An industrial cooling water on-line dosing device

Abstract

This utility model relates to the field of chemical production technology, specifically an online chemical dosing device for industrial cooling water. It includes a cold water circulation tank, a chiller unit, a heat exchanger, and a dosing system. The outlet of the cold water circulation tank is connected to the inlet of the chiller unit via a first circulation pipe. The inlet of the heat exchanger is connected to the outlet of the chiller unit via a second circulation pipe. The inlet of the cold water circulation tank is connected to the outlet of the heat exchanger via a third circulation pipe. The dosing system includes a dosing tank, a stirring assembly, a water supply pipeline, and a dispensing pipeline. The water supply pipeline is located at the inlet of the dosing tank, the stirring assembly is located inside the dosing tank, and the dispensing pipeline is located at the outlet of the dosing tank and is connected in series with the first circulation pipe. The combined design of the multi-chamber dosing tank, the dedicated stirring assembly, and the water supply pipeline solves the problem of reagent concentration fluctuations. Each chamber corresponds to a set of stirring blades, and with the precise water distribution from the main and branch brine supply pipes, the reagent and brine can be thoroughly and evenly mixed, ensuring the reagent concentration.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, specifically to an online chemical dosing device for industrial cooling water. Background Technology

[0002] In the field of chemical production technology, industrial cooling water systems (including core equipment such as cold water circulation tanks, chillers, and heat exchangers) are crucial auxiliary systems for ensuring continuous and stable production operation. Their main function is to provide cooling for process equipment through the circulation of cooling water, preventing equipment damage due to overheating or affecting product quality. However, during the circulation process, the concentration of calcium, magnesium, chloride, and sulfur ions in the cooling water continuously increases due to factors such as evaporation and concentration, intrusion of air pollutants (such as dust and soluble gases), and potential leakage of materials from heat exchangers. Simultaneously, microorganisms proliferate rapidly, easily forming scale, corrosion layers, and biological slime on the inner walls of pipes and the surfaces of heat exchangers. These problems not only lead to a decrease in heat exchanger efficiency but, with long-term accumulation, can also cause pipe corrosion and perforation, equipment failure, and in severe cases, even production interruption. Therefore, it is essential to add scale inhibitors, corrosion inhibitors, and bactericides to the circulating water through online chemical dosing to inhibit scaling, corrosion, and microbial growth.

[0003] Traditional industrial cooling water chemical dosing is primarily manual: maintenance personnel periodically extract samples from the circulating water, analyze water quality indicators (such as hardness and microbial content) in a laboratory, and then manually calculate and add the chemicals based on the test results. This method has significant drawbacks: firstly, manual sampling and testing have a time lag, failing to reflect changes in circulating water quality in real time, easily leading to untimely or excessive chemical dosing (excessive dosing not only increases chemical costs but may also cause secondary pollution); secondly, manual operation is highly subjective, making it difficult to control the accuracy of dosing, and requires continuous investment of manpower, which does not meet the development needs of automated and efficient chemical production.

[0004] To address the drawbacks of traditional manual dosing, the industry has seen attempts to improve dosing technology through automation. For example, Chinese patent CN214990328U discloses an automatic dosing device for circulating water systems. This device, through a chemical storage tank connected to the cooling tower's makeup water pipeline, pH and conductivity sensors installed on the pipeline valve assembly, and an intelligent electrical control box integrating pH and conductivity meters, achieves automatic detection of circulating water quality. Based on the detection results, it can control the dosing pump for dosing, the makeup water solenoid valve for makeup water, and the drain valve for wastewater discharge, thus overcoming to some extent the shortcomings of traditional manual methods, such as being time-consuming, labor-intensive, and unable to provide real-time monitoring.

[0005] However, the technical solutions in the prior art still have some shortcomings in practical applications of complete chilled water circulation systems (including chillers and heat exchangers) in the chemical industry: 1. Insufficient uniformity of reagent mixing: The dosing device only includes a dosing tank and a dosing pump, and lacks a dedicated stirring mechanism for the reagent and diluent (such as brine). When the reagent and brine need to be diluted in a specific ratio, uneven mixing can easily lead to fluctuations in reagent concentration, thus affecting the treatment effects such as scale inhibition and sterilization. This is especially true for reagents that require precise concentration control (such as oxidizing bactericides), where uneven concentration may directly lead to treatment failure.

[0006] 2. Lack of precise control and switching capabilities for multiple agents: The device does not have a clearly defined chamber design for independent storage and dosing of multiple agents. It only uses a single or simple combination of multiple dosing tanks and pumps, which makes it difficult to achieve independent storage, precise dosing and rapid switching of different types of agents (such as scale and corrosion inhibitors, oxidizing bactericides and non-oxidizing bactericides). In addition, the system does not integrate a flow monitoring and feedback adjustment module, so it cannot monitor the agent dosing flow rate in real time and make dynamic corrections. The dosing accuracy is easily affected by pipeline pressure fluctuations.

