BRPI0314322B1 - CONTINUOUS SUSPENSION POLYMERIZATION PROCESS IN A TUBULAR CYCLE REACTOR - Google Patents

Description

POLYMERIZATION PROCESS IN CONTINUOUS SUSPENSION IN A

TUBULAR CYCLE REACTOR

RELATED REQUESTS:

This application claims the benefit under 35 U. S. C. § 119 (e) of U.S. Provisional Patent Application number 60 / 411,612 (application 612 ”) filed on September 17, 2002. Application 612 is incorporated herein by reference.

FIELD OF THE INVENTION:

This invention relates to the suspension polymerization in a liquid medium. More particularly, the invention relates to an improved pumping apparatus and processes for a large volume cycle reactor used for suspension polymerization.

BACKGROUND OF THE INVENTION:

Polyolefins like polyethylene and polypropylene can be prepared by particle formation polymerization also known as suspension polymerization. In this technique, the feed materials such as monomer and catalyst are fed into a cycle reactor and a product suspension containing solid polyolefin particles in a liquid medium is removed from the reactor.

In a cycle polymerization operation, a fluid suspension circulates through the cycle reactor using one or more pumps, typically axial flow pumps having thrusters disposed inside the reactor. The pumps provide the driving force for the circulation of the fluid suspension. As the volume of the reactor and the concentration of solids in the fluid suspension increase, the demand for the pumps also increases. In general, the flow rate, pressure, density and viscosity of the

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2/34 fluid suspension must be considered when selecting and operating the cycle reactor pumps.

Suspension polymerization in a cycle reactor zone proved to be commercially successful. The suspension polymerization technique has achieved international success with billions of pounds of olefin polymers being produced this way annually. However, it is still desirable to design and build larger reactors. The size of a reactor has a significant impact on the requirements of the pump, particularly with regard to height (differential pressure through the pump impeller, expressed in meters of liquid) and flow (velocity multiplied by the pipe cross-sectional area , expressed in liters per minute) developed by the pump.

Until quite recently, fluid suspensions of olefin polymers in a diluent were limited to relatively low concentrations of reactor solids. Sedimentation tubes were used to concentrate the suspension to be removed, so that at the exit of the sedimentation tubes the suspension would have a higher concentration of solids. As the name suggests, sedimentation occurs in the sedimentation tubes to increase the concentration of solids in the suspension to be removed.

In addition to the suspension concentration, another factor that affects the concentration of solids in the reactor is the circulation speed of the fluid suspension. A higher suspension speed for a given reactor diameter leads to more solids, since the suspension speed affects limiting factors such as heat transfer and reactor clogging due to polymer build-up

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3/34 in the reactor.

By increasing the height and the flow capacity of the cycle reactor circulation pump (s), a greater percentage of solids weight can be circulated in the reactor. Using two pumps in series can allow the pumping height capacity to be doubled and the resulting increase in solids. The two pumps may be located in different segments of the reactor and it may be desirable that each pump be dedicated to an equivalent number of tubes.

BRIEF SUMMARY OF THE INVENTION:

A cycle reactor apparatus may comprise a plurality of vertical segments, a plurality of upper horizontal segments and a plurality of lower horizontal segments. Each of the vertical segments is connected, at an upper end, to one of the upper horizontal segments and is connected, at a lower end, to one of the lower horizontal segments. The vertical and horizontal segments form a continuous flow route adapted to carry a fluid suspension. The cycle reactor apparatus may also include at least two pumps to transmit driving force to the fluid suspension inside the reactor. Each pump is operationally connected to a propellant arranged on the continuous flow route. Two thrusters are facing each other and fire in opposite directions and the two thrusters are spaced sufficiently so that one of the thrusters benefits from the rotational energy of the other thruster. The cycle reactor apparatus also includes means for introducing an olefin monomer into the

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4/34 continuous flow; means for introducing a diluent into the continuous flow path; means for introducing a polymerization catalyst into the continuous flow path and means for removing a portion of a fluid suspension from the continuous flow path.

A cycle reactor apparatus may comprise a plurality of larger segments and a plurality of smaller segments. Each smaller segment connects two of the larger segments to each other, where the larger and 10 smaller segments form a continuous flow route. The cycle reactor apparatus also includes a monomer feed attached to one of the segments, a catalyst feed attached to one of the segments and a product outlet attached to one of the segments. The cycle reactor apparatus also includes a pump against the current and a pump in the direction of the current, where the pumps are each fixed to a propellant arranged inside the continuous flow route. The pumps are arranged so that the propellers rotate in opposite directions and are close enough that the rotational energy transmitted by the pump against the current is at least partially recovered by the pump in the current direction. The thrusters are located in at least an enlarged section of one of the segments. The enlarged section and the thrusters having diameters greater than 25 the diameter of the segments.

Both cycle reactor devices can also include two thrusters and are arranged in the same horizontal segment. In addition, a portion of the continuous flow path against the current of at least one of the 30 thrusters can accommodate at least one guide fin arranged

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5/34 to transmit rotary motion in a direction opposite to the rotary motion of the thruster.

A cycle reactor apparatus may comprise a plurality of larger segments and a plurality of 5 smaller segments. Each smaller segment connects two of the larger segments to each other, where the larger and smaller segments form a continuous flow route. The cycle reactor apparatus also includes a monomer feed attached to one of the segments, a catalyst feed 10 attached to one of the segments and a product outlet attached to one of the segments. The cycle reactor apparatus also includes at least one guide vane arranged within the continuous flow path and a pump towards the current of the guide vane. The pump is attached to a thruster 15 disposed within the flow path and the thruster is also in the direction of the guide fin chain. The guide vane and the propellant transmit rotational movement to the flow path in opposite directions and are close enough so that the suspension is absorbed in the rotational movement when using the current direction pump.

