Screening components and methods for screening polymers from effluent streams with reduced polymer entrainment levels.

Abstract

The present invention relates to a screening assembly comprising a separation device connected to a conduit for an effluent stream comprising a mixture of polymers and hydrocarbons, wherein the separation device is configured to separate the effluent stream into a polymer-rich stream and a polymer-lean vapor stream, wherein the first separation device comprises: an inlet; a first outlet for extracting the polymer-rich stream and a second outlet for extracting the polymer-lean vapor stream; a screening device connected to the separation device via a conduit for the polymer-lean vapor stream, wherein the screening device comprises a first inlet connected to the conduit for the polymer-lean vapor stream, a first outlet for extracting a clean vapor stream, a second outlet for extracting a polymer-containing condensate vapor stream, and at least one second inlet for introducing the condensate vapor stream.

Description

Technical Field

[0001] This invention relates to a screening assembly for screening polymers from an effluent stream. Furthermore, the invention also relates to a method for screening polymers from said effluent stream. In particular, the screening assembly and method can be used in solution polymerization processes. Background Technology

[0002] Typically, in solution polymerization processes, the polymer concentration in the reactor is relatively low during reactor operation. Accordingly, a low polymer concentration is generally considered to be less than 30 wt% relative to the total amount of polymer, solvent, monomer, and optional comonomer used.

[0003] Furthermore, in solution polymerization processes, reactors are typically operated at higher temperatures than in gas-phase polymerization. The advantage of higher temperatures is higher catalyst activity, resulting in better catalytic efficiency. However, a disadvantage is that in the case of rapid exothermic reactions, too much heat is absorbed into the reaction mixture, leading to the risk of runaway reaction. To control this rapid exothermic reaction and potential for uncontrolled reaction, the polymer concentration is typically between 15 wt% and 25 wt%, making the generation of exothermic reactions controllable.

[0004] Therefore, the resulting effluent streams contain individual amounts of unwanted hydrocarbons, such as solvents, unreacted monomers, and optional comonomers, which must be removed from the polymer in processing steps following the polymerization reaction step.

[0005] Although solution polymerization processes known in the art vary in these subsequent process steps, almost all processes typically utilize the following steps: a) heating the molten polymer solution under pressure; b) depressurizing the solution to allow volatile compounds to evaporate.

[0006] Typically, this solution polymerization process is carried out under conditions where the reactor pressure is above 50 barg and the reactor outlet temperature is above 150°C. In some solution polymerization techniques known in the art, in a subsequent step, the solution stream is heated to above 200°C, followed by a pressure drop to a vacuum level to produce the final polymer.

[0007] Typically, this separation is carried out in a flash separator, forming a condensate stream and a vapor stream. In a typical reactor assembly or process, this vapor stream from the evaporation step is condensed and sent to a recovery section. For example, this vapor stream can be reused as a solvent and / or as a source of unreacted monomers and / or comonomers.

[0008] In certain applications of polymers, it is necessary to have particularly low volatile content in the polymer, where volatiles can be specifically represented by hydrocarbons, such as solvent molecules and / or unreacted monomers or comonomers remaining in the produced polymer. To achieve such low volatility in polymers, multi-step evaporation processes have been developed. In particular, it is known in the art that at least two or three evaporation processes are required to achieve acceptable low levels of volatility in polymers for certain market applications, which in most cases necessitates the use of additional equipment, such as devolatilization extruders or kneaders, as a final step.

[0009] Typically, in each step of a multi-step process, the vapor stream is subsequently condensed and can be reused as reactor feed for the process or as feed for the recovery section, where hydrocarbons, such as solvents, comonomers, and monomers, are separated beforehand.

[0010] Problems to be solved

[0011] These vapor streams may include polymers that have already been entrained in the vapor stream during the separation steps. Because the pressure drop in the separation steps is typically large, the separation occurs so rapidly that fine polymer particles may be drawn out by the evaporated material and introduced into the vapor stream. It turns out that the level of polymer entrainment is particularly high in the first separation step. This is likely because the amount of evaporated material is the largest in the first separation step.

[0012] Fouling in the equipment following the separation step leads to reduced heat removal and decreased separation efficiency in the process section / equipment. This is particularly problematic for condensers used to condense the vapor stream in subsequent steps. The heat removal efficiency of such condensers can be significantly reduced by fouling, or even completely block the channels. Therefore, fouling in the equipment can even affect temperature control and production capacity of the polymerization process when the vapor stream is reused as reactor feed. Therefore, appropriate protective measures are needed to prevent polymer entrainment and fouling effects in the vapor stream of the gas-phase / condensed-phase separation step following polymerization processes (especially solution polymerization).

[0013] Purpose of the invention

[0014] In view of the above problems, one object of the present invention is to provide a screening assembly, including a screening device, particularly a gas phase / condensed phase screening device, for screening polymers from an effluent stream, preferably drawn from a polymerization reactor, and more ideally from a solution polymerization reactor, having reduced or preferably eliminated polymer entrainment.

[0015] Furthermore, also in view of the above-mentioned problems, a second object of the present invention is to provide a processing method for screening polymers from the effluent stream of a polymerization process (especially a solution polymerization process), thereby reducing or eliminating polymer entrainment. Summary of the Invention

[0016] It has now been surprisingly discovered that the above objective can be achieved by combining the separation step with at least one sieving step, wherein the vapor phase of the separation step is introduced into the sieving step, in which the vapor phase of the separation step comes into contact with the condensed vapor phase.

[0017] Therefore, the present invention relates to a method for screening polymers from an effluent stream comprising a mixture of polymers and hydrocarbons (e.g., at least one solvent, at least one monomer, and optionally at least one comonomer), the method comprising the following steps:

[0018] a) Separate the outflow stream into a polymer-rich stream and a polymer-lean vapor stream;

[0019] b) Contacting a lean polymer vapor stream with a first condensed vapor stream, wherein the flow direction of the first condensed vapor stream is countercurrent to the flow direction of the lean polymer vapor stream, to produce a clean vapor stream and a polymer-containing condensed vapor stream.

[0020] Furthermore, the present invention relates to a screening assembly comprising a separation device connected to a conduit for an effluent stream comprising a mixture of polymer and hydrocarbons (e.g., at least one solvent, at least one monomer, and optionally at least one comonomer), wherein the separation device is configured to separate the effluent stream into a polymer-rich stream and a polymer-lean vapor stream, wherein the separation device includes an inlet, a first outlet for extracting the polymer-rich stream and a second outlet for extracting the polymer-lean vapor stream, and a screening device connected to the separation device via the conduit for the polymer-lean vapor stream, wherein the screening device includes: a first inlet connected to the conduit for the polymer-lean vapor stream, a first outlet for extracting a clean vapor stream, a second outlet for extracting a polymer-containing condensate vapor stream, and at least one second inlet for introducing the condensate vapor stream.

[0021] Finally, the present invention relates to the use of the screening assembly according to the invention for preventing scaling in polymerization processes (preferably solution polymerization processes).

[0022] Definition of noun

[0023] The term "jetting" as used herein must be understood as a step in the method in which a condensed phase is introduced into the gas phase. Consequently, the condensed phase is broken into multiple droplets. This is typically accomplished by at least one nozzle. Jetting must also be understood as a step in the method in which a two-phase system (gas / condensed phase) with the highest possible phase separation surface is formed.

[0024] The term "condensation point" as used herein must be understood as a combination of conditions that cause a compound to condense from a vaporized mixture. Specifically, the condensation point depends on pressure, temperature, and hydrocarbons, such as solvents, monomers and optional comonomers, as well as any other gaseous components of the system. The condensation point can be achieved by changing any one or two of these parameters.

