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Ultra-small biomass gasification and power generation systems are a promising technology for disaster areas in developed countries and non-electrified rural areas of developing countries. The gasification characteristics of carbonized wood pellets and carbonized wood briquettes without or with 1 wt% sea salt were tested in a pilot-scale updraft fixed-bed gasifier. The results showed that the carbon balance during gasification was easily achieved, and most of the chlorine in the carbonized briquettes with sea salt remained in the residual char and fly ash after gasification. Inorganic chlorine in the solid fuel was transformed into organic chlorine combined with carbon matrix after heat treatment in the gasifier. Syngas with a low heating value higher than 4 MJ·m −3 could be continuously obtained when the system reached a stable condition, which enabled power generation using a gas engine. A combination of several secondary tar removal processes was adopted for the syngas purification. The tar content in the syngas after the gas cleaning for 425 °C-carbonized pellet, 425 °C-carbonized briquette, 475 °C-carbonized briquette, and 475 °C-carbonized briquette with sea salt was 0.98, 0.26, 1.4, and 0.2 g·Nm −3 , respectively. During the stable stage, 425 °C-carbonized pellet showed the highest cold gas efficiency (CGE) of 45.6% and carbon conversion efficiency (CCE) of 57.8%, respectively, with an equivalence ratio (ER) of 0.24. A lower carbonization temperature showed a higher CGE and CCE. The residual char and fly ash after gasification could be considered for reuse as feedstock to further improve the overall process efficiency. The maximum output power was 23 kW at an air flow rate of 40 Nm 3 /h during the gasification of carbonized pellets, and the corresponding overall power generation efficiency of the engine using the syngas was about 27.8%. For 475 °C carbonized briquette, the maximum output power was 18 kW at an air flow rate of 40 Nm 3 /h, and the corresponding overall power generation efficiency of the engine using the syngas was about 25.5%. [ABSTRACT FROM AUTHOR]

Small-scale, distributed and low cost biomass power generation technologies are highly required in the modern society. The biomass pretreatment process, that is, a combination of carbonization and pelletization processes of cedar wood were explored in this study. For the carbonization process, a novel carbonizer composed of one carbonization chamber and one combustion chamber was tested, and the mass and energy balances during cedar wood carbonization at 400–500 °C were analyzed, respectively. During the initial heating stage, about 22 kg of wood with dry basis should be supplied into the combustion chamber through several batches. When the temperature in the carbonization chamber reached to the range of 200–220 °C, the combustion chamber could be self-heated by burning the pyrolysis gas (tar vapor, CH 4 , H 2 , CO) sent from the carbonization chamber. The specific wood consumption for producing 1 kg of wood char was within 3.6–4.4 kg, which presented an increase trend with increasing the carbonization temperature. Moreover, this carbonization system can deal with different kinds of biomass with various water contents and shapes. For the pelletization process, effects of adding amount of the binder (poval solution), water and the carbonization temperature on the pellet quality were studied so as to explore the optimal condition for making high quality pellets from the crushed wood char. The results indicated that there was an optimal ratio among char, added water, and the binder for making high quality pellets. Considering the energy transfer efficiency and pellet quality, the mass ratio of 0.93:0.32:0.10 for 450 °C-char in the dry basis: added water plus water in char: poval solution was the optimal condition for making high quality pellets. [ABSTRACT FROM AUTHOR]