrolysis of bio-oils from materials like pine chips, corn cobs, other plants, and organic materials, as well as vegetable oils, are increasingly important as alternatives to or supplements to crude oil as processed fuels. The FCC process can be similarly used to produce hydrocarbon fuels from bio-oils. Desired results can be obtained when bio-oil is co-processed with crude oil feedstock. Due to the temperature instability of bio-oils, care must be taken when injecting them into the FCC riser. Exposing bio-oil to high temperatures can cause premature polymerization and nozzle clogging. Summary of the Invention

[0004] The purpose of this invention is to provide a reliable, non-clogging, and efficient bio-oil atomization and injection system for the co-processing of bio-oil and hydrocarbon feedstock in a fluid catalytic cracking system.

[0005] Another objective is to provide a bio-oil feed assembly that can operate efficiently at the operating temperatures associated with a catalytic cracking system and at reasonable temperatures associated with the atomization of bio-oil vapors, fuel gases, nitrogen, and other gases.

[0006] Another objective is to provide bio-oil feed nozzle assemblies of the above types, wherein the liquid bio-oil feed is maintained at an optimal temperature below its polymerization or decomposition temperature for efficient atomization into the catalyst inside the FCC riser, and to provide guidance when passing through even relatively long feed nozzles (such as those up to 2 and 6 feet in length) simultaneously with hot steam or other atomizing gases.

[0007] Another objective is to provide spray nozzle assemblies of the aforementioned type that meet all the requirements for maintaining the integrity of bio-oil, and are relatively simple in structure and conducive to economical manufacturing. Attached Figure Description

[0008] Other objects and advantages of the invention will become apparent from the following detailed description and from the accompanying drawings, in which: Figure 1 A schematic depiction of an illustrative fluidized catalytic cracking system, operable to simultaneously inject both crude oil feed and bio-oil feed into the catalytic cracking riser; Figure 2 For the purpose of describing the biofeed nozzle assembly according to the present invention, the biofeed nozzle assembly is installed inside the riser wall of the catalytic cracking riser; Figure 3 This is an enlarged longitudinal section of the bio-oil feed spray nozzle assembly of the present invention; and Figure 4 An enlarged cross-section of the spray tip for an alternative form of the bio-oil feed spray nozzle assembly shown, the alternative form of the spray tip having a cooling channel for cooling the discharged liquid bio-oil.

[0009] While the invention allows for various modifications and alternative structures, an illustrative embodiment has been shown in the accompanying drawings and will be described in detail below. However, it should be understood that the invention is not intended to be limited to the specific forms disclosed, but rather, it is intended to cover all modifications, alternative structures, and equivalents falling within the spirit and scope of the invention. Detailed Implementation

[0010] Now refer more specifically to the attached diagram. Figure 1The illustration shows a fluid catalytic cracking system 10 capable of operating to atomize both crude oil and bio-oil and direct them into a riser 11 of a catalytic cracking reactor 12. As is known in the art, system 10 includes a reactor 12 and a regeneration unit 14. In such systems, catalyst particles contact liquid hydrocarbons (such as crude oil) that are atomized and directed by a liquid hydrocarbon feed nozzle 15 into the inlet of riser 11. The crude oil feed nozzle 15 can be of a conventional type, such as that depicted in U.S. Patents 5,921,472 and 8,820,663, assigned to the same assignee as this application, the disclosure of which is incorporated herein by reference. Thorough atomization of the hydrocarbon feed is crucial for contacting the hydrocarbon feed with the catalyst particles, as a uniform and narrow distribution of droplet size facilitates faster evaporation of the hydrocarbons, thereby reducing unwanted coke formation and enabling more efficient product yields. Steam is typically used as the atomizing gas, and hot catalyst particles from regeneration unit 14 cause the feed oil to evaporate upon contact in riser 11, thus initiating cracking as oil evaporate. The steam and catalyst particles move upwards in riser 11. During this upward movement, the temperature of the catalyst particles decreases as the oil evaporates and the endothermic cracking reaction proceeds. The cracking reaction causes coke to deposit on the catalyst, leading to catalyst deactivation. The catalyst is separated from the evaporate mixture at the top of the riser located inside reactor 12, which contains a mixture of steam and hydrocarbons from the catalyst stripping tower and is sent to a fractionator. The separated coking catalyst is stripped using steam in the catalyst stripping tower before being sent to regeneration unit 14 to burn off the coke with air. The heat released from the combustion of the coke deposit raises the temperature of the catalyst particles returning to the riser to supply the heat required for the cracking reaction, and this cycle is repeated.

