CN-122021467-A - Fluid simulation method for optimizing performance of demister unit of desulfurizing tower

CN122021467ACN 122021467 ACN122021467 ACN 122021467ACN-122021467-A

Abstract

The invention discloses a fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower, which comprises the steps of S1, establishing a three-dimensional solid model before optimization, S2, extracting grid-connected grid division of a fluid domain, establishing a finite element model, S3, setting a turbulence model, boundary conditions and a solving algorithm, S4, carrying out steady-state iterative computation, analyzing flow fields, speeds, pressure distribution and pressure drop rules to obtain a performance evaluation result, S5, optimizing a structure according to the evaluation result, determining structural parameters and establishing an optimized three-dimensional solid model, S6, repeating the steps S2 to S4 for simulation on the optimized model, comparing the results before and after optimization, and determining the optimized operation parameters and the unit structure. The invention can accurately evaluate the performance of the demister, guide and verify the design of the novel spline curve blade structure, and realize the whole process optimization from problem diagnosis to scheme verification.

Inventors

Mi Dabin
WANG JIANFENG
GUO JIANGLONG
MI CUILI
MOU FAHAI
CHEN ZIYANG
Mi Weiting
ZHAO YUEJING
QIN ZHIYING

Assignees

河北建投能源科学技术研究院有限公司
河北建投能源投资股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (8)

1. A fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower is characterized by comprising the following steps: s1, establishing a three-dimensional solid model according to geometric parameters of internal blades of a demister unit before optimization and the size of an external cylinder; s2, extracting a fluid domain, naming and meshing the three-dimensional entity model, and establishing a finite element model of the demister unit; S3, setting turbulence models and boundary conditions of the finite element models and gas media and solving algorithms in the demister units in fluid simulation software, and setting simulation parameters; s4, setting operation condition parameters to perform steady-state iterative computation, and analyzing flow field distribution, speed distribution, pressure distribution and pressure drop rules of the demister units under different working conditions before optimization to obtain demisting performance evaluation results; S5, optimizing the demister unit structure according to the demisting performance evaluation result in the step S4, determining optimized structural parameters, and establishing an optimized three-dimensional entity model based on the structural parameters; The optimized structural parameters are a novel spline curve blade structure, the blade of the novel spline curve blade structure is composed of two three-dimensional spline curves, each spline curve is composed of two tangent sub-curves, a smooth continuous three-dimensional spiral curved surface is formed through lofting, and the solid spiral blade is thickened; S6, repeating the steps S2 to S4 for flow field simulation on the optimized three-dimensional solid model, comparing simulation results before and after optimization, and determining optimized operation condition parameters and unit structures.
2. The fluid simulation method for optimizing the performance of the demister unit of the desulfurizing tower according to claim 1, wherein in the step S2, SPACECLAIM software is adopted for extracting the fluid domain, and the method specifically comprises the steps of conducting geometric repair after a three-dimensional solid model is imported, automatically repairing gaps, overlapped surfaces or damaged boundaries, selecting an extraction option under the function of preparing the fluid volume, clicking an internal hollow area to generate the internal fluid volume, and naming the fluid domain, wherein the fluid domain comprises an inlet, an outlet, a blade wall surface and a shell wall surface area.
3. The fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower according to claim 1, wherein in the step S2, a ANSYS MESHING module is adopted for grid division, the minimum size is 2mm, the maximum size is 30mm, the growth rate is 1.2, partial encryption is carried out on grids of a blade edge, a near-wall area and a transition area according to the characteristics of a blade channel, and meanwhile, multiple layers of expansion layer grids are arranged on the wall surface of a shell to ensure the resolution of a boundary layer.
4. The fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower according to claim 1, wherein in the step S3, a k-omega SST model is selected as a turbulence model to capture strong rotating flow and secondary flow structures guided by spiral blades, boundary conditions are set as an inlet is a speed inlet, an outlet is a pressure outlet and takes zero gauge pressure, slip-free boundary conditions are adopted for the blades and the wall surface of a shell, a fluid medium is sulfo-dioxide, an ideal gas model is adopted to define density, and dynamic viscosity is set by adopting an empirical value.
5. The fluid simulation method for optimizing the performance of the demister unit of the desulfurizing tower according to claim 1, wherein in the step S4, flow field distribution, pressure distribution and speed distribution data are extracted through a post-processing function of fluid simulation software, a rotating flow structure formed in a channel is analyzed, a change rule of a high-speed area and a backflow area is observed, a trend of flow guiding strength along with inlet speed improvement is judged, influences of structural parameters on fluid resistance are evaluated by comparing change characteristics of total pressure drop under different working conditions, and a lifting rule of demisting efficiency is predicted by calculating centrifugal force field strength and liquid drop deviation trend of a blade channel.
6. The fluid simulation method for optimizing the performance of a desulfurizing tower demister unit according to claim 1, wherein two three-dimensional spline curves in the spline curve blade structure are cubic B spline curves, and are constructed by restraining tangential directions of a starting point, a finishing point, a connecting point and an end part, and adjacent sub-curves are smoothly and tangentially transited at the connecting point in the following concrete construction modes: The first sample strip curve is arranged in the middle of the outer wall of the central cylinder, the initial point coordinate of a first section of the sub-curve is (X 0 ,Y 0 ,Z 0 ), the tangential azimuth angle is 90 degrees, the pitch angle is 5 degrees, the end point coordinate of a second section of the sub-curve is (X 0 ,Y 0 +200,Z 0 -40), the tangential azimuth angle is 90 degrees, the pitch angle is-5 degrees, and the two sections of the sub-curves are tangential at the connecting point of (X 0 ,Y 0 +116,Z 0 -20); The second sample strip curve is arranged according to the end position of the first sample strip curve, the initial point coordinate of the first section of the sub-curve is (X 0 -130,Y 0 ,Z 0 +60), the tangential azimuth angle is-90 degrees, the pitch angle is 5 degrees, the end point coordinate of the second section of the sub-curve is (X 0 -130,Y 0 +200,Z 0 -100), the tangential azimuth angle is-90 degrees, the pitch angle is-5 degrees, and the two sections of the sub-curves are tangential at the connecting point of (X 0 -130,Y 0 +100,Z 0 -23.5).
7. The fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower according to claim 1, wherein in the step S5, the process of establishing the optimized three-dimensional solid model further comprises: constructing a central column of the leaf fan, and using an array command to perform equidistant expansion of spiral blades around the constructed central column to form a complete demister leaf fan; And constructing a demister sleeve, adopting two-stage leaf fan arrangement, arranging a first-stage leaf fan at an inlet position, and arranging a second-stage leaf fan at an outlet position to form an optimized three-dimensional solid model.
8. The fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower according to claim 1, wherein in the step S6, simulation results before and after optimization are compared, and the influence of the spiral form of the blades, the pitch of the blades and the length of the shell on the fluid resistance is evaluated by analyzing the change rule of a rotating flow structure, a high-speed area and a backflow area formed in a spiral blade channel and the change characteristics of total pressure drop under different working conditions, so that the optimized operation working condition parameters and the unit structure are finally determined.

