Radio frequency treatment to phytosanitize wood packaging materials used in international shipping
A method for treating wood packaging materials using Radio Frequency heating includes the steps of heating wood packaging materials using RF heating and applying a pressure before the heating or incrementally applying a pressure during the heating until a temperature of the wood packaging materials reaches at least 60° C. and that temperature is maintained for at least 1 minute.
1. A method of treating wood packaging materials (WPMs) using Radio Frequency heating, the method comprising the steps of:
providing a RF operating unit including:
a sealed chamber,
a RF generator connected to the chamber for applying RF heating treatment to the WPMs,
a pressurization system for controlling the pressure inside the chamber;
loading the chamber with a workload of the WPMs;
applying a pressure to the chamber during the treatment, the pressure being at least 5 psi above atmospheric pressure;
treating the WPMs using RF heating until a temperature of the WPMs reaches a predetermined temperature not more than 100° C.; and
maintaining the predetermined temperature for at least 1 minute.
2. The method of treating wood packaging materials in accordance with claim 1 , wherein the temperature of the WPMs is an average temperature of the WPMs.
3. The method of treating wood packaging materials in accordance with claim 1 , wherein the predetermined temperature is not less than 60° C.
4. The method of treating wood packaging materials in accordance with claim 1 , wherein the predetermined temperature is not more than a maximum temperature of 90° C., 80° C. or 70° C.
5. A method of treating wood packaging materials (WPMs) using Radio Frequency heating, the method comprising the steps of:
providing a RF operating unit including:
a sealed chamber,
a RF generator connected to the chamber for applying RF heating treatment to the WPMs,
a pressurization system for controlling the pressure inside the chamber;
loading the chamber with a workload of the WPMs;
applying a pressure to the chamber during the treatment;
treating the WPMs using RF heating until a temperature of the WPMs reaches a predetermined temperature not more than 100° C.; and
maintaining the predetermined temperature for at least 1 minute, but not longer than a period of 5 minutes, 4 minutes, 3 minutes or 2 minutes.
6. The method of treating wood packaging materials in accordance with claim 1 , wherein the step of applying of the pressure to the chamber comprises maintaining the chamber generally at a first pressure during a first period and changing the pressure in the chamber generally to a second pressure after the first period.
7. The method of treating wood packaging materials in accordance with claim 6 , wherein the first pressure is approximately atmospheric pressure and the second pressure is greater than atmospheric pressure.
8. The method of treating wood packaging materials in accordance with claim 7 , wherein the second pressure is at least 10 psi above atmospheric pressure.
9. The method of treating wood packaging materials in accordance with claim 7 , wherein the first period is defined by elapsed time, the elapsed time period being predefined based on the WPMs being treated.
10. The method of treating wood packaging materials in accordance with claim 7 , wherein the first period is defined by a temperature threshold, the first period ending when the temperature of at least some of the WPMs reach a temperature threshold in the range of approximately 30° C. to approximately 60° C.
11. The method of treating wood packaging materials in accordance with claim 7 , wherein the first period is defined by a temperature threshold, the first period ending when the temperature of at least some of the WPMs reach a temperature threshold of approximately 50° C.
12. The method of treating wood packaging materials in accordance with claim 1 , wherein the step of applying pressure to the chamber comprises:
applying 5 psi of pressure before reaching a rise of 10° C. from an initial ambient temperature of the WPMs; and
adding another 5-10 psi to the chamber when 50° C. is first registered by a temperature sensor within the WPMs.
13. The method of treating wood packaging materials in accordance with claim 1 , further comprising monitoring the temperature of the WPMs using RF compatible temperature sensors placed within the WPMs, the temperature of the WPMs comprises an average temperature from the temperature sensors, a maximum temperature from one of the sensors, or a minimum temperature from one of the sensors.
14. The method of treating wood packaging materials in accordance with claim 1 , further comprising depressurizing the chamber after reaching at least 60° C. with a 1-minute hold time.
15. The method of treating wood packaging materials in accordance with claim 14 , wherein the depressurizing of the chamber is at a rate of decreased pressure of 2-4 psi per minute.
16. The method of treating wood packaging materials in accordance with claim 15 , further comprising checking a surface temperature of the WPMs using surface temperature imaging technology after the depressurization step.
17. The method of treating wood packaging materials in accordance with claim 1 , further comprising unloading the WPMs from the chamber for cooling and post-treatment construction of shipping materials.
18. The method of treating wood packaging materials in accordance with claim 1 , wherein the RF operating unit further includes two primary electrodes inside the chamber and the RF generator is connected to the primary electrodes, the primary electrodes being a top electrode and a lower ground electrode.
19. The method of treating wood packaging materials in accordance with claim 18 , wherein the WPMs are disposed between the two primary electrodes and the top electrode applies a load pressing down onto the WPMs to remove air gaps between the two primary electrodes.
20. The method of treating wood packaging materials in accordance with claim 18 , wherein the RF operating unit further includes secondary electrodes.
21. The method of treating wood packaging materials in accordance with claim 18 , wherein the primary electrodes include a top winged electrode.
22. The method of treating wood packaging materials in accordance with claim 1 , wherein the treating the WPMs using RF heating is at a constant rate or at a ramping rate.
23. The method of treating wood packaging materials in accordance with claim 1 , further comprising applying a load to the WPMs to reduce air gaps.