Evaluating the performance of honeycomb briquettes produced from semi-coke and corn stover char: Co-combustion, emission characteristics, and a value-chain model for rural China.

A honeycomb briquette made from semi-coke and corn stover char was developed as a possible heating fuel in rural China. In this study, the co-combustion characteristics of semi-coke and corn stover char combined in different proportions were tested and analyzed. It was determined that adding 20% corn stover char (BS28) effectively improved the combustion performance of semi-coke, and this proportion was regarded as the ideal mixing ratio. Thus, the integrated combustion characteristics of the blend improved to 15.08 × 10−12 K−3 min−2 compared to 5.44 × 10−12 K−3 min−2 for semi-coke alone. The emission test results revealed that SO 2 and PM 2.5 emissions decreased with corn stover char addition; however, NO X emissions increased and the combustion efficiency decreased slightly with corn stover char addition. The SO 2 concentrations resulting from the combustion of BriqCK, Briq28, and Briq46 (honeycomb briquettes with ratios of char to semi-coke of 0:10, 2:8, and 4:6, respectively) under different experimental conditions were 24.9–26.3, 9.5–16.7, and 5.2–15.4 mg/Nm3, respectively, and the NO X concentrations were 63.1–149.7, 54.3–175.4, and 57.7–168.4 mg/Nm3, respectively. A value-chain model for the new heating fuel was developed and possible benefits were analyzed. If either the new investment cost or raw material input costs ($25 USD/t of straw char) were subsidized by national public finance, then the project would be profitable and run sustainably. This study provided an important technical basis for the development and application of new heating fuels in China. Image 1 • Semi-coke was condensed with corn stover char to produce heating fuel. • Corn stover char improved the integrated combustion characteristics of semi-coke. • SO 2 and PM 2.5 emissions decreased with the addition of corn stover char. • NO X emissions increased slightly with the addition of corn stover char. • A value-chain model for the new heating fuel was designed and analyzed. [ABSTRACT FROM AUTHOR]