scholarly journals ROTARY FURNACE LINING TO REDUCE THERMAL STRESS

2021 ◽  
pp. 56-61
Keyword(s):  
Thermal Stress ◽  
Service Life ◽  
Thermal Stresses ◽  
Rotary Furnace ◽  
Raw Material ◽  
Cement Clinker ◽  
Furnace Lining ◽  
Fuel Savings ◽  
Magnesite Refractory ◽  
Rotary Kilns

The aim of the study is to reduce the thermal stresses of the lining in the areas adjacent to the flare sintering zone of rotary kilns intended for the production of cement clinker. It is proposed to use a lining made of parallel rows of alternating chamotte and chromium-magnesite refractory products to reduce thermal stresses in the areas adjacent to the flare sintering zone by up to 20%, increase the service life of the lining by 1.1-1.2 times as a result of equalizing thermal stresses in the areas of the sintering zone. Optimization of the initial raw material mixture, in turn, made it possible to reduce the temperature of clinker formation and led to fuel savings.

Pengaruh Penggunaan Batu Basalt Lampung dan Batubara dalam Bahan Baku terhadap Karakteristik Klinker

2020 ◽  
Vol 10 (1) ◽  
pp. 49
Author(s):  
Suharto Suharto ◽  
Muhammad Amin ◽  
Muhammad Al Muttaqii ◽  
Syafriadi Syafriadi ◽  
Kiki Nurwanti
Keyword(s):  
Experimental Study ◽  
Raw Materials ◽  
Coal Ash ◽  
Heating Time ◽  
Raw Material ◽  
Silica Sand ◽  
Cement Clinker ◽  
Duration Of Heating

Experimental study on the use of basalt stone originated from Lampung has been conducted to evaluate its potential for a partial substitute of raw material in production of cement clinker. The basalt stone contains minerals of anorthite, augite, and albite phases that are required for clinker formation. In this study, the main raw materials were 80% limestone, 10% silica sand, 9% clay and 1% iron sand. The raw material in these experiments were mixtures 90% or 80% of the main raw material and 10% or 20% of basalt stone. The effect of adding coal to raw materials was also studied to see the possibility of an increase in clinkerization temperature inside the raw material mixture, and at the same time to see the effect of coal ash on clinker composition. Clinker obtained from heating of raw materials at a temperature of 1100oC had LSF of 94.1% and 95.1% (heating time of 1 and 3 hours). If heating is carried out at 1200oC, the clinker had LSF of 97.7% and 98.0% (heating time of 2 and 3 hours, respectively). Depending on the temperature and duration of heating, the clinker mostly had SM in the range of 2.18-2.40% , and AM in the range of 0,78-1.80%. Characterization using XRD showed that the clinker consisted of larnite and gehlenite phases, and dominated by CaO.Batu basalt Lampung telah diuji potensinya sebagai pengganti sebagian bahan baku utama pembuatan klinker semen. Batu basalt tersebut memiliki mineral-mineral dalam fase anorthite, augite, dan albite yang diperlukan pada pembentukan klinker. Pada penelitian ini, bahan baku utama adalah batu kapur 80%, pasir silika 10%, tanah liat 9% dan pasir besi 1%. Campuran bahan baku klinker adalah 90% atau 80% bahan baku utama dan 10% atau 20% batu basalt. Efek penambahan batubara ke dalam bahan baku klinker juga dipelajari untuk melihat kemungkinan kenaikan temperatur klinkerisasi di dalam campuran bahan baku, dan sekaligus untuk melihat efek abu batubara terhadap komposisi klinker. Klinker hasil pemanasan bahan baku pada temperatur 1100oC memiliki LSF 94,1% dan 95,1% (lama pemanasan 1 dan 3 jam). Jika pemanasan dilakukan pada 1200oC, klinker memilik LSF 97,7% dan 98,00% (lama pemanasan 2 dan 3 jam). Tergantung pada temperatur dan lama pemanasan, klinker hasil percobaan ini umumnya memiliki SM 2,18-2,40%, dan AM antara 0,78-1,80%. Karakterisasi dengan XRD menunjukkan bahwa klinker terdiri dari fase larnite dan gehlenite, dan didominasi CaO.

