Numerical Simulation of Coal Ash Particle Behavior in Entrained Flow Coal Gasifier

2003 ◽  
Author(s):  
Hiroaki Watanabe ◽  
Kazuyoshi Ichikawa ◽  
Maromu Otaka ◽  
Jun Inumaru
Keyword(s):  
Numerical Simulation ◽  
Gas Phase ◽  
Coal Gasification ◽  
Current Model ◽  
Electric Power Industry ◽  
Central Research ◽  
Ash Deposition ◽  
Entrained Flow ◽  
Coal Gasifier ◽  
Coal Particles

The objective of this study is to develop an evaluation tool for a design and performance of a coal gasifier by a numerical simulation technique. In the present paper, a gas-particle two phase reacting flow calculation is carried out for a prediction of phenomena in an entrained flow coal gasifier due to coal and ash particles behavior, such as ash deposition on the wall. A transportation of the coal particles is modeled via a Lagrangian manner. The ash particle adhesion on the wall of the gasifier is discriminated by an empirical ash adhesion model based on a liquid phase fraction concept in the ash particle. The gas phase properties are calculated by three dimensional time-mean Eulerian conservation equations. The turbulent flow field is determined by the k-ε two equations model. Radiative heat transfer is calculated by the discrete transfer radiation method. Coal gasification reaction model is composed of three chemical processes in the current model: a pyrolysis, a char gasification and gas phase reactions. 2 tons/day (t/d) air-blown pressurized entrained flow coal gasifier, which has been constructed and operated by Central Research Institute of Electric Power Industry (CRIEPI) was targetted. As a result, a relationship between an operating condition (air ratio) of the gasifier and the gasifier performance is presented. The trend of the ash deposition on the gasifier inner wall is also presented. Comparison between the computational and the experimental results shows that the most feature of the gasifier performance and the profile of the ash deposition have been captured by the present model. It was confirmed that the numerical simulation approach is very useful for the assessment of gasifier performance and operation support.

Investigation of chemical composition and morphology of ash deposition in syngas cooler of an industrialized two-stage entrained-flow coal gasifier

Energy ◽  
2020 ◽  
Vol 194 ◽  
pp. 116901 ◽  
Author(s):  
Guangyu Li ◽  
Shisen Xu ◽  
Xuebin Zhao ◽  
Ruijin Sun ◽  
Chang’an Wang ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Ash Deposition ◽  
Two Stage ◽  
Entrained Flow ◽  
Coal Gasifier

Numerical Study of Coal Gasification Using Eulerian-Eulerian Multiphase Model

2007 ◽  
Author(s):  
Shaoping Shi ◽  
Christopher Guenther ◽  
Stefano Orsino
Keyword(s):  
Gas Phase ◽  
Large Scale ◽  
Coal Gasification ◽  
Solid Phase ◽  
Numerical Study ◽  
Three Dimensional ◽  
Phase Method ◽  
Multiphase Model ◽  
Measured Temperature ◽  
Entrained Flow

Gasification converts the carbon-containing material into a synthesis gas (syngas) which can be used as a fuel to generate electricity or used as a basic chemical building block for a large number of uses in the petrochemical and refining industries. Based on the mode of conveyance of the fuel and the gasifying medium, gasification can be classified into fixed or moving bed, fluidized bed, and entrained flow reactors. Entrained flow gasifiers normally feature dilute flow with small particle size and can be successfully modeled with the Discrete Phase Method (DPM). For the other types, the Eulerian-Eulerian (E-E) or the so called two-fluid multiphase model is a more appropriate approach. The E-E model treats the solid phase as a distinct interpenetrating granular “fluid” and it is the most general-purposed multi-fluid model. This approach provides transient, three-dimensional, detailed information inside the reactor which would otherwise be unobtainable through experiments due to the large scale, high pressure and/or temperature. In this paper, a transient, three-dimensional model of the Power Systems Development Facility (PSDF) transport gasifier will be presented to illustrate how Computational Fluid Dynamics (CFD) can be used for large-scale complicated geometry with detailed physics and chemistry. In the model, eleven species are included in the gas phase while four pseudo-species are assumed in the solid phase. A total of sixteen reactions, both homogeneous (involving only gas phase species) and heterogeneous (involving species in both gas and solid phases), are used to model the coal gasification chemistry. Computational results have been validated against PSDF experimental data from lignite to bituminous coals under both air and oxygen blown conditions. The PSDF gasifier geometry was meshed with about 70,000, hexahedra-dominated cells. A total of six cases with different coal, feed gas, and/or operation conditions have been performed. The predicted and measured temperature profiles along the gasifier and gas compositions at the outlet agreed fairly well.

Effect of Radiation Models on Coal Gasification Simulation

2012 ◽  
Author(s):  
Xijia Lu ◽  
Ting Wang
Keyword(s):  
Wall Temperature ◽  
Coal Gasification ◽  
Cfd Simulation ◽  
Stokes Equations ◽  
Heterogeneous Reactions ◽  
Coal Slurry ◽  
Radiation Model ◽  
Entrained Flow ◽  
Gasification Process ◽  
Coal Particles

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.

Design and Testing of a High Pressure and High Temperature, Optically Accessible, Entrained Flow Coal Gasifier

2011 ◽  
Author(s):  
Indraneel Sircar ◽  
Rohan Gejji ◽  
Anup Sane ◽  
David Blunck ◽  
Scott Meyer ◽  
...  
Keyword(s):  
Coal Gasification ◽  
Tunable Diode Laser ◽  
Thermodynamic Efficiency ◽  
Entrained Flow ◽  
Laser Absorption ◽  
Coal Gasifier ◽  
Powder Feeder ◽  
Major Species ◽  
Gasification Reaction ◽  
Design And Testing

Improved understanding of coal gasification chemical kinetics is needed to increase thermodynamic efficiency and to reduce undesirable CO2 emissions. This work describes an optically-accessible entrained-flow coal gasifier designed and built to allow measurements of the major species at various stages of the chemical reactions. The 2-meter tall gasifier consists of five subsystems: the optical diagnostics, steam generator, coal feeder, external heaters, and gas sampling and analysis. A stoichiometric H2-O2 flame generates superheated steam, the gasifying agent, which reacts with pulverized coal fed from a variable feed-rate pressurized powder feeder. To sustain the endothermic coal gasification reaction, radiant heaters provide 15 kW of external heating. Diagnostics to determine the major species concentrations consist of tunable diode laser absorption spectroscopy (TDLAS) measurements within the reactor vessel assembly and analysis of dry product gases using a gas chromatograph.

Sign in / Sign up

Export Citation Format

Share Document