Abstract: Abstract: Shaanxi Yanchang Petroleum Yulin Kaiyue Coal Chemical Co., Ltd. Coal slurry preparation system of the three rod mills have been in a fully open state, no standby machine, when the rod mill failure shutdown, the subsequent gasification and synthesis must reduce the load, thus affecting the output of methanol.In order to reduce costs and increase efficiency and expand production capacity, Yulin Kaiyue decided to adopt the three-generation discontinuous gradation CWS preparation technology developed by the General Institute of Coal Science and Technology to transform the original pulping system.Standby a coarse powder production line, when a rod mill maintenance or failure to start, in order to fundamentally solve the bar mill unprepared machine caused by the production load fluctuation problem.The complete set of technology of discontinuous gradation of high concentration pulping organically combines selective grinding machine and fine grinding machine, which greatly improves the comprehensive grinding efficiency, and the coal slurry concentration can be increased by more than 4 percentage points.