A method of heating a low solids, low boiling point polymer solution

Abstract

The application provides a heating method of a low-solid-content low-boiling-point polymer solution, which comprises the following steps: feeding the polymer solution into the tube side of a two-section shell-and-tube heat exchanger in a parallel flow mode; the shell side of the heat exchanger comprises an inlet section shell side and an outlet section shell side; the heating medium of the heat exchanger comprises a first medium and a second medium; the first medium is fed into the inlet section shell side and has an inlet temperature of T in‑up ; the second medium is fed into the outlet section shell side and has an inlet temperature of T in‑down ; T in‑up < bubble point temperature of the solvent of the polymer solution < T in‑down ; and the gas holdup of the polymer solution at the outlet of the heat exchanger is less than or equal to 50%. In the application, based on the parallel flow shell-and-tube heat exchanger, by controlling the inlet temperature of the first medium in the inlet section shell side and the inlet temperature of the second medium in the outlet section shell side, and by controlling the gas holdup of the polymer solution at the outlet, the latent heat of vaporization is provided while the temperature of the solution is increased, and the polymer solution is prevented from being blocked in the heat exchanger due to a large amount of vaporization at the inlet end.

Description

Technical Field

[0001] This invention relates to the field of polymer polymerization technology, specifically to a heating method for low-solids-content, low-boiling-point polymer solutions. Background Technology

[0002] High-value-added polymers are often produced using solution polymerization or homogeneous bulk polymerization processes, such as POE, polybutene-1, ethylene propylene rubber, polytetramethyl-1-pentene, and SEBS. The output from solution or homogeneous bulk polymerization reactors is typically a polymer solution with low solids content and a low boiling point, requiring solvent removal in the post-processing unit. The commonly used method is to heat the polymer solution and flash-evaporate it to remove the solvent, a process known as the devolatilization unit.

[0003] Patent document (CN116351088) A) A system for removing volatiles from polymers is disclosed, comprising: a flash evaporation unit, located downstream of a reactor forming the polymer, for receiving and flash evaporating a polymer solution from the reactor to obtain a first volatile gas phase and a pre-devoured polymer solution; a static devouring unit, located downstream of the flash evaporation unit, comprising at least two static devourers connected in series, for receiving and heating the pre-devoured polymer solution from the flash evaporation unit to obtain a second volatile gas phase and a statically devoured polymer solution; a dynamic devouring unit, located downstream of the static devouring unit, for receiving the statically devoured polymer solution from the static devouring unit and heating it in a turbulent state to obtain a third volatile gas phase and a dynamically devoured polymer solution; and a volatile recovery unit, connected to the static and dynamic devouring units, for receiving the second and third volatile gas phases; wherein the first volatile gas phase comprises unreacted light monomer components in the polymer solution, the second volatile gas phase comprises the solvent in the polymer solution, and the third volatile gas phase comprises heavy components in the polymer solution. The system includes a flash evaporation unit, a static devolatification unit, a dynamic devolatification unit, and a volatile matter recovery unit. The operation of these multiple units is complex, with many influencing factors, making them difficult to control.

[0004] Using shell-and-tube heat exchangers is a conventional method for heating low-solids-content, low-boiling-point polymer solutions. However, shell-and-tube heat exchangers have a relatively small specific surface area, resulting in a large footprint and high equipment investment. Furthermore, the large pressure drop can cause significant fluctuations in production conditions, and the design is complex. Shell-and-tube heat exchangers, on the other hand, have a large specific surface area, are easy to scale up, and have a low pressure drop. However, when using conventional shell-and-tube heat exchangers to heat low-solids-content, low-boiling-point polymer solutions, a large amount of solvent vaporization can occur at the inlet of the heat exchanger, leading to residual polymer clogging of the tubes and a sharp decrease in heat exchange efficiency.

[0005] Therefore, in order to overcome the technical difficulties such as the large-scale vaporization of solvent in the polymer solution, which can clog the heat exchanger and result in insufficient heat exchange capacity of the solution, thus failing to meet the requirements for solvent removal, when heating low-boiling-point polymer solutions in tube heat exchangers, it is urgent to develop an efficient heating method for low-solid-content, low-boiling-point polymer solutions. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a heating method for low-solid-content, low-boiling-point polymer solutions based on a shell-and-tube heat exchanger. The provided heating method can achieve efficient heat exchange of low-solid-content, low-boiling-point polymer solutions and is suitable for long-term stable operation.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The first aspect of this invention provides a method for heating a low-solids-content, low-boiling-point polymer solution. The method includes the following steps: heating the polymer solution by passing it through the tube side of a two-stage shell-and-tube heat exchanger with a common tube side; the shell side of the two-stage shell-and-tube heat exchanger includes an inlet shell side and an outlet shell side; the heating medium of the shell-and-tube heat exchanger includes a first medium and a second medium, wherein the first medium and the second medium may be the same or different; the first medium is introduced into the inlet shell side and its inlet temperature is T. in-up The second medium is introduced into the shell side of the outlet section and its inlet temperature is T. in-down T in-up <bubble point temperature of the solvent in the polymer solution<T in-down The gas holdup of the polymer solution at the outlet of the two-stage tube heat exchanger is ≤50%.

