CIESC Journal ›› 2015, Vol. 66 ›› Issue (4): 1537-1543.DOI: 10.11949/j.issn.0438-1157.20141567

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Characterization and modeling of limestone calcination and sulfation in oxy-fuel combustion atmosphere

WANG Chunbo, ZHANG Bin, CHEN Liang, GUO Taicheng   

  1. School of Energy Power and Mechanical Engineering, North China Electric Power University, Baoding 071003, Hebei, China
  • Received:2014-10-16 Revised:2014-12-18 Online:2015-04-05 Published:2015-04-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51276064).

富氧燃烧气氛下石灰石煅烧/硫化特性及模型模拟

王春波, 张斌, 陈亮, 郭泰成   

  1. 华北电力大学能源动力与机械工程学院, 河北 保定 071003
  • 通讯作者: 王春波
  • 作者简介:王春波(1973-),男,教授。
  • 基金资助:

    国家自然科学基金项目(51276064)。

Abstract:

The characteristics of simultaneous calcination and sulfation of limestone in the atmosphere simulating circulating fluidized bed oxy-fuel combustion were studied using an experimental system that could measure sample mass changes at a preset temperature. The pore structure and conductivity of samples were measured to study the diffusion mechanism in the product layer. Compared with CaO that was calcined without SO2, the porosity of CaO was easier to be blocked up and the process had a shorter duration before transfering into the diffusion control stage when limestone calcination and sulfation occured simultaneously. A higher sulfation rate and higher conversion were observed because of higher diffusibility in the product layer than that of CaO calcined without SO2. Sintering of CaO would decrease its sulfation capability, especially when temperature was above 950℃. Particle size was an important factor that determined sulfation of sorbents, and higher sorbent utilization would be obtained for smaller particles. Also, higher SO2 concentration would improve sulfation of sorbents. A grain-micrograin model was set up, and the effects of some factors, such as temperature, sorbent particle size and SO2 concentration were simulated. The calculation results fitted well with the testing.

Key words: circulating fluidized bed, CO2 capture, limestone, simultaneous calcination/sulfation, numerical simulation

摘要:

利用自制恒温热重装置,模拟循环流化床富氧燃烧气氛,进行了石灰石同时煅烧/硫化实验,并通过对煅烧/硫化产物孔结构以及硫化产物电导率的测量,探讨了硫化反应机理。相比石灰石先煅烧成CaO再硫化,吸收剂孔隙更容易堵塞且更早进入到产物层扩散控制阶段;产物层扩散控制阶段固态离子扩散率更高,可获得更快的硫化速率和更高的最终钙转化率。烧结会极大影响CaO的钙转化率,尤其当温度高于950℃时;粒径效应显著,随石灰石颗粒粒径减小最终钙转化率明显提高;SO2浓度提高有助于最终钙利用率的提高。建立了晶粒-微晶粒模型,对不同温度、粒径、SO2浓度条件下石灰石同时煅烧/硫化特性进行了数学模拟,模拟结果与实验结果较为吻合。

关键词: 循环流化床, 二氧化碳捕集, 石灰石, 同时煅烧/硫化, 数值模拟

CLC Number: