98/01501 Monitoring of the combustion heat of fuel gas and excess air coefficient by flame electroconductivity

1998 ◽  
Vol 39 (2) ◽  
pp. 132
Keyword(s):  
Combustion Heat ◽  
Fuel Gas ◽  
Excess Air ◽  
Excess Air Coefficient

Numerically Study on Combustion and NOx Emission Characteristics in Tangentially Fired Boiler Co-Firing Semi-Coke

2018 ◽  
Author(s):  
Yongbo Du ◽  
Chang'an Wang ◽  
Pengqian Wang ◽  
Qiang Lv ◽  
Defu Che
Keyword(s):  
Bituminous Coal ◽  
Combustion Efficiency ◽  
Low Rank ◽  
Operation Performance ◽  
Combustion Heat ◽  
Practical Utilization ◽  
Excess Air ◽  
Utility Boilers ◽  
Excess Air Coefficient ◽  
Char Burnout

Semi-coke is a specific solid fuel, which is mainly produced by upgrading low-rank coal. The poor reactivity of semi-coke makes a difficulty to its practical utilization in utility boilers. Previous research was mainly focused on the combustion behavior of semi-coke, while the industrial application has to be understood. In this paper, the effect of co-firing semi-coke and bituminous coal on the operation performance of pulverized boiler was numerically studied. The work was conducted on a 300 MW tangentially fired boiler, and the temperature distribution, the char burnout and NOx production were mainly examined. The results indicate that the incomplete combustion heat loss drops with the increase in semi-coke blending ratio. The NOx concentration increases from 186 mg/Nm3 for only firing the bituminous coal to 200, 214, and 255 mg/Nm3, when the blending ratio was 17%, 33% and 50%, respectively. With enhancing excess air coefficient for the co-firing condition, the combustion efficiency got improved, while NOx production increased very slightly. In general, the boiler is well adapted to co-firing semi-coke, and the semi-coke blending ratio of 1/3 with an excess air coefficient of 1.235 is recommended.

Optimized Operation of Boiler

2014 ◽  
Vol 960-961 ◽  
pp. 399-404
Author(s):  
Chang Liu
Keyword(s):  
Heat Loss ◽  
Power Plants ◽  
Thermal Power ◽  
Optimal Operation ◽  
Operating Efficiency ◽  
Combustion Heat ◽  
Correlative Analysis ◽  
Excess Air ◽  
Boiler Efficiency ◽  
Excess Air Coefficient

This paper studies the problem of optimal operation of 300MW boiler. We combine the actual situation of the device and the theory of heat together, and improve the operating efficiency of the boiler through adjustment of device parameters, thus improving the economic benefit of thermal power plants. Firstly, according to coal characteristics and the theory of heat, we establish an improved utility model to calculate the heat loss of exhaust - gas, chemical incomplete combustion heat loss and heat loss of mechanical incomplete combusting. Then, we use fitting and interpolation, which is always applied to problems of Discrete Mathematical Statistics, to analyze discrete form of experiment data record, and give the relationship between 300MW boiler efficiency and excess air coefficient, which leads us to a new way to ascertain optimal excess air coefficient. And then, we use Principal Components Analysis (PCA) and Correlative Analysis (CA) to study the affection of operation parameters on boiler efficiency. Finally, we combine local optimization with global optimization, and establish an optimal operational model.

The Optimal Operation Problem of Boilers

2014 ◽  
Vol 953-954 ◽  
pp. 1454-1458
Author(s):  
Cong Sun
Keyword(s):  
Heat Loss ◽  
Optimal Operation ◽  
Combustion Heat ◽  
Incomplete Combustion ◽  
Excess Air ◽  
Exhaust Heat ◽  
Excess Air Coefficient ◽  
Main Factors ◽  
The Relationship

Boiler optimum efficiency problem can be solved by optimum excess air coefficient model. It is the key to find the relationship between main factors and the excess air coefficient. These main factors are smoke exhaust heat losschemistry incomplete combustion heat loss and mechanical incomplete combustion heat loss.In this paper, we projected the relationship between the factors and the excess air coefficient by using the computational formulas of principles of boiler. Then we synthesized the three formulas to establish the excess air coefficient model. Finally, this paper geted the optimum excess air coefficient using extremum method.That is αp=1.152596.

