Investigation of Bulging Behavior of Coke Drum: Feasible Study on Causes of Bulging

2011 ◽  
Author(s):  
Mitsuru Ohata ◽  
Nana Kawai ◽  
Tetsuya Tagawa ◽  
Fumiyoshi Minami ◽  
Toshiya Yamamoto ◽  
...  
Keyword(s):  
Temperature Field ◽  
Ambient Temperature ◽  
Temperature Profile ◽  
Shell Structure ◽  
Cooling Water ◽  
Fe Analysis ◽  
Large Strains ◽  
Shell Surface ◽  
Feasible Study ◽  
Rapid Drop

Coke drums undergo cyclic operations typically in the temperature range from ambient temperature to about 500°C (930°F). During quenching, the coke drum is inevitably subjected to a rapid drop in temperature because cooling water is injected directly into the coke drum through the bottom inlet nozzle. The temperature profile on the shell surface is no more uneven in quenching, and can vary in each cycle of quenching operation. Such complicate thermal profile induces large strains in the shell portion of the coke drum, and eventually causes damage like bulging or cracking. This study makes investigations into the bulging behavior of the coke drum by the thermal elastic-plastic FE-analysis. In this work, a feasible study is conducted on potential causes of bulging. As factors inducing a heterogeneous plasticity in the shell structure of the coke drum, the strength overmatch of welds and the uneven temperature field in quenching as well as quenching conditions are focused.

Investigation of Bulging Behavior of Coke Drum—A Practical Analysis of Bulging Under Complex Quench Conditions

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Toshiya Yamamoto ◽  
Kazuaki Arii ◽  
Shinta Niimoto ◽  
Mitsuru Ohata ◽  
Tetsuya Tagawa ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Cooling Water ◽  
Fe Analysis ◽  
Temperature Fields ◽  
Large Strains ◽  
Analysis Model ◽  
Actual Operation ◽  
Feasible Study ◽  
Temperature Strain ◽  
Rapid Drop

Coke drums undergo cyclic operations typically in the temperature range from room temperature to about 500 °C (930 °F). During quenching, the coke drum is inevitably subjected to a rapid drop in temperature because cooling water is injected directly into the coke drum through the bottom inlet nozzle. The temperature profile on the shell surface is uneven during quenching, and can vary in each cycle of the quenching operation. Such a complicated thermal profile induces large strains in the shell portion of the coke drum, and eventually causes damage like bulging and/or cracking. The authors have investigated the bulging behavior of the coke drum by the thermal elastic-plastic finite element (FE)-analysis, considering the existence of the overmatch welds and uneven temperature field during quenching (Ohata et al., 2011, “Investigation of Bulging Behavior of Coke Drum—Feasible Study on Causes of Bulging,” ASME PVP2011-57276, Baltimore). In this paper, a practical FE-analysis is developed to estimate the complex strain that leads to bulging under uneven temperature fields during quenching. The actual temperature and strain data during operation are collected by thermocouples and high temperature strain gauges. A thermal analysis model, including an evaluation of boiling heat transfer on the shell's inner surface, is established to simulate the measured shell behavior of the coke drum. By utilizing this FE-analysis model, several parameters thought of as causal factors in bulging can be examined under the uneven temperature profile that is likely to occur during actual operation. This analytical approach can also provide effective technique for improvements in shell durability.

Investigation of Bulging Behavior of Coke Drum: A Practical Analysis of Bulging Under Complex Quench Conditions

2011 ◽  
Author(s):  
Toshiya Yamamoto ◽  
Kazuaki Arii ◽  
Huhetaoli ◽  
Shinta Niimoto ◽  
Mitsuru Ohata ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Cooling Water ◽  
Fe Analysis ◽  
Temperature Fields ◽  
Large Strains ◽  
Analysis Model ◽  
Strain Data ◽  
Actual Operation ◽  
Temperature Strain ◽  
Rapid Drop

Coke drums undergo cyclic operations typically in the temperature range from room temperature to about 500°C (930°F). During quenching, the coke drum is inevitably subjected to a rapid drop in temperature because cooling water is injected directly into the coke drum through the bottom inlet nozzle. The temperature profile on the shell surface is uneven during quenching, and can vary in each cycle of the quenching operation. Such a complicated thermal profile induces large strains in the shell portion of the coke drum, and eventually causes damage like bulging and/or cracking. The authors have investigated the bulging behavior of the coke drum by the thermal elastic-plastic FE-analysis, considering the existence of the overmatch welds and uneven temperature field during quenching [1]. In this paper, a practical FE-analysis is developed to estimate the complex strain that leads to bulging under uneven temperature fields during quenching. The actual temperature and strain data during operation are collected by thermocouples and high temperature strain gauges. A thermal analysis model, including an evaluation of boiling heat transfer on the shell’s inner surface, is established to simulate the measured shell behavior of the coke drum. By utilizing this FE-analysis model, several parameters thought of as causal factors in bulging can be examined under the uneven temperature profile that is likely to occur during actual operation. This analytical approach can also provide effective technique for improvements in shell durability.