[0011] As indicated above, renewable energy sources, such as bio-oil produced from bio-oil, are becoming increasingly important as alternatives to and supplements to hydrocarbon feedstocks in catalytic processing. Injecting bio-oil through feed nozzles 15, which are designed to inject hydrocarbon feedstocks into FCC units, has been found to be undesirable because bio-oil is prone to decomposition, coking, and clogging, thus hindering efficient atomization of the bio-oil and impeding its guidance into the riser.

[0012] In implementing this embodiment, a bio-oil feed nozzle assembly 20, separate from and distinct from the hydrocarbon feed nozzle 15, is provided for more efficient atomization of the liquid bio-oil feed and its guidance into the riser 11 of the FCC unit, where similar liquid particles are broken down into liquid hydrocarbon feed. The illustrated bio-oil feed nozzle assembly 20 (like the hydrocarbon feed nozzle 15) is conventionally mounted on the partition wall 11 of the riser 11 of the fluidized catalytic reactor 12.a In this case, the bio-oil feed nozzle 20 is supported in a tubular sleeve 21, which is fixed to the wall 11 at an angle relative to the vertical direction. a Inside, for discharging atomized liquid bio-oil upwards into riser 11. The tubular sleeve 21 has an outwardly extending flange 21. a The support flange 20 is fixed to the bio-oil feed nozzle assembly 20. a It can be fixed to the outwardly extending flange 21 a The bio-oil feed nozzle assembly 20 has a liquid bio-oil inlet 22 for connection to the liquid bio-oil supply 24 (in... Figure 2 and Figure 3 (Illustrated in a schematic manner), and an atomizing gas inlet 24 (also shown in the diagram) for connection to an atomizing gas supply 23 (such as steam, fuel gas processed in a refinery, nitrogen, natural gas, etc.). Figure 2 and Figure 3 (Illustrated in a schematic manner). Although the bio-oil feed nozzle assembly 20 shown is positioned upstream of the hydrocarbon feed nozzle 15, alternatively, the bio-oil feed nozzle assembly 20... a It can be set upstream of the hydrocarbon feed.

[0013] In this case, the bio-oil feed nozzle assembly 20 includes a nozzle body 25 in the form of an elongated outer cylindrical body or conduit segment, which substantially extends the length of the feed nozzle assembly 20. Due to the riser wall 11 a Due to the thickness and angled mounting of the feed nozzle assembly 20, the nozzle body 25 typically has a relatively long length, ranging from approximately 2 to 6 feet, depending on the size of the FCC unit. A spray tip 26 (in this case, transversely shaped) with an exhaust orifice 28 is attached to the downstream end of the nozzle body 25 by a weldment 29 in an adjacent relationship.

[0014] The bio-oil feed pipe 30 is centrally supported within the nozzle body 25, which has an upstream end communicating with the liquid bio-oil supply 24. In this configuration, an intermediate pipe or conduit section 31 is concentrically supported surrounding the bio-oil feed pipe 30, wherein the outer surface of the intermediate pipe 31 and the inner surface of the nozzle body 25 define an annular atomizing gas passage 32, which has an upstream end communicating with the atomizing gas supply 23. Similarly, the downstream ends of the bio-oil feed pipe 30 and the intermediate pipe 31 are respectively formed by welded joints 29. a 29 b Fixed to the spray nozzle 26.

[0015] The illustrated bio-oil feed conduit 30 communicates with a central liquid flow passage 35 of the spray tip 26, which extends into a protruding, generally cylindrical liquid guide nose 40 centrally positioned within an enlarged diameter mixing chamber 41 defined within the spray tip 26 in a surrounding relationship with the nose 40. The central liquid flow passage 35 communicates with a plurality of intersecting holes 42 (in this case, four in number), which extend perpendicular to and intersect with the central axis of the spray tip's central liquid flow passage 35. While in this case the illustrated liquid guide nose is an integral part of the spray tip 26, it will be understood that, alternatively, it could be an extension of the bio-oil feed conduit 30.

