Flash evaporator and long carbon chain nylon salt liquid polymerization equipment

Abstract

The utility model provides a flash evaporator and long carbon chain nylon salt liquid polymerization equipment, and belongs to the field of polymer production. The flash evaporator comprises a horizontal shell, a double-spiral coil pipe is arranged in the shell in the axial direction and comprises a small-diameter double-spiral coil pipe and a large-diameter double-spiral coil pipe which are sequentially connected, the inlet end of the small-diameter double-spiral coil pipe extends out of one end of the shell to serve as a material inlet of the flash evaporator, and the outlet end of the large-diameter double-spiral coil pipe extends out of the other end of the shell to serve as a material outlet of the flash evaporator. The outlet end of the large-diameter double-spiral coil extends out of the other end of the shell to serve as a material outlet of the flash evaporator; and a heat-conducting medium inlet and a heat-conducting medium reflux inlet are formed in the side wall of the shell. According to the flash evaporator disclosed by the utility model, the double-spiral coil pipe is arranged in the shell, and the double-spiral coil pipe is of the expanding structure, so that moisture in a material is evaporated out through the expanding structure of the internal double-spiral coil pipe, and the moisture in the material is evaporated out through multiple times of spirals in the double-spiral coil pipe; and the material and the water vapor reach a gas-liquid balance state in the double-spiral coil pipe, so that the effect of flash evaporation and pressure reduction is achieved.

Description

Technical Field

[0001] The utility model belongs to the field of polymer production, and specifically relates to a flash evaporator and long carbon chain nylon salt solution polymerization equipment. Background Art

[0002] Long-chain nylon, defined as nylon with a carbon chain length of at least ten, exhibits advantages such as low water absorption, corrosion resistance, and wear resistance. Continuous polymerization to produce long-chain nylon involves neutralizing a long-carbon dibasic acid and a long-carbon diamine in ethanol to form a nylon salt. The nylon salt is then filtered and dried to form a powder. This powder is then dissolved in water and subjected to high-pressure prepolymerization, flash evaporation, gas-liquid separation, and final polymerization to produce the long-chain nylon. The flash evaporation process connects the high-pressure and low-pressure sections of the reaction, playing a crucial role in ensuring continuous and stable production.

[0003] At present, the flash evaporator used in long carbon chain nylon polymerization equipment is a shell and tube structure. The shell is equipped with a single spiral coil. Since the diameter of the single spiral coil changes, the pitch needs to be expanded accordingly, resulting in a larger equipment size and a larger footprint under the same pressure drop. Utility Model Content

[0004] The purpose of the utility model is to solve the problems existing in the above-mentioned prior art and to provide a flash evaporator and a long carbon chain nylon salt solution polymerization device.

[0005] The utility model is realized through the following technical solutions:

[0006] A first aspect of the present invention provides a flash evaporator, comprising a horizontal shell, wherein a double spiral coil is axially arranged in the shell, wherein the double spiral coil comprises a small-diameter double spiral coil and a large-diameter double spiral coil connected in sequence, wherein an inlet end of the small-diameter double spiral coil extends from one end of the shell as a material inlet of the flash evaporator, and an outlet end of the large-diameter double spiral coil extends from the other end of the shell as a material outlet of the flash evaporator;

[0007] A heat-conducting medium inlet and a heat-conducting medium return port are provided on the side wall of the shell.

[0008] The further improvement of the present invention is:

[0009] The double spiral coil is formed by winding two expanded heat exchange tubes. The ends of the two expanded heat exchange tubes with smaller inner diameters extend from one end of the shell as the material inlet of the flash evaporator, and the ends with larger inner diameters extend from the other end of the shell as the material outlet of the flash evaporator.

[0010] The further improvement of the present invention is:

[0011] The length of the double spiral coil in the shell is not less than 400m.

