Bed mass transfer performance measuring device and method based on gas distributor
By directly passing the liquid phase and gas into the bed, forming a micro bubble group and measuring the mass transfer performance in the bed, the problems of large liquid phase reaction losses and errors in the prior art are solved, and accurate and real-time beds are achieved The measurement of layer mass transfer performance improves industrial production efficiency and economic benefits.
Patent Information
- Application Number
- CN202411499053.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-25
- Publication Date
- 2025-01-07
AI Technical Summary
In the existing bed mass transfer performance measurement methods, the liquid phase reaction components and the gas phase contact outside the bed for a long time lead to large losses, inaccurate measurement, and the system error difference under different operating conditions is too large, so it is impossible to effectively detect bed transmission. Quality performance affects industrial production.
Design a mass transfer performance measurement device for beds based on gas distributors. By directly passing into the liquid phase containing reaction components in the bed, use auxiliary liquid and gas flow controller to form a micro bubble group to avoid reaction outside the bed. , directly measure the mass transfer performance in the bed, and calculate the volume mass transfer coefficient by pH measurement using CO2-NaOH system.
It realizes accurate and real-time measurement of the mass transfer performance of the bed, reduces system errors, facilitates adjustment of operating conditions and equipment parameters, and improves production efficiency and economic benefits.
Smart Images
Figure CN119269340A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of fixed bed mass transfer, and relates to a device and method for measuring bed mass transfer performance based on a gas distributor. Background Art
[0002] In my country, fixed-bed bubbling reactors are widely used in chemical, petrochemical, metallurgical and other fields. A gas distribution device is generally installed at the bottom, such as a membrane distributor, a Venturi distributor, a orifice plate distributor, an ultra-gravity rotary distributor, etc.
[0003] The bed mass transfer performance of the fixed-bed bubbling reactor has a decisive influence on the product conversion rate, and the quality of the mass transfer performance directly affects the economic benefits of industrial production. The inability to detect the bed mass transfer performance will lead to a lack of research on the production mechanism and production process, and it is impossible to coordinate and control the different variables in each production link from a macro perspective, resulting in waste of raw materials, high production costs, and low production efficiency. Control based on the improvement of bed mass transfer performance as an indicator can effectively guide the optimization of operating conditions and equipment parameters, thereby improving productivity and promoting technological progress. Therefore, accurate and effective bed mass transfer performance measurement methods are very important for fixed bed production guidance.
[0004] The existing bed mass transfer performance measurement method is generally a cold model, using a single liquid phase feed, and the reaction liquid flows through the gas distributor after being prepared outside the equipment. 2 -NaOH solution system and O 2 -Na 2 SO 3 In the solution system, gas-liquid mass transfer is carried out in the bed, and then the volumetric mass transfer coefficient is calculated by measuring the gas solubility in the liquid phase at the bed inlet. In this process, the liquid phase reaction components and the gas phase are in contact for a long time outside the bed, which will cause violent reactions and great losses, resulting in inaccurate measurements of the bed mass transfer performance. At low flow rates, there may even be situations where the material is exhausted and cannot be tested. Moreover, under different operating conditions, the degree of material loss is different, the initial state of the microbubbles at the bed inlet is different, and the gas dissolution margin in the liquid phase is different, resulting in large differences in system errors under different conditions.
[0005] Therefore, it is necessary to develop practical and accurate devices and methods for measuring bed mass transfer performance. Summary of the invention
[0006] Aiming at the problems existing in the traditional bed mass transfer performance measurement, the present invention proposes a novel bed mass transfer performance measurement device and method based on a gas distributor.
