CN113998767A

CN113998767A - Electrocatalysis pH value processing system based on automatic control

Info

Publication number: CN113998767A
Application number: CN202111259826.6A
Authority: CN
Inventors: 关伟; 谢杨俊; 陈泉洲
Original assignee: Chongqing University of Arts and Sciences
Current assignee: Chongqing University of Arts and Sciences
Priority date: 2021-10-28
Filing date: 2021-10-28
Publication date: 2022-02-01
Anticipated expiration: 2041-10-28
Also published as: CN113998767B

Abstract

The invention provides an electrocatalysis pH value processing system based on automatic control, which comprises a pH sensor (2) for detecting the pH value of electroplating waste liquid in real time, a pH regulator (3) for carrying out dropping addition of composite alkali according to the instruction of a controller (4) and adopting the automatic composite alkali adder, and the controller (4) for receiving the signal of the pH sensor (2) in real time, calculating in real time and outputting the instruction to the pH regulator (3); the controller (4) obtains PID control feedback quantity and control system regulating quantity through error variable calculation, then obtains pH value regulating quantity through PID control feedback quantity and control system regulating quantity, and further regulates the error feedback quantity through introducing an error second derivative and matching with an error value and an error first derivative, so that oscillation is slowed down, the automatic system is further stably regulated, and the pH value in the electrocatalysis process is stabilized at a target value.

Description

Electrocatalysis pH value processing system based on automatic control

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to an electrocatalysis pH value treatment system based on automatic control.

Background

Industrial pollution refers to the pollution of waste gases, waste water and solid emissions formed during industrial production processes to the environment; industrial pollution not only destroys the living environment of organisms, but also directly harms human health. In industrial pollution, industrial wastewater is a common one, and the most main pollution source in the industrial wastewater is electroplating wastewater; the sources of the electroplating wastewater are generally plating part cleaning water, waste electroplating solution, other wastewater (such as washing workshop floor, washing polar plate cleaning water, ventilating equipment condensed water, various bath solutions and drainage caused by leakage of plating bath or improper operation management), equipment cooling water and the like; the electroplating wastewater has complex water quality and difficultly-controlled components, and pollutants of the electroplating wastewater comprise heavy metals (nickel, chromium, copper, zinc and the like) and complexing agents, wherein the pollutants comprise heavy metal complexes, heavy metal ions, organic matters and the like, and some of the heavy metal complexes, the heavy metal ions, the organic matters and the like belong to carcinogenic, teratogenic and mutagenic virulent substances; at present, the concentration of pollutants in the electroplating wastewater composed of the substances is up to thousands of milligrams per liter, and far exceeds the discharge standard of the electroplating wastewater.

In the prior art, the treatment method for the electroplating wastewater is more, and mainly comprises an air floatation method, an ion exchange method, an electrocatalysis method and an extraction method. The electrocatalysis method mainly comprises the steps that active groups such as superoxide radical, hydrogen peroxide and hydroxyl radical are generated under the action of an electrode and a catalytic material and act on organic matters in water, and the organic matters undergo a rapid oxidation reaction and a radical chain reaction under the action of the active groups, so that the aim of removing the organic matters is fulfilled; the electrocatalysis method mainly adopts electrons in the treatment process, does not need to add an oxidant, does not produce secondary pollution, has mild reaction conditions, high energy efficiency, has the functions of air floatation, flocculation and sterilization at intervals, has simple reaction device, flexible process, strong controllability and easy automation, and is one of the sewage purification methods which are widely concerned by the industries in recent years. However, in the electrocatalytic treatment process of the electroplating wastewater, various parameters are as follows: such as the current, the pH value of the waste liquid, electrode materials, the distance between polar plates, the initial concentration of pollutants and the like can influence the reaction time and efficiency of the electrocatalytic waste liquid, wherein in the waste liquid treatment process, the range of the pH value greatly influences the treatment efficiency and the operation cost, so that a control system is usually adopted to monitor and adjust the pH value in real time in the prior art; for example: chinese patent CN210367090U, the name "a photovoltaic driven electrocatalytic degradation ignition effluent treatment plant", it adopts the pH meter, pH controller etc. carries out the pH value in the electrolytic bath and adjusts, thereby make the degradation of waste water reach the optimal condition, but the pH governing system of this patent can only adjust between 2 ~ 5 in the electrolytic bath, its fluctuation range is big (pH value fluctuates in the interval of scope being 3), lead to the treatment effeciency of electrocatalytic process low, simultaneously because the pH value fluctuation range of electrolytic bath is big, can cause whole reaction process unstable, the condition that the electrocatalytic process is suddenly and suddenly slow. Since the pH value dynamically changes with the reaction time (i.e., the longer the operation time and the smaller the pH value during the wastewater treatment process), which involves various factors such as the addition time of the regulator, the amount of the regulator added, and the amount of pH change during the wastewater treatment process, the cost involved increases (the smaller the interval and the higher the control cost) if the pH value is controlled to be kept in a small range, and the treatment process is complicated and the fluctuation of the control increases (i.e., the smaller the interval kept, the lower the stability during the control process); therefore, how to keep and stabilize the pH value in a small range is one of the problems in the prior art of electrocatalytic electroplating wastewater treatment.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present invention is to provide an electrocatalysis pH processing system based on automatic control, which can effectively stabilize the pH value in the electrocatalysis process at a target value, and at the same time, the system has small oscillation, high stability and high automation degree.

