Investigation on Tradescantia zebrine (wandering jew) as a resource for Biomass energy production

Abstract

Tradescantiazebrina (TRZE) is readily available and grows rapidly in agricultural farms. It grows well along with other agricultural crops like tea bushes, maize and coffee; however, it is a weed demanding its continuous removal from farms whenever encountered by farmers.This research investigated the potential of Tradescantiazebrina (TRZE) weed plant for bio-fuel energy production. TRZE analysis had the following specific objectives; to harvest, roll, dry, mill and produce pellets from TRZE; determine the energy content in the material; and thirdly, determine the combustion characteristics of TRZE material that form a combustible material. To achieve the stated objectives, TRZE was harvested, sorted, cleaned, rolled, dried, milled, screened, blended and pelletized for combustion property analysis. The combustion characteristics of TRZE were analyzed in an oven and the following data were obtained. Moisture content in (% wt.) of the material from the source had 14.20% with a heating value of 4.49MJ/Kg (using a ballistic bomb calorimeter) while an average of 18.10MJ/Kg was obtained after fitting in energy models from data obtained after oven combustion of compressed pellet particles. The average percentage concentrations by weight of nitrogen, carbon, volatile matter, fixed carbon, ash and moisture content in the TRZE indicates 1.42 (using Kjeldahl method), 50.37, 54.30, 19.22, 16.03 and 10.45 respectively. The values of VM and FC are averagely high, an indication that TRZE material produces heat. The results of moisture content shows that TRZE is within range of other combustible biomass material like coconut shell - 13.95, rice husks - 12.67 and paddy husks - 10.79 (Oladeji, 2010). Determined angle of repose ranged from 30 0 to 50 0 at varying particle sizes. The general stoichiometric formula of CH 1.17 O 0.64 and A/F ratio of 4.63 was determined. For a pellet with an average mass of 15.30grams, the compression ratio (l/2r) decreased as follows 0.54, 0.52, 0.51 and 0.50 over pressure loads of 0.0, 6.89bars, 13.78bars and 20.68bars respectively. In the experiments of durability indices determination by Tumbler method (Oveisi, 2011), 2.0mm particle sizes achieved durability index of 80% for no binder condition at 13.79 bars whileother particle sizes obtained maximum indices of 50% at 13.79 bars for 0.6 mm, 10% at 6.86 bars for 1.18 mm and a no value for 2.36 mm particle sizes at all pressure loads. Only 2.0mm particle sizes obtained 85% durability index at 13.79bars for water bound pellets. Cane molasses bound pellets achieved a durability index of 83% at 20.68 bars for 0.6 mm, 95% at 6.86 bars, 13.79 bars and 20.68 bars for both 1.18 mm and 2mm, while 2.36mm particle sizes achieved 90% index at 6.86 bars, 13.79 bars and 20.68 bars. Comparatively, cane molasses binder produced high quality pellets followed by water binder and least quality pellets when no binder was used. Averagely, 2.00mm particle size performed well in all the three conditioning parameters in a range of 6.86bars to 20.68bars pressure loads. In density versus pressure load experiment, molasses bound pellets’ density were above 700kg/m 3 for all pressure loads applied while the no binder and water bound states achieved density values below 600kg/m 3 . Nevertheless, comprehensibility study curves using Jones (1960) model revealed that 2.36mmparticle sizes are more easily compressed than 1.18mm particle sizes which were least compressible when cane molasses was used as a binder. The TRZE C/N ratio (34.47) was out of the optimum range (20-30) for biogas production. Thus, if Tradescantiazebrina is properly exploited and processed, it could be a good quality and readily available biomass feedstock for heat energy production.