[0007] Therefore, in view of the shortcomings of existing automatic dosing devices in terms of uniformity of reagent mixing and precise control of multiple reagents, there is an urgent need to design an online dosing device that can achieve efficient mixing of reagents and independent and precise dosing of multiple reagents, so as to further improve the stability and efficiency of industrial cooling water treatment and ensure the continuous operation of chemical production. Utility Model Content

[0008] The purpose of this invention is to provide an online chemical dosing device for industrial cooling water, which solves the problems mentioned in the prior art in the background section.

[0009] To achieve the above objectives, this utility model provides the following technical solution: an online chemical dosing device for industrial cooling water, comprising a cold water circulation tank, a chiller unit, a heat exchanger, and a dosing system. The outlet of the cold water circulation tank is connected to the inlet of the chiller unit via a first circulation pipe. The inlet of the heat exchanger is connected to the outlet of the chiller unit via a second circulation pipe. The inlet of the cold water circulation tank is connected to the outlet of the heat exchanger via a third circulation pipe. The dosing system includes a dosing tank, a stirring assembly, a water supply pipe, and a chemical outlet pipe. The water supply pipe is located at the inlet of the dosing tank, the stirring assembly is located inside the dosing tank, and the chemical outlet pipe is located at the outlet of the dosing tank and is connected in series with the first circulation pipe.

[0010] Furthermore, a circulation pump is connected in series on the first circulation pipe.

[0011] Furthermore, the stirring assembly includes a motor, a drive shaft, and multiple stirring blades; the inside of the dosing tank is divided into multiple chambers by a partition plate, the motor is located on one side of the vertical wall of the dosing tank, the drive shaft is horizontally rotatable inside the dosing tank and connected to the motor output shaft, and the multiple stirring blades are all located on the drive shaft and are respectively located in the multiple chambers.

[0012] Furthermore, the water supply pipeline includes a main saline water supply pipe and multiple water supply branch pipes; the upper part of the dosing tank is provided with multiple inlets, each inlet corresponding to a multiple chamber, one end of each water supply branch pipe is located in one of the multiple inlets, and the other end of each water supply branch pipe is connected to the main saline water supply pipe through a distributor.

[0013] Furthermore, the drug outlet pipeline includes multiple drug outlet branches and miniature diaphragm pumps respectively installed on the multiple drug outlet branches; the bottom of the dosing tank is provided with outlets corresponding to multiple chambers, one end of the multiple drug outlet branches is connected to the multiple outlets respectively, and the other end of the multiple drug outlet branches is connected in series to the first circulation pipe through a four-way valve and is located on the side of the circulation pump outlet near the cold water circulation tank.

[0014] Furthermore, the cold water circulation tank is also equipped with a demineralized water supply pipe.

[0015] Furthermore, each of the aforementioned drug dispensing branches is equipped with a flow meter.

[0016] Furthermore, valves are installed on the first circulation pipe, the second circulation pipe, the third circulation pipe, the brine replenishment main pipe, the replenishment branch pipe, the medicine outlet branch pipe, and the desalination water replenishment pipe.

[0017] This invention addresses the shortcomings of traditional industrial cooling water dosing methods and the deficiencies of existing automatic dosing devices. By optimizing the system structure design, it achieves deep integration of chemical dosing, water quality control, and the cold water circulation system. Specific beneficial effects are as follows: 1. Addressing the shortcomings of existing automatic dosing devices (such as CN214990328U) that lack a dedicated stirring mechanism and suffer from uneven mixing of chemicals and diluents, this invention solves the problem of chemical concentration fluctuations through a combination design of a multi-chamber dosing tank, a dedicated stirring assembly, and a water supply pipeline. The dosing tank is divided into multiple independent chambers by partitions, which can store different chemicals such as scale inhibitors and corrosion inhibitors, and oxidizing bactericides, respectively, avoiding cross-contamination. Each chamber corresponds to a set of stirring blades (synchronously driven by a motor drive shaft), and with the precise water distribution from the main and branch brine supply pipes (controlled by a distributor to regulate the brine volume in each chamber), the chemicals and brine are thoroughly mixed to ensure uniform chemical concentration. This is particularly suitable for concentration-sensitive chemicals such as oxidizing bactericides, preventing bactericidal failure or localized corrosion due to uneven concentration, and improving the stability of scale inhibition, corrosion inhibition, and bactericidal effects.

[0018] 2. Addressing the shortcomings of existing devices in multi-agent dosing switching capabilities and the lack of flow feedback adjustment, this invention achieves on-demand dosing and precise control of multiple agents through independent dosing branches, flow monitoring, and a PLC intelligent control system. Each chamber corresponds to an independent dosing branch, which integrates an electric valve, a miniature diaphragm pump, and a glass tube rotor flowmeter, allowing for individual control of the start and stop of dosing for a specific type of agent. The PLC control system uses a PID algorithm to compare the target dosing amount with the actual flow rate of the flowmeter, automatically adjusting the opening of the electric valve to avoid overdosing or underdosing as is common in traditional manual dosing. This reduces the cost of agents in case of overdosing and also minimizes secondary pollution of circulating water caused by agent residue. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a system block diagram of the present invention.

