# US 8,465,845 B2 · Method and apparatus for preserving wood, and wood product > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,465,845 B2 - Document ID: US8465845B2 - Status: Granted - Kind: B2 - Application number: 12/520,770 - Filed: 2007-12-20 - Published: 2010-06-10 - Granted: 2013-06-18 - Earliest claimed: 2006-12-22 - Assignees: Firmowood Nederland B.V. - Applicants: Wilhelmus Petrus Martinus Willems - Inventors: Wilhelmus Petrus Martinus Willems - Web page: https://patentgrep.com/patent/US8465845B2 ## CPC - B27K 1/00: Damping wood - B27K 5/009: {using a well-defined temperature schedule} - B27K 5/04: Combined bleaching or impregnating and drying of wood - C08L 97/02: Lignocellulosic material, e.g. wood, straw or bagasse {(manufacture of articles made from lignocellulosic material by dry processes B27N)} - B27K 3/025: {Controlling the process} - Y10T 428/31986: Regenerated or modified - Y10T 428/31989: Of wood - Y10T 428/662: Wood timber product [e.g., piling, post, veneer, etc.] - B27K: PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR (applying liquids or other fluent materials to surfaces in general B05; coating wood or similar material B44D); CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An apparatus for preserving wood product comprising, in one embodiment, a treatment space sealable in medium-tight manner; a vacuum pump connected to the treatment space; a steam source connected to the treatment space; a heating device which is in thermal contact with the treatment space; a dispenser for adding predetermined amounts of either a base or an acid to the treatment space; pH measuring device for determining the pH value of steam in the treatment space; and 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. Also disclosed is a method for preserving wood. The preservation process has a relatively short process time, wherein a good preservation is realized while the mechanical strength of the wood is largely retained. The amount of waste wood material is greatly reduced. ## Claims ### Claim 1 A method for preserving wood, comprising: A) placing wood for treating in a treatment space; B) removing air, in particular, oxygen, from the treatment space; C) feeding steam into 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. ### Claim 2 (depends on 1) The method of claim 1, further comprising a step F between steps C and D, step F comprising: F) compressing the heated wood. ### Claim 3 (depends on 1) The method of claim 1, wherein the steam has a maximum degree of saturation of 95% during step C. ### Claim 4 (depends on 1) The method of claim 1, wherein at least a part of the oxygen is removed in step B by placing the treatment space under reduced pressure. ### Claim 5 (depends on 4) The method of claim 4, wherein the reduced pressure is lower than 13 kPa. ### Claim 6 (depends on 1) The method of claim 1, wherein the pH of the steam is adjusted at least during step C to a value between 3.0 and 6.0 by adding either a base or an acid. ### Claim 7 (depends on 6) The method of claim 6, wherein the pH is increased to a pH between 4.2 and 4.7. ### Claim 8 (depends on 6) The method of claim 6, wherein the added base comprises ammonia. ### Claim 9 (depends on 6) The method of claim 6, wherein the added acid is carbon dioxide. ### Claim 10 (depends on 6) The method of claim 6, wherein the pH is monitored and maintained at a value between 3.0 and 6.0 during step C by adding either a base an acid. ### Claim 11 (depends on 1) The method of claim 1, wherein the reaction temperature in step C is between 160 and 190 degrees Celsius. ### Claim 12 (depends on 1) The method of claim 1, wherein the wood has a temperature higher than 150 degrees Celsius for between 10 and 60 minutes during step C. ### Claim 13 (depends on 1) The method of claim 1, wherein the steam has a pressure of at least 4 bar during step C. ### Claim 14 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. ### Claim 15 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. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the measuring and control equipment is programmed to maintain the pH in the treatment space at a predetermined value by adding either base or acid by activating the dispenser. ### Claim 17 (depends on 15) The apparatus of claim 15, further comprising a homogenizing device for spreading the steam homogeneously over the treatment space. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the steam source includes a container for heating water. ### Claim 19 (depends on 15) The apparatus of claim 15, characterized in that wherein the treatment space is bounded by a double wall provided with thermally conducting oil. ### Claim 20 (depends on 15) The apparatus of claim 15, adapted to: A) place wood for treating in a treatment space; B) remove air, in particular, oxygen, from the treatment space; C) feed steam to the treatment space, wherein the temperature of the wood is simultaneously increased, wherein from a temperature of 70 degrees Celsius the temperature is raised 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) polymerize 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) cool 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.