[0012] The further improvement of the present invention is:

[0013] The length ratio of the large-diameter double-helix coil and the small-diameter double-helix coil is (2-3):1.

[0014] The further improvement of the present invention is:

[0015] The heat-conducting medium inlet is arranged close to one end of the material inlet, and the heat-conducting medium return port is arranged close to one end of the material outlet.

[0016] The further improvement of the present invention is:

[0017] The heat transfer medium inlet and the heat transfer medium return port are respectively arranged on the upper and lower sides of the shell.

[0018] The second aspect of the present invention provides a long carbon chain nylon salt solution polymerization device, comprising a prepolymerization kettle, a flash evaporator, a front polymerization kettle and a falling film final polymerization reactor connected in sequence.

[0019] The further improvement of the present invention is:

[0020] The pipeline between the prepolymerization kettle and the flash evaporator includes a first main line and two first branch lines connected to the first main line, the first main line is connected to the prepolymerization kettle, and the two first branch lines are respectively connected to the two material inlets of the flash evaporator;

[0021] A first gear pump is provided on the first main line.

[0022] The further improvement of the present invention is:

[0023] The pipeline between the pre-polymerization kettle and the flash evaporator includes two second branch pipelines and a second main line connected to the two second branch pipelines. The two second branch pipelines are respectively connected to the two material outlets of the flash evaporator, and the second main line is connected to the pre-polymerization kettle.

[0024] The further improvement of the present invention is:

[0025] A second gear pump is provided on the pipeline between the pre-polymerization reactor and the falling film final polymerization reactor.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] The flash evaporator of the utility model is provided with a double spiral coil in a shell, and the double spiral coil is provided with an expanded diameter structure. The material passes through the expanded diameter structure of the internal double spiral coil to evaporate the moisture in the material, and passes through the spiral multiple times in the double spiral coil. The material and water vapor reach a gas-liquid equilibrium state in the double spiral coil to achieve the effect of flash evaporation and decompression.

[0028] The utility model adopts a double spiral coil expanded diameter flash evaporator, which can reduce the pressure of the material by increasing the pipe diameter and evaporating the water. The material flows along the spiral coil horizontally along the axis, so that most of the material fills the pipe, increasing the effective heat exchange area, improving the heat transfer efficiency, and evaporating as much water in the material as possible.

[0029] While achieving the same heat exchange effect, the flash evaporator of the utility model has a relatively small equipment size, which reduces the occupied area. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of a flash evaporator in an embodiment of the present utility model;

[0031] Figure 2 This is a schematic diagram of the structure of the long carbon chain nylon salt solution polymerization equipment.

[0032] In the figure, 1, prepolymerization kettle, 2, first gear pump, 3, flash evaporator, 301, shell, 302, double spiral coil, 303, material inlet, 304, material outlet, 305, heat transfer medium inlet, 306, heat transfer medium reflux port, 4, prepolymerization kettle, 5, second gear pump, 6, falling film final polymerization reactor. DETAILED DESCRIPTION

[0033] The present invention is described in further detail below with reference to the accompanying drawings:

[0034] [Example 1]

[0035] like Figure 1 As shown, the embodiment of the present invention provides a flash evaporator 3, comprising a horizontal shell 301, in which a double spiral coil 302 is axially arranged. The double spiral coil 302 comprises a small-diameter double spiral coil and a large-diameter double spiral coil connected in sequence. The inlet end of the small-diameter double spiral coil extends from one end of the shell 301 as a material inlet 303 of the flash evaporator, and the outlet end of the large-diameter double spiral coil extends from the other end of the shell 301 as a material outlet 304 of the flash evaporator.

[0036] A heat transfer medium inlet 305 and a heat transfer medium return port 306 are provided on the side wall of the housing 301 .

