CIESC Journal ›› 2019, Vol. 70 ›› Issue (8): 3188-3195.DOI: 10.11949/j.issn.0438-1157.20190067

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Effects of high steam partial pressure on desulfurization process of limestone

Kang WANG(),Yang ZHANG,Lilin HU,Hai ZHANG(),Junfu LYU,Guangxi YUE   

  1. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
  • Received:2019-01-21 Revised:2019-03-02 Online:2019-08-05 Published:2019-08-05
  • Contact: Hai ZHANG

高分压水蒸气对石灰石脱硫过程的影响作用

王康(),张扬,胡丽琳,张海(),吕俊复,岳光溪   

  1. 清华大学能源与动力工程系,热科学与动力工程教育部重点实验室,北京 100084
  • 通讯作者: 张海
  • 作者简介:王康(1993—),男,硕士研究生,<email>18612526286@163.com</email>
  • 基金资助:
    国家自然科学基金项目(U1710251)

Abstract:

To understand the limestone desulfuration process in the water-coal-slurry fired circulating fluidized bed (CFB) boiler, in which the steam concentration in the furnace is much higher than the conventional CFB boiler, calcination and sulfuration processes of the limestone desulfuration were respectively studied at a rather wide range of steam concentration using a fixed-bed reactor. The pore structure and apparent morphology of the calcined product and the sulfurized product were analyzed by a true densitometer and a scanning electron microscope. The results show that the presence of water vapor (H2O(g) ) promotes the sintering of calcination product. The porosity and specific surface area of calcination product are lower than those of the calcination product at H2O(g) free condition. With the presence of H2O(g), the macropore portion of calcination product increases, reducing the reactivity of the calcium oxide (CaO) and thereby retards sulfation reaction. With the increase of the H2O(g) concentration, the presence of H2O(g) promotes first and then inhibites sulfuration reaction. At an optimal H2O(g) concentration around 10%, the conversion of calcium is the highest. The reason for the non-monotonic variation is due to that on the one hand, H2O(g) promotes the solid-state diffusion of sulfuration product, and on the other hand, H2O(g) promotes the sintering of unreacted CaO.

Key words: steam concentration effect, limestone, fixed-bed, sintering, calcination, sulfuration, water-coal-slurry CFB boiler

摘要:

针对水煤浆循环流化床锅炉水蒸气浓度高的特点,在较宽的水蒸气浓度内采用固定床反应器对石灰石脱硫过程的煅烧和硫化阶段分别开展机理研究,并利用低温氮吸附法、真密度计和扫描电子显微镜分析煅烧产物和硫化产物的孔结构特征、表观形貌。研究表明水蒸气促进煅烧产物的烧结,减小了煅烧产物的孔隙率和比表面积,增大了大孔份额,使产物氧化钙失去活性;水蒸气对硫化反应的作用呈非单调性,随着水蒸气浓度提高,同一时刻的钙转化率表现为先促进后抑制,在水蒸气浓度10%左右时钙转化率最高。其原因可以归结为水蒸气一方面促进硫化产物固态离子扩散,另一方面促进未反应氧化钙烧结成块。

关键词: 水蒸气作用, 石灰石, 固定床, 烧结, 煅烧, 硫化, 水煤浆循环流化床锅炉

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