Papers by Keyword: Multi-Effect Distillation

Abstract: The advantages and disadvantages of the conventional desalination methods were discussed. A four-effect desalination demonstration plant using waste heat from a diesel engine was designed. Not only the water yield but also the physical dimension of the distiller has been calculated under the operating condition. The analysis of energy consumption shows that the desalination system is low-cost.

Abstract: The multi-effect distillation (MED) process is one of the oldest process in desalination of seawater. This technology has been used for water and heat recovery from the petroleum waste in Liaohe Oilfield. However, the scale formation is one of the main problems that encountered in the operation of different plants. The temperature of the first stage of the MED evaporation is higher than 138 °C. Therefore, both the scale inhibition and removal technologies should be adopted. The Belgard EV 2050 scale inhibitor produced by Ciba-Geigy is recommended to be used to inhibit the scale due to the excellent scale inhibiting performance. Scale removal technology also needs to be adopted regularly for device descaling in addition to the scale controlling technology. The sulfamic acid (concentration of 5% -10%) can be selected as the acid cleaning agent with a certain amount of inhibitor added.

Abstract: The relation curve of the raw water flow and main steam pressure under different main stream temperature is established by off-line experiments and expert experiences. For the time-varying in heat conduction coefficient, which is resulted by scaling and so on, water level need to be detected by installing float level gauge in every effect, and the curve can be corrected according to water level, so effective separation space of gas and water is ensured to avoid dry or flood pot. Because medical water distiller need to provide pure steam, by detecting the output flow of pure steam, correct the curve and inhibit the interference of production process due to pure steam output, then the production process of distilled water can be finished by automatically controlling the adjustable valves of raw water flow and main stream pressure. The method will improve the robustness of heat conduction coefficient time-varying and pure steam output interference.

Abstract: The treatment of high salinity wastewater treatment in refinery has been widely noticed due to more and more stringent laws and regulations. In the paper, in order to deal with the high salinity wastewater efficiently, a MED process was performed, and mathematical modeling was established to discuss the effect of feed steam on MED dealing with high-salinity wastewater. The results indicated that the temperature of steam produced by different low-temperature heat and pressures of the steam could all affect the MED system obviously. For example, the mass of pure water increased slightly with the increase of feed steam temperature in 3 effects system. With the same pressure feed steam, more mass of pure water was produced by fewer effects system, etc. This paper would provide a very useful reference for the high-salinity wastewater reduction via MED process in petroleum refinery.

Abstract: This paper presents the thermal performance of a multi-effect distillation (MED) solar desalination unit located in southern China. The system was designed and installed in April 2011, and has been in operation since that time till now. The seawater desalination system is driven by 60 m² all-glass vacuum tubes solar collector with an additional rainwater utilization system to produce fresh water on both sunny and rainy days. The preliminary experimental results show that the water production of the system for per unit of solar collector area could reach up to more than 12.5kg/m²·day under the fine weather conditions. Water production of the system was stable in long period and the annual production could reach to 387.5 m³ in southern China. The economic performance of the system is also discussed. The cost of water production is estimated approximately 4.15 $/m³ for the 15-year service life.