CN114671558A - Heat supply network circulating water treatment system and method with electrochemical softening coupled with electric flocculation - Google Patents

Abstract

The invention discloses a heat supply network circulating water treatment system and method with electrochemical softening coupled with electric flocculation, wherein the system comprises a pressurizing unit, an electrochemical softening unit, an electric flocculation unit, a clarification unit and a sludge treatment unit, wherein the pressurizing unit, the electrochemical softening unit, the electric flocculation unit and the clarification unit are sequentially arranged along the water flow direction of circulating water of a heat supply network; the electric flocculation unit comprises a first polar plate, a second polar plate and a first control device; the first polar plate and the second polar plate are alternately matched; a first gap is arranged between the first polar plate and the adjacent second polar plate; the first polar plate and the second polar plate are electrically connected with a first control device, and the first control device can enable the first polar plate and the second polar plate to be reversed. The first polar plate and the second polar plate are soluble electrodes. The system can simultaneously realize softening of the circulating water of the heat supply network, combined removal of suspended particles and metal corrosion product impurities in the suspended particles, and is reasonable in design, convenient to use and not easy to generate secondary pollution.

Description

A thermal network circulating water treatment system and method with electrochemical softening coupled with electroflocculation

technical field

The invention belongs to the technical field of heat network circulating water treatment, and relates to a heat network circulating water treatment system and method with electrochemical softening coupled with electric flocculation.

Background technique

At present, my country's economic growth is improving, the national economy has been greatly developed, and the living standards of residents have been continuously improved. For the northern region of my country, central heating is a very important livelihood project, which is directly related to the quality of life of residents. The so-called central heating is to use water or water vapor as the medium to send heat into the residents' homes through the transmission of heating pipes, thereby replacing the traditional personal heating method to achieve central heating. Typically, the medium that ultimately delivers heat to a resident's home is water.

The heating pipe network system is a relatively special system in industrial production, and its water temperature is high, which is prone to scaling and corrosion problems. According to the current standard CJJ34-2010 "Code for Design of Urban Heating Pipe Networks" and GB/T 12145-2016 "Water and Vapor Quality Standards for Thermal Power Generation Units and Steam Power Equipment", the hot water heating network with thermal power plants and regional boiler rooms as heat sources, among which The hardness of the make-up water should not exceed 0.60mmol/L. However, my country has a vast territory and a vast territory, and the heating pipe network system is usually relatively large. If the water quality in the standard specification is fully adopted, the primary reverse osmosis effluent of the power plant or the primary desalinated water needs to be used as the circulating water for the heating network. Power plants and heating companies are unable to afford their water production costs. Therefore, at present, most of the heating water directly uses tap water, circulating water and even unsoftened raw water such as reclaimed water. This leads to a decrease in the efficiency of the heating system and even blockage.

The scale samples in the heat exchange tubes of a heating pipe network system were analyzed, and the results showed that the main components were calcium and magnesium scale and iron corrosion products, of which calcium and magnesium scale accounted for 83%, and iron corrosion products accounted for 17%. The hardness of the circulating water in the heating network of the heating pipe network system is above 4 mmol/L, and there are a large number of corrosion products of suspended iron, the turbidity is 110-150 NTU, and the iron content is 4-7 mg/L. Due to the high hardness of the circulating water of the heating network, scaling is easy to occur inside the heating network heater with a higher temperature during operation. A large number of iron corrosion products and scales in the circulating water are combined together, resulting in the gradual deterioration of the scaling. Finally, the heat exchange tube of the heat network heater is blocked.

In order to solve the scaling and corrosion problems of the heating pipe network system, some power plants or heating companies treat the supply water of the heating pipe network system by putting into operation sodium beds, and use ion exchange resin to remove Ca ²⁺ and Mg ²⁺ in the water. The scale-forming ions are replaced by Na ⁺ to achieve the purpose of softening the make-up water, but the ion exchange resin is easy to fail due to pollution and poisoning, the requirements for the influent water are high, and regeneration is required. The cost of high-salt wastewater treatment is also relatively high; some power plants or heating companies also add scale inhibitors and antiseptics to the heating pipe network system to inhibit the growth and deposition of scale and slow down corrosion. Poor, not only the added agent needs to maintain the scale inhibition rate and corrosion inhibition performance required by the system at high temperature, but also requires the agent itself to have good stability and should not be decomposed at high temperature. The scale inhibitor that can meet the above requirements is usually phosphorus. It is a scale and corrosion inhibitor of the series, in which the phosphorus content is relatively high, and long-term use is likely to cause secondary pollution, which is not conducive to environmental protection.