scholarly journals Methodology for the quantification of concrete sustainability

2018 ◽  
Vol 174 ◽  
pp. 01006 ◽  
Author(s):  
Břetislav Teplý ◽  
Tomáš Vymazal ◽  
Pavla Rovnaníková
Keyword(s):  
Decision Making ◽  
Life Cycle Assessment ◽  
Life Cycle ◽  
Environmental Impact ◽  
Service Life ◽  
Circular Economy ◽  
Point Of View ◽  
Raw Material ◽  
Load Bearing Capacity ◽  
Sustainability Management

Efficient sustainability management requires the use of tools which allow material, technological and construction variants to be quantified, measured or compared. These tools can be used as a powerful marketing aid and as support for the transition to “circular economy”. Life Cycle Assessment (LCA) procedures are also used, aside from other approaches. LCA is a method that evaluates the life cycle of a structure from the point of view of its impact on the environment. Consideration is given also to energy and raw material costs, as well as to environmental impact throughout the life cycle - e.g. due to emissions. The paper focuses on the quantification of sustainability connected with the use of various types of concrete with regard to their resistance to degradation. Sustainability coefficients are determined using information regarding service life and "eco-costs". The aim is to propose a suitable methodology which can simplify decision-making in the design and choice of concrete mixes from a wider perspective, i.e. not only with regard to load-bearing capacity or durability.

Three Turnaround Heat Treating Studies

2003 ◽  
Author(s):  
Jaan Taagepera ◽  
Marty Clift ◽  
D. Mike DeHart ◽  
Keneth Marden
Keyword(s):  
Heat Treatment ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Heat Treating ◽  
Element Analysis ◽  
Stress Profiles ◽  
Insight Into

Three vessel modifications requiring heat treatment were analyzed prior to and during a planned turnaround at a refinery. One was a thick nozzle that required weld build up. This nozzle had been in hydrogen service and required bake-out to reduce the potential for cracking during the weld build up. Finite element analysis was used to study the thermal stresses involved in the bake-out. Another heat treatment studied was a PWHT of a nozzle replacement. The heat treatment band and temperature were varied with location in order to minimize cost and reduction in remaining strength of the vessel. Again, FEA was used to provide insight into the thermal stress profiles during heat treatment. The fmal heat treatment study was for inserting a new nozzle in a 1-1/4Cr-1/2Mo reactor. While this material would ordinarily require PWHT, the alteration was proposed to be installed without PWHT. Though accepted by the Jurisdiction, this nozzle installation was ultimately cancelled.

Steady-State Thermal Stresses in Wedge-Shaped Cutting Tools

1975 ◽  
Vol 97 (3) ◽  
pp. 1060-1066
Author(s):  
P. F. Thomason
Keyword(s):  
Thermal Stress ◽  
Steady State ◽  
Metal Cutting ◽  
Thermal Stresses ◽  
Heat Conduction Problem ◽  
Equivalent Stress ◽  
Cutting Tools ◽  
Thermoelastic Stress ◽  
Plastic State ◽  
Steady State Heat

Closed form expressions for the steady-state thermal stresses in a π/2 wedge, subject to constant-temperature heat sources on the rake and flank contact segments, are obtained from a conformal mapping solution to the steady-state heat conduction problem. It is shown, following a theorem of Muskhelishvili, that the only nonzero thermal stress in the plane-strain wedge is that acting normal to the wedge plane. The thermal stress solutions are superimposed on a previously published isothermal cutting-load solution, to give the complete thermoelastic stress distribution at the wedge surfaces. The thermoelastic stresses are then used to determine the distribution of the equivalent stress, and this gives an indication of the regions on a cutting tool which are likely to be in the plastic state. The results are discussed in relation to the problems of flank wear and rakeface crater wear in metal cutting tools.

