COUNTER-CURRENT PROCESS FOR BIOMASS CONVERSION
A countercurrent process is disclosed for converting solid biomass material. The solid biomass material travels through a reactor system in countercurrent with hot heat carrier materials, such as particulate heat carrier material and hot gases. The solid biomass material is subjected to a first conversion at a first temperature T 1, and a second conversion at a second temperature, T 2, such that T 2>T 1. Bio-oil produced to at T 1 is not exposed to the higher temperature T 2. As a result, secondary reactions of the bio-oil components are minimized.
1 . A countercurrent process for the conversion of biomass material, said process comprising the steps of
(i) providing a solid particulate biomass material;
(ii) heating the solid particulate biomass material to a first temperature T1 in a first conversion zone to thereby convert a first portion of the solid particulate biomass material into first gaseous reaction products while leaving a second portion of the solid particulate biomass material unconverted;
(iii) transferring at least part of the first gaseous reaction products from the first conversion zone to a first condenser; and
(iv) heating at least part of the second portion of the solid particulate biomass material to a second temperature T 2 in a second conversion zone by contacting the second portion of the solid particulate biomass material with a hot gas flowing countercurrent to the solid articulate biomass material and/or a hot particulate heat carrier material wherein T2>T1.
2 . The process of claim 1 wherein step (ii) comprises mixing the solid particulate biomass material with a hot heat carrier material.
3 . The process of claim 2 wherein, prior to or during step (ii), the solid particulate biomass material is contacted with a catalyst.
4 . The process of claim 3 wherein the catalyst is in a solid particulate form.
5 . The process of claim 4 wherein the heat carrier material comprises the solid particulate catalyst.
6 . The process of claim 5 wherein a mixture of solid reaction by-products and solid particulate catalyst is retrieved from the first conversion zone.
7 . The process of claim 6 comprising the farther step of separating the solid particulate catalyst from the solid reaction by-product.
8 . The process of claim 1 wherein said first gaseous reaction product comprises condensable and non-condensable gases, further comprising the step of converting at least part of the condensable gases to a liquid in the first condenser.
9 . The process of claim 8 further comprising the step of combusting at least part of the non-condensable gases.
10 . The process of claim 9 wherein heat generated by the combustion of the at least part of the non-condensable gases is used to heat the heat carrier material.
11 . The process of claim 10 wherein at least part of the flue gas produced in the combustion of the at least part of the non-condensable gases is used as the hot gas in step (iv).
12 . The process of claim 11 wherein flue gas is separated from heat carrier material in a cyclone.
13 . The process of claim 11 wherein the flue gas comprises CO.
14 . The process of claim 1 which is carried out in a cascade of at least two reactors.
15 . The process of claim 14 wherein the first of the cascade of reactors is a cyclone.
16 . The process of claim 15 wherein, in the first of the cascade of reactors, biomass particles are brought into contact at high velocity with solid heat carrier particles.
17 . The process of claim 1 wherein the first conversion zone is operated at a temperature in the range of from 80 to 50° C.
18 . The process of claim 1 which is carried out in a series of at least two vertical tube reactors.
19 . The process of claim 1 which is carried out in a countercurrent auger reactor.
20 . The process of claim 1 which is carried out in a series of vertical tube reactors.
21 . An apparatus for carrying out the process claim 1 , said apparatus comprising (i) a first reactor operated at a temperature in the range of from 80 to 50° C., wherein biomass particles are mixed with catalyst particles; (ii) a second reactor operated at a temperature in the range of 200-450° C.; and (iii) a third reactor operated at a temperature in the range of from 400 to 550° C.
22 . The process of claim 1 wherein said first and second conversion zones are located in separate reactors.
23 . The process of claim 1 wherein said first and second conversion zones are distinct zones of a single reactor.
24 . The process of claim 1 wherein T 1 and T 2 differ by 50 to 200° C.
25 . The process of claim 1 further comprising the step of condensing at least part of the first gaseous reaction products in the first condenser to thereby form liquid bio-oil.
26 . The process of claim 1 wherein said heating of step (iv) converts at least part of the second portion of the biomass material into second gaseous reaction products.
27 . The process of claim 26 further comprising the step of condensing at least part of the second gaseous reaction to thereby form liquid bio-oil.
28 . The process claim 1 wherein flash pyrolysis is carried out in at least one of the first and second conversion zones.
29 . The process of claim 28 wherein said flash pyrolysis is carried out in the presence of a catalyst.