Lab-Scale Study on Fireside Superheaters Corrosion in MSWI Plants

2009 ◽  
Author(s):  
Jean-Michel Brossard ◽  
Florimonde Lebel ◽  
Christophe Rapin ◽  
Jean-Franc¸ois Mareˆche´ ◽  
Xavier Chaucherie ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Flue Gas ◽  
Gas Flow ◽  
Operating Conditions ◽  
Gas Temperature ◽  
Steam Temperature ◽  
Corrosion Tests ◽  
Corrosion Rates ◽  
First Results

Combustion of the municipal waste generates highly corrosive gases (HCl, SO2, NaCl, KCl and heavy metals chlorides) and ashes containing alkaline chlorides and sulphates. Currently, corrosion phenomena are particularly observed on superheater’s tubes. Corrosion rates depend mainly on installation design, operating conditions i.e. gas and steam temperature and velocity of the flue gas containing ashes. This paper presents the results obtained using an innovative laboratory-scale corrosion pilot, which simulates MSWI boilers conditions characterized by a temperature gradient at metal tube on the presence of corrosive gases and ashes. The presented corrosion tests were realized on carbon steel at fixed metal temperature (400°C). The influence of the flue gas temperature, synthetic ashes composition and flue gas flow pattern were investigated. After corrosion test, cross section of tube samples were characterised to evaluate thickness loss and estimate corrosion rate while the elements present in corrosion layers were analysed. Corrosion tests were carried out twice in order to validate the accuracy and reproducibility of results. First results highlight the key role of molten phase related to the ash composition and flue gas temperature as well as the deposit morphology, related to the flue gas flow pattern, on the mechanisms and corrosion rates.

scholarly journals Computer modeling of a convective steam superheater

2015 ◽  
Vol 36 (1) ◽  
pp. 125-137 ◽  
Author(s):  
Marcin Trojan
Keyword(s):  
Pressure Drop ◽  
Flue Gas ◽  
Gas Flow ◽  
Practical Importance ◽  
Steam Superheater ◽  
Saturated Steam ◽  
Gas Temperature ◽  
Steam Temperature ◽  
Dynamics Simulations ◽  
Ash Fouling

Abstract Superheater is for generating superheated steam from the saturated steam from the evaporator outlet. In the case of pulverized coal fired boiler, a relatively small amount of ash causes problems with ash fouling on the heating surfaces, including the superheaters. In the convection pass of the boiler, the flue gas temperature is lower and ash deposits can be loose or sintered. Ash fouling not only reduces heat transfer from the flue gas to the steam, but also is the cause of a higher pressure drop on the flue gas flow path. In the case the pressure drop is greater than the power consumed by the fan increases. If the superheater surfaces are covered with ash than the steam temperature at the outlet of the superheater stages falls, and the flow rates of the water injected into attemperator should be reduced. There is also an increase in flue gas temperature after the different stages of the superheater. Consequently, this leads to a reduction in boiler efficiency. The paper presents the results of computational fluid dynamics simulations of the first stage superheater of both the boiler OP-210M using the commercial software. The temperature distributions of the steam and flue gas along the way they flow together with temperature of the tube walls and temperature of the ash deposits will be determined. The calculated steam temperature is compared with measurement results. Knowledge of these temperatures is of great practical importance because it allows to choose the grade of steel for a given superheater stage. Using the developed model of the superheater to determine its degree of ash fouling in the on-line mode one can control the activation frequency of steam sootblowers.

scholarly journals Reliable simple zonal method of the furnace thermal calculation

2005 ◽  
Vol 9 (2) ◽  
pp. 45-55
Author(s):  
Vladan Ivanovic
Keyword(s):  
Energy Consumption ◽  
Flue Gas ◽  
Thermal Load ◽  
Operating Conditions ◽  
Thermal Calculation ◽  
Gas Temperature ◽  
Zonal Method ◽  
One Dimensional ◽  
Furnace Performance ◽  
Steam Boilers

The calculation of the furnace in the industrial and power boilers is the most important and the most responsible part of the thermal calculation, and it has important influence on the rationalization of energy consumption. In the paper one-dimensional zonal method of the furnace thermal calculation of steam boilers is presented. It can successfully define disposition of flue gas temperature and specific thermal load of screen walls with height of the furnace in case of uneven deposits distribution which vary in size and quality. Its greatest use is for comparing furnace performance under various operating conditions.

