Online monitoring method and device for gas-liquid volume mass transfer coefficient in high-viscosity reactor

Abstract

The invention discloses an on-line monitoring method and device for gas-liquid volume mass transfer coefficient in a high-viscosity reactor, and the monitoring method comprises the following steps: vacuumizing to exhaust CO2 in a melt in a closed reactor, vacuumizing to exhaust inert gas in the closed reactor, filling CO2 into the closed reactor until the pressure is less than 20 kPa, stirring the melt in the reactor to absorb CO2, and carrying out vacuum pumping to exhaust inert gas in the closed reactor; the gas-phase pressure in the reactor is collected in real time through precise pressure equipment, and quantitative analysis is carried out on a change curve of the gas-phase pressure along with time, so that the gas-liquid volume mass transfer coefficient (kLa) CO2 of CO2 in the reactor is obtained. According to the method, the pressure in the reactor in the process that CO2 is absorbed by the high-viscosity melt in the closed system is collected through precise pressure equipment, the problem that melt sampling is difficult in a traditional high-viscosity reactor kLa measuring method can be solved, the reactor does not need to be excessively modified, and therefore the calculation result can guide reaction process optimization and production practice.

Description

Technical Field

[0001] The invention relates to the technical field of gas-liquid mass transfer, and in particular to an online monitoring method and device for a gas-liquid volumetric mass transfer coefficient in a high-viscosity reactor. Background Art

[0002] Gas-liquid volumetric mass transfer coefficient k L a It is a key indicator reflecting the mass transfer performance of a reactor and is mainly used in the study of reaction kinetics in chemical reaction engineering, as well as the selection and structural optimization of reactors in chemical processes. k L a Quantitative determination is usually carried out through cold simulation experiments. The cold simulation experiment refers to the use of a small test device with similar geometry to the industrial reactor, using a system with similar physical properties such as density and viscosity to the actual reaction system at room temperature to conduct experimental determination, and then derive the industrial size reactor through similarity criteria. k L a .

[0003] In the existing gas-liquid mass transfer equipment such as low viscosity reactors, high viscosity reactors, packed towers, pipelines, film formers, and biofermentation reactors, the existing k L a The determination method includes an offline sampling detection method and an online monitoring method. The offline sampling detection method refers to sampling and analyzing the gas phase or liquid phase at different time points to obtain the change of gas component content over time; the gas phase sample can be analyzed by an infrared gas analyzer, etc., and the liquid phase sample can be analyzed by acid-base titration and other methods.

[0004] The online monitoring method refers to real-time monitoring of the composition or properties of the gas phase or liquid phase during the gas-liquid mass transfer process. For example, when CO2 is used as the gas phase component, the liquid phase pH value is measured to deduce the change of CO2 concentration in the liquid phase over time. For example, CN117368292A discloses a device for detecting the gas-liquid mass transfer coefficient and a method for calculating the gas-liquid mass transfer coefficient. The method for calculating the gas-liquid mass transfer coefficient is to build an experimental device, inject CO2 into a horizontal pipeline in a full pipe flow state, detect and record the change of the pH value of the liquid in the pipeline in real time, and shoot a video of the change of the volume of the CO2 balloon during the entire experiment to calculate the gas-liquid mass transfer coefficient of CO2 in the flowing water body of the horizontal pipeline. The specific situation of the gas-liquid mass transfer of a larger balloon in a limited volume of liquid can be determined more accurately, thereby more accurately guiding production practice.

[0005] Or when O2 is used as the gas phase component, an oxygen probe is used to measure the oxygen concentration change in the gas phase in real time. kL a In addition to the determination method, patent CN118425257A also reported adding sodium sulfide to the anaerobic tank to determine the change in redox potential during H2S desorption. k L a method.

