Technology

DEVELOPMENT OF INTEGRATED MEASURES FOR PERFORMANCE ANALYSIS OF A GAS TURBINE POWER PLANT

2025-10-21T11:16:44Z

DEVELOPMENT OF INTEGRATED MEASURES FOR PERFORMANCE ANALYSIS OF A GAS TURBINE POWER PLANT BASSEY, Joseph Benedict Performance analysis of gas turbine power plant is imperative for its optimal operations and maintenance. Reliability, exergy efficiency and emission characteristics are measures that have been used independently to assess its performance. However, this independent assessment approach has not adequately expressed the actual state of the plant performance. While other approaches are being explored, literature on Integrated Assessment Approach (IAA) is sparse. This study therefore focused on development of performance measures of IAA for the evaluation of gas turbine power plants. Four-year (year