| 1. |
- Andersson, Britt M., et al.
(författare)
-
Electrical transport in dense, bulk YBa2Cu4O8 produced by hot isostatic pressing
- 1990
-
Ingår i: Physica B Volumes 165 & 166, Part 2. - : Elsevier B.V.. ; , s. 1699-1700
-
Konferensbidrag (refereegranskat)abstract
- Dense (98.5%) bulk sintered specimens of YBa2Cu4O8 have been produced by hot isostatic pressing. Data for the electrical resistivity π versus temperature T and pressure p in the range 70–300 K and 0–0.7 GPa are reported and discussed. The critical current density of the material studied exceeds 100 Acm−2 below 60 K.
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| 2. |
- Andersson, Britt M., et al.
(författare)
-
Electrical transport properties of dense bulk YBa2Cu4O8 produced by hot isostatic pressing
- 1990
-
Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 170:5-6, s. 521-531
-
Tidskriftsartikel (refereegranskat)abstract
- Highly dense sintered YBa2Cu4O8 has been produced by hot isostatic pressing (HIP). The electrical resistivity varrho of this material has been measured as a function of temperature T and pressure varrho in the range 40–650 K and 0–0.7 GPa. Both the temperature dependence and the pressure dependence of varrho are found to be well described by a model based on the standard Bloch-Grüneisen theory. It is pointed out that varrho is liner in T only under isobaric conditions, while varrho is strongly nonlinear in all high-Tc superconductors under isochoric (constant volume) conditions. The critical current density of the material is 900 A/cm2 at 4 K, while the resistivity is 630 μΩ cm at 294 K.
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| 3. |
- Andersson, Britt M., et al.
(författare)
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High-pressure properties of high-Tc superconductor samples produced by hot isostatic pressing
- 1990
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Ingår i: High Pressure Research, volumes 3 to 5. - London : Gordon and Breach. - 2881247466 ; 3:1-6, s. 123-125
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Konferensbidrag (refereegranskat)abstract
- The electrical resistance of dense YBa2Cu3Ox and YBa2Cu4Oy produced by hot isostatic pressing has been measured vs. T and p. At 295 K we find d (ln R)/dp ≃ -0.12 and -0.09 GPa-1, respectively, with no systematic dependence on initial density. For 1-2-4, dTC/dp ≃ 5.1 K/GPa, which is ten times that of 1-2-3.
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| 4. |
- Andersson, Britt M., et al.
(författare)
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Thermal conductivity of polycrystalline YBa2Cu4O8
- 1994
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 49:6, s. 4189-4198
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured the thermal conductivity κ and the thermal diffusivity a of a dense bulk ceramic polycrystalline sample of YBa2Cu4O8 (1:2:4) in the temperature range 30–300 K. We find κ≊10 W m-1 K-1 at 100 K, significantly higher than in ceramic YBa2Cu3O7-δ (1:2:3) and approaching the in-plane value for single-crystal 1:2:3, and decreasing to 7.6 W m-1 K-1 at 300 K. The data for this sample can be described by standard theories for phonon thermal conductivity of crystalline materials with boundary, phonon, and electron scattering. The higher κ in 1:2:4 as compared to 1:2:3 is, in this model, due to the smaller point defect scattering in the former. The fitted parameters for the three scattering mechanisms all agree with independent estimates based on simple models; inserting data for electric resistivity, grain size, carrier density, and lattice properties we can predict κ and its T dependence to within about 20%. We also discuss models for the phonon and electron thermal conductivities in some detail, including some second-order effects such as inelastic electron scattering and a T-dependent carrier density.
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| 5. |
- Cuervo-Piñera, Victor, et al.