[0007] In order to achieve the above object, the present invention is implemented by adopting the following technical solutions: A device for measuring bed mass transfer performance based on a gas distributor comprises a device body, wherein the device body comprises a fixed bed, a membrane distributor, an auxiliary liquid storage tank, a gas storage tank and a reaction liquid storage tank, the membrane distributor is arranged at the lower part of the fixed bed, an upper viewing window is arranged above the fixed bed, and a lower viewing window is arranged between the fixed bed and the membrane distributor; the membrane distributor comprises a membrane assembly and a membrane tube, the outlet end of the auxiliary liquid storage tank is connected to the lower part of the membrane assembly and communicates with the membrane tube pipe side, the gas storage tank is connected to the side of the membrane assembly and communicates with the membrane tube shell side, the upper part of the membrane tube pipe side is connected to the bottom end of the lower viewing window through the top of the membrane assembly, the top of the upper viewing window is open, and a material outlet pipeline is arranged on the side of the upper viewing window; an auxiliary liquid feed pump is arranged between the auxiliary liquid storage tank and the membrane assembly, a reaction liquid feed pump is arranged between the reaction liquid storage tank and the fixed bed, and a gas flow controller is arranged between the gas storage tank and the membrane assembly.
[0008] Preferably, the end of the reaction liquid storage tank outlet pipeline is provided with a plurality of liquid outlets, such as a three-hole needle, and the outlet position needs to be deep inside the fixed bed layer (the middle position of the bed layer) to ensure that the reaction liquid can be evenly input. The entrance of the reaction liquid storage tank infusion pipeline entering the bed layer is 1 cm away from the bottom of the bed layer, and the infusion pipeline is connected to the side wall of the bed layer using an adapter.
[0009] The method for measuring the mass transfer performance of the bed using the above device comprises the following steps: (1) Filling the fixed bed with catalyst particles and vibrating the fixed bed to ensure that the catalyst particles are densely packed; (2) Open and adjust the gas flow controller so that the gas flow rate reaches the set value; open the auxiliary liquid pump so that the gas forms microbubble groups under the shearing action of the auxiliary liquid and flows upward into the lower window, bed layer, and upper window in sequence; (3) After the microbubble group fills the upper window, turn on the reaction liquid feed pump to carry out gas-liquid reaction. After the reaction is stable, sample and test the material outlet pipeline on the side of the upper window to calculate the volume mass transfer coefficient of the bed.
[0010] The auxiliary liquid is required not to react with the gas phase and to be miscible with the reaction liquid, that is, a liquid phase that does not contain reaction components; the reaction liquid refers to a liquid that contains substances that can react with the gas phase.
[0011] The auxiliary liquid is n-butanol solution, the reaction liquid is NaOH solution, and the gas phase is CO 2 Taking the catalyst carrier particles as spherical alumina particles as an example, during the detection, the mass concentration of n-butanol solution is preferably 0.05-0.5wt%; the molar concentration of NaOH solution is preferably 0.2-2mol / L, and the catalyst particle diameter is preferably 1-5mm. 2The flow rate of gas is 50-150mL / min; the flow rate of n-butanol solution controlled by the bottom feed pump is 10-50mL / min. The delivery rate of NaOH solution controlled by the side feed pump is 0.5-2.5mL / min. The above parameters such as material concentration and flow rate can also be adjusted according to actual production conditions.
[0012] The system test method is: Step 1: Install an infusion pipe on the side wall of the bed with a three-hole needle at the head, then randomly fill the catalyst carrier particles into the bed and knock them to achieve a dense state.
[0013] Step 2: Use deionized water to prepare n-butanol solution and NaOH solution respectively.
[0014] Step 3: Turn on the gas flow controller and introduce CO into the membrane distributor at a certain volume flow rate. 2 gas, turn on the bottom feed pump to deliver the n-butanol solution without reactive components at a certain volume flow rate.
[0015] Step 4: When liquid flows out of the upper window tube liquid phase outlet, turn on the side feed pump to deliver NaOH solution to the bed at a certain volume flow rate. Collect the liquid phase sample flowing out of the upper window tube liquid phase outlet and measure the pH. When it is stable, take the value. The hydrogen ion concentration in the liquid phase at the bed outlet at this pH c (H+) The following formula (1): .
[0016] Where: c (H+) is the hydrogen ion concentration in the liquid phase, in mol / L.
[0017] The following formula (2) is obtained from the acid-base equilibrium theory: .
[0018] Substituting the hydrogen ion concentration into (2), we can obtain the CO 2 Solubility of a gas in a liquid phase.
