Oy Tampella Ab

Mo Och Domsjo Aktiebolag

Pekka O Haikkala

Raimo Pessa

Juhani Ahonen

Jonas A Lindahl

Matti I Aario

Eero Hanhilahti

Toivo Lajunen

Frame construction for a pressure grinding machine of press type, which frame construction comprises a gastight, pressure-proof grinding chamber, bearing housings for a grinder member revolving in the grinding chamber, as well as at least one press chamber for the pulpwood and a press device limiting the press chamber on one side. The frame construction consists of two separate parts, namely a pressure frame, which constitutes the said grinding chamber and press chamber and which substantially receives the pressure forces resulting from the positive pressure prevailing in the grinding chamber, and a power frame, which connects the press device and the bearing housings of the grindstone to each other and which substantially receives the tensile and circumferential forces resulting from the grinding and from the pressing of the wood against the grindstone.

Frame construction for a pressure grinding machine of press type

A method for feeding a wood batch into a pressure grinder, according to which method the wood batch is first fed into a pressurizable feeding device (9) and thereafter from the feeding device into a continuously pressurized grinding chamber (5) to make contact with a grinding means (3) rotating in the grinding chamber. The wood batch is fed from the feeding device into the grinding chamber essentially in a horizontal plane in the direction of the axis (4) of rotation of the grinding means for maintaining proper order of the wood batch during the feeding operation. In a feeding device for carrying out the method the feeding device (9) is positioned on the side of the grinding chamber (5) so that the bottom (10a) of the feeding pocket (10) formed by the feeding device is essentially in level with the bottom (5a) of the grinding chamber. The feeding device is provided with a pushing means (17) displaceable in the feeding pocket towards the grinding chamber in parallel with the level of the bottom.

Method of and a feeding device for feeding a wood batch into a pressure

Apparatus for continuously processing wood comprises a pressurized grinding chamber, a grinding stone which is mounted for rotation in the grinding chamber, a device for feeding wood into the grinding chamber to form a primary groundwood stock therein, and a device for discharging the primary groundwood stock from the chamber without allowing gas to escape from the chamber to atmosphere. The feeding device comprises a stationary feeding chamber provided with shutters for sequentially pressure-tightly closing the feeding chamber from the atmosphere and from the grinding chamber respectively, thereby to prevent escape of gas from the grinding chamber through the feeding device. The discharging device comprises a stick crusher for crushing sticks present in the primary groundwood stock thereby to produce a secondary groundwood stock and an outlet for continuously discharging the secondary groundwood stock while preserving a hydraulic seal of groundwood stock thereby to prevent escape of gas from the grinding chamber through the discharging device.

Apparatus for continuously grinding wood under pressure and continuously

Apparatus for continuously processing wood comprises a pressurized grinding chamber, a grinding stone which is mounted for rotation in the grinding chamber, a device for feeding wood into the grinding chamber to form a primary groundwood stock therein, and a device for discharging the primary groundwood stock from the chamber without allowing gas to escape from the chamber to atmosphere. The discharging device comprises a stick crusher for crushing sticks present in the primary groundwood stock thereby to produce a secondary groundwood stock and an outlet for continuously discharging the secondary groundwood stock while preserving a hydraulic seal of groundwood stock thereby to maintain the groundwood stock in the apparatus under superatmospheric pressure.

A sealing arrangement for a shutter for a feeding chamber of a continuously operating pressure grinder. The feeding chamber is provided with an inlet opening for feeding wood batches at atmospheric pressure into said feeding chamber and with an outlet opening for feeding said wood batches into the grinding chamber at overpressure. Each opening of said feeding chamber is provided with a shutter movable between an opened position and a closed position for preventing of escape of said overpressure through said feeding chamber. The feeding chamber is provided with a fixed guide supporting the shutter during its movement between opened and closed positions. Said guide comprises two parallel support surfaces between which the shutter is slidably mounted. The distance between said support surfaces is greater than the thickness of the shutter adjacent said support surfaces so that the shutter is displaceable towards and away from said support surfaces in a direction perpendicular to said support surfaces. A sealing element is provided in one of said support surfaces in such a way that, when the shutter is displaced away from said one support surface towards the other support surface, the shutter is released from contact with said sealing element. In this way the shutter is due to the pressure difference between opposite sides of the shutter pressed against said one support surface and against said sealing element but is released from contact with said support surface and said sealing element when the pressures are equilized on opposite sides of the shutter and can be moved to open and closed positions without said contact.

Sealing arrangement for a shutter of a pressure grinder

A method of grinding wood under pressurized conditions in a grinder according to which wood is fed in batches into a pressurized gas-filled grinding chamber provided with a rotary grinding means. The wood batches are fed through a feeding chamber provided with means for sequentially opening and pressure-tightly closing said feeding chamber from two sides in and respectively out of communication with the atmosphere and said grinding chamber respectively. The groundwood stock is discharged from the grinding chamber through a pressure lock formed by the groundwood stock. In this way feeding of the wood batches into the grinding chamber and the discharging of the groundwood stock out from said grinding chamber are carried out as sluicing steps, whereby a continuous pressure can be maintained in the grinding chamber in spite of feeding of new wood batches and discharging of groundwood stock.

Method of and a grinder for grinding wood under pressure

A method of discharging groundwood stock when grinding wood under pressurized conditions in a grinding chamber, according to which the groundwood is suspended into stock and collected in a tank provided with an outflow for groundwood stock to atmospheric pressure. The surface of the stock in said tank is maintained at such a level above said outflow, that the stock in said tank forms a pressure lock in the communication between the grinding chamber and said outflow. In this way the discharging of the groundwood stock out from said grinding chamber is carried out as a sluicing step, whereby a continuous pressure can be maintained in the grinding chamber in spite of discharging of groundwood stock.

Method of and a grinder for discharging groundwood stock when grinding

A process is provided for preparing groundwood pulp from debarked pulpwood logs which comprises grinding the logs under a superatmospheric pressure of a gas selected from the group consisting of steam, air and steam and air, while continuously supplying thereto process white water and water separated in thickening groundwood pulp suspension at a temperature within the range from about 75.degree. to about 100.degree. C., and forming a pulp suspension in the resulting aqueous liquor; centrifugally separating steam from the pulp suspension, and using the separated steam to heat the water supplied to the grinding; thickening the pulp suspension to a pulp concentration within the range from about 5 to about 40%, and supplying water separated therefrom to the grinding; diluting the thickened pulp, and screening the diluted pulp suspension; after thickening the screened rejects suspension to a pulp concentration of at least 10% and defibrating the screened rejects suspension in a refiner, recycling the defibrated screened rejects to the from-steam-separated pulp suspension; and mixing the thickened and refined rejects suspension, having a pulp concentration of at least 8%, with the pulp suspension, thereby increasing the pulp concentration of the from-steam-separated pulp suspension, and thus facilitating its thickening.

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Tampere, Finland

Pekka O Haikkala