Tower type VOCs catalytic ozonation reactor and flow field simulation method thereof

Abstract

The invention discloses a tower-type VOCs catalytic ozonization reactor and a flow field simulation method thereof, the reactor adopts a tower-type structural design, the reactor comprises: a catalytic reactor gas channel cylinder, the bottom end of which is provided with a VOCs gas inlet, the top end of which is provided with a purified gas discharge outlet, and the inlet and the outlet both adopt a conical gas channel design; the flow guide plate is arranged at the VOCs gas inlet, a parallel flow guide plate is arranged close to the inlet, and a corner flow guide plate is arranged far away from the inlet; the flow equalizing plate is arranged at the VOCs gas inlet so as to ensure that a flow field is uniformly distributed before gas in the hearth enters the catalyst bed layer; and the catalyst bed layer is a movable grating plate and is arranged on the cross section plane of the catalytic reactor air channel cylinder, so that ozone and VOCs are subjected to a synergistic catalytic reaction on the surface of a catalyst. According to the invention, the divergence of gas can be improved, the uniformity of gas flow in the cavity is improved, and the removal efficiency of VOCs is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of equipment design simulation optimization, and in particular relates to a tower type VOCs catalytic ozonation reactor and a flow field simulation method thereof. Background Art

[0002] Volatile organic compounds (VOCs) are one of the main sources of air pollution and have a significant impact on the environment and human health. Traditional treatment methods such as adsorption, combustion and biological treatment have problems such as high energy consumption, secondary pollution or low treatment efficiency. Catalytic ozonation technology has become a research hotspot in the field of VOCs treatment due to its high efficiency, low energy consumption and ability to treat a variety of pollutants. This technology reacts ozone with VOCs under the action of a catalyst to produce harmless products such as carbon dioxide and water. Tower catalytic ozonation equipment is widely used in industrial VOCs treatment due to its compact structure, large reaction contact area and long residence time.

[0003] However, the fluid distribution in the furnace is crucial to the efficiency of the mixed reaction of ozone and VOCs. Uneven fluid distribution may lead to incomplete reaction, catalyst failure, and excessively high local temperature in the reactor, thus affecting the treatment effect and equipment life. Traditional reactor designs are mostly based on experience and simplified theoretical models, lacking in-depth analysis and optimization of the internal flow field. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a tower VOCs catalytic ozonation reactor and a flow field simulation method thereof to solve the above problems existing in the prior art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a tower-type VOCs catalytic ozonation reactor, wherein the reactor adopts a tower-type structure design and comprises:

[0006] The catalytic reactor airway cylinder has a VOCs gas inlet at the bottom and a purified gas discharge outlet at the top, and both the inlet and the outlet are designed in a conical airway;

[0007] A guide plate is arranged at the VOCs gas inlet, with a parallel guide plate arranged near the inlet and a corner guide plate arranged far from the inlet to guide the change of the airflow direction;

[0008] A flow equalizing plate is arranged at the VOCs gas inlet to ensure that the gas in the furnace of the catalytic ozonation reactor is evenly distributed before entering the catalyst bed;

[0009] The catalyst bed is a movable grid plate placed on the cross-sectional plane of the gas channel of the catalytic reactor.

[0010] Preferably, the fluid dead zone of the furnace of the catalytic ozone oxidation reactor adopts a sloped or arc-shaped structure design.

[0011] Preferably, the conical airway adopts a quadrangular pyramid or conical structure design.

[0012] Preferably, the corner guide plates include obtuse-angle guide plates, right-angle guide plates, and arc-shaped guide plates.

[0013] Preferably, the catalyst bed is divided into two layers and is supported by a porous grid, wherein the hole diameter of the porous grid is 5-15 mm.

