(644g) Optimization of Flash Carbonization(Tm) Conditions for Charcoal Production from Sunflower Shells
Once again the rapidly escalating price of transportation fuels has engendered intense interest in the production of biodiesel and other liquid fuels from renewable biomass. Biodiesel is an expensive fuel because it is manufactured from vegetable oils. Fortunately the plants that produce vegetable oils often also produce copious lignocellulosic byproducts. For example, in addition to sunflower oil the sunflower plant produces shells, a flower, and a stem. It is often erroneously assumed that these lignocellulosic byproducts have no value. In a visionary paper Varhegyi et al. (Energy & Fuels, 1989, 3, 755-760) described the production of biocarbon (i.e. charcoal) from the sunflower stem. In this paper we detail the effects of process conditions (pressure, air-flow rate, and total air delivery) on the yields and properties of biocarbons that can be derived from the sunflower shell by use of the University of Hawaii's Flash Carbonization? process. This process involves the ignition and control of a flash fire at elevated pressure (ca. 1 MPa) within a packed bed of biomass. The fire moves upward through the bed, against the downward flow of air, triggering the transformation of biomass into gas at elevated pressure, and charcoal with fixed-carbon yields that can reach the thermochemical equilibrium ?limit? in less than 30 min of reaction time. Conditions that offer the highest fixed-carbon yield and greatest biomass throughput are identified. Sunflower shells are an ideal feedstock for biocarbon production by the Flash Carbonization? process. Revenue from the sale of this charcoal can help to lower the price of biodiesel production and make biodiesel a more competitive transportation fuel.