Process Gas Filter Recirculation for Passivating Metal Residue
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Solution Overview
Problem
Existing filter devices for additive manufacturing of three-dimensional objects face challenges in effectively removing contaminants from process gases, particularly when using metal-containing materials, as they can lead to uncontrolled reactions and fires due to spontaneous oxidation, and require additional inerting agents that increase maintenance frequency.
Innovation Solution
A filter device with a recirculation system that reintroduces filter residue into the filter chamber, utilizing a fluid flow to mix and chemically react with oxidizing agents, breaking up agglomerates and reducing flammability through inerting agents like lime powder, without the need for additional filters or waste containers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filter residue is removed from the filter chamber, then fire risk is reduced, but filter efficiency decreases due to loss of inerting agents
Solution Approach 1:
The invention extracts only the necessary portion of filter residue containing oxidizing agents from the filter chamber through the conveying device, while retaining the inerting agents (lime powder, magnesia) in the filter chamber. This selective removal reduces fire risk by eliminating reactive metal particles while preserving filter efficiency through retention of inerting agents that prevent spontaneous combustion of remaining residue.
Solution Approach 2:
The conveying device acts as an intermediary system that selectively transports filter residue from the filter chamber to a collection container. This intermediary mechanism enables controlled removal of hazardous materials while maintaining the beneficial inerting agents in place, thus mediating between fire risk reduction and filter efficiency preservation.
2Object-affected harmful factors
If additional inerting agents are added to filter residue, then flammability is reduced, but maintenance frequency increases due to faster fill level
Solution Approach 1:
The invention removes oxidizing agents (metal particles, condensate) from the filter chamber before inerting agents can be consumed. By extracting the reactive components that would otherwise react with and deplete inerting agents like lime powder and magnesia, the system maintains flammability reduction without accelerating inerting agent consumption, thus avoiding increased maintenance frequency.
Solution Approach 2:
The system performs preliminary removal of oxidizing agents from the filter chamber before they can react with and deplete the inerting agents. This preliminary action preserves the inerting agents for continued use, maintaining flammability control while extending the time between maintenance operations.
3Loss of time
If filter chamber is opened quickly for filter element change, then operation time is reduced, but uncontrolled oxidation occurs leading to filter fires
Solution Approach 1:
The invention extracts and removes oxidizing agents (metal particles and condensate) from the filter chamber through the conveying device before filter element replacement. This removal eliminates the fuel source for spontaneous combustion, allowing the filter chamber to be opened quickly without risk of uncontrolled oxidation or filter fires during the element change operation.
Solution Approach 2:
The system performs preliminary removal of reactive metal particles and condensate from the filter chamber before the filter element is changed. This preliminary action eliminates the hazard of uncontrolled oxidation that would otherwise occur upon rapid opening, enabling safe and quick maintenance operations.
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
The system effectively reduces the risk of fires and maintains filter efficiency by chemically passivating residues, breaking up agglomerates, and minimizing the need for additional filters, thus enhancing safety and reducing maintenance.
Implementation Method 1
a conveying device for conveying the filter residue in the fluid flow which is designed and/or arranged such that the filter residue is at least partially removed from the filter chamber and conveyed back into the filter chamber
Implementation Method 2
the particles tend to react with oxidizing materials at high temperatures, with the reaction rate increasing at elevated temperatures. Metal condensate can spontaneously ignite at room temperature upon contact with atmospheric oxygen
Implementation Method 3
at least one filter element arranged in the filter chamber which is designed to filter the process gas, leaving a filter residue
Data Source
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AI summary
The invention relates to a filter device (1) for filtering a process gas. In particular, the process gas can be a process gas of a device (101) for the additive manufacture of three-dimensional objects (102), and the filter device (1) comprises: a filter chamber (10), at least one filter element (20) which is arranged in the filter chamber and which is designed to filter the process gas, wherein a filter residue remains, a fluid flow generating device (40, 40') which is designed to generate a fluid flow, and a conveyor device (50) for conveying the filter residue in the fluid flow, said conveyor device being designed and/or arranged such that the filter residue is at least partly removed from the filter chamber (10) and is conveyed back into the filter chamber (10).