Control method and system for edible salt evaporation unit

Abstract

The invention discloses a control method and system for an edible salt evaporation unit. The control method comprises the steps that brine parameters in a first evaporation tank are obtained; setting execution parameters of three evaporation tanks according to the brine parameters; performing crystallization parameter acquisition on a first evaporation tank slurry discharge port, a second evaporation tank slurry discharge port and a third evaporation tank slurry discharge port at fixed time and fixed points, wherein the crystallization parameters at least comprise grain size, crystal form and grain size uniformity; and adjusting the execution parameters or flow of the downstream or the evaporation tank according to the crystallization parameters of the slurry discharge port of each evaporation tank. According to the control method, linkage adjustment of a plurality of evaporation tanks can be achieved, the adjustment is based on upstream real-time data, the reaction is rapid, the grain size and the grain size uniformity of table salt processed through the control method are controllable, the crystal form is well monitored, and table salt of various qualities can be produced conveniently.

Description

Technical Field

[0001] The invention relates to the field of automatic control, in particular to a control method and system for an edible salt evaporation unit. Background Art

[0002] In the existing salt market, in order to meet the needs of different customers, salt manufacturers have launched a variety of salt, such as classification based on the crystal shape, grain size, added elements, etc.

[0003] In the production and processing of salt, it is very difficult to control the grain size and crystal shape of salt. In order to meet the production of different grain sizes or screen salt of different crystal shapes, many companies achieve this by adjusting the process flow. In the actual production process, the control of key parameters (such as heating temperature, washing water volume, stirring speed, etc.) is more critical; however, in the traditional production process, it is difficult to achieve linkage adjustment of the key parameters of different equipment, which leads to unstable product quality or failure to obtain the desired product. Summary of the invention

[0004] Therefore, in order to solve the above-mentioned shortcomings, the present invention provides a control method and system for an edible salt evaporation unit. The present invention can realize the linkage adjustment of multiple evaporation tanks, and the adjustment is based on upstream real-time data, and the response is fast. The grain size and grain size uniformity of the edible salt processed by the control method of the present invention are more controllable, and the crystal shape is also better monitored, so as to produce edible salt of various qualities.

[0005] Specifically, a control method for an edible salt evaporation unit is provided, wherein the evaporation unit comprises at least three evaporation tanks connected in series, and are sequentially divided into a first evaporation tank, a second evaporation tank, and a third evaporation tank, each evaporation tank is provided with an agitator, a circulating temperature control tube, a sight glass, and a washing water pipe, and adjacent evaporation tanks are connected with a mother liquor connecting tube; the control method comprises:

[0006] Obtaining parameters of brine in the first evaporation tank, wherein the brine is purified and the parameters of the brine include at least brine volume, brine concentration, and sulfate concentration;

[0007] The execution parameters of the three evaporation tanks are set according to the brine parameters, and the execution parameters at least include stirring speed, evaporation temperature and washing water volume; wherein the stirring speed is achieved by controlling the stirrer, and the evaporation temperature is achieved by controlling the temperature and pressure of the medium in the circulating temperature control tube. When the temperature and pressure of the medium are determined, the evaporation temperature is further maintained by the flow rate of the medium; the washing water volume is achieved by controlling the water output of the washing water pipe; wherein the stirring speed of the first evaporation tank is greater than that of the second evaporation tank, and the speed of the third evaporation tank is not higher than that of the second evaporation tank;

[0008] Collecting crystallization parameters at the first evaporation tank discharge port, the second evaporation tank discharge port, and the third evaporation tank discharge port at a fixed time and point, wherein the crystallization parameters at least include grain size, crystal shape, and grain size uniformity;

[0009] adjusting the execution parameters of the second evaporator according to the crystallization parameters of the slurry discharge port of the first evaporator;

[0010] adjusting the execution parameters of the third evaporator according to the crystallization parameters of the slurry discharge port of the second evaporator;

[0011] Determine the flow rate of the third evaporator discharge port according to the crystallization parameters of the third evaporator discharge port;

[0012] The execution parameters of the second evaporation tank and the third evaporation tank are adjusted and the flow rate of the slurry discharge port of the third evaporation tank is determined synchronously.

[0013] Optionally, the crystallization parameters are obtained by analyzing after photographing with an imaging device installed in a sight glass, and the sight glass is located inside the pulp discharge port of the evaporation tank.