The purpose of the invention is realized by the following technical scheme:

an electrocatalysis pH value processing system based on automatic control, which is characterized in that: the method comprises the following steps:

the pH sensor is used for detecting the pH value of the electroplating waste liquid in real time;

the pH regulator adopts a composite alkali automatic adder and adds the composite alkali in a dropping way according to the instruction of the controller;

the controller is used for receiving the pH value fed back by the pH sensor in real time, calculating the pH value regulating quantity according to the feedback value and then outputting an instruction to the pH regulator;

the controller is respectively electrically connected with the pH sensor and the pH regulator;

the step of calculating the pH value adjustment amount by the controller is specifically as follows:

firstly, comparing a difference value between a measured value fed back by a pH sensor and a target value to obtain an error variable e (t);

and then calculating to obtain PID control feedback quantity through an error variable e (t):

wherein p (t) is PID control feedback quantity; k_p、K_i、K_dThe coefficient values are respectively proportional coefficient, integral coefficient and differential coefficient, and the coefficient values are obtained according to the setting method of the PID control module;

in the electroplating wastewater treatment process, in order to ensure that the pH value fluctuation range is in the optimal range, the control system regulating quantity f (t) is calculated through an error variable e (t);

wherein sign (x) is a function symbol, and when x > 0, sign (x) is 1; when x < 0, sign (x) is-1;

finally, the PID controls the feedback quantity p (t) and the control system regulating quantity f (t) to obtain a pH value regulating quantity mu (t):

μ(t)＝p(t)·[1+0.5f(t)]。

for further optimization, the compound alkali is a mixture of sodium carbonate and sodium hydroxide with the mass ratio of 1: 1.

Preferably, the target value is between 2.7 and 2.9.

For further optimization, the controller comprises a comparison module, a calculation module, a PID control module, an input module, an output module and a power supply module.

For further optimization, the controller comprises a display module and a display screen, and is used for displaying the calculated amount of the compound alkali needing to be added dropwise and the current pH value detected by the pH sensor.

Considering that a waste liquid treatment pool is enlarged, a pH regulator is added with mixed alkali to regulate the pH value, a certain time difference exists, so that the pH value of a local area is too high and the pH value of the local area is too low, meanwhile, the distance from the pH regulator to an electrode is not passed in the electrocatalysis action, and the content of each substance in the waste water has inconsistency of local high and local low (the diffusion speed of a molecular substance in water is related to temperature, concentration difference and the like); thereby affecting the efficiency of the electro-catalytic treatment of the waste liquid and failing to obtain the optimal operation cost.

Further optimized, the electrocatalysis pH value processing system also comprises a spoiler, and the spoiler is reasonably arranged in the electrocatalysis cell according to the position of the electrode plate.

Preferably, the turbulence generator adopts a turbulence submersible pump and is used for forming convection in the electro-catalytic cell and accelerating the exchange speed of substances in water, so that the substances in water are prevented from forming distribution with local high and local low.

Preferably, the pH regulator is arranged near an electrode plate of the electro-catalysis cell, and the pH sensor is arranged between the pH regulator and the electrode plate.

