Long-term strength of coke-furnace heating walls

A hierarchical model of material with a minimum number of implicit parameters has previously been proposed. This model permits calculation of the long-term strength of the heating walls in coke furnaces, as well as assessment of their condition. As an example, three long-term strength curves are presented for Dinas brick at 1273, 1323, and 1373 K. These curves are based on the equation of state and the kinetic equations containing the minimum number of implicit parameters.     

Reducing spatial dimensionality in a model of moisture diffusion in a solid material

A model of the moisture movement in solid wood under isothermal conditions taking into consideration coating (insulation) of the surface of the material, is presented in a 2-D-in-space formulation. The validity of using a corresponding 1-D model on a 2-D problem is investigated. A measure of reliability of the 1-D model is introduced. This paper presents a new technique, which adjusts the width of a material as well as the degree of coating of the edges, to ensure the relative error of the problem solution is less than the required, resulting from reducing the model from 2-D to 1-D-in-space. This technique is based on the computer simulation of 2-D diffusion to estimate the reliability of the corresponding 1-D diffusion model.     

Urinary fistulas: vaginal repair using a labial fat pad

A technique is recommended to repair urinary fistulas vaginally using a pedicle of labial fat to separate the urothelial and vaginal layers. The technique was used in 6 patients with vesicovaginal and 4 patients with urethrovaginal fistulas. Anatomic results were successful in all cases and stress incontinence was cured in all patients who had this coexistent condition.     

Fast removal of Pb(II) and Cu(II) from contaminated water by groundwater treatment waste: impact of sorbent composition

ABSTRACT

A non-hazardous groundwater treatment waste (GWTW) was examined as a low-cost sorbent for Pb(II) and Cu(II) ions. The content of the dominant elements in GWTW was as follows: 78% Fe₂O₃, 7.4% P₂O₅, 7.4% CaO and 5.2% SiO₂. The removal of Pb(II) and Cu(II) was fast, and more than 67–95% of ions were accumulated by GWTW during the first 3 min. The sorption capacity of GWTW depends on solution pH, concentration and temperature. Equilibrium data fitted well with Langmuir–Freundlich and Langmuir-partition models. The inherently formed nano-adsorbent could be utilized for the treatment of water contaminated with Pb(II) and Cu(II) ions.     

Deformation of coke-furnace heating walls under the action of nonsteady forces and temperatures

The hierarchical model of Dinas ceramic based on defining relations with a minimum of implicit parameters permits assessment of the viability of Dinas structures and prediction of the creep and long-term strength of the heating walls in coke furnaces. However, prediction of the cyclic creep is also required, on account of the cyclic variation in the heating-wall temperature and the load (the coking pressure). The prediction of the creep curves at hazardous points of the heating walls is considered, in the light of the simultaneous variation in stress and temperature during coke-battery operation.     

Effect of Mo content on electrochemical behaviour of TiMo alloys for dental applications

Corrosion behaviour of the new TiMo alloys together with the currently used metallic biomaterials commercial pure titanium (Cp‐Ti) was investigated for dental applications. Ingots of composition Ti12Mo, Ti20Mo and Ti40Mo were synthesized by the cold crucible levitation melting (CCLM) technique. All the samples were examined using electrochemical techniques: open circuit potential, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in two electrochemical media: artificial saliva and in commercial mouthwash solution with 450 ppm F^? (Astera^©, EU), at 25 °C. The passive behaviour for all the Ti samples is observed for artificial saliva and for commercial mouthwash solution. The results suggest a non‐predominant fluoride effect on the passive behaviours of titanium samples. The EIS technique was applied to study the nature of the passive film formed on all the samples at various potentials in artificial saliva and in commercial mouthwash solution. Equivalent circuits (EC) were used to modelling EIS data, in order to characterize samples surface and better understanding the effect of Mo addition on the Cp‐Ti. The TiMo alloys, with a dendritic arrangement, appear to possess superior corrosion resistance than the Cp‐Ti in both electrochemical media.     

Assessing the stability of Dinas properties by means of creep-test data for samples from the heating-wall lining in coke furnaces

Short-term creep data at 1300°C for Dinas samples cut from the brick lining of the heating walls in coke furnaces after prolonged operation (up to 31 years) indicates that, on the basis of generalized creep diagrams, the primary creep curves ? ^cr (t) may be described by a power law: ? ^cr = ct ^α. The generalized creep diagrams are also described by a power law $ \varepsilon ^{cr} = \left( {\tfrac{1} {{\alpha \eta A}}} \right)^\alpha (\sigma ^2 t)^\alpha $ with the same exponent α. Values of α—the slope of the generalized creep diagram—are measured at different times: it increases from 0.314 before operation to 0.334 after prolonged service. The increase in α indicates restructuring of the material, accompanied by decrease in the remaining life of the refractory.