Apparatus and method for preparing a feed stream for solution polymerization

Abstract

A feed apparatus for preparing a feed stream for solution polymerization, comprising a feed vessel, the feed vessel comprising a top region and a bottom region; a feed outlet for withdrawing the feed stream, wherein the feed outlet is positioned at the bottom region; a waste outlet for withdrawing a waste vapor stream, wherein the waste outlet is positioned at the top region; a first heat exchanger positioned below the top region; an absorber positioned below the first heat exchanger; a first inlet for introducing a fresh liquid stream into the absorber or on top of the absorber, wherein the first inlet is positioned at the absorber; a second inlet for introducing a recycle liquid stream, wherein the second inlet is positioned below the first inlet; and a third inlet for introducing a recycle vapor stream, wherein the third inlet is positioned below the second inlet and above the feed outlet.

Description

[0001] This invention relates to an apparatus and method for preparing a feed stream for solution polymerization. Background Technology

[0002] In solution polymerization, it is essential that all reactants be completely absorbed (i.e., dissolved) in the solvent upstream of the reactor. Therefore, the reactants and solvent are typically mixed and dissolved together before being introduced into the polymerization reactor. This method is generally understood as the preparation of the feed stream for the solution polymerization reactor.

[0003] Problems to be solved

[0004] The feed stream of a solution polymerization reactor can be prepared by mixing fresh solvent and fresh reactants. However, a portion of the mixture leaving the reactor is typically recycled and reintroduced into the feed stream preparation. This setup offers advantages not only in material recycling but also in energy recycling, as the circulating stream still provides a certain temperature and pressure, in addition to the unreacted reactants and solvent it contains.

[0005] However, these recirculating streams also contain components whose concentrations should be controlled, ideally reduced. One category of such components includes volatile impurities. Failure to remove these impurities will cause them to accumulate during recirculation. This accumulation can lead to disturbances in the process and deviations in reactor control. Therefore, removing these volatile impurities in the feed preparation step is a common objective. Another category includes hydrogen, which is commonly used as a chain transfer agent in polymerization processes. For certain polymerization products, it is necessary to control (i.e., at least partially remove) the amount of hydrogen in the feed stream to prevent the product from deviating from the desired property set and optimal operating window / settings.

[0006] Furthermore, these circulating streams typically consist of condensed products (liquid) and uncondensed products (vapor). Volatile impurities and hydrogen are usually present in the gas phase, but may also be present in the liquid phase.

[0007] Removing volatile components from the liquid phase or liquid / gas combination phase is typically done by simply evacuating the volatiles (i.e., by allowing them to evaporate when the pressure is suddenly reduced). However, in the case of solution polymerization, volatile reactants, such as ethylene or propylene, are also present in the circulating stream. Therefore, simply evacuating these volatile components will inevitably lead to a significant loss of reactants that can still be used in the solution polymerization process.

[0008] Therefore, considering the control of volatile components and the improvement of volatile reactant circulation, there is a general need for optimized apparatus and methods for preparing feed streams for solution polymerization.

[0009] Purpose of the invention

[0010] In view of the above problems, one object of the present invention is to provide a feeding device for preparing a feed stream for solution polymerization, which can remove volatile components, such as hydrogen, inert gases and / or volatile impurities, while preventing the loss of volatile reactants such as ethylene or propylene.

[0011] More specifically, in view of the above-mentioned problems, a second object of the present invention is to provide a method for preparing a feed stream for solution polymerization that can remove volatile components, such as hydrogen, inert gases and / or volatile impurities, while preventing the loss of volatile reactants such as ethylene or propylene. Summary of the Invention

[0012] Now, it has been surprisingly found that the above-mentioned problem is solved by a feeding device for preparing a feed stream for solution polymerization, the feeding device comprising a feed container including a top region and a bottom region; a feed outlet for extracting the feed stream, wherein the feed outlet is located in the bottom region; a waste outlet for extracting waste vapor stream, wherein the waste outlet is located in the top region; a first heat exchanger located below the top region; an absorber located below the first heat exchanger; a first inlet for introducing a fresh liquid stream into or above the absorber, wherein the first inlet is located at the absorber; a second inlet for introducing a circulating liquid stream, wherein the second inlet is located below the first inlet; and a third inlet for introducing a circulating vapor stream, wherein the third inlet is located below the second inlet and above the feed outlet.

[0013] It was further surprising to discover that the problem was solved by a solution polymerization reactor assembly including the feed device.

