CN100545105C - Automatic Control Method of Ozone Treatment Cooling Circulating Water System - Google Patents

Abstract

The invention discloses an automatic control method for an ozone treatment cooling circulating water system. By detecting the dirt thermal resistance, corrosion rate and microbial index of the circulating water in the cooling circulating water system, and comparing it with a preset multi-parameter database, it can be judged The state of circulating water is prone to corrosion or fouling, so as to dynamically implement the automatic operation instructions of the system. Among them, according to the previous judgment of the state of the water, the discharge of the cooling circulating water and the operation of the pump valve of the supplementary water are commanded. Furthermore, according to the previous judgment on the state of water and the discharge and replenishment of water, the amount of ozone generation can be adjusted in real time. The invention can realize the automation of water quality detection and control, make the water quality of the circulating water fully meet the standard, and increase the cycle times of the treated water.

Description

Automatic Control Method of Ozone Treatment Cooling Circulating Water System

technical field

The invention relates to an automatic water treatment method, in particular to an automatic control method for an ozone treatment cooling circulating water system.

Background technique

Scaling and corrosion are the most common problems in heat exchange equipment systems using circulating cooling water, which will endanger the operation of the equipment. The open cooling tower continuously evaporates water to take away heat during the working process, which not only concentrates many substances in the water, but also continuously brings pollutants, dust, microorganisms, etc. in the atmosphere into the water. If the water quality of the circulating cooling water cannot be controlled, It will soon reduce the working efficiency of heat exchange equipment (various types of refrigerators, air compressors, etc.), blockage of pipelines, greatly increase energy consumption, cause corrosion of equipment, shorten service life, and cause great economic losses. Simultaneously because suitable water temperature, grow a large amount of bacteria, especially produce pathogenic bacteria (as legionella pneumophila) and cause very big threat to public health.

At present, chemical agents and physical methods are usually used to alleviate the above problems of circulating cooling water. The chemical reagent method uses many different reagents to complex with ions in water to alleviate scaling, adjust pH to prevent corrosion, and use fungicides to sterilize and sterilize. Because these agents affect each other, the scaling tendency and corrosion tendency of water are contradictory, that is, Water that tends to scale is generally not prone to corrosion, and vice versa, so adjusting scaling and corrosion tendencies separately is difficult to have both regulatory effects. Moreover, the composition of cooling water is changing at any time, and it is constantly changing with the change of working conditions, climate, and composition of supplementary water. The regular dosing adopted by the chemical reagent method actually corrects the scaling or corrosion tendency in the water after a period of time (such as once a week or once a month). Furthermore, the chemical treatment method actually controls the conductance of the circulating cooling water through discharge, and discharge is carried out when the conductance is increased to a certain extent. Therefore, when the conductance of water is high, it is very difficult to use the medicine method. In addition, the medicament method cannot effectively sterilize bacteria, and may cause drug resistance and become invalid, so it needs to be replaced in time. The pharmaceutical method uses a large amount of substances containing phosphorus, zinc, chlorine, and nitrogen. Even if the concentration in the water reaches the standard when it is discharged, from the perspective of the total amount of pollution control requirements, the discharge of tons of chemicals over the years is obviously a non-negligible contribution to the environmental water body. harm.

Based on the above problems, the disadvantages of using chemical reagent method to treat circulating water are obvious.

In terms of automatic control, the current dosing method adopts the method of automatic monitoring and control. The monitoring method is mainly based on the chemical composition of water, such as: calcium, magnesium, total alkali, chlorine, etc., as well as pH and conductivity. Control water discharge and replenishment. However, these data are only used as indirect indicators to judge the scaling or corrosion tendency of water for control, and these indicators may not be able to accurately and comprehensively reflect the water quality.

The physical method is mainly used for scale inhibition. It uses a magnetic field to penetrate the water, so that the scale-forming ions are surrounded by water molecules and dispersed into small crystals, which are not easy to form scale on the surface of the equipment. However, in practical application, it is found that there are high requirements for water quality, the descaling effect is limited, and the effectiveness of killing corrosion and microorganisms is not obvious.

Ozone treatment of circulating cooling water is a new technology that has become mature in the past ten years. By injecting dissolved ozone into the circulating water, strong oxidizing free radicals such as OH are generated in the water, and they react with microorganisms and chemical molecules in the water to achieve the purpose of purification and disinfection. Through proper design, under certain process conditions, the ozone method can replace the chemical treatment, and at the same time achieve the effects of scale inhibition, corrosion prevention, and sterilization.

Since the 1990s, foreign countries have accumulated some basic experience and research results in the application of ozone to treat cooling water. The application of ozone in this field has been proven to be a safe, effective and non-polluting cleaning technology. In practice, ORP (Oxidation-Reduction Potential) is used to control the amount of ozone generated, and it is carried out manually according to the conductivity of water, sodium, chlorine, calcium, magnesium and total alkalinity (POSI index, practical ozone scaling index) and bacteria. Drain and replenish circulating water. That is to say, the current ozone treatment method has not yet entered the automatic control stage, but relies on manual periodic measurement, and after comprehensive consideration of multiple parameters, artificial discharge and replenishment of circulating water are carried out.

