CAJ | 학술논문

为了实现竹屑热解三态产物品质最优化，该文研究了竹屑250～950℃热解多联产的产物分布规律和演变特性，通过分析焦孔隙结构与分形维数演变规律对竹屑热解过程进行了探讨。结果表明，竹屑在较低温度下热解释放出大量的 CO 和 CO2，同时生成乙酸、糠醛和酮类物质；450～650℃之间，木质素大量分解使得 H2和 CH4含量上升，液体产物中苯酚类物质含量迅速增加，并开始出现萘、茚等物质；750℃后挥发分二次反应加剧，CO相对含量升高。650℃前，生物炭比表面积与总孔容积迅速增大，平均孔径逐渐减少，表面分形维数和体积分形维数均增大；650℃后，各参数均表现出相反的变化规律。650℃竹屑热解生物焦具有较好孔隙结构，比表面积可达307.65 m2/g。根据竹屑热解多联产产物分布规律与演变特性，可同时得到具有较高品质的气、液和固三态产物，有利于实现竹屑综合高效利用，为竹屑热解多联产设备的开发与运行提供参考依据。
위료실현죽설열해삼태산물품질최우화，해문연구료죽설250～950℃열해다련산적산물분포규률화연변특성，통과분석초공극결구여분형유수연변규률대죽설열해과정진행료탐토。결과표명，죽설재교저온도하열해석방출대량적 CO 화 CO2，동시생성을산、강철화동류물질；450～650℃지간，목질소대량분해사득 H2화 CH4함량상승，액체산물중분분류물질함량신속증가，병개시출현내、인등물질；750℃후휘발분이차반응가극，CO상대함량승고。650℃전，생물탄비표면적여총공용적신속증대，평균공경축점감소，표면분형유수화체적분형유수균증대；650℃후，각삼수균표현출상반적변화규률。650℃죽설열해생물초구유교호공극결구，비표면적가체307.65 m2/g。근거죽설열해다련산산물분포규률여연변특성，가동시득도구유교고품질적기、액화고삼태산물，유리우실현죽설종합고효이용，위죽설열해다련산설비적개발여운행제공삼고의거。
Bamboo is one of the most important forestry resources, and a large amount of waste is produced during its utilization, such as bamboo chips and tailing. To improve the recycling of bamboo waste, pyrolysis technology for polygeneration was employed. The experiment was carried out in a fixed bed reactor at 250-950℃, and the effect of temperature on products yields, compositions and characteristics was investigated. Micro-GC (3000, Agilent, USA) and GC-MS (7890A/5975C, Agilent, USA) were used to analyze the compositions of bio-gas and bio-oil, respectively. The evolution of bio-char structure was studied with automatic adsorption equipment (ASAP 2020, Micromeritics, USA) via nitrogen adsorption at 77 K. The specific surface area was calculated from the adsorption isotherms using the Brunauer-Emmett-Teller (BET) equation. The pore size distribution was estimated by the Barrett-Joiner-Halenda (BJH) method from the desorption isotherms. In addition, the fractal theory was applied to characterize the fractal properties of pore structure of bio-char. With the temperature increasing, bio-char yield was decreased and bio-gas yield was increased significantly, while bio-oil yield was not changed much. Change of products yields was mainly due to the three components (hemicellulose, cellulose, and lignin) decomposing at different temperatures, and volatiles secondary cracking at high temperature. Bio-gas was mainly composed of H2, CH4, CO, and CO2. Cellulose and hemicellulose decomposed at lower temperature, which resulted that CO and CO2 were released. After the temperature increased over 450℃, lignin began to decompose, and the content of H2 rose sharply, while the content of CH4 rose slowly. After 750℃, volatiles secondary cracking intensified to release more H2. Liquid oil mainly consists of acetic acid, furfural, furan, ketone, aldehyde, and phenol. At 250℃, hemicellulose decomposed predominantly, which generated acetic acid, 2-furanmethanol, hydroxyacetone, and small molecular organic compounds. When the pyrolysis temperature was increased from 250 to 550℃, cellulose decomposed significantly, which resulted that furfural and pentene compounds appeared. With the lignin decomposed, phenol class materials increased quickly, while indene and naphthalene appeared after 650℃. The N2 absorption-desorption isotherms showed that bio-char pore structure was slits pore at lower temperature in comparison with conical pore at higher temperature. With the temperature increasing, the BET specific surface area and pore volume of bio-char increased significantly first, and then decreased gradually. However, the trend of the mean pore size was reversed. This phenomenon could be explained by that the number of micropores significantly increased with the removal of volatiles in bio-char, and some of them might be blocked as a result of ash melting at high temperature. At 650℃, the BET specific surface area and pore volume reached the maxima (307.65 m2/g and 16.416 mL/g, respectively), while the mean pore size was the minimum (2.11 nm). Besides, micro-pores accounted for about 83%. The pore structure of bio-char had doubled fractal characteristics with the pore surface and pore volume. With the increase of pyrolysis temperature, both the surface fractal dimension and volume fractal dimension firstly increased and decreased later. Surface fractal dimension and volume fractal dimension reached the highest value (2.93 and 2.97, respectively) at 650℃. This phenomenon reflected that the pore structure of bio-char developed gradually and then tended to be uniformity.