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Article
Publication date: 13 June 2008

J. Boran, L. Houdkova, V. Ucekaj and P. Stehlik

The purpose of this paper is to compare well‐known technologies of sludge utilization on the basis of energy and economical balances of real processes. The calculations…

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Abstract

Purpose

The purpose of this paper is to compare well‐known technologies of sludge utilization on the basis of energy and economical balances of real processes. The calculations are based on pilot tests in the Central Waste Water Treatment Plant (CWWTP) in Prague, the biggest waste water treatment plant in the Czech Republic.

Design/methodology/approach

A key issue for the comparison of mass and energy flow of sludge management is the attainable level of sludge dewaterability. Results of dewatering of anaerobic digested sludge are available from real applications since most sewage plants use digesters. The existing limited knowledge about mixed raw sludge (MRS) dewaterability have driven authors to make pilot tests targeted to establishment of an attainable level of MRS dewaterability. To get as close results as possible even anaerobic stabilized sludge was dewatered and various other data were collected to obtain a comprehensive data set for energy balance of the sludge management calculation. The pilot tests took place at CWWTP in 2005. Measured data were used to calculate energy balance of a number of different sludge managements.

Findings

To produce self‐reliant combusting sludge, a dry matter content of 35‐45 per cent for MRS and 45‐55 per cent for digested sludge has to be achieved by means of dewatering and potentially drying. In recent measurements at CWWTP a dry matter content of about 33 per cent was achieved by dewatering of MRS. This value is very close to the range of the dry matter content at which a self reliant combustion can be expected.

Practical implications

This comparison together with investment cost analysis should be one of the most important parameters in case of design a new or revamp an old waste water treatment plant.

Originality/value

The paper provides results from pilot tests at CWWTP together with three different energy balances comparison.

Details

Management of Environmental Quality: An International Journal, vol. 19 no. 4
Type: Research Article
ISSN: 1477-7835

Keywords

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Article
Publication date: 2 January 2018

Mohsen Shabanlo, Reza Amini Najafabadi and Amirhossein Meysami

This study aims to investigate the effect of post heat treatment on mechanical properties of NiCrBSi coatings, which were applied on 316L stainless steel using…

Abstract

Purpose

This study aims to investigate the effect of post heat treatment on mechanical properties of NiCrBSi coatings, which were applied on 316L stainless steel using high-velocity oxygen-fuel (HVOF) and flame spray techniques.

Design/methodology/approach

The properties of coatings were investigated by metallographic characterizations as well as wear, micro-hardness and adhesion tests.

Findings

The micro-hardness results showed that the coatings considerably increased the sub-layer hardness. In addition, regarding the wear test results, it can be seen that heat treatment increased wear resistance of the coatings. These thermal sprayed coatings are usually re-melted by post heat treatment, leading to improvement in tribological properties. The results obtained revealed that re-melting procedure improved the metallurgical bonding in the substrate\coating interface.

Originality/value

Microstructure defects resulting from thermal spraying such as pores and unmelted particles can be eliminated by post heat treatment. This process can considerably improve the corrosion and wear resistances of the thermal sprayed coatings.

Details

Anti-Corrosion Methods and Materials, vol. 65 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 18 November 2019

Manoj Kumar and Rohit Upadhyaya

The purpose of this paper is to develop the high pressure high-velocity oxy-liquid fuel sprayed WC-10Co-4Cr coatings on geothermal turbine 9Cr-1Mo steel for protection…

Abstract

Purpose

The purpose of this paper is to develop the high pressure high-velocity oxy-liquid fuel sprayed WC-10Co-4Cr coatings on geothermal turbine 9Cr-1Mo steel for protection against wear and corrosion.

Design/methodology/approach

The microstructural characterization of as-deposited and corroded coating was done and presented using X-ray diffraction and scanning electron microscope/energy dispersive spectroscopy analysis.

Findings

The developed coating offered 50 per cent enhanced microhardness (1,200 HV) and 100 per cent enhanced wear resistance, in comparison to bare geothermal turbine steel, respectively. The coating has shown enhanced life in the simulated working conditions (fog test and dip test). This may be because of the high microhardness of the developed coating as per the proven tribological theories.

Originality/value

Coating offered excellent corrosion resistance in the harsher simulated environments to geothermal turbines.

Details

World Journal of Engineering, vol. 16 no. 6
Type: Research Article
ISSN: 1708-5284

Keywords

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Article
Publication date: 26 November 2018

Shaikh Asad Ali Dilawary, Amir Motallebzadeh, Muhammad Afzal, Erdem Atar and Huseyin Cimenoglu

The purpose of the study is to examine the sliding wear performance of plasma transfer arc (PTA) deposited and laser surface melted (LSM) Mo modified Stellite 12…

Abstract

Purpose

The purpose of the study is to examine the sliding wear performance of plasma transfer arc (PTA) deposited and laser surface melted (LSM) Mo modified Stellite 12 hardfacings under high contact stresses (i.e. >20 GPa).

