Emission Control of Gaseous Pollutants From Co-Firing of Petroleum Coke and Coal in CFB

2003 ◽  
Author(s):  
Changsui Zhao ◽  
Wenxuan Wang ◽  
Fengjun Wang ◽  
Chuanmin Chen ◽  
Song Han
Keyword(s):  
Petroleum Coke ◽  
Circulating Fluidized Bed ◽  
Pilot Scale ◽  
Molar Ratio ◽  
Gaseous Pollutants ◽  
Emission Characteristic ◽  
Sources Of Pollution ◽  
Excess Air ◽  
Bed Temperature ◽  
Fuel Mixtures

Petroleum cokes including delayed coke, fluid coke, etc. are byproducts of solid residuals from the crude refining process. Using high sulfur petroleum coke as alternative fuel is feasible owing to its high fixed carbon and low ash content, but petroleum cokes are difficult to ignite due to their low volatile content and containing substantial concentrations of vanadium, nickel, nitrogen and sulfur, which can be sources of pollution emission and fireside fouling or corrosion problem. Co-firing petroleum coke and coal in circulating fluidized bed (CFB) is an ideal solution for those problems. Emission characteristic of gaseous pollutants from co-firing petroleum coke and coal is investigated in the paper. Experiments were carried out in a 0.6 MWt pilot-scale CFB combustor with the total height of 12m from the air distributor to the exit of combustor. The concentrations of SO2, NO, N2O, O2, CO2 and CO were measured on line by the gas analyzer. The effect of several parameters, in term of the primary air percentage, air excess coefficient, bed temperature, Ca/S molar ratio and percentage of petroleum coke in mixed fuel on the emission of SO2, NO, N2O is verified in experiments. Experimental results show that SO2 concentration in flue gas reduces with increase in the primary air percentage, excess air coefficient and Ca/S ratio for all kinds of fuel mixtures, whereas NO, N2O concentration rises with increase in the primary air percentage and excess air. When the bed temperature changes, the NO concentration varying trend is opposite to N2O. There is an optimal temperature for sulfur retention. Co-firing of petroleum coke and coal with different mixing ratio in CFB can be stable, efficient and environment friendly.

Combustion Behavior and SO2, NOx Emissions of an Anthracite Coal in a Circulating Fluidized Bed

2005 ◽  
Author(s):  
Leming Cheng ◽  
Zhongyang Luo ◽  
Zhenglun Shi ◽  
Haixiao Zheng ◽  
Qinghui Wang ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Cross Section ◽  
Circulating Fluidized Bed ◽  
Nox Emissions ◽  
So2 Emission ◽  
Combustion Behavior ◽  
Excess Air ◽  
Anthracite Coal ◽  
Bed Temperature ◽  
Experimental Researches

Combustion behavior and SO2, NOx emissions of anthracite coal in a circulating fluidized bed are reported in this paper. Experimental researches were done on a 1 MWt circulating fluidized bed facility with a 0.31 m × 0.31 m cross section and 11.2 m height combustor. The anthracite coal with 6.28% volatile and 3.76% sulfur content burns steadily during the test. The bed was operated under different temperature, Ca/S ratio and excess air. A limestone containing 75% CaCO3 and 15% MgCO3 was used as the sulfur sorbent. Results show that the SO2 emission varies with operating bed temperature and more than 90% sulfur capture efficiency can be reached while Ca/S is about 3. With Rosemount Analytical NGA2000, N2O, NO and NO2 were also measured in the test. It was found the majority content of NOx was NO and the least was NO2. Those NOx emissions change highly with the excess air number.

Optimizing Ammonia Injection in Bio-Fuelled CFBCs

2005 ◽  
Author(s):  
Edgardo Coda Zabetta ◽  
Patrik Yrjas ◽  
Mikko Hupa ◽  
Juha Roppo ◽  
Marko Nylund
Keyword(s):  
Circulating Fluidized Bed ◽  
Nox Reduction ◽  
Fuel Mixture ◽  
Molar Ratio ◽  
N2o Emissions ◽  
Detailed Chemical Kinetics ◽  
Maximum Reduction ◽  
Ideal Mixing ◽  
Fuel Mixtures ◽  
Ammonia Injection