Modelling of Convective Melt Flow and Interface Shape in Commercial Bridgman-Stockbarger Growth of CdZnTe

2000 ◽  
Author(s):  
Toby D. Rule ◽  
Ben Q. Li ◽  
Kelvin G. Lynn
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Solute Transport ◽  
Latent Heat ◽  
Thermal Stresses ◽  
Radiation Detector ◽  
Time History ◽  
High Quality ◽  
Melt Convection ◽  
The Impact

Abstract CdZnTe single crystals for radiation detector and IR substrate applications must be of high quality and controlled purity. The growth of such crystals from a melt is very difficult due to the low thermal conductivity and high latent heat of the material, and the ease with which dislocations, twins and precipitates are introduced during crystal growth. These defects may be related to solute transport phenomena and thermal stresses associated with the solidification process. As a result, production of high quality material requires excellent thermal control during the entire growth process. A comprehensive model is being developed to account for radiation and conduction within the furnace, thermal coupling between the furnace and growth crucible, and finally the thermal stress fields within the growing crystal which result from the thermal conditions imposed on the crucible. As part of this effort, the present work examines the heat transfer and fluid flow within the crucible, using thermal boundary conditions obtained from experimental measurements. The 2-D axisymetric numerical model uses the deforming finite element method, with allowance made for melt convection, solidification with latent heat release and conjugate heat transfer between the solid material and the melt. Results are presented for several stages of growth, including a time-history of the solid-liquid interface (1365 K isotherm). The impact of melt convection, thermal end conditions and furnace temperature gradient on the growth interface is evaluated. Future work will extend the present model to include radiation exchange within the furnace, and a transient analysis for studying solute transport and thermal stress.

scholarly journals Measurement and Isolation of Thermal Stress in Silicon-On-Glass MEMS Structures

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2603 ◽  
Author(s):  
Zhiyong Chen ◽  
Meifeng Guo ◽  
Rong Zhang ◽  
Bin Zhou ◽  
Qi Wei
Keyword(s):  
Thermal Stress ◽  
Natural Frequency ◽  
Frequency Conversion ◽  
Thermal Stresses ◽  
Sensors And Actuators ◽  
Stress Variation ◽  
Rigid Frame ◽  
Measured Stress ◽  
Stress Isolation ◽  
Frequency Variations

The mechanical stress in silicon-on-glass MEMS structures and a stress isolation scheme were studied by analysis and experimentation. Double-ended tuning forks (DETFs) were used to measure the stress based on the stress-frequency conversion effect. Considering the coefficients of thermal expansion (CTEs) of silicon and glass and the temperature coefficient of the Young’s modulus of silicon, the sensitivity of the natural frequency to temperature change was analyzed. A stress isolation mechanism composed of annular isolators and a rigid frame is proposed to prevent the structure inside the frame from being subjected to thermal stresses. DETFs without and with one- or two-stage isolation frames with the orientations <110> and <100> were designed, the stress and natural frequency variations with temperature were simulated and measured. The experimental results show that in the temperature range of −50 °C to 85 °C, the stress varied from −18 MPa to 10 MPa in the orientation <110> and −11 MPa to 5 MPa in the orientation <100>. For the 1-stage isolated DETF of <110> orientation, the measured stress variation was only 0.082 MPa. The thermal stress can be mostly rejected by a stress isolation structure, which is applicable in the design of stress-sensitive MEMS sensors and actuators.

Numerical Study of Thermal Stresses in a Planar Solid Oxide Fuel Cell Stack

2017 ◽  
Author(s):  
Cun Wang ◽  
Tao Zhang ◽  
Cheng Zhao ◽  
Jian Pu
Keyword(s):  
Thermal Stress ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Numerical Study ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Compressive Loads ◽  
Cte Mismatch

