Min Oh

Numerical analysis of thermal decomposition for RDX, TNT, and Composition B

Demilitarization of waste explosives on a commercial scale has become an important issue in many countries, and this has created a need for research in this area. TNT, RDX and Composition B have been used as military explosives, and they are very sensitive to thermal shock. For the safe waste treatment of these high-energy and highly sensitive explosives, the most plausible candidate suggested has been thermal decomposition in a rotary kiln. This research examines the safe treatment of waste TNT, RDX and Composition B in a rotary kiln type incinerator with regard to suitable operating conditions. Thermal decomposition in this study includes melting, 3 condensed phase reactions in the liquid phase and 263 gas phase reactions. Rigorous mathematical modeling and dynamic simulation for thermal decomposition were carried out for analysis of dynamic behavior in the reactor. The results showed time transient changes of the temperature, components and mass of the explosives and comparisons were made for the 3 explosives. It was concluded that waste explosives subject to heat supplied by hot air at 523.15K were incinerated safely without any thermal detonation.

Surface Design of Separators for Oil/Water Separation with High Separation Capacity and Mechanical Stability

A convection heat treatment that can replace existing chemical oxidation methods was developed for the preparation of hierarchically oxidized Cu meshes with various surface morphologies, representing a very simple and green route that does not involve toxic chemicals. Three types of Cu meshes [bumpy-like (BL) and short and long needle-like (NL) structures] exhibited similar separation efficiencies of 95-99% over 20 separation cycles, as indicated by their similar water contact angles (WCAs; 147-150°). However, these Cu meshes exhibited different flux behaviors. Excessively rough and excessively smooth surfaces of the Cu mesh resulted in increased resistance to flow and to a decrease of the penetration of oil. A surface with intermediate smoothness, such as the BL-Cu mesh, was necessary for high flux over a broad range of oil viscosities. Furthermore, a less rough surface was more suitable for the separation of highly viscous oil. Computational fluid dynamics (CFD) simulations were carried out to support our experimental results. The BL-Cu meshes also showed outstanding mechanical stability because of their low resistance to the flow of fluids.

Simulation of Reaction in a Fluidized Bed Incinerator with Mixing Ratio of Double Based Propellant and Water

Abstract Recently, there have been various studies how to incinerate explosive waste safely due to environmental problems and safety problems. Explosive waste requires a new incineration mechanism, because of the pollution gas generated during the conventional treatment process, such as rotary kiln or outdoor exploration. This study focuses on the fluidized bed incinerator technology which can burn the target material using only a small amount of air at a relatively low temperature condition. In this study, we simulated the process of burning Double Based Propellant (DBP) mixed with water in the incinerator safely. The fluidized bed incinerator was modeled as a cylinder with a diameter of 0.5xa0m and a height of 2.0xa0m, and a case study was carried out by changing the mixing ratio of the injected slurry. As a result, we confirmed the optimal mixing ratio with water for burning DBP without explosion, and confirmed that DBP combustion and decomposition reaction occurring inside the incinerator can be safely simulated. Based on this, it is considered that the design of the actual incinerator will provide a new direction for research on the explosive waste treatment process in Korea in the future.

Modeling and simulation for acrylamide polymerization of super absorbent polymer

In view of the scale up of a batch reactor for super absorbent polymer (SAP), a dynamic mathematical model of a commercial scale batch reactor was developed with mass balance, energy balance, and complex polymerization kinetics. The kinetic parameters of the polymerization were estimated on the basis of the established mathematical model and reference data. Simulation results were validated with less than 10% marginal error compared with reference data. A case study was executed in terms of dynamic simulation for eight different initial concentrations of initiator and monomer to analyze the influence of initial concentration and predict the operation condition for desired product. The results were compared with various reference data, and good agreement was achieved. From the results, we argue that the methodology and results from this study can be used for the scale up of a polymerization batch reactor from the early stage of design.