阅读说明：本技术 一种基于数值模拟的uv-paa耦合反应器设计优化方法 (UV-PAA coupling reactor design optimization method based on numerical simulation ) 是由 周雪飞 陈家斌 张亚雷 肖绍赜 于 2020-03-31 设计创作，主要内容包括：本发明公开了一种本发明专利公开了一种基于数值模拟的UV-PAA耦合反应器设计优化方法。本发明通过CFD理论,对反应器内流体流态、紫外光分布与化学反应进行模拟,实现动态计算反应时各物理量随时间的变化情况。可以针对不同结构的反应器与运行工况快速、准确的得出模拟预测结果,对反应器性能进行评估并为UV-PAA耦合反应器提供设计、优化的理论决策依据。本发明不仅可节省反应器设计成本、提高反应器效果,也能作为实际运行期间的实时监控与工况优化手段,是具有发展潜力的设计优化方法。(The invention discloses a design optimization method of a UV-PAA coupling reactor based on numerical simulation. According to the invention, the fluid state, the ultraviolet light distribution and the chemical reaction of the fluid in the reactor are simulated through the CFD theory, so that the change condition of each physical quantity along with time during the dynamic calculation reaction is realized. The simulation prediction result can be rapidly and accurately obtained according to reactors with different structures and operation conditions, the performance of the reactors can be evaluated, and a theoretical decision basis for design and optimization is provided for the UV-PAA coupling reactor. The method can save the design cost of the reactor, improve the effect of the reactor, can be used as a real-time monitoring and working condition optimizing means during actual operation, and is a design optimizing method with development potential.)

1. A design optimization method of a UV-PAA coupling reactor based on numerical simulation is characterized by comprising the following steps:

s1 determining the elementary reaction of the simulation reaction system, the detailed structure and the size information of the reactor, and compiling a corresponding UDF program; the UDF program comprises a calculation method of the concentration of each reaction component, the ultraviolet light intensity at different positions, the ultraviolet lamp tube aging condition and the fluid viscosity in a UV-PAA system;

s2 determining a physical model of the reactor according to the size of the UV/PAA coupling reactor, water inlet and outlet, a dosing port and an ultraviolet lamp tube, and establishing a geometric model by using an Ansys Design Modeler;

s3, importing the geometric model into Ansys Mesh, determining a numerical simulation calculation domain, and performing Mesh division on a geometric body;

s4, guiding the grids into a Fluent, checking the grids again, guiding the grids into a UDF module according to actual conditions, setting calculation model parameters of ultraviolet lamp tube parameters, chemical reaction rate and water inlet and outlet flow rate, and setting boundary conditions, corresponding control equations and solving methods for calculation;

s5, guiding the calculation result into Ansys CFD-Post for Post-processing, analyzing distribution changes of a flow field, ultraviolet intensity, oxidant concentration and pollutant concentration in the actual reaction process through visual observation, and according to the visualization result, pertinently improving the processing performance of the reactor and optimizing reaction conditions by adjusting a medicament adding mode, water inlet and outlet flow, stirring intensity and ultraviolet lamp tube setting parameters.

2. The UV-PAA coupling reactor design optimization method based on numerical simulation of claim 1, characterized in that: in the step S1, determining the substances participating in the reaction process and the involved elementary reactions according to the actual conditions; the method for calculating the concentration of each reaction component comprises the following steps: determining elementary reaction and reaction path according to the reactant, and simplifying the reaction according to the actual condition; carrying out differential equation description on each step of reaction; and solving a differential equation set by adopting a Runge Kutta method.

3. The UV-PAA coupling reactor design optimization method based on numerical simulation of claim 1, characterized in that: assuming that the ultraviolet light source is a set of point light sources, a point source superposition approximation method is adopted, and a specific light intensity distribution formula is as follows

Wherein E is the light intensity at a certain position; oc is an absorption coefficient; p is the effective output power of the ultraviolet lamp tube; l is the length of the ultraviolet lamp tube; d is the distance from the position to the central axis of the ultraviolet lamp tube; h is the height from the position to the center of the ultraviolet lamp tube;

assuming that the ultraviolet light source is a set of annular micro-elements, the light intensity distribution formula obtained by integration is as follows:

wherein E is the light intensity at a certain position; p is the effective output power of the ultraviolet lamp tube; l is the length of the ultraviolet lamp tube; x is the number of₁·x₀Respectively are two vertex coordinates of the ultraviolet lamp tube in the axial direction; theta₀Characteristic included angle, β solution transmittance, d position to violetDistance of the central axis of the outer lamp tube; x is the number of_p·y_p·z_pIs a three-dimensional coordinate of the location.

4. The method of claim 1, wherein the method comprises the following steps: in the step S5, the post-processing includes drawing a cloud map, a contour map, and a vector map of each physical quantity, deriving relevant data, and drawing a line graph of the physical quantity changing with time and space.

