Development of a Mini Single-Tube Biomass Boiler

This paper reports the design and construction of a biomass boiler that can generate steam from locally available wood charcoal. Various parts of the boiler were designed using the ASME standard, and appropriate components for safety and measurement were selected. The boiler tube was a 58 liters capacity cylindrical vessel with hemispherical base with thickness of 6 mm, designed for maximum pressure of 15 bar. After construction, the designed boiler was tested by heating with wood charcoal with intention to identify the boiler response time. The new boiler performed satisfactorily

Conceptual design and preliminary analysis of a CSP-biomass organic Rankine cycle plant

Sequel to the obvious needs to realize sustainable energy systems in the 21st century, energy experts have been working assiduously to mitigate the fluctuating effects of renewable energy sources, thereby facilitating their dispatchability. One of the strategies currently being employed involves hybridizing two or more energy sources and/or systems. In furtherance of this, a concept has been formulated in this article, aimed at the design and preliminary analysis of a 630 kWe CSP-biomass hybrid plant. The system being proposed consists of linear Fresnel (LF) collectors and biomass furnace in parallel, supplying thermal energy input into organic Rankine cycle (ORC) plant. The solar field has been designed alongside a double-tank thermal energy storage (TES) system, using Therminol SP-I as heat transfer fluid (HTF) and sensible heat storage medium. Biomass furnace burning woody crops constantly supplies specified fraction of thermal energy into ORC, to ensure continuous operation of the system. Thus, with dual objectives of avoiding the start-up/shutdown intermittencies and increasing overall dispatchability of the hybrid renewable power plant, a design methodology has been presented, which adopts concepts that depart slightly from the conventional ones available in literature, in the sizing of solar field and TES tank. Considering thermal contributions from biomass furnace, the solar multiple (SM) needed to achieve full load operations of the power plant on a given design summer day was obtained as 1.47. Then, this SM value was used to simulate plant performance over one year, for preliminary energy and economic assessments of the proposed plant. Annual electrical energy production of the ORC was obtained as 2.77 GWh/year, of which solar energy contributes about 34%. The initial investment cost and annual costs were estimated at about 4 M€ and 181 k€/y respectively, leaving levelised cost of energy (LCOE) at about 187 €/MWh. Relative to existing plants within the same power range, it could be affirmed that the presented scheme and design methodology will enhance energy management in isolated and rural regions, especially where high solar irradiation and woody biomass are abundant

Optimal ORC configuration for the combined production of heat and power utilizing solar energy and biomass

This paper aims to investigate the best configuration of an ORC plant for supplying power and useful heat to industrial processes, using solar energy and biomass. In particular, a solar plant based on linear Fresnel collectors integrated with a two-tank Thermal Energy Storage (TES) system and a biomass furnace is considered for the thermal energy production, while an ORC power plant is proposed for the combined production of electricity and useful heat (by recovering waste heat from the condenser). An optimization tool is implemented for the choice of the best ORC layout and cycle conditions with the objective of maximizing its exergy efficiency. System performance are evaluated for several working fluids and different heat demand temperatures by imposing an ORC inlet temperature of 250°C and a desired power output of 630 kW. The results show that the best working fluids belong to siloxanes (in particular the hexamethyldisiloxane), and linear alkanes (Pentane, Iso-Hexane etc.) characterized by high molecular complexity. The exergy efficiency is around 56-58%, but the optimal working fluid varies according to the condenser temperature. Finally, the yearly-based analysis of the hybrid biomass-solar CHP plant highlights the fundamental role of the biomass contribution (about 50% of the overall thermal energy input) for assuring the continuous daytime operation of the ORC unit under nominal conditions