A cycle reactor apparatus may comprise a tubular cycle reactor adapted to conduct an olefin polymerization process comprising polymerizing at least one olefin monomer into a liquid diluent to produce a fluid suspension comprising liquid diluent and solid olefin polymer particles. . The cycle reactor apparatus may also comprise a monomer feed attached to the tubular cycle reactor, a catalyst feed attached to the tubular cycle reactor, a product outlet attached to the cycle reactor

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6/34 tubular and at least one mixed flow pump disposed inside the tubular cycle reactor.

Any of these cycle reactor devices can have a thruster located in an enlarged section of one of the lower or smaller horizontal segments. The extended section and the thrusters have diameters larger than the diameter of the lower horizontal segments. Generally, each thruster will have a diameter larger than the average diameter of the segments.

A suspension polymerization process may include introducing a monomer, diluent and catalyst into a cycle reactor, polymerizing the monomer to form a suspension comprising the diluent and solid polyolefin particles, circulating the suspension using two propellants, transmitting a first rotational motion to the suspension with a first thruster and transmit a second rotational motion to the suspension with a second thruster. In the improved process, the second rotational movement is opposite to the first rotational movement. The process may further include pre-centrifuging the suspension against the current of the first thruster, in a direction opposite to the first rotational movement of the thruster of the first thruster. The process may also include post-centrifuging the suspension in the current direction of the second pump to recover the centrifugal movement of the second pump propellant and converting it into flow and height in the axial direction of the pump.

A cycle suspension polymerization process may comprise introducing monomer, diluent and catalyst into a cycle reactor, polymerizing the monomer

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7/34 to form a suspension comprising the diluent and solid polyolefin particles, circulate the suspension using at least one propellant, transmitting a first rotational motion to the suspension before the suspension reaches the propellant (s) and transmitting a second rotational movement to the suspension with the propellant (s). In the improved process, the second rotational movement is in the opposite direction to the first rotational movement. The first rotational movement is desirably transmitted through the pre-centrifugation fins.

In any of these cycle suspension polymerization processes, the space between at least one propellant and a portion of the cycle reactor can be minimized by housing the propellant. In the improved process, the suspension may have a minimum desired concentration of the solid polyolefin particles, for example, at least about 45% by weight. The suspension can be circulated at a flow of about 75,708.24 liters per minute to about 378,541.18 liters per minute. The thrusters alone or together can reach a height of about 36.58 meters to about 182.88 meters.

BRIEF DESCRIPTION OF THE DRAWINGS:

Figure 1 shows a state of the art cycle reactor and a polymer recovery system.

Figure 2 is a cross-sectional view of the propulsion mechanism.

Figure 3 shows a cycle reactor having two pumps arranged to make better use of rotational energy.

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Figure 4 is a close-up view of the arrangement of the two pumps in Figure 3.

Figure 5 shows the cycle reactor with guide fins.

Figure 6 is a different view of the guide fins.

DETAILED DESCRIPTION OF THE INVENTION:

The present process and apparatus are applicable to any cycle reaction zone comprising a suspension of polymer solids in a liquid medium, including suspensions employed in olefin polymerization processes. In particular, the present process and apparatus are applied to large volume cycle reactors in which a fluid suspension having a high concentration of solids is circulated.

As used herein, the term "suspension" refers to a composition in which solids and liquids are present in separate phases. The term fluid suspension ”refers to the suspension comprising polymeric solids and liquid medium circulating in a cycle reaction zone. The solids can include catalyst and a polymerized olefin, such as polyethylene.

The liquid medium can include an inert diluent, such as isobutane, with monomer, comonomer, molecular weight control agents, such as hydrogen, antistatic agents, anti-encrusting agents, dissolved purgers and other process additives.

Alternatively, the liquid medium can be formed, mainly, of unreacted monomer, as in some propylene polymerization processes. The term product suspension ”refers to the portion of the suspension removed from the cycle reaction zone to recover the polyolefin product.

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It is not easy to design and build a single pump that is capable of providing the height and flow capacities necessary for a large volume cycle reactor for suspension polymerization, particularly if suspension 5 will have a high concentration of solids. Higher height and flow capacities are desirable as they allow the reactor to operate at higher solids concentrations. A higher concentration of solids has several advantages. For example, a higher solids concentration in the reactor generally means that less diluent will be removed as part of the product suspension. Also, a higher concentration of solids can increase the yield of the polymer over a period of time (or increase the residence time of the polymer in the same production range, thereby increasing the efficiency of the catalyst).

In US Patent No. 6.23 9,235, which is incorporated herein by reference, some of the present inventors disclose a process and an apparatus in which a pump of 20 high solids and a continuous outlet attachment enabled significant increases in the concentrations of solids inside the reactor . Concentrations of more than 40% by weight are possible according to this process and apparatus. (Throughout this Order, the weight of catalyst is ignored since productivity, particularly with chromium oxide on silica, is extremely high).

The present process and apparatus are suitable for circulating a fluid suspension having a minimum solids concentration of at least 45% by weight, alternatively 30 at least 46% by weight, alternatively at least 47% by weight.

