Impeller reactor

Abstract

A reactor according to an embodiment of the present invention comprises: a reaction vessel; and an agitator including two or more stages of impellers, wherein the impellers of each stage are positioned at arbitrary intervals along the shaft direction of the agitator, and the uppermost impeller in the agitator is a pitch paddle-type impeller having a blade angle of 5 to 50 degrees with respect to the agitator shaft and can generate an upward flow in the reaction vessel. The reactor can improve fluidity and suppress the generation of fish eyes by employing a pitch paddle-type impeller as the uppermost impeller.

Description

impeller reactor

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0117870, filed September 5, 2023, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to an impeller reactor, and more particularly to a PVC polymerization reactor, and more particularly to a device for improving fluidity and suppressing fish eye formation by applying a specific impeller.

[0004] Fish eye, a quality issue in PVC, causes product defects and is a particularly critical quality issue in products such as films using soft PVC.

[0005] To suppress fish eye formation, PVC particles must be small enough to form a strong break in the flow. Furthermore, the area of ​​low velocity, low turbulence, and low shear rate within the tank must be small.

[0006] In the poor coalescence zone, the particles do not grow by clumping together, and polymerization occurs in a single large particle without disintegration, forming a fish eye particle without pores.

[0007] Accordingly, research is ongoing to optimize the impeller design to reduce the particle size to a certain level and minimize areas where flow is not smooth.

[0008] Accordingly, an embodiment according to the present invention seeks to provide a reactor capable of improving PVC quality by reducing the production of fish eyes by changing the impeller type.

[0009] According to one embodiment of the present invention, a reactor is provided, comprising: a reaction vessel; and a stirrer including two or more stages of impellers; wherein the impellers of each stage are positioned at arbitrary intervals along the axis of the stirrer, and the uppermost impeller in the stirrer is a pitch paddle type with a blade angle of 5 to 50 degrees with respect to the axis of the stirrer, thereby forming an upward flow within the reaction vessel.

[0010] In one embodiment, the top impeller in the agitator may have a blade angle of 10 to 30 degrees with respect to the agitator axis.

[0011] In one embodiment, the impellers of the remaining stages, excluding the top impeller, may be paddle-type with a blade angle of 0 degrees with respect to the agitator axis.

[0012] In one embodiment, the paddle-type agitator may include two to three stages of impellers.

[0013] In one embodiment, the reactor may be a reactor for PVC polymerization reaction.

[0014] By utilizing a reactor having a specific top impeller type, as in one embodiment of the present invention, PVC particles can be made smaller than a certain level and areas with poor flow can be minimized. Accordingly, high-quality PVC can be produced by minimizing the formation of fish eyes.

[0015] Figure 1 is a schematic drawing of a reactor according to one embodiment of the present invention.

[0016] Figures 2 and 3 compare the dead zone ratio according to a comparative example and an embodiment.

[0017] Figures 4 and 5 compare the turbulence dissipation rates according to comparative examples and embodiments.

[0018] Hereinafter, a multi-stage impeller reactor and the like according to a specific implementation example of the invention will be described.

[0019] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0020] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0021] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0022] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0023] Furthermore, the sizes and thicknesses of each component shown in the drawings are arbitrarily indicated for convenience of explanation, and thus the present invention is not necessarily limited to the illustrated components. In the drawings, the thicknesses are enlarged to clearly represent various layers and regions. Furthermore, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0024] Additionally, throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0025] A reactor according to an exemplary embodiment of the present invention comprises a reaction vessel and a stirrer having two or more stages of impellers, wherein the impellers of each stage are positioned at arbitrary intervals along the axial direction of the stirrer, and the uppermost impeller in the stirrer may be a pitch paddle type with a blade angle of 5 to 50 degrees with respect to the axis of the stirrer, and may form an upward flow within the reaction vessel. For example, the reactor may be a reactor for a PVC polymerization reaction as a stirring device for mixing a solid and a liquid.

[0026] In the design of a conventional mixing reactor, the uppermost impeller creates an internal flow by forming a radial flow or a down axial flow, but in the case of a reactor according to an embodiment of the present invention, by making the uppermost impeller a pitched paddle type impeller, an up axial flow can be formed, thereby improving the quality index.

[0027] FIG. 1 is a schematic drawing of a reactor according to one embodiment of the present invention. As shown in FIG. 1, the reactor according to one embodiment of the present invention may include a reaction vessel (120) containing a reactant, a stirrer, and optionally, a cooling baffle (not shown) installed within the reaction vessel (120).

[0028] The above reactor (100) may be, for example, a polymerization reactor for polymerization of a polymer. The reaction vessel (120) is not limited in shape, but may have a cylindrical structure, and includes a cylindrical side wall, a bottom, and a cover to form a space for accommodating a reaction material (110). The reaction vessel (120) may be formed with a double-wall structure (not shown), and a fluid may circulate within the double wall, and heat may be exchanged between the fluid and the reactant. That is, a heat exchange jacket may be installed in the reaction vessel.

