WO2014202715A1 - Procédé de production d'élastomères epdm en solution, et réacteur de polymérisation pour une utilisation dans ledit procédé - Google Patents

Procédé de production d'élastomères epdm en solution, et réacteur de polymérisation pour une utilisation dans ledit procédé Download PDF

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Publication number
WO2014202715A1
WO2014202715A1 PCT/EP2014/062934 EP2014062934W WO2014202715A1 WO 2014202715 A1 WO2014202715 A1 WO 2014202715A1 EP 2014062934 W EP2014062934 W EP 2014062934W WO 2014202715 A1 WO2014202715 A1 WO 2014202715A1
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reactor
cstr
reaction
fed
reaction bath
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PCT/EP2014/062934
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English (en)
Inventor
Gian Paolo QUADRI
Francesco MICHELETTI
Alessandro Susa
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Fastech S.R.L.
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Priority to CN201480044120.XA priority Critical patent/CN105452314A/zh
Publication of WO2014202715A1 publication Critical patent/WO2014202715A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
    • C08F210/18—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers with non-conjugated dienes, e.g. EPT rubbers

Definitions

  • the present invention relates to a process for the preparation of ethylene-propylene elastomeric copolymers or ethylene-propylene-diene (EPDM) elastomeric terpolymers in solution, and a polymerisation reactor for use in said process.
  • the polymerisation of ethylene and propylene, optionally with a diene, to produce EP(D)M elastomers is typically obtained in the presence of a Ziegler-Natta catalytic system, either of traditional type or using metallocenes.
  • a Ziegler-Natta catalytic system either of traditional type or using metallocenes.
  • Conventional Ziegler-Natta (Z/N) systems comprising vanadium compounds, which are soluble in hydrocarbon solvents and consequently form an essentially homogeneous system, have been widely used. Elastomeric polymers obtained with these catalysts contain little or no crystalline homopolymer fraction.
  • the vanadium compounds most commonly used are vanadium oxytrichloride VOCI 3 , vanadium tetrachloride VCI 4 , and vanadium triacetylacetonate V(ACAC) 3 .
  • the Z/N catalytic system also comprises an aluminium alkyl as a co-catalyst, such as diethyl aluminium chloride, or ethylaluminium sesquichloride.
  • the molecular weight of the EP(D)M copolymer or terpolymer is controlled by means of the use of chain transfer agents, typically hydrogen or diethyl zinc.
  • the monomers, the catalytic system and the molecular weight regulator, and any other component in the mixture are fed into a polymerisation reactor.
  • a solvent of the resulting polymer usually a saturated hydrocarbon such as hexane, is fed into the polymerisation reactor.
  • the polymerisation process usually takes place within a temperature range of 10-70°C and is exothermic, so the heat released by the reaction has to be removed.
  • EP(D)M The reaction involved in the production of EP(D)M is one of the most complex currently known polymerisation processes.
  • the production of EP(D)M entails the reaction of three monomers having a very different reactivity, a multi-component catalytic system and molecular weight regulator, such as hydrogen that, being a very lightweight gas, is very difficult to distribute evenly through the reaction solution.
  • the reaction solution is highly viscous because of the dissolved polymer.
  • EP(D)M can be produced for various applications, including more than twenty different types of polymer, each of which must comply with very strict specifications i n terms of composition, acceptability ranges, molecular weight, and molecular weight distribution.
  • the polymerisation reactions and the related control methods must consequently be such that they ensure a perfect reproducibility of the reaction conditions and their stability in time and space.
  • the polymerisation reaction is obtained with equipment and procedures that make it difficult to ensure that the reaction medium remains homogeneous in time and space, and it is consequently difficult to control the reaction itself.
  • multiple reactors, connected in series or in parallel, are widely used, into which the raw materials and catalyst are fed from above and/or below, at distinctly lower temperatures than that of the reagent, thus making it difficult to distribute them evenly within the polymeric solution (which is highly viscous) and to achieve uniform temperature conditions in said solution.
  • a very important factor for proper polymerisation concerns the elimination of the heat of polymerisation, which is commonly dissipated by means of a heat exchange through the metal wall that creates a temperature gradient in the reaction tank between the centre of the reactor and the refrigerated wall. This can cause fouling phenomena on the wails, however, with a consequent loss of productivity of the reactor and an impaired temperature control.
  • the energy consumption for dissipating the heat of the reaction also has an enormous influence on the energy balance of the polymerisation reactor, which is translated into a higher cost in economic terms for the production of EP(D)M elastomers in solution.
