A monitoring device and method for dispersed phase residence time in a continuous reactor

Abstract

The present invention relates to a monitoring device and method for the residence time of a dispersed phase in a continuous reactor, wherein the monitoring device comprises a raw material storage device, a feed control device, a continuous reactor, a discharge control device, a flat pipe and a collecting device connected in sequence along the material flow direction; the monitoring device also comprises a high-speed camera, which is used to photograph the heterogeneous mixture on the flat pipe, and the high-speed camera is connected to a computer. The present invention innovatively combines an online monitoring device to achieve rapid monitoring of the residence time of the dispersed phase without interfering with the reaction system through digital detection of a high-speed camera and a computer; based on image recognition technology, high-frequency sampling in a continuous reactor is achieved, and by calculating the concentration of the dispersed phase in the heterogeneous mixture, the residence time distribution of the dispersed phase in the continuous reactor can be further obtained, which has important guiding significance for optimizing reaction conditions and improving reaction efficiency.

Description

Technical Field

[0001] The invention relates to the field of reactors, and in particular to a monitoring device and method for the residence time of a dispersed phase in a continuous reactor. Background Art

[0002] A solid-liquid or liquid-liquid continuous reactor is a device used for chemical reactions between solids and liquids or between liquids and liquids. The former is usually used to handle reaction processes in suspended solid particles or particle beds, and the latter is usually used to handle reaction processes of incompatible liquids. By continuously adding raw materials, products and reactants, and continuously discharging products, the reaction conditions are controlled in the reactor to achieve a continuous reaction process. The efficiency of the continuous reactor in handling raw material mixing directly affects the quality and production cost of the product. In the reaction process, the conversion rate of the reactants is a key factor in improving production efficiency and ensuring product quality. This requires not only precise control of reaction conditions such as concentration, temperature and pressure, but also a deeper understanding of the flow characteristics of the fluid, especially the residence time distribution of the material in the reactor.

[0003] Residence time distribution is one of the important parameters of continuous operation reaction. The time that the dispersed phase experiences from entering the reactor to leaving the reactor is the residence time. Due to factors such as uneven flow velocity distribution of the dispersed phase in the reactor, diffusion of the dispersed phase, and the existence of dead zones in the reactor, the residence time of the dispersed phase in the reactor is different, thus forming the residence time distribution. The residence time distribution of the dispersed phase in the reactor will directly affect the reaction efficiency and product selectivity. Therefore, it is very important to measure the residence time of the dispersed phase in the reactor.

[0004] The measurement methods of dispersed phase residence time mainly include tracer method, dilution method, intermittent sampling analysis method, reactor model and mathematical modeling. CN 110672542A discloses a device and method for online determination of residence time distribution in liquid-liquid and gas-liquid continuous reactors. The tracer in the quantitative loop is injected into liquid B through an electric six-way valve, and fluid A and liquid B containing the tracer are mixed in a continuous reactor. After the mixture flows out of the continuous reactor, it is quickly separated by an online phase separator. Liquid B containing the tracer flows out of the online phase separator, and the real-time tracer concentration is detected by an online detector. The online detector is connected to a computer to record the tracer concentration change data over time in real time, and calculate the residence time distribution data. However, the device and method provided by the invention are not suitable for determining the distribution of particle residence time in a solid-liquid two-phase reactor, and have certain limitations.

[0005] Traditional determination of dispersed phase residence time still relies on intermittent sampling and analysis, but sampling and analysis is usually complicated and time-consuming, and the reaction system may be disturbed due to sample removal.

[0006] The movement path and residence time distribution of the dispersed phase in the reactor can be inferred by using the reactor model and mathematical modeling, such as a numerical simulation method for predicting the residence time of filamentous biomass particles in a rotating drum disclosed in CN 110879929A, which includes: constructing a physical model of filamentous biomass particles and a rotating drum; the filamentous biomass particles are composed of multiple spherical "aggregates"; analyzing the movement law of the airflow and the aggregates in the rotating drum by the Euler-Lagrange method to obtain a numerical calculation model of gas-solid two-phase flow; using a soft ball model to process the collision between the aggregates to obtain a mathematical model of the movement law of the filamentous biomass particles in the rotating drum; establishing particle dynamics equations, gas phase flow mathematical equations, aggregate collision forces and gas-solid force equations; solving the average residence time of particles in the drum. Although this method can predict fluid behavior to a certain extent, the simplified assumptions often cannot accurately reflect the fluid dynamics characteristics under actual industrial conditions.

[0007] Therefore, in view of the shortcomings of the existing technology, there is an urgent need to provide a monitoring device for the residence time of the dispersed phase in solid-liquid and liquid-liquid systems, which can not only avoid interference with the reaction system but also ensure accuracy. Summary of the invention

[0008] The purpose of the present invention is to provide a monitoring device and method for the residence time of a dispersed phase in a continuous reactor, which can not only avoid interfering with the reaction system but also ensure the accuracy of monitoring, so as to achieve fine optimization of reaction conditions and improve reaction efficiency.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a monitoring device for the residence time of a dispersed phase in a continuous reactor, the monitoring device comprising a raw material storage device, a feed control device, a continuous reactor, a discharge control device, a flat pipe and a collecting device connected in sequence along the material flow direction; the monitoring device also comprises a high-speed camera, the high-speed camera is used to photograph the heterogeneous mixture on the flat pipe, and the high-speed camera is connected to a computer.

