An accurate and complete geometric model was constructed to simulate the combustion, flow and temperature environment in the radiant section of the steam cracking furnace. Simulation of flow and radiation status has u...An accurate and complete geometric model was constructed to simulate the combustion, flow and temperature environment in the radiant section of the steam cracking furnace. Simulation of flow and radiation status has utilized the standard k-ε model and P1 model. The finite-rate/eddy-dissipation (finite-rate/ED) combustion model and non-premixed combustion model were both used to simulate accurately the combustion and the operation status of the steam cracking furnace. Three different surfaces of the steam cracking furnace were obtained from the simulation, namely:the flue gas temperature field of the entrance surface in long flame burners, the central surface location of tubes, and the crossover section surface. Detailed information on the flue gas temperature and the mass concentration fraction of these different surfaces in the steam cracking furnace can also be obtained by the simulation. This paper analyzed and compared the simulation results with the two combustion models, estimated the operation status of the steam cracking furnace, and reported that the finite-rate/ED model is appropriate to simulate the steam cracking furnace by comparing key simulation data with actual test data. This work has also provided a theoretical basis for simulating and operating the steam cracking furnace.展开更多
Five coal char samples were burnt in thermobalance with ramp heating rate of 30 K/min. The pore structure of these char samples was studied through mercury intrusion method. Combined with the kinetic theory of gases, ...Five coal char samples were burnt in thermobalance with ramp heating rate of 30 K/min. The pore structure of these char samples was studied through mercury intrusion method. Combined with the kinetic theory of gases, the data of surface area was used in fitting the results. As a result, the kinetic triplet was given. The analysis showed that five char samples share almost the same intrinsic activation energy of the overall reaction. The phenomenological implication of the derived combustion rate equation was given.展开更多
Magnesium is of interest for underwater propulsion due to the superior ignition behavior of magnesium particles and the highly exothermic Mg-water reaction.In this work,the ignition and combustion characteristics of a...Magnesium is of interest for underwater propulsion due to the superior ignition behavior of magnesium particles and the highly exothermic Mg-water reaction.In this work,the ignition and combustion characteristics of an individual millimeter-sized magnesium particle in water vapor were studied.In order to build an atmosphere of water vapor,an experiment system was established and validated by the experiments of magnesium particle in air.The ignition and combustion of a single magnesium particle were accomplished in a combustor filled with water vapor.The surface changes of the particle during the ignition and a steady-state vapor phase combustion were observed.Based on the data obtained,ignition mechanism was analyzed and ignition temperature was determined.The steady-state combustion of the sample was controlled by diffusion in gas phase,and a one-dimensional,spherically symmetric quasi-steady model was adopted to describe the process.The dependence of burning time on the diameter was investigated,and the conclusion that burning time is proportional to the square of the metal sample diameter was drawn.展开更多
基金supported by the technology development fund of China Petroleum & Chemical Corporation (Sinopec 409045)
文摘An accurate and complete geometric model was constructed to simulate the combustion, flow and temperature environment in the radiant section of the steam cracking furnace. Simulation of flow and radiation status has utilized the standard k-ε model and P1 model. The finite-rate/eddy-dissipation (finite-rate/ED) combustion model and non-premixed combustion model were both used to simulate accurately the combustion and the operation status of the steam cracking furnace. Three different surfaces of the steam cracking furnace were obtained from the simulation, namely:the flue gas temperature field of the entrance surface in long flame burners, the central surface location of tubes, and the crossover section surface. Detailed information on the flue gas temperature and the mass concentration fraction of these different surfaces in the steam cracking furnace can also be obtained by the simulation. This paper analyzed and compared the simulation results with the two combustion models, estimated the operation status of the steam cracking furnace, and reported that the finite-rate/ED model is appropriate to simulate the steam cracking furnace by comparing key simulation data with actual test data. This work has also provided a theoretical basis for simulating and operating the steam cracking furnace.
基金The work was subsidized by the Special Funds for Major State Basic Research Projects(973).project number G1999022205.
文摘Five coal char samples were burnt in thermobalance with ramp heating rate of 30 K/min. The pore structure of these char samples was studied through mercury intrusion method. Combined with the kinetic theory of gases, the data of surface area was used in fitting the results. As a result, the kinetic triplet was given. The analysis showed that five char samples share almost the same intrinsic activation energy of the overall reaction. The phenomenological implication of the derived combustion rate equation was given.
基金supported by the National Natural Science Foundation of China (Grant No. 51006118)
文摘Magnesium is of interest for underwater propulsion due to the superior ignition behavior of magnesium particles and the highly exothermic Mg-water reaction.In this work,the ignition and combustion characteristics of an individual millimeter-sized magnesium particle in water vapor were studied.In order to build an atmosphere of water vapor,an experiment system was established and validated by the experiments of magnesium particle in air.The ignition and combustion of a single magnesium particle were accomplished in a combustor filled with water vapor.The surface changes of the particle during the ignition and a steady-state vapor phase combustion were observed.Based on the data obtained,ignition mechanism was analyzed and ignition temperature was determined.The steady-state combustion of the sample was controlled by diffusion in gas phase,and a one-dimensional,spherically symmetric quasi-steady model was adopted to describe the process.The dependence of burning time on the diameter was investigated,and the conclusion that burning time is proportional to the square of the metal sample diameter was drawn.