[0025] The volatile substances or volatile compounds used herein must be understood as compounds with significantly lower molecular weights compared to the polymers produced by the methods of this invention. When exposed to a flash separator, such compounds are typically present in a gaseous form. Generally, volatile compounds include at least one unreacted monomer, optionally an unreacted comonomer, a solvent, and any other gaseous components present in the effluent stream.

[0026] Flash separators have been used in the prior art for decades (also as low-pressure separators). As is well known in the art, a liquid feed is passed into a flash vessel operating at low pressure. In this way, a portion of the liquid phase vaporizes and can be extracted from the low-pressure separator as a top stream (or vapor stream). The remaining liquid phase is extracted from the flash vessel as a bottom stream or liquid stream. This describes the operation of the low-pressure separator under conditions where both gas and liquid phases are present in the flash vessel.

[0027] The term "washing column" as used here refers to a container that allows contact between a vapor stream and a liquid stream, with the liquid stream traveling from top to bottom, partially evaporating along the way, and the vapor stream traveling from bottom to top, partially condensing along the way. Particles / droplets present in the vapor stream are washed away by the liquid falling to the bottom. Washing columns typically operate with a reservoir at the bottom that maintains the boiling point to ensure a vapor stream even when the input vapor stream is reduced. Furthermore, a washing column may include distributors for both streams: a liquid distributor and a vapor distributor. A washing column may be a packed bed to reduce entrainment in the vapor stream.

[0028] The term separation efficiency used in this paper is defined as the mass flow of the component extracted from a lean polymer stream or vapor stream under equilibrium conditions divided by the (theoretical) mass flow of the component in the lean polymer stream or condensate stream.

[0029] The term "sieving" as used here refers to the process of removing some or all of the solids from a liquid. Attached Figure Description

[0030] Figure 1 shows a schematic layout of a screening assembly and method according to the most common embodiment of the present invention, wherein a washing column without a gas distributor and a liquid distributor (Figure 1a) and a washing column with a gas distributor and a liquid distributor (Figure 1b) are used as screening devices.

[0031] Figure 2 shows a schematic layout of the screening components and method according to Figure 1, with several modifications made using a condensed vapor stream containing polymer.

[0032] Figure 2a illustrates a modified scheme in which a portion of the polymer-containing condensate vapor stream is circulated as a jet into the lean polymer vapor stream entering the scrubbing column.

[0033] Figure 2b illustrates a modified scheme in which a portion of the polymer-containing condensate vapor stream is recycled as washing liquid in a washing column.

[0034] Figure 2c shows a modified scheme in which a portion of the polymer-containing condensate vapor stream is circulated in a separation unit.

[0035] Figure 2d shows a modification in which a portion of the polymer-containing condensate vapor stream is used to control the temperature of the condensate vapor components in the screening device.

[0036] Figure 3 shows a combination of all the modifications proposed in Figures 2a to 2d.

[0037] Figure 4 shows a schematic layout of the screening assembly and method according to Figure 1, wherein the clean steam stream drawn from the top of the washing column is condensed and reintroduced, which may be done without (Figure 4a) or with the use of a pump and container (Figure 4b).

[0038] Figure 5 shows a combination of the embodiments in Figures 3 and 4.

[0039] Figure Labels

[0040] 1. Polymerization reactor

[0041] 2. Separation device

[0042] 3 Screening device

[0043] 4(3) First entrance

[0044] 5(3) First Exit

[0045] The second exit of 6(3)

[0046] The first second entrance of 7(3)

[0047] The second second entrance of 8(3)

[0048] The third entrance of 9(3)

[0049] 10a First Liquid Distributor

[0050] 10b Second Liquid Dispenser

[0051] 11a First Gas Distributor

[0052] 11b Second Gas Distributor

[0053] 12 First Pump

[0054] 13 Heaters

[0055] 14 Condenser

[0056] 15 Containers

[0057] 16 Second Pump

[0058] 17. Liquid level of condensed vapor composition

[0059] Q1 First condensing vapor source

[0060] Q2 Second condensing vapor source

[0061] Q3 Third Condensation Vapor Source

[0062] Q4 Fourth condensate vapor source

[0063] outflow logistics

[0064] b Polymer-rich flow

[0065] c. Polymer-poor vapor flow

[0066] d Clean steam flow

[0067] e Condensed vapor stream containing polymer

[0068] f First condensed vapor flow

[0069] g Second condensing vapor stream

[0070] h heated condensate vapor stream

[0071] i. Jet condensate vapor stream

[0072] j Circulating condensate vapor flow

[0073] k Clean steam cleaning flow Detailed Implementation

[0074] The invention will now be described in detail with reference to the accompanying drawings and embodiments therein.

[0075] The screening component according to the present invention

[0076] According to the screening component in Figure 1a

[0077] In the most general embodiment of the invention described in FIG1a, a screening component is provided, comprising:

[0078] A separation device (2) is connected to a conduit for an effluent stream (a), the effluent stream (a) comprising a mixture of polymer and hydrocarbons, such as at least one solvent, at least one monomer, and optionally at least one comonomer, wherein the separation device (2) is configured to separate the effluent stream (a) into a polymer-rich stream (b) and a polymer-lean vapor stream (c), wherein the first separation device (2) includes an inlet, a first outlet for extracting the polymer-rich stream (b), and a second outlet for extracting the polymer-lean vapor stream (c).

[0079] A screening device (3) is connected to a separation device (2) via a conduit for a lean polymer vapor stream (c), wherein the screening device (3) comprises:

[0080] The first inlet (4) is connected to the conduit of the lean polymer vapor flow (c).

[0081] The first outlet (5) is used to extract a clean steam stream (d).

[0082] The second outlet (6) is used to extract the condensate vapor stream (e) containing the polymer, and

[0083] At least one second inlet (7, 8) is used to introduce the condensate vapor stream (f, g).

[0084] Preferably, the effluent is drawn from the polymerization reactor (1), and more preferably from the solution polymerization reactor.

[0085] Preferably, the polymer is a polyolefin homogeneous material or copolymer, more preferably a polyethylene or polypropylene homogeneous material or copolymer.

[0086] The screening assembly ensures that the lean polymer vapor stream (c) from the separation device (2) comes into contact with the condensate vapor components introduced via at least one second inlet (7, 8) for introducing the condensate vapor stream (f, g). The advantage of contact between the lean polymer vapor stream (c) and the condensate vapor stream (f, g) is that polymers entrained in the lean polymer vapor stream (c) within the separation device (2) can be effectively removed from the lean polymer vapor stream (c), thereby generating a clean vapor stream (d) that can be extracted from the first outlet (5).

[0087] Preferably, the polymer-rich stream (b) is used to extract the stream containing the final polymer. Further subsequent steps, such as a washing chamber, may be required to achieve a certain quality of polymer.

[0088] Preferably, the condensate stream (e) containing the polymer can be washed. In this case, a subsequent separation step is still required to extract the final polymer from the stream.

[0089] Preferably, a clean vapor stream (d) is used to clean volatile compounds.

[0090] Preferably, the lean polymer vapor stream (c) generated in the separation device (2) is superheated. This is due to the conditions typically used in this separation step. Preferably, the temperature used in the separation device (2) is between 100°C and 400°C, more preferably between 130°C and 300°C, and more preferably between 170°C and 250°C. Furthermore, the pressure drop relative to the pressure in the outflow stream (a) is preferably greater than 30 gauge pressures, more preferably greater than 60 gauge pressures, and most preferably greater than 90 gauge pressures. Therefore, the conditions in the lean polymer vapor stream (c) are set such that the hydrocarbon mixture, i.e., the solvent, unreacted monomers, and / or comonomers, is at a temperature above its condensation point. Therefore, the mixture of compounds in the lean polymer vapor stream (c) is preferably in gaseous form.