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10/34 weight, alternatively at least 48% by weight, alternatively at least 49% by weight, alternatively at least 50% by weight, alternatively at least 51% by weight, alternatively at least 52% by weight, alternatively at least 53% by weight, alternatively at least 54% by weight, alternatively at least 55% by weight, alternatively at least 56% by weight, alternatively at least 57% by weight, alternatively at least 58% by weight, alternatively at least 59% by 10 alternatively at least 60% by weight. The process and apparatus are also suitable for circulating a fluid suspension having a maximum solids concentration of a maximum of 75% by weight, alternatively a maximum of 74% by weight, a maximum of 73% by weight, a maximum of 72% by weight, 15 in maximum 71% by weight, maximum 70% by weight, maximum 69% by weight, maximum 68% by weight, maximum 67% by weight, maximum 66% by weight, maximum 65% by weight, maximum 64% by weight, maximum 63% by weight, maximum 62% by weight, maximum 61% by weight. The aforementioned minima and maximums can be absolute minima and maximums, or they can be minima and maximums of the average solids concentration. Any minimum amount and any maximum amount of solids concentration, as specified above, can be combined to define a concentration range of 25 solids, namely that the selected minimum is less than the selected maximum. In some situations, the aforementioned weight percentages may be approximate.

The present processes and devices are suitable for homopolymerization of ethylene and copolymerization of 30 ethylene and a superior 1-olefin such as butene, 1-pentene, 1

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11/34 hexene, 1-octene or 1-decene. A preferred process is copolymerization of ethylene and, as a starting material, an amount of comonomer in the range of 0.01% to 10% by weight, preferably from 0.01% to 5% by weight, more preferably 0.1 % to 4% by weight, where the comonomer is selected from the aforementioned upper 1-olefins and the percentage by weight is based on the total weight of ethylene and comonomer. Alternatively, sufficient comonomer can be used as a starting material to provide a resulting product polyolefin having an incorporated amount of comonomer in the range of 0.01% to 10%, preferably 0.01% to 5%, more preferably 0 , 1% to 4% by weight. Such copolymers are still considered polyethylene.

Diluents suitable for use as the liquid medium in the present invention are well known in the art and include hydrocarbons that are inert and liquid under suspension polymerization conditions. Suitable hydrocarbons include isobutane, propane, n-pentane, i-pentane, neopentane and n-hexane, with isobutane being especially preferred.

In addition, the present invention can be employed where the unreacted monomer is the liquid medium for polymerization. For example, the present techniques can be used for the polymerization of propylene, where propylene is the liquid medium and an inert diluent is not present in any substantial amount. A diluent can also be used for the catalyst. For illustration, but not as a limitation, the present invention will be described in connection with a polyethylene process using an inert diluent as the liquid medium, but it should

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It should be understood that the present invention can also be employed where the monomer is used as the liquid medium and would replace the diluent in the following descriptions.

Suitable catalysts are also well known in the art. Chromium oxide in a support such as silica is particularly suitable, as widely disclosed, for example, in U.S. Patent No. 2,825,721, which is incorporated herein by reference. The reference here to silica supports should also encompass any known support containing silica, for example, silica-alumina, silica-titania and silica-alumina-titania. Any other known support, such as aluminum phosphate, can also be used. The invention is also applicable to polymerizations using organometallic catalysts, including those frequently called in the art of Ziegler catalysts and metallocene catalysts.

Additional details regarding cycle reactor apparatus and polymerization processes can be found, for example, in U.S. Patent Nos. 4,674,290; 5,183,866; 5,455,314; 5,565,174; 6,045,661;

6,051,631; 6,114,501; and 6,262,191, which are incorporated herein can be referred to.

The pumps are used for suspension polymerization in a cycle reactor to provide the driving force for circulating the fluid suspension containing solid polymer particles in a diluent. Pumps with propellants arranged in the reactor or in the reaction zone can be used. Such axial flow pumps can circulate the fluid suspension at a speed. As the speed of the suspension increases, the

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13/34 heat transfer from the reactor to the cooling liners (or other cooling system) improves and a higher solids level can be circulated. The increased speed of the suspension, however, requires more force supplied by the pump motor, greater height, and more shaft, bearing, seal and propeller force. It is therefore desirable to emphasize the pump's efficiency, construction details and pump specification details. Several available techniques emphasize these points and facilitate the pumping of a large volume of polymerization suspension having a high concentration of solids at a high speed.

First, a dual pump arrangement can be employed, in which the pumps are arranged so that the rotational energy transmitted by the pump against the current is at least partially recovered by the pump in the current direction. For example, two pumps can be arranged in a single horizontal segment or a single smaller segment. Two pumps can be placed on adjacent cycle reactor knees so that the rotational energy transmitted to the suspension by the first pump (the current pump) is partially recovered by the second pump (the current pump) which is rotating its thruster in an opposite direction. This arrangement improves the height and flow of the suspension and, consequently, the pumping efficiency for two pumps in series. Figures 3 and 4 demonstrate this technique. In other situations, the thrusters do not need to be arranged in the same segment, as long as they are close enough so that the thruster in the

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14/34 current direction benefit from the rotational energy of the propellant against the current. In still other situations, substantial benefits can be found by placing the pumps and / or thrusters in an asymmetrical arrangement.