[0006] In high viscosity reactors, the reported k L a There are two measurement methods: one is the CO2 isokinetic absorption method, in which the CO2 in the high-viscosity melt is first exhausted, and then the gas phase of the reactor is partially replaced by CO2, so that the CO2 in the gas phase is absorbed by the melt, and samples are taken at different time points and acid-base titration is performed to obtain the change of CO2 concentration in the melt over time; the second is the oxygen probe method, in which the high-viscosity melt absorbs O2 to saturation, and then the gas phase of the reactor is partially replaced by N2, the device is sealed and stirring is started, so that the O2 in the melt is desorbed into the gas phase, and the change of oxygen concentration over time is collected. The main difficulty of method one is the difficulty in sampling viscous melts. At present, it is only used in systems with a melt viscosity below 100 Pa·s. In chemical processes involving high viscosity such as polyester thickening, the melt viscosity can reach more than 500 Pa·s. According to the Hagen-Poiseuille formula for laminar flow of fluids in pipes It can be seen that the melt outflow speed from the sampling port is u Inversely proportional to viscosity μ In the actual practice, it was found that it took more than 10 minutes to make a syrup with a viscosity of 500 Pa·s flow out through a sampling port with an inner diameter of 10 mm. It can be seen that it is extremely difficult to sample a melt with extremely high viscosity. Method 2 does not require sampling during the mass transfer process, but the amount of O2 dissolved in the melt is very low, which affects k L a The measurement accuracy is limited, and this method is not suitable for systems that are easily oxidized.

[0007] CO2 has good solubility in solution. For example, the solubility of CO2 in water at room temperature is more than 20 times that of other common gases including N2 and O2. k L a Most of the determination methods use CO2 as the gas phase component. Taking the absorption of CO2 by maltose syrup with a dry matter content of 85% as an example, according to theoretical derivation and experimental results, the pressure drop when CO2 absorption reaches equilibrium in a closed system can reach about 10kPa. The use of precision pressure equipment can monitor the gas-liquid mass transfer progress of CO2 in real time with high measurement accuracy, thereby achieving k L a Online determination. Summary of the invention

[0008] The present invention aims at the gas-liquid volume mass transfer coefficient in the high viscosity reaction system k L a In order to solve the problems of difficult sampling and low real-time monitoring accuracy of traditional offline measurement methods, an online monitoring method for the gas-liquid volume mass transfer coefficient in a high-viscosity reactor is provided. This method uses precision pressure equipment to collect the real-time pressure changes in the reactor during the absorption of CO2 by the high-viscosity melt in the closed reactor, and then measures the accurate CO2 in the reactor. k L a ,accomplish k L a Online determination.

[0009] To achieve the above object, the technical solution adopted by the present invention is: An online monitoring method for gas-liquid volumetric mass transfer coefficient in a high viscosity reactor comprises the steps of: Step 1, evacuate the gas in the closed reactor, fill the reactor with inert gas to normal pressure, stir the melt in the reactor to desorb CO2 to the gas phase, and evacuate the CO2; repeat the steps until the CO2 in the melt is exhausted; Step 2: Vacuum the inert gas in the closed reactor, fill it with CO2 to below 20 kPa, stir the melt in the reactor to absorb CO2, collect the gas phase pressure in the reactor in real time through precision pressure equipment, and quantitatively analyze the change curve of gas phase pressure over time to obtain the gas-liquid volume mass transfer coefficient of CO2 in the reactor ( k L a ) CO2 .

[0010] In the present invention, CO2 is charged into the reactor, the reactor is sealed and stirring is started, and the pressure in the reactor during the absorption of CO2 by the high-viscosity melt in the closed system is collected by a precision pressure device. The pressure of CO2 in the reactor is quantitatively analyzed and calculated based on the change curve of the gas phase pressure over time. k L a , and then obtain the other gas phase components in the actual reaction system under the same operating conditions k L a This method can solve the problem of high viscosity reactor k L a The difficulty of melt sampling in traditional determination methods does not require excessive modification of the reactor, and the calculation results can guide reaction process optimization and production practice.

[0011] In step 1, if the CO2 concentration in the gas phase in the reactor measured by a CO2 detector is below 1000 ppm, the CO2 in the melt is deemed to be exhausted; or in step 1, if the gas phase pressure in the reactor reaches equilibrium for more than 1 hour, the CO2 in the melt is deemed to be exhausted.

[0012] The viscosity of the melt is 10-2000 Pa·s. The method of the present invention is very suitable for high viscosity reactors, and does not require sampling of the melt during the reaction process, and can also achieve online measurement.