[0011] The monitoring device provided by the present invention innovatively combines an online monitoring device to achieve fast and efficient monitoring of the residence time of the dispersed phase without interfering with the reaction system through digital detection of a high-speed camera and a computer, which can meet the real-time regulation and stability requirements of the continuous reactor and significantly improve the operating efficiency and consistency of the reaction results. Based on image recognition technology, high-frequency sampling in the continuous reactor is achieved, and by calculating the concentration of the dispersed phase in the heterogeneous mixture, the residence time distribution of the dispersed phase in the continuous reactor can be further obtained, which has important guiding significance for optimizing reaction conditions and improving reaction efficiency.

[0012] Preferably, the number of the raw material storage devices is ≥ 1, for example, it can be 1, 2, 3, 4 or 5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] Preferably, the raw material storage device comprises a raw material tank.

[0014] Preferably, the feed control device comprises a gear pump.

[0015] In the present invention, since the feed does not contain solid particles, a gear pump can be used to control the feed speed.

[0016] Preferably, the monitoring device further comprises a peristaltic pump, and the peristaltic pump is used to control the raw material to enter the reactor from the raw material storage device.

[0017] Preferably, the discharge control device comprises a peristaltic pump or a gear pump.

[0018] In the present invention, when the discharge material contains solid particles, a peristaltic pump is selected to control the discharge speed, and when the discharge material does not contain solid particles, a peristaltic pump or a gear pump is selected to control the discharge speed.

[0019] Preferably, the collecting device comprises a collecting trough.

[0020] In the present invention, the collecting device is a termination device for the end of the current process, and can also be used as a raw material device for the start of the next process.

[0021] Preferably, the high-speed camera is provided with a reflective device.

[0022] Preferably, the reflecting device comprises a reflecting plate.

[0023] In the present invention, the flat pipe can make the solid-liquid mixture spread thinly, which is convenient for the high-speed camera to shoot the composition of the solid-liquid mixture; the reflective device makes the shooting background of the high-speed camera clean and pure, which is convenient for later observation and processing; the computer is connected to the high-speed camera, and the high-speed camera parameters can be adjusted and the shooting effects can be viewed and saved.

[0024] Preferably, the continuous reactor is provided with a feed inlet and a discharge outlet.

[0025] Preferably, the number of the feed ports and the discharge ports is independently ≥ 1, for example, 1, 2, 3, 4 or 5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] The feed inlet and the discharge inlet can be set in reasonable numbers according to the actual reaction process.

[0027] Preferably, a stirring motor and a stirring paddle connected to the stirring motor are provided inside the continuous reactor.

[0028] Preferably, the volume of the continuous reactor is 0.2-50 L, for example, 0.2 L, 1 L, 7.2 L, 10 L, 20 L, 30 L, 40 L or 50 L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] In a second aspect, the present invention provides a method for monitoring the residence time of a dispersed phase in a continuous reactor, the monitoring method being performed by the monitoring device described in the first aspect, and the monitoring method comprising the following steps:

[0030] The raw materials are controlled to enter the continuous reactor for mixing reaction, and then the obtained heterogeneous mixture is controlled to enter the flat-plate pipeline, the composition of the heterogeneous mixture is photographed, and the residence time distribution density function E(t), the residence time cumulative distribution function F(t) and the average residence time τ of the dispersed phase in the heterogeneous mixture are obtained by calculation; the heterogeneous mixture is collected after flowing out of the flat-plate pipeline.

[0031] The method for monitoring the residence time of a dispersed phase in a continuous reactor provided by the present invention can realize rapid monitoring of the residence time of particles without causing interference to the reaction system, meet the requirements of the continuous reactor for real-time regulation and stability, and significantly improve the operating efficiency and the consistency of the reaction results; based on image recognition, the mass of the dispersed phase in the photographed heterogeneous mixture can be calculated and the concentration of the dispersed phase can be converted, and further calculation can be performed to obtain the residence time distribution density function E(t), the residence time cumulative distribution function F(t) and the average residence time τ of the dispersed phase. Through standardized data analysis, human errors are reduced. Compared with traditional intermittent sampling analysis, the problem of difficulty in accurate sampling and measurement due to the reduction of the dispersed phase concentration in the later stage of measurement can be avoided. At the same time, high-frequency sampling can be achieved to achieve fine optimization of reaction conditions and improve reaction efficiency.

[0032] Preferably, the feed rate of the raw material is 240-360 mL / min, for example, it can be 240 mL / min, 280 mL / min, 320 mL / min, 340 mL / min or 360 mL / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, the discharge rate of the heterogeneous mixture is 240-360 mL / min, for example, 240 mL / min, 280 mL / min, 320 mL / min, 340 mL / min or 360 mL / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] The heterogeneous mixture includes a solid-liquid mixture or an incompatible liquid-liquid mixture.

[0035] Preferably, the particle size of the dispersed phase of particles in the solid-liquid mixture is 0.2-1 mm, for example, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm or 1 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the density of the dispersed phase of particles in the solid-liquid mixture is 1.15-1.38 g / cm 3 , for example, it can be 1.15 g / cm 3 , 1.2g / cm 3 , 1.25g / cm 3 , 1.3g / cm 3 or 1.38 g / cm 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the solid content of the solid-liquid mixture is 1-3%, for example, 1%, 1.5%, 2%, 2.5% or 3%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] Preferably, the type of the particle dispersed phase in the solid-liquid mixture includes at least one of PVC particles, PA66 particles or PS particles.