[0009] In this invention, a two-stage shell-and-tube heat exchanger based on a common tube side is used, wherein the inlet temperature of the first medium in the shell side of the inlet section is controlled to be T. in-up The inlet temperature of the second medium in the shell side of the outlet section is T. in-down Furthermore, by controlling the gas holdup of the polymer solution at the outlet of the two-stage tube heat exchanger, the solution temperature is increased while providing a certain amount of latent heat of vaporization, ensuring sufficient heat exchange for the polymer solution, and preventing the inlet end of the polymer solution from being blocked by excessive vaporization.

[0010] In some embodiments of the present invention, the boiling point of the polymer solution is -10 to 120°C; the solid content of the polymer solution is less than 50%.

[0011] In some embodiments of the present invention, the polymer solution is selected from POE, polybutene-1, ethylene propylene rubber, polytetramethyl-1-pentene, or SEBS polymerization reaction solution.

[0012] In some embodiments of the present invention, T in-up The temperature is set to be 2-5°C lower than the bubble point temperature of the solvent in the polymer solution, preferably 2-3°C.

[0013] In some embodiments of the present invention, T in-down Set to a temperature higher than the polymer solution outlet temperature (T) out-PB Temperatures above 2℃ are preferred, T is preferred. in-down Set the temperature to be 5℃ to 60℃ higher than the polymer solution outlet temperature, for example, 20℃, 25℃, 30℃, 35℃, 40℃, 48℃, 50℃, 60℃.

[0014] In some embodiments of the present invention, the gas content of the polymer solution at the outlet of the heat exchanger is 20-50%, for example 20%, 25%, 30%, 35%, 40%, 45%, 50%, preferably 30-40%.

[0015] In this invention, the pressure of the polymer solution at the outlet of the heat exchanger is controlled. Compared with the traditional shell-and-tube heat exchange process, this heat exchange method has a relatively small pressure drop in the heat exchanger and is less difficult to operate.

[0016] In some embodiments of the present invention, the pressure of the polymer solution at the outlet of the heat exchanger is 15-30 bar, for example 15 bar, 20 bar, 25 bar, 30 bar, preferably 25-30 bar.

[0017] In some embodiments of the present invention, the inlet temperature of the first medium in the shell side of the inlet section is 100-150°C, the reflux temperature of the first medium in the shell side of the inlet section is 90-145°C, and the flow rate ratio of the polymer solution to the flow rate of the first medium is 1:(1-100), for example 1:1, 1:2, 1:5, 1:7.5, 1:10, 1:20, 1:30, 1:50, 1:100, preferably 1:(2-50).

[0018] In some embodiments of the present invention, the inlet temperature of the second medium in the shell side of the outlet section is 140-250°C, the reflux temperature of the second medium in the shell side of the outlet section is 135-230°C, and the flow rate ratio of the polymer solution to the flow rate of the second medium is 1:(0.5-50), for example 1:0.5, 1:1, 1:1.5, 1:1.75, 1:2, 1:3, 1:5, 1:10, 1:20, 1:30, 1:50, preferably 1:(0.8-20).

[0019] In some embodiments of the present invention, the polymer solution inlet temperature is 30-120°C and the polymer solution outlet temperature is 120-200°C.

[0020] In some embodiments of the present invention, the first medium and the second medium are not mixed.

[0021] In some embodiments of the present invention, in the two-section tube heat exchanger with a common tube pass, the tube pass includes an inlet section tube and an outlet section tube, the inlet section tube and the outlet section tube being formed as an integral tube; or the inlet section tube and the outlet section tube are formed as two sections of tube, the outlet end of the first section tube serving as the inlet section tube and the inlet end of the second section tube serving as the outlet section tube are fixed by a distribution plate, so that the material in the first section tube enters the corresponding second section tube.

[0022] In some embodiments of the present invention, the pressure of the polymer solution at the outlet of the heat exchanger is controlled by a heat exchanger outlet pressure control facility.

[0023] In some embodiments of the present invention, the heat exchanger outlet pressure control device is a pressure control valve.

[0024] In some embodiments of the present invention, the bubble point temperature of the polymer solution is obtained by simulation using Aspen software, given the known pressure of the polymer solution at the outlet of the heat exchanger.

[0025] In some embodiments of the present invention, the number of tubes in the tube heat exchanger is 20-1000, the inner diameter of the tubes is 10-100mm, the length of the inlet section tubes is 500-20000mm, and the length of the outlet section tubes is 500-20000mm.

[0026] A second aspect of the present invention provides a method for recovering a polymer solution, the method comprising the following steps:

[0027] (1) The polymer solution is treated by the above heating method to obtain the heated polymer material;

[0028] (2) In a flash evaporator, the polymer material is flash-evaporated to obtain a gas phase component and a liquid phase component;

[0029] (3) The gas phase component is sent to the light component recovery unit, and the liquid phase component is sent to the solvent separation unit for further solvent separation.

[0030] The flash evaporation method and solvent separation method are conventional operating methods in the field, and the present invention does not particularly limit them.

[0031] The technical solution provided by this invention has the following beneficial effects:

[0032] 1) The inlet temperature of the first medium in the shell side of the inlet section is T. in-upThe temperature is lower than the bubble point temperature of the polymer solution solvent, ensuring that the polymer solution is in a homogeneous state at the inlet section of the tube heat exchanger, thus avoiding large-scale vaporization of the polymer solution at the inlet end and blockage of the tubes.

[0033] 2) The inlet temperature of the second medium in the shell side of the outlet section is T. in-down The temperature is higher than the bubble point temperature of the solvent in the polymer solution, ensuring that there is a certain amount of vaporization in the outlet section of the tube heat exchanger. This increases the solution temperature and provides a certain amount of latent heat of vaporization, ensuring sufficient heat exchange for the polymer solution.