[0019] in, c (CO2) For CO 2 The solubility of a gas in a liquid phase, expressed in mol / L.
[0020] K H2O is the ionic product constant of water, which is 10 -14 .
[0021] K 1is the chemical equilibrium constant 1, with a value of 10 -6.352 .
[0022] K 2 is the chemical equilibrium constant 2, with a value of 10 -10.329 .
[0023] From the double membrane theory and material balance, the following formula (3) can be obtained: .
[0024] in, k L a is the volumetric mass transfer coefficient of the bed, in s -1 .
[0025] Q L is the liquid phase volume flow rate, in mL / min.
[0026] V is the fixed bed volume, in cm 3 .
[0027] c * For CO 2 The saturated solubility in the liquid phase is 0.189 mol / L.
[0028] c in For CO 2 Solubility at the bed inlet, in mol / L.
[0029] c out For CO 2 The solubility at the bed outlet, in mol / L.
[0030] Since there is no reaction outside the bed, c in = 0. 2 Substituting the gas solubility in the liquid phase into formula (3) can calculate the volumetric mass transfer coefficient of the bed.
[0031] Compared with the prior art, the advantages and positive effects of the present invention are: 1. The present invention proposes a novel device for measuring the mass transfer performance of a bed, which enables the liquid phase containing the reaction components to be directly introduced into the bed without passing through a gas distributor, thereby effectively avoiding the reaction of the gas-liquid materials before entering the bed, eliminating the loss of the reaction outside the bed, and only measuring the mass transfer performance between the materials in the bed, thus solving the problem of excessive error in the bed mass transfer performance test system in chemical production.
[0032] 2. The bed mass transfer performance measurement method of the present invention is simple, CO 2 -The mass transfer detection of the NaOH system can be calculated by real-time measurement of the pH value of the bed effluent liquid phase, which is convenient and accurate, and realizes in-situ measurement.
[0033] 3. The parameters of each condition are easy to adjust, which solves the problem that the traditional method cannot examine the influence of the concentration of liquid phase reaction components on the mass transfer performance of the bed, and facilitates the optimization of various parameters in actual industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 It is a schematic structural diagram of a device for measuring bed mass transfer performance based on a gas distributor according to the present invention.
[0035] Figure 2 Schematic diagram of the membrane component structure of the membrane distributor.
[0036] Figure 3 Schematic diagram of the multi-channel ceramic membrane tube structure of the membrane distributor.
[0037] Figure 4 for Figure 3 Cross-sectional view of a multi-channel ceramic membrane tube.
[0038] Figure 5 Schematic diagram of the structure of the bed acrylic tube.
[0039] Figure 6 This is a cross-sectional view of the acrylic tube in the bed.
[0040] The reference numerals are: 1-butanol solution storage tank, 2-bottom feed pump, 3-gas flow controller, 4-CO 2 Gas cylinder, 5-side feed pump, 6-NaOH solution storage tank, 7-membrane distributor, 8-lower window tube, 9-bed, 10-upper window tube, A-n-butanol solution storage tank outlet, B-bottom feed pump inlet, C-bottom feed pump outlet, D-membrane distributor bottom inlet, E-gas flow controller inlet, F-gas flow controller outlet, G-membrane distributor side wall inlet, H-NaOH solution storage tank outlet, I-side feed pump inlet, J-side feed pump outlet, K-infusion pipeline outlet, L-upper window tube gas phase outlet, M-upper window tube liquid phase outlet, 11-membrane assembly, 12-multi-channel ceramic membrane tube. DETAILED DESCRIPTION
[0041] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.
[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.
