폐타이어의 저온 열분해시 발생되는 오염물의 거동 특성

Behavior Characteristics of Pollutants Caused by Low Temperature Pyrolysis of Waste Tires

목적 : 폐타이어를 환경적으로 안전하게 처리할 수 있는 저온 열분해공정을 개발하는 데 있다.방법 : 폐타이어의 무게를 계량하여 열분해로에 장입한 후, 진공상태에서 저온으로 열분해하였다. 열분해로에서 발생되는 공해물질을 제거하기 위하여 후 처리공정은 가스세정기, 응축기, 폐열보일러, 여과필터로 구성되었다. 본연구를 위해 조사된 오염물질은 황화합물, 질소화합물, 암모니아 등 28개 대기오염물질과 복합악취, 12개의 지정악취물질, 다이옥신 그리고 응축수에 함유된 BOD 등 13개 수질오염물질이다.결과 및 토의 : 열분해로에 장입된 폐타이어는 100 Kg이며, 3회에 걸쳐 7시간 동안 진행되었다. 열분해로에서 폐타이어의 안정적 분해는 320℃ 전후에서 일어나며, 이는 열분해로의 배기가스를 통해서 확인할 수 있었다. 열분해로에서 처리 시 발생되는 대기오염물질은 CO, HCl, NOx 등 10개 물질이 검출되었으며, 불소화합물, 페놀, 비소 등 18개 물질은 검출되지 않았다. 열분해로에서 발생되는 대기오염물질은 후처리공정에서 법 규제치 이하로안정적으로 처리되었다. 폐타이어를 열분해로에서 처리할 때 발생되는 복합악취는 42,800 희석배수였다. 최종 배출구에서는 복합악취의 강도는 300 희석배수이며, 초기 발생농도 대비 99%가 저감되었다. 암모니아, 황화수소, n-발레르산 등 11개 지정악취 물질이 검출되었다. 이중 암모니아와 아세트알데히드는 가스세정기에서 각각99.3%, 94.5%가 제거되었으며, 남은 물질은 여과필터에서 안정적으로 제거되었다. 최종배출구의 다이옥신농도는0.002 ng-TEQ/Sm³로 배출허용기준인 5 ng-TEQ/Sm³보다 훨씬 낮은 농도로 나타났다.결론 : 28개의 대기오염물질중 10개가, 22개 지정악취물질 중 11개가 검출되었다. 열분해로에서 발생되는 NH³ 농도는 후처리공정인 가스 세정기에서 97.2%가 저감되었으며, HCl농도는 여과필터를 통과한 후에 99.7%까지 저감되었다. 최종 배출구에서는 복합악취의 강도는 300 희석배수로 초기 발생농도 대비 99%가 저감되었다. 지정악취물질인 암모니아와 아세트알데히드는 가스세정기에서 각각 99.3%, 94.5%가 제거되었다. 최종배출구의 다이옥신농도는 0.002 ng-TEQ/Sm³로 조사되었으며, 법규제치 이하였다.

Objectives : The purpose of this study is to develop environmentally stable treatment process by low temperature pyrolysis of waste tires.Methods : The weight of the waste tire was measured and charged to the pyrolysis furnace and pyrolyzed at a low temperature in a vacuum state. In order to remove the pollutants generated in the pyrolysis furnace, the post treatment process consisted of a gas scrubber, a condenser, a waste heat boiler, and a filter. The pollutants investigated for this study are 28 air pollutants such as sulfur compounds, nitrogen compounds, and ammonia, complex odor, 12 designated odorous substances, dioxin, and 13 water pollutants including BOD, CODMn contained in condensed water.Results and Discussion : The waste tire charged to the pyrolysis furnace was 100 kg, which was run three times for 7 hours. Stable decomposition of the waste tire in pyrolysis furnace occurred around 320℃, that could be confirmed by the exhaust gas of pyrolysis furnace. Out of 28 air pollutants, 10 substances such as CO, HCl and NOx were detected, and 18 substances such as fluorine compounds, phenol and arsenic were not detected. The air pollutants generated from the pyrolysis furnace were stably treated in the post-treatment process to below the legal limits. The complex odor generated when the waste tires were treated in the pyrolysis furnace was 42,800 dilution. At the final outlet, the intensity of the complex odor was 300 dilution, which was reduced by 99% compared to the initial concentration. 11 designated odor substances such as ammonia, hydrogen sulfide, and n-valeric acid were detected. Ammonia and acetaldehyde were 99.3 and 94.5% removed from the scrubber, respectively, and the remaining material was stably removed from the filter. The dioxin concentration at the final outlet was 0.002 ng-TEQ/Sm³, much lower than the emission limit of 5 ng-TEQ/Sm³.Conclusions : Ten out of 28 air pollutants and eleven out of 22 designated odorous substances were detected. The NH³ concentration in the pyrolysis furnace was reduced by 97.2% in the scrubber, and the HCl concentration was reduced to 99.7% after passing through the filter. Ammonia and acetaldehyde, designated odor substances, were removed by 99.3% and 94.5% respectively in the gas scrubber. At the final outlet, the intensity of the complex odor was 300 dilutions, which is a 99% decrease compared to the initial concentration. The dioxin concentration at the final outlet was 0.002 ng-TEQ/Sm³, which was very allowable level to the legal.