摘要
准东煤中高含量的碱金属会在燃烧过程中引发严重的结渣与沾污问题,但准东煤气化过程中,在加压条件下碱金属的迁移转化规律仍不明确。为探究准东煤中NaCl在加压条件下的迁移转化机制,根据系统吉布斯自由能最小原则的热力学计算方法,采用HSC Chemistry的化学热力学平衡计算模块,对纯NaCl和准东煤中NaCl在加压过程中Na基化合物的物质的量进行计算。研究结果表明,压力显著影响纯NaCl的气化温度,在常压下,开始气化温度和气化完成温度分别为800℃和1 400℃;压力升至4 MPa时,气化开始温度和气化完成温度分别升至1 500℃和2 200℃。准东煤中Si、Al、H和O参与反应时,在0. 1 MPa条件下,300℃开始,NaCl逐渐与煤灰中的SiO_2、Al_2O_3和H_2O反应生成大量的NaAlSi_3O_8、NaAlSiO_4和Na_2SiO_3等Na基化合物。在1 500℃时,生成的气相NaCl仅占Na物质的量的25%左右。系统反应压力越高,生成低熔点且具有助熔作用的NaAlSi_3O_8、NaAlSiO_4、Na_2SiO_3就越多,导致炉内产生结渣的风险越高。
The high content of alkali metals in Zhundong coal induces serious slagging and fouling problems during combustion,however,the migration and transformation rules of alkali metals under pressurized condition in Zhundong coal gasification are still ambiguous.In order to obtain the migration and transformation mechanism of NaCl in Zhundong coal under pressurized condition,according to the thermodynamic calculation method of Gibbs free energy minimum principle of the system,the thermodynamic equilibrium calculation module of HSC Chemistry was adopted to calculate the molar mass of sodium-based compounds in the pressurized gasification process of pure NaCl and Zhundong coal.The results show that pressure impacts the gasification temperature of pure NaCl significantly.At ordinary pressure,the start and finish temperatures of gasification are 800 ℃ and 1 400 ℃ respectively.When the reaction pressure up to 4 MPa,the start and finish temperatures of gasification increase to 1 500 ℃ and 2 200 ℃ respectively.When the Si,Al,H,O of Zhundong coal participate in the reaction under the condition of 0.1 MPa,300 ℃,the NaCl will react with SiO 2 ,Al 2 O 3 and H 2 O in the coal ash to form a large number of sodium-based compounds,such as NaAlSi 3 O 8 ,NaAlSiO 4 ,Na 2 SiO 3 , etc.In 1 500 ℃,the generated gaseous NaCl accounts for only about 25% of the molar mass of Na.The higher the reaction pressure of the system is,the more NaAlSi 3 O 8 ,NaAlSiO 4 and Na 2 SiO 3 with low melting point and fluxing action will be generated,and the higher risk of slagging in the furnace will be.
作者
王建江
魏博
张雪慧
李显
谭厚章
WANG Jianjiang;WEI Bo;ZHANG Xuehui;LI Xian;TAN Houzhang(Key Laboratory of Coal Cleaning Conversion & Chemical Engineering Process,Xinjiang University,Urumqi830046,China;MOE Key Laboratory of Thermo-Fluid Science and Engineering,Xi'an Jiaotong University,Xi'an710049,China)
出处
《洁净煤技术》
CAS
2019年第2期134-138,共5页
Clean Coal Technology
基金
新疆维吾尔自治区自然科学基金资助项目(2016D01C059)