[0014] Optionally, the method of adjusting the execution parameters of the second evaporator according to the crystallization parameters of the slurry discharge port of the first evaporator is:

[0015] According to the grain size of the slurry discharge port of the first evaporator, the stirring speed and evaporation temperature of the second evaporator are regulated.

[0016] Assume that the grain size is the threshold range [ε, φ],

[0017] When the grain size of the slurry discharge port of the first evaporator is less than ε, the flow rate and stirring speed of the medium in the circulating temperature control tube of the second evaporator are increased, and the stirring speed of the first evaporator is also increased;

[0018] When the grain size of the slurry discharge port of the first evaporation tank is within the threshold range, the first evaporation tank and the second evaporation tank execute the existing execution parameters;

[0019] When the grain size of the slurry discharge port of the first evaporator is greater than φ, the flow rate and stirring speed of the medium in the circulating temperature control tube of the second evaporator are reduced, and the stirring speed of the first evaporator is also reduced.

[0020] Optionally, the method of adjusting the execution parameters of the third evaporator according to the crystallization parameters of the slurry discharge port of the second evaporator is:

[0021] The method for regulating the evaporation temperature and the amount of washing water in the third evaporator according to the crystal shape of the discharge port of the second evaporator is:

[0022] Optionally, the method for determining the flow rate of the third evaporator discharge port according to the crystallization parameter of the third evaporator discharge port is:

[0023] The opening and closing degree of the third evaporator discharge port is controlled by the uniformity of the grain size of the third evaporator discharge port, and the flow rate is controlled by the opening and closing degree of the discharge port.

[0024] The slurry discharge port of the third evaporator is set to be fully open and three-quarters open;

[0025] When the grain size uniformity is not less than the set value, the opening of the third evaporator discharge port is fully open;

[0026] When the uniformity of the grain size is less than the set value, the opening of the discharge port of the third evaporator is three quarters open.

[0027] Optionally, an evaporation tank can be added between the three evaporation tanks according to the working conditions and production requirements.

[0028] On the other hand, a control system for an edible salt evaporation unit is provided, the control system being used to implement the above control method, the control system comprising:

[0029] A control unit, used to receive and process data and send execution commands;

[0030] an input unit, connected to the control unit, and used to input data into the control unit; and

[0031] an execution unit, connected to the control unit, and configured to execute an execution command sent by the control unit;

[0032] The input unit includes at least: a molding device installed in each mirror, a temperature sensor and a sensor for measuring the rotation speed of the stirrer;

[0033] The execution unit at least comprises: an agitator, a washing water pump installed on the washing water pipe, and a circulation pump installed on the circulation temperature control pipe.

[0034] Optionally, the system further comprises a storage unit connected to the control unit and used for storing data of the control unit.

[0035] The present invention has the following advantages:

[0036] The present invention can realize the linkage adjustment of multiple evaporation tanks, and the adjustment is based on timely real-time data from the upstream, and the response is fast. The grain size and grain size uniformity of the salt processed by the control method of the present invention are relatively controllable, and the crystal shape is also well monitored, so as to produce salt of various qualities.

[0037] The present invention realizes linkage regulation by controlling the parameters of the three evaporation tanks, utilizes the previous evaporation tank to adjust the parameters of the next evaporation tank, and finally realizes the triangular cycle regulation of the three evaporation tanks. The data of the next evaporation tank is adjusted by the data of the previous evaporation tank, so that the parameters can be better adjusted, and the deficiency of the previous evaporation tank is compensated. After reaching the last evaporation tank, the parameters of the last evaporation tank are the best at that time. Due to the realization of the triangular cycle, even if the data is fed back, the best parameters at that time can also be taken into consideration when regulating the parameters of the first evaporation tank, and finally the three evaporation tanks are operated under the best parameters, so as to improve the processing quality of salt. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart of the control method for the edible salt evaporation unit according to the present invention;

[0039] Figure 2 It is a schematic diagram of the salt processing process;

[0040] Figure 3 It is a structural block diagram of the control system for the edible salt evaporation unit of the present invention;

[0041] In the figure: 100, evaporation unit; 101, first evaporation tank; 102, second evaporation tank; 103, third evaporation tank; 104, circulation temperature control tube; 105, stirrer; 106, sight glass; 200, control unit; 300, execution unit; 400, input unit; 500, storage unit. DETAILED DESCRIPTION

[0042] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0043] In this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises", or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or apparatus.

