Manufacture of Formed Coke by Hot-Briquetting Method (VI)
Variation of the Coefficient of Contraction during Carbonization Process of Formed Coke
1971 Volume 50 Issue 8 Pages 655-663
Details
1971 Volume 50 Issue 8 Pages 655-663
From the point of view of the properties of heat shock the coefficient of contraction during carbonization process was investigated by changing coal rank, forming temperature, pre-heating condition, treatment temperature of non-coking coal, heating rate and so on.
The coefficient of contraction shows the first and the second maxima, respectively at about 500°C and 800°C. The value of the first maximum becomes larger with the increase of volatile matter, although the maximum disappears in case of the coal with carbon content more than 90%.
The value of the second maximum is almost independent of the rank of coal, 3-4.5×10-4. And higher temperature during forming green briquette makes the coefficient of contraction smaller. In the case of pre-heating treatment, the highest temperature affects the properties of formed coke more than the time hold. In the case of two fluidized beds-type it was found that higher treatment temperature affects the maxima of the coefficient of contraction, especially the second maximum value, and the heating rate also affects considerably. From the experimental results including the value of thermal stress deduded from the coefficient of contraction, it was found that in order to endure heat shock under the temperature 1000°C the briquette is required to have the maximum value of the coefficient of contraction being smaller than 3×10-4. Then pre-heating treatment is desired and the temperature is to be at least 700°C.
