Dual vessel chemical modification and heating of wood with optional vapor containment

Patent metadata

Field	Value
Publication number	US-2016354948-A1
Application number	US-201615242090-A
Country	US
Kind code	A1
Filing date	Aug 19, 2016
Priority date	Dec 23, 2010
Publication date	Dec 8, 2016
Grant date	—

Abstract

A commercial scale system and process for chemically modifying wood and then heating the chemically-modified wood. The system/process separates the chemical modification step from the heating step by utilizing two different vessels for the modification and heating steps. The system and process can, in certain situations, include a containment room for preventing escape of vapors from a chemical wood modification reactor, a wood heater, and/or a chemically-modified bundle of wood as the bundle is transported from the wood modification reactor to the wood heater.

First claim

We claim:

1 . A commercial-scale process for producing chemically-modified wood, said process comprising:
(a) loading a quantity of wood into a chemical modification reactor, wherein said quantity of wood weighs at least 500 pounds when loaded into said reactor and wherein said chemical modification reactor defines an internal reactor volume of at least 100 cubic feet; (b) chemically modifying at least a portion of said quantity of wood to thereby provide a chemical-wet quantity of wood, wherein said chemical-wet quantity of wood comprises at least one heat-removable chemical component resulting from said chemically modifying; (c) transporting at least a portion of said chemical-wet quantity of wood out of said chemical modification reactor and into a microwave heater; (d) generating microwave energy with at least one microwave generator; (e) passing at least a portion of said microwave energy from said at least one microwave generator, through a microwave distribution system, and into said microwave heater, wherein said microwave distribution system comprises—
at least one waveguide for transporting said microwave energy from said microwave generator to said microwave heater,
at least one microwave launcher for discharging said microwave energy into the interior of said microwave heater through at least one uncovered launch opening, and
at least one barrier assembly entirely disposed outside of said microwave heater between said microwave generator and said microwave launcher,
wherein said barrier assembly fluidly isolates said microwave heater from an external environment outside said microwave heater while still permitting passage of said microwave energy therethrough, wherein said barrier assembly is configured to minimize arcing therein when said microwave energy passes therethrough at a rate of at least 30 kW and when said pressure within said microwave heater is not more than 350 torr, wherein said at least one waveguide includes at least a first waveguide segment and a second waveguide segment, wherein said first waveguide segment is positioned between said microwave generator and said barrier assembly and is configured to propagate microwave energy from said microwave generator to said barrier assembly, and wherein said second waveguide segment is positioned between said barrier assembly and said microwave launcher and is configured to propagate microwave energy from said barrier assembly to said microwave launcher, wherein said first waveguide segment is entirely disposed outside of said microwave heater and wherein said second waveguide is at least partially disposed outside of said microwave heater; and
(f) heating at least a portion of said chemical-wet quantity of wood in said microwave heater under a pressure of not more than 350 torr to thereby vaporize at least a portion of said at least one heat-removable chemical component in said microwave heater to thereby provide a dried quantity of chemically-modified wood.

2 . The process of claim 1 , wherein said chemically modifying of step (a) comprises acetylating said at least a portion of said quantity of wood.

3 . The process of claim 1 , wherein said at least one heat-removable chemical component comprises acetic acid.

4 . The process of claim 1 , wherein said chemically modifying of step (a) comprises a heat-initiated chemical reaction, wherein said heat-initiated chemical reaction is not initiated by microwave heating.

5 . The process of claim 4 , wherein said heat-initiated chemical reaction is initiated by injecting hot vapors into said chemical modification reactor to thereby heat at least a portion of said quantity of wood, wherein at least a portion of said hot vapors injected into said chemical modification reactor condense on at least a portion of said quantity of wood.

6 . The process of claim 1 , wherein during said transporting of step (b) vapors from said chemical modification reactor, from said microwave heater, and/or from said chemical-wet quantity of wood are reduced from escaping into an external environment by a containment room coupled to said chemical modification reactor and said microwave heater, further comprising, during said transporting of step (b), drawing gases and vapors out of said containment room using a ventilation system.

7 . The process of claim 1 , wherein said chemical modification reactor and said microwave heater are spaced from one another by at least 2 feet and not more than 50 feet, wherein said chemical modification reactor and said microwave heater each have an internal volume of at least 500 cubic feet.

8 . The process of claim 1 , wherein said heating of step (e) includes introducing microwave energy into said microwave heater at a rate of at least 50 kW.

9 . The process of claim 1 , wherein said quantity of wood is in the form of a bundle having a total volume of at least 250 cubic feet, wherein said quantity of wood weighs at least 1,000 pounds when said quantity of wood is loaded into said reactor, wherein said chemical-wet quantity of wood comprises at least 8 weight percent of said at least one heat-removable chemical component prior to step (d), wherein said dried quantity of chemically-modified wood comprises not more than 3 weight percent of said at least one heat-removable chemical component after step (d), wherein said process dries said chemical-wet quantity of wood to produce said dried quantity of chemically-modified wood in a time period of not more than 8 hours.

10 . The process of claim 1 , wherein said process is has an annual production capacity of at least about 500,000 board feet.

11 . A commercial-scale process for producing chemically-modified wood, said process comprising:
(a) chemically modifying at least a portion of a bundle of wood in a chemical modification reactor to thereby provide a chemical-wet bundle of wood, wherein said chemical-wet bundle of wood comprises at least one heat-removable chemical component resulting from said chemically modifying; (b) transporting at least a portion of said chemical-wet bundle of wood from said chemical modification reactor, through a containment room, and into a microwave heater, wherein each of said chemical modification reactor and said microwave heater has an internal volume of at least 100 cubic feet; (c) drawing gases and vapor out of said containment room while said chemical-wet bundle of wood is contained therein; (d) generating microwave energy using at least one microwave generator; (e) directing said microwave energy from said at least one microwave generator, through a microwave distribution system, and into said microwave heater, wherein said microwave energy is provided to said microwave heater at a rate of at least 30 kW, wherein said microwave distribution system comprises at least one barrier assembly for fluidly isolating said heater from an external environment outside said heater while still permitting passage of said microwave energy therethrough, wherein said barrier assembly is positioned between said microwave generator and said microwave heater and outside of said microwave heater; and (f) heating at least a portion of said chemical-wet bundle of wood with at least a portion of said microwave energy in said microwave heater to thereby vaporize at least a portion of said heat-removable chemical component and thereby provide a dried bundle of chemically-modified wood, wherein said heating is carried out at a pressure of not more than 350 torr.

12 . The process of claim 11 , wherein said containment room is maintained at a pressure below atmospheric pressure during said transporting.

13 . The process of claim 11 , wherein drawin

Assignees

• Eastman Chem Co

Inventors

• Felty Jr Jarvey Eugene
• Attride David Carl
• Overturf Brad William
• Hiester Andrew C
• Littrell Tyler
• Moore Jared
• Nelson James S
• Shelton Mark Robert
• Kimrey Jr Harold Dail
• Mykytka John Peter
• Guinn Timothy Lee

Classifications

• H05B2206/046

  Microwave drying of wood, ink, food, ceramic, sintering of ceramic, clothes, hair · CPC title

• B27K5/0055 Primary

  Radio-waves, e.g. microwaves · CPC title

• H05B6/763

  Microwave radiation seals for doors · CPC title

• B27K3/346

  Grafting onto wood fibres (B27K3/156 takes precedence; macromolecular compounds derived from lignocellulosic materials C08H) · CPC title

• H05B6/707 Primary

  using waveguides · CPC title