[0039] Preferably, the solid-liquid mixture further includes 0.05-2% DTAB surfactant, for example, 0.05%, 0.1%, 0.5%, 1%, 1.5% or 2%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] The droplet dispersed phase in the incompatible liquid-liquid mixture includes at least one of silicone oil, kerosene or glycerin, and the continuous phase is incompatible with the droplet dispersed phase.

[0041] The morphology of the dispersed phase of droplets in the immiscible liquid-liquid mixture includes spherical or cake-shaped.

[0042] Preferably, when the particle size of the droplet dispersion phase is less than 1 mm, the droplet dispersion phase is spherical, for example, it can be 0.8 mm, 0.6 mm, 0.5 mm, 0.3 mm or 0.1 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, when the particle size of the droplet dispersion phase is ≥1 mm, the droplet dispersion phase is in a pancake shape, for example, it can be 1.1 mm, 1.3 mm, 1.5 mm, 1.8 mm or 2 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] In the present invention, since the sphericity of the shape of the droplet dispersion phase decreases as the particle size increases, in order to more accurately photograph and analyze the morphology of the droplet dispersion phase, the present invention uses a flat pipe with a thickness of 1 mm to photograph the droplet dispersion phase. According to experimental standards, when the particle size of the droplet dispersion phase is less than 1 mm, it can be considered to be spherical; and when the particle size of the droplet dispersion phase is greater than or equal to 1 mm, the droplet dispersion phase morphology tends to be pancake-shaped.

[0045] Preferably, the density of the dispersed phase of the droplets in the incompatible liquid-liquid mixture is 0.6-0.9 g / cm 3 , for example, it can be 0.6 g / cm 3 , 0.76g / cm 3 , 0.8g / cm 3 or 0.9g / cm 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0046] Preferably, the mass fraction of the dispersed phase of droplets in the incompatible liquid-liquid mixture is 0.1-5%, for example, 0.1%, 1%, 2%, 3% or 5%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] Preferably, the residence time distribution of the dispersed phase of particles in the solid-liquid mixture in the continuous reactor is measured using a pulse method, and the calculation formula of the residence time distribution density function E(t) of the dispersed phase of particles in the solid-liquid mixture is as follows:

[0048]

[0049] Where C(t) is the concentration of the dispersed phase of particles at time t; is the total concentration of the dispersed phase added.

[0050] Preferably, the conversion formula of the residence time distribution density function E(t) of the particle dispersed phase in the solid-liquid mixture is as follows:

[0051]

[0052] Where m(t) is the mass of the dispersed phase of particles at time t, in g; is the total mass of the particle dispersed phase added, in g.

[0053] Since the total mass of the particle dispersed phase is easy to measure, the residence time of the particle dispersed phase is calculated based on the mass of the particle dispersed phase and can therefore be converted using the above formula.

[0054] Preferably, the mass m(t) of the dispersed phase of particles at time t is calculated as follows:

[0055] m(t) = ρ × V(t);

[0056] Where ρ is the density of the dispersed phase of particles, in g / cm 3 ; V(t) is the volume of all dispersed phases of particles in the target number of photos at time t, in cm 3 .

[0057] Since the parameter obtained by intelligent shooting calculation in the present invention is the volume of the dispersed phase of the outlet particles, it can be converted by the above formula.

[0058] Furthermore, the calculation formula of the residence time distribution density function E(t) of the particle dispersed phase in the solid-liquid mixture is as follows:

[0059]

[0060] Preferably, the volume V(t) of all dispersed phases of particles in the target number of photos at time t is calculated as follows:

[0061]

[0062] Where k is the target number of photos; n j is the number of dispersed phase particles in the jth photo; d ij is the particle size of the i-th particle dispersed phase in the j-th photo, in cm.

[0063] Preferably, the calculation formula of the residence time cumulative distribution function F(t) of the particle dispersed phase in the solid-liquid mixture is as follows:

[0064]

[0065] Where t is time and E(t) is the residence time distribution density function of the dispersed phase of particles in the solid-liquid mixture.

[0066] Preferably, the calculation formula for the average residence time τ of the dispersed phase of particles in the solid-liquid mixture is as follows:

[0067]

[0068] Where t is time and E(t) is the residence time distribution density function of the dispersed phase of particles in the solid-liquid mixture.

[0069] In the present invention, different fitting methods can be used according to the morphology of different dispersed phases. For example, if the dispersed phase of particles is spherical, spherical particles can be obtained by shooting, and then the diameter can be obtained. The volume of the standard sphere is further calculated according to the diameter, and the mass is converted to obtain the residence time distribution density function E (t); a high-speed camera is called every 3-5 minutes to take pictures, and the frame rate is adjusted. Each photo uses a computer to automatically identify and count the number and average diameter of the dispersed phase of particles as the residence time distribution density function E (t) at the current moment. In addition, since the peristaltic pump will produce periodic pulse flow when working, there will be deviations in the particle statistics in a short time, so it is necessary to count the particle flow changes at a spacing of 16-25s as the residence time distribution density function E (t) at the current moment. The experimental time is 80-150min, and the system is set to be relatively stable, that is, the difference in the particle mass statistics for four consecutive times is less than 0.01g for the experiment to end.

