Experimental investigation of a novel batch evaporation system coupled mechanical vapor recompression technology and steam heat storage technology

Abstract

In order to address the high energy consumption and low efficiency in batched food evaporation industry, such as beer boiling, lactose crystallization, drug concentration, a novel batched mechanical vapor recompression evaporation device coupled the heat storage technology and mechanical vapor recompression technology was assembled to capture and reuse the waste heat from secondary steam and reduce the water consumption. The relevant key parameters affecting the overall performance were investigated and analyzed, including evaporation temperature, interval time, startup time and compressor frequency. In a practical sense, the thermodynamic, economic, as well as the environmental performance of the proposed system was compared with the previous single-effect evaporation technology. Experimental results exhibited that the proposed system could accomplish efficient batch evaporation process at specific interval time with only a small amount of electricity, as the temperature loss of steam accumulator was approximately 1 °C. It was found that the evaporation temperature was a positive factor for the overall performance of the system, while the startup time of the whole system showed an opposite effect, subject to the startup time of the steam compressor. Furthermore, it was highlighted that the evaporation capacity of novel system was very sensitive to compressor frequency, while a minimum value of 64.5 kWht−1 for specific heating energy consumption emerged at f = 65 Hz. Therefore, the operating cost and standard coal consumption could be saved by 85.26% and 83.66% compared to the single-effect evaporation technology, respectively, which demonstrated the significant superiority of the proposed method in economic and environmental benefits in batch evaporation industry.