Modeling and Experiment on Combustion Characteristics for Biomass Rotary Burner

2020 ◽  
Vol 04 ◽  
Author(s):  
Guohai Jia ◽  
Lijun Li ◽  
Li Dai ◽  
Zicheng Gao ◽  
Jiping Li
Keyword(s):  
Combustion Chamber ◽  
Combustion Temperature ◽  
Combustion Efficiency ◽  
Middle Part ◽  
Combustion Characteristics ◽  
Maximum Temperature ◽  
Excess Air ◽  
Element Simulation ◽  
Excess Air Coefficient ◽  
Secondary Air

Background: A biomass pellet rotary burner was chosen as the research object in order to study the influence of excess air coefficient on the combustion efficiency. The finite element simulation model of biomass rotary burner was established. Methods: The computational fluid dynamics software was applied to simulate the combustion characteristics of biomass rotary burner in steady condition and the effects of excess air ratio on pressure field, velocity field and temperature field was analyzed. Results: The results show that the flow velocity inside the burner gradually increases with the increase of inlet velocity and the maximum combustion temperature is also appeared in the middle part of the combustion chamber. Conclusion: When the excess air coefficient is 1.0 with the secondary air outlet velocity of 4.16 m/s, the maximum temperature of the rotary combustion chamber is 2730K with the secondary air outlet velocity of 6.66 m/s. When the excess air ratio is 1.6, the maximum temperature of the rotary combustion chamber is 2410K. When the air ratio is 2.4, the maximum temperature of the rotary combustion chamber is 2340K with the secondary air outlet velocity of 9.99 m/s. The best excess air coefficient is 1.0. The experimental value of combustion temperature of biomass rotary burner is in good agreement with the simulation results.

Effect of thermal input, excess air coefficient and combustion mode on natural gas MILD combustion in industrial-scale furnace

Fuel ◽  
2021 ◽  
Vol 302 ◽  
pp. 121179
Author(s):  
Mingming Huang ◽  
Ruichuan Li ◽  
Jikang Xu ◽  
Shen Cheng ◽  
Haoxin Deng ◽  
...  
Keyword(s):  
Natural Gas ◽  
Industrial Scale ◽  
Combustion Mode ◽  
Mild Combustion ◽  
Excess Air ◽  
Excess Air Coefficient

Effects of Air Flowrate on the Combustion and Emissions of Blended Corn Straw and Pinewood Wastes

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Xiaoxiao Meng ◽  
Wei Zhou ◽  
Emad Rokni ◽  
Honghua Zhao ◽  
Rui Sun ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ignition Delay Time ◽  
Fixed Bed ◽  
Combustion Efficiency ◽  
Fixed Bed Reactor ◽  
Corn Straw ◽  
Excess Air ◽  
Burning Rates ◽  
Excess Air Coefficient ◽  
Hazardous Pollutants

This research investigated the effects of the specific primary (under-fire) air flowrate (m˙air) on the combustion behavior of a 50–50 wt % blend of raw corn straw (CS) and raw pinewood wastes in a fixed-bed reactor. This parameter was varied in the range of 0.079–0.226 kg m−2 s−1, which changed the overall combustion stoichiometry from air-lean (excess air coefficient λ = 0.73) to air-rich (excess air coefficient λ = 1.25) and affected the combustion efficiency and stability as well as the emissions of hazardous pollutants. It was observed that by increasing m˙air, the ignition delay time first increased and then decreased, the average bed temperatures increased, both the average flame propagation rates and the fuel burning rates increased, and the combustion efficiencies also increased. The emissions of CO as well as those of cumulative gas phase nitrogen compounds increased, the latter mostly because of increasing HCN, while those of NO were rather constant. The emissions of HCl decreased but those of other chlorine-containing species increased. The effect of m˙air on the conversion of sulfur to SO2 was minor. By considering all of the aforesaid factors, a mildly overall air-rich (fuel-lean) (λ = 1.04) operating condition can be suggested for corn-straw/pinewood burning fixed-bed grate-fired reactors.