[0037] A heat-conducting medium (e.g., heat-conducting oil) is introduced into the shell 301 through the heat-conducting medium inlet 305 and fills the shell. The prepolymer is pumped into the double-helix coil 302 through the material inlet 303. The prepolymer first flows through the small-diameter double-helix coil for heating, and then enters the large-diameter double-helix coil for heating and evaporation. As the pipe diameter increases and the water evaporates, the prepolymer pressure decreases. After the prepolymer drops to normal pressure, it is discharged from the material outlet 304.

[0038] In the present invention, since the prepolymer flashes under the action of the heat-conducting medium, the gas-liquid two-phase is subjected to the dual action of the forced driving force of the pump and gravity in the double spiral coil 302. During this process, the gas phase will have a secondary circulation, which increases the heat exchange area, enhances the heat transfer effect, and increases the residence time, which is conducive to the realization of the flash evaporation process and the stabilization of the gas-liquid two-phase state.

[0039] From the perspective of spatial arrangement, the double-helix tube flash evaporator of the utility model has a compact internal structure and occupies a smaller area while achieving the same flash evaporation effect.

[0040] [Example 2]

[0041] The double helix coil 302 is wound from two expanded heat exchange tubes. The ends with smaller inner diameters of the two expanded heat exchange tubes extend from one end of the shell 301 to serve as the material inlet 303 of the flash evaporator, and the ends with larger inner diameters extend from the other end of the shell 301 to serve as the material outlet 304 of the flash evaporator. Therefore, the flash evaporator 3 has two material inlets 303 and material outlets 304. The prepolymer will be divided into two paths and enter the double helix coil 302 from the two material inlets 303 of the flash evaporator respectively. After flash evaporation under the action of the heat transfer medium, the prepolymer will be discharged from the material outlets 304 corresponding to the material inlets 303.

[0042] [Example 3]

[0043] The length of the double spiral coil 302 in the shell 301 is not less than 400m, so that there can be a pressure loss of about 2MPAG in the pipe. Under the action of the heat-conducting medium, the moisture in the prepolymer is continuously evaporated. When the prepolymer enters the large-diameter double spiral coil section from the small-diameter double spiral coil section, due to the change in curvature, the gas phase flow rate is faster and flows out of the pipe first, resulting in a decrease in the pressure in the spiral coil, thereby realizing the pressure reduction process of the prepolymer.

[0044] In this embodiment, preferably, the length ratio of the large-diameter double-helix coil and the small-diameter double-helix coil is (2-3):1.

[0045] [Example 4]

[0046] The heat conducting medium inlet 305 is arranged near one end of the material inlet 303, and the heat conducting medium return port 306 is arranged near one end of the material outlet 304, and the heat conducting medium inlet 305 and the heat conducting medium return port 306 are respectively arranged on the upper and lower sides of the shell 301. In this way, sufficient heat can be provided starting from the material inlet 303, so that the moisture in the prepolymer evaporates as quickly as possible, thereby improving the flash evaporation effect.

[0047] [Example 5]

[0048] like Figure 2As shown, the embodiment of the present invention also provides a long carbon chain nylon salt solution polymerization device, comprising a prepolymerization reactor 1, a flash evaporator 3, a front polymerization reactor 4 and a falling film final polymerization reactor 6 connected in sequence;

[0049] The pipeline between the prepolymerization kettle 1 and the flash evaporator 3 includes a first main line and two first branch pipelines connected to the first main line. The first main line is connected to the prepolymerization kettle, and the two first branch pipelines are respectively connected to the two material inlets of the flash evaporator. A first gear pump 2 is provided on the first main line.

[0050] The pipeline between the pre-polymerization kettle 4 and the flash evaporator 3 includes two second branch pipelines and a second main line connected to the two second branch pipelines. The two second branch pipelines are respectively connected to the two material outlets of the flash evaporator, and the second main line is connected to the pre-polymerization kettle.

[0051] A second gear pump 5 is provided on the pipeline between the pre-polymerization reactor 3 and the falling film final polymerization reactor 6 .

