Method for removing liquid from a slurry

Patent metadata

Field	Value
Publication number	US-10654235-B2
Application number	US-201314408068-A
Country	US
Kind code	B2
Filing date	Jun 11, 2013
Priority date	Jun 13, 2012
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

The method includes the following steps: (i) feeding a slurry into the inlet of a press; (ii) removing liquid from the slurry as the slurry advances through a deliquefying section of the press, thereby producing a pressate stream; (iii) forming a plug of material as the slurry is advanced through a plug formation section of the press; (iv) advancing the plug of material to a discharge section of the press; and (v) removing additional liquid from the plug of material by operating the press so that the pressure in the discharge section of the press is greater than the pressure of the pressate stream by at least 2 psi. There is also described a method for controlling discharge consistency from a press, without provision of discharge restrictors, by varying a pressure differential between a discharge section of the press and a pressate stream.

First claim

The invention claimed is:

1. A method of removing liquid from a slurry by a press having an inlet, a deliquefying section, a plug formation section, a discharge section, an outlet, and a restriction cone rigidly attached to a conveyance member that is mounted axially in the press for advancing material therethrough, the method comprising:
(i) pressurizing the slurry and feeding the pressurized slurry into the inlet of the press;
(ii) advancing the pressurized slurry through the deliquefying section of the press, thereby removing liquid from the slurry to produce a partially deliquefied slurry and a pressate stream of liquid pressed from the slurry;
(iii) advancing the partially deliquefied slurry to the plug formation section of the press using the conveyance member and compacting the partially deliquefied slurry into an annular space between the conveyance member and a surrounding shell to form an annular plug of material;
(iv) advancing the annular plug of material through the annular space, past the restriction cone, to the discharge section of the press;
(v) removing additional liquid from the annular plug of material by operating the press so that a pressure in the discharge section of the press is greater than a pressure of the pressate stream by at least 2 psi, thereby producing a plug of material having a reduced liquid content; and
(vi) removing the plug of material having the reduced liquid content, or segments thereof, through the outlet of the press.

2. The method according to claim 1 , wherein the pressate passes through an enclosed pressate chamber, and wherein the method comprises controlling a pressure in the pressate chamber independently of the pressure in the discharge section.

3. The method according to claim 2 , which comprises controlling the pressate chamber pressure by way of a valve.

4. The method according to claim 1 , which comprises controlling the pressure in the discharge section by adding a compressed gas.

5. The method according to claim 1 , which comprises controlling the pressure in the discharge section by adding steam.

6. The method according to claim 1 , wherein the press includes one or more baskets in the deliquefying section with openings and the method comprises allowing liquid to pass through the openings while retaining undissolved solids.

7. The method according to claim 6 , wherein the openings in the one or more baskets have a shape selected from the group consisting of round, slotted and hexagonal.

8. The method according to claim 1 , which comprises operating the press with the pressure in the discharge section section that is greater than the pressure of the pressate stream by at least 10 psi.

9. The method according to claim 1 , which comprises passing the annular plug of material through a throat section in the discharge section, the throat section being defined by the restriction cone mounted on the conveyance member.

10. The method according to claim 1 , wherein the conveyance member is a rotatable screw axially mounted within the press.

11. A method for controlling liquid removal from a slurry using a press having an inlet, a deliquefying section, a plug formation section, a discharge section, an outlet, and a restriction cone rigidly attached to a rotatable screw that is mounted axially therein, the method comprising the following steps:
(i) pressurizing the slurry and feeding the pressurized slurry into the inlet of the press;
(ii) advancing the pressurized slurry through the deliquefying section of the press, thereby removing liquid from the slurry and producing a pressate stream with liquid pressed from the slurry;
iii) advancing the partially deliquefied slurry to the plug formation section of the press using the rotatable screw and compacting the partially deliquefied slurry into an annular space disposed between the rotable screw and a surrounding shell to form an annular plug of material;
(iv) advancing the annular plug of material through the annular space, past the restriction cone, to the discharge section of the press;
(v) varying a pressure differential between the pressate stream and the discharge section of the press so as to achieve a given target consistency of a plug or segments thereof at the outlet of the press; and
(vi) removing a plug of material, or segments thereof, having the given target consistency through the outlet of the press.

12. The method according to claim 11 , wherein the target consistency of material discharged from the press is between 20 and 35 wt % undissolved solids.

13. The method according to claim 11 , which comprises pressurizing both the slurry fed to the inlet of the press and the discharge section of the press.

14. The method according to claim 11 , wherein the rotatable screw has an increasing cross-sectional area from the inlet of the press to the outlet of the press and wherein said cross-sectional area is measured perpendicular to the longitudinal axis of the press.

Assignees

• Voith Patent Gmbh
• Iogen Energy Corp

Inventors

• Miller William
• Richardson Trevor
• Rowland Stephen A

Classifications

• B30B9/18

  with means for adjusting the outlet for the solid · CPC title

• B30B9/12

  using pressing worms or screws co-operating with a permeable casing · CPC title

• B30B9/14

  operating with only one screw or worm · CPC title

• B30B9/125 Primary

  Control arrangements · CPC title

• B30B9/127

  Feed means · CPC title