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Porous media combustion (PMC) is relatively a new concept, and due to its inherent characteristics of high efficiency and low emissions, it has found wide applications in many practical systems like internal combustion engine (IC engine), water heater, LPG (Liquefied Petroleum Gas) stoves, etc. In this study, the concept of PMC has been employed in a kerosene pressure stove, and the usefulness of the media consisting of alumina (Al2O3) and silicon carbide (SiC) in terms of efficiency and emissions is investigated. Further, the conditions for optimum efficiency and emission are brought out through a systematic analysis with different burner geometry and exergy calculation. The major highlight of this study is that the highest efficiency of the stove with porous media is found to be ∼10% higher than the average thermal efficiencies of the stoves available in the Indian market.

An important aspect of the commercialization of biomass gasifiers is feedstock flexibility. The present study has dealt with performance assessment of a circulating fluidized bed gasifier (50 kWth) with binary blends of three biomasses, sawdust (SD), rice husk (RH) and bamboo dust (BD), as feedstock. The performance of gasification was assessed in respect of the specific yield of producer gas, its LHV, and tar content in addition to gasification efficiencies. Experiments were conducted with varying equivalence ratio (ER) from 0.19 to 0.35, and temperatures of 800°–900 °C. The blending of biomasses resulted in the enhancement of gasification performance due to synergistic effects. Minerals in the ash of RH catalyzed char and tar conversion leading to higher efficiencies. At ER = 0.35, maximum CGE = 62% and CCE = 98% were obtained for RH + BD blend. With increasing temperature, H2, CO content and net yield of producer gas increased with concurrent decreasing in tar. The highest LHV of producer gas (5.05 MJ/Nm3) was obtained for the RH + BD blend at ER = 0.19 and 800 °C. Maximum gas yield (1.72 Nm3/kg dry biomass) and minimum tar content (2.01 g/kg dry biomass) were obtained for SD + BD and RH + BD blends, respectively, at 800 °C and ER = 0.35.

Low-grade coal and biomass waste such as bamboo dust, sawdust, rice husk, etc. are abundantly available in India. Utilization of such resources to generate electricity is a challenging task with conventional methods. Atmospheric circulating fluidized bed (ACFB) is considered to be one of the potential devices to utilize coal or biomass or both for power production through gasification or combustion routes. In this paper, the effect of various operating parameters such as bed inventory, particle size, superficial velocity, blends of coal with sawdust (percentage by weight) and operating pressure on bed hydrodynamics, i.e., bed voidage, suspension density, and solid circulation rate were studied experimentally in a pressurized circulating fluidized bed (PCFB). The bed voidage decreases with an increase in operating pressure and increases with an increase in particle size. Maximum of 8.2% decrement in bed voidage is observed as operating pressure varies from atmospheric to 4 bar. Further, the suspension density is found to increase with an increase in inventory weight. Peak increment of 28.3% in suspension density is perceived with an increase in inventory weights at a pressure of 4 bar.

In recent years, biomass gasification has emerged as a viable option for decentralized power generation, especially in developing countries. Another potential use of producer gas from biomass gasification is in terms of feedstock for Fischer–Tropsch (FT) synthesis – a process for manufacture of synthetic gasoline and diesel. This paper reports optimization of biomass gasification process for these two applications. Using the non–stoichometric equilibrium model (SOLGASMIX), we have assessed the outcome of gasification process for different combinations of operating conditions. Four key parameters have been used for optimization, viz. biomass type (saw dust, rice husk, bamboo dust), air or equivalence ratio (AR = 0, 0.2, 0.4, 0.6, 0.8 and 1), temperature of gasification (T = 400, 500, 600, 700, 800, 900 and 1000 °C), and gasification medium (air, air–steam 10% mole/mole mixture, air–steam 30%mole/mole mixture). Performance of the gasification process has been assessed with four measures, viz. molar content of H2 and CO in the producer gas, H2/CO molar ratio, LHV of producer gas and overall efficiency of gasifier. The optimum sets of operating conditions for gasifier for FT synthesis are: AR = 0.2–0.4, Temp = 800–1000 °C, and gasification medium as air. The optimum sets of operating conditions for decentralized power generation are: AR = 0.3–0.4, Temp = 700–800 °C with gasification medium being air. The thermodynamic model and methodology presented in this work also presents a general framework, which could be extended for optimization of biomass gasification for any other application.