RESUMEN
The impacts of the composition and properties of tar products on their utilization are of great importance, while the consequences of varying tar separation conditions on distillation fractions remain underexplored. Solid impurities in special tar products (e.g., subsurface in situ pyrolysis-derived tar-like substances) can contribute to the separation as well. In the present study, low-temperature coal tar (LTCT) was used as an analogue to pyrolysis product, mixed with semi-coke and coal dust, representing pyrolytic byproducts and nonpyrolytic substances, respectively. The LTCT mixtures were tested with vacuum distillation at various pressures and temperatures. The results revealed the role of pressure in fraction distribution across temperatures, with higher pressure concentrating fractions at lower temperatures. The impact of solid impurities on distillation primarily stemmed from adsorption. Minimal concentrations of solid impurities carried coal dust/semi-coke into the distillation, but higher levels retained them in the residue. The adsorption of coal dust was quite high at lower temperatures and waned as temperature increased, unlike semi-coke, which had consistent adsorption throughout the distillation. The present study can advance the understanding of vacuum distillation for tar products in the presence of solid impurities, offering a framework for the effective distillation/utilization of coal tar. By probing separation conditions, tar properties, and solid impurity effects, the present research will refine strategies for optimizing coal tar use, crucial for enhancing energy security and sustainable progress in China.
RESUMEN
The recovery of low-grade waste heat from power plants greatly benefits energy conservation and emission reduction during electricity generation, while the waste heat utilization directly from desulfurization slurry is a significantly promising method to deeply recover such low-grade energy and has been developed in practical application. However, the pipe materials are subjected to erosion and corrosion challenges due to the high level of solid compositions and the presence of harmful ions, such as Cl-1, which requires further evaluation under the condition of slurry heat exchange. The present study aimed at an experimental study on the erosion-corrosion characteristics of desulfurization slurry on three types of stainless steel, including type 304, 316L, and 2205. Both mass loss and micromorphology features were analyzed with possible mechanisms elucidated. The erosion-corrosion rate is weak at low temperatures, while the increase in the slurry temperature clearly promotes its rate. The influence of the temperature on the corrosion resistance of 304 is much greater than that of 2205. With an increase in duration time, the weight loss rate of stainless steel in the desulfurization slurry declines, and the changing trend of metal mass slightly slows down. The present study offers a better understanding of the erosion-corrosion behaviors of three types of stainless steel under flow and heat transfer conditions of a desulfurization slurry.