Taguchi approach for co-gasification optimization of torrefied biomass and coal

Statistical analysis of CO2/N2 gas separation permeance and selectivity using taguchi method

The separation of CO2 from flue gases presents a crucial challenge that needs to be addressed. However, membrane processes offer a promising alternative solution. Polysulfone (PSF)membranes were prepared using N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) using a dry-wet phase inversion technique. The membranes were fabricated with the selection of casting parameters, PSF concentration (20-30 wt%), solvent ratio of THF/NMP (0/100-35/65), and evaporation time (0-4 min). In this work, the interaction between these influencing factors during preparation and membrane performance was studied. Scanning electron microscopy (SEM) was used to characterize the membranes for morphological investigation. Taguchi statistical analysis was employed in the Minitab-19 software used for the design of the experiments in this study, and the responses of the CO2 permeance and CO2/N2 separation factor were analyzed and optimized based on the casting parameters. The results showed the CO2 permeance of the membranes was determined between 1.25 ± 0.04 and 8.47 ± 0.51GPU and selectivity was between 2.95 and 8.92. The statistical analysis indicated that casting conditions affect membrane performance in the following order: PSF concentration > solvent ratio > evaporation time. The optimum parameters for casting solution were the PSF concentration of 20 wt%, THF/NMP ratio of 17.5/82.5, and evaporation time of 4 min. The selected method also reinforces the connection between membrane casting parameters and the observed outcomes in terms of permeation and morphology.

Analysis of microparticle deposition in the human lung by taguchi method and response surface methodology

The deposition phenomenon of microparticle and SAR-CoV-2 laced bioaerosol in human airways is studied by Taguchi methods and response surface methodology (RSM). The data used herein is obtained from simulations of airflow dynamics and deposition fractions of drug particle aerosols in the downstream airways of asthma patients using computational fluid dynamics (CFD) and discrete particle motion (DPM). Three main parameters, including airflow rate, drug dose, and particle size, affecting aerosol deposition in the lungs of asthma patients are examined. The highest deposition fraction (DF) is obtained at the flow rate of 45 L min^-1, the drug dose of 200 μg·puff^-1, and the particle diameter of 5 μm. The optimized combination of levels for the three parameters for maximum drug deposition is performed via the Taguchi method. The importance of the influencing factors rank as particle size > drug dose > flow rate. RSM reveals that the combination of 30 L min^-1, 5 μm, 200 μg·puff^- has the highest deposition fraction. In part, this research also studied the deposition of bioaerosols contaminated with the SAR-CoV-2 virus, and their lowest DF is 1.15%. The low DF of bioaerosols reduces the probability of the SAR-CoV-2 virus transmission.

Gas-pressurized torrefaction of biomass wastes: Co-gasification of gas-pressurized torrefied biomass with coal

Co-gasification of coal and biomass offers a relatively cleaner utilization way of fossil fuel. The fuel property improvement of biomass can not only improve the property of syngas but also enhance the synergistic effect during the co-gasification. In our previous work, a novel gas-pressurized (abbreviated as GP) torrefaction was proposed to effectively upgrade the biomass under mild condition. In this work, the co-gasification of GP torrefied biomass and coal were conducted to explore the synergistic effect and kinetics. Significant synergistic effect during the co-gasification was proved. The CO yield of co-gasification increased to as high as 70.70 mol/kg, resulting from the promotion of carbon in coal converting into CO by GPRS. Furthermore, the kinetic model of RPM was most fitting for the co-gasification, and the activation energy of co-gasification was reduced. Thus, the coal gasification was promoted significantly by GP torrefied biomass through obvious synergistic effect during the co-gasification.

A Study of the Production and Combustion Characteristics of Pyrolytic Oil from Sewage Sludge Using the Taguchi Method

Sewage sludge is a common form of municipal solid waste, and can be utilized as a renewable energy source. This study examines the effects of different key operational parameters on sewage sludge pyrolysis process for pyrolytic oil production using the Taguchi method. The digested sewage sludge was provided by the urban wastewater treatment plant of Tainan, Taiwan. The experimental results indicate that the maximum pyrolytic oil yield, 10.19% (18.4% on dry ash free (daf) basis) by weight achieved, is obtained under the operation conditions of 450 °C pyrolytic temperature, residence time of 60 min, 10 °C/min heating rate, and 700 mL/min nitrogen flow rate. According to the experimental results, the order of sensitivity of the parameters that affect the yield of sludge pyrolytic oil is the nitrogen flow rate, pyrolytic temperature, heating rate and residence time. The pyrolysis and oxidation reactions of sludge pyrolytic oil are also investigated using thermogravimetric analysis. The combustion performance parameters, such as the ignition temperature, burnout temperature, flammability index and combustion characteristics index are calculated and compared with those of heavy fuel oil. For the blend of sludge pyrolytic oil with heavy fuel oil, a synergistic effect occurs and the results show that sludge pyrolytic oil significantly enhances the ignition and combustion of heavy fuel oil.

Numerical Investigations of the Effects of the Rotating Shaft and Optimization of Urban Vertical Axis Wind Turbines

The central shaft is an important and indispensable part of a small scale urban vertical axis wind turbines (VAWTs). Normally, it is often operated at the same angular velocity as the wind turbine. The shedding vortices released by the rotating shaft have a negative effect on the blades passing the wake of the wind shaft. The objective of this study is to explore the influence of the wake of rotating shaft on the performance of the VAWT under different operational and physical parameters. The results show that when the ratio of the shaft diameter to the wind turbine diameter (α) is 9%, the power loss of the wind turbine in one revolution increases from 0% to 25% relative to that of no-shaft wind turbine (this is a numerical experiment for which the shaft of the VAWT is removed in order to study the interactions between the shaft and blade). When the downstream blades pass through the wake of the shaft, the pressure gradient of the suction side and pressure side is changed, and an adverse effect is also exerted on the lift generation in the blades. In addition, α = 5% is a critical value for the rotating shaft wind turbine (the lift-drag ratio trend of the shaft changes differently). In order to figure out the impacts of four factors; namely, tip speed ratios (TSRs), α, turbulence intensity (TI), and the relative surface roughness value (ks/ds) on the performance of a VAWT system, the Taguchi method is employed in this study. The influence strength order of these factors is featured by TSRs > ks/ds > α > TI. Furthermore, within the range we have analyzed in this study, the optimal power coefficient (Cp) occurred under the condition of TSR = 4, α = 5%, ks/ds = 1 × 10−2, and TI = 8%.

Investigation on the high-temperature flow behavior of biomass and coal blended ash

The high-temperature flow behavior of biomass (straw) and coal blended ash was studied. The variation of viscosity and the temperature of critical viscosity with different straw content were investigated. It is found that the straw ash with high viscosity is unsuitable for directly gasification and the 20% straw content sample can effectively decrease the viscosity. The solid phase content and mineral matters variation calculated by FactSage demonstrate the change of viscosity. In addition, the network theory illustrates that the Si-O-Si bond decreases to improve the viscosity of 20% straw content sample. The variation of mineral matters in XRD analysis validates the change of viscosity. Furthermore, the temperature of critical viscosity and lowest operation temperature reach the minimum when the straw content is 20%. Hysteresis between heating and cooling process of the sample with 20% straw content is more obvious than that of the samples with 40% and 80% straw content.