[0070] Preferably, the residence time distribution of the dispersed phase of the droplets in the incompatible liquid-liquid mixture in the continuous reactor is measured using a step method, and the calculation formula of the residence time cumulative distribution function F(t) of the dispersed phase of the droplets in the incompatible liquid-liquid mixture is as follows:

[0071]

[0072] Where C(t) is the concentration of the dispersed phase of the droplets at time t; C0 is the initial concentration of the dispersed phase of the droplets; C ∞ is the concentration of the dispersed phase of the droplets when steady state is reached.

[0073] Preferably, the concentration C(t) of the dispersed phase of the droplets at time t is calculated as follows:

[0074]

[0075] Where V(t) is the volume of all droplet dispersed phases in the target number of photos at time t, in cm 3 ; V0 is the total volume of the liquid-liquid mixture in the target number of photos at time t, in cm 3 .

[0076] Preferably, when the dispersed phase droplets are spherical, the volume V(t) of all the dispersed phase droplets in the target number of photos at time t is calculated as follows:

[0077]

[0078] Where k is the target number of photos; n j is the number of spherical droplet dispersed phase in the jth photo; d ij is the particle size of the dispersed phase of the i-th spherical droplet in the j-th photo, in cm.

[0079] Preferably, when the dispersed phase of droplets is in a pie shape, the volume V(t) of all pie-shaped dispersed phases of droplets in the target number of photos at time t is calculated as follows:

[0080]

[0081] Where k is the target number of photos; n j A is the number of pie-shaped droplet dispersed phases in the jth photo; ij is the bottom area of ​​the dispersed phase of the ith pancake droplet in the jth photo, in cm 2 ; h is the height of the dispersed phase of the pancake droplets, in cm.

[0082] Preferably, the calculation formula of the residence time distribution density function E(t) of the dispersed phase of the droplets in the incompatible liquid-liquid mixture is as follows:

[0083]

[0084] Where t is time and F(t) is the cumulative distribution function of the residence time of the dispersed phase of the droplets in the immiscible liquid-liquid mixture.

[0085] Preferably, the average residence time τ of the dispersed phase of the droplets in the incompatible liquid-liquid mixture is calculated as follows:

[0086]

[0087] Where t is time and E(t) is the residence time distribution density function of the dispersed phase of the droplets in the immiscible liquid-liquid mixture.

[0088] In the present invention, the average residence time τ and the theoretical average residence time τ' are calculated and compared. When the experimentally obtained τ and the theoretical time τ' are close in value, it can be determined that the monitoring device for the residence time of the dispersed phase has a high accuracy.

[0089] The calculation formula of the theoretical average residence time τ' is as follows:

[0090]

[0091] Among them, V R is the volume of the continuous reactor, and Q is the pumping rate.

[0092] In the present invention, for the measurement of the residence time of the dispersed phase of the droplets in the incompatible liquid-liquid mixture, the pulse method is not effective because the dispersed phase of the droplets may have a high viscosity problem. The step method is used to measure the residence time distribution of the dispersed phase of the droplets in the incompatible liquid-liquid system. Different fitting methods can be used according to the morphology of different dispersed phases. After determining that the dispersed phase of the droplets is spherical or pancake-shaped, the volume of the dispersed phase of the droplets is further calculated, and then the cumulative distribution function of the residence time F(t) is obtained; a high-speed camera is called to take pictures every 3-5 minutes, and the frame rate is adjusted. For each picture, a computer is used to automatically identify and count the number and average diameter of the dispersed phase of the droplets, which is used as the cumulative distribution function of the residence time F(t) at the current moment.

[0093] Preferably, the collected heterogeneous mixture is used as a raw material for subsequent processes.

[0094] Compared with the prior art, the present invention has the following beneficial effects:

[0095] The monitoring device provided by the present invention innovatively combines an online monitoring device to achieve rapid monitoring of the residence time of the dispersed phase without interfering with the reaction system through digital detection of a high-speed camera and a computer, which can meet the real-time regulation and stability requirements of a continuous reactor and significantly improve the operating efficiency and consistency of the reaction results. Based on image recognition, the mass of the dispersed phase in the heterogeneous mixture obtained by photographing can be calculated and the concentration of the dispersed phase can be converted. Further calculations can be performed to obtain the residence time distribution density function E(t), the residence time cumulative distribution function F(t) and the average residence time τ of the dispersed phase. Human errors are reduced through standardized data analysis. Compared with traditional intermittent sampling analysis, the problem of difficulty in accurate sampling and measurement due to a decrease in the concentration of the dispersed phase in the later stage of measurement can be avoided. At the same time, high-frequency sampling can be achieved to achieve fine optimization of reaction conditions and improve reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figure 1 is a schematic structural diagram of a monitoring device for the residence time of a dispersed phase in a continuous reactor provided in Example 1 of the present invention;

[0097] Figure 2 is a schematic diagram of the shooting effect of the high-speed camera provided in Example 1 of the present invention;

[0098] Figure 3 It is a schematic diagram of the computer processing calculation effect provided by Example 1 of the present invention;

[0099] Figure 4 is a graph of the residence time distribution density function E(t) of the particle dispersed phase provided in Example 1 of the present invention;

[0100] Figure 5is a graph of the residence time distribution function F(t) of the particle dispersed phase provided in Example 1 of the present invention;

[0101] Figure 6 is a graph of the residence time distribution density function E(t) of the particle dispersed phase provided in Example 2 of the present invention;