  • US2008/0207852 Al describes a solution polymerisation process involving several stages for the production of ethylene- a- olefin copolymers in two reactors in series.
  • the heat released by the polymerisation reaction is dissipated using two different methods, with a cooling jacket installed on the reactor, and with a cooling method that relies on the latent heat of evaporation (vaporisation) of the solvent and of the monomers (see paragraph [0035]).
  • the examples provide no information on which cooling method is preferable, or on which the process is mainly based.
  • This type of process has several drawbacks, however, including: the use of several reactors connected in series, which makes it difficult to control the polymerisation reaction in order to guarantee a homogeneous reaction medium; the use of a cooling jacket or wall, which demands a high temperature difference between the reaction bath and the cooling wall or, in other words, a rather low wail temperature. Because the solubility of the EP(D)M produced is lower at lower temperatures, this leads to the formation of elastomer deposits on the reactor wall, which can reduce the quality of the product and make it necessary to frequently interrupt production to remove them. In addition, the use of these cooling systems is costly both in energy terms and in economic terms in order to obtain a cooling jacket capable of regulating the temperature adequately.
  • WO 2012/156393 Al describes a solution process for the production of EPDM in a continuous stirred-tank reactor (CSTR), in which the reaction bath is kept boiling at a temperature between 40°C and 60°C, and a pressure between 6 and 13 bar, and in which from 40% to 80% of the heat of the reaction is dissipated by the boiling of the reaction bath, while the remaining heat is removed by means of the subcooling of the fluids recycled to the reactor.
  • the reactor is equipped with a stirring system with three impellers, a device for distributing the recycled fluids to the bottom of the reactor, and a gamma ray level control device.
  • the object of the present invention is a solution process for the production of EP(D)M elastomers that enables the production of the elastomer to be optimised by taking action on the reaction parameters so as to ensure an efficient and reproducible control of the reaction involved and reduce the process management costs.
  • Another object of the present invention is a solution process for the production of EP(D)M elastomers in which the energy consumption for controlling the temperature and pressure parameters is considerably reduced.
  • a further object of the present invention is a plant for the production of EP(D)M elastomers in solution that enables the costs of managing said plant to be reduced while maintaining a high quality of the polymer produced, and that enables the use of less extreme compression and refrigeration systems, that are consequently easier to maintain and demand lower investment costs.
  • EP(D)M elastomers comprising:
  • a monomer polymerisation reaction step in which ethylene, propylene, optionally a diene, the catalytic system, hydrogen and a hydrocarbon solvent for said EP(D)M elastomers, are fed continuously into a stirred reactor (CSTR) with the formation of a reaction bath in which the EP(D)M elastomer is dissolved in said hydrocarbon solvent, and wherein said reaction bath is maintained in a boiling condition at a temperature from 40° to 70°C, and at a pressure from 8 to 15 barg, such that the partial vaporisation of said reaction bath occurs;
  • CSTR stirred reactor
  • a degassing step wherein the solution containing the EP(D)M elastomer and the unreacted monomers drawn from said CSTR stirred reactor, is fed to a distillation column in which said unreacted monomers are separated from the solution containing the polymer; said unreacted monomers are removed from said distillation column, compressed to a pressure ranging from 18 to 22 barg, cooled to a temperature lower than the temperature of said reaction bath, and fed to said stirred reactor (CSTR), characterized in that:
  • vapours formed by the partial vaporisation of said reaction bath in said reaction step and a liquid stream of said hydrocarbon solvent are fed to an absorption column and placed in contact in a countercurrent therein, whereby said vapours are absorbed in said solvent;
  • said hydrocarbon solvent in which the vapours are absorbed according to item (i) is drawn from said absorption column, subjected to a first cooling stage in a water heat exchanger, sent to a second cooling stage in a subcooler and fed to said CSTR stirred reactor at a temperature lower than the temperature of said reaction bath.
  • the un eacted monomers of said degassing step and a liquid stream of said hydrocarbon solvent are fed to an absorption column and placed in contact therein, so as to cause an absorption of said unreacted monomers in said solvent.
  • the hydrocarbon solvent in which the unreacted monomers are absorbed as explained above is drawn from said absorption column, submitted to a first cooling stage in a water heat exchanger, sent to a second cooling stage in a subcooler, and then fed to said stirred reactor (CSTR) at a temperature lower than the temperature of said reaction bath.
  • CSTR stirred reactor
  • subcooler is used, according to the present invention, to mean a heat exchanger that uses a fluid coming from a refrigeration cycle as the cooling medium. This makes it possible to reduce the quantity of heat that the subcooler must remove from the vapours being recycled because the absorption column and the subsequent cooling stage in the water heat exchanger contribute to dissipating a part of the heat. With this phase of the process, the consumption of the subcooler is consequently reduced, and also the total cost of managing the polymerisation process.
