A method for regulating evaporation separation of electroplating wastewater

Abstract

The application discloses a kind of evaporation separation electroplating wastewater's regulation and control method, by adjusting the pressure in evaporation separation tower to different components or working condition electroplating wastewater is effectively handled, realize the complete crystallization before electroplating wastewater discharge.This regulation and control method includes steps 10, calculate the physical parameters of electroplating wastewater solution to be handled;Step 20, establish spray evaporation separation tower model;According to the spray evaporation separation tower model, calculate the optimum pressure value of electroplating wastewater solution to be handled in evaporation separation tower;Step 30, send electroplating wastewater solution to be handled to evaporation separation tower, and form mist through pressure nozzle in evaporation separation tower by electroplating wastewater solution to be handled;According to the optimum pressure value in evaporation separation tower, control vortex fan and electric heater, so that the air pressure in evaporation separation tower is optimum pressure value, realize the regulation and control of evaporation separation electroplating wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment and relates to a control method for evaporating and separating electroplating wastewater. Background Art

[0002] In recent years, the contradiction between environmental pollution and development has become a prominent conflict in economic development, production, and life, and a major issue within industrial production. Over the past five years, wastewater discharge, particularly industrial wastewater, has continued to rise. As a component of industrial wastewater, electroplating wastewater is particularly important due to its dispersed production, rapid contamination spread, and difficulty in treatment.

[0003] Evaporation separation technology is a common method for treating electroplating wastewater. This technology utilizes the principle of evaporation to remove water from wastewater, concentrating and separating harmful substances in the wastewater, thereby achieving wastewater treatment and resource recycling. Traditional evaporation separation systems require high-temperature separation media, resulting in high energy consumption and inability to achieve both "zero waste discharge" and high energy efficiency.

[0004] Pressure is a crucial parameter in the evaporation separation process. It directly impacts the efficiency, evaporation rate, and separation quality of the evaporation process. Therefore, there is an urgent need to find a method to calculate the optimal pressure for the evaporation separation process. By adjusting the pressure, we can achieve efficient treatment of electroplating wastewater and reduce the energy consumption of the evaporation separation system. Summary of the Invention

[0005] In order to address the shortcomings and deficiencies of the existing technology, the present invention provides a control method for evaporating and separating electroplating wastewater. By adjusting the pressure in the evaporation separation tower, electroplating wastewater with different components or working conditions is effectively treated to achieve complete crystallization of the electroplating wastewater before discharge.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A control method for evaporating and separating electroplating wastewater comprises the following steps:

[0008] Step 10: Calculate the physical parameters of the electroplating wastewater solution to be treated, wherein the physical parameters of the electroplating wastewater solution to be treated include the specific heat capacity, density, and dynamic viscosity of the electroplating wastewater solution to be treated; the electroplating wastewater solution to be treated contains n kinds of metal ion solutes; n is an integer greater than or equal to 2;

[0009] Step 20: Establish a spray evaporation separation tower model; and calculate the optimal pressure value of the electroplating wastewater solution to be treated in the evaporation separation tower according to the spray evaporation separation tower model;

[0010] Step 30, the evaporation separation tower is transported to the electroplating wastewater solution to be processed, the electroplating wastewater solution to be processed is formed in the evaporation separation tower by the pressure nozzle mist; according to the best pressure value in the evaporation separation tower, the vortex fan and the electric heater are controlled, so that the air pressure in the evaporation separation tower is the best pressure value, and the regulation and control of the evaporation separation electroplating wastewater are realized.

[0011] As a preferred example, in step 10, the specific heat capacity of the electroplating wastewater solution to be processed is calculated according to formula (1), the density of the electroplating wastewater solution to be processed is calculated according to formula (2), and the dynamic viscosity of the electroplating wastewater solution to be processed is calculated according to formula (3):

[0012]

[0013]

[0014]

