MXPA06007797A - Process and apparatus for cooling polymer - Google Patents

Abstract

A process and apparatus is disclosed for heating or cooling polymer solids in a dispensing section (72) of a solid-state polycondensation reactor (34). Gas (38) is delivered to the dispensing section of the reactor in which it cools polymer solids in the dispensing section by direct heat exchange. Part of the gas is withdrawn at a point (92) proximate to the dispensing section of the reactor and is cooled. The rest of the gas ascends through a reactive section of the reactor and purges polymer solids of impurities. The gas withdrawn from the reactive section of the reactor is oxidized of impurities and dried and then combined with the gas withdrawn proximate to the dispensing section of the reactor. To achieve uniform heating or cooling of the polymer solids in the dispensing section, a preferred ratio of mass flow rate of gas to the mass flow rate of solids is recommended.

Description

PROCESS AND DEVICE FOR COOLING BACKGROUND POLYMERS BACKGROUND OF THE INVENTION The present invention relates to a process for cooling or heating polymers in a polymerization reactor. The present invention relates specifically to cooling polymerized solids in a polycondensation reactor. The present invention relates particularly to cooling pieces of polyester, polyamide or polycarbonate in a solid state polycondensation reactor (SSP). Polymer resins are molded into a variety of useful products. One of these polymer resins is polyethylene terephthalate resin (TPE). It is well known that aromatic polyester resins, particularly TPE, copolymers of terephthalic acid with low proportions of isophthalic acid and polybutylene terephthalate, are used in the production of beverage containers, films, fibers, packages and tire fibers. U.S. Pat. US-A-4,064,112 Bl discloses a polycondensation or solid state polymerization (SSP) process for the production of TPE resins. Although the intrinsic viscosity of the resin for fibers and films should generally be between 0.6 and 0.75 dl / g, higher values are needed to mold materials such as containers and tire fibers. A higher intrinsic viscosity, of more than 0.75 dl / g, can be obtained directly, albeit only with difficulty, by the polycondensation of molten TPE, commonly known as the molten phase process. The SSP process makes the polymerization to a greater degree, thereby increasing the molecular weight of the polymer by heating and eliminating the reaction products. The polymer with higher molecular weight has a higher mechanical strength and other useful properties for the production of containers, fibers and films, for example. The SSP process starts with pieces of polymer that are in an amorphous state. U.S. Pat. US-A-4,064,112 Bl discloses the crystallization and heating of the pieces in a crystallizing vessel under stirring, until a density of between 1,403 to 1,415 g / cm 3 and a temperature of between 230 and 245 ° C is obtained, before entering the SSP reactor . Otherwise, the pieces tend to stick together. The SSP reactor may consist of a cylindrical reactive section, containing a vertical moving bed into which the polymer pieces are introduced from above, and a frusto-conical portion of a sourcing section in a base for dispensing the pieces of product. Typically, the polycondensation reactor operates at temperatures between 210 and 220 ° C. The polyester pieces are moved through the cylindrical reactive section of the polycondensation reactor by flow with gravity. However, when the pieces enter the frustoconical portion of the sourcing section at the base of the polycondensation reactor, they enter a non-flat velocity profile, which produces a disuniformity in the amount of residence time of the pieces in the reactor. polycondensation. Consequently, a variation from one piece to another occurs in the degree of polymerization, due to the variation in residence time. Moreover, in the transition from the cylinder to the cone, the pieces are subjected to a consolidation pressure that can be several times the normal radial axial pressure to which the piece was previously subjected to. The pieces that are in a vitreous region have a strong tendency to stick. Accordingly, the consolidation pressure can cause lumps formed from pieces, and interruption of flow. Various reactions occur during the polycondensation of TPE. The main reaction that increases the molecular weight of TPE is the elimination of the ethylene-gricol group: TPE-COO-CH2-CH2-OH + H0-CH2-CH2-00G-TPE? TPE-COO-CH2-CH2-OOC-TPE + HO-CH2-CH2-OH An inert gas such as nitrogen is introduced into the crystallizing vessel and the polycondensation reactor to remove volatile impurities from the polymer being developed, where the impurities are generated by the polycondensation reaction. Impurities include ethylene glycol and acetaldehyde if TPE is produced. U.S. Pat. US-A-5,708, 124 Bl discloses maintaining the ratio of inert gas mass flow rate to mass flow rate of solid polymers TPE to less than 0.6 in an SSP reactor. The conventional method used for the purification of a recycled inert gas stream from an SSP process includes an oxidation step to convert the organic impurities to C02, and a drying step to remove the water formed in the polymerization process and the oxidation step . The oxidation step is performed with oxygen-containing gas, using an oxygen concentration of no more than a slight excess of the stoichiometric amount relative to the organic impurities. The oxidation step is controlled in accordance with U.S. Pat. US-A-5,612,011 Bl, so that the inert gas stream in the outlet contains an oxygen concentration of more than 250 parts per million, and preferably in accordance with US Pat. US-A-5,547, 652 Bl, so that the inert gas stream in the outlet contains an oxygen concentration of no more than 10 parts per million. These patents disclose that a de-oxidation step, previously required, of reducing oxygen with hydrogen is not required between the oxidation and drying steps. Typically, the inert gas stream must be heated before being recycled into the polycondensation reactor, which requires additional installation costs. It is also well known that polyamide resins, and among them particularly PA6, PA6.6, PA11, PA12 and their copolymers, have wide applications in the flexible and flexible packaging sectors, and in the production of articles manufactured by blow and by extrusion technology. As long as the relative viscosity of fiber resins is low, between 2.4 and 3.0, higher relative viscosities of between 3.2 and 5.0 are required for articles produced by blowing and extrusion technologies. The relative viscosity is increased to more than 3.0 by an SSP process that operates at temperatures between 140 and 230 ° C, depending on the types of polyamide used. U.S. Pat. US-A-4, 60, 762 Bl describes an SSP process for a polyamide, and different methods for accelerating this reaction. An SSP process for polyamide resins is also described in the article "Nylon Polymerization in the Solid State," R. J. Gaymans et al., Journal of Applied Polymer Science, Vol. 27, 2515-2526 (1982), which teaches the use of nitrogen as an aid for heating and emptying. The reaction is carried out at 145 ° C. It is also known that the molecular weight of a polycarbonate can be increased by an SSP process. Pieces of polymer leaving an SSP reactor must be cooled to less than the glass transition temperature for packaging purposes, especially to avoid heat damage in the packaging containers, such as bags and boxes. The desired packing temperature is less than 80 ° C for TPE pieces. U.S. Pat. US-A-5,817,747 Bl discloses a two-stage cooling of the polymer pieces after leaving the polycondensation reactor. The first cooling stage is a fluidized bed with nitrogen, used to purge impurities from the SSP process after the nitrogen is purified. The fluidized gas enters the polymer powder, separating it from the pieces of polymer, while cooling them to between 160 and 180 ° C. The polymer powder is formed in the processing apparatus by the action of rotating parts of a stirrer, in contact with the polymer pieces, in the crystallizing vessel, and sliding friction between the pieces and walls of the polycondensation reactor. The second cooling stage is a heat exchange cooler of shell and tube type, or walls, which uses water as a cooling fluid, to cool the pieces to between 40 and 60 ° C. U.S. Pat. US-A-5, 662, 870 Bl discloses a fluidized bed with two chambers for cooling pieces of polymer leaving the SSP reactor in a single step. Fluidizing gas is recycled from the hot chamber, into which hot pieces enter from the SSP reactor, to heat the SSP reactor after being dusted off by a cyclone. The fluidizing gas of the cooling chamber is also dedusted by a cyclone and recycled to the fluidizing bed. The amount of powder collected in the fluidizing gas from a fluidized bed is significant, and must be eliminated. Japanese Patent JP 5-253468 