Measurement of gas species, temperatures, char burnout, and wall heat fluxes in a 200-MWe lignite-fired boiler at different loads

Li, Zhengqi; Jing, Jianping; Liu, Guangkui; Chen, Zhichao; Liu, Chunlong

doi:10.1016/j.apenergy.2009.05.035

Cited by 43 publications

(10 citation statements)

References 20 publications

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“…Accordingly, much attention has been devoted to optimize the combustion systems 14,21–23 . However, previous numerical studies have been mainly concentrated on NO x emissions and combustion characteristics under different air‐staging conditions, whereas less attention has been paid to the heat flux distributions of water‐cooled walls 24–27 . In addition, knowledge about the heat flux distributions is essential for the accurate prediction of temperature distribution based on the hydrodynamic calculation.…”

Section: Introductionmentioning

confidence: 99%

“…14,[21][22][23] However, previous numerical studies have been mainly concentrated on NO x emissions and combustion characteristics under different air-staging conditions, whereas less attention has been paid to the heat flux distributions of water-cooled walls. [24][25][26][27] In addition, knowledge about the heat flux distributions is essential for the accurate prediction of temperature distribution based on the hydrodynamic calculation. At present, the calculation standard in 1983 (Zhou et al 28 ) is adopted to conduct the hydrodynamic calculation in China.…”

mentioning

confidence: 99%

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Numerical study on combustion characteristics and heat flux distributions of 660‐MW ultra‐supercritical double‐reheat tower‐type boiler

Deng

Zhang

et al. 2021

Asia-Pacific J Chem Eng

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Ultra‐supercritical double‐reheat technology, as one of the most advanced coal‐fired power generation technology, is an important direction for emission reduction and energy saving in the world. In this study, the numerical calculation was executed in a 660‐MW ultra‐supercritical double‐reheat tower‐type boiler under deep‐air‐staging conditions. The refined HCN oxidation model was adopted to substitute the default model implemented by the user‐defined functions to calculate the NOx emission. The influences of the boiler load, over‐fire air (OFA) ratio, and excess air coefficient on temperature, species, and heat flux distributions were investigated. Results show that the decrement of the boiler load from boiler maximum continuous rating to 50% turbine heat acceptance gives rise to an increase of NOx emission. The heat flux distributions along with the furnace width direction present bell shaped. When the OFA ratio rises from 17% to 43%, NOx emission descends from 357.7 to 179.3 mg m−3 at the furnace outlet, and the heat flux distributions become more uniform along with the furnace width direction with lower peaks. Temperatures, species, and heat flux distributions are similar under the three different excess air coefficients. The NOx emission is the lowest when the excess air coefficient is 1.15. The results could provide a reference for combustion characteristics optimization and hydrodynamic calculation of ultra‐supercritical double‐reheat tower‐type boiler.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Numerical study on combustion characteristics and heat flux distributions of 660‐MW ultra‐supercritical double‐reheat tower‐type boiler

Deng

Zhang

et al. 2021

Asia-Pacific J Chem Eng

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“…The char burnout ratio can be an indicator of the combustion efficiency, because volatile matter from coal devolatilization is combusted completely inside the furnace in all three scenarios, assuming clean wall conditions in the furnace. The char burnout ratio was calculated using the following equation [20,21]:…”

Section: Char Burnout Charactersmentioning

confidence: 99%

CFD Approach for Unburned Carbon Reduction in Pulverized Coal Boilers

Jun

Jankowski²,

Kotecki³

et al. 2012

Energy Fuels

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Low-NOx technologies are widely used in pulverized coal boilers, but they usually produce high levels of carbon in the fly ash. High levels of unburned carbon represent fuel loss, so the overall boiler efficiency is reduced. Additionally, the higher carbon content affects the suitability of fly ash for cement applications. The purpose of this paper is to provide a CFD approach for unburned carbon reduction by optimizing operating conditions. In this paper, three different boiler loads were simulated: 200 MW, 170 MW, and 140 MW. The air supply system was simulated previously for preparing as precise as possible boundary conditions. At last, unburned carbon level of every burner was investigated, and the effects of residue residence time and the local fuel-air momentum ratio are discussed in detail. According to the predicted results, operating conditions and the residence time of the coal particles affects the unburned carbon level in fly ash. Operating conditions plays a more significant role during the combustion process, while the residence time affects char burnout only when the burner's location is low. Therefore, it is concluded that a cost effective method could be developed for reducing the unburned carbon level in ash and correspondingly, the loss on ignition level. First, it is necessary to determine which burners are operating under poor conditions through CFD analysis. Then, the fuel air momentum ratios of those burners should be modified by changing the operating conditions, meanwhile, increasing residence time of coal particles to ensure complete combustion.

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“…As low-rank coal, lignite generally features high water (25-60% by weight) and volatile contents but low net heating value. Thus lignite fired power plants consume more coal as compared to bituminous-coal fired power plants with the same electric power outputs, which translates to a concomitant increase in Green House Gases (GHG) emissions [4][5][6]. In addition, a lignite fired boiler with a relatively high exhaust flue gas temperature leads to a greater heat loss of the flue gas and further lowers the efficiency and economics of the lignite fired power plant.…”

Section: Introductionmentioning

confidence: 97%

An improved configuration of lignite pre-drying using a supplementary steam cycle in a lignite fired supercritical power plant

Cheng

Zhao

et al. 2015

Applied Energy

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h i g h l i g h t sAn improved lignite pre-drying using a supplementary steam cycle is proposed. Thermodynamic and economic analyses are quantitatively conducted. Lower exergy destruction and better matched energy level are obtained. Higher energy efficiency improvement and greater economic benefits are achieved. a b s t r a c tA novel concept of improved configuration of lignite pre-drying using a supplementary steam cycle incorporated in a lignite fired supercritical power plant was proposed in this study. Differing from the conventional lignite pre-drying power plant configuration, in this lignite pre-drying power plant (LPDPP) concept, the steam bleeds for the dryer and some regenerative heaters (RHs) are redirected from the high pressure turbines and low pressure turbines through a separate turbine named the Regenerative-turbine (R-turbine). With the R-turbine in place, the degree of super-heating of the bleeds for the dryer and for RH3-RH5 is significantly reduced, thus leading to a reduction in the heat transfer temperature difference and exergy destruction rate. The net energy efficiency and the economic benefits of the proposed LPDPP are also enhanced as compared to the conventional configuration. The analysis showed that, for a 600 MW supercritical LPDPP, the exergy destruction of the dryer could be reduced from 14.23 MW th in the conventional configuration to 13.25 MW th in the proposed design. The net energy efficiency could be further improved by 0.3 percentages points with a heat rate reduction of approximately 59.4 kJ/kW h. The net economic benefit of the proposed LPDPP could reach $47.6 M per year, which is $0.9 M greater than that of the conventional lignite pre-drying unit.

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Measurement of gas species, temperatures, char burnout, and wall heat fluxes in a 200-MWe lignite-fired boiler at different loads

Cited by 43 publications

References 20 publications

Numerical study on combustion characteristics and heat flux distributions of 660‐MW ultra‐supercritical double‐reheat tower‐type boiler

Numerical study on combustion characteristics and heat flux distributions of 660‐MW ultra‐supercritical double‐reheat tower‐type boiler

CFD Approach for Unburned Carbon Reduction in Pulverized Coal Boilers

An improved configuration of lignite pre-drying using a supplementary steam cycle in a lignite fired supercritical power plant

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