The reduction of nitrogen oxides (NOx) via ammonia injection (NH3) was investigated for circulating fluidized bed combustors (CFBCs) fuelled with mixtures of coal, peat, wood, bark, and logging residues. The reference boiler was the Alholmen Kraft, i.e. the largest co-fired unit in the world (550 MWth, 194 kg/s, 165 bar, 545 °C). The boiler featured ammonia injectors at the cyclone. Fuel composition, gas composition, and temperature were measured at suitable locations along the boiler while operating with diverse fuel mixtures. A chemical model was developed for analyzing the NOx reduction and was validated against measurements. The model accounts for the elemental composition of fuels, the composition of gases at the cyclone and in the stack, and the profile of temperature from cyclone to stack. The chemical reactions downstream the ammonia injection are described by gas-phase detailed chemical kinetics and accounting for ideal mixing. Measurements and simulations reveal that NOx reductions of over 50% are achievable for any fuel mixture and with moderate amounts of ammonia. Reductions are mainly affected by the temperature. All simulations show the existence of a maximum reduction vs. temperature, whose extent and location is affected by the concentrations of CO, NO, and the molar ratio [NH3]injected/[NO]cyclone. Simulations also indicate that with fuel mixtures other than the mixtures used in the reference boiler the maximum reduction is also affected by the concentrations of H2O, O2, CxHy, and N2O. Finally, simulations suggest an additional strategy for reducing emissions in co-fired CFBCs, where the N2O formed from coal is used to support the NOx reduction by ammonia, thus reducing NOx while maintaining acceptable N2O emissions. Further investigation is necessary for clarifying the details of this strategy. Under all circumstances, the only N-based pollutants predicted in detectable amounts are NO and N2O.

Study on Burnout and so2 Emission Characteristics during Co-Combustion of Petroleum Coke and Oil Shale in a Fluidized Bed

2011 ◽  
Vol 55-57 ◽  
pp. 1547-1553
Author(s):  
Wei Qun Lu ◽  
Ding Ye Fang ◽  
Zhi Yong Yang
Keyword(s):  
Fluidized Bed ◽  
Petroleum Coke ◽  
Oil Shale ◽  
Molar Ratio ◽  
Thermal Engineering ◽  
Mixing Ratio ◽  
Mixed Fuel ◽  
Bed Temperature ◽  
Desulfurization Efficiency ◽  
Fuel Mixing

The effects of several factors, including fuel mixing ratio fed into boiler, bed temperature, primary air ratio, on burnout characteristics of mixed fuel of petroleum coke and oil shale were investigated at a 1 MW circulating fluidized bed (CFB) test apparatus at Xi’an Thermal Engineering Research Institute. Meantime, the effect of the fuel mixing ratio and Ca/S molar ratio on SO2 emission during co-combustion of petroleum coke and oil shale were studied. The results show that preferred mixing ratio of petroleum coke over oil shale is between 4:6 and 5:5, and primary air ratio is about 55% to accomplish favorable burnout of the mixed fuel. The combustion efficiency is higher than 97%. The increase in oil shale share in the mixture helps to improve the desulfurization efficiency during co-combustion. There is an optimum Ca/S molar ratio to achieve the highest desulfurization efficiency for co-firing the petroleum coke and oil shale. SO2 emission during co-combustion of petroleum coke and oil shale can meet the environmental requirement.

Pilot-scale combustion studies with kraft lignin in a powder burner and a CFB boiler

TAPPI Journal ◽  
2010 ◽  
Vol 9 (6) ◽  
pp. 24-30 ◽  
Author(s):  
NIKLAS BERGLIN ◽  
PER TOMANI ◽  
HASSAN SALMAN ◽  
SOLVIE HERSTAD SVÄRD ◽  
LARS-ERIK ÅMAND
Keyword(s):  
Circulating Fluidized Bed ◽  
Black Liquor ◽  
Chloride Content ◽  
Pilot Scale ◽  
High Energy ◽  
Kraft Lignin ◽  
High Energy Density ◽  
Alkali Chloride ◽  
Cfb Boiler ◽  
Solid Biofuel

Processes have been developed to produce a solid biofuel with high energy density and low ash content from kraft lignin precipitated from black liquor. Pilot-scale tests of the lignin biofuel were carried out with a 150 kW powder burner and a 12 MW circulating fluidized bed (CFB) boiler. Lignin powder could be fired in a powder burner with good combustion performance after some trimming of the air flows to reduce swirl. Lignin dried to 10% moisture content was easy to feed smoothly and had less bridging tendencies in the feeding system than did wood/bark powder. In the CFB boiler, lignin was easily handled and cofired together with bark. Although the filter cake was broken into smaller pieces and fines, the combustion was not disturbed. When cofiring lignin with bark, the sulfur emission increased compared with bark firing only, but most of the sulfur was captured by calcium in the bark ash. Conventional sulfur capture also occurred with addition of limestone to the bed. The sulfur content in the lignin had a significantly positive effect on reducing the alkali chloride content in the deposits, thus reducing the high temperature corrosion risk.

