Experimental Study on Gas Atmosphere near Side Walls of Swirl Opposed Supercritical Boiler

2013 ◽  
Vol 732-733 ◽  
pp. 116-119
Author(s):  
Xing Sen Yang ◽  
Xin Gang Zhou
Keyword(s):  
High Temperature ◽  
Corrosion Test ◽  
Side Wall ◽  
Experimental System ◽  
High Temperature Corrosion ◽  
Test Area ◽  
Reducing Atmosphere ◽  
Gas Atmosphere ◽  
Co Concentration ◽  
Side Walls

High temperature corrosion of metal material was found on the side water-walls of a swirl-opposed firing supercritical boiler. The gas atmosphere near the side wall has great relationship with the high temperature corrosion. Test holes were installed on the side walls to form an experimental system. The gas compositions near the side walls were analyzed under different combustion conditions. High CO concentration is detected near the side walls. The effects of the operation states of burners on the CO concentration near side walls were tested. High over-fire air quantity results in strong reducing atmosphere of the test area. The adjusting method to control the atmosphere is suggested.

Numerical investigation on optimization of wall jet to reduce high temperature corrosion in 660 MW opposed wall fired boiler

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yong Zhang ◽  
Yuyang Liu ◽  
Xigang Yang ◽  
Guoqing Chen ◽  
Baosheng Jin
Keyword(s):  
High Temperature ◽  
Inclination Angle ◽  
Positive Impact ◽  
Side Wall ◽  
High Temperature Corrosion ◽  
Coverage Area ◽  
Wall Film ◽  
Jet Trajectory ◽  
Jet Velocity ◽  
Rational Organization

Abstract For an air staged combustion boiler, the rational organization of jets to form closing-to-wall film using as little air as possible plays a key role in resolving the high temperature corrosion problems. In this work, a comprehensive computational fluid dynamics (CFD) model including hydrodynamics and coal combustion is established for a 660 MW opposed wall fired boiler. Based on the grid independence and model validation, the flow field, temperature profile, and species concentration are predicted, and the influences of the structure of nozzles and the operation parameter of jets are further evaluated. The results show that the corrosion area of the side wall is dependent on the jet projection velocity and nozzle structures. The increase of the jet velocity does not always have an active influence on the reduction of corrosive area. Only increasing the nozzle diameter does not always have a positive impact on the improvement of the corrosion. The increase of the jet inclination angle can extend the jet trajectory, contributing to increase the oxygen coverage area. Reasonably adjusting the jet inclination angle of each layer can obtain the lower corrosion area. The increase of jet row number leads to a decrease in the spacing between rows, which enables the downstream jet to penetrate deeper into the cross stream. By increasing the number of jet layers and reducing the jet velocity of each layer, the lowest corrosion area can be obtained.

High Temperature Corrosion of Ti3AlC2 in Ar-1%SO2 Atmosphere

2007 ◽  
Vol 544-545 ◽  
pp. 343-346 ◽  
Author(s):  
Dong Bok Lee ◽  
Jee Hoon Choi
Keyword(s):  
High Temperature ◽  
Ternary Compound ◽  
Mixed Layer ◽  
High Temperature Corrosion ◽  
Tio2 Layer ◽  
Gas Atmosphere ◽  
Α Al2o3 ◽  
So2 Gas

The layered, machinable ternary compound, Ti3AlC2, was corrosion-tested at 800, 900, and 1000oC under an Ar-1% SO2 gas atmosphere. The scale formed consisted primarily of TiO2 and α-Al2O3. As the corrosion progressed, the scale became thicker and developed into an outer TiO2 layer and an inner (TiO2,Al2O3)-mixed layer.

scholarly journals How universal is the vibration-velocity controlled granular convection?

2021 ◽  
Vol 249 ◽  
pp. 03019
Author(s):  
Mika Umehara ◽  
Ko Okumura
Keyword(s):  
Side Wall ◽  
Experimental System ◽  
Wall Friction ◽  
Vibration Velocity ◽  
High Reproducibility ◽  
Vertical Side ◽  
Granular Dynamics ◽  
A Cell ◽  
Brazil Nut Effect ◽  
Side Walls

Recently, a number of articles have reported that granular convection induced by continuous vibration is controlled by vibration velocity, in contrast with some previous studies. We have reported such an example for the Brazil nut effect when the vibration is given discontinuously, using a one-layer granular bed in a cell with down-facing side walls. Here, we report the effect of vibration phase and wall friction using the same experimental system, to confirm rising motion of an intruder induced by granular convection is again governed by vibration velocity. We compare two different cases of vibration phase for giving intermittent vibration cycles, and found one, in which granular packing is well established before grains start to lose contacts due to vibration, provides distinctly high reproducibility. We further control the side wall friction using a microfabrication technique, and found that significantly high reproducibility is attained in a cell with vertical side walls when a millimeter texture is introduced on the side walls. Our results indicate that the granular convection is universally controlled by vibration velocity. The present study opens a way to conduct highly reproducible experiments on granular dynamics, which is indispensable for deep physical understanding of granular flow and segregation.

