Screening methods and apparatus

Abstract

An apparatus ( 25 ) for use in screening a liquid and solids mixture feed ( 2 ) comprises a conduit ( 18 ), including a screening portion ( 22 ) that is formed and arranged to divide a liquid and solids mixture feed flowing through the conduit. The feed ( 2 ) is divided into a first, cleaned stream (C 1 ) comprising liquid and solid particles of below a selected size limit, and a second, concentrated, stream ( 24 ) comprising liquid, and particles above the selected size limit. The apparatus ( 25 ) may be a stand alone module, part of a system with other solids and liquids separating equipment or an integral part of a solids and liquid separator such as a shale shaker. Methods of using the apparatus ( 25 ) are also described.

1 . An apparatus for use in screening a liquid and solids mixture feed, the apparatus comprising:
 a conduit, including a screening portion and formed and arranged to divide a liquid and solids mixture feed flowing through the conduit into a first, cleaned stream comprising liquid and solid particles of below a selected size limit, and a second, concentrated, stream comprising liquid, and particles above the selected size limit.   
     
     
         2 . An apparatus according to  claim 1  wherein at least the screening portion of the conduit is subject to vibration provided by vibration means. 
     
     
         3 . An apparatus according to  claim 2  wherein at least the screening portion of the conduit is:
 mounted on resilient mountings; or 
 is located in a basket mounted on resilient mountings; and 
 the screening portion of the conduit or the basket containing it is subject to vibration by the vibration means. 
 
     
     
         4 . An apparatus according to  claim 1  wherein the conduit is a pipe or channel having a screen mesh or other filter material that replaces part of its wall. 
     
     
         5 . An apparatus according to  claim 1  wherein the conduit incorporates a secondary, internal conduit, for example a pipe, that has a portion of wall replaced by a screen mesh or other screen or filter material. 
     
     
         6 . An apparatus according to  claim 1  wherein the conduit comprises at least two screens, provided in one or more screening portions of the conduit, wherein the at least two screens are formed and arranged to operate in a series fashion whereby the first, cleaned stream is passed successively through both screens. 
     
     
         7 . An apparatus according to  claim 1  wherein the conduit is formed and arranged so that the screening of the feed effected by the screening portion of the conduit is carried out in an upwardly flowing direction through the screening portion. 
     
     
         8 . An apparatus according to  claim 1  wherein the conduit is formed and arranged so that the screening of the feed effected by the screening portion of the conduit is carried out in a downwardly or a horizontally flowing direction through the screen. 
     
     
         9 . An apparatus according to  claim 1  formed and arranged so that the screening is carried out at a slight positive pressure provided by one or more of the following:
 an inlet for the conduit is at a height greater than the height of the screening portion of the conduit; 
 an outlet for the conduit, in the form of a weir or an orifice, is at a greater height than the screening portion of the conduit; 
 a pump supplies the liquid and solids mixture feed to the conduit; and 
 an outlet orifice from the screening portion of the conduit is restricted with respect to the size of the inlet flow. 
 
     
     
         10 . An apparatus according to  claim 9  wherein at least one of:
 inlet height; 
 outlet height; 
 pumping rate; and 
 outlet orifice size; 
 is manually or automatically variable to adjust the flow rate and the pressure applied for screening. 
 
     
     
         11 . An apparatus according to  claim 9  wherein the screening portion of conduit has a portion of screen mesh or other filter material on an upwards facing portion of wall and the feed is supplied at a slight positive pressure so as to effect upwards filtration through the screen mesh. 
     
     
         12 . An apparatus according to  claim 9  wherein the screening portion of conduit has a portion of screen mesh or other filter material on a vertical or downwards facing portion of wall and the feed is supplied at a slight positive pressure so as to effect horizontal or downwards filtration through the screen mesh. 
     
     
         13 . An apparatus according to  claim 8  wherein the conduit:
 a) is mounted in a vibrating basket or is itself mounted on resilient members and is directly vibrated; 
 b) has a downwards directed, for example vertical, inlet end followed by a generally horizontally disposed screening portion that has a screen mesh replacing a portion of conduit wall; and 
 c) the conduit continues by having an upwardly directed, for example vertical, outlet end at a lower height than the inlet end. 
 