(författare)
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Blast Furnace Gas Based Combustion Systems in Steel Reheating Furnaces
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; , s. 357-364
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Konferensbidrag (refereegranskat)abstract
- The usage of steelmaking process gases in thermoprocessing plants is the most efficient way to reduce the natural gas dependence and therefore both fuel costs and carbon footprint in steelworks. Furthermore NOx emissions can be cut by firing lean gases considering their low adiabatic flame temperatures. A European funded project aiming to enhance the usage of blast furnace gas (BFG) in steel reheating furnaces has been successfully accomplished by a multidisciplinary international consortium of research centers (ArcelorMittal Global R&D Asturias and Maizières, Centro Sviluppo Materiali, Swerea MEFOS, VDEh-Betriebsforschungsinstitut), burner suppliers (Tenova, AGA Linde) and end-users (ArcelorMittal). Three innovative preheated fuel gas burner technologies, namely double regenerative air-fuel, oxy-fuel and flat-flame burners, have been designed and manufactured for 100% BFG firing, so that the inherent constraints of burning very lean gases have been overcome. On the one hand, flameless oxy-fuel combustion with central preheated BFG, so that capital expenditures are limited, allowing easily furnaces retrofitting and potentially carbon capture. On the other hand, for air burners a dual honeycomb regenerator that preheats both air and BFG streams at the burner level, so that operating costs are reduced. Finally, an oxy-regenerative flat-flame burner that transfers homogeneously radiant heat to the load, combining the two beforehand mentioned technologies that are used mainly for high capacity burners (higher than 0.5-1 MW). These systems have been tested (long-term) at both pilot plant and industrial scale in order to define the guidelines for a safe application in the industrial environment, to address technical and economic issues and to put forward guidelines for retrofitting existing furnaces. Moreover, computational fluid dynamics (CFD) modelling has been carried out and validated with the pilot testing results, so that a numerical set-up has been defined for BFG firing. For this purpose a new radiation model for the radiative properties of the products of combustion of BFG has been developed, considering the low water vapor-carbon dioxide ratio. By means of preheating BFG with the waste heat content in flue gases stream, the typical operating temperatures of reheating furnaces (1350°C) have been achieved without natural gas enrichment, keeping the NOx emissions level below the European regulation threshold. © 2017 The Authors. Published by Elsevier Ltd.
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| 6. |
- Diederichs, J., et al.
(författare)
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Critical currents in Tl-2122 and Y-124 sinters under high hydrostatic pressure
- 1991
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Ingår i: Superconductor Science and Technology, volume 4, Special Issue 1S. - Bristol : Adam Hilger. - 0750301082 ; , s. S97-S99
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Konferensbidrag (refereegranskat)abstract
- Utilizing AC susceptibility measurements the authors have investigated the inter and intragranular properties of selected bulk materials under hydrostatic pressures to 3.5 GPa. A single phase Tl2CaBa2Cu2O8 sample with superconducting transition temperature Tc approximately=107 K shows a clear maximum in Tc(P) at approximately 2.2 GPa coupled with a nearly twofold increase to 3 GPa of the intergranular critical current density JcJ near Tc. The second sample, a YBa2Cu4O8 sinter, shows a large linear increase in Tc with pressure (+5.5 K/GPa) as well as a fivefold increase JcJ to 3 GPa. Applying a critical state model, the authors find that Tc(P) varies as lambda g-2(P), where lambda g is the intragranular (London) penetration depth.
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| 7. |
- Dou, S.X., et al.
(författare)
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Improvement of critical current density in the Bi-Pb-Sr-Ca-Cu-O system through hot isostatic pressing
- 1990
-
Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 167:5-6, s. 525-528
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of hot isostatic pressing (HIPing) on densification and the superconducting properties of the Bi-Pb-Sr-Ca-O system were investigated. A relative density up to 95% and a critical current density greater than 1100 A/cm2 at 77 K were achieved through HIPing at 650°C for 2 h under 200 MPa argon. Under these conditions, the product gave a value of Jc four times that without HIPing. To was unaffected by HIPing for samples encapsulated with a combination of glass and silver tubes. However, To was suppressed from 103 K to 86 K for samples encapsulated with stainless steel and silver tubes while Jc increased from 260 A/ cm2 to 1086 A/cm2 during HIPing, indicating that the weak links were significantly improved. A new minor phase, having a composition of Bi/Pb/Sr/Ca/Cu=0.58/2.8/3.0/2.1/1.1, was observed in HIPed samples but its effect on Jc is not clear
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| 8. |
- Easterling, K.E., et al.