  • vapours formed by the partial vaporisation of the reaction bath are preferably submitted to partial condensation in a water condenser located upstream from the inlet to the absorption column.
  • the vapours thus undergo a first cooling action that contributes to reducing the consumption of the subcooler, further reducing the process management costs.
  • vapours formed by the partial vaporisation of the reaction bath are preferably compressed with a compression ratio in the range of 1.3- 1.6 before they are fed to said absorption column. This makes it possible to recycle the vapours, which are subsequently condensed, inside the stirred reactor (CSTR) without altering the pressure conditions of the reaction, while maintaining a stable and efficient polymerisation reaction.
  • CSTR stirred reactor
  • the vapours leaving from the top of the absorption column are preferably compressed with a compression ratio in the range of 1.3- 1.6, submitted to partial condensation in a water condenser, cooled to a temperature lower than the temperature of said reaction bath and fed into said stirred reactor (CSTR). This makes it possible to recycle the gases leaving the absorption column and feed them back into the stirred reactor (CSTR) without altering the pressure balances involved in the polymerisation reaction.
  • the hydrocarbon solvent for the EP(D)M in which the vapours are absorbed is preferably fed into the bottom, of the reactor. In this way, the balances of the reaction inside the stirred reactor (CSTR) remain unaffected, and the vapours used to remove the reaction heat from the reaction bath can be fully recycled.
  • Said absorption column preferably contains a packing material. This makes it possible to obtain an optimal absorption of the solvent vapours and enables a significant recycling of the unreacted monomers contained in the vapours formed by the partial vaporisation of the reaction bath.
  • the flow rate of the vapours formed by the partial vaporisation of the reaction bath is preferably proportional to the productivity of the reactor and it is recorded, processed and used to control the flow rates of the monomers, solvent and catalyst fed into the reactor. This makes it possible to achieve an optimal control of the reaction parameters, while keeping the reaction stable and efficient for the purposes of optimising the polymerisation process.
  • a further aspect of the present invention concerns a plant for the production of
  • EP(D)M elastomers in solution characterised in that it comprises:
  • CSTR stirred reactor
  • said reactor comprising an upper portion and a lower portion, said upper portion having a diameter greater than the diameter of said lower portion, and the height of said upper portion being less than the height of said lower portion;
  • an absorption column for the absorption of said monomers contained in the vapours formed by the partial vaporization of the reaction bath in the stirred reactor (CSTR) in a hydrocarbon solvent for said EP(D)M elastomers, equipped with a packing material and located downstream from said reactor; iv. a water heat exchanger placed downstream from said absorption column;
  • the plant for the production of EP(D)M elastomers in solution preferably comprises an absorption column located downstream from said distillation column for the absorption of said unreacted monomers in the hydrocarbon solvent, and a water heat exchanger located downstream, from said absorption column.
  • the plant for the production of EP(D)M elastomers in solution preferably comprises a water condenser located downstream from the stirred reactor (CSTR) and upstream from the absorption column. This makes it possible to reduce the load on the subcooler located upstream from the stirred reactor, and to obtain an energy saving and a consequent economic saving.
  • CSTR stirred reactor
  • the plant for the production of EP(D)M elastomers in solution preferably comprises a compressor located downstream from the stirred reactor (CSTR) and upstream from the absorption column. This makes it possible to feed the recycled fluids directly back into the reactor, reducing the energy consumption for the compression stage without reducing the output of the polymerisation process or modifying the reaction parameters.
  • CSTR stirred reactor
  • the stirred reactor (CSTR) of the polymerisation section of the plant for the production of EP(D)M elastomers has an upper portion with a larger diameter than the diameter of the lower portion, and the height of said upper portion is lower than the height of said lower portion.
  • the ratio between said diameter of the upper portion and said diameter of the lower portion is between 1 and 2.
  • Figure 1 shows a simplified layout of the process according to the known state of the art.
  • Figure 2 shows a simplified layout of the process according to the present invention in a first embodiment.
  • Figure 3 shows a simplified layout of the process according to the present invention in a second embodiment.
  • Figure 4 shows a simplified layout of the process according to the present invention in a third embodiment.
  • Figure 5 shows a simplified layout of the process according to the present invention in a fourth embodiment.
  • Figure 6 shows a simplified layout of the process according to the present invention in a fifth embodiment.
  • Figure 7 shows a schematic cross-sectional view of the CSTR reactor in a particular embodiment according to the present invention.
