One of the concerns presented by desktop 3D printing is the amount of potentially harmful particles that are produced by the process. In a paper entitled “An Intelligent Exhaust Gas Processing System for Desktop 3D Printer,” a group of researchers discuss how they developed a system to perform adsorption and catalysis for desktop 3D printers.
The system consists of a digital universal particle concentration sensor, a microcontroller, and a DC motor. The particle concentration sensor detects whether the concentration of particulates in the 3D printer exceeds the lowest critical value harmful to the human body.
“The concentration of the detected particulates is compared with the preset concentration limits by the circuit,” the researchers explain. “If the concentration exceeds the upper limit, the motor is turned on; if less than The lower limit, the motor is closed, if the user needs manual intervention and adjustment in special circumstances, can be manually controlled through an external switch to achieve air processor switch.”
“The main task of the microcontroller microprocessor in this system is to complete the control and processing of the data collected by the particle concentration acquisition module and compare it with the preset standard value,” the researchers continue. “When the value is greater than the standard value, the control motor is turned on. The main program first completes the initialization, and then starts the particle concentration acquisition module and performs the corresponding output operation…System software flow is mainly divided into system initialization, data acquisition, data processing three parts.”
For the exhaust of the 3D printer, the adsorption equilibrium constant is small, so it must be cooled before adsorption. After heating the desorption concentrated exhaust gas to a certain temperature, it catalyzes carbon dioxide and water, and discharges after cooling. The exhaust gas treatment equipment includes an adsorption-desorption device and a catalytic burner.
Adsorption pad 3 is filled with a shaped adsorbent, and gas passes through to the adsorption zone for adsorption purification. A small amount of hot air blows through the desorption zone, the volatile organic compounds (VOCs) are forcibly desorbed, and the adsorbent is regenerated. The desorption of the adsorbent is cooled with a small amount of low-temperature airflow to ensure the effect of adsorption of the adsorption zone.
“The exhaust gas produced by the desktop 3D working process contains solid particles and harmful gases, which will cause some damage to the environment and people,” the researchers conclude. “Although it is suitable for FDM desktop 3D printers, this paper can also be used on other desktop 3D printers such as SLA and SLS, and develop an adsorption and catalytic combustion composite reactor based on 51 single-chip microcomputer based intelligent coupling adsorption desorption and catalytic combustion, which can realize 3D printing. The harmless treatment of exhaust gas fills the blank of 3D printing waste gas treatment, and greatly expands the application of desktop 3D printer.”
Authors of the paper include Ligang Cai, Shunlei Li, Qiang Cheng, Zhifeng Liu, Wei Cui and Huirong Fu.
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