(författare)
-
The microstructure and properties of high Tc superconducting oxides
- 1990
-
Ingår i: Science Progress. - 0036-8504 .- 2047-7163. ; 74:293, s. 69-90
-
Tidskriftsartikel (refereegranskat)abstract
- There has been considerable progress in producing and characterizing high Tc superconductors, but a number of materials science-related problems still exist, before their mechanical and electrical properties meet the requirements of many of the proposed applications. These materials are brittle, ceramic compounds with long unit cells that can be thought of as formed from layers of various oxides are an important common feature. The long unit cell structure leads to anisotropy in their electrical and mechanical properties, including the current carrying capacity or current density Jc. The crystallography and microstructure of the three major families of high Tc superconductors are reviewed and possible solutions to some of the materials problems are presented
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| 9. |
- Grishin, A., et al.
(författare)
-
Straightened voltage effect in high-Tc superconductors
- 1994
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 76:10, s. 6947-6949
-
Tidskriftsartikel (refereegranskat)abstract
- A new effect called ``ac-current straightening'' has been observed in ceramic (Bi,Pb)-2223 slabs carrying ac current Idc+Iac cos(ωt). The current-voltage (I-V) characteristics of the ceramic were measured at 77 K at frequencies ranging from 50 to 20 000 Hz. A spectrum analyzer showed a series of high harmonics in the voltage signal as well as a constant voltage drop. The full set of experimental data has been explained theoretically using the Bean-Kim critical state model with a magnetic field dependent critical current jc(H)=jc(0)/(1+H/H0). A low transport ac current gives a voltage linearly proportional to the frequency and quadratically proportional to the ac-current amplitude Iac. It consists of odd harmonics only. If a bias dc current is switched on, then even harmonics and a dc-voltage drop appear. Their amplitudes are proportional to the small parameter Iac/cH0 and depend on the Idc/Iac ratio.
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| 10. |
- Hu, Yukun, et al.
(författare)
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Zone modelling coupled with dynamic flow pattern for the prediction of transient performance of metal reheating
- 2014
-
Ingår i: AISTech - Iron and Steel Technology Conference Proceedings. - : Association for Iron and Steel Technology, AISTECH. - 9781935117421 ; , s. 3395-3408
-
Konferensbidrag (refereegranskat)abstract
- Relatively robust predictive models for the steel reheating processes are crucial for efficient control and optimisation of reheat furnace operation while ensuring good quality of the heated products. This paper describes the development of a two-dimensional (2D) mathematical model, based on the zone method of radiation analysis, which is capable of simulating the thermal performance of a walking-beam reheating furnace, such as the temperature distribution inside the furnace and the heated stock. The models were initially validated using experimental data supplied by Swerea MEFOS, Sweden. The validated models were further used to investigate changes in the furnace operating conditions, such as production rates and production delay. The results show that the model predictions are in agreement with the measured data and that the model can reasonably respond to the changes in different operating conditions. The developed model has the potential to predict durations of furnace operation of a thousand times faster than the actual run time, and it also demonstrates the feasibility and practicality for incorporation into a model based furnace control system.
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| 11. |
- Loberg, Bengt, et al.
(författare)
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High critical currents in Bi-2223 phase bars
- 1993
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Ingår i: Cryogenics (Guildford). - 0011-2275 .- 1879-2235. ; 33:5, s. 475-476
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Tidskriftsartikel (refereegranskat)abstract
- The critical current Ic and the critical current density Jc of Bi-2223 phase bars have been found to depend on the mass density of the bars. Bars densified using a cold isostatic pressing (CIPing) process have been obtained with transport critical currents of gt;150 A with Jc levels up to approximately equals 103 A cm-2 at 77 K in the absence of an applied magnetic field. Bending or kinking of the grains may promote densification during CIPing of a sintered bar.
