An apparatus and process for
solvent pulping of
cellulose-containing
biomass utilizes at least one
steaming vessel, a plug screw feeder or
compression screw device, at least one super-atmospheric impregnation vessel, a
solvent delignification reactor capable of operating at a pressure of 350 psig or more, and a
solvent containing line for introducing solvent-containing liquor at the plug screw feeder outlet or
compression screw device outlet. The process and
system can also include at least one series connected pressure diffuser and optionally a retention tube downstream of each pressure diffuser to provide sufficient
retention time to substantially preclude re-deposition of
lignin on the
cellulose fibers of the
biomass, a blow tank connected to the last of the pressure diffusers and retention tubes, and vessels for multistage
alcohol washing. The method steams the
biomass and impregnates it with solvent to produce an aqueous
slurry of biomass and solvent, delignifies the particulate biomass in the
slurry, removes solvent while continuing delignification of the biomass in the
slurry and while substantially precluding re-deposition of
lignin on the
cellulose of the biomass, reduces the pressure of the slurry; and then washes the slurry.