A method for predicting liquid holdup in packed tower

Abstract

The present invention discloses a method for predicting liquid holdup in a packed tower, the method comprising: replacing the internal structure of the packed tower with a mathematical model, establishing a three-dimensional mathematical model of the packed tower; constructing a packing unit model; constructing a point fluid model and a line fluid model; integrating the point fluid model and the line fluid model into a packing unit model; constructing a packing wall unit model according to the three-dimensional mathematical model of the packed tower; constructing a vertical fluid model and a biased fluid model; integrating the vertical fluid model and the biased fluid model into a packing wall unit model; analyzing the packed tower according to the packing unit model and the packing wall unit model; and predicting the liquid holdup in the packed tower using the three-dimensional mathematical model of the packed tower. The method of the present invention can accurately predict the liquid holdup in the corrugated plate packed tower under a small amount of test conditions, thereby meeting the actual production needs of the packed tower.

Description

Technical Field

[0001] The invention relates to the technical field of packed towers, and in particular to a method for predicting liquid holdup in a packed tower. Background Art

[0002] A packed tower is a structure with low fluid resistance, suitable for large gas processing volume and small liquid volume. The liquid flows from top to bottom along the surface of the packing, and the gas and liquid are in countercurrent or parallel flow, depending on the specific reaction. The amount of liquid in the packed tower is small. Regardless of the gas phase or liquid phase, its flow pattern in the tower is close to piston flow. If solid phase is generated during the reaction, it is not suitable to use a packed tower.

[0003] The packed tower is filled with fillers of various shapes (called fillers) inside the tower, so that the liquid flows along the surface of the fillers to form a liquid film, which is dispersed in the continuously flowing gas. The contact surface between the gas and liquid phases is on the liquid film surface of the fillers. It is a membrane contact equipment.

[0004] The packing for Katapak chemical reactor of Sulzer Company is a corrugated packing made of double-layer wire mesh, and the catalyst is installed in the interlayer of the wire mesh. The Optiflow structured packing of Sulzer Company has a unique structure, which is made of thin plates stamped, folded and assembled. It changes the traditional mode of liquid phase flowing stably over a long distance on the surface of Mellapak plate ferry packing. Through the tortuous and constantly changing direction of the plates, it promotes the dispersion-polymerization-redispersion cycle of the liquid phase, ensures good contact with the gas phase, and keeps the mass transfer surface updated. It combines the advantages of structured packing and random packing, and has both high efficiency and great flux. It is said that compared with conventional tower plates and packing, under the same separation efficiency conditions, the processing capacity can be increased by 20% to 25%, and under the same processing capacity, the mass transfer efficiency can be increased by 50%.

[0005] Corrugated plate packed towers have outstanding advantages in the field of packed towers and are suitable for mass production scenarios, so we need a method to predict the liquid holdup in packed towers.

[0006] Currently, there is no method for predicting the liquid holdup of a corrugated plate packing tower in Chinese invention patents.

[0007] Chinese invention patent CN103559378A is a method for predicting the liquid holding capacity in a random packing tower, comprising the following steps: 1) selecting flow parameters that affect the liquid holding capacity as input variables of the model and establishing data samples; 2) applying the RRELM method to establish a liquid holding capacity model based on the FLOO-CV criterion for the data characteristics collected in step 1), and establishing an initial RELM model for predicting the liquid holding capacity; 3) applying the RRELM model established in step 2) based on the FLOO-CV criterion to calculate the final predicted value of the liquid holding capacity: wherein Ht is the hidden layer output matrix generated according to the input Xt of the test sample, which is the final predicted value. This invention analyzes the liquid holding capacity of a random packing tower by establishing a RRELM model, which can be used as a comparative reference, but has limited reference value for corrugated plate packing towers. Summary of the invention

[0008] The invention provides a method for predicting the liquid holdup in a packed tower, so as to solve the technical problem that there is no prediction method for a corrugated plate packed tower.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] Step S1: replacing the internal structure of the packed tower with a mathematical model to establish a three-dimensional mathematical model of the packed tower;