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| 12. |
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| 13. |
- Niska, John, et al.
(författare)
-
Combustion Control Using An IR Diode Laser
- 2003
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Tunable diode laser absorption spectroscopy (TDLAS) is a recent development in process instrumentation. A commercial TDLAS instrument has been tested both in an industrial steel reheating furnace and in a pilot furnace at MEFOS for continuous oxygen analysis of the furnace combustion gases. Automatic control of the air-to-fuel ratio (AFR) was proven using a time-averaged oxygen concentration signal with a TDC2000 furnace controller at MEFOS. The oxygen concentrations measured by the TDLAS instrument compared well with local measurements of the oxygen concentration using a conventional zirconia probe in both furnaces. The diode laser has the advantages of high reliability for average gas concentration measurements in the path of the beam, when compared to point gas analysis with conventional zirconia instrumentation. Reliable gas analysis offers the benefits of improved process control, which for steel reheating furnaces include energy savings, reduced emissions and improved productivity.
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| 14. |
- Niska, John, et al.
(författare)
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Effect of oxygen loss on densification when hot isostatic pressing YBa2Cu3O7-δ
- 1989
-
Ingår i: Journal of The American Ceramic Society. - : Wiley. - 0002-7820 .- 1551-2916. ; 72:8, s. 1508-1510
-
Tidskriftsartikel (refereegranskat)abstract
- Hot isostatic pressing of the high-Tc superconductor YBa2Cu3O7-δ can lead to loss of oxygen and transformation of the material from the high-Tc orthorhombic phase to the nonsuperconducting tetragonal phase. It is shown that glass encapsulation helps retain the orthorhombic structure, whereas steel encapsulation resulted in formation of the tetragonal phase. Reasons for this phenomenon are discussed. The equilibrium oxygen gas pressure for the oxygen decomposition reaction in YBa2Cu3O7, however, prevents full densification of this material in glass when employing hot isostatic pressing conditions of 200 MPa and 845°C.
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| 15. |
- Niska, John, et al.
(författare)
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Evidence for unpinned magnetic flux vortices above the Ic transition in the 2223-phase high-Tc superconductor
- 1993
-
Ingår i: Journal of Superconductivity. - 0896-1107 .- 1572-9605. ; 6:4, s. 255-259
-
Tidskriftsartikel (refereegranskat)abstract
- similarity in the dc voltage-current (V I) curves for both direct and alternating transport currents is used to propose that unpinned flux vortices are generated above the Ic transition for dc transport currents, when Abrikosov flux vortices begin to penetrate the superconductor. Two methods can be used to give a dc voltage drop for an ac transport current: (1) if there is a slight dc voltage in the ac current which favors vortex loop collapse as in a traditional dc Ic test, or (2) if an asymmetric transverse magnetic field is present which favors vortex loop collapse for current in one direction over the reverse direction.
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| 16. |
- Niska, John, et al.
(författare)
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Formation of the 124 phase superconductor (YBa2Cu4O8) by retaining oxygen in a reaction HIP sintering process
- 1990
-
Ingår i: Journal of materials science letters. - 0261-8028 .- 1573-4811. ; 9:7, s. 770-771
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Tidskriftsartikel (refereegranskat)abstract
- The ceramic superconductor YBa2Cu4O8 has been produced by high temperature sintering of a mixture of CuO and YBa2Cu3O7 in a glass capsule under high hydrostatic argon pressure. The resulting highly dense material is investigated by X-ray diffraction, optical and electron microscopy, resistance measurements and hardness measurements, and shown to be a homogeneous High transition temperature superconductor.