[0014] It was further surprising to discover that the problem was solved by a method for preparing a feed stream for solution polymerization, the feed stream comprising at least one solvent, at least one reactant, and optionally hydrogen, the method comprising the following steps: providing at least one fresh liquid stream comprising the at least one solvent and optionally the at least one reactant; providing at least one circulating liquid stream comprising the at least one solvent and the at least one reactant; providing at least one vapor circulating stream comprising the at least one reactant; contacting the at least one circulating vapor stream with the at least one circulating liquid stream to generate a contacting circulating liquid stream and a contacting circulating vapor stream; contacting the contacting circulating vapor stream with the at least one fresh liquid stream to generate a contacting fresh liquid stream and a waste vapor stream; combining the contacting fresh liquid stream with the contacting circulating liquid stream to generate the feed stream; extracting the waste vapor stream; and extracting the feed stream.

[0015] definition

[0016] As used herein, the term "volatile component" refers to preferred components in the liquid and vapor circulation streams provided by the circulation section in a solution polymerization process. These streams include components that can evaporate from these liquid streams when the pressure is released or the temperature is increased. Such volatile components can be inert gases (e.g., nitrogen), unreacted light monomers (e.g., ethylene and propylene), low-carbohydrate substances (e.g., methane, ethane, propane, or butane), volatile impurities typically provided by side reactions in the polymerization process, and hydrogen.

[0017] The term "fresh liquid" as used in this article refers to a liquid used in the feed stream under ambient conditions, namely 1 atmosphere and 20°C, that contains no amount of volatile components.

[0018] The term "circulating liquid" as used in this article refers to a liquid with a certain amount of volatile components used in the feed stream under ambient conditions, namely 1 atmosphere and 20°C.

[0019] The term "circulating vapor" as used in this article refers to a gaseous composition containing a certain amount of volatile components.

[0020] The term “reactant” as used in this article refers to monomers (such as ethylene or propylene), but also includes optional comonomers.

[0021] As used herein, the term "absorber" refers to a device suitable for enhancing the contact between liquid and gas phases. Preferably, the absorber is a packed bed column and / or a tray column. However, tray columns require more space than packed columns. Therefore, a packed bed column is more preferred. Most preferably, the absorber comprises one or more units, one of which includes a liquid distributor at the top, followed by a section of packing material, preferably random metallic packing such as Intalox metallic packing or Raschig rings, and a gas distributor at the bottom.

[0022] It should be further understood that the terms “below” and “above” used in this article to describe the configuration of the feeding device are based on gravity and therefore on the height of the feeding device.

[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 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] As used herein, the term "distributor" refers to a device capable of distributing, i.e., finely dispersing, liquids and / or gases as they pass through it. Preferably, the distributor is a distribution plate that distributes liquids downwards and vapors upwards. Attached Figure Description

[0025] Figure 1 A schematic diagram of the most common embodiment of the feeding device according to the present invention is shown. It should be understood that this schematic diagram does not reflect the actual dimensions of the feeding device. The same applies to the remaining figures.

[0026] Figure 2 shows a schematic diagram of the feeding device according to the invention, illustrating a preferred embodiment with regard to introducing a circulating liquid flow into the feeding container. Thus, the figure shows an embodiment (2a) involving an inlet suitable for injection, another embodiment (2b) involving a gas distributor and a liquid distributor, and a third embodiment (2c) in which a second inlet is located at the absorber.

[0027] Figure 3 This is a schematic diagram illustrating an embodiment of the feeding device according to FIG2 of the present invention, which incorporates embodiments 2a and 2b.

[0028] Figure 4 shows a schematic diagram of the feeding device according to the invention, illustrating a preferred embodiment with regard to introducing a circulating vapor stream into the feeding container. Thus, an embodiment (4a) involving a metering tube and another embodiment (4b) involving a gas distributor are shown.

[0029] Figure 5 A schematic diagram of the most preferred embodiment of the feeding device according to the present invention is shown, which incorporates... Figure 3 and Figure 4a Features of the illustrated embodiment.

[0030] Figure 6 A schematic diagram of the polymerization reactor of the present invention, including a feeding device, is shown to indicate the position of the feeding container in the overall reactor feeding system.

[0031] Figure 7 It shows the use of according to Figure 1 A schematic diagram of the most common embodiment of the method of the present invention for a feeding device. Reference numerals given in italics and enclosed in parentheses indicate steps provided for the method.