Description

Fluid simulation method for optimizing performance of demister unit of desulfurizing tower Technical Field The invention relates to the technical field of optimization of industrial gas-liquid separation devices, in particular to a fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower. Background In industrial scenes such as wet desulfurization towers (WFGD) of thermal power plants, large-scale ventilation and dehumidification systems, sea water desalination devices, chemical absorption towers and the like, a large amount of liquid drops are often entrained in the flowing process of wet saturated gas, and if the liquid drops can not be removed in time, the operation of equipment can be obviously influenced. The gas-liquid separation is a key process in industrial equipment such as a thermal power plant, a chemical tower, a wet desulfurization system and the like, and a demister which is common in the current engineering application comprises a wire mesh demister, a baffle plate demister and a vane type demister, wherein the vane type demister has the advantages of small pressure drop, convenience in maintenance, modularity in structure and the like, and is most widely applied to equipment such as wet desulfurization, steam dehumidification, air cooling islands and the like. The existing research is concentrated on the local optimization of the traditional baffling structure, and the research on the three-dimensional vortex enhanced structure is insufficient. Along with the increase of industrial equipment scale and the improvement of desulfurization efficiency requirement, current defroster structure exposes following problem gradually: (1) The demisting efficiency is limited, the flow passage of the straight plate type blade before optimization is a two-dimensional curve, the rotation capacity of the airflow in the flow passage is weak, the trapping efficiency of small-particle-size liquid drops (20-50 mu m) is insufficient, and secondary water carrying is easy to cause. (2) The flow resistance is large, the energy consumption is high, the existing baffling structure depends on a plurality of sharp turns to realize the liquid drop separation, the pressure drop can be increased, and the overall operation energy consumption of the system is influenced. (3) The liquid drop re-entrainment phenomenon is obvious, namely, the liquid film on the surface of the blade is easily stripped to form re-atomized liquid drops under the action of a high-speed main flow, so that the content of water mist at an outlet is increased, and the strict discharge standard cannot be met. (4) The method for effectively simulating the spiral three-dimensional flow field is lacking, and the demister before optimization is often analyzed based on a two-dimensional or quasi-three-dimensional model and is not suitable for a complex three-dimensional spiral curved surface flow channel. With the development of gas-liquid separation technology to high efficiency, low resistance and compactness, the construction of novel demister structures has become a research hotspot. The airflow generates stable spiral rotation in the flow channel, and a higher radial centrifugal force is formed, so that the migration of liquid drops to the wall surfaces of the blades is enhanced. However, the three-dimensional complexity of the flow field increases the experimental analysis difficulty, so that a set of high-precision fluid simulation method for the desulfurizing tower demister is developed, is used for simulating the change rules of flow field distribution, speed and pressure, and has important significance. At present, a system simulation method aiming at flow field characteristic expression is not available. Therefore, a complete simulation flow which can be used for structural optimization, performance prediction and engineering application is needed, and technical support is provided for structural optimization and research and development of the desulfurizing tower demister. Disclosure of Invention The invention aims to solve the technical problem of providing a fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower, which not only can accurately evaluate the performance of the demister, but also can directly guide and verify the design of a novel spline curve blade structure with high efficiency and low resistance, thereby realizing the whole process optimization from problem diagnosis to scheme generation and verification. In order to solve the technical problems, the technical scheme adopted by the invention is as follows. A fluid simulation method for optimizing the performance of a demister unit of a desulfurizing tower comprises the following steps: s1, establishing a three-dimensional solid model according to geometric parameters of internal blades of a demister unit before optimization and the size of an external cylinder; s2, extracting a fluid domain, n