Measurement of Residence Time Distributions of Coal Particles in a Pressurized Fluidized Bed Gasifier (PFBG) using Radio Tracer Technique

摘要

A pressurized fluidized bed gasifier (PFBG) system of an integrated coal gasification and combined cycle (ICGCC) plant is designed to behave as a well-mixed flow system for coal; and any deviation from the well-mixed flow condition will deteriorate the performance and efficiency of the gasification system. This paper describes a radiotracer investigation carried out to measure RTDs of coal particles in a pilot-scale PFBG with objectives to determine mean residence time (MRT) of coal/ash particles in the gasifier and estimate degree of mixing at different operating and process conditions. Lanthanum-140 labeled coal (100 gm) was used as a radiotracer. The tracer was instantaneously injected into the coal feed line and monitored at ash and gas outlets of the gasifier using collimated scintillation detectors. The measured RTD was used to determine mean residence time (MRT) of coal particles within the system and simulated using fractional tank-in-series model. The results of simulation indicated that the system behaved as a well-mixed system with undesired bypassing of a small fraction coal particle from the system. The results of the study were used to improve the design of the gasifier and optimize the system.