Effect of Coal Blending on Gasification Performance and Agglomeration

Abstract

To localize coal utilization, a local Hongshagang bituminous coal (Hc) with low ash fusion temperatures (AFTs) was blended with the Guanghui bituminous coal (Gc). Prior to its application in an industrial fluidized bed gasifier, a series of verification tests were performed in this study for feasibility analysis. The AFTs and CO2 gasification reactivity of blended coal decrease with the increases in the additive amount of Hc. Therefore, the additive amount of Hc was determined to be 10–30% for further bubbling fluidized bed (BFB) gasification. During BFB gasification experiments, the addition of Hc lowered the gasification performance; furthermore, agglomeration and slagging occurred. The deposited slags were examined via SEM, XRF, and XRD to determine the formation mechanism. Specifically, the flux effect of Fe and Na in Hc ash promoted the slagging. The local oxidizing atmosphere in the bottom of the reactor affected the mineral transformation in slags. It changed the contents of crystal phases and led to solidification of liquid phase by comparing XRD results and Factsage calculations. At last, the formation process of slag was described based on the aforementioned experimental phenomena.

Effects of ash compositions in Zhundong coal on its ash fusion behavior and crystal phase transformation

“…As a consequence, the ash fusion features a complicated process. Many scholars researched the impacts of ash composition on AFTs through blending combustion or adding additives into coal or ash, but it is hard to analyze the influence mechanism of each composition in detail 22–25 . Hence, some researchers replaced the coal ash with synthetic ash via various analytic reagents, which was beneficial for the specific analysis of each composition influence and the reaction between these compositions 26 .…”