Investigation of Heat Transfer and Gasification of Two Different Fuel Injectors in an Entrained Flow Coal Gasifier

Wang, Ting; Silaen, Armin K.; Hsu, Heng-Wen; Shen, Cheng-Hsien

doi:10.1115/1.4001806

Cited by 7 publications

(4 citation statements)

References 2 publications

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“…The injector is water cooled through an annular water jacket wrapping around the fuel and oxygen passages. The blunt injector tip with multiple holes is derived from a previous study which investigated the performance and life expectancy of two injectors' designs [1]. It was discovered that the injector with a blunt tip geometry was able to reduce temperature gradient along the injector and significantly increase the life of the fuel injector more than the injector with the conical tip.…”

Section: Experimental Facilitymentioning

confidence: 99%

Employment of Two-Stage Oxygen Feeding to Control Temperature in a Downdraft Entrained-Flow Coal Gasifier

Wang¹,

Lu²,

Hsu³

et al. 2014

IJCCE

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The traditional practice of employing a two-stage coal-fed gasification process is to feed all of the oxygen to provide a vigorous amount of combustion in the first stage but only feed the coal without oxygen in the second stage to allow the endothermic gasification process to occur downstream of the second stage. One of the merits of this 2-stage practice is to keep the gasifier temperature low downstream from the 2nd stage. This helps to extend the life of refractory bricks, decrease gasifier shutdown frequency for scheduled maintenance, and reduce the maintenance costs. In this traditional 2-stage practice, the temperature reduction in the second stage is achieved at the expense of a higher than normal temperature in the first stage. This study investigates a concept totally opposite to the traditional two-stage coal feeding practices in which the injected oxygen is split between the two stages, while all the coal is fed into the first stage. The hypothesis of this two-stage oxygen injection is that a distributed oxygen injection scheme can also distribute the release of heat to a larger gasifier volume and, thus, reduce the peak temperature distribution in the gasifier. The increased life expectancy and reduced maintenance of the refractory bricks can prevail in the entire gasifier and not just downstream from the second stage. In this study, both experiments and computational simulations have been performed to verify the hypothesis. A series of experiments conducted at 2.5-3.0 bars shows that the peak temperature and temperature range in the gasifier do decrease from 600˚C-1550˚C with one stage oxygen injection to 950˚C-1230˚C with a 60-40 oxygen split-injection. The CFD results conducted at 2.5 bars show that 1) the carbon conversion ratio for different oxygen injection schemes are all above 95%; 2) H2 (about 70% vol.) dominates the syngas composition at the exit; 3) the 80%-20% case yields the lowest peak temperature and the most uniform temperature distribution along the gasifier; and 4) the 40%-60% case produces the syngas with the highest HHV. Both experimental data and CFD predictions verify the hypothesis that it is feasible to reduce the peak temperature and achieve more T. Wang et al. 30 uniform temperature in the gasifier by adequately controlling a two-stage oxygen injection with only minor changes of the composition and heating value of the syngas.

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Section: Experimental Facilitymentioning

confidence: 99%

Employment of Two-Stage Oxygen Feeding to Control Temperature in a Downdraft Entrained-Flow Coal Gasifier

Wang¹,

Lu²,

Hsu³

et al. 2014

IJCCE

Self Cite

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“…combustion of coal particles are dictated by the following global processes: (i) evaporation of moisture, (ii) devolatilization, (iii) gasification to CO and (iv) combustion of volatiles, CO, and char. The rate of depletion of solid due to a surface reaction is expressed as: (15) and (16) where = rate of particle surface species depletion (kg/s) A p = particle surface area (m 2 ) Y = mass fraction of surface the solid species in the particle η = effectiveness factor (dimensionless) R = rate of particle surface species reaction per unit area (kg/m 2 -s) p n = bulk concentration of the gas phase species (kg/m 3 ) D = diffusion rate coefficient for reaction k = kinetic rate of reaction (units vary) N = apparent order of reaction.…”

Section: Heterogeneous Reactions (Coal Particles)mentioning

confidence: 99%

“…In collaboration with the research team of Industrial Technology Research Institute (ITRI), Wang and Silaen effectively employed the CFD gasification model to investigate gasification process under the influences of different part loads, two different injectors, and three different slagging tap sizes [14] [15] [16]. In 2011, Wang, et al performed the simulation on the effects of potential fuel injection techniques on gasification performance in order to help design the top-loaded fuel injection arrangement for an entrained-flow gasifier using a coal-water slurry as the input feedstock.…”

