Mohd. Kamaruddin Abd. Hamid

Evaluation of hydrodynamic behavior of the perforated gas distributor of industrial gas phase polymerization reactor using CFD-PBM coupled model

Abstract A 2D computational fluid dynamics (Eulerian–Eulerian) multiphase flow model coupled with a population balance model (CFD-PBM) was implemented to investigate the fluidization structure in terms of entrance region in an industrial-scale gas phase fluidized bed reactor. The simulation results were compared with the industrial data, and good agreement was observed. Two cases including perforated distributor and complete sparger were applied to examine the flow structure through the bed. The parametric sensitivity analysis of time step, number of node, drag coefficient, and specularity coefficient was carried out. It was found that the results were more sensitive to the drag model. The results showed that the entrance configuration has significant effect on the flow structure. While the dead zones are created in both corners of the distributors, the perforated distributor generates more startup bubbles, heterogeneous flow field, and better gas–solid interaction above the entrance region due to jet formation.

Hydrocarbon Mixture Fractionation Direct Sequence Retrofitting and Feed Condition Sensitivity Analysis

The objective of this paper is to present the retrofit analysis for the hydrocarbon mixture (HM) direct sequence fractionation process and to analyse the process sensitivity with respect to feed conditions. To perform the study and analysis, the energy efficient HM separation process methodology has been developed. The methodology consists of four hierarchical steps. In the Step 1, a simple and reliable short-cut method of process simulator (Aspen HYSYS) is used to simulate a direct HM sequence. The energy used to recover individual fractions in the base sequence is analysed and taken as a reference. In the Step 2, an optimal HM sequence is determined using driving force method. All individual driving force curves for all adjacent components are plotted and the optimal sequence is determined based on the plotted driving force curves. Once the optimal HM sequence has been determined, the new optimal sequence is then simulated in Step 3 using a simple and reliable short-cut method (using Aspen HYSYS), where the process sensitivity and energy used in the optimal HM sequence are analysed, the process sensitivity of optimal HM sequence is compared with the other three different sequences by changing their feed conditions. Better sensitivity sequence was achieved when compared optimal sequence with the other three sequences in Step 4, the sequence determined by the driving force method has better sensitivity compared to the three other sequences as well as less energy requirement. All of these findings show that the methodology is able to design better sensitivity and minimum energy distillation column sequence for HM fractionation process in an easy, practical and systematic manner.

The Effect of Catalyst Loading (ni-ce/al2o3) on Coconut Copra Pyrolysis via Thermogravimetric Analyzer

The aim of this study is to investigate the influence of catalyst weight loading on pyrolysis of coconut copra via thermogravimetric analyser (TGA). The pyrolysis process is conducted up to 700 °C at a heating rate of 10 °C/min in nitrogen (N2) atmosphere flowing at 150 mL/min. The catalyst was successfully prepared via wet impregnation method, with alumina (Al2O3) used as support, while cerium (Ce) and nickel (Ni) act as promoter. The feedstock samples for TGA were prepared accordingly with biomass to catalyst weight loading ratio as follows: CC-1 (1 : 0.05), CC-2 (1 : 0.10), CC-3 (1 : 0.15), CC-4 (1 : 0.20), CC-5 (1 : 0.50), and CC-6 (1 : 1). For comparison, the pyrolysis of coconut copra without catalyst is also determined at the same operating condition and labelled as CC-7 (1 : 0). The TGA-DTG curves shows that, the presences of catalyst significantly affect the degradation rate of volatile matter than lignin degradation. In this study, the CC-3 sample has achieved high mass loss at 83.27 % and also high degradation rate at 0.0107 mg/s. For lignin decomposition, it shows that, CC-1 to CC-6 samples has achieved lignin mass loss percentage below 12.7 %. The non-catalytic sample (CC-7) has exhibited 80.33 % of volatile matter of mass loss and 13.92 % of lignin mass loss. The optimum catalyst loading was observed at 1 : 0.15 (CC-3) that work best to degrade volatile matter at highest mass loss, in which attributes to higher yield of pyrolysis oil.

