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含油污泥是石油化工行业在生产、集输等过程产生的一种固体废弃物。其成分复杂,含有大量残留石油类物质、苯系、酚类、蒽、芘等有毒物质,除此之外还含有Cu、Cr、Pb等重金属[1]。含油污泥因具有毒性和易燃性而被列入《国家危险废物名录(2021)》HW08条目中[2]。我国石化行业每年产生的含油污泥约为300×104 t[3]。含油污泥如未经有效处理而任意堆放不仅会侵占土壤、污染水系和大气,还会对人群健康造成严重威胁。然而,含油污泥中含有的石油烃(PHCs)具有很高的回收价值。面对我国环保标准日益严格及能源消耗量增加的现实,如何实现含油污泥的资源化和无害化是当今亟待解决的问题。目前,含油污泥常用的处理技术有焚烧法[4]、化学热洗法[5]、微波法[6-7]、溶剂萃取法[8]等。这些技术共同的弊端是,含油污泥中的PHCs回收不充分,而且会造成二次污染。然而,热解法能充分回收油泥中烃类物质,以实现热解过程中有害成分的“零排放”[9-10]。含油污泥的热解是在高温、缺氧的条件下,利用含油污泥中的有机物的热不稳定性而引起有机物的热分解的过程,最后得到含油污泥热解的三相产物,分别为气体、液体和固体,也被称为干化热解技术[11]。
热解终温是影响热解产物特性的重要因素,许多研究者已对该问题进行了研究。刘颖等[12]发现,有机质发生热解反应的主要温度为350~500 ℃和575~625 ℃;温度越高,热解残渣率和热解残渣含油率越低,热解产气率越高。VIDONISH等[13]发现,在150 ℃时,轻质烃发生分解反应;而在400~500 ℃时,重质油开始发生裂解,热解气态产物主要是CO2、烃类、H2O和CO。GONG等[14]发现,当温度达到200~580 ℃时,油泥热解产生大量挥发性物质及轻质油,当热解温度于580~800 ℃时,有机残渣的分解及某些重金属盐在高温下发生了复杂的化学反应。
然而,在含油污泥热解研究中,对热解终温影响油泥三相产物的分析和产物析出规律的研究不够深入。为此,本实验通过研究不同热解终温下热解油、热解气和热解残渣的特性,为资源化利用含油污泥提供参考。
热解终温对含油污泥三相产物特性的影响
Effect of final pyrolysis temperature on characteristics of three-phase products of oily sludge
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摘要: 为实现含油污泥的资源化利用,以罐底油泥为研究对象并以油回收率为考核指标,对热解终温对油泥三相产物的影响进行了研究。结果表明,最佳热解条件是:升温速率为10 ℃·min−1、载气中最佳氧气体积分数为4.2%。在400~800 ℃范围内,随着温度的升高,回收的热解油产率由16.43%提升至21.46%,后又降至14.15%;热解气产率由9.12%提升到了27.87%,热解残渣中可回收组分含量由39.1%降至16.5%。热解油中主要为轻质组分,油的品质较高;热解气中主要成分为CO2和CO,且温度越高可燃气比例越高。对热解残渣进行电镜分析发现,渣体表面没有结焦现象,残渣表现出良好的吸附性能。本研究可为含油污泥热解处理资源化提供参考。Abstract: In order to realize the resource utilization of oily sludge, the effect of final pyrolysis temperature on three-phase products of oily sludge was investigated with the tank bottom sludge as the research object and the oil recovery rate as the assessment index. The experimental results were summarized as follows. The optimal pyrolysis condition was set with heating rate as 10 ℃·min−1 and oxygen concentration in carrier gas as 4.2%. In the range of 400~800 ℃, with the elevation of temperature, the yield of recovered pyrolysis oil increased from 16.43% to 21.46% and then decreased to 14.15%, the pyrolysis gas yield increased from 9.12% to 27.87%, and the content of recoverable components in residues decreased from 39.1% to 16.5%. The pyrolytic oil was mainly composed of light components in high quality. In addition, the main components of pyrolysis gas are CO2 and CO, and the higher the temperature is, the higher the proportion of combustible gas is. Moreover, no coking was on surface by electron microscope analyses and the pyrolytic residue showed good adsorption capability, which ensured the possible employment as an adsorbent. This study can provide reference for resource utilization of oily sludge pyrolysis treatment.
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Key words:
- oily sludge /
- final pyrolysis temperature /
- three-phase products /
- resource
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表 1 油泥的组分分析、元素分析及热值
Table 1. Component analysis, elemental analysis and calorific value of oil sludge
组分分析/% 元素分析/% 热值/(MJ·kg−1) 水分 灰分 挥发分 C H N S 17.3 38.6 42.7 54.9 9.3 0.3 2.2 16.9 表 2 不同热解终温下热解残渣的组分分析、热值和碘离子吸附量
Table 2. Component analysis, calorific values, and iodide adsorption capacities of pyrolysis residues at different final pyrolysis temperatures
热解
温度/℃组分分析 热值/
(MJ·kg−1)碘离子吸附量/
(mg·g−1)挥发分/% 灰分/% 400 39.1 60.9 12.8 2170 500 36.8 63.2 12.3 2320 600 35.7 64.3 11.7 2690 700 27.4 72.6 10.8 2720 800 16.5 83.5 7.6 1780 -
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