scholarly journals NOx EMISSIONS FROM BUBBLING FLUIDIZED BED COMBUSTION OF LIGNITE COAL

2015 ◽  
Vol 55 (4) ◽  
pp. 275 ◽  
Author(s):  
Pavel Skopec ◽  
Jan Hrdlička ◽  
Jan Opatřil ◽  
Jiří Štefanica
Keyword(s):  
Nitrogen Content ◽  
Fluidized Bed ◽  
Oxygen Concentration ◽  
Brown Coal ◽  
Conversion Factor ◽  
Nox Emissions ◽  
Fluidization Velocity ◽  
Bed Temperature ◽  
Bubbling Fluidized Bed ◽  
Air Staging

This paper presents experimental results of NO<sub>x</sub> emission measurements for combustion of two kinds of coal in a bubbling fluidized bed combustor. The tested fuels were Czech brown coal (CBC) and German young brown coal (GYC). These fuels have different nitrogen contents. The experiments were performed in the pilot scale BFB experimental unit with power output of 500 kW. The influence of several parameters on NO<sub>x</sub> formation are investigated in this paper. The parameters studied here include the effect of the nitrogen content in the fuel, the effect of the oxygen concentration in the bed, the effect of bed temperature, the effect of air staging, and the effect of fluidization velocity. Significantly different behaviour of the fuels was found. Although GYC has a lower nitrogen content than CBC, it is more reactive and produces higher NO<sub>x</sub> emissions. The biggest dependence of NO<sub>x</sub> production for CBC was found for the effects of air staging and fluidization velocity. As the fluidization velocity increases and the amount of secondary air decreases, there is an increase in NOx emissions. The oxygen concentration in the bed has the strongest effect on the NO<sub>x</sub> production of GYCs. With increasing oxygen concentration, the production of NO<sub>x</sub> also increases. On the basis of the NO<sub>x</sub> measurements, the N-NO conversion factor was calculated and the effect of the operating parameters on this conversion factor was investigated.

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.

An Experimental Study of the Gaseous Pollution Emissions in Petroleum-Coke-Fired Fluidized Beds

2003 ◽  
Author(s):  
Chun-Lin Zhang ◽  
Gui-Cheng Yuan ◽  
De-Chang Liu ◽  
Han-Ping Chen ◽  
Ding-Yu Liu ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Petroleum Coke ◽  
Calorific Value ◽  
Excess Oxygen ◽  
N2o Emissions ◽  
Bed Temperature ◽  
High Sulfur Content ◽  
Bubbling Fluidized Bed ◽  
Pollution Emissions ◽  
Gaseous Pollution

Petroleum cokes have high calorific value (about 37 MJkg−1), high sulfur content (2–7% wt.), and high nitrogen content (1∼3% wt.), introducing serious environmental problems when using as fuel. In this paper the effects of operating parameters (bed temperature, Ca/S mole ratio, and excess oxygen) on gaseous pollutant (SO2, NO, and N2O) emissions in a well-controlled bench scale fluidized bed reactor and an 1t/h bubbling fluidized bed for different type of petroleum cokes. Finally, the pollution emission differences between petroleum coke and coal were compared and the reasons were analyzed.

Pengurangan Pelepasan Emisi dari Pembakar Lapisan Terbendalir Menggunakan Tempurung Kelapa Sawit Sebagai Bahan Api

2012 ◽  
pp. 07-11
Author(s):  
Mohammad Nazri Mohd Jaafar ◽  
Rosyida Permatasari ◽  
Mohd Nazar Yakin Mohd Sobree
Keyword(s):  
Fluidized Bed ◽  
Fuel Oil ◽  
Silica Sand ◽  
Nox Emissions ◽  
Fuel Feed ◽  
Bed Height ◽  
Excess Air ◽  
Axial Temperature ◽  
Fluidized Bed Combustor ◽  
Air Staging