discloses introducing nitrogen gas into a container surrounding a dispensing cone at the bottom of a reaction chamber, to indirectly cool a product, a mixture of gas and solid in the cone, without causing turbulence within the cone. A thesis by G. Ghisolfi entitled "Impianto di Postpolicondensazione di Polietilentereftalato "(1984-85) reveals an SSP reactor with nitrogen gas distributors located along the height of the reactor in which the nitrogen distributor of the bottom cools pieces of polyester at less than a temperature at which it can occur an oxidation, such as 177 ° C. The chunks should subsequently be cooled to lower temperatures to allow packing.A presentation by A. Cristel entitled "Advanced PET Bottle-to-Bottle Recycling" given at the 2000 World Polyester Congress, reveals cooling directly recycled TPE flakes in an SSP reactor hopper with cold nitrogen Cooling the polymer chunks after leaving the polycondensation reactor requires at least one cooling device, a gas reamer as a fan, and a device This equipment must be located below the reactor, or at some collection point, and is It is necessary to use a pneumatic conveying device to transport the hot pieces to the top of a cooling section. Each approach involves additional equipment and construction costs. In addition, the first approach requires a larger overall SSP complex. U.S. Pat. US-A-4,255,542 Bl discloses an exothermic gas phase polymerization process in a fluidized bed reactor, which is cooled by indirect cooling inside the reactor. U.S. Pat. US-A-3,227,527 Bl discloses a catalytic reactor vessel, wherein the product gas permeates a truncated cone section in the reactor base, which must be cooled with a quench liquid before leaving the reactor. These patents do not involve direct cooling of the solid polymers in a bed filled with a gas. Accordingly, an object of the present invention is to eliminate the additional cooling equipment required to cool the pieces to a packing temperature after leaving the SSP reactor. A further object of the present invention is to consolidate the equipment used to cool solid polymers and to introduce purge gas to the S? P reactor to purge the impurities. A further object of the present invention is to cool the pieces of polymer entering the SSP reactor's supply section, and consequently to make the sourcing section a non-reactive region, and to prevent hot and sticky polymer pieces from forming lumps. when they are subject to the consolidation temperature, when entering the frustoconical portion of the sourcing section. Still another object of the present invention is to be able to eliminate the need for expensive dust removal equipment, which is necessary for the cooling equipment of the post-polycondensation reactor. SUMMARY OF THE INVENTION We have discovered that it is possible to cool the polymer pieces of the SSP reactor temperature from 185 to 240 ° C to less than 175 ° C in a polycondensation reactor sourcing section. In addition, we have discovered that we can cool the granules to less than 80 ° C, which is below the glass transition temperature for packing and normal transports of TPE pieces. It was surprisingly discovered that the heat transfer from gases to solids is fast enough to allow the upper part of the sourcing section to be used for efficient cooling, if particular mass proportions are used. Accordingly, in one embodiment, the present invention relates to a device for performing a polymerization process. The device comprises a reactor that includes a heated reactive section, in which an essential polymerization of contained polymeric solids occurs, and a dispensing section for supplying solid polymers from the reactor. The sourcing section defines an interior volume, preferably in a form that reduces its flow surface in the direction of particle flow. A gas inlet connected to the interior volume of the sourcing section supplies gas to the sourcing section to heat or cool solid polymers passing through the sourcing section. A gas outlet connected to the reactor, next to the sourcing section, extracts gas from the sourcing section. In another embodiment, the present invention relates to a process for cooling solid polymers in a reactor, comprising a reactive section and a dispensing section. The process comprises supplying solid polymers to the upper part of the reactive section. The solid polymers are polymerized by flowing down in the reactive section, to increase the molecular weight of the solid polymers.

