The heating system of hot-dip galvanizing furnace must meet the following requirements: low fuel consumption, i.e. high heat utilization; The heating temperature in the whole galvanizing furnace shall be uniform to avoid overheating and insufficient heating areas, especially local strong flame and radiation high temperature; The temperature can be adjusted at will according to the needs of hot galvanizing production; The outer wall temperature of the zinc pot shall not be too high.

The correct design and operation of the heating system of the hot galvanizing furnace can greatly prolong the service life of the zinc pot, and reduce the amount of zinc slag and zinc ash.

1. Gas and fuel oil heating system

When using gas or fuel oil, the burner is installed on the furnace wall, and the gas or fuel oil is sprayed into the furnace for combustion. The number of burners depends on the type of fuel, the size of zinc pot and the output of zinc plating. The local strong flame shall not directly shoot into the steel zinc pot. The following furnace types are available for reference and selection:

(1) A fire baffle is added between the zinc pot and the flame. A fire baffle is added to protect the zinc pot from direct contact with the flame. The material selection and installation position of the fire baffle shall be appropriate, which can not only block the fire, but also not affect the heating, so as not to reduce the energy efficiency.

(2) Add forced circulation heating system. In order to improve the heating efficiency, a high temperature resistant fan is installed next to the combustion chamber to make the hot gas after combustion circulate quickly in the galvanizing furnace, so that the temperature and heat transfer in the furnace are relatively uniform.

(3) High speed jet burner system is adopted. The high-speed jet burner is installed at the position opposite to the diagonal of the galvanizing furnace body, as shown in Figure 2-1. The flame and combustion furnace gas flow rapidly along the channel surrounding the zinc pot in the zinc plating furnace. The heat conduction is very uniform, eliminating hot spots, and obtaining high heat conduction efficiency. Galvanizing furnace with high-speed jet burner system is referred to as high-speed furnace.

The combustion flame length of flat flame burner is very short and the diameter is large. The partition wall between the burner and the zinc pot avoids the direct contact between the flame and the zinc pot. It heats the wall of the combustion chamber, which generates heat radiation to make the zinc pot obtain the required uniform heating. Galvanizing furnace with flat flame burner system is referred to as flat flame furnace for short.

Galvanizing furnace using high-speed burner and flat flame burner is a popular furnace type at home and abroad.

2. Electric heating system

(1) Induction heating system. The induction heating system of the boiler wall is used. An induction coil is installed outside the boiler wall. After the power is turned on, an induction current is generated on the boiler wall to heat the zinc in the boiler. The heating system does not need a large heating chamber, and the heating efficiency is very high. Because heat is directly generated on the outer wall of the zinc pot, the temperature can be accurately controlled.

(2) Electric heater heating system. The electric heater is made of alloy heating wire (strip) resistant to high temperature oxidation. According to Joule's law Q=I2R, the heat generated by the current flowing through the heating wire can be calculated. About 60% of the heat is transferred to the boiler wall by radiation and 40% by convection. The heating wire is divided into several groups, which can be independently controlled, so the heat energy can be adjusted according to the demand.

Generally, each group of electric heating wires, corresponding supports and insulation materials (aluminum silicate fiber felt) are assembled on the frame of a thin iron plate to form a piece of electric heating plate that can be lifted and installed separately. These electric heating plates are installed on the frame of the galvanizing furnace and connected with the power distribution control device with wires.