Gasification of MDF residue in an updraft fixed bed gasifier to produce heat and power via an ORC turbine

Abstract

Biomass, which is a renewable resource, is regarded as an essential energy source due to its accessibility and abundance. In this study, the gasification of wood-based biomass wastes from the medium density fiberboard (MDF) facility was carried out and investigated utilizing an updraft fixed bed gasifier. The feeding capacity of the upstream gasifier is 2100 kg/h. MDF wastes are loaded into the system with feeding capacities of 1500, 1750 and 2100 kg/h. As a reference, the system has also been tested with oak wood chips at a maximum rate of 2100 kg/h. Produced syngas production rate to biomass waste is approximately 2.5 Nm³/kg. The measured gas compositions are CO, CO₂, CH₄, H₂, O₂ and N₂. Test results with 2100 kg/hMDF wastes have similar gas composition compared to the test results with oak wood chips. The quality of the syngas produced by gasification is directly related to the fuel. It has been observed that the efficiency of the gasification process can be directly or indirectly impacted by the properties of the fuel, such as the moisture content, chemical compositions, and size. The temperature of the produced gas is approximately 430 °C, and it isdirectly combusted with tars and soot it contains to ensure that no chemical energy is lost. The thermal gasification system converts approximately 88% by weight of MDF residue to syngas. The calorific value of produced syngas is obtained between 6.0 and 7.0 MJ/Nm³. The hot syngas containing tars produced from the gasifier was directly burned in the thermal oil heater retrofitted to vortex syngas burner to recover thermal energy, which was then utilized in the production of energy via an ORC turbine. The thermal oil heater has a thermal capacity of 7MWh and the power generation capacity of the ORC turbine is 955 kW of electricity.

Keywords: Biomass; Gasification; MDF residue; ORC Turbine; Updraft Gasifier.