[0034] 3) The inlet section tubes and the outlet section tubes share the same pipeline or the inlet section tubes and the outlet section tubes correspond one-to-one, so that the high solid content polymer solution in the outlet section can be continuously carried away from the tubes by the dilute solution in the inlet section, ensuring the tubes are unobstructed and maintaining a high heat exchange efficiency.

[0035] 4) Maintaining a low to medium gas holdup (≤50%) at the outlet section can ensure stable control of the heat exchanger outlet pressure control system. Detailed Implementation

[0036] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the materials used in the embodiments are commercially available products or conventional products that can be synthesized by known methods.

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0038] Example 1

[0039] A heating method for a low-solids-content, low-boiling-point polymer solution includes: using 1-butene monomer as a solvent, a homogeneous polybutene-1 bulk polymer is used as the low-solids-content, low-boiling-point polymer; the polymer solids content at reactor discharge is 20%, the flow rate of the polymer solution is 2 t / h, the inlet temperature of the polymer solution is 75℃, and after heat exchange in a shell-and-tube heat exchanger, it enters a flash tank to remove unpolymerized 1-butene monomer. The heat exchanger uses hot oil I and hot oil II for heating. The structural parameters of the heat exchanger are: 630 tubes, 25 mm inner diameter, 3000 mm inlet tube length, 1800 mm outlet tube length, and the inlet and outlet tubes are shared. Hot oil I and hot oil II are simply the same type of hot oil at different temperatures. The polymer solution inlet temperature, polymer solution outlet temperature, hot oil I inlet temperature in the inlet shell side, hot oil I reflux temperature in the inlet shell side, hot oil II inlet temperature in the outlet shell side, and hot oil II reflux temperature in the outlet shell side are all measured using thermocouple thermometers. The pressure at the heat exchanger outlet is measured using a diaphragm pressure gauge.

[0040] The heat absorption Q of the polymer solution is calculated using the following formula (1), and the gas holdup X at the outlet of the polymer solution is calculated using the following formula (2):

[0041] Q = (M oil-up ×(T in-up -T out-up )+M oil-down ×(T in-down -T out-down ))×C p-oil / M PB (1)

[0042] X = (Q - (T) out-PB -T in-PB )×C p-PB ) / L PB (2)

[0043] Among them, M oil-up T is the flow rate of hot oil I. in-up The inlet temperature of hot oil I in the shell side of the inlet section, T out-up The reflux temperature of hot oil I in the shell side of the inlet section; M oil-down For the flow rate of hot oil II, T in-down The inlet temperature of hot oil II in the shell side of the outlet section, T out-down The reflux temperature of hot oil II in the shell side of the outlet section; M PB T is the flow rate of the polymer solution. in-PB T is the inlet temperature of the polymer solution. out-PB The outlet temperature of the polymer solution; C p-oil C is the isobaric specific heat capacity of hot oil. p-PB The isobaric specific heat capacity of polybutene-1 solution; LPB The latent heat of vaporization of butene-1.

[0044] Isobaric specific heat capacity of hot oil (C) p-oil 2.4 kJ / (kg·℃);

[0045] The latent heat of vaporization of butene-1 (L PB 390 kJ / kg;

[0046] The isobaric specific heat capacity (C) of polybutene-1 solution p-PB The effective temperature and humidity (TQH) is 2.8 kJ / (kg·℃).

[0047] The process parameters that need to be controlled are as follows:

[0048] Heat exchanger outlet pressure (barg): 28;

[0049] Butene-1 has a bubble point temperature of 130°C at a pressure of 28 barg.

[0050] Flow rate of hot oil I (M oil-up (t / h): 15;

[0051] The inlet temperature (T) of hot oil I in the shell side of the inlet section in-up (℃): 128;

[0052] The reflux temperature of hot oil I in the inlet shell side (T) out-up (℃): 120;

[0053] Flow rate of hot oil II (M oil-down (t / h): 4;

[0054] The inlet temperature of hot oil II in the shell side of the outlet section (T) in-down (℃): 190;

[0055] Reflux temperature of hot oil II in the shell side of the outlet section (T) out-down (℃): 140;

[0056] Flow rate of polymer solution (M PB (t / h): 2;

[0057] Polymer solution heat exchange effect:

[0058] Polymer solution inlet temperature (T) in-PB (℃): 75;

[0059] polymer solution outlet temperature (T) out-PB (℃): 165;

[0060] The heat absorbed by the polymer solution, Q (kJ / kg), is 384.

[0061] The gas holdup X (%) of the polymer solution at the outlet of the two-stage tube heat exchanger is 33.8.

[0062] The temperature at the outlet section of the heat exchanger is stable, with a temperature fluctuation range of less than ±10%, and the pressure fluctuation range at the outlet of the heat exchanger is less than ±0.5 barg, indicating stable operation of the heat exchanger.

