CN110813225B - Melt polycondensation reactor and falling film element thereof - Google Patents
Melt polycondensation reactor and falling film element thereof Download PDFInfo
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- CN110813225B CN110813225B CN201910958139.XA CN201910958139A CN110813225B CN 110813225 B CN110813225 B CN 110813225B CN 201910958139 A CN201910958139 A CN 201910958139A CN 110813225 B CN110813225 B CN 110813225B
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- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/24—Stationary reactors without moving elements inside
- B01J19/247—Suited for forming thin films
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- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0006—Controlling or regulating processes
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- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
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- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
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Abstract
The invention discloses a melt polycondensation reactor and a falling film element thereof, wherein a melt material slides down along a falling film runner of the falling film element to perform polycondensation, and the falling film element is a combined falling film element of which a pipe fitting is connected with a flat plate to enclose and obtain an open type vertical inwards concave falling film runner. The combined falling film element is vertically installed, falling film runners on the element are arranged in parallel and are provided with film distribution holes, and the arrangement mode of the pipe fittings and the flat plate, the size of the falling film runners and the arrangement of the film distribution holes can be designed aiming at the melt polycondensation reaction of each polymer; a heating medium circulation passage is arranged in the pipe fitting of the falling film element to ensure that the reaction material is heated uniformly and stably when moving along the falling film flow channel. The reactor and the falling film element have the advantages of flexible design and processing, low cost, small flow resistance of molten materials, no back mixing dead zone, large film forming area and surface updating frequency, and can be used for efficient melt polycondensation of polymers such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate and the like.
Description
Technical Field
The invention relates to a melt polycondensation reactor device in the production of high-viscosity polymers.
Background
The key point in the polycondensation production process of the high molecular weight polymer is to continuously remove small molecules generated in the system so as to ensure that the reaction is continuously carried out in the forward direction. The molecular weight of the polymer at the early stage of melt polycondensation is low, the viscosity of the system is not high, and the technological processes of stirring, mixing, heat transfer, mass transfer (micromolecule removal) and the like are not difficult, however, the high molecular weight generally means high viscosity, the viscosity of the reaction material at the later stage of melt polycondensation shows the order of magnitude change, the difficulty of micromolecule removal is increased greatly, and therefore the flow characteristic and the mass transfer of the material become the key control factors of the process.
The common solution currently used in the industry for the melt polycondensation production of high-viscosity polymers is the use of horizontal stirred reactors, the stirring elements being mainly of the disc and cage type. The film forming efficiency and the surface updating frequency of the reactor materials are closely related to the interaction between the stirring element and the materials, but when the viscosity of the materials is too high, the materials between the discs or the meshes are adhered, and the materials are easily and completely pulled out and synchronously rotated, so that the film forming efficiency and the surface updating frequency of a melt are limited, and the devolatilization of small molecules is influenced; limited by the reactor structure, the reaction temperature of the materials is not uniform enough, the flow condition of the melt is not good, a plurality of dead zones exist, the viscosity of the melt is not uniform, and the space for improving the equipment aiming at the higher-viscosity polymer is not large.
The falling film polycondensation reactor realizes high film forming efficiency and surface renewal frequency by means of film forming movement of prepolymer melt on a falling film element, and the lower energy consumption and production efficiency make the falling film polycondensation reactor more suitable for preparing high-viscosity polymers compared with the horizontal reactor. Most of the falling film polycondensation reactors disclosed at present are designed and manufactured based on specific process operating conditions or high-viscosity polymer products, and the problems of difficult control of reaction material residence time, obvious fluctuation of polymer product quality and the like can occur by changing the process operating conditions or the high-viscosity polymer products. However, the falling film element, which is a key internal component of the reactor, has the characteristics of small scope of improvement, complex structure of part of the falling film element, difficult processing and the like, the reactor has high improvement cost for the structure of the falling film element during manufacturing, and the design adjustment with low cost is difficult to realize on the basis of the former structure according to the change of the melt flow behavior of the polymer in the falling film polycondensation process, so that the application range of the falling film polycondensation reactor in the later period is limited.
