Search

Detailed analysis performed on modified 9Cr-1Mo steel in normalised and tempered (N+T) and three different post-weld heat treatment (PWHT) conditions indicated that the work hardening behaviour can be adequately described by Kocks-Mecking approach in the temperature range 300-873 K. The steel in all test conditions exhibited two-stage work hardening behaviour in the variation of instantaneous work hardening rate (θ) with true stress (where θ = dσ/dε, σ is true stress and ε is true plastic strain). The variations of work hardening parameters and θ-σ with temperature exhibited three distinct temperature regimes. The influence of additional PWHTs is discussed in terms of the systematic variations in flow and work hardening parameters due to microstructural softening observed with increasing PWHT temperature in modified 9Cr-1Mo steel. Comparison of work hardening parameters obtained using Voce equation and Kocks-Mecking approach demonstrated an analogy between two approaches for the steel. [ABSTRACT FROM AUTHOR]

True stress-true plastic strain behaviour of 9Cr-1Mo steel in two different product forms, i.e. 20-mm plate and thick section tubeplate forging has been examined in the temperature range 300-873 K in the framework of various flow relationships. The analysis suggested that a combination of Ludwigson and Hollomon equations describes stress-strain behaviour most accurately in both plate and tubeplate forging. Two-stage work hardening has been observed in the variations of instantaneous work hardening rate with stress. The variations in stress-strain, flow parameters and work hardening rate as a function of stress with respect to temperature exhibited three distinct temperature regimes. Signatures of dynamic strain ageing at intermediate temperatures and dominance of dynamic recovery at high temperatures have been observed. The differences in tensile flow and work hardening behaviour obtained between plate and tubeplate forging has been attributed to the affects associated with the initial microstructures obtained for the two product forms in 9Cr-1Mo steel. [ABSTRACT FROM AUTHOR]

We present the simulation studies carried on separation of the N2−O2mixture with the original and modified duplex PSA. The purities of products were in excess of 99 mol %with the modified duplex PSA, whereas the original duplex PSA yielded product purities of 72 mol %.For both product purities of 95 mol %, the bed size and energy requirements with the modified duplex PSA were less by 10 and 2.5 times respectively compared to the conventional PSA and were less by an order of magnitude compared to those with original duplex PSA. [ABSTRACT FROM AUTHOR]

A modified duplex PSA has been proposed, which could yield sharp separation and has the potential for process intensification. The performances for the original and the modified duplex PSA have been evaluated for two types of systems: the CO2−N2−13X zeolite with single component adsorption and the N2−O2−5A zeolite with competing adsorption. Part 1 of the companion papers presents the simulation studies on the separation of the CO2−N2mixture. The purities of both products were in excess of 99 mol % with the modified duplex PSA against 78 mol % CO2and 95 mol % N2with the original duplex PSA for the same conditions. The bed sizes and energy requirements for the modified duplex PSA were one-half of those for the original duplex PSA. Part 2 presents studies on the separation of the N2−O2mixture. [ABSTRACT FROM AUTHOR]

HiGee technology is emerging as an alternative to conventional tray and packed towers for mass-transfer applications. To evaluate the process intensification (volume reduction) potential of the technology, a systematic design procedure is developed in this work. HiGee designs using split packing innovation of Chandra et al. [Ind. Eng. Chem. Res.2005, 44, 4051−4060] are developed for four industrially relevant distillation and absorption systems. Comparison with conventional packed or tray tower designs shows that significant volume reduction is possible. For the systems studied, the process intensification achieved is particularly impressive when the gas side mass-transfer resistance is dominant. The results suggest that split packing design innovation may be particularly suitable for intensification of gas side mass-transfer resistance controlled processes. [ABSTRACT FROM AUTHOR]