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Simulation of Hydrocarbon Waste-gas Combustion in Incinerator and Pollution Control

Modarres, Mohammad Reza | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46263 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Masoud
  7. Abstract:
  8. Emission control, especially Carbon Monoxides (CO) as one of the major by-products of combustion processes, is one of the most serious challenges in burning waste-gases with high amounts of humidity and Carbon Monoxide. We investigated an oil waste-gas incinerator serving to a bitumen production line located in Pasargad Oil Company, Shazand, Arak, Iran. The aforementioned incinerator was criticized seriously for its high CO emissions. We were requested to find a solution to reduce the undesirable CO emission from that. Following the environmental standards, there is an upper limit of 150 ppm for the CO produced by an industrial waste oil incinerator. To present an inclusive solution for such high pollution production, we used a commercial computational fluid dynamics tool and simulated the combustion process through the current incinerator. We defined the mixture fraction standard deviation as an index to evaluate the mixing performance within the incinerator and the amount of produced pollution. This parameter and the chemical species residence time were considered as the two most important parameters, which could let us evaluate the combustion quality more explicitly. In order to decrease the amount of pollutants from the waste-gas incinerator, we studied the effects of different waste-gas inlets to the incinerator. In this regard, the main waste-gas inlet was transferred from its original position to a position near the bottom face of incinerator. Such inlets were tangential to the incinerator. The results of our numerical studies showed that the inlets with a width-to-length ratio larger than unity would have noticeable effects on reducing the CO emission. Indeed, our new inlets resulted in a homogeneous mixing of species and consequently a suitable CO emission due to a homogeneous temperature distribution around the main axis of incinerator. Our evidences showed that the CO emission could reduce to 150 ppm, which is really much lower than its original amount, i.e., about 2000 ppm.
    As an additional task, we decided to study the current combusting flow problem using the chemical reactor network (CRN) model. To simplify the main 3D incinerator, we carried out our study using two simple 2D incinerator shapes. The results of CRN modeling were eventually combined with each other. The results showed that the preceding combustion modeling would have been able to predict the amounts of combustion species very reliably. Evidently, the CRN model could provide more accurate results if we were able to model the incinerator in its full 3D shape
  9. Keywords:
  10. Mixing ; Carbon Monoxide ; Chemical Kinetic ; Reactor Network ; Pollution Control ; Chemical Reactors ; Incinerator ; Combustion Simulation

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