What are the main factors affecting the desulfurization efficiency in the circulating fluidized bed boiler?

　　(1) The distribution of limestone in the furnace.

　　(2) Limestone reaction activity.

　　(3) The combustion temperature in the furnace.

　　(4) The residence time of limestone in the furnace.

　　(5) Limestone particle size.

　　(6) Volatile content of fuel.

　　(7) Calcium-sulfur molar ratio.