Electrochemical softening is to put an electrode loaded with low-voltage direct current in water, and the scale-forming ions in the water are crystallized and precipitated near the cathode, and then removed to achieve the purpose of softening and scaling. However, part of the calcium carbonate and magnesium hydroxide suspended particles generated by calcium and magnesium ions in the electrochemical softening process cannot be well precipitated, and the metal corrosion products in the circulating water of the heating network cannot be removed by the electrochemical softening process, making the heating network There is still a risk of fouling and plugging of the system.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides a heating network circulating water treatment system and method with electrochemical softening coupled with electroflocculation, so as to simultaneously realize softening, suspended particulate matter and metal corrosion products of circulating water in the heating pipe network The effective settlement and removal of the heating pipe network ensures the normal use of the heating pipe network and effectively prolongs the service life of the heating pipe network.

The present invention is achieved through the following technical solutions:

A heat network circulating water treatment system with electrochemical softening coupled with electric flocculation, comprising a booster unit, an electrochemical softening unit, an electroflocculation unit, a clarification unit and a sludge treatment unit; the booster unit, the electrochemical softening unit, the electric The flocculation unit and the clarification unit are arranged in sequence along the flow direction of the circulating water in the heating network;

The heating network circulating water treatment system is arranged on the bypass of the heating network circulating system;

The electrochemical softening unit, the electric flocculation unit and the clarification unit are all communicated with the sludge treatment unit;

The electric flocculation unit includes several first pole plates, several second pole plates and a first control device; several first pole plates and several second pole plates are alternately arranged to cooperate; A first gap is arranged between the adjacent second electrode plates; a plurality of the first electrode plates and a plurality of second electrode plates are electrically connected to the first control device;

The first electrode plate and the second electrode plate are both soluble electrodes.

Preferably, the electric flocculation unit further includes a first conductive rod and a second conductive rod; a plurality of the first electrode plates are evenly spaced along the axial direction of the first conductive rod, and a plurality of second electrode plates are arranged along the second conductive rod The axial direction of the rod is evenly spaced;

The first conductive rod and the second conductive rod are electrically connected to the first control device; when the first conductive rod is connected to the positive electrode of the first control device, the second conductive rod is connected to the negative electrode of the first control device. When connected, the plurality of first electrode plates are anodes, and the plurality of second electrode plates are cathodes; when the first conductive rod is connected to the negative electrode of the first control device, the second conductive rod is connected to the negative electrode of the first control device. When the positive electrode is turned on, the plurality of first electrode plates are cathodes, and the plurality of second electrode plates are anodes.

Preferably, the water outlet of the clarification unit is further provided with a turbidity monitoring device, and the water outlet of the turbidity monitoring device is provided with a first pipeline and a second pipeline, and the first pipeline is connected to the clarification unit. The water inlet is connected, and the second pipeline is connected to the heating network circulation system.

Preferably, the electric flocculation unit is further provided with a first exhaust port, a first inspection port and a first sewage outlet; the first exhaust port is communicated with the outside atmosphere, and is used for discharging waste generated in the electric flocculation unit. gas; the first sewage outlet is used for discharging the sediment in the electric flocculation unit, and the first sewage outlet is communicated with the sludge treatment unit; the first inspection port is used for overhauling the electric flocculation unit.

Preferably, the electric flocculation unit further comprises a first drive motor and a first rotation shaft connected with the first drive motor; the first drive motor is electrically connected with the first control device; the plurality of first pole plates A through hole is provided on each of the plurality of second pole plates, the first rotating shaft is arranged through the through hole, and a second gap is arranged between the first rotating shaft and the through hole.

Preferably, a plurality of first rotating scrapers are arranged at intervals along the axial direction of the first rotating shaft; and a plurality of the first rotating scrapers extend along the radial direction of the first rotating shaft.

