Method for the wet-chemical transformation of biomass by hydrothermal carbonization

Abstract

A method for converting biomass into higher-energy-density solids, in particular carbon, humus or peat, is described. In the method, organic substances from the biomass are suspended in water to form a suspension and at least a part of the suspension to be converted is heated to a reaction temperature and is converted into higher-energy-density solids by hydrothermal carbonization at elevated pressure. The conversion is carried out in a reaction volume which is located underneath the Earth's surface. Uniformity of the product quality and an increase in the economic efficiency of the process are achieved by the method.

1 - 22 . (canceled) 
   
   
       23 . A method for converting biomass into higher-energy-density solids, comprising suspending organic substances from the biomass in water to form a suspension, heating at least a part of the suspension to be converted to a reaction temperature and converting into higher-energy-density solids by hydrothermal carbonization at elevated pressure, wherein said converting is carried out in a reaction volume that is located underneath the Earth's surface. 
   
   
       24 . The method according to  claim 23 , further comprising buffering released reaction heat of the reaction volume in a surrounding area corresponding to at least four times a mean diameter of the reaction volume by surrounding the reaction volume with a mass of compact liquid and/or solid material which is greater than eight times the biomass contained in the reaction volume. 
   
   
       25 . The method according to  claim 23 , wherein the converting is carried out at a process pressure which is higher than an equilibrium pressure which would be established at the reaction temperature in a gastight reactor filled with the suspension. 
   
   
       26 . The method according to  claim 24 , wherein the converting is carried out at a process pressure which is higher than an equilibrium pressure which would be established at the reaction temperature in a gastight reactor filled with the suspension. 
   
   
       27 . The method according to  claim 25 , further comprising generating the process pressure hydrostatically by introducing the at least a part of the suspension to be converted into a volume region of a volume filled with water or the suspension up to an upper filling level, wherein a height difference of at least 100 m exists between an upper filling level and the volume region forming the reaction volume. 
   
   
       28 . The method according to  claim 23 , wherein a cavity in the Earth's surface serves as the reaction volume and is filled with water or the suspension. 
   
   
       29 . The method according to  claim 23 , wherein a region below a water surface of a sea or a lake serves as the reaction volume. 
   
   
       30 . The method according to  claim 28 , further comprising inserting at least one reactor in the cavity and filling said at least one reactor with water or the suspension. 
   
   
       31 . The method according to  claim 29 , further comprising inserting at least one reactor in the sea or the lake and filling said at least one reactor with water or the suspension. 
   
   
       32 . The method according to  claim 30 , wherein the at least one reactor is formed with a flexible outer wall. 
   
   
       33 . The method according to  claim 30 , wherein the at least one reactor is inserted in a horizontal or inclined shaft and is surrounded by water, which exhibits a hydrostatic pressure whereby a wall of the reactor is at least partially relieved of pressure in the reactor. 
   
   
       34 . The method according to  claim 30 , wherein the at least one reactor is at least partially perforated to allow passage of gases. 
   
   
       35 . The method according to  claim 28 , further comprising supplying cold water, for slowing conversion of the biomass, in a controlled manner to the reactor or cavity at different heights via cooling water supply lines to avoid overheating. 
   
   
       36 . The method according to  claim 23 , further comprising pumping said at least a part of the suspension to be converted in a pumping direction through the reaction volume, to produce a pulsating flow of the at least a part of the suspension to be converted through the reaction volume by repeated brief reversal of the pumping direction. 
   
   
       37 . The method according to  claim 23 , further comprising generating turbulence in the reaction volume to counter any sedimentation of solids in the reaction volume. 
   
   
       38 . The method according to  claim 23 , further comprising pumping the suspension water or another cooling medium for cooling and using the heat dissipated by the cooling to generate electrical energy. 
   
   
       39 . The method according to  claim 23 , further comprising providing the Earth's heat in the reaction volume sufficient to contribute towards increasing the temperature of the suspension to be converted. 
   
   
       40 . The method according to  claim 23 , further comprising forming a circuit in which the higher-energy-density solids are removed from the suspension after conversion and supplying an added part of the suspension anew to the reaction volume. 
   
   
       41 . The method according to  claim 23 , further comprising separating heavy substances from the suspension before introducing the suspension into the reaction volume. 
   
   
       42 . The method according to  claim 23 , wherein the water contains at least one conversion-promoting substance or at least one conversion-promoting substance is added to the water or the suspension. 
   
   
       43 . The method according to  claim 23 , further comprising adjusting viscosity of the suspension supplied to the reaction volume so that the viscosity is at least 20 mPas. 
   
   
       44 . The method according to  claim 23 , further comprising adjusting viscosity of the suspension supplied to the reaction volume so that a liquid phase extracted from the reaction volume does not exceed a viscosity of 5 mPas. 
   
   
       45 . The method according to  claim 23 , further comprising providing the suspension to be converted in a container which allows pressure exerted on the container to be transferred to contents of the container, wherein the suspension to be converted remains in the container during said converting. 
   
   
       46 . Higher-energy-density solids produced by the method according to  claim 23  comprising fuel or a starting material for a fuel. 
   
   
       47 . Higher-energy-density solids produced by the method according to  claim 23  comprising hydrocarbon-rich liquid fuel.