[0032] Figure Labels

[0033] 1. Feed container

[0034] 2. Top area

[0035] 3. Bottom area

[0036] 4. Feed Inlet / Outlet

[0037] 5. Waste export

[0038] 6 First heat exchanger

[0039] 7 Absorbers

[0040] 8 First Entrance

[0041] 9 Second Entrance

[0042] 10 Third Entrance

[0043] 11 First Distributor

[0044] 12 Second Distributor

[0045] 13 Metering tube

[0046] 14 Third Distributor

[0047] 15 pumps

[0048] 16 Polymerization reactor

[0049] 17 Fourth Entrance

[0050] 18 Second heat exchanger

[0051] 19 Fifth Entrance

[0052] 20 Sixth Entrance

[0053] a feed flow

[0054] b Waste vapor stream

[0055] c Fresh liquid flow

[0056] fresh liquid flow in contact with c1

[0057] d circulating liquid flow

[0058] Circulating liquid flow in contact with d1

[0059] e-circulating vapor flow

[0060] e1 contact circulating vapor flow

[0061] f Comonomer Flow

[0062] g Single-unit flow

[0063] h Hydrogen gas flow Detailed Implementation

[0064] Feeding device

[0065] This invention provides a feeding device for preparing a feed stream (a) for solution polymerization (see reference). Figure 1 ), including a feed container (1), the feed container (1) comprising:

[0066] - Top region (2) and bottom region (3);

[0067] - Feed outlet (4), which is used to draw the feed stream (a), wherein the feed outlet (4) is located in the bottom region (3);

[0068] - Waste outlet (5), which is used to extract waste vapor stream (b), wherein the waste outlet (5) is located in the top region (2);

[0069] - First heat exchanger (6), which is located below the top region (2);

[0070] - Absorber (7), which is positioned below the first heat exchanger (6);

[0071] - First inlet (8), which is used to direct fresh liquid flow (c) to the absorber (7) or the top of the absorber (7), wherein the first inlet (8) is located at the absorber (7);

[0072] - A second inlet (9) for introducing a circulating liquid flow (d), wherein the second inlet (9) is located below the first inlet (8); and

[0073] - A third inlet (10) is used to introduce a circulating steam flow (e), wherein the third inlet (10) is located below the second inlet (10) and above the feed outlet (4).

[0074] Preferably, the first heat exchanger (6) of the feeding device of the present invention is positioned such that at least a portion of the waste vapor stream (b) passing through the first heat exchanger (6) is condensed and returned to the absorber (7). Therefore, with reference to the flow direction of the vapor in the feed container (1), the heat exchanger (7) is preferably positioned downstream of the first inlet (8), downstream of the absorber (7), and upstream of the waste outlet (4). In such a configuration, the first heat exchanger (6) can be adjusted to selectively condense and return only volatile components (e.g., unreacted reactants) that should be reintroduced into the feed stream (a). It should be understood that while the heat exchanger is preferably part of the feed container (1), such an arrangement is not necessarily required. Therefore, in an alternative embodiment, the first heat exchanger (6) can be positioned outside the feed container (1) and connected to it to receive the waste vapor stream (b) and return the condensed waste vapor stream to the feed container (1).

[0075] Optionally and preferably, the feeding device of the present invention further includes a second heat exchanger (not shown). This second heat exchanger is positioned upstream of the fresh liquid stream (c) relative to the flow direction of the fresh liquid stream (c). This heat exchanger can be used to cool the fresh liquid stream (c) before it enters the absorber (7) to support the removal and discharge of less volatile reactants along with the waste vapor stream (b).

[0076] Preferably, the absorber (3) is a packed bed absorber.

[0077] Furthermore, according to the present invention Figure 2aIn a preferred embodiment, the second inlet (9) further includes an ejector device configured to inject the circulating liquid stream (d) into the feed container (1). The effect of the ejection by the ejector device is to form a gas / liquid system with a very high phase separation surface in a very short time, wherein the liquid portion of the system is the circulating liquid stream (d). As a subsequent effect of the formation of the system, the volatile components contained in the circulating liquid stream are released and move toward the top region (2) of the feed container (1). Furthermore, as another subsequent effect, the condensate portion of the circulating liquid stream is finely dispersed and moves downward toward the bottom region (3) of the feed container (1). Given that the volatile components contained in the circulating vapor stream (e) rise counter-currently from the third inlet (10) to the top region (2) of the feed container (1), this fine dispersion makes the liquid more absorbent.

