根据RH废气分析系统对废气流量及其中所含CO、CO2气体含量的测量，建立了废气分析脱碳数学模型，经验证模型计算值与实际测量值吻合较好；对于成品碳含量≤20×10-6的超低碳钢，模型计算的RH终点碳含量误差在±3ppm之间；废气流量修正系数 采用分段取值更能符合实际情况，RH精炼开始至三分钟内， 为0.35，三分钟后 为0.6；在RH脱碳后期，当废气中CO的含量由峰值降低到5%时，钢水中碳含量的平均值达到13×10-6，已经低于RH终点碳含量的要求值，可以判定RH脱碳结束。

Based on the measure of waste gas flow rate and CO, CO2 content of it by the RH waste gas analysis system, waste gas analysis decarburization mathematic model was established. The calculated results by model inosculated the measured ones. The precision of the end-point carbon content of RH treatment was ±3×10-6 for a carbon range of ULC steel([C] ≤20×10-6). The correction coefficient, , of waste gas flow rate was evaluated by two subsection according with the factual production process. The value of was 0.35 when the RH treatment time was less than 3 minutes, otherwise was 0.6. When the CO content of waste gas decreased to 5% from the maximum at the terminal stage of RH decarburization, the average value of carbon content in the bulk liquid steel was 13×10-6 which was below the requirement content at the end of RH process. Therefore, 5% CO in waste gas at the terminal stage of RH decarburization became a criterion to judge the finish of RH decarburization.