Technical Field

The invention relates to the field of sewage treatment, and particularly belongs to a design optimization method of a UV-PAA coupling reactor based on numerical simulation.

Background

With the vigorous development of the industry and the continuous improvement of the living standard in China, the discharge amount of pollutants such as medicines, personal care products, chemical by-products and the like is increased sharply, the types and the treatment difficulty of components in the wastewater are increased continuously, and great harm is brought to the water environment safety. Government has been increasing the discharge and drinking water standard, but the physicochemical method to the concentration is high, the salinity is high, toxicity is high, biochemical poor difficult to handle waste water treatment effect is poor, and traditional oxidation technologies such as chlorine, ozone, etc. have the purification thoroughly, the by-product harm is big, can't meet the advanced treatment requirement. The novel oxidant such as PAA (peroxyacetic acid) has better performance and higher safety, and has great potential in advanced treatment. The oxidation system of PAA under UV (ultraviolet) activation is very suitable for high-concentration and poor-biodegradability wastewater such as personal care product production wastewater, pharmaceutical wastewater, chemical wastewater and the like which are difficult to treat, and PPCPs-containing wastewater such as municipal wastewater, livestock wastewater and the like which is deeply treated, and the method has the characteristics of spectral property, convenient operation, mild reaction conditions and the like. The removal of pollutants is realized by generating high-activity free radicals in the reaction process, and reacting the free radicals with organic matters in water.

The UV-PAA coupling reactor relates to a complex system of physical and chemical reactions, and is usually designed and working condition optimized by adopting an experimental means, the method has long experimental period and high cost, cannot acquire information such as real-time fluid flow state, ultraviolet intensity distribution, pollutant degradation, medicament consumption and the like in the reactor, and is difficult to provide powerful support for the design optimization of the reactor.

Disclosure of Invention

The technical problem to be solved by the invention is that the existing UV-PAA coupling reactor is designed by adopting an experimental means and optimized in working condition, so that the experimental period is long, the cost is high, and real-time information in the reactor cannot be acquired.

In order to solve the technical problems, the invention adopts the technical scheme that: a design optimization method of a UV-PAA coupling reactor based on numerical simulation comprises the following steps:

s1 determining the elementary reaction of the simulation reaction system, the detailed structure and the size information of the reactor, and compiling a corresponding UDF program; the UDF program comprises a calculation method of the concentration of each reaction component, the ultraviolet light intensity at different positions, the ultraviolet lamp tube aging condition and the fluid viscosity in a UV-PAA system;

s2 determining a physical model of the reactor according to the size of the UV/PAA coupling reactor, water inlet and outlet, a dosing port and an ultraviolet lamp tube, and establishing a geometric model by using an Ansys Design Modeler;

s3, importing the geometric model into Ansys Mesh, determining a numerical simulation calculation domain, and performing Mesh division on a geometric body;

s4, guiding the grids into a Fluent, checking the grids again, guiding the grids into a UDF module according to actual conditions, setting calculation model parameters of ultraviolet lamp tube parameters, chemical reaction rate and water inlet and outlet flow rate, and setting boundary conditions, corresponding control equations and solving methods for calculation;

s5, guiding the calculation result into Ansys CFD-Post for Post-processing, analyzing distribution changes of a flow field, ultraviolet intensity, oxidant concentration and pollutant concentration in the actual reaction process through visual observation, and according to the visualization result, pertinently improving the processing performance of the reactor and optimizing reaction conditions by adjusting a medicament adding mode, water inlet and outlet flow, stirring intensity and ultraviolet lamp tube setting parameters.

Further, in the step S1, according to the actual situation, the substances participating in the reaction process and the involved elementary reactions are determined; the method for calculating the concentration of each reaction component comprises the following steps: determining elementary reaction and reaction path according to the reactant, and simplifying the reaction according to the actual condition; carrying out differential equation description on each step of reaction; and solving a differential equation set by adopting a Runge Kutta method.

Further, assuming that the ultraviolet light source is a set of point light sources, a point source superposition approximation method is adopted, and a specific light intensity distribution formula is as follows

Wherein E is the light intensity at a certain position; oc is an absorption coefficient; p is the effective output power of the ultraviolet lamp tube; l is the length of the ultraviolet lamp tube; d is the distance from the position to the central axis of the ultraviolet lamp tube; h is the height from the position to the center of the ultraviolet lamp tube;

assuming that the ultraviolet light source is a set of annular micro-elements, the light intensity distribution formula obtained by integration is as follows:

wherein E is the light intensity at a certain position; p is the effective output power of the ultraviolet lamp tube; l is the length of the ultraviolet lamp tube; x is the number of₁、x₀Respectively are two vertex coordinates of the ultraviolet lamp tube in the axial direction; theta₀Characteristic included angle, β solution light transmittance, d distance from the central axis of the ultraviolet lamp tube, and x_p·y_p·z_pIs a three-dimensional coordinate of the location.