Disclosure of Invention
The invention aims to provide a melt polycondensation reactor, which is provided with a novel combined falling film element with flexible design and low processing difficulty to adapt to melt flow behaviors of different polymers in a falling film polycondensation process, improve and maintain high melt film forming efficiency and surface updating frequency, ensure uniform material reaction temperature, realize uniform and stable melt retention time and finally obtain a high-quality polymerization product meeting requirements, and the following technical scheme is provided for the purpose:
a melt polycondensation reactor comprises an end enclosure, a material chamber, a vertical shell connected with the lower end of the material chamber and a bottom shell, wherein the reactor is provided with a feeding pipe, a material outlet and a vacuum degassing port, and the material chamber is communicated with the feeding pipe; the method is characterized in that:
at least one group of falling film elements are vertically arranged in the vertical shell, each falling film element is a combined falling film element formed by connecting a pipe fitting and a flat plate, a flat plate is connected between every two adjacent pipes, and the pipe fittings and the flat plates form an open type inwards-concave vertical falling film flow channel in an enclosing manner;
the melting polycondensation reactor is provided with a heat transfer system, the peripheries of the vertical shell and the bottom shell are both provided with heat preservation heat transfer passages, and heat preservation media in the passages circulate; the melt polycondensation reactor is provided with a first heating medium chamber and a second heating medium chamber which are communicated with the outside and provided with pipelines, the structure style of the melt polycondensation reactor can be diversified, the uniform inflow and outflow of the heating media are mainly realized, and the first heating medium chamber and the second heating medium chamber are communicated with a combined falling film element to form a heat transfer circulation path of the heating medium in the reactor.
The material chamber lower plate is a film distribution plate and is provided with film distribution holes, at least one group of combined falling film elements are vertically arranged below the film distribution plate, and each falling film flow channel on each combined falling film element is at least correspondingly distributed with one film distribution hole. Preferably, the number, size and shape of the film distribution holes of each falling film flow channel and the relative positions of the film distribution holes and the falling film flow channels are completely consistent with those of other falling film flow channels, and the effective cross-sectional area of each film distribution hole is 1-200 mm2。
Preferably, when the falling film runner belongs to one film distribution hole, the film distribution hole is positioned at the center of the concave bottom surface of the falling film runner; when a plurality of film distribution holes are formed in each falling film runner, the film distribution holes are symmetrically distributed on the wall surface of each falling film runner along the central line of the concave bottom surface of each falling film runner. The minimum distance between the inner wall of the film distribution hole and the wall surface of each falling film runner is less than 5 mm.
The end enclosure, the material chamber, the vertical shell and the bottom shell are all vertically arranged, the vertical shell is provided with a vacuum degassing port, and the reactor is provided with a discharge port for discharging.
The falling film element is a combined falling film element formed by connecting a pipe fitting and a flat plate, a flat plate is connected between two adjacent pipes, and the pipe fitting and the flat plate are enclosed into an open type concave falling film flow passage.
Furthermore, the combined falling film element at least comprises a flat plate which is connected with two adjacent pipe fittings, and a vertical falling film flow channel enclosed by the pipe fittings and the flat plate of the combined falling film element is concave. The section of the pipe fitting can be in various forms such as rectangle, circle, semicircle, triangle, ellipse, arc and the like, and the upper end of the flat plate is closely adjacent to the bottom plate of the material chamber;
the connection mode of the pipe fittings and the flat plate of the combined falling film element comprises that the pipe fittings and the flat plate are alternately connected in parallel in sequence according to the relative positions of the pipe fittings and the flat plate, and the pipe fittings are vertically arranged on the surface of the flat plate in an opposite mode or a staggered mode. When the pipes are alternately connected in parallel, a flat plate is arranged between the adjacent transverse pipes, and the left end and the right end of the flat plate are respectively connected with the pipes; when the pipe fittings are vertically arranged on the front side surface and the rear side surface of the flat plate, the front side surface and the rear side surface of the flat plate respectively comprise at least two parallel pipe fittings, the pipe fittings are arranged in a pairwise opposite mode or in a staggered mode in sequence on the front side surface and the rear side surface of the flat plate along the transverse direction, particularly, for the pipe fittings with straight wall surfaces on the back surfaces, the pipe fittings can be alternately arranged in the positive direction and the negative direction and connected with each other, the straight wall surfaces on the back surfaces of the pipe fittings are used as the flat plate, and the mutually connected pipe fittings are directly enclosed to form a combined falling film element with an inwards concave falling film flow channel, which belongs to a reasonable derivation of the invention. At least one falling film flow channel is arranged on each of two sides of the combined falling film element, a plurality of falling film flow channels are arranged in parallel, and parameters of the falling film flow channels are all the same.