Second, guide fins (also called pre-centrifuge fins or post-centrifuge fins) or other means to passively rotate the suspension, to transmit rotation to the suspension, can be employed. The pre-centrifuge fins can transmit a rotation to the suspension before it reaches the propellant. The guide fins can assign a rotation in the opposite direction of the rotation transmitted by the thruster, so that the pump has an increased relative rotational speed and the suspension has a higher discharge and flow speed. This produces improved pump efficiency. The post-centrifuge fins can transmit a rotation to the suspension after it has passed through the propellant. The transmitted speed of the post-centrifuge fins can be the same or the opposite of the speed transmitted by the propellant, depending on the desired effect. The post-centrifuge fins incorporated in the design of the columns that support a bearing housing or seal for the pump shaft. Also, if there are two or more thrusters on an axis rotating in the same direction, a guide vane can be placed between the thrusters to redirect the rotational movement in the axial or counter-rotation movement to improve efficiency, pump capacity and differential height. bomb. Figure 5 illustrates the positioning of pre-centrifuge fins or guide fins in relation to the

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15/34 pump propellant to practice this technique. Such pre-centrifuge fins can increase the efficiency of the pump by at least 2%, alternatively by at least 3%, alternatively by at least 4%, alternatively by at least 5% 5, alternatively by at least 6%, alternatively by at least least 7%, alternatively at least 8%, alternatively at least 9%, alternatively at least 10%. In some situations, the above values are approximate.

Third, the space between a pump propellant and a reactor tube can be minimized by housing the propellant. The thruster and the reactor wall in which the thruster is arranged (located) defines a space. Minimizing this space reduces backflow from the pump discharge (high pressure) to the suction of the pump (low pressure). This improves the flow and height of the pump. However, a balance must be reached with an increased tendency to break solids into smaller particles or fines. The space may be 0.35 millimeter or less, 0.41 millimeter or less, 0.53 millimeter or less, 0.79 millimeter or less, 1.06 millimeter or less, 1.59 millimeter or below or 3.17 mm or below. The aforementioned space values can be approximate in some situations.

Fourthly, the reactor pump propeller can be produced from aluminum, titanium or steel using the machining manufacturing technique on a 6-axis computer-controlled plunge mill. This allows for fabrication from solid masses of metal that can be selected for failure in advance. This

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16/34 avoids weak propellant segments due to failure and the thickness of a propellant section can be closely controlled to transmit the force necessary to withstand high height and flow requirements to operate a cycle reactor at a high concentration of solids .

Fifth, a pump propellant having a diameter greater than the diameter of the cycle reactor (as shown in Figure 2 here and Figure 8 of U.S. Patent No. 6,239,235) can be employed. For example, for a polyethylene cycle reactor of 60.96 centimeters in diameter, a propellant having a diameter of 66.04 centimeters or more can be used. Alternatively, a propellant having a diameter of

71.12 centimeters or more.

Alternatively, a propellant having a diameter of 76.2 centimeters or more can be used. A polyethylene cycle reactor circulation pump with a speed (RPM) of 180 to

18,000 to reach a reactor circulation pump with a pump height of 36.58 meters at

182.89 meters high and 75,708.23 to 378,541.18

LPM with a polyethylene cycle reactor with a diameter (nominal) of 60.96 centimeters. Other ranges are suitable for cycle reactors of other sizes.

Sixth, a radial flow or mixed flow pump can be used. In a radial or mixed flow pump, the propeller blades transmit a greater amount of speed and energy to the suspension flow when they come into contact with the suspension than conventional axial pumps. In this way, radial or mixed pumps generate greater flow height and speed for better

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17/34 meet the pressure needs of large reactors.

This changes the characteristic of the axial flow pump to one more similar to a typical radial or centrifugal pump, where the fluid flow leaves the propellant in a radial direction after entering the pump in an axial direction. In a mixed flow pump, the fluid flow leaves the propellant with a vector that has both axial and radial components.

this vector can have an angle from 0 degrees to 90 degrees, where degree indicates a vector that leaves the pump in the axial direction and 90 degrees indicates a vector that leaves the pump in the radial direction.

Any or all of the aforementioned techniques can be used in conjunction with a polymerization process that employs continuous outlet, sedimentation tubes, vaporization pipe heater (s), a vaporizer system for separating the polymer diluent by vaporization and direct diluent recycling to the reactor in a new or retrofitted cycle process to produce polyolefin. The present apparatus and process may employ continuous output to obtain an additional increase in the concentration of solids in the reactor, as described in

U. Patent

S. No. 6,239,235, which is incorporated herein by reference.

Alternatively or in addition, the present apparatus and process can employ sedimentation tubes to increase sedimentation efficiency. The term sedimentation efficiency ”is defined as the kilo / hour ratio of polymer taken from a sedimentation tube (or continuous outlet) divided by the total kilo / hour of polymer plus the kilos / hour of isobutane diluent removed during the same time as the the

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18/34 sedimentation tube (or continuous outlet).

Referring now to the figures, Figure 1 shows a typical cycle reactor (10) having vertical segments (12), upper horizontal segments (14) and lower horizontal segments (16). These upper and lower segments (14) and (16) define the upper and lower horizontal flow zones. A thruster is located in the cycle reactor (14) to circulate the suspension. Each vertical segment (12) is connected to another vertical segment through a corresponding horizontal segment (14). The vertical segment (12) can include heat exchange coatings (or cooling coatings) (18). The vertical segments (12) and the horizontal segments (14) define a cycle reaction zone. The cycle reaction zone can include more or less vertical segments (12) and corresponding horizontal segments (14) like those shown in Figure 1. Furthermore, the cycle reaction zone can be oriented vertically or horizontally. Additionally, some or all of the horizontal segments (14) can be curved members that connect the vertical segments. In fact, the connecting segments (14) can have any shape that connects the vertical segments (12) and allows the fluid to flow between them.