A three dimensional numerical model of a practical planar solid oxide fuel cell (SOFC) stack based on the finite element method is constructed to analyze the thermal stress generated at different uniform temperatures. Effects of cell positions, different compressive loads, and coefficient of thermal expansion (CTE) mismatch of different SOFC components on the thermal stress distribution are investigated in this work. Numerical results indicate that the maximum thermal stress appears at the corner of the interface between ceramic sealants and cells. Meanwhile the maximum thermal stress at high temperature is significantly larger than that at room temperature (RT) and presents linear growth with the increase of operating temperature. Since the SOFC stack is under the combined action of mechanical and thermal loads, the distribution of thermal stress in the components such as interconnects and ceramic sealants are greatly controlled by the CTE mismatch and scarcely influenced by the compressive loads.

scholarly journals Numerical Simulation Study on the Front Shape and Thermal Stresses in Growing Multicrystalline Silicon Ingot: Process and Structural Design

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1053
Author(s):  
Chengmin Chen ◽  
Guangxia Liu ◽  
Lei Zhang ◽  
Guodong Wang ◽  
Yanjin Hou ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Simulation Method ◽  
Power Ratio ◽  
Radial Temperature ◽  
Front Shape ◽  
Simulation Results ◽  
Insulation Block ◽  
Transient Numerical Simulation

In this paper, a transient numerical simulation method is used to investigate the effects of the two furnace configurations on the thermal field: the shape of the melt–crystal (M/C) interface and the thermal stress in the growing multicrystalline ingot. First, four different power ratios (top power to side power) are investigated, and then three positions (i.e., the vertical, angled, and horizontal positions) of the insulation block are compared with the conventional setup. The power ratio simulation results show that with a descending power ratio, the M/C interface becomes flatter and the thermal stress in the solidified ingot is lower. In our cases, a power ratio of 1:3–1:4 is more feasible for high-quality ingot. The block’s position simulation results indicate that the horizontal block can more effectively reduce the radial temperature gradient, resulting in a flatter M/C interface and lower thermal stress.

scholarly journals Post mortem analysis of burned magnesia-chromite brick used in short rotary furnace of secondary lead smelting

Cerâmica ◽  
2009 ◽  
Vol 55 (333) ◽  
pp. 61-66 ◽  
Author(s):  
E. Prestes ◽  
A. S. A. Chinelatto ◽  
W. S. Resende
Keyword(s):  
Reduction Process ◽  
Rotary Furnace ◽  
Furnace Lining ◽  
X Ray Diffraction ◽  
Good Resistance ◽  
Metallic Lead ◽  
Parallel Cracks ◽  
Standard Product ◽  
Short Service Life ◽  
Powder Analysis

Burned magnesia-chromite bricks are the standard product for the lining of furnaces in lead industry, where the short service life is a great problem. Used sintered magnesia-chromite brick sample from short rotary furnace lining, sent by a secondary lead manufacturer, showed parallel cracks to the hot face due to structural spalling damage. The refractory infiltrated region and slag interface were analyzed using a scanning electron microscope with an energy dispersive spectroscopy analyzer, and X-ray diffraction powder analysis. Crucible corrosion test was performed to evaluate the influence of slag attack. The results showed that the structural spalling was due to strong Pb-infiltration of the refractory microstructure by bath components of the furnace (metallic lead and lead sulphite) during the reduction process and that the slag infiltration had little contribution due to the good resistance of the magnesia-chromite bricks to FeO rich slag attack.

scholarly journals An Elastoplastic Thermal-Stress Analysis of a Free Plate

1956 ◽  
Vol 23 (3) ◽  
pp. 395-402
Author(s):  
Jerome Weiner
Keyword(s):  
Thermal Stress ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Uniqueness Theorem ◽  
Unique Solution ◽  
Heat Input ◽  
Thermal Stresses ◽  
Elastoplastic Material ◽  
Heuristic Solution ◽  
Peak Magnitude

Abstract The thermal stresses in a free plate of elastoplastic material subjected to a varying heat input over one face are determined. A heuristic solution is first found by suitable modifications of the known elastic solution. It is then verified that the solution satisfies all the conditions of the appropriate uniqueness theorem and represents therefore the unique solution to the problem. Residual stresses are determined and found to depend markedly on the peak magnitude of the heat input.

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