[0091] It has now been found that polymer entrained in a polymer-lean vapor stream (c) can be effectively removed by contacting a condensed vapor component comprising a mixture of hydrocarbons (e.g., at least one solvent comprising at least one monomer and optionally at least one comonomer) with the polymer-lean vapor stream (c). Without being bound by theory, we assume that the condensed phase adheres to the polymer particles, making them heavier. Therefore, they sink into the condensed vapor phase. Furthermore, the high temperature of the condensed phase prevents high-concentration polymers from "sticking" to the walls or interior of the equipment.

[0092] In a preferred general embodiment of the invention, the screening device (3) includes at least one liquid distributor (10) and / or at least one gas distributor (11). These distributors ensure that the distribution of gas and liquid is maximized. This maximized distribution increases the contact between the polymer-lean vapor stream (c) and at least one condensed vapor stream (f, g), and the increased contact leads to improved removal of entrained polymer from the vapor stream.

[0093] The gas or liquid distributor can be open packing within the flow path of the stream to be distributed. Typically, the screening device fills the space between the top liquid distributor and the bottom gas distributor with random metallic packing (e.g., Koch-Glitsch ITMP). Preferably, this packing should still ensure a high recirculation flow rate. In the top portion of the scrubbing column, the cleaned liquid is used as a second-stage scrubbing steam stream.

[0094] Preferably, the first separation device (2) is a flash separator.

[0095] Preferably, the screening device (3) is a washing column.

[0096] According to the screening component in Figure 1b

[0097] Therefore, in a preferred embodiment of the invention, as described in FIG1b, the screening assembly further includes a first liquid distributor (10a) located above the first inlet (4) and below at least one second inlet (7, 8) relative to the height of the screening device (3).

[0098] Furthermore, according to a preferred embodiment of the invention, the screening assembly described in FIG1b further includes a first gas distributor (11a) located above the first inlet (4) and below at least one second inlet (7, 8) relative to the height of the screening device (3).

[0099] Preferably, in the screening assembly described in FIG1b according to a preferred embodiment of the present invention, the first gas distributor (11a) is further positioned above the first inlet (4) and below the first liquid distributor (10a) relative to the height of the screening device (3).

[0100] The positions of the first liquid distributor (10a) and the first gas distributor (11a) ensure maximum contact between the vapor flow and the condensed vapor flow.

[0101] It should be understood that there is no limit to the number of distributors. Therefore, there can be more than one distributor between inlets or between the top and bottom. For example, if the distance between the inlets is large and the distribution effect is lost as the vapor travels upward or the liquid descends, then a second or even more distributors along the way may help maintain the distribution of the two phases, thereby improving the cleaning effect.

[0102] Typically, a liquid distributor is installed below an inlet, while a vapor distributor is installed above an inlet. Preferably, when using more than two packing sections, the packing section consists of a bottom gas distributor (optionally with an upper random metal packing section) and a top liquid distributor. This arrangement ensures that the gas entering the packing section from the bottom is dispersed, and the liquid entering the packing section from the top is also dispersed, thereby maximizing the dispersed contact between the gas and liquid in the packing section.

[0103] However, in a more preferred general embodiment of the invention, at least one second inlet (7, 8) includes a first second inlet (7) for introducing a first condensate vapor flow (f) and a second second inlet (8) for introducing a second condensate vapor flow (g), wherein the first second inlet (7) is positioned above the first inlet (4) and below the second second inlet (8) relative to the height of the screening device (3), while the second second inlet (8) is positioned above the first second inlet (7) and below the first outlet (5) relative to the height of the screening device (3). This assembly provides two contact modes: between the first inlet (4) and the first second inlet (7) and between the first second inlet (7) and the second second inlet (8). In each of these modes, the contact can be individually adjusted by the nature of the first condensate vapor flow (f) and the second condensate vapor flow (g) and by the gas distributor and liquid distributor used. The gas distributor and liquid distributor can be adjusted, for example, by the type of optional random metal packing used therein. In particular, it can be adjusted by the density of the packing. The distribution of gas and liquid can be adjusted by the design of the respective distributors. Different geometric variables of the packing material affect the distribution quality along the bed. Among these variables are the column diameter / packing height ratio, the crimp height and angle, and the surface of the packing sheets (smooth, grooved, stamped). Open packing results in lower pressure drop but less distribution, while higher density packing results in higher pressure drop but increased distribution.

[0104] Therefore, the screening assembly of such a preferred general embodiment may further include a second liquid distributor (10b) located above the first liquid distributor (10a) and below the first outlet (5) relative to the height of the screening device (3).

[0105] Furthermore, the screening assembly of such a preferred general embodiment may further include a second gas distributor (11b) located above the first liquid distributor (10a) and below the first outlet (5) relative to the height of the screening device (3).

[0106] Finally, in such a preferred general embodiment of the screening assembly, the second gas distributor (11b) may be further positioned above the first liquid distributor (10a) and below the second liquid distributor (10b) relative to the height of the screening device (3).

[0107] These gas distributors and liquid distributors can be provided and adjusted as needed. However, a preferred general embodiment consisting of a first gas distributor and a first liquid distributor, as well as a second gas distributor and a second liquid distributor, is depicted in Figure 1b.

[0108] It has now been further discovered that by injecting a condensed vapor component comprising a hydrocarbon mixture (e.g., at least one solvent comprising at least one monomer and optionally at least one comonomer) into the lean polymer vapor stream (c), entrainment into the clean vapor stream of the screening device can be further significantly reduced. Without being bound by theory, we consider that the condensed phase adheres to the polymer particles, making them heavier. Therefore, the polymer particles are further removed from the gas phase. Furthermore, the high temperature of the condensed phase prevents high-concentration polymer from "sticking" to the walls or interior of the device. It can be further considered that the injection has two effects compared to simply contacting the lean polymer vapor stream (c) and the condensed vapor streams (f, g) as shown in the general embodiments according to Figures 1a and 1b. First, the condensed phase itself already provides the aforementioned effects. However, secondly, the mixture found in the lean polymer vapor stream (c) is cooled, eventually reaching its condensation point. Therefore, more condensed phase is generated through the condensation of the vapor stream itself, further enhancing the effect of reducing entrainment.

[0109] According to the screening components in Figure 2

[0110] Therefore, in a preferred embodiment of the screening assembly of the present invention according to FIG2, the first inlet (4) of the screening device (3) is configured to inject condensed vapor into the lean polymer vapor stream (c).

[0111] The condensate vapor stream used for injection into the lean polymer vapor stream (c) can generally be provided from any source. Therefore, in the preferred embodiment according to Figures 2a to 2d, a first condensate vapor source (Q1) is connected to a first inlet (4) for injection into the lean polymer vapor stream (c).

[0112] Each specific embodiment described below in Figures 2a to 2d discloses a modification of the polymer-containing condensate vapor stream (e). It should be understood that in each of these embodiments, a certain portion of the stream ((i), (f), (j), or (h)) is drawn from the stream (e). Thus, a portion of (e) is used for each cycle, but (e) can still be drawn from the screening device (3) for cleaning.

[0113] According to the screening component in Figure 2a

[0114] However, other embodiments of the screening assembly according to the invention are also conceivable. In a preferred embodiment of the screening assembly according to FIG. 2a, not only is the first condensate vapor component source connected to the first inlet (4), but the injected condensate vapor stream (i) is also connected to the first inlet (4). It should be understood that although a combination of the two connections is shown in FIG. 2a, the connection to the first condensate vapor component source (Q1) is optional.