  • Figure 8 is a diagram illustrating the energy consumption of the process in the various embodiments compared with the consumption of the process according to the known state of the art.
  • the diene used in the process for the production of EP(D)M elastomers according to the invention is a non-conjugated diene chosen from the group comprising: ethyl idene norbornene (ENB), vinyl norbornene (VNB), dicyclopentadiene (DCPD) and 1,4-hexadiene ( HD ).
  • the diene is typically contained in the EPDM polymer in a quantity below 12% by weight.
  • Ft hy I idene norbornene (ENB) is the preferred diene.
  • the process according to the invention comprises a polymerisation reaction stage conducted in a CSTR stirred reactor, where the monomers are polymerised to produce the EP(D)M elastomer, and a degassing stage, where the unreacted monomers are separated from the polymer solution emerging from the bottom of the polymerisation reactor.
  • the process according to the invention is characterised in the polymerisation reaction stage by an innovative method for removing the heat of the polymerisation reaction achieved by means of a combination of partial vaporisation of the bath and the use of subcooled fluids recycled to the reactor.
  • the partial vaporisation is obtained by keeping the bath in a boiling condition at a temperature in the range of 40° to 70°C and a pressure in the range of 8 to 15 barg.
  • the quantity of heat dissipated with the vaporisation is in the range of 30% to 80% of the total heat of the reaction.
  • the heat dissipated with the vaporisation is preferably in the range of 35% to 60% of the total heat of the reaction.
  • the term 'subcooling' is used here to mean the operation of cooling each of the fluids to be recycled in the reactor to a temperature lower than the temperature of the reaction bath, i.e. below 40-70°C.
  • the fluids recycled at said temperature are called 'subcooled fluids' .
  • the quantity of heat dissipated by feeding the subcooled fluids to the reactor is between 70% and 20% of the total heat released by the reaction.
  • the heat dissipated by this method is preferably in the range of 65% to 40% of the total heat of the reaction.
  • the recycled fluids, l ike the fresh reagents used i n the reaction are subcooled by means of a subcooler. As mentioned previously, the subcooler has a high energy consumption that considerably influences the polymerisation process management costs.
  • the polymerisation reaction is completed in a boiling liquid so that the temperature is the same in every part of the reactor.
  • the composition of the bath i.e. the concentration of the monomers and of the molecular weight regulator in the solvent
  • the pressure at which the liquid boils and the composition of the gaseous phase produced by the partial vaporisation of the solution are also established.
  • the heat released by the polymerisation reaction varies according to the type of EP(D)M elastomer being produced, but averages approximately 700 kcal/kg. Exact values of the heat of the reaction are known to a person skilled in the art.
  • the latent heat of vaporisation depends on the composition of the liquid phase, and averages approximately 70 kcal/kg.
  • the exact values of the latent heat of vaporisation can be calculated by a person skilled in the art. Since the ratio between the heat of polymerisation and the heat of vaporisation is approximately 10 to 1, if all the heat of polymerisation were to be removed by boiling the reaction bath, 1 kg of elastomer produced would cause the vaporisation of approximately 10 kg of liquid from the reaction bath.
  • each kilogram of elastomer produced generates 700 kcal, 350 of which are removed by subcooling, and 350 are dissipated by the vaporisation of 5 kg of liquid.
  • the instrument for measuring the temperature and flow rate of each raw material fed to the reactor e.g. ethylene, propylene, diene, solvent, hydrogen, catalyst;
  • the monomers, solvents, catalyst and molecular weight regulator e.g. hydrogen
  • the monomers, solvents, catalyst and molecular weight regulator e.g. hydrogen
  • the catalyst is fed to one side of the reactor 10, diluted in additional solvent, and therefore bypasses the subcooler 20.
  • the polymerisation process takes place inside the reactor 10, stirred by variable- speed, multiple-impeller stirring means, and the reactor contains means for controlling the level, pressure and composition of the vapours that develop from the partial vaporisation of the reaction bath.
  • the working pressure is in the range of 8 to 15 barg, while the temperature range is preferably between 50° and 60°C, depending on the degree of polymerisation to be obtained.
  • the reaction takes place in a liquid phase, approximately in equilibrium with the vapour phase.
  • the stirring action and the arrangement of the reactor inlets are designed to ensure a temperature as evenly distributed as possible and an equilibrium between the liquid and the gaseous phases.
  • the heat of the exothermic polymerisation reaction generates a partial evaporation of the reaction bath, which contributes to dissipating the heat released and to keeping the reaction stable and homogeneous.