[0015] In the formula, c p represents the specific heat capacity of the electroplating wastewater solution to be processed, c p,1 represents the specific heat capacity of the first solute in the electroplating wastewater solution to be processed, represents the mass percentage of the first solute in the electroplating wastewater solution to be processed, c p,2 represents the specific heat capacity of the second solute in the electroplating wastewater solution to be processed, represents the mass percentage of the second solute in the electroplating wastewater solution to be processed; c p,n represents the specific heat capacity of the n-th solute in the electroplating wastewater solution to be processed, represents the mass percentage of the n-th solute in the electroplating wastewater solution to be processed; p s represents the density of the electroplating wastewater solution to be processed, p1 represents the density of the first solute in the electroplating wastewater solution to be processed, p2 represents the density of the second solute in the electroplating wastewater solution to be processed, p n represents the density of the n-th solute in the electroplating wastewater solution to be processed; m s represents the dynamic viscosity of the electroplating wastewater solution to be processed, m1 represents the dynamic viscosity of the first solute in the electroplating wastewater solution to be processed, m2 represents the dynamic viscosity of the second solute in the electroplating wastewater solution to be processed, m n represents the dynamic viscosity of the n-th solute in the electroplating wastewater solution to be processed; satisfy formula (4):

[0016]

[0017] As a preferred example, in step 20, the spray evaporation separation tower model is shown in formula (5) and formula (6):

[0018] The Sauter mean diameter is used to represent the average size of the uneven liquid drops sprayed from the pressure nozzle, as shown in equation (5):

[0019]

[0020] In the formula, r d0 is the droplet radius at the inlet of the tower body of the evaporation separation tower, in units of m; a is an adjustment coefficient related to the dynamic viscosity of the electroplating wastewater solution to be treated, in units of kg / s 2 ; θ is the spray half-angle of the pressure nozzle; μ s is the dynamic viscosity of the electroplating wastewater solution to be treated, in units of Pa·s; ρ a is the air density in the evaporation separation tower, in units of kg / m 3 ; p noz is the pressure of the pressure nozzle, in units of Pa; O is the spray liquid film thickness of the pressure nozzle, in units of m; b is an adjustment coefficient related to the density of the electroplating wastewater solution to be treated, in units of Pa·m; ρ s is the density of the electroplating wastewater solution to be treated, in units of kg / m 3 ;

[0021]

[0022] In the formula, O is the spray liquid film thickness of the pressure nozzle, in units of m; d noz is the spray diameter of the pressure nozzle, in units of m; m s is the mass flow of the electroplating wastewater solution to be treated, in units of kg / s; μ s is the dynamic viscosity of the electroplating wastewater solution, in units of Pa·s; ρ s is the density of the electroplating wastewater solution to be treated, in units of kg / m 3 ; p noz is the pressure of the pressure nozzle, in units of Pa; p a is the air pressure in the evaporation separation tower, in units of Pa; l sp is the length of the pressure nozzle, in units of m.

[0023] As a preferred example, in the step 20, the process of calculating the optimal pressure value of the electroplating wastewater to be treated in the evaporation separation tower according to the spray evaporation separation tower model is:

[0024] Step 201, calculate the spray liquid film thickness O of the pressure nozzle by equation (6), wherein p a The initial value is equal to the external environment air pressure; then substitute the spray liquid film thickness O of the pressure nozzle into equation (5) to calculate the droplet radius r d0 at the inlet of the tower body of the evaporation separation tower;

[0025] Step 202: The electroplating wastewater solution to be treated is formed into droplets through a pressure nozzle in an evaporation separation tower. The three stages of a single droplet refer to the first stage of single droplet evaporation without a shell, the second stage of single droplet shell formation, and the third stage of single droplet evaporation with a shell in the evaporation separation tower. In the second stage, a bottom shell is first formed at the bottom of the droplet, and then the area of ​​the bottom shell gradually increases, eventually covering the entire droplet surface. I is defined as the ratio of the surface area of ​​the droplet not covered by the shell to the total surface area of ​​the droplet, as shown in formula (7):

[0026]

[0027] Where A d is the droplet area, in m 2 ; A cr is the shell area of ​​the droplet, in m 2 ;

[0028] Calculate the droplet parameters of the tower outlet of the evaporation separation tower, substitute into formula (7), and calculate the I of the droplet at the tower outlet; if I≤0, the wastewater at the outlet is in a completely crystalline state, and replace p in formula (6) a As the optimal pressure value; if I>0, the wastewater at the outlet is unsaturated, and p a The pressure setting decreases as the value decreases, and the process returns to step 201 until I≤0. Then, the p in equation (6) is a is the optimal pressure value calculated iteratively.

[0029] As a preferred example, in step 202, the pressure setting reduction value is 10 kPa.

[0030] As a preferred example, in step 202, the calculation of the droplet parameters at the tower outlet of the evaporation separation tower specifically includes: according to the droplet radius r at the tower outlet d,out , calculate the droplet area A d ,in, Where m s is the mass flow rate of electroplating wastewater solution, in kg / s; ρ s is the density of the electroplating wastewater solution to be treated; the shell area of ​​the droplet Where r cr is the droplet shell radius at the tower outlet.