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.

Ignition characteristics of co-fired mixtures of petroleum coke and bituminous coal in a pilot-scale furnace

Fuel ◽  
2012 ◽  
Vol 97 ◽  
pp. 315-320 ◽  
Author(s):  
B.R. Clements ◽  
Q. Zhuang ◽  
R. Pomalis ◽  
J. Wong ◽  
D. Campbell
Keyword(s):  
Petroleum Coke ◽  
Bituminous Coal ◽  
Pilot Scale ◽  
Ignition Characteristics

Carbon dioxide purity and combustion characteristics of oxy firing compared to air firing in a pilot-scale circulating fluidized bed

Energy ◽  
2019 ◽  
Vol 166 ◽  
pp. 183-192 ◽  
Author(s):  
Ji-Hong Moon ◽  
Sung-Ho Jo ◽  
Sung Jin Park ◽  
Nguyen Hoang Khoi ◽  
Myung Won Seo ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pilot Scale ◽  
Combustion Characteristics

Sulphur Neutralization by Lignite Ash: Pilot-Scale Combustion Experiments

1979 ◽  
Vol 101 (4) ◽  
pp. 615-619 ◽  
Author(s):  
T. D. Brown ◽  
G. K. Lee ◽  
H. A. Bambrough
Keyword(s):  
Nitric Oxide ◽  
Flue Gas ◽  
Solid Phase ◽  
Coal Ash ◽  
Pilot Scale ◽  
Controlled Experiments ◽  
Excess Air ◽  
Nitric Oxide Emissions ◽  
Carry Over ◽  
Lime Addition

A pilot-scale research boiler (750 kg steam/hr) has been used to study the degree of sulphur neutralization during combustion experiments with three lignites. A series of four closely controlled experiments showed that sulphur balances close to 100 percent could be achieved in the pilot-scale system burning Gascoyne lignite; in these experiments the sulphur retained in solid phase residues varied between 21 and 24 percent of the input sulphur. It was also demonstrated with Utility lignite that external recirculation of flue-gas was moderately effective in reducing nitric oxide emissions at the expense of major increased in the carry-over of unburnt carbon. However, sulphur dioxide neutralization by the coal-ash cations remained essentially unchanged as the recirculation ratio increased. Enhancement of sulphur neutralization by dry lime addition to Poplar River lignite was only found to be effective at addition rates above 1/2 percent lime by weight. The effectiveness of the lime was found to increase as the excess-air level increased.

Identification of Circulating Fluidized Bed Boiler Bed Temperature Based on Hyper-Plane-Shaped Fuzzy C-Regression Model

2020 ◽  
Vol 19 (04) ◽  
pp. 2050029
Author(s):  
Jianzhong Shi
Keyword(s):  
Regression Model ◽  
Fluidized Bed ◽  
Membership Function ◽  
Clustering Algorithm ◽  
Circulating Fluidized Bed ◽  
Fuzzy Model ◽  
Identification Algorithm ◽  
Identification Process ◽  
Bed Temperature ◽  
Hyper Plane

Bed temperature in dense-phase zone is the key parameter of circulating fluidized bed (CFB) boiler for stable combustion and economic operation. It is difficult to establish an accurate bed temperature model as the complexity of circulating fluidized bed combustion system. T-S fuzzy model was widely applied in the system identification for it can approximate complex nonlinear system with high accuracy. Fuzzy c-regression model (FCRM) clustering based on hyper-plane-shaped distance has the advantages in describing T-S fuzzy model, and Gaussian function was adapted in antecedent membership function of T-S fuzzy model. However, Gaussian fuzzy membership function was more suitable for clustering algorithm using point to point distance, such as fuzzy c-means (FCM). In this paper, a hyper-plane-shaped FCRM clustering algorithm for T-S fuzzy model identification algorithm is proposed. The antecedent membership function of proposed identification algorithm is defined by a hyper-plane-shaped membership function and an improved fuzzy partition method is applied. To illustrate the efficiency of the proposed identification algorithm, the algorithm is applied in four nonlinear systems which shows higher identification accuracy and simplified identification process. At last, the algorithm is used in a circulating fluidized bed boiler bed temperature identification process, and gets better identification result.

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