Determination of biomass-coal blending ratio by 14C measurement in co-firing flue gas

Abstract

To verify the feasibility of using radiocarbon detection for the measurement of the biomass-coal blending ratio in co-firing heat and power plants, 14 C activity detection technology that uses benzene synthesis as the sample preparation method and a liquid scintillation counter as the detection instrument was studied. A benzene synthesis system was built to enrich carbon in the combustion flue gas in the form of benzene. The benzene sample was mixed with scintillator (butyl-PBD) and 14 C activity was measured using a liquid scintillation counter (Quantulus 1220). Three kinds of coal and six kinds of biomass were tested repeatedly. The measured 14 C activity was 0.3365 DPM/gC in Zhundong lignite, 0.2701 DPM/gC in Shenmu bitumite, and 0.3060 DPM/gC in Changzhi anthracite. These values were much higher than the instrument background activity. For the co-fired experiment, we used groups with biomass ratios (based on the carbon) of 6.51%, 12.95%, and 20.75%. A modified empirical expression to determine the biomass, coal blending ratio based on the 14 C activity measured in the co-firing flue gas, was proposed by analyzing and verifying measurement accuracy. From the 14 C measurements of the co-fired samples, the corresponding estimated biomass ratios were (5.54±0.48)%, (12.31±0.67)%, and (19.49±0.90)%. The absolute measurement error was around 1% for a typical biomass-coal co-firing application.

Determination of Biomass-Coal Blending Ratio during Indirect Cocombustion by the 14C-Liquid Scintillation Count Method

“…Since the radiocarbon in coal has been completely decayed, , the 14 C activity values of SHC and LCQC represented the background level of the liquid scintillation counter. The results demonstrate that the background values were effectively controlled within acceptable limits through the use of high-purity Mg powder, thus representing an improvement over the previous study . The 14 C activity of poplar wood was found to be significantly higher compared to those of rice husk and corn straw.…”

“…The results demonstrate that the background values were effectively controlled within acceptable limits through the use of high-purity Mg powder, thus representing an improvement over the previous study. 28 The 14 C activity of poplar wood was found to be significantly higher compared to those of rice husk and corn straw. However, there was no noticeable difference between the 14 C activities of rice husk and corn straw.…”

“…To ensure the achievement of complete combustion, a HORIBA PG-350 flue gas analyzer was employed to monitor the gas composition and combustion process in the alternate flue gas path. The carbon dioxide that was taken up was transformed into strontium carbonate precipitate for the subsequent production of benzene, following the procedure outlined in the referenced source …”

“…The carbon dioxide that was taken up was transformed into strontium carbonate precipitate for the subsequent production of benzene, following the procedure outlined in the referenced source. 28 Table 3 presents the categorization of cocombustion conditions based on fuel types or blending ratios. In this table, the symbol ″f biomass cb_actual ″ denotes the actual biomass gas-coal blending ratios used in the study.…”

Optimization of the direct LSC method for determination of biogenic component in liquids by applying 14C

“…Radiocarbon methods based on various concentration of radiocarbon ( 14 C) in biogenic and fossil fuels has been proved to be one of the most accurate and reliable methods of biogenic fraction determination and the only method that directly quantifies the carbon of recent biological origin in a material [5][6][7]. The 14 C method can be successfully applied for determination of biogenic component in any type of samples and by different measurement techniques, such as accelerator mass spectrometry (AMS), liquid scintillation counting with benzene synthesis (LSC-B), liquid scintillation counting with absorption of CO 2 (LSC-A) [3,5,[7][8][9][10][11][12][13]. However, these classical radiocarbon techniques, used for dating purposes mainly, can be expensive and time consuming although applicable to all kinds of material (solid, liquid, gaseous) [3,5,7].…”