Abstract: A method for heating a plurality of articles according to a prescribed heating profile is provided. The method includes heating a first test article in a small-scale microwave heating system and, based on the value of one or more parameters determined during this small-scale heating, determining a prescribed heating profile for the test article. Suitable parameters can include for example, net power discharged, sequential microwave distribution, average temperature and flow rate of the fluid in the heating chamber, and residence time. The heating profile can then be used to control a commercial-scale microwave heating system used to heat a plurality of similar articles.

Abstract: A locking gate device suitable for selectively blocking the flow of fluid and/or articles through a pair of openings defined by two spaced-apart members is provided. The spaced-apart members may be opposing walls or flanges of two adjacent processing chambers or vessels in a pressurized heating system. The locking gate device includes a gate assembly that is movable within a gate-receiving space defined between opposed sealing surfaces of the spaced-apart members. The gate assembly comprises a pair of sealing plates and a drive member shiftable relative to the sealing plates. As the drive member is shifted between a retracted position and an extended position, a pair of bearings disposed between the sealing plates and the drive member forces the sealing plates outwardly to contact the sealing surfaces of the spaced-apart members. This substantially blocks the flow-through openings defined by one or both sealing surfaces and restricts flow therethrough.

Abstract: A microwave heating system configured to heat a plurality of articles is provided. The microwave heating system can include one or more microwave launchers that define at least one launch opening having a depth of not more than about 0.625 ?, wherein ? is the predominant wavelength of the microwave energy passing through the launcher. Additionally, in some embodiments, the launch opening may have a width or depth that is less than the corresponding inlet dimension, such that the microwave launcher has a generally tapered profile. When the microwave launcher includes a single inlet and two or more launch openings, the center points of adjacent outlets may be laterally spaced from one another relative to the direction in which the articles are passed through the heating chamber.

Abstract: A method and system for heating a plurality of articles is provided. The method includes discharging microwave energy into a microwave chamber and passing a plurality of articles through the heating zone. At least a portion of the microwave energy discharged into the heating zone may first be phase shifted using one or more phase shifting devices. One embodiment of a rotatable phase shifting device is also provided and includes an elongated fixed member disposed proximate a rotatable housing. The phase shifting device employed by the microwave heating system is configured such that the ratio of the article residence time in the heating zone to the phase shifting rate is at least about 4:1. Rotatable phase shifting devices, or variable phase short circuits, as described herein can also be used in other applications, such as, for example, as impedance or frequency tuning devices.

Abstract: An optimized microwave barrier assembly suitable for use with a vacuum microwave heater. The barrier assembly is configured to allow microwaves to pass therethrough in a TMab mode, wherein a is 0 and b is an integer in the range of 1 to 5. The barrier assembly is also configured to maintain a pressure differential across a window of the barrier assembly. Such a configuration can reduce or eliminate arcing in the barrier assembly, even at low pressures.

Abstract: A microwave heater equipped with a microwave choke and suitable for heating one or more articles under vacuum. The microwave choke inhibits leakage of microwave energy between a door of the heater and a main vessel body of the heater without causing arcing at the choke, even at low pressures. In certain situations, the microwave choke can be configured with side-by-side choke cavities. In certain situations, the microwave choke can be removably coupled to the door and/or vessel body for easier fabrication, installation, and/or replacement.

Abstract: A microwave heater capable of heating a bundle of wood and equipped with an optimized system for introducing microwave energy into the heater. The system uses a high-efficiency elongated waveguide launcher having a plurality of launch openings defined in relatively thin walls. The waveguide launcher can exhibit a launch efficiency of at least 50 percent, thereby providing substantially energy savings over conventional waveguide launchers.

Abstract: An optimized system and process for heating wood using a microwave heater. The optimized system/process directs microwave energy towards different regions of the wood at different times during heating. In certain situations, microwave energy is introduced into the heater using microwave launchers and the system includes one or more microwave switches that control distribution of microwave energy to the microwave launchers so that two adjacent and/or opposing microwave launchers do not simultaneously introduce microwave energy into the heater. The optimized heating process also includes heating wood using a plurality of sequential heating cycles carried out at different conditions. For example, at least one of the heating cycles can be carried out at a lower input rate of microwave energy and/or at a lower pressure than one of the previous heating cycles.

Abstract: A microwave heater equipped with a microwave choke and suitable for heating wood under vacuum. The microwave choke inhibits leakage of microwave energy between a door of the heater and a main vessel body of the heater without causing arcing at the choke, even at low pressures. In certain situations, the microwave choke can be configured with side-by-side choke cavities. In certain situations, the microwave choke can be removably coupled to the door and/or vessel body for easier fabrication, installation, and/or replacement.

Abstract: A commercial scale microwave system that includes a heater having enhanced heat distribution and minimized void space. The enhanced heat distribution can be provided by a unique launcher and/or reflector configuration disposed in the interior of the microwave heater. The microwave system can be operated to prevent the wood from both overheating (which results in scorching) and under-heating (which results in inadequate drying and/or inadequate thermal-modification). The microwave heating system can provide enhanced microwave energy distribution for large quantities of wood, even large quantities of wood heated under vacuum and/or in the presence of one or more chemical reagents.

Abstract: A microwave heater capable of heating a bundle of wood and equipped with an optimized system for launching and/or dispersing microwave energy. The microwave launching system can include one or more split microwave launchers at least partly disposed in the interior of the heater. The microwave dispersing system can include one or more moving reflectors for rastering microwave energy emitted from the split launchers.

Abstract: A microwave heater capable of heating a bundle of wood and equipped with an optimized system for introducing microwave energy into the heater is provided. Also provided is an enhanced system for launching and dispersing within the heater. The system uses one or more TMab microwave launchers to emit microwave energy in the interior of the microwave heater in a TMab mode, where a is 0 and b is an integer between 1 and 5. The TMab launchers can be configured to emit microwave energy through an open outlet that faces generally parallel to the nearest wall of the heater. In certain situations, it can be advantageous to use at least two TMab microwave launchers having open outlets that face towards one another. In certain situations, it can be advantageous to use at least two TMab microwave launchers located on generally opposite sides of the microwave heater. In certain situations, the system can also include one or more moving reflectors for dispersing microwave energy emitted from the TMab microwave launchers.

Abstract: An optimized microwave barrier assembly for use in conjunction with a microwave wood heater. The barrier is configured to allow microwaves to pass therethrough in a TMab mode, where a is 0 and b is an integer between 1 and 5. The barrier assembly is also configured to maintain a pressure differential across a window of the barrier assembly. Such a configuration can reduce or eliminate arcing in the barrier assembly, even at low pressures.