On the computational fluid dynamics of PEM fuel cells (PEMFCs): an investigation on mesh independence analysis

Mesh independence analysis is one of the most crucial steps in any CFD problem. The aim of this study was to investigate the most commonly used variables employed for grid independency studies in a typical PEMFC and to find possibly the most effective variables that may be decisive in a PEMFC grid independence test. Herein, a three-dimensional (3-D), steady state, non-isothermal computational fluid dynamics (CFD) model of a serpentine channel proton exchange membrane fuel cell (PEMFC) was developed. The present model includes various conservation equations that are dominant in a typical PEMFC: the mass, momentum, species, charge, and energy equations, which are coupled with the electrochemical model. The numerical results indicate that much more care should be taken while obtaining a mesh independence solution for CFD studies in PEMFC systems. Based on our findings in this study, it was demonstrated that employment of merely the polarization curve (current–voltage), especially only in a given specific point, was not sufficient to carry out the mesh independence tests for CFD studies in PEMFCs. In addition, it was observed that the average volumetric hydrogen concentration inside the catalyst layer on the anode side has a more significant role to check the grid independency tests.

Product sampling time and process residence time prediction of palm oil refining process

The quality of product produced in palm oil industries is important due to customer need and world demand. It is crucial to monitor and predict the quality of Refine Bleached Deodorised Palm Oil (RBDPO) produced. One of the most significant driving forces behind the demand for quality prediction of RBDPO is the reducing production cost of RBDPO. Palm oil had the highest manufacturing cost in that scenario, mainly because of the higher demand for ethanol in the pre-treatment step. The development of rapid and non-destructive measuring technique is needed to enhance the efficiency of palm oil quality monitoring. Today in the Lahad Datu Edible Oil Sdn. Bhd. (LDEO) company, the cost production of RBDPO is much higher and can be double or triple than the usual cost production due to the need of recycle process for getting the desired quality of RBDPO. The current production of RBDPO takes a lot of time. This show how important the quality predict of RBDPO in meeting the needs of the LDEO Company to reduce the need of recycle process due to the cost production and time consuming. This study aims to develop a statistical analysis that can predict the sampling time and residence time for the whole refinery process using autocorrelation and cross-correlation in MATLAB. The data analysis of Crude Palm Oil (CPO) and RBDPO is based on five parameters, percentage of the free fatty acids (% FFA), the percentage of the moisture, the deterioration of bleachability index (DOBI), iodine value (IV) and peroxide value (PV), which are used to monitor the RBDPO quality provided by the LDEO Company. For the 65 sample size data, the sampling time and residence of the whole refinery process are 2 h and 2.4 h. Both data are required in developing a tool to predict the RBDPO quality.

Energy efficiency improvement in the natural gas liquids fractionation unit

The objective of this paper is to present the study and analysis of the energy efficiency for the natural gas liquids (NGLs) fractionation sequence by using driving force method. To perform the studies and analysis, the energy efficient NGLs fractionation plant methodology is developed. Hence, the methodology consists of four hierarchical steps; Step 1: Existing Sequence Energy Analysis, Step 2: Optimal Sequence Determination, Step 3: Optimal Sequence Energy Analysis and Step 4: Energy Comparison. The capability of this methodology is tested in designing an optimal energy efficient distillation columns sequence of NGLs fractionation unit. By using the driving force method, maximum of 21 % energy reduction is able to be achieved by changing the sequence of NGLs fractionation unit. It can be concluded that, the sequence determined by the driving force method is able to reduce energy used for NGLs fractionation. These findings show that the methodology is able to design energy efficient distillation columns for NGLs fractionation sequence in an easy, practical and systematic manner.