[0014] In a second aspect, the present invention further provides a flow field simulation method for a tower VOCs catalytic ozonation reactor. Based on the tower VOCs catalytic ozonation reactor described in any one of the first aspects, the flow field simulation method comprises the following steps:

[0015] Based on the three-dimensional structure of the catalytic ozonation reactor, a flow field model was established;

[0016] Extracting the internal fluid region of the flow field model, limiting the boundary conditions of the fluid region and determining the fluid calculation domain by setting boundary parameters;

[0017] Based on the fluid computational domain, determining the minimum computational unit of the fluid computational domain by unit grid division;

[0018] Based on the fluid calculation domain and its minimum calculation unit, a turbulence model of the airflow is established;

[0019] Based on the turbulence model, the initial inlet velocity of the gas is selected by the diameter of the boundary inlet;

[0020] Based on different inlet velocities, the flow field distribution diagram of the catalytic ozonation reactor is simulated, and its internal airflow distribution is determined.

[0021] Preferably, the meshing tool is Fluent meshing or ICEM, wherein the mesh type of the fluid calculation domain is a regular tetrahedral mesh or a regular hexahedral mesh.

[0022] Preferably, the turbulence model comprises:

[0023] The energy equation is:

[0024]

[0025] Where ρ is the fluid density, t is the time, u is the viscosity coefficient, p is the pressure, T is the temperature, x is the Cartesian coordinate, λ is the thermal conductivity, w is the vorticity, h is the specific enthalpy, and q is the heat source term;

[0026] The momentum equation is:

[0027]

[0028] Where ρ is the fluid density, t is the time, u is the viscosity coefficient, p is the pressure, F is the volume force term, and x is the Cartesian coordinate.

[0029] Preferably, the initial inlet velocity is 8.373 m / s, 12.559 m / s, or 16.746 m / s.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] The present invention provides a tower VOCs catalytic ozonation reactor, which adopts a tower structure design and comprises: a catalytic reactor airway cylinder, a VOCs gas inlet is arranged at the bottom end, and a purified gas discharge outlet is arranged at the top end, and the inlet and the outlet both adopt a conical airway design; a guide plate is arranged at the VOCs gas inlet, a parallel guide plate is arranged near the inlet, and a vertical guide plate is arranged away from the inlet; a flow equalizing plate is arranged at the VOCs gas inlet to ensure that the gas in the furnace is evenly distributed before entering the catalyst bed; the catalyst bed is a movable grid plate, which is arranged on the cross-sectional plane of the catalytic reactor airway cylinder, so that ozone and VOCs can perform a synergistic catalytic reaction on the catalyst surface.

[0032] The present invention rationally optimizes the internal flow guidance and gas distribution structure of the tower VOCs catalytic ozonation reactor, which can effectively improve the divergence of the gas and the uniformity of the airflow in the cavity. The movable grid adopts a multi-pore design to ensure uniform contact between VOCs and the catalyst surface, thereby improving the VOCs removal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0034] Figure 1 It is a schematic plan view of a tower type VOCs catalytic ozonation device according to an embodiment of the present invention;

[0035] Figure 2 It is a velocity distribution cloud diagram of a tower type VOCs catalytic ozonation device according to an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the model structure of a tower-type VOCs catalytic ozonation device (including a guide plate and a flow equalizing plate) according to an embodiment of the present invention;

[0037] Figure 4 It is a velocity distribution cloud diagram of a tower type VOCs catalytic ozonation device (including guide plates) according to an embodiment of the present invention;

[0038] Figure 5 It is a schematic diagram of fluid particle size simulation of a tower-type VOCs catalytic ozonation device (including a guide plate) according to an embodiment of the present invention;

[0039] In the above figure: 1. Boundary inlet; 2. Flow equalizing plate; 3. Guide plate; 4. Catalyst bed (movable grid plate); 5. Boundary outlet. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0042] First, the technical terms involved in the following embodiments are explained.

[0043] A catalytic ozone reactor is a device that uses a catalyst to catalyze ozone oxidation reactions, and is mainly used to treat organic compound pollutants in water sources or air. Its working principle is to increase the reactivity of ozone through a catalyst, so that ozone can more effectively degrade volatile organic compounds (VOCs) or oxidize nitrogen oxides (NOx), and ultimately convert pollutants into carbon dioxide and water or other decomposable substances.

[0044] Catalytic ozone reactors are usually composed of ozone generators, catalyst reactors, circulation pumps and control systems. The ozone generator produces ozone, the catalyst reactor adds a catalyst to enhance the oxidation capacity of ozone, the circulation pump ensures that ozone is fully in contact with pollutants, and the control system is responsible for the automation of the entire process.

