Method and apparatus for preserving wood, and wood product

A preserved wood product produced by the method comprising:

• A) placing wood for treating in a treatment space;
• B) removing air, in particular, oxygen, from the treatment space;
• C) feeding steam to the treatment space, wherein the temperature of the wood is simultaneously increased, wherein the temperature is raised from 70 degrees Celsius with a temperature gradient of a maximum of 60 degrees Celsius per hour, to a temperature of at least 150 degrees Celsius, wherein the wood is heated at a temperature above 150 degrees Celsius during a reaction time of at least 10 minutes;
• D) polymerizing wood constituents thermally activated in step C by removing moisture from the wood up to a moisture content lower than 5% at a temperature of at least 130 degrees Celsius;
• and
• E) cooling the wood, wherein the moisture content of the wood is simultaneously increased to at least 7% by weight, in the temperature path below 140 degrees.

An apparatus for preserving wood, comprising:

• A) a treatment space sealable in medium-tight manner;
• B) a vacuum pump connected to the treatment space;
• C) a steam source connected to the treatment space;
• D) a heating device which is in thermal contact with the treatment space;
• E) a dispenser for adding predetermined amounts of either a base or an acid to the treatment space;
• F) pH measuring device for determining the pH value of steam in the treatment space;
• and
• G) measuring and control equipment adapted to monitor at least the pH temperature and pressure inside the treatment space and to control the vacuum pump, the steam source and the heat source, and the pH by dispensing either a base or an acid.