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1. The purpose of the oven

Before the newly built or repaired kiln is put into use, it must be baked to exclude the free water and crystal water in the lining body after the construction of the refractory to obtain the high temperature performance of the refractory. The correct oven operation is to expel water from the masonry slowly without causing sudden changes in internal stress. Specific oven measures should be formulated to draw the correct oven heating curve to avoid disorderly and arbitrary operations.

Second, the choice of temperature measurement point

   During the oven, the location of the temperature measurement point should be representative, generally set at the location with the highest baking temperature and the fastest heating rate, and the end surface of the thermocouple should be flush with the lining working surface or retracted by about 5 mm Ground temperature reflects liner. In the oven process, when the flue gas temperature rises to the required upper limit, the heating is stopped immediately, and when the flue gas temperature drops to the lower limit of the oven, the heating is started

3. Maintenance before the oven

After the construction of the refractory lining is completed, it should be naturally dried and cured before the ignition oven. Its dryness depends mainly on the ambient temperature and the elapsed time. Generally, after the construction is completed, it can be heated for about 7 days before drying and heating.

4. The three stages of the oven

1. Normal temperature ~ 110 ℃, drying of free water on the surface.

After natural drying and curing, there is still a lot of water in the furnace lining. These free water and crystal water must be discharged in the oven. According to the test of refractory castables at different temperatures, the free water on the surface of the castables evaporates at room temperature ~ 110 ℃.

2. 80 ～ 300 ℃, the discharge of combined water and crystallization water inside the material.

In the oven, the stage of 80 ～ 300 ℃ is the key stage of the oven. This is because the water is transformed into steam at 100 ℃. At this stage, the amount of dehydration is large, the speed of dehydration is fast, and the rate of discharged water has a great influence on the castable. If the water is discharged too quickly, the residual water diffusion rate is not as fast as the surface evaporation rate, and the surface of the material will crack, and the internal water will also be converted into steam by heat, which will expand and cause the castable to crack, so at this stage Two constant temperature treatments were carried out at 110 and 200 ° C to ensure the complete discharge of the combined water and crystallization water inside the material.

3. 300 ～ 600 ℃, the initial crystal transformation and the formation of polymerization.

When the temperature is raised to 300 ℃, free water and crystallization water have been basically discharged, and the initial crystal conversion and polymerization can be completed at 600 ℃.

Fives. Basic principles of oven

1. In order to fully remove the deep free water and crystallization water and complete the crystal form conversion, each temperature must be treated at 150, 250, 300, 450, 600 ℃.

2. In principle, during the entire oven process, the oven temperature can only rise, not fall. If the temperature rise is too fast and exceeds the heating plan of the day, it can only keep the temperature or slow down the heating rate. It is strictly forbidden to sharply rise and fall; when the temperature does not reach the plan of the day, it is strictly prohibited to rush to catch up with the plan. In the temperature area, the temperature must be increased strictly according to plan.

six. Reference graph of oven curve.

Temperature range ℃

Heating rate ℃ / h

Time required h

Cumulative time h

30 ～ 150

15

8

8

150

0

36

44

150 ～ 250

15

6.7

50.7

250

0

twenty four

74.7

250 ～ 300

15

3.3

78

300

0

twenty four

102

300 ～ 450

15

10

112

450

0

twenty four

136

450 ～ 600

15

10

146

600

0

12

158

600 ～ 1100

20

25

183