  • vapours formed by the partial vaporisation of the reaction bath emerge from the top of the reactor and are partially condensed in a condenser 11 that uses water as a refrigerant.
  • the condensed liquid consisting of solvent and un reacted monomers, is sent to the subcooler 20, cooled to a temperature lower than that of the reaction bath and recycled to the reactor 10.
  • the uncondensed flow is sent to the intake of a compressor 12, e.g. an oil-free single-stage screw compressor.
  • This compression has the dual purpose of compensating for the pressure drops in the flow consisting of solvents and unreacted monomers being recycled to the reactor, and also of facilitating heat dissipation and improving the absorption of monomers in the solvent, as explained below.
  • the flow of compressed vapours is sent to an absorption column 30, and fed into the bottom thereof, while a flow of solvent is fed into the top of said column.
  • the countercurrent contact between the flow of vapours and the flow of solvent causes the absorption of the vapours into the solvent.
  • the fluid leaving the bottom of the absorption column 30 thus contains the solvent and a part of the unreacted monomers previously contained in the flow of compressed vapours.
  • the absorption column 30 contains a packing material that increases its contact surface area, thereby increasing the absorption efficiency of the column.
  • vapours not absorbed in the absorption column 30 emerge from the top of the column and undergo partial condensation in a condenser 32 that uses water as a cooling fluid.
  • the resulting condensate is sent to the subcooler 20, cooled to a temperature lower than that of the reaction bath and recycled to the reactor 10 after being mixed with other recycled fluids and with fresh reagents. Part of the uncondensed vapours are drained off, while the majority is recycled to the reactor 10 together with the condensate.
  • the liquid leaving the absorption column is thus submitted to a first cooling stage in a heat exchanger 31 that uses water as a refrigerant.
  • the cooled liquid gas consisting of solvent and unreacted monomers, is partly recirculated to the top of the same column, and partly mixed with other recycled fluids and sent to the subcooler 20, where it is cooled to a temperature lower than that of the reaction bath and recycled to the reactor 10.
  • the second phase of the process for the production of EP(D)M elastomers i.e. the degassing phase
  • the degassing phase has the purpose of separating the lightweight unreacted monomers (ethylene, propylene) that are dissolved in fairly high quantities (of the order of 10,000 kg/h ) in the polymer solution emerging from the bottom of the polymerisation reactor. These monomers are recovered by distillation and then compressed and recycled to the reactor. The degassing operation takes place as explained below.
  • the polymer solution collected from the reactor is fed continuously to a distillation column 40, in which the lightweight unreacted monomers are separated at the top of the column.
  • the heat required is provided by a reboiler 42.
  • the column 40 contains segmental perforated plates (or other types of special plate, e.g. 'disc & doughnut') that enable a highly viscous fluid such as the polymer solution to be treated.
  • the working conditions of the column 40 are as follows:
  • the product at the top containing the lightweight monomers (ethylene, propylene) and part of the solvent, undergoes partial condensation in a condenser 41 that uses water as a refrigerant, and recycled to the reactor that operates at a pressure below 15 barg.
  • a three- stage compressor 43 is used for this purpose, fitted with intermediate partial water condensers (not shown in the figure) and a final partial condenser (E-DEGFIN), that uses water as a refrigerant.
  • the final compression pressure is approximately 20 barg.
  • Both the condensed fluid and the uncondensed fluid have sufficient pressure to be sent to the subcooler 20, cooled to a temperature below that of the reaction bath, and recycled to the reactor 10, after being mixed with fresh monomers and fluids coming from the recycling of the previous stages.
  • the polymer solution emerging from the bottom of the degassing column 40, and containing polymer, most of the solvent and the unreacted heavy monomer (diene ). is sent for subsequent processing by means of a pump.
  • the content of lightweight monomers in the solution is mini mal (of the order of 10 kg/h ) and consequently allowable without any need for further recovery.
  • the degassing stage of the process for the production of EP(D)M elastomers as illustrated schematically in Figure 3, comprises an absorption column 50 located between the first and second compression stages 43. After undergoing a first cycle of condensation and compression, the fluid emerging from the top of the distillation column is fed to the bottom of an absorption column 50. while a flow of solvent is fed to the top of said column. The countercurrent contact causes the absorption of the lightweight monomers in the solvent. The liquid emerging from the bottom of the absorption column 50 thus contains solvent and a part of the lightweight un eacted monomers previously contained in the fluid emerging from the distillation column.
  • the absorption column 50 contains a packing material.
  • the liquid leaving the absorption column is submitted to a first cooling stage in a heat exchanger 51, that uses water as a refrigerant.