The solid polymers are supplied from the reactor's supply section. Gas is supplied to the sourcing section to flow concurrently with the solid polymers, and come in contact with the solid polymers to heat or cool them in the sourcing section. Part of the gas is extracted in an outlet close to the sourcing section. In still another embodiment, the present invention relates to a process for adjusting the temperature of solids moving in a container, by direct heat exchange with a gas. The process comprises supplying solids to a first section of the container. The solids are dispensed from a second section of the container. Gas is flowed through the vessel to effect a direct heat exchange between the gas and the solids. A mass flow rate ratio of the gas, multiplied by the thermal capacity of the gas at a solids mass flow rate, multiplied by the thermal capacity of the solids over a temperature range in the reactor, is at least one. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic view of a polymerization flow scheme of the present invention. Figure 2 is an enlarged partial view of a reactor and cooler dispenser section of Figure 1. Figure 3 is an enlarged partial view of an alternative reactor cooler and assortment section of Figure 1. Figure 4 is a graph of a temperature profile through the supply section of a reactor. DETAILED DESCRIPTION OF THE INVENTION A detailed description of a preferred process and device of the present invention is provided in the context of a solid state polycondensation (SSP) process. The SSP process can be used to increase the intrinsic viscosity of polyester, polyamide and polycarbonate components. However, the present invention can be used with other types of polymerization process, in which cooling of the polymer solid product is necessary. Polyester resins usable in the process SSP are polycondensation products of aromatic bicarboxylic acid, particularly terephthalic acid or its esters with diols with 1 to 12 carbon atoms such as ethylene glycol, 1,4-dimethylolcyclohexane and 1,4-butanediol. Preferred resins are polyethylene terephthalate (TPE) and polybutylene terephthalate. Polyester resins usable in the SSP process may also include elastomeric polyester resins, including segments derived from polyethylene glycol and copolyesters containing up to 20% units derived from aromatic bicarboxylic acids other than terephthalic acid, such as isophthalic acid. The TPE resins to be subjected to SSP may contain a resin upgrade additive to accelerate the SSP reaction. Preferred preferred preferred compounds are dianhydrides of aromatic tetracarboxylic acids, and particularly pyromellitic dianhydride. The updating agent is generally used in an amount between 0.05 and 2% of the weight. Conventional additives, such as stabilizers, dyes, flame retardants and nuclearizers, may also be present in the resin. Polyester resins useful for updating in SSP processes can also be materials produced from recycled containers, previously washed, crushed and dried. Typically, the recycled material is remelted and granulated before being sent to the SSP process. The polyamide resins usable in the process of the present invention include polyamide 6 derived from caprolactam, polyamide 6,6 obtained from hexamethylenediamine and adipic acid, polyamide 11 obtained from aminoundecanoic acid, copolyamides 6/10 and 10/12 from 12 polylaurylacetone, in addition of metaxylene diamine polyamides. Figure 1 is an example of an SSP process for updating TPE pieces with the present invention. However, the present invention can be applied to other polymerization processes, in which the solid polymers must be heated or cooled. The SSP process in Figure 1 can process up to 100 metric tons per day, and more than solid polymers, and typically between 300 and 500 metric tons per day of solid polymers. The SSP process of polyester comprises feeding amorphous and transparent polyester pieces, with an intrinsic viscosity of between 0.57 and 0.65 dl / g to a hopper 12 through a line 10. The intrinsic viscosity or molecular weight of the initial material is not important for the practice of the present invention. Generally, the SSP process can be efficiently performed with feeds from a wide range of values. For example, techniques for using an initial material with a degree of polymerization of up to 2-40 are disclosed by US Pat. US-A-5,540,868 Bl and US-A-5, 633, 018 Bl and US-A-5,744,074 Bl, which contemplate eventually passing through an SSP processing to raise the molecular weight enough to produce useful resins. In addition, the initial intrinsic viscosity in the case of post-consumer recycle material can be at levels of more than 0.65 dl / g. The hopper 12 feeds the pieces through a line 14 and a control valve 16 to a fluidized bed pre-crystallizer 18. The pre-crystallizer 18 operates at 170 ° C and 10.3 kPa to obtain a crystallinity of 35% of the pieces of polyester. The polyester pieces of the pre-crystallizer 18 are then fed through a line 20 and a control valve 22 to a first crystallizer 24. If a