基于微波诱导定向加热的污泥新型热解方法能耗分析

Energy consumption analysis of novel pyrolysis method of sewage sludge based on microwave-induced target-oriented heating

针对现有污泥热解技术耗时耗能、炭性能受限等难题,提出微波诱导协同热解的新型技术思路,即仅先用常规初级热解获得微波强化吸收的热解基体,再用微波诱导其高能位点效应,以期低能耗制备较高性能的污泥炭。对样品进行介电特性、工业分析等多种测试,在简要分析并验证该思路可行的基础上,探寻其能耗机制,以期为实际应用提供参考。结果表明,通过常规700℃热解10min的热解基体,介电特性提高约22%,可在微波900W中5min升高到平均900℃;不仅提高炭性能,而且比常规700℃热解60min节能省时达50%以上,这主要归因于对热解过程整体用时的显著缩减与微波能的高效利用。研究思路为低能耗制备高附加值污泥炭奠定工艺应用基础,有望实现污泥大规模资源化处置。

There are many difficulties of current research on sewage sludge pyrolysis, such as time consuming, high energy consumption and limitation of char properties. To solve those difficulties, this paper provides a novel technical approach of microwave-induced synergistic pyrolysis. Namely without adding extra microwave absorbent, semi-pyrolytic sludge char can be obtained by pre-pyrolysis of sewage sludge itself under conventional low energy consumption;then it is used as basal body to be pyrolysed under microwave, which is based on in-situ carbonation enhancement by high-energy-site effects and heavy metal solidification via vitrification;finally, highly stable sludge char is expected to be produced with low energy consumption in the novel process. The paper tested the dielectric properties, proximate analysis, toxicity characteristic leaching procedure, specific surface area and SEM images of sewage sludge materials. By brief analysis and verification of feasibility of the novel approach, its energy consumption mechanism was focused on, which will contribute to practical application. In this experiment, semi-pyrolytic sludge char produced by pre-pyrolysis(700℃, 10 min) could increase whole dielectric properties by 22%, that was conductive to achieve average 900℃ in 5 min under microwave pyrolysis (900 W). That was helpful for improving properties of sludge char, and the novel pyrolysis process saved up to 50% than the traditional one (700℃, 60 min). Energy saving property of the novel approach is mainly attributed to obviously shorten whole pyrolysis time and high efficiency utilization of microwave energy. This novel technical approach can complete the preparation of highly stable sludge char with low energy consumption, and will open a large-scale disposal route for sewage sludge.