CN-121979319-A - Intelligent regulation and control method and related device for dissolved oxygen concentration of indirect cooling circulating water system

CN121979319ACN 121979319 ACN121979319 ACN 121979319ACN-121979319-A

Abstract

The invention belongs to the technical field of indirect cooling system circulating water treatment, and relates to an intelligent regulation and control method and a related device for the concentration of dissolved oxygen in an indirect cooling circulating water system. The method comprises the steps of obtaining unit load and water quality on-line data of a sampling pipe section, determining a dissolved oxygen concentration control target and a pH value control target of the sampling pipe section according to the unit load and the water quality on-line data, obtaining the actual dissolved concentration and the pH value of the sampling pipe section, calculating to obtain the deviation between the dissolved oxygen concentration control target and the actual dissolved oxygen concentration and the deviation between the pH value control target and the actual pH value, and dynamically adjusting the oxygen injection quantity by adopting a fuzzy model predictive control algorithm according to the deviation. The control problem of the dissolved oxygen concentration of the indirect cooling circulating water system under the variable load working condition is effectively solved, and the stability and the reliability of the system are obviously improved.

Inventors

ZHANG HONGBO
Ha Buri
JIANG WEI
ZHAO QING
ZHAO CUNHAI
Hao Hongduo
JIN CHENGJIANG
LI SHAOZHONG
XIAO HAIGANG
GUO YAN
ZHANG YUEFANG
HAN LIMING
ZHOU PENG

Assignees

西安热工研究院有限公司
北方魏家峁煤电有限责任公司

Dates

Publication Date: 20260505
Application Date: 20260127

Claims (10)

1. An intelligent regulation and control method for the concentration of dissolved oxygen in an indirect cooling circulating water system is characterized by comprising the following steps: acquiring water quality on-line data of unit load and sampling pipe sections; determining a dissolved oxygen concentration control target and a pH value control target of the sampling pipe section according to the unit load and the water quality on-line data; Obtaining the actual dissolved concentration and the pH value of the sampling pipe section, and calculating to obtain the deviation between the dissolved oxygen concentration control target and the actual dissolved oxygen concentration and the deviation between the pH value control target and the actual pH value; And dynamically adjusting the oxygen injection quantity by adopting a fuzzy model predictive control algorithm according to the deviation.
2. The intelligent regulation and control method for the dissolved oxygen concentration of the indirect cooling circulating water system according to claim 1 is characterized in that the online water quality data comprise iron content, pH value and corrosion inhibitor adding state, and the unit load is real-time output power of a generator unit matched with the indirect cooling circulating water system.
3. The intelligent control method for the concentration of dissolved oxygen in an indirect cooling circulating water system according to claim 1, wherein the target for controlling the concentration of dissolved oxygen is set to be 0.3-1.0 mg/L.
4. The intelligent control method for the concentration of dissolved oxygen in an indirect cooling circulating water system according to claim 1, wherein the fuzzy model predictive control algorithm comprises the steps of: the upper layer carries out model predictive control, namely rolling and optimizing the oxygen supply in the future time domain based on a dissolved oxygen balance equation; The lower layer carries out fuzzy control and carries out real-time correction on the oxygen supply output by the upper layer.
5. The intelligent regulation and control method for the concentration of dissolved oxygen in an indirect cooling circulating water system according to claim 4, wherein the equation of the concentration of dissolved oxygen is: Wherein, the The instantaneous change rate of the dissolved oxygen concentration of the ith section of pipeline; The dissolved oxygen concentration at the moment t of the ith section of pipeline; is the volume of the ith section of pipeline; oxygen injection flow is at time t; Is an oxygen dissolution efficiency factor; Is the circulating water flow; The dissolved oxygen concentration at the time t of the i-1 th section pipeline; Is the iron corrosion rate constant of the i-th section pipeline.
6. The intelligent control method for the concentration of dissolved oxygen in the indirect cooling circulating water system according to claim 5, wherein the specific method for optimizing the future time-domain oxygen supply by rolling is as follows: Based on the dissolved oxygen concentration at the moment t of the ith pipeline section and the dissolved oxygen concentration at the moment t of the ith-1 pipeline section, predicting the dissolved oxygen concentration of the P steps in the future through a dissolved oxygen equilibrium equation, wherein the calculation formula is as follows: Wherein, the The predicted value of the dissolved oxygen concentration after the kth step is the t moment; the oxygen supply amount of the kth-1 step planned at the moment t is calculated; And (3) rolling optimization, and solving the following quadratic programming optimization problem in each sampling period t: Wherein, the Defining a weighted sum of system performance indexes as an objective function, wherein M is a control time domain length (M is less than or equal to P, and P is a prediction time domain), and constraint conditions comprise a system dynamics equation, an input constraint and a state constraint; For sampling period When the system is the first A number of control variables; To the last moment in the control time domain M A number of control variables; from optimizing solution sequences In which the first-step control amount is applied ; At the next sampling period And repeating the optimization and execution processes to realize closed-loop rolling optimization control.
7. The intelligent regulation and control method for the dissolved oxygen concentration of the indirect cooling circulating water system according to claim 6, wherein the specific method for correcting the oxygen supply output by the upper layer in real time is as follows: calculating a deviation value at the time t according to the actual dissolved oxygen concentration and the predicted value, wherein a calculation formula is as follows: Wherein, the The deviation value is t time; A predicted value of the dissolved oxygen concentration at the time t is the time t-1; the calculation formula of the deviation change rate is as follows: Wherein, the The deviation change rate at the time t; The deviation value is t-1; Inputting the deviation value at the time t and the deviation change rate at the time t into a fuzzy controller for fuzzy reasoning, outputting an oxygen supply correction coefficient, and adjusting model prediction control output through a fuzzy rule; The fuzzy rule is as follows: When (when) When >0, generating a correction instruction for reducing the oxygen supply amount; When (when) <0 And When >0, a correction command for increasing the oxygen supply amount is generated.
8. An intelligent regulation and control system for dissolved oxygen concentration of an indirect cooling circulating water system is characterized by comprising: the water quality data acquisition module is used for acquiring water quality online data of the unit load and the sampling pipe section; The control target generation module is used for determining a dissolved oxygen concentration control target and a pH value control target of the sampling pipe section according to the unit load and the water quality on-line data; The deviation calculation module is used for obtaining the actual dissolved concentration and the pH value of the sampling pipe section, and calculating to obtain the deviation between the dissolved oxygen concentration control target and the actual dissolved oxygen concentration and the deviation between the pH value control target and the actual pH value; And the intelligent adjusting module dynamically adjusts the oxygen injection quantity by adopting a fuzzy model predictive control algorithm according to the deviation.
9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 1-7 when the computer program is executed.
10. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method according to any one of claims 1-7.