[0078] According to Figure 2b In a preferred embodiment of the invention, the feed container (1) further includes a second distributor (12) positioned below the second inlet (9) and above the third inlet (10). This also ensures that the liquid contained in the circulating liquid stream (d) forms a liquid spray, causing the liquid in the circulating liquid stream (b) to fall in a highly dispersed manner within the feed container (1). As a result, at least a portion of the volatile components in the circulating liquid stream is released and moves along the flow direction toward the top region (2) of the feed container (1). These volatile components may include hydrogen, inert gases, volatile impurities, and volatile reactants. Furthermore, the feed device is configured to ensure that the volatile components released from the circulating liquid stream pass through the absorber (3). Figure 2b In the preferred embodiment, the feed container (1) may further include a first distributor (11) positioned above the second inlet (9) and below the absorber (7). This arrangement ensures that the gas evaporating from the liquid spray and the gas in the circulating vapor stream moving upward to the top region (2) are agitated, thereby maximizing contact with the liquid in the downward-moving fresh liquid stream (c). This also has the advantage of allowing conditions to be adjusted so that only specific components (e.g., reactants) are absorbed (i.e. dissolved) in the fresh solvent of the fresh liquid stream (c) and / or the liquid in the circulating liquid stream (d). Generally, pressure and temperature are chosen to enable the removal of volatile compounds. However, the feed locations of the fresh and circulating streams can maximize the absorption of relatively heavy components.

[0079] Even more preferably, the features of these two preferred embodiments can be combined, that is, the injector device of the second inlet (9) can be combined with the first distributor (11) and the second distributor (12), as follows: Figure 3As described. Preferably, metal packing can be added between the first and second distributors. The combination of the two distributors and the metal packing forms an absorber.

[0080] The fundamental feature of this invention is that the fresh liquid stream (c) is directly introduced into or to the top of the absorber (7). In this way, the fresh liquid in the fresh liquid stream (c) and the volatile components evaporated from the circulating liquid stream (d) and the circulating vapor stream (e) come into contact in the absorber (7). This has the advantage of maximizing contact within the absorber (7) and allows for the adjustment of conditions within the absorber (7) so that only specific components, such as reactants, are absorbed (i.e. dissolved) in the fresh liquid of the fresh liquid stream (c). This adjustment is more readily found by maximizing contact between the volatile components and the fresh liquid.

[0081] Therefore, in preferred embodiments 2a and 2b, the second inlet (9) is located below the absorber (7) and above the third inlet (10). However, in the present invention... Figure 2c In another alternative preferred embodiment, the second inlet (9) is located at the absorber (7), and even more preferably below the first inlet (8). Thus, in such a preferred embodiment, contact with the fresh liquid in the fresh liquid flow (c) occurs entirely within the absorber. The gas and liquid flows exiting the absorber at the top and bottom are then finely distributed back into the absorber (7) by the gas distributor and liquid distributor, respectively.

[0082] It should be understood that, preferably, the circulating liquid stream in the polymerization process is drawn from the circulation section, and more preferably, it is extracted from the circulation section into which the feed stream is fed in the polymerization process. The circulation section of such a solution polymerization process typically consists of one or more flash separators that separate the mixture drawn from the reactor into one or more polymer-rich liquid streams and one or more polymer-lean vapor streams, typically including unreacted reactants, solvents, inert gases, and volatile impurities. The vapor streams are preferably further separated into at least one liquid stream and at least one vapor stream. Thus, the circulation section provides at least one circulating liquid stream and one circulating vapor stream, which is introduced into the feed device of the present invention as disclosed above. However, this stream may still contain unreacted reactants, which can be recycled back into the polymerization process.

[0083] Therefore, the feeding device of the present invention further includes a third inlet (10) positioned below the second inlet (9) and above the feed outlet (4) for introducing the circulating vapor stream (e). In this way, the volatile components of the circulating vapor stream (e) move upward to the top region (2), thereby passing through and contacting the liquid components of the fresh liquid stream (c) and the circulating liquid stream (d). This allows for the selective dissolution of reactants from the circulating vapor stream (e) and their reintroduction into the feed stream (a).