[0020] In the diagram: 1. Cold water circulation tank; 2. Chiller unit; 3. Heat exchanger; 4. First circulation pipe; 5. Second circulation pipe; 6. Third circulation pipe; 7. Dosing tank; 8. Circulation pump; 9. Motor; 10. Drive shaft; 11. Agitator blade; 12. Brine makeup water main pipe; 13. Makeup water branch pipe; 14. Dosing water branch pipe; 15. Miniature diaphragm pump; 16. Demineralized water makeup water pipe; 17. Flow meter; 18. Valve. Detailed Implementation

[0021] The following is in conjunction with the appendix Figure 1-2 This document provides a detailed description of the specific implementation method of an online chemical dosing device for industrial cooling water according to this utility model. Based on the technical solution of the utility model patent and combined with the actual application scenarios in the chemical industry, this embodiment clarifies the material selection, specifications, specific connection structures, and sealing measures for each component, ensuring stable operation, corrosion resistance, and compliance with explosion-proof and leak-proof requirements.

[0022] The industrial cooling water online dosing device of this embodiment mainly includes two modules: a cold water circulation system and a dosing system. The cold water circulation system consists of a cold water circulation tank 1, a chiller unit 2, a heat exchanger 3, a circulation pump 8, and first circulation pipes 4, second circulation pipes 5, and third circulation pipes 6, realizing the cooling, transportation, and circulation of cooling water. The dosing system consists of a dosing tank 7, a stirring assembly (motor 9, drive shaft 10, stirring blades 11), a water supply pipeline (brine water supply main pipe 12, water supply branch pipes 13), a chemical outlet pipeline (chemical outlet branch pipe 14, micro diaphragm pump 15, flow meter 17, chemical outlet branch pipe valve, electric four-way valve), and a PLC control system, realizing the preparation, stirring, precise dosing, and on-demand switching of chemicals. There are also valves 18 on each pipeline and a demineralized water supply pipe 16 to ensure system flow control and water supply requirements. Details are as follows: The cold water circulation tank 1 is constructed of 316L stainless steel for both the tank body and top end cap, offering excellent corrosion resistance and suitability for use with trace amounts of acidic / alkaline media that may be present in chemical environments. It features a cylindrical, enclosed structure with an outer diameter of 1200mm, an inner wall height of 1800mm, and an effective volume of 1.8m³. 3 The tank body has a wall thickness of 8mm, and the top arc-shaped end cap has a wall thickness of 10mm. The end cap is connected to the tank body by circumferential full welding (welding standard GB / T 985.1-2008). After welding, a permeation test (PT) is performed to ensure there are no weld leaks or pores. Two DN80 interfaces are opened at the top (connecting to the demineralized water supply pipe 16 and the third circulation pipe 6 respectively). 316L stainless steel flanges (standard GB / T 9119-2010, model DN80 PN1.6MPa, sealing surface is raised face RF) are welded at the interfaces. The welding height between the flange and the tank body end cap is 6mm. After welding, a water pressure test is performed (test pressure 0.3MPa, pressure held for 30min with no pressure drop). The demineralized water supply pipe 16 (316L stainless steel pipe, DN50, wall thickness 3.5mm) is fastened to the tank body flange with M16×50 316L stainless steel bolts (torque 35N・m). Fluororubber gaskets (model GB / T) are sandwiched between the flanges. 4622.2-2008, DN80×3mm, temperature resistance -20℃-200℃), to prevent desalination water leakage.

[0023] Chiller Unit 2 uses a screw-type industrial chiller (brand: Gree Industrial), model LSBLG130M, suitable for cooling water requirements of 5℃; cooling capacity 130kW, rated outlet water temperature 5℃, rated return water temperature 10℃, input power 40kW, power supply 380V / 50Hz; built-in plate evaporator (316L stainless steel plate, heat exchange area 20㎡) and condenser (304 stainless steel plate, heat exchange area 25㎡), evaporator inlet and outlet diameter DN100, condenser inlet and outlet diameter DN125; chiller unit 2 inlet is connected to the first circulation pipe 4 It is connected to the outlet of the circulating pump 8, and the outlet is connected to the inlet of the heat exchanger 3 through the second circulating pipe 5; both the first circulating pipe 4 and the second circulating pipe 5 are made of 304 stainless steel pipe (DN100, wall thickness 4.5mm). The pipe and the unit interface flange (304 stainless steel, DN100PN1.6MPa) are fully welded (welding height 6mm, PT test). An asbestos rubber gasket (GB / T4622.1-2009, DN100×3mm) is sandwiched between the flanges and fastened with M20×60 304 stainless steel bolts (torque 50N・m).

[0024] Heat exchanger 3 is a detachable plate heat exchanger, model M10-B, suitable for heat exchange requirements of industrial cooling water and process materials; heat exchange area is 15㎡, plate material is 316L stainless steel (thickness 0.5mm, corrugation angle 30°), and sealing gasket material is EPDM rubber (temperature resistance -20℃-150℃, aging resistance); the inlet and outlet diameters are both DN80, and the interface flange is 304 stainless steel (PN1.6MPa); the inlet of heat exchanger 3 is connected to the outlet of chiller unit 2 through the second circulation pipe 5 (304 stainless steel, DN100), and the outlet is connected to the inlet of chilled water circulation tank 1 through the third circulation pipe 6 (304 stainless steel, DN80, wall thickness 4.0mm); the pipes and heat exchanger flanges are fixed by welding, with EPDM gaskets (DN80×3mm) sandwiched between the flanges, and tightened with M16×50 304 stainless steel bolts (torque 35N・m).

[0025] Circulating pump 8 is a horizontal single-stage single-suction explosion-proof centrifugal pump, model ISW80-160 (I), suitable for the explosion-proof requirements of chemical workshops (explosion-proof rating Ex d IIB T4 Gb); flow rate 50 m³ / h. 3 The pump has a head of 32m, a rated power of 7.5kW, and a speed of 2900r / min. The pump body, impeller, and pump shaft are all made of 304 stainless steel. The mechanical seal is model BIA-80 (silicon carbide dynamic ring + silicon carbide stationary ring, fluororubber O-ring). The inlet of the circulating pump 8 is connected to the outlet flange of the cold water circulation tank 1 through the first circulation pipe 4 (304 stainless steel, DN80). The pump outlet is connected to the inlet flange of the chiller unit 2 through the first circulation pipe 4. The pump inlet and outlet flanges (304 stainless steel, DN80PN1.6MPa) are fully welded to the pipeline flanges, and fluororubber gaskets (DN80×3mm) are sandwiched between the flanges. They are fastened with M16×50 304 stainless steel bolts (torque 35N・m). The pump base is made of 40mm thick Q235 steel plate and is fixed to the concrete foundation with 4 M20×80 expansion bolts. Rubber shock-absorbing pads (50mm×50mm×10mm) are added between the base and the pump body to reduce operating noise.

[0026] The first circulation pipe 4 (DN80), the second circulation pipe 5 (DN100), and the third circulation pipe 6 (DN80) are all made of 304 stainless steel pipe (GB / T). 14976-2012), with wall thicknesses of 4.0mm, 4.5mm, and 4.0mm respectively; 304 stainless steel elbows (90°, R=1.5D) are used at pipe bends, connected by welding (welding height 5mm, PT test); 304 stainless steel flange ball valves, model Q41F-16P, nominal pressure 1.6MPa, sealing surface material PTFE (polytetrafluoroethylene), resistant to acid and alkali corrosion, are installed on each circulation pipe; the first circulation pipe 4 (DN80) is equipped with a DN80 valve, the second circulation pipe 5 (DN100) is equipped with a DN100 valve, and the third circulation pipe 6 (DN80) is equipped with a DN80 valve; valve 18 is fastened to the pipe flange with M16×50 (DN80) and M20×60 (DN100) 304 stainless steel bolts, with torques of 35N·m and 50N·m respectively, and fluororubber gaskets of corresponding specifications are sandwiched between the flanges.

[0027] The dosing tank 7 is constructed from 304 stainless steel sheet, with an overall rectangular structure measuring 1200mm × 500mm × 600mm (length × width × height) and a total volume of 360L. The tank walls are 5mm thick, the bottom is 8mm thick, and the top is 5mm thick. The interior is divided into three independent chambers (each 120L) along its length by two 5mm thick 304 stainless steel partition plates. The partition plates are continuously and fully welded to the bottom, top, and side walls (welding height 5mm). A hydrostatic test (0.2MPa) is performed after welding. (Pressure holding for 30 minutes with no cross-contamination); Each chamber has a 150mm diameter feed port at the top, with a 304 stainless steel short pipe (DN150, 50mm length, 5mm wall thickness) welded to the feed port; the top of the short pipe is fitted with a 304 stainless steel sealing cap (5mm thickness, 160mm diameter), the sealing cap and the short pipe are connected by M160×2 fine thread, the thread is wrapped with PTFE raw material tape (20mm width, 0.1mm thickness), and a EPDM rubber sealing gasket (160mm diameter × 3mm) is clamped to ensure a seal to prevent the volatilization of the agent; Each chamber has a DN20 drain port at the bottom corner, with a 304 stainless steel short pipe (30mm length) welded to the drain port and a 304 stainless steel ball valve (Q11F-16P, DN20) installed for chamber cleaning and drainage.

[0028] Motor 9 is an explosion-proof three-phase asynchronous motor, model YBX3-100L1-4, suitable for chemical explosion-proof environments (explosion-proof rating Ex d IIB T4 Gb); rated power 0.75kW, rated speed 1440r / min, rated voltage 380V, power factor 0.82, protection rating IP54; the motor is fixed to one side vertical wall of the dosing tank 7 by a 304 stainless steel motor bracket (thickness 10mm, size 200mm×150mm×100mm); the bracket is fastened to the dosing tank wall by 4 M12×30 304 stainless steel bolts (torque 25N・m), and nitrile rubber washers (2mm thick) are added at the bolt holes to prevent the agent from penetrating and corroding the bolts.