[0043] Example 1 This embodiment provides a method for realizing CO 2 - Typical measurement device for detecting bed mass transfer performance in NaOH system, such as Figure 1-6 As shown, it includes a n-butanol solution storage tank 1, a bottom feed pump 2, a gas flow controller 3, a CO 2 Gas cylinder 4, side feed pump 5, NaOH solution storage tank 6, membrane distributor 7, lower window tube 8, bed 9, upper window tube 10. The bottom feed pump includes a feed pump inlet B and a feed pump outlet C, the feed pump inlet B is connected to the outlet A of the n-butanol solution storage tank, and the feed pump outlet C is connected to the bottom inlet D of the membrane distributor. The membrane distributor 7 is composed of a membrane assembly 11 and a multi-channel ceramic membrane tube 12 for fixing a multi-channel ceramic membrane tube, and the top of the membrane distributor 7 is connected to the bottom of the lower window tube 8 by a flange. The bed 9 and the lower window tube 8 and the upper window tube 10 are all connected by threads, and a filter is set between the bed 9 and the lower window tube 8 and the upper window tube 10 to intercept catalyst carrier particles. The membrane assembly 11 is commercially available and customized, and after the membrane assembly fixes the membrane tube, there is no gap between the upper and lower ends of the membrane tube and the shell side, so that the gas can only enter the tube side from the shell side through the membrane hole, and the auxiliary liquid can smoothly enter the lower window from the tube side. The upper window tube 10 has an opening at the top, which is marked as a gas phase outlet L, and a liquid phase outlet M is provided on the side wall. The gas flow controller 3 includes an inlet E and an outlet F. The inlet E and the CO 2 The gas cylinder 4 is connected, and the outlet F is connected to the membrane distributor side wall inlet G. The side feed pump 5 includes a feed pump inlet I and a feed pump outlet J. The feed pump inlet I is connected to the NaOH solution storage tank outlet H, and the feed pump outlet J is connected to the infusion pipeline outlet K. The infusion pipeline passes through the side wall of the bed, and the head is a three-hole needle. The CO passing through the membrane distributor G 2 Microbubbles and n-butanol solution flow upward into bed layer 9, and NaOH solution flows directly into bed layer 9 from outlet K of the infusion pipeline. 2 React with NaOH, the remaining gas phase escapes from the gas phase outlet L of the upper window tube, and the remaining liquid phase flows out from the liquid phase outlet M of the upper window tube, and the pH value is collected and measured.
[0044] In this embodiment, the lower window tube 8, the bed layer 9, and the upper window tube 10 are all made of round tubes with an inner diameter of 2 cm and an outer diameter of 4 cm, and are made of polymethyl methacrylate. The bed layer 9 is 20 cm long, and the lower window tube 8 and the upper window tube are both 5 cm long. The catalyst particles randomly filled in the bed layer 9 have a diameter of 1 mm, are made of α-alumina, and are spherical in shape.
[0045] The operation steps are as follows: use deionized water to prepare 5L of 0.25wt% n-butanol solution and 500mL of 2mol / L NaOH solution, and add them to n-butanol solution storage tank 1 and NaOH solution storage tank 6 respectively. Turn on gas flow controller 3, CO 2 The gas volume flow rate is 150 mL / min, and it enters the membrane module 7 shell side through the membrane distributor side wall inlet G. Turn on the bottom feed pump 2, control the volume flow rate of the n-butanol solution to 47.5 mL / min, and enter the membrane module 7 tube side through the bottom inlet D of the membrane distributor to shear CO 2 The gas forms a microbubble group, and then the gas-liquid mixed phase fluid flows upward into the bed layer 9. The side feed pump 5 is turned on, and the volume flow rate of the NaOH solution is 2.5 mL / min, and it enters the bed layer 9 from the outlet K of the infusion pipeline. The fluid is mixed evenly in the bed layer 9, dissolving CO 2 The liquid phase flowing out of the upper window tube liquid phase outlet M is collected, and the pH value is taken when it is stable. The volumetric mass transfer coefficient is further calculated to be 0.01202s -1 .
[0046] Example 2 The difference between this embodiment and embodiment 1 is that CO 2 The gas volume flow rate was set to 60 mL / min, the n-butanol solution volume flow rate was 9.5 mL / min, and the NaOH solution volume flow rate was 0.5 mL / min. The liquid phase flowing out of the upper window tube liquid phase outlet M was collected. When the pH value was stable, the volume mass transfer coefficient was calculated to be 0.00285 s -1 .
