Filter-Press with Integrated RF Heating

Abstract

A method of separating a mixture of liquid and insoluble solids in a filter press may comprise: pumping the mixture into a chamber between two filter plates in the filter press to form a filter cake, wherein the chamber is lined by filter cloths, and wherein, during the pumping, filtrate is forced through the filter cloths and out of the chamber; heating the filter cake in the chamber, wherein, during the heating, filtrate is forced through the filter cloths and out of the chamber, and wherein the heating is by radio frequency irradiation of the filter cake in the chamber; and releasing dried filter cake from the chamber. A filter press system for separating a mixture of liquid and insoluble solids may comprise: a frame; a plurality of filter plates configured to form a stack of parallel plates, each of the plurality of filter plates being movably attached to the frame, the plurality of filter plates further being configured to form a multiplicity of chambers, each of the multiplicity of chambers being lined by filter cloths, wherein the plurality of filter plates, the multiplicity of chambers and the filter cloths are configured to allow filtrate to escape from the chambers while retaining solids from the mixture to form a filter cake; and a radio frequency heater, for directly heating the filter cake in the multiplicity of chambers. The radio frequency heating may include microwave heating, or dielectric heating by lower frequency radio waves in the range of 1 to 100 MHz.

What is claimed is: 
     
         1 . A method of separating a mixture of liquid and insoluble solids in a filter press, said method comprising:
 pumping said mixture into a chamber between two filter plates in said filter press to form a filter cake, wherein said chamber is lined by filter cloths, and wherein, during said pumping, filtrate is forced through said filter cloths and out of said chamber;   heating said filter cake in said chamber, wherein, during said heating, filtrate is forced through said filter cloths and out of said chamber; and   releasing dried filter cake from said chamber;   wherein said heating is by radio frequency irradiation of said filter cake in said chamber.   
     
     
         2 . A method as in  claim 1 , wherein said radio frequency irradiation is microwave irradiation. 
     
     
         3 . A method as in  claim 2 , wherein said microwave irradiation is at a frequency between 300 and 3000 MHz. 
     
     
         4 . A method as in  claim 1 , wherein said radio frequency irradiation is applied by a system including parallel electrode plates configured (1) with the planes of said parallel electrode plates roughly orthogonally to the planes of each of said plurality of filter plates, (2) in close proximity to the outer surface of said plurality of filter plates, and (3) on either side of said plurality of filter plates. 
     
     
         5 . A method as in  claim 4 , wherein said radio frequency irradiation is at a frequency between 1 and 100 MHz. 
     
     
         6 . A method as in  claim 1 , further comprising, during said heating, vacuum pumping said chamber. 
     
     
         7 . A method as in  claim 1 , further comprising squeezing said filter cake in said chamber. 
     
     
         8 . A method as in  claim 7 , wherein each of said plurality of filter plates includes an envelope, said envelope being inflatable by a fluid, and wherein said squeezing includes inflating said envelopes with said fluid. 
     
     
         9 . A method as in  claim 8 , wherein said fluid is steam. 
     
     
         10 . A method as in  claim 8 , wherein said fluid is compressed air. 
     
     
         11 . A method as in  claim 1 , wherein said filtrate forced through said filter cloths and out of said chamber during said heating includes filtrate vapor. 
     
     
         12 . A method as in  claim 1 , wherein said filtrate is water and said dried filter cake contains less than 10% water by weight. 
     
     
         13 . A method as in  claim 12 , wherein said dried filter cake contains less than 1% water by weight. 
     
     
         14 . A method as in  claim 1 , wherein said filter press comprises a plurality of said filter plates and a multiplicity of said chambers. 
     
     
         15 . A method as in  claim 14 , wherein said plurality is N and said multiplicity is M, M is equal to N−1, and N and M are integers. 
     
     
         16 . A method of separating a mixture of liquid and insoluble solids in a filter press including a plurality of filter plates, said method comprising:
 pumping said mixture into a multiplicity of chambers to form a filter cake, each of said multiplicity of chambers being between adjacent filter plates of said plurality of filter plates, each of said multiplicity of chambers being lined by filter cloths, wherein, during said pumping, filtrate is forced through said filter cloths and out of said multiplicity of chambers;   heating said filter cake in said multiplicity of chambers, wherein, during said heating, filtrate is forced through said filter cloths and out of said multiplicity of chambers; and   releasing dried filter cake from said multiplicity of chambers;   wherein said heating is by radio frequency irradiation of said filter cake in said chambers.   
     
     
         17 . A method as in  claim 16 , wherein said plurality is N and said multiplicity is M, M is equal to N−1, and N and M are integers. 
     
     
         18 . A filter press system for separating a mixture of liquid and insoluble solids, said filter press system comprising:
 a frame;   a plurality of filter plates configured to form a stack of parallel plates, each of said plurality of filter plates being movably attached to said frame, said plurality of filter plates further being configured to form a multiplicity of chambers, each of said multiplicity of chambers being formed by adjacent filter plates of said plurality of filter plates, each of said multiplicity of chambers being lined by filter cloths, wherein said plurality of filter plates, said multiplicity of chambers and said filter cloths are configured to allow filtrate to escape from said chambers while retaining solids from said mixture to form a filter cake; and   a radio frequency heater, for directly heating said filter cake in said multiplicity of chambers.   
     
     
         19 . A filter press system as in  claim 18 , wherein said radio frequency heater comprises parallel electrode plates attached to said frame and electrically coupled to a radio frequency generator, said parallel electrode plates being configured with the planes of said parallel electrode plates roughly orthogonally to the planes of each of said plurality of filter plates, and in close proximity to the outer surface and on either side of said plurality of filter plates. 
     
     
         20 . A filter press system as in  claim 19 , wherein said parallel electrode plates include multiple pairs of parallel electrode plates. 
     
     
         21 . A filter press system as in  claim 20 , wherein each of said multiple pairs of parallel electrode plates is coupled to a separate radio frequency generator. 
     
     
         22 . A filter press system as in  claim 18 , wherein said radio frequency heater comprises a microwave antenna positioned in an aperture extending centrally through said plurality of filter plates, said microwave antenna being roughly orthogonal to the planes of each of said plurality of filter plates. 
     
     
         23 . A filter press system as in  claim 22 , wherein said microwave antenna is configured to be retractable from said aperture extending centrally through said plurality of filter plates. 
     
     
         24 . A filter press system as in  claim 18 , wherein said radio frequency heater comprises multiple microwave antennae embedded in a plurality of filter plates. 
     
     
         25 . A filter press system has in  claim 24 , wherein said multiple microwave antennae are embedded in every P th  of said plurality of filter plates, P being an integer greater than 1. 
     
     
         26 . A filter press system as in  claim 18 , wherein said radio frequency heater comprises multiple microwave horns positioned on the surface of said plurality of filter plates and configured to direct microwave radiation into said chambers. 
     
     
         27 . A filter press system as in  claim 18 , further comprising a radio frequency screen in close proximity to the surface of said plurality of filter plates for absorbing radio frequency radiation emanating from said filter press. 
     
     
         28 . A filter press system as in  claim 18 , wherein said plurality of filter plates are made of plastics. 
     
     
         29 . A filter press system as in  claim 18 , wherein said frame is nonmetallic.