NOVELTY - The apparatus has a stator (20F) and rotor (20R) that are spaced apart from each other. A motor rotates rotor with respect to stator so that rotational movement of rotor imparts tangential shear to predefined volume of pretreated biomass at preset pressure and temperature while biomass is moving in direction of pressure difference between inlet and outlet. Shear homogenizes volume of pretreated biomass and pressure difference to cause partial phase separation of homogenized biomass into vapor and liquid phases so that pretreated biomass undergoes three-fold total volumetric increase.    USE - Combined tangential shear homogenizing and flashing apparatus for destructuring pretreated biomass such as cellulosic or lignocellulosic biomass. Uses include but are not limited to biomass such as aquatic or terrestrial plants, macroalgae, microalgae, grasses, trees, other energy crops, corn stover, forestry byproducts , biomass processing byproducts such as bagasse and sawdust, and postconsumer product such as office paper, retail waste and municipal solid waste derived from aquatic or terrestrial plants.    ADVANTAGE - The apparatus can easily and effectively homogenize cellulosic or lignocellulosic biomass by imposing tangential shear on the biomass while simultaneously exposing the biomass to a flashing operation. The biomass can be destructured efficiently. The time, investment and energy required for destructuring the biomass can be reduced. The apparatus assists in the destructuring process by homogenizing the pretreated biomass while simultaneously causing a partial phase separation of the homogenized biomass into vapor and liquid phases. The gap adjustment control system enables the apparatus to automatically adjust the gap between the rotor and the stator and to compensate for variations in pretreated biomass composition, flow properties and particulate size. This ability to vary the gap between the stator and rotor allows the apparatus to function as a metering device.    DETAILED DESCRIPTION - The inlet of the housing (20H) is connected to a source of pressurized pretreated biomass while the outlet is arranged in direct fluid communication with a downstream utility. The stator and rotor which is spaced apart from each other to define a mixing zone (20Z) communicating with the inlet and outlet. The rotor and the stator are arranged such that the gap between the stator and rotor defines a radially outer region (20GM) of the mixing zone having a uniform dimension and a radially inner region (20Gi) of the mixing zone having a section exhibiting a non-uniform dimension. A valve is provided in the radially outer region. The pretreated biomass undergoes a weight transition to a vapor of 1%. The flow diverter is mounted between the rotor and the stator for conducting biomass into the mixing zone. The stator is provided with a cylindrical portion having a predetermined axial dimension. The substantially cylindrical barrel having a predetermined axial dimension is mounted to the rotor and extended axially from the rotor into nested relationship with the cylindrical portion of the rotor. The extending milling zone is formed between the barrel and the cylindrical portion of housing. The barrel of the stator is provided with an array of mixing enhancers. The flow diverter is mounted at the axially upstream end of barrel.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the combined tangential shear homogenizing and flashing apparatus.    Stator (20F)    Radially outer region (20GM)    Radially inner region (20Gi)    Housing (20H)    Rotor (20R)