[0063] Example 2

[0064] A heating method for a low-solids-content, low-boiling-point polymer solution includes: using 1-butene monomer as a solvent, a homogeneous polybutene-1 bulk polymer is used as the low-solids-content, low-boiling-point polymer; the polymer solids content at reactor discharge is 20%, the flow rate of the polymer solution is 2 t / h, the inlet temperature of the polymer solution is 75℃, and after heat exchange in a shell-and-tube heat exchanger, it enters a flash tank to remove unpolymerized 1-butene monomer. The heat exchanger uses hot oil I and hot oil II for heating. The structural parameters of the heat exchanger are: 630 tubes, 25 mm inner diameter, 3000 mm inlet tube length, 1800 mm outlet tube length, and the inlet and outlet tubes are shared. Hot oil I and hot oil II are simply the same type of hot oil at different temperatures. The polymer solution inlet temperature, polymer solution outlet temperature, hot oil I inlet temperature in the inlet shell side, hot oil I reflux temperature in the inlet shell side, hot oil II inlet temperature in the outlet shell side, and hot oil II reflux temperature in the outlet shell side are all measured using thermocouple thermometers. The pressure at the heat exchanger outlet is measured using a diaphragm pressure gauge.

[0065] The heat absorption Q of the polymer solution is calculated using the following formula (1), and the gas holdup X at the outlet of the polymer solution is calculated using the following formula (2):

[0066] Q = (M oil-up ×(T in-up -T out-up )+M oil-down ×(T in-down -T out-down ))×C p-oil / M PB (1)

[0067] X = (Q - (T) out-PB -T in-PB )×C p-PB ) / L PB (2)

[0068] Among them, M oil-up T is the flow rate of hot oil I. in-up The inlet temperature of hot oil I in the shell side of the inlet section, T out-up The reflux temperature of hot oil I in the shell side of the inlet section; M oil-down For the flow rate of hot oil II, T in-downThe inlet temperature of hot oil II in the shell side of the outlet section, T out-down The reflux temperature of hot oil II in the shell side of the outlet section; M PB T is the flow rate of the polymer solution. in-PB T is the inlet temperature of the polymer solution. out-PB The outlet temperature of the polymer solution; C p-oil C is the isobaric specific heat capacity of hot oil. p-PB The isobaric specific heat capacity of polybutene-1 solution; L PB The latent heat of vaporization of butene-1.

[0069] Isobaric specific heat capacity of hot oil (C) p-oil 2.4 kJ / (kg·℃);

[0070] The latent heat of vaporization of butene-1 (L PB 390 kJ / kg;

[0071] The isobaric specific heat capacity (C) of polybutene-1 solution p-PB The effective temperature and humidity (TQH) is 2.8 kJ / (kg·℃).

[0072] The process parameters that need to be controlled are as follows:

[0073] Heat exchanger outlet pressure (barg): 28;

[0074] Butene-1 has a bubble point temperature of 130°C at a pressure of 28 barg.

[0075] Flow rate of hot oil I (M oil-up (t / h): 15;

[0076] The inlet temperature (T) of hot oil I in the shell side of the inlet section in-up (℃): 128;

[0077] The reflux temperature of hot oil I in the inlet shell side (T) out-up (℃): 120;

[0078] Flow rate of hot oil II (M oil-down (t / h): 3.5;

[0079] The inlet temperature of hot oil II in the shell side of the outlet section (T) in-down (℃): 215;

[0080] Reflux temperature of hot oil II in the shell side of the outlet section (T) out-down (℃): 151;

[0081] Flow rate of polymer solution (M PB (t / h): 2;

[0082] Polymer solution heat exchange effect:

[0083] Polymer solution inlet temperature (T) in-PB (℃): 75;

[0084] polymer solution outlet temperature (T) out-PB (℃): 167;

[0085] The heat absorbed by the polymer solution, Q (kJ / kg), is 412.8.

[0086] The gas holdup X (%) of the polymer solution at the outlet of the two-stage tube heat exchanger is 39.8.

[0087] The temperature at the outlet section of the heat exchanger is stable, with a temperature fluctuation range of less than ±10%, and the pressure fluctuation range at the outlet of the heat exchanger is less than ±0.5 barg, indicating that the heat exchanger can operate stably.

[0088] Example 3

[0089] A heating method for a low-solids-content, low-boiling-point polymer solution includes: using 1-butene monomer as a solvent, a homogeneous polybutene-1 bulk polymer is used as the low-solids-content, low-boiling-point polymer; the polymer solids content at reactor discharge is 20%, the flow rate of the polymer solution is 2 t / h, the inlet temperature of the polymer solution is 75℃, and after heat exchange in a shell-and-tube heat exchanger, it enters a flash tank to remove unpolymerized 1-butene monomer. The heat exchanger uses high-temperature condensate (inlet section heat exchanger) and hot oil (outlet section heat exchanger) for heating. The structural parameters of the heat exchanger used are: 630 tubes, 25 mm inner diameter of the tubes, 3000 mm length of the inlet section tubes, 1800 mm length of the outlet section tubes, and the inlet and outlet sections share a common tube configuration. The inlet temperature of the polymer solution, the outlet temperature of the polymer solution, the inlet temperature of the high-temperature condensate in the shell side of the inlet section, the reflux temperature of the high-temperature condensate in the shell side of the inlet section, the inlet temperature of the hot oil in the shell side of the outlet section, and the reflux temperature of the hot oil in the shell side of the outlet section are all measured using thermocouple thermometers. The pressure at the outlet of the heat exchanger is measured using a diaphragm pressure gauge.

