Quality control and dust removal analysis of dust-containing gaseous tar from low rank coal pyrolysis

Abstract

Under the background of “carbon peaking and carbon neutrality”, the grading and qualitative conversion of low-rank coal through pyrolysis as the core technology is of great significance to the green and low-carbon development of the coal processing industry. Aiming at the bottleneck problems of high temperature dust removal and quality control of dust-containing pyrolysis tar, the mechanism of coal pyrolysis and volatiles’ reaction is first analyzed, and the effect of dust-containing gaseous tar composition and volatiles’ reaction characteristics on the tar quality and carbon deposition behavior is discussed. Based on the mechanism of volatiles’ reaction, it is proposed to suppress the induction effect of oxygenated compounds on the formation of coke and to supply effective hydrogen to free radical fragments by optimally matching the coal characteristics and operating conditions. Ultimately, the tar quality is improved, and the coke deposition is reduced, thus, a feasible method to effectively relieve the separation pressure of oil and dust in subsequent gaseous tar is put forward. Based on the above method, the related research progress and technical application of dust removal technology and the in-situ upgrading of pyrolysis gaseous tar are analyzed in detail. It is pointed out that the use of granular bed dust removal technology can adjust the volatiles’ reaction path by changing the physical and chemical properties of the filter material and the spatial effect of the packed bed, so as to achieve the synergistic effect of the dust removal and in-situ upgrading of dust-containing gaseous tar. It is particularly important to develop multi-functional media materials suitable for the granular bed filtration and in-situ upgrading of gaseous tar under the premise of ensuring tar yield. As a granular bed filter material, the hierarchical porous carbon-based catalyst can realize the cracking of heavy components and the activation of hydrogen-rich components while filtering dust. In this case, the mass transfer resistance of heavy tar in the pore structure is reduced and the “synchronous hydrogen supply” through the combined effect of active sites and pore structure is also achieved, leading to an effective upgrading of tar quality and inhibiting of coke. The study provides a theoretical guidance for the development of large-scale pulverized coal pyrolysis and the efficient gas-solid separation technology of dust-containing gaseous tar.

Keywords

• pulverized coal
• pyrolysis
• dust-containing gaseous tar
• volatiles’ reaction
• dust removal technology
• tar upgrading