[0029] The drive shaft 10 is made of high-quality 45# carbon steel (GB / T 699-2015), with a shaft diameter of 20mm and a total length of 600mm. The shaft surface is chrome-plated (plating thickness 0.05mm) to improve rust prevention and wear resistance. One end of the drive shaft 10 is connected to the motor output shaft via an HL2 type flexible coupling. The coupling is made of 45# steel, with a nominal torque of 16N·m, and the shaft hole diameters match the motor output shaft (19mm) and the drive shaft (20mm) respectively. The coupling is fixed to the two shafts with M8×12 304 stainless steel set screws (the ends of the set screws are milled with anti-slip grooves) to ensure no slippage. A single-end mechanical seal (model BIA-20, brand: John Crane) is used where the drive shaft 10 passes through the side wall of the dosing tank to prevent chemical leakage. The sealing cavity is made of 304 stainless steel, and both the dynamic and static rings are made of silicon carbide. The auxiliary sealing component is a fluororubber O-ring (AS568-214, inner diameter 25.4mm×). The wire diameter is 3.53mm; the mechanical seal is fixed to the mounting hole (22mm diameter) on the side wall of the dosing tank via a sealing seat (304 stainless steel, 8mm thick). The sealing seat is fastened to the tank wall with 6 M8×20 304 stainless steel bolts (torque 15N・m). A fluororubber gasket (2mm thick) is sandwiched between the sealing seat and the tank wall. The sealing cavity is filled with No. 46 anti-wear hydraulic oil (Great Wall L-HM46), which is replenished every 3 months to ensure sealing and lubrication.

[0030] Each chamber corresponds to one set of stirring blades 11, and each set contains two blades (symmetrically distributed, with an included angle of 180°). The blades are made of 304 stainless steel plate (thickness 3mm) and are rectangular in shape (100mm×50mm). The blade ends are bent upward at 15° to improve stirring efficiency. The stirring blades are fixed to the drive shaft 10 by welding (welding height 3mm, full welding). The center distance of each set of stirring blades 11 from the end of the drive shaft is 150mm, 300mm, and 450mm respectively (corresponding to 3 chambers), ensuring that the blades stir in the center of the chamber without dead corners.

[0031] The main brine supply pipe 12 uses UPVC-U water supply pipe (GB / T 10002.1-2006), model De50 (outer diameter 50mm, wall thickness 4.6mm), with a length of 5m (adjustable according to the on-site installation distance). One end of the main pipe connects to the workshop's brine supply network (pressure 0.4MPa), and the other end connects to three branch pipes 13 via a PVC three-way connector (model De50×32×3, brand: Liansu). The branch pipes 13 use UPVC-U water supply pipe, model De32 (outer diameter 32mm, wall thickness 3.2mm), each with a length of 1.2m. m corresponds to 1 chamber; the distributor is connected to the main pipe and branch pipes by socket joints, and the interface is coated with UPVC special adhesive (Deli DL-801), with a curing time of ≥24h. After curing, a 0.2MPa air pressure test is performed (pressure holding for 10min without leakage); the end of each branch pipe extends to the top of the corresponding chamber and is connected to the 304 stainless steel short pipe (De32, length 30mm) at the chamber inlet by a PVC flange (DN32PN1.0MPa), with a rubber gasket (2mm thick) sandwiched between the flanges, and fastened with 4 M6×16 PVC bolts; each water supply branch pipe 13 is equipped with a PVC ball valve (model Q11F-16S, DN32, brand: Liansu) for individually adjusting the brine supply of each chamber.

