阅读说明：本技术 一种化盐桶液位优化控制方法 (Optimized control method for liquid level of salt melting barrel ) 是由 吕伟军 王风根 于现军 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种在连续上盐或者非连续上盐的化盐工序中,利用顶点曲线法代替实际液位曲线,通过搭建数学模型,利用预测模型、自适应模型等先控模块来优化系统结构,降低系统的灵敏度,协调参数,自动控制化盐桶液位的方法,实现了化盐桶液位的自动控制,保持了液位的稳定,避免了液位过高或过低的问题,从而稳定了盐水浓度,同时还极大的降低了工人的劳动强度。(The invention discloses a method for optimizing a system structure, reducing the sensitivity of the system, coordinating parameters and automatically controlling the liquid level of a salt dissolving barrel by using a vertex curve method to replace an actual liquid level curve and using a prediction model, an adaptive model and other pre-control modules in the salt dissolving process of continuous salt adding or discontinuous salt adding, which realizes the automatic control of the liquid level of the salt dissolving barrel, keeps the stability of the liquid level, avoids the problem of overhigh or overlow liquid level, stabilizes the salt water concentration and greatly reduces the labor intensity of workers.)

1. A method for optimizing and controlling the liquid level of a salt melting barrel comprises the steps of (1) establishing a vertex curve; (2) calculating the water inflow; (3) optimizing and controlling; (4) a liquid level controller; the method is characterized in that: the vertex curve method is provided for replacing an actual liquid level curve, the system structure is optimized by building a mathematical model and utilizing a prediction model, a self-adaptive model and other pre-control modules, the sensitivity of the system is reduced, parameters are coordinated, the liquid level is stable, and therefore the brine concentration is stabilized.

2. The vertex curve of claim 1, wherein for a variable of the liquid level, each scanning cycle of the system is compared with a previous cycle value, if the current cycle is greater than the previous cycle value, the previous cycle value is recorded and compared with a next cycle value, if the current cycle is less than the previous cycle value, the previous cycle value is recorded and compared with the next cycle value, finally, the output highest value is always kept, and under the condition that the highest values are kept unchanged for a plurality of cycles, the highest value of the current previous salt cycle is considered as the current value, when the next previous salt cycle starts, the highest value of the previous cycle is delayed for the corresponding previous salt cycle until the highest value of the current cycle appears, so that the obtained curve is a continuous available liquid level vertex curve.

3. Calculation of water intake according to claim 1: the water inflow consists of the following 3 parts, wherein the first part is the water inflow obtained by the product of the water outflow and a corresponding coefficient; the second part is a divisor of water quantity and time corresponding to the deviation between the set value of the liquid level and the actual value; the third part is the allowed deviation of the liquid level set point from the actual value as a dead band.

4. The optimization control of claim 1: by building a mathematical model, a system structure is optimized by using a prediction model, a self-adaptive model and other pre-control modules, the sensitivity of the system is reduced, parameters are coordinated, the change of the liquid level has a specified upper limit and a specified lower limit, and the risk of overflow or drainage is reduced; likewise, the flow into and out of the system cannot exceed the range of fluctuations that it can tolerate.

5. The salt tank level controller of claim 1: the system comprises a controlled object salt dissolving barrel, a controlled variable salt dissolving barrel liquid level, a manipulated variable salt dissolving barrel water flow and an actuating mechanism fresh salt water pump;

the basic principle formula of the salt dissolving barrel liquid level controller is as follows:

and (3) taking the finally calculated flow value of the fresh salt water as a real-time manipulated variable, sending a control signal of the salt melting barrel controller to an execution mechanism, and changing the frequency of the frequency converter to adjust the flow value of the fresh salt water to track and calculate the value in real time.

Technical Field

The invention provides a salt dissolving barrel liquid level optimization control method which utilizes a vertex curve method to replace an actual liquid level curve in a salt dissolving process of continuous salt adding or discontinuous salt adding, thereby stabilizing the liquid level and the brine concentration.

Background

The main equipment of the salt solution systematization salt process includes salt dissolving tank and salt dissolving bucket, salt and water are all added into the salt dissolving tank, salt solution after mixing overflows to the salt dissolving bucket by the salt dissolving tank, because the salt dissolving tank adds the unable access automatic control of salt part, consequently, add salt quantity uncontrollable, when adding salt at every turn, salt dissolving bucket liquid level can rise suddenly, the in-process of salt dissolving, the liquid level drops back to the level that begins gradually again, the curve of every salt adding cycle liquid level is exactly a sawtooth wave, what salt dissolving bucket liquid level was added through the salt dissolving tank water yield and is controlled, therefore the liquid level of stabilizing the salt bucket has just also stabilized the concentration of salt dissolving bucket salt water, also just stabilized the later chlor-alkali process.

