Effect of lowering carbonization temperature of coking coal on the reactivity of the coke with CO2

Abstract

Environmental issues are hot topic around the world. Integrated steel mills have various environmental issues in each sector including NOX, SOX, Dust, Odor and Noise, etc. In particular, NOX is the most important issue in the coke making process. NOX is generated during combustion at high temperatures above 1100℃, because the combustion chamber of coke oven is operating at 1000 to 1200℃. In the already constructed coke oven, it is difficult to solve the fundamental problem, which results in decreased production. To solve this issue, the current research aims to find the minimum temperature of the coke oven combustion chamber. Because the decrease in temperature is related to the quality of coke, the optimal temperature is required to find in the conditions that do not affect the quality. To do this, four representative coals being used in actual operation were selected to prepare coal chars in the maximum coking temperature range from 800 to 1200℃. Each char was reacted with CO2 at 1000, 1100, and 1200℃ to measure the carbon conversion. The char of semi-soft coking coal increased the carbon conversion with increasing the coking temperature. However, the carbon conversion evaluated by the char of hard coking coal did not increase the maximum coking temperature range of 1000 to 1200℃. The char of the hard coking coal was further reacted with CO2 below even 1000℃ to find each optimal coking temperature where carbon conversions no longer increased. For the sake of reference, the reactivity of the actual coke used in the operation was compared with those of the chars (CRI), and they was then converted to the coke strength (CSR) . In conclusions, the char of the hard coking coal satisfied the requirement of coke quality, which can reduce the maximum coking temperature below 1000oC.