Daily maintenance and water quality requirements for induction furnace cooling water system
The cooling water system of a medium-frequency induction furnace is the “شريان الحياة” that ensures the safe and stable operation of the equipment. Core components such as the induction coil, خزانة الطاقة, and capacitors generate a significant amount of heat during operation. If cooling fails or water quality is substandard, it can easily lead to scaling, copper tube burn-through, or even severe production accidents like electrical short circuits.
Below is a breakdown of the water quality requirements and daily maintenance technical specifications for the cooling water system, which can be directly utilized as a basis for workshop management standards or technical training:
Water Quality Requirements for the Cooling Water System
To prevent water circuit scaling and electrochemical corrosion, induction furnaces have strict industrial standards for water quality. Given the characteristics of medium-frequency furnaces, it is generally recommended to use softened water or deionized water as the internal circulation medium:
- Hardness (Scale Prevention): Total hardness should be less than 10 mg/L (calculated as CaO). The thermal conductivity of scale is extremely low. Once it adheres to the inner wall of the copper tube, it will cause local overheating of the induction coil, carbonization of the insulation layer, and even melting of the copper tube.
- pHقيمة: Maintain between 7.0 و 8.5. The water should be neutral or slightly alkaline to prevent acidic corrosion on copper fittings, aluminum radiators, and water pump impellers.
- الموصلية الكهربائية (كهربائي أمان): The power cabinet and water-cooled cables have specific insulation requirements for water. The electrical conductivity of the internal circulating water is usually required to be less than 500 ميكرو سيمنز/سم (الجهد العالي, high-power equipment has stricter requirements, عادة أقل من 50 ميكرو سيمنز/سم) to prevent electrical leakage.
- Suspended Solids and Turbidity: The suspended solids content should be less than 10 mg/L, with no visible impurities, رمل, or algae, to prevent clogging of the extremely fine water-cooling channels inside the power cabinet.
- Inlet and Outlet Temperature Control:
- Inlet Temperature: Usually controlled at 5℃ – 35درجه مئوية. Temperatures that are too low can easily cause condensation on the equipment surface (especially on thyristors and capacitors in humid environments), while temperatures that are too high result in insufficient heat dissipation efficiency.
- Outlet Temperature: Strictly controlled below 55℃. Once this critical temperature is exceeded, the chemical reaction rate of calcium and magnesium ion scaling will increase exponentially.
Daily Maintenance Specifications for the Cooling Water System
In the daily management of a foundry workshop, standardized inspection and maintenance procedures should be established to ensure the cooling system is always in optimal working condition:
Pre-shift/Mid-shift Inspections (يوميًا)
- Pressure and Flow Confirmation: Check the operating status of the main water pump to ensure the inlet water pressure is maintained between 0.15 – 0.3 MPa. Observe whether the return water funnels or water flow indicators of each branch are unblocked to ensure there are no dead zones without water.
- مراقبة درجة الحرارة: Real-time comparison of inlet and outlet thermometers. If the outlet temperature of a specific branch (such as a specific group of thyristors or a specific turn of the induction coil) is abnormally high or the water flow becomes noticeably restricted, the furnace must be stopped immediately to check if that water circuit is blocked.
- Leak Detection and Troubleshooting: فحص الملف التعريفي, water-cooled cable interfaces, aging of insulation hoses, and the joints of the power cabinet water distributor to see if there is any water leakage or seepage. Any leaks must be addressed immediately.
Regular Maintenance and Testing (Weekly/Monthly)
- Cleaning Filter Devices: Inspect and clean the Y-type strainers on the main pipeline and each branch weekly to remove intercepted impurities, scale debris, pipe rust, or external flying debris brought in by the cooling tower.
- Testing Emergency Interlock Systems: Manually trigger the water over-temperature alarm, low water pressure alarm, and flow switches regularly every month to verify the sensitivity of the interlock protection system. Ensure that the equipment can instantaneously and automatically cut off the medium-frequency power supply in the event of a sudden water supply failure.
- Checking Backup Water Sources: Verify the liquid level of the high-level emergency water tank, or regularly test-run the backup diesel water pump. This ensures that in the event of a sudden plant-wide power outage, emergency cooling water can be continuously supplied to prevent uncooled water within the furnace from boiling and causing equipment damage.
Periodic Deep Maintenance (Quarterly/Biannually)
- إدارة جودة المياه: For open cooling tower systems, algaecides and corrosion/scale inhibitors need to be added regularly, and blowdown and water replacement should be carried out based on water turbidity. For closed cooling towers, the consumption of internal circulating softened water should be checked regularly and replenished promptly.
- Descaling and Cleaning: If the overall system return water flow is observed to decrease or the equipment temperature rises significantly faster than normal, a shutdown for maintenance should be scheduled. Use a specialized weak-acid environmental descaling agent combined with a circulating pump to perform closed-loop cleaning of the water circuit. After cleaning, the system must be repeatedly flushed and neutralized with clean water until the pH value returns to neutral, and compressed air should be used to blow out any residual moisture.