The calculation formula of the practical ozone fouling index POSI mentioned above can be operated at a higher number of cycles than the chemical method. POSI expressions are as follows:

$\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Ca</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; Mg</span>}}{\mathrm{<span\; class="notranslate">\; Na</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Cl</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; ALK</span>}}{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 0</span>}$

Among them: Ca, Mg, ALK are calcium ions expressed in calcium carbonate, magnesium ions and total alkalinity (mg/L) respectively in supplementary water; Cl, Na are the concentrations of chlorine and sodium ions in supplementary water (mg/L); C0 is the electrical conductivity of the supplementary water, and C1 is the maximum electrical conductivity allowed by the circulating water. C1/C0 is the concentration multiple or the number of cycles of circulating water. The higher the value, the higher the water utilization rate, which has a great influence on the water saving effect. On the other hand, when the discharge water is insufficient, it will also cause scaling, the growth of microorganisms, the formation of dirt and bacterial corrosion.

However, the number of cycles calculated by the conductivity value of C1 and C0 in the POSI formula may be low, so using this index to control water circulation and discharge often cannot achieve the highest efficiency. For this reason, some people suggest that the concentration of a certain component in water should be used instead of conductivity to calculate C1/C0. For example, a higher cycle number can be achieved with the concentration of sodium, total alkali, silicon, etc., but it is difficult to realize automatic monitoring in actual operation. inconvenient. Therefore, the POSI value expressed by the above formula is still uncertain. More importantly, because the supplementary water quality often changes in practice, seasonal changes and changes in working conditions will directly affect the determination of the POSI value. For example, the conductance of tap water in this city varies greatly, resulting in changes in the preset POSI value. Moreover, when using water from other sources as supplementary water, there is no guarantee that the conductance will always be stable and other components will remain unchanged. Therefore, In these cases, simply using the POSI calculated under steady-state conditions as a measure of fouling propensity will not be reliable.

In view of the above problems, designing a method that fully reflects the circulating water indicators in the ozone treatment circulating cooling water system and using these indicators to realize the automatic control of circulating cooling water is the key to the promotion and development of the ozone treatment method.

Contents of the invention

The technical problem to be solved by the present invention is to provide an automatic control method for the ozone treatment cooling circulating water system, which can detect various parameters in the cooling circulating water system, and determine the direct indicators that can reflect the water quality accordingly. When some key indicators exceed When specified, ozone concentration adjustment or discharge and replenishment of water are performed automatically.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: provide an automatic control method for the ozone treatment cooling circulating water system, use an automatic control system to perform detection and control of the cooling circulating water system, the cooling circulating water system includes a sump , a cooling tower that provides cooling water to the sump, a refrigeration unit that cools the output water from the sump and sends it to the cooling tower, and an ozone generator for injecting ozone, wherein a discharge valve is provided at the bottom of the sump; the automatic The control system has a real-time data detection unit, an analysis unit and a control device, the data detection unit includes a plurality of sensors arranged in the cooling circulating water system, the control device has a database, the water quality is stored in the database The preset values of microbial index and dirt heat resistance value, and the preset range of ozone concentration; the automatic control method includes the following steps. a. automatically collect a group of real-time parameters with the real-time data detection unit, wherein the group of real-time parameters at least include the microbial index of water quality, and at least the dirt thermal resistance value of water quality can be determined; b. detect according to the real-time data with the described analysis unit The real-time parameters input by the unit calculate the dirt thermal resistance value; c. According to the comparison result of the measured microbial index and the microbial index preset value in the database, determine a control point from the preset range of ozone concentration in the database and output To the ozone generator; d. compare the calculated dirt thermal resistance value with the preset value of the dirt thermal resistance value in the database, and when the dirt thermal resistance value exceeds the preset value, the control device outputs a control signal to make The drain valve drains water.

In the above automatic control method, the microbial indicators include the amount of biological slime and/or the total number of bacteria.

In the above-mentioned automatic control method, the calculation formula of the dirt thermal resistance value R is:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; Cp</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}$

Where A is the heat transfer area of the heat exchanger of the refrigeration unit, T1/T2 is the inlet/outlet temperature of the heat medium, t1/t2 is the inlet/outlet temperature of the cooling circulating water, and G is the cooling water flow through the heat exchanger , Cp is the specific heat of water.

In the above automatic control method, the real-time parameters also include the corrosion rate of cooling circulating water.

In the above-mentioned automatic control method, the step a also includes: receiving a set of regular parameters input from the outside with a data input unit, wherein the practical ozone fouling index POSI can be determined in combination with the real-time parameters and the regular parameters; and the step b also includes: calculating the ozone fouling index according to the real-time parameter and the periodic parameter.

In the above-mentioned automatic control method, after the step b, it also includes: displaying the real-time parameters and water quality indicators with a system monitoring unit, and outputting corresponding control signals when a certain parameter or indicator is abnormal; and monitoring according to the system. The control signal of the unit makes an alarm unit output a corresponding prompt alarm.

In the above-mentioned automatic control method, the real-time parameters also include the first oxidation-reduction potential of the ozone water injection point, the second oxidation-reduction potential of the heat exchanger inlet of the refrigeration unit, and the step c also includes: using the first oxidation-reduction potential The reduction potential and the second oxidation-reduction potential are used as feedback signals to adjust the amount of ozone generated by the ozone generator.

In the above-mentioned automatic control method, it also includes step e: using a backflushing device to backflush the suspended particles in the circulation pipeline of the cooling circulating water system, and the step e further includes: e1. providing a filter, which is set On the pipeline output from the sump to the refrigeration unit, it is connected to a recoil pump through a recoil valve, and the recoil pump is connected to a water source; e2. Use the real-time data detection unit to detect the filter The inlet/outlet pressure difference, in the control device, compares the pressure difference with the pressure difference preset value in the database; and e3. When the pressure difference exceeds the preset value, the The control device outputs a control signal to open the recoil valve, so that the water in the water source enters the filter through the recoil pump and the recoil valve to wash away the dirt therein.

In the above automatic control method, the preset range of ozone concentration in the database is: the ozone water injection point is 0.5-1.5 ppm, and the inlet of the heat exchanger of the refrigeration unit is 0.02-0.08 ppm.

The inventors of the present invention have found through practice that the fouling thermal resistance value R is used as a direct indicator to measure the fouling tendency of circulating water, which can stably and accurately reflect the fouling tendency of circulating water. Combining the fouling thermal resistance value R with the corrosion rate of water and microbial indicators will be able to comprehensively and directly reflect the water quality of circulating water, thus providing an accurate basis for automatic control. Owing to adopting above technical scheme, the present invention can reach following beneficial effect at least:

1. Through the automatic control method of the present invention, it is possible to monitor in real time the three main direct water quality indicators of the ozone treatment circulating cooling water, such as scaling, corrosion and microorganisms, to ensure that the cooling circulating water is in changing working conditions, seasons, supplementary water from different sources, etc. Maintain a good balance of water quality under certain conditions, and at the same time achieve a clean state of scale inhibition, corrosion resistance and low microorganisms.

2. Through the present invention, effective real-time detection and control of the ozone-treated cooling circulating water is realized, which is of vital significance for improving the energy efficiency of the heat exchanger, reducing corrosion, and increasing the service life of the equipment.

Description of drawings

In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

Fig. 1 is the schematic diagram of the cooling circulating water system adopting the automatic control method of the present invention.

Fig. 2 is a structural block diagram of an automatic control system designed according to an automatic control method according to an embodiment of the present invention.

Fig. 3 is a flowchart of an embodiment of the automatic control method of the present invention.

Detailed ways

The present invention is an automatic control method designed for the ozone treatment circulating cooling water system, which is used to achieve the following purposes: to establish a multi-parameter database combining direct water quality scaling, corrosion, microbial indicators and chemical and physical indicators, according to different users The working conditions and water source conditions set the boundary conditions that can ensure the balance of water quality. It mainly carries out the following tasks: First, through the determination of multiple parameters, monitor the changing state of circulating water, and compare the direct indicators with the preset database to judge whether the state of circulating water is corrosion or scaling Tendency, in order to dynamically implement the automatic operation instructions of the system. Secondly, according to the previous judgment on the state of the water, the discharge of the cooling circulating water and the operation of the pump valve of the supplementary water are commanded. Furthermore, according to the previous judgment on the state of water and the discharge and replenishment of water, the amount of ozone generation can be adjusted in real time: increase when needed, and decrease when not needed.

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is the schematic diagram of the cooling circulating water system adopting the automatic control method of the present invention. Please refer to FIG. 1 , the entire circulating cooling water system mainly includes a cooling tower 70 , a sump 71 and a refrigeration unit 72 . The flow direction of the circulating water is: from the sump 71 to the refrigeration unit 72, after contacting the hot surface of the refrigeration unit, it flows to the cooling tower 70, and then flows back to the sump 71 after being sprayed. Due to the discharge or evaporation of the circulating water, when the water level in the sump 71 is lower than a certain water level, the valve 79 is controlled by the float level controller 78 to realize the automatic replenishment of the circulating water from the replenishing water source 80 .

