| The large number of high concentration salt water produced in industrial production will cause great pollution to water resources,and then cause serious environmental problems,and the lack of fresh water resources has also caused a series of sharp social problems.For this reason,the need for saline water desalination processing,in order to realize the recycling of water resources and solve the problem of shortage of fresh water.Due to the increased demand for freshwater,around the world are in a sustainable way for water recycle,to protect water resources.The direct discharge of saline wastewater will not only destroy the ecological environment,but also cause great harm to human body.If large quantities of seawater and salt water from salt lakes are properly treated,it can effectively supplement fresh water resources and bring both environmental and economic benefits.Therefore,it is necessary to research and develop the treatment method of salt-containing wastewater with high efficiency,energy saving and low operating cost.Electrodialysis technology was originally used to desalinate seawater,but it is now widely used to desalinate salt water and is the main method of producing fresh water in some parts of the world.At the same time,electrodialysis technology is also an economical and efficient desalination process,which can significantly reduce the ion concentration in wastewater.The concentration of concentrated brine in electrodialysis is also much higher than in reverse osmosis because there is no osmotic pressure limit;electrodialysis has the advantage of lower energy consumption compared to distillation processes.Multi-effect evaporation technology plays an important role in various seawater desalination,wastewater treatment and solution concentration,food industry and so on,and has become a relatively mature water treatment method.And multi-effect evaporation has the advantages of high heat transfer coefficient,less power consumption,low operating temperature,and low requirements for the feeding of saline wastewater.Reusing the natural renewable energy-solar energy to process salt water can not only significantly improve the treatment efficiency and save energy,but also effectively reduce the consumption of fossil energy,so it is an environmentally friendly and economical way to produce fresh water.Most seawater desalination and high-salt wastewater desalination systems can use thermal energy directly,and CPC collectors are very suitable for salt water treatment.In related processes,since solar energy can be used directly,CPC solar energy can be used for power generation,heating and cooling,so as to achieve the purpose of desalination and production of fresh water.In this experiment,electrodialysis,multi-effect evaporation and CPC collector were used for process coupling treatment of high-salt wastewater,and the sequence of multi-effect evaporator and electrodialysis was adjusted:(1)CPC collector,electrodialysis,multi-effect evaporation process.Then,based on the control and simulation technology of COMSOL Multiphysics,a simulation model was established for the electrodialysis system in the high salt water treatment process,and the simulation analysis and calculation and process optimization research were carried out.(2)CPC collector,multi-effect evaporation,electrodialysis process.The COMSOL Multiphysics control simulation technology is also used to establish a simulation model for the electrodialysis system in the high salt water treatment process,and the simulation analysis calculation and process optimization research are carried out.Among them,the CPC solar collector provides the required steam for the multi-effect evaporator in the high-salt wastewater treatment process.After the steam is used by the multi-effect evaporator,the steam containing waste heat is heated by the CPC collector again through the heat exchanger and supplied to the multi-effect evaporator.The steam waste heat remaining after the multi-effect evaporation treatment is recycled,which not only improves the work efficiency but also effectively reduces the cost.High salt water with a mass fraction of 3.7%NaCl and an initial concentration of 700mol/m~3 is first configured:(1)The high salt water with initial concentration is pretreated by filters,degassing heaters and microfilters.After the concentration treatment of electrodialysis system,the concentration is 1900mol/m~3,the mass fraction of NaCl is 9.8%.Finally,the concentration is 5647 mol/m~3 and the mass fraction of NaCl is 28%after further concentration treatment by three-effect evaporator.(2)The high salt water with initial concentration is pretreated by filters,degassing heaters and microfilters.After dealing with the three effect evaporator to concentrate again concentration to 2100 mol/m~3,NaCl mass fraction is 13%.Finally,the concentration reached 4000 mol/m~3 after further concentration treatment by electrodialysis system,and the mass fraction of NaCl was 21.7%. |
