Longzhi Li

A microwave reactor for characterization of pyrolyzed biomass

A microwave reactor (MWR) was designed to investigate microwave-induced pyrolysis of biomass. Condensation of tars on the quartz reactor and the pipelines was prevented by an electric heating device, and a temperature control function allowed determination of product characteristics at constant temperatures. Temperature had an important influence on microwave pyrolysis; the yields of gas products increased from 17.69 wt.% to 22.27 wt.% and the ratio of combustible gas to total gas products increased from 67.21 vol.% to 77.14 vol.% as the temperature increased from 400 °C to 600 °C. A large number of volatiles was released as temperature increased, resulting in an increase in the number of pores of the coke and a uniform pore structure was obtained. The specific surface area of coke increased from 0.89 m(2)/g (400 °C) to 9.81m(2)/g (600 °C) and the pore volume increased from 0.006 cm(3)/g (400 °C) to 0.012 cm(3)/g (600 °C), but the average pore size decreased from 282.16 nm (400 °C) to 46.64 nm (600 °C).

Kinetics of Pyrolysis of Straw Bales by Microwave Heating

The direct pyrolysis of large size biomass is a difficulty, and it seems to be that microwave pyrolysis is a novel process to overcome the problem. This paper presents the experimental results of microwave pyrolysis process for straw bales in a microwave thermogravimetric analyzer the first time. TG and DTG analysis techniques are adopted to study the pyrolysis behaviors of straw bales systematically. The experimental results show that the input power of microwave, heating time and temperature have important effects on pyrolysis process. Reaction kinetics for microwave pyrolysis of straw bale is analyzed theoretically. A one-step comprehensive model is used to describe the microwave pyrolytic reaction in this experiment. The activation energies for the corn and wheat straw under microwave power of 334 and 668 W/ (kg straw) are 24.4, 26.8 kJ/mol and 67.2, 70.3 kJ/mol, respectively, the pyrolytic reaction is first order. The activation energy and pre-exponential factor increase with the increasing of microwave power. The experiment of microwave pyrolysis provides a new method for the wide uses of straws.

Technical and Economic Analysis on Syngas Production from Biomass Gasification

The processes and routes of syngas production from biomass gasification were first outlined, and the key processes of this technology were highlighted in the paper. Simultaneously, the cost of syngas production from biomass gasification was evaluated to be RMB 1.05/Nm 3 when the handling capacity of gasifier, material cost and system operating rate is separately fixed to be lton/h, RMB 250/ton and 0.8. On this basis, the influences of these three aspects (handling capacity of gasifier, material cost and system operating rate) on the syngas production cost were analyzed. It could be concluded that the reduction in the syngas production cost could be achieved by raising handling capacity of gasifier, reducing material cost and enhancing system operating rate. Finally, the prospect of this technology was put forward from technical and economic points of view.