There are many sensors in the whole system to detect data online in real time, for example, a conductance probe 60 is installed at the inlet of the cooling water replenishment, which is connected to the conductance meter 40 through wires as the conductance value of the replenishment water. A flow meter 61 is installed in the circulating water pipeline where the cooling circulating water flows to the refrigerating unit 72 side, and is connected with the flow meter 41 by a wire, as the flow value G of the cooling circulating water; Table 42 is connected as the cooling water inlet temperature value t1; an online pressure gauge 43 is installed in the inlet pipe of the filter 75 as the recoil inlet pressure; an online pressure gauge 44 is installed in the outlet pipe of the filter 75 to do To recoil the outlet pressure; install a temperature probe 55 in the circulating water pipeline on the side where the cooling circulating water flows out of the refrigerating unit 72, and connect it to the thermometer 35 through a wire as the cooling outlet temperature value t2. A temperature probe 53 is installed at the inlet of the heat medium of the refrigeration unit 72, and is connected with the thermometer 33 through a wire, as the inlet temperature T1 of the heat medium; at the same time, a temperature probe 54 is installed at the outlet of the heat medium, and is connected with the thermometer through a wire. 34 connection, as the outlet temperature T2 of the heat medium. A bypass is designed between the inflow pipeline and the outflow pipeline of the cooling circulating water, and an online corrosion rate meter 73 is installed on the bypass to test the corrosion rate of the cooling circulating water to metals (such as low carbon steel, red copper).

Bearing the above, a section of pipeline is designed between the cooling circulating water pipeline flowing to the refrigeration unit 72 and the sump 71 for the injection of ozone, and a nozzle 76 is installed near the water collector side in the pipeline, and the ozone generator 20 produces The ozone that comes out is injected into the circulating water system through the nozzle 76; an ORP probe 59 is installed in front of the nozzle 76, and is connected with the ORP meter 39 through a wire, and the first oxidation-reduction potential ORP1 for detecting the ozone injection point is installed behind the nozzle 76 A booster pump 77 is used to ensure the water pressure and flow in the pipeline. Install the following detection instruments near the circulating water inflow pipeline in the pipeline: conductance probe 50, connected with the conductance instrument 30 through a wire, as the conductance value PH probe 51 of cooling circulating water, connected with the PH instrument 31 through a wire, as a cooling cycle The pH value of water; the ORP probe 52 is connected to the ORP instrument through wires, and is used to detect the second oxidation-reduction potential ORP2 at the inlet of the heat exchanger (not shown) of the refrigeration unit 72 .

In addition, a filter 75 is installed in the inlet pipe of the cooling circulation pump 81, and the filter 75 can filter suspended particles in the circulating water to make it deposit, while the water in the backflush water source 82 can pass through the backflush valve 22 and the backflush pump. 23. Backflush into the filter 75 to wash away the dirt deposits inside it.

It should be pointed out that the above-mentioned sensors and instruments are all determined according to the needs of the parameters to be collected, and their types, quantities and set positions are not used to limit the present invention.

All the instrument signals mentioned above are sent to the monitoring device 120 of the automatic control system 100 through the bus communication mode (please refer to Fig. 2), and the parameters that need to participate in the system control in the monitoring device can be transmitted to the control device 130 through a dedicated communication cable, and the control The device 130 calculates various received signals, and then controls the ozone generator 20, the circulating water discharge valve 21, the recoil valve 22 and the recoil pump 23 in the recoil device. At the same time, a remote communication port is reserved on the control device 130, which can be connected with a remote host as required.

Fig. 2 is a structural block diagram of an automatic control system designed according to an automatic control method of an embodiment of the present invention. Please refer to FIG. 2 , the automatic control system 100 is composed of four parts connected in sequence, namely a parameter acquisition device 110 , a monitoring device 120 , a control device 130 and an actuator 140 . The parameter acquisition device 110 is responsible for the detection and input of parameters, the monitoring device 120 completes the storage and display of various data; the control device 130 is responsible for the logic judgment and calculation of the entire control system, and through its combination with the monitoring device 120, it becomes The core of the whole system directs the action of the actuator 140 . Wherein, the actuator includes an ozone generator 20 , a discharge valve 21 , a recoil valve 22 and a recoil pump 23 as shown in FIG. 1 .

Based on the above, the parameter acquisition device 110 further includes a real-time data detection unit 111 and a data input unit 112 . The real-time data detection unit 111 includes all the sensors shown in Figure 1 to collect various parameters in real time and transmit them to the monitoring device 120 through the communication mode of the field bus to achieve real-time and accurate results, listed in Table 1 below These parameters:

Table 1

It should be pointed out that the sensors for detecting the pressure of the ozone generator cooling water and the flow rate of the ozone generator cooling water are not shown in FIG. 1 , but those skilled in the art can completely install them in appropriate positions as required.

The data input unit 112 is a component that can receive input instructions, such as a keyboard or a touch screen, which is used to receive a set of regular parameters manually input, and the following table 2 lists these regular parameters by category:

Table 2

The first ozone concentration is the ozone concentration at the ozone water injection point, and the second ozone concentration is the ozone concentration at the inlet of the heat exchanger, which can be used to correct the above-mentioned first oxidation-reduction potential ORP1 and second oxidation-reduction potential ORP2.