[0047] Example 3 The difference between this embodiment and embodiment 1 is that CO 2 The gas volume flow rate was set to 30 mL / min, the volume flow rate of the n-butanol solution was 28.5 mL / min, and the volume flow rate of the NaOH solution was 1.5 mL / min. The liquid phase flowing out of the liquid phase outlet M of the upper window tube was collected. When the pH value was stable, the volume mass transfer coefficient was calculated to be 0.00154 s -1 .
[0048] Example 4 The difference between this embodiment and embodiment 1 is that CO 2 The gas volume flow rate was set to 60 mL / min, and the other conditions were kept the same as the operation process. The liquid phase flowing out of the liquid phase outlet M of the upper window tube was collected, and the pH value was taken when it was stable. The volume mass transfer coefficient was further calculated to be 0.00504 s -1 .
[0049] Example 5 The difference between this embodiment and embodiment 4 is that the catalyst particle diameter is 1.6 mm. The other conditions and operation procedures remain the same. The liquid phase flowing out of the upper window tube liquid phase outlet M is collected, and the value is taken when its pH value is stable. The volume mass transfer coefficient is further calculated to be 0.00499s -1 .
[0050] Example 6 The difference between this embodiment and embodiment 4 is that the catalyst particle diameter is 2.5 mm. The other conditions and operation procedures remain the same. The liquid phase flowing out of the upper window tube liquid phase outlet M is collected, and the value is taken when the pH value is stable. The volume mass transfer coefficient is further calculated to be 0.00490s -1 .
[0051] From the above examples 1-6, it can be seen that under different process conditions, gas CO 2 The mass transfer coefficient between the gas and liquid is very different from that of the NaOH solution. In Example 1, the mass transfer coefficient of the two is the highest. In actual industrial production, this operating condition is adopted, and the mass transfer efficiency between gas and liquid is the highest, which can effectively save raw materials, improve output rate and reduce production costs.
[0052] It should be noted that Example 1 only provides a feasible method for fixed bed mass transfer detection. According to actual production conditions, the types of materials, feed parameters and other conditions in the present invention may also have other implementation forms, and the present invention does not limit this.
[0053] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.
Claims
1. A device for measuring bed mass transfer performance based on a gas distributor, characterized in that: The invention comprises a device body, which comprises a fixed bed, a membrane distributor, an auxiliary liquid storage tank, a gas storage tank and a reaction liquid storage tank. The membrane distributor is arranged at the lower part of the fixed bed, an upper viewing window is arranged above the fixed bed, and a lower viewing window is arranged between the fixed bed and the membrane distributor; the membrane distributor comprises a membrane assembly and a membrane tube, the outlet end of the auxiliary liquid storage tank is connected to the lower part of the membrane assembly and communicates with the membrane tube pipe side, the gas storage tank is connected to the side of the membrane assembly and communicates with the membrane tube shell side, the upper part of the membrane tube pipe side is connected to the bottom end of the lower viewing window through the top of the membrane assembly, the top of the upper viewing window is open, and a material outlet pipeline is arranged on the side of the upper viewing window; an auxiliary liquid feed pump is arranged between the auxiliary liquid storage tank and the membrane assembly, a reaction liquid feed pump is arranged between the reaction liquid storage tank and the fixed bed, and a gas flow controller is arranged between the gas storage tank and the membrane assembly.
2. The device for measuring bed mass transfer performance based on a gas distributor according to claim 1, characterized in that: The end of the outlet pipeline of the reaction liquid storage tank goes deep into the fixed bed and is provided with a plurality of liquid outlets.
3. A method for measuring bed mass transfer performance using the device according to claim 1 or 2, characterized in that: Here are the steps: (1) Filling the fixed bed with catalyst particles and vibrating the fixed bed to ensure that the catalyst particles are densely packed; (2) Open and adjust the gas flow controller so that the gas flow rate reaches the set value; open the auxiliary liquid pump so that the gas forms microbubble groups under the shearing action of the auxiliary liquid and flows upward into the lower window, bed layer, and upper window in sequence; (3) After the microbubble group fills the upper window, turn on the reaction liquid feed pump to carry out gas-liquid reaction. After the reaction is stable, sample and test the material outlet pipeline on the side of the upper window to calculate the volume mass transfer coefficient of the bed.