煤作为我国主要的一次能源，已被证明能够通过预处理来改善其物理和化学特性。本研究在一种台式试验台上，研究了改变预热温度（Tp）和一次空气当量比（λp）等操作条件对三种典型煤粉预热特性的影响。测量了沿立管轴和自预热燃烧器出口的高温煤气，还分别收集了预热过程中产生的煤焦油和煤焦油并对其进行了分析。结果表明，随着挥发物的显著释放和化学反应的发生，颗粒表面出现裂纹和微孔，使表面的孔隙结构更加发达，而Tp对煤颗粒结构的影响最为显著。此外，当三种典型煤的预热特性达到最佳时，相应的条件也存在明显差异。预热对无烟煤改性程度的影响最大。对于煤焦油，Tp和λp的增加进一步促进了其二次裂化和氧化，导致产量下降。在本研究中，对于烟煤和褐煤，在预热过程中产生了大量的煤焦油，其最高产量分别可达5.74%和6.15%。而对于无烟煤，由于其自身的煤炭性质，其产量极低，均低于1.02%。
ZHANG Jinyang, OUYANG Ziqu, DING Hongliang, SU Kun
. Experimental Study on Product Characteristics of Typical Pulverized Coal Preheated by a Self-Preheating Burner[J]. 热科学学报, 2023
, 32(5)
: 1912
-1934
.
DOI: 10.1007/s11630-023-1848-1
As the major primary energy source in China, coal has been proved to be capable to improve its physical and chemical characteristics by the pretreatment of the self-preheating burner. In this study, the effects of altering operating conditions including preheating temperature (Tp) and primary air equivalence ratio (λp) on preheating characteristics of three typical pulverized coal were investigated on a bench-scale test rig. The high-temperature coal gas compositions along the axis of the riser and at the outlet of the self-preheating burner were measured, and the coal char and coal tar produced in the preheating process were collected and analyzed separately. The results indicated that with the significant release of volatile and the occurrence of chemical reactions, cracks and micropores emerged on the surface of the particles, making the pore structure on the surface more developed, and Tp had the most significant effect on the structure of coal particles. Additionally, there were evident differences in the corresponding operating conditions when the preheating characteristics of the three typical coal reached optimally. And preheating had the strongest influence on the degree of anthracite modification. With respect to coal tar, the increase of Tp and λp further promoted its secondary cracking and oxidation, resulting in a decrease in production yield. In this study, for bituminous coal and lignite, a large amount of coal tar were produced during preheating and the highest production yields could reach 5.74% and 6.15%, respectively. While for anthracite, the production yield was intensely low due to its own coal properties, all below 1.02%.
