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Article
Publication date: 1 January 1962

W.D. Jarvis

The corrosive attack of boiler surfaces exposed to flue gases has occurred from time to time in plant operated by the Central Electricity Generating Board. The…

Abstract

The corrosive attack of boiler surfaces exposed to flue gases has occurred from time to time in plant operated by the Central Electricity Generating Board. The availability lost in this way is little more than 1% of the total boiler capacity installed, but when the load demand is met mainly by unit generators with a steaming capacity over 100 MW, the enforced shut‐down of one of these units would be a more serious loss. This article describes the ways in which various parts of boilers are attacked, the factors affecting corrosion in these cases and the chemical basis of the processes. Investigations are being carried out, and several preventive methods are mentioned.

Details

Anti-Corrosion Methods and Materials, vol. 9 no. 1
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 3 July 2007

D. Rezakhani

Four thermal spray coatings were subjected to high temperature corrosive environments of oil‐fired boiler conditions to compare their corrosion protection under simulated…

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Abstract

Purpose

Four thermal spray coatings were subjected to high temperature corrosive environments of oil‐fired boiler conditions to compare their corrosion protection under simulated conditions. The coatings included FeCrAl, Tafaloy 45CT, which were arc‐sprayed, 50Ni‐50Cr and Cr3C2‐NiCr, which were coated by high velocity oxy fuel spray (HVOF) method.

Design/methodology/approach

The coating substrates used were SA213TP 347H, SA213 T11 and SA213 T22 alloys that are widely used as boiler tube materials. Specimens were covered with a synthetic ash mixture of 70 per cent V2O5‐20 per cent Na2SO4‐10 per cent NaCl and exposed to 550°C and 650oC°for 192 h (6 cycles). After high temperature corrosion tests, weight change curves were obtained; specimens were examined by metallographical techniques, scanning electron microscopy and EDX analyses.

Findings

Salt deposits attacked steels and coatings during the exposure. The corrosion rates were strongly affected by the composition of the scale formed adjacent to the steels and coatings surfaces. Austenitic steel was only bare material that experienced uniform corrosion in the tests. Ferritic steels were primarily attacked by grain boundary corrosion. Thermally sprayed coatings were mainly attached through oxides and voids at splat boundaries. FeCrAl and 50Ni‐50Cr were prone to spalling. Tafaloy 45CT is also a promising method for producing homogenous coatings. Cr3C2‐NiCr 80/20 coating remained mostly intact.

Originality/value

This paper provides useful information about corrosion behaviours of four coatings used for common boiler tubes. It shows with a practical explanation how the bare material and coatings react in corrosion simulated environments.

Details

Anti-Corrosion Methods and Materials, vol. 54 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 29 April 2014

Debasis Das Adhikary, Goutam Kumar Bose, Dipankar Bose and Souren Mitra

The purpose of this paper is to present a multi criterion failure mode effect and criticality analysis for coal-fired thermal power plants using uncertain data as well as…

Abstract

Purpose

The purpose of this paper is to present a multi criterion failure mode effect and criticality analysis for coal-fired thermal power plants using uncertain data as well as substituting the traditional risk priority number estimation method.

Design/methodology/approach

Grey-complex proportional assessment (COPRAS-G) method, a multi criteria decision making tool is applied to evaluate the criticalities of the failure modes (alternatives). In this model the criteria (criticality factor) against each alternative are expressed in grey number instead of crisp values.

Findings

Rupture failure of the straight tube of economizer (ECO) due to erosion is the highest critical failure mode whereas rupture failure of the stub of ECO due to welding defect is the lowest critical failure mode.

Originality/value

This paper incorporates human and environmental factors as additional factors which also influence the failure modes significantly. The COPRAS-G method is modified according this problem. Uncertainty in the scoring of criticality factors against each failure mode by various maintenance personnel is expressed in grey numbers.

Details

International Journal of Quality & Reliability Management, vol. 31 no. 5
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 1 November 1980

C.A. Smith

Other Industrial Gases All oxidising gases can lead to oxide formation on chromium steels at elevated temperatures and in some instances this can be associated with…

Abstract

Other Industrial Gases All oxidising gases can lead to oxide formation on chromium steels at elevated temperatures and in some instances this can be associated with absorption of some other substance in the steel. Carbonaceous gases are a good example and whereas high‐alloy steels successfully resist flue gases even under conditions of considerable air deficiency, reduction of oxygen content eventually leads to conditions under which at a sufficiently high temperature considerable carburisation of the metal occurs. An example is the endothermic gases used as protective atmospheres for other metals which, at elevated temperature, can rapidly cause embrittlement of high‐alloy steel.

Details

Anti-Corrosion Methods and Materials, vol. 27 no. 11
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 1 November 1958

Nigel Seely

In broad terms the object of every engineer operating oil burning plant has always been to obtain the maximum amount of effective B.Th.U.s for every pound of oil burned…

Abstract

In broad terms the object of every engineer operating oil burning plant has always been to obtain the maximum amount of effective B.Th.U.s for every pound of oil burned. Recently, however, it has been established that as the thermal efficiency of modern high pressure, high temperature oil burning plant has increased there has been a similar increase in corrosion. The extent of this problem is due to the fact that currently available residual fuel oils contain inorganic substances, amongst them vanadium, sodium and sulphur. If these substances were not present hydrocarbon petroleum oils would merely be burned to yield carbon dioxide and water.

