Apparatus for reacting lignocellulosic material with a gas phase comprising a nitrogen oxide and oxygen under controlled gas pressure

Claim 1

Apparatus for reacting lignocellulosic material with a gas phase comprising a nitrogen oxide and oxygen under controlled gas pressure in the presence of water, as a pretreatment before an alkaline delignification, the oxygen suppressing rapid initial reactions between nitrogen oxide and lignin leading to demethylation of the lignin, and indirectly leading to decreases in the regeneration of consumed nitrogen oxide by secondary reactions between modified lignin, nitric acid and oxygen gas resulting in the formation of an active form of nitrogen oxide; while promoting reactions between nitrogen oxide and water forming nitric acid; reoxidation of reduced nitrogen oxide; and the secondary oxidation with oxygen of modified lignin and nitrogen oxide, comprising, in combination, in continuous flow sequence; (1) a supply of water-containing lignocellulosic material, a supply of nitrogen oxide, and a supply of oxygen containing gas; (2) a first reaction chamber receiving a continuous flow of water-containing lignocellulosic material, and nitrogen oxide from the supply of water-containing lignocellulosic material and the supply of nitrogen oxide; (3) a first inlet for introducing lignocellulosic material into the first reaction chamber; (4) a second inlet with control means for introducing nitrogen oxide into the first reaction chamber; (5) a first outlet for withdrawing a continuous flow of lignocellulosic material after reaction with nitrogen oxide from the first reaction chamber; (6) gas locks retaining gas pressure in the first reaction chamber at each of the first inlet and first outlet; (7) a second reaction chamber in connection with the first reaction chamber via the gas lock at the outlet thereof and receiving a continuous flow of lignocellulosic material from the first reaction chamber after reaction with nitrogen oxide; (8) a third inlet with control means for introducing oxygen from the supply of oxygen containing gas into the second reaction chamber; (9) a second outlet for withdrawing a continuous flow of lignocellulosic material after reaction with oxygen from the second reaction chamber; and (10) a gas lock retaining gas pressure in the second reaction chamber at the second outlet; the second reaction chamber having a volume that is at least 2.5 times the volume that is at least 2.5 times the volume of the first reaction chamber.