[0031] As a preferred example, the evaporation separation tower comprises a top, a tower body and a base which are sequentially connected from top to bottom; and the tower body of the evaporation separation tower gradually shrinks from top to bottom.

[0032] As a preferred example, the evaporation separation tower top comprises, from top to bottom, a first expansion section, an intermediate section, a second expansion section and a connecting section; the diameter of the first expansion section gradually increases from top to bottom, the diameter of the second expansion section gradually increases from top to bottom, the intermediate section and the connecting section are both cylindrical, the bottom end diameter of the first expansion section, the top end diameter of the second expansion section and the diameter of the intermediate section are equal, and the bottom end diameter of the second expansion section and the diameter of the connecting section are equal.

[0033] As a preferred example, the evaporation separation tower body corner is 5-15°.

[0034] Compared with the disadvantages and deficiencies of the prior art, the present application has the following beneficial effects: the control method effectively treats electroplating wastewater of different components or working conditions by adjusting the pressure in the evaporation separation tower, and realizes complete crystallization of the electroplating wastewater before discharge. The method can calculate the optimal pressure value of the evaporation separation of the electroplating wastewater of different components and working conditions in the evaporation separation tower, and adjust the pressure in the evaporation separation tower to the optimal pressure value during the evaporation separation process, which can effectively treat electroplating wastewater of multiple concentrations and multiple solutes. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a method flowchart of an embodiment of the present application;

[0036] Figure 2 is a structural schematic diagram of an evaporation separation device employed in an embodiment of the present application;

[0037] Figure 3 is a structural schematic diagram of an evaporation separation tower employed in an embodiment of the present application.

[0038] In the figure: vortex fan 1, electric heater 2, evaporation separation tower 3, top 31, first expansion section 311, intermediate section 312, second expansion section 313, connecting section 314, tower body 32, base 33; pressure nozzle 4, liquid storage tank 5, bag-type dust collector 6. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0040] As Figure 1 shown, a control method for evaporation separation of electroplating wastewater according to an embodiment of the present application comprises the following steps:

[0041] Step 10, calculating the physical parameters of the electroplating wastewater solution to be treated, the physical parameters of the electroplating wastewater solution to be treated including the specific heat capacity, density and dynamic viscosity of the electroplating wastewater solution to be treated; the electroplating wastewater solution to be treated containing n kinds of metal ion solutes; n being an integer greater than or equal to 2.

[0042] Step 20, establishing a spray evaporation separation tower model; according to the spray evaporation separation tower model, calculating the optimal pressure value of the electroplating wastewater solution to be treated in the evaporation separation tower 3.

[0043] Step 30, conveying the electroplating wastewater solution to be treated into the evaporation separation tower 3, the electroplating wastewater solution to be treated forming a mist through a pressure nozzle in the evaporation separation tower 3; according to the optimal pressure value in the evaporation separation tower 3, controlling the vortex fan 1 and the electric heater 2 so that the air pressure in the evaporation separation tower 3 is the optimal pressure value, realizing the regulation and control of the evaporation separation electroplating wastewater.

[0044] The regulation and control method of the above embodiment, by calculating the optimal pressure value in the evaporation separation tower 3, then regulating and controlling the gas pressure in the evaporation separation tower 3 to be equal to the optimal pressure value. When the gas pressure in the evaporation separation tower 3 is the optimal pressure value, the electroplating wastewater solution to be treated can be completely crystallized in a solid state when it is discharged from the outlet of the evaporation separation tower 3. This can avoid the higher air temperature required for treating the electroplating wastewater solution under a non-optimal pressure, thereby realizing the reduction of energy consumption.

[0045] The regulation and control method of the above embodiment, the electroplating wastewater to be treated containing multiple metal ion solutes. Through this regulation and control method, these metal ion solutes can all be discharged in a crystal state. When working, the temperature in the evaporation separation tower 3 is 100-150℃. The device can operate at medium and low temperature (within 150℃), without the need for special equipment, low sealing requirement, less consumables, low requirement for materials, simple and convenient, low operating cost. This method uses air as a separation carrier to treat electroplating wastewater, the separation carrier is easy to obtain and is basically not limited by the environment.