[0011] Step S2: constructing a packing unit model according to the three-dimensional mathematical model of the packed tower, wherein the packing unit model is composed of a point fluid model and a line fluid model;

[0012] Step S3: constructing a point fluid model and a line fluid model;

[0013] Step S4: integrating the point fluid model and the line fluid model into a packing unit model;

[0014] Step S5: constructing a packing wall unit model according to the three-dimensional mathematical model of the packed tower, wherein the packing wall unit model is composed of a vertical fluid model and an offset fluid model;

[0015] Step S6: constructing a vertical fluid model and a biased fluid model;

[0016] Step S7: integrating the vertical fluid model and the offset fluid model into a packing wall unit model;

[0017] Step S8: analyzing the packed tower according to the packing unit model and the packing wall unit model;

[0018] Step S9: using a three-dimensional mathematical model of a packed tower to predict the liquid holdup in the packed tower.

[0019] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0020] The present invention replaces the internal structure of the packed tower with a mathematical model, establishes a three-dimensional mathematical model of the packed tower; constructs a packing unit model; constructs a point fluid model and a line fluid model; integrates the point fluid model and the line fluid model into a packing unit model; constructs a packing wall unit model according to the three-dimensional mathematical model of the packed tower; constructs a vertical fluid model and a biased fluid model; integrates the vertical fluid model and the biased fluid model into a packing wall unit model; analyzes the packed tower according to the packing unit model and the packing wall unit model; and uses the three-dimensional mathematical model of the packed tower to predict the liquid holding capacity in the packed tower. The method of the present invention can more accurately predict the liquid holding capacity in the corrugated plate packed tower under a small amount of test conditions, meeting the actual production needs of the packed tower. The present invention can accurately predict the common corrugated plate packed towers without considering the unit size and inclination angle of the corrugated plate. In actual production, most packed towers use corrugated plates as the main body, so the applicability of the present invention is very wide. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 is a flow chart of a method for predicting liquid holdup in a packed tower provided in an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of a corrugated plate provided in an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of an idealized model of a corrugated plate provided in an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of a point fluid model provided by an embodiment of the present invention;

[0026] Figure 5 A schematic diagram of a line fluid model provided by an embodiment of the present invention;

[0027] Figure 6 A schematic diagram of a vertical fluid model provided by an embodiment of the present invention;

[0028] Figure 7 A schematic diagram of a bias fluid model provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] Example 1

[0031] The present embodiment provides a method for predicting the liquid holdup in a packed tower, which replaces the internal structure of the packed tower with a mathematical model, establishes a three-dimensional mathematical model of the packed tower; constructs a packing unit model; constructs a point fluid model and a line fluid model; integrates the point fluid model and the line fluid model into a packing unit model; constructs a packing wall unit model according to the three-dimensional mathematical model of the packed tower; constructs a vertical fluid model and an offset fluid model; integrates the vertical fluid model and the offset fluid model into a packing wall unit model; analyzes the packed tower according to the packing unit model and the packing wall unit model; and predicts the liquid holdup in the packed tower using the three-dimensional mathematical model of the packed tower, comprising the following steps:

[0032] Please refer to Figure 1 It is a flow chart of a method for predicting liquid holdup in a packed tower provided in an embodiment of the present invention.

[0033] Step S1: replacing the internal structure of the packed tower with a mathematical model to establish a three-dimensional mathematical model of the packed tower;

[0034] Step S1-1, idealize the interior of the packed tower into a structure isolated by mutually perpendicular corrugated plates.

[0035] The corrugated plate filler structure is relatively simple and common, and has higher functional efficiency than the traditional stacking method, so only this case is considered in this embodiment.

[0036] Step S1-2, the corrugated plate is idealized and the thickness is ignored;

[0037] Step S1-3, idealizing the material injected into the packed tower to be injected vertically to the horizontal plane.

[0038] Step S2: constructing a packing unit model according to the three-dimensional mathematical model of the packed tower, wherein the packing unit model is composed of a point fluid model and a line fluid model;

[0039] It should be noted that the point fluid model here is a model that considers the intersection of the repeated units in the middle of the corrugated plate. Similarly, the line fluid model is a model on the oblique side of the repeated units in the middle of the corrugated plate.