[0102] Figure 7 is a graph of the residence time distribution function F(t) of the particle dispersed phase provided in Example 2 of the present invention;

[0103] Figure 8 is a graph of the residence time distribution density function E(t) of the particle dispersed phase provided in Example 3 of the present invention;

[0104] Fig. 9 is a graph of the residence time distribution function F(t) of the particle dispersed phase provided in Example 3 of the present invention;

[0105] Fig.10 is a graph of the residence time distribution density function E(t) of the particle dispersed phase provided in Example 4 of the present invention;

[0106] Fig.11 is a graph of the residence time distribution function F(t) of the particle dispersed phase provided in Example 4 of the present invention;

[0107] Fig.12 is a graph of the residence time distribution density function E(t) of the particle dispersed phase provided in Example 5 of the present invention;

[0108] Fig.13 is a graph of the residence time distribution function F(t) of the particle dispersed phase provided in Example 5 of the present invention;

[0109] Fig.14 is a graph of the residence time distribution density function E(t) of the particle dispersed phase provided in Example 6 of the present invention;

[0110] Fig.15 is a graph of the residence time distribution function F(t) of the particle dispersed phase provided in Example 6 of the present invention;

[0111] Fig.16 is a schematic diagram of the shooting effect of a high-speed camera provided in Example 7 of the present invention;

[0112] Fig.17 It is a schematic diagram of the computer processing calculation effect provided by Example 7 of the present invention;

[0113] Fig.18 is a graph of the residence time distribution density function E(t) of the droplet dispersed phase provided in Example 7 of the present invention;

[0114] Fig.19is a graph of the residence time distribution function F(t) of the droplet dispersed phase provided in Example 7 of the present invention;

[0115] Among them: 1, raw material tank; 2, gear pump; 3, continuous reactor; 4, peristaltic pump; 5, flat pipe; 6, collecting tank; 7, high-speed camera; 8, computer; 9, reflector; 10, stirring motor; 11, stirring paddle. DETAILED DESCRIPTION

[0116] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0117] In the following embodiments, a high-speed camera is called to take pictures every 5 minutes, with a frame rate of 2000 pictures / s. One picture is taken every 10 pictures, and the number and average diameter of the dispersed phase are automatically identified and counted using a computer, and the residence time distribution density function E(t) of the particle dispersed phase at the current moment or the residence time cumulative distribution function F(t) of the droplet dispersed phase at the current moment is calculated; in addition, since the peristaltic pump will produce periodic pulse flow when working, the dispersed phase statistics in a short time will have deviations, so it is necessary to count the number and average diameter of the dispersed phase at intervals of 16-25s. The experimental time is 80-150 minutes, and the system is set to be relatively stable, that is, the difference in the particle statistics for four consecutive times is less than 0.01g or the difference in the droplet volume is less than 0.01mL, which is the end of the experiment.

[0118] Example 1

[0119] This embodiment provides a monitoring device for the residence time of the dispersed phase in a continuous reactor, such as Figure 1 As shown, the monitoring device includes a raw material tank 1, a gear pump 2, a continuous reactor 3, a peristaltic pump 4, a flat pipe 5 and a collecting tank 6 which are sequentially connected along the material flow direction; the monitoring device also includes a high-speed camera 7, which is used to photograph the solid-liquid mixture on the flat pipe 5, and the high-speed camera 7 is connected to a computer 8; the high-speed camera 7 is provided with a reflector 9;

[0120] The continuous reactor 3 is provided with a feed port and a discharge port respectively; a stirring motor 10 and a stirring paddle 11 connected to the stirring motor 10 are provided inside the continuous reactor 3; the volume of the continuous reactor 3 is 7.2L.

[0121] The method for monitoring the residence time of the dispersed phase in the continuous reactor by the monitoring device comprises the following steps:

[0122] The raw materials are controlled to enter the continuous reactor 3 for mixed reaction, and the feed rate of the raw materials is 240 mL / min. Then the obtained solid-liquid mixture is controlled to enter the flat pipe 5, and the discharge rate of the solid-liquid mixture is 240 mL / min. Then the composition of the solid-liquid mixture is photographed. The schematic diagram of the photographing effect of the high-speed camera is shown in FIG. Figure 2 As shown: the solid-liquid mixture contains PVC particles, the particle size of the PVC particles is 1 mm, and the density is 1.38 g / cm 3 ; The solid content of the solid-liquid mixture is 1%; the solid-liquid mixture is collected after flowing out of the flat pipe 5.

[0123] In this embodiment, the residence time distribution density function E(t), the residence time distribution function F(t) and the average residence time τ of the dispersed phase of the particles in the solid-liquid mixture are obtained by calculation. The schematic diagram of the computer processing calculation effect is shown in FIG. Figure 3 As shown; the residence time distribution density function E (t) is shown in FIG. Figure 4 As shown, the residence time distribution function F(t) is shown in Figure 5 As shown; the theoretical average residence time τ' is 30min, and the average residence time τ in this embodiment is 24.25min. The experimental value is smaller than the theoretical value, indicating that the actual flow in the reactor may tend to be more like plug flow or short-circuit flow, or the particle dispersion is poor.

[0124] Example 2

[0125] This embodiment provides a monitoring device for the residence time of a dispersed phase in a continuous reactor. The difference between the monitoring method for the residence time of a dispersed phase in a continuous reactor performed by the monitoring device and that of Example 1 is that, except for adjusting the feed rate of the raw material to 200 mL / min and the discharge rate of the solid-liquid mixture to 200 mL / min, the rest is the same as Example 1.

