The heating method of the zinc pot directly affects the galvanizing efficiency, energy consumption and process stability.
Author: Marisa
The heating method of the zinc pot directly affects the galvanizing efficiency, energy consumption and process stability. The following are common zinc pot heating methods and their characteristics:
1. Gas/Oil Direct Heating
Principle: Burn natural gas, liquefied gas or diesel, and the flame directly heats the bottom or side wall of the zinc pot.
Applicable scenarios: small and medium-sized zinc pots, batch hot-dip galvanizing (such as steel structures).
Advantages:
Fast heating speed and flexible temperature adjustment.
Low initial investment, suitable for intermittent production.
Disadvantages:
Low thermal efficiency (about 40~50%) and high fuel cost.
Combustion products may contaminate the zinc liquid (the air-fuel ratio needs to be controlled).
2. Electric Heating
(1) Immersion Heating Elements
Principle: Insert the electric heating rod (usually a silicon carbon rod or alloy resistance wire) into the side wall or bottom of the zinc pot.
Applicable scenarios: small zinc pots (such as galvanizing of wires and fasteners).
Advantages:
Precise temperature control (±1°C), no pollution.
Simple structure, easy maintenance.
Disadvantages:
Limited heating power, not suitable for large zinc pots.
The electric heating rod is prone to corrosion and needs to be replaced regularly.
(2) Induction Heating
Principle: Eddy current heating is generated outside the zinc pot through the induction coil.
Applicable scenarios: Medium and large continuous galvanizing lines (such as plates and pipes).
Advantages:
High thermal efficiency (>80%), significant energy saving.
No open flame, high safety, good zinc liquid purity.
Disadvantages:
High initial investment, need to match with variable frequency power supply.
Requirements for the material of the zinc pot (usually heat-resistant steel).
3. Indirect Heating
(1) Thermal Oil Heating
Principle: The burner or electric heater first heats the thermal oil, and then transfers the heat to the zinc pot through the coil.
Applicable scenarios: Precision galvanizing with high requirements for temperature uniformity.
Advantages:
Stable temperature (±2℃), avoiding local overheating.
Reduce zinc liquid oxidation and slag generation.
Disadvantages:
The system is complex and requires an additional heat transfer oil circulation device.
The thermal response speed is slow.
(2) Radiant Tube Heating
Principle: The electric heating element is enclosed in a high-temperature resistant alloy tube and transfers heat by radiation.
Applicable scenarios: Galvanizing process with strict anti-oxidation requirements.
Advantages:
Isolate combustion exhaust gas and high zinc liquid cleanliness.
Longer service life than direct resistance heating.
Disadvantages:
High energy consumption, suitable for small and medium-sized zinc pots.
4. Hybrid Systems
Common combinations:
Gas + electromagnetic induction: Use gas for rapid heating stage and induction heating for energy saving in the insulation stage.
Electric heating + waste heat recovery: Use the waste heat of exhaust gas to preheat the combustion air or zinc pot feed.
Key factors for selection
Zinc pot capacity:
<1 ton: resistance rod or electric radiation tube.
1~10 tons: gas/electromagnetic induction.
>10 tons: electromagnetic induction or thermal oil system.
Production continuity: Induction heating is preferred for continuous galvanizing lines, and gas can be used for intermittent production.
Energy consumption cost: Electric heating is used in areas with abundant electricity, and combustion heating is used in areas with low gas prices.
Environmental protection requirements: Electromagnetic induction or electric heating is cleaner.
Emerging technologies
Microwave heating: In the experimental stage, it can achieve ultra-fast heating of zinc liquid, but the equipment cost is extremely high.
Infrared heating: Used for local heating, energy-saving but not yet popular.
If you need to discuss a certain heating method (such as coil design for induction heating) in depth, you can explain it further!