[0013] The gas-liquid volume mass transfer coefficient of CO2 in the reactor was obtained by quantitatively analyzing the change curve of gas phase pressure over time ( k L a ) CO2 The specific steps include: The initial value of the gas-liquid volume mass transfer coefficient ( k L a )0, according to the measured data of gas phase pressure at each time node, the CO2 in the reactor is obtained by optimization method ( k L a ) CO2 , so that the formula The time nodes obtained t i The corresponding theoretical value of gas phase pressure p i The sum of deviations from the measured data is minimized; in, p 0 is the gas phase pressure in the reactor at the initial moment of CO2 filling, V L is the volume of the melt, V G is the volume of the gas phase space in the reactor, R is the gas constant, T is the temperature inside the reactor, H is the Henry coefficient of CO2 in the melt.

[0014] The initial value of the gas-liquid volumetric mass transfer coefficient ( k L a )0According to the initial moment of CO2 absorption t 0 and end time t 1 Calculation of measured data of gas phase pressure:

[0015] in, V L is the volume of the melt, V Gis the volume of the gas phase space in the reactor, R is the gas constant, T is the temperature inside the reactor, H is the Henry coefficient of CO2 in the melt, p 0 is the gas phase pressure in the reactor at the initial moment of CO2 filling, p 1 is the gas phase pressure of the reactor at the end of CO2 absorption.

[0016] The Henry coefficient H Calculated according to the following formula:

[0017] in, V L is the volume of the melt, V G is the volume of the gas phase space in the reactor, R is the gas constant, T is the temperature inside the reactor, p 0 is the gas phase pressure in the reactor at the initial moment of CO2 filling, p eq It is the gas phase pressure in the reactor when CO2 absorption reaches equilibrium.

[0018] Said p eq The test methods specifically include: Replace step 2 with: evacuate the inert gas in the closed reactor, fill it with CO2 to below 20 kPa, stir the melt in the reactor to absorb CO2, and collect the gas phase pressure in the reactor in real time through a precision pressure device until the gas phase pressure in the reactor drops to an equilibrium state. The gas phase pressure in the reactor measured at the equilibrium moment is p eq .

[0019] According to the gas-liquid volumetric mass transfer coefficient of CO2 in the reactor ( k L a ) CO2 Calculate the other gas phase components in the same melt or other melts with the same viscosity ( k L a ) g :

[0020] in,( k L a ) CO2 is the gas-liquid volumetric mass transfer coefficient measured using CO2 as the gas phase component, DCO2 is the diffusion coefficient of CO2 in the melt, D g is the diffusion coefficient of other gas phase components in the melt, ( k L a ) g is the derived gas-liquid volumetric mass transfer coefficient of other gas phase components in the same melt or other melts with the same viscosity.

[0021] The present invention also provides an online monitoring device for the gas-liquid volume mass transfer coefficient in a high viscosity reactor used in the online monitoring method, comprising a closed reactor and a precision pressure device, a vacuum pump, a nitrogen bottle, and a carbon dioxide bottle connected to the closed reactor; The precision pressure equipment is used to measure the pressure of the gas phase of the closed reactor, the vacuum pump is used to discharge the gas in the gas phase of the closed reactor, the nitrogen bottle is used to fill the closed reactor with nitrogen, and the carbon dioxide bottle is used to fill the closed reactor with carbon dioxide.

[0022] The online monitoring device also includes a carbon dioxide detector connected to the closed reactor; The closed reactor includes a horizontal reactor or a vertical reactor.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The pressure in the reactor during the absorption of CO2 by the high-viscosity melt in the closed system is collected by precision pressure equipment, and the pressure of CO2 in the reactor is calculated according to the method of the present invention. k L a , and then obtain the other gas phase components in the actual reaction system under the same operating conditions k L a , can solve the problem of high viscosity reactor k L a The difficulty of melt sampling in traditional determination methods does not require excessive modification of the reactor, so the calculation results can guide reaction process optimization and production practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the gas-liquid volume mass transfer coefficient of the high viscosity reactor detected in the present invention. k L a Schematic diagram of the device, wherein 1 is a closed reactor, 2 is a precision pressure device, 3 is a carbon dioxide detector, 4 is a vacuum pump, 5 is a nitrogen bottle, and 6 is a carbon dioxide bottle.