The reactor is cooled by means of heat exchangers formed by vertical segments (12) and cooling liners (18). As mentioned above, the higher the speed of the suspension through the pipes (12), the better the heat transfer from the cycle reactor to the cooling liners (18) and consequently a higher concentration of solids in the fluid suspension. Each

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19/34 segment is connected to the next segment by a smooth bend or knee (20), thus providing a continuous flow route substantially free of internal obstructions. The suspension is circulated by means of a propeller (22) (shown in Figure 2) powered by an engine (24). The monomer and the forming diluent are introduced through the pipes (26) and (28), respectively, which can enter the cycle reactor (10) directly in one or in a plurality of locations can be combined with the recycling pipe of condensate diluent (30) as shown. The comonomer can also be introduced into the reactor through these pipes. The monomer and comonomer can be fed into the cycle reactor (10) by any suitable technique, such as a simple opening to the reactor, a nozzle, a sprinkler or other distribution device.

The catalyst is introduced through the catalyst introduction means (32) which provides a (local) zone for catalyst introduction. Any suitable means for introducing catalyst into the cycle reactor can be employed. For example, the process and apparatus disclosed in U.S. Patent No. 6,262,191 (hereby incorporated by reference) for preparing a catalyst sludge and supplying it to a reaction zone (polymerization) can be used with the present process and apparatus.

The elongated hollow attachment for continuous output of an intermediate product suspension is broadly designated by the reference element (34). The continuous exit mechanism (34) is located at or adjacent to one end in the direction of the current of one of the lower horizontal segments (16) and adjacent or on the knee of

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20/34 connection (20). The cycle reactor can have one or more continuous output attachments.

On the device shown in Figure

1, the product suspension is transported through the duct (36) into a high pressure expansion chamber (38). The duct (36) includes a surrounding duct (40), to which a heated fluid is supplied, which provides indirect heating to the suspension material in a vaporization pipe duct (36). The vaporized diluent leaves the expansion chamber (38) through the duct (42) for further processing which includes condensation by simple heat exchange using the recycling condenser (50) and returns to the system, without the need for compression, through the recycled diluent tubing (30). The recycling condenser (50) can use any suitable heat exchange fluid known in the art under any conditions known in the art. However, a fluid at a temperature that can be supplied economically (such as a steam) is generally employed. A suitable temperature range for this heat exchange fluid ranges from 4.44 degrees Celsius to 54.44 degrees Celsius.

The polymer particles are removed from the high pressure expansion chamber (38) through the pipeline (44) for further processing techniques known in the art. They can be transported to the low pressure expansion chamber (46) and recovered there as a polymer product through piping (48). A fluff chamber ”(not shown) can be arranged between the high pressure expansion chamber (38) and the low pressure expansion chamber (46) to facilitate maintenance

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21/34 of the pressure differential between the expansion chambers. The separated diluent is transported through the compressor (47) to a duct (42). This two-stage expansion project is widely reported in Hanson and others, U. S. Patent No. 4,424,341, the disclosure of which is hereby incorporated by reference.

Any number of vertical segments (12) or tubes can be used in addition to the eight illustrated in Figure 1. It is considered that a twelve tube reactor can benefit from the techniques disclosed here. The flow length of the cycle reaction zone is generally greater than 274.32 meters, alternatively greater than 304.80 meters, alternatively greater than 335.28 meters, alternatively greater than 365.76 meters, alternatively greater than 396.24 meters , alternatively greater than 426.72 meters, alternatively greater than 457.20 meters, alternatively greater than 487.68 meters, alternatively greater than 518.16 meters, alternatively greater than 548.64 meters, alternatively greater than 579.12 meters, alternatively greater than 609.60 meters. The aforementioned lengths can be approximated in some situations.

The present process and apparatus are particularly

useful for reactors in 113,562.35 liters or more, alternatively fence in 124,918.59 liters or more, alternatively fence in 132,489.41 liters or more, alternatively fence in 136,274.82 liters or more, alternatively fence in 151,416.47 liters or more, alternatively fence in 158,987.29 liters or more, alternatively fence in 166,558.12 liters or more, alternatively fence in 174,128.76 liters or more,

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alternatively fence in 181,699.76 liters or more, alternatively fence in 189,270.59 liters or more, alternatively fence in 227,124.71 liters or more, alternatively fence in 264,978.82 liters or more, alternatively fence in 302,832.94 liters or more, alternatively fence in 340,687.06 liters or more, alternatively about 378 .541.18 liters or more, why

they can efficiently use pumping equipment to generate superior performance. The aforementioned volumes can be approximated. The present techniques may make it desirable to connect two cycle reactors that were previously separated. Certainly, for a relatively small cost of capital, two 68,137.41 liter reactors can be combined to form a 136,274.82 liter reactor using the same two pumps, but with more than twice the productivity.

The cycle reactor (10) may be operated in such a way as to generate a pressure differential of at least 124.10 KPa, alternatively at least 137.89 KPa, alternatively at least 151.68 KPa, alternatively at least 165.47 KPa, alternatively at least 179.26 KPa, alternatively at least 193.05 KPa, alternatively at least 206.84 KPa between the ends against the current and in the current direction of one or more pumps in a reactor of 60.96 centimeters in nominal diameter . Generally, the cycle reactor (10) is operated in such a way as to generate a height, expressed as a pressure loss per unit length of the reactor of at least 0.07 meter in height of pressure drop suspension per meter in length. reactor for a 60.96 cm reactor

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23/34 of nominal diameter. The reference to a diameter of 60.96 centimeters means an internal diameter of approximately 55.63 centimeters. For larger diameters, a higher suspension speed and a greater pressure drop per unit of reactor length is required. This assumes that the suspension density is generally about 0.5 to 0.6.

