Successful demonstration of biomass gasification for hydrogen generation using local resources will bring a new generation of small-scale biomass residue power plants much closer to technical and economic reality. Data from the project will be used to ascertain the viability of a biomass gasification plant to address the long-term hydrogen needs of KSC (and CCAFS).

Furthermore, the development of the new technology will help the local economy by developing a market for the citrus peel, a waste byproduct of citrus processing, and by generating jobs associated with power production.

Data from the project will be used to ascertain the viability of biomass gasification plant to provide for the long- term NASA KSC hydrogen needs. Local production of hydrogen will secure a renewable and environmentally friendly fuel for the spaceport operations, Furthermore, the development of the new technology will help the local economy by generating jobs associated with power production. As a renewable energy source, biomass derived hydrogen offers an alternative to conventional energy sources and provides environmental, rural economic growth, and national energy security benefits.

Ultimate and Proximate Analysis of the Citrus Pellets. The citrus peels pellets were obtained from Citrus World Inc. in Lake Wales, FL. Citrus World, Inc. is one of the largest producers for Citrus products in the US. The citrus pellets are used for the cattle feed. The citrus pellets have approximately 14% (wt.) moisture content. The peels show an equivalent amount of Hydrogen that is present in wood chips. The ultimate analysis does show trace amounts of Sulfur that may have to be dealt with the downstream side of the gasifier.

The elemental analysis (Table 2) on ash revealed the following metals. Sodium, Potassium, Calcium, Magnesium, and Silicon are the major elements found in ash. Solid wastes generated will be subject to the state of Florida leaching tests and will need to be certified as nonhazardous. We plan to carry out the leaching tests once the pilot-scale gasifier is operational so that the ash can be certified and can be disposed of using conventional methods.

Using the elemental analysis and a gasifier model developed by researchers from Biomass Gasification Group (BGG) of the Department of Mechanical Engineering at the Technical University of Denmark was used to carry out preliminary simulations.1 The gasifier model assumes a downdraft type gasifier with air and steam as gasification agents. The schematic of the gasifier is shown in Fig. 1.

The model is based on mass and energy balances and chemical equilibrium and does not take into account the reaction kinetics and/or mass transport. As such, its use is limited to first approximations only. Some of the results are summarized in appendix A. We also tried to use ASPEN Plus for the simulation. However, since FIU does not have a chemical engineering program the procurement of the software was cost prohibitive given the budgetary constraints. We plan to use the expertise of UCF researchers led by Dr. Ali Raissi for ASPEN simulations once we have data from the pilot-scale gasifier.

The pilot-scale gasifier will generate dry producer gas from palletized orange-skins. The system is designed for 30 Nm3/hr of producer gas using a positive displacement blower for motive force on the gasifier. The system is skid mounted including the pellet feeder, gasifier, heat exchangers, gas cleanup, and the control module. The system also includes a flare system and the control system uses off-the-shelf PLC platform.

The gasifier is a two stage fixed bed downdraft gasifier. Citrus peels will be fed through the top of the gasifier and is converted to char and then char ash within the central core of the gasifier. Char and char ash is supported by a grate that is vibrated periodically to clear the buildup. Some of the ash also gets entrained in the exiting gas that is cleaned downstream of the gasifier. Air is also fed at the top of the gasifier and helps in breaking down the biomass. Air is also fed at the bottom of the gasifier to help combust the char to form hydrogen and carbon
monoxide. The gasifier has five strategically placed thermocouples and a differential pressure gauge to measure the pressure drop across the char bed. Detail gasifier specifications are shown in Appendix B.