Olagoke Oladokun

Non-isothermal kinetic analysis of oil palm empty fruit bunch pellets by thermogravimetric analysis

The pyrolysis kinetics of oil palm empty fruit bunch (OPEFB) pellets was examined under non-isothermal conditions in a thermogravimetric (TG) analyser. Thermal analysis was carried out from 30 °C to 1,000 °C using three different heating rates 5, 10, 20 °C min -1 under nitrogen gas (N2). The TG-DTG curves showed that the pyrolysis process occurred in three steps; drying, active pyrolysis and passive pyrolysis signifying the removal of moisture, holocellulose and lignin. The pyrolysis kinetic parameters; activation energy, Ea, and frequency factor A, were deduced from the Flynn-Wall-Ozawa (FWO) model. The average Ea and A values from α = 0.10 0.60 were 160.20 kJ/mol and 1.38 x 10 24 min -1 . The highest Ea (231.42 kJ/mol) and A (8.27 x 10 24 min -1 ) occurred at α = 0.30 indicating this is the slowest or rate determining step (RDS) during thermal degradation of OPEFB pellets. The average Ea for OPEFB pellets was comparably lower than cornstalk (206.40 kJ/mol), sawdust (232.60 kJ/mol) and oak (236.20 kJ/mol). The kinetic compensation or isokinetic effect was also observed during thermal decomposition of the OPEFB pellets. Hence, the results indicate OPEFB pellets can be utilized as a potential feedstock for pyrolysis.

Modelling multicomponent devolatilization kinetics of imperata cylindrica

Biomass devolatilization is an important phenomenon in the thermochemical conversion of biomass into clean fuels through pyrolysis, gasification and combustion. In this paper multicomponent model fitting (MMF) was carried out to analyse the devolatilization kinetics of Imperata cylindrica using non-isothermal thermogravimetry (TG) to determine the pre-exponential factors (k0), activation energies (Ea) and fractional contribution. The TGA of Imperata cylindrica was carried out in the temperature range of 30-1,000 °C at four heating rates of 5, 10, 15, and 20 K/min using Nitrogen at a flow rate of 20 mL/min as purge gas. Evaluation of the kinetic parameters involved the numerical regression of the non-isothermal TGA data in MATLAB 2013a based on the pseudocomponent modelling method. The pseudocomponents number used in the modelling was limited between 3 and 10, and the overall quality of fit (QOF) for eight pseudocomponents was found to be the lowest with the value of 1.89 %. The corresponding average values for pre-exponential factor, activation energy and fractional contribution were 791.63 s -1 , 12.13 kJ/mol and 0.13. The results proved that pseudocomponent reaction modelling method can be successfully employed to accurately predict the experimental devolatilization rates.

Gasification of Empty Fruit Bunch Briquettes in a Fixed Bed Tubular Reactor for Hydrogen Production

The gasification of EFB briquette was investigated in a fixed bed tubular reactor to examine the effects of temperature on gas composition, heating value and cold conversion efficiency.The resultsrevealedthat H2 gas composition increased from 17.17 mol. % to 29.67 mol. % with increasing temperature from 600°C to 700°C at an equivalence ratio (ER) of 0.4. The heating value (HHV) of the producer gas increased from 6.18 MJ/Nm3 to 7.64 MJ/Nm3 and cold gas efficiency increased from 35.19% to 43.50% with increasing temperature during gasification. However, carbon conversion efficiency increased only marginally from 31.85% to 32.84% while a significant quantity of char (~ 21%) was produced per unit mass of EFB briquette. The results indicate that higher temperatures are required to increase the overall efficiency of EFB briquette gasification in a fixed bed tubular reactor.

Physicochemical, Microstructural, Mineralogical and Thermal Properties of Owukpa Coal

Coal currently accounts for over 38% of electric power generation around the globe. Hence, it is a significant critical contributor to socio-economic growth and development, particularly in the BRIC economies. The success of the coal energy in these nations in addition to the discovery of vast new coal deposits have revived Nigeria’s interest in coal power. However, there is lack of comprehensive data on the pollution emission profiles, along with the physicochemical, thermal, and kinetic properties of Nigerian coals as required for power plant operations. Therefore, this paper presents preliminary findings on the physicochemical, microstructural, mineralogical and thermal properties of Owukpa (WKP) coal from Benue State in Nigeria. The results showed that WKP contains high compositions of combustible elements and heating value but low pollutant elements. Furthermore, thermal degradation revealed high conversion efficiencies particularly under oxidative conditions as required for electric power generation through combustion.