     
     
         14 . An apparatus according to  claim 1  further comprising a scalping screen, formed and arranged to remove large particles from the liquid and solids mixture feed before it flows through the conduit. 
     
     
         15 . An apparatus according to  claim 14  wherein the scalping is subject to vibration by vibration means. 
     
     
         16 . A method of screening a liquid and solids mixture feed, the method comprising:
 providing a conduit, including a screening portion and formed and arranged to divide the feed flowing through the conduit into a first, cleaned stream comprising liquid and solid particles, of below a selected size, and a second, concentrated, stream comprising liquid and particles above the selected size; and   passing a liquid and solids mixture feed through the conduit.   
     
     
         17 . A method according to  claim 14  wherein the method further comprises:
 directing the second stream to an apparatus for further processing. 
 
     
     
         18 . The method according to  claim 17  wherein the second stream is processed by a method comprising passing the second stream through at least one of a vibratory screening machine, a centrifuge and a hydrocyclone. 
     
     
         19 . A method according to  claim 16  wherein the method further comprises:
 processing a liquid and solids mixture feed through at least one of: a scalping screen, a vibratory screening machine, a centrifuge and a hydrocyclone: 
 before passing a resulting liquid and solids mixture feed through the conduit. 
 
     
     
         20 . (canceled) 
     
     
         21 . A method according to  claim 17  wherein the at least one apparatus employed to process the second stream is a shale shaker. 
     
     
         22 . A system for screening a liquid and solids mixture feed, the system comprising:
 an apparatus including a conduit, the conduit including a screening portion formed and arranged to divide a liquid and solids mixture feed flowing through the conduit into a first, cleaned stream comprising liquid and solid particles of below a selected size limit, and a second, concentrated, stream comprising liquid, and particles above the selected size limit; and   screening or liquid and solids separating apparatus for processing the second stream.   
     
     
         23 . A system according to  claim 22  wherein the apparatus including a conduit is as wherein at least the screening portion of the conduit is subject to vibration provided by vibration means. 
     
     
         24 . A system according to  claim 22  wherein the screening apparatus for processing the second stream is selected from the group consisting of hydrocyclones, centrifuges, decanting centrifuges, vibratory screening machines such as shale shakers, and combinations thereof. 
     
     
         25 . A vibratory screening machine for separating solids from liquid, in a liquid and solids mixture feed, the machine including as an integral part:
 an apparatus comprising:   a conduit, including a screening portion and formed and arranged to divide a liquid and solids mixture feed flowing through the conduit into a first, cleaned stream comprising liquid and solid particles of below a selected size limit, and a second, concentrated, stream comprising liquid, and particles above the selected size limit.   
     
     
         26 . A vibratory screening machine according to  claim 25  wherein the apparatus is mounted in the vibrating basket of a shale shaker. 
     
     
         27 . A vibratory screening machine according to  claim 26  formed and arranged so that the second concentrated stream comprising liquid and particles above the selected size limit is fed to one or more screens of the shale shaker for further processing. 
     
     
         28 . A vibratory screening machine according to  claim 26  formed and arranged so that the liquid and solids mixture feed is processed through at least one scalping screen of the shale shaker, before being fed to the apparatus comprising: the conduit. 
     
     
         29 . A vibratory screening machine according to  claim 26  further comprising a switchable flow distributor formed and arranged to:
 receive the second concentrated stream from the apparatus comprising the conduit; and 
 to divide said second concentrated stream to feed, in parallel, a stack of at least two vibrating screens in the basket; or 
 to feed said second concentrated stream successively through a stack of at least two vibrating screens in the basket. 
 
     
     
         30 . A system for screening a liquid and solids mixture feed, the system comprising:
 screening or liquid and solids separating apparatus for processing the feed to produce at least one processed liquid and solids mixture stream; followed by   an apparatus including a conduit, the conduit being formed and arranged to receive the at least one processed liquid and solids mixture and including a screening portion formed and arranged to divide the processed liquid and solids mixture flowing through the conduit into a first, cleaned stream comprising liquid and solid particles of below a selected size limit, and a second, concentrated, stream comprising liquid, and particles above the selected size limit.   
     
     
         31 . A system according to  claim 30  further comprising screening or liquid and solids separating apparatus for processing the second stream. 
     
     
         32 . A system according to  claim 30  wherein at least the screening portion of the conduit is subject to vibration provided by vibration means.