larger capacity is required, a second crystallizer 28 can be used which feeds the first crystallizer 24 by means of a line 26. In the crystallizers 24,28 the pieces are possibly preheated or in some cases cooled, at an SSP reaction temperature while being subjected to mechanical agitation to prevent the pieces from sticking together. The pieces that come out of the crystallizer have a crystallinity of 45%. Crystallizing the TPE granules before polycondensation prevents the granules from sticking during the SSP reaction. The pieces leaving the crystallizers are fed via a line 30 to a control valve 32 to a full moving bed SSP reactor 34 suitably operated at 150 to 240 ° C, and preferably at 210 to 220 ° C for TPE. The pieces are moved by gravity through a heated reactive section where polymerization occurs for 12 to 36 hours to produce crystalline and opaque granules, with an intrinsic viscosity of 0.75 dl / g or more, depending on the application to the polyester granules. The pieces of the reactor 34 are removed by a line 36. An inert gas without oxygen, typically nitrogen, purges the polymerization reactor, the crystallizers and the pre-crystallizer to remove impurities produced by the pieces. The inert gas is supplied via a line 38 to the reactor 34. A gas line 42 removes inert gas with impurities from the reactor 34, and divides it into a recycle line 44 and a crystallizer line 46. The crystallizer line 46 supplies the inert gas to the second crystallizer 28, and a line 48 supplies inert gas from the second crystallizer 18 to the first crystallizer 24. A line 50 supplies inert gas with impurities to the pre-crystallizer 18, and a line 52 supplies inert gas with impurities to join the line Recycling 44. The inert gas recycled in a combined recycling line 53 is preferably at a temperature between 200 and 220 ° C. The combined recycling line 53 passes the inert gas with impurities through a filter 54. After filtering the recycled inert gas stream, air is injected via a line 57 to a line 56 leaving the filter 54. The mixture is transported. of air and inert gas by a line 59 through a heater (not shown), if this is necessary to obtain the desired oxidation reaction temperature, to an oxidation reactor 58 where the organic impurities are burned by circulating the current on a catalyst bed including an oxidation catalyst. Oxygen is injected via line 57 in essentially stoichiometric amounts, to ensure complete combustion of the organic impurities in the oxidation reactor 58. Preferably, no more than 10 parts per million oxygen is present in the reactor effluent 58. The oxidation reactor 58 can be activated with these conversions at temperatures between 200 and 350 ° C, depending on the catalyst. A line 60 extracts the effluent from the oxidation reactor 58 which contains only nitrogen, carbon dioxide, water and traces of oxygen. The carbon dioxide content is stabilized at a certain level, due to the losses by the SSP plant, and acts similarly to an inert gas due to its chemical inertness. The gaseous stream leaving on line 60 can be circulated through a heat exchanger (not shown) to recover heat, or to condense and remove some of the water, by cooling the oxidation reactor effluent. Optional condensing collection equipment is not shown in the figures. The gaseous stream is supplied by line 60 to a dryer 62 which preferably operates at 200 ° C. The dryer 62 preferably contains molecular filters to adsorb the water. The effluent from the dryer 62 is transported by a line 64 after having filtered (not shown) the possible particles derived from the molecular filters. Line 38 collects the combined contents of lines 64 and 74. Line 38 recycles the gaseous stream to reactor 34. Regeneration of the molecular filter bed is performed according to known methods (not shown). The reactor 34 includes the active or reactive heated cylindrical section 70, which is preferably heated with a circulating oil cover. The reactor 34 also includes an assortment or inactive section 72 containing a peelable cylindrical portion 88, and an inverted and generally frustoconical consolidating portion 90. The inert gas, preferably nitrogen, enters an interior volume 91 defined by the sourcing section 72 a through line 38. The inert gas directly cools the solid polymers in the sourcing section up to 175 ° C, preferably to less than 100 ° C, preferably to less than 80 ° C and possibly to less than 50 ° C, if so is desired The cooled solid polymers can then be transported to storage via line 36 without the need for traditional chiller equipment. A portion of the inert gas is removed from the reactor 34 near the sourcing section 72 by a line 76, and enters a dust removing device 78. Next to the sourcing section device 72, the extraction point of the line 76 is in the dispensing section 72, but not below the lower quarter of the reactive section 70, and preferably not above the lower tenth of the reactive section 70. The dust-free gas is conveyed from the dust extraction device 78 by a line 80, and is moved by a fan 82 by a line 84 to