NOVELTY - The classifier (100) has a separator conduit (102) extending between a flow input (104) and a flow output (106) to define flow axis (108) along a portion of the separator conduit. A cross-flow input (114) and a cross-flow output (116) are in fluid communication with the separator conduit between the flow input and the flow output, where the cross-flow input is located upstream of the cross-flow output with respect to the flow axis and defines a cross-flow axis (118) intersecting the flow axis at cross-flow angle (120) between 700 and 1800 with respect to the flow axis.    USE - Cross-flow char particle classifier for use in a pyrolysis system (claimed) i.e. auger based pyrolysis system, for biomass processing application.    ADVANTAGE - The classifier allows a particle separator to separate micron-sized particles in air quality testing to separating immiscible fluids in dryer systems and operates at moderate gas cross-flow rates in an efficient manner.    DETAILED DESCRIPTION - The classifier allows a particulate made of glass, ceramic, mineral, polymeric composite, steel, cobalt, molybdenum, nickel, titanium, tungsten, zinc, antimony, bismuth, cerium, vanadium, niobium, tantalum, chromium, manganese, rhenium, iron, platinum, iridium, palladium, osmium, rhodium, ruthenium, copper impregnated zinc oxide, copper impregnated chromium oxide, nickel aluminum oxide, palladium aluminum oxide, cobalt molybdenum, nickel molybdenum, nickel molybdenum tungsten, sulfided cobalt molybdenum, sulfided nickel molybdenum, and metal carbide. INDEPENDENT CLAIMS are also included for the following:    (1) a pyrolysis system    (2) a method for performing cross-flow separation    (3) a pyrolysis method.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a cross-flow char particle classifier.    Cross-flow char particle classifier (100)    Separator conduit (102)    Flow input (104)    Flow output (106)    Flow axis (108)    Cross-flow input (114)    Cross-flow output (116)    Cross-flow axis (118)    Cross-flow angle (120)