[0025] Figure 2It is a schematic diagram of the shape, size and liquid level height of the closed reactor in Example 1.

[0026] Figure 3 This is the pressure-time curve collected by the precision pressure equipment during the CO2 absorption to equilibrium process in Example 1.

[0027] Figure 4 It is the pressure-time curve collected by the precision pressure equipment during the CO2 absorption until the pressure drops by 2 kPa in Example 2 and the fitting curve of the calculation formula. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0029] like Figure 1 As shown, an online monitoring device for gas-liquid volume mass transfer coefficient in a high viscosity reactor includes a closed reactor 1 and a precision pressure device 2 connected to the closed reactor 1, a carbon dioxide detector 3, a vacuum pump 4, a nitrogen bottle 5, and a carbon dioxide bottle 6; The precision pressure equipment 2 is used to measure the pressure of the gas phase of the closed reactor 1, the carbon dioxide detector 3 is used to measure the carbon dioxide content in the gas phase of the closed reactor 1, the vacuum pump 4 is used to discharge the gas in the gas phase of the closed reactor 1, the nitrogen bottle 5 is used to fill nitrogen into the closed reactor 1, and the carbon dioxide bottle 6 is used to fill carbon dioxide into the closed reactor 1.

[0030] The closed reactor 1 is a horizontal biaxial cold state simulation experimental device with a water bath temperature control function; the carbon dioxide detector 3 is a handheld carbon dioxide detector or a pipeline carbon dioxide sensor with a range of 0-10000ppm. The precision pressure equipment 2 is a micro-pressure digital pressure gauge or pressure transmitter with a measurement range of 0-10kPa and an accuracy level of 0.4%, and the pressure measurement error does not exceed ±0.04kPa. During the experiment, a pressure value is collected every 30s.

[0031] In the CO2 desorption stage, CO2 enters the gas phase from the melt, causing the gas phase pressure to rise, and the pressure rise is equivalent to the pressure drop in the CO2 absorption stage. When the gas phase pressure reaches dynamic equilibrium for more than 1 hour, the CO2 detector is placed at the reactor outlet, and the CO2 concentration is measured to be below 1000ppm, indicating that CO2 has been basically exhausted. At this time, the trace CO2 remaining in the melt will not affect the subsequent CO2 absorption stage. If the CO2 detector is not used, the gas phase pressure measured by the precision pressure equipment 2 after multiple rounds of CO2 desorption can also be used as the basis for judging whether CO2 is exhausted.

[0032] Example 1

[0033] Use Figure 1 The online monitoring device shown in the figure performs an online monitoring method for the gas-liquid volume mass transfer coefficient in a high viscosity reactor, and first determines the Henry coefficient of CO2 in the melt.

[0034] In the present invention, it is assumed that the CO2 gas in the gas phase space in the closed reactor follows the ideal gas law: , , in, p 0 is the gas phase pressure at the initial moment of CO2 absorption, p is the gas phase pressure at different time points during the CO2 absorption process, V G is the gas phase volume, R is the gas constant, T is temperature; Assume that the gas-liquid phase equilibrium of CO2 follows Henry's law: , in, H is the Henry coefficient, c eq is the equilibrium concentration of CO2 in the liquid phase, c eq = n eq / V L , V L is the liquid phase volume, n eq is the amount of CO2 in the liquid phase under gas-liquid equilibrium.

[0035] In the closed reactor 1, maltose syrup is used as the viscous melt, and the viscosity of the syrup is adjusted to 500 Pa·s by controlling the temperature to (30.0±0.1)°C and adjusting the mass fraction of water in the syrup to 14.5%. Add syrup to Figure 2 Initial level shownY =95mm, the liquid volume corresponding to the initial liquid level V L =14.9L, gas phase volume V G =20.5L. The specific steps include: Step 1, CO2 desorption: vacuum pump 4 evacuates the gas in the closed reactor 1, nitrogen bottle 5 fills nitrogen into the closed reactor to normal pressure, stirs the melt in the reactor to desorb CO2 to gas phase, vacuum pump 4 evacuates CO2; repeat the steps until CO2 in the melt is exhausted; Step 2: vacuum pump 4 evacuates nitrogen in the closed reactor, and carbon dioxide bottle 6 is filled with CO2 until the gauge pressure of precision pressure device 2 reaches 9.41 kPa. The viscous melt is stirred at 5 rpm. CO2 absorption continues for 22.5 hours to reach dynamic equilibrium. The gauge pressure collected by precision pressure device 2 is converted into absolute pressure. The resulting pressure-time curve is shown in Figure 3 shown.