[0029] In an exemplary embodiment, the polymerization heat can be maintained at a polymerization temperature of 40 to 100 degrees by dissipating heat using a jacket, a reflux condenser (RC), and a baffle. The baffle (not shown) changes the circumferential flow of the reactants according to the rotation of the impellers (132, 133) into an up-and-down flow to improve mixing of the reactants (110) and effectively remove the heat of reaction, and may be configured as a pipe through which a fluid for heat exchange, such as cooling water, flows. The baffle has a function of controlling the temperature by keeping the temperature of the reactants constant through heat exchange with the reactants, i.e., a heat dissipation function.

[0030] The fluid for heat exchange may have a temperature of approximately 4 to 35 degrees Celsius for low temperatures and approximately 50 to 200 degrees Celsius for high temperatures.

[0031] Baffles may be arranged in multiple numbers along the circumference of the reaction vessel (120) and spaced apart from the inner wall of the reaction vessel (120) and the paddle-type stirrer. The multiple baffles may be installed along the circumference of the reaction vessel (120) at a constant distance from the impeller (132, 133), and may preferably be installed at equal intervals along the circumference.

[0032] The stirrer includes a plurality of impellers (132, 133) installed inside the reaction vessel to rotate the reactants, and a motor having a rotational shaft (131) connected to each impeller (132, 133) to rotate the impellers. The rotational shaft (131) may be located at the center of the reaction vessel (120).

[0033] The impeller (132, 133) is located inside the reaction vessel (120), is coupled to the rotation shaft (131), and rotates by the rotation shaft.

[0034] In an exemplary embodiment, the agitator may include two or three stages of impellers, and at least two agitators may be positioned at a predetermined interval (S1) along the height direction of the rotation axis (131) to form a multi-stage batch reactor.

[0035] Meanwhile, it is important for the batch reaction process to produce a uniform product. The stirrer according to the embodiment of the present invention is positioned at a constant interval (S1) along the height direction of the rotation shaft (131) to form a multi-stage structure, thereby enabling effective stirring of the reactant (110) and maintaining the flow of the reactant uniformly in each zone, compared to a single-stage structure having a single impeller. Therefore, ultimately, a uniform product can be produced, thereby increasing productivity and improving the stability of product quality.

[0036] Specifically, the impellers (132, 133) may be installed as a set of multiple blades at one end of the rotation shaft (131), and may be installed as a set of two or more sets at a constant interval (S1) along the length direction of the rotation shaft for effective stirring of the reactants. One set of impellers (132, 133) may include at least two to four blades. The installation position and number of impellers may be selected in various ways as needed.

[0037] Meanwhile, the stirring performance of the stirrer affects the reaction performance of the batch reactor (100). The stirrer may be configured in the form of a stirring blade of a paddle type, a propeller type, or a turbine type. In particular, in an exemplary embodiment, the uppermost impeller (132) of the stirrer may be a pitch paddle type impeller. For example, it may be an up-pitch paddle type impeller, and may form an up-axial flow to improve the quality index.

[0038] In an exemplary embodiment, the uppermost impeller (132) in the agitator may have a blade angle of 5 to 50 degrees relative to the agitator axis, preferably 5 to 45 degrees, 10 to 30 degrees, or 10 to 20 degrees. In the above range, the occurrence of fish eye can be reduced and excellent quality indicators can be achieved.

[0039] In an exemplary embodiment, the impellers (133) of the remaining stages, excluding the top impeller (132), may be pitchless paddle-type impellers, which may be paddle-type with a blade angle of 0 degrees with respect to the agitator axis. By applying a pitched paddle-type impeller as the top impeller and pitchless paddle-type impellers as the impellers of the remaining stages, an upward axial flow can be formed, thereby improving the quality index.

[0040]

[0041] Example

[0042] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0043] Comparative Example 1: Application of a paddle-paddle impeller

[0044] A mixing tank reactor with a two-stage paddle impeller was prepared. Both two-stage impellers were of the paddle type, and the polymerization heat was maintained at 40°C to 100°C by dissipating heat using a jacket, a reflux condenser (RC), and a cooling baffle.

[0045] Both the first and second stages used paddle impellers with a diameter of 0.1533 m. PVC polymerization was performed at a rotation speed of 550 rpm, and after removing water from the slurry and drying, a quality analysis was conducted on the final PVC resin. The stirring power was maintained at 400 W.