[0032] The drug outlet branch pipe 14 uses a UPVC-U water supply pipe (resistant to chemical corrosion), model De20 (outer diameter 20mm, wall thickness 2.0mm), each pipe is 1.5m long and corresponds to one chamber; each chamber of the dosing tank 7 has a DN20 outlet at the bottom, and a 304 stainless steel short pipe (40mm long) is welded to the outlet. The short pipe is connected to the drug outlet branch pipe 14 by a socket joint, and the joint is coated with UPVC adhesive (cured for 24 hours); the other end of the branch pipe converges to an electric four-way valve (De20×4, brand: Airtac). The outlet of the four-way valve is connected to the first circulation pipe 4 through a De20 UPVC pipe (the connection position is located between the inlet of the circulation pump 8 and the outlet of the cold water circulation tank 1). The electric four-way valve is an explosion-proof electric UPVC four-way valve (brand: Airtac, model 4V230E-08); nominal diameter DN20, valve body material UPVC, drive method is pilot-operated solenoid valve (explosion-proof rating Ex d IIB T4 Gb), control signal is PLC digital output (24V DC), with 3 inlets (corresponding to 3 chamber drug outlet branches) and 1 outlet (connected to the first circulation pipe 4), switching response time ≤0.5s, no drug cross-contamination; the 3 inlets are respectively connected to 3 drug outlet branches 14 (De20) with socket connection (coated with UPVC adhesive), and the outlet is connected to the UPVC pipe leading to the first circulation pipe 4; the wiring terminals are connected to the PLC digital output module through an explosion-proof sealed terminal box (model JH-AG, Ex d IIB T4) to prevent drug corrosion of the wiring. The outlet branch pipe valve is an explosion-proof electric UPVC ball valve (brand: Shanghai Hugong, model Q911F-16S); nominal diameter DN20 (compatible with the De20 pipe diameter of outlet branch pipe 14), nominal pressure 1.6MPa, sealing surface material PTFE (polytetrafluoroethylene), drive motor is explosion-proof (Ex d IIB T4 Gb), rated voltage 220V, control signal 4-20mA (receives PLC analog output), opening adjustment accuracy ±1%; the valve is installed on the outlet branch pipe 14 between the inlet end of the miniature diaphragm pump 15 and the outlet end of the dosing tank 7 chamber, and is connected to the pipeline by a socket type (the interface is coated with UPVC adhesive and cured for 24 hours); after connection, a sealing test is performed: close the valve, inject clean water into the corresponding chamber to 1 / 2 liquid level, maintain pressure for 1 hour, and it is qualified if there is no dripping or seepage at the interface; it is linked with the flow meter 17 to realize automatic flow regulation; during maintenance, the corresponding chamber's drug passage is isolated; it assists in controlling the initial flow of the drug to avoid fluctuations.

[0033] The miniature diaphragm pump 15 is a corrosion-resistant miniature diaphragm pump, model GMI-40, suitable for chemical delivery (acid and alkali resistant, PVDF pump head); flow range 0.5-4L / h, rated pressure 0.4MPa, motor power 120W, power supply 220V, protection level IP65; the pump inlet and the chemical outlet branch pipe 14 (De20) are connected by G1 / 4 thread, and the thread is wrapped with PTFE raw material tape; the pump outlet and the subsequent chemical outlet branch pipe 14 are also connected by G1 / 4 thread; the pump base is fixed to the side wall bracket (304 stainless steel, 5mm thick) of the dosing tank 7 by two M5×10 plastic bolts, and the bracket is welded to the dosing tank wall.

[0034] Flowmeter 17 is a glass tube rotor flowmeter, model LZB-15, suitable for small-flow-rate pharmaceutical metering; it has a 4-20mA signal output module (integrated with the flowmeter design), which can convert the real-time flow value into a standard current signal for transmission to the PLC; the range is 0.1-1L / h, the glass tube is made of borosilicate glass (impact resistant), the float is made of 304 stainless steel, and the scale accuracy is ±5%; the inlet and outlet of flowmeter 17 and the pharmaceutical branch pipe 14 (De20) are connected by a socket type, and a rubber sealing ring (1.5mm thick) is added at the interface, which is tightened by plastic nuts at both ends of the flowmeter to ensure a leak-free seal; the flowmeter is installed vertically (vertical deviation ≤1°) for easy reading.

[0035] The demineralized water supply pipe 16 is made of 304 stainless steel (GB / T 14976-2012), model DN50, wall thickness 3.5mm, and length 3m; one end is connected to the workshop demineralized water supply network (pressure 0.3MPa), and the other end is connected to the DN50 interface flange at the top of the cold water circulation tank 1 through a 304 stainless steel flange (DN50PN1.6MPa); a fluororubber gasket (DN50×3mm) is sandwiched between the flanges and fastened with M12×40 304 stainless steel bolts (torque 25N・m); a 304 stainless steel ball valve (Q41F-16P, DN50) is installed on the pipeline to control the water supply.

[0036] The PLC control system is adapted to the explosion-proof and stable operation requirements of chemical plants. It uses an intrinsically safe PLC controller (Siemens, model S7-1200F), equipped with explosion-proof analog input / output modules (SM 1234, 4 AI / 2 AO channels), digital input / output modules (SM1223, 8 DI / 8 DO channels), and an explosion-proof human-machine interface (HMI, model KTP700F, 7-inch touchscreen, IP65 protection rating). It receives 4-20mA signals from flow meters and water quality detection signals (such as online hardness meters and residual chlorine meters, 4-20mA), and outputs control signals to electric valves (4-20mA) and electric four-way valves (24V DC) to achieve automatic adjustment of chemical flow and switching of chemical types. The flow meter signal module and water quality sensor are connected via shielded cables (RVVP 2×0.75mm). 2 The PLC analog input module is connected to the flow meter 17 (Ex d IIB); electric valves and electric four-way valves are connected to the PLC analog / digital output module via shielded cables; all wiring terminals use explosion-proof sealed terminal boxes (JH-AG, Ex d IIB T4); an independent explosion-proof power supply (KDW127 / 24B, input 127V AC, output 24V DC, 100W) is used, isolated from the main power supply; an 8GB SD card is built-in to store flow rate, water quality, and valve opening data in real time (storage period 1min), and can review 3 months of historical data; the PLC uses a PID algorithm to compare the actual flow rate fed back by the flow meter 17 with the target flow rate set by the HMI, and automatically adjusts the opening of the electric valve (if the actual flow rate is < target value, increase the valve opening; otherwise, decrease it), ensuring that the flow deviation is ≤±3%; when the flow rate is abnormal (<0.05L / h or >1.2L / h), the PLC triggers the HMI alarm and closes the corresponding valve; the PLC presets the correspondence between reagents and water quality indicators (e.g., hardness >300mg / L). After adding scale and corrosion inhibitors and receiving signals from the water quality sensor, the PLC outputs a digital signal to control the four-way valve to switch the passage (e.g., if the hardness exceeds the standard, the branch pipe of the scale and corrosion inhibitor is opened); when switching manually, after the HMI selects the target agent, the PLC first closes the current passage, delays for 2 seconds to drain the residual agent, and then opens the new passage, synchronously adjusting the initial opening of the corresponding electric valve.