[0036] The initial pressure p 0=110.67kPa, balanced pressure p eq =99.46kPa, total pressure drop Δ p =11.21 kPa, gas constant R =8.314 J·mol -1 ·K -1 , the temperature inside the reactor T =303K, according to Henry coefficient calculation formula , substituting the numerical value, we can get the Henry coefficient of CO2 in the melt H =1.62×10 4 kPa·L·mol -1 .

[0037] Example 2

[0038] According to the steps of Example 1, the same maltose syrup is still used as the viscous melt, the viscosity of the syrup is adjusted to 500 Pa·s by controlling the temperature to (30.0±0.1)°C and adjusting the mass fraction of water in the syrup to 14.5%, and the other conditions are consistent with those of Example 1. The method for online monitoring of the gas-liquid volume mass transfer coefficient includes the steps of: Step 1, CO2 desorption: vacuum pump 4 evacuates the gas in the closed reactor 1, nitrogen bottle 5 fills nitrogen into the closed reactor to normal pressure, stirs the melt in the reactor to desorb CO2 to gas phase, vacuum pump 4 evacuates CO2; repeat the steps until CO2 in the melt is exhausted; Step 2: vacuum pump 4 evacuates nitrogen in the closed reactor, and carbon dioxide bottle 6 is charged with CO2 until the gauge pressure of precision pressure device 2 reaches 9.57 kPa. After continuous stirring at 4 rpm for 1.81 h, the gauge pressure drops to 7.57 kPa, and stirring is stopped. The obtained pressure-time curve is as follows: Figure 4 shown.

[0039] The fluctuation of the pressure test curve is caused by the temperature fluctuation in the water bath temperature control process and the measurement error of the precision pressure equipment. It can be seen that from the beginning of CO2 absorption to the pressure drop of 2kPa, the pressure fluctuation has little effect on the pressure-time curve. At the same time, the time of the CO2 absorption experiment is shortened to less than 1 / 10 of that in Example 1, thereby saving the experimental time cost.

[0040] Initial value of gas-liquid volumetric mass transfer coefficient ( k L a )0 is calculated according to the following formula:

[0041] The end time t 1=6516s, initial pressure p 0=110.90kPa, pressure at the end p 1=108.90kPa, liquid volume V L =14.9L, gas phase volume V G =20.5L, Henry coefficient H As obtained in Example 1, H =1.62×10 4 kPa·L·mol -1 , the gas constant R =8.314 J·mol -1 ·K -1 , the temperature inside the reactor T =303K, the final calculated value is ( k L a )0=2.71×10 -5 s -1 .

[0042] The initial value of the gas-liquid volume mass transfer coefficient ( k L a )0, according to the measured data of gas phase pressure at each time node, the CO2 in the reactor is obtained by optimization method ( k L a ) CO2 , so that the formula The time nodes obtained t i The corresponding theoretical value of gas phase pressure p i The sum of deviations from the measured data is minimized; use The measured experimental values ​​are fitted, and the fitting curve is shown in Figure 4 , thus the gas-liquid volumetric mass transfer coefficient of CO2 in the reactor is obtained ( k L a ) CO2 =2.66×10 -5 s -1 .

[0043] Example 3 Acid-base titration method to verify the gas-liquid volume mass transfer coefficient measured in Example 2 Before the CO2 absorption experiment in Example 2, a 5.0 g portion of the syrup sample was taken as a control group, and after the experiment, three 5.0 g portions of the syrup sample were taken as experimental groups. An excess of 0.02 mol·L -1 NaOH dissolves CO2 in the syrup. Add phenolphthalein indicator and add 0.02 mol·L -1 The concentration of CO2 absorbed in the syrup is obtained from the amount of NaOH and dilute hydrochloric acid used, which is:

[0044] in, c (NaOH) and c (HCl) is the molar concentration of NaOH solution and dilute hydrochloric acid, V 0(NaOH) and V 0(HCl) is the amount of NaOH solution and dilute hydrochloric acid used in the control group, V (NaOH) and V (HCl) is the amount of NaOH solution and dilute hydrochloric acid used in the experimental group samples, m s is the sample mass, ρ s is the density of syrup, ρ s =1.44 g cm -3 The reason for introducing the control group here is that the maltose in the syrup will react with part of the NaOH, and the effect of this reaction on the CO2 concentration titration results needs to be eliminated.

