System and method for preextraction of hemicellulose through using a continuous prehydrolysis and steam explosion pretreatment process

A system for pretreating cellulosic biomass feed stock comprising:

• a first pressurized reactor receiving the feed stock, wherein the feed stock undergoes hydrolysis in the first pressurized reactor at a gauge pressure in a range of 1.5 bar gauge to 6 bar gauge, and at a temperature of at least 110 degrees Celsius;
• a sealing and extraction device having a first pressurized coupling to a feedstock discharge port of the first pressurized reactor and a second pressurized coupling to a second pressurized reactor;
• a wash stage introducing a wash liquid into the feed stock in at least one of the first pressurized reactor and the sealing extraction device;
• a drain for removing a liquid including dissolved hemi-cellulosic material extracted from the feed stock in at least one of the first pressurized reactor and the sealing and extraction device;
• the second pressurized reactor assembly receiving the pressurized feed stock from the sealing and extraction device and infusing a steam or water vapor into the feed stock in the second pressurized reactor, wherein the reactor assembly applies a gauge pressure to the feed stock in a range of 8 bar gauge to 25.5 bar gauge, and the second pressurized reactor assembly having a pressurized discharge coupled to a discharge conduit, and
• an expansion device downstream of the second pressurized reactor assembly, wherein the expansion device rapidly releases the pressure of the feed stock discharged from the second pressurized reactor such that the feed stock undergoes a steam explosion reaction.