a cooler 86, and is combined with the line 64 to be recycled to the sourcing section 72 of the reactor 34 via the line 38. Figure 2 provides a partial view of the reactor 34. The the cylindrical removable portion 88 has an inner diameter greater than the inner diameter of the reactive section 70. Gas is withdrawn from the reactor 34 towards the line 76 by at least one outlet nozzle 92. The outlet nozzle is preferably disposed in the detached portion 88 of the dispenser section 72. Although only one outlet nozzle 92 is shown in Figure 2, a plurality of radially disposed outlet nozzles 92 is contemplated. The remaining gas will rise through the Reactive section 70 of reactor 34, and purge impurities extracted from the polymer that develops. Since solid polymers exchange heat with the cooling gas, the gas which is extracted by the outlet nozzles 92 and which rise through the reactive section 70 will have a temperature which is not essentially different from the solid polymers in the reactive section 70 of the reactor 34. Accordingly, the gas rising to the Reactive section 70 will not interfere with the polycondensation reaction by cooling. The dust removing device 78 is a dust removing cyclone or filter, which can operate continuously. The amount of dust removed from the cooling gas flowing through the packed bed of solid polymers is low, because it is only taken from the top layer of the polymer. Accordingly, circulating gas cooling can be performed with a single filter, or with a more compact and less expensive dust removal cyclone than the equipment required to remove dust from a conventional fluidized bed. The cooler 86 removes the heat that the gas acquires in the sourcing section 72 by indirect heat exchange with a cooling medium, such as water. The flow rate of the gas removed next to the sourcing section 72 can be set by a variable capacity characteristic of the fan or by a control valve (not shown). Accordingly, the surplus inert gas, equal to the gas flow from the dryer 62 in the line 64, rises to the reactive section 70 from the sourcing section 72. The control valve 40 regulates the gas flow through the line 64. Preferably the regulation of the control valve 40 ensures that the mass flow rate of the gas against solids is less than 0. 6, taking into account the gas removed from the reactor for cooling and recirculation. The temperature of the rising and extracted gas is set by the temperature of the gas fed to the sourcing section 72, plus the temperature rise caused by the removal of heat from the solid polymers. The variable capacity fan 82 or control valve can regulate the temperature of the solid polymers leaving the outlet 100 of the reactor 34. For example, setting the fan 82 or the control valve for a very low flow rate, or a zero flow, raises the temperature of the gas in line 38, since it is mixed with less cooled gas from line 74. Therefore, if desired, the solid polymers leaving outlet 70 may have sufficient temperature to be transported directly to a molding process such as injection molding, which requires that the temperature of the solid polymers be above the glass transition temperature to be able to be molded. In addition, the flow rate of the cooler circulated by the cooler 86 can regulate the temperature of the solid polymers leaving the reactor without affecting the flow rate of the gas flowing through the nozzles 92 and the nozzle 96. The inlet nozzle 96 distributes the gas by an annular distributor 98 in the form of a ring of a pipe (not shown), or ring around the inner diameter of the sourcing section 72. The annular distributor 98 has openings distributed radially around its circumference, to distribute gas to the sourcing section 72. Preferably, the distributor does not extend to the reactor 34, to prevent it from obstructing the flow of solid polymers. Figure 3 shows a different device for injecting inert gas into the sourcing section 72, and including a control valve 94 on a bypass line 68. A distributor 98 'in Figure 3 injects cooling gas around the periphery of the assortment section 72 of the reactor 34. The distributor 98 'injects the cooling gas to the sourcing section 72, through perforations (not shown) in the wall of the sourcing section 72. The perforations of the distributor 98' can be defined by slots, bands or wire meshes. Essentially, distributor 98 'does not extend to reactor 34. In Figure 3, the control valve 94 regulates the temperature of the solid polymers leaving the outlet 100. The flow of the line 84 'is divided into a line 102 that goes to the cooler 86, and the line 68 that dodges the cooler 86 through the control valve 94, and is attached to the effluent of the cooler 86 in a line 74 '. A combined line 104 is connected to line 64 from dryer 62, and communicates with inlet nozzle 96 via line 38. Control valve 94 regulates gas bypass on line 68 to control the gas temperature at line 104, and ultimately line 38. Opening the control valve 94 further cools the recirculating gas in the cooler 86, to reduce the cooling of the solids, and