Further, in step S5, the post-processing includes drawing a cloud map, a contour map, and a vector map of each physical quantity, deriving relevant data, and drawing a line graph of the physical quantity changing with time and space.

The technical scheme shows that the invention has the following advantages: the simulation prediction result can be rapidly and accurately obtained according to reactors with different structures and operation conditions, the performance of the reactors can be evaluated, and a theoretical decision basis for design and optimization is provided for the UV-PAA coupling reactor. The invention not only can save the design cost of the reactor and improve the effect of the reactor, but also can be used as a real-time monitoring and working condition optimizing means during the actual operation.

Drawings

FIG. 1 is a flow chart of design optimization of the present invention;

FIG. 2 is a diagram of a UV-PAA coupling reactor;

FIG. 3 is a schematic diagram of UV-PAA coupling reactor meshing;

FIG. 4 is a vector diagram of the internal velocity of a UV-PAA coupling reactor;

FIG. 5 is a cloud chart of inlet and outlet velocities of a UV-PAA coupling reactor;

FIG. 6 is a UV-PAA coupling reactor internal UV intensity cloud;

FIG. 7 is a cloud of contaminant concentrations inside a UV-PAA coupled reactor;

fig. 8 is a graph of the disinfection effect at different rotation speeds.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

The present invention is further described with reference to the following embodiments, which are only some application scenarios, but not all application scenarios, and other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention based on the embodiments of the present invention.

Example one

Aiming at high-concentration organic breeding wastewater discharged by a certain livestock and poultry factory, a certain UV-PAA coupling reactor is selected to carry out advanced treatment on effluent of a sedimentation tank after secondary treatment, the reactor is a barrel-shaped continuous flow complete mixing reactor, an ultraviolet lamp tube is arranged on the central axis of a cylinder, a stirrer is arranged near the bottom end, the hydraulic retention time is 10 minutes, the number of water-inlet escherichia coli is 10⁷CFU/L. The method for designing and optimizing the UV-PAA coupling reactor based on numerical simulation is developed by the patent, the running condition of the reactor is simulated and evaluated, and the rotating speed of a stirrer is selected.

The method comprises the following steps:

s1 determining the elementary reaction of the simulation reaction system, the detailed structure and the size information of the reactor, and compiling a corresponding UDF program;

measuring the quality of inlet water, taking COD as an index of pollutants, and compiling a UDF program of ultraviolet ray source attenuation and COD degradation kinetics.

The concentration change in the reaction process of COD and PAA is simplified as follows:

wherein, C_COD，C_PAACOD and PAA concentrations, respectively; t is the reaction time; k is a reaction rate constant.

S2 determining a physical model of the reactor according to the size of the UV/PAA coupling reactor and the combination of structures such as water inlet and outlet, a dosing port and an ultraviolet lamp tube, and establishing a geometric model by using an Ansys Design Modeler;

s3 introduces the geometric model into Ansys Mesh, determines a numerical simulation calculation domain, and performs Mesh division on the geometric object according to the actual situation and in consideration of the number and quality of meshes, where the total number of meshes is 370964 in this embodiment.

S4, guiding the grid into Fluent, rechecking the grid, guiding the ultraviolet column source attenuation and COD degradation kinetics UDF program, setting a water inlet as a speed inlet and a water outlet as a pressure outlet, setting COD and PAA concentrations, and calculating by adopting a standard k-model.

In this embodiment, the ultraviolet light source is a collection of point light sources, a point-source superposition approximation method is adopted, and a specific light intensity distribution formula is as follows

Wherein E is the light intensity at a certain position; oc is an absorption coefficient; p is the effective output power of the ultraviolet lamp tube; l is the length of the ultraviolet lamp tube; d is the distance from the position to the central axis of the ultraviolet lamp tube; h is the height from the position to the center of the ultraviolet lamp tube;

if the ultraviolet light source is a set of annular micro-elements, the light intensity distribution formula obtained by integration is as follows:

wherein E is the light intensity at a certain position; p is the effective output power of the ultraviolet lamp tube; l is ultraviolet lamp tubeA length; x is the number of₁、x₀Respectively are two vertex coordinates of the ultraviolet lamp tube in the axial direction; theta₀Characteristic included angle, β solution light transmittance, d distance from the central axis of the ultraviolet lamp tube, and x_p、y_p、z_pIs a three-dimensional coordinate of the location.

S5, guiding the calculation result into Ansys CFD-Post for Post-processing, and analyzing the distribution changes of the flow field, the ultraviolet intensity, the oxidant concentration and the pollutant concentration in the actual reaction process through visual observation, as shown in figures 2 to 7. The result model can accurately predict the fluid state, the ultraviolet light intensity, the distribution condition of pollutants and oxidants at different positions in the reactor, and finally comprehensively measure the COD removal rate and the energy consumption in the effluent water as shown in figure 8, wherein the rotating speed of the stirrer is selected to be 80rpm, and the removal rate can reach 99.999%.