Volume 22: Sustainable Energy Solutions for a Post-COVID Recovery towards a Better Future: Part V

Reducing Carbon Dioxide Emission in the Process of Oxygen-thermal Coal to Calcium Carbide Polygeneration System Wanyi Xu, Hongxia Wang, Xiaomei Wu, Zaoxiao Zhang

Abstract

With the development of economy, the chemical production from coal is becoming more and more important. Calcium carbide is a typical product from coal in China. There are two ways to produce calcium carbide product. Oxygen-thermal method (OTM) is a potential means of preparing calcium carbide from coal. The reuse of the furnace off-gas is one of the reasons restricting its industrial application. Besides, the CO2 generated during the off-gas reuse process also needs to be captured and utilized. Therefore, this paper proposes two furnace off-gas reuse ways to polygenerate DME and adds Carbon Capture Utilization and Storage (CCUS) system which can be divided into two technologies as Carbon Capture Storage (CCS) and Carbon Capture Utilization (CCU) to reduce carbon emission. First, the Aspen Plus software was used to simulate the whole process of the two production chains, and then the carbon footprint of the production chain was analyzed. Then the CCUS unit was carried out in the system. Finally, the carbon footprint of the production chain before and after the retrofit are compared. CCS system can reduce the total carbon emissions of indirect and direct methods by 41.55% and 60.52%, respectively. As the output of the system increased with the addition of CCU module, the effect of CCU process was evaluated by comparing the different products yield under the same CO2 emission. The result shows that in the direct polygeneration process, the addition of CCS part can increase the product yield by 2.53 times under the same CO2 emission. In the indirect process, the addition of CCS part has the best carbon emission reduction effect, and the output of calcium carbide and dimethyl ether can be increased by 1.71 times under the same CO2 emission. When using CCU technology to transform the polygeneration system, under the same carbon emission, the production of methanol in the direct method is increased to 15.8 times, and the production of dimethyl ether in the indirect method is increased to 2.33 times, which are promising ways to realize carbon reduction in the chemical production.

Keywords CO2 emission, CCUS, polygeneration, calcium carbide, oxygen-thermal method