[0090] The heat absorption Q of the polymer solution is calculated using the following formula (1), and the gas holdup X at the outlet of the polymer solution is calculated using the following formula (2):

[0091] Q = (M water-up ×(T in-up -T out-up )×C p-water +M oil-down ×(T in-down -T out-down )×C p-oil ) / M PB (1)

[0092] X = (Q - (T) out-PB -Tin-PB )×C p-PB ) / L PB (2)

[0093] Among them, M water-up T is the flow rate of the high-temperature condensate. in-up The inlet temperature of the condensate in the shell side of the inlet section, T out-up The reflux temperature of the condensate in the shell side at the inlet; M oil-down T is the flow rate of hot oil. in-down The inlet temperature of hot oil in the shell side of the outlet section, T out-down The reflux temperature of the hot oil in the shell side of the outlet section; M PB T is the flow rate of the polymer solution. in-PB T is the inlet temperature of the polymer solution. out-PB The outlet temperature of the polymer solution; C p-oil C is the isobaric specific heat capacity of hot oil. p-water C is the isobaric specific heat capacity of the condensate. p-PB The isobaric specific heat capacity of polybutene-1 solution; L PB The latent heat of vaporization of butene-1.

[0094] Isobaric specific heat capacity of hot oil (C) p-oil 2.4 kJ / (kg·℃);

[0095] isobaric specific heat capacity of condensate (C p-water 4.2 kJ / (kg·℃);

[0096] The latent heat of vaporization of butene-1 (L PB 390 kJ / kg;

[0097] The isobaric specific heat capacity (C) of polybutene-1 solution p-PB The effective temperature and humidity (TQH) is 2.8 kJ / (kg·℃).

[0098] The process parameters that need to be controlled are as follows:

[0099] Heat exchanger outlet pressure (barg): 28;

[0100] Butene-1 has a bubble point temperature of 130°C at a pressure of 28 barg.

[0101] Flow rate of high-temperature condensate (M water-up (t / h): 10;

[0102] The inlet temperature (T) of the high-temperature condensate in the shell side of the inlet section in-up (℃): 125;

[0103] The reflux temperature of the high-temperature condensate in the shell side at the inlet (T) out-up (℃): 120;

[0104] Hot oil flow rate (M oil-down (t / h): 4;

[0105] The inlet temperature of hot oil in the shell side of the outlet section (T) in-down (℃): 190;

[0106] Reflux temperature of hot oil in the shell side of the outlet section (T) out-down (℃): 140;

[0107] Flow rate of polymer solution (M PB (t / h): 2;

[0108] Polymer solution heat exchange effect:

[0109] Polymer solution inlet temperature (T) in-PB (℃): 75;

[0110] polymer solution outlet temperature (T) out-PB (℃): 155;

[0111] The heat absorbed by the polymer solution, Q (kJ / kg), is 345.

[0112] The gas holdup X (%) of the polymer solution at the outlet of the two-stage tube heat exchanger is 31.0.

[0113] The temperature at the outlet section of the heat exchanger is stable, with a temperature fluctuation range of less than ±10%, and the pressure fluctuation range at the outlet of the heat exchanger is less than ±0.5 barg, indicating stable operation of the heat exchanger.

[0114] Comparative Example 1

[0115] A heating method for a low-solids-content, low-boiling-point polymer solution includes: using 1-butene monomer as a solvent, a homogeneous polybutene-1 bulk polymer is employed as the low-solids-content, low-boiling-point polymer; the reactor discharge polymer has a solids content of 20%, the polymer solution flow rate is 2 t / h, the polymer solution inlet temperature is 75℃, and after heat exchange in a shell-and-tube heat exchanger, it enters a flash tank to remove unpolymerized 1-butene monomer. The heat exchanger uses hot oil I and hot oil II for heating. The structural parameters of the heat exchanger are: 630 tubes, 25 mm inner diameter, 3000 mm inlet section tube length, 1800 mm outlet section tube length, and the inlet and outlet sections share a common tube configuration. Hot oil I and hot oil II are simply the same type of hot oil at different temperatures. The polymer solution inlet temperature, polymer solution outlet temperature, the inlet shell-side temperature of hot oil I, and the inlet shell-side temperature of hot oil II are all measured using thermocouple thermometers, and the heat exchanger outlet pressure is measured using a diaphragm pressure gauge.

[0116] The heat absorption Q of the polymer solution is calculated using the following formula (1), and the gas holdup X at the outlet of the polymer solution is calculated using the following formula (2):

[0117] Q = (M oil-up ×(T in-up -T out-up )+M oil-down ×(T in-down -T out-down ))×C p-oil / M PB (1)

[0118] X = (Q - (T) out-PB -T in-PB )×C p-PB ) / L PB (2)

[0119] Among them, M oil-up T is the flow rate of hot oil I. in-up The inlet temperature of hot oil I in the shell side of the inlet section, T out-up The reflux temperature of hot oil I in the shell side of the inlet section; M oil-down For the flow rate of hot oil II, T in-down The inlet temperature of hot oil II in the shell side of the outlet section, T out-down The reflux temperature of hot oil II in the shell side of the outlet section; M PB T is the flow rate of the polymer solution. in-PB T is the inlet temperature of the polymer solution. out-PB The outlet temperature of the polymer solution; C p-oil C is the isobaric specific heat capacity of hot oil. p-PB The isobaric specific heat capacity of polybutene-1 solution; L PB The latent heat of vaporization of butene-1.

[0120] Isobaric specific heat capacity of hot oil (C) p-oil 2.4 kJ / (kg·℃);

[0121] The latent heat of vaporization of butene-1 (L PB 390 kJ / kg;

[0122] The isobaric specific heat capacity (C) of polybutene-1 solution p-PB The effective temperature and humidity (TQH) is 2.8 kJ / (kg·℃).