scholarly journals Fundamental Investigations on the High-Temperature Corrosion of Spinel-Forming Alumina Castables by Steel Slags

2022 ◽  
Vol 12 (2) ◽  
pp. 704
Author(s):  
Jakub Ramult ◽  
Klaudia Wiśniewska-Tobiasz ◽  
Ryszard Prorok ◽  
Dominika Madej
Keyword(s):  
High Temperature ◽  
Liquid Phase ◽  
Corrosion Test ◽  
Steel Slag ◽  
High Temperature Corrosion ◽  
Mass Ratio ◽  
Narrow Temperature Range ◽  
Coating Method ◽  
Alumina Castables ◽  
Static Corrosion

This study investigated the effect of the CaO/SiO2 mass ratio of steel slag on the corrosion behavior of spinel-forming alumina-based castables with a content of MgO (3–7 wt.%). Equiweight mixtures of castables and slags were calculated by FactSage, observed by HMTA, fired at 1350 °C, and investigated by XRD. From these results, we conclude that the presence of SiO2-rich phases accelerates the growth of the liquid phase in a narrow temperature range for the tested samples, which accelerates the degradation of castables. The static corrosion test was conducted by means of the coating method at 1450 °C. The corrosion index (IC) in the regions of castables affected by slags was calculated. Phases and phase distributions were evaluated by SEM-EDS. From these results, we conclude that for the slag with the lowest mass ratio of CaO/SiO2 (1.1), the reaction zone occurs only below the slag-refractory interface, which indicates the aggressive character of this slag.

Accelerated Corrosion of Stainless Steels in the Presence of Molten Carbonate below 923 K

1997 ◽  
Vol 496 ◽  
Author(s):  
Ken-ichiro Ota ◽  
Katsuya Toda ◽  
Naobumi Motohira ◽  
Nobuyuki Kamiya
Keyword(s):  
Weight Gain ◽  
High Temperature ◽  
Corrosion Rate ◽  
Stainless Steels ◽  
Corrosion Test ◽  
Initial Period ◽  
High Temperature Corrosion ◽  
Molten Carbonate ◽  
Reaction Conditions ◽  
Accelerated Corrosion

ABSTRACTThe high temperature corrosion of stainless steels (SUS316L and SUS310S) in the presence of molten carbonate [(Li0.62K0.8)2CO3 and (Li0.52Na0.48)2CO3] has been studied in a CO2-O2 atmosphere by measuring the weight gain of the specimens.The corrosion of SUS316L significantly depended on the reaction conditions. With the carbonate coating (both Li/Na and Li/K carbonates), severe corrosion occurred during the initial period of the corrosion test below 923 K, especially around 823 K. The initial severe corrosion was a local corrosion which produced through holes in the metal specimens and occurred more clearly at low Pco2 with the Li/Na coating than with the Li/K coating. The corrosion became more severe at higher CO2 pressures and lower O2 pressures. In a pure CO2 atmosphere (without O2), the corrosion rate significantly increased at 823 K. The steel was corroded uniformly at that time.

High Temperature Corrosion Resistance of Siliconized Stainless Steel under Continuous Deposition of Salt

2011 ◽  
Vol 696 ◽  
pp. 266-271
Author(s):  
Naka Sato ◽  
Toshiya Kaneta ◽  
Michihisa Fukumoto ◽  
Motoi Hara
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Diffusion Layer ◽  
Corrosion Test ◽  
Silicon Oxide ◽  
High Temperature Corrosion ◽  
Silicon Iron ◽  
Continuous Deposition ◽  
Silicon Diffusion

The surface alloying of Si into SUS304 austenitic stainless steel was carried out by a halide-activated pack-cementation method. By this treatment, the silicon diffusion layer containing about 13 at.% Si was formed. The high temperature corrosion resistance of this specimen was evaluated under the continuous deposition of salt. The result of the corrosion test showed that the oxidation mass gain of the siliconized stainless steel was lower than that of non-treated stainless steel. It was found from the observation of the cross-section of the specimen after the corrosion test that a thin scale was formed on the silicon diffusion layer and silicon oxide was formed as an inner layer of the scale. A mechanism of the oxidation suppression for the siliconized steel under the continuous deposition of salt was investigated by the oxidation test of pure silicon, iron, chromium or nickel powder mixed with equimolar NaCl-KCl. As a result, it was found that the high corrosion resistance of the siliconized steel was attributable to the fact that the silicon oxide formed on the silicon diffusion layer was inert to the chemical reaction with the NaCl-KCl salt.

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