[0115] Therefore, the preferred embodiment of the invention according to FIG. 2a relates to a screening assembly according to FIG. 1b, wherein the injected condensate vapor stream (i) containing polymer and the polymer-lean vapor stream (c) connected to the second outlet (6) are fluidly connected, preferably via a pump (12). Typically, the condensate vapor components must be compressed again to match the pressure in the polymer-lean vapor stream (c) drawn from the separation device (2) before being injected into the polymer-lean vapor stream (c). While a first fresh condensate vapor phase source (Q1) may optionally be fluidly connected to the polymer-containing condensate vapor stream (e), it should be understood that embodiments without this source are preferred.

[0116] The preferred embodiment, which includes at least partially recirculated condensate vapor stream (e) and subsequent injection of the condensate vapor component from said vapor stream into a lean polymer vapor stream (c) (via a conduit for injecting the condensate vapor stream (i) and a first inlet (4)), has the advantage that it eliminates or almost eliminates the need to introduce fresh condensate vapor component into the screening device (3) for injection. Therefore, materials and energy can be saved. In particular, since the injected condensate vapor stream (i) still has a relatively high temperature, reheating is not required. Nevertheless, since the recirculated component has been condensed, the temperature will not be too high, but it reliably ensures that the lean polymer vapor stream reaches its condensation point.

[0117] Preferably, in the preferred embodiment according to FIG. 2a, the second source (Q2) of the condensate vapor composition is connected to the polymer-containing condensate vapor stream (e). An advantage of this embodiment is that the polymer-containing condensate vapor stream (e) can be diluted, thereby adjusting the temperature and / or the composition / concentration in the polymer-containing condensate vapor stream (e).

[0118] However, other recycling schemes for polymer-containing condensate vapor streams are conceivable, which can be used individually or in combination. These are described in Figures 2b to 2d.

[0119] According to the screening component in Figure 2b

[0120] In the preferred embodiment according to FIG. 2b, a modification has been made to the screening assembly according to FIG. 1a or FIG. 1b, wherein the polymer-containing condensate vapor stream (e) connected to the second outlet (6) and the first condensate vapor stream (f) connected to the first second inlet (7) are fluidly connected, preferably via a pump (12). Typically, the condensate vapor components must be compressed again to match the pressure in the screening device (3). While FIG. 2a through 2d show the additional features of FIG. 1b, it should be understood that the additional features of FIG. 2a through 2d are combinable and are therefore disclosed in conjunction with the embodiments of FIG. 1a and FIG. 1b.

[0121] In addition, in this preferred embodiment, the second fresh condensate vapor phase source (Q2) can be fluidly connected to the conduit of the clean condensate vapor stream (e) to obtain the same advantages mentioned above.

[0122] Furthermore, in this preferred embodiment, a third fresh condensate vapor phase source (Q3) may be fluidly connected to the conduit of the first condensate vapor stream (f). In some embodiments, Q3 may serve as a supplementary stream, i.e., a compensation stream, should an disturbance occur during operation.

[0123] The advantages of this embodiment are comparable to those of the embodiment according to FIG. 2a. While the purpose of the recirculated vapor stream involves contacting the lean polymer vapor stream (c) in the screening device (3) to remove entrained polymer, an additional advantage of this embodiment is that no or almost no fresh condensed vapor component needs to be introduced into the screening device (3). Therefore, materials and energy can be saved. In particular, since the first condensed vapor stream (f) still has a relatively high temperature, reheating is not required. Nevertheless, since the recirculated component has already been condensed, the temperature will not be too high, but it can be ensured that the entrained polymer is reliably removed from the lean polymer vapor stream (c).

[0124] According to the screening component in Figure 2c

[0125] In the preferred embodiment according to FIG. 2c, the screening assembly according to FIG. 1a or FIG. 1b is modified such that the polymer-containing condensate vapor stream (e) connected to the second outlet (6) and the circulating condensate vapor stream (j) connected to the separation device (2) are fluidly connected, preferably via a pump (12) and a heater (13). Typically, the condensate vapor components must be compressed again to match the pressure required for separation in the separation device (2). Furthermore, separation in the separation device (2) typically requires increasing the temperature of the condensate vapor components in the circulating condensate vapor stream (j).

[0126] In addition, in this preferred embodiment, the second fresh condensate vapor phase source (Q2) can be fluidly connected to a clean condensate vapor stream (e) to obtain the same advantages mentioned above.

[0127] The advantage of this preferred embodiment is that at least a portion of the polymer-containing condensate vapor stream (e) is recycled back to the separation unit (2). Therefore, this arrangement improves the overall separation efficiency of the first unit and the screening unit. Furthermore, it eliminates the requirement to separate the polymer and volatile substances within the polymer-containing condensate vapor stream (e).

[0128] According to the screening component in Figure 2d

[0129] The screening assembly according to FIG. 2d further includes a third inlet (9) for introducing a heated condensate vapor stream (h). In one embodiment, a fresh heated condensate vapor stream (h) may be introduced into this third inlet (9). However, in a preferred embodiment, in the screening assembly according to FIG. 2d, the polymer-containing condensate vapor stream (e) connected to the second outlet (6) and the heated condensate vapor stream (h) connected to the third inlet (9) are fluidly connected, preferably via a pump (12) and a heater (13). Typically, the condensate vapor components must be compressed again to match the pressure in the screening device (3). In another embodiment, the arrangement of FIG. 2d may also omit the heater (13).

[0130] In addition, in this preferred embodiment, the second fresh condensate vapor phase source (Q2) can be fluidly connected to the clean condensate vapor stream (e) to obtain the same advantages mentioned above.

[0131] The advantage of the screening assembly according to Figure 2d is that the state within the screening device (3) can be controlled. It is advantageous to keep the condensed vapor components present in the screening device (3) (the upper limit of the phase is indicated by (17)) at their boiling point temperature. This ensures better vapor transport, and in particular, improves separation efficiency. If the condensed vapor components do not boil, more vapor will be extracted from the screening device in condensed form, and it is preferable to extract as many gaseous volatile compounds as possible in order to separate them from the polymer.

[0132] According to the screening components in Figure 3

[0133] It should be understood that all embodiments can be combined without any disadvantage. A preferred embodiment is depicted in Figure 3. In this preferred embodiment, the flow rates of the individual streams (f, h, i, j) can be controlled by valves. Therefore, the combined advantage of this embodiment of the screening assembly of the present invention is that the flow rates can be adjusted to control the conditions found in the first and screening devices. For example, if the temperature of the condensed vapor component in the screening device (3) drops below the boiling point of the vapor component, the flow rate of the heated condensed vapor stream (h) introduced into the third inlet (9) can be increased, resulting in an increase in the temperature of the condensed vapor component in the screening device (3). Similarly, if the vapor component in the lean polymer stream (c) does not reach its condensation point when entering the screening device 3, the flow rate of the injected condensed vapor component can be increased. If the separation efficiency of the screening device (3) is to be improved, i.e., if the clean vapor stream (d) still contains excessive polymer, the flow rate of the first condensed vapor stream (f) can be increased. Therefore, this embodiment allows for multifunctional control of the reaction conditions in the screening device according to the present invention.

[0134] According to the screening components in Figure 4

[0135] The sieving assembly according to the invention is illustrated with respect to the embodiments of FIG4a and FIG4b, taking into account modifications to the clean vapor stream (d) and the second condensed vapor stream (g). Although these embodiments are described relative to the most general embodiment according to FIG1a, it should be understood that the modifications shown in the embodiments of FIG4a and FIG4b can also be combined with any of the embodiments shown in FIG1b, FIG2a to FIG2d and FIG3.

