Bubbling column reactor

Abstract

The present invention provides a bubble column reactor comprising a reaction zone in which a gaseous reactant is reacted in a liquid reaction medium, a separation zone arranged above the reaction zone and into which a first gas stream rising from the reaction zone is introduced, and a condensation zone arranged above the separation zone and into which a second gas stream rising from the separation zone is introduced, wherein the diameter of the condensation zone is greater than the diameter of the separation zone.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0177025, filed on December 10, 2021, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0004] This invention relates to a bubble column reactor, and more specifically, to a bubble column reactor for reducing the amount of solids and liquids entrained inside the reactor during oligomer production, thereby improving the stability of the entire process. Background Technology

[0005] Alpha-olefins are widely used commercially as important materials in comonomers, detergents, lubricants, and plasticizers. In particular, 1-hexene and 1-octene have been widely used as comonomers to control the density of polyethylene in the production of linear low-density polyethylene (LLDPE).

[0006] α-olefins are typically prepared by the oligomerization of ethylene. As a type of reactor in which the oligomerization of ethylene takes place, a bubble column reactor has been used to carry out the oligomerization (trimerization or tetramerization) of ethylene by contacting gaseous ethylene as a reactant with a reaction zone containing a liquid reaction medium containing a catalyst.

[0007] In the case of a bubble column reactor, the gaseous reactants are mixed with the liquid reaction medium in the reaction zone to exist as a two-phase reaction. As a result of the catalytic reaction, a small amount of polymer is produced as a byproduct, floating in the liquid reaction medium. At this time, due to the high rate at which a large amount of gaseous reactants are introduced into the reaction zone in the form of a large number of bubbles, solid polymer and liquid reaction medium are inevitably entrained.

[0008] Due to this entrainment, byproduct polymers accumulate not only on the inner walls of the reactor but also on downstream process units (such as condensers, pipes, and valves), causing scaling. Therefore, scaling in downstream process units can lead to equipment degradation and mechanical damage, and in the worst case, may require shutting down the entire process, resulting in increased costs associated with scrubbing and reduced productivity due to decreased operating time.

[0009] Therefore, to solve the above problems, it is necessary to study how to reduce the entrainment of polymer-containing solids and liquids in the bubble column reactor. Summary of the Invention

[0010] [Technical Issues]

[0011] In order to solve the problems mentioned in the background art, the object of the present invention is to provide a bubble column reactor for preventing the entrainment of by-products, including polymer materials, in addition to the desired product in the reactor, thereby improving the stability of the entire process.

[0012] [Technical Solution]

[0013] In one general aspect, the bubble column reactor includes: a reaction zone in which gaseous reactants react in a liquid reaction medium; a separation zone disposed above the reaction zone, wherein a first gas stream rising from the reaction zone is introduced therein; and a condensation zone disposed above the separation zone, wherein a second gas stream rising from the separation zone is introduced therein, wherein the diameter of the condensation zone is larger than the diameter of the separation zone.

[0014] [Beneficial Effects]

[0015] According to the bubble column reactor of the present invention, since a condensation zone is provided above the reaction zone of the bubble column reactor, it is possible to prevent the condenser itself from scaling due to entrainment, compared with the case where a separate condenser is provided outside the bubble column reactor of the related art.

[0016] Meanwhile, by making the diameter of the condensation zone of the bubble column reactor larger than the diameter of the separation zone located between the reaction zone and the condensation zone, the gas rising rate in the condensation zone can be reduced to improve the non-vapor precipitation effect. Furthermore, the gas path is altered by the eddies generated in the condensation zone, which has a relatively larger diameter than the separation zone, thereby achieving uniform mixing and ultimately uniform condensation in the condensation zone.

[0017] Meanwhile, by setting cooling coils in the condensation zone, a uniform temperature distribution can be achieved in the condensation zone, thereby effectively condensing and refluxing the solvent and polymer in the gas flow back to the reaction zone.

[0018] Correspondingly, the stability of the entire process can be improved by reducing the amount of entrained non-vapor solids and liquids, the reactor downtime can be effectively increased by fundamentally preventing fouling in downstream process units, and energy costs can be reduced by preventing efficiency reductions due to fouling in downstream process units. Attached Figure Description

[0019] Figure 1 and Figure 2 This is a view illustrating the bubble column reactor and related process flow according to an embodiment of the present invention.