Preferably, the first rotating scraper is arranged at the first gap; the first rotating scraper is provided with a blade on the side close to the first pole plate and the side close to the second pole plate.

Preferably, the first electrode plate and the second electrode plate are one of iron electrodes or aluminum electrodes.

A method for treating circulating water in a heating network by electrochemical softening coupled with electroflocculation, characterized in that the treatment system described in any one of the above is used to purify the circulating water in the heating network, and during the purification process, the first electrode plate or the The surface current density of the second electrode plate is 30-300 A/m ² ; after the electroflocculation unit runs for 5-30 minutes, the connection modes of the first electrode plate, the second electrode plate and the control device are exchanged.

Compared with the prior art, the present invention has the following beneficial technical effects:

A thermal network circulating water treatment system with electrochemical softening coupled with electroflocculation. In the electrochemical softening unit, calcium and magnesium ions in the thermal network circulating water react on the cathode surface of the electrochemical softening unit to generate calcium carbonate and magnesium hydroxide suspension. particulates. The soluble electrode of the electroflocculation unit The soluble anode loses electrons after high-voltage pulsed direct current is applied to form metal cations, which combine with OH ⁱⁿ the solution to form highly active flocculation groups, which have strong adsorption properties. The functions of bridges and nets, such as sweeping and sweeping, turn impurities such as calcium carbonate and magnesium hydroxide suspended particles in the circulating water of the heating network into large particles, and co-precipitate with them, containing co-precipitated particles. The circulating water of the heating network from the sediments enters the clarification unit for precipitation to obtain a supernatant, which is returned to the heating pipe network system again. It can simultaneously realize the softening of the circulating water in the heating network, the combined removal of suspended particulate matter and metal corrosion products and impurities.

Further, the first conductive rod and the second conductive rod can make the installation of the first pole plate and the second pole plate more convenient; the connection modes of the first conductive rod and the second conductive rod and the first control device can be interchanged, and Effectively reduce the surface dirt on the first pole plate and the second pole plate, and prolong the service life of the device.

Further, the turbidity monitoring device is convenient to monitor the purified water quality, so as to control the quality of the circulating water. When the water quality meets the requirements, the purified circulating water enters the heating network circulation system through the second pipeline. If the purified water quality does not meet the requirements, it enters the clarification unit again through the first pipeline for treatment until it meets the requirements, and then passes The second pipeline enters the heating network circulation system, which can make the circulating water effectively meet the actual requirements.

Further, the first exhaust port is communicated with the outside atmosphere, so that the gas generated in the electric flocculation unit can be discharged in time, so as to ensure the safety of the system. The first sewage outlet and the first inspection port can effectively prolong the service life of the device.

Further, the first rotating shaft facilitates the installation of the first rotating scraper. On the one hand, the first rotating scraper can effectively remove the deposits on the surfaces of the first electrode plate and the second electrode plate, improve the current efficiency of the electroflocculation unit, and reduce energy consumption. At the same time, it can play an effective stirring role, improve the turbulence degree of the water flow on the surface of the first electrode plate and the second electrode plate, thereby eliminating the concentration polarization and effectively improving the current efficiency.

Further, on the first rotating scraper, the side close to the first pole plate and the side close to the second pole plate are all provided with a blade, so that the deposits on the surface of the first pole plate and the second pole plate can be thoroughly cleaned. scrape.

Further, the first electrode plate and the second electrode plate are one of iron electrodes or aluminum electrodes, and the flocculation effect is good, and at the same time, the installation cost of the device can be effectively reduced.

A heat network circulating water treatment method with electrochemical softening coupled with electric flocculation, in the treatment process, the surface current density of the first electrode plate or the second electrode plate is controlled to be 30-300 A/m ² ; the current density during the electric flocculation process determines The dissolution of metal ions on the metal electrode increases the current density on the surface of the electrode plate to a certain extent, which can increase the precipitation of metal cations, thereby accelerating the formation rate of the flocculant, and the electroflocculation effect will also be enhanced. It means high energy consumption, and as the current density increases, the polarization and passivation of the electrode will become more serious, which will lead to the worsening of the flocculant generation conditions and the decrease of the electroflocculation effect. The selection of current density should comprehensively consider factors such as pH, temperature and flow rate to ensure that the electroflocculation unit operates at a higher current efficiency. The present invention controls the surface current density of the electrode plate to be 30-300 A/m ² , which can maximize the effect of electric flocculation. The treatment process has a higher degree of automation and simpler operation. It is an active descaling method, and it is not easy to produce secondary pollution, and has the characteristics of environmental friendliness.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the connection schematic diagram of the processing system of the present invention;

Fig. 2 is the structural representation of electroflocculation unit in the present invention;

FIG. 3 is a schematic structural diagram of an electrochemical softening unit in the present invention.