The monitoring device 120 may further include an analysis unit 121 , a system monitoring unit 122 , a data storage unit 123 , and an alarm unit 124 . In one embodiment, the monitoring device 120 may use an industrial computer or a touch screen HMI as a medium for human-computer interaction. The data storage unit 123 is used to store data that needs to be saved, including collected, input and analyzed data. In one embodiment, the data storage unit 123 uses SDRAM as a memory, and the internal battery is used for power-off protection, and the historical data in the SDRAM memory can be transferred through a USB mobile memory, which is convenient for users to process data and save data files. .

The control device 130 is composed of a programmable controller PLC, which is the core of the automatic control system. The process parameters in the monitoring device 120 are obtained through the field bus communication method, and the closed-loop control of the ozone concentration is realized through calculation and comparison with a database. control, closed-loop control of cooling circulating water discharge, and closed-loop control of backflush pump valves. The control device 130 includes a database 131 , an ozone concentration control unit 132 , a cooling water discharge control unit 133 , and a backflush control unit 134 .

The database 131 stores the process parameters obtained from the monitoring device 120 (such as the parameters in Table 1 and Table 2), as well as the preset values of various process parameters, which are the basis for judging whether each real-time parameter is normal. The preset values of these parameters are, for example: thermal resistance of dirt: 3*10 ^-4 m ² K/W, amount of biological slime: 4ml/m ³ , total number of bacteria 3000CFU/ml, carbon steel corrosion rate 0.125mm/year , The first ozone concentration: 0.5-1.5ppm, the second ozone concentration: 0.02-0.08ppm. It should be noted that these preset values and preset ranges are just examples, and actual preset values and preset ranges can be adjusted according to changes in the quality of supplementary water, or changes in seasons and working conditions.

Please in conjunction with Fig. 1～shown in Fig. 3, the automatic control method of the present invention comprises the following steps:

First, step 301 is executed to automatically collect a group of real-time parameters with the real-time data detection unit 111, wherein the real-time parameters include at least the microbial index of water quality, and at least the dirt thermal resistance value of water quality can be determined; for example, the real-time collected data is at least Including: cooling water inlet temperature t1, cooling outlet water temperature t2, heat medium inlet temperature T, heat medium outlet temperature T2, circulating cooling water flow G, and biological slime amount, total number of bacteria, etc. used to calculate the thermal resistance value R of the dirt Microbial indicators.

In practice, it is often uneconomical and unnecessary to use real-time detection for all parameters. For this reason, in step 301, a group of aforementioned regular parameters receiving external input by the data input unit 112, i.e. Microbial indicators such as mud volume and total number of bacteria, as well as total alkalinity, calcium ions, sodium ions, magnesium ions, chloride ions, turbidity, TOC/5-day biochemical oxygen demand, first ozone concentration DO31, second ozone concentration DO32, etc. index. Because these data changes infrequently or the cost of on-line detection is high, manual collection by portable instruments or laboratory tests are used to transfer the manually measured data to the monitoring device 120 through the data input unit 112, which can save costs. Especially at present, although microbial indicators such as the amount of biological slime and the total number of bacteria can also be measured in real time by the on-line detection instruments included in the real-time data detection unit 111, but because such instruments are expensive, and the significance of real-time detection is not large, Therefore, the method input by the data input unit 112 can be used instead of real-time measurement. However, the present invention does not limit the collection method of parameters, that is, the embodiment of the present invention can use online detection equipment to collect microbial indicators such as the amount of biological slime and the total number of bacteria, or other indicators that are currently not easily collected by online detection methods.

Next, step 302 is executed, and the analysis unit 121 calculates the fouling thermal resistance value R according to the real-time parameters input by the real-time data detection unit 111. The fouling thermal resistance value R is a direct indicator used to measure the fouling tendency of circulating water. In the invention, as the basis for discharging water to eliminate scaling tendency, its calculation formula is

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; Cp</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}$

Among them, R is the fouling thermal resistance of the cooling circulating water, A is the heat transfer area of the heat exchanger, which is a predictable fixed value, T1/T2 is the inlet/outlet temperature of the heat medium, and t1/t2 is the inlet/outlet of the cooling circulating water Temperature, G is the cooling water flow through the heat exchanger, Cp is the specific heat of water, which is 4.15kJ/kg.℃.

At the same time, the ozone fouling index POSI is used for another scaling tendency index of circulating water, although it is not accurate enough to regard it simply as the fouling tendency. However, the relevant data of POSI can be used as a reference to play an early warning role. Therefore, the analysis unit 122 can also calculate the POSI according to the parameters obtained by the parameter acquisition device 110 and transmit it to the system monitoring unit 122 for display, and its expression is as follows:

$\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; Ca</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; Mg</span>}}{\mathrm{<span\; class="notranslate">\; Na</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Cl</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; log</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; ALK</span>}}{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 0</span>}$

Among them: Ca, Mg, ALK are calcium ions expressed in calcium carbonate, magnesium ions and total alkalinity (mg/L) respectively in supplementary water; Cl, Na are the concentrations of chlorine and sodium ions in supplementary water (mg/L); C0 is the electrical conductivity of the supplementary water, and C1 is the maximum electrical conductivity allowed by the circulating water. C1/C0 is the concentration multiple or cycle times of circulating water.

