Pulsed Electron Beam Sterilization of Thermoplastic Containers
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Solution Overview
Problem
Existing methods for sterilizing the interior of thermoplastic containers, such as PET bottles, using electron beams face challenges including material alteration and long treatment times, making them unsuitable for industrial application.
Innovation Solution
A pulsed electron beam with high intensity (of the order of kilo-Ampere) and short emission duration (less than 100 nanoseconds) is used to sterilize the interior of containers without compromising the material, achieved through an explosive emission process, and a reflector is introduced to selectively reflect the beam for efficient irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous electron beam is used to sterilize the interior of thermoplastic containers, then sterilization effectiveness is improved, but treatment time increases and material alteration occurs
Solution Approach 1:
The patent applies periodic action by using pulsed electron beam irradiation instead of continuous irradiation. The electron beam is delivered in short pulses (nanosecond to microsecond duration) separated by intervals, allowing rapid sterilization while minimizing total exposure time and reducing material alteration. This periodic delivery method maintains sterilization effectiveness while dramatically reducing treatment time compared to continuous beam methods.
2Reliability
If a continuous electron beam is used to sterilize the interior of thermoplastic containers, then sterilization effectiveness is improved, but material alteration increases
Solution Approach 1:
The periodic pulsed electron beam delivery allows the thermoplastic material to recover between pulses, minimizing cumulative radiation damage while maintaining sterilization effectiveness. The short pulse durations with intervals prevent excessive energy deposition that would cause material degradation, thus resolving the contradiction between sterilization effectiveness and material preservation.
Solution Approach 2:
The patent changes the temporal parameters of electron beam delivery from continuous to pulsed mode, controlling pulse duration, frequency, and intensity. By optimizing these parameters, the system achieves effective sterilization while limiting the total energy absorbed by the material, thereby preventing harmful alterations to the thermoplastic container.
3Object-affected harmful factors
If low energy electron beam is used to reduce material interaction, then material alteration is reduced, but sterilization effectiveness decreases
Solution Approach 1:
The pulsed electron beam system delivers high-intensity radiation in brief intervals, allowing the use of lower average energy levels that reduce material interaction while maintaining peak intensities sufficient for sterilization. The periodic delivery ensures that microorganisms are exposed to lethal radiation doses during the pulses, while the intervals between pulses prevent cumulative heating and material degradation.
4Productivity
If high intensity pulsed electron beam is used to reduce treatment time, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent employs parameter changes by adjusting electron beam generation parameters (pulse duration, frequency, intensity) to achieve industrial production rates. The system uses controllable pulsed electron sources that can be tuned to match manufacturing throughput requirements, balancing productivity gains with acceptable device complexity through optimized operational parameters rather than fundamentally complex hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for rapid and effective sterilization of the interior surfaces of containers, reducing treatment time to be compatible with industrial production rates while minimizing interactions with the thermoplastic material, thus ensuring the containers' integrity and safety for food packaging.
Implementation Method 1
One alternative solution involves using ionizing radiation formed by an electron beam which is used to irradiate the surface to be sterilized
Implementation Method 2
arranging an electron beam emitter outside the container makes it possible to overcome this problem of limited accessibility; the electrons of the beam emitted by the emitter pass radially through the body and neck of the container from the outside in, to irradiate the inside of the container to be sterilized
Implementation Method 3
a reflector is introduced to selectively reflect the beam for efficient irradiation
Implementation Method 4
achieved through an explosive emission process
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to a device (10) and a method for sterilizing thermoplastic containers using a pulsed beam (F) of electrons which is formed of a succession of pulses each having an emission time (d) which is less than 100 ns and an intensity (i) which is greater than 1 kA so as to sterilize, through a wall (18) of the container, at least the inside (20) of said container (12). A reflector (16) mounted with the ability to move axially relative to the container is included.