Key Aspects of Slag Viscosity in Slagging Gasifiers

• Applicant: Dr.-Ing. Stefan Guhl
• Subject Area: Chemical and Thermal Process Engineering
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392218733

In China, coal based gasification is one of the main technologies for the production of chemical base components and transportation fuels. Germany is a traditional location for gasification process development and plant engineering.Entrained flow gasification is regarded as the predominant choice for coal conversion. From the perspective of coal chemistry, slag viscosity is the key parameter for running the gasifier, but several key aspects of slag viscosity during slag tapping are unclear, even from a scientific perspective. The entrained flow gasifier faces the risk of shut-down, while the slag viscosity is not in the suitable range. In this Joint Sino-German Research Project, the following key aspects and objectives are considered: (1) The influence of atmosphere and cooling rate on slag viscosity is systematically investigated. A measurement method will be developed to consider real gasifier conditions and allow for the direct transfer of the measurement results to the practical application. (2) The optical observed flow velocity is correlated with viscosity. The results will help to understand the slag flow behavior directly. (3) The crystallization and metal precipitation leads to slag blockages in the gasifier. With methods like in-situ XRD, a microscope coupled with heat stage, DTA and SEM-EDX/WDX parameters affecting slag crystallization, iron precipitation, and finally the viscosity will be quantified. A prediction method based on key figures will be developed to establish guidance for proper coal selection. (4) In order to use other feedstock (pet coke, biomass) for co-gasification, the transformation behavior of Vanadium, Nickel and Phosphorus and their effect on slag viscosity is studied at different gasification conditions. (5) Partially reacted coke always exists in the slag, but the interaction between slag and coke is not clear. The wetting behavior and chemical reaction between slag and coke are characterized by thermo-optical methods, SEM and in-situ XRD. The effect of partially reacted coke on slag viscosity is evaluated. The above research will supply theoretical and practical results. Only the understanding and control of the slag viscosity allows for an efficient utilization of the feedstocks and supports the optimization and development towards efficient gasification processes. Beside the scientific objectives, the proposed joint research project is the base for the establishment of a long term cooperation between TUBAF and SKLCC. Researchers will be trained, the mobility of researchers between China and Germany will be stimulated and the scientific network will be enlarged.

• DFG Programme: Research Grants
• International Connection: China
• Partner Organisation: National Natural Science Foundation of China
• Co-Investigators: Professor Dr.-Ing. Bernd Meyer; Dr. Marcus Schreiner
• Cooperation Partner: Professor Dr. Jin Bai