[0040] It should be noted that the middle position described in this embodiment is used to distinguish from the boundary position.

[0041] Step S2-1, the point fluid model is a fluid model at the intersection where the material vertically enters the corrugated plate.

[0042] Please refer to Figure 4 A schematic diagram of a point fluid model provided in an embodiment of the present invention.

[0043] It should be noted that here we simply consider that the material enters the corrugated plate vertically, which is an approximate consideration. In fact, due to the repeated structure of the corrugated plate in the packing tower, it can also be treated in this way, which has a smaller impact on the result.

[0044] Step S2-2, after the material flows into the intersection of the corrugated plates, it is divided into three directions, among which the proportion of vertical downward is recorded as r, and the proportion of the eye corrugated plate direction is 0.5 (1-r), forming a vertical flow model;

[0045] Step S2-3, the material flows into the corrugated plate in two directions, where the ratio in the vertical direction is recorded as p, and the ratio in the corrugated plate direction is 1-p, forming a biased fluid model;

[0046] Step S2-4, set the coordinate axes i, j, k to be the parallel direction of the wave plate, the horizontal direction, and the vertical direction to the ground respectively, the intersection of the wave plate is represented by (X, Y, Z), then the material flow rate at the intersection position is (Lx, Ly, Lz), the line fluid model flow rate vertically downward at the intersection position is Lz1, and the point fluid model flow rate is Lz2.

[0047] Step S3: constructing a point fluid model and a line fluid model;

[0048] Please refer to Figure 5 A schematic diagram of a line fluid model provided in an embodiment of the present invention.

[0049] Step S3-1, assuming that the kth wave plate intersection position is represented by the wave plate intersection number in the direction perpendicular to the ground, then for the position k=1, the material flow in the wave plate direction in the point fluid model is , for:

[0050]

[0051] Among them, i is an even number, when i is an odd number, the material flow in the wave direction , Just swap. Indicates the material flow at the current point q;

[0052] It should be noted that the difference between taking odd and even numbers for i here is only in the convenience of origin and counting, and has no effect on a large number of repeating units.

[0053] Step S3-2: Material flow in the vertical direction of the ground in the point fluid model for:

[0054]

[0055] Wherein, i is a positive integer;

[0056] Step S3-2, since the wave plate is a repetitive model, for any position k, it is a cyclic calculation value, and the material flow rate at the position k=2, 3, ... can be calculated;

[0057] Step S3-3, for the lowest position, the material flow rate at the current point q for:

[0058]

[0059] Step S4: integrating the point fluid model and the line fluid model into a packing unit model;

[0060] Step S4-1, take k=k0 position, k0 represents the bottom position, then

[0061]

[0062] Among them, INT means rounding, H means the height of the corrugated plate, and h means the distance between individual units of the corrugated plate;

[0063] Step S4-2, the number of grids n in the vertical section of the corrugated plate is:

[0064]

[0065] Wherein, D represents the vertical section width of the corrugated plate.

[0066] Step S5: constructing a packing wall unit model according to the three-dimensional mathematical model of the packed tower, wherein the packing wall unit model is composed of a vertical fluid model and an offset fluid model.

[0067] It should be noted that the packing wall unit model here is similar to the packing unit model in processing, the difference is that the packing wall unit model is considered as a model under boundary conditions.

[0068] Step S5-1, the vertical flow model is a flow model where the material vertically enters the non-intersection point of the corrugated plate along the edge;

[0069] Please refer to Figure 6 A schematic diagram of a vertical fluid model provided in an embodiment of the present invention.

[0070] Step S5-2, the biased fluid model is a fluid model where the material vertically enters the intersection of the corrugated plates along the edge;

[0071] Step S5-3, for the material flowing through the edge intersection, it is divided into two directions, wherein the proportion of the material flowing vertically along the edge downward is f, and the proportion of the material flowing offset toward the wave plate direction is 1-f;

[0072] Step S5-4, use w(i,-j0-1,k) and w(i,j0+1,k) to represent the material flow on both sides of the corrugated plate respectively.

