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Continuous research on the clean and effective use of coal is still necessary as coal will continue to play a key role in global energy supply for the foreseeable future. Hence, in the current study, the optimisation of in-furnace coal blending for one of Malaysia's opposed-firing utility boilers was numerically executed on the basis of hydrodynamics and combustion characteristics. The predicted FEGT from the numerical model was validated against the actual FEGT from the coal-fired power plant, revealing a difference of less than 10 %. Four (4) coal blended cases were tested, which included both bituminous (bit) and sub-bituminous (sub-bit) coals. The findings demonstrate that due to the difference in density between bit and sub-bit coals, the hydrodynamic performance is predicted to significantly improve when sub-bit coal is injected at the bottom burner as opposed to the upper burner. In terms of kinetics, the higher volatile matter (VM) of sub-bit coal in contrast to bit coal has been postulated to release a substantial amount of volatiles and improve the combustibility of bit coal. Furthermore, enhanced oxygen release from sub-bit coal volatiles can aggravate the gas-solid heterogeneous reaction during bit coal char combustion. As a result of the bottom burner's high temperature, it has been discovered that introducing sub-bit coals into those burners speeds up VM release and char combustion, which increases the rate of combustion. Thus, when combustibility rises, the peak temperature position moves downward, reducing the likelihood of delayed combustion and, consequently, the risk of heat exchanger pendant failure and ash deposition. In a furnace with a relatively long coal residence time, a considerable fraction (>20 %) of high gross calorific value (GCV) sub-bit coal (>5800 kcal/kg) is predicted to produce two peak flame temperatures exceeding 1600°C owing to the likelihood of enhanced char which created delayed combustion. Therefore, a furnace condition with a comparatively shorter coal residence time may aid in the rapid evacuation of residual char from the combustion/burner zone and minimise the potential for delayed combustion. Nonetheless, residual char escape may exacerbate the emission problem by releasing considerable unburned carbon. Overall, the current numerical model has the potential to be a reliable and cost-effective tool for investigating the combustion characteristics of coal blends in a power plant boiler.

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The combustion of coals will result in significant ash-related issues, which will ultimately lead to the efficiency loss of coal-fired utility boilers. While there have been numerous attempts to predict ash deposition dynamics using numerical approaches, the majority of these models were constructed using experimental data from pilot-scale furnaces and without integration with combustion models. Therefore, the current study collects meaningful power plant data from ash sampling activities at one of Malaysia's 700 MW sub-critical coal-fired power plants, enabling the ash deposition behavior in a real coal-fired utility boiler to be adequately captured and converted into a reliable ash deposition numerical model. The validation feedback loop of the ash deposition model was run using in-situ measurement data (ash sampling picture) and the actual power plant operating conditions during the ash sampling activities. The image processing algorithm was used to determine the degree of similarity between the actual ash sampling image and the predicted ash deposition image from the numerical model. Prior to the validation feedback loop, the overall numerical model (solver, combustion, turbulence, radiation) was successfully validated with the FEGT from the actual power plant, revealing a difference of less than 5 %. The current study found that the baseline ash deposition model (created from experimental data) underestimates the quantity of ash deposition gathered. The validation feedback loop of the baseline ash deposition model successfully established a new set of impaction efficiency constants, which increased the similarity of the images between the actual and predicted ash depositions. The current study's drawback, however, is mostly in the validation basis, which is largely qualitative in nature. Although the Structural Similarity Index (SSIM) value is useful for comparing the similarity of images between actual and predicted ash depositions, a more quantitative measurement that can provide extra meaningful data points and higher accuracy on the deposited ash is preferable. However, based on this modified version of the ash deposition model, the agreement is found to be satisfactory in terms of gaining a rudimentary insight of the ash deposition behavior in a coal-fired boiler.

A first comprehensive noise exposure survey was conducted in 1987 by Esso Production Malaysia Incorporated (EPMI). Since then noise surveys are routinely conducted in EPMI's operations, both on-shore and offshore. The noise exposure guidelines EPMI has adopted are based on the Malaysian noise exposure regulations which are similar to United State's 0SHA Noise Regulations. Even though the regulations are not applicable offshore, EPMI has utilized the standards as guidelines for its offshore operations, as we believe such guidelines provide for personnel hearing protection. This paper discusses the noise surveys in EPMI operations conducted at the onshore terminal, production platforms, and drilling rigs (during exploration and development drilling). The equipment used, methodology, criteria and strategies adopted for noise surveys are described. The results and findings of the surveys conducted, such as personnel dosimetry, noise sources, area noise levels, noise characteristics, and noise control recommtendations, are presented.