[0046] Preferably, in step 10, the specific heat capacity of the electroplating wastewater solution to be treated is calculated according to formula (1), the density of the electroplating wastewater solution to be treated is calculated according to formula (2), and the dynamic viscosity of the electroplating wastewater solution to be treated is calculated according to formula (3):

[0047]

[0048]

[0049]

[0050] In the formula, c prepresents the specific heat capacity of the electroplating wastewater solution to be treated, c p,1 represents the specific heat capacity of the first solute in the electroplating wastewater solution to be treated, c represents the mass percentage of the first solute in the electroplating wastewater solution to be treated, c p,2 represents the specific heat capacity of the second solute in the electroplating wastewater solution to be treated, c represents the mass percentage of the second solute in the electroplating wastewater solution to be treated, c p,n represents the specific heat capacity of the nth solute in the electroplating wastewater solution to be treated, c represents the mass percentage of the nth solute in the electroplating wastewater solution to be treated, c s represents the density of the electroplating wastewater solution to be treated, represents the density of the first solute in the electroplating wastewater solution to be treated, represents the density of the second solute in the electroplating wastewater solution to be treated, represents the density of the nth solute in the electroplating wastewater solution to be treated, and n represents the density of the nth solute in the electroplating wastewater solution to be treated, and s represents the dynamic viscosity of the electroplating wastewater solution to be treated, represents the dynamic viscosity of the first solute in the electroplating wastewater solution to be treated, represents the dynamic viscosity of the second solute in the electroplating wastewater solution to be treated, represents the dynamic viscosity of the nth solute in the electroplating wastewater solution to be treated, and n represents the dynamic viscosity of the nth solute in the electroplating wastewater solution to be treated, and satisfies equation (4):

[0051]

[0052] Preferably, in step 20, the spray evaporation separation tower model is shown in equations (5) and (6):

[0053] The average size of the non-uniform droplets sprayed from the pressure nozzle is represented by the Sauter mean diameter, as shown in equation (5):

[0054]

[0055] In the equation, r d0 is the droplet radius at the inlet of the tower body of the evaporation separation tower 3, with a unit of m; a is an adjustment coefficient related to the dynamic viscosity of the electroplating wastewater solution to be treated, with a unit of kg / s 2 ; θ is the spray half-angle of the pressure nozzle; μ s is the dynamic viscosity of the electroplating wastewater solution to be treated, with a unit of Pa·s; ρ a is the air density in the evaporation separation tower 3, with a unit of kg / m 3 ; p noz is the pressure of the pressure nozzle, with a unit of Pa; O is the spray liquid film thickness of the pressure nozzle, with a unit of m; b is an adjustment coefficient related to the density of the electroplating wastewater solution to be treated, with a unit of Pa·m; and ρs ρ is the density of the electroplating wastewater solution to be treated, in kg / m 3 . Preferably, a = 2.26 kg / s 2 , b = 0.195 Pa-m.

[0056]

[0057] In the formula, O is the spray film thickness of the pressure nozzle, in m; d noz is the spray diameter of the pressure nozzle, in m; m s is the mass flow of the electroplating wastewater solution to be treated, in kg / s; μ s is the dynamic viscosity of the electroplating wastewater solution, in Pa-s; ρ s is the density of the electroplating wastewater solution to be treated, in kg / m 3 ; p noz is the pressure of the pressure nozzle, in Pa; p a is the air pressure in the evaporation separation tower, in Pa; l sp is the length of the pressure nozzle, in m.

[0058] Preferably, in the step 20, the process of calculating the optimal pressure value of the electroplating wastewater to be treated in the evaporation separation tower according to the spray evaporation separation tower model is:

[0059] Step 201, calculate the spray film thickness O of the pressure nozzle by formula (6), wherein p a The initial value is equal to the external environment air pressure; then substitute the spray film thickness O of the pressure nozzle into formula (5) to calculate the droplet radius r d0 of the tower body inlet of the evaporation separation tower;

[0060] Step 202, the electroplating wastewater solution to be treated forms droplets through the pressure nozzle in the evaporation separation tower 3; the three stages of single droplet refer to the first stage of single droplet evaporation without shell, the second stage of single droplet shell formation, and the third stage of single droplet evaporation with shell in the evaporation separation tower 3; in the second stage, a bottom shell is first formed at the bottom of the droplet, then the bottom shell area gradually increases, and finally covers the entire droplet surface, and I is defined as the ratio of the surface area of the droplet not covered by the shell to the total surface area of the droplet, as shown in formula (7):

