Design and Simulation of a Hybrid Entrained-Flow and Fluidized Bed Mild Gasifier: Part 2—Case Study and Analysis

2011 ◽  
Author(s):  
A. K. M. Monayem Mazumder ◽  
Ting Wang ◽  
Jobaidur R. Khan
Keyword(s):  
Multiphase Flow ◽  
Fluidized Bed ◽  
Flow Behavior ◽  
Flame Temperature ◽  
Heterogeneous Reactions ◽  
Thermal Flow ◽  
Entrained Flow ◽  
Progressive Development ◽  
Gasification Process ◽  
Flow And Heat Transfer

To help design a mild-gasifier, a reactive multiphase flow computational model has been developed in Part 1 using Eulerian-Eulerian method to investigate the thermal-flow and gasification process inside a conceptual, hybrid entrained-flow and fluidized-bed mild-gasifier. In Part 2, the results of the verifications and the progressive development from simple conditions without particles and reactions to complicated conditions with full reactive multiphase flow are presented. Development of the model starts from simulating single-phase turbulent flow and heat transfer in order to understand the thermal-flow behavior, followed by introducing seven global, homogeneous gasification reactions progressively added one equation at a time. Finally, the particles are introduced, and heterogeneous reactions are added in a granular flow field. The mass-weighted, adiabatic flame temperature is validated through theoretical calculation and the minimum fluidization velocity is found to be close to Ergun’s correlation. Furthermore, the predicted exit species composition is consistent with the equilibrium values.

scholarly journals Cyber-Physical Observer for Fluidized Bed-Chemical Looping Control Applications

2017 ◽  
Author(s):  
Lawrence Shadle ◽  
David Tucker ◽  
Ronald Breault ◽  
Samuel Bayham ◽  
Justin Weber ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Fluidized Bed ◽  
Gas Flow ◽  
Flow Behavior ◽  
Chemical Looping ◽  
Flow Paths ◽  
Response Data ◽  
Flow Through ◽  
And Performance ◽  
And Control

A cyber-physical fluidized bed-chemical looping reactor (FB-CLR) is proposed to observe and control the multiphase flow behavior and improve process operations, stability, and performance. The cyber-physical observer (CPO) provides an opportunity to probe a duplicate, or mirrored, non-reacting, multiphase flow system in real-time and provide response data not available from the hot reacting system in order to control the hot unit. A control strategy was developed to share and integrate this information between to the two systems. During test operations the data from the shifting inventory of granular particles in the cold flow unit will be used to control some of the valves controlling the gas flow paths in the hot unit. Taken in conjunction with the inlet flows, temperatures, and pressures in the hot unit a control system is proposed to balance the exhaust flow through the various gas outlets of the different vessels. System identification studies are needed to characterize the process delays, time constants, and interactions between control parameters.

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 Simulation of a Hybrid Entrained-Flow and Fluidized Bed Mild Gasifier: Part 1—Design Considerations and Development of a Multiphase Model

2011 ◽  
Author(s):  
A. K. M. Monayem Mazumder ◽  
Ting Wang ◽  
Jobaidur R. Khan
Keyword(s):  
Power Plant ◽  
Computational Model ◽  
Fluidized Bed ◽  
Stokes Equations ◽  
High Energy ◽  
Multiphase Model ◽  
Entrained Flow ◽  
Design Considerations ◽  
Gasification Process ◽  
Coal Particles

A mild gasification process has been developed to provide an innovative form of clean coal technology, which can be utilized to build a new, highly efficient, and compact power plant or to retrofit an existing coal-fired power plant in order to achieve lower emissions and significantly improved thermal efficiency. The core technology of the mild gasification power plant lies on the design of a compact and effective mild gasifier that can produce synthesis gases with high energy volatiles through a hybrid system: utilizing the features of both entrained-flow and fluidized bed gasifiers. The objectives of this study are to (a) describe the features and design considerations of this mild gasifier and (b) develop a multiphase computational model to guide the design of the mild-gasifier by investigating the thermal-flow and gasification process inside a conceptual mild gasifier. Due to the involvement of a fluidized bed, the Eulerian-Eulerian method is employed to calculate both the primary phase (air) and the secondary phase (coal particles). Multiphase constitutive equations developed from kinetic theory are employed for calculating the effective shear viscosities, bulk viscosities, and effective thermal conductivities of granular flows to simulate the hydrodynamic and thermal interactions between the solid and gas phases. Multiphase Nativer-Stokes equations and seven global reaction equations with associated species transported equations are implementd to simulate the mild gasification process. Part 1 of this paper documents the design principle of the mild gasifier as well as the development of the computational model starting from single phase, then using multiple phases, and finally including all reactions in the multiphase flow.