[0037] The connection relationship and specific working process of this utility model are as follows: I. Overall Connection Relationship 1. Cold water circulation path: Cold water circulation tank 1 → First circulation pipe 4 (including circulation pump 8 and valve 18) → Chiller unit 2 → Second circulation pipe 5 (including valve 18) → Heat exchanger 3 → Third circulation pipe 6 (including valve 18) → Cold water circulation tank 1, forming a closed loop.

[0038] 2. Dosing path: Dosing tank 7 chambers → Dosing branch pipe 14 (including electric valve, micro diaphragm pump 15, flow meter) → Electric four-way valve → First circulation pipe 4 (outlet section of circulation pump 8) → into cooling water circulation.

[0039] 3. Control path: PLC control system → receives signals from flow meter / water quality sensor → outputs control signals to electric valve / electric four-way valve → realizes flow regulation and reagent switching.

[0040] 4. Water replenishment path: Demineralized water replenishment pipe 16 → Cold water circulation tank 1 (to replenish circulating water loss); Brine replenishment main pipe 12 → Diverter → Replenishment branch pipe 13 → Each chamber of the dosing tank 7 (for preparing medicines).

[0041] II. Specific Work Process 1. Cooling water circulation starts: Open the valve on the demineralized water supply pipe 16 and inject demineralized water into the cold water circulation tank 1 until the level gauge shows 80% (a magnetic float level gauge, model UHZ-58 / C, with a range of 0-1800mm, is installed on the side wall of the tank); start the circulation pump 8 and open the valves on the first circulation pipe 4, the second circulation pipe 5, and the third circulation pipe 6. The demineralized water is pressurized by the circulation pump and sent to the chiller unit 2; start the chiller unit 2 and set the outlet water temperature to 5℃. The unit cools the water to 5℃ through the evaporator and then sends it to the heat exchanger 3; the 5℃ cooling water exchanges heat with the chemical process materials in the heat exchanger 3 (absorbing heat from the materials), and the water temperature rises to 10℃. Then, it flows back to the cold water circulation tank 1 through the third circulation pipe 6 to complete one cycle.

[0042] 2. Preparation and Dosing of Reagents: Based on water quality test results (such as hardness and microbial content), add scale and corrosion inhibitors (such as HEDP), oxidizing bactericides (such as sodium hypochlorite), and non-oxidizing bactericides (such as isothiazolinone) to the three chambers of the dosing tank 7, respectively; close all electric valves on the outlet branch pipes 14, open the valves on the brine supply main pipe 12 and the corresponding supply branch pipes 13, and inject brine (concentration 5%) into each chamber until the level gauge (magnetic float level gauge, range 0-600mm, chamber-mounted) shows 70%, then close the supply valves; start the motor 9 of the stirring assembly, driving the shaft 10... The stirring blade 11 rotates (1440 r / min) to mix the agent and brine evenly (stirring time 15 min). The operator selects the target agent (e.g., scale and corrosion inhibitor) via the PLC's HMI and inputs the target dosage (e.g., 1 L / h). After receiving the command, the PLC outputs a digital signal to control the electric four-way valve to switch to the scale and corrosion inhibitor outlet branch, and simultaneously opens the corresponding electric valve of the outlet branch (initial opening 50%), starting the micro diaphragm pump 15. The flow meter 17 collects the actual flow rate in real time (e.g., 0.8 L / h, corresponding to a 16 mA signal) and transmits it to the PLC. The PLC calculates the deviation (0.8 L / h < 1 L / h) using a PID algorithm and outputs a control signal to increase the opening of the electric valve (e.g., from 50% to 65%), so that the actual flow rate gradually approaches 1 L / h, and the deviation is controlled within ±2% after stabilization. During operation, the online hardness meter monitors the hardness of the circulating water in real time: if the hardness drops to 200 mg / L (meeting the standard), the PLC... The system automatically reduces the target dosage of scale and corrosion inhibitor to 0.5 L / h and simultaneously adjusts the electric valve opening to 30%. If the hardness rises again to 300 mg / L, the PLC automatically restores the dosage to 1 L / h. When switching agents (e.g., from scale and corrosion inhibitor to oxidizing bactericide), the PLC first closes the electric valve of the scale and corrosion inhibitor branch pipe, stops the corresponding micro diaphragm pump 15, and empties the pipeline after a 5-second delay. Then, it outputs a signal to control the electric four-way valve to switch to the oxidizing bactericide outlet branch pipe passage, opens the electric valve of this passage (initial opening 40%), starts the corresponding micro diaphragm pump 15, and adjusts the opening to the target value (e.g., 0.5 L / h) according to the flow meter signal.