A higher pressure or height differential can be achieved using one or more of the techniques disclosed here. For example, differential pressure can be improved by controlling the speed of rotation of the pump impeller, reducing the space between the impeller blades and the inner wall of the pipeline, or by using a more aggressive impeller design. The differential pressure or height can also be increased by using at least one additional pump.

Figure 2 shows the propellant (22) to continuously move the suspension along the flow path. The thruster (22) has the blades (74) and is mounted on the shaft (78) connected to the motor (24). The tubing (21) has a vertical segment (12) and a lower horizontal segment (16) that interconnect at one knee (20). The motor (24) rotates the shaft (78) and thus the blades (74), so that the propeller (22) pushes the suspension in the direction of arrow A towards the knee (20) and upwards in the vertical segment ( 12). As can be seen, the thruster (22) is located in an enlarged section (66) of the pipeline (21) that serves as the thrust zone (70). The enlarged section (66) of the pipe (21) has a larger diameter than the rest of the pipe (21). By way of example only, the diameter of the pipe (21) is 60.96

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24/34 centimeters. By way of example only, the diameter of the enlarged section (66) is greater than 60.96 centimeters. In this way, the propellant (22) has a diameter, measured through the blades (74), which is greater than the diameter of the pipe (21). By way of example only, the diameter of the propellant (22), measured through the blades (74), is greater than 60.96 centimeters. Because the enlarged section (66) allows the use of a propeller larger than the tubing (21), the propellant (22) pushes the suspension at a higher speed through the tubing (21). The higher the thruster (22) also increases the height by increasing the pressure in the discharge suspension. By way of example only, for a 60.96 cm reactor, the largest propellant (22) generates from 75,708.23 to 378,541.18 liters per minute of suspension and 36.58 meters at 182.88 meters in height. Consequently, the larger propellant (22) also creates more heat transfer in the cooling liners (18) (Figure 1) so that the cycle reactor (10) (Figure 1) produces higher levels of solids.

Alternatively, instead of increasing the diameter of the thruster (22), a smaller thruster (22) can be operated at a speed of 180 to 18,000 RPM to reach a height of 36.58 meters at 73.15 meters and a flow from 75,708.23 to 189,270.59 LPM with a 60.96 cm diameter (nominal) cycle reactor.

Figure 3 shows two pumps (100) and (102) positioned at opposite ends of a lower horizontal segment (16) of the pipeline (21). For clarity, another device shown in Figure 1 is omitted, but it would be used in a production polymerization system.

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As shown, pumps (100) and (102) direct the suspension flow in the direction of arrow A through the cycle reactor (10).

Figure 4 shows the two pumps (100) and (102) and the piping (21) in greater detail. The pump (100) includes the propellant (22a), which has the blades (74a) and is mounted on the shaft (78a) connected to a motor (24a). The pump (102) includes the propellant (22b), which has the blades (74b) and is mounted on the shaft (78b) connected to a motor (24b). The pipe (21) has two parallel vertical segments

(12a) and (12b) and a horizontal segment bottom (16), what interconnects the vertical segments (12a) and (12b) we knees (20th) and (20b), respectively. The engine (24a) turns the axis (78a) and consequently the blades (74a) of

thruster (22a) in a first rotational direction and the motor (24b) rotates the shaft (78b) and consequently the blades (74b) of the thruster (22b) in a second opposite rotational direction. By way of example only, the thruster (22a) rotates in a clockwise direction and the thruster (24b) rotates in a counterclockwise direction. The suspension flows through the pipe (21) in the direction of arrow A through the pump (102) and then through the pump (100).

The suspension flows to the propellant (22b), generally parallel to the axis (78b). As the suspension flows through the blades (74b) of the propellant (22b), the blades (74b) discharge the suspension tangentially at angles to the axis (78b), towards the inner wall of the pipe (21). The suspension is discharged in a particular direction at a particular angle depending on the rotational direction of the thruster (22b). The thruster (22a) is

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26/34 positioned close enough to the thruster (22b) so that the suspension is still flowing at tangential angles when the suspension approaches the thruster (22a). The suspension confronts the blades (74a) of the thruster (22a) and, due to the fact that the thruster (22a) rotates in the opposite direction of the rotation of the thruster (22b), it is deflected by the blades (74a) so that the suspension is discharged of the thruster (22b) following the direction of arrow A in an orientation essentially parallel to the axis (78a). Consequently, the thruster (22a) straightens the suspension's steering route and discharges the suspension in an axial alignment essentially parallel to that of the axle (78a). The suspension then flows to the knee (20a) and upwards through the vertical segment (12a). Additionally, due to the fact that the suspension 15 confronts the blades (74a) at an angle, the suspension slides through the angled blades (74a) with reduced resistance.

Due to the fact that the suspension is flowing in an axial alignment generally parallel to the shaft (78a) when being discharged by the thruster (22a), the suspension proceeds at a higher speed after passing through the pump (100) than if the suspension flow through the pump (102) only. The suspension discharged by the pump (102) travels at a slower speed because the suspension flows at angles towards the inner walls of the pipe (21) and is thus deflected and decelerated by the inner wall.