Role of the gas temperature and power to gas flow ratio on powder and voids formation in films grown by PECVD technique

Vacuum ◽  
2000 ◽  
Vol 56 (1) ◽  
pp. 25-30 ◽  
Author(s):  
R Martins ◽  
V Silva ◽  
I Ferreira ◽  
A Domingues ◽  
E Fortunato
Keyword(s):  
Gas Flow ◽  
Flow Ratio ◽  
Gas Temperature ◽  
Gas Flow Ratio ◽  
Power To Gas

Coal Ash Deposition on Nozzle Guide Vanes: Part I—Experimental Characteristics of Four Coal Ash Types

2011 ◽  
Author(s):  
J. Webb ◽  
B. Casaday ◽  
B. Barker ◽  
J. P. Bons ◽  
A. D. Gledhill ◽  
...  
Keyword(s):  
Film Cooling ◽  
Gas Flow ◽  
Guide Vane ◽  
Ambient Pressure ◽  
Coal Ash ◽  
Leading Edge ◽  
Operating Conditions ◽  
Test Facility ◽  
Gas Temperature ◽  
Nozzle Guide

An accelerated deposition test facility was operated with three different coal ash species to study the effect of ash composition on deposition rate and spatial distribution. The facility seeds a combusting (natural gas) flow with 10–20 micron mass mean diameter coal ash particulate. The particulate-laden combustor exhaust is accelerated through a rectangular-to-annular transition duct and expands to ambient pressure through a nozzle guide vane annular sector. For the present study, the annular cascade consisted of two CFM56 aero-engine vane doublets; comprising three full passages and two half passages of flow. The inlet Mach number (0.1) and gas temperature (1100°C) are representative of operating turbines. Ash samples were tested from the three major coal ranks: lignite, subbituminous, and bituminous. Investigations over a range of inlet gas temperatures from 900°C to 1120°C showed that deposition increased with temperature, though the threshold for deposition varied with ash type. Deposition levels varied with coal rank, with lignite producing the largest deposits at the lowest temperature. Regions of heightened deposition were noted; the leading edge and pressure surface being particularly implicated. Scanning electron microscopy was used to identify deposit structure. For a limited subset of tests, film cooling was employed at nominal design operating conditions but provided minimal protection in cases of severe deposition.

Experimental and Simulation Study on the Effects of Twisted Coil Plates on the Performance of Fire Tube Boiler

2014 ◽  
Vol 564 ◽  
pp. 234-239
Author(s):  
M.K. Roslim ◽  
Suhaimi Hassan ◽  
K. Izzati
Keyword(s):  
Flue Gas ◽  
Operating Time ◽  
Width Ratio ◽  
Gas Temperature ◽  
Steam Temperature ◽  
Ansys Fluent ◽  
Boiler Efficiency ◽  
Twist Ratio ◽  
Fluent Simulation ◽  
Tube Coil

Influences of twisted coil plate insert on the performance of fire tube boiler using were experimentally investigated. In this study, the twisted coil plate was placed inside the tube to illustrate boiler performance. The performances of boiler were studied in terms of operating time taken, exhaust flue gas temperature, steam temperature and boiler efficiency. The boiler was operated with 50%, 100% and without tube coil plate inserts at low and high fire burner setting. Based on the results obtained, effect of twisted plate insert and without insert were observed. There is an enhancement in boiler performance in terms of boiler efficiency. The ANSYS Fluent simulation showed the effect of width ratio and twist ratio. Therefore, the experimental results indicate that using twisted coil plate in the boiler is one of the best ways to improve boiler performance.