  • a part of the cooled liquid, consisting of solvent and lightweight unreacted monomers, is recirculated to the top of the same column 50, and a part is sent to the top of the absorption column 30 in the first stage of the process, where it may be mixed with fresh solvent before being added to the column.
  • Said liquid thus becomes the liquid in which the unreacted monomers contained in the vapours formed by the partial vaporisation of the reaction bath are absorbed.
  • the inclusion of the absorption column 50 in the degassing phase thus achieves a reduction in the load on the second and third compression stages 43.
  • the polymerisation reaction phase of the process for the production of EP(D)M elastomers illustrated schematically in Figure 4 differs from the layout shown in Figure 2 as regards the relative positions of the temperature-regulating compressor 12 in relation to the absorption column 30, and the omission of the condenser 11 at the outlet for the vapours at the top of the reactor 10.
  • the compressor C-TH is positioned downstream from the absorption column 30 and upstream from the condenser 32. This enables a reduction in the energy consumption for cooling the vapours and, at the same time, it enables the pressure conditions inside the system to be kept stable so that the recycled fluids can be fed back into the reactor. This solution also enables a reduction in the flow rate to the compressor 12 by comparison with the standard situation.
  • the polymerisation reaction phase of the process for the production of EP(D)M elastomers as shown schematically in Figure 5 differs from the layout illustrated in Figure 2 as regards the relative position of the temperature-regulating compressor 12 in relation to the absorption column 30, which is downstream from the absorption column 30 and upstream from the condenser 32.
  • the energy consumption for cooling the vapours while an adequate pressure of the recycled fluid is nonetheless maintained.
  • This solution also enables a reduction in the flow rate to the compressor 12 by comparison with the standard situation.
  • the polymerisation reaction phase in the process for the production of EP(D)M elastomers as illustrated schematically in Figure 6 differs from the layout shown in Figure 2 as regards the omission of the condenser 11 at the outlet for the vapours at the top of the reactor 10.
  • the diagram in Figure 8 shows the energy consumptions (shown on the x-axis) as a function of the hourly output of polymer (on the y-axis) of different configurations of the process according to the present invention by comparison with the energy consumptions of a process according to the known state of the art.
  • the energy consumptions of the process according to the known state of the art are higher than the energy consumptions achieved with a process according to the present invention.
  • the energy consumption in a process where there is an absorption column, with a corresponding water condenser, only in the polymerisation reaction phase is clearly significantly lower than the energy consumption involved in a process according to the known state of the art.
  • the layout of the process in which there is an absorption column in both the reaction stage and the degassing stage (the layout shown in Figure 3), there is a further reduction in the total energy consumption needed to produce the same amount of EP(D)M elastomer.
  • the process for the production of EP(D)M elastomers according to the present invention can be implemented in a plant comprising a first polymerisation section comprising a subcooler 20, i.e. a heat exchanger that uses as a refrigerant a flow coming from a cooling cycle in which the previously puri fied reagents coming from supply lines are cooled to CSTR a temperature below that of the reaction bath.
  • a stirred reactor 10 Downstream from the subcooler there is a stirred reactor 10, with stirring means 103 comprising multiple impellers 104, and a distributor of the incoming streams 105 located in the vicinity of the bottom of said reactor.
  • a condenser 1 1 that uses water as a refrigerant is positioned downstream from the stirred reactor 10 for the purpose of recovering and condensing the vapours formed by the partial evaporation of the reaction bath.
  • the condensate coming from the condenser 11 downstream from the reactor is fed back through recycling lines 21 into the reactor 10, after cooling in the subcooler 20 located upstream from the reactor 10.
  • a compressor 12 preferably a single-stage screw dry compressor (oil-free), compresses the uncondensed vapours in the condenser located downstream from the reactor 10 and feeds them into the bottom of an absorption column 30.
  • a flow of reaction solvent is fed into the top of the absorption column 30, generating a countercurrent flow between the vapours and the solvent.
  • the absorption column 30 preferably contains a packing material.
  • a heat exchanger 31 that uses water as a refrigerant and is located downstream from the absorption column 30, is fed with the liquid emerging from the bottom of the absorption column 30 and contributes to reducing the temperature of said liquid by dissipating the heat of absorption.
  • the cooled liquid is partly recirculated to the top of the absorption column 30 and partly recycled through lines 31 to the reactor 10, after cooling in the subcooler 20 located upstream from the reactor 10.
  • a condenser 32 that uses water as a refrigerant is located downstream from the absorption column 30 for the purpose of recovering and condensing the unabsorbed vapours emerging from the top of the absorption column 30.
