Experimental study on the scaling law of the heat exchange tube surface in the process of low-temperature single-effect distillation of high-mineralized mine water

Abstract

High-mineralized mine water, due to its characteristics such as high mineralization degree, will have scaling phenomena on the surface of the heat exchange tube during the desalination treatment process, resulting in a reduction in the water production efficiency of the equipment and affecting the normal operation. To reduce the cost of water production and improve the service life of distillation equipment, this paper independently designs and builds a low-temperature single-effect distillation high-mineralized mine water experimental system to study the influence of operating parameters (temperature, spray density, concentration ratio, and system pressure) on the scaling law on the surface of the heat exchange tube. The distribution and characteristics of scale deposits on the surface of the heat exchange tube are analyzed through the growth rate and microscopic morphology of the scale deposit. The results indicate that the scaling on the surface of the titanium plate is mainly in the needle-like and rod-like morphology of CaCO3 aragonite, and a small amount of CaSO4 and calcite are generated with the increase of temperature. It was found that within the range of spray density from 0.0509 kg/(m·s) to 0.0625 kg/(m·s), concentration ratio from 2.3 to 2.7, and system pressure at 36.3 kPa, it is beneficial to the evaporation heat transfer of the heat exchange tube and the reduction of scaling generation. At the same time, it is found that the scaling of the first row of heat exchange tubes is mainly within the range of circumferential angle from 0 to 100 degrees, and the scaling of the second row and the third row of heat exchange tubes is mainly within the range of circumferential angle from 110 to 170 degrees. The research results of this paper provide support for the design and operation of the low-temperature multi-effect treatment system for mine water in engineering, promote the process of zero discharge of high-mineralized mine water in Xinjiang, China, and improve the resource utilization rate of high-mineralized mine water.