Disclosed is a filter medium for removing contaminants, including gels, from molten polymers. The medium contains layers of sintered metal fibers having diameters of 50 microns or less. At least two adjacent layers are separated by a screen, and the screen and layers are bonded together by compression and sintering. Preferably the layers include from 35 to 60 volume percent fibers. The filter medium is graded so that the polymer as it flows through the medium encounters fiber layers having pores that generally decrease in size. The screen has pores that are larger than the average size of the pores in any downstream layer and that are larger than the average size of the pores in the upstream layer immediately adjacent the screen. The screen collects at least some of the gels or other particles that pass through the upstream layer, giving the medium a higher dirt holding capacity than the conventional filter medium.
CROSS REFERENCE OF CO-PENDING APPLICATION
This application is a continuation application of co-pending application Ser. No. 679,486, filed Apr. 23, 1976, now abandoned.
A filter medium includes at least a first and a second layer. Both first and second layers have a layer volume VLq and a layer filtering surface SLq, where SLq is the accumulation of all mantle surfaces of the fibers present in this layer q. The first layer has a SL1/VL1-ratio of less than 32500 m.sup.2/m.sup.3, and the second layer has a SL2/VL2-ratio being more than 1.1.times.SL1/VL1.
A method for manufacturing a porous laminate includes continuously passing a laminate preform having a metal wire mesh and a metal non-woven fiber web superposed on the wire mesh between rotating pressure rollers having differing electrical potentials. The fibers of the non-woven web are sintered together at mutual points of contact and to the mesh by passing an electrical current cross-sectionally through the laminate preform in a zone of contact with the rollers, thereby forming the porous laminate.
Disposable filter element, adapted for use in a high-pressure filter housing, has a plurality of layers of flexible filtering material, some layers being formed with openings through which a portion of the fluid can flow without being filtered, and at least one downstream layer of the filtering material being free from such openings. When all of the layers of filtering material have the same pore size, the total area of the openings in each layer is larger than that of the openings of any downstream layer. Each opening-containing layer of the filtering material removes part of the contaminant in the fluid. Interposed between adjacent opening-containing filtering layers is a layer of flexible transport material, and there is a layer of flexible prefiltering material positioned upstream of said filtering layers. The prefiltering material has a porosity to filter out from the fluid any particle that is substantially as large as the openings of the most upstream of the filtering layers to guard against an opening becoming blocked by such a particle.
A coal-fired power generation system including means for the production of coal-derived gas and a filter system for the filtration of this coal-derived gas. The filter system comprises at least one high temperature and, corrosion resistant filter. The filter is made from a Fe--Cr--Al based alloy further comprising at least one additional element selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta and the lanthanides.
A substantially cylindrical, unitized filter element for separating contaminant material from a flowing media includes an outer, substantially cylindrical wall portion which is fabricated by a two step process involving both a compacting step followed by a sintering step. The result of these processing steps is to create a rigid, porous filtering matrix. The filter element also includes an inner, substantially cylindrical wall portion which is also constructed through a two step process of a granular material which has been compacted and sintered into a rigid and porous filtering matrix. Disposed between the two cylindrical wall portions is a substantially cylindrical structural support member which is fabricated from a non-restrictive material and a material which is compatible with the material selected for the inner and outer wall portions. The structural support member is positioned between the two wall portions prior to the compacting process step and is sintered to the outer and inner wall portions in order to create a unitized filter element.