[0136] According to the screening component in Figure 4a

[0137] The screening assembly according to a preferred embodiment of the invention according to FIG4a further includes a condenser (14), the condenser including an inlet and an outlet, wherein a first outlet (5) is fluidly connected to the inlet of the condenser (14) via a conduit for a clean vapor flow (d), and wherein the outlet of the condenser (14) is fluidly connected to a second inlet (8) via a conduit for a second condensed vapor flow (g).

[0138] Preferably, in the screening assembly according to the embodiment of FIG4a, a fourth fresh condensate vapor phase source (Q4) is fluidly connected to the second condensate vapor stream (g). The fourth fresh condensate vapor phase source (Q4) allows for control of the second condensate vapor stream (g) in terms of temperature and composition.

[0139] A general advantage of the preferred embodiment according to Figure 4a is that at least a portion of the clean vapor component stream (d) is recycled back to the second condensed vapor stream (g). The second condensed vapor stream (g) serves to provide a second contact step between the lean polymer vapor stream (c) and the condensed vapor stream to remove polymer still present in the lean polymer vapor stream (c). By recycling a portion of the clean vapor stream (d), not only is the need for additional input of fresh condensed vapor component reduced, but the energy extracted from the system by the clean vapor stream (d) is also at least partially returned to the screening device (3).

[0140] According to the screening component in Figure 4b

[0141] Furthermore, preferably, the screening assembly according to the embodiment of FIG4b includes a container (15) having an inlet, a first outlet, and a second outlet, wherein the inlet is fluidly connected to the outlet of the condenser (14), and the first outlet is fluidly connected to a second condensate vapor stream (g). The second outlet of the container (15) is preferably adapted to extract a clean condensate vapor phase (k).

[0142] The container (15) forms a reservoir for a clean stream of condensed vapor (d), which further ensures the reliable operability of the screening assembly.

[0143] Preferably, in the screening assembly according to the embodiment of FIG4b, a fourth fresh condensate vapor phase source (Q4) is fluidly connected to the second condensate vapor stream (g). The fourth fresh condensate vapor phase source (Q4) allows for control of the second condensate vapor stream (g) in terms of temperature and composition.

[0144] The screening assembly according to Figure 4b further includes a pump (16) having an inlet and an outlet, wherein the inlet is fluidly connected to the outlet of the condenser (14) and the outlet is fluidly connected to a second condensate vapor stream (g).

[0145] According to the screening components in Figure 5

[0146] Figure 5 illustrates a preferred embodiment of the screening assembly of the present invention, which combines modifications to the polymer-containing condensed vapor stream (e) of the embodiments according to Figures 2a to 2d, and modifications to the clean vapor stream (d) of the embodiments according to Figures 4a and 4b. Furthermore, the screening device (3) of this embodiment incorporates the gas distributor and liquid distributor described in the embodiment according to Figure 1b, with an optional random metal packing section between the liquid distributor and the gas distributor. Therefore, the screening device (3) used in the embodiment according to Figure 5 is a washing column. Preferably, the separation device (2) used in the embodiment according to Figure 5 is a flash separator.

[0147] Other screening components

[0148] In another preferred embodiment, more than one screening device (3) may be used, preferably connected in series. In such a screening assembly, the clean vapor stream (d) of the first screening device (3) is connected to the first inlet (4) of the screening device, and so on. Although theoretically many screening devices can be connected in series, it has been proven that a significant improvement in separation efficiency can be achieved with just a second screening device. Therefore, in the most preferred embodiment, the screening assembly includes a first separation device (2), preferably a flash separator, a first screening device (3), preferably a first washing column, and a second screening device (3), preferably a second washing column, connected in series. It should be understood that several separation devices, i.e., flash separators, may be used in a polymerization reactor assembly. The present invention, i.e., the screening device of the present invention, may be applied after each such separation device.

[0149] According to the method of the present invention

[0150] The method of the present invention aims to screen polymers from an effluent stream (a), which is preferably drawn from a polymerization reactor.

[0151] Polymerization process

[0152] The effluent stream can be prepared using any polymer production process that requires the separation of volatile compounds from the polymer after production. Preferably, the invention is applicable to supercritical, solution, and advanced solution polymerization processes. More preferably, continuous supercritical, solution, and advanced solution polymerization processes are used. Most preferably, the production process includes a continuous solution polymerization process.

[0153] The polymer produced in this invention can be any polymer, and volatile compounds are used in its production. Preferably, the polymer produced in this invention is an olefin homogeneous polymer or copolymer. More preferably, the monomer of such polymer is selected from α-olefins having 2 to 4 carbon atoms, preferably ethylene, propylene, 1-butene, and most preferably ethylene. Most preferably, the polymer is a polyethylene copolymer or homopolymer.

[0154] When the polymer is a copolymer, the monomer is preferably different from the α-olefin monomer and is selected from the group consisting of linear and cyclic olefins and α-olefins having 2 to 12 carbon atoms and mixtures thereof. More preferably, the monomer is an α-olefin different from the olefin monomer and is selected from the group consisting of linear olefins having 2 to 12 carbon atoms (preferably 4 to 10 carbon atoms) and mixtures thereof, with 1-octene being the most preferred.

[0155] In the most preferred embodiment, the polymer is produced from the solution polymerization process disclosed below.

[0156] Polymerization is typically carried out in the presence of an olefin polymerization catalyst. The olefin polymerization catalyst can be any catalyst known in the art, capable of polymerizing monomers and optionally copolymers. Therefore, the polymerization catalyst can be a Ziegler-Natta catalyst disclosed in EP-A-280352, EP-A-280353, and EP-A-286148, or a metallocene catalyst disclosed in WO-A-1993025590, US-A-5001205, WO-A-1987003604, and US-A-5001244, or a combination thereof. Other suitable catalysts may also be used, such as post-transition metal catalysts.

[0157] In solution polymerization processes, a solvent is also present. The solvent is in a liquid or supercritical state under polymerization conditions. The solvent is typically and preferably a hydrocarbon solvent. The liquid hydrocarbon solvent used is preferably C42-C ... 5-12 - Hydrocarbons, which can be unsubstituted or C-substituted. 1-4 Alkyl-substituted compounds, such as pentane, methylpentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, and hydrogenated naphtha. More preferably, unsubstituted C4 compounds are used. 6-10 - Hydrocarbon solvents.

[0158] Other components may also be added to the reactor. It is well known that hydrogen is added to the reactor to control the molecular weight of the polymer formed during the polymerization process. The use of different antifouling compounds is also known in the art. Furthermore, different types of accelerators or retarders can be used to control the activity of the catalyst.

[0159] Typically, in an effluent stream containing a mixture of solvent, polymer, and hydrocarbons (such as solvent, unreacted monomer, and optional comonomer), the polymer content is 10 wt% to 35 wt%, preferably 12.5 wt% to 25 wt%, and more preferably 15 wt% to 25 wt%.

[0160] The effluent stream is the feed stream entering the separation unit. It can be the product stream from the polymerization reactor, as described above. The reaction mixture stream then typically has the polymer content, composition, temperature, and pressure disclosed above.

[0161] Preferably, the effluent stream comprises a polymer, at least one unreacted monomer, and optionally at least one unreacted comonomer. Depending on the polymerization process, the reaction mixture may further comprise at least one solvent.

[0162] According to the screening method in Figure 1a

[0163] In the most general embodiment of the invention according to FIG. 1a, a method for sieving polymer from an effluent stream (a), preferably drawn from a polymerization reactor (1), wherein the effluent stream (a) comprises a mixture of polymer and hydrocarbons, such as at least one solvent, at least one monomer, and optionally at least one comonomer, the method comprising the following steps

[0164] A) Separate the outflow stream (a) into a polymer-rich stream (b) and a polymer-lean vapor stream (c).