Section: Introductionmentioning

confidence: 99%

Effect of Radiation Models on Coal Gasification Simulation

Wang

2012

Volume 6: Energy, Parts a and B

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Adequate modeling of radiation heat transfer is important in CFD simulation of coal gasification process. In an entrained-flow gasifer, the non-participating effect of coal particles, soot, ashes, and reactive gases could significantly affect the temperature distribution in the gasifier and hence affects the local reaction rate and life expectancy of wall materials. For slagging type gasifiers, radiation further affects the forming process of corrosive slag on the wall which can expedite degradation of the refractory lining in the gasifier. For these reasons, this paper focuses on investigating applications of five different radiation models to coal gasification process, including Discrete Transfer Radiation Model (DTRM), P-1 Radiation Model, Rosseland Radiation Model, Surface-to-Surface (S2S) Radiation Model, and Discrete Ordinates (DO) Radiation Model. The objective is to identify the pros and cons of each model’s applicability to the gasification process and determine which radiation model is most appropriate for simulating the process in entrained-flow gasifiers. The Eulerian-Lagrangian approach is applied to solve the Navier-Stokes equations, nine species transport equations, and seven global reactions consisting of three heterogeneous reactions and four homogeneous reactions. The coal particles are tracked with the Lagrangian method. Six cases are studied—one without the radiation model and the other five with different radiation models. The result reveals that the various radiation models yield uncomfortably large uncertainties in predicting syngas composition, syngas temperature, and wall temperature. The Rosseland model does not yield reasonable and realistic results for gasification process. The DTRM model predicts very high syngas and wall temperatures in the dry coal feed case. In the one-stage coal slurry case, DTRM result is close to the S2S result. The P1 method seems to behave stably and is robust in predicting the syngas temperature and composition; it yields the result most close to the mean, but it seems to underpredict the gasifier’s inner wall temperature.

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“…The GDI injector's working mechanism relates to the electro-magnetic-thermal-machine-liquid multi-disciplinary theory, with strong nonlinearity and coupling [1], so the GDI injector must have high dynamic response speed, wide linear dynamic range of fuel injection quantity and high control precision. In order to meet the requirements mentioned above, the current research of GDI injector mainly focuses on two aspects: on the one hand, through optimizing the drive circuit and control strategy to improve the controlling precision of the injector drive circuit that improve the dynamic response of the GDI injector [2][3][4]; on the other hand, through optimizing the nozzle structure to improve the fuel atomization quality and spray form [5].…”

Section: Introductionmentioning

confidence: 99%

Simulation and analysis on electro-magnetic- thermal coupling of solenoid GDI injector

Cheng

Zhang

Guo

et al. 2014

International Journal of Applied Electromagnetics and Mechanics

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The GDI (Gasoline Direct Injection) injector is influenced by electro-magnetic-thermal coupling, and has strong nonlinearity and coupling. Temperature rise greatly impacts the performance of the GDI injector and makes the ECU of the engine difficult to control fuel injection quantity accurately. According to the coupling relationship of electric, magnetic and thermal subsystems of the GDI injector, the physical model of coupled process was established. The energy loss and transformation of the GDI injector in work process was explored, and revealed that the energy loss in electromagnetic conversion was a key factor to cause the GDI injector temperature rise. The energy loss coming from electromagnetic conversion was regarded as heat source. The temperature field of the GDI injector contains heat conduction and thermal radiation was analyzed based on the finite element theories. By using the ANSYS software to simulate multiple physical fields of the GDI injector, and then experiment method to verify the simulation results, distribution characteristics of temperature field and variations of temperature rise effect on the performance of the GDI injector was analyzed. The results show that, higher temperature rise is concentrated on coil and core part and with the higher temperature rise the response time of the GDI injector get longer, the fuel injection quantity becomes less. The value and pulse width of the holding current I have great impact on the GDI injector performance and temperature rise.

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Investigation of Heat Transfer and Gasification of Two Different Fuel Injectors in an Entrained Flow Coal Gasifier

Cited by 7 publications

References 2 publications

Employment of Two-Stage Oxygen Feeding to Control Temperature in a Downdraft Entrained-Flow Coal Gasifier

Employment of Two-Stage Oxygen Feeding to Control Temperature in a Downdraft Entrained-Flow Coal Gasifier

Effect of Radiation Models on Coal Gasification Simulation

Simulation and analysis on electro-magnetic- thermal coupling of solenoid GDI injector

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