[0084] According to Figure 4a In a preferred embodiment, a third inlet (10) is located in the bottom region (3) and includes a metering tube (13) extending into the bottom region (3) of the feed container (1). Most preferably, such a metering tube may be a dispensing tube, which preferably has the same length as the diameter of the feed container (1) and has orifices thereon. It should be understood that the bottom region (3) is configured to contain the liquid phase of the feed flow (a). This is indicated by a wavy line in the figure. Therefore, in Figure 4a In a preferred embodiment, the metering tube is configured to extend in the liquid phase of the feed stream (a). Therefore, the circulating vapor stream (e) passing through the metering tube is not only finely dispersed and agitated, but also forced to traverse the liquid in the bottom region. The effect of this is that, due to the significantly increased surface area of ​​the liquid / gas, volatile components most readily soluble in the liquid (e.g., reactants) are first dissolved in the feed stream liquid. Furthermore, this embodiment has the advantage that the circulating vapor stream (e) is agitated, and therefore, the contact with the circulating liquid stream (d) is also improved. The advantage of contacting the circulating vapor stream (e) with the circulating liquid stream (d) is that the reactants in the circulating vapor stream (e) may have already dissolved in the circulating liquid stream (d). Since the vapor of the circulating vapor stream (e) and the volatile components evaporating from the circulating liquid stream (d) follow the same path, the vapor and volatile components are also directed to the absorber (7) or the top of the absorber (7). Therefore, a common advantage of introducing the circulating vapor stream (e) into the feed vessel (1) is similar to the advantage of guiding volatile components evaporating in the circulating liquid stream (d) through an absorber (7) that provides a fresh liquid stream (c): since the contact between the circulating vapor stream (e) and the fresh liquid stream (c) is maximized within the absorber (7), the conditions within the absorber (7) can be adjusted so that only specific components (e.g., reactants) are absorbed (i.e. dissolved) in the fresh solvent of the fresh solvent stream (c). Furthermore, another common advantage is that such an arrangement allows reactants to be circulated from both the circulating liquid stream (d) and the circulating vapor stream (e).

[0085] According to the present invention Figure 4bIn another preferred embodiment of the feeding device, the feeding container (1) includes a third distributor (14) positioned above the third inlet (10) and below the second inlet (9). This measure ensures that the circulating steam flow (e) is agitated and improves the contact between the circulating steam flow (e) and the liquid from the fresh liquid flow (c) and the circulating liquid flow (d).

[0086] Preferably, the feeding device of the present invention further includes a storage container for storing the feed stream (a), which is positioned downstream of the feed outlet (4). The advantage of the storage container is that it ensures that the feed stream (a) does not run dry, and that the polymerization reactor can be continuously and reliably replenished with the feed stream.

[0087] Preferably, the feeding device of the present invention includes further means for preparing the feed stream (a). Generally, in addition to the recirculation aspect, the feed stream (a) may need to be enriched with certain reactants, and if necessary, also with hydrogen. Furthermore, the state of the stream may need to be adjusted before it enters the polymerization reactor. Therefore, as Figure 6 As shown, the feeding device of the present invention preferably further includes a pump (15), which is positioned downstream of the feed outlet (4) of the feed container (1) with reference to the flow direction of the feed flow (a). Such a pump ensures that the pressure of the feed flow can be adjusted to the pressure at which the polymerization reactor (16; not part of the feeding device) is operated.

[0088] Furthermore, the feeding device of the present invention preferably further includes at least one fourth inlet (17) for introducing at least one comonomer stream (f) into the feed stream (a), wherein, with reference to the flow direction of the feed stream (c), the at least one fourth inlet (17) is positioned downstream of the feed outlet (4), preferably downstream of the pump (15). It has been found that the comonomer can also be incorporated as part of the fresh liquid stream (c). This is particularly preferred if the comonomer has the same or a higher boiling point than the solvent used.

[0089] Preferably, the feeding device of the present invention further includes at least one third heat exchanger (18), which is positioned downstream of the feed outlet (4) with reference to the flow direction of the feed flow (a). Preferably, the pump (15) is positioned upstream of the at least one third heat exchanger (18) with reference to the flow direction of the feed flow (a).

[0090] Also preferably, the feeding device of the present invention further includes at least one fifth inlet (19) for introducing monomers (preferably acetylene or propylene) into the feed stream (a), the fifth inlet (19) being positioned downstream of the feed outlet (4) with reference to the flow direction of the feed stream (a). Preferably, with reference to the flow direction of the feed stream (a), the fifth inlet (19) is positioned upstream of the pump (15) and downstream of the at least one third heat exchanger (18).

[0091] More preferably, the feeding device of the present invention further includes at least one sixth inlet (20) for introducing hydrogen into the feed stream (a), and with reference to the flow direction of the feed stream (a), the sixth inlet (20) is preferably located downstream of at least the third heat exchanger (18).