[0061]

[0062] In the formula, A d is the droplet area, in m 2 ; A cr is the shell area of the droplet, in m 2 ;

[0063] Calculate the droplet parameters of the tower outlet of the evaporation separation tower, substitute into formula (7), and calculate the I of the droplet at the tower outlet; if I≤0, the wastewater at the outlet is in a completely crystalline state, and replace p in formula (6) a As the optimal pressure value; if I>0, the wastewater at the outlet is unsaturated, and p a The pressure setting decreases as the value decreases, and the process returns to step 201 until I≤0. Then, the p in equation (6) is a The optimal pressure value is calculated iteratively. Preferably, the pressure setting reduction value is 10 kPa.

[0064] The optimal pressure value of the electroplating wastewater to be treated in the evaporation separation tower is obtained through iterative calculations in steps 201 and 202. This iterative calculation uses parameter I to determine whether the air pressure in the tower is at the optimal value. After iteratively calculating the optimal air pressure in the tower, the electroplating wastewater solution can be effectively treated to a crystalline state and energy consumption can be reduced.

[0065] Preferably, in step 202, calculating the droplet parameters at the tower outlet of the evaporation separation tower specifically includes:

[0066] According to the droplet radius r at the tower outlet d,out , calculate the droplet area A d ,in, Where m s is the mass flow rate of electroplating wastewater solution, in kg / s; ρ s is the density of the electroplating wastewater solution to be treated; the shell area of ​​the droplet Where r cr is the radius of the droplet shell at the tower outlet. cr =0.02r d0 .

[0067] The surface heat transfer coefficient and surface mass transfer coefficient of a single droplet in three stages of the electroplating wastewater solution to be treated in the evaporation separation tower 3 are calculated; the electroplating wastewater solution to be treated forms droplets through a pressure nozzle in the evaporation separation tower 3; the three stages of the single droplet refer to a first stage of single droplet evaporation without a shell, a second stage of single droplet shell formation, and a third stage of single droplet evaporation with a shell in the evaporation separation tower 3.

[0068] The single droplet surface heat transfer coefficient α1 in the first stage is calculated according to formula (8):

[0069]

[0070] Where λ a is the thermal conductivity of the air in the evaporation separation tower 3, in W·m -1 ℃ -1 ;Nu sNu is the Nusselt number of the electroplating wastewater solution to be treated, dimensionless; r d is the droplet radius, in m.

[0071] The single droplet surface heat transfer coefficient a3 of the third stage is calculated according to formula (9):

[0072]

[0073] In the formula, λ a is the air thermal conductivity within the evaporation separation tower 3, in W·m -1 ·°C -1 ; Nu s is the Nusselt number of the electroplating wastewater solution to be treated, dimensionless; r d is the droplet radius, in m; λ cr is the shell thermal conductivity of the droplet, in W·m -1 ·°C -1 ; δ cr is the shell thickness of the droplet, in m.

[0074] The single droplet surface mass transfer coefficient b1 of the first stage is calculated according to formula (10):

[0075]

[0076] In the formula, C M,a,1 is the air mass transfer diffusion coefficient of the first stage, in m 2 / s; Sh s is the Sherwood number of the electroplating wastewater solution to be treated, dimensionless; r d is the droplet radius, in m.

[0077] The single droplet surface mass transfer coefficient b3 of the third stage is calculated according to formula (11):

[0078]

[0079] In the formula, C M,a,1 is the air mass transfer diffusion coefficient of the first stage, in m 2 / s; Sh s is the Sherwood number of the electroplating wastewater solution, dimensionless; r d is the droplet radius, in m; C M,a,3 is the air mass transfer diffusion coefficient of the third stage, in m 2 / s; δ cr is the shell thickness of the droplet, in m.

[0080] In the second stage, a bottom shell is first formed at the bottom of the droplet, and then the area of ​​the bottom shell gradually increases until it covers the entire droplet surface. I is defined as the ratio of the surface area of ​​the droplet not covered by the shell to the total surface area of ​​the droplet, as shown in Equation (7):

[0081]

[0082] Where A d is the droplet area, in m 2 ; A cr is the shell area of ​​the droplet, in m 2 .

[0083] The single droplet surface heat transfer coefficient α2 in the second stage is calculated according to formula (12):

[0084] α2=Iα1+(1-I)α3 Formula (12).

[0085] The single droplet surface mass transfer coefficient β2 in the second stage is calculated according to formula (13):

[0086] β2=Iβ1+(1-I)β3 Formula (13).

