68.PFBCプラントから回収した灰分のキャラクタリゼーションとそのセラミックフィルター上での堆積メカニズム(石炭利用における科学と工学の融合)

抄録

Ash recovered from ceramic filter of 71 MW PFBC (Pressurized Fluidized Bed Combustion) demonstration plant of EPDC in Wakamatsu, Kitakyushu was characterized by high-resolution SEM, EDX, and EPMA, in order to clarify the filter performances with or without cyclone bypass and chemical changes of calcite charged for defulfurization as well as fluidization. The ash recovered with bypass consisted of large and small grains. The large grains of alumina, gypsum and calcium carbonate often carried small grains on their surface. Such adhesion of small grains may prevent their plugging into the filter pores, reducing pressure drop accumulation and number of back-wash as experienced with cyclone bypass operation in comparison with full operation of cyclones. Calcium carbonate recovered from the filter showed very different morphology from that of calcite charged, which is calcined into lime to adsorb SO_2 forming gypsum. The formation of lime explains the high desulfurization degree in PFBC in spite of high CO_2 pressure at the boiler outlet.