[0123] The process parameters that need to be controlled are as follows:

[0124] Heat exchanger outlet pressure (barg): 28;

[0125] Butene-1 has a bubble point temperature of 130°C at a pressure of 28 barg.

[0126] Flow rate of hot oil I (M oil-up (t / h): 15;

[0127] The inlet temperature (T) of hot oil I in the shell side of the inlet section in-up (℃): 140;

[0128] Flow rate of hot oil II (M oil-down (t / h): 4;

[0129] The inlet temperature of hot oil II in the shell side of the outlet section (T) in-down (℃): 190;

[0130] Flow rate of polymer solution (M PB (t / h): 2;

[0131] Polymer solution heat exchange effect:

[0132] Polymer solution inlet temperature (T) in-PB (℃): 75;

[0133] polymer solution outlet temperature (T) out-PB (℃): The initial temperature gradually decreased from 175℃ to 85℃.

[0134] Inlet temperature of hot oil I inlet section shell side (T) in-up The temperature of the polymer solution outlet gradually decreased from 175°C to 85°C after running for half an hour, exceeding the bubble point temperature of butene-1. This indicates that the heat exchanger is significantly clogged and the above operating parameters cannot guarantee the long-term stable operation of the heat exchange equipment.

[0135] Comparative Example 2

[0136] A heating method for a low-solids-content, low-boiling-point polymer solution includes: using 1-butene monomer as a solvent, a homogeneous polybutene-1 bulk polymer is used as the low-solids-content, low-boiling-point polymer; the polymer solids content at reactor discharge is 20%, the flow rate of the polymer solution is 2 t / h, the inlet temperature of the polymer solution is 75℃, and after heat exchange in a shell-and-tube heat exchanger, it enters a flash tank to remove unpolymerized 1-butene monomer. The heat exchanger uses hot oil I and hot oil II for heating. The structural parameters of the heat exchanger are: 630 tubes, 25 mm inner diameter, 3000 mm inlet tube length, 1800 mm outlet tube length, and the inlet and outlet tubes are shared. Hot oil I and hot oil II are simply the same type of hot oil at different temperatures. The polymer solution inlet temperature, polymer solution outlet temperature, hot oil I inlet temperature in the inlet shell side, hot oil I reflux temperature in the inlet shell side, hot oil II inlet temperature in the outlet shell side, and hot oil II reflux temperature in the outlet shell side are all measured using thermocouple thermometers. The pressure at the heat exchanger outlet is measured using a diaphragm pressure gauge.

[0137] The heat absorption Q of the polymer solution is calculated using the following formula (1), and the gas holdup X at the outlet of the polymer solution is calculated using the following formula (2):

[0138] Q = (M oil-up ×(T in-up -T out-up )+M oil-down ×(T in-down -T out-down ))×C p-oil / M PB (1)

[0139] X = (Q - (T) out-PB -T in-PB )×C p-PB ) / L PB (2)

[0140] Among them, M oil-up T is the flow rate of hot oil I. in-up The inlet temperature of hot oil I in the shell side of the inlet section, T out-up The reflux temperature of hot oil I in the shell side of the inlet section; M oil-down For the flow rate of hot oil II, T in-down The inlet temperature of hot oil II in the shell side of the outlet section, T out-down The reflux temperature of hot oil II in the shell side of the outlet section; M PB T is the flow rate of the polymer solution. in-PB T is the inlet temperature of the polymer solution. out-PB The outlet temperature of the polymer solution; C p-oil C is the isobaric specific heat capacity of hot oil. p-PB The isobaric specific heat capacity of polybutene-1 solution; L PB The latent heat of vaporization of butene-1.

[0141] Isobaric specific heat capacity of hot oil (C) p-oil 2.4 kJ / (kg·℃);

[0142] The latent heat of vaporization of butene-1 (L PB 390 kJ / kg;

[0143] The isobaric specific heat capacity (C) of polybutene-1 solution p-PB The effective temperature and humidity (TQH) is 2.8 kJ / (kg·℃).

[0144] The process parameters that need to be controlled are as follows:

[0145] Heat exchanger outlet pressure (barg): 28;

[0146] Butene-1 has a bubble point temperature of 130°C at a pressure of 28 barg.

[0147] Flow rate of hot oil I (M oil-up (t / h): 15;

[0148] The inlet temperature (T) of hot oil I in the shell side of the inlet section in-up (℃): 128;

[0149] The reflux temperature of hot oil I in the inlet shell side (T) out-up (℃): 120;

[0150] Flow rate of hot oil II (M oil-down (t / h): 9;

[0151] The inlet temperature of hot oil II in the shell side of the outlet section (T) in-down (℃): 190;

[0152] Reflux temperature of hot oil II in the shell side of the outlet section (T) out-down (℃): 158;

[0153] Flow rate of polymer solution (M PB (t / h): 2;

[0154] Polymer solution heat exchange effect:

[0155] Polymer solution inlet temperature (T) in-PB (℃): 75;

[0156] polymer solution outlet temperature (T) out-PB (℃): 170;

[0157] The heat absorbed by the polymer solution, Q (kJ / kg), is 489.6.

[0158] The gas holdup X (%) of the polymer solution at the outlet of the two-stage tube heat exchanger is 57.3.