[0092] Conventional method of the present invention

[0093] Generally, the feeding method of the present invention is connected to a solution polymerization method. First, the feeding method provides a feed stream to the solution polymerization method. Second, preferably, the feeding method is used to circulate the streams (liquid stream and vapor stream) extracted from the solution polymerization method. More preferably, the two solution polymerization methods (i.e., the method in which the feed stream is fed in and the method in which the circulating stream is extracted) are the same solution polymerization method. Therefore, the solution polymerization method should be described as follows.

[0094] Solution polymerization method

[0095] Preferably, the present invention is applicable to supercritical polymerization methods, solution polymerization methods, and advanced solution polymerization methods. More preferably, it is applicable to continuous supercritical polymerization methods, continuous solution polymerization methods, and continuous advanced solution polymerization methods. Most preferably, the production method includes a continuous solution polymerization method.

[0096] The polymer produced in this invention can be any polymer, and its production uses volatile compounds. Preferably, the polymer produced in this invention is an olefin homopolymer or copolymer. More preferably, the monomer of such polymer is selected from α-olefins having 2 to 4 carbon atoms, preferably from ethylene, propylene, and 1-butene, and most preferably from ethylene. Most preferably, the polymer is a polyethylene copolymer or homopolymer.

[0097] When the polymer is a copolymer, the comonomer 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 comonomer 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-butene and 1-octene being the most preferred.

[0098] In the most preferred embodiment, the polymer is produced using the solution polymerization method disclosed below.

[0099] Polymerization typically occurs 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, comonomers. Therefore, the polymerization catalyst can be a Ziegler-Natta catalyst disclosed in EP-A-280352, EP-A-280353, and EP-A-286148, or it can be 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, such as post-transition metal catalysts, can also be used.

[0100] In solution polymerization, a solvent is also present. The solvent is in a liquid or supercritical state during polymerization. Hydrocarbon solvents are typically and preferably used. The liquid hydrocarbon solvent used is preferably C24-24 ... 5-12- Hydrocarbons, which can be unsubstituted or carbon-substituted. 1-4 Alkyl groups (e.g., pentane, methylpentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, and hydrogenated naphtha) are substituted. More preferably, unsubstituted C4 groups are used. 6-10- Hydrocarbon solvents, preferably unsubstituted C424 ... 5-7- Hydrocarbon solvents.

[0101] 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 polymerization. The use of different antifouling compounds is also known in the art. Furthermore, different types of activity promoters or activity retarders can be used to control the activity of the catalyst.

[0102] Typically, in the stream drawn from the polymerization reactor, which contains solvent, polymer, and unreacted monomers and optional comonomers, the polymer content is 10 wt% to 35 wt%, preferably 12.5 wt% to 30 wt%, and more preferably 15 wt% to 25 wt%.

[0103] Similarly, typically, more than 20% of the total flow drawn from the reactor is further recycled (i.e. fed into) to the downstream separation section, preferably more than 40%, and most preferably more than 60%.

[0104] The stream is fed into a separation section. In such a separation section, the polymer-containing stream is typically separated into a polymer-rich condensate phase and a polymer-lean vapor phase by the aid of one or more flash separators. The vapor phase, comprising volatile reactants, inert gases, hydrogen, and volatile impurities, is then separated into a circulating liquid stream and a circulating vapor stream. In the feeding method according to the invention, this circulating liquid stream and circulating vapor stream are fed as described below.

[0105] Feeding method

[0106] The present invention further provides a method for preparing a feed stream for solution polymerization, the feed stream comprising at least one solvent, at least one reactant, and optionally hydrogen, an inert gas, and / or impurities, the method comprising the following steps:

[0107] (i) providing at least one fresh liquid stream (c), said at least one fresh liquid stream (c) comprising at least one solvent and optionally at least one reactant;

[0108] (ii) Providing at least one circulating liquid stream (d), said at least one circulating liquid stream (d) comprising at least one solvent and at least one reactant;

[0109] (iii) Providing at least one circulating vapor stream (e), said at least one circulating vapor stream (e) comprising said at least one reactant;

[0110] (iv) Contact the at least one circulating vapor flow (e) with the at least one circulating liquid flow (d) to create a contacting circulating liquid flow (d1) and a contacting circulating vapor flow (e1);

[0111] (v) The contacting circulating vapor stream (e1) is contacted with the at least one fresh liquid stream to generate a contacting fresh liquid stream (c1) and a waste vapor stream (b);

[0112] (vi) The fresh liquid flow (c1) in contact is combined with the circulating liquid flow (d1) in contact to generate a feed flow (a);

[0113] (vii) Extract the waste vapor stream (b);

[0114] (viii) Extract the feed stream (a).