Afterwards, step 303 is executed, and the ozone concentration control unit 132 determines a control point from the preset range of the ozone concentration in the database 131 according to the comparison result of the microbial index measured and the microbial index preset value in the database 131 and outputs it to the ozone generator. device 20; for example, when the amount of biological slime measured exceeds the preset value of 4ml/m ³ , or the total number of bacteria exceeds 3000CFU/ml, within the preset range of 0.5-1.5ppm, the above-mentioned first ozone concentration is increased, and at 0.02 Within the preset range of ~0.08ppm, increase the above-mentioned second ozone concentration. The preset ranges of the first and second ozone concentrations can be reduced to one point. For example, in a preferred embodiment, the first ozone concentration is set to 1 ppm, and the second ozone concentration is set to 0.02 ppm. In another preferred embodiment, the first ozone concentration can be set to 0.57ppm, and the second ozone concentration can be set to 0.05ppm. Under these circumstances, the first and second ozone concentrations will be slightly adjusted around the preset values.

The step 303 preferably includes using a PID controller (not shown) in the ozone concentration control unit 132 to perform closed-loop control. Please refer to Fig. 1, the specific process is: after determining the appropriate ozone concentration control point, by comparing with the ozone concentration corresponding to the oxidation-reduction potential ORP1, ORP2 collected by the ORP probes 59, 52 in the pipeline, the The size and change speed of this comparison value are sent to the PID controller as a feedback signal, and the PID controller outputs the analog signal m to the ozone generator 20 according to the calculation result, and the ozone generator 20 generates a corresponding amount of the corresponding amount according to the input analog value. Ozone is injected into the pipeline of the cooling circulating water through the nozzle 76 to complete the PID closed-loop control of the ozone concentration. The first oxidation-reduction potential ORP1 and the second oxidation-reduction potential ORP2 can be measured by the real-time data detection unit 111 in step 301 .

In addition, there may be deviations between the above-mentioned oxidation-reduction potentials ORP1, ORP2 and the actual ozone concentration. For this reason, the present invention also includes measuring the first ozone concentration DO31 and the second ozone concentration DO32 at the positions of ORP1 and ORP2 in advance to measure the oxidation-reduction potential ORP1, ORP2 carry out the steps of correction (for example, carry out straight line fitting), in order to improve the measurement accuracy.

Please return to FIG. 3 and in conjunction with FIG. 1, step 304 is executed, the cooling water discharge control unit 133 compares the calculated dirt thermal resistance value with the preset value of the dirt thermal resistance value in the database 131, and when the dirt thermal resistance value exceeds When the preset value is 3*10 ⁻⁴ m ² ·K/W, the control device outputs a control signal p to the discharge valve 21 below the sump, so that the discharge valve 21 is opened to drain water.

When the water level in the sump 71 is lower than a certain water level, the float level controller 78 will automatically control the valve 79 to realize the automatic replenishment of circulating water from the supplementary water source 80 . Thereafter, the drainage was maintained until the detected conductance of the circulating water was 2000uS/sec.

In addition, the corrosion rate can also be used as a reference index for discharge water. For example, the cooling water discharge control unit 133 compares the low-carbon steel corrosion rate of circulating water with the preset value of 0.125mm/year in the database 131. When the low-carbon steel corrosion rate exceeds 0.125 mm/year, the cooling water discharge control unit 133 needs to refer to the value of the thermal resistance of the dirt and the value of the microbial index. If these two indexes are qualified, no drainage can be made to maintain a high electrical conductivity of the system, which can reduce corrosion. The cooling water discharge control unit 133 performs a draining action only if the corrosion rate is greatly increased due to a sudden event.

Of course, since the ozone concentration in the water changes after the discharge, the present invention will automatically adjust the generation of the ozone generator 20 according to the feedback of the first oxidation-reduction potential ORP1 and the second oxidation-reduction potential OPR2 with the ozone concentration control unit 132. quantity.

Still refer to Fig. 3 and shown in conjunction with Fig. 1, carry out step 305, utilize backflushing device to backflush the suspended particle in the circulation line of cooling circulating water system, this step 305 further comprises the following steps: first with real-time data detection unit 111 The pressure gauges 43 and 44 detect the inlet/outlet pressure difference of the filter 75 , and the backflush control unit 134 compares the pressure difference with the preset value of the pressure difference in the database 131 . When the pressure difference exceeds the preset value, the recoil control unit 134 outputs a control signal f to open the recoil valve 22, so that the water in the water source 82 enters the filter 75 through the recoil pump 23 and the recoil valve 22 to be washed away the dirt in it. Practice has proved that this step will greatly reduce the suspended solids in the circulating water and improve the cleanliness of the water. However, it should be pointed out that the lack of recoil does not affect the realization of the main purpose of the method.