Investigation of Bulging Behavior of Coke Drum: Feasible Study on Causes of Bulging

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Mitsuru Ohata ◽  
Nana Kawai ◽  
Tetsuya Tagawa ◽  
Fumiyoshi Minami ◽  
Toshiya Yamamoto ◽  
...  
Keyword(s):  
Cooling Water ◽  
Large Strains ◽  
Shell Wall ◽  
Shell Surface ◽  
Operating Cycle ◽  
Plastic Distortion ◽  
Rate Of Cooling ◽  
Analytical Result ◽  
Feasible Study ◽  
Rapid Drop

Coke drums undergo cyclic operations typically in the temperature range from ambient temperature to about 500 °C (930 °F). During quenching, the coke drum is inevitably subjected to a rapid drop in temperature because cooling water is injected directly into the coke drum through the bottom inlet nozzle. The temperature profile on the shell surface is no more uneven in quenching, and can vary in each cycle of quenching operation. Such complicate thermal profile induces large strains in the shell portion of the coke drum, and eventually causes damage like bulging or cracking. This study makes investigations into the bulging behavior of the coke drum by the thermal elastic-plastic FE-analysis. In this work, a feasible study is conducted on potential causes of bulging. As factors inducing a heterogeneous plasticity in the shell structure of the coke drum, the strength overmatch of welds and the uneven temperature field in quenching as well as quenching conditions are focused. The analytical result shows that strength overmatch in girth seam welds can be one of the causes of plastic distortion under one operating cycle. The lower rising rate of cooling source can induce plastic straining over the whole shell wall, which tends to induce more remarkable plastic distortion.

Analysis of the autothermal operability of the Sabatier reaction in a heat-recirculating microreactor using CFD

2019 ◽  
Vol 4 (10) ◽  
pp. 1823-1833 ◽  
Author(s):  
Aswathy K. Raghu ◽  
Niket S. Kaisare
Keyword(s):  
Ambient Temperature ◽  
Temperature Profile ◽  
Methane Yield ◽  
Stable Operation ◽  
Heat Recirculation ◽  
Sabatier Reaction ◽  
Micro Reactor

The Sabatier reaction in a U-bend micro-reactor benefits from a favourable temperature profile owing to heat recirculation, which improves methane yield and enables stable operation even with feed at ambient temperature.

scholarly journals Modeling temperature profile in mass concrete at early ages of cement hydration

2021 ◽  
Vol 10 (1) ◽  
pp. 64
Author(s):  
Ugwuanyi Donald Chidiebere ◽  
Okafor Fidelis Onyebuchi
Keyword(s):  
Ambient Temperature ◽  
Temperature Profile ◽  
Cement Hydration ◽  
Concrete Block ◽  
Control Measures ◽  
Mass Concrete ◽  
Thermally Induced ◽  
Thermal Cracks ◽  
Concrete Placement ◽  
And Control

Thermally induced cracks due to temperature gradient in mass concrete have adverse effects on its durability and service life. Heat released during the hydration of Portland cement in early age mass concrete can be quite excessive depending on the ambient temperature, cement content of the concrete mix and the size. Finite difference model using Crank Nicholson implicit method was developed based on the two dimensional unsteady state heat conduction. Optimized MATLAB based software was developed for simulation and data visualization. A mass concrete block cast with standard mix ratio and water cement ratio was used to verify the efficacy of the model. Type-K thermocouple and digital thermometer were used to monitor the temperature at time intervals. The temperature profile showed a hotter core and cooler surface except for the initial placement temperature, which exhibited a uniform temperature for all thermocouple locations. Peak temperature values were recorded within the first day of concrete placement. The model successfully predicted the temperature profile of the mass concrete at early ages of cement hydration. With the knowledge of the ambient temperature and the configuration of the mass concrete, the model can reliably predict the temperature profile from which potential for thermal cracks occurrence can be determined to enable suitable proactive preventive and control measures.  

Effects of Stone-Wales Defects on the Thermal Conductivity of Carbon Nanotubes

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Li Wei ◽  
Feng Yanhui ◽  
Peng Jia ◽  
Zhang Xinxin
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Temperature Profile ◽  
Defect Position ◽  
Non Equilibrium Molecular Dynamics ◽  
Increasing Temperature ◽  
Dynamics Method

The thermal conductivity of carbon nanotubes with Stone-Wales (SW) defects was investigated using non-equilibrium molecular dynamics method. The defect effects were analyzed by the temperature profile and local thermal resistance of the nanotubes with one or more SW defects and further compared with perfect tubes. The influences of the defect concentration, the length, the chirality and the radius of tubes and the ambient temperature were studied. It was demonstrated that a sharp jump in the temperature profile occurred at defect position due to a higher local thermal resistance, thus dramatically reducing the thermal conductivity of the nanotube. As the number of SW defects increases, the thermal conductivity decreases. Relative to the chirality, the radius has greater effects on the thermal conductivity of tubes with SW defects. With the similar radius, the thermal conductivity of armchair nanotube is higher than that of zigzag one. The shorter nanotube is more sensitive to the defect than the longer one. Thermal conductivity of the nanotube increases with ambient temperature, reaches a peak, and then decreases with increasing temperature.

Numerical Simulation Investigation on the Temperature Field Distribution and Variations in Hot Stamping Process

2010 ◽  
Vol 44-47 ◽  
pp. 992-996
Author(s):  
Lei Zhang ◽  
Guo Qun Zhao ◽  
Hui Ping Li
Keyword(s):  
Temperature Field ◽  
Field Distribution ◽  
Hot Stamping ◽  
Water Channel ◽  
Cooling Water ◽  
Temperature History ◽  
Temperature Field Distribution ◽  
Finite Element Software ◽  
Stamping Process ◽  
Die Surface

With finite element software Abaqus, a coupled thermal mechanical simulation of hot stamping process of U-Channel part using high strength steel was performed. Through the analysis of the temperature field distribution on the die surface, the influence of contact state between die and blank on the temperature field distribution was discussed. With temperature history curve of a selected node on die corner, the heat flow on two contact boundaries (die surface and cooling water channel surface) was discussed and its effects rules on the die temperature were given.

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