[0073] Step S6: constructing a vertical fluid model and a biased fluid model;

[0074] Please refer to Figure 7 A schematic diagram of a bias fluid model provided in an embodiment of the present invention.

[0075] Step S6-1, in the vertical fluid model, the flow in the direction of the wave plate for:

[0076]

[0077] The vertical flow w is:

[0078]

[0079] For any vertical position for:

[0080]

[0081] For any vertical position for:

[0082] Step S6-2, the biased fluid model is a vertical fluid model. and exchange.

[0083] It should be noted that the difference between the vertical fluid model and the offset fluid model is small, with a difference of 1 grid in the k direction and no difference in the i and j directions. The calculation method only needs to be and They can be interchanged and will not be described in detail in this embodiment.

[0084] Step S7: integrating the vertical fluid model and the offset fluid model into a packing wall unit model;

[0085] Step S7-1, take the position j=j0 close to the edge, where j0 represents the most edge position:

[0086]

[0087] Wherein, D represents the vertical section width of the corrugated plate, INT represents rounding, and h represents the spacing distance between single units of the corrugated plate.

[0088] Step S8: analyzing the packed tower according to the packing unit model and the packing wall unit model;

[0089] Step S8-1, setting hyperparameter constraints in the packing unit model and the packing wall unit model, that is, 0≤p,r,f≤1;

[0090] Step S8-1, for a given point , and The packing unit model and the packing wall model have the same value, and the packing unit model and the packing wall model are combined into a three-dimensional mathematical model of the packed tower.

[0091] Step S9: using a three-dimensional mathematical model of a packed tower to predict the liquid holdup in the packed tower.

[0092] S9-1, collecting the liquid separation ratio of the pile when it flows down the wave plate unit and the side wall, and obtaining the hyperparameters p, r, and f values ​​of the three-dimensional mathematical model of the packed tower;

[0093] S9-2, using a three-dimensional mathematical model of a packed tower to estimate the liquid holdup, thereby realizing the prediction of the liquid holdup in the packed tower.

[0094] In addition, it should be noted that the present invention can be provided as a method, an apparatus or a computer program product. Therefore, the embodiments of the present invention can take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0095] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0096] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, so that a series of operation steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable terminal device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0097] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0098] Finally, it should be noted that the above is a preferred embodiment of the present invention. It should be pointed out that although the preferred embodiment of the present invention has been described, for those skilled in the art, once the basic creative concept of the present invention is known, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. Therefore, the attached claims are intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the embodiments of the present invention.