The invention has the following technical effects:

the invention can adjust the control variable to a stable value well by introducing a PID control system to comprehensively consider the change conditions of the current error, the past error and the future error, thereby ensuring that the pH value is kept in a target value (namely, within the range of 2.7-2.9); meanwhile, the error feedback quantity is further adjusted by introducing the control system adjustment quantity, namely by introducing the second-order error derivative (namely judging whether the process of error expansion or reduction is acceleration or deceleration) and matching the error value and the first-order error derivative (namely whether the error is expansion or reduction), so that the oscillation is slowed down, and the whole automatic system is further stably adjusted.

The system can effectively keep the pH value in the electrocatalysis process within the range of 2.7-2.9 (the range interval of the pH value is 0.2 and is far smaller than the range interval of the pH value of 3 in the prior art; the area section of the invention is reduced to 60 times of the prior art), and meanwhile, the system keeps the pH value within the range of a small interval and has small vibration, high stability (namely the pH value of the electroplating wastewater in the electrocatalysis process is controlled to always keep the fluctuation within the small range of 2.7-2.9) through PID control and second derivative control, and the degree of automation is high; in addition, the invention only adopts the pH sensor, the pH regulator and the controller to realize the purposes of keeping the pH value within a small range of 0.2, having small fluctuation and small vibration, has simple structure (no need of adding other auxiliary equipment), easy operation of process steps (automatic identification and operation, no need of adding other process steps) and low cost, and can greatly improve the treatment efficiency of the electroplating waste liquid treated by the electro-catalysis method, thereby reducing the operation cost of the electro-catalysis process.

Drawings

FIG. 1 is a schematic diagram of the overall structure of an electrocatalytic waste liquid pH value treatment system in the embodiment of the invention.

Wherein, 1, an electro-catalysis cell; 11. a power source; 12. an anode electrode plate; 13. a cathode electrode plate; 14. a water inlet; 15. a photocatalyst addition port; 16. a water outlet; 2. a pH sensor; 3. a pH adjuster; 4. a controller; 5. a spoiler.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example (b):

as shown in figure 1, an electrocatalytic pH value treatment system based on automatic control is characterized in that: the method comprises the following steps:

the pH sensor 2 is used for detecting the pH value of the electroplating waste liquid in real time;

the controller 4 receives the pH value fed back by the pH sensor 2 in real time through the input module, calculates the pH value adjustment amount according to the feedback value, and outputs an instruction to the pH regulator 3 through the output module; the controller 4 comprises a comparison module, a calculation module, a PID control module, an input module, an output module and a power supply module; the controller 4 further comprises a display module and a display screen, and is used for displaying the calculated amount of the compound alkali needing to be dripped and the current pH value detected by the pH sensor 2;

a pH regulator 3 which adopts a composite alkali automatic adder and adds the composite alkali by dropping according to the instruction of the controller 4;

the controller 4 is electrically connected with the pH sensor 2 and the pH regulator 3 respectively.

The steps of the controller 4 for calculating the pH value adjustment amount are specifically as follows:

firstly, the controller 4 obtains the current real-time collected pH value fed back by the pH sensor 2 through an input module, then compares the difference value between the measured value fed back by the pH sensor 2 and the target value (namely the value to be kept for the pH value, which is 2.7-2.9) through a comparison module, and obtains an error variable e (t) through a calculation module;

and then, calculating by using a calculation module and a PID control module through an error variable e (t) to obtain a PID control feedback quantity:

in the electroplating wastewater treatment process, in order to ensure that the pH value fluctuation range is in the optimal range, the error variable e (t) is used for calculating by using a calculation module and a PID control module to obtain the control system regulating quantity f (t);

and finally, utilizing a calculation module to control the feedback quantity p (t) and the control system regulating quantity f (t) through PID to obtain a pH value regulating quantity mu (t):

μ(t)＝p(t)·[1+0.5f(t)]。

wherein the compound alkali is a mixture of sodium carbonate and sodium hydroxide with the mass ratio of 1: 1.

Considering that the waste liquid treatment pool is enlarged, the pH value of the pH regulator 3 is adjusted by adding mixed alkali, so that the pH value of a local area is too high and the pH value of the local area is too low, and meanwhile, in the electrocatalysis action, the distance from the pH regulator to an electrode is not passed, and the content of each substance in the waste water has inconsistency of local high and local low (the diffusion speed of a molecular substance in water is related to temperature, concentration difference and the like); thereby affecting the efficiency of the electro-catalytic treatment of the waste liquid and failing to obtain the optimal operation cost.

