高碱煤热烟气强化水洗脱碱及其燃烧结渣沾污研究

Dealkalization by a Novel Flue Gas Enhanced Water Leaching Method and Fouling/Slagging Behavior of High AAEM Coal

新疆高碱煤强结渣沾污特性是影响其大规模燃烧发电的瓶颈问题。本研究基于CO_(2)溶于水形成的碳酸可有效脱除煤中水不溶碱金属碱土金属的原理,提出以热烟气为CO_(2)来源的高碱煤热烟气强化水洗脱碱方法。通过对多种典型新疆高碱煤的实验研究发现,Na的脱除率达到90%以上,Ca的脱除率达到45%,显著优于普通水洗对Na和Ca的脱除效果。洗后煤灰的碱酸比显著降低,灰熔点提高了150℃左右,大部分煤的结渣沾污倾向从严重结渣变为了中等结渣,或从中等结渣变为了不结渣。所以,热烟气强化水洗对高碱煤脱碱及抑制其燃烧过程的结渣沾污具有明显效果。另外,本方法简单可行,而且为电厂烟气(CO_(2))提供了一条新的资源化利用途径,具有明显的经济价值和社会意义。

Severe slagging and fouling issues of Xinjiang’s high alkali coal hindered its large-scale use in power generation.In this study,based on the theory that the carbonic acid formed by the dissolved CO_(2) can effectively remove water-insoluble alkali and alkaline earth metals(AAEM)from coal,a hot flue gas-enhanced water leaching(FG-WL)method was proposed for AAEM re-moval from high alkali coals using the flue gas as the CO_(2) source.Results showed that the removal rate of Na and Ca from several typical Xinjiang high alkali coals reached 90%and 45%,respec-tively,which were significantly better than those from conventional water leaching.Moreover,the alkali-to-acid ratio(B/A)of leached coal ashes were remarkably reduced,the ash melting points were increased by about 150℃,and the tendency of slagging and fouling of coals obviously inhib-ited from the Severe to Moderate,or from the Moderate to Non-slagging after FG-WL treatment.Therefore,the FG-WL method was proven effective in AAEM removal and inhibiting the slagging and fouling risks from high alkali coals.Furthermore,the simplicity and feasibility of this method make it an ideal solution for utilizing power plant flue gases,holding great economic and social significance.