[0046]

[0047] Example 1: Application of a 20° uppitch paddle-paddle impeller

[0048] A mixing tank reactor with a two-stage paddle impeller was prepared, similar to Comparative Example 1. The paddle impellers used in both the first and second stages had a diameter of 0.1533 m, and the upper impeller was a 20° up-pitch paddle, while the lower impeller was a paddle type.

[0049] The driving stirring speed was increased to 590 rpm, which is higher than that of Comparative Example 1, and the stirring power was maintained at the level of 400 W. In the case of the pitch-type paddle, the torque value applied to the fluid is smaller than that of the paddle impeller when operated at the same rpm as the paddle type, so the rpm was increased to operate the stirring power at the same level as that of Comparative Example 1 at 400 W for comparison under equal conditions. All other conditions were the same as those of Comparative Example 1.

[0050]

[0051] Example 2: Application of a 45° uppitch paddle-paddle impeller

[0052] A mixing tank reactor identical to that of Example 1 was prepared, except that the upper impeller was set to a 45° uppitch paddle and the stirring speed was increased to 640 rpm.

[0053]

[0054] Experimental Example: Reactor Quality Analysis

[0055] The quality of the reactors of Comparative Example 1 and Example 1-2 was analyzed.

[0056] 1) When the RC load increases, the role of pulling the volume (droplet) down into the vortex and mixing it is important. However, referring to Table 1 below, it can be confirmed that the average surface velocity of Example 1 (20° uppitch paddle) is lower than that of Comparative Example 1 (paddle).

[0057] Comparative Example 1 Example 1 Example 2 avg_vortex velocity (vol. 0.75) 0.302 m / sec 0.164 m / sec 0.834 m / sec

[0058] Therefore, when applying up-pitch paddles, the reactor quality may appear to be poor, but the internal flow analysis results, referring to FIGS. 3 and 4, show that Example 1 has a smaller dead zone than Comparative Example 1, and referring to FIGS. 5 and 6, show that the turbulence dissipation rate is high, resulting in very high mixing efficiency. Here, the dead zone is a region where the fluid flow velocity is slow, and dead zone % means the volume of the dead zone with respect to the total volume of the reactor.

[0059] In Fig. 2, it can be seen that the flow is not good at more than 27% in the case of Example 2, and the volume % of the dead zone is 16.9% in the case of Example 1, which is improved compared to the comparative example. Fig. 3 shows an internal velocity graph for explaining the results of Fig. 2.

[0060] Meanwhile, in the case of Example 2, the speed was faster than that of Comparative Example 1 at 0.834 m / sec, but since the flow was pushing outward rather than inside the vortex, it was not good for mixing the liquid vcm coming down from the RC.

[0061]

[0062] 2) Quality indicators were predicted using a random forest learning model. Referring to Table 2 below, the result shows that the fish eye (FE) increase / decrease rate in Example 1 was -61% compared to Comparative Example 1. In other words, the number of FEs in Example 1 decreased by -61% compared to Comparative Example 1, confirming the FE reduction effect due to the introduction of an up-pitch paddle-type impeller.

[0063] Comparative Example 1 Example 1 Example 2 y_predict0%-61%4%

[0064] 3) Referring to Table 3, when the upper impeller is made of an up-pitch paddle type, the internal flow is improved and the FE is reduced because the flow between the impellers is very well developed due to the strong axial flow formed in the upper impeller. Meanwhile, from Example 1-2, it can be confirmed that the optimal value is obtained when the blade twist angle in the up-pitch paddle is approximately 20°.

[0065] @ Planar comparison between impellers Example 1 Example 1 Example 2-z (downward direction) mass flow rate (kg / s) 0.000817-0.00126-0.00095

[0066] In this way, as in the embodiment of the present invention, when the uppermost impeller in the agitator uses a pitch paddle-type impeller with a blade angle of 5 to 50 degrees, preferably 10 to 30 degrees, with respect to the agitator axis, the occurrence of fish eye can be reduced.

[0067] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented in various ways within the scope of the claims, the detailed description of the invention, and the attached drawings.

Claims

1. Reaction vessel; and A stirrer including two or more impellers; The impellers of each stage are positioned at arbitrary intervals along the axis of the agitator, A reactor in which the uppermost impeller in the above-mentioned stirrer is a pitch paddle type with a blade angle of 5 to 50 degrees with respect to the stirrer axis, and forms an upward flow within the reaction vessel.

2. In paragraph 1, A reactor in which the uppermost impeller in the above agitator has a blade angle of 10 to 30 degrees with respect to the agitator axis.

3. In paragraph 1, A reactor in which the impellers of the remaining stages, excluding the uppermost impeller, are paddle-type with a blade angle of 0 degrees with respect to the agitator axis.

4. In paragraph 1, A reactor wherein the above paddle-type stirrer comprises two to three stages of impellers.

5. In paragraph 1, The above reactor is a reactor for PVC polymerization reaction.

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