Aerodynamics of a swirling fluidized bed

Swirling Fluidized Bed (SFB) is one of the fluidized bed systems that have potential to be widely used in the mineral processing, power generation and chemical industries. By using an annular bed and inclined injection of gas through the distributor in SFB it will archive a high performance in fluidization. A numerical simulation Computational Fluid Dynamics (CFD) and experimental work with Particle Image Velocimetry (PIV) has been used to investigate physical parameters that influence the type of plenum chamber, the distributor pressure drop and the uniformity of tangential velocity distribution. The study focused on the 60 blades distributor whereby the effect of two horizontal inclinations (12° and 15°) and tangential entry plenum chamber (single, double and triple). Three velocities component were analyzed; tangential velocity, radial velocity and axial velocity. In actual industrial applications, the axial velocity will create fluidization while the tangential velocity provides swirling effect. The presence of radial velocity can be explained as a consequence of centrifugal force generated by the swirling gas. The tangential velocity is the major velocity component in this study and it represents the velocity of the swirling air in the annular region of the bed. The uniformity of tangential velocity distribution and pressure drop is set as performance criteria and has been analyzed with statistical method; mean value, standard deviation & root mean square of difference (RMSD). The most significant finding in simulation configuration is the pressure drop of the distributor blade increased when a triple tangential entry plenum chamber along with horizontal inclination 15° has been applied which then create high tangential velocity. Only parameter for double tangential entry plenum chamber consists with horizontal inclination, 12° has been selected to validate with the PIV result. Comparison of the simulation result (CFD) and experimental data (PIV) are presented, and it is confirmed that good agreement is obtained

Factors influencing project delay: a case study of the vale malaysia minerals project (VMMP)

Delays are one of the biggest problems faced by the construction industry. Delays in construction projects have significant financial and social impact to parties involved in the projects. The main objective of this study is to explore the causes of delay in the Vale Malaysia Minerals Project (VMMP) in Lumut, Perak. This study was conducted by using a qualitative approach. A series of face to face interviews were conducted with an expert from the construction organization and VMMP staff. Responses were analysed qualitatively using content analysis. The results revealed that several factors contribute to the delay in VMMP completion, i.e. poor communication, delays in material delivery, and poor management on site, etc. Time and cost overrun were the effect of delays in the construction project. The findings of this study will help project managers and/ or the client to take necessary actions and to use of supply chain management techniques to avoid further delays in future project completion on construction project

Nitrification/denitrification in a submerged anaerobic membrane bioreactor (SAMBR) for nitrogen removal

Due to serious drawbacks in the conventional nitrification-denitrification process for nitrogen removal from wastewaters, such as high energy and carbon inputs and significantly increased sludge production, the more efficient and cost-effective Anammox process is starting to be used more widely. Anammox is an anaerobic biological process where around equimolar amounts of NH4+ and NO2- are oxidised/reduced, respectively, to produce dinitrogen gas without using a carbon donor. In the first part of this study, the start-up and performance of the Anammox process were evaluated in a 3-litre submerged anaerobic membrane bioreactor (SAMBR). The start-up using seed culture from an anaerobic digester (Anglian Water, UK) was relatively quick (60 and 70 d) for SAMBR 1 (HRT = 2d) and SAMBR 2 (HRT = 4d), respectively, compared to other reports in the literature. Both reactors showed quite high NH4+ and NO2- removal efficiencies of over 80% and 65%, respectively, resulting in a molar ratio of NH4+ to NO2- consumption of 1:0.9, which was comparable to recently reported values in the literature which are lower than the originally cited ratio of 1:1.32. Despite different HRTs, there were no significant differences in performance between the reactors. The use of a flat sheet membrane panel (~0.4 m pore size-Kubota, UK) was shown to be capable of shortening the start-up period for Anammox compared to continuous flow through reactors such as conventional CSTRs. The second major part of this work examined the novel process of partial pre-oxidation of NH4+ using nanofiltration (NF) hollow fiber membrane modules, to provide a feasible alternative to conventional partial nitrification preceding the Anammox process. Prior to investigating the feasibility of this process, ammonium oxidising bacteria (AOB) were enriched from both activated sludge and full-scale SAMBR sludge, in batch reactors, in order to determine whether it was possible to use anaerobic sludge as a source of nitrifiers. The enriched AOB demonstrated stable and high nitrifying activity throughout the enrichment period of 200-300 days, with average NH4+ removal efficiencies of over 90%. In the pre-oxidation process, AOB in the shell-side of the membrane unit was shown to be capable of oxidising the NH4+ mainly to NO2- which then diffused back into the tube side, resulting in a mixture of NH4+ and NO2- in the exit stream from the membrane unit. It was found that only flow rates of above 3.0 L/h were feasible, with a maximum NH4+ flux in the range of 8 – 10 g/m2 h. After 48 hours of operation, and at a flow rate of 5.0 L/h, an approximately equimolar ratio of NH4+ to NO2- was observed in the exit stream, and this would meet the requirement for the Anammox process as suggested by previous reports. This study has demonstrated the potential benefits of applying the Anammox process in a SAMBR for the treatment of nitrogen-containing wastewater as it could reduce the process start-up period, and the operation can be carried out at a short HRT. The application of a membrane process for the pre-oxidation of NH4+ was found to be reasonably promising at a laboratory-scale, and practically viable at a scale similar to actual SHARON reactor (Whitlingham STC, UK) based on an estimation of the number of HF modules needed. However, a proper optimisation study of the process is strongly recommended so that its feasibility could be further examined at a larger scale linking both processes together.Open Acces

Perkembangan dan Cabaran Institusi Pengajian Tinggi di Malaysia: Suatu Pemerhatian Awal

Pendidikan adalah proses di mana ia mengembangkan kemampuan dan sikap manusia. Pendidikan pengajian tinggi mula diperluaskan setelah Perang Dunia Ke-2 kerana kesedaran politik yang semakin meningkat mengenai kepentingannya untuk prospek masa hadapan negara. Kajian ini memfokuskan bagaimana pendidikan pengajian tinggi memberi kesan kepada graduan Malaysia dengan mengkaji perkembangan sistem dari selepas merdeka sehingga sekarang dan bahkan kajian ini juga memfokuskan sehingga tahun 2025. Pendekatan kualitatif digunakan, berdasarkan kebanyakan buku, jurnal dah artikel yang layak. Artikel ini juga bertujuan mengenal pasti bagaimana sistem pendidikan pengajian tinggi di Malaysia memastikan para graduan mendapat pekerjaan pada masa hadapan