Advanced Materials Research Vols. 614-615

Abstract: A model for the combustion of oil shale in the 65t/h circulating fluidized bed (CFB) boiler was developed, consisting of oil shale combustion, steam-water and ash circulation system, calculating the O2 and RO2 content of flue gas emission under three kinds of oil shale combustion in 65t/h CFB boiler. The calculated results indicate that the simulation values are consistent with the experimental values. Effect of boiler load on the temperature of furnace, flue gas emission, inlet and outlet flue gas of economizer was discussed based on the model. Boiler load on the increase results in a increase in temperature of furnace, flue gas emission, inlet and outlet flue gas of economizer. The main performance parameters of 65t/h oil shale CFB boiler system were discussed and preliminarily predicted by the model.

Abstract: Two brown coals from China were dewatered under hydrothermal dewatering (HTD) conditions at 250–320 °C for 1 h in a 2 L autoclave. The HTD products and brown raw coals were pyrolyzed in a thermogravimetry analyzer at heat rate of 15°C/min from ambient temperature to 800°C. And the gas products were measured by Fourier Transform Infrared Spectrometer. Besides, The Coast-Redfern model was employed to analyze the effects of HTD on kinetics during coal pyrolysis process. The results showed that the initial temperatures of each pyrolysis stage of HTD products were higher than that of raw coals. The temperatures at which methane appears during pyrolysis process increased and the total absorbance intensity of CH4 was weakened as increasing HTD temperature. Moreover, the activity energy also increased as increasing HTD temperature. It meant that thermal stability of brown coals was improved during HTD process.

Abstract: Tangentially-fired burner is widely used in pulverized coal boiler, but its air burner has some shortcomings, including the velocity of exit airflow weaken with the decrease of the opening degree of the air damper, leading to insufficient mixing between air and coal-powder. In view of the existing problems, a new type of double-channel air burner had been designed. Its flow field and adjustment characteristic were studied by using numerical simulation method. The results showed the double-channel air burner had effective flow adjustment characteristic which closely linearity. One of the channels could keep higher exit velocity when the air volume decrease and it could fulfill the demand of air adjustment better while in low NOx combustion or load variation.

Abstract: Thermo-acoustic refrigerator is a new type of engine, which is based on the thermo-acoustic effect. A new model which expresses as an ellipse in pressure-volume diagram is established to investigate the thermodynamic performance of an actual thermo-acoustic refrigeration micro-cycle. The demarcation points of endothermic processes and exothermic processes in the actual micro-cycle are found. The analytic expressions of the dimensionless cooling load and the coefficient of performance (COP) are deduced. The relationship between the dimensionless cooling load and the COP are investigated by numerical examples. The results show that the dimensionless cooling load is a monotonically increasing function of the COP and the pressure amplitude.

Abstract: In this research, experimental samples were from Maoming, Huadian, Wangqing, Fushun and Longkou regions in different layers and different mining area. The experimental results of oil shale proximate analysis and heating value measurement show that there are certain relations between proximate analysis of moisture, ash, fixed carbon, volatile matter and lower heating value. The relations between oil shale lower heating value and proximate analysis have important significance to estimate the average characteristics of oil shale as received and oil shale combustion conditions in boiler.

Abstract: The phenomenon of combustion of a gaseous mixture in a two-dimension alumina ( ) particle packed bed porous media burner is studied by means of a numerical simulation with FLUENT software using two-step reaction mechanism. The Eddy-dissipation-concept (EDC) model, the standard model and the Discrete- Ordinates (DO) radiation model are used in this paper. It is concluded that the methane/air gas mixture with lower equivalence ratio or with faster inlet velocity, can achieve the faster wave propagates. The methane/air gas mixture with lower equivalence ratio or with faster inlet velocity, can achieve the faster wave propagates.

Abstract: In order to obtain the more real condition of the flow field at condenser throat the flow field of condenser throat is numerical simulated by the FLUENT commercial software, alone or coupling with the low-pressure exhaust hood. The results show that the flow field of condenser throat is strongly influenced by low-pressure exhaust hood, the frustum’s diffuse-angle, the low-pressure heater and the injection of the exhaust steam from the small turbine. The velocity distribution at the outlet of the throat isn’t uniform. The calculation result of combined model is also different from the single calculation result of condenser throat. Combined numerical simulation obtains more reasonable result.

Abstract: The calculation of exhaust steam enthalpy for steam turbine units is an important parameter in the on-line monitoring and system analysis for thermal power plants. The cognitive modeling method for exhaust steam enthalpy based on evidence theory was studied in this paper. Take 330MW steam turbine for example, exhaust steam enthalpy samples are obtained from steam turbine variable condition analysis model, then exhaust steam enthalpy cognitive model based on simplify evidential regression multi-model is established. The error analysis shows that the accuracy of this model has higher prediction accuracy than the SVM and NW soft measurement model.

Abstract: The improved diagnostic technique based on the structure theory is applied to a 600MW coal fired power plant. Two typical malfunctions which only one malfunction occurs and multiple malfunctions occur simultaneously are researched by the malfunction simulation. The induced malfunctions could be separated by the sequential process model. The results show the modified diagnostic model based on thermo-economics structural theory is correct and practical.

Abstract: Daqing oil shale semi-coke combustion experiment has been performed through the Spouted bed experimental device for obtaining the temperature distribution, temperature and carbon content of separation materials. This paper presented the experimental study that the effect of three factors, containing screening particle size, wind speed and feeding flux, on the temperature variation of spouted bed and separation materials, and the carbon content in separation materials under different operating conditions. The experimental results show that the screening particle size and wind speed had great influence on the temperature of separation materials, while the carbon content is inversely proportional to the temperature of separation materials. This research further understands the combustion characteristic of Daqing oil shale semi-coke in spouted bed, establishing the foundation for the solid heat carrier retort in rotating retorting.