| In this thesis, the performances of the evaporating water tower using fixed-valve trays were discussed. Evaporating hot water tower is the key equipment to recover the heat from steams in slag water system. A new type of fixed-valve tray with simple structure and high transfer efficiency was considered to be used in the evaporating hot water tower to replace the packed tower currently used in industrial application which would be filled with ash carried by the steam after long running.Heat and mass transfer experiments with new fixed-valve tray were carried in the hot mode devices to study direct contact heat exchange process. The gas temperature distribution along the tower was obtained to determine the suitable gas-liquid operation conditions. Contrasted on experimental results of packed tower and plate tower, plate tower had larger liquid load range than packed tower. The best condensate water flow rate of packing tower was7.6while that of plate tower was6-8. The heat and mass transfer effect of fixed-valve trays was better than that of sieve trays.The hydrodynamic characteristics of gas-liquid two-phase countercurrent flow was studied in the newly built experimental equipments. Wet and dry plate pressure drop was measured using a micro-pressure sensor. The effect of different gas flow rate, spraying density and weir height was discussed. A double sensor probe was used to measure local interfacial parameters such as void fraction and bubble size. The experimental results was discussed to give reference to optimize and perfect the design of hot water tower and provide theoretical basis for the industrial application.Different fixed-valve trays were used in experiments to discuss the impact of hole diameter, hole pitch and opening ration on the heat and mass transfer process. The relation of transfer units for liquid phase and kinetic energy parameter was established and correlation equation was deduced to guide the design of fixed-valve tray. |
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