[0020] Figure 3 and Figure 4 It shows a view of the bubble column reactor of the relevant technology and a process flow diagram based on the relevant technology. Detailed Implementation

[0021] The terms and words used in the specification and claims of this invention should not be interpreted as having a general or dictionary meaning, but rather should be interpreted as having a meaning and concept consistent with the technical idea of ​​this invention, based on the principle that the inventors can appropriately define the concepts of the terms in order to best describe their own invention.

[0022] In this invention, the term "flow" can refer to the flow of fluid in a process, or to the fluid itself flowing through a delivery pipeline (pipeline). Specifically, "flow" can refer to both the fluid itself flowing through pipes connecting various devices and the flow of fluid. Furthermore, fluid can refer to one or more of gas, liquid, and solid.

[0023] In this invention, the term "C#" where "#" is a positive integer refers to all hydrocarbons having # carbon atoms. Therefore, the term "C10" refers to a hydrocarbon compound having 10 carbon atoms. Furthermore, the term "C#+" refers to all hydrocarbon molecules having # or more carbon atoms. Therefore, the term "C10+" refers to a mixture of hydrocarbons having 10 or more carbon atoms.

[0024] In the following text, reference will be made to Figure 1 The invention will be described in more detail to aid in understanding it.

[0025] A bubble column reactor 100 according to an embodiment of the present invention may include a reaction zone in which gaseous reactants react in a liquid reaction medium; a separation zone disposed above the reaction zone and into which a first gas flow rising from the reaction zone is introduced; and a condensation zone disposed above the separation zone and into which a second gas flow rising from the separation zone is introduced, wherein the diameter of the condensation zone is larger than the diameter of the separation zone.

[0026] According to one embodiment of the present invention, the bubble column reactor 100 can be used to prepare oligomer products by carrying out an oligomerization reaction of gaseous reactants including monomers in a liquid reaction medium of solvent and catalyst.

[0027] More specifically, the bubble column reactor 100 may include a reaction zone 300, and a reaction medium may be supplied to the reaction zone 300 via one or more reaction medium supply lines 310 connected to one side of the reaction zone 300. Here, the reaction medium may include a catalyst, a co-catalyst, and a solvent. The catalyst, co-catalyst, and solvent may be supplied separately via individual reaction medium supply lines 310, and two or more reaction medium components may be mixed and supplied to the reaction zone 300 via reaction medium supply lines 310.

[0028] According to one embodiment of the invention, the monomer may include ethylene monomer. As a specific example, a gaseous reactant including ethylene monomer may be supplied to the lower chamber 200 of a bubble column reactor 100, described later, to produce the desired α-olefin product by oligomerization.

[0029] Solvents may include one or more selected from n-pentane, n-hexane, n-heptane, cyclohexane, methylcyclohexane, octane, cyclooctane, decane, dodecane, benzene, xylene, 1,3,5-trimethylbenzene, toluene, ethylbenzene, chlorobenzene, dichlorobenzene, and trichlorobenzene.

[0030] The catalyst may include a transition metal source. The transition metal source may be one or more compounds selected from, for example, chromium acetylacetonate (III), chromium tetrahydrofuran chloride (III), chromium 2-ethylhexanoate (III), chromium tri(2,2,6,6-tetramethyl-3,5-heptadecanoate (III), chromium benzoylacetone (III), chromium hexafluoro-2,4-pentanedione (III), chromium acetate (III) hydroxide, chromium acetate (III), chromium butyrate (III), chromium valerate (III), chromium laurate (III), and chromium stearate (III).

[0031] The cocatalyst may include one or more selected from, for example, trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, ethyl sesquichloride, diethylaluminum chloride, ethyl dialuminum chloride, methylaluminoxane, modified methylaluminoxane, and borate.