In practice, technicians often need to directly monitor system operating state parameters as well as various water quality indicators so that appropriate interventions can be made. Therefore, after the above-mentioned step 301, it also includes: using the system monitoring unit 122 to display real-time parameters, regular parameters and water quality indicators, and outputting corresponding control signals when a certain parameter or indicator is abnormal; and according to the control of the system monitoring unit 122 signal, so that an alarm unit 123 outputs a corresponding prompt alarm. Specifically, the data displayed by the system monitoring unit 122 includes: all collected data, the thermal resistance value of dirt, the maximum conductivity of circulating water, the scaling index POSI of supplementary water, the scaling index POSI of circulating water; the operation of the ozone generator 20 state, the working state of the discharge valve 21, the working state of the recoil valve 22; the target circulation ratio, the national water quality reference standard, etc. When a monitored parameter is abnormal, the system monitoring unit 122 will send a corresponding control signal to the alarm unit 124 to perform corresponding actions.

When the alarm unit 124 receives the control signal output by the system monitoring unit 122, it will generate a corresponding alarm. These alarms can be divided into alarms for equipment status and alarms for water quality indicators. Equipment state alarm is for example, is when the ozone generator 20 cooling water pressure is too low, components and parts are overheated, oxygen pressure is too low, there is ozone concentration leakage etc. in the air, alarm unit 124 will report to the police and cut off the power supply automatically, protection equipment and On-site safety. At this time, the user needs to repair and troubleshoot before resuming operation. The water quality prompt alarm, for example, is a prompt alarm to the user in the following cases: when the conductivity exceeds the value (concentration multiple) measured and estimated according to POSI; when the calcium hardness exceeds 500, when the chloride ion concentration exceeds 1000 mg/ liter, when the total alkalinity exceeds 500 (calculated as calcium carbonate), the pH value is less than 8, and some ions such as phosphate and sulfate are too high, they can be used as prompt alarms, causing users to pay close attention, because these indicators do not directly reflect the water quality. indicators, so appropriate interventions can be made or left untreated. At the same time, it should be pointed out that since these indicators are only used as references, the selection of indicators and the preset values of indicators can be determined by users themselves, and it is not necessary to make prompt alarms for the abnormalities of all the above indicators.

In summary, the automatic control method of the present invention is applied to the circulating water of cooling towers, comprehensive corrosion rate, online dirt thermal resistance and microorganisms and other direct indicators, using intelligent control methods to judge the circulating water in different water quality and working conditions corrosion and fouling tendencies. By comparing with the database 131 to determine the appropriate ozone concentration value in the circulating water, the PID regulator of the ozone concentration control unit 132 realizes the closed-loop control of the ozone concentration in the circulating water; at the same time, the control device 130 compares the parameters such as the dirt thermal resistance value of the circulating water Automatically control the discharge valve 21 of the circulating water, and the pressure difference before and after passing through the filter 75, and automatically control the recoil pump 23 and the recoil valve 22; The best condition for scale, corrosion and microorganisms. Therefore compared with prior art, the present invention has the following advantages:

1. Through the automatic control method of the present invention, it is possible to monitor in real time the three main direct water quality indicators of the ozone treatment circulating cooling water, such as scaling, corrosion and microorganisms, to ensure that the cooling circulating water is in changing working conditions, seasons, supplementary water from different sources, etc. Maintain a good balance of water quality under certain conditions, and at the same time achieve a clean state of scale inhibition, corrosion resistance and low microorganisms. Treatment with ozone can replace the traditional method of adding a variety of chemicals. Its various indicators are superior to traditional pharmaceutical methods: it can efficiently kill heterotrophic bacteria that cause corrosion, greatly reduce the total number of bacteria in water, and kill algae and pathogenic Legionella. Moreover, since the ozone method does not use chemicals, chemical pollution to the environment caused by water discharge is eliminated from the source.

Through the present invention, effective real-time detection and control are realized for the ozone-treated cooling circulating water, and compared with the manual control method, the energy efficiency of the heat exchanger is improved, corrosion is reduced, and the service life of the equipment is increased.

2. By the estimation of the scaling tendency (POSI) of circulating water in ozone treatment by the present invention, in conjunction with other relevant process parameters, the allowable recycling times (or concentration multiples) are determined according to different cooling circulating water systems, and passed Automatically controlled discharge and replenishment of circulating water to maximize water utilization efficiency. This control method has been shown to allow higher conductance than the pharmaceutical method, which means a greater concentration factor. At present, the number of cycles treated by the traditional method is 2-3 times, which can be increased to 5-10 times or even higher with this technology. The present invention can utilize different water sources as circulating water (for example utilizing waste water in certain processes, regenerated water, etc.). Through prior analysis, calculation and control, significant water saving can be effectively realized. The practice result proves that the present invention has a very good actual effect on the correction of POSI, which can greatly increase the water utilization rate than the calculated value, and ensure that the water quality fully complies with the standard.