The electrocatalytic pH treatment system further comprises a turbulence generator 5, wherein the turbulence generator 5 is reasonably arranged in the electrocatalytic cell 1 according to the positions of the electrode plates (namely, the anode electrode plate 12 and the cathode electrode plate 13) (the optimal arrangement mode is selected according to the conventional arrangement mode in the field and the arrangement mode for achieving the purpose of the invention, which is the conventional technology in the field, so that the invention is not discussed more). Preferably, the turbulence generator 5 is a turbulence submersible pump, and is used for forming convection in the electro-catalytic cell 1 and accelerating the exchange speed of substances in water, so that the substances in water are prevented from forming local high and low distribution.

The electro-catalysis cell 1 comprises a power supply 11, an anode electrode plate 12, a cathode electrode plate 13, a water inlet 14, a photoelectric catalyst adding port 15 and a water outlet 16; the anode electrode plate 12 and the cathode electrode plate 13 are respectively located inside the electro-catalytic cell 1, one end of each of the anode electrode plate and the cathode electrode plate is electrically connected to the power supply 11, the water inlet 14, the photocatalyst adding port 15 and the water outlet 16 are respectively arranged on the side wall of the electro-catalytic cell 1, the water inlet 14 is located at the uppermost end, and the water outlet 16 is located at the lowermost end.

The pH adjuster 3 is installed near an electrode plate (one or more of an anode electrode plate 12 or a cathode electrode plate 13, and the installation of a plurality of pH adjusters 2 can ensure uniform adjustment of the whole) of the electro-catalytic cell 1, and the pH sensor 2 is installed between the pH adjuster 3 and the electrode plate.

The foregoing describes the general principles of the present disclosure in conjunction with specific embodiments, however, it is noted that the advantages, effects, etc. mentioned in the present disclosure are merely examples and are not limiting, and they should not be considered essential to the various embodiments of the present disclosure. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the disclosure is not intended to be limited to the specific details so described.

The block diagrams of devices, apparatuses, systems referred to in this disclosure are only given as illustrative examples and are not intended to require or imply that the connections, arrangements, configurations, etc. must be made in the manner shown in the block diagrams. These devices, apparatuses, devices, systems may be connected, arranged, configured in any manner, as will be appreciated by those skilled in the art. Words such as "including," "comprising," "having," and the like are open-ended words that mean "including, but not limited to," and are used interchangeably therewith. The words "or" and "as used herein mean, and are used interchangeably with, the word" and/or, "unless the context clearly dictates otherwise. The word "such as" is used herein to mean, and is used interchangeably with, the phrase "such as but not limited to".

Also, as used herein, the use of "or" in a list of items beginning with "at least one" indicates a separate list, e.g., "A, B or at least one of C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not mean that the described example is preferred or better than other examples.

The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit embodiments of the disclosure to the form disclosed herein. While a number of example aspects and embodiments have been discussed above, those of skill in the art will recognize certain variations, modifications, alterations, additions and combinations thereof.

Claims

1. An electrocatalysis pH value processing system based on automatic control, which is characterized in that: the method comprises the following steps:

the pH sensor (2) is used for detecting the pH value of the electroplating waste liquid in real time;

a pH regulator (3) which adopts an automatic complex alkali adder and adds complex alkali in a dropping way according to the instruction of the controller (1);

the controller (1) is used for receiving the pH value fed back by the pH sensor (2) in real time, calculating the pH value regulating quantity according to the feedback value and then outputting an instruction to the pH regulator (3);

the controller (1) is respectively electrically connected with the pH sensor (2) and the pH regulator (3);

the controller (1) calculates the pH value adjustment amount specifically comprises the following steps:

μ(t)＝p(t)·[1+0.5f(t)]。

2. the electrocatalytic pH treatment system based on automated control as set forth in claim 1, wherein: the compound alkali is a mixture of sodium carbonate and sodium hydroxide with the mass ratio of 1: 1.

3. An electro-catalytic pH treatment system based on automated control according to any of claims 1 or 2, characterized in that: the electrocatalysis pH value treatment system also comprises a spoiler (5), wherein the spoiler (5) is reasonably arranged in the electrocatalysis tank (1) according to the position of the electrode plate.

4. An electro-catalytic pH treatment system based on automated control according to any of claims 1-3, characterized in that: the pH regulator (3) is arranged near an electrode plate of the electro-catalysis cell (1), and the pH sensor (2) is arranged between the pH regulator (3) and the electrode plate.