Treatment Of Cyanide Containing Waste Gas From The Carbonization Process For The Manufacture Of Carbon Fiber

The process of production of polyacrylonitrile-based carbon fiber will produce a huge amount of hydrogen cyanide pernicious gas, especially in the carbonation section, and the HCN gas will greatly endanger people’s health and the environment. There is no method to deal with the gaseffectively. Pilot experiments were carried out to treat the real cyanide-containing waste gas produced fromcarbon fiber, the research main content is as follows:(1) Analysis the exhaust gas composition of polyacrylonitrile-based carbon fiber production process by TGA (Thermal Gravimetric Analysis) technology, for carbon fiber strand/oxidation decomposition of carbon filament silk/products/dissociation temperature characteristic, when the temperature in the 300-700 degree the carbon fiber was declinedobviously in quality. Through the Py/GC-MS (Pyrolysis/Gas Chromatographic-Mass Spectrometry) pyrolysis chromatography-Mass Spectrometry technology to researchthe exhaust gas composition under different temperature. Except the main product HCN, there are many organics such as pyrrole, benzamidine, methylene glutaric nitrile,2-methy pyrazine,2-methylene glutaric. Using FTIR (Fourier Transmittance Infra-Red spectroscopy) to get the exhaust gas components of the fingerprint characteristic spectra.(2)Using double temperature control system to heat the preoxidation wire to 700℃ to simulated carbonization process, then collect the waste gasand use the bubbling tower form to explore the removal of exhaust gas under different concentration of solution. When the NaOH concentration reaches 1 mol/L, HCN removal rate can reach more than 99%.(3) Using chemical absorption to deal with the exhaust gas, because the HCN gas is hypertoxic and cannot be extensively used in laboratory, so we use the CO2 mixture as the simulated flue gasto explore the absorption effect of exhaust gas by controlling the airflow, fluid volume, pH value, the concentration of NaOH, and other conditions for chemical waste gas absorption. When using 1 mol/L NaOH solution to absorb 20% volume fraction of CO2 emissions, the absorption effect can reach more than 99%.(4)According to the related parameters in the exhaust gas provided by the factory, calculate and design the packed tower as the diameter of 200 mm. Then use NaOH solution as the absorption to absorb the cyanide waste gas produced from carbide section. The field pilot-scale test result shows that the dust emissioncan reach the national standard (1.9 mg/m~3).The cyanide containing waste gas from the carbonization process of carbon fiber can be treated by chemical absorptiontechnology, which can reach the exhaust emission national standard at 1.9 mg/m3. It’s meaningful that the chemical absorption method used in the industrial application in the field of cyanide waste gas treatment, which has played a good demonstration effect.