In addition, since the suspension slides through the blades (74a) with less resistance, less power is required by the propellant (22) to confront the suspension. In this way, positioning the two pumps (100) and (102), 30 that rotate in opposite directions, close to each other and in a

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27/34 series, the rotational energy transmitted to the suspension by the pump (102) is partially recovered in the pump (100) so that the suspension flows through the pipe (21) more efficiently and leaves the pump at a higher speed. Thus, the two pumps (100) and (102) produce improved levels of solids.

A two-stage pump could be used as a replacement for the two separate pumps (100) and (102). The two-stage pump includes two thrusters on the same pump that are aligned close together and rotating in opposite directions.

Figure 5 shows a pump (100) and guide fins (114) in the pipeline (21). The guide fins (114) are located against the current from the pump (100) as the suspension flows through the pipe (21) in the direction of arrow A. As such, these guide fins are pre-centrifugation fins. The guide fins (114) extend from the inner wall of the tubing (21) towards the pump (100). All guide fins (114) curve radially inward at the same angle as the inner wall. The suspension approaches the guide fins (114) in the direction of arrow A in a straight orientation generally parallel to the axis (78). As the suspension faces the guide fins (114), the guide fins (114) transmit an angular rotation or centrifugation to the suspension so that the suspension flows towards the inner wall of the pipe (21) at an angle to each other to the shaft (78). Depending on the direction in which the guide fins (114) curve from the inner wall of the pipe (21), the guide fins (114) cause the suspension to rotate in a clockwise or counterclockwise direction. By example

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28/34 only, the guide fins (114) are oriented to create a suspension rotation counterclockwise.

The suspension leaves the guide fins (114) and flows in contact with the propellant (22) at an angle to the axis (78). Preferably, the propellant (22) rotates in the opposite direction of the rotation of the suspension created by the fins (114). The propeller can rotate in the same direction as the suspension rotation created by the guide fins. By way of example only, the thruster (22) rotates counterclockwise. Due to the fact that the suspension confronts the blades (74) at an angle and is rotating in the opposite direction to that of the blades (74), the suspension slides through the angled blades (74) with less resistance than if the suspension flowed through the blades (74) directly.

Thus, the speed of the suspension flowing through the thruster (22) is less impeded by the blades (74) and the rotational speed of the thruster (22) is less hindered by the suspension. In this way, less power is needed to increase the speed of the suspension as it leaves the thruster (22) and the thruster (22) requires less engine power (24) to act and push the suspension.

Additionally, when the thruster (22) rotates in the opposite direction of the suspension after passing through the guide fins (114), the blades (74) deflect the suspension so that the suspension is discharged from the thruster (22) in the direction of the arrow A in an orientation essentially parallel to the axis (78). Thus, the thruster (22) straightens the directional route of the suspension and discharges the suspension in an axial alignment essentially parallel to the axis (78). The suspension flows more

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29/34 when it is discharged parallel to the axis (78) than when it is discharged at an angle to the axis (78) towards the inner wall of the pipe (21) because the inner wall resists and deflects the flow of the suspension.

Figure 6 provides a different view of the guide fins (110). In this view, the guide fins (110) are shown emerging from a pipe (21), which is not connected to the rest of the reactor.

In this way, the use of guide fins with the pump (100) improves the efficiency in moving the suspension through the cycle reactor (10) (Figure 1), increasing the speed of the suspension as the suspension leaves the pump (100) and reducing the power required to turn the thruster (22). Thus, the use of guide fins with the propellant (22) produces improved levels of solids.

In a conventional axial pump used in reactors, the propeller blades have a limited range of inclination or angle to the axis. In this way, the suspension discharged from the axial pump blades transits predominantly in the axial direction, generally parallel to the propeller shaft. However, due to the limited inclination of the blades, they interfere with the flow of the suspension and, consequently, the suspension is slowed down when coming into contact with the blades. Thus, a significant amount of energy is required to increase the speed of the suspension with the axial pump.

Figure 7 shows a mixed pump (200) inside a pipe (21). The pump (200) is fitted inside the pipe (21) in an arc-shaped pump box (204) that has a larger diameter than the pipe (21). THE

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The pump (200) has a thruster (228) attached to the shaft (212) extending through the piping (21). The thruster (228) has blades (208) that are positioned at an angle to the axis (212). The blades (208) can be oriented with respect to the axis at an angle between 0 and 90 degrees. The pump (200) includes a projection (216) positioned around the shaft (212) inside the pump housing (204) to define a curved or arc-shaped flow path (220) between the projection (216) and a wall (224) of the pump housing (204).

In the mixed pump shown in Figure 7, the suspension flows through the pipe (21) to a pump (200) in the direction of arrow B and confronts the blades (208). Due to the fact that the blades (208) can be aligned at different slopes (angles to the axis (212)), as the thruster (228) rotates, the suspension flows through the blades (208) with less interference and less energy is needed to increase the flow rate of the suspension. In this way, mixed pumps can increase the speed of the flow suspension more efficiently than axial pumps. The suspension that leaves the blades (208) has components of considerable speed in the directions perpendicular and parallel to the axis (212). The flow velocity components of the suspension are captured in the flow path (220) and the arc-shaped wall (224) of the flow path gradually redirects the orientation of the suspension speed components so that the suspension flows in one direction axial parallel to the shaft (212) when being unloaded from the pump housing (204) in the pipeline (21). Thus, mixed pumps can generate more height and

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31/34 speed in the flow of the suspension than an axial flow pump and then efficiently redirect the flow of the suspension when discharged from the propellant (228), so that improvements in speed and height are not lost. In this way, the mixed pumps generate the flow height and speed necessary to meet the pressure needs of large reactors.