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| 17. |
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| 18. |
- Niska, John, et al.
(författare)
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Hot isostatic pressing of high temperature superconducting ceramics
- 1994
-
Ingår i: Materials technology (New York, N.Y.). - : Informa UK Limited. - 1066-7857 .- 1753-5557. ; 9:9-10, s. 211-215
-
Tidskriftsartikel (refereegranskat)abstract
- Large specimens of ceramic superconductors are difficult to solid-state sinter to full density, while maintaining superconductivity, without the high temperatures and pressures found in a hot isostatic press (HIP). HIPing can give highly dense, superconducting Bi2Sr2CaCu2O8 (Bi2212) and Bi2Sr2Ca2Cu3O10 (Bi2223) with only slight decomposition. If Y123 is HIPed to full density in a metal capsule, then the nonsuperconducting tetragonal phase forms as a result of decomposition. HIPing of CuO plus YBa2Cu3O7 gives highly dense, superconducting YBa2Cu4O8 (Y124), which is stable at high temperatures and oxygen pressures.
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| 19. |
- Niska, John, et al.
(författare)
-
Investigating Potential Problems and Solutions of Renewable Fuel Use in Steel Reheating Furnaces
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Implementing renewable fuels in steel reheating furnaces can reduce carbon dioxide emissions from fossil fuels, so the steel industry is interested in finding the optimal method of implementation. The relatively low cost of solid biofuels from forest products make them an attractive candidate, but there is a risk of reaction between pellets ash and furnace brick. Therefore a test was conducted with wood pellets ash on a furnace brick to test the sensitivity to pellets ash. One problem is the formation of a glassy phase due to the interaction of furnace refractories with pellets ash. The risk for the formation of a glassy phase depends on the composition of the refractory, composition of the ash and the furnace conditions, for example, a glassy phase was found to form on a chamotte refractory furnace brick when a pellets ash and the brick were heated to 1200°C.One method to analyze the risk for volatile and low melting point compounds from solid biofuels is to use a tertiary phase diagram to divide various components in the ash. Oxides and compounds rich in the alkali metals (Na and K) tend to form volatile compounds. These alkali metal oxides together with silica can give low melting point phases for compositions near the bottom of this diagram. Ash compositions near the top of the diagram which are rich in CaO and MgO tend to have higher melting points. The wood pellets ash investigated was analysed and found to contain a large percentage of Ca, Si and Mg, expressed as CaO (44.4%), SiO2 (14.6%) and MgO (10.1%) and relatively modest amounts of the alkali metals Na and K expressed as Na2O (3.5%) and K2O (6.2%). This mostly stem wood pellets ash could give concern with the formation of a glassy phase, so biofuels with more twigs, leaves and bark with a higher concentration of alkali metals could give even greater concerns. Therefore alternatives like gasification should be considered.Gasification of solid biofuels is one way to avoid ash-forming compounds in reheating furnaces. A survey was performed to evaluate different gasification technologies, as well as existing applications of syngas in other high-temperature industries.
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| 20. |
- Niska, John, et al.
