Study Of Small Scale Multi-effect Evaporation Desalination Process With Brine Re-circulation

Water is the basic material to the survival of humans, so water resource is an important index for the sustainable development of a country. The lack of fresh water resources is becoming a global widespread and increasingly serious social problem, which is also restricting the development of social economy. The fresh water problem has become a cause of international conflict, regional conflict and the focus of social panic after the energy problem. China is one of the most serious water shortage countries in the world, and desalination is an important approach to solve the shortage problem. Seawater desalination now draws much attention from the country. China has a long coastline and a large number of islands along the coastal land. Many islands have no fresh water, so fresh water consumption in these islands comes from the rain and transport from inland. These approaches are highly unstable and expensive. Desalination technology will provide new important freshwater sources for these islands. Besides, ships away from the mainland need to carry fresh water or acquire fresh water by using seawater desalination, and large ocean-going vessels currently also adopt desalination. China has become a major country of shipbuilding, but efficient marine fresh water generators still depend on the import, also China is still lack of independent ability of desalination device design and manufacturing at present. Such problems are not compatible with the country’s shipbuilding power, which is significantly reducing the country shipbuilding industry profits space and is disadvantageous to the country’s shipbuilding benefit. Based on the above background, this work proposes a small-scale marine multi-effect desalination system with brine circulation. This system uses the waste heat from the ship power as the heat resource. It has the advantages of compact structure, good adaptability with islands, ocean-going vessels and big ships. The main contents are listed as follow:1. Conduct the thermodynamic calculation of the low temperature multi-effect desalination system. The influences of effects of evaporator/condensers, the seawater technological process and the brine technological process to the performance of desalination plant are analyzed2. An innovative multi-effect desalination system with brine circulation was proposed for a 50T/d marine fresh water generator. Its performance parameters was computed and compared with regular technological process. The advantages of brine circulation system are summarized.3. The structural design analysis of the 50T/d marine multi-effect desalination equipment. was conducted.