  • the condensed vapours are sent back through recycling lines 21 to the reactor 10 after cooling in the subcooler 20 located upstream from the reactor 10.
  • the uncondensed vapours are partly recycled together with the condensate and partly drained off through a drainage line 33.
  • the plant according to the present invention also comprises a degassing section located downstream from the CSTR stirred reactor 10, in which a distillation column 40, preferably with segmental perforated plates (or other types of special plate, e.g. disc & doughnut) is fed with the liquid coming from the reactor 10.
  • the liquid is fed into the top of the distillation column 40, and the heat needed to achieve the separation inside the column is provided by a reboiler 42.
  • the liquid leaving the bottom of the distillation column 40 is sent to subsequent processing stages, while the vapours coming from the top of the column 40 are compressed by a three- stage compressor 43 with intermediate condensers 41 and a final water condenser 44.
  • the liquid obtained from the condensation and compression of the gases coming from the top of the column 40 is sent back through recycling lines 22 to the reactor 10 after cooling in the subcooler 20 located upstream from the reactor 10.
  • the degassing section of the plant for the production of EP(D)M elastomers is complete with an absorption column 50 located downstream from the first condensing and compression cycle performed on the gases emerging from the top of the distillation column 40.
  • the flow coming from the first compression stage is fed to the bottom of the absorption column 50, while a flow of reaction solvent is fed into the top of the absorption column, thus generating a countercurrent flow.
  • the absorption column 50 preferably contains a packing material.
  • the liquid emerging from the bottom of the absorption column is fed to a heat exchanger 51 that uses water as a refrigerant, and then partly recycled to the top of the column 40 and partly sent to the top of the absorption column i n the polymerisation section by means of supply lines.
  • a condenser 44 that uses water as a refrigerant is provided downstream from the absorption column 40 in order to recover and condense the unabsorbed gases coming from the top of the absorption column 40.
  • the condensed gases are fed back through recycling lines 22 into the reactor 10, after cooling in the subcooier 20 located upstream from the reactor 10.
  • the uncondensed gases are partly recycled to the reactor together with the condensed fraction and partly drained off through a drainage line 45.
  • the CSTR stirred reactor 10 is shaped such that the upper portion 101 of the reactor 10 is wider, as shown in Figure 7. More precisely, the upper portion 101 has a larger diameter than the diameter of the lower portion 102. The height of the upper portion 101 is lower than the height of the lower portion 102. In particular, the ratio between the diameter of the upper portion and the diameter of the lower portion is in the range of 1 to 2.
  • the reactor is complete with stirring means 103 with multiple impellers 104 and a toroidal distributor 105 of the incoming streams.
  • the shape of the reactor 10, combined with the stirring means 103 and the toroidal distributor 105, enables a better mixing of the incoming fluids, particularly thanks to the narrower diameter of the lower portion of the reactor.
  • the wider top of the reactor reduces the entrainment of reaction fluid by the vapours that emerge from the top of the reactor thanks to a reduction in the flow rate of the vapour induced by said wider diameter. This avoids fouling phenomena in the circuit at the outlet from the top of the reactor, and consequently reduces the plant servicing and management costs.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Polymerisation Methods In General (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Graft Or Block Polymers (AREA)

Abstract

La présente invention porte sur un procédé de préparation de copolymères élastomères éthylène-propylène ou de terpolymères élastomères éthylène-propylène-diène EP(D)M en solution, et sur un réacteur de polymérisation pour utilisation dans ledit procédé. En particulier, le procédé comprend : une étape de réaction de polymérisation de monomères dans laquelle de l'éthylène, du propylène, en option un diène, un système catalytique, de l'hydrogène et un solvant hydrocarboné pour lesdits élastomères EP(D)M sont introduits en continu dans un réacteur muni d'un agitateur (CSTR) avec formation d'un bain réactionnel dans lequel l'élastomère EP(D)M est dissous dans ledit solvant hydrocarboné ; ledit bain réactionnel est maintenu à ébullition à une température comprise dans la plage de 40 à 70°C et sous une pression comprise dans la plage de 8 à 15 barg, de façon qu'ait lieu une vaporisation partielle dudit bain réactionnel ; dans une étape de dégazage, la solution contenant l'élastomère EP(D)M et les monomères n'ayant pas réagi, sortant dudit réacteur muni d'un agitateur CSTR, est introduite dans une colonne de distillation, dans laquelle lesdits monomères n'ayant pas réagi sont séparés de la solution contenant le polymère ; lesdits monomères n'ayant pas réagi sont soutirés de ladite colonne de distillation, comprimés sous une pression comprise dans la plage de 18 à 22 barg, refroidis à une température inférieure à la température dudit bain réactionnel, et recyclés vers ledit réacteur muni d'un agitateur (CSTR). Pendant ce procédé, les vapeurs formées par la vaporisation partielle dudit bain réactionnel dans ladite phase de réaction, et un courant liquide dudit solvant hydrocarboné, sont envoyés à une colonne d'absorption et y sont placés en contact à contre-courant, de façon à induire une absorption desdites vapeurs par ledit solvant. Ledit hydrocarbure par lequel les vapeurs ont été absorbées comme expliqué ci-dessus est soutiré de ladite colonne d'absorption, soumis à une première étape de refroidissement dans un échangeur de chaleur de l'eau, puis à une deuxième étape de refroidissement dans un sous-refroidisseur, puis envoyé audit réacteur muni d'un agitateur (CSTR) à une température inférieure à la température dudit bain réactionnel.