[0045] The working principle of catalytic ozone reactor is to use catalysts to break down ozone molecules into highly active oxygen ions, which can oxidize pollutants more effectively. Catalysts are usually compounds made of metal elements such as titanium, iron, copper, chromium, and cobalt. They play a key role in the reaction and can be recycled1.

[0046] Catalytic ozone reactors are widely used in industrial waste gas treatment, food manufacturing, printing plants, paint production and other industries. They can effectively treat a variety of pollutants, including VOCs, NOx, benzene, phenol, formaldehyde, ethanol, etc.1. In addition, it also has a significant effect in sewage treatment, and can efficiently treat high-difficulty wastewater such as printing and dyeing wastewater, garbage leachate and coal chemical wastewater.

[0047] advantage:

[0048] High efficiency: The reaction rate of catalytic ozone reactors is much higher than other similar technologies, which can effectively reduce pollutant concentrations.

[0049] Safe and environmentally friendly: The main products produced during the treatment process are carbon dioxide and water, which is environmentally friendly.

[0050] Wide range of applications: Able to handle a variety of pollutants1.

[0051] shortcoming:

[0052] High maintenance costs: Catalysts and seals need to be replaced frequently, and equipment and energy costs are high.

[0053] Complex operation: Need to ensure that there are no impurities in the reactor to prevent catalyst damage or ozone leakage1.

[0054] In conclusion, the catalytic ozone reactor is an efficient and environmentally friendly pollutant treatment technology. Despite some maintenance and operational challenges, its broad application prospects and technical advantages make it occupy an important position in the industrial and environmental protection fields.

[0055] This embodiment provides a tower-type VOCs catalytic ozonation reactor, which adopts a tower structure design, and the gas flows from bottom to top, including:

[0056] The catalytic reactor airway cylinder has a VOCs gas inlet at the bottom and a purified gas discharge outlet at the top, and both the inlet and the outlet are designed in a conical airway;

[0057] A guide plate is arranged at the VOCs gas inlet, a parallel guide plate is arranged near the inlet, and a corner guide plate is arranged far from the inlet;

[0058] A flow equalizing plate is arranged at the VOCs gas inlet to ensure that the gas in the furnace is evenly distributed before entering the catalyst bed;

[0059] The catalyst bed is a movable grid plate, which is arranged in the airway cylinder of the catalytic reactor, so that ozone and VOCs can undergo a synergistic catalytic reaction on the catalyst surface, thereby achieving efficient VOCs degradation at room temperature.

[0060] As an additional implementation method, the dead zone of the fluid in the furnace of the catalytic ozonation reactor is designed with a slope or arc shape to minimize the existence of the dead zone of the fluid inside the cavity. This design solves the problem that the traditional equipment cannot judge the uniformity of the reactor gas flow distribution and the reaction efficiency during the actual design and manufacturing process, and provides an efficient and economical solution for the treatment of industrial waste gas.

[0061] Furthermore, the conical airway adopts a quadrangular pyramid and a conical structure design.

[0062] Furthermore, the corner guide plates include obtuse-angle guide plates, right-angle guide plates, and arc-shaped guide plates.

[0063] Furthermore, the catalyst bed is divided into two layers and adopts a porous grid support design, and the hole diameter of the porous grid is 5-15mm.

[0064] This embodiment discloses a flow field simulation method for a tower-type VOCs catalytic ozonation reactor. Based on the tower-type VOCs catalytic ozonation reactor, the flow field simulation method includes the following steps:

[0065] S1. Establish a flow field model based on the three-dimensional structure of the catalytic ozonation reactor;

[0066] S2, extracting the internal fluid region of the flow field model, limiting the boundary conditions of the fluid region and determining the fluid calculation domain by setting boundary parameters;

[0067] S3, based on the fluid calculation domain, determining the minimum calculation unit of the fluid calculation domain by unit grid division;

[0068] S4. Establishing a turbulence model of the airflow based on the fluid calculation domain and its minimum calculation unit;

[0069] Specifically, the energy equation in the turbulence model is:

[0070]

[0071] Where ρ is the fluid density, t is the time, u is the viscosity coefficient, p is the pressure, T is the temperature, x is the Cartesian coordinate, λ is the thermal conductivity, w is the vorticity, h is the specific enthalpy, and q is the heat source term;

[0072] The momentum equation is:

[0073]

[0074] Where ρ is the fluid density, t is the time, u is the viscosity coefficient, p is the pressure, F is the volume force term, and x is the Cartesian coordinate.

