Analysis of the reusability of the energy of the exhaust gas from the calciner for the production of carbon

A calciner is used to produce carbon from anthracite coal. In its working process, a significant amount of energy is lost through its exhaust gas. How much energy can be recovered from the exhaust gas becomes important. To answer this question a method to determine the mass flow rate and the composition of the exhaust gas from a calciner is developed, and a combustion model based on well-stirred reactor is used to obtain the suitable combustor parameters and the amount of the chemical energy which can be released in combustion. As an example to verify the method and the model, the energy utilization ratio of a calciner with power of 1250 kW is investigated. The results show that the method can determine the mass flow rate and the composition of the exhaust gas, and the combustion model is suitable for obtaining reasonable results in determining the volume and the heat duty of the combustor, the air–fuel ratio, and the amount of the chemical energy released. For a calciner with power of 1250 kW, when the temperature of the tail gas after combustion reaches to 135 °C, the energy utilization ratio of the calciner is calculated to be around 77%.