Study On Thermodynamics Properties Of Biomass-oil And Key Problems In Spray Condensation Of Biomass Pyrolysis Gas

Effective use of biomass energy has important strategic significance for sustainable development of our economy and society. Biomass pyrolysis technology is most likely the first to achieve commercial application in all the biomass production of high quality liquid fuel technology path. In this process, rapid condensation of biomass pyrolysis gas is one of the key factors of the biomass-oil quality and yield. Biomass-oil condensation process is very complex. Water ratio is 25% to 30% of the total weight, the rest are mainly oxygenated organic compounds. Biomass-oil presents strong polarity. Multi-component condensation in a temperature range is different from pure substances with a single condensing temperature. As the temperature is not the same, the composition of liquid and gas is very different. This article is aimed at key problems in rapid condensation of high-temperature biomass pyrolysis gas.A measuring device using novel thermal probe method based on a Monte Carlo stochastic approximation was established. The thermal conductivity and specific heat capacity value of biomass-oil at different temperatures and with different additive were measured by this device.Prediction models for thermodynamics properties of biomass-oil and vapor-liquid phase equilibrium were presented respectively by using Pseudo-components method and Continuous Thermodynamics method on the basis of true boiling point distillation curve. Because the model assumed all the boiling range fractions as pseudo n-alkanes, but the real mixture contains a lot of water, the precision of forecasting is unsatisfactory. Continuous thermodynamics been proven has better advantages in the application of multi-component complex system. A modify model was established based on Continuous Thermodynamics. We estimated the thermal properties of biomass-oil under different temperature and phase equilibrium properties, also the effects caused by initial quality of the water in the system and additive. Compared with experimental values, Prediction was good.Spray condensation is a very effective way to bring it out.The coupled heat and mass transfer characteristics in the spray condensation of the multi-component system,composed of the key components of biomass pyrolysis gas,were studied in this paper.To describe the heat and mass transfer of multi-component system,the classic film model and the Maxwell-Stefan Equation were used combined with gas-liquid inter-phase mass transfer characteristics.Variation of droplet diameter,average temperature of droplet and mixed gas were derived.And we also analysed the effect caused by the initial velocity,the diameter of the droplet and the flow ratio of the gas and liquid in the progress of the biomass pyrolysis gas condensation.