[0043] 3. System monitoring and maintenance: Maintenance personnel can remotely view real-time data such as flow rate of each drug outlet branch pipe, opening degree of electric valve, current passage of four-way valve, and water quality indicators through HMI, without the need for on-site inspection; when situations such as flow deviation exceeding ±5%, four-way valve switching failure, or water quality exceeding the standard for 10 minutes occur, the PLC triggers the HMI red alarm pop-up window and triggers the on-site audible and visual alarm (BBJ-2, ​​Ex d IIBT4), and at the same time sends an alarm SMS to the maintenance personnel's mobile phone via GSM module.

[0044] Weekly HMI-based four-way valve switching test: PLC controls the four-way valve to switch three channels sequentially, pausing for 30 seconds on each channel, to check the smoothness of the switching and whether there is any cross-contamination. The test data is automatically stored to an SD card.

[0045] The linkage accuracy between the flow meter and the electric valve is calibrated monthly via HMI: input calibration values ​​(such as 0.5L / h, 1L / h), PLC controls the valve opening from 20% to 80%, records the actual flow rate at different openings, automatically generates calibration curves, and corrects control parameters.

[0046] This specific implementation method, by clearly defining the materials, models, and connection and sealing details of each component, ensures that the device meets the requirements of corrosion resistance, explosion prevention, and leak prevention in the chemical industry. It can stably realize the circulation and cooling of industrial cooling water and online dosing, ensuring the continuous operation of chemical production.

Claims

1. An online chemical dosing device for industrial cooling water, comprising a cold water circulation tank (1), a chiller unit (2), a heat exchanger (3), and a dosing system, wherein the outlet of the cold water circulation tank (1) is connected to the inlet of the chiller unit (2) via a first circulation pipe (4), the inlet of the heat exchanger (3) is connected to the outlet of the chiller unit (2) via a second circulation pipe (5), and the inlet of the cold water circulation tank (1) is connected to the outlet of the heat exchanger (3) via a third circulation pipe (6), characterized in that, The dosing system includes a dosing tank (7), a stirring assembly, a water supply pipeline, and a drug outlet pipeline; the water supply pipeline is located at the inlet of the dosing tank (7), the stirring assembly is located inside the dosing tank (7), and the drug outlet pipeline is located at the outlet of the dosing tank (7) and is connected in series with the first circulation pipe (4).

2. The online dosing device as described in claim 1, characterized in that, A circulation pump (8) is also connected in series on the first circulation pipe (4).

3. The online dosing device as described in claim 1, characterized in that, The stirring assembly includes a motor (9), a drive shaft (10), and multiple stirring blades (11); the inside of the dosing tank (7) is divided into multiple chambers by a partition plate, the motor (9) is located on one side of the vertical wall of the dosing tank (7), the drive shaft (10) is horizontally rotatable inside the dosing tank (7) and connected to the output shaft of the motor (9), and the multiple stirring blades (11) are all located on the drive shaft (10) and are respectively located in multiple chambers.

4. The online dosing device as described in claim 1, characterized in that, The water supply pipeline includes a main saline water supply pipe (12) and multiple water supply branch pipes (13); the upper part of the dosing tank (7) is provided with multiple inlets, each of which corresponds to a multiple chamber, and one end of each of the multiple water supply branch pipes (13) is located in one of the multiple inlets, and the other end of each of the multiple water supply branch pipes (13) is connected to the main saline water supply pipe (12) through a distributor.

5. The online dosing device as described in claim 3, characterized in that, The drug outlet pipeline includes multiple drug outlet branches (14) and miniature diaphragm pumps (15) respectively installed on the multiple drug outlet branches (14); the bottom of the dosing tank (7) is provided with outlets corresponding to multiple chambers, one end of the multiple drug outlet branches (14) is connected to the multiple outlets, and the other end of the multiple drug outlet branches (14) is connected in series to the first circulation pipe (4) through a four-way valve and is located on the side of the circulation pump (8) outlet near the cold water circulation tank (1).

6. The online dosing device as described in claim 2, characterized in that, The cold water circulation tank (1) is also equipped with a demineralized water supply pipe (16).

7. The online dosing device as described in claim 5, characterized in that, Each of the aforementioned drug outlet branches (14) is equipped with a flow meter (17).

8. The online dosing device as described in claim 6, characterized in that, Valves (18) are provided on the first circulation pipe (4), the second circulation pipe (5), the third circulation pipe (6), the brine replenishment main pipe (12), the replenishment branch pipe (13), the medicine outlet branch pipe (14), and the desalination water replenishment pipe (16).

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