It should be noted that a radial pump can also be used in the configuration in Figure 7. A radial pump works similarly to a mixed pump and provides many of the advantages of the mixed pump. However, a radial pump discharges the suspension flow from the propeller blades in a direction more perpendicular to the axis (212).

In addition, the post-propeller guide fins may be positioned along the flow path (220) to redirect the rotational flow and suspension speed. The suspension discharged by the thruster (228) generally moves in the same rotational direction as the thruster (228) and thus is not facing the direction of the outflow of the flow path (220). The post-propeller guide fins convert and redirect the rotational direction of the speed, energy and flow of the suspension so that the suspension that is discharged by the guide fins travel in a direction more parallel to the axis (212). Thus, the post-propeller guide fins improve the flow height of the suspension and the efficiency of the pump. These fins can also be known as diffusers, stators or connecting rods. They can also provide mechanical support within the flow path (200).

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The mixed or radial pump can be used in combination with any of the other aspects to be used with reactor cycles that are disclosed here, including: the dual pump arrangement, guide fins, minimized space between the propeller blade and the piping, manufacturing techniques and the propellant with a diameter larger than the pipe diameter.

Returning to Figure 2, the blades (74) of the thruster (22) have tips (88) that extend close to the inner wall of the enlarged section (66) without actually touching the inner wall. The distance between the tips (88) and the inner wall is the space distance. During operation, some suspension circulates back over the tips (88) of the blades (74) against the propeller chain (22) after being discharged in the direction of the propeller chain (22). Thus, the propellant (22) needs to confront the suspension that was once confronted. Reprocessing the suspension requires more power for the propellant (22) and slows down the pumping process. Thus, the re-circulated suspension leads to a less efficient reactor cycle with a reduced suspension speed.

The smaller the span of space, the less likely it is that the suspension will circulate back over the tips (88) of the blades against the thruster current (22) after being discharged towards the thruster current (22). The preferred space span in Figure 2 is 0.4 millimeters or less. When bringing the tips (88) of the blades (74) to 0.4 millimeters or less from the inner walls of the pipe (21), the propellant (22) reduces the recirculation, increasing the speed and pressure of the

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33/34 suspension on discharge and thus improving the flow and height of the suspension. The improved height, speed and flow of the suspension by the propellant (22) results in improved solids levels in the production suspension.

Finally, producing the propellant (22) from aluminum, titanium or steel results in a stronger propellant that is more resistant and that lasts longer. Commercial pumps for functions such as circulating reagents in a closed loop reactor are routinely tested by their 10 manufacturers and the pressures necessary to prevent cavitation must be determined. The manufacture of the thruster (22) in a 6-axis computer-controlled plunge cutter allows the thruster (22) to be manufactured from solid masses of metal that can be selected for 15 casting failures that can threaten the structural integrity of the propellant (22). In addition, the 6-axis computer-controlled plunge cutter can be used to closely control the thickness of the propeller (22) and to ensure that the propeller (22) has the general resistance required to withstand the highest speed, height and flow requirements thus improving the efficiency and production of solids in the reactor cycle (10) (Figure 1).

Increasing the height, speed and flow of the suspension by applying the techniques described above results in an improved level of solids being produced. Increasing the speed of the suspension as it flows through the cycle reactor causes greater heat transfer from the suspension to the cooling liners. The improved heat transfer results in a more efficient polymerization process and, consequently, a greater

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34/34 solids yield in the production suspension.

Although the invention has been described with reference to certain modalities, it will be understood by those skilled in the art that various modifications can be made and equivalents can be replaced without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Thus, it is intended that the invention is not limited to the particular modality disclosed, but that the invention includes all modalities that fall within the scope of the appended claims.

Claims (7)

1. Continuous suspension polymerization process in a tubular cycle reactor characterized by the fact that it comprises: 5 the introduction of monomer and catalyst to a cycle reactor; polymerizing the monomer to form a suspension comprising solid polyolefin particles in a liquid medium; 10 the circulation of the suspension using two propellants; transmitting a first rotational movement to the suspension with a first thruster; transmitting a second rotational motion to the suspension with a second thruster, where the second rotating motion is opposite the first rotating motion, and where the second thruster is spaced sufficiently close to the first thruster so that the second thruster benefit from the rotational energy of the first thruster. 2. Continuous suspension polymerization process, according to claim 1, characterized by the fact that it still comprises the pre-centrifugation of the suspension against 25 current of the first thruster, in a direction opposite to the first rotational movement of the thruster of the first thruster. 3. Continuous suspension polymerization process, according to claim 1, characterized by the fact that 30 still understand post-centrifugation of the suspension in the direction Petition 870190033550, of 8/8/2019, p. 43/45 2/2 of the current of the second pump, in the same direction as the second rotational movement of the propeller of the second pump. 4. Continuous suspension polymerization process, according to claim 1, characterized by the fact that 5 further comprising minimizing a space between at least one propellant and a portion of the cycle reactor containing the propellant. 5. Continuous suspension polymerization process, according to claim 1, characterized by the fact that 10 that the suspension has a concentration of solid polyolefin particles of at least about 45% by weight and at most 75% by weight. 6. Continuous suspension polymerization process, according to claim 1, characterized by the fact that 15 that the suspension is circulated at a flow of about 75,708.24 liters per minute to about 189,270.59 liters per minute. 7. Continuous suspension polymerization process, according to claim 1, characterized by the fact that 20 that the propellant reaches a height of about 36.58 meters to about 73.15 meters.