Preferably, the falling film flow channel has a wide concave bottom surface (L)1) 5 to 100mm, an inner concave depth (H) of 2 to 100mm, and an opening distance (L)2) 8-100 mm;
a heat medium circulating heat transfer path is arranged in the pipe fitting of the combined falling film element, and the pipe fitting of the combined falling film element is communicated with a first heat medium chamber and a second heat medium chamber on the melt polycondensation reactor; the heat medium uniformly flows into the pipe fitting of the combined falling film element through one of the heat medium chambers and then flows into the other heat medium chamber through the pipe fitting, so that the heat medium at the falling film element circularly flows.
Compared with the prior art, the design style of the core component of the melt polycondensation reactor, namely the falling film element, adopts the idea of connecting a pipe fitting and a flat plate to obtain the open type concave vertical falling film runner, and can flexibly design the falling film flow on the surface of the falling film element according to the reaction characteristic and the flow characteristic of a target polymer meltThe structure is called as a combined falling film element, the falling film element has low processing difficulty and low cost, and the relative position between the pipe fittings and the connected flat plates and the pipe fitting interval (L) can be defined2) And the parameters such as the size of the pipe fitting and the like meet various special design requirements such as self-defining the width and the depth of a flow passage on the falling film flow passage, and further a high-efficiency and very targeted polymer melt polycondensation solution is obtained. A heat transfer pipeline of a heat medium which circularly flows is arranged in the combined falling film element, so that the uniform reaction temperature of the molten prepolymer is ensured when the molten prepolymer forms a film on the falling film flow channel and slides downwards, and the quality stability and uniformity of the melt are improved. The reaction equipment provided by the invention is simple, feasible and low in cost, has a series of advantages of strong adaptability, large film forming area and surface updating rate, high melt polycondensation reaction efficiency, low energy consumption, easiness in cleaning and the like, can realize high matching of melt polycondensation reaction process, melt physical property change and falling film flow development, is uniform and controllable in overall material residence time, and finally obtains high-quality and high-viscosity polymer products of different types.
Drawings
FIG. 1 is a schematic view of the structure of one embodiment of a melt polycondensation reactor according to the present invention.
FIG. 2 is a schematic view of the structure of another embodiment of the melt polycondensation reactor according to the present invention.
Fig. 3a and 3b are schematic views of an embodiment of the combined falling film element of the invention, l and Φ being the side length of a square tube and the diameter of a round tube, respectively.
Fig. 4a, 4b and 4c are schematic views of another embodiment of the combined falling film element according to the invention, l and h being the side length and the height, respectively, of the regular triangular tube elements.
Fig. 5a, 5b and 5c are schematic diagrams of the geometric layout of film distribution holes at the top of a trapezoidal section falling film flow channel of the combined falling film element of the invention.
The meaning of each number in the figure is: seal head 1, heat medium chamber 2, material chamber 3, film distribution plate 31, film distribution hole 311, combined falling film element 4, falling film flow channel 41, flat plate 411, pipe 412, pipe inter-heat medium flow port 413, vertical shell 5, tower jacket 6, tower jacket heat medium inlet 61, bottom jacket 7, bottom jacket heat medium inlet 71, bottom jacket 8, discharge port 81, bottom jacket heat medium outlet 72, bottom jacket connecting flange 82, bottom jacket connecting bolt 81, sleeve 11, tower jacket heat medium outlet 62, vacuum degassing port 51, material chamber connecting flange 33, material chamber connecting bolt 32, heat medium chamber heat medium outlet 21, heat medium chamber connecting bolt 22, heat medium chamber connecting flange 23, feed pipe 12, seal head heat medium inlet 13, seal head connecting bolt 14, seal head connecting flange 15
Detailed Description
The invention is described in detail below with reference to the drawings, wherein like reference numerals are used to refer to like or similar elements or elements having like or similar functions.
In the melt polycondensation reactor provided by the invention, as shown in fig. 1, a first heating medium chamber and a second heating medium chamber are important components of a falling film element heat transfer system, so that uniform inflow and outflow of heating media are ensured, and preferably, the end socket 1 is used as the first heating medium chamber, and the heating medium chamber 2 is used as the second heating medium chamber; a heating medium chamber 2 is connected below the seal head 1, and a tower body jacket 6 and a vacuum degassing port 51 are arranged on the vertical shell 5; the material chamber 3 is respectively connected with the vertical shell 5 and the heating medium chamber 2 through flanges, the prepolymer feeding pipe 12 is communicated with the material chamber, and a pipe fitting 412 penetrates through the prepolymer feeding pipe; at least one group of combined falling film elements 4 are vertically arranged under a film distribution plate 31 (lower bottom plate) which is tightly attached to the material chamber 3, two sides of each combined falling film element 4 are respectively provided with at least one open type vertical inwards concave falling film flow channel 41, the lower ends of pipe fittings of the combined falling film elements are closed, the upper ends of the pipe fittings are connected with the heat medium chamber 2 and are not communicated with each other, a sleeve pipe 11 connected with a seal head 1 is inserted in the pipe fittings, and a typical square pipe and a flat plate are enclosed to form the combined falling film element; the heat medium enters the reactor through the end socket heat medium inlet 13 at the end socket 1 (first heat medium chamber), the heat medium is injected into the lower end of the pipe fitting 412 by the sleeve 11 and overflows to the heat medium chamber 2 (second heat medium chamber) from the upper end of the pipe fitting, and the heat medium chamber is provided with a heat medium chamber heat medium outlet 21, so that the heat transfer circulation flow path of the combined falling film element 4 is completed, and the uniform heating and the consistent temperature of the falling film flow channel 41 are ensured. The end enclosure, the material chamber, the vertical shell and the bottom shell are all vertically arranged and connected by a flange fastener, so that the disassembly, the overhaul and the installation are convenient; the lower end bottom shell 7 is provided with a discharge hole 71 for discharging.
Referring to fig. 2, the melt polycondensation reactor of the present invention can be further modified in another embodiment, which is different from the polycondensation reactor of fig. 1 in that the sleeve 11 is removed from the head 1, the adjacent pipe members 412 of the combined falling film element 4 are connected to each other, a part of the pipe members of the falling film element are directly connected to the head, and the other part of the falling film element is connected to the heat medium chamber 2, and a typical combined falling film element formed by enclosing a U-shaped circular pipe and a flat plate is illustrated in the drawing. The heat medium enters the reactor through the end socket heat medium inlet 13 at the end socket 1 (first heat medium chamber), directly overflows to the heat medium chamber 2 (second heat medium chamber) from the upper end of the pipe fitting after internally circulating through the pipe fitting, and the heat medium chamber is provided with a heat medium chamber heat medium outlet 21, so that the heat transfer circulation flow path of the combined falling film element 4 is completed, and the falling film flow passage 41 is uniformly heated and has consistent temperature. In addition, other structural designs of the polycondensation reactor shown in fig. 2, such as the main structure of the melt polycondensation reactor, the structure of the surface flow channels of the combined falling film elements, the length and the arrangement of the film distribution holes, are the same as those of the polycondensation reactor shown in fig. 1, and the specific selection of the melt polycondensation reactor structure and the heat medium circulation scheme are determined by the specific form of the combined falling film elements.
