Analysis and simulation of a flue gas flow model with a 90 rectangular large-diameter bend

Corrosion of boiler tubes remains an operational and economic limitation in municipal waste power plants. The understanding of the nature, mechanism, and related factors can help reduce the degradation process caused by corrosion. The chlorine content in the fuel has a significant effect on the production of gaseous components (e.g., HCl) and condensed phases on the chloride base. This study aimed to analyze the effects of flue gases on the outer surface and saturated steam on the inner surface of the evaporator tube. The influence of gaseous chlorides and sulfates or their deposits on the course and intensity of corrosion was observed. The salt melts reacted with the steel surface facing the flue gas flow and increased the thickness of the oxide layer up to a maximum of 30 mm. On the surface not facing the flue gas flow, they disrupted the corrosive layer, reduced its adhesion, and exposed the metal surface. Beneath the massive deposits, a local overheating of the inner surface of the evaporator tubes occurred, which resulted in the release of the protective magnetite layer from the surface. Ash deposits reduce the boiler’s thermal efficiency because they act as a thermal resistor for heat transfer between the flue gases and the working medium in the pipes. The effect of insufficient feedwater treatment was evinced in the presence of mineral salts in the corrosion layer on the inner surface of the tube.

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Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

Applied Sciences ◽

10.3390/app11072961 ◽

2021 ◽

Vol 11 (7) ◽

pp. 2961

Author(s):

Nikola Čajová Kantová ◽

Alexander Čaja ◽

Marek Patsch ◽

Michal Holubčík ◽

Peter Ďurčanský

Keyword(s):

Particulate Matter ◽

Flue Gas ◽

Gas Flow ◽

Negative Impact ◽

Combustion Process ◽

Cfd Simulations ◽

Piv Measurements ◽

Computational Fluid Dynamics Cfd ◽

Particle Imaging ◽

Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

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A modified gas flow model in the near wellbore region below dew point pressure

Petroleum ◽

10.1016/j.petlm.2021.01.002 ◽

2021 ◽

Author(s):

Abed Inan Chowdhury ◽

Md Mostafijul Karim

Keyword(s):

Gas Flow ◽

Flow Model ◽

Dew Point ◽

Point Pressure ◽

Dew Point Pressure

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High Flue Gas Flow Rate Tests for Removal and Recovery of Carbon Dioxide under Power Plant Effluent Gas Conditions

KAGAKU KOGAKU RONBUNSHU ◽

10.1252/kakoronbunshu.30.758 ◽

2004 ◽

Vol 30 (6) ◽

pp. 758-761

Author(s):

Tomio MIMURA ◽

Yasuyuki YAGI ◽

Masaki IIJIMA ◽

Ryuji YOSIYAMA ◽

Takahito YONEKAWA

Keyword(s):

Carbon Dioxide ◽

Power Plant ◽

Flow Rate ◽

Flue Gas ◽

Gas Flow ◽

Gas Flow Rate ◽

Power Plant Effluent ◽

Removal And Recovery

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A Novel Design for Reduction of Ammonium Bisulfate Deposition in the Rotary Air Preheater

Volume 1: Fuels, Combustion, and Material Handling; Combustion Turbines Combined Cycles; Boilers and Heat Recovery Steam Generators; Virtual Plant and Cyber-Physical Systems; Plant Development and Construction; Renewable Energy Systems ◽

10.1115/power2018-7278 ◽

2018 ◽

Author(s):

Yufan Bu ◽

Limin Wang ◽

Xiaoyang Wei ◽

Lei Deng ◽

Defu Che

Keyword(s):

Flue Gas ◽

Gas Flow ◽

Catalytic Reduction ◽

Operating Cost ◽

Reaction Chamber ◽

Air Preheater ◽

Accurate Temperature ◽

Ammonium Bisulfate ◽

Lower Temperature ◽

Novel Design

Nitrogen oxide (NOx) emitted from boilers in coal-fired power plant may be reduced by 90 percent through the application of the selective catalytic reduction (SCR). However, the escaped ammonia from the SCR systems could react with sulfur oxides (SOx) in the flue gas to form ammonium bisulfate (ABS) in exhaust systems. The blockage and corrosion caused by ABS seriously impact the rotary air preheater (RAPH), which would not only increase operating cost on ash-blowing and cleaning but also lead to unplanned outage. To solve the problem, in this paper a novel preheater system is proposed. A single preheater is split into two sub-preheaters, between which the main flue gas flow is mixed with the recirculated flue gas from outlet of the lower-temperature preheater. After the mixing point, a reaction chamber and a precipitator are installed. A numerical finite difference method (FDM) is employed to model the RAPH and obtain the accurate temperature distribution of fluid and heat transfer elements. The initial formation temperatures of (NH4)2SO4 and ABS are 200 °C and 170 °C, respectively, according to the flue gas composition in this work. By calculation, this split design of the RAPH is believed to be effective in reducing deposition of ABS.

