Performance comparison and energy-saving optimization for two DTRO systems in coal mine concentrated brine treatment

Based on the principle of large reflux of concentrated water, two-segments and single-segment DTRO systems were used to treat concentrated brine in coal mine. The performance of the two DTRO was compared under various operating conditions, and the relationship between salt content, recovery rate, operating pressure and output water quality were investigated. The actual operation showed that the operating pressure of two-segments DTRO was 0.7-0.9 MPa lower than that of single-segment DTRO, and the desalination rate was 0.10%-0.15% higher than that of single-segment DTRO. The higher the TDS or recovery rate of the influent, the more advantageous two-segments DTRO process was. The overall operation of the two DTRO systems was stable, running continuously for 3 months without obvious membrane contamination, and the water yield only decreased by about 8%. The water production cost of two-segments DTRO was about 0.3 yuan/m3 lower than that of single-segment DTRO. According to the characteristics of DTRO system, the energy saving optimization strategy was put forward in the aspects of concentrated water circulation, concentrated water energy recovery, circulating pump selection, high pressure pump operation. It provided a positive reference for the long-term stable operation and energy conservation of large-scale DTRO system in the application of concentrated brine treatment in coal mine.