Design/methodology/approach

For this purpose, after structural characterization, sliding wear tests have been conducted using sphero-conical diamond indenter as the counterface with different normal loads. The wear tracks formed on the hardfacings were examined by atomic force microscopy and scanning electron microscopy.

Findings

Both hardfacings showed severe wear (at high contact stress levels ranging from 24 to 41 GPa), which progressed by plastic deformation, although the wear resistance of LSMed hardfacings was better than the PTA hardfacings by a factor of two due to its near surface microstructure characterized as carbide-rich zone.

Originality/value

Sliding wear characterization of a promising 10 Wt.% Mo modified version of commercial Stellite 12 hardfacings (as reported previously by authors) was done in as PTA and LSMed states using nanomechanical test system. To the best of authors’ knowledge, no report is available in the open literature on such hardfacings under these testing conditions.

Details

Industrial Lubrication and Tribology, vol. 72 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 16 August 2019

Vivek Bhardwaj, R.K. Pandey and V.K. Agarwal

The purpose of this paper is to develop an energy-efficient and dynamically improved thrust ball bearing using textured race. A texture has been used on the stationary…

Abstract

Purpose

The purpose of this paper is to develop an energy-efficient and dynamically improved thrust ball bearing using textured race. A texture has been used on the stationary race of the test bearing to conduct the long-duration experiment for exploring its tribological and vibrational behaviours under starved lubricating condition using micro size MoS2 blended grease. The performance behaviours of the textured race bearing have been compared with conventional bearing (i.e. having both races without textures) under the identical operating conditions for demonstrating the advantages of textured race.

Design/methodology/approach

Texture was created on stationary race of the test ball bearing (51308) using nano-second pulsed Nd: YAG laser. Performance parameters (frictional torque, temperature rise and vibrations) of textured ball bearings were measured under severe starved lubricating conditions for understanding the critical role of texture in the long duration of the test. S-type load cell and miniature accelerometer were used for measuring the frictional torque and vibration, respectively. Bulk temperature at stationary races (at the back side) of test bearings was measured in operating conditions using a non-contact infrared thermometer.

Findings

Significant reduction in frictional torque and decrease in amplitude of vibration with textured ball bearing were found even under the severe starved lubricating condition in comparison to conventional bearing.

Originality/value

There is dearth of research pertaining to the performance behaviours of ball bearings using textures on the races. Therefore, an attempt has been made in this study to explore the tribo-dynamic performance behaviours of a thrust ball bearing using a texture on its stationary race under severe starved lubricating condition for the longer duration of the test.

Details

Industrial Lubrication and Tribology, vol. 71 no. 9
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 12 April 2019

Ali Abdul Munim Alhattab, Shaikh Asad Ali Dilawary, Amir Motallebzadeh, Cevat Fahir Arisoy and Huseyin Cimenoglu

The purpose of this study is to investigate the effect of electron beam surface melting (EBSM) on the properties of Plasma Transfer Arc (PTA) deposited Stellite 12 hardfacing.

Abstract

Purpose

The purpose of this study is to investigate the effect of electron beam surface melting (EBSM) on the properties of Plasma Transfer Arc (PTA) deposited Stellite 12 hardfacing.

Design/methodology/approach

For this purpose, structural characterization and dry sliding wear tests have been conducted on the hardfacings at room temperature. The wear tracks formed on the surfaces of the hardfacings were examined by a stylus-type profilometer and a scanning electron microscope.

Findings

Refinement of the matrix and the carbides following EBSM process led to about 15 per cent increment in hardness as compared to PTA state. Despite an increase in the surface hardness, EBSM’ed hardfacing exhibited about 50 per cent lower sliding wear resistance than PTA hardfacing against alumina ball. According to the worn surface examinations, reduction in the wear resistance of Stellite 12 after EBSM process has been associated with the extensive refinement of the carbides which made them easier to be removed from the matrix during the sliding contact.

Originality/value

The authors of current study have applied EBSM to PTA deposited Stellite 12 hardfacing alloy to investigate if the surface structure and properties could be improved. More specifically the dry sliding wear performance of PTA and EBSM’ed hardfacings have been focused in the scope of this study. To the best of the authors’ knowledge, this approach, i.e. use of EBSM as a post deposition treatment of Stellite 12 hardfacings, has not been reported in open literature.

Details

Industrial Lubrication and Tribology, vol. 71 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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