Among them: 1. Booster unit, 2. Electrochemical softening unit, 20, Second exhaust port, 211, Cathode support frame, 212, Cathode, 221, Anode support frame, 222, Anode, 24, Second control device, 231, the second drive motor, 232, the second rotating shaft, 233, the connecting rod of the scraper, 234, the second rotating scraper, 25, the second inspection port, 26, the backwash water inlet, 27, the second sewage outlet, 3, Electroflocculation unit, 31, first electrode plate, 32, second electrode plate, 33, first control device, 311, first conductive rod, 321, second conductive rod, 34, first exhaust port, 35, No. An inspection port, 36, the first sewage outlet, 37, the first drive motor, 38, the first rotating shaft, 381, the first rotating scraper, 4, the clarification unit, 41, the sewage outlet of the clarification unit, 5, the sludge treatment unit , 6, turbidity monitoring device, 61, first pipeline, 62, second pipeline, 7, valve.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inside", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings , or the usual orientation or positional relationship when the product of the invention is used, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed in a specific orientation and operation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are only used to differentiate the description and should not be construed to indicate or imply relative importance.

Furthermore, the presence of the term "horizontal" does not imply that the component is required to be absolutely horizontal, but rather may be tilted slightly. For example, "horizontal" only means that its direction is more horizontal than "vertical", it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the embodiments of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. It can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

Below in conjunction with accompanying drawing, the present invention is described in further detail:

As shown in FIG. 1 , a heating network circulating water treatment system with electrochemical softening coupled with electro-flocculation includes a booster unit 1, an electrochemical softening unit 2, an electro-flocculation unit 3, a clarification unit 4 and a sludge treatment unit 5, wherein The pressurization unit 1, the electrochemical softening unit 2, the electric flocculation unit 3 and the clarification unit 4 are arranged in sequence along the water flow direction of the circulating water of the heat network. The bypass water outlet of the heating pipe network system is connected to the water inlet of the booster unit 1. The water outlet of the booster unit 1 is divided into two paths, one of which is connected to the first water inlet of the electrochemical softening unit 2. , the other way is connected to the backwash water inlet of the electrochemical softening unit, and the backwash water outlet of the electrochemical softening unit is connected to the water inlet of the sludge treatment unit 5; the water inlet of the electroflocculation unit 3 is connected to the electrochemical softening unit. The water outlet of the unit 2 is connected; the water inlet of the clarification unit 4 is connected to the water outlet of the electric flocculation unit 3, and the water outlet of the clarification unit is connected to the water inlet of the online turbidity monitoring device 6. The outlet of the monitoring device 6 is divided into two channels, one of which is connected to the bypass return port of the heating pipe network system through the second pipeline 62 , and the other is connected to the water inlet of the clarification unit 4 through the first pipeline 61 . The clarification unit 4 is provided with a clarification unit sewage outlet 41, and the clarification unit sewage outlet 41 is arranged in communication with the sludge treatment unit 5, which can ensure the cleanliness of the interior of the unit and avoid the phenomenon of fouling. Preferably, the heating network circulating water treatment system is arranged on the bypass of the heating pipe network system; the pressurization unit 1 is arranged in communication with the bypass water outlet of the heating pipe network system, and the water outlet of the clarification unit 4 is connected to the heating pipe network system. The bypass inlet of the pipe network system is connected. The bottom of the clarification unit 4 is a funnel-type structure, which is convenient for the discharge of sediment.