[0075] S5. Based on the turbulence model, select the initial inlet velocity of the gas by the diameter of the boundary inlet;

[0076] S6. Based on different inlet velocities, the flow field distribution diagram of the catalytic ozone oxidation reactor is simulated, and the internal airflow distribution is determined so as to make a reactor structure adjustment plan according to the optimization result.

[0077] In this embodiment, the internal airflow distribution of the catalytic ozonation reactor is simulated by CFD simulation to perform flow field simulation and visualize the results to ensure uniform distribution of the airflow and maximize the reaction efficiency.

[0078] Furthermore, the process of determining the fluid calculation domain through mesh division is as follows:

[0079] The fluid calculation domain of the flow field model is transferred to Fluent meshing for meshing, and the minimum calculation unit of the fluid calculation domain is determined; wherein the mesh type of the fluid calculation domain body is selected as tetrahedron mesh or regular hexahedron.

[0080] Specifically, this embodiment may also use the ICEM meshing tool.

[0081] Furthermore, the initial inlet velocity is 8.373 m / s, 12.559 m / s, and 16.746 m / s.

[0082] Simulation experiment 1:

[0083] The inlet and outlet of the tower VOCs catalytic ozonation reactor are designed with a conical diffusion structure, in which the hole diameter of the active grid plate of the catalyst bed is 10mm, and the length and width are 300mm respectively. Figure 1 As shown, the entire model is extracted through Design Modeler for fluid calculation domain, and the calculation domain boundary inlet (inlet) and outlet (output) are set, and they are respectively defined as velocity inlet and pressure outlet. The geometric pre-processing model is transferred to Fluent Meshing for meshing, and the volume mesh type is selected as tetrahedral mesh; then the divided mesh model is imported into the solver (solution), the energy equation is turned on, and the gas viscosity model k-epsilon is selected; then air is selected as the fluid material, and its density is 1.225kg / m 3 , specific heat is 1006.43 J / (kg·K), thermal conductivity is 0.0242 W / (m·K), viscosity is 1.7894×10-5 kg / (m·s) to set boundary conditions, select the inlet condition velocity inlet (inlet), its velocity is 8.373 m / s, temperature is 300 K, outlet condition is pressure outlet (outlet), its temperature is 300 K; select mixed initialization to perform the initial instructions of the region boundary, the computer defaults to 20 iterations, until the scalar variable order of magnitude becomes 10 -8 Left and right cutoff; calculation parameter setting, the number of iterations is 500 steps, and the residual is set to 10 -6 , calculate until convergence.

[0084] After the calculation is completed, open the calculation cloud map (contours) and CFD post-processing tools, and analyze the results by cutting the cross section (plane) of the device and visualizing the overall equipment area. Figure 2 As shown, the calculation result cloud map shows that the airflow hits the catalytic furnace wall at the initial velocity from the inlet to form an "impact jet" phenomenon, and generates vortices in the cavity to form an obvious fluid dead zone.

[0085] Simulation experiment 2:

[0086] For the simulation experiment 1, the interior of the reactor was further optimized. A catalyst bed (movable grid plate) 4 with a pore size of 10 mm was designed at the reactor inlet, and the pore density was 64 / dm 2 , parallel, obtuse, right-angled, and arc-shaped guide plates are arranged inside the reaction chamber. The tower VOCs catalytic ozonation device (including guide plates and equalizing plates) model includes a boundary inlet 1, an equalizing plate 2, a guide plate 3, a catalyst bed (active grid plate) 4, and a boundary outlet 5, wherein the catalyst bed is composed of two layers of perforated grids, such as Figure 3 As shown. The whole model is extracted by Design Modeler for fluid calculation domain, and the calculation domain boundary inlet (inlet) and outlet (output) are set, and they are respectively defined as pressure inlet and velocity outlet. Fluent calculation simulation method is the same as simulation experiment 1.