[0044] As described in the background technology, in the production and processing of table salt, it is very difficult to control the grain size and crystal shape of table salt. In order to meet the production of different grain sizes or screen table salt of different crystal shapes, many companies achieve this by adjusting the process flow. In the actual production process, the control of key parameters (such as heating temperature, washing water volume, stirring speed, etc.) is more critical; however, in the traditional production process, it is difficult to achieve linkage adjustment of the key parameters of different equipment, which leads to unstable product quality or failure to obtain the desired product.

[0045] Based on the above reasons, this embodiment provides a control method for an edible salt evaporation unit, wherein the evaporation unit 100 includes at least three evaporation tanks connected in series, which are respectively divided into a first evaporation tank 101, a second evaporation tank 102, and a third evaporation tank 103, each evaporation tank is provided with an agitator 105, a circulating temperature control tube 104, a sight glass 106, a washing water pipe and a slurry discharge pipe, and adjacent evaporation tanks are connected by a mother liquor connecting pipe.

[0046] like Figure 1 As shown, the control method includes:

[0047] Step S100, obtaining parameters of brine in the first evaporation tank, wherein the brine is purified and the parameters of the brine include at least brine volume, brine concentration, and sulfate concentration; and controlling the parameters of the mother liquor (such as mother liquor concentration and volume) in each evaporation tube to be substantially the same as above.

[0048] Step S200, setting the execution parameters of the three evaporation tanks according to the brine parameters (exemplarily, by the volume and concentration of the brine, using the existing process parameters to set more reliable execution parameters; and then adjusting the execution parameters by the following method), the execution parameters at least include stirring speed, evaporation temperature and elutriation water volume; wherein the stirring speed is achieved by controlling the stirrer, the evaporation temperature is achieved by controlling the temperature and pressure of the medium in the circulating temperature control tube, and when the temperature and pressure of the medium are determined, the evaporation temperature is further maintained by the flow rate of the medium; the elutriation water volume is achieved by controlling the water output of the elutriation water pipe; wherein the stirring speed of the first evaporation tank is greater than that of the second evaporation tank, and the speed of the third evaporation tank is not higher than that of the second evaporation tank;

[0049] Step S300, collecting crystallization parameters of the first evaporation tank discharge port, the second evaporation tank discharge port, and the third evaporation tank discharge port at a fixed time and point, wherein the crystallization parameters at least include grain size, crystal shape, and grain size uniformity;

[0050] Step S400: adjusting the execution parameters or flow of the downstream or current evaporator according to the crystallization parameters of the slurry discharge ports of each evaporator.

[0051] Exemplarily, step S400 includes:

[0052] adjusting the execution parameters of the second evaporator according to the crystallization parameters of the slurry discharge port of the first evaporator;

[0053] adjusting the execution parameters of the third evaporator according to the crystallization parameters of the slurry discharge port of the second evaporator;

[0054] Determine the flow rate of the third evaporator discharge port according to the crystallization parameters of the third evaporator discharge port;

[0055] The execution parameters of the second evaporation tank and the third evaporation tank are adjusted and the flow rate of the slurry discharge port of the third evaporation tank is determined synchronously.

[0056] The above technical features can be used to control the parameters of multiple evaporation tanks in a linked manner, which makes it easy to realize automatic control, and the parameter control is more precise, which facilitates the control of crystal shape and grain size.

[0057] In one embodiment, the crystallization parameters are obtained by analyzing after being photographed by an imaging device installed in a sight glass, and the sight glass is located on the inner side of the slurry discharge port of the evaporation tank; the crystallization parameters are obtained using existing technologies. For example, after obtaining high-definition photos through an imaging device, they are transmitted to a processor, and the processor obtains the size, number, shape, etc. of the grains after processing through existing technologies such as computer vision (for example, the principle of a software counting camera), thereby inferring the particle size, crystal shape and grain size uniformity.

[0058] Exemplarily, the method of adjusting the execution parameters of the second evaporator according to the crystallization parameters of the slurry discharge port of the first evaporator is:

[0059] According to the grain size of the slurry discharge port of the first evaporator, the stirring speed and evaporation temperature of the second evaporator are regulated.

[0060] Assume that the grain size is the threshold range [ε, φ],

[0061] When the grain size of the slurry discharge port of the first evaporator is less than ε, the flow rate and stirring speed of the medium in the circulating temperature control tube of the second evaporator are increased, and the stirring speed of the first evaporator is also increased;

[0062] When the grain size of the slurry discharge port of the first evaporation tank is within the threshold range, the first evaporation tank and the second evaporation tank execute the existing execution parameters;

[0063] When the grain size of the slurry discharge port of the first evaporator is greater than φ, the flow rate and stirring speed of the medium in the circulating temperature control tube of the second evaporator are reduced, and the stirring speed of the first evaporator is also reduced.

