煤的基本化工过程与污染特征分析

Basic coal chemical processes and their pollution characteristics

通过回顾性叙述煤干馏、煤制焦、煤制气、煤制油等方面的煤化工过程基本原理,分析了煤化工过程的产品方向,从煤的性质、工艺要求和技术特点介绍了煤化工过程产生污染物的原因。从煤制焦、煤制气两个方面重点分析了"三废"的来源及其成分,其中,废气来自化学转化过程中未完全炭化的细煤粉及其析出的挥发分、焦油气、飞灰和泄漏的粗煤气、出焦时灼热的焦炭与空气接触生成的CO、CO_2、NO_2等,废水包括除尘废水、剩余氨水、酚氰废水、脱硫废液、煤气水封水等,废渣包括粉尘、煤尘、酸焦油、焦油渣、剩余污泥等。煤化工过程的气相污染物主要包括碳氧化物、硫氧化物、氨气、挥发酚、苯、苯并芘、CO、CH_4、小分子烃类化合物等,液相污染物除了含有氨氮、氰化物、硫氰化物、硫化物、苯类、酚类及油分外,还含有大量苯并芘、萘等的多环芳烃和吡啶、咔唑、联苯、三联苯等的杂环芳烃化合物。煤化工污染表现为分布面广、组分复杂、高浓度、多相介质共存、环境风险大的特征,而煤化工废水则表现为高浓度/盐分、高污染(组分多)、有毒难降解、富氮缺磷的典型特征。文中指出煤化工过程与污染特征之间的关系的阐明需要科技工作者加深对煤的基本性质、转化过程原理、分离纯化原理、产品应用原理的全面认识,与此对应的技术与策略应当立足于对行业的资源-产品-经济-环境-社会作用链深度理解和有效的系统集成基础上,从规模、产品、技术、管理、市场、人才等方面加强战略设计与逻辑创新的构建。

The basic principles of coal chemical processes were reviewed in this paper including coal carbonization,coal-to-coke,coal-to-gas and coal-to-oil,and the product direction of coal chemical process was analyzed. The reasons of main pollutants produced by coal chemical process were introduced from the coal properties,the process requirements,and the technology features. The source and composition of the ＂three wastes＂ were selectively analyzed from the processes of coal-to-coke and coal-to-gas. Among them,the waste gas came from the incompletely carbonized pulverized coal in the chemical conversion process,the precipitated matters including volatile matter,tar fog and fly ash,the leaked raw gas,as well as CO,CO_2 and NO_2 generated by burning coke on contact with air. The wastewater included dedusting wastewater, surplus aqueous ammonia, phenol and cyanogens wastewater,desulfurization liquid and the water sealing gas. The waste residue included dust,coal dust,acid tar,tar slag and sludge. The gas phase pollutants from coal chemical process mainly included oxycarbide,oxysulphide,ammonia gas,volatile phenol,benzene,benzopyrene,CO,CH_4 and small molecule hydrocarbons. The liquid phase pollutants contained not only ammonia,cyanide,sulphide,benzene,phenol and oil,but also a lot of benzopyrene,naphthalene and other PAHs,and heterocyclic aromatic hydrocarbons including pyridine, carbazole, biphenyl, terphenyl, etc. The pollution characteristics showed wide distribution,complex components,high concentration,coexistence of multiphase mediums with high environment risk. The typical characteristics of the coal chemical wastewater were high concentration/salinity,high pollution（multicomponent）,toxic and refractory. The clarification of the relationship between the coal chemical process and pollution characteristics needed researchers to deepen the comprehensive understanding for the basic coal properties,the principles of conversion,purification and application. Therefore,the control technology and strategy should be based on the deep understanding for the chain of resource- product-economy-environmentsociety and the effective integration system,and the strategic design and logic innovation should be enhanced through the scale,product,technology,management,market and talent.