[0087] Preferably, Figure 2 As shown, the evaporative separation device used in the control method of this embodiment includes a vortex blower 1, an electric heater 2, an evaporative separation tower 3, a pressure nozzle 4, a liquid storage tank 5, and a bag filter 6. The evaporative separation tower 3 includes a top 31, a tower body 32, and a base 33, which are connected in sequence from top to bottom. The tower body 32 of the evaporative separation tower gradually decreases from top to bottom. Preferably, the tower body 32 of the evaporative separation tower has a contraction angle of 5 to 15 degrees. The vortex blower 1 is connected to the top 31 of the evaporative separation tower via a first pipe, and the electric heater 2 is connected to the first pipe. The vortex blower 1 is used to draw in external ambient air. The electric heater 2 is used to heat the external ambient air to a desired temperature. The vortex blower 1 and the electric heater 2 heat the external ambient air to the desired temperature, forming hot air, which is then transported to the inner cavity of the top 31 of the evaporative separation tower. The temperature of the hot air is 110 to 150°C. The external ambient air is at room temperature, for example, 18 to 22°C. The outlet of the liquid storage tank 5 is connected to the pressure nozzle 4 through a valve. The pressure nozzle 4 is located at the upper part of the inner cavity of the evaporation separation tower 3. An exhaust pipe is provided at the bottom of the evaporation separation tower 3, and a bag dust collector 6 is provided in the exhaust pipe.

[0088] The liquid storage tank 5 is used to store the electroplating wastewater to be treated. The pressure nozzle 4 is used to atomize the electroplating wastewater into a spray. In operation, the valve is opened, and the electroplating wastewater in the liquid storage tank 5 is pressurized by the pump and flows to the pressure nozzle 4. The electroplating wastewater is atomized into a spray by the pressure nozzle 4 in the inner cavity of the evaporation separation tower top 31. The electroplating wastewater is atomized into a spray by the pressure nozzle 4, which is more conducive to heat exchange between the electroplating wastewater and the hot air delivered from the hot air assembly, so that the water in the misty electroplating wastewater is more easily evaporated. The misty electroplating wastewater and the hot air converge at the top 31 of the evaporation separation tower and flow from top to bottom. In the process of flowing, the misty electroplating wastewater and the hot air are further heat exchanged.

[0089] The electric heater 2 can adjust the air temperature. According to different electroplating wastewater compositions or working conditions, the heat and mass transfer process in the evaporation separation tower 3 is strengthened by adjusting the flow rate and pressure of the electroplating wastewater, as well as the air temperature.

[0090] The electroplating wastewater and the hot air fall from top to bottom in the evaporation separation tower 3, and heat exchange is achieved in the process of falling, and the water in the electroplating wastewater evaporates. At the bottom of the evaporation separation tower 3, the exhaust gas is discharged from the exhaust pipe, the water in the electroplating wastewater evaporates, and solid recovery is formed. The electroplating wastewater flows from top to bottom in the tower body 32 of the evaporation separation tower, and the concentration becomes higher and higher. Compared with the electroplating wastewater located at the upper part of the tower body 32, the electroplating wastewater located at the lower part of the tower body 32 is high-concentration electroplating wastewater. The high-concentration electroplating wastewater in the lower part of the evaporation separation tower 3 has a large heat and mass transfer resistance with the hot air, resulting in poor heat and mass transfer effect. In this embodiment, the tower body 32 of the evaporation separation tower gradually narrows instead of being in the shape of a cylinder with equal diameters. The tower body of the evaporation separation tower 3 gradually narrows, which can improve the driving force of heat and mass transfer after reducing the pressure of the high-concentration electroplating wastewater, thereby achieving the effect of strengthening the heat and mass transfer between the high-concentration electroplating wastewater and the hot air.