One embodiment of the combined falling film element 4 can be described as a combined falling film element formed by connecting pipe elements 412 and flat plates 411 in parallel and alternately in sequence, wherein the flat plates are arranged between adjacent transverse pipe elements, the left end and the right end of each flat plate are respectively connected with the pipe elements, and the distance L between the adjacent pipe elements is L2Similarly, the upper end of the flat plate is close to the material chamber film distribution plate 31, and a circulating heat medium flows in the pipe fitting to realize heat transfer of the falling film flow channel of the combined falling film element. The heat transfer modes of the combined falling film elements can be distinguished according to whether the adjacent pipe fittings are communicated or not and are respectively applied to the melt polycondensation reactors described in the two embodiments. As shown in fig. 3a, the tube section of the combined falling film element 4 is square and has a width L1The two ends of the flat plate are connected with the diagonal edges of the pipe fittings, the central connecting line of the pipe fittings is superposed with the flat plate, the adjacent pipe fittings are not communicated, the falling film element is arranged in the melt polycondensation reactor shown in figure 1, a sleeve 11 connected with the end socket 1 is inserted in the pipe fittings, and the inflow heat medium at the end socket is injected through the sleeveThe falling film runner enters the pipe fitting to ensure uniform heating and consistent temperature; FIG. 3b shows a combined falling film element with a round tube cross-section and a width L1The flat plate is positioned on a connecting line of the circle centers of the adjacent pipe fittings, the lower ends of the adjacent pipe fittings are communicated in a U-shaped pipe form, so that the combined falling film element is arranged in the melt polycondensation reactor shown in figure 2, and an inflow heating medium at the end socket enters a heating medium chamber through the U-shaped pipe fitting, thereby completing the circulation of the heating medium and the uniform heat transfer of the falling film flow channel. In addition, the cross section of the pipe fitting can be in various forms such as a semi-circle shape, an arc shape, a triangle shape or a trapezoid shape, and the necessary connection does not exist between the cross section of the pipe fitting and a heat transfer circulation mode applied by the falling film element, and the cross section of the pipe fitting and the heat transfer circulation mode can be selected independently according to actual conditions. Two sides of the falling film element are respectively provided with at least one open type concave vertical falling film flow channel, and the main control parameter of the falling film flow channel comprises the opening distance (L) of the falling film flow channel2) And the width of the bottom surface of the inner concave (L)1) And the concave depth (H) of the falling film flow channel can be designed according to the polymer property.
Another embodiment of the combined falling film element 4 can be described as a combined falling film element formed by installing the pipe 412 on the surface of the flat plate 411, and the upper end of the flat plate is adjacent to the material chamber film distribution plate 31. When the pipe fittings are vertically arranged on the surfaces of the front side and the rear side of the flat plate, the front side and the rear side of the flat plate respectively comprise at least two parallel pipe fittings, the pipe fittings are arranged in pairs or in a staggered way on the surfaces of the front side and the rear side of the flat plate along the transverse direction, and the distance L between adjacent pipe fittings on the same side is2The same; likewise, the heat transfer modes of the combined falling film element can be distinguished according to whether the adjacent pipe fittings are communicated or not and can be respectively applied to the two melt polycondensation reactors. As shown in fig. 4a, the cross section of the pipe fitting of the combined falling film element 4 is triangular, the pipe fitting is symmetrically distributed along two sides of the flat plate, one side of the pipe fitting is connected with the end socket, the other side of the pipe fitting is communicated with the heat medium chamber, a hole for communicating the pipe fitting at two sides as shown in fig. 4c is arranged below the pipe fitting, and the tail end of the pipe fitting is closed; the combined falling film element can be arranged in the melt polycondensation reactor shown in fig. 2, and a heat medium can pass through the flat plate through the hole to complete the circulating flow of the heat medium during work, so that the falling film flow channel on the combined falling film element is heated uniformly and at the same temperature. As shown in fig. 4b, a combined falling film element4, the pipe fittings are also regular triangles in cross section, the pipe fittings are distributed along two sides of the flat plate in a staggered manner, the sleeves 11 connected with the end sockets 1 are inserted into the pipe fittings at two sides and used for injecting heat medium flowing into the end sockets, all the pipe fittings are connected with the heat medium chamber, and the heat medium enters the heat medium chamber through the pipe fittings so as to complete uniform and stable heat medium circulation required by a falling film flow channel of the combined falling film element, so that the combined falling film element can be arranged in the melt polycondensation reactor shown in fig. 1. Particularly, when the side length L of the regular triangle is less than the width L of the concave bottom surface1In the process, the tube body walls of the regular triangular tubes arranged in a staggered manner can be connected, the flat wall surface of each tube serves as the concave bottom surface of the falling film flow channel 41, the wall surfaces of the two adjacent connected tubes serve as the side wall surfaces of the falling film flow channel, and the arrangement of the tubes in the staggered manner also has the main functional characteristics of the falling film element shown in fig. 4, as described above, belongs to reasonable derivative changes, and is within the protection scope of the present invention. Similarly, the cross section of the tube 412 of the combined falling film element 4 in this embodiment may have various forms such as a semi-circular shape, an arc shape or a trapezoid shape, besides the triangular shape shown in fig. 4a, 4b and 4c, and there is no necessary relationship between the cross section of the tube and the heat transfer cycle applied by the falling film element. At least one open-type concave vertical falling film flow channel 41 is also arranged on each of the two sides of the falling film element, and the main control parameters of the falling film flow channel are the same as those of the first embodiment of the combined falling film element.
The embodiments of the melt polycondensation reactor and the combined falling film element described above are only preferred embodiments of the present invention, and variations or substitutions within the scope of the present invention by those skilled in the art are all within the scope of the present invention.
The novel melt polycondensation reactor and the falling film element thereof provided by the invention are further characterized in that: the material chamber film distribution plate 31 (lower bottom plate) is provided with film distribution holes 311, the lower bottom plate is vertically provided with at least one combined falling film element 4, and each falling film flow channel 41 on the falling film element is at least distributed with one film distribution hole; the number, size and shape of the film distribution holes 311 of each falling film runner and the relative position of the film distribution holes and the falling film runners are completely consistent with those of other falling film runners, and the film distribution holes are effectiveThe cross-sectional area is 1-200 mm2。
Preferably, as shown in fig. 5a, when there is one film distribution hole 311 to which each falling film flow channel 41 belongs, the film distribution hole is located at the center of the concave bottom surface of the falling film flow channel; as shown in fig. 5b and 5c, when there are a plurality of film distribution holes 311 in each falling film flow channel 41, the film distribution holes are symmetrically distributed on the wall surface of the falling film flow channel along the central line of the concave bottom surface of the falling film flow channel, and the minimum distance between the inner wall of the film distribution hole and the wall surface of each falling film flow channel is less than 5 mm.
Preferably, the falling film flow channel of the combined falling film element 8 has a wide concave bottom surface (L)1) 5 to 100mm, and an opening distance (L)2) 8-100 mm, and the depth (H) of the indent is 2-100 mm.
According to the invention, according to the characteristics of melt flow behavior change in the polycondensation reaction process of different types of polymers, the combined falling film element can flexibly select the type and arrangement mode of pipe fittings, and a falling film runner is designed in a targeted manner to adapt to viscosity change along the falling direction of the polymer melt, so that the high-efficiency melt polycondensation reaction is maintained, and the final quality of the product is improved. The melt polycondensation reaction method of the polycondensation reactor adopting the combined falling film element comprises the following steps:
the method comprises the following steps that a molten material is continuously injected into a material chamber through a feeding pipe, the material is uniformly dispersed on a film distribution plate, then the material flows out along film distribution holes on the film distribution plate, a film is formed on a falling film runner of a combined falling film element and slides downwards by means of gravity, and small-molecule volatile components are continuously removed in the process and the viscosity of a polymer is improved;
the melt on each falling film runner is gathered to the lower part of the vertical polycondensation reactor, and the materials can be stirred to further react under the stirring condition, so that the quality stability and uniformity of the melt are improved, and the melt after the reaction is discharged from a bottom discharge hole.
When the device works, a heat transfer medium uniformly flows into the polycondensation reactor from the outside of the polycondensation reactor through one of the heat medium chambers, uniform heat transfer to the falling film flow channel and the molten material is completed through the pipe fitting of the combined falling film element, then the heat transfer medium flows into the other heat medium chamber and finally uniformly flows out of the reactor, and the heat transfer medium is heated or cooled externally and then circularly runs.
Example 1: saddle-shaped section falling film runner for melt polycondensation and tackifying Polyester (PET)
Reactor structure and principles as described above, the first embodiment of the present embodiment using a combined falling film element is installed in the melting reactor shown in fig. 1, the pipe is a circular pipe, the falling film flow channel section of the combined falling film element is saddle-shaped, and the structure and operation parameters of part of the reactor are as follows: falling film flow channel wide concave bottom surface (L) on combined falling film element1) 5-40 mm, opening distance (L)2) 15-90 mm, 5-25 mm of depth (H), and 10-50 mm of pipe diameter of the circular pipe. The Polyester (PET) prepolymer with the viscosity of 0.65dL/g flows into a melt polycondensation reactor through a feeding pipe, and flows down to a trapezoidal falling film flow channel of a combined falling film element through a film distribution hole in a material chamber, the PET prepolymer slides down in a film forming manner on the falling film flow channel to finish polycondensation and viscosity increasing, the viscosity of the obtained product is 1.0-1.05 dL/g, and the production quality of the reactor is higher than that of a traditional horizontal polyester polycondensation reactor (the viscosity of the polyester product is 0.85-0.87 dL/g).
Example 2: trapezoidal section falling film runner for PET melt polycondensation viscosity enhancement
Reactor configuration and principles as described above, to further reduce the product viscosity variation range and improve product quality, the present embodiment employs a second embodiment of a combined falling film element, which is also installed in the melting reactor of fig. 1 by changing the tube design and arrangement. The pipe fitting is made of equilateral triangle section pipe, staggered arrangement is selected along the flat plate arrangement mode, the section of the falling film flow passage of the combined falling film element is trapezoidal, and the inner concave bottom surface of the falling film flow passage is wide (L)1) 5-40 mm, opening distance (L)2) 15-60 mm, 10-15 mm in depth (H), and 10-20 mm in side length of a triangle of the section of the pipe fitting; the structures of other reactors are the same as those of the embodiment 1, the PET prepolymer forms a film on a falling film runner and slides downwards to finish polycondensation and viscosity increasing, the viscosity of the obtained product is 1.02-1.04 dL/g, the product viscosity is also superior to that of the traditional horizontal polyester polycondensation reactor (0.85-0.87 dL/g), and the viscosity fluctuation range is smaller than that of the embodiment 1.