Furnace Design for Improved Exhaust Gas Circulation and Heat Transfer Efficiency

2020 ◽  
Author(s):  
Ayoola T. Brimmo ◽  
Mohamed I. Hassan Ali
Keyword(s):  
Heat Transfer ◽  
Metal Surface ◽  
Flue Gas ◽  
Waste Heat ◽  
Operating Conditions ◽  
Aluminum Production ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Exhaust Gases ◽  
Gas Circulation

Abstract In the aluminum production industry, metal furnaces are operated by diffusion flame over the metal surface to maintain the aluminum metal at the set point temperature for alloying and casting. Heat is transferred from the flame and its exhaust gases to the metal surface via radiation and convection. The exhaust gases leaves through the furnace’s chimney carrying a significant amount of waste heat to the atmosphere. Furnace efficiency could be improved by enhancing the heat transfer inside the furnace. In this study, a validated full-scale 3-D CFD model of a natural gas fired aluminum furnace is developed to investigate the effect of flue gas ventilation configurations and burner operating conditions on the heat transfer inside the furnace. Onsite measurements are carried out for the fuel and airflow rates as well as flue gas temperature. Four flue ventilation configurations are considered with eight furnace’s operation modes. The flue-gas’s waste-heat varies from 49–58%, with the highest value occurring at the high-fire operating mode. This indicates a significant room for improvement in the furnace performance. Results suggest that a symmetrical positioning of the exhaust duct favors effective exhaust gas circulation within the furnace and hence, increases hot-gases’ heat-transfer effectiveness inside the furnace. These results provide some guidelines for optimal aluminum reverberatory furnace designs and operation.

scholarly journals Advanced and Intensified Seawater Flue Gas Desulfurization Processes: Recent Developments and Improvements

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5917 ◽  
Author(s):  
Nguyen Van Duc Long ◽  
Dong Young Lee ◽  
Kim Myung Jin ◽  
Kwag Choongyong ◽  
Lee Young Mok ◽  
...  
Keyword(s):  
Flue Gas ◽  
Gas Flow ◽  
Process Integration ◽  
Waste Heat ◽  
Combined Treatment ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Flue Gas Desulfurization ◽  
Loading Capacity ◽  
Equipment Size

Seawater flue gas desulfurization (SWFGD) is considered to be a viable solution for coastal and naval applications; however, this process has several drawbacks, including its corrosive absorbent; low vapor loading capacity since the solubility of sulfur oxides (SOx) in seawater is lower than that of limestone used in conventional methods; high seawater flowrate; and large equipment size. This has prompted process industries to search for possible advanced and intensified configurations to enhance the performance of SWFGD processes to attain a higher vapor loading capacity, lower seawater flowrate, and smaller equipment size. This paper presents an overview of new developments as well as advanced and intensified configurations of SWFGD processes via process modifications such as modification and optimization of operating conditions, improvement of spray and vapor distributors, adding internal columns, using square or rectangular shape, using a pre-scrubber, multiple scrubber feed; process integration such as combined treatment of SOx and other gases, and waste heat recovery; and process intensification such as the use of electrified sprays, swirling gas flow, and rotating packed beds. A summary of the industrial applications, engineering issues, environmental impacts, challenges, and perspectives on the research and development of advanced and intensified SWFGD processes is presented.

scholarly journals Combined Removal Of NOx And SO2 From Flue Gas At Low Temperature

2018 ◽  
Vol 53 ◽  
pp. 04038 ◽  
Author(s):  
Zhipeng Xue ◽  
Hao Chen ◽  
Minmin Zhao
Keyword(s):  
Removal Efficiency ◽  
Flue Gas ◽  
Gas Flow ◽  
Ph Value ◽  
National Standards ◽  
Raw Material ◽  
Nox Removal ◽  
Gas Temperature ◽  
Solution Ph ◽  
Nox Removal Efficiency

