540 / 2018-09-25 19:33:47

Influence of Non-condensable Gases on the Condensation Characteristic of Pyrolysis Oil Simulants Vapor

生物质多联产 > 生物质多联产

In present work, water, acetic acid and furfuryl alcohol are selected as pyrolysis oil simulants. N2, CO2 and synthetic pyrolysis gas are selected as non-condensable gases (NCG). The effects of NCG content and types on the condensation characteristics of different simulants are investigated. The mixed feeding was heated to vaporized steam and passed through the indirect vertical condenser to collect the liquid. Temperature data was monitored and Boltzmann model fitting was performed to calculate the local heat flux and local heat transfer coefficient (LHTC). The result shows that, the LHTC of the three simulants vapor condensation without NCG is much higher. When the NCG are imported, the maximum LHTC drops significantly and the synthetic pyrolysis gas is the worse for the condensation with the average LHTC arrangement from large to small: CO2 >N2 >synthetic pyrolysis gas, CO2 has relatively little effect on the simulants vapor condensation. Meanwhile, the LHTC of water has the minimal reduction and acetic acid has maximum, the effect of NCG on acetic acid vapor condensation is even worse. As the NCG content increases, the peak value of all simulants vapor condensation LHTC decreases. The effective condensation section moves down gradually, the lower half is relatively better than first half. The NCG forms a diffusion layer thermal resistance between the tube wall and condensable vapor, which reduces the contact heat conduction, moreover, the increased NCG content shortens effective condensation tube process, so the heat transfer effect is obviously deteriorated, efficient condensation is difficult to achieve. Through this study, the improved design of the efficient condenser can be performed according to the NCG condensation characteristics in the pyrolysis volatiles.