Method for continuous acetylation of wood elements

Method for continuous acetylation of wood elements, wherein the acetylation is conducted with an acetylation medium under wood acetylation reaction conditions at a pressure of at least 1.5 barg in a substantially oxygen free environment,

• wherein the method comprises:
• a) providing wood elements in a batch vessel;
• b) batchwise removing oxygen from the wood elements in said batch vessel using vacuum, providing oxygen-removed wood elements;
• c) thereafter bringing the oxygen-removed wood elements under an oxygen-free inert atmosphere;
• d) transferring the oxygen-removed wood elements under said oxygen-free inert atmosphere from said batch vessel into a continuous acetylation reactor;
• e) after the oxygen removal and before acetylation, bringing the oxygen-removed wood elements under increased pressure of at least 1.5 barg;
• and
• f) treating the wood elements with an acetylation medium in said continuous acetylation reactor under wood acetylation reaction conditions, at a pressure of at least 1.5 barg and under an oxygen content in the acetylation reactor that is less than 0.8 vol. %,
• wherein at least 80 wt. % of the acetylation medium is supplied to the wood elements after the wood elements are at a pressure of at least 1.5 barg.