Kinetic modelling of coking coal fluidity development

Coal plasticity is a phenomenon directly affecting the creation of coke structure. It is very much a time- and temperature-dependent transformation of the coal matrix, which allows changing the physical phase from solid to liquid-like and again into solid of different properties. The coking process, particularly in a plasticization temperature range, can be considered as a non-isothermal reaction at a constant heating rate. In this work, a macro-kinetics approach is applied that results in effective kinetic parameters, i.e. pre-exponential factor and activation energy. It is postulated in this work that the original content of metaplast (M0) is a part of volatile matter that melts under the effect of temperature. The coal sample can melt steadily with the temperature increase, achieving the maximum fluidity (Fmax) when the total amount of metaplast available turns into the plastic state. Coal behaviour while it is being heated can be described by two mechanisms. Under first one, the coal turns into plastic phase starting at t1 and ending at tmax, where solidification starts. This can be considered as independent reactions model. In the second model, both plasticization and solidification reactions compete over entire range of phenomena. This can be considered as reactions in the series model. The developed models were validated against experimental data of coal fluidity delivering kinetic parameters.

P84 Co-Polyimide-based Tubular Carbon Membrane: Effect of Pyrolysis Temperature

In this study, the effect of carbonization temperature on the performance of carbon membrane was being investigated. P84 co-polyimide-based tubular carbon membrane were fabricated through the dip-coating technique. The prepared membranes were characterized by using the thermogravimetric analysis and scanning electron microscopy. CO2, N2, and CH4 pure gas were utilized in determination of the carbon membrane’s permeation attributes. In order to enhance the membrane’s performance, carbonization process was performed in Ar environment; with the flow rate of 200 ml/min. The carbonization process was done at various temperature, namely 600 oC, 700 oC, 800 oC and 900 oC in a constant heating rate of 3 oC/min. The increased in the temperature of carbonization leads to the production of small pores size carbon membrane. Carbon membrane prepared at 800 oC showed the highest CO2/CH4 and CO2/N2 selectivity of 63.2±5.2 and 61.3±1.7, respectively.

Cracking and Failure in a High Strength Low Alloy Steel during Solidification

The present study focuses on characterizing cracks and fracture that appeared during solidification in the segregated zones of the as-cast structure of a large size ingot made of high strength low alloy steel. Solidification experiment was conducted, using Gleeble® 3800 thermo-mechanical simulator, on samples taken from the ingot/hot top interface of a 40 MT (Metric Ton) ingot. The thermal cycle consisted in heating from ambient temperature to 1385 °C with a constant heating rate of 2 °C/s followed by a free cooling. Optical and scanning electronic microscopies were used to analyze and quantify the cracked regions. Microstructural observations revealed that shrinkage during rapid solidification of melted grain boundaries ultimately led to the initiation and propagation of cracks.