Method and apparatus for explosively defibrating cellulosic fiber

• US 4,163,687 A
• Filed: 04/24/1978
• Issued: 08/07/1979
• Est. Priority Date: 04/27/1977
• Status: Expired due to Term

• Current Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Original Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Inventors: Mamers, Heikki, Rowney, John E.
• Primary Examiner(s): Fisher, Richard V.
• Assistant Examiner(s): Alvo, Steve
• Application Number:
  US05/899,148
• Time in Patent Office: 470 Days
• Field of Search: 162/21, 162/52, 162/246, 162/247, 162/22, 239/590.5, 138/42, 241/5, 241/1, 426/621, 426/625
• US Class Current: 162/21
• CPC Class Codes: D21B 1/36 Explosive disintegration by sudden pressure reduction
• CPC Class Codes: D21C 7/08 Discharge devices

Abstract

A uniquely designed nozzle is described for assisting the liberation of fibres from cellulosic material during an explosive defibration process. The nozzle is constructed with a plurality of internal bars so as to provide a tortuous path to the material passing therethrough from a region of high pressure to a region of low pressure.

Claims

1. In a process for explosively defibrating cellulosic fibre from plant material wherein the plant material is subjected to a high pressure environment followed by rapid transfer to a lower pressure environment, the improvement comprising passing the material from the high to the low pressure environment by way of a discharge nozzle across which a plurality of bars spanning diametrically across the nozzle having rounded leading edges facing in the direction of flow are arranged in such a manner as to cause the plant material passing therethrough to be folded over, successive bars thereby subjecting the folded plant material to shear and tensile forces generated by the concomitant passage of highly turbulent fluids causing the material to be successively pulled apart into individual fibres and fibre bundles wherein said bars are disposed at varying angles relative to each other along the longitudinal axis of the nozzle and the minimum number of bars and their arrangement in the nozzle is such that when the nozzle is viewed in the direction of passage of the plant material no clear passage exists in the nozzle through which a fragment of the plant material may traverse without being folded over a bar.

2. A discharge nozzle having a passageway through which cellulosic material may be explosively defibrated from a high pressure pulping digester to a lower pressure reservoir, said nozzle having a plurality of bars spanning diametrically across the nozzle having rounded leading edges facing the direction of flow extending across said passageway at varying locations along the longitudinal axis thereof so as to provide a series of the bars which are arranged so that any passing plant material is successively folded over the bars and pulled apart into individual fibres and small fibre bundles wherein the angles at which the axis of the bars are set relative to each other are randomized and the minimum number of bars and their arrangement in said passageway is such that when the passageway is viewed in the direction of passage of the plant material no clear passage exists in the passageway through which a fragment of the plant material may traverse without being folded over bar.

3. A discharge nozzle as set forth in claim 2, wherein the cross section of each bar is circular.

4. A discharge nozzle as set forth in claim 3, wherein each bar has a diameter greater than 2 mm and no more than 13 mm.

5. A discharge nozzle as claimed in any one of claims 2, 3 or 4 wherein when the cellulosic material has an average length "x," the spacing between the successive bars is at least x/2.