[0052] Since the prepolymer (polymer) has a high viscosity, the present invention provides a first gear pump and a second gear pump to provide a forced driving force to send the prepolymer (polymer) downstream.

[0053] The prepolymerization kettle, front polymerization kettle and falling film final polymerization reactor all use existing structural equipment, which will not be described in detail here.

[0054] Long-chain nylon salt begins polymerization in a high-pressure prepolymerization reactor. After polymerization is complete, the prepolymer is pumped by the first gear pump to the two material inlets of the flash evaporator. The prepolymer first flows through a small-diameter double-helix coil for heating, then enters a large-diameter double-helix coil for heating and evaporation. As the tube diameter increases and water evaporates, the prepolymer pressure decreases. Once the prepolymer reaches atmospheric pressure, it is discharged from the material outlet and enters the prepolymerization reactor, which operates at atmospheric pressure. During this process, the prepolymer chain grows. The prepolymer, driven by the second gear pump, enters the falling-film final polymerization reactor, which operates under vacuum conditions. Finally, the final polymer is pelletized, dried, and packaged to produce the nylon product. The flash evaporator, serving as the link between prepolymerization and prepolymerization, is required to relieve pressure within the prepolymerization reactor, playing a key role in ensuring stable and continuous production.

[0055] In the description of this utility model, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0056] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0057] The above technical solution is only one implementation method of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A flash evaporator, characterized in that: The flash evaporator comprises a horizontal shell, wherein a double spiral coil is axially arranged in the shell, wherein the double spiral coil comprises a small-diameter double spiral coil and a large-diameter double spiral coil connected in sequence, wherein the inlet end of the small-diameter double spiral coil extends from one end of the shell as a material inlet of the flash evaporator, and the outlet end of the large-diameter double spiral coil extends from the other end of the shell as a material outlet of the flash evaporator; A heat-conducting medium inlet and a heat-conducting medium return port are provided on the side wall of the shell.

2. The flash evaporator according to claim 1, characterized in that The double spiral coil is formed by winding two expanded heat exchange tubes. The ends of the two expanded heat exchange tubes with smaller inner diameters extend from one end of the shell as the material inlet of the flash evaporator, and the ends with larger inner diameters extend from the other end of the shell as the material outlet of the flash evaporator.

3. The flash evaporator according to claim 1, characterized in that The length of the double spiral coil in the shell is not less than 400m.

4. The flash evaporator according to claim 1, characterized in that The length ratio of the large-diameter double-helix coil and the small-diameter double-helix coil is (2-3):

1.

5. The flash evaporator according to claim 1, characterized in that The heat-conducting medium inlet is arranged close to one end of the material inlet, and the heat-conducting medium return port is arranged close to one end of the material outlet.

6. The flash evaporator according to claim 5, characterized in that The heat transfer medium inlet and the heat transfer medium return port are respectively arranged on the upper and lower sides of the shell.

7. A long carbon chain nylon salt solution polymerization device, characterized in that: The process comprises a prepolymerization reactor, a flash evaporator, a front polymerization reactor and a falling film final polymerization reactor which are connected in sequence.

8. The polymerization device according to claim 7, characterized in that The pipeline between the prepolymerization kettle and the flash evaporator includes a first main line and two first branch lines connected to the first main line, the first main line is connected to the prepolymerization kettle, and the two first branch lines are respectively connected to the two material inlets of the flash evaporator; A first gear pump is provided on the first main line.

9. The polymerization device according to claim 7, characterized in that The pipeline between the pre-polymerization kettle and the flash evaporator includes two second branch pipelines and a second main line connected to the two second branch pipelines. The two second branch pipelines are respectively connected to the two material outlets of the flash evaporator, and the second main line is connected to the pre-polymerization kettle.

10. The polymerization device according to claim 7, characterized in that A second gear pump is provided on the pipeline between the pre-polymerization reactor and the falling film final polymerization reactor.

Images