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

Abstract

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 cocombustion 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 SO2 and PM2.5 emissions decreased with corn stover char addition; however, NOX emissions increased and the combustion efficiency decreased slightly with corn stover char addition. The SO2 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/Nm 3 , respectively, and the NOX concentrations were 63. 1-149.7, 54.3-175.4, and 57.7-168.4 mg/Nm 3 , 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.

Co-Combustion Characteristics of Typical Biomass and Coal Blends by Thermogravimetric Analysis

“…Under such a blending ratio, the catalytic effects of biomass char were dramatically restricted by the blocking pores, while for 80% biomass samples, the reaction of biomass in different stages dominated the whole process due to the higher biomass blending ratio. Cong et al (2020) confirmed this result in evaluating the performance of semi-coke and corn stover, and such a trend was also observed.…”

Co-combustion, co-densification, and pollutant emission characteristics of charcoal-based briquettes prepared using bio-tar as a binder

“…Small amounts of starch, sodium nitrate, limestone, borax, and sawdust are generally added to briquettes for improving ignition, promoting steady burning, and to achieve efficient manufacturing [11]. A honeycomb briquette was developed from a blend of semi-coke and corn stover char, and the value-chain model analysis of the new fuel suggests that it has promising application prospects as a heating fuel in rural China [12]. However, difficulties in handling and using bio-tar presented a severe problem to the biomass pyrolysis project.…”