[0032] Meanwhile, in the reaction zone 300 of the bubble column reactor 100, the oligomerization reaction of the monomer can be carried out in a liquid reaction medium including a catalyst, a co-catalyst, and a solvent. As described above, the region consisting of the reaction medium in which the monomer oligomerization reaction takes place can be defined as the reaction zone 300. Oligomerization reaction can refer to the reaction in which monomers are oligomerized. Depending on the number of monomers to be polymerized, oligomerization reactions can also be called trimerization and tetramerization, which are collectively referred to as polymerization.

[0033] Alpha-olefins are widely used commercially as important materials in comonomers, detergents, lubricants, plasticizers, and more. In particular, 1-hexene and 1-octene are commonly used as comonomers to control the density of polyethylene in the production of linear low-density polyethylene (LLDPE). Alpha-olefins, such as 1-hexene and 1-octene, can be prepared by trimerizing or tetramerizing, for example, ethylene.

[0034] The bubble column reactor 100 may include a product discharge line 320 connected to the reaction zone 300 and disposed on the other side of the reaction medium supply line 310, through which products including the oligomerization product α-olefin may be discharged. That is, the product discharge line 320 may include oligomer products and solvents generated by the oligomerization reaction, and the oligomer products and solvents may be separated by a separate separation device. The separated solvent may be reused in the oligomer production process. Furthermore, for example, when ethylene monomer is used as the monomer for the oligomerization reaction, the oligomer products may include 1-hexene and 1-octene. The supply of the reaction medium to the reaction zone 300 and the discharge of products from the reaction zone 300 can be continuous.

[0035] Meanwhile, gaseous reactants containing monomers for oligomerization can be supplied through gaseous reactant supply line 210 to the lower chamber 200 located at the bottom of the bubble column reactor 100, and then supplied through dispersion plate 350 to the reaction zone 300 containing liquid reaction medium.

[0036] In other words, the dispersion plate 350 can be disposed between the lower chamber 200 and the reaction zone 300. Gaseous reactants, such as gaseous monomers, can be uniformly distributed and supplied from the lower chamber 200 through holes formed at equal intervals along the center and circumference of the dispersion plate 350 to the reaction zone 300, which includes the reaction medium.

[0037] Gaseous reactants flow into the reaction zone 300 containing the liquid reaction medium through the dispersion plate 350 and are simultaneously dispersed. Turbulence is generated by the force of the dispersed gas, causing the liquid reaction medium and gaseous reactants to mix naturally. At this time, the dispersion force of the gaseous reactants flowing into the reaction zone 300 through the dispersion plate 350 remains greater than the head pressure acting downwards from the liquid reaction medium, allowing the liquid reaction medium to remain in the reaction zone 300.

[0038] Meanwhile, as described above, the gaseous reactants supplied to the reaction zone 300 of the bubble column reactor 100 can be catalyzed in a liquid reaction medium containing a solvent and a catalyst, and specifically, the catalytic reaction can be an oligomerization reaction. In this case, the gaseous reactants and the reaction medium in the reaction zone 300 are mixed together, thus existing as two phases. Simultaneously, in the reaction zone 300, a small amount of polymer may be generated as a byproduct due to the catalytic reaction of the gaseous reactants floating in the liquid reaction medium. At the same time, a large amount of gaseous reactants is introduced into the reaction zone 300, and unreacted gaseous reactants rise as gas through the reaction medium. Entrainment of solid polymers and the liquid reaction medium may occur due to the flow rate and velocity of the rising gaseous reactants. That is, when unreacted gaseous reactants move upward through the reaction zone 300, not only the unreacted gaseous reactants but also the polymers as byproducts and partially evaporated solvent move upward together. In this case, the entrained polymers deposit in the downstream process unit of the bubble column reactor 100 due to polymer adhesion, thereby causing scaling that hinders fluid flow.

[0039] Therefore, the bubble column reactor 100 according to an embodiment of the present invention may include a separation zone DS and a condensation zone CZ disposed above the reaction zone 300, thereby preventing the entrainment of byproducts containing polymers, thereby preventing scaling in downstream process units and improving the stability of the entire process.

[0040] More specifically, a first gas flow from reaction zone 300 can be introduced into separation zone DS. In addition to unreacted gaseous reactants, the first gas flow may include vaporized solvent and entrained polymer as part of the mixed gas. The first gas flow, including unreacted gaseous reactants and the mixed gas, can have its upward velocity reduced by passing through separation zone DS, allowing a portion of the entrained polymer and solvent, particularly a portion of the polymer non-vaporized material (i.e., heavier solids), to preferentially precipitate into reaction zone 300.

[0041] Meanwhile, the height H1 of the separation zone DS, i.e., the length from the upper surface of the reaction zone 300 to the upper surface of the separation zone DS, can be 10% to 40% of the total length of the bubble column reactor 100. When the height H1 of the separation zone DS is 10% or more of the total length of the bubble column reactor 100, sufficient time and space can be provided for the precipitation of polymers and solvents entrained in the first gas flow. When the height H1 of the separation zone DS is less than 40%, in addition to the effective precipitation effect of the separation zone DS, the space occupied by the bubble column reactor 100 can also be minimized.

[0042] Subsequently, the airflow rising from the separation zone DS can then be introduced as a second airflow into the condensation zone CZ located above the separation zone DS.

[0043] The condensation zone CZ is a space where the internal temperature is maintained below that of the separation zone DS. When the second gas stream passes through the condensation zone CZ, the solvent and entrained polymer that evaporate in the second gas stream may be condensed and precipitated. In particular, the evaporated solvent can be liquefied by condensation, and the liquefied solvent can precipitate and flow back to the reaction zone 300.

[0044] Meanwhile, a bubble column reactor of the relevant technology is shown in reference. Figure 3 The bubble column reactor comprises, in sequence, a lower chamber, a reaction zone, and a separation zone, but does not include a condensation zone as described in this invention. That is, unreacted vapors discharged to the upper part of the bubble column reactor are condensed by an external heat exchanger, and then the condensed components (such as solvents and unreacted gaseous reactants) are separated by a separation device (such as a flash tank). In this case, entrained polymer components may be discharged unas-is to the upper part of the bubble column reactor, and polymer components may deposit in the heat exchanger, flash tank, and the pipes connecting them, resulting in frequent scaling.

[0045] In other words, compared to the case where a separate condenser is installed outside the bubble column reactor, according to the embodiment of the present invention, since a condensation zone CZ is provided inside the bubble column reactor 100, the effect of rapid condensation and precipitation of the mixed gas can be achieved even without separate facilities such as pipes. Furthermore, it can fundamentally solve the scaling problem caused by entrained polymers in the pipes between the bubble column reactor and the external condenser, or the scaling problem of the condenser itself.

[0046] Meanwhile, the bubble column reactor 100 can be a cylinder with a circular cross-section, and the cross-sections of the reaction zone 300, the condensation zone CZ, and the separation zone DS can also be circular. The diameter of the separation zone DS can be the same as the diameter of the reaction zone 300, and the diameter of the condensation zone CZ can be larger than the diameter of the separation zone DS. Here, the diameter of the condensation zone CZ specifically refers to the cross-sectional diameter of the condensation zone CZ, and the diameter of the separation zone DS specifically refers to the cross-sectional diameter of the separation zone DS.

[0047] When the diameter of the condensing zone CZ is larger than the diameter of the separation zone DS, the path of the second gas flow through the separation zone DS, which has a relatively narrow cross-sectional area, changes at the inlet of the condensing zone CZ, thereby generating a vortex. Due to this vortex, the second gas flow can mix at the inlet of the condensing zone CZ and can be uniformly distributed and rise. Furthermore, as the diameter of the condensing zone CZ increases, the rising velocity of the second gas flow can be reduced, resulting in excellent condensation of the evaporated solvent and precipitation of the entrained polymer. With the uniformly mixed second gas flow passing through the condensing zone CZ at a reduced rate, the condensation efficiency of the condensing zone CZ can be further improved.

[0048] Specifically, the diameter of the condensation zone CZ can be 1.3 to 3 times the diameter of the separation zone DS, and more specifically, it can be 1.5 to 2 times the diameter of the separation zone DS. When the diameter ratio is 1.3 times or greater, excellent non-vapor precipitation effect can be achieved through the uniform mixing of the second airflow and the reduction of the upward velocity. At the same time, when the ratio is 3 times or less, the minimum upward pressure of the second airflow through the condensation zone CZ can be maintained.

[0049] Meanwhile, the condensing zone CZ may include a cooling coil, which may be wound up from top to bottom within the condensing zone CZ. The cooling coil is in the form of a pipe through which refrigerant can flow, and the cooling coil may include a cooling coil inlet and a cooling coil outlet. Refrigerant can be introduced into the upper cooling coil of the condensing zone CZ through the cooling coil inlet, and refrigerant can be discharged into the lower cooling coil of the condensing zone CZ through the cooling coil outlet.

[0050] Meanwhile, the temperature of the refrigerant supplied from the upper part of the condensing zone CZ of the present invention can be in the range of -10°C to -5°C, and the temperature of the refrigerant discharged from the lower part of the condensing zone CZ can be in the range of 0°C to 5°C.

[0051] Considering the oligomerization reaction temperature in reaction zone 300, the temperature of the refrigerant supplied to condenser zone CZ needs to be at least below -5°C to condense the gas flow. Additionally, depending on the available reaction temperature range and energy-saving requirements, the supplied refrigerant temperature needs to be -10°C or higher.

[0052] Meanwhile, in order to reduce the temperature of the gaseous outflow stream 550 from the predetermined oligomerization reaction temperature, the difference between the refrigerant supply temperature and the temperature of the discharged refrigerant is preferably about 10°C, and in this respect, the temperature of the discharged refrigerant can be in the range of 0°C to 5°C.

[0053] Since the diameter of the condensation zone CZ is relatively large, it is important to maintain a suitable cooling temperature within the condensation zone CZ. Therefore, the cooling coil may include a first cooling coil 500 and a second cooling coil 600, wherein the first and second cooling coils may be arranged meanderingly from top to bottom within the condensation zone CZ.

[0054] Reference Figure 1 According to an embodiment of the present invention, the first cooling coil 500 and the second cooling coil 600 can be connected in parallel in the condensation zone CZ, and the lower end of the first cooling coil 500 can extend upward to connect to the upper end of the second cooling coil 600.

[0055] Specifically, the inlet 510 for introducing refrigerant into the first cooling coil 500 can be located at the upper part of the first cooling coil 500. The refrigerant introduced into the inlet 510 of the first cooling coil 500 can exchange heat with the second gas flow while moving downwards along the interior of the coiled first cooling coil 500. The refrigerant that has moved to the lower part of the first cooling coil 500 can be reintroduced into the upper part of the second cooling coil 600. Then, the refrigerant can exchange heat with the second gas flow while moving along the interior of the coiled second cooling coil 600. The refrigerant can be discharged to the outside of the reactor through the outlet 520 of the second cooling coil 600 located at the lower part of the second cooling coil 600.

[0056] Thus, the bubble column reactor 100 of the present invention includes first and second cooling coils in the condensation zone CZ, ensuring sufficient heat exchange area between the cooling coils and the second airflow even if the diameter of the condensation zone CZ is larger than the diameter of the separation zone DS, thereby achieving a uniform cooling temperature distribution in the condensation zone CZ. Furthermore, since the refrigerant supplied to the first cooling coil 500 can be used as the refrigerant for the second cooling coil 600, energy-saving effects can be achieved.

[0057] Furthermore, when a portion of the entrained polymer and evaporated solvent with relatively high specific gravity in the first gas flow undergoes natural precipitation, and the remaining polymer and evaporated solvent rise in the separation zone DS, the rising velocity decreases and the direction of motion is altered by the vortex due to the increased diameter of the condensation zone CZ. Therefore, uniform mixing and thus uniform condensation occur in the condensation zone CZ, while reducing the non-contact zone (dead zone), thereby preventing the polymer and evaporated solvent from failing to precipitate or from passing through the condensation zone CZ despite condensation.

[0058] At the same time, refer to Figure 4 When the condensation zone CZ of a bubble column reactor includes a row of cooling coils, condensation can occur around the cooling coils, but relatively less condensation occurs away from the cooling coils, leading to an increase in the non-contact zone (dead zone). In this single-row cooling coil configuration of the related art, the effective condensation efficiency of the evaporated solvent contained in the second gas flow and the precipitation efficiency of non-vaporized material in the condensation zone CZ with its increased diameter decreases. Therefore, when the diameter of the condensation zone CZ increases relatively, it becomes difficult to maintain a suitable cooling temperature within the condensation zone CZ.