[0126] In this embodiment, the residence time distribution density function E(t), the residence time distribution function F(t) and the average residence time τ of the dispersed phase of the particles in the solid-liquid mixture are obtained by calculation; the residence time distribution density function E(t) is shown in FIG. Figure 6 As shown, the residence time distribution function F(t) is shown in Figure 7 As shown; the theoretical average residence time τ' is 36min, and the average residence time τ in this embodiment is 28.11min. Compared with Example 1, the deviation between the experimental value and the theoretical value increases, indicating that reducing the inlet and outlet flow rates will further aggravate the plug flow or short-circuit flow, or the particle dispersion is poor.

[0127] Example 3

[0128] This embodiment provides a monitoring device for the residence time of a dispersed phase in a continuous reactor. The difference between the monitoring method for the residence time of a dispersed phase in a continuous reactor performed by the monitoring device and that of Example 1 is that, except for adjusting the feed rate of the raw material to 400 mL / min and the discharge rate of the solid-liquid mixture to 400 mL / min, the rest is the same as Example 1.

[0129] In this embodiment, the residence time distribution density function E(t), the residence time distribution function F(t) and the average residence time τ of the dispersed phase of the particles in the solid-liquid mixture are obtained by calculation; the residence time distribution density function E(t) is shown in FIG. Figure 8 As shown, the residence time distribution function F(t) is shown in Fig. 9 As shown; the theoretical average residence time τ' is 18min, and the average residence time τ in this embodiment is 17.58min. The average residence time is equivalent to the theoretical value, indicating that a larger inlet and outlet flow rate can improve the plug flow or short-circuit flow in the flow field of the reactor.

[0130] Example 4

[0131] This embodiment provides a monitoring device for the residence time of a dispersed phase in a continuous reactor, and the monitoring device is the same as that in Embodiment 1;

[0132] The method for monitoring the residence time of the dispersed phase in the continuous reactor by the monitoring device comprises the following steps:

[0133] The raw materials were controlled to enter the continuous reactor 3 for mixing reaction, and the feed rate of the raw materials was 360 mL / min. Then, the obtained solid-liquid mixture was controlled to enter the flat pipe 5, and the discharge rate of the solid-liquid mixture was 360 mL / min. Then, the composition of the solid-liquid mixture was photographed: the solid-liquid mixture contained PA66 particles, and the particle size of the PA66 particles was 1 mm and the density was 1.15 g / cm 3 ; The solid content of the solid-liquid mixture is 1%; the solid-liquid mixture is collected after flowing out of the flat pipe 5.

[0134] In this embodiment, the residence time distribution density function E(t), the residence time distribution function F(t) and the average residence time τ of the dispersed phase of the particles in the solid-liquid mixture are obtained by calculation; the residence time distribution density function E(t) is shown in FIG. Fig.10 As shown, the residence time distribution function F(t) is shown in Fig.11 As shown; the theoretical average residence time τ' is 20min, and the average residence time τ in this embodiment is 28.71min. The experimental value is greater than the theoretical value, indicating that incomplete mixing of the fluid in the reactor or the existence of dead zones, or interactions between particles, such as aggregation or sedimentation, may also lead to an increase in the residence time.

[0135] Example 5

[0136] This embodiment provides a monitoring device for the residence time of a dispersed phase in a continuous reactor, and the monitoring device is the same as that in Embodiment 1;

[0137] The method for monitoring the residence time of the dispersed phase in the continuous reactor by the monitoring device comprises the following steps:

[0138] The raw materials were controlled to enter the continuous reactor 3 for mixing reaction, and the feed rate of the raw materials was 360 mL / min. Then, the obtained solid-liquid mixture was controlled to enter the flat pipe 5, and the discharge rate of the solid-liquid mixture was 360 mL / min. Then, the composition of the solid-liquid mixture was photographed: the solid-liquid mixture contained PA66 particles, and the particle size of the PA66 particles was 0.2 mm and the density was 1.15 g / cm 3 ; The solid content of the solid-liquid mixture is 1%; the solid-liquid mixture also includes a DTAB surfactant with a content of 0.2%; the solid-liquid mixture is collected after flowing out of the flat pipe 5.

[0139] In this embodiment, the residence time distribution density function E(t), the residence time distribution function F(t) and the average residence time τ of the dispersed phase of the particles in the solid-liquid mixture are obtained by calculation; the residence time distribution density function E(t) is shown in FIG. Fig.12 As shown, the residence time distribution function F(t) is shown in Fig.13 As shown; the theoretical average residence time τ' is 20min, and the average residence time τ in this embodiment is 17.44min. Compared with Example 4, the addition of an appropriate surfactant can effectively improve and reduce the aggregation or sedimentation of the particles, and the average residence time of the particles in the reactor is reduced.

[0140] Example 6

[0141] This embodiment provides a monitoring device for the residence time of a dispersed phase in a continuous reactor, and the monitoring device is the same as that in Embodiment 1;

[0142] The method for monitoring the residence time of the dispersed phase in the continuous reactor by the monitoring device comprises the following steps:

[0143] The raw materials were controlled to enter the continuous reactor 3 for mixing reaction, and the feed rate of the raw materials was 360 mL / min. Then, the obtained solid-liquid mixture was controlled to enter the flat pipe 5, and the discharge rate of the solid-liquid mixture was 360 mL / min. Then, the composition of the solid-liquid mixture was photographed: the solid-liquid mixture contained PVC particles, and the particle size of the PVC particles was 0.2 mm and the density was 1.38 g / cm 3; The solid content of the solid-liquid mixture is 1%; the solid-liquid mixture also includes a DTAB surfactant with a content of 0.2%; the solid-liquid mixture is collected after flowing out of the flat pipe 5.