[0064] In one embodiment, when the grain size of the first evaporation tank discharge port is less than ε;

[0065] The method to increase the flow rate of the medium in the circulating temperature control tube in the second evaporator is:

[0066] Increase the flow rate of the temperature control tube according to the following formula:

[0067]

[0068] Among them, V 21 is the original flow rate of the second evaporator temperature control tube, V 22 is the speed of the second evaporator temperature control tube after lifting, A is the grain size, and β is a correction constant with a range of [0.9, 1.2];

[0069] The method of increasing the stirring speed in the second evaporation tank is:

[0070] Increase the stirring speed according to the following formula:

[0071]

[0072] Among them, N 21 is the original stirring speed of the second evaporator, N 22 is the stirring speed of the second evaporator after it is increased;

[0073] The specific method of increasing the stirring speed of the first evaporation tank is:

[0074] Increase the stirring speed of the first evaporator according to the following formula:

[0075] N 12 =N 11 β1

[0076] Among them, N 11 is the original stirring speed of the first evaporator, N 12 is the stirring speed of the first evaporator after it is lifted, β1 is the adjustment coefficient with a value range of [1, 2.5], and the specific value is determined by the staff in combination with β.

[0077] Exemplarily, when the grain size of the first evaporator discharge port is greater than φ,

[0078] The method of reducing the flow rate of the medium in the circulating temperature control pipe in the second evaporator is:

[0079] Reduce the flow rate of the temperature control tube according to the following formula:

[0080]

[0081] Among them, V 21 is the original flow rate of the second evaporator temperature control tube, V 22 is the speed of the second evaporator temperature control tube after lifting, A is the grain size, and α is a correction constant with a value range of [0.8, 1];

[0082] The method to reduce the stirring speed of the second evaporator is:

[0083] Reduce the stirring speed according to the following formula:

[0084]

[0085] Among them, N 21 is the original stirring speed of the second evaporator, N 22 is the stirring speed of the second evaporator after it is increased;

[0086] The method of reducing the stirring speed of the first evaporator is:

[0087] Reduce the stirring speed of the first evaporator according to the following formula:

[0088] N 12 =N 11 α1

[0089] Among them, N 11 is the original stirring speed of the first evaporator, N 12 is the stirring speed of the first evaporator after the boost, α1 is the adjustment coefficient with a value range of [0.7, 0.95], and the specific value is determined by the staff in combination with α.

[0090] Through the technology of the above formula, the upstream parameters can be used for the downstream parameters, realizing linkage control while improving the control accuracy. It is no longer a separate ruleless control. Because traditional control is basically implemented based on experience, it can now reduce reliance on experience, be more in line with automated control, and improve stability.

[0091] Exemplarily, the method of adjusting the execution parameters of the third evaporator according to the crystallization parameters of the discharge port of the second evaporator is:

[0092] The method for regulating the evaporation temperature and the amount of washing water in the third evaporator according to the crystal shape of the discharge port of the second evaporator is:

[0093] The crystal shape is divided into spherical and non-spherical, and the threshold of the spherical proportion is set to λ;

[0094] When the spherical proportion is less than λ, the evaporation temperature of the third evaporation tank is increased, and the crystal slurry concentration and sulfate concentration in the third evaporation tank are changed by adjusting the amount of washing water;

[0095] When the spherical occupancy is not less than λ, the second evaporation tank and the third evaporation tank execute the existing execution parameters.

[0096] Exemplarily, a method for determining the flow rate of the third evaporator discharge port according to the crystallization parameters of the third evaporator discharge port is:

[0097] The opening and closing degree of the third evaporator discharge port is controlled by the uniformity of the grain size of the third evaporator discharge port, and the flow rate is controlled by the opening and closing degree of the discharge port.

[0098] The slurry discharge port of the third evaporator is set to be fully open and three-quarters open;

[0099] When the grain size uniformity is not less than the set value, the opening of the third evaporator discharge port is fully open;

[0100] When the uniformity of the grain size is less than the set value, the opening of the discharge port of the third evaporator is three quarters open.

[0101] In one embodiment, an evaporation tank may be added between the three evaporation tanks according to the working conditions and production requirements.

