Experimental And Numerical Study On Two-stage Dry Feed Entrained Flow Gasiifcation

As one of the key technologies in the Clean Coal field, coal gasification is the basis fordeveloping Integrated Gasification Combined Cycle (IGCC), coal-based chemicalengineering and clean energy systems. Entrained flow gasification, which represents thedevelopment direction of large-scale gasification technologies, has many advantages such ashigh carbon conversion rate and cold gas efficiency, good coal adaptability, and intensivemixing of gas and solids at high temperatures and pressures. At present, the two-stage dryfeed entrained flow gasification technology, as one of the typical representatives of entrainedflow gasification technologies, has been successfully applied to an IGCC system and acoal-based chemical project. Based on Huaneng Tianjin IGCC Demonstration Power Plant,an experimental and numerical study on the two-stage dry feed gasifier was conducted in thispaper.The gasification test on a commercial scale two-stage dry feed gasifier was performed for thefirst time. The gasification performance and operation characteristics of the gasifier wereobtained, and the effect of key operation parameters on the gasification process was alsoinvestigated. The long-term continuous operations demonstrated that the scale-up design ofthe gasifier was reliable. According to the experimental results, the carbon conversion ratewas above98.5%, and the effective gas content was up to86.42%. Moreover, the cold gasefficiency reached83.6%, and the specific consumption of oxygen and coal (dry ash freebasis) was321.0Nm3/1000Nm3and486.7kg/1000Nm3, respectively. These dataindicated that the performance of the gasifier was slightly better than that of similar units,while has higher cold gas efficiency and carbon conversion rate.According to the test data and the gasifier operation characteristics, a3-D numerical modelfor the first-stage combustor of the gasifier was established by using FLUENT. Moreover,the computational grid, boundary conditions, and the solution method and strategy for themodel were determined. By solving the model, the calculated temperature and compositionof the outlet gas were obtained, and the flow field and gas composition distribution werepredicted. The results agreed well with the test data, indicating the numerical model wasreasonable. It was also found that the gasification reactions were fast and reachedequilibrium, and both the operation temperature in the gasifier and the water-gas shift reaction played important roles in the gasification process.The study in this paper lays a foundation for improving the two-stage dry feed gasificationprocess further, optimizing the gasifier structure, and promoting the gasification technology.Consequently, the study has significance in both theoretical research and engineeringapplications.