10MWth高硫石油焦化学链气化制合成气耦合硫磺回收新系统模拟研究

基于化学链气化技术依靠气固反应定向调控气化产物中H₂S和SO₂摩尔比为2的优势,将化学链气化与Claus工艺中的催化转化单元相结合,提出了高硫石油焦化学链气化制合成气和回收硫磺的新系统。针对系统核心单元,即化学链气化过程,基于Aspen Plus,开展热输入10 MW_th的高硫石油焦化学链气化过程模拟,以赤铁矿石为载氧体,水蒸气为气化介质,重点考察了氧碳比、气化温度对化学链气化过程及硫转化过程的影响。结果发现,氧碳比的增大导致合成气产率显著降低,但系统从需要外部提供能量逐渐转变为对外部放热,在氧碳比0.8669～0.9535区间内,系统可以达到热量自平衡。同时,气化温度的提高对合成气产率是有利的,在975℃时达到2.15 m³/kg,主要是由于CO体积分数随气化温度增加而增加。氧碳比和气化温度的提高都会导致H₂S浓度的降低和SO₂浓度的提高。并且研究了当H₂S和SO₂摩尔比为2的最佳工况时,氧碳比和气化温度为反相关,其中氧碳比为0.8669,气化温度为900℃时,冷煤气效率为64.09%。

Simulation of chemical looping gasification of high-sulfur petroleum coke for syngas production coupled with recycling sulfur in 10 MWth system

The present work proposes a novel system which integrates high-sulfur petroleum coke chemical looping gasification (CLG) and sulfur recovery. Depending on the gas-solid reaction, CLG process has the ability to control the reaction pattern to obtain the mole ratio of H₂S and SO₂ as 2 in the syngas. The chemical chain gasification is combined with the catalytic conversion unit in the Claus process, and the high sulfur petroleum coke chemistry is proposed. Focusing on the core part of the system, CLG section, the simulation using the Aspen Plus was performed. The thermal input was designed as 10 MW_th with high-sulfur petroleum coke as fuel. Iron ore and steam were used as oxygen carrier and gasification agent respectively. Effects of O/C, gasification temperature on the thermal balance during CLG process, syngas yield, effective gas content and sulfur conversion were investigated. Results indicated that increasing O/C leads to a decrease in the production yield of syngas, but the system gradually shifts from the endothermic to exothermic. When O/C is between 0.8669 and 0.9535, the system can maintain the heat balance without extra energy. Further, the increase of temperature is beneficial to syngas production. The CO concentration increases with increasing temperature and reaches 2.15 m³/kg at a gasification temperature of 975℃. A high ratio of O/C and gasification temperature can enhance H₂S conversion during gasification process with a consequence of H₂S concentration decreasing and SO₂ concentration increasing. Furthermore, in the best case of the mole fraction of H₂S to SO₂ as 2, a negative correlation on the factors of O/C ratio and temperature was found. The cold gas efficiency is 64.09% at the conditions of the O/C ratio as 0.8669 and the gasification temperature of 900℃.