[0165] B) Contact the polymer-lean vapor stream (c) with the first condensed vapor stream (f), wherein the flow direction of the first condensed vapor stream (f) is opposite to the flow direction of the polymer-lean vapor stream (c), to produce a clean vapor stream (d) and a polymer-containing condensed vapor stream (e).

[0166] Preferably, the lean polymer vapor stream generated in step A) is superheated. This is due to the conditions typically used in this separation step. Preferably, step A) is carried out under conditions that allow volatile compounds in the effluent stream to evaporate from the condensate phase (mainly comprising the polymer). Preferably, the temperature used in step A) is between 100°C and 400°C, more preferably between 130°C and 300°C, and even more preferably between 170°C and 250°C. Furthermore, the pressure drop relative to the pressure in the effluent stream (a) is preferably greater than 30 gauge pressures, more preferably greater than 60 gauge pressures, and most preferably greater than 90 gauge pressures. Therefore, the conditions in the lean polymer vapor stream (c) are set such that the hydrocarbon mixture, i.e., the solvent, unreacted monomers, and / or comonomers, is not at its condensation point. Therefore, the mixture of compounds in the lean polymer vapor stream (c) is typically found to be in gaseous form.

[0167] Therefore, it is preferable to use a flash separator for step A).

[0168] Preferably, the polymer is a homogeneous or comonomer of polyolefin, more preferably a homogeneous or comonomer of polyethylene or polypropylene.

[0169] Preferably, the polymer in the effluent stream is molten. This ensures optimal mass exchange of the volatile compounds that evaporate from the polymer in step A).

[0170] It has now been surprisingly discovered that by contacting the condensed vapor components with the lean polymer vapor stream (c), the polymer trapped in the lean polymer vapor stream (c) can be effectively removed.

[0171] Further investigation revealed that distributing the lean polymer vapor stream (c) and / or the condensate vapor stream leads to increased contact and improves the separation efficiency of the entire process.

[0172] According to the screening method in Figure 1b

[0173] Therefore, in the method of the preferred embodiment of the present invention according to FIG1b, in step B), the first condensate vapor stream (f) is distributed using the first liquid distributor (10a).

[0174] Furthermore, preferably, in an embodiment of the method of the invention according to FIG. 1b, in step B), a first gas distributor (11a) is used to distribute the lean polymer vapor stream (c). In a preferred embodiment, the space between the first liquid distributor (10a) and the first gas distributor (11a) is filled with random metal packing.

[0175] The distribution of the first condensate vapor stream (f) preferably occurs downstream of the distribution of the lean polymer vapor stream (c) with respect to the flow direction of the lean polymer vapor stream (c).

[0176] In another preferred embodiment of the method of the present invention described in FIG1b, the method further includes the step of step C) contacting the lean polymer vapor stream (c) with a second condensed vapor stream (g) downstream of the contact in step B) relative to the flow direction of the lean polymer vapor stream (c), wherein the flow direction of the second condensed vapor stream (g) is countercurrent to the flow direction of the lean polymer vapor stream (c).

[0177] In this preferred embodiment, in step C), the second condensate vapor stream (g) is diffused using the second liquid distributor (10b). Furthermore, it is preferred that in step C), the lean polymer vapor stream (c) is diffused using the second gas distributor (11b). In a preferred embodiment, the space between the second liquid distributor (10b) and the second gas distributor (11b) is filled with random metal packing.

[0178] Therefore, most preferably, in step C), the distribution of the second condensate vapor stream (g) occurs downstream of the distribution of the lean polymer vapor stream (c) with respect to the flow direction of the lean polymer vapor stream (c).

[0179] According to the sieving method in Figure 2a

[0180] It has now been surprisingly discovered that by injecting the condensed vapor components into the lean polymer vapor stream (c) prior to step B), the polymer trapped in the lean polymer vapor stream (c) can be further significantly removed.

[0181] Therefore, in a preferred embodiment of the method of the invention according to FIG. 2a, in which a condensed vapor component comprising a hydrocarbon mixture (e.g., a solvent comprising at least one monomer and optionally at least one comonomer) is injected into a lean polymer vapor stream (c) by means of a jet condensed vapor stream (i), which occurs upstream of the contact in step B) and downstream of the separation in step A) (relative to the flow direction of the lean polymer vapor stream (c). Preferably, the jet condensed vapor stream (i) is compressed before being injected into the lean polymer vapor stream (c).

[0182] In one embodiment of the method of the invention according to FIG. 2a, the jet condensate vapor stream is fed from a first fresh condensate vapor component source. However, preferably, in step B), the polymer-containing condensate vapor stream (e) is at least partially fed into the jet condensate vapor stream (i). Preferably, the jet condensate vapor stream (i) is compressed using pump 12. Optionally, a second fresh condensate vapor component source (Q2) is supplied to the polymer-containing condensate vapor stream (e). However, a preferred embodiment is that there is no second fresh condensate vapor component source (Q2).

[0183] This preferred embodiment of the method of the present invention includes the recirculation of the condensate vapor stream (e) and the subsequent injection of the condensate vapor component in the stream into the lean polymer vapor stream (c) via a conduit and a first inlet (4) of the injected condensate vapor stream (i). The advantage is that little or no fresh condensate vapor component needs to be introduced into the screening device (3) for injection. As a result, materials and energy can be saved. In particular, since the injected condensate vapor stream (i) still has a relatively high temperature, it does not need to be reheated. Nevertheless, since the recirculated component has been condensed, the temperature will not be too high, but it can reliably ensure that the lean polymer vapor stream reaches its condensation point.

[0184] According to the screening method in Figure 2b

[0185] In another preferred embodiment of the method of the invention according to FIG. 2b, the condensate vapor stream (e) is at least partially fed into the first condensate vapor stream (f). Furthermore, preferably, the polymer-containing condensate vapor stream (e) is compressed before being fed into the first condensate vapor stream (f). Additionally, in a preferred embodiment of the method of the invention according to FIG. 2b, optionally and preferably, a second fresh condensate vapor component source (Q2) is supplied to the polymer-containing condensate vapor stream (e).

[0186] The advantages of this embodiment are comparable to those of the embodiment according to FIG. 2a. While the purpose of the recirculated vapor stream is to contact the lean polymer vapor stream (c) in the screening device (3) to remove entrained polymer, in this embodiment, there is also an advantage that no or almost no fresh condensed vapor component needs to be introduced into the screening device (3). As a result, material and energy savings are possible. In particular, since the first condensed vapor stream (f) still has a relatively high temperature, it does not need to be reheated. Nevertheless, since the recirculated component has already been condensed, the temperature will not be too high, but it can be ensured that the entrained polymer is reliably removed from the lean polymer vapor stream (c).

[0187] According to the screening method in Figure 2c

[0188] In another preferred embodiment of the method of the invention according to FIG. 2c, a circulating condensate vapor stream (j) is introduced into step A). ​​Preferably, a polymer-containing condensate vapor stream (e) is at least partially fed into the circulating condensate vapor stream (j). Preferably, the circulating condensate vapor stream (j) is compressed using pump 12. Even more preferably, the circulating condensate vapor stream (j) is heated using heater (13). Optionally and preferably, a second source of fresh condensate vapor components (Q2) is supplied to the polymer-containing condensate vapor stream (e).

[0189] The advantage of this preferred embodiment is that at least a portion of the polymer-containing condensate vapor stream (e) is recovered into the separation unit (2). Therefore, this arrangement improves the overall separation efficiency of the first and screening units combined. Furthermore, it eliminates the need to separate polymers and volatile substances from the polymer-containing condensate vapor stream (e).

[0190] According to the sieving method in Figure 2d

[0191] In another preferred embodiment of the method of the present invention according to FIG. 2d, the heated condensate vapor stream (h) is in contact with the lean polymer vapor stream (c), wherein the flow direction of the heated condensate vapor stream (h) is countercurrent to the flow direction of the lean polymer vapor stream (c).

[0192] Preferably, at least a portion of the polymer-containing condensate vapor stream (e) is fed into the heated condensate vapor stream (h). Preferably, the heated condensate vapor stream (h) is compressed using a pump (12). Even more preferably, the heated condensate vapor stream (h) is heated using a heater (13). Optionally and preferably, a second source of fresh condensate vapor components (Q2) is supplied to the polymer-containing condensate vapor stream (e).

[0193] The advantage of the method according to Figure 2d is that the conditions within the screening device (3) can be controlled. It is advantageous to keep the condensed vapor components present in the screening device (3) (the upper limit of the phase is indicated by (17)) at their boiling point temperature. This ensures better steam transport, and in particular, improves separation efficiency. If the condensed vapor components do not boil, more steam will be extracted from the screening device in condensed form, and it is preferable to extract as many gaseous volatile compounds as possible in order to separate them from the polymer.

[0194] According to the screening method in Figure 3

[0195] It should be understood that, in the embodiments of the processing method according to Figures 2a to 2d, the modifications to the polymer-containing condensate vapor stream in step A) can be combined. As a particularly preferred embodiment of the method according to Figure 3, all modifications to the polymer-containing condensate vapor stream (e) are combined.

[0196] According to the screening method in Figure 4a

[0197] In another preferred embodiment of the method of the invention according to FIG. 4a, in step C), the clean vapor stream (d) is condensed and at least partially fed into the second condensed vapor stream (g). Preferably, a portion of the clean vapor stream is extracted as a clean vapor phase (k).

[0198] A general advantage of the preferred embodiment according to Figure 4a is that at least a portion of the clean vapor stream (d) is recycled back to the second condensed vapor stream (g). The second condensed vapor stream (g) serves to provide a second contact step between the lean polymer vapor stream (c) and the condensed vapor stream to remove polymer still present in the lean polymer vapor stream (c). By recycling a portion of the clean vapor stream (d), not only is the need for additional input of fresh condensed vapor components reduced, but the energy extracted from the system by the clean vapor stream (d) is also at least partially returned to the screening device (3).

[0199] According to the screening method in Figure 4b

[0200] In a more preferred embodiment of the method of the invention according to FIG. 4b, the clean vapor stream (d) is stored in a container after being condensed. Preferably, the clean vapor stream (d) is compressed after being fed from the container to a second condensed vapor stream (g).

[0201] The advantage of this embodiment is that the storage of clean vapor stream (d) ensures a reliable supply of condensate vapor.

[0202] According to the screening method in Figure 5

[0203] The preferred embodiment of the method of the present invention according to FIG5 is a combination of the embodiment of the method of the present invention according to FIG3 and the modification scheme of the polymer-containing flow (e) shown in the embodiment of the method of the present invention according to FIG4a and FIG4b.

[0204] General features of the method of the present invention

[0205] In the preferred method according to the invention, step A) is performed using a flash separator.

[0206] More preferably, steps B) and / or C) of the method of the present invention are performed using a washing column.

[0207] Preferably, according to the method of the invention, the temperature in the washing column is between 30°C and 240°C, preferably between 100°C and 220°C, and most preferably between 130°C and 200°C. Generally, the method of the invention is preferably carried out at temperature conditions that ensure the polymer remains in a molten state in the first washing column throughout the process.

[0208] Preferably, the method according to the invention is carried out at a pressure of 0.0 gauge pressure to 15.0 gauge pressure in the washing column.

[0209] Preferably, according to the method of the invention, the temperature of the clean steam stream (d) is between 90°C and 200°C, more preferably between 100°C and 180°C, and most preferably between 120°C and 160°C.

[0210] In a more preferred embodiment of the invention, step B) is performed in series multiple times. In a particularly preferred embodiment of the invention, step B) is performed such that the clean vapor stream (d) from the first washing column is selectively reheated and fed into a new separator, where the lean polymer vapor phase is treated again with a washing column.

[0211] Generally, the method of the present invention is preferably carried out at a temperature that ensures the polymer remains in a molten state in the second washing column throughout the process.

[0212] Furthermore, preferably, the method according to the invention treats the lean gas phase generated in the next separation unit (2') according to the invention. The polymer-rich stream (b) from the separation unit (2) is compressed again, heated, and fed into the next separation unit (2) to generate the next lean polymer vapor stream (c'). Since the composition of the polymer-rich vapor stream (b) going to the next separation unit (2') is different from that of the effluent stream (a) going to the separation unit (2), the processing conditions in the next separation unit (2') are also different, wherein the flash evaporation step and the washing step are carried out at a pressure in a third washing column between 0.0 gauge pressure and 6.0 gauge pressure, preferably between 0.1 gauge pressure and 2.0 gauge pressure, and more preferably between 0.2 gauge pressure and 1.0 gauge pressure. The advantage of these reduced pressures compared to the pressure applied in the first washing column is that volatiles with higher molecular weights can also be effectively removed from the lean polymer vapor stream. Preferably, the method is carried out at a certain temperature of the next clean steam stream (d') in the third washing column, said temperature being between 50°C and 130°C, more preferably between 55°C and 120°C, and most preferably between 60°C and 110°C.

[0213] Use of the screening component of the present invention

[0214] The present invention also relates to the use of the screening component according to the invention in preventing scaling in a polymerization process.

[0215] Example

[0216] This example employs a vertical setup with a washing column to create close contact between the condensate vapor stream and the polymer-lean vapor stream. The setup according to Figure 5 has been used, where the separation step is performed using a flash separator. Polymer entrainment is discharged from the bottom of the washing column by gravity through the polymer-containing condensate vapor stream (e). The clean vapor stream (d) exits from the top of the washing column.

[0217] Before the washing column, solvent spraying is performed to ensure that the vapor is at its condensation point, as the lean polymer vapor stream is superheated.

[0218] The lean polymer vapor stream enters the scrubbing column above the liquid surface (17) in the liquid pool and moves upward, forming a countercurrent with the descending condensate vapor stream. The scrubbing column is filled with packing material between the liquid distributor 10 and the gas distributor 11 to improve the contact between the lean polymer vapor stream and the condensate vapor stream. In this example, a high flow rate of condensate vapor is applied at the bottom to ensure thorough particle removal (cleaning).

[0219] The washing column operates at the boiling point of the vapor components.

[0220] To improve separation efficiency, a second washing column is used, which is connected in series with the clean vapor flow (e) of the first washing column.

[0221] First washing column

[0222] The operating conditions are set to a temperature higher than the polymer melting temperature.

[0223] For polymers produced from octene monomers, the melting temperature ranges from about 40°C for the lowest density to about 130°C for a density of about 940 kg / m³.

[0224] Therefore, if the pressure of the first washing column is maintained above 5 gauge pressure, it will always operate in the state of molten polymer (see Table 1).

[0225] Table 1: Operating Temperature of the Washing Column

[0226] Bottom temperature Top temperature Octene grade 160-200 ℃ 140-180℃

[0227] Terms and Conditions

[0228] 1. A method for screening polymers from a lean polymer stream, wherein the method comprises the following steps:

[0229] A) Separating the effluent stream (a) comprising the polymer and hydrocarbon mixture into a polymer-rich stream (b) and a polymer-lean vapor stream (c);

[0230] B) Contact the lean polymer vapor stream (c) with the first condensate vapor stream (f).

[0231] The first condensate vapor stream (f) flows in the opposite direction to the polymer-lean vapor stream (c) to produce a clean vapor stream (d) and a polymer-containing condensate vapor stream (e).

