Study On Urea Enrichment,Hydrolysis Law And Physical Properties Simulation In ADC Wastewater

The main pollutants of ADC foaming agent wastewater are high concentration of sodium salt,ammonium salt and high concentration of urea.In this paper,we studied the ADC foaming agent wastewater produced in Wendeng city of Shandong province,and the urea concentration and hydrolysis of urea in the process were studied,and the related properties of NaCl-NH4Cl-H2O system were fitted.The phenomenon of urea enrichment existed in the process of ADC wastewater evaporation.While the production process lack of urea enrichment regularity data.In this paper,we use the method of atmospheric evaporation and evaporation.The difference between the experimental value and the value of the calculation showed that:in the process of evaporation and concentration of urea,urea hydrolyzing with the increase of the evaporation rate.The presence of non-Condensable gases made the heat transfer coefficient greatly decrease during the process of evaporation.The non-Condensable gases of ADC foaming agent were produced by the hydrolysis of urea.Therefore,it was necessary to study the kinetics of hydrolysis of urea.We studied the kinetics of urea hydrolysis to obtain the kinetic parameters(the forward rate constant,reaction order,activation energy and frequency factors)of urea decomposition in aqueous solution,sodium chloride solution,ammonium chloride solution and sodium chloride solution in the mixed electrolyte solution respectively.Conditions are acidic,neutral and alkaline respectively too.The results showed that the conversion rate of urea in acid condition was significantly higher than that in alkaline and neutral conditions.When the temperature is below 80,it is almost non-hydrolysis of urea hydrolysis under acidic,alkaline and neutral conditions.The hydrolysis of urea in the salt contained system is lower than that of the urea solution.In order to obtain the physical properties of NaCl-NH4Cl-H2O system,the experimental study was carried out by using the orthogonal regression method and the experimental results were treated by using multiple linear regression method.The model was established for the estimation of the content of specific heat,electrical conductivity,viscosity,density in the temperature between 20 ? and 80 ?.Through the significance test,obtaining some influence factors on the physical properties.Comparing the model calculated data with experimental data,the relative error of the regression equation of specific heat,viscosity,conductivity and density were 3.996%,2.22%,3.97%,0.781%.