The contents of the following Japanese and International patent applications are incorporated herein by reference:

Appln. No. 2018-022907 filed in JP on Feb. 13, 2018,

Appln. No. 2019-007353 filed in JP on Jan. 18, 2019, and

Appln. No. PCT/JP2019/005126 filed in WO on Feb. 13, 2019.

TECHNICAL FIELD

The present invention relates to a dry grinding machine.

BACKGROUND ART

A dry grinding machine is known that manufactures dry powder from a material to be processed containing moisture, as shown in Patent Document 1, for example

CITATION LIST

Patent Literature

[PTL 1] Japanese Patent Application Publication No. 2013-174405

GENERAL DISCLOSURE

In the dry grinding machine described above, the rotating shaft supporting the blade holds the blade on one side, and therefore the axial length is limited, and it is difficult to improve the processing capability by enlarging the volume of the grinding chamber. One aspect of the present invention may be the dry grinding machine described below. The dry grinding machine may include a rotating shaft. The dry grinding machine may include a first blade that is rotationally driven by the rotating shaft. The dry grinding machine may include a grinding chamber that houses the first blade. The dry grinding machine may include a feed-in section that feeds material to be processed, which is transported by hot air, into the grinding chamber from a direction intersecting the rotating shaft. The dry grinding machine may include a discharging section that is arranged on a side of the first blade opposite the feed-in section, in an axial direction of the rotating shaft, and discharges from the grinding chamber, along with the hot air, the material to be processed that has been fed in from the feed-in section and then ground by the first blade while being dried by the hot air. The grinding chamber may have a rotating body shape centered on the rotating shaft. The grinding chamber may have a portion where an inner diameter becomes larger closer to the discharging section in the axial direction, at least on the discharging section side of the first blade.

A position of the rotating shaft relative the grinding chamber is fixed in the axial direction, at both ends of the grinding chamber. The grinding chamber may include a portion where an inner diameter is constant, in the axial direction, at each end in the axial direction. The dry grinding machine may further include a second blade arranged on a side of the feed-in section opposite the first blade, in the axial direction. A space between the second blade and the grinding chamber may be sealed by high-pressure air whose pressure is higher than atmospheric pressure. A ratio of surface area of one side of a blade to a cross section of the grinding chamber including the second blade may be greater for the second blade than for the other blade. The dry grinding machine may further include a blowing section that is arranged on a side of the feed-in section opposite the first blade, in the axial direction, and blows hot air into the grinding chamber. The blowing section may blow the hot air along a line tangent to the grinding chamber in a cross section orthogonal to the rotating shaft of the grinding chamber. The dry grinding machine may further include a third blade arranged between the feed-in section and the blowing section, in the axial direction. The third blade may be arranged downstream from the feed-in section in a direction of gravity. The dry grinding machine may further include a second blade arranged on a side of the blowing section opposite the third blade, in the axial direction. A space between the second blade and the grinding chamber may be sealed by high-pressure air whose pressure is higher than atmospheric pressure. A ratio of surface area of one side of a blade to a cross section of the grinding chamber including the second blade may be greater for the second blade than for other blades. The dry grinding machine may further include a fourth blade arranged between the first blade and the discharging section, in the axial direction. The material to be processed may be a food product. The material to be processed may be any one of biomass fuel and a hydrous solid fuel including lignite.

The summary clause does not necessarily describe all necessary features of the embodiments of the present invention. The present invention may also be a sub-combination of the features described above.