[0091] Preferably, as shown in Figure 3 The evaporation separation tower top 31 comprises, from top to bottom, a first expansion part 311, an intermediate part 312, a second expansion part 313, and a connecting part 314; the diameter of the first expansion part 311 gradually increases from top to bottom, the diameter of the second expansion part 313 gradually increases from top to bottom, the intermediate part 312 and the connecting part 314 are in the shape of a cylinder, the diameter of the bottom end of the first expansion part 311, the diameter of the top end of the second expansion part 313, and the diameter of the intermediate part 312 are equal, and the diameter of the bottom end of the second expansion part 313 and the diameter of the connecting part 314 are equal. The connecting part 314 in the shape of a cylinder is provided for connecting the evaporation separation tower top 31 and the tower body 32. As shown in Figure 3The top 31 of the evaporation separation tower can be connected with the tower body 32 by a connecting flange. The first expansion part 311 and the second expansion part 313 are both in the shape of a horn mouth with the upper part being small and the lower part being large, so as to reduce the speed of the airflow, so that the hot air is more fully mixed with the misty electroplating wastewater, and the moisture in the misty electroplating wastewater is evaporated more quickly. The airflow flowing through the vortex fan 1 and the electric heater 2 has a high speed after entering the top 31 of the evaporation separation tower. The speed of the airflow is reduced through the first expansion part 311 and the second expansion part 313.

[0092] In the method of the embodiment, the optimal pressure value is maintained during the operation of the evaporation separation tower, so that the required inlet air temperature for complete evaporation separation is the lowest, and therefore, the pressure in the evaporation separation tower is reduced to make the electroplating wastewater reach complete evaporation separation at a low inlet air temperature. Preferably, the temperature of the hot air entering the evaporation separation tower is 110-150°C. According to different components or working conditions of the electroplating wastewater, the pressure in the evaporation separation tower is adjusted to optimize and control the evaporation separation treatment of the electroplating wastewater.

[0093] The method of the embodiment determines the optimal pressure when treating electroplating wastewater with different components or working conditions by establishing an evaporation separation tower model with adjustable pressure, and performs adjustment and control. The tower body of the evaporation separation tower is in a tapered structure from top to bottom. The principle of the tapered nozzle is used to gradually reduce the pressure of the electroplating wastewater in the tower, so that the electroplating wastewater with a higher concentration in the middle and lower parts of the tower body can be effectively treated.

[0094] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for the controlled evaporation of electroplating wastewater, characterized in that, The regulation method comprises the following steps: Step 10, calculating the physical parameters of the electroplating wastewater solution to be treated, the physical parameters of the electroplating wastewater solution to be treated including the density and dynamic viscosity of the electroplating wastewater solution to be treated; the electroplating wastewater solution to be treated containing n kinds of metal ion solutes; n is an integer greater than or equal to 2; Step 20, establishing a spray evaporation separation tower model; according to the spray evaporation separation tower model, calculating the optimal pressure value of the electroplating wastewater solution to be treated in the evaporation separation tower (3); Step 30, delivering the electroplating wastewater solution to be treated into the evaporation separation tower (3), the electroplating wastewater solution to be treated forming mist through pressure nozzles in the evaporation separation tower (3); according to the optimal pressure value in the evaporation separation tower (3), controlling the vortex fan (1) and the electric heater (2) so that the air pressure in the evaporation separation tower (3) is the optimal pressure value, realizing the regulation and control of the evaporation separation electroplating wastewater.

2. The method of claim 1, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. In the step 10, the density of the electroplating wastewater solution to be treated is calculated according to formula (2), and the dynamic viscosity of the electroplating wastewater solution to be treated is calculated according to formula (3): Formula (2) Formula (3) wherein, represents the mass percentage of the first solute in the electroplating wastewater solution to be treated, represents the mass percentage of the second solute in the electroplating wastewater solution to be treated; represents the mass percentage of the nth solute in the electroplating wastewater solution to be treated; represents the density of the electroplating wastewater solution to be treated, represents the density of the first solute in the electroplating wastewater solution to be treated, represents the density of the second solute in the electroplating wastewater solution to be treated, represents the density of the nth solute in the electroplating wastewater solution to be treated; represents the dynamic viscosity of the electroplating wastewater solution to be treated, represents the dynamic viscosity of the first solute in the electroplating wastewater solution to be treated, represents the dynamic viscosity of the second solute in the electroplating wastewater solution to be treated, represents the dynamic viscosity of the nth solute in the electroplating wastewater solution to be treated; satisfies formula (4): Equation (4).

