Incineration Of Salty Aniline Wastewater And Corrosion Behavior Of Molten Salt

As an efficient and viable wastewater treatment, more and more attention hasbeen paid on wastewater incineration, while little research has been done on if itwas economy or reasonable for wastewater to incineration. The organic saltywastewater with high concentration can cause the incinerator agglomeration anddefluidization in the incineration process, so as the corrosion of the furnacematerial. This thesis studied on the pretreatment process of salty aniline wastewaterby distillation before incineration, then discussed its combustion dynamics,finally analyzed the corrosion behaviors of metal materials by molten salt at hightemperature. It has provided a basic research for the incineration of wastewaterwith organic salty wastewater and the design of wastewater incinerator.1. It requires generally a lot of auxiliary fuel to incinerate the salty anilinewastewater. The presence of alkali metal salt species， which was inclined toagglomeration and defluidization on the interior fluidized bed incinerator, wouldreduce the combusting efficiency of fluidized bed. It was firstly studied thepretreatment process of salty aniline wastewater by distillation before incinerationin the present thesis. The results showed that the ratio of COD removal and theorganic precipitation ratio were related to the initial mass concentration of NaCl.The COD removal ratio reached the highest value when the initial concentration ofNaCl was20000mg/L; The organic precipitation ratio increased with the additionof initial NaCl concentration, the organic precipitation ratio could reach at48%when the initial NaCl concentration was40000mg/L, then no longer changehappened; The desalination ratio of wastewater reached at98%stably duringdistillation process. Both ions of sodium and chlorine were separated out not withsodium chloride but with ion-state during distillation process.2. It was measured the heat value and COD value of the aniline wastewater.Found that even the moisture content reached at50%, the COD value of thewastewater has always been more than5×10~5mg/L and the heat value was above3.2×10~4J/g, the result showed that the wastewater still suitable for incineration.3. It was analysed the single aniline wastewater, the aniline-diesel wastewaterand the aniline-biodiesel wastewater by means of TG-DTG, found that the ignitiontemperature of the three solutions was about150℃. Used the first-order dynamicsmodel to simulate the thermal degradation process of single aniline wastewater and aniline-diesel wastewater, the result showed that the thermal degradation process ofsingle aniline wastewater in air was generally divided into two stages: theevaporation of moisture and the combustion of the remained components, while thethermal degradation process of single aniline wastewater in nitrogen was mainlydivided into two stages: the evaporation of moisture and the combustion of theremained components. After fitted the data which got at the two kinds ofatmosphere, we got a correlation coefficient r≥0.9, it suggested that thehypothesis: single aniline wastewater was first-order reaction, was substantiated.The thermal degradation process of aniline-diesel wastewater in air was generallydivided into three stages, while the apparent activation energy at combustion stagewas the largest, the thermal degradation process of aniline-diesel wastewater innitrogen was mainly divided into two stages: the evaporation of small moleculesand moisture, the pyrolysis of the remained components. Used the first-orderdynamics model to simulate the thermal degradation process of aniline-dieselwastewater, after fitted all data points, it got a correlation coefficient r≥0.8,which showed a good correlativity.4. Although the salty aniline wastewater was pretreated by distillation, therewere still remained salts in the solution, which would corrode the furnace material.Finally, the effect of molten salt on the corrosion behaviors of cast iron wasinvestigated at high temperature. It was concluded that the corrosion degree of thespecimens was proportional to the test temperature and duration, and the saltcontent. It was also found that adding kaolin could effectively reduce the corrosionof cast iron and different corrosive medium would lead to the variable surfacemorphologies resulted from corrosion by means of EDS and XRD. The componentof the oxide film was mainly Fe2O3on the surface of Fe specimen.