A grinding device, in particular a vertical mill for grinding a grinding material, the grinding device including at least two grinding elements that are movable relative to one another, wherein the two grinding elements together form at least one grinding portion in which the grinding material is grindable by the two grinding elements; and at least one contact pressure device including at least one hydraulic cylinder including a cylinder operating chamber and at least one gas spring including a spring operating chamber, wherein the cylinder operating chamber and the spring operating chamber are flow connected with one another, wherein a contact force is impartible upon at least one of the grinding elements by the at least one contact pressure device and the grinding elements are pressable onto one another by the contact force.

A system for servicing a pulverizer includes a pulverizer having a housing, a journal assembly pivotally connected to the housing, a grinding mechanism operatively connected to the journal assembly, and an opening within the housing adjacent to the journal assembly and providing an access point to an interior of the housing, and a hoist apparatus mounted to the housing. The hoist apparatus includes a frame assembly received about the opening in the housing, a sheave assembly including a plurality of sheaves supported by the frame assembly, a motor operatively connected to one of the plurality of sheaves, and a cable received by the sheave assembly. The motor is operable to at least one of retract the cable through the sheave assembly to rotate a component out of the pulverizer through the opening and controllably let out the cable to rotate the component into the pulverizer through the opening.

A vertical roller mill comprising a grinding table and a grinding roller having a rotational axis, each having a grinding surface and arranged to define a grinding zone between the grinding surfaces grinds particulate material. A feeder feeds the particulate material to the vertical roller mill, with the grinding roller is-arranged to roll around a grinding path on said grinding table. The feeder receives a supply of the particulate material and directs that material to flow to the grinding zone of the vertical roller mill. The feeder can constrain the flow of material to a defined cross-section by applying a momentum to and/or pushing, or to compact the flow of material prior to directing the material, or combinations thereof. In particular, the disclosure is applicable to grinding particulate materials like mining ores, industrial minerals and chemicals, sand, slag, ash, clay, pigments for coatings, pharmaceuticals and cement raw materials.

A system for servicing a pulverizer includes a pulverizer having a housing, a journal assembly pivotally connected to the housing, a grinding mechanism operatively connected to the journal assembly, and an opening within the housing adjacent to the journal assembly and providing an access point to an interior of the housing, and a hoist apparatus mounted to the housing. The hoist apparatus includes a frame assembly received about the opening in the housing, a sheave assembly including a plurality of sheaves supported by the frame assembly, a motor operatively connected to one of the plurality of sheaves, and a cable received by the sheave assembly. The motor is operable to at least one of retract the cable through the sheave assembly to rotate a component out of the pulverizer through the opening and controllably let out the cable to rotate the component into the pulverizer through the opening.

In a method and a corresponding device for controlling a rotational speed of a drive driving a shaft, the rotational speed is controlled by a control device which is supplied with a control deviation calculated based on a desired value and an actual value for the rotational speed. The actual value for the rotational speed of the shaft is measured on the shaft with a first sensor and at least one additional sensor and the actual value is calculated from a weighted average of the individual measured values for the rotational speed obtained from the first and the at least one additional sensor.

In grinding of a raw material by a vertical roller mill, highly-efficient grinding is performed irrespective of the type of the raw material, and the life of the mill roller is extended. In order to achieve these, in a grinding roller used in a vertical roller mill, an outer circumferential surface of the roller as a grinding surface is divided into a main grinding surface that mainly performs pulverizing and a grinding surface other than the main grinding surface. The main grinding surface is made smooth, and the grinding surface other than the main grinding surface is a raw material transfer surface in which slit grooves inclined at 90 degrees or an angle exceeding 45 degrees relative to a roller circumferential direction or screw grooves inclined at 45 degrees or smaller relative to the roller circumferential direction are formed.

The present invention improves the even distribution of a powder to a pulverized coal pipe. A rotary classifier including: a rotary shaft rotatably supported around a rotational axis extending in a vertical direction; a frame body supported by the rotary shaft and including an opening on the outer periphery of the frame body; a plurality of powder outlets provided along the rotation direction and opening on the upper section of the frame body; a plurality of blades extending in the vertical direction at the opening on the outer periphery of the frame body and provided along the rotation direction; and an annular member that serves as a constricting section provided so as to narrow the interval from the blades to the rotary shaft.

A turret includes a generally frusto-conical shaped body and a plurality of static vanes arranged interior to the body and extending inwardly from an interior sidewall of the body. The vanes are configured to guide a swirling flow of solid particles as they enter the body, and to divide the swirling flow into a plurality of controlled flows that are communicated to a plurality of coal outlet pipes.

A turret includes a generally frusto-conical shaped body and a plurality of static straightening vanes arranged interior to the body, the vanes dividing the body into a plurality of substantially equal sections. The vanes are configured to straighten a swirling flow of solid particles as they enter the body, and to divide the swirling flow into a plurality of straightened flows that are communicated to a plurality of coal outlet pipes.

Provided is a vertical roller mill equipped with a rotary classifier for causing a plurality of classification blades provided above a rotary table and positioned around an axis to rotate about the axis, wherein: of a solid fuel pulverized by a roller, the rotary classifier guides solid fuel fine powder from an outer-circumferential-side space to an inner-circumferential-side space surrounded by the plurality of classification blades, and suppresses, by collision with the plurality of classification blades, an intrusion of solid fuel coarse powder into the inner-circumferential-side space; and each of the plurality of classification blades is shaped in a manner such that there is no interference between a scattering direction in which the coarse powder that collided with the classification blades scatters and an intake direction in which the fine powder is guided to the inner-circumferential-side space, and the scattering direction is oriented upward relative to a horizontal direction.