Abstract: The rotating electric machine includes: a rotor; and a stator, wherein the rotor includes: a rotor core having a magnet insertion hole group including a plurality of magnet insertion holes; and a permanent magnet group including a plurality of permanent magnets inserted in the plurality of magnet insertion holes of the magnet insertion hole group, respectively, wherein the plurality of magnet insertion holes are arranged side by side in a shape convex toward a center of the rotor from a radially-outer side surface of the rotor core, wherein the permanent magnet group forms one magnetic pole, wherein, in a part of the rotor core between the radially-outer side surface and the magnet insertion hole group, a magnetic slit is formed to extend in a shape convex toward the center of the rotor from the radially-outer side surface, and wherein the magnet insertion hole group includes three magnet insertion holes.

Abstract: A method of grinding cement clinkers and a cement clinker grinding apparatus having a vertical roller mill are provided. In the method, feed material is ground by a table and rollers. Next, substantially all the resultant ground material is taken out from an underside of the table and then converted to a separator for classifying the ground material by a bucket elevator. The resultant coarse powder provided by the separator is returned to a center of the table. In grinding, an pressing force of each of the rollers onto the table is selected so that a roller pressure per full sectional area of the roller ranges from 10 to 15 kg/cm2. Further, a circulation quantity of the coarse powder to be returned to the vertical roller mill is selected from 100 to 300% of the feed material charged into the center of the table. And the liquid of 0.

Abstract: The grinding efficiency can be improved by use of a vertical roller mill, while reducing the energy consumption and improving the product quality. The disclosed cement clinker grinding apparatus comprises a closed circuit for conveying the ground material from the vertical roller mill (21) to the external separator (28) by the bucket elevator (29), for classifying the conveyed material into coarse powder and fine powder, and further for returning the classified coarse powder into the vertical roller mill (21). That is, a part of the ground material conveyed by the bucket elevator (29) is divided by the distributing damper (32) and then directly returned to the vertical roller mill (21). Since the ground material are not conveyed by air flow conveyance (i.e., air sweep), it is possible to prevent an increase of power consumption of the suction fan (31).

Abstract: A fluidized-bed classifier has a vessel defining a space divided into an upper fluidized-bed chamber and a lower gas chamber by a perforated dispersion plate having the shape of a funnel. Rising currents of a gas, such as air, are blown through the dispersion plate into the upper fluidized-bed chamber to produce a fluidized bed of a particulate material over the dispersion plate. The lower gas chamber is divided into a first gas chamber and a second gas chamber by a partition plate. The gas is supplied into the first air chamber so that rising gas currents of a velocity necessary for fluidizing coarse particles contained in the particulate material fed into the vessel are blown from the first air chamber through the dispersion plate into the fluidized-bed chamber.