A method was proposed to remove NOx and SO2 in flue gas by using the sulfinyl functional group as a catalyst. Ozone is introduced into the flue gas to oxidize NO. Soluble NO2 and SO2 reacted with ammonia to form ammonium sulfate and ammonium nitrate, which were the raw material of the compound fertilizer. A small pilot is built in a container that can be easily transported to power plant and extracts the actual flue gas directly from the gas duct. In order to obtain the best the SO2 and NOX removal efficiency in this experiment, many parameters were changed. Such as flue gas flow, ozone / NOX ratio, liquid-gas ratio, flue gas temperature, catalyst type, catalyst concentration, solution pH value. Results indicated that SO2 was cleaned up quite efficiently and the removal efficiency was nearly 99% under all conditions. the best NOX removal efficiency can reach 88%. The NOX removal efficiency depended primarily on ozone / NOX ratio, and the temperature of flue gas also had influence on the NOX removal efficiency. The optimum pH range is 5.6-6.3. After inspection by authoritative institutions, the quality of fertilizers is superior to national standards.

Simulation and Validation of a Mass Burn WTE Boiler Using CFD Modeling

2004 ◽  
Author(s):  
Greg Epelbaum
Keyword(s):  
Flue Gas ◽  
Cfd Modeling ◽  
Design Parameters ◽  
Air Distribution ◽  
Gas Temperature ◽  
Corrosion Rates ◽  
Velocity Surface ◽  
Boiler Tubes ◽  
Chloride Salts ◽  
Simulation And Validation

American Ref-Fuel Company (ARC) spends millions of dollars each year on corrosion related costs in the boilers. The corrosion is caused by chloride salts in the slag that deposit on the boiler tubes, coupled with the high temperatures of flue gas going through the boiler. Corrosion rates are known to be very sensitive to the flue gas temperature and velocity, surface temperature and heat flux through the slag, oxygen in flue gas distribution, etc. These parameters are primarily determined by the firing rate of the boiler, and they are also affected by combustion control and air distribution in the boiler. Some design parameters, such as surface area of refractory, tile, and inconel overlay, also affect the flue gas temperature throughout the boiler, and thereby impact corrosion.

Coal Ash Deposition on Nozzle Guide Vanes—Part I: Experimental Characteristics of Four Coal Ash Types

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Webb ◽  
B. Casaday ◽  
B. Barker ◽  
J. P. Bons ◽  
A. D. Gledhill ◽  
...  
Keyword(s):  
Film Cooling ◽  
Gas Flow ◽  
Guide Vane ◽  
Ambient Pressure ◽  
Coal Ash ◽  
Leading Edge ◽  
Operating Conditions ◽  
Test Facility ◽  
Gas Temperature ◽  
Nozzle Guide

An accelerated deposition test facility was operated with four different coal ash species to study the effect of ash composition on deposition rate and spatial distribution. The facility seeds a combusting (natural gas) flow with 10–20 micron mass mean diameter coal ash particulate. The particulate-laden combustor exhaust is accelerated through a rectangular-to-annular transition duct and expands to ambient pressure through a nozzle guide vane annular sector. For the present study, the annular cascade consisted of two CFM56 aero-engine vane doublets, comprising three full passages and two half passages of flow. The inlet Mach number (0.1) and gas temperature (1100 °C) are representative of operating turbines. Ash samples were tested from the three major coal ranks: lignite, subbituminous, and bituminous. Investigations over a range of inlet gas temperatures from 900 °C to 1120 °C showed that deposition increased with temperature, though the threshold for deposition varied with ash type. Deposition levels varied with coal rank, with lignite producing the largest deposits at the lowest temperature. Regions of heightened deposition were noted; the leading edge and pressure surface being particularly implicated. Scanning electron microscopy was used to identify deposit structure. For a limited subset of tests, film cooling was employed at nominal design operating conditions but provided minimal protection in cases of severe deposition.

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