Study on Pollutants Emission Characteristic of Coal Gasification in a Fluidized Bed Test Rig

2005 ◽  
Author(s):  
Zhaoping Zhong ◽  
Baosheng Jin ◽  
Yaji Huang ◽  
Hongcang Zhou ◽  
Davide Ross ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Coal Gasification ◽  
Local Maximum ◽  
High Heat ◽  
Relative Mass ◽  
Feed Ratio ◽  
Emission Characteristic ◽  
Test Rig ◽  
Coal Syngas ◽  
Bed Temperature

This paper presents the results of coal gasification in a fluidized bed test rig of Xuzhou bituminous coal. The diameter of the fluidized bed combustor is 0.1m and the height is 4.22m. The bed temperature is maintained by a method of high temperature flue gas interline heating to overcome high heat losses associated with a oil burner. Test results are reported for variations in the bed temperature, air to coal, steam to coal and Ca to S ratio and their influence on gas yields and desulphurization efficiency. The distribution of polycyclic aromatic hydrocarbons (PAHs) and heavy metal trace elements into the char and syngas are also presented. The molar contents for CH4 and H2 in the coal syngas are found to decrease with increasing air to coal feed ratio from 2.5 to 5, while the content of CO shows little variation. Increasing the steam to coal feed ratio from 0.4 to 0.65 results in all three of the main gas components measured to form a local maximum content at a steam/coal feed ratio of 0.55. The efficiency of desulphurization improves as the ratio of Ca to S, air to coal and the bed temperature are increased, while decreasing with increasing steam to coal feed ratios. The volatile trace element species in decreasing order of relative mass ratio released into the gas phase are Hg, Se, As, Co, Cr, Cd, Cu, and Zn. Besides Hg, Se, and As, for all other trace heavy metals the majority of their mass distribution remains within the char with the proportion contained within char always greater than their combined yields in the coal syngas and slag. The total PAHs in the coal syngas is greater than that contained in the original coal and this indicates that PAHs are formed during the coal gasification process.

Development of Gas Steam and Power Multi-Generation System

2005 ◽  
Author(s):  
Mengxiang Fang ◽  
Qinghui Wang ◽  
Chunjiang Yu ◽  
Zhenglun Shi ◽  
Zhongyang Luo ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Coal Gasification ◽  
Cool System ◽  
Test Facility ◽  
Circulation Rate ◽  
Generation System ◽  
Fuel Gas ◽  
Heating Value ◽  
Bed Temperature ◽  
High Efficient

A new system using combined coal gasification and combustion has been developed for clean and high efficient utilization of coal. The coal is first gasified by air/steam or recycle gas and the produced fuel gas is then used for industrial purpose or as a fuel for gas turbine. The char residue from the gasifier is burned in a circulating fluidized bed combustor to generate steam for power generation. A 1MW pilot plant test facility has been erected, which consists of a fluidized bed gasifier, a CFB combustor, flue gas and fuel gas clean and cool system, data acqisition and control system. The primary results show that the system can produce 12–14MJ/Nm3 middle heating value gas by using recycle gas or steam as gasification mediaand bed temperature and solid circulation rate are main parameters. On bases of this, a 25 MW gas steam and power multi-generation system has been designed. In this system, a fluidized bed gasifiers are combined with a 130t/h circulating bed boiler to realize gas and steam cogeneration. The system can produce 7800 M3/h gas with heating value 10–14 Mj/Nm3 and 25 MW Power.

Effect of Static Bed Height on the Combustion of Rice Husk in a Fluidized Bed Combustor

2005 ◽  
Author(s):  
M. Rozainee ◽  
S. P. Ngo
Keyword(s):  
Fluidized Bed ◽  
Residence Time ◽  
Rice Husk ◽  
Bubble Formation ◽  
Combustion Process ◽  
High Heat ◽  
Transfer Rates ◽  
Bed Height ◽  
Bed Temperature ◽  
Bed Material

The combustion process is largely controlled by temperature, turbulence and residence time. When the temperature is sufficiently high so that the reaction is no longer kinetically-controlled, turbulence and residence time play a significant role. The reaction is thus diffusion-controlled. During the combustion of rice husk in a fluidized bed, the turbulence is largely governed by the mixing behavior in the inert sand bed, which in turn is governed by the bubble formation characteristics. Further, the residence time among the reactants (air and rice husk) and the heat source is also dependent on the turbulence in the bed. When all other parameters are held constant, the bubble phenomena vary according to the expanded bed height corresponding to a given static bed height. For high heat and mass transfer rates, small slowly rising bubbles are desired. Thus, the purpose of this study is to investigate the effect of static bed height on the quality of ash during the combustion of rice husk. The degree of rice husk burning in the bed could be deduced from the bed temperature as a higher bed temperature indicated that a higher portion of the rice husk feed is being burnt in the bed. Moreover, the particle size of the resulting ash is also able to give indication of the degree of rice husk burning in the bed as the turbulence arising from the bubbling action of the bed material is known to break down the char skeleton of the rice husk, thereby, resulting in ash with finer size. From this study, the static bed height of 0.5 DC was found to give the lowest residual carbon content in the ash (1.9 wt%) and the highest bed temperature (670°C) among the other range of static bed heights investigated.