[0016] Pressurized liquid bio-oil, guided through the central bio-oil supply conduit 30 and passage 35, impacts an end wall 45 at the downstream end of the central passage 35, which is partially defined by a cross orifice 42. As the pressurized liquid bio-oil impacts the end wall 45, it breaks into liquid particles and is radially outwardly guided through the discharge orifice 42 of the cross orifice 42. a .

[0017] Simultaneously, the pressurized atomized gas is guided laterally across the corresponding radial discharge orifice 42a through the annular atomized gas passage 32 into the mixing zone 41 of the spray tip 26, thereby further breaking up and atomizing the laterally guided bio-oil stream. The atomized bio-oil particles, internally atomized within the spray tip 26, are then guided at high speed into the downstream expansion chamber 48 of the spray tip 26 for further breaking up and atomizing as they are discharged through the spray tip discharge orifice 28. In this case, the expansion chamber 48 is slightly smaller in diameter than the upstream mixing zone 41 and has a relatively short axis smaller than its diameter.

[0018] Consistent with an important aspect of this embodiment, the bio-oil feed nozzle assembly 20 is designed to shield the flow of liquid bio-oil within the feed nozzle assembly from overheating due to the temperature of the simultaneously guided atomizing gas and the ambient temperature of the catalytic cracking system. To this end, an insulating layer is disposed between the bio-oil feed conduit 30 and the annular atomizing gas passage 32 to isolate the liquid bio-oil guided through the feed conduit 30 from high-temperature exposure. In the illustrated embodiment, the central bio-oil feed conduit 30 and the intermediate conduit 31 define an annular space 50 between them to hold the insulating material 51 substantially along the length of the bio-oil feed conduit 30, which shields the passing liquid bio-oil from the heat of the system's surroundings. The insulating material 51 is preferably a microporous insulating material, which allows for the very low thermal conductivity of the high-temperature vapor or other atomizing gas guided through the annular atomizing gas passage 32, which surrounds the liquid bio-oil feed conduit 30 along a relatively long nozzle body 25. The separator material is preferably a granular microporous powder, which can vary in size between approximately 0.3 and 2.25 mm. Such microporous materials have been found to be effective in preventing significant heat transfer across the bio-oil feed line 30, even in the relatively small radial space of the cavity 51 between the bio-oil feed line 30 and the intermediate line 31. This temperature control of the bio-oil occurs substantially along its entire path through the bio-oil feed line 30 before being guided to the spray end mixing chamber 41. Due to the effective shielding of the liquid bio-oil from the high temperatures in the surrounding annular atomizing gas passage 32, it has been unexpectedly found that the liquid bio-oil can be maintained in an optimal temperature range of approximately 40°C to 70°C after entering the mixing chamber 41 for the atomization and guidance of the liquid bio-oil from the feed nozzle assembly 20, wherein the droplet size distribution is consistent with the droplet size distribution of the crude oil discharged from the hydrocarbon spray nozzle.

[0019] As an alternative, such as in Figure 4 As depicted, the spray tip 26 may have a plurality of longitudinally extending cooling channels 52 formed around its periphery, the cooling channels 52 communicating with the atomizing gas passage 23 to guide the atomizing gas around the periphery of the spray tip to further reduce the tip temperature. Other forms of spray tips may also be used.

[0020] As seen above, a catalytic cracking system is provided, which is suitable for more efficient and effective atomization and use of bio-oil in the catalytic cracking unit. During its passage through the feed nozzle assembly, the liquid bio-oil is effectively shielded from the high-temperature atomizing gases for optimal atomization and optimal emissions from the feed nozzle to the riser of the FCC unit, consistent with the atomization and guidance of the feed from the hydrocarbon feed nozzle.

