Black Liquor Slurry Fouling And Slagging Mechanism And Micro-materialized

Slag and ash deposits on boiler in thermal power plant not only decrease the boiler efficiency and the plant economy, but also are potensitial hazards of many safety accidents. Black liquor coal water slurry technology is a new clean coal technology. But it has a strong tendency of slagging. In allusion to this problem, the mechanisms of fouling and slagging was analyzed and studied thoroughly and systematically.A probe based on the law Fourier is designed in this paper to investigate the dynamic changes of resultant heat flux when ash deposits on the heat transfer surface. The result indicates that the heat flux declination gradation of black liquor coal water slurry is lagger than that of coal water slurry. The findings can provide important references and instructions for sootblowing operation optimization.The probes of SiC are used to simulate the ash deposition process on the heat transfer surface, such as water-cooling wall. The result indicates that sedimention speed of black liquor cws is 1.5 times than that of cws, and the tendency of slagging and fouling for black liquor cws is stronger than that of cws.Test of dynamic ash deposition show that Fe is the key factor of formation of initial deposition process.A novel method is presented in this paper to study deposition methanism and formation of coal ash. The electron probe microanalyzer is adopted to analyze mineral elementary distribution along thickness direction at ash deposits, sampled from inside test furnace's several locations. The results show that S, Na, Cl promote the formation of fouling and Fe, Ca play an important role in initial deposition process of slagging.Essential mineral matter in black liquor cws ash deposits is aluminosilicate, such as nepheline and thenardite, according to XRD analysis. The crystal boundary becomes blur according to SEM analysis.Typical location ash samples' molten characteristics changes between Liaohe and Xinwen boiler are analyzed and compared in this paper. The two important factors, ash chemical composition and mineral phase influencing ash's fusing temperature are investigated in details. The reverse change trends of ash behavior inside two boilers are made rational explanation and analysis. The results show coal's characteristics in nature is the root factor deciding mineral behavior inside furnace, and the chief difference of the coal fired in two boilers is the ferric mode of occurrence.Based on the evaluation model with predecessors' experiences, a seven-indexfuzzy comprehensive evaluation model is presented. A method of determining weighting coefficient based on rough set theory is shown in this paper. The proposed approach overcomes the subjectivity of traditional determination to weighting coefficient, and makes combination forecast more objective.