[0045] In the acid-base titration experiment, the amount of NaOH solution used in the experimental and control group samples V (NaOH) = = V0(NaOH)=6.00mL, the amount of dilute hydrochloric acid is the control group V 0(HCl)=1.93mL, average value of three samples in the experimental group , thus obtaining the CO2 concentration in the syrup at the end of CO2 absorption c (CO2) = 1.15 × 10 -3 mol·L -1 .

[0046] According to the ideal gas state equation: , substitute the values, where the liquid volume V L =14.9L, gas phase volume V G =20.5L, gas constant R =8.314 J·mol -1 ·K -1 , the temperature inside the reactor T =303K, and the pressure drop corresponding to the titration value of CO2 concentration in the above syrup is obtained p It is 2.11kPa.

[0047] At initial pressure p 0 = 110.90 kPa minus the pressure drop to get the end time t 1 = 6516s calculated value of pressure p 1=108.79 kPa, substitute Finally, we get k L a ) CO2 =2.88×10 -5 s -1 .

[0048] It can be seen that the ( k L a ) CO2 Compared with the value obtained in Example 2 ( k L a ) CO2 Close, indicating that the present invention is determined by collecting pressure-time curve k L a The method is feasible, accurate and fast.

[0049] Example 4

[0050] In Example 2, it was measured as follows Figure 2Under the reactor size and liquid level shown, using syrup with a viscosity of 500 Pa·s as the melt medium and a rotation speed of 4 rpm, the gas-liquid volumetric mass transfer coefficient of CO2 in the reactor ( k L a ) CO2 .

[0051] At this syrup concentration and temperature, the diffusion coefficient of CO2 in the syrup is D CO2 =1.9×10 -9 s -1 . Through this ( k L a ) CO2 It is deduced that in the polyester final polycondensation process, when the polymer melt is polyethylene terephthalate (PET) with a viscosity of 500 Pa·s, the gas-liquid volumetric mass transfer coefficient of ethylene glycol in the reactor ( k L a ) g It is known that at a reaction temperature of 270°C and a melt viscosity of 500 Pa·s, the diffusion coefficient of ethylene glycol in PET is D g =2.0×10 -10 s -1 , substitute ,get( k L a ) g =8.6×10 -10 s -1 The results can be used to guide the production practice of polyester final polycondensation process.

Claims

1. An online monitoring method for gas-liquid volumetric mass transfer coefficient in a high viscosity reactor, characterized in that: Includes steps: Step 1, evacuate the gas in the closed reactor, fill the reactor with inert gas to normal pressure, stir the melt in the reactor to desorb CO2 to the gas phase, and evacuate the CO2; repeat the steps until the CO2 in the melt is exhausted; Step 2: Vacuum the inert gas in the closed reactor, fill it with CO2 to below 20 kPa, stir the melt in the reactor to absorb CO2, collect the gas phase pressure in the reactor in real time through precision pressure equipment, and quantitatively analyze the change curve of gas phase pressure over time to obtain the gas-liquid volume mass transfer coefficient of CO2 in the reactor ( k L a ) CO2 .

2. The method for online monitoring of the gas-liquid volumetric mass transfer coefficient in a high viscosity reactor according to claim 1, characterized in that: In step 1, when the CO2 concentration in the gas phase in the reactor is measured by a CO2 detector and is below 1000 ppm, it is considered that the CO2 in the melt is exhausted; And / or, in step 1, the CO2 in the melt is deemed to be exhausted when the gas phase pressure in the reactor reaches equilibrium for more than 1 hour.

3. The method for online monitoring of the gas-liquid volumetric mass transfer coefficient in a high viscosity reactor according to claim 1, characterized in that: The viscosity of the melt is 10 - 2000 Pa·s.