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Development of the Burden Distribution and Gas Flow Model in the Blast Furnace Shaft

ISIJ International ◽

10.2355/isijinternational.51.1617 ◽

2011 ◽

Vol 51 (10) ◽

pp. 1617-1623 ◽

Cited By ~ 18

Author(s):

Jong-In Park ◽

Ui-Hyun Baek ◽

Kyoung-Soo Jang ◽

Han-Sang Oh ◽

Jeong-Whan Han

Keyword(s):

Blast Furnace ◽

Gas Flow ◽

Flow Model ◽

Burden Distribution ◽

Furnace Shaft

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Numerical Simulation on Double-nozzle Spray Evaporation of Desulfurization Wastewater

10.20944/preprints202110.0213.v1 ◽

2021 ◽

Author(s):

Hong Xu ◽

Shuqin Feng ◽

Liehui Xiao ◽

Yazhen Hao ◽

Xiaoze Du

Keyword(s):

Flue Gas ◽

Gas Flow ◽

Evaporation Rate ◽

Flow Direction ◽

Droplet Diameter ◽

Numerical Results ◽

Least Square ◽

Lagrangian Model ◽

Support Vector ◽

Exhaust Heat

To achieve the near zero emission of wastewater in the flue gas desulfurization (FGD) system in coal-fired power plant and better utilize the exhaust heat from flue gas, a feasible technology of spraying FGD wastewater in the flue duct for evaporation is discussed in the present study. A full-scale influencing factor investigation on the wastewater droplet evaporation performance is established under the Eulerian-Lagrangian model numerically. The dominant factors, including the characters of wastewater droplets, flue gas and the spray nozzles were analyzed under different conditions, respectively. Considering the multiple factors and conditions in the process, a Least-Square support vector machine (LSSVM) model is introduced to predict the evaporation rate based on the numerical results. Conclusions are made that the flue gas temperature and droplet diameter are of great importance in the evaporation process. The spray direction of droplet parallel with the flue gas flow direction is profitable for the dispersion of droplet, resulting the maximal evaporation rate. A double-nozzle arrangement optimized with relatively small flow rate is recommended. The LSSVM model can accurately predict the evaporation rate using the numerical results with different conditions.

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Development of a Laboratory-Scale Thermal-Arc-Plasma Reactor and its Application in the Pyrolysis of Petroleum Oily Sludge

Frontiers in Advanced Materials Research ◽

10.34256/famr2012 ◽

2020 ◽

Vol 2 (1) ◽

pp. 15-27

Author(s):

Abubakar M. Ali ◽

Mohd A. Abu-Hassan ◽

Raja R.K. Ibrahim ◽

Bala I. Abdulkarim

Keyword(s):

Flue Gas ◽

Gas Flow ◽

Waste Treatment ◽

Treatment Time ◽

Plasma Reactor ◽

Pilot Scale ◽

Oily Sludge ◽

Arc Plasma ◽

Plasma Arc ◽

Mass Reduction

Waste treatment using thermal arc plasma is well established and laboratory/pilot scale plasma reactors were developed and their performances for the destruction of different hazardous wastes, other than petroleum oily sludge, were studied. This work aims to extend the plasma technology to the pyrolysis of hazardous petroleum oily sludge. A 4.7 kW thermal arc plasma reactor was developed using a standard TIG arc welding torch. The transferred arc plasma reactor was used to treat 20 g/batch of petroleum oily sludge. The prevailing temperature inside the reactor ranges between 356 – 1694 oC. The plasma arc temperature increased with increasing plasma arc current and also with increasing plasma gas flow-rate. A vitreous slag and a flue gas were generated as products. A mass reduction of between 36.87 – 91.40% and a TOC reduction of 21.47 – 93.76% were achieved in the treatment time of 2 – 5 min. The mass reduction was observed to increase with treatment time. However, the increase was more rapid between the 3rd and the 4th min of the treatment. The flue gas produced contains H2 (43.79 – 50.97 mol%), H2O (26.60 – 30.22 mol%), CO (8.45 – 11.18 mol%), CO2 (5.12 – 10.35 mol%), CH4 (2.17 – 3.38 mol%), C2H2 (0.86 – 2.69 mol%) and C2H4 (0.76 – 2.17 mol%). Thus, the thermal plasma reactor provides a suitable method of treating petroleum oily sludge.

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INFLUENCE OF FLUE GAS PATTERN FLOW IN BOILER RADIANT SECTION ON HEAT TRANSFER

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4051369 ◽

2021 ◽

pp. 1-16

Author(s):

Branislav Jacimovic ◽

Srbislav Genic ◽

Nikola Jacimovic

Keyword(s):

Heat Transfer ◽

Flue Gas ◽

Gas Flow ◽

Plug Flow ◽

Integral Model ◽

Engineering Practice ◽

Conductive Heat ◽

Small Deviations ◽

Proposed Model ◽

Perfect Mixing

Abstract During the sizing of the radiant zone in boilers and furnaces, the most often used method is the Lobo-Evans model. This method is based on the perfect mixing model for flue gas flow inside the fire box, which represents a conservative or pessimistic flow pattern. This paper presents a different, optimistic model which is based on the plug flow for flue gas flow which results in the largest possible heat duty. The proposed model is given in two distinct forms – integral and numerical. As shown in the paper, the integral model results in small deviations with respect to the numerical model and, as such, is well suited for the engineering practice. Paper also presents an engineering approach to the calculation of the conductive heat transfer through the membrane wall, which is shown to be sufficiently accurate and simple for engineering calculations.

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