Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B9/00—Presses specially adapted for particular purposes
  • B30B9/02—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material
  • B30B9/20—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using rotary pressing members, other than worms or screws, e.g. rollers, rings, discs
  • B30B9/207—Roller-and-ring presses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B9/00—Presses specially adapted for particular purposes
  • B30B9/02—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material
  • B30B9/20—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using rotary pressing members, other than worms or screws, e.g. rollers, rings, discs

Definitions

• the present invention relates to a method for removing liquid from bark, for example in order to increase the dry solids content of wet bark or other bark generated in wood debarking, and a drum-type press.
• a drum-type press mainly comprises a rotary external screen drum and a press roll mounted rotatably in the interior thereof. Further the press has e.g. a frame/support structures supported by which the screen drum rotates, a drive mechanism or drive mechanisms and feed devices for introducing the material to be pressed into the press.
• the material from which the liquid is required to be removed is fed into the screen drum, wherein it is passed into a throat formed by the screen drum and the press roll and is pressed between the screen drum and the press roll, whereby liquid is removed from the material.
• the dewatered material is discharged from the press after the pressing, e.g. by means of a screw type conveyor or by plowing.
• Drum-type presses are used in various object of application, among other in the chemical pulping or saw industry for dewatering bark.
• the purpose of pressing bark is to improve the heat value of the bark or to facilitate further drying for some other process by removing as much water from the bark as possible.
• the aim in bark pressing is the highest possible dry-solids content value.
• the bark generated in wood debarking is used almost solely as fuel and every additional percentage unit in the dry-solids content means, even at a medium-size power plant, savings amounting to hundreds of thousands of euros at an annual level compared to producing the amount of energy corresponding to increase in the dry-solids content by means of some other fuel, for example.
• the significance of the final dry-solids content of pressed material also increases.
• a novel solution has been developed for removing liquid from a material.
• the purpose of the invention is to provide a drum-type press that is remarkably more productive than before and to provide the most wide and versatile solution possible for solving the problems present in the prior art solutions.
• a drum-type press has inside its screen drum two press rolls, which together with the screen drum form a first and a second pressing stage.
• the pressing is performed in two stages so that the first pressing stage is carried out between the screen drum and the first press roll and the next stage between the screen drum and the second press roll.
• an even solid material mat is formed from the bark being pressed, which material mat is transferred on the inner surface of the screen drum as such to the second pressing stage.
• the second pressing stage can utilize ready-formed material mat, from where a portion of the liquid has been removed.
• a ready-formed material mat at a higher dry solids content resists a higher pressing pressure.
• a ready-formed material mat acts as a filtering mat, which decreases the passing of solid matter into the exiting liquid.
• a ready-formed bark mat decreases material packing into the dewatering holes.
• the screen press includes flanges that rotate along with it.
• the flanges are arranged substantially at the ends of the screen drum and they extend in the radial direction of the screen drum at least towards the interior.
• the press rolls can rotate between the flanges and a suitably small gap remains between the flanges and the press rolls.
• the height of the flanges is arranged such that the pressing takes place outside the inner circumference of these flanges, whereby material being pressed cannot pass in the axial direction out of the screen drum end and no separate end plates are needed for preventing the exit.
• the press additionally has guide plates, which are used to guide the bark being pressed between the screen drum flanges. The guide plates extend between the screen drum flanges, overlapping with them in the radial direction of the screen drum.
• liquid is also removed from the press rolls, in addition to the screen drum.
• the pressing is intensified, since liquid is removed in the thickness direction of the material bed in both directions.
• Liquid is removed, in addition to the screen drum, from all press rolls, whereby the pressing result is further improved.
• the press rolls, from which liquid is removed are at their ends provided with openings, through which the liquid is led from the interior of the press roll to the outside of it.
• a nip refers to a zone between the screen drum and the press roll, wherein the radial distance between their casings is the smallest.
• the nip can be controlled, if desired, by adjusting the pressing force. If, for instance, the thickness of the nip decreases, the pressing force can be decreased for increasing the thickness of the nip.
• the press rolls are provided with a sensor system measuring the position and force. By means of the sensor system, data is obtained from each pressing stage, such as e.g. the thickness and pressing force of the nip. The obtained data is utilized in controlling the pressing stage in question and the subsequent pressing stage.
• Fig. 1 illustrates a drum press roll according to a preferred embodiment of the invention seen from the direction of the end
• Fig. 2 illustrates a detail of a solution according to a preferred embodiment of the invention seen from the lateral direction of the press.
• Fig. 1 illustrates, according to a preferred embodiment of the invention, a drum- type press 10, which comprises a feed screw 1 1 , substantially a horizontal screen drum 20, flanges 40 at the ends of the screen drum, substantially a substantially horizontal first press roll 30, substantially a horizontal second press roll 31 , members 38 for leading the once-pressed bark to a subsequent pressing stage, and devices 12 for discharging the pressed bark from the press.
• the bark being pressed is fed into press 10 with suitable members, such as the feed screw 1 1 shown in the figure.
• the flanges 40 are arranged substantially at the ends of the screen drum 20, extending radially at least towards the interior, and press rolls 30 and 31 are arranged on the inside of these.
• the pressing stage occurs within the area between the flanges 40 of the screen drum 20.
• the first press roll 30 and screen drum 20 comprise the first nip between them, and the second press roll 31 and screen drum 20 comprise the second nip.
• the screen drum 20 and first press roll 30 are positioned so that the bark being pressed is guided by gravity into the space between screen drum 20 and first press roll 30 before the first nip, where the bark is pressed in the first pressing stage.
• the axles of screen drum 20 and press rolls 30 and 31 are substantially horizontal.
• Press rolls 30 and 31 are positioned so that the liquid being removed from the material can be led by gravity out of the press, without allowing the removed liquid to flow back into the already pressed material or unpressed material. Consequently, no separate vacuum source is needed to discharge from the press the liquid removed from the bark.
• both press rolls 30 and 31 are positioned so that both nips, the first and the second, are positioned underneath the rotating shaft of the screen drum 20.
• press rolls 30 and 31 are positioned inside the screen drum 20 so that the press roll rotating shafts are on both sides of the vertical axis of the screen drum as seen from the end of the screen drum 20.
• the press rolls are positioned so that the first nip is lower than the second nip.
• the material mat pressed once in the first pressing stage is led along the inner surface of the screen drum 20 to the next pressing stage in the zone between the screen drum 20 and press roll 31 .
• the members 38 can be used to lead the material mat, as shown in the figure.
• the drum-type press 10 comprises guide plates 45, which are used to lead the bark being pressed between the screen drum 20 flanges 40.
• the guide plates 45 extend between the screen drum 20 flanges 40, overlapping with them in the axial direction of the screen drum.
• Fig. 2 shows a detail of the screen drum 20 and press rolls 30, 31 , according to the invention. The figure shows how a pressing space 4, where the material is pressed, is defined against the screen drum 20, the press rolls 30, 31 and the flanges 40 of the screen drum, and the pressing of the material takes place in this space and material being pressed cannot pass in the axial direction out of the end of the screen drum 20.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)
• Sampling And Sample Adjustment (AREA)

Applications Claiming Priority (6)

Publications (1)

Family

ID=55971025

Family Applications (1)

Country Status (2)

Cited By (3)

Citations (3)

• 2016
  • 2016-04-14 WO PCT/FI2016/050247 patent/WO2016170227A1/en active Application Filing
  • 2016-04-22 UY UY0001036645A patent/UY36645A/es not_active Application Discontinuation

Patent Citations (3)

Also Published As

Similar Documents

Legal Events