[0115] As described prior to the feed device, the step of releasing the volatile components provided by the separation section of the aforementioned polymerization process from the circulating liquid stream (d) and contacting the fresh liquid stream (c) with these evaporated components has a surprising effect: unwanted volatile components (e.g., inert gases, hydrogen, or volatile impurities) in the circulating liquid stream (d) can be removed and discharged from the stream, while desired volatile components (e.g., reactants) in the circulating liquid stream (d) can be recombined in the feed stream (a), thereby enabling the recovery of these desired components in the polymerization process without the disadvantage of not being able to control the amount of inert gases, hydrogen, and / or volatile impurities in the process.

[0116] To ensure optimal evaporation of volatile components in the circulating liquid stream, the method of the present invention preferably further includes the step of distributing the circulating liquid stream (a). As described in the description of the feeding device, this can preferably be achieved using a distributor (12) or an injector device.

[0117] The method of the present invention further includes the step of providing a vapor circulation stream (e). This vapor circulation stream (e) currently flows countercurrently to the fresh liquid stream (c) and the circulating liquid stream (d). This contact between the circulating vapor stream and the fresh liquid stream (c) and the circulating liquid stream (d) has a surprising effect: unwanted volatile components (e.g., inert gases, hydrogen, or volatile impurities) in the circulating vapor stream (e) can be additionally removed from and discharged from said stream, while desired volatile components (e.g., reactants) in the circulating vapor stream (e) can be recombined in the feed stream (a), thereby allowing these desired components to be recovered in the polymerization process without the disadvantage of not being able to control the amount of inert gases, hydrogen, and / or volatile impurities in the process.

[0118] Even more preferably, the vapor circulating stream (e) is further distributed using a metering tube or gas distributor before it comes into contact with the fresh liquid stream (c) and / or the circulating liquid stream (d). Most preferably, the circulating vapor stream (e) is brought into contact with the liquid in the bottom region. As previously mentioned, this is most preferably achieved by a metering tube (13) extending into the liquid in the bottom region of the feed device. As explained in the paragraph concerning the feed device, the advantage of this distribution is that it also allows more of the desired volatile components (e.g., unreacted reactants) from the circulating vapor stream (e) to come into contact with the fresh liquid stream (c) so as to selectively absorb (i.e. dissolve) the desired volatile components (e.g., unreacted reactants) and recycle them into the feed stream (a).

[0119] In another preferred embodiment of the invention, the method further includes a step of intermediate storage of the feed stream (a) in a storage container. This configuration ensures that the feed stream is buffered and that the polymerization reactor is continuously and reliably replenished with the feed stream.

[0120] Furthermore, according to the method of the invention, the most preferred embodiment further includes the step of using a first heat exchanger (6) to at least partially generate a condensate vapor stream (b) and reintroducing the condensate vapor stream into the top region. This configuration further enhances the method's ability to selectively remove unwanted volatile components from the circulating stream and selectively recycle unreacted reactants back into the polymerization reactor.

[0121] Preferably, the method according to the invention further includes the step of at least partially cooling the fresh liquid stream using a second heat exchanger before the inlet (8). Cooling can affect the feeding method and the temperature in the feeding device. Therefore, cooling affects the driving force for the absorption of several components.

[0122] In the method of the present invention, it is preferable that the feed stream (a) is further treated before entering the polymerization reactor. Therefore, it is preferable that the feed stream is compressed to a pressure range of 50 bar to 300 bar before entering the polymerization reactor. Furthermore, it is also preferable that the feed stream is cooled to a temperature range of -50°C to +50°C before entering the polymerization reactor.

[0123] Finally, in a preferred embodiment, the feed stream can be further modified by introducing at least one monomer into the feed stream (a), introducing at least one comonomer into the feed stream (a), and / or introducing hydrogen into the feed stream (a).

[0124] Preferably, the method is carried out in a pressure range of 3 to 8 bar.