vice versa. A temperature indicating controller (not shown) automatically regulates the control valve 94 based on the desired temperature of the solids exiting through the outlet 100. The flow scheme at the outlet 3 advantageously controls the temperature of the solid polymers, while maintaining a constant gas rate from nozzle 92 and towards nozzle 96. Accordingly, the rate of gas flow ascending through reactive section 70 to purge impurities is not affected. In accordance with the teachings of the present invention, other types of injection can be used. cooling gas and collector equipment. Furthermore, it is contemplated that hot inert gas could be fed to the reactor to heat the solids, if desired, with the same equipment, with the exception that a heater is used instead of the cooler 86. For example, this could be used. flow scheme to heat the solid polymers to make them suitable for injection molding after their polycondensation. Preferably, the actual local velocity of the cooling gas in all sections of the sourcing section should not exceed 75% of the minimum fluidization rate of the solid polymers. This preference mainly avoids the agitation of the solids, which can produce a maldistribution of flow and a subsequent loss of cooling efficiency. Second, the fluidization of the solid polymers can alter the mass flow of the solids through the perturbations in the bed, which could produce a larger residence time distribution, and a variability in the intrinsic viscosity. In order to ensure the uniformity of temperature of the solid polymers, it is important that a thermal mass ratio "R" is greater than or equal to l. The thermal mass ratio is as follows: Mass of ascending gas flow * thermal capacity of gas R = mass flow of falling solids * thermal capacity of solids (1) With R > 1 and substituting the thermal capacities of inert gas and solids, equation 1 can be rewritten as follows: ascending mass flow index for gases Thermal capacity of solids mass descending flow index for - Gas thermal capacity / 2) solids Having nitrogen as the inert gas and polyester, polyamide or a polycarbonate as the solids, a suitable proportion of mass upflow index for gas versus mass flow rate for solids is 1.6, and 1.9 is a preferred ratio representing any non-uniformity of flow. Efficient cooling is achieved in the sourcing section 72 of the reactor 34 without wasting additional space or using additional equipment. Typically, the cooling equipment is below the reactor 34. Eliminating conventional cooling equipment reduces capital costs, and the overall height of the SSP. Alternatively, no collection point is required to transport hot solid polymers to a cooling zone, which is not located below the polycondensation reactor. The mechanics of solid flow indicates that through the active cylindrical section of reactor 34, solid polymers are in flux. However, when the solid polymers enter the frusto-conical portion of the sourcing section 72, they begin to flow non-uniformly to some extent. By cooling the solid polymers below the reaction temperature, the sourcing section ceases to be an active section, and the solid to solid variation in intrinsic viscosity or molecular weight is less due to the effective residence time with the solids has a more adjusted distribution. Additionally, the transition of the solid polymers from the cylindrical reactive section 70 to the frustosonic portion 90 of the sourcing section 72 puts them under a consolidation pressure that can stick the solids together, which produces lumps of solids and interruption of flow . Maintaining the transition between the reactive section 70 and the assortment section 72 of the polycondensation reactor at a lower temperature reduces the stickiness of the solids, which results in greater ease of operation. Therefore, the materials that are more prone to sticking can be processed by cooling in the sourcing section. In addition, the temperature of the reactor 34 may be increased, to cause a higher reactivity of the polymer, with a higher concomitant production rate and an increase in intrinsic viscosity or molecular weight. The high thermal conductivity of polymeric resins such as TPE causes the temperature of the inert gas rising above the sourcing section to store at the temperature of solid polymers that flow downward. If this rising gas from the sourcing section were too cold, it would require intermediate heating to prevent the cooling gas from producing a negative impact on the polycondensation reaction. However, the efficient recovery of what would otherwise be wasted heat from the solid polymers, would allow the excess cooling gas to flow through the active section of the polycondensation reactor, and function to purge impurities from the solid polymers. Therefore, the reactor needs only a stream of inert gas that works both for cooling and for purging. Additionally, the solid polymers in the sourcing section distribute the gas through the cross section of the reactor, and avoid the need for expensive distribution equipment that could clog the flow of solids. EXAMPLE The sourcing section of the present invention was tested in a 618 mm inner diameter pilot reactor. Nitrogen cooling gas was injected radially at a point of the frustoconical portion of the supply section, which corresponds to a gas velocity of approximately 0.6 m / sec. The cooling gas was removed at the top of the frustoconical portion of the sourcing section. The TPE copolymer with an intrinsic viscosity of 0. 