[0144] In this embodiment, the residence time distribution density function E(t), the residence time distribution function F(t) and the average residence time τ of the dispersed phase of the particles in the solid-liquid mixture are obtained by calculation; the residence time distribution density function E(t) is shown in FIG. Fig.14 As shown, the residence time distribution function F(t) is shown in Fig.15 As shown; the theoretical average residence time τ' is 20min, and the average residence time τ in this embodiment is 14.75min. Compared with Example 5, different types of particles are replaced, and the rest remain unchanged, and the average residence time decreases, indicating that the type of particles will affect the residence time of particles in the reactor.

[0145] Example 7

[0146] This embodiment provides a monitoring device for the residence time of a dispersed phase in a continuous reactor, and the monitoring device is the same as that in Embodiment 1;

[0147] The method for monitoring the residence time of the dispersed phase in the continuous reactor by the monitoring device comprises the following steps:

[0148] The raw materials are controlled to enter the continuous reactor 3 for mixed reaction, and the feed rate of the raw materials is 240 mL / min. Then, the obtained incompatible liquid-liquid mixture is controlled to enter the flat pipe 5, and the discharge rate of the liquid-liquid mixture is 240 mL / min. Then, the composition of the incompatible liquid-liquid mixture is photographed. The schematic diagram of the photographing effect of the high-speed camera is shown in FIG. Fig.16 As shown: the incompatible liquid-liquid mixture contains silicone oil droplets, and the density of the silicone oil droplets is 0.76 g / cm 3 ; The mass fraction of the dispersed phase of droplets in the incompatible liquid-liquid mixture is 5%; the incompatible liquid-liquid mixture is collected after flowing out of the flat pipe 5.

[0149] In this embodiment, the residence time cumulative distribution function F(t), residence time distribution density function E(t) and average residence time τ of the dispersed phase of the droplets in the incompatible liquid-liquid mixture are calculated, and the schematic diagram of the computer processing calculation effect is shown as follows: Fig.17 As shown; the residence time distribution density function E (t) is shown in FIG. Fig.18 As shown, the residence time distribution function F(t) is shown in Fig.19As shown; the theoretical average residence time τ' is 20min, and the average residence time τ in this embodiment is 36.97min. The experimental value is greater than the theoretical value, indicating that incomplete mixing of the fluid or the existence of dead zones in the continuous reactor, or interactions between dispersed phases of droplets, such as aggregation or sedimentation, may also lead to an increase in the residence time.

[0150] In summary, the monitoring device provided by the present invention innovatively combines an online monitoring device to achieve rapid monitoring of the residence time of the dispersed phase without interfering with the reaction system through digital detection of a high-speed camera and a computer, which can meet the real-time regulation and stability requirements of continuous reactors, and significantly improve operating efficiency and consistency of reaction results; through standardized data analysis, human errors are reduced, and high-frequency sampling can be achieved, so as to achieve fine optimization of reaction conditions and improve reaction efficiency.

[0151] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for monitoring the residence time of a dispersed phase in a continuous reactor, characterized in that: The monitoring method is carried out using a monitoring device; The monitoring device comprises a raw material storage device, a feed control device, a continuous reactor, a discharge control device, a flat pipe and a collecting device which are sequentially connected along the material flow direction; the monitoring device also comprises a high-speed camera, which is used to photograph the heterogeneous mixture on the flat pipe, and the high-speed camera is connected to a computer; The monitoring method comprises the following steps: Controlling the raw materials to enter the continuous reactor for mixing reaction, and then controlling the obtained heterogeneous mixture to enter the flat-plate pipeline, photographing the composition of the heterogeneous mixture and obtaining the residence time distribution density function E(t), the residence time cumulative distribution function F(t) and the average residence time τ of the dispersed phase in the heterogeneous mixture by calculation; and collecting the heterogeneous mixture after it flows out of the flat-plate pipeline; The heterogeneous mixture includes a solid-liquid mixture or an incompatible liquid-liquid mixture; The calculation formula of the residence time distribution density function E(t) of the particle dispersed phase in the solid-liquid mixture is as follows: Where C(t) is the concentration of the dispersed phase of particles at time t; is the total concentration of the dispersed phase added; The conversion formula of the residence time distribution density function E(t) of the particle dispersed phase in the solid-liquid mixture is as follows: Where m(t) is the mass of the dispersed phase of particles at time t, in g; is the total mass of the particle dispersed phase added, in g.

2. The monitoring method according to claim 1, characterized in that: The number of the raw material storage devices is ≥1.

3. The monitoring method according to claim 1, characterized in that: The feed control device includes a gear pump.

4. The monitoring method according to claim 1, characterized in that: The discharge control device comprises a peristaltic pump or a gear pump.

5. The monitoring method according to claim 1, characterized in that: The high-speed camera is provided with a reflecting device.

6. The monitoring method according to claim 1, characterized in that: The continuous reactor is provided with a feed inlet and a discharge outlet.

7. The monitoring method according to claim 6, characterized in that: The number of the feed port and the discharge port is independently ≥ 1.