(författare)
-
Retaining oxygen when hiping the YBa2Cu3O7 superconductor
- 1989
-
Ingår i: Hot isostatic pressing. - : ASM International. - 871704137 ; , s. 305-313
-
Konferensbidrag (refereegranskat)abstract
- series of HIP cycles were made on powder samples of the high Tc superconductor YBa2Cu3O7-x in the range of 600 to 1000 C, and pressures of 150 to 200 MPa. The high Tc superconducting orthorhombic phase is difficult to fully densify, because the material easily decomposes and releases oxygen. Two types of encapsulation materials have been used, mild steel and borosilicate glass, of which, glass has a lower oxygen diffusivity and reactivity than steel. Two decomposition regimes were observed. The first regime is from about 600 to 850 C when there is a partial decomposition leading to oxygen backpressure in glass and a transformation of the orthorhombic phase into the tetragonal phase in steel. The second stage of decomposition is above about 900 C, when the superconductor powder in a steel encapsulation decomposes into simpler oxides, and in glass nearly full density results, but without the desired orthorhombic YBa2Cu3O7 structure. Addition of excess CuO has been found to yield the 124 phase (YBa2Cu4O8) superconductor. The 124 phase is the thermodynamically favoured phase at high temperatures and pressures. The 124 phase samples reached nearly full density at the highest temperatures used
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| 21. |
- Niska, John
(författare)
-
The isostatic pressure processing of high Tc superconductors and their properties
- 1993
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The high Tc superconductors are highly anisotropic, ceramic materials which makes it difficult to sinter them at atmospheric pressure to full density. High porosity is detrimental to their mechanical and electrical properties, so the use of isostatic pressures was used to give higher density materials with improved properties. Two general types of isostatic pressing investigated were (1) hot isostatic pressing or HIPing and (2) cold isostatic pressing or CIPing. The HIPing of the YBCO superconductor 123 in a glass encapsulation was shown to retain the oxygen leading to a material which is superconducting without an additional heat treatment, but the 123 phase is unstable in a high oxygen partial pressure, so a partial decomposition occurred at the temperatures required to give a low porosity. A low or high oxygen pressure can be obtained in the HIP depending on the type of encapsulation material used. Maintaining a high oxygen pressure by HIPing in glass makes it possible to quickly form dense samples of the 124 phase from 123 plus CuO by a reaction HIP sintering technique developed. Advantages of this method to form the 124 phase include the high density and short reaction time relative to low pressure synthesis of 124. Disadvantages of this method include the risk of cracking due to thermal expansion mismatch with the glass encapsulation, the presence of unreacted CuO and the lack of grain alignment to improve Jc. The BSCCO 2223 superconductor can be HIPed to nearly full density with good current transport properties without additional heat treatments. The thermal expansion of the 124 phase was measured by low temperature X-ray diffraction, and the 2223 phase by high temperature X-ray diffraction. The c-axis expansion was higher than for the a-axis or b-axis for both materials. A buffer layer of silver plus MgO powder could prevent thermal expansion cracking for HIPing of the 2223 phase superconductor. The mechanical properties are of little interest if the electromagnetic properties are poor, so the final portion of the research is directed toward critical transport current (Ic) in the BSCCO 2223 phase superconductor. The Ic of bars of the 2223 phase superconductor could be raised to the limits of the magnetic self-field (Hs) of the transport current by CIPing without resorting to the more complex HIP process. The Hs limit for the 2223 phase was observed to be about 7000 A/m for our bars with a low oxygen partial pressure final heat treatment. This critical value of Hs appears to be a fundamental limit to the current transport in bulk 2223 materials using the current solid state sintering technique, since it is of the same order of magnitude as for the best bulk 2223 specimens reported in the literature. Determination of the selffield limit provides a very useful method to compare the quality of specimens with different geometries. Finally, it was discovered that an AC transport current can be used to examine flux vortex motion from the DC voltage drop near the normal DC Ic transition in bars of the 2223 superconductor. Two methods of inducing a DC voltage drop for an AC transport current were observed (1) when a DC offset voltage is present in the nominally AC current or (2) when an asymmetric magnetic field is applied to the specimen. The sign of the longitudinal electric field parallel to the current transport can be changed by reversing the direction, or by reversing the asymmetry of the applied magnetic field. The AC Ic transition phenomena provides evidence for the penetration of flux vortices when Hs equals Hc1 for the grains at the surface of the specimen.
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| 22. |
- Niska, John, et al.
