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Article
Publication date: 13 September 2011

Wei Wang and Hairui Yang

Rectangular fluidised beds are commonly used in industry, e.g. circulating fluidised bed (CFB) boilers. Apparently, no one has tried to imagine rectangular fluidised beds by…

250

Abstract

Purpose

Rectangular fluidised beds are commonly used in industry, e.g. circulating fluidised bed (CFB) boilers. Apparently, no one has tried to imagine rectangular fluidised beds by electrical capacitance tomography (ECT). The purpose of this paper is to design a rectangular ECT sensor to understand the behaviour of a rectangular CFB riser.

Design/methodology/approach

A rectangular sensor with eight electrodes is adopted to obtain the capacitance data. The sensitivity map is simulated to calculate the grey level of pixels for visualisation using the linear back‐projection algorithm.

Findings

Experiments showed that the position of the objects in the riser can be obviously indicated and the central region of the object(s) has significantly higher grey level than other regions in the images using the rectangular ECT sensor.

Research limitations/implications

It has a limitation in providing a higher resolution image.

Practical implications

The results obtained by the rectangular ECT sensor show that it is promising to study the characteristics of flow non‐uniformity in the fast fluidisation regime of CFB.

Originality/value

Without using square and circular ECT sensors, this is the first time a rectangular ECT sensor has been developed to study the unique problems of the characteristics of flow non‐uniformity in a rectangular CFB riser.

Details

Sensor Review, vol. 31 no. 4
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 6 December 2023

Hairui Jiang, Jianjun Guan, Yan Zhao, Yanhong Yang and Jinglong Qu

The purpose of this study is to investigate the corrosion resistance of superalloys subjected to ultrasonic impact treatment (UIT). The passive film growth on the superalloys’…

101

Abstract

Purpose

The purpose of this study is to investigate the corrosion resistance of superalloys subjected to ultrasonic impact treatment (UIT). The passive film growth on the superalloys’ surface is analyzed to illustrate the corrosion mechanism.

Design/methodology/approach

Electrochemical tests were used to investigated the corrosion resistance of GH4738 superalloys with different UIT densities. The microstructure was compared before and after the corrosion tests. The passive film characterization was described by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) tests.

Findings

The compressive residual stress and corrosion resistance of the specimens significantly increased after UIT. The order of corrosion resistance is related to the UIT densities, i.e. 1.96 s/mm2 > 1.71 s/mm2 > 0.98 s/mm2 > as-cast. The predominant constituents of the passive films are TiO2, Cr2O3, MoO3 and NiO. The passive film on the specimen with 1.96 s/mm2 UIT density has the highest volume fraction of Cr2O3 and MoO3, which is the main reason for its superior corrosion resistance.

Originality/value

This study provides quantitative corrosion data for GH4738 superalloys treated by ultrasonic impact. The corrosion mechanism is explained by the passive film’s characterization.

Details

Anti-Corrosion Methods and Materials, vol. 71 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 26 December 2024

Hairui Jiang, Jianjun Guan, Yan Zhao, Jinglong Qu and Yanhong Yang

This study aims to investigate the corrosion resistance and electrochemical dissolution behavior of superalloys treated by different oxidation treatments.

9

Abstract

Purpose

This study aims to investigate the corrosion resistance and electrochemical dissolution behavior of superalloys treated by different oxidation treatments.

Design/methodology/approach

Ni-based superalloys were subjected to oxidation treatment at 1000 °C for 10 h, 1150 °C for 10 h and 1200 °C for 20 h. The microstructure, electrochemical dissolution behavior, elemental distribution, as well as compactness and composition of the oxide layer, were studied.

Findings

The results show that both the thickness and the granular oxide size of the oxide layer on Ni-based superalloys increase with longer oxidation times and higher temperatures. The electrochemical dissolution efficiency of Ni-based superalloys decreases with increasing oxidation time and temperature. The reduced electrochemical dissolution efficiency observed in Ni-based superalloys oxidation-treated at 1200 °C for 20 h is primarily attributed to the thicker oxide layer, which contains the highest Cr oxide content.

Originality/value

The findings contribute to the advancement of recycling and utilization of Ni-based superalloy scrap.

Details

Anti-Corrosion Methods and Materials, vol. 72 no. 2
Type: Research Article
ISSN: 0003-5599

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