As shown in FIG. 2 , the electric flocculation unit 3 adopts a parallel-plate modular design, and specifically includes a plurality of first electrode plates 31 , a plurality of second electrode plates 32 and a first control device 33 ; the electric flocculation unit 3 also includes a first conductive rod 311 and the second conductive rod 321 ; a plurality of the first pole plates 31 are evenly spaced and fixed along the axial direction of the first conductive rod 311 , and a plurality of second pole plates 32 are evenly spaced and fixed along the axial direction of the second conductive rod 321 The first conductive rod 311 and the second conductive rod 321 are electrically connected to the first control device 33; when the first conductive rod 311 is connected to the positive pole of the first control device 33, the second conductive rod 321 is When the negative pole is connected, the first pole plates 311 are anodes, and the second pole plates 321 are cathodes; when the first conductive rod 311 is connected to the negative pole of the first control device 33, the second conductive rod 321 is connected to the first control device. When the positive electrode of 33 is turned on, the plurality of first electrode plates 311 are the cathodes, and the plurality of second electrode plates 321 are the anodes. This inversion function is used to reduce the formation of fouling on the electrode surface. The first pole plate 31 and the second pole plate 32 are circular, and a number of first pole plates 31 and a number of second pole plates 32 are arranged alternately; between the first pole plate 31 and the adjacent second pole plate 32 The first gap; the electric flocculation unit 3 is also provided with a first exhaust port 34, a first inspection port 35 and a first sewage outlet 36; the first exhaust port 34 is communicated with the outside atmosphere for discharging the electric flocculation unit 3 The first sewage outlet 36 is used to discharge the sediment in the electric flocculation unit 3, and the first sewage outlet 36 is communicated with the sludge treatment unit 5; the first inspection port 35 is used for overhauling the electric flocculation unit 3. . The electric flocculation unit 3 also includes a first drive motor 37 and a first rotating shaft 38 connected to the first drive motor 37; the first drive motor 37 is electrically connected to the first control device 33; the first pole plate 31 and several The diode plates 32 are all provided with through holes. The through holes may be circular holes. The first rotating shaft 38 is disposed through the through holes. A second gap is provided between the first rotating shaft 38 and the through holes. A plurality of first rotating scrapers 381 are provided at intervals along the axial direction of the first rotating shaft 38 ; the plurality of first rotating scrapers 381 extend along the radial direction of the first rotating shaft 38 . The first rotating scraper 381 is disposed at the first gap; the first rotating scraper 381 is provided with a blade on the side close to the first pole plate 31 and the side close to the second pole plate 32 . The first electrode plate 31 and the second electrode plate 32 are one of soluble electrodes such as iron electrodes or aluminum electrodes. The shell material of the electroflocculation unit 3 is made of rubber-lined carbon steel, and the material of the first rotating shaft 38 and the first rotating scraper 381 is made of 304 stainless steel.

As shown in FIG. 3 , the electrochemical softening unit 2 adopts a coaxial electrode cylinder type modular design, and specifically includes a cathode support frame 211, a cathode 212, an anode support frame 221, an anode 222 and a second control device 24; the cathode support frame 211 and The anode support frame 221 is arranged in coordination, and the cathode support frame is provided with arc-shaped holes to allow the anode support frame to pass through; the cathode 212 is arranged in cooperation with the anode 222, and the cathode 212 includes the cylindrical wall of the electrochemical treatment unit and the curved cathode above the cathode support frame. The anode 222 is the curved anode above the anode support frame 221, and a gap is provided between the anode 222, the curved cathode on the inner side and the cylindrical wall on the outer side. The electrochemical softening unit 2 also includes a second scale scraping device, the second scale scraping device includes a second drive motor 231, a second rotating shaft 232, a scraper connecting rod 233 and a second rotating scraper 234, the extension line of the second rotating shaft 232 Coinciding with the central axes of the cathode 212 and the anode 222, the middle part of the second rotating shaft 232 is connected with the middle part of the scraper connecting rod 233, the lower part of the scraper connecting rod 233 is equipped with a second rotating scraper 234, and the second rotating scraper 234 is located at the anode 222 and the second rotating scraper 234. The gap between the inner curved cathode and the outer cylindrical wall is symmetrically arranged with respect to the axis of the cathode 212 and the anode 222 , and the blade of the second rotating scraper 234 faces the cathode direction. The second scale scraping device can effectively remove the deposits on the cathode surface, improve the current efficiency of the electrochemical softening unit, and reduce energy consumption. The control device 24 is electrically connected to the cathode 212 , the anode 222 , and the second driving motor 231 . The electrochemical softening unit 2 is also provided with a second exhaust port 20 and a second inspection port 25. The second exhaust port 20 is connected to the outside atmosphere for discharging the gas generated in the electrochemical softening unit to ensure the safety of the device. ; The second inspection hole 25 is used for the repair and maintenance work of the electrochemical softening unit. The cathode of the electrochemical softening unit is made of stainless steel or carbon steel, and the anode is made of a titanium electrode, and the surface of the titanium electrode is coated with a ruthenium-iridium or iridium-tantalum mixed metal oxide coating. The second scale scraping device is made of 304 stainless steel. The electrochemical softening unit 2 is provided with a backwash water inlet 26 and a second sewage outlet 27. The backwash water inlet 26 is used to clean the electrochemical softening device, and the backwash water is discharged to the sludge treatment unit through the second sewage outlet 27. 5, can prolong the service life of the device.