Stress Relief of Coil Springs using Fluidized Bed

2021 ◽  
Author(s):  
Andrew S. Dickinson
Keyword(s):  
Heat Treatment ◽  
Fluidized Bed ◽  
Steel Wire ◽  
Stress Relief ◽  
High Heat ◽  
Turnaround Time ◽  
Internal Stresses ◽  
High Heat Transfer ◽  
Bed Temperature ◽  
Conventional Heat Treatment

Abstract After manufacturing coil springs, internal stresses exist within the steel wire. These stresses can lead to defects and may impact the working lifespan of springs. Stress must be relieved to maximize the elastic properties of the spring alloys. Stress relief is a critical step during the manufacturing process, typically using large belt furnaces and convection ovens. The fluidized bed heat treatment system is an alternative for stress relief of small- and medium-sized coil springs. Springs are suspended in a parts basket and deposited into a fluidized bed furnace, consisting of fine aluminum oxide particles gently mixed by an upward air flow. With its high heat transfer coefficient, fluidized bed relieves the stress in coil springs in significantly less time than other conventional heat treatment methods. Bed temperature is accurately controlled using either electric heaters, with excellent thermal uniformity throughout the working area of the bed. Fluidized bed, with its advantages of uniformity and quick turnaround time, render it the best option for the rapid and efficient stress relief processing of coil springs and heat treatment of other metal components.

Reducing Tar Emissions during Coal Gasification by Optimizing the Cracking/Reforming over Char in a Fluidized Bed

2021 ◽  
Author(s):  
Koichi Matsuoka ◽  
Koji Kuramoto ◽  
Sou Hosokai ◽  
Hiroaki Sato ◽  
Yosuke Tsuboi
Keyword(s):  
Fluidized Bed ◽  
Coal Gasification

The Local Heat Balance in a Stationary Fluidized-Bed Furnace Burning Biomass Fuels

2003 ◽  
Author(s):  
Fredrik Niklasson ◽  
Filip Johnsson
Keyword(s):  
Fluidized Bed ◽  
Combustion Rate ◽  
Heat Balance ◽  
Circulating Fluidized Bed ◽  
Local Heat ◽  
Splash Zone ◽  
Two Phase ◽  
Bed Temperature ◽  
Temperature Constant ◽  
The Vertical Distribution

This work investigates the influence of biomass fuel properties on the local heat balance in a commercial-scale fluidized bed furnace. Experiments with different wood based fuels were performed in the Chalmers 12 MWth circulating fluidized bed boiler, temporarily modified to run under stationary conditions. A two-phase flow model of the bed and splash zone is applied, where the combustion rate in the bed is estimated by global kinetic expressions, limited by gas exchange between oxygen-rich bubbles and a fuel-rich emulsion phase. The outflow of bubbles from the bed is treated as “ghost bubbles” in the splash zone, where the combustion rate is determined from turbulent properties. It is found that a large amount of heat is required for the fuel and air to reach the temperature of the bed, in which the heat from combustion is limited by a low char content of the fuel. This implies that a substantial fraction of the heat from combustion of volatiles in the splash zone has to be transferred back to the bed to keep the bed temperature constant. It is concluded that the moisture content of the fuel does not considerably alter the vertical distribution of heat emitted, as long as the bed temperature is kept constant by means of flue gas recycling.

Combined Coal Gasification and Methane Reforming for Production of Syngas in a Fluidized-Bed Reactor

2005 ◽  
Vol 19 (2) ◽  
pp. 512-516 ◽  
Author(s):  
Jinhu Wu ◽  
Yitian Fang ◽  
Yang Wang ◽  
Dong-ke Zhang
Keyword(s):  
Fluidized Bed ◽  
Coal Gasification ◽  
Fluidized Bed Reactor ◽  
Methane Reforming

The Pyrocarbon Deposition Techniques of Mechanical Heart Valve Prostheses

2011 ◽  
Vol 464 ◽  
pp. 749-752 ◽  
Author(s):  
Jian Hui Zhang ◽  
Xin Chen
Keyword(s):  
Fluidized Bed ◽  
Heart Valve ◽  
Gas Flow ◽  
Mechanical Heart Valve ◽  
Carbon Matrix ◽  
Artificial Heart Valve ◽  
Bed Temperature ◽  
Wide Range ◽  
Isotropic Carbon ◽  
Deposition Conditions

The structure and property of pyrocarbon varies widely with different deposition conditions. The isotropic carbon which can only been deposited in the bed of fluidized particles is very important in biomedical fields, for instance, it is often used as the coating of artificial heart valve components. The deposition of isotropic pyrocarbon containing silicon is experimented in fluidized bed over a wide range of deposition conditions. The results show that bed temperature influences strongly average coating rate, coating density, silicon content and coating micro-hardness. Propane concentration has a much effect on coating density, carbon matrix density and isotropic characteristics. Total gas flow rate and inlet dimension of fluidized bed affect the formation of fluidized bed.

Air-based coal gasification in a two-chamber gas reactor with circulating fluidized bed

2017 ◽  
Vol 64 (1) ◽  
pp. 46-52 ◽  
Author(s):  
A. M. Dubinin ◽  
V. G. Tuponogov ◽  
Y. A. Kagramanov
Keyword(s):  
Fluidized Bed ◽  
Coal Gasification ◽  
Circulating Fluidized Bed ◽  
Chamber Gas

Effect of bed temperature on bubble size and bubble rising velocity in a semi-cylindrical slugging fluidized bed.

1990 ◽  
Vol 23 (6) ◽  
pp. 765-767 ◽  
Author(s):  
Yasuo Hatate ◽  
Kazuya Ijichi ◽  
Yoshimitsu Uemura ◽  
Mitsunobu Migita ◽  
Desmond F. King
Keyword(s):  
Fluidized Bed ◽  
Bubble Size ◽  
Bed Temperature ◽  
Bubble Rising ◽  
Bubble Rising Velocity
Sign in / Sign up

Export Citation Format

Share Document