醋酸钾对轻石脑油裂解结焦的影响  

Influence of potassium acetate on coke formation during cracking of light naphtha

作　　者：栾小建[1] 徐宏[1] 王志远[1] 周建新[1,2] 曲瑞波[1] 

机构地区：[1]化学工程联合国家重点实验室,华东理工大学机械与动力工程学院,上海200237 [2]南京工业大学机械与动力工程学院,江苏南京210009

出　　处：《化工学报》2011年第12期3405-3410,共6页CIESC Journal

基　　金：上海市曙光跟踪计划项目~~

摘　　要：为考察碱金属元素对裂解结焦的影响,以醋酸钾为结焦抑制剂,在850℃下对退役25Cr35Ni炉管试样内表面进行了结焦实验。利用扫描电子显微镜(SEM)、场发射扫描电镜(FE-SEM)、能量色散谱仪(EDS)、X射线衍射(XRD)和Raman光谱对退役25Cr35Ni炉管试样内表面和焦层进行了表征。结果表明,退役25Cr35Ni炉管内表面主要由Cr1.3Fe0.7O3、FeCr2O4、Mn1.5Cr1.5O4和Fe、Ni的金属间化合物,以及针状的Cr与Fe金属间化合物的析出相组成。醋酸钾对结焦有显著的抑制作用,在添加量为200μg.g-1时,结焦抑制率为51.54%。醋酸钾没有缩短焦丝长度,而是细化了丝状焦的直径。醋酸钾抑制结焦的主要机理为:醋酸钾中的碱金属元素催化了由非催化结焦机理生成的焦炭颗粒与水蒸气的气化反应。退役25Cr35Ni炉管试样内表面的焦层均是由sp2和sp3的C混合结构组成。醋酸钾的加入提高了焦炭的石墨化程度。To study the influence of alkali metal on coke formation, a coking test was carried out on the inner surface of a used 25Cr35Ni cracking tube at 850℃ usmg potassium aceate as coking inhibitor.Its inner surface and cokes deposited in the coking tests were characterized by scanning electron microscopy （SEM）, field-emission scanning electron microscopy （FE-SEM）, X-ray energy dispersion spectrometry （EDS）, X-ray diffraction （XRD） and Raman spectroscopy. The results showed that the inner surface of the used 25Cr35Ni cracking tube was mainly composed of Cr1. 3 Fe0.7 O3, FeCr2O4, Mn1.5 Cr1.5O4, the intermetallic compound （Fe and Ni） and the needle-like deposition phase （intermetallic compound of Cr and Fe）. Potassium acetate could inhibit coke formation effectively. When its concentration was 200 μg·g^-1, deposition of coke was reduced by 51.54% in lh. Potassium acetate did not change the length of coke filament, but it made filament diameter into nanometer level. The mechanism of inhibiting coking by potassium acetate was that gasification reaction between coke and water was catalyzed by alkali metal. The carbon in cokes deposited on the inner surface was of sp^2 and sp^3 bonds structure. Potassium acetate increased also graphitization degree of coke deposited.

关 键 词：退役25Cr35Ni炉管 裂解 石脑油 醋酸钾 结焦 

分 类 号：TE624[石油与天然气工程—油气加工工程] TK227.2[动力工程及工程热物理—动力机械及工程]