3. The intelligent control method can combine the discharge and replenishment of water with the amount of ozone generation, and dynamically adjust the amount and concentration of ozone generation at any time. Through PID control, the amount of ozone generated by the system can be changed with the working conditions. For example, when the organic matter in the water increases due to air or accidental entry, or the biological sludge increases due to climate reasons, the amount of ozone generated will increase, and vice versa. This design not only makes the system more efficient, but also reduces the energy consumption of the system itself.

The above descriptions of the embodiments are only descriptions of preferred embodiments of the present invention, and those skilled in the art can make various other equivalent replacements and modifications based on the above descriptions of the embodiments of the present invention. However, the various equivalent replacements and modifications made according to the embodiments of the present invention belong to the inventive spirit of the present invention and the patent scope defined by the claims.

Claims (9)

1. an automatic control method of an ozone treatment cooling circulating water system, utilizes an automatic control system to carry out the detection and control of the cooling circulating water system, the cooling circulating water system comprises a sump, a cooling tower providing cooling water to the sump, a Cool the output water of the sump tank and deliver it to the refrigeration unit of the cooling tower, and an ozone generator for injecting ozone, wherein a discharge valve is provided at the bottom of the sump pool; the automatic control system has a real-time data detection unit and an analysis unit And a control device, the data detection unit includes a plurality of sensors arranged in the cooling circulating water system, the control device has a database, the microbial index of the water quality and the preset value of the dirt thermal resistance value are stored in the database, And the preset scope of ozone concentration; Described automatic control method comprises: a. Automatically collect a group of real-time parameters with the real-time data detection unit, wherein the group of real-time parameters at least include microbial indicators of water quality, and at least the dirt thermal resistance value of water quality can be determined; b. calculating the dirt thermal resistance value with the analysis unit according to the real-time parameters input by the real-time data detection unit; c. According to the comparison result of the microbial index measured and the microbial index preset value in the database, a control point is determined from the preset range of the ozone concentration in the database and output to the ozone generator; d. Comparing the calculated dirt thermal resistance value with the preset value of the dirt thermal resistance value in the database, and when the dirt thermal resistance value exceeds the preset value, the control device outputs a control signal to make the discharge valve drain. 2. The automatic control method according to claim 1, characterized in that, the microbial indicators include biological slime amount and/or total number of bacteria. 3. automatic control method as claimed in claim 1, is characterized in that, the computing formula of described dirt thermal resistance value R is: $\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; Cp</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}$ Where A is the heat transfer area of the heat exchanger of the refrigeration unit, T1/T2 is the inlet/outlet temperature of the heat medium, t1/t2 is the inlet/outlet temperature of the cooling circulating water, and G is the cooling water flow through the heat exchanger , Cp is the specific heat of water. 4. The automatic control method according to claim 1, characterized in that, said real-time parameters also include the corrosion rate of cooling circulating water. 5. automatic control method as claimed in claim 1, is characterized in that, The step a also includes: receiving a set of externally input regular parameters with a data input unit, wherein the practical ozone fouling index POSI can be determined by combining the real-time parameters and the regular parameters; and The step b also includes: calculating the ozone fouling index according to the real-time parameters and the regular parameters. 6. automatic control method as claimed in claim 1, is characterized in that, also comprises after described step b: Using a system monitoring unit to display the real-time parameters and water quality indicators, and output corresponding control signals when a certain parameter or indicator is abnormal; and According to the control signal of the system monitoring unit, an alarm unit outputs a corresponding prompt alarm. 7. automatic control method as claimed in claim 1, is characterized in that, described real-time parameter also comprises the first oxidation-reduction potential of ozone water injection point, the second oxidation-reduction potential of the heat exchanger inlet of refrigerating unit, and said The step c further includes: using the first oxidation-reduction potential and the second oxidation-reduction potential as feedback signals to adjust the amount of ozone generated by the ozone generator. 8. The automatic control method as claimed in claim 1, further comprising step e: utilizing a recoil device to recoil the suspended particles in the circulating pipeline of the cooling circulating water system, said step e further comprising : e1. Provide a filter, which is arranged on the pipeline output from the sump to the refrigeration unit, and connected to a recoil pump through a recoil valve, and the recoil pump is connected to a water source; e2. Detect the inlet/outlet pressure difference of the filter with the real-time data detection unit, and compare the pressure difference with the pressure difference preset value in the database in the control device; and e3. When the pressure difference exceeds the preset value, the control device outputs a control signal to open the recoil valve, so that the water in the water source enters the filter through the recoil pump and the recoil valve to wash away the dirt. 9. The automatic control method according to claim 1, wherein the preset range of ozone concentration in the database is: the injection point of ozone water is 0.5-1.5ppm, and the inlet of the heat exchanger of the refrigeration unit is 0.02-1.5ppm. 0.08ppm.

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