[0102] Through the above method, linkage adjustment of multiple evaporation tanks can be achieved, and the adjustment is based on timely real-time data from the upstream, with a fast response. The grain size and grain size uniformity of the salt processed by the control method of the present invention are relatively controllable, and the crystal shape is also well monitored, so as to produce salt of various qualities.

[0103] In another embodiment, a control system for an edible salt evaporation unit is provided, the control system is used to implement the above control method, the control system comprises:

[0104] The control unit 200 is used to receive and process data and send execution commands;

[0105] an input unit 400, connected to the control unit, and used to input data to the control unit; and

[0106] An execution unit 300, connected to the control unit, and configured to execute an execution command sent by the control unit;

[0107] The input unit includes at least: a molding device installed in each mirror, a temperature sensor and a sensor for measuring the rotation speed of the stirrer;

[0108] The execution unit at least comprises: an agitator, a washing water pump installed on the washing water pipe, and a circulation pump installed on the circulation temperature control pipe.

[0109] In order to better save and access data, the system further comprises a storage unit 500 connected to the control unit, which is used to store data of the control unit; the control unit may be a computer.

[0110] The above control system can realize the automatic control of the above control method, improve the stability of the production line, and make the quality of processed products more stable and guaranteed.

[0111] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for an edible salt evaporation unit, characterized in that: The evaporation unit comprises at least three evaporation tanks connected in series, which are sequentially divided into a first evaporation tank, a second evaporation tank, and a third evaporation tank. Each evaporation tank is provided with a stirrer, a circulating temperature control tube, a sight glass, and a washing water pipe. A mother liquid connecting pipe is connected between adjacent evaporation tanks. The control method comprises: Obtaining parameters of brine in the first evaporation tank, wherein the brine is purified and the parameters of the brine include at least brine volume, brine concentration, and sulfate concentration; The execution parameters of the three evaporation tanks are set according to the brine parameters, and the execution parameters at least include stirring speed, evaporation temperature and washing water volume; wherein the stirring speed is achieved by controlling the stirrer, and the evaporation temperature is achieved by controlling the temperature and pressure of the medium in the circulating temperature control tube. When the temperature and pressure of the medium are determined, the evaporation temperature is further maintained by the flow rate of the medium; the washing water volume is achieved by controlling the water output of the washing water pipe; wherein the stirring speed of the first evaporation tank is greater than that of the second evaporation tank, and the speed of the third evaporation tank is not higher than that of the second evaporation tank; Collecting crystallization parameters at the first evaporation tank discharge port, the second evaporation tank discharge port, and the third evaporation tank discharge port at a fixed time and point, wherein the crystallization parameters at least include grain size, crystal shape, and grain size uniformity; adjusting the execution parameters of the second evaporator according to the crystallization parameters of the slurry discharge port of the first evaporator; adjusting the execution parameters of the third evaporator according to the crystallization parameters of the slurry discharge port of the second evaporator; Determine the flow rate of the third evaporator discharge port according to the crystallization parameters of the third evaporator discharge port; The execution parameters of the second evaporation tank and the third evaporation tank are adjusted and the flow rate of the slurry discharge port of the third evaporation tank is determined synchronously.

2. A control method for an edible salt evaporation unit according to claim 1, characterized in that: The crystallization parameters are obtained by analyzing after photographing with an imaging device installed in a sight glass, and the sight glass is located inside the pulp discharge port of the evaporation tank.

3. A control method for an edible salt evaporation unit according to claim 1, characterized in that: The method for adjusting the execution parameters of the second evaporator according to the crystallization parameters of the slurry discharge port of the first evaporator is as follows: according to the grain size of the slurry discharge port of the first evaporator, the stirring speed and evaporation temperature of the second evaporator are adjusted, and the grain size is set as the threshold range [ε, φ], When the grain size of the slurry discharge port of the first evaporator is less than ε, the flow rate and stirring speed of the medium in the circulating temperature control tube of the second evaporator are increased, and the stirring speed of the first evaporator is also increased; When the grain size of the slurry discharge port of the first evaporation tank is within the threshold range, the first evaporation tank and the second evaporation tank execute the existing execution parameters; When the grain size of the slurry discharge port of the first evaporator is greater than φ, the flow rate and stirring speed of the medium in the circulating temperature control tube of the second evaporator are reduced, and the stirring speed of the first evaporator is also reduced.