Claims

1. A catalytic cracking system, comprising: Catalytic cracking reactor; A riser connects upwards to the catalytic cracking reactor, into which catalyst particles are guided; Liquid hydrocarbon supply; A first feed spray nozzle assembly is mounted in and extends through the wall of the riser and has a first spray tip at its downstream end. The first feed spray nozzle assembly has an upstream end connected to the liquid hydrocarbon supply and the atomizing gas supply, such that liquid hydrocarbons guided through the first feed spray nozzle assembly are atomized by the atomizing gas at the downstream end and discharged as a finely atomized liquid hydrocarbon spray from the first spray tip into the riser to contact the catalyst particles guided to the catalytic cracking reactor. The second feed spray nozzle assembly includes an elongated nozzle body having a length between 2 and 6 feet, the elongated nozzle body being mounted in and extending through the wall of the catalytic cracking riser, and having a second spray tip at a downstream end. Liquid bio-oil supply; A bio-oil feed pipe is supported within the elongated nozzle body, the elongated nozzle body having an upstream end connected to the liquid bio-oil supply for guiding the liquid bio-oil through the bio-oil feed pipe to the second spray end. An intermediate tubular component is concentrically supported between the elongated nozzle body of the second feed spray nozzle assembly and the bio-oil feed pipe; The inner surface of the elongated nozzle body of the second feed spray nozzle assembly and the outer surface of the intermediate tubular component define an annular atomizing gas passage. The annular atomizing gas passage is connected to the atomizing gas supply for guiding the gas through the annular atomizing gas passage to atomize the liquid bio-oil discharged from the liquid feed pipe and the spray tip into a fine-particle liquid bio-oil spray; and A microporous granular powder insulating material is inserted into and completely fills the annular space between the inner surface of the intermediate tubular component and the outer surface of the bio-oil feed pipe without any voids therebetween. This serves to isolate the liquid bio-oil guided through the bio-oil feed pipe from exposure to the high temperature of the atomizing gas guided through the atomizing gas passage for most of the length of the bio-oil feed pipe. This maintains the temperature of the liquid bio-oil passing through the bio-oil feed pipe within a temperature range of 40°C to 70°C, preventing premature polymerization of the liquid bio-oil and nozzle clogging, and promoting atomization of the liquid bio-oil. The droplet size distribution is consistent with the droplet size distribution of the liquid hydrocarbons discharged from the first feed spray nozzle assembly, so that the liquid bio-oil can effectively contact the catalyst in the riser.

2. The catalytic cracking system according to claim 1, characterized in that, The separator layer comprises granular microporous powder having a particle size between 0.3 and 2.25 mm.

3. The catalytic cracking system according to claim 1, characterized in that, The second spray tip defines an internal mixing chamber, in which a bio-oil liquid guide nose is disposed and communicates with the bio-oil feed pipe. The liquid guide nose forms multiple radial discharge channels for guiding the bio-oil that is guided through the bio-oil feed pipe laterally outward in the radial direction into the mixing chamber, so as to break it up and atomize it by the atomizing gas guided from the atomizing gas channel into the mixing chamber.

4. The catalytic cracking system according to claim 3, characterized in that, The radial discharge passage defines an end wall within the liquid guide nose section, where pressurized liquid bio-oil impacting the end wall breaks into liquid droplets and is guided radially outward into the mixing chamber.

5. The catalytic cracking system according to claim 4, characterized in that, The second spray tip includes an expansion chamber downstream of the mixing chamber, into which liquid bio-oil is guided for further atomization and dispersal as it is discharged from the discharge orifice of the spray tip.

6. The catalytic cracking system according to claim 1, characterized in that, The second spray tip has a longitudinally extending cooling channel formed around its periphery. The longitudinally extending cooling channel is connected to the atomizing gas supply to guide the atomizing gas around the spray tip to cool the spray tip from radiation by the heated catalyst.

7. The catalytic cracking system according to claim 1, characterized in that, The atomizing gas supply connected to the atomizing gas passage of the second feed spray nozzle assembly is a steam supply.

8. The catalytic cracking system according to claim 1, characterized in that, The atomizing gas supply connected to the atomizing gas passage of the second feed spray nozzle assembly is pressurized fuel gas, nitrogen, or natural gas.

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