The design of a dynamic simulation system of a liquid chemical filling process
The flow sheet and operation principle of a liquid filling process was briefly discussed, and the dynamic simulation mathematic models of the filling process were developed in detail using the mass balance equations, gas state equations and historical process data. Based on the intelligent process control (IPC) simulation mode, the overall structure and the development scheme of the filling process simulation system was designed. A dynamic simulation system of the filling process was successfully developed, by taking a typical SCADA (supervisory control and data acquisition) configuration software named Century Star as GUI (graphical user interface) development platform, and integrating with a DLL (dynamic link library) function program to perform the calculation of the simulation models programmed using Visual C++. The development of the simulation GUI included the design and Command Language programming of simulated process flow sheet diagrams, simulation command buttons and their displaying diagrams, and the operation and parameters adjustment diagrams of all kinds of manipulators in the process flow sheets. The overall simulation operation of the filling process was fairly good achieved. Then some comprehensive and systematic simulation tests of the filling process were carried out. The simulation results show that the simulation system could satisfy the filling process research and design requirements very well, and the main process operation parameters were optimized through these simulation tests.
Development of a fine chemical process operator-training simulator
Fine chemical processes usually are very complex, and their operations are heavy and complicated. The success operations of fine chemical processes require high skill operators. As there are lots of limitations to use real fine chemical production plants to train operators, we need to develop process operation simulation training system to train process operators. However, the traditional development methods of process operation simulation training system are inconvenient due to their poor modularity, so new development strategies of process operation simulation training system with high efficiency should be studied. In this paper, a new Supervisory Control and Data Acquisition (SCADA) simulation-mode is put forward according to the operation training characteristics of fine chemical production processes. The SCADA mode process simulation system is developed using SCADA software to design graphical user interface (GUI), and integrating with simulation models built by the combination of process mechanics modeling method and dynamic compensation modeling method through the design of a kind of dynamic link library (DLL) function. The SCADA mode process simulation system is more modularized; and it can be more conveniently developed than the traditional process simulation system. The SCADA mode training simulator is successfully applied to the simulation operation training of a fine chemical production process. The training results show that the simulation operation of the SCADA mode training simulator is vivid and it is very similar to the operation of the real plant. The SCADA mode training simulator satisfies the process training requirements quite well, and the operation training effect and efficiency is highly improved.
Neutron Residual Stress Measurements on Rail Sections for Different Production Conditions
Rail sectioning with subsequent neutron diffraction experiments has been used to assess residual stresses in the rails. In this study we present the results of neutron stress measurements performed at the NIST Center for Neutron Research (NCNR) on rail sections from rails that were produced under various conditions. Specifically, these are air-cooled, air-cooled and roller-straightened, head-hardened and head-hardened and roller-straightened. More significantly, a head-hardened and roller-straightened rail was also studied after service to elucidate evolution of the service-induced residual stresses. In the latter case both a transverse-cut slice and the central region of a 0.53 m long piece were studied. Measurements on this piece are the first in which triaxial stresses have been determined for an intact rail. Neutron strain measurements with 3×3×3 mm3 spatial resolution were successfully employed for transversally cut slices to verify the difference in the stress state depending on the production process. Although examination of slices allows determination of only two-dimensional stresses in the plane of the slice, additional measurements on obliquely-cut slices, which were also carried out, and utilization of FEM gives the possibility of reconstructing the full triaxial stress distribution. Together, these approaches provide a better understanding of rail fabrication and the possibility of improving the durability and safety of rails in the future.Copyright © 2004 by ASME