[0059] According to another embodiment of the invention, the first cooling coil 500 and the second cooling coil 600 can be separated from each other and spaced apart. Specifically, see... Figure 2Refrigerant can be introduced into corresponding inlets 510 and 610 located at the upper ends of the first cooling coil 500 and the second cooling coil 600, and can exchange heat with the second airflow while moving downwards along the interior of the first and second cooling coils 500 and 600, which are wound in a coil form. Subsequently, the refrigerant can be discharged to corresponding outlets 520 and 620 located at the lower ends of the first cooling coil 500 and the second cooling coil 600. In this configuration, the radial temperature deviation of the condensation zone CZ can be minimized, and the internal temperature of the condensation zone CZ can be controlled more uniformly.

[0060] Meanwhile, the ratio (H2 / H1) of the height H2 of the condensation zone to the height H1 of the separation zone can be between 1.2 and 2.0. When the height ratio is within this range, excellent non-vapor precipitation effect can be obtained because sufficient time and space are provided in the separation zone DS for the polymer and solvent entrained in the first gas stream to precipitate. In this way, due to the excellent non-vapor precipitation effect in the condensation zone CZ, the height of the separation zone DS can be reduced, thereby minimizing the space occupied by the bubble column reactor 100.

[0061] Therefore, in one embodiment of the invention, non-vaporous components (e.g., evaporated solvent and polymer in the second gas stream) in the condensation zone CZ can be condensed and precipitated, and the gaseous effluent 550, including unreacted monomers (e.g., gaseous ethylene), can be discharged to the top of the bubble column reactor 100. In this case, the gaseous effluent 550 can be discharged with most of the mixed gas (evaporated solvent and entrained polymer) contained in the first effluent removed.

[0062] The bubble column reactor according to the present invention has been described above and illustrated in the accompanying drawings. However, the description and illustrations are only for understanding the essential components of the invention. Processes and apparatus not separately described and illustrated in the specification and drawings may be suitably applied and used to implement the bubble column reactor according to the present invention.

Claims

1. A bubble column reactor, comprising: The reaction zone, in which gaseous reactants react in a liquid reaction medium; A separation zone is provided above the reaction zone, and a first gas flow rising from the reaction zone is introduced therein; and A condensation zone is located above the separation zone, and a second airflow rising from the separation zone is introduced therein. The diameter of the condensation zone is larger than the diameter of the separation zone. The height (H1) of the separation zone is 10% to 40% of the total length of the bubble column reactor. The ratio (H2 / H1) of the height of the condensation zone (H2) to the height of the separation zone (H1) is 1.2 to 2.

0.

2. The bubble column reactor according to claim 1, in, The diameter of the condensation zone is 1.3 to 3 times the diameter of the separation zone.

3. The bubble column reactor according to claim 1, in, The diameter of the condensation zone is 1.5 to 2 times the diameter of the separation zone.

4. The bubble column reactor according to claim 1, in, The condensation zone includes cooling coils. The cooling coil is arranged in a wound manner from top to bottom within the condensation zone.

5. The bubble column reactor according to claim 4, in, The cooling coil includes a first cooling coil and a second cooling coil. The first cooling coil and the second cooling coil are respectively arranged in a wound manner from top to bottom in the condensation zone.

6. The bubble column reactor according to claim 5, in, The first cooling coil and the second cooling coil are connected in parallel with each other, and The lower end of the first cooling coil extends upward and connects to the upper end of the second cooling coil.

7. The bubble column reactor according to claim 6, in, The first cooling coil includes an inlet located at the upper end of the first cooling coil, and The temperature of the refrigerant introduced into the inlet of the first cooling coil is -10°C to -5°C.

8. The bubble column reactor according to claim 5, in, The first cooling coil and the second cooling coil are separated from each other, and The refrigerant is introduced into the corresponding inlets located at the upper ends of the first and second cooling coils, and discharged through the corresponding outlets located at the lower ends of the first and second cooling coils.

9. The bubble column reactor according to claim 1, in, The gaseous reactants include ethylene monomer.

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