[0087] After the calculation is completed, open the calculation cloud map (contours) and CFD post-processing tools, and analyze the results by cutting the cross section (plane) of the device and visualizing the overall equipment area. Figure 4 As shown in the calculation result cloud diagram, the airflow fully diffuses the inlet fluid through the flow equalizer and the guide plate, and evenly disperses the airflow to flow through the catalyst in three paths, such as Figure 5 As shown in the figure, through the CFD post equipment internal field trace analysis diagram, it can be seen that there are fewer vortices in the device internal field, indicating that the equipment has no obvious dead zone.

[0088] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A tower type VOCs catalytic ozonation reactor, characterized in that: The reactor adopts a tower structure design, comprising: The catalytic reactor airway cylinder has a VOCs gas inlet at the bottom and a purified gas discharge outlet at the top, and both the inlet and the outlet are designed in a conical airway; A guide plate is arranged at the VOCs gas inlet, with a parallel guide plate arranged near the inlet and a corner guide plate arranged far from the inlet to guide the change of the airflow direction; A flow equalizing plate is arranged at the VOCs gas inlet to ensure that the gas in the furnace of the catalytic ozonation reactor is evenly distributed before entering the catalyst bed; The catalyst bed is a movable grid plate placed on the cross-sectional plane of the gas channel of the catalytic reactor.

2. The tower type VOCs catalytic ozonation reactor according to claim 1, characterized in that: The fluid dead area of ​​the furnace of the catalytic ozone oxidation reactor adopts a sloped or arc-shaped structure design.

3. The tower type VOCs catalytic ozonation reactor according to claim 1, characterized in that: The conical airway adopts a quadrangular pyramid and a conical structure design.

4. The tower type VOCs catalytic ozonation reactor according to claim 1, characterized in that: The corner guide plates include obtuse-angle guide plates, right-angle guide plates, and arc-shaped guide plates.

5. The tower type VOCs catalytic ozonation reactor according to claim 1, characterized in that: The catalyst bed is divided into two layers and adopts a porous grid support design. The hole diameter of the porous grid is 5-15mm.

6. A flow field simulation method for a tower VOCs catalytic ozonation reactor, characterized in that: Based on the tower VOCs catalytic ozonation reactor according to any one of claims 1 to 5, the flow field simulation method comprises the following steps: Based on the three-dimensional structure of the catalytic ozonation reactor, a flow field model was established; Extracting the internal fluid region of the flow field model, limiting the boundary conditions of the fluid region and determining the fluid calculation domain by setting boundary parameters; Based on the fluid computational domain, determining the minimum computational unit of the fluid computational domain by unit grid division; Based on the fluid calculation domain and its minimum calculation unit, a turbulence model of the airflow is established; Based on the turbulence model, the initial inlet velocity of the gas is selected by the diameter of the boundary inlet; Based on different inlet velocities, the flow field distribution diagram of the catalytic ozonation reactor is simulated, and its internal airflow distribution is determined.

7. The flow field simulation method of the tower VOCs catalytic ozonation reactor according to claim 6, characterized in that: The meshing tool is Fluent meshing or ICEM, wherein the mesh type of the fluid calculation domain is selected as a regular tetrahedral mesh or a regular hexahedral mesh.

8. The flow field simulation method of the tower VOCs catalytic ozonation reactor according to claim 6, characterized in that: The turbulence model includes: The energy equation is: Where ρ is the fluid density, t is the time, u is the viscosity coefficient, p is the pressure, T is the temperature, x is the Cartesian coordinate, λ is the thermal conductivity, w is the vorticity, h is the specific enthalpy, and q is the heat source term; The momentum equation is: Where ρ is the fluid density, t is the time, u is the viscosity coefficient, p is the pressure, F is the volume force term, and x is the Cartesian coordinate.

9. The flow field simulation method of a tower VOCs catalytic ozonation reactor according to claim 6, characterized in that: The initial inlet velocities are 8.373 m / s, 12.559 m / s, and 16.746 m / s.

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