At present, the water inlet pump is operated manually according to experience to achieve the purpose of controlling the liquid level, and manual operation has the problems of untimely adjustment, poor consistency, high labor intensity and the like, so that a control method capable of fully automatically optimizing and controlling the liquid level of the salt barrel is required to be introduced.

In conclusion, the existing salt dissolving bucket liquid level control method cannot meet the current development requirements, and in order to stabilize the salt dissolving bucket liquid level, the method for controlling the salt dissolving bucket liquid level by the vertex curve method is invented.

Disclosure of Invention

In order to overcome the fluctuation of the liquid level of the salt dissolving barrel, a first control module is still selected to control the liquid level, but the fluctuation of a liquid level measured value under manual operation is too large to be input as the first control module, and the problem to be solved is to find a parameter to replace an actual liquid level value to be used as an input value of the first control module.

In order to solve the problems, the invention provides a vertex curve method to replace an actual liquid level curve, and solves the input problem of a prior control module; in the actual operation process, after salt feeding is finished each time, the liquid level of the salt dissolving barrel reaches a high point position called a vertex, the vertexes are connected into a line called a vertex curve, the curve is used as a measured value input (PV value) of the advanced control module, the actual liquid level expected value is used as a liquid level set value (SP value), and automatic adjustment is carried out by the advanced control module (see attached figure 1).

The technical scheme is also suitable for the working condition that salt adding is discontinuous (see the attached figure 2).

Drawings

FIG. 1 is a diagram showing the relationship between the liquid level of a continuous salt tank and the water inlet flow.

FIG. 2 is a diagram showing the relationship between the liquid level of the discontinuous salinization salt barrel and the inflow water flow.

FIG. 3 shows a salt tank level controller.

Detailed Description

The technical scheme comprises the following aspects: (1) establishing a vertex curve; (2) calculating the water inflow; (3) optimizing and controlling; (4) a liquid level controller.

The above (1) creation of vertex curve: comparing each scanning period of the system with the value of the previous period once for the variable of the liquid level, recording the value of the previous period and comparing the recorded value with the value of the next period if the current period is larger than the value of the previous period, recording the value of the previous period and comparing the recorded value with the value of the next period if the current period is smaller than the value of the previous period, and finally always keeping outputting the highest value, and under the condition that the highest value keeps a plurality of periods unchanged, considering that the highest value of the current salting period is the current value, and delaying the highest value of the previous period until the highest value of the current period appears when the next salting period starts, so that the obtained curve is a continuous available liquid level vertex curve.

The water inflow calculation in the step (2): the water inflow consists of the following 3 parts, wherein the first part is the water inflow obtained by the product of the water outflow and a corresponding coefficient; the second part is a divisor of water quantity and time corresponding to the deviation between the set value of the liquid level and the actual value; the third part is the allowed deviation of the liquid level set point from the actual value as a dead band.

The above (3) optimization control: by building a mathematical model, a system structure is optimized by using a prediction model, a self-adaptive model and other pre-control modules, the sensitivity of the system is reduced, parameters are coordinated, the change of the liquid level has a specified upper limit and a specified lower limit, and the risk of overflow or drainage is reduced; likewise, the flow into and out of the system cannot exceed the range of fluctuations that it can tolerate.

The salt melting barrel liquid level controller in the step (4): the controlled object salt dissolving barrel, the controlled variable salt dissolving barrel liquid level, the manipulated variable salt dissolving barrel water flow and the actuating mechanism fresh salt water pump.

The basic principle formula of the salt dissolving barrel liquid level controller is as follows:

(see FIG. 3);

wherein

And (3) taking the finally calculated flow value of the fresh salt water as a real-time manipulated variable, sending a control signal of the salt melting barrel controller to an execution mechanism, and changing the frequency of the frequency converter to adjust the flow value of the fresh salt water to track and calculate the value in real time.

The invention has the advantages that: the problem of change salt bucket liquid level automatic control is solved, stabilized the liquid level, just also stabilized salt water concentration, improved the product quality of whole process, reduced workman's intensity of labour simultaneously.