The Pilot Apparatus Research On Low-temperature Multi-effect Distillation

Low-temperature multi-effect distillation (LT-MED) has been one kind of main commercial seawater desalination technology, which is due to the high purity of potable water, the simplicity of apparatus, the independence on the salt concentration of raw seawater and the easy pretreatment. At present, LT-MED plant is usually established nearby the seashore power plant, which has become the preferred method for most countries to set up large-scale seawater desalination plant. The advantages of this combination are based on the following fact: the cheap low-grade steam that is produced in the power plant, is very suitable for LT-MED plant to produce fresh water; such production water can be provided to the power plant itself, chemical factory and petrochemical plant, which is more efficient than the deep treatment of tap water; in addition the desalted water also can be supply for the coastal cities. So the combination of LT-MED and power plant is helpful to decrease the total cost.Because the freshwater is highly stress in the coastal cities, the Department of Science and Technology decided to develop the LT-MED technology with our own intellectual property rights during the tenth Five-year Plan period, so establishing a set of LT-MED seawater desalination demonstrative project was included in the State Key Scientific & Technological Project, which greatly push the development of seawater desalination industrialization. In 2002, the Institute of Seawater Desalination & Multi-purpose Utilization, SOA (Tianjin) and Qingdao Hua'ou Group decided to built up 3000 t/d LT-MED seawater desalination demonstrative project at Huangdao Power Plant.This is the first large-scale LT-MED seawater desalination apparatus in China, so the two sides decided to first set up 60 t/d low-temperature double effect mechanical vapor compression (MVC) apparatus which was regarded as a pilot experimental apparatus for the demonstrative project. During the design, setup and operation, some engineering problem that we didn't master at now were dissolved, and these experiences were helpful for the demonstrative project.In this paper, the basic experiments, the design and fabrication of apparatus and the operation and test of this pilot apparatus were described. The detailed researches are:...