Emissions released from fluidized bed combustor (FBC) are highly dependent on several operating parameters, for example, temperature, staged air, excess air, fuel feed rate, and fuel properties. This paper presents results of experiments conducted using air staging technique on a laboratory scale fluidized bed rig, using palm shells as fuel oil and silica sand as an inert medium. Silica sand was used to ensure a sustainable fuel ignition and stable combustion occurs in the FBC. Emission of CO and NOx emissions, and temperatures along the height of the bed and flue were measured. The experimental results show that the axial temperature profile along the height was proportionally reduced with bed height of FBC. CO and NOx emissions obtained exhibit lower values for the air staged combustion. Pelepasan emisi dari pembakar lapisan terbendalir (FBC) adalah sangat bergantung kepada beberapa parameter kendalian sebagai contoh: suhu, udara berperingkat, udara berlebihan, kadar suapan bahan api, dan sifat bahan api. Kertas kerja ini mempersembahkan keputusan eksperimen yang dilaksanakan menggunakan teknik pemeringkatan udara ke atas rig lapisan terbendalir skala makmal, menggunakan tempurung kelapa sawit sebagai bahan api dan pasir silika sebagai bahan perantara lengai. Pasir silica telah digunakan untuk memastikan pencucuhan bahan api mampan dan pembakaran stabil berlaku di dalam FBC. Pelepasan gas emisi CO dan NOx serta suhu sepanjang ketinggian pembakar dan juga dalam serombong diukur. Keputusan ujikaji menunjukkan bahawa profil suhu paksi berkurangan secara berkadaran sepanjang ketinggian FBC. Pelepasan CO dan NOx yang diperolehi mempamerkan nilai yang lebih rendah untuk keadaan pembakaran dengan pemeringkatan udara.

Effect of the Shape of the Baffles on the Hydrodynamics of a Fluidized Bed

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Srinivasa Rao Venkata Naga Kaza
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Gas Flow ◽  
Experimental Studies ◽  
Expansion Ratio ◽  
Blockage Ratio ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Bubbling Fluidized Bed

Gas flow in a gas–solid fluidized bed is characterized by the predominance of bubbles. When gas flow is more than the minimum fluidization velocity, the top of the fluidized bed may fluctuate vigorously leading to unstable operation. Bed fluctuation and fluidization quality are interrelated. The quality of fluidization can largely be improved by introducing baffles in bubbling and turbulent fluidized beds. In the present work three baffle geometries, i.e., circular, triangular and square are used to determine different hydrodynamic parameters such as minimum fluidization velocity, bed expansion, pressure drop across the bed, fluctuation ratio, expansion ratio, etc. in a bubbling fluidized bed. A new parameter blockage ratio is introduced to analyze the behaviour of baffled fluidized beds. It is found from the current experimental studies that the blockage ratio mainly influences the hydrodynamics of the bed rather than the shape of the baffle.

Minimum Air Fluidization Velocity Study of Specific 2-D Bubbling Fluidized Bed Reactor

2014 ◽  
Vol 699 ◽  
pp. 660-665
Author(s):  
M. Fadhil ◽  
M.S. Aris ◽  
A.H. Abbas ◽  
A.B.A. Ibrahim ◽  
N. Aniza
Keyword(s):  
Fluidized Bed ◽  
Particle Density ◽  
Flow Behavior ◽  
Numerical Approach ◽  
Combustion Efficiency ◽  
Fluidized Bed Combustion ◽  
Fluidization Velocity ◽  
Bubbling Fluidized Bed ◽  
Flow Through ◽  
Bed Expansion

Research on the thermodynamic behavior of sand beds was carried out using a commercial computational dynamic package. The work involved simulating, with the use of the Ergun equation, the air flow through a two-dimensional bubbling bed reactor to predict the bed character whilst considering the major effective function (particle size, particle density, bed height and reactor width). The Minimum Fluidization Velocity (Umf) values were then calculated before the optimum value of Umfneeded to ensure a workable Bubbling Fluidize Bed Combustor (BFBC) system. The effects of using different Umfvalues on the flow behavior were also investigated using the numerical approach at different times. The results from these investigations indicate that the bubbling region in the fluidized bed combustion can be correlated to the sand bed expansion with minimum errors and assist in enhancing the combustion efficiency by supplying the required volume of oxygen into the system.

Cofiring low-rank coal and biomass in a bubbling fluidized bed with varying excess air ratio and fluidization velocity

Energy ◽  
2020 ◽  
Vol 203 ◽  
pp. 117882 ◽  
Author(s):  
Paulo R. Wander ◽  
Flávio M. Bianchi ◽  
Nattan R. Caetano ◽  
Marcos A. Klunk ◽  
Maria Luiza S. Indrusiak
Keyword(s):  
Fluidized Bed ◽  
Low Rank ◽  
Low Rank Coal ◽  
Fluidization Velocity ◽  
Excess Air ◽  
Bubbling Fluidized Bed
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