A valve 7 is set between each unit to control the opening and closing of the pipeline. The inlet of the bypass booster pump is connected to the heating pipe network system through the bypass outlet valve, one of which is connected to the water inlet of the electrochemical softening unit through the inlet valve of the electrochemical softening unit, and the other is connected to the backwash water inlet valve of the electrochemical softening unit. To the backwash water inlet of the electrochemical softening unit, the backwash drain port of the electrochemical softening unit is connected to the inlet of the sludge treatment device through the backwash drain valve, and the second exhaust port of the electrochemical softening unit is directly connected to the atmosphere through the second exhaust valve. The water production port of the electrochemical softening unit is connected to the water inlet of the electric flocculation unit through the water inlet valve of the electric flocculation unit; the second exhaust port of the electric flocculation unit is connected to the atmosphere through the second exhaust valve, and the sewage outlet of the electric flocculation unit It is connected to the inlet of the sludge treatment device through a blowdown valve, and the water production port of the electroflocculation unit is connected to the water inlet of the clarification unit through the clarification unit inlet valve; The inlet of the turbidity monitoring device is connected to the inlet of the online turbidity monitoring device, and the outlet of the online turbidity monitoring device is divided into two channels, one of which is connected to the heating pipe network system through the bypass return valve, and the other is returned to the return port of the clarifier through the return valve of the clarifier, at the bottom of the clarifier. The sludge discharge port is connected with the inlet of the sludge treatment device through the bottom discharge valve of the clarifier. Both the electrochemical softening unit and the electroflocculation unit are prefabricated modular designs, and the number of modules can be customized according to on-site requirements, with easy construction and flexible assembly.

When the above-mentioned electrochemically coupled electroflocculation treatment system for heat network circulating water is used to purify the heat network circulating water, the specific treatment process is as follows:

Under the action of the bypass booster pump, the circulating water of the heating network is pumped into the electrochemical softening unit 2, and enters through the water inlet below the side of the electrochemical softening unit 2. The electrochemical softening unit 2 operates in a constant current mode, and the softening During the program, the surface current density of the cathode plate is controlled to be 5-30A/m ² , the water inlet valve of the electrochemical softening unit 2, the water outlet valve of the electrochemical softening unit 2, and the exhaust valve of the electrochemical softening unit 2 are kept open, and Keep the cleaning water inlet valve, blowdown valve and drive scraper motor of the electrochemical softening unit 2 in a closed state. At this time, the reactions shown in equations 1 and 2 occur on the cathode surface of the electrochemical softening unit:

2H ₂ O+4e ^- +O ₂ →4OH ^- formula 1

2H ₂ O+2e ^- →2OH ^- +H ₂ ↑ Formula 2

The generated OH ^- forms an alkaline region near the cathode, which increases the solubility of CO ₂ in water, and also promotes the formation of CO ₃ ^2- from HCO ₃ - in the original solution. The reactions are shown in equations 3 and 4:

CO ₂ +OH ^- →HCO ₃ - Formula 3

HCO ₃ -+OH ^- →H ₂ O+CO ₃ ^2- Formula 4

With the occurrence of the electrolysis reaction, Ca ²⁺ and Mg ²⁺ in the water migrate to the cathode under the action of the electric field, and react with a large amount of CO ₃ ^2- near the cathode to react, bond, crystallize, precipitate and remove. The reactions are shown in formulas 5 and 6. shown.

