关键词: 机械蒸汽再压缩(MVR), 罗茨风机, 计算流体力学, 数值模拟, 稳定性

Abstract: This research investigated the performances of Roots blower in mechanical vapor recompression (MVR) process by using Fluent software. The three-dimensional unsteady compressible flow field and fluctuation performance of outlet flow, pressure and temperature for involute type three-lobe Roots blowers with air cooling and counter-current cooling and the fluctuation performance of counter-current cooling Roots blowers under different pressure and rotational speed in the MVR system were numerically investigated. The results showed that counter-current cooling Roots blower could avoid the backflow and reduce gas dynamic noise. The flow field uniformity and fluctuation performance of outlet flow, pressure and temperature of counter-current cooling were better than that of air cooling. The outlet temperature and pressure met the design demand of MVR system. In the range of 6.4—19.2kPa, the adiabatic efficiency of counter-current cooling Roots blower was 1.2%—1.7%, higher than air cooling and the comprehensive performances. In addition, counter-current cooling Roots blower was more stable under different pressures and rotational speeds. The outlet flow and temperature could be adjusted to meet operation needs. The flow was adjusted by changing the frequencies of conversion motor speed. The outlet steam temperature was adjusted by changing the pre-inlet steam temperature. The numerical simulation results of outlet temperature for Roots blower with counter-current cooling agreed well with the experimental results.

Key words: mechanical vapor recompression(MVR), Roots blower, computational fluid dynamics, numerical simulation, stability