Thermal desorber assembly for high-volume sampling filters
Inventors
Dicicco, Joseph A. • Flanigan, IV, Paul M. • Perry, David • Brady, John • Smith, Barry
Assignees
Signature Science LLC • US Department of Homeland Security
Publication Number
US-11958010-B2
Publication Date
2024-04-16
Expiration Date
2041-08-06
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Abstract
Disclosed is a thermal desorber assembly for desorbing substances collected on a high-volume sampling (HVS) filter. The assembly includes, among other elements, a filter holder for securing a HVS filter within the assembly, a desorber body, and an insulating enclosure. The design of the thermal desorber assembly is such that it can accommodate a variety of different types of HVS filter media. Also described herein is a system comprising the thermal desorber assembly and method of using the assembly.
Core Innovation
The invention disclosed is a thermal desorber assembly designed for desorbing substances collected on a high-volume sampling (HVS) filter. The assembly includes key components such as a filter holder that can secure a variety of HVS filter media, a desorber body with a cavity to receive the filter holder, an inlet and outlet configured to connect to a mass flow controller and vapor collection or analytical detection systems respectively, and an insulating enclosure that houses the desorber body. The filter holder has two portions hingedly connected and configured to rotate from an open to a closed position, with each portion defining filter holes that align and cooperate to secure the filter when closed.
The design allows the desorber body to align its inlet and outlet with the respective filter holes of the filter holder to facilitate controlled purge gas flow through the filter for desorption of collected substances. The desorber body also includes holes to receive heating elements and temperature sensors, allowing precise temperature control of the desorption process. An insulating enclosure surrounds the desorber body and is equipped with openings for electrical leads and port openings that align with the inlet and outlet for connections to external gas and analytical systems. Additionally, a lid and locking mechanism create an airtight seal over the desorber body and filter holder assembly.
The problem solved by this invention addresses challenges in detecting contraband materials using vapor sampling. Contraband detection is difficult due to the diversity of signature molecules, low vapor pressures producing only trace vapors, operational constraints requiring high throughput, and interference from cargo or previous container fumigation. Current vapor screening systems use HVS systems to sample large air volumes and pre-concentrator filters to capture vapors. However, there was a need for a thermal desorber capable of adequately desorbing substances from HVS filters, which this invention fulfills by providing an assembly configured to thermally desorb collected substances efficiently, with features to accommodate various filter types and integrate with analytical systems.
Claims Coverage
The patent contains two independent claims outlining the thermal desorber assembly and system with multiple inventive features.
Filter holder with hinged portions and recesses to secure a filter
A filter holder having first and second portions hingedly secured and configured to rotate from open to closed position, each defining respective filter holes that align when closed, and at least one portion defining a recess to receive and secure a filter within.
Desorber body with cavity and aligned inlet and outlet
A desorber body defining a cavity to receive the closed filter holder, with an inlet configured to connect to a mass flow controller and an outlet configured to connect to a vapor collection or analytical detection system, wherein the inlet and outlet at least partially align with the recessed filter holes when the filter holder is inserted.
Insulating enclosure configured to receive the desorber body
An insulating enclosure designed to receive the desorber body, having openings for heater and sensor wire leads and port openings aligned with the desorber body's inlet and outlet.
Holes in desorber body for heating elements and temperature sensors
The desorber body further defines at least one hole configured to receive a heating element and at least one hole configured to receive a temperature sensor, enabling controlled heating.
Magnetically securing filter holder portions
First and second portions of the filter holder each comprise a respective magnet that magnetically secure the portions together when in the closed position.
Insulating spacers supporting desorber body inside enclosure
The insulating enclosure includes insulating spacers to support the desorber body and prevent metal-to-metal contact with the enclosure's interior surface.
Lid and locking assembly for sealing desorber body cavity
A lid configured to seal the desorber body cavity when the filter holder is inserted, and a locking assembly comprising a locking base and latch to retain the lid in a closed position, with the locking base spaced from and not in direct contact with the insulating enclosure.
Thermal desorber assembly system comprising mass flow controller and collection/detection apparatus
A system including a mass flow controller, a vapor collection or analytical detection apparatus, the filter holder, desorber body with inlet and outlet connected respectively to the mass flow controller and collection/detection apparatus, and the insulating enclosure.
Temperature process controller for heating elements and sensors
A temperature process controller in communication with heating elements and temperature sensors in the desorber body, configured to control temperature based on feedback.
Desorber body mass less than 600 grams
The desorber body is designed to have a mass under 600 grams to improve heating efficiency.
The independent claims collectively cover a thermal desorber assembly and system featuring a hinged filter holder with recesses to secure filters, a desorber body cavity with aligned inlet and outlet for purge gas flow, an insulating enclosure, heating and sensing capability integrated into the desorber body, magnetic or other securing means for filter holder closure, and sealing means with a lid and locking assembly. The system also includes control elements and specified mass limits for efficient thermal operation.
Stated Advantages
The thermal desorber assembly can accommodate a variety of different types of high-volume sampling filters.
The desorber body has minimal mass to reduce heating and cooling time, enabling faster temperature ramping and analysis throughput.
The filter holder secures filters reliably through hinged portions and magnetic or other securing methods, facilitating easy insertion and replacement.
The insulating enclosure and insulating spacers prevent heat loss by avoiding metal-to-metal contact and enable stable, efficient thermal operation.
The assembly provides an airtight seal via the lid and gasket to maintain controlled desorption environment.
Integration with mass flow controllers and analytical detection systems enables controlled purge gas desorption and subsequent vapor analysis.
External fans aid in rapid cooling of the thermal desorber assembly after analysis.
Documented Applications
Detection and identification of contraband materials via vapor sampling on large transport systems, using high volume sampling filters.
Vapor screening analysis where trace vapors of target substances are adsorbed on HVS filters and then thermally desorbed for chemical analysis.
Analytical quantification via systems such as ambient thermal desorption sorbent tubes or heated transfer lines paired with gas chromatograph-mass spectrometer instrumentation.
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