PCT/EP2014/062934 2013-06-21 2014-06-19 Procédé de production d'élastomères epdm en solution, et réacteur de polymérisation pour une utilisation dans ledit procédé WO2014202715A1 (fr)

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IT001035A ITMI20131035A1 (it) 2013-06-21 2013-06-21 Processo in soluzione per la produzione di elastomeri epdm e reattore di polimerizzazione per l'uso in detto processo
ITMI2013A001035 2013-06-21

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Cited By (3)

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Publication number Priority date Publication date Assignee Title
WO2017069446A1 (fr) * 2015-10-19 2017-04-27 주식회사 엘지화학 Procédé de séparation d'un réactif d'oligomérisation de l'éthylène
WO2022207551A1 (fr) * 2021-03-29 2022-10-06 Arlanxeo Netherlands B.V. Procédé de production de polymères
WO2023217397A1 (fr) * 2022-05-09 2023-11-16 Arlanxeo Netherlands B.V. Procédé de production de polymères

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US3969470A (en) * 1975-04-21 1976-07-13 E. I. Du Pont De Nemours And Company Process for recycling hydrogen when making blends of olefin copolymers
US5326855A (en) * 1983-10-06 1994-07-05 Henry Kahn Process for the manufacture of elastomers in particulate form
WO1996033227A1 (fr) * 1995-04-21 1996-10-24 Exxon Chemical Patents Inc. PROCEDE DE POLYMERISATION D'UNE SOLUTION DE POLYMERES D'ETHYLENE-α-OLEFINE/DIOLEFINE
US20080207852A1 (en) 2007-01-31 2008-08-28 Sumitomo Chemical Company, Limited Process for producing ethylene -alpha- olefin copolymer
WO2011087728A2 (fr) * 2010-01-14 2011-07-21 Exxonmobil Chemical Patents Inc. Procédés et appareils pour réaliser une polymérisation en solution en continu
WO2012156393A1 (fr) 2011-05-16 2012-11-22 Fastech S.R.L. Procédé en solution pour la production d'élastomères ep(d)m et réacteur de polymérisation destiné à être utilisé dans ledit procédé

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US3969470A (en) * 1975-04-21 1976-07-13 E. I. Du Pont De Nemours And Company Process for recycling hydrogen when making blends of olefin copolymers
US5326855A (en) * 1983-10-06 1994-07-05 Henry Kahn Process for the manufacture of elastomers in particulate form
WO1996033227A1 (fr) * 1995-04-21 1996-10-24 Exxon Chemical Patents Inc. PROCEDE DE POLYMERISATION D'UNE SOLUTION DE POLYMERES D'ETHYLENE-α-OLEFINE/DIOLEFINE
US20080207852A1 (en) 2007-01-31 2008-08-28 Sumitomo Chemical Company, Limited Process for producing ethylene -alpha- olefin copolymer
WO2011087728A2 (fr) * 2010-01-14 2011-07-21 Exxonmobil Chemical Patents Inc. Procédés et appareils pour réaliser une polymérisation en solution en continu
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017069446A1 (fr) * 2015-10-19 2017-04-27 주식회사 엘지화학 Procédé de séparation d'un réactif d'oligomérisation de l'éthylène
US10066031B1 (en) 2015-10-19 2018-09-04 Lg Chem, Ltd. Method of separating ethylene oligomerization reactor effluent
WO2022207551A1 (fr) * 2021-03-29 2022-10-06 Arlanxeo Netherlands B.V. Procédé de production de polymères
WO2023217397A1 (fr) * 2022-05-09 2023-11-16 Arlanxeo Netherlands B.V. Procédé de production de polymères

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ITMI20131035A1 (it) 2014-12-22

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