Abstract

Dense-phase pneumatic conveying is widely applied in large-scale entrained-bed gasification systems for feeding and conveying pulverized coal into the gasifiers. The discharge stability of blow tanks will affect the conveying process of powders in the conveying pipelines, and ultimately influence the long-term safe and stable operation of the gasifiers. In this paper, aiming at the problem of controllable discharge and conveying of powders in dense-phase pneumatic conveying systems, the research on the discharge analysis of a top discharge blow tank was carried out, which improves the understanding of top discharge blow tanks. Shannon entropy analysis and relative standard deviation analysis based on instantaneous solid mass flow rate signals were used as indicators for the discharge stability. The effects of operating conditions, powder external moisture content, and blow tank structural parameters on the discharge stability of a top discharge blow tank were investigated. The results indicate that for a given pneumatic conveying system, there exists an optimal supplementary gas volume flow rate corresponding to the most stable discharge process of the blow tank. With an increase in the external moisture content of pulverized coal, the discharge stability of the blow tank first increases and then decreases. As the riser diameter increases, the discharge process of the blow tank becomes unstable owing to the increase in the randomness of the conveying process.

摘要

密相气力输送广泛应用于大型气流床气化系统，用于将煤粉送入气化炉。吹气罐的排放稳定性会影响粉体在输送管道中的输送过程，最终影响气化炉的长期安全稳定运行。本文针对密相气力输送系统中粉体的可控卸料和输送问题，开展了顶卸式吹气罐排放分析的研究，提高了对顶卸式吹气罐的认识。基于瞬时固体质量流量信号的香农熵分析和相对标准偏差分析被用作排放稳定性的指标。操作条件的影响，研究了粉体外部水分含量和吹罐结构参数对顶部卸料吹罐排放稳定性的影响。结果表明，对于给定的气力输送系统，存在与吹罐最稳定排放过程对应的最佳补气体积流量。随着煤粉外部水分含量的增加，吹灰罐的卸料稳定性先升高后降低。随着立管直径的增加，由于输送过程的随机性增加，吹气罐的排放过程变得不稳定。存在与放气罐最稳定的排放过程相对应的最佳补气体积流量。随着煤粉外部水分含量的增加，吹灰罐的卸料稳定性先升高后降低。随着立管直径的增加，由于输送过程的随机性增加，吹气罐的排放过程变得不稳定。存在与放气罐最稳定的排放过程相对应的最佳补气体积流量。随着煤粉外部水分含量的增加，吹灰罐的卸料稳定性先升高后降低。随着立管直径的增加，由于输送过程的随机性增加，吹气罐的排放过程变得不稳定。