Development of a bi-equilibrium model for biomass gasification in a downdraft bed reactor.
This work proposes a simple and accurate tool for predicting the main parameters of biomass gasification (syngas composition, heating value, flow rate), suitable for process study and system analysis. A multizonal model based on non-stoichiometric equilibrium models and a repartition factor, simulating the bypass of pyrolysis products through the oxidant zone, was developed. The results of tests with different feedstocks (corn cobs, wood pellets, rice husks and vine pruning) in a demonstrative downdraft gasifier (350kW) were used for validation. The average discrepancy between model and experimental results was up to 8 times less than the one with the simple equilibrium model. The repartition factor was successfully related to the operating conditions and characteristics of the biomass to simulate different conditions of the gasifier (variation in potentiality, densification and mixing of feedstock) and analyze the model sensitivity.
Airflow Channeling Through Fixed Wheat Straw Bed in an Updraft Gasifier Before the Initiation of Gasification
Channeling is an operational problem of updraft gasifiers used to gasify cereal straw. Airflow distribution within a fixed straw bed before the initiation of gasification was investigated to understand the channeling. Absolute pressure deviations in the central plane of the straw bed were determined to check the uniformity of airflow distribution, because pressure was the driving force of airflow. Airflow channeling occurred through the straw bed even before the initiation of gasification. Superficial velocity through the straw bed inversely affected the uniformity of airflow distribution while machine-chopped straw and straw bed depth improved it.
Integrated Systems for Hydrogen Production and Use in Distributed Generation
The aim of the work is to report the object and the preliminary activities of the Italian FISR project on new production and management systems for energy “ Integrated Systems for Hydrogen Production and Use in Distributed Generation”. The most significant research activities deal with hydrogen production from solid fuels (coals as well as biomass fuels, residues and wastes), syngas treatment and separation, hydrogen utilisation in the generation of distributed electricity. Innovative components, technologies and systems are developed in order to minimise the environmental impact and to make competitive the production of hydrogen. The integration of the hydrogen production/separation process with a centralised power plant operating with the same fuel is crucial for the technological and economic feasibility, supplying energy, steam, heat, whereas the residue char can be used as fuel in the combustor. All participants to the project are listed in Table 1.