[0232] 2. The method according to Clause 1 further includes the following steps:

[0233] C) The polymer-lean vapor stream (c) is brought into contact with a second condensed vapor stream (g) downstream of the contact in step B), with respect to the flow direction of the polymer-lean vapor stream (c), wherein the flow direction of the second condensed vapor stream (g) is countercurrent to the flow direction of the polymer-lean vapor stream (c).

[0234] 3. The method according to any of the preceding clauses, wherein, relative to the flow direction of the lean polymer vapor stream (c), upstream of the contact in step B) and downstream of the separation in step A), a jet condensate vapor stream (i) is used to inject a condensate vapor component comprising a hydrocarbon mixture into the lean polymer vapor stream (c), wherein the second condensate vapor stream (e) is partially fed into the jet condensate vapor stream (i).

[0235] 4. The method according to any of the preceding clauses, wherein in step B), the polymer-containing condensate vapor stream (e) is fed into the first condensate vapor stream (f).

[0236] 5. The method according to any of the preceding clauses, wherein a circulating condensate vapor stream (j) is introduced into step A), wherein the polymer-containing condensate vapor stream (e) is at least partially fed into the circulating condensate vapor stream (j), and wherein the circulating condensate vapor stream (j) is heated using a heater (13).

[0237] 6. The method according to any of the preceding clauses, wherein the heated condensate vapor stream (h) is in contact with the lean polymer vapor stream (c), wherein the flow direction of the heated condensate vapor stream (h) is countercurrent to the flow direction of the lean polymer vapor stream (c), wherein the polymer-containing condensate vapor stream (e) is at least partially fed into the heated condensate vapor stream (h), and wherein the heated condensate vapor stream (h) is optionally heated using a heater (13).

[0238] 7. The method according to any one of the preceding clauses 2 to 6, wherein in step C), the clean vapor stream (d) is condensed and fed into the second condensed vapor stream (g).

[0239] 8. A screening assembly, comprising

[0240] - A separation device (2) connected to a conduit for an effluent stream (a) comprising a hydrocarbon mixture, wherein the separation device (2) is configured to separate the effluent stream (a) into a polymer-rich stream (b) and a polymer-lean vapor stream (c), wherein the first separation device (2) includes an inlet, a first outlet for extracting the polymer-rich stream (b), and a second outlet for extracting the polymer-lean vapor stream (c).

[0241] - A screening device (3) connected to the separation device (2) via a conduit for the lean polymer vapor stream (c), wherein the screening device (3) comprises:

[0242] The first inlet (4) is connected to the conduit for the lean polymer vapor flow (c).

[0243] The first outlet (5) is used to extract a clean steam stream (d).

[0244] The second outlet (6) is used to extract the condensate vapor stream (e) containing the polymer, and

[0245] At least one second inlet (7, 8) is used to introduce the condensate vapor stream (f, g).

[0246] The at least one second inlet (7, 8) is located above the first inlet (4) and below the first outlet (5) relative to the height of the screening device (3).

[0247] The first inlet (4) is located above the second outlet (6) and below the at least one second inlet (7, 8) relative to the height of the screening device (3).

[0248] 9. The screening assembly according to Clause 8, wherein the at least one second inlet (7, 8) includes

[0249] - The first second inlet (7) is used to introduce the first condensate vapor stream (f), and

[0250] - A second inlet (8) is used to introduce the second condensate vapor stream (g).

[0251] The first second inlet (7) is located above the first inlet (4) and below the second second inlet (8) relative to the height of the screening device (3), and the second second inlet (8) is located above the first second inlet (7) and below the first outlet (5) relative to the height of the screening device (3).

[0252] 10. The screening assembly according to any one of the preceding clauses 8 or 9, wherein the first inlet (4) is configured to inject condensed vapor into the lean polymer vapor stream (c), and the polymer-containing condensed vapor stream (e) connected to the second outlet (6) and the jet condensed vapor stream (i) injected into the lean polymer vapor stream (c) are fluidly connected, preferably via the pump (12).

[0253] 11. The screening assembly according to any one of the preceding clauses 8 to 10, wherein the polymer-containing condensate vapor stream (e) connected to the second outlet (6) and the condensate vapor stream (f) connected to the first second inlet (7) are fluidly connected, preferably via a pump (12).

[0254] 12. The screening assembly according to any one of the preceding clauses 8 to 11, wherein the polymer-containing condensate vapor stream (e) connected to the second outlet (6) and the circulating condensate vapor stream (j) connected to the separation device (2) are fluidly connected, preferably via the pump (12) and the heater (13).

[0255] 13. The screening assembly according to any one of the preceding clauses 8 to 12 further includes a third inlet (9) for introducing a heated condensate vapor stream (h), wherein the polymer-containing condensate vapor stream (e) connected to the second outlet (6) and the heated condensate vapor stream (h) connected to the third inlet (9) are fluidly connected, preferably via the pump (12) and the heater (13).

[0256] 14. The screening assembly according to any one of the preceding clauses 8 to 13 further includes a condenser (12) comprising an inlet and an outlet, wherein the first outlet (5) is fluidly connected to the inlet of the condenser (14) via a conduit for the clean vapor flow (d), and wherein the outlet of the condenser (14) is fluidly connected to the second inlet (8) via a conduit for the second condensed vapor flow (g).

[0257] 15. The screening assembly as described in any of the preceding clauses 8 to 14 is used to prevent scaling.

Claims

1. A method for screening polymers from a lean polymer stream, wherein the method comprises the following steps: A) Separating the effluent stream (a) comprising the polymer and hydrocarbon mixture into a polymer-rich stream (b) and a polymer-lean vapor stream (c); B) Contact the lean polymer vapor stream (c) with the first condensate vapor stream (f), The first condensate vapor stream (f) flows in the opposite direction to the polymer-lean vapor stream (c) to produce a clean vapor stream (d) and a polymer-containing condensate vapor stream (e). In this process, the polymer in the effluent stream (a) is molten. Step B) involves using a washing column, wherein the temperature in the washing column is between 100°C and 220°C and the pressure in the washing column is between 0.0 gauge pressure and 15 gauge pressure. Upstream of the contact in step B) and downstream of the separation in step A), relative to the flow direction of the lean polymer vapor stream (c), a condensate vapor component comprising a hydrocarbon mixture is injected into the lean polymer vapor stream (c) using a jet condensate vapor stream (i), wherein the polymer-containing condensate vapor stream (e) is partially fed into the jet condensate vapor stream (i).

2. The method according to claim 1, further comprising the following steps: C) The lean polymer vapor stream (c) is brought into contact with a second condensed vapor stream (g) downstream of the contact in step B), with respect to the flow direction of the lean polymer vapor stream (c), wherein the flow direction of the second condensed vapor stream (g) is countercurrent to the flow direction of the lean polymer vapor stream (c).

3. The method according to claim 1, wherein in step B), the polymer-containing condensate vapor stream (e) is fed into the first condensate vapor stream (f).

4. The method according to claim 1, wherein a circulating condensate vapor stream (j) is introduced into step A), wherein the polymer-containing condensate vapor stream (e) is at least partially fed into the circulating condensate vapor stream (j), and wherein the circulating condensate vapor stream (j) is heated using a heater (13).

5. The method according to claim 1, wherein the heated condensate vapor stream (h) is in contact with the lean polymer vapor stream (c), wherein the flow direction of the heated condensate vapor stream (h) is countercurrent to the flow direction of the lean polymer vapor stream (c), wherein the polymer-containing condensate vapor stream (e) is at least partially fed into the heated condensate vapor stream (h), and wherein the heated condensate vapor stream (h) is heated using a heater (13).

6. The method according to claim 2, wherein in step C), the clean vapor stream (d) is condensed and fed into the second condensed vapor stream (g).

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