A pilot study on a 30 t/h biomass gasification-combustion plant

Abstract

As a renewable energy with zero carbon emission, the utilization of biomass has attracted widely studied. One of the most effective methods is to gasify the biomass into high-quality gas fuel. In the recent years, the majority of research on biomass gasification is conducted in the laboratory. However, it lacks the research in engineering application scale. In this work, a biomass gasification-combustion plant was designed and built to provide the industrial steam with a rate of 30 t/h for a food industrial park. The agricultural and forestry waste biomass was gasified in a gasifier, and then the product gas combusted in a boiler to supply the steam. The characteristics of the product gas from the gasifier were studied. The corrosion and pollutants in the combustion process were investigated. In the gasification process, the main components of the product gas are CO, H₂ and CH₄. CO and H₂ account for 29.55 vol%-30.56 vol% and 11.65 vol%-15.35 vol%, respectively. The calorific value of the product gas is 5.88–6.29 MJ/m³. The tar concentration is 110.58–155.07 g/Nm³. At the outlet of the boiler, the concentration of the filterable particulate matter is 300.25 mg/Nm³, and the particle size is concentrated at 1.00–2.50 μm. The concentration of the condensable particulate matter (CPM) is 157.14 mg/Nm³, and the proportion of water-soluble ions in CPM is 86.36 wt%. The concentration of Cl⁻, SO₄^2-, NH₄⁺ and Na⁺ in CPM is relatively high, with the values of 28.83 mg/Nm³, 10.29 mg/Nm³, 7.46 mg/Nm³, and 5.06 mg/Nm³, respectively. During the half-year running, the ash deposition and corrosion were detected in the boiler heating surface and the economizer. The ash deposit in the boiler is mainly composed of the sulfate and silicate, such as CaSO₄, Zn₂SO₄, Na₂SO₄ and K₃Na(SO₄)₂. The ash deposit in the economizer is primarily composed of the sulfate and a small amount of alkali metal chloride. The flue gas reaches the emission requirement after passing through the pollution control devices and can be discharged into the atmosphere.