Research On The Energy Saving Of Recovering Dmf From Wastewater By Distillation

N, N-dimethylformamide (DMF) is a good organic solvent and chemical synthesis material. It has been widely used in polyurethane synthetic leather、fibre spinning、pharmaceutical industries、pesticide、petrochemical industries and so on.These industries always produce much DMF wastewater. However, DMF is toxic and can do serious harm to the environment and human health. What is more, DMF wastewater discharge results in great economic loss. In order to achieve green production and improve the economic benefit, it is necessary to recover DMF from wastewater. At present, the main way of recovering DMF is distillation. But the recovery of DMF by distillation consumes huge energy. And it is urgent to change it in an era of energy crisis.This paper applies the energy-saving technology of heat pump to the DMF recovery process. And the heat network is developed based on pinch technology.The main contributions of this thesis could be summarized as follows:A vacuum distillation experiment is conducted to recover DMF from the wastewater. In the experiment, Gas Chromatography and Karl Fischer method are respectively applied to determine the DMF and water content in mixture. The operating condition meeting the requirement of recovering DMF is obtained and the experimental results provide a basis for the process simulation.The experiment is simulated by Aspen Plus and it is investigated that the simulating results are credible by comparing the experimental results and the simulating results. And the results show that the simulation results are in agreement with the experimental result. According the characteristic of DMF recovery by distillation, the paper comes up with a three-column process and uses Aspen Plus to excute process calculation. The calculation results contains processing parameters、 stream data、heat duty.Based on the calculation results of the three-column process, the pinch technology is used to design the energy-saving heat network. The difference in temperature at pinch point is optimized, and the composite curve at pinch point is obtained. Then the principle of pinch technology is used to conduct the heat pump intergration. Finally, the thesis obtains the three-column heat pump process, which reduces energy consumption a lot compared with current processes.