Details

Anti-Corrosion Methods and Materials, vol. 5 no. 11
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 1 February 2021

Sushovan Chatterjee, Subhasish Das and Neelam Kumar Sarma

The heat transfer within a heat exchanger is highly influenced by geometry of the components especially those with hollow structures like tubes. This paper aims to intend…

Abstract

Purpose

The heat transfer within a heat exchanger is highly influenced by geometry of the components especially those with hollow structures like tubes. This paper aims to intend toward the study of efficient and optimized heat transfer in the bends of superheater tubes, with different curvature ratio at constant Reynolds Number.

Design/methodology/approach

The effect of changing curvature ratio on enthalpy of the fluid passing through the superheater tubes for multi-pass system has been studied with the aid of computational fluid dynamics (CFD) using ANSYS 14.0. Initially a superheater tube with two pass system has been examined with different curvature ratios of 1.425, 1.56, 1.71, 1.85 and 1.99. An industry specified curvature ratio of 1.71 with two pass is investigated, and a comparative assessment has been carried out. This is intended toward obtaining an optimized radius of curvature of the bend for enhancement of heat transfer.

Findings

The results obtained from software simulation revealed that the curvature ratio of 1.85 provides maximum heat transfer to the fluid flowing through the tube with two pass. This result has been found to be consistent with higher number of passes as well. The effect of secondary flow in bends of curvature has also been illustrated in the present work.

Research limitations/implications

The study of heat transfer in thermodynamic systems is a never-ending process and has to be continued for the upliftment of power plant performances. This study has been conducted on steady flow behavior of the fluid which may be upgraded by carrying out the same in transient mode. The impact of different curvature ratios on some important parameters such as heat transfer coefficients will certainly upgrade the value of research.

Originality/value

This computational study provided comprehensive information on fluid flow behavior and its effect on heat transfer in bends of curvature of superheater tubes inside the boiler. It also provides information on optimized bend of curvature for efficient heat transfer process.

Details

World Journal of Engineering, vol. 18 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 1 September 1965

Combustion Chemicals Ltd., of Guildford Street, Chertsey, Surrey, announce that, following an extensive programme of research and field trials, the Desulfurol fuel…

Abstract

Combustion Chemicals Ltd., of Guildford Street, Chertsey, Surrey, announce that, following an extensive programme of research and field trials, the Desulfurol fuel treatment process now incorporates further improvements in its formulation and will in future be known as New Desulfurol corrosion inhibitor and fuel oil improver. Every aspect of fuel treatment has been covered by field trials over the last two years and the resulting data indicate that the improved formulation represents a considerable technical advance over the usual run of fuel additives, particularly in respect of low‐ and high‐temperature corrosion and of acidic smut emission.

Details

Anti-Corrosion Methods and Materials, vol. 12 no. 9
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 1 January 1989

Low cost stainless steel in cooling tower construction. 3CR12 low cost stainless steel from Cromweld Steels is helping to keep commercial and industrial buildings cool all…

Abstract

Low cost stainless steel in cooling tower construction. 3CR12 low cost stainless steel from Cromweld Steels is helping to keep commercial and industrial buildings cool all over the UK.

Details

Anti-Corrosion Methods and Materials, vol. 36 no. 1
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 5 June 2017

Amrita Kumari, S.K. Das and P.K. Srivastava

This paper aims to propose an efficient artificial neural network (ANN) model using multi-layer perceptron philosophy to predict the fireside corrosion rate of superheater

Abstract

Purpose

This paper aims to propose an efficient artificial neural network (ANN) model using multi-layer perceptron philosophy to predict the fireside corrosion rate of superheater tubes in coal fire boiler assembly using operational data of an Indian typical thermal power plant.

Design/methodology/approach

An efficient gradient-based network training algorithm has been used to minimize the network training errors. The input parameters comprise of coal chemistry, namely, coal ash and sulfur contents, flue gas temperature, SOX concentrations in flue gas, fly ash chemistry (Wt.% Na2O and K2O).

Findings

Effects of coal ash and sulfur contents, Wt.% of Na2O and K2O in fly ash and operating variables such as flue gas temperature and percentage excess air intake for coal combustion on the fireside corrosion behavior of superheater boiler tubes have been computationally investigated and parametric sensitivity analysis has been undertaken.

Originality/value

Quite good agreement between ANN model predictions and the measured values of fireside corrosion rate has been observed which is corroborated by the regression fit between these values.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 7 March 2016

Fei Zhong, Chunlei Zhang, Wensheng Li, Jingpin Jiao and Liqiang Zhong

Super304H steel is a new fine-grained austenitic heat-resistant stainless steel developed in recent years, and it is widely used in high temperature section superheater

Abstract

Purpose

Super304H steel is a new fine-grained austenitic heat-resistant stainless steel developed in recent years, and it is widely used in high temperature section superheater and reheater tubes of ultra-supercritical thermal power units’ boiler. Currently intergranular corrosion (IGC) has occurred in a few austenitic stainless steel tubes in ultra-supercritical units and led to boiler leakage. The purpose of this paper is to find a nondestructive method to quickly and easily detect IGC of austenitic stainless steel tube.

Design/methodology/approach

This paper uses the nonlinear characteristics of ultrasonic propagation in steel tube to detect the IGC of Super304H tube.

Findings

The experimental results show that the nonlinear coefficient generally increases sensitively with the degree of IGC; hence, the nonlinear coefficient can be used to assess IGC degree of tubes, and the nonlinear coefficient measurement method is repeatable for the same tube.

Research limitations/implications

A theory of how IGC would affect the ultrasonic signals and lead to a nonlinear response needs further research.

Practical implications

A nondestructive method to quickly and easily detect IGC is provided.

Social implications

Using ultrasonic nonlinear coefficient to assess IGC degree of tubes is a new try.

Originality/value

This paper provides a new way to test IGC.

Details

Anti-Corrosion Methods and Materials, vol. 63 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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