Numerical Simulation on Moisture Influence to MSW Combustion

2014 ◽  
Vol 1006-1007 ◽  
pp. 181-184
Author(s):  
Zhu Sen Yang ◽  
Xing Hua Liu ◽  
Shu Chen
Keyword(s):  
Numerical Simulation ◽  
Moisture Content ◽  
Flue Gas ◽  
Combustion Process ◽  
Average Temperature ◽  
Excess Air ◽  
Heat Value ◽  
Moisture Influence ◽  
Excess Air Coefficient ◽  
Combustible Gases

The combustion process of municipal solid waste (MSW) in a operating 750t/d grate furnace in Guangzhou was researched by means of numerical simulation. The influence of MSW moisture content on burning effect was discussed. The results show that: with the moisture content dropped from 50% to 30%, the heat value could be evaluated from 13.72% to 54.91% and the average temperature in the furnace could be promoted 90-248°C. However, the combustible gases and particle in the flue gas of outlet would take up a high proportion since lacking of oxygen would lead to an incomplete combustion. The excess air coefficient should be increased to 2.043~2.593 in order to ensure the flue gas residence time more than 2s and temperature in the furnace higher to 800°C.

scholarly journals THE INFLUENCE OF THE COMPOSITION AND PARAMETERS OF THE OIL GAS SUPPLY ON THE COMBUSTION LIMITS IN THE COMBUSTION CHAMBER

2020 ◽  
pp. 64-71
Author(s):  
Alyona Shilova ◽  
◽  
Roman Bulbovich ◽  
Nikolay Bachev ◽  
Oleg Matyunin ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Power Plants ◽  
Central Place ◽  
Combustion Stability ◽  
Fuel Gas ◽  
Micro Gas Turbine ◽  
Gas Utilization ◽  
Excess Air ◽  
Combustion Limits ◽  
Oil Gas

The question of oil gas utilization today is very important.In the development of domestic micro-gas-turbine utilization power plants, the central place is occupied by the creation of a universal combustion chamber, which would ensure stable combustion of ballasted gases at different fields under variable operating conditions.In this work, the phlegmatization method was used to determine the lower and upper concentration limits, which allows taking into account the effect of ballasting components on the combustion limits. When calculating the coefficients of excess air at the upper and lower limits, the influence of the composition, temperature, and supply pressure of the components was taken into account.An analysis of the results showed that taking into account the parameters of air and oil gas at the outlet of the compressors expands the limits of combustion by the coefficient of excess air. An additional regenerative heating of the air between the compressor and the combustion chamber shifts the combustion stability region in terms of the excess air coefficient towards rich mixtures. Recuperative heating of fuel gas shifts the area of sustainable combustion towards lean mixtures. Simultaneous regenerative heating of fuel gas and air expands the area of sustainable combustion.

scholarly journals Modeling of the Thermal Efficiency of a Whole Cement Clinker Calcination System and Its Application on a 5000 MT/D Production Line

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5257
Author(s):  
Yanfei Yao ◽  
Songxiong Ding ◽  
Yanxin Chen
Keyword(s):  
Calcium Carbonate ◽  
Thermal Efficiency ◽  
Production Line ◽  
Cement Clinker ◽  
Specific Process ◽  
Excess Air ◽  
Positive Linear Correlation ◽  
Excess Air Coefficient ◽  
Secondary Air ◽  
The Relationship

This paper proposes that the scope of research should be extended to the whole clinker calcination system from its single device or specific process (i.e., its functional subunits) as conventionally conducted. Mass/heat flow and effective heat were first analyzed to obtain the thermal efficiencies of its subunits (φi); a thermal efficiency model of the whole system φQY was thus established by correlating the relationship between φi and φQY. The thermal efficiency model of the whole system showed that φi had a positive linear correlation with φQY; it was found that the thermal efficiency of the decomposition and clinker calcination unit (φDC) had the greatest weight on φQY, where a 1% increase in φDC led to a 1.73% increase in φQY—improving φDC was shown to be the most effective way to improve φQY. In this paper, the developed thermal efficiency model was applied to one 5000 MT/D production line. It was found that its φQY was only 61.70%—about 2.35% lower than a representative line; such decrease was caused by its low φDC and φP which, as disclosed by model, were derived from the low decomposition rate of calcium carbonate in preheated meal put into a calciner and the high excess air coefficient of secondary air. Controlled parameter optimization of this 5000 MT/D production line was then carried out. As a result, the φDC and φP of the production line were increased from 30.03% and 64.61% to 30.69% and 65.69%, respectively; the φQY increased from 61.70% to 62.55%; the clinker output of the production line increased from 5799 MT/D to 5968 MT/D; the heat consumption of clinker was reduced from 3286.98 kJ/kg·cl to 3252.41 kJ/kg·cl.

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