Claims

1. A method for predicting liquid holdup in a packed tower, characterized in that: The method comprises the following steps: Step S1: replacing the internal structure of the packed tower with a mathematical model to establish a three-dimensional mathematical model of the packed tower; Step S2: constructing a packing unit model according to the three-dimensional mathematical model of the packed tower, wherein the packing unit model is composed of a point fluid model and a line fluid model; Step S3: constructing a point fluid model and a line fluid model; Step S4: integrating the point fluid model and the line fluid model into a packing unit model; Step S5: constructing a packing wall unit model according to the three-dimensional mathematical model of the packed tower, wherein the packing wall unit model is composed of a vertical fluid model and an offset fluid model; Step S6: constructing a vertical fluid model and a biased fluid model; Step S7: integrating the vertical fluid model and the offset fluid model into a packing wall unit model; Step S8: analyzing the packed tower according to the packing unit model and the packing wall unit model; Step S9: predicting the liquid holdup in the packed tower using a three-dimensional mathematical model of the packed tower; Wherein step S2 also includes the following sub-steps: Step S2-1, the point fluid model is a fluid model at the intersection of the corrugated plates where the material vertically enters; Step S2-2, after the material flows into the intersection of the corrugated plates, it is divided into three directions, among which the proportion of vertical downward is recorded as r, and the proportion of the eye corrugated plate direction is 0.5 (1-r), forming a vertical flow model; Step S2-3, the material flows into the corrugated plate in two directions, where the ratio in the vertical direction is recorded as p, and the ratio in the corrugated plate direction is 1-p, forming a biased fluid model; Step S2-4, set the coordinate axes i, j, k to be the parallel direction of the wave plate, the horizontal direction, and the vertical direction to the ground respectively, the intersection of the wave plate is represented by (X, Y, Z), then the material flow rate at the intersection position is (Lx, Ly, Lz), the flow rate of the line fluid model vertically downward at the intersection position is Lz1, and the flow rate of the point fluid model is Lz2; Wherein step S1 also includes the following sub-steps: Step S1-1, idealizing the interior of the packed tower into a structure isolated by mutually perpendicular corrugated plates; Step S1-2, the corrugated plate is idealized and the thickness is ignored; Step S1-3, idealizing the material injected into the packed tower to be injected vertically to the horizontal plane; Wherein step S3 also includes the following sub-steps: Step S3-1, assuming that the kth wave plate intersection position is represented by the wave plate intersection number in the direction perpendicular to the ground, then for the position k=1, the material flow in the wave plate direction in the point fluid model is , for: ； Among them, i is an even number, when i is an odd number, the material flow in the wave direction , Just swap. Indicates the material flow at the current point q; Step S3-2: Material flow in the vertical direction of the ground in the point fluid model for: ； Wherein, i is a positive integer; Step S3-2, since the wave plate is a repetitive model, for any position k, it is a cyclic calculation value, and the material flow rate at the position k=2, 3, ... can be calculated; Step S3-3, for the lowest position, the material flow rate at the current point q for: ； Wherein step S4 also includes the following sub-steps: Step S4-1, take k=k0 position, k0 represents the bottom position, then ； Among them, INT means rounding, H means the height of the corrugated plate, and h means the distance between individual units of the corrugated plate; Step S4-2, the number of grids n in the vertical section of the corrugated plate is: ； Where D represents the vertical section width of the corrugated plate; Wherein, in step S5, the following sub-steps are also included: Step S5-1, the vertical flow model is a flow model where the material vertically enters the non-intersection point of the corrugated plate along the edge; Step S5-2, the biased fluid model is a fluid model where the material vertically enters the intersection of the corrugated plates along the edge; Step S5-3, for the material flowing through the edge intersection, it is divided into two directions, wherein the proportion of the material flowing vertically along the edge downward is f, and the proportion of the material flowing offset toward the wave plate is 1-f; Step S5-4, using w(i,-j0-1,k) and w(i,j0+1,k) to represent the material flow on both sides of the wave plate respectively; Wherein, in step S6, the following sub-steps are also included: Step S6-1, in the vertical fluid model, the flow in the direction of the wave plate for: ； The vertical flow w is: ； For any vertical position for: ； For any vertical position for: ； Step S6-2, the biased fluid model is a vertical fluid model. and exchange; Wherein, in step S7, the following sub-steps are also included: Step S7-1, take the position j=j0 close to the edge, where j0 represents the most edge position: ； Where D represents the vertical section width of the corrugated plate, INT represents rounding, and h represents the spacing distance between individual units of the corrugated plate; Wherein, in step S8, the following sub-steps are also included: Step S8-1, setting hyperparameter constraints in the packing unit model and the packing wall unit model, that is, 0≤p,r,f≤1; Step S8-1, for a given point , and The packing unit model and the packing wall model have the same value, and the packing unit model and the packing wall model are combined into a three-dimensional mathematical model of the packed tower.

2. The method for predicting liquid holdup in a packed tower according to claim 1, wherein: Wherein, in step S9, the following sub-steps are also included: S9-1, collecting the liquid separation ratio when the pile flows down the wave plate unit and the side wall, and obtaining the hyperparameters p, r, and f values ​​of the three-dimensional mathematical model of the packed tower; S9-2, using a three-dimensional mathematical model of a packed tower to estimate the liquid holdup, to achieve prediction of the liquid holdup in the packed tower.

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