Detonation potential in rotating detonation engine (RDE) depends on well-mixed fuel and oxidizer in the annulus. A numerical study was carried out to analyze hydrogen (H 2 ) -oxygen (O 2 ) mixing in RDE prior to the detonation. A validation was effectively achieved by comparing the expected detonation criteria with the reported experimental results where less than 10 % error was observed. Non-reacting flow inside the annulus was examined with a new parameter describing the fuel uniformity, the amplitude of the maximum deviation from the H 2 average mass fraction, | |. The numerical results are generated at variable distance between the fuel injector and the oxidizer plenum, D to provide insights on the fuel uniformity and the mixing efficiency. Case A3 with D = 6 mm results in the worst mixing indicated by the highest | | of 0.0156. This happened due to the impingement of fuel stream that separates the stream into two distinctive flows and formed two major vortices that separates the fuel streams. Case A1 with D = 2 mm results in the best mixing indicated by the lowest | | of 0.0012 due to the cross flow collisions of fuel and oxidizer and large turbulent region created. The location of fuel inlet situated face to face with the 90° elbow wall has been predicted to generate the most significant fuel distribution imbalance within the annulus. In conclusion, prediction towards excessive fuel inhomogeneity in the annulus as one of the major factors affecting stability of detonation wave for RDE is achieved in this study.

A rotating supersonic combustion engine (RSCE) is tested with various initiator tube positions along the combustion chamber to determine its impact on the ignition process. The type of fuel used is methane with oxygen as the oxidizer. The initiation of RSCE is assessed for nearstoichiometric methane-oxygen mixture to slightly rich mixture. Successful initiation of rotating supersonic combustion in the RSCE was obtained when the position of the initiator tube is located higher end of the combustion chamber that indicates a proper mixing of reactants. The mixing of reactants improves further up the annulus chamber of the RSCE.

The fluctuating quality of natural gas (NG) in Peninsular Malaysia (PM) makes it challenging for the gas turbine (GT) combustor to meet the combustion performance requirements from the Original Equipment Manufacturer (OEM). Moreover, the gas quality sensitivity is more apparent in modern dry low NOx (DLN) combustors. Many of the prior combustion investigations were conducted on a modest scale in the laboratory. In actuality, combustion characterizations in complicated DLN combustors are more valuable to the power generation sector. Hence, the current numerical analysis utilized the RANS formulation and a detailed chemistry to examine the impact of ethane (C2H6), carbon dioxide (CO2), and nitrogen (N2) proportions in NG on combustion characteristics in a multi-nozzle DLN (MN-DLN) combustor, with the support of Modified Wobbe Index (MWI) calculations. Validations were performed using the combustor outlet temperature (COT) from the power plant where the actual MN-DLN combustor is operated, which revealed less than 10 % discrepancy. Qualitative validations were carried out by comparing the burn trace from the actual combustor wall to the predicted results, revealing an adequate Structural Similarity Index (SSIM) of 0.43. From numerical results of flame fronts and COTs, the addition of 20 % diluents (CO2 and N2) to NG demonstrated the blowoff risk. When MWIs of Kerteh and the JDA (major NG resources) were used as baselines, MWI ranges of all NG compositions under study surpassed the OEM’s ± 5 % limit. The increase in CO2 proportion results in a wide MWI range, especially when Kerteh is used as the baseline. Therefore, any GTs in PM that have previously been calibrated to use Kerteh's NG are more likely to have combustion instabilities if CO2 levels in NG suddenly increase. The higher MWI range backs up the current numerical results that showed the deleterious effects of a high CO2 composition throughout the combustor firing process. However, increasing the amount of C2H6 by up to 20 % is predicted to have minor effects on combustion characteristics. Overall, the validated numerical model of the MN-DLN combustor provided critical information about combustion characteristics and multifuel capabilities in respect to the NG quality in PM.