| With the rapid growth of global population and rapid economic development,the problem of freshwater resources is becoming more and more serious.Most of the water resources on earth exist in the form of sea water,but there are very few freshwater resources available for people to use.Seawater desalination technology relax the tension of water resources by reducing the water salinity in order to achieve the purpose of desalination and increasing the total amount of water resources,and fresh water can be produced according to the demand for fresh water,conducive to energy conservation to ensure supply,in order to save energy and ensure supply.In addition,the seawater desalination technology has the advantages of less land occupation,less pollution,good water quality,and a wide range of raw material resources,and can provide a continuous stream of fresh water resources,and the development prospect is huge.LT-MED is characterized by the use of vacuum technology to reduce the boiling point of seawater and concentrated seawater,under the condition of keeping a certain vacuum,the maximum evaporation temperature of seawater is not more than 70?,the corrosion of the equipment and the scaling problem of inorganic salts are greatly reduced.Low operating temperature makes the material requirements of the equipment and the equipment investment cost is reduced.In addition to the first effect evaporator to provide heat source for heating,all the other effects evaporate circularly by the latent heat of secondary steam,thus reducing the energy consumption.It has the advantages of low fouling risk,small power consumption,high thermal efficiency,as well as the advantages of low temperature waste heat from the petrochemical plant or waste heat from low grade steam in the thermal power plant to heat seawater,widely used in engineering practice.Evaporation is the process of separation,the energy consumption of the separation process is relatively large,and accompanied by the production of secondary steam.Therefore,it is great significance to study the energy-saving optimization and effective control in the operation of evaporation.At the same time to ensure that the outlet concentration of end effect reaches the technological requirements,it can reduce the energy consumption and improve the economic benefit by the effective control and optimization of the evaporation system.As a widely used process simulation software in chemical industry,Aspen Plus and gPROMS software can accurately and conveniently realize the calculation and analysisof LT-MED with high efficiency and low temperature in a variety of processes and conditions.Using Aspen Plus to simulate the process of LT-MED,and according to the working environment,data parameters and operating conditions of the actual project in related references,the steady state mathematical model is established.Based on steady state process simulation by Aspen Plus,realizing simulation and optimize control of dynamic process of multi-effect desalination process by gPROMS,analysis of evaporator fouling of continuous system,and change the optimal operating conditions change with scaling,ensure the margin of heat exchangers and other equipment to meet the long cycle of operation to realize the optimal control.The influence of the continuous scaling of evaporator on the system is analyzed,and the optimal operation conditions with the change of scale are changed,and the margin of the heat exchanger is guaranteed to meet the long period operation and realize optimal control. |
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