4. A control method for an edible salt evaporation unit according to claim 3, characterized in that: When the grain size at the discharge port of the first evaporator is less than ε; The method to increase the flow rate of the medium in the circulating temperature control tube in the second evaporator is: Increase the flow rate of the temperature control tube according to the following formula: Among them, V 21 is the original flow rate of the second evaporator temperature control tube, V 22 is the speed of the second evaporator temperature control tube after lifting, A is the grain size, and β is a correction constant with a range of [0.9, 1.2]; The method of increasing the stirring speed in the second evaporation tank is: Increase the stirring speed according to the following formula: Among them, N 21 is the original stirring speed of the second evaporator, N 22 is the stirring speed of the second evaporator after it is increased; The specific method of increasing the stirring speed of the first evaporation tank is: Increase the stirring speed of the first evaporator according to the following formula: N 12 =N 11 β1 Among them, N 11 is the original stirring speed of the first evaporator, N 12 is the stirring speed of the first evaporator after it is lifted, β1 is the adjustment coefficient with a value range of [1, 2.5], and the specific value is determined by the staff in combination with β.

5. The control method for the edible salt evaporation unit according to claim 3, characterized in that: When the grain size of the first evaporator discharge port is greater than φ, The method of reducing the flow rate of the medium in the circulating temperature control pipe in the second evaporator is: Reduce the flow rate of the temperature control tube according to the following formula: Among them, V 21 is the original flow rate of the second evaporator temperature control tube, V 22 is the speed of the second evaporator temperature control tube after lifting, A is the grain size, and α is a correction constant with a value range of [0.8, 1]; The method to reduce the stirring speed of the second evaporator is: Reduce the stirring speed according to the following formula: Among them, N 21 is the original stirring speed of the second evaporator, N 22 is the stirring speed of the second evaporator after it is increased; The method of reducing the stirring speed of the first evaporator is: Reduce the stirring speed of the first evaporator according to the following formula: N 12 =N 11 α1 Among them, N 11 is the original stirring speed of the first evaporator, N 12 is the stirring speed of the first evaporator after the boost, α1 is the adjustment coefficient with a value range of [0.7, 0.95], and the specific value is determined by the staff in combination with α.

6. The control method for an edible salt evaporation unit according to claim 1, characterized in that: The method for adjusting the execution parameters of the third evaporator according to the crystallization parameters of the discharge port of the second evaporator is: The method for adjusting the evaporation temperature and the amount of washing water in the third evaporator according to the crystal shape of the discharge port of the second evaporator is: The crystal shape is divided into spherical and non-spherical, and the threshold of the spherical proportion is set to λ; When the spherical proportion is less than λ, the evaporation temperature of the third evaporation tank is increased, and the crystal slurry concentration and sulfate concentration in the third evaporation tank are changed by adjusting the amount of washing water; When the spherical occupancy is not less than λ, the second evaporation tank and the third evaporation tank execute the existing execution parameters.

7. The control method for an edible salt evaporation unit according to claim 1, characterized in that: The method for determining the flow rate of the third evaporator discharge port according to the crystallization parameters of the third evaporator discharge port is: The opening and closing degree of the third evaporator discharge port is controlled by the uniformity of the grain size of the third evaporator discharge port, and the flow rate is controlled by the opening and closing degree of the discharge port. The slurry discharge port of the third evaporator is set to be fully open and three-quarters open; When the grain size uniformity is not less than the set value, the opening of the third evaporator discharge port is fully open; when the grain size uniformity is less than the set value, the opening of the third evaporator discharge port is three quarters open.

8. The control method for an edible salt evaporation unit according to claim 1, characterized in that: According to the working conditions and production requirements, evaporation tanks can be added between the three evaporation tanks.

9. A control system for an edible salt evaporation unit, characterized in that: The control system is used to implement the control method according to any one of claims 1 to 8, and the control system includes: A control unit, used to receive and process data and send execution commands; an input unit, connected to the control unit, and used to input data into the control unit; and an execution unit, connected to the control unit, and configured to execute an execution command sent by the control unit; The input unit includes at least: a molding device installed in each mirror, a temperature sensor and a sensor for measuring the rotation speed of the stirrer; The execution unit at least comprises: an agitator, a washing water pump installed on the washing water pipe, and a circulation pump installed on the circulation temperature control pipe.

10. A control system for an edible salt evaporation unit according to claim 9, characterized in that: It also includes a storage unit connected to the control unit and used for storing data of the control unit.

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