A Method for the Quantification of Alkali and Alkaline Earth Metallic Species in Bioslurry Fuels

This study reports a method for the quantification of alkali and alkaline earth metallic (AAEM) species in bioslurry fuels. The so-called evaporation-ashing-digestion-ion chromatography (IC) method consists of four steps, including evaporation that converts bioslurry into solid-like residue, ashing that converts the residue into ash, acid digestion that dissolves the ash into a solution, and IC analysis that quantifies the AAEM species in the solution. The novelty of the method is the combination of the evaporation step with the existing ashing-digestion-IC method that is developed for solid fuels but notsuitable for bioslurry fuels. The evaporation step consists of multi-steps of slow heating and holding at various segment temperatures corresponding to the boiling points of the major compounds in bio-oil, resulting in progressive evaporation of biooil vapors with little carry-over of biochar particles. The method has been successfully applied for quantifying AAEM species in bioslurry fuels with various biochar loading levels (5-20 wt %), with small relative standard errors (within ±3%) and low limitations of quantification (0.4-3.0 ppm). It also overcomes the biochar incomplete oxidation issue associated with the microwave-digestion-based methods, which considerably underestimate the concentrations of AAEM species in bioslurry fuels

Phase Behavior and Fuel Properties of Bio-Oil/Glycerol/Methanol Blends

This study investigates the phase behavior and fuel properties of a series of bio-oil/glycerol/methanol blends. The results show that even though glycerol has a poor solubility in bio-oil, homogeneous bio-oil/glycerol/methanol fuel blends can be prepared with appropriate amount of methanol addition. Compared to the bio-oil or glycerol alone as a fuel, the bio-oil/glycerol/methanol blends have improved fuel properties (higher heating value, lower viscosity, and lower surface tension, etc.). Taking into safety consideration during storage and transportation of a fuel and the possible ratio of glycerol to methanol that may be obtained from biodiesel production process, potential feasible compositions of the bio-oil/glycerol/methanol blends (bio-oil ≥ 70 wt %; glycerol ≤ 20 wt %; methanol ≤ 10 wt %) are recommended as burner fuel for combustion applications. Further accelerated aging experiments of selected fuel blends in the recommended composition range indicate that the fuel blends experience decreases in the viscosity and total acid number and an increase in water content of the fuel blends upon long-term storage

Bioslurry as a fuel. 5. Fuel properties evolution and aging during bioslurry storage

This study investigates the evolution of fuel properties and aging of a series of bioslurry fuels prepared from fast pyrolysis bio-oil and biochar at different biochar loading levels (up to 20 wt %) for a storage period of 29 days. The results demonstrate that, at room temperature, the storage of bioslurry results in a reduction in the acidity [total acid number (TAN)], a reduction in the viscosity, and an increase in the water content of the bio-oil phase. In comparison to the blank bio-oil samples, the presence of biochar leads to more severe changes in the fuel properties of bioslurry. After 29 days of storage, the bioslurry fuels are still acidic. An increase in the biochar loading level further decreases the TAN and viscosity of bio-oil phases and increases the water content of bio-oil phases. The storage of bioslurry also results in undesired redistribution of alkali and alkaline earth metallic species between the biochar and bio-oil phase in bioslurry, via the leaching of these inorganic species from the biochar into the acidic bio-oil by two-step kinetics