| Wastewater incinerator is the most widely used in many types of wastewater incinerator plant, it’s also the core equipment of wastewater incineration technology,and suitable for all kinds of different situations. Wastewater incinerator could deal with all kinds of complex organic wastewater, and has a lot of advantages, such as:high combustion efficiency, adjust temperature speed, the construction cost and maintenance cost is relatively low. But inside the incinerator,combustion reaction is very complex, the temperature is uneven distribution, the flame is too long, NOx emissions is very high, it’s prone to heavy slagging, at the same time, atomization is more difficult,solid-state high suspended solids concentration organic waste liquid treatment the effect not beautiful is a typical problem in engineering practice. With the rapid development of computer hardware and software, we can adopt the method of numerical simulation analysis of the chemical liquid inside the incinerator combustion process and the characteristics of pollutant generating, it also can provide reliable theory basis for optimization of operating chemical waste liquid incinerator in engineering practice.Comprehensive 3D numerical simulation of combustion process of a 10 t·h-1 wastewater incinerator in a petroleum refinery has been performed by FLUENT.Appling the realizable κ-ε turbulent flow equation and the conservation of mass, energy and momentum, chemical composition equation describe the flow and combustion process, choosing the Random Walking Model (RSM) to track waste burning the trajectories of the particles and the influence of transient turbulent pulsation of waste combustion particles;Using local chemical equilibrium of simplified PDF model to simulate the wastewater burning process, and calculating under different mixture fraction beta function of scalar average.In addition, using DPM particle model to simulate atomizing particle distribution of industrial organic wastewater, droplet gasification and droplet internal heat transfer on the influence of heat and mass transfer were considered in the calculation process; Choosing PI model to simulate radiation process inside the furnace; Based on various types of NOx formation mechanism and characteristics of the temperature in the furnace, using thermal NOx, fuel NOx model to simulate the formation of NOx. Through systematical study of the impact of different excess air coefficient and the value of different PA/SA in the wastewater incineration, complicated flow, temperature distribution, pollutant emissions, component concentration distributions and the shape of the flame have been studied. Analyze the toxic and harmful substances in the wastewater of burning /decomposition characteristics in the plant in detail and combine the NOx pollution formation mechanism, fuel NOx, thermal NOx and total NOx formation characteristics has been analyzed in detail, calculation result has good agreement with the measured value. The results show that the excess air coefficient,and value of PA/SA are key factors on the characteristics of pollutants generated, choosing reasonable excess air coefficient and value of PA/SA can increase the combustion efficiency, reduce the pollutant concentration, realize the optimal operation of the chemical wasteater incinerator. |
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