6 dl / g was raised to 0.8 dl / g in the reactor, and the product leaving the frusto-conical in the sourcing section had a temperature of about 45 ° C. The mass flow rate ratio of gas against solids in the sourcing section was 2.0, and the gas was injected at approximately 42 ° C. The temperature of the granules was measured by sliding a thermocouple about the centerline, and the results were that the heat transfer was achieved at slightly more than one reactor diameter. Figure 4 shows a graph of the temperature profile. Since the thermocouple is thought to be in contact with the TPE granules, the temperature of the gas was estimated by a heat balance. The dust was collected with a filter in the stream leaving the reactor, and represented less than 5 parts per million of the weight of the gas stream. A stream of cooling gas with such low dust concentrations can be adequately moved by a normal gas impeller. 4/4 500 1000 1500 2000 2500 3000 3500 Helght of Reactor (mm) FIG. 4

Claims (10)

1. CLAIMS 1. A device for carrying out a polymerization process, wherein the device comprises a reactor that includes: a heated reactive section in which an essential polymerization of the solid polymers occurs; a supply section for supplying solid polymers from the reactor, where the sourcing section defines an interior volume; a gas inlet that is connected to the interior volume of the sourcing section, to supply gas to the sourcing section, to heat or cool solid polymers that are transported through the sourcing section, which preferably includes an annular distributor with openings in communication, but which essentially do not extend to the interior volume of the reactor sourcing section; and a gas outlet connected to the reactor, close to the sourcing section, to extract gas from the sourcing section.
2. 2. The device of claim 1, wherein the dispensing section includes a shape that educes its flow area in the direction of particle flow, preferably by a frustoconical portion with a smaller diameter opening from which the solid polymers exit. of the reactor.
3. The device of claim 2, wherein the reactive section is cylindrical, and which is connected to a large diameter opening of the dispensing section.
4. The device of claim 1 to 3, wherein a gas cooler is in communication with the gas inlet, and preferably a gas driver that is in communication with the gas inlet, and the gas cooler communicates with the gas inlet. a purge line that supplies gas extracted from the reactive section of the reactor to the gas inlet.
5. The device of claim 4, wherein a variable capacity gas impeller or a control valve regulates the flow rate of the gas extracted from the gas outlet.
6. The device of claim 4, wherein the purge line includes a control valve upstream of a communication with the gas cooler.
7. 7. A process for cooling solid polymers in a reactor, comprising a reactive section and a dispensing section comprising: supplying solid polymers to the top of the reactive section; polymerizing the solid polymers as they flow down to the reactive section, to increase the molecular weight of the solid polymers; supplying the solid polymers from the reactor supply section, preferably at a temperature of less than 150 ° C; supplying gas to the assortment section to flow against the current of the solid polymers and to come into contact with the solid polymers to heat or cool them in the sourcing section; and extract part of the gas in an outlet close to the sourcing section.
8. 8. The process of claim 7, which includes cooling the extracted gas close to the sourcing section, preferably filtering it before it is cooled, and preferably regulating the flow rate or temperature of the recycled gas to the sourcing section to obtain a desired temperature of solid polymers in the assortment section. The process of claim 7, wherein the remainder of the gas not extracted from the outlet purges impurities from the solid polymers in the reactive section and is drawn to the reactive section, the gas extracted from the reactive section is combined with nearby extracted gas to the sourcing section after the gas extracted close to the sourcing section is cooled, and the gas extracted from the reactive section has impurities that are oxidized and dried before they are combined with the gas extracted from the sourcing section. The process of any of claims 7 to 9, wherein the ratio of a mass flow rate of the gas multiplied by the thermal capacity of the gas, against the mass flow index of solid polymers multiplied by the thermal capacity of the solid polymers, in a temperature range in reactor is at least one.