CO ₃ ^2- +Ca ²⁺ → CaCO ₃ Formula 5

2OH ^- +Mg ²⁺ →Mg(OH) ₂ Formula 6

Run the automatic cleaning procedure of the electrochemical softening unit every 90 minutes: close the water inlet valve, water outlet valve and exhaust valve of the electrochemical softening unit 2, open the backwash water inlet valve, backwash drain valve and drive the scraper motor of the electrochemical softening unit 2, The scraper is driven by the driving scraper motor to scrape the wall of the softening unit and the curved cathode inside. The water is discharged to the sludge treatment unit 5 through the backwash drain valve of the electrochemical softening unit 2 .

The softened produced water enters the water inlet of the electric flocculation unit 3 through the water inlet valve of the electric flocculation unit 3. During the operation of the electric flocculation unit 3, the surface current density of the control electrode plate is 30-300A/m ² . Under the action of high-voltage pulsed direct current , the soluble anode of electroflocculation unit 3 loses electrons to form metal cation Fe ²⁺ , which combines with OH ^- in the solution to form a highly active flocculation group, which has a very strong adsorption capacity. , the metal corrosion products in the circulating water of the heat network are adsorbed and co-precipitated to remove them. The electric flocculation unit drives the motor to run continuously, which drives the rotary scraper in the electric flocculation unit 3 to rotate continuously. During the operation of the electric flocculation unit, the reverse period of the electrode is controlled to be 5-30 minutes. Open the sewage outlet at the bottom of the electric flocculation unit every 7-30 days, and the sewage discharge time is 10 to 30 minutes. After the sewage discharge is completed, close the sewage outlet at the bottom of the electric flocculation unit.

The circulating water treated by the electric flocculation unit 3 enters the clarification unit 4, and the circulating water of the heating network treated by the clarification unit 4 is divided into two paths after the turbidity is measured by the online turbidity monitoring device 6, and the turbidity of the produced water in the clarification unit is high. In this case, close the bypass return valve, open the return valve of the clarification unit, and return the produced water from the clarification unit to the water inlet of the clarification unit for further clarification treatment. Open the bypass return valve and return the purified heat network circulating water to the heat supply pipe network system. It is necessary to open the bottom discharge valve of the clarification unit regularly once a day to discharge the sludge at the bottom of the clarification unit.

