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Fossil fuels (i.e., petroleum, natural gas and coal), which meet most of the world's energy demand today, are being depleted rapidly and will be exhausted in decades or several hundred years. Also, their combustion products are causing global problems, such as the greenhouse effect, ozone layer depletion, acid rain and pollution, which are posing great danger for our environment, and eventually, for the total life on our planet. It is the controlled thermonuclear fusion hydrogen energy system that would overcome all these problems and be the permanent solution of the world's energy supply lasting for billions of years. Source

You C.,Tsinghua University | Li Y.,Dongfang Boiler Group Co.
Environmental Science and Technology

Semidry flue gas desulfurization (FGD) experiments were conducted using rapidly hydrated sorbents with four different adhesive carrier particles: circulation ash from a circulating fluidized bed boiler (CFBB circulation ash), fly ash from the first electrical field of the electrostatic precipitator of a circulating fluidized bed boiler (CFBB ESP ash), fly ash from a chain boiler (chain boiler ash), and river sand smaller than 1 mm. The influences of various adhesive carrier particles and operating conditions on the desulfurization characteristics of the sorbents were investigated, including sprayed water, reaction temperature, and the ratio of calcium to sulfur (Ca/S). The experimental results indicated that the rapidly hydrated sorbents had better desulfurization characteristics by using adhesive carrier particles which possessed better pore, adhesion, and fluidization characteristics. The desulfurization efficiency of the system increased as the reaction temperature decreased, it improved from 35% to 90% as the mass flow rate of the sprayed water increased from 0 to 10 kg/h, and it increased from 65.6% to 82.7% as Ca/S increased from 1.0 to 2.0. Based on these findings, a new semidry circulating fluidized bed (CFB)-FGD system using rapidly hydrated sorbent was developed. Using the rapidly hydrated sorbent, this system uses a cyclone separator instead of an ESP or a bag filter to recycle the sorbent particles, thereby decreasing the system flow resistance, saving investment and operating costs of the solids collection equipment. © 2013 American Chemical Society. Source

Peng Z.,Wuhan University | Cai L.,Wuhan University | Peng F.,Dongfang Boiler Group Co. | Hu Y.,Inner Mongolia North Heavy Industries Group Co. | Chen F.,Wuhan Iron And Steel Company
Jinshu Xuebao/ Acta Metallurgica Sinica

In the present study, the multi-segment feature of stress vs rupture-time plot and the corresponding quatitative change of phase parameters of M23C6 and Laves in each segment were investigated for P92 steel samples subjected to 625°Ccreep-rupture tests. The results indicate that the stress vs rupture-time plot obtained from the test results can be divided into two segments (higher stress level and shorter rupture time segment: 180-150 MPa/30-454 h, and lower stress level and longer rupture time segment: 140-110 MPa/2881-10122 h) respectively, and the microstructure evolution is closely related to the feature of each segment. In the higher stress level and shorter rupture time segment the M23C6 particles are coarsened, while in the lower stress level and longer rupture time segment both M23C6 and Laves phases are coarsened, but the latter is predominantly. The average composition, the amount and the elemental partitioning of each alloy phase called phase parameters can be deter- mined by a multiphase separation method developed. © Copyright. Source

Peng Z.,Wuhan University | Dang Y.,Wuhan University | Peng F.,Dongfang Boiler Group Co.
Jinshu Xuebao/ Acta Metallurgica Sinica

Long-term creep-rupture properties are usually evaluated from short-term data by time-temperature parameter (TTP) method, such as Larson-miller parameter (LMP) and Orr-Sherby- Dorn (OSD) methods. However, the conventional TTP methods sometimes overestimate long-term creep rupture properties if the prediction is based on their short-term test data for 9%-12%Cr ferrite steels. The following concepts/methods are thus proposed in this paper in order to reduce the property overestimation tendency caused by the conventional TTP methods and to obtain a better agreement of the predicted property values with the observed ones. They include the C-value optimization and the multi-C region analysis, the long-term (5×103-1×105 h) creep rupture property prediction using short term test data (5×103 h), the optimization of function used for property prediction, and the effect of d[g(σ)]/d(P) vs P on the stability of steel properties based on the improved LMP method. All the data sets for the 9%-12%Cr steels are from NIMS database for the related calculations and analyses. The results show that the C-value in LMP is not only different from steel to steel type but also varies with the multi-region stress levels, and the new approach to rupture life prediction proposes procedures for extrapolations of the short-term results, with rupture time measurements from tests lasting up to only 5×103 h providing reasonable estimates of 105 h rupture strengths, as well as the variation tendency of d[f(σ)]/d(P) vs P can reflect directly the long-term property stability of the steels investigated. Therefore, the concepts/methods proposed could improve effectively the accordance of predicted property values with observed ones and overcome obviously the overestimation tendency of 105 h strengths, which are more suitable and easily realized to assess the long-term creep-rupture properties of the advanced high Cr ferritic steels. © Copyright. Source

Hu Z.,Shandong Electric Power Research Institute | Hao W.,Shandong Electric Power Research Institute | Xue M.,Hefei University of Technology | Wang J.,Dongfang Boiler Group Co.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering

For getting higher efficiency and lower NOx emission, a test to optimize combustion system is conducted in a 1000 MW bituminous coal-fired boiler in opposed firing pattern. During the test, the gas temperature distribution in furnace is measured, combustion and NOx emission characteristic is studied by varying such factors as type of coal, O2 at economizer exit, mass flow of over fired air (OFA), air damper position of burner and after air port (AAP), combinations of burners and boiler load. It indicates that O2 at economizer exit and mass flow of OFA have great effect on boiler efficiency and NOx emission. It's better to keep these two parameters at 3.0% and 750 t/h respectively , which can also eliminate slagging on platen superheater. O2 deviation along furnace width can be eliminated by setting outer second air damper of burners in same horizontal row at different proper positions. Unburned carbon in fly ash can be decreased by using design coal, closing outer second air damper of AAP, setting burner's core air damper at 50% and shutting down one-layer upper row burners at full load if possible. After adjustment, the measured efficiency of boiler is above 94.4% and NOx emission concentration is lower than 300 mg/m3. They are obviously better than those of boilers in service in China. © 2010 Journal of Mechanical Engineering. Source

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