生物质连续热解炭气油联产中试系统开发

Development of carbon, gas and oil poly-generation pilot system based on biomass continuous pyrolysis

针对目前多数生物质炭化设备生产连续性差、能耗高、生产过程中存在焦油水洗二次污染等问题,结合生物质炭化技术最新进展和农林剩余物原料特征,提出了生物质连续热解炭气油联产工艺方案,引入连续分段热解、多级组合除尘脱焦和燃油/燃气回用加热工艺方法。在此基础上,重点突破了多线螺旋抄板物料均匀有序输送、多腔旋流梯级高效换热、保温沉降密封出炭、系统压力与气体组分耦合预警等技术,开发了生物质连续热解中试生产系统。运行检测结果表明:系统运行稳定可靠,温度控制精度为±16℃,反应室压力控制精度为±25 Pa,以花生壳为原料,原料处理量为28.2 kg/h,生物炭得率为31.3%,热解气产率29.6%,液体产物产率19.8%,热解气低位热值为16.3 MJ/m^3,各项技术指标均达到了系统设计目标与要求。该中试系统的开发为设备放大及示范应用奠定了重要基础。

： Biomass carbonization technology refers to the process of biochar, bio-oil, and non-condensable gas products＇ formation from raw biomass material. This process occurs in the anaerobic or hypoxic environment, which is a low-temperature slow pyrolysis technology. Biomass pyrolysis and muki-generation technology uses modem biomass carbonization technology as the core. Bio-carbon, high-quality gas, wood tar and wood vinegar and other products are produced through the separation and purification of pyrolysis gas. Biochar can be widely used in carbon sequestration, water purification, heavy metal adsorption and soil improvement. Thus, biochar production and application have attracted wide attention of domestic and foreign researchers. Pyrolysis gas has an important development and utilization value as a high-quality clean gas. With the advantages of high utilization rate of resources, diversified product forms and less secondary pollution, this technology can further improve the development and utilization of comprehensive benefits. It also meets the strategic thinking on comprehensive utilization of biomass energy resources, and has a good prospect of popularization and application. Continuous biomass carbonization technology represents the future development direction of biomass carbonization technology, with the advantages of good production continuity, high productivity, convenient process controlling and relatively stable product quality. In view of the fact that most of the biomass carbonization equipment has poor continuity, high energy consumption and secondary tar pollution, the carbon, gas, and oil co-production process scheme was put forward. Combined with the latest development in the biomass carbonization technology and the raw material characteristics of agricultural and forestry residues, continuous segmentation pyrolysis, multi-stage combined dust removal and fuel/gas reuse heating process methods were used. Based on it, the technologies of evenly and orderly multi-level screw board material delivering, efficient multi-cavity swirl cascade heat transferring, insulated settled and sealed char launching, with system pressure and gas component coupling early warning obtained the breakthrough. In addition, biomass continuous pyrolysis test production system was also developed. When this equipment worked, the raw material was orderly reversed with the rotation of continuous pyrolysis reaction tube in the reaction chamber. Dehydration, volatile precipitation and cracking reaction occurred during this process. As the material fell down, the biochar was separated from the gas. The biochar entered into thermal insulation device and was further carbonized in the oxygen and heat insulation environment. After being cooled down, the production was sequentially output through the screw conveyor. As for the pyrolysis gas, it was transferred to the high-pressure gas storage device using the booster pump after the steps of dust removal, multi-stage condensation, and scrubbing. To form a micro-positive pressure carbonization environment in the reaction chamber, this system would control the air volume in real time with the help of pressure signal feedback. The result showed that the system was stable and reliable. Using the peanut shell as the raw material, its treatment capacity was 28.2 kg/h, the biochar yield was 31.3%, the gas calorific value was 16.3 MJ/m3, and the temperature control precision was ±10 ℃. All of the technical indicators reached the system design goals and requirements. In this way, the pilot system development provided the foundation for equipment amplification and demonstration applications. Biomass pyrolysis and polygeneration can further improve the comprehensive development and utilization benefits of biomass resources, in line with the comprehensive utilization strategic thinking of biomass energy, which has a good application prospect.