8. The monitoring method according to claim 1, characterized in that: A stirring motor and a stirring paddle connected to the stirring motor are arranged inside the continuous reactor.

9. The monitoring method according to claim 1, characterized in that: The volume of the continuous reactor is 0.2-50L.

10. The monitoring method according to claim 1, characterized in that: The feed rate of the raw material is 240-360 mL / min.

11. The monitoring method according to claim 1, characterized in that: The discharge rate of the heterogeneous mixture is 240-360 mL / min.

12. The monitoring method according to claim 1, characterized in that: The particle size of the dispersed phase particles in the solid-liquid mixture is 0.2-1 mm.

13. The monitoring method according to claim 1, characterized in that: The density of the dispersed phase of particles in the solid-liquid mixture is 1.15-1.38 g / cm 3 .

14. The monitoring method according to claim 1, characterized in that: The solid content of the solid-liquid mixture is 1-3%.

15. The monitoring method according to claim 1, characterized in that: The morphology of the dispersed phase of droplets in the immiscible liquid-liquid mixture includes spherical or cake-shaped.

16. The monitoring method according to claim 15, characterized in that: When the particle size of the droplet dispersed phase is less than 1 mm, the droplet dispersed phase is spherical.

17. The monitoring method according to claim 15, characterized in that: When the particle size of the droplet dispersed phase is ≥1 mm, the droplet dispersed phase is in a cake shape.

18. The monitoring method according to claim 1, characterized in that: The density of the dispersed phase of the droplets in the incompatible liquid-liquid mixture is 0.6-0.9 g / cm 3 .

19. The monitoring method according to claim 1, characterized in that: The mass fraction of the droplet dispersed phase in the incompatible liquid-liquid mixture is 0.1-5%.

20. The monitoring method according to claim 1, characterized in that: The calculation formula of the mass m(t) of the particle dispersed phase at time t is as follows: m(t) = ρ × V(t); Where ρ is the density of the dispersed phase of particles, in g / cm 3 ; V(t) is the volume of all dispersed phases of particles in the target number of photos at time t, in cm 3 .

21. The monitoring method according to claim 20, characterized in that: The calculation formula for the volume V(t) of all the dispersed phases of particles in the target number of photos at time t is as follows: Where k is the target number of photos; n j is the number of dispersed phase particles in the jth photo; d ij is the particle size of the i-th particle dispersed phase in the j-th photo, in cm.

22. The monitoring method according to claim 1, characterized in that: The calculation formula of the residence time cumulative distribution function F(t) of the particle dispersed phase in the solid-liquid mixture is as follows: Where t is time and E(t) is the residence time distribution density function of the dispersed phase of particles in the solid-liquid mixture.

23. The monitoring method according to claim 1, characterized in that: The calculation formula for the average residence time τ of the dispersed phase of particles in the solid-liquid mixture is as follows: Where t is time and E(t) is the residence time distribution density function of the dispersed phase of particles in the solid-liquid mixture.

24. The monitoring method according to claim 1, characterized in that: The calculation formula of the residence time cumulative distribution function F(t) of the droplet dispersed phase in the incompatible liquid-liquid mixture is as follows: Where C(t) is the concentration of the dispersed phase of the droplets at time t; C0 is the initial concentration of the dispersed phase of the droplets; C ∞ is the concentration of the dispersed phase of the droplets when steady state is reached.

25. The monitoring method according to claim 24, characterized in that: The calculation formula of the concentration C(t) of the droplet dispersed phase at time t is as follows: Where V(t) is the volume of all droplet dispersed phases in the target number of photos at time t, in cm 3 ; V0 is the total volume of the liquid-liquid mixture in the target number of photos at time t, in cm 3 .

26. The monitoring method according to claim 25, characterized in that: When the dispersed phase of the droplets is spherical, the calculation formula for the volume V(t) of all the dispersed phases of the spherical droplets in the target number of photos at time t is as follows: Where k is the target number of photos; n j is the number of spherical droplet dispersed phase in the jth photo; d ij is the particle size of the dispersed phase of the i-th spherical droplet in the j-th photo, in cm.

27. The monitoring method according to claim 25, characterized in that: When the dispersed phase of the droplets is in the shape of a pancake, the calculation formula for the volume V(t) of all the dispersed phases of the pancake-shaped droplets in the target number of photos at time t is as follows: Where k is the target number of photos; n j A is the number of pie-shaped droplet dispersed phases in the jth photo; ij is the bottom area of ​​the dispersed phase of the ith pancake droplet in the jth photo, in cm 2 ; h is the height of the dispersed phase of the pancake droplets, in cm.

28. The monitoring method according to claim 24, characterized in that: The calculation formula of the residence time distribution density function E(t) of the droplet dispersed phase in the incompatible liquid-liquid mixture is as follows: Where t is time and F(t) is the cumulative distribution function of the residence time of the dispersed phase of the droplets in the immiscible liquid-liquid mixture.

29. The monitoring method according to claim 28, characterized in that: The calculation formula for the average residence time τ of the dispersed phase of the droplets in the incompatible liquid-liquid mixture is as follows: Where t is time and E(t) is the residence time distribution density function of the dispersed phase of the droplets in the immiscible liquid-liquid mixture.

30. The monitoring method according to any one of claims 1 to 29, characterized in that: The collected heterogeneous mixture is used as a raw material for subsequent processes.

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