Modeling of Multiphase Flow and Heat Transfer in Radiant Syngas Cooler of an Entrained-Flow Coal Gasification

2009 ◽  
Vol 48 (22) ◽  
pp. 10094-10103 ◽  
Author(s):  
Guangsuo Yu ◽  
Jianjun Ni ◽  
Qinfeng Liang ◽  
Qinghua Guo ◽  
Zhijie Zhou
Keyword(s):  
Heat Transfer ◽  
Multiphase Flow ◽  
Coal Gasification ◽  
Entrained Flow ◽  
Flow And Heat Transfer

Investigation on the control of multiphase flow behavior in a continuous casting tundish during ladle change

2020 ◽  
Vol 117 (6) ◽  
pp. 619
Author(s):  
Rui Xu ◽  
Haitao Ling ◽  
Haijun Wang ◽  
Lizhong Chang ◽  
Shengtao Qiu
Keyword(s):  
Multiphase Flow ◽  
Flow Behavior ◽  
Rolled Strip ◽  
Impact Zone ◽  
Steel Cleanliness ◽  
Carry Over ◽  
Slag Carry Over ◽  
Hot Rolled ◽  
Turbulence Inhibitor ◽  
The Impact

The transient multiphase flow behavior in a single-strand tundish during ladle change was studied using physical modeling. The water and silicon oil were employed to simulate the liquid steel and slag. The effect of the turbulence inhibitor on the slag entrainment and the steel exposure during ladle change were evaluated and discussed. The effect of the slag carry-over on the water-oil-air flow was also analyzed. For the original tundish, the top oil phase in the impact zone was continuously dragged into the tundish bath and opened during ladle change, forming an emulsification phenomenon. By decreasing the liquid velocities in the upper part of the impact zone, the turbulence inhibitor decreased considerably the amount of entrained slag and the steel exposure during ladle change, thereby eliminating the emulsification phenomenon. Furthermore, the use of the TI-2 effectively lowered the effect of the slag carry-over on the steel cleanliness by controlling the movement of slag droplets. The results from industrial trials indicated that the application of the TI-2 reduced considerably the number of linear inclusions caused by ladle change in hot-rolled strip coils.

Investigation of a dual cold-flow fluidized bed for calcium looping gasification process

2019 ◽  
Vol 353 ◽  
pp. 10-19 ◽  
Author(s):  
Yijun Liu ◽  
Shiyi Chen ◽  
Min Zhu ◽  
Ahsanullah Soomro ◽  
Wenguo Xiang
Keyword(s):  
Fluidized Bed ◽  
Cold Flow ◽  
Calcium Looping ◽  
Gasification Process

Effect of Surface State of Die on Flow Rate of Steamed Bamboo Powder in Thermal Flow Test Using Capillary Rheometer

2015 ◽  
Vol 651-653 ◽  
pp. 830-835
Author(s):  
Shohei Kajikawa ◽  
Riku Sakagami ◽  
Takashi Iizuka
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Surface State ◽  
Flow Behavior ◽  
Thermal Flow ◽  
Average Roughness ◽  
Arithmetic Average ◽  
Flow Test ◽  
Die Surface ◽  
Bamboo Powder

Thermal flow tests were performed on steamed bamboo powder using capillaries that were processed under different conditions in order to investigate the effect of the die surface state on the fluidity of the woody powder. The capillaries were processed by wire-cut electric discharge machining, reaming or drilling, and the arithmetic average roughness (Ra) varied from 0.5 to 2.5 μm. The bamboo powder was first steamed at 200 °C for 20 min, and its particle size was then controlled using different mesh screens. The thermal flow temperature was set at 200 °C. The results indicated that the flow behavior improved with increasing particle size. For the capillaries processed by WEDM, the flow rate for samples with particle sizes of 75~150 and 150~300 μm decreased with increasing Ra. On the other hand, when reaming or drilling was used to process the capillaries, the flow rate was almost independent of Ra, regardless of the particle size.

Dynamic Modeling for Temperature Prediction in a Fluidized Bed Biomass Gasification Process

2021 ◽  
Author(s):  
Ibtihaj Khurram Faridi ◽  
Evangelos Tsotsas ◽  
Wolfram Heineken ◽  
Marcus Koegler ◽  
Abdolreza Kharaghani
Keyword(s):  
Fluidized Bed ◽  
Dynamic Modeling ◽  
Biomass Gasification ◽  
Temperature Prediction ◽  
Gasification Process
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