Description

Intelligent regulation and control method and related device for dissolved oxygen concentration of indirect cooling circulating water system Technical Field The invention belongs to the technical field of indirect cooling system circulating water treatment, and relates to an intelligent regulation and control method and a related device for the concentration of dissolved oxygen in an indirect cooling circulating water system. Background The SCAL indirect air cooling unit gradually becomes a main engine type of thermal power due to the water-saving characteristic. The indirect air cooling system of the type uses about 10000 tons of desalted water as circulating water, and the pH, conductivity, iron content, turbidity and other indexes of the circulating water are often increased abnormally because the buffer capacity of the desalted water is small and no water purification device exists in the system. The increase in pH aggravates corrosion of aluminum radiators, and the increase in conductivity indicates an increase in impurity ion concentration in the system, wherein aggressive ions (Cl - and SO 42-) accelerate the corrosion rate of carbon steel, and the increase in iron content and turbidity aggravate the flush corrosion suffered by the aluminum pipe orifice. The Chinese patent with publication number of CN111977758A discloses an intelligent purification system for circulating water of an indirect air cooling system and a use method thereof, which are used for controlling parameters such as pH, conductivity, turbidity and the like of the circulating water within a target value range, but in actual operation, certain problems still exist, such as the phenomenon that the pH is abnormally increased in the unit operation process even if the conductivity of the circulating water is controlled below 2 mu S/cm, and the phenomenon is particularly obvious when the load of a peak shaver unit is frequently changed. At this time, the operation cost of adjusting the pH value by continuously putting the mixed bed is high, and after corrosion inhibitor is added into circulating water in part of the thermal power plant, the corrosion inhibitor can be invalid due to the continuously putting the mixed bed. Studies have shown that the cause of abnormal rise in the pH of the indirect cooling circulating water is related to the concentration of dissolved oxygen in the circulating water. In a pure water environment, the anodic and cathodic reactions of carbon steel and pure aluminum are as follows: Anode reaction: Fe→Fe2++2e- Al→Al3++3e- Cathode reaction: O2+2H2O+4e-→4OH- When the dissolved oxygen in water is sufficient, carbon steel corrosion mainly occurs as the following secondary reactions: 2Fe2++2OH-+O2+2H2O→2Fe(OH)3↓ The pure aluminum corrosion reaction also eventually produces Al (OH) 3, calculated from the solubility product, at a dissolution equilibrium in a pure water environment, the pH values of Fe (OH) 3 and Al (OH) 3 are 4.48 and 5.90, respectively, so that in an environment with a pH >7.0, the secondary reaction forms Fe (OH) 3 and Al (OH) 3 precipitates, consuming OH - produced by the corrosion reaction, and the material corrosion does not substantially cause a change in pure water pH. When the concentration of dissolved oxygen in water is low, carbon steel corrosion mainly occurs as the following secondary reactions: Fe2++2OH-→Fe(OH)2↓ There is a large amount of Fe (OH) 2 in water, and the pH of Fe (OH) 2 is 8.66 when in dissolution equilibrium in pure water environment, calculated as solubility product. Therefore, when the content of dissolved oxygen in pure water is low, the concentration of OH - in water in a dissolution equilibrium state is high, which causes the rise of pH value, and in addition, in the process of peak regulation and load change, fe 2+、OH- is in a supersaturated state due to Flow Acceleration Corrosion (FAC), temperature change and other reasons, and the pH value of the indirect cooling circulating water may exceed 8.66. Because the indirect cooling circulating water system is a closed operation system, the main parts communicated with the atmosphere are an expansion water tank top, a ground water tank top and an emptying pipeline of each sector, the parts are not basically involved in circulation during normal operation, the dissolved oxygen in the normal water exchange water is almost negligible for a 10000 ton system, and the concentration of the dissolved oxygen in the circulating water can be always less than 10 mug/L during long-term operation. The dissolved oxygen concentration in the circulating water can be increased by filling oxygen, but because the dissolved oxygen is a depolarizer, carbon steel corrosion can be promoted, and the problem of material corrosion of an indirect cooling circulating water system can be aggravated by excessive filling of oxygen. Disclosure of Invention The invention provides an intelligent regulation and control method for the concentration of dissol