[0159] The flow rate of hot oil II at the outlet section is too high, and the gas holdup of the polymer solution at the outlet of the two-stage shell and tube heat exchanger exceeds the limit. The pressure fluctuation at the heat exchanger outlet is as high as 5 barg, and the outlet pressure control valve operates frequently, which has a significant negative impact on the stable control of the upstream system pressure.

[0160] Comparative Example 3

[0161] A heating method for a low-solids-content, low-boiling-point polymer solution includes: using 1-butene monomer as a solvent, a homogeneous polybutene-1 bulk polymer is employed as the low-solids-content, low-boiling-point polymer; the polymer solids content at reactor discharge is 20%, the flow rate of the polymer solution is 2 t / h, the inlet temperature of the polymer solution is 75℃, and after heat exchange in a shell-and-tube heat exchanger, it enters a flash tank to remove unpolymerized 1-butene monomer. The heat exchanger is heated by hot oil I. The heat exchanger used is a conventional shell-and-tube heat exchanger with the following main structural parameters: 630 tubes, 25 mm inner diameter, and 4800 mm length. The polymer solution inlet temperature, polymer solution outlet temperature, hot oil I inlet temperature, and hot oil I reflux temperature are all measured using thermocouple thermometers, and the pressure at the heat exchanger outlet is measured using a diaphragm pressure gauge.

[0162] The heat absorption Q of the polymer solution is calculated using the following formula (1), and the gas holdup X at the outlet of the polymer solution is calculated using the following formula (2):

[0163] Q = M oil ×(T in -T out )×C p-oil / M PB (1)

[0164] X = (Q - (T) out-PB -T in-PB )×C p-PB ) / L PB (2)

[0165] Among them, M oil T is the flow rate of hot oil I. in Hot oil I enters at temperature T out Hot oil reflux temperature; M PB T is the flow rate of the polymer solution. in-PB T is the inlet temperature of the polymer solution. out-PB The outlet temperature of the polymer solution; C p-oil C is the isobaric specific heat capacity of hot oil. p-PB The isobaric specific heat capacity of polybutene-1 solution; L PB The latent heat of vaporization of butene-1.

[0166] Isobaric specific heat capacity of hot oil (C) p-oil 2.4 kJ / (kg·℃);

[0167] The latent heat of vaporization of butene-1 (L PB 390 kJ / kg;

[0168] The isobaric specific heat capacity (C) of polybutene-1 solution p-PB The effective temperature and humidity (TQH) is 2.8 kJ / (kg·℃).

[0169] The process parameters that need to be controlled are as follows:

[0170] Heat exchanger outlet pressure (barg): 28;

[0171] Butene-1 has a bubble point temperature of 130°C at a pressure of 28 barg.

[0172] Flow rate of hot oil I (M oil (t / h): 30;

[0173] Hot oil I entry temperature (T) in (℃): 128;

[0174] Hot oil reflux temperature (T) out (℃): 125;

[0175] Flow rate of polymer solution (M PB (t / h): 2;

[0176] Polymer solution heat exchange effect:

[0177] Polymer solution inlet temperature (T) in-PB (℃): 75;

[0178] polymer solution outlet temperature (T) out-PB (℃): 114;

[0179] The heat absorbed by the polymer solution, Q (kJ / kg), is 108.

[0180] The gas holdup X (%) of the polymer solution at the outlet of the two-stage tube heat exchanger is 0.

[0181] A conventional shell-and-tube heat exchanger is used, and the inlet temperature (T) is used. in The low-temperature hot oil I, which is below the solvent bubble point, has limited heat transfer capacity of the heat exchanger, and the heat absorbed by the polymer solution is only 28% of that in the example.

[0182] Comparative Example 4

[0183] A heating method for a low-solids-content, low-boiling-point polymer solution includes: using 1-butene monomer as a solvent, a homogeneous polybutene-1 bulk polymer is employed as the low-solids-content, low-boiling-point polymer; the reactor discharge polymer solids content is 20%, the polymer solution flow rate is 2 t / h, the polymer solution inlet temperature is 75℃, and after heat exchange in a shell-and-tube heat exchanger, it enters a flash tank to remove unpolymerized 1-butene monomer. The heat exchanger is heated by hot oil II. The heat exchanger used is a conventional shell-and-tube heat exchanger with the following main structural parameters: 630 tubes, 25 mm inner diameter, and 4800 mm length. The polymer solution inlet temperature, polymer solution outlet temperature, and hot oil II inlet temperature are all measured using thermocouple thermometers, and the pressure at the heat exchanger outlet is measured using a diaphragm pressure gauge.

[0184] The heat absorption Q of the polymer solution is calculated using the following formula (1), and the gas holdup X at the outlet of the polymer solution is calculated using the following formula (2):

[0185] Q = M oil ×(T in -T out )×C p-oil / M PB (1)

[0186] X = (Q - (T) out-PB -T in-PB )×C p-PB ) / L PB (2)

[0187] Among them, M oil For the flow rate of hot oil II, T in Hot oil II entry temperature, T out Hot oil II reflux temperature; M PB T is the flow rate of the polymer solution. in-PB T is the inlet temperature of the polymer solution. out-PB The outlet temperature of the polymer solution; C p-oil C is the isobaric specific heat capacity of hot oil. p-PB The isobaric specific heat capacity of polybutene-1 solution; L PB The latent heat of vaporization of butene-1.

[0188] Isobaric specific heat capacity of hot oil (C) p-oil 2.4 kJ / (kg·℃);

[0189] The latent heat of vaporization of butene-1 (L PB 390 kJ / kg;

[0190] The isobaric specific heat capacity (C) of polybutene-1 solution p-PB The effective temperature and humidity (TQH) is 2.8 kJ / (kg·℃).

[0191] The process parameters that need to be controlled are as follows:

[0192] Heat exchanger outlet pressure (barg): 28;

[0193] Butene-1 has a bubble point temperature of 130°C at a pressure of 28 barg.

[0194] Flow rate of hot oil II (M oil (t / h): 30;

[0195] Hot oil II entry temperature (T) in (℃): 190;

[0196] Flow rate of polymer solution (MPB (t / h): 2;

[0197] Polymer solution heat exchange effect:

[0198] Polymer solution inlet temperature (T) in-PB (℃): 75;

[0199] polymer solution outlet temperature (T) out-PB (℃): The initial temperature gradually decreased from 175℃ to 85℃.

[0200] A conventional shell-and-tube heat exchanger is used, and the inlet temperature (T) is used. in After running for half an hour, the outlet temperature of the heat exchanger for the high-temperature hot oil II, which is higher than the solvent bubble point, gradually decreased from 175°C to 85°C, indicating that the heat exchanger was significantly blocked. The above operating parameters could not guarantee the long-term stable operation of the heat exchange equipment.

[0201] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for heating a low-solids-content, low-boiling-point polymer solution, characterized in that, The heating method includes the following steps: heating the polymer solution by introducing it into the tube side of a two-stage shell-and-tube heat exchanger with a common tube pass; the shell side of the two-stage shell-and-tube heat exchanger includes an inlet shell side and an outlet shell side; the heating medium of the shell-and-tube heat exchanger includes a first medium and a second medium, wherein the first medium may be the same as or different from the second medium; the first medium is introduced into the inlet shell side and its inlet temperature is T. in-up The second medium is introduced into the shell side of the outlet section and its inlet temperature is T. in-down T in-up <bubble point temperature of the solvent in the polymer solution<T in-down The gas holdup of the polymer solution at the outlet of the two-stage tube heat exchanger is ≤50%.

2. The method for heating the polymer solution according to claim 1, characterized in that, The polymer solution has a boiling point of -10 to 120°C; the solid content of the polymer solution is less than 50%.

3. The method for heating the polymer solution according to claim 1 or 2, characterized in that, T in-up The temperature is set to be 2-5°C lower than the bubble point temperature of the solvent in the polymer solution, preferably 2-3°C.

4. The method for heating the polymer solution according to any one of claims 1-3, characterized in that, T in-down Set to be 2°C or higher than the polymer solution outlet temperature, preferably T. in-down Set the temperature to be 5℃~60℃ higher than the polymer solution outlet temperature.

5. The method for heating the polymer solution according to any one of claims 1-4, characterized in that, The polymer solution has a gas content of 20-50% at the outlet of the heat exchanger, preferably 30-40%; And / or, the polymer solution is at a pressure of 15-30 bar at the outlet of the heat exchanger, preferably 25-30 bar.

6. The method for heating the polymer solution according to any one of claims 1-5, characterized in that, The inlet temperature of the first medium in the shell side of the inlet section is 100-150℃, the reflux temperature of the first medium in the shell side of the inlet section is 90-145℃, and the flow rate ratio of the polymer solution to the flow rate of the first medium is 1:(1-100), preferably 1:(2-50). And / or, the inlet temperature of the second medium in the shell side of the outlet section is 140-250°C, the reflux temperature of the second medium in the shell side of the outlet section is 135-230°C, and the flow rate ratio of the polymer solution to the flow rate of the second medium is 1:(0.5-50), preferably 1:(0.8-20). And / or, the polymer solution inlet temperature is 30-120℃, and the polymer solution outlet temperature is 120-200℃.

7. The method for heating a polymer solution according to any one of claims 1-6, characterized in that, The first medium and the second medium do not mix.

8. The method for heating the polymer solution according to claim 7, characterized in that, In the two-section tube heat exchanger with a common tube side, the tube side includes an inlet tube section and an outlet tube section, wherein the inlet tube section and the outlet tube section are formed as a single tube; or the inlet tube section and the outlet tube section are formed as two tube sections, wherein the outlet end of the first tube section serving as the inlet tube section and the inlet end of the second tube section serving as the outlet tube section are fixed by a distribution plate, so that the material in the first tube section enters the corresponding second tube section.

9. The method for heating the polymer solution according to claim 7 or 8, characterized in that, The pressure of the polymer solution at the outlet of the heat exchanger is controlled by a heat exchanger outlet pressure control device; preferably, the heat exchanger outlet pressure control device is a pressure control valve. And / or, the bubble point temperature of the polymer solution is obtained by simulation using Aspen software. And / or, the number of tubes in the tube heat exchanger is 20-1000, the inner diameter of the tubes is 10-100mm, the length of the inlet section tubes is 500-20000mm, and the length of the outlet section tubes is 500-20000mm.

10. A method for recovering a polymer solution, characterized in that, The recycling method includes the following steps: (1) The polymer solution is treated by the heating method according to any one of claims 1-9 to obtain the heated polymer material; (2) In a flash evaporator, the polymer material is flash-evaporated to obtain a gas phase component and a liquid phase component; (3) The gas phase component is sent to the light component recovery unit, and the liquid phase component is sent to the solvent separation unit for further solvent separation.