3. The method of claim 1, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. In the step 20, the spray evaporation separation tower model is shown in formula (5) and formula (6): The Sauter average diameter is used to represent the average size of the non-uniform droplets sprayed from the pressure nozzle, as shown in formula (5): ， In the formula, is the droplet radius at the inlet of the column body of the evaporative separation column (3) in meters; is an adjustment coefficient related to the dynamic viscosity of the electroplating wastewater solution to be treated in ; is the spray half-angle of the pressure nozzle; is the dynamic viscosity of the electroplating wastewater solution to be treated in ; is the air density in the evaporative separation column (3) in kg / m 3 ; is the pressure of the pressure nozzle in Pa; is the spray liquid film thickness of the pressure nozzle in meters; is an adjustment coefficient related to the density of the electroplating wastewater solution to be treated in ; is the density of the electroplating wastewater solution to be treated in kg / m 3 ; Formula (6) wherein is the spray film thickness of the pressure nozzle in m; is the spray diameter of the pressure nozzle in m; is the mass flow of the electroplating wastewater solution to be treated in kg / s; is the dynamic viscosity of the electroplating wastewater solution in m ; is the density of the electroplating wastewater solution to be treated in kg / m 3 ; is the pressure of the pressure nozzle in Pa; is the air pressure in the evaporation separation column in Pa; is the length of the pressure nozzle in m.

4. The method of claim 3, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. In the step 20, according to the spray evaporation separation tower model, the process of calculating the optimal pressure value of the electroplating wastewater to be treated in the evaporation separation tower is as follows: Step 201, calculate the spray liquid film thickness of the pressure nozzle by formula (6) wherein, The initial value is equal to the external environment air pressure; then calculate the spray liquid film thickness of the pressure nozzle Substitute into formula (5) to calculate the droplet radius at the inlet of the tower body of the evaporation separation tower ; Step 202, the electroplating wastewater solution to be treated forms droplets through pressure nozzles in the evaporation separation tower (3); the three stages of single droplet refer to the first stage of single droplet evaporation without shell, the second stage of single droplet shell formation and the third stage of single droplet evaporation with shell in the evaporation separation tower (3); in the second stage, a bottom shell is first formed at the bottom of the droplet, then the bottom shell area gradually increases, and finally covers the entire droplet surface, and I is defined as the ratio of the uncoated surface area of the droplet to the total surface area of the droplet, as shown in formula (7): Formula (7) wherein is the droplet area in m 2 ; is the shell area of the droplet in m 2 ; The droplet parameter at the tower body outlet of the evaporation separation tower is calculated, substituted into formula (7), and I of the droplet at the tower body outlet is calculated; if I≤0, the waste water at the outlet is in a complete crystallization state, and the value of P in formula (6) is taken as the optimal pressure value; if I>0, the waste water at the outlet is in an unsaturated state, and the value of P in formula (6) is taken as the optimal pressure value ; if I>0, the waste water at the outlet is in an unsaturated state, and the value of P in formula (6) is taken as the optimal pressure value ; if I>0, the waste water at the outlet is in an unsaturated state, and the value of P in formula (6) is taken as the optimal pressure value ; if I>0, the waste water at the outlet is in an unsaturated state, and the value of P in formula (6) is taken as the optimal pressure value 5. The method of claim 4, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. In the step 202, the pressure setting reduction value is 10 kPa.

6. The method of claim 4, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. In the step 202, the droplet parameter at the tower body outlet of the evaporation separation tower is calculated, specifically comprising: calculating the droplet radius at the tower body outlet according to the droplet radius at the tower body inlet , calculating the droplet area , wherein , ; in the formula, is the mass flow of the electroplating wastewater solution, in kg / s; is the density of the electroplating wastewater solution to be treated; the shell area of the droplet , wherein is the shell radius of the droplet at the tower body outlet.

7. The method of claim 6, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. The .

8. The method of claim 1, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. The evaporation separation tower (3) comprises a top (31), a tower body (32) and a base (33) connected in sequence from top to bottom; from top to bottom, the tower body (32) of the evaporation separation tower gradually narrows.

9. The method of claim 8, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. The top (31) of the evaporation separation tower comprises a first expansion part (311), an intermediate part (312), a second expansion part (313) and a connecting part (314) connected in sequence from top to bottom; the diameter of the first expansion part (311) gradually increases from top to bottom, the diameter of the second expansion part (313) gradually increases from top to bottom, the intermediate part (312) and the connecting part (314) are both cylindrical, the bottom end diameter of the first expansion part (311), the top end diameter of the second expansion part (313) and the diameter of the intermediate part (312) are equal, and the bottom end diameter of the second expansion part (313) and the diameter of the connecting part (314) are equal.

10. The method of claim 8, wherein the evaporation separation of the electroplating wastewater is regulated by controlling the temperature of the electroplating wastewater. The tower body (32) of the evaporation separation tower has an included angle of 5-15°.

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