Fuel Characterization of Newly Discovered Nigerian Coals

This study seeks to characterize and highlight the fuel properties, rank, and classification of coals from Ihioma (IHM) and Ogboligbo (OGB) in Imo and Kogi states of Nigeria, respectively. The fuel properties were examined based on ultimate, proximate, and bomb calorific analyses. The results indicated that IHM coal contains comparatively higher C and H but lower O, N, and S content than OGB. In addition, the nitrogen (N) and sulphur (S) content for both coal samples were above 0.7 wt.% and 1.5 wt.%, respectively, which indicates high potential for pollutant emissions. Furthermore, the coal proximate properties were below 5 wt.% for Moisture; Volatiles (70 wt.%); Fixed Carbon (45 wt.%) and Ash (2.5 wt.%) on average. IHM coal has an HHV of 19.40 MJ/kg whereas OGB is 15.55 MJ/kg. This is due to the low carbon (C), hydrogen (H) and high oxygen (O) content in OGB whereas IHM contains higher VM and HHV. Furthermore, OGB presents better handling, storage, and transport potential. Furthermore, OGB has a higher fuel ratio and value index due to lower moisture, ash content, and volatiles. Based on the ASTM D388 standard, the coals were classified as Lignite (Brown) Low-Rank Coals (LRCs) with potential for energy recovery.

Evaluating the Energy Recovery Potential of Nigerian Coals under Non-Isothermal Thermogravimetry

This study investigated the fuel properties and energy recovery potential of two coal samples from Ihioma (IHM) and Ogboligbo (OGB) environs in Nigeria. The ultimate, proximate, and bomb calorimetric analyses of the coal were examined. Next, the rank classification and potential application of the coals were evaluated according to the ASTM standard D388. Lastly, thermal decomposition behaviour was examined by non-isothermal thermogravimetry (TG) under pyrolysis conditions from 30 – 900 °C. The results indicated IHM and OGB contain high proportions of combustible elements for potential thermal conversion. The higher heating value (HHV) of IHM was 20.37 MJ/kg whereas OGB was 16.33 MJ/kg. TG analysis revealed 55% weight loss for OGB and 76% for IHM. The residual mass was 23% for IHM and 44% for OGB. Based on the temperature profile characteristics (TPCs); Ton , Tmax , and Toff , IHM was more reactive than OGB due to its higher volatile matter (VM). Overall, results revealed the coals are Lignite (Brown) low-rank coals (LRCs) with potential for electric power generation.

Fluidised bed gasification and chemical exergy analysis of pelletised oil palm empty fruit bunches

The National Biomass Strategy was envisioned to foster the efficient valorisation and management of Oil Palm Waste (OPW) in Malaysia. However, the proposed Circular Energy Economy is hampered by poor OPW fuel properties, inefficient conversion techniques, and process design. This study explored the valorisation of Oil Palm Empty Fruit Bunches (OPEFB) Briquettes through fluidised bed gasification with the aim of exploiting the superior qualities of pelletised biomass and excellent reactor dynamics of fluidised beds. Gasification of OPEFB Briquettes was examined from 600 – 800 °C and equivalence ratio, ER is 0.20 – 0.25 under atmospheric pressure. The fuel properties and chemical exergy of OPEFB briquettes were characterised. The gasification of OPEFB briquettes produced high biochar yield and bio syngas with higher heating value from 1.15 – 3.05 MJ/m3 whereas the Cold Gas Efficiency (CGE) and Carbon Conversion Efficiency (CCE) ranged from 6.54 – 17.34 % and 43.37 – 78.16 %. Bed agglomeration and defluidisation typically encountered in pulverised OPEFB gasification were minimal during the gasification of OPEFB briquettes. In conclusion, the results demonstrated that OPEFB Briquettes gasification is a practical route for valorising OPW into renewable energy and sustainable fuels.

Alternative prediction models for data scarce environment

Abstract Effective accident prediction is needed in the chemical process industries to facilitate risk management during plant operations. This is however hampered by the unavailability of data needed for accident modelling purposes, and models that are based on distribution theory are used as they require the least amount of data. This article discusses the application of grey modelling approach and its combination with Bayesian network. The models are applied to two case studies, i.e. a process vessel and an LNG facility. The results obtained are compared to that of Poisson model. Results show that the hybrid first-order grey model with Bayesian network BG(1,1) is most accurate, followed by the grey models G(1,1) and G(2,1), with the Poisson model trailing behind. The results illustrated the potentials of grey modelling approach in dealing with scarce data conditions.

Control and optimization of aromatic compounds in multivariable distillation column

Product separations in petroleum refineries depend significantly on distillation process, which is known to be challenging to be optimally managed, especially when multiple products with variety of purity requirements are involved due to nonlinear dynamics and high degree of process interactions. In this paper, control and optimization aspects of a multivariable distillation process are discussed. A mathematical model of the system is simulated in MATLAB programming environment, and analyses of process behavior and control performances are carried out. The controllers are tuned using conventional Ziegler-Nichols method and L-V control configuration was adopted. The results on disturbance rejection and set point tracking capabilities, in order to maintain the purity of benzene in the distillate above 98.5 % are discussed. Based on these insights, the optimum operating conditions were determined, which serves as a good starting point for further works in addressing variety of problems related to process operations.