A system utilizing electrochemical softening coupled with electroflocculation to treat circulating water in a heating network. In an electrochemical softening unit, calcium and magnesium ions in the circulating water in the heating network react on the cathode surface of the electrochemical softening unit to form calcium carbonate and magnesium hydroxide, respectively. Suspended particulate matter, and then through the electro-flocculation unit, the calcium carbonate, magnesium hydroxide suspended particulate matter and the original metal corrosion products in the heating network circulating water and other impurities become large particles, and the heating network circulating water containing large particles enters the clarification unit for precipitation to obtain The supernatant is returned to the heating pipe network system again. The softening of the circulating water of the heating network and the removal of impurities of metal corrosion products can be realized at the same time. The system design is reasonable, the degree of automation is high, and it is not easy to produce secondary pollution, and it is environmentally friendly.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A thermal network circulating water treatment system of electrochemical softening coupled with electric flocculation, is characterized in that, comprises pressurization unit (1), electrochemical softening unit (2), electric flocculation unit (3), clarification unit (4) and a sludge treatment unit (5); the pressurization unit (1), the electrochemical softening unit (2), the electric flocculation unit (3), and the clarification unit (4) are arranged in sequence along the water flow direction of the heating network circulating water; The heating network circulating water treatment system is arranged on the bypass of the heating network circulating system; The electrochemical softening unit (2), the electric flocculation unit (3) and the clarification unit (4) are all communicated with the sludge treatment unit (5); The electric flocculation unit (3) includes a plurality of first electrode plates (31), a plurality of second electrode plates (32) and a first control device (33); a plurality of the first electrode plates (31) and a plurality of the first electrode plates (31) Diode plates (32) are arranged alternately in coordination; a first gap is provided between the first electrode plate (31) and the adjacent second electrode plate (32); a plurality of the first electrode plates (31) and a plurality of The second pole plate (32) is electrically connected to the first control device (33); The first electrode plate (31) and the second electrode plate (32) are both soluble electrodes. 2. A thermal network circulating water treatment system with electrochemical softening coupled with electric flocculation according to claim 1, wherein the electric flocculation unit (3) further comprises a first conductive rod (311) and a second conductive rod rods (321); a plurality of the first pole plates (31) are evenly spaced along the axial direction of the first conductive rods (311), and a plurality of second pole plates (32) are arranged along the axis of the second conductive rods (321) Set to evenly spaced; The first conductive rod (311) and the second conductive rod (321) are electrically connected to the first control device (33); when the first conductive rod (311) is connected to the positive pole of the first control device (33) When connected, when the second conductive rod (321) is connected with the negative electrode of the first control device (33), the plurality of first pole plates (311) are anodes, and the plurality of second pole plates (321) are cathodes; When the first conductive rod (311) is connected to the negative electrode of the first control device (33), and the second conductive rod (321) is connected to the positive electrode of the first control device (33), the first The plate (31) is the cathode, and the plurality of second plates (32) are the anode. 3. a kind of electrochemical softening coupled electric flocculation heat network circulating water treatment system according to claim 1, is characterized in that, the water outlet of described clarification unit (4) is also provided with turbidity monitoring device (6) , the water outlet of the turbidity monitoring device (6) is provided with a first pipeline (61) and a second pipeline (62), and the first pipeline (61) communicates with the water inlet of the clarification unit (4) , the second pipeline (62) is connected to the heating network circulation system. 4. a kind of electrochemical softening coupled electric flocculation heat network circulating water treatment system according to claim 1, is characterized in that, described electric flocculation unit (3) is also provided with the first exhaust port (34), a first inspection port (35) and a first sewage outlet (36); the first exhaust port (34) is communicated with the outside atmosphere, and is used to discharge the gas generated in the electric flocculation unit (3); the first exhaust port (34) The sewage outlet (36) is used to discharge the sediment in the electric flocculation unit (3), and the first sewage outlet (36) is communicated with the sludge treatment unit (5); the first inspection port (35) Used for overhauling the electroflocculation unit (3). 5. A thermal network circulating water treatment system with electrochemical softening coupled with electric flocculation according to claim 1, wherein the electric flocculation unit (3) further comprises a first drive motor (37) and a first drive motor (37) and a first a first rotating shaft (38) to which the drive motor (37) is connected; the first drive motor (37) is electrically connected to the first control device (33); the plurality of first pole plates (31) and the plurality of The diode plates (32) are all provided with through holes, the first rotating shaft (38) is disposed through the through holes, and a second gap is provided between the first rotating shaft (38) and the through holes . 6. A thermal network circulating water treatment system with electrochemical softening coupled with electroflocculation according to claim 5, characterized in that, a plurality of first rotating shafts are arranged at intervals along the axial direction of the first rotating shaft (38). a scraper (381); a plurality of the first rotating scrapers (381) extend along the radial direction of the first rotating shaft (38). 7 . The thermal network circulating water treatment system with electrochemical softening coupled with electric flocculation according to claim 6 , wherein the first rotating scraper ( 381 ) is disposed at the first gap; the first rotating scraper ( 381 ) The scraper (381) is provided with a blade on the side close to the first pole plate (31) and the side close to the second pole plate (32). 8. The thermal network circulating water treatment system of electrochemical softening coupled with electroflocculation according to claim 1, characterized in that the first electrode plate (31) and the second electrode plate (32) are iron electrodes or One of the aluminum electrodes. 9. A method for treating circulating water in a thermal network with electrochemical softening coupled with electroflocculation, characterized in that, adopting the treatment system described in any one of claims 1-8 to purify the circulating water in the thermal network, and in the purification process, control The surface current density of the first electrode plate (31) or the second electrode plate (32) is 30-300 A/m ² ; after the electroflocculation unit (3) is operated for 5-30 minutes, the first electrode plate is (31), the connection modes of the second pole plate (32) and the control device (33) are interchanged.

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