In recent years, with the development of industry and the expansion of urban scale, the increasing shortage of water resources has become a prominent problem restricting the development of human society. In addition to advocating water conservation, wastewater purification and recycling, seawater desalination is one of the best ways to solve the problem of water shortage. Up to now, seawater desalination technology has been used in more than 120 countries and regions around the world. According to relevant statistics, there are now more than 13,000 desalination plants in the world, which can desalinate 35 million tons of seawater a day, and the annual growth rate is more than 10%.
Now commonly used desalination processes are: reverse osmosis method (filtration method), solar energy method, low temperature multi-effect distillation technology, multi-stage flash method, electrodialysis method, pressure gas distillation, dew point evaporation method, water and electricity cogeneration method, hot film cogeneration method, at the same time there are unpressurized osmosis adsorption method and other new technologies. Among these methods, multistage flash distillation, low temperature multi-effect distillation and reverse osmosis are the main methods. China mainly uses low-temperature multi-effect distillation and reverse osmosis, it is reported that in the next few years, there will be a number of desalination projects.
After more than 40 years of study, the seawater desalination technology is becoming more mature in our country, the large-scale application of seawater desalination already has the cost advantage, and the cost is lower compared with the South water diversion project. At the same time, the government has introduced a series of incentives, the next 10 years will be five times the size of the current desalination.
In addition, titanium tubes in seawater desalination equipment will gradually replace the original copper alloy tubes. Compared with the two, titanium tubes have the following advantages:
1. First of all, compared with copper alloy tube, the wall thickness of titanium tube is thinner and the amount of pipe is less.
2, titanium thermal conductivity is 17W/(m·k), low thermal conductivity, good thermal conductivity.
3, the use of titanium tube more cost-effective. The price of titanium tube can compete with that of copper alloy tube. Due to the low density of titanium and the same wall thickness, the quality of titanium tube of the same length is only 50% of that of copper alloy tube. When the wall thickness of titanium tube is 50% of that of copper alloy tube, the quality of titanium tube with the same heat transfer area is only 1/4 of that of copper alloy tube. Visible, titanium tube is competitive in price.
4. The service life of titanium tube is longer. Because seawater is often mixed with sediment and Marine organisms, they adhere to the heat transfer pipe and pipe end, will erode the copper alloy pipe, copper alloy will also be corroded by BR-in seawater. Titanium tubes do not have this problem, especially in order to kill bacteria in seawater, have to inject oxygen, more need to use good corrosion resistance titanium tubes.
