Method for cleaning a reactor for processing a lignocellulosic biomass
The present invention relates to a processing method at acidic or neutral pH in a reactor ( 4 ) for processing lignocellulosic biomass (P), said process including a continuous cleaning phase of the reactor which comprises introducing a basic aqueous solution (EB) into said reactor containing the biomass being processed.
1 . A process for treatment of a lignocellulosic biomass (P), said process comprising:
impregnating the lignocellulosic biomass (P) with an acidic aqueous solution (EA) in an impregnation reactor ( 3 ) to form an impregnated lignocellulosic biomass (P),
pretreating the impregnated lignocellulosic biomass (P) in a pretreatment reactor ( 4 ), and
providing a phase of continuous cleaning of the pretreatment reactor ( 4 ) while pretreating the impregnated lignocellulosic biomass (P) in a pretreatment reactor ( 4 ), wherein the phase of continuous cleaning comprises:
introducing a basic aqueous solution (EB) into said pretreatment reactor ( 4 ) containing the impregnated lignocellulosic biomass (P), and
adjusting a concentration of the basic aqueous solution (EB) to increase a pH of the impregnated lignocellulosic biomass (P) in the pretreatment reactor ( 4 ) from an acidic pH range of between 0.5 and 3, to a basic pH range of between 8 and 14,
wherein the pH of the basic aqueous solution (EB) before introduction into the pretreatment reactor ( 4 ) is greater than or equal to 9.
2 . The process as claimed in claim 1 , wherein the basic aqueous solution (EB) is heated before introduction into the pretreatment reactor ( 4 ) to a temperature of at least 40° C.
3 . The process as claimed in claim 1 , wherein the pretreatment reactor, has an internal volume and wherein the temperature of the internal volume of the pretreatment reactor is at least 120° C. when the basic aqueous solution is introduced.
4 . The process as claimed in claim 1 , wherein the introduction of the basic aqueous solution (EB) into said pretreatment reactor ( 4 ) containing the impregnated lignocellulosic biomass (P) has a duration of between 15 minutes and 8 hours.
5 . The process as claimed in claim 1 , wherein during the phase of continuous cleaning of the pretreatment reactor ( 4 ), the basic aqueous solution (EB) has a residence time in said pretreatment reactor ( 4 ) of between 5 and 15 minutes.
6 . The process as claimed in claim 1 , wherein during the phase of continuous cleaning of the pretreatment reactor ( 4 ), the basic aqueous solution (EB) is introduced at an inlet of said pretreatment reactor ( 4 ) at flow rate, the process as claimed in claim 1 , further comprises adjusting the flow rate so that a solids content SC of the lignocellulosic biomass (P) decreases during its passage through the pretreatment reactor from a value of 30% SC to 60% SC.
7 . The process as claimed in claim 1 further comprising:
introducing a change to at least one of a physical, chemical or rheological characteristic of the impregnated lignocellulosic biomass (P) in the pretreatment reactor ( 4 ) during the continuous cleaning phase.
8 . The process as claimed in claim 1 , wherein pretreating the impregnated lignocellulosic biomass (P) in a pretreatment reactor ( 4 ) is achieved by steam explosion cooking, wherein said steam explosion cooking provides steam having thermal energy in the pretreatment reactor ( 4 ),
the process of claim 1 further comprising:
exhausting at least a first portion of the steam at an outlet of a separation device ( 5 ) is positioned at an outlet of the pretreatment reactor ( 4 ),
recovering said thermal energy of the at least first portion of steam via a heat exchanger, and heating one of the basic aqueous solution (EB), an acidic aqueous solution (EA), or a neutral aqueous solution (E), and
condensing a second portion of the steam via a condenser.
9 . The process as claimed in claim 1 , further comprising reducing or eliminating acid content of the acidic aqueous solution (EA).
10 . The process as claimed in claim 1 , wherein during the phase of continuous cleaning of the pretreatment reactor ( 4 ), the acidic aqueous solution (EA) is replaced by the basic aqueous solution (EB), or by an aqueous solution (E) having a neutral pH.
11 . The process as claimed in claim 1 , wherein the impregnation of the lignocellulosic biomass (P) is realized via a first impregnation reactor ( 3 ) and a second impregnation reactor ( 3 ′) used in parallel,
the first impregnation reactor ( 3 ) is fed with an acidic aqueous solution (EA) or with an aqueous solution (E) of neutral pH, and the second impregnation reactor ( 3 ′) is fed with basic aqueous solution (EB),
wherein the first impregnation reactor ( 3 ) and a second impregnation reactor ( 3 ′) are operate alternately, and
wherein the second reactor ( 3 ′) is operational during the phase of continuous cleaning the pretreatment reactor ( 4 ).
12 . The process as claimed in claim 1 further comprising:
separating the lignocellulosic biomass (P) and an aqueous phase in liquid or vapor form at an outlet of the pretreatment reactor ( 4 ) by a separation device ( 5 ), and
wherein the phase of continuous cleaning of the pretreatment reactor ( 4 ) comprises, at least one rinsing of the separation device by an aqueous solution (E) after introduction of the basic aqueous solution (EB) into the pretreatment reactor ( 4 ).