Preheating plug brick is an important step to ensure its stable use in high temperature environment. The following are specific preheating steps and precautions:

I. Preheating step

(1) natural drying

Before preheating, plug bricks should be naturally dried to remove excess water on the surface and inside. It usually needs to be dried at room temperature for 24-48 hours.

This step can reduce the brick cracking caused by rapid evaporation of water during preheating.

(2) Preparation of preheating equipment

Use electric baking dryer or special preheating furnace for preheating.

Ensure the normal operation of temperature control and ventilation system of preheating equipment.

(3) gradually heating up

Put the plug brick into the preheating equipment and start to heat up slowly. The heating rate should be controlled at 30-50℃ per hour.

For example, it may take 6-10 hours to raise the temperature from room temperature to 300℃, depending on the size and material of the brick.

(4) heat preservation stage

When the temperature reaches 300-400℃, keep the temperature for a period of time (usually 2-3 hours) to ensure the uniform temperature inside the brick body.

This step is helpful to reduce the temperature gradient and avoid thermal stress concentration.

(5) continuously raising the temperature to the use temperature.

After the heat preservation stage, continue to slowly raise the temperature to the actual use temperature of the plug brick (such as 1200-1500℃, depending on the material).

The heating rate should be kept at 50-100℃ per hour to avoid damage to the brick body due to rapid heating.

(6) final heat preservation

After reaching the service temperature, keep warm for a period of time (usually 1-2 hours) to ensure that the brick body can fully adapt to the high temperature environment.

II. Precautions

Temperature control: the heating rate must be strictly controlled in the preheating process to avoid the brick body from cracking due to the rapid temperature change.

Uniform heating: ensure that the plug brick is heated evenly during preheating to avoid local overheating or supercooling.

Good ventilation: Preheating equipment should be well ventilated so that moisture and volatiles can be discharged smoothly.

Check the equipment: Before preheating, check whether the temperature sensor, heating element and ventilation system of the preheating equipment are normal.

Through the above steps and precautions, the plug brick can be effectively preheated, its service life can be prolonged and production efficiency can be improved.