Claims

1. A feeding device for preparing a feed stream (a) for solution polymerization, comprising a feed container (1), the feed container (1) comprising: - Top region (2) and bottom region (3); - Feed outlet (4), the feed outlet (4) is used to draw the feed stream (a), wherein the feed outlet (4) is located at the bottom region (3); - Waste outlet (5), said waste outlet (5) is used to extract waste vapor stream (b), said waste outlet (5) is located at said top region (2); - First heat exchanger (6), the first heat exchanger (6) is located below the top region (2); - Absorber (7), which is positioned below the first heat exchanger (6); - First inlet (8), the first inlet (8) is used to direct a fresh liquid flow (c) to the absorber (7) or the top of the absorber (7), wherein the first inlet (8) is located at the absorber (7); - Second inlet (9), the second inlet (9) is used to introduce circulating liquid flow (d), wherein the second inlet (9) is located below the first inlet (8); as well as - A third inlet (10) is used to introduce a circulating steam flow (e), wherein the third inlet (10) is located below the second inlet (9) and above the feed outlet (4).

2. The feeding device according to claim 1, further comprising: - A storage container for storing the feed stream (a), the storage container being positioned downstream of the feed outlet (4).

3. The feeding device according to claim 1, wherein, The second inlet (9) further includes an injector device configured to inject at least one of the circulating liquid flows (d) into the feed container (1).

4. The feeding device according to claim 1, wherein, The feed container (1) further includes a first distributor (11) and a second distributor (12), the first distributor (11) being positioned above the second inlet (9) and the second distributor (12) being positioned below the second inlet (9).

5. The feeding device according to claim 1, wherein the second inlet (9) is located at the absorber (7).

6. The feeding device according to claim 1, wherein the third inlet (10) is located in the bottom region (3), and wherein the third inlet (10) further comprises a metering tube (13) extending into the bottom region (3).

7. The feeding device according to claim 1, wherein the feeding container (1) further includes a third distributor (14) located above the third inlet (10).

8. A solution polymerization reactor assembly, comprising a feed device according to any of the preceding claims.

9. A method for preparing a feed stream (a) for solution polymerization in a feed container (1), said feed stream (a) comprising at least one solvent and at least one reactant, said method comprising the following steps: (i) Providing at least one fresh liquid stream (c), said at least one fresh liquid stream (c) comprising said at least one solvent; (ii) Providing at least one circulating liquid stream (d), said at least one circulating liquid stream (d) comprising said at least one solvent and said at least one reactant; (iii) Providing at least one circulating vapor stream (e), said at least one circulating vapor stream (e) comprising said at least one reactant; (iv) Contact the at least one circulating vapor flow (e) with the at least one circulating liquid flow (d) to create a contacting circulating liquid flow (d1) and a contacting circulating vapor flow (e1). (v) Contact the circulating vapor stream (e1) with the at least one fresh liquid stream (c) to generate a fresh liquid stream (c1) and a waste vapor stream (b). (vi) Combining the contacting fresh liquid flow (c1) with the contacting circulating liquid flow (d1) to generate the feed flow (a). (vii) The waste vapor stream (b) is extracted through the waste outlet (5) located at the top region (2) of the feed container (1); (viii) The feed stream (a) is drawn through the feed outlet (4) located at the bottom region (3) of the feed container (1), wherein In step (i), the at least one fresh liquid flow (c) is provided by a first inlet (8) to the absorber (7) or to the top of the absorber (7), wherein the first inlet (8) is located at the absorber (7). In step (ii), the at least one circulating liquid flow (d) is provided by a second inlet (9), wherein the second inlet (9) is positioned below the first inlet (8). In step (iii), the at least one circulating steam flow (e) is provided by a third inlet (10), wherein the third inlet (10) is positioned below the second inlet (9) and above the feed outlet (4).

10. The method according to claim 9, wherein, When step (vi) is performed, the contacting fresh liquid stream (c1) also comes into contact with the circulating vapor stream (e).

11. The method of claim 9, further comprising the following steps: (ix) Distribute the circulating liquid flow (d) prior to step (iv).

12. The method of claim 9, further comprising the following steps: (x) Distribute the circulating vapor stream (e) prior to step (iv).

13. The method of claim 9, further comprising the following steps: (xi) After step (vii), the feed stream (a) is stored in a storage container.

14. The method of claim 9, further comprising the following steps: (xii) The waste vapor stream (b) is at least partially condensed using the first heat exchanger (6) to produce a condensed waste vapor stream (b1), and the condensed waste vapor stream (b1) is reintroduced in step (v).

15. The method of claim 9, further comprising the following steps: (xiii) The fresh liquid stream is cooled at least partially using a second heat exchanger prior to step (i) (c).

16. The method according to claim 9, wherein, The feed stream (a) also includes hydrogen.

17. The method according to claim 9, wherein, In step (i), the at least one fresh liquid stream (c) further includes the at least one reactant.

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