Cyclic Evaporation Treatment Of High Concentration Organic Wastewater Containing Propyl Alcohol

Propanol-containing wastewater is a high-concentration organic wastewater with a high COD content,which is a major problem in wastewater treatment plants.Its main pollutants are propargyl alcohol,butynol,methanol and other byproducts.Proalinol and butynediol are not easily catabolized by microorganisms,and they have inhibitory effects on the growth of sludge.Direct discharge of the near pipe network will cause impact on the operation system of the sewage treatment plant.Therefore,it must be treated before discharge.Since methanol,propynyl alcohol,and 1,4 butynediol are all industrially valuable raw materials,it is assumed that the treatment of propanol-containing waste water by evaporation will not only treat harmful substances in the waste water but also recover industrial raw materials in the waste water.So consider the use of evaporation method for the treatment of propanolcontaining wastewater.Considering that mechanical vapor recompression technology is a relatively high energy-efficient evaporation process in the current evaporation process,this method is adopted in the thesis.Firstly,through analyzing the composition of the wastewater containing propargyl alcohol,an evaporation experiment device was set up to test the effects of different temperatures,vacuum levels,and temperature differences on the concentration of various substances in the effluent.The methanol,propynyl alcohol and 1,4-butynediol were relationship at 4:1:10 ratios.The experiment showed that: at 105℃,the vacuum degree is 0.03 MPa,the temperature difference is 16℃,and the distillation is carried out for 2 hours,the methanol is completely distilled into the evaporating liquid.Only the propargyl alcohol and 1,4-butynediol are concentrated in the concentrated liquid to 20% of the mixed liquid,1,4 butyndiol constitutes 99.5% of the mixture and is effectively concentrated.The existing mechanical vapor recompression system model was used to simulate important components including heat exchangers,evaporation indoor heat exchangers,compressors,and the entire cycle process,and the mechanical vapor recompression system was thermodynamically calculated and analyzed.The calculation and comparison of the system model for the treatment of propanolcontaining wastewater with mechanical steam recompression technology was performed to analyze the thermodynamic properties of the system.The relationship among COP,temperature difference and compression ratio was analyzed and compared.The results showed that the compression ratio was distributed between of 1.8-2.0,the temperature difference was distributed between of 10-16℃,and the system energy utilization rate was distributed between of 7.5-9.Also are analyzed the concentration of 1,4 butynediol concentration,heat transfer temperature difference,evaporation temperature and other factors on the overall performance of mechanical steam recompression system.Mechanical steam recompression treatment of the propanol-containing wastewater system equipment was designed and selected,which mainly includes plate heat exchangers,falling film evaporators and Roots type steam compressors.The heat exchange area of the heat exchanger is 0.23m2,the heat exchange area of the evaporation indoor heat exchanger is 17.2m2,the heat exchange tube size is φ38×2.5mm,and the number of tubes is 100.The effects of the concentration of 1,4-butynediol in the concentrate on the heat exchanger,heat exchanger and compressor were analyzed.The engineering investment costs and operating costs for the treatment of propanol-containing wastewater from a plant using mechanical steam recompression technology was calculated.With a treatment capacity of 12 t/d,the input cost was approximately 1.6382 million yuan,and the wastewater treatment cost was approximately 35 yuan per ton.Yuan provided a reference for the projects of mechanical vapor recompression treatment of wastewater containing propargyl alcohol.