关键词: 废物处理, 热解, 辐射, 市政污泥, 微波诱导协同热解, 节能

Abstract:

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.

Key words: waste treatment, pyrolysis, radiation, sewage sludge, microwave-induced synergistic pyrolysis, energy saving