Pilot test of a 30 t·d-1 desalination device with multi-effect and operated at low temperature by evaporating seawater

In this paper, pilot test was carried out on a 30 t·d-1 desalination device with multi-effect and operated at low temperature by evaporation of seawater, which was designed and constructed in the earlier phase of a project. Using the results obtained, the relationships between various key parameters, including motive steam, operating maximum temperature, temperature difference, spray density, extraction method of non-condensing gas, flow of steam ejector, gained output ratio, and product conductivity, were analyzed. Based on these test results, the conclusions drawn are as follows: (1)device stability, productivity of water and GOR are strongly affected by the fluctuation of motive steam pressure; (2)temperature difference by optimal design of heat transfer is about 3°C, and the spray density between 240 L·(m·h)-1 and 300 L·(m·h)-1 in desalination; (3)Water productivity increases by 3.64% when vacuum pump is operated from parallel mode changing to series mode; (4)application of thermal vapor compressor(TVC)can increase water productivity and gained output ratio(GOR), at the same time can reduce system energy consumption. If the deviation between real running conditions and design value of the parameters was ≥20%, the injecting ratio will be reduced. The results obtained in this paper can be as a knowledge accumulation and design basis for design of large-scale, low-temperature, multi-effect seawater desalination devices. © All Rights Reserved.