Abstract

Torrefaction is considered as a method for producing biofuels with improved characteristics compared to those of the “raw” biomass (higher calorific value, moisture resistance, better grindability). The torrefaction process is an endothermic process that is usually carried out in a gaseous atmosphere in the absence of oxygen. To reduce the required heat input, it is proposed to employ the oxidative torrefaction and conduct the process in a fluidized bed agitated with flue gases containing less than 6% oxygen. Preliminary studies of the oxidative torrefaction of sunflower husks, including thermogravimetric analysis of the treated material, have shown that the heat treatment time for the biomass should be at least 5 min. A fluidized bed is a reactor with ideal mixing of the treated material where uniform treatment of raw material particles cannot generally be attained. To overcome this disadvantage of the fluidization technique and achieve the required residence time for biomass in a fluidized bed during a continuous torrefaction process, it was proposed to equip a torrefaction reactor with a series of vertical baffles spaced at 50 mm. These baffles induce a loop-like flow of the processed biomass from the inlet to the outlet of the reactor. To investigate the residence time for husk particles in the reactor, a tracer, which was colored to husk particles' color with a water-soluble dye which did not change the weight and size of the particles, was injected into the bed of uncolored particles. Tracer samples were taken every 30 s at the outlet of the reactor and were analyzed using a special procedure to determine the fraction of colored particles in each sample. This enabled us to gauge the time during which the colored particles injected into the fluidized bed reached the point of their discharge from the bed. Studies performed in a “cold” model of the reactor showed that a series of vertical baffles in the bed can provide the required residence time for biomass in a reactor including commercial reactors. Plates can provide the necessary biomass residence time in the reactor.

中文翻译：

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流化床反应器氧化生物废料的研制

摘要

与“原始”生物质相比，烘焙被认为是一种具有改进特性的生物燃料的生产方法（较高的发热量，耐湿性，可磨性）。烘焙过程是吸热过程，通常在没有氧气的气体气氛中进行。为了减少所需的热量输入，建议采用氧化焙烧法，并在流化床中进行该工艺，该流化床中的烟气含氧量少于6％。对葵花皮氧化焙烤的初步研究（包括对处理过的物料进行热重分析）表明，生物质的热处理时间至少应为5分钟。流化床是一种理想地混合处理过的物料的反应器，通常无法实现对物料颗粒的均匀处理。为了克服流化技术的这一缺点并在连续的焙干过程中获得生物质在流化床中所需的停留时间，提出给焙干反应器配备一系列间隔为50mm的垂直挡板。这些挡板引起处理后的生物质从反应器的入口到出口的环状流动。为了研究壳中颗粒在反应器中的停留时间，将示踪剂注入未着色颗粒床中，该示踪剂用不改变颗粒重量和尺寸的水溶性染料着色为壳中颜色。示踪剂样品每30 s在反应器出口采集一次，并使用特殊程序进行分析，以确定每个样品中有色颗粒的比例。这使我们能够测量注入流化床中的有色颗粒达到从床中排出的时间。在反应器的“冷”模型中进行的研究表明，床中的一系列垂直挡板可以为生物质在包括商业反应器的反应器中提供所需的停留时间。板可以提供反应器中必要的生物质停留时间。在反应器的“冷”模型中进行的研究表明，床中的一系列垂直挡板可以为生物质在包括商业反应器的反应器中提供所需的停留时间。板可以提供反应器中必要的生物质停留时间。在反应器的“冷”模型中进行的研究表明，床中的一系列垂直挡板可以为生物质在包括商业反应器的反应器中提供所需的停留时间。板可以提供反应器中必要的生物质停留时间。