(författare)
-
Thermal expansivity of HIP synthesized YBa2Cu4O8
- 1991
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 44:1, s. 93-94
-
Tidskriftsartikel (refereegranskat)abstract
- The thermal expansion coefficient of a sample of the YBa2Cu4O8 phase superconductor was measured using a low temperature X-ray diffractometer. The thermal expansivity was found to be highly anisotropic. The average coefficient of thermal expansion over the temperature range of 150 to 450 K was approximately equal for the a and b axes at 9×10-6/°C, vs a coefficient of about 15×10-6/°C for the c axis. This would indicate that the bonding is weaker along the c-axis than in the ab-plane and that the specific heat of single crystals of the high Tc superconductors can depend on their geometry. The low thermal expansivity in the ab-plane relative to typical metal conductors as copper and silver could lead to compressive stresses in the superconductor when cooling a composite metal-superconductor wire having good alignment of the ab-plane along the wire axis
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| 23. |
- Saffari Pour, Mohsen, 1987-, et al.
(författare)
-
The behavior of impurities during producer gas implementation as alternative fuel in steel reheating furnaces : A CFD and thermochemical study
- 2016
-
Ingår i: ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE). - USA : American Society of Mechanical Engineers (ASME). - 9780791850589
-
Konferensbidrag (refereegranskat)abstract
- The use of available and cheap industrial producer gases as alternative fuels for the steel reheating furnaces is an attractive topic for steel industry. The application of producer gases for such furnaces introduces not only the complicated combustion system of Low Calorific Value (LCV) gases, but also several impurities that could be problematic for the quality of final steel products. The quality of steel can be highly affected by the interaction of impurities with iron-oxides at hot slab surfaces. In this research, the combustion of producer gases and the behavior of impurities at the steel slab surface are studied by aid of a novel coupled computational fluid dynamics (CFD) and thermodynamics approach. The impurities are introduced as mineral ash particles with the particle size distributions of 15-100 νm. The CFD predicted data regarding the accumulation of ash particles are extracted from an interface layer at the flaring gas media around the steel slab surface. Later on, these predicted data are used for the thermo-chemical calculations regarding the formation of sticky solutions and stable phases at the steel slab surface. The results show that the particles are more likely follow the flow due to the high injection velocity of fuel (70 m/s) and the dominant inertial forces. More than 90 percent of particles have been evacuated through the exhaust pipes. The only 10 percent of remaining particles due to the high recirculation zones at the middle of furnace and the impinging effect of front walls tend to stick to the side wall of slab in the heating zone more than the soaking zone.
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| 24. |
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| 25. |
- Sidestam, Patrik, et al.
(författare)
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Modeling of hydrogen diffusion in piled slabs
- 2014
-
Ingår i: Advanced Materials Research. - : Trans Tech Publications. - 9783038350736 ; , s. 2201-2206
-
Konferensbidrag (refereegranskat)abstract
- Hydrogen is harmful in steel which makes it important to reduce the hydrogen content. Piling slabs after casting gives a slow cooling which increases the diffusion out of the steel. Finite element modeling has been used to simulate this process where hydrogen solubility and phase dependent diffusivity can be taken into account. The hydrogen diffusion model is using STEELTEMP® 2D for the thermal analysis. Measurements of temperature and hydrogen content in piled slabs have been done and the calculations are in good agreement. © (2014) Trans Tech Publications, Switzerland.
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| 26. |
- Sidestam, Patrik, et al.
(författare)
-
Modeling of hydrogen diffusion in piled slabs
- 2014
-
Ingår i: Materials Engineering Forum. - : Trans Tech Publications Ltd. - 9783038350736 ; , s. 2201-2206
-
Konferensbidrag (refereegranskat)abstract
- Hydrogen is harmful in steel which makes it important to reduce the hydrogen content. Piling slabs after casting gives a slow cooling which increases the diffusion out of the steel. Finite element modeling has been used to simulate this process where hydrogen solubility and phase dependent diffusivity can be taken into account. The hydrogen diffusion model is using STEELTEMP® 2D for the thermal analysis. Measurements of temperature and hydrogen content in piled slabs have been done and the calculations are in good agreement. © (2014) Trans Tech Publications, Switzerland.
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