Reaction apparatus and a process for the gasification of wet biomass

Abstract

A reaction apparatus for the gasification of wet biomass comprises a feeding system for feeding wet biomass at a pressure of at least 22.1 MPa (absolute), a reactor comprising a reaction tube and a heating device, and a recovery system. The reaction tube is configured to comprise a bed of solid particles suspended in a fluid, and to receive wet biomass from the feeding system at a temperature below the critical temperature of water. The bed of solid particles suspended in a fluid is a bubbling fluidised bed having a length of at least 0.5 m and a cross sectional area of at most 20 dm 2 . The heating device is configured to heat the feed in the presence of the bed of suspended solid particles to a temperature above the critical temperature of water by heat exchange with a heating fluid, forming supercritical water and fluid gasification product. The reaction tube is adapted to allow wet biomass to pass in the longitudinal direction of the reaction tube, and co-currently or counter-currently with the heating fluid. Also claimed: a process for the gasification of wet biomass.

1 . A reaction apparatus for the gasification of wet biomass, which reaction apparatus comprises
 a feeding system for feeding wet biomass at a pressure of at least 22.1 MPa (absolute),   a reactor comprising a reaction tube and a heating device, wherein
 the reaction tube is fluidly connected to the feeding system, 
 the reaction tube is configured to comprise a bed of solid particles suspended in a fluid, and to receive wet biomass from the feeding system at a temperature below the critical temperature of water, and 
 the heating device is configured to heat the feed in the presence of the bed of suspended solid particles to a temperature above the critical temperature of water by heat exchange with a heating fluid, forming supercritical water and fluid gasification product, and 
   a recovery system, which recovery system is fluidly connected to the reaction tube for receiving fluid gasification product from the reaction tube, in which reaction apparatus   the reaction tube is adapted to allow wet biomass to pass in the longitudinal direction of the reaction tube, and co-currently or counter-currently with the heating fluid, and   the bed of solid particles suspended in a fluid is a bubbling fluidised bed having a length of at least 0.5 m and a cross sectional area of at most 20 dm 2 .   
     
     
         2 . A reaction apparatus as claimed in  claim 1 , wherein the reaction apparatus comprises a plurality of the reaction tubes in a parallel arrangement. 
     
     
         3 . A reaction apparatus as claimed in  claim 2 , wherein the number of reaction tubes is in the range of from 2 to 20 (inclusive), in particular in the range of from 3 to 10 (inclusive). 
     
     
         4 . A reaction apparatus as claimed in  claim 1 , wherein the reactor additionally comprises a distribution plate. 
     
     
         5 . A reaction apparatus as claimed in  claim 1 , wherein the bed of solid particles suspended in a fluid has a length in the range of from 0.5 m to 10 m and a cross sectional area in the range of from 1 cm 2  to 20 dm 2 . 
     
     
         6 . A reaction apparatus as claimed in  claim 5 , wherein the bed of solid particles suspended in a fluid has a length in the range of from 1 m to 5 m and a cross sectional area in the range of from 2 cm 2  to 5 dm 2 . 
     
     
         7 . A reaction apparatus as claimed in  claim 1 , wherein the bed of solid particles suspended in a fluid has the shape of a circular cylinder having a length to diameter ratio in the range of from 5 to 50, in particular in the range of from 8 to 30. 
     
     
         8 . A reaction apparatus as claimed in  claim 1 , wherein the heating device comprises a heating jacket and/or one or more heating pipes adapted to allow a heating fluid to flow through. 
     
     
         9 . (canceled) 
     
     
         10 . A reaction apparatus as claimed in  claim 1 , wherein the reaction tube is adapted to allow wet biomass to pass counter-currently with the heating fluid. 
     
     
         11 . A process for the gasification of wet biomass, which process comprises
 feeding the wet biomass at a temperature of at most 370° C. and a pressure of at least 22.1 MPa (absolute) to a reactor comprising a bubbling fluidised bed of solid particles suspended in a fluid, which bubbling fluidised bed has a length of at least 0.5 m and a cross sectional area of at most 20 dm 2 ,   increasing the temperature of the feed in the presence of the bed of suspended solid particles to a temperature of at least 375° C., forming supercritical water, and   converting in the presence of the supercritical water at least a portion of the organic materials present in the wet biomass into fluid gasification product.   
     
     
         12 . A process as claimed in  claim 11 , wherein the wet biomass is selected from fermentation residues, sewage sludge, dredging sludge, algae, animal manures, and mixtures thereof, and wherein the wet biomass comprises at least 40% w of water, relative to the total weight of the wet biomass. 
     
     
         13 . A process as claimed in  claim 11 , wherein the wet biomass is fed at a temperature in the range of from 280° C. to 360° C., in particular in the range of from 300° C. to 350° C., and at a pressure in the range of from 22.1 MPa to 50 MPa, in particular in the range of from 22.5 MPa to 35 MPa. 
     
     
         14 . A process as claimed in  claim 11 , wherein the temperature of the feed is increased in the presence of the bed of suspended solid particles to a temperature in the range of from 400° C. to 800° C., in particular in the range of from 420° C. to 760° C. 
     
     
         15 . A process as claimed in  claim 11 , wherein the fluid is an aqueous fluid. 
     
     
         16 . A process as claimed in  claim 11 , wherein the suspended solid particles comprises particles selected from minerals or aggregates of minerals, crushed rock or crushed stone, salts, metals, crystalline or non-crystalline ceramics, and mixtures thereof. 
     
     
         17 . A process as claimed in  claim 11 , wherein the process comprises
 heating wet biomass at a pressure P p  in the range of from 22.1 MPa to 35 MPa (absolute) from a temperature of at most T 1  to a temperature of at least T 2  by heat exchange with a first heating fluid, upon which heating the fluid gasification product is obtained,   further heating the fluid gasification product, and   using the further heated fluid gasification product as the first heating fluid, upon which use the further heated fluid gasification product is cooled down at a pressure P s  in the range of from 22.1 MPa to 35 MPa (absolute) from a temperature of at least T 3  to a temperature of at most T 4 ,   
       wherein T 1 , T 2 , T 3  and T 4  are temperatures in ° C. which can be calculated by using the mathematical formulae
     T   1 =3.2× P   p +301.6,
 
     T   2 =3.8× P   p +292.4,
 
     T   3 =3.8× P   s +292.4, and
 
     T   4 =3.2× P   s +301.6,
 
 
       wherein P p  and P s  denote the pressures P p  and P s , respectively, in MPa. 
     
     
         18 . A process as claimed in  claim 17 , wherein T 1 , T 2 , T 3  and T 4  are temperatures in ° C. which can be calculated by using the mathematical formulae
     T   1 =2.9× P   p +306.2,
 
     T   2 =4.1× P   p +287.8,
 
     T   3 =4.1× P   s +287.8, and
 
     T   4 =2.9× P   s +306.2,
 
 
       wherein P p  and P s  denote the pressures P p  and P s , respectively, in MPa having values in the range of from 22.1 MPa to 33 MPa. 
     
     
         19 . A process as claimed in  claim 18 , wherein T 1 , T 2 , T 3  and T 4  are temperatures in ° C. which can be calculated by using the mathematical formulae
     T   1 =2.6× P   p +310.8,
 
     T   2 =4.4× P   p +283.2,
 
     T   3 =4.4× P   s +283.2, and
 
     T   4 =2.6× P   s +310.8,
 
 wherein P p  and P s  denote the pressures P p  and P s , respectively, in MPa having values in the range of from 22.1 MPa to 32 MPa.