Design and Fabrication of Bench-Scale Flash Pyrolysis Reactor for Bio-Fuel Production

The purpose of this paper is to present the construction and testing of a bench-scale flash pyrolysis reactor for bio fuel production from local biomasses such as empty fruit bunches (EFB) and rice husk. The reactor is intended for a mobile application where it can be brought into the fields. The design is based on ablative reactor technology so that larger feed size can be processed. The moving rotor is equipped with helical strips to create optimum centrifugal and mechanical force inside the system. In order to provide a sustainable heat source, the resulting syngas is burned and recycled back into the reactor. This reactor will operate with reactor temperature ranges from 450 to 600 °C, 300 - 1,000 °C/s heating rates and 5 - 20 g/min biomass processing capacity. This study can provide an important basis in designing a mobile fast pyrolysis reactor for Malaysia’s biomass which in general consists of higher cellulose content

Methodology Development of a Flexible and Operable Energy Integrated Distillation Columns

This paper presents the development of a new methodology that will enable to design flexible and operable energy integrated distillation columns (EIDCs). Distillation is the primary separation process used in the industrial chemical processing. Although it has many advantages, however the main drawback concerns with the large energy requirement, which significantly influence overall plant profitability. The large energy requirement of these processes can be reduced by using energy integration. Therefore, a new methodology that will enable to design flexible and operable of EIDCs has been proposed in this study. This can be successfully obtained by implementing the integration of process design and control (IPDC) methodology. The design of EIDCs can be further improved to ensure that the design is more cost efficient, flexible, controllable, and operable. This can be achieved by developing a new model-based IPDC method, which includes cost optimality and controllability at the early design stage, which is also the main objective of this study. It is expected that this new methodology will help engineers to solve EIDCs design problem in a systematic and efficient manner. Methodology Development

A simple case study on application in synthesising a feasible heat exchanger network

kamaruddin@cheme.utm.my Heat exchanger network (HEN) is very important to optimise energy usage in process industry. Heat exchanger network synthesis is an important process synthesis problem where different tools and methods have been presented to solve this synthesis problem. In HEN synthesis, the feasibility of the HEN design is not taken into consideration. The HEN design may not be able to be implemented in industrial applications. It is essential to check the feasibility of a design before it is being implemented in the industry. The objective of this paper is to present the application of a new flexible and operable heat exchanger network (FNO HEN) methodology in synthesising a feasible HEN using a simple case study. The novelty of this work is to determine an optimal ΔTmin value that gives minimum external energy requirement (EER) and heat exchanger area (HEA) as well as simultaneously analyse the feasibility of the HEN design in an easy, systematic and efficient manner. Using the new developed FNO HEN methodology framework, HEN design target, which is the value of ΔTmin is determined to obtain the feasible HEN design. From process design point of view, ΔTmin value determines the size of heat exchanger in the network as well as energy saving. A process simulator is used to check the process feasibility of the HEN designs. With the use of the feasible HEN trade-off plot, which is a plot of EER and HEA at different value of ΔTmin with additional of feasibility area, the optimal feasible HEN design which satisfies external energy requirement (operability), heat exchanger area (capital) and process feasibility has been successfully determined.

Sensitivity analysis of industrial heat exchanger network design

The problem of interaction between economic design and controller design of heat exchanger network (HEN) is addressed in this work. The feasibility and sensitivity issues are incorporated in the classical design of HEN. HENs in industry seem to be very efficiently operated. The network that may have operated efficiently perhaps is the one that is not fully optimised in term of flexibility and sensitivity. It is important to do synthesis and sensitivity analyses of the designed network. The objective of this paper is to investigate and compare the sensitivity criteria of the originally designed HEN of the fatty acid fractionation process (FAFP) and the new HEN design. In this study, the HEN designs are already fixed at the value of ?Tmin = 40 °C. A new suggested HEN is redesigned from the original HEN of FAFP plant by obeying Pinch Analysis (PA) rules. The new HEN was redesigned by applying the PA stream splitting compared to the original HEN (that has been used in the industry), in which the design is not have stream splitting. The aim of this work is to determine the best optimised design whether the one that not followed Pinch Analysis rules or the other one. Using the new developed FNO HEN methodology framework, sensitivity analysis was applied which consists of two tests: 1) Flexibility Analysis and 2) Sensitivity Analysis. According to the results, the best candidate that satisfies the sensitivity and economy criteria is the new HEN design. It can be concluded that it is important to do stream splitting in order to obtain not only the best HEN in terms of design and economy criteria, but also in the matter of sensitivity criteria.