4. The method for online monitoring of the gas-liquid volumetric mass transfer coefficient in a high viscosity reactor according to claim 1, characterized in that: The gas-liquid volume mass transfer coefficient of CO2 in the reactor was obtained by quantitatively analyzing the change curve of gas phase pressure over time ( k L a ) CO2 Specifically include step: The initial value of the gas-liquid volumetric mass transfer coefficient ( k L a )0, according to the measured data of gas phase pressure at each time node, the CO2 in the reactor is obtained by optimization method ( k L a ) CO2 , so that the formula The time nodes obtained t i The corresponding theoretical value of gas phase pressure p i The sum of deviations from the measured data is minimized; in, p 0 is the gas phase pressure in the reactor at the initial moment of CO2 filling, V L is the volume of the melt, V G is the volume of the gas phase space in the reactor, R is the gas constant, T is the temperature inside the reactor, H is the Henry coefficient of CO2 in the melt.

5. The method for online monitoring of the gas-liquid volumetric mass transfer coefficient in a high viscosity reactor according to claim 4, characterized in that: The initial value of the gas-liquid volumetric mass transfer coefficient ( k L a )0According to the initial moment of CO2 absorption t 0 and end time t 1 Calculation of measured data of gas phase pressure: ， in, V L is the volume of the melt, V G is the volume of the gas phase space in the reactor, R is the gas constant, T is the temperature inside the reactor, H is the Henry coefficient of CO2 in the melt, p 0 is the gas phase pressure in the reactor at the initial moment of CO2 filling, p 1 is the gas phase pressure of the reactor at the end of CO2 absorption.

6. The method for online monitoring of the gas-liquid volumetric mass transfer coefficient in a high viscosity reactor according to claim 4, characterized in that: The Henry coefficient H Calculated according to the following formula: ， in, V L is the volume of the melt, V G is the volume of the gas phase space in the reactor, R is the gas constant, T is the temperature inside the reactor, p 0 is the gas phase pressure in the reactor at the initial moment of CO2 filling, p eq It is the gas phase pressure in the reactor when CO2 absorption reaches equilibrium.

7. The method for online monitoring of the gas-liquid volumetric mass transfer coefficient in a high viscosity reactor according to claim 6, characterized in that: Said p eq The test methods specifically include: Replace step 2 with: evacuate the inert gas in the closed reactor, fill it with CO2 to below 20 kPa, stir the melt in the reactor to absorb CO2, and collect the gas phase pressure in the reactor in real time through a precision pressure device until the gas phase pressure in the reactor drops to an equilibrium state. The gas phase pressure in the reactor measured at the equilibrium moment is p eq .

8. The method for online monitoring of gas-liquid volumetric mass transfer coefficient in a high viscosity reactor according to claim 1, characterized in that: According to the gas-liquid volumetric mass transfer coefficient of CO2 in the reactor ( k L a ) CO2 Calculate the other gas phase components in the same melt or other melts with the same viscosity ( k L a ) g : ， in,( k L a ) CO2 is the gas-liquid volumetric mass transfer coefficient measured using CO2 as the gas phase component, D CO2 is the diffusion coefficient of CO2 in the melt, D g is the diffusion coefficient of other gas phase components in the melt, ( k L a ) g is the derived gas-liquid volumetric mass transfer coefficient of other gas phase components in the same melt or other melts with the same viscosity.

9. An online monitoring device for the gas-liquid volumetric mass transfer coefficient in a high viscosity reactor used in the online monitoring method according to any one of claims 1 to 8, characterized in that: It includes a closed reactor and precision pressure equipment, a vacuum pump, a nitrogen bottle, and a carbon dioxide bottle connected to the closed reactor; The precision pressure equipment is used to measure the pressure of the gas phase of the closed reactor, the vacuum pump is used to discharge the gas in the gas phase of the closed reactor, the nitrogen bottle is used to fill the closed reactor with nitrogen, and the carbon dioxide bottle is used to fill the closed reactor with carbon dioxide.

10. The online monitoring device for the gas-liquid volume mass transfer coefficient in a high viscosity reactor according to the online monitoring method of claim 9, characterized in that: The online monitoring device also includes a carbon dioxide detector connected to the closed reactor; And / or, the closed reactor includes a horizontal reactor or a vertical reactor.

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