Claims (7)
1. A melt polycondensation reactor comprises a seal head (1), a material chamber (3), a vertical shell (5) and a bottom shell (8), wherein the vertical shell is connected with the lower end of the material chamber; the method is characterized in that:
at least one group of falling film elements are vertically arranged in the vertical shell (5), the falling film elements are combined falling film elements (4) formed by connecting pipe fittings and flat plates, a flat plate is connected between every two adjacent pipes, and the pipe fittings and the flat plates are enclosed into an open type inwards concave vertical falling film flow passage (41); the connecting mode of the pipe fittings and the flat plates of the combined falling film element (4) comprises the steps that the pipe fittings (412) and the flat plates (411) are sequentially and alternately connected in parallel, and the pipe fittings are vertically arranged on the surfaces of the flat plates;
the melt polycondensation reactor is provided with a heat transfer system, the peripheries of the vertical shell (5) and the bottom shell (8) are both provided with heat preservation heat transfer passages, and heat preservation media circulate in the passages; the melt polycondensation reactor is provided with a first heating medium chamber and a second heating medium chamber which are communicated with the outside and provided with pipelines, and the first heating medium chamber and the second heating medium chamber are communicated with the combined falling film element (4) to form a heat transfer circulation path of the heating medium in the reactor;
a heat medium circulating heat transfer path is arranged in a pipe fitting of the combined falling film element (4), and the pipe fitting (412) of the combined falling film element is communicated with a first heat medium chamber and a second heat medium chamber on the melt polycondensation reactor; the heat medium uniformly flows into the pipe fitting of the combined falling film element through one of the heat medium chambers and then flows into the other heat medium chamber through the pipe fitting, so that the heat medium at the falling film element circularly flows.
2. A melt polycondensation reactor as set forth in claim 1, wherein: the lower bottom plate of the material chamber (3) is a film distribution plate (31) and is provided with film distribution holes (311), at least one group of combined falling film elements (4) are vertically arranged below the film distribution plate, and each falling film flow channel (41) on each combined falling film element is at least correspondingly distributed with one film distribution hole.
3. A melt polycondensation reactor as set forth in claim 2, wherein: when the number of the film distribution holes (311) in the falling film flow channel (41) is one, the film distribution holes are positioned in the center of the concave bottom surface of the falling film flow channel; when a plurality of film distribution holes (311) are formed in each falling film runner (41), the film distribution holes are symmetrically distributed on the wall surface of each falling film runner along the central line of the concave bottom surface of each falling film runner.
4. A melt polycondensation reactor as set forth in claim 3, wherein: the minimum distance between the inner wall of the film distribution hole and the wall surface of each falling film runner is less than 5 mm.
5. A melt polycondensation reactor as set forth in claim 1, wherein: the seal head (1), the material chamber (3), the vertical shell (5) and the bottom shell (8) are all vertically arranged, the vertical shell (5) is provided with a vacuum degassing port (51), and the reactor is provided with a discharge port (81) for discharging.
6. A falling film element for a melt polycondensation reactor, characterized by: the falling film element is a combined falling film element (4) formed by connecting a pipe fitting and a flat plate, the flat plate is connected between every two adjacent pipes, and the pipe fitting and the flat plate enclose an open type inwards concave falling film flow passage (41);
the connecting mode of the pipe fittings and the flat plates of the combined falling film element (4) comprises the steps that the pipe fittings (412) and the flat plates (411) are sequentially and alternately connected in parallel, and the pipe fittings are vertically arranged on the surfaces of the flat plates;
a heat medium circulating heat transfer path is arranged in a pipe fitting of the combined falling film element (4), and the pipe fitting (412) of the combined falling film element is communicated with a first heat medium chamber and a second heat medium chamber on the melt polycondensation reactor; the heat medium uniformly flows into the pipe fittings of the combined falling film element through one of the heat medium chambers and then flows into the other heat medium chamber through the pipe fittings, so that the heat medium at the falling film element circularly flows.
7. The falling film element of a melt polycondensation reactor of claim 6, wherein: the falling film flow channel (41) enclosed by the pipe fitting and the flat plate of the combined falling film element is concave, and the falling film flow channel is concaveWidth of bottom surface (L)1) 5 to 100mm, an inner concave depth (H) of 2 to 100mm, and an opening distance (L)2) 8-100 mm; at least one falling film flow channel (41) is respectively arranged on two sides of the combined falling film element (4), and a plurality of falling film flow channels are arranged in parallel.
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| ES2430421T3 (en) * | 2010-09-28 | 2013-11-20 | Rinheat Oy | Falling film evaporator |
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| CN105854734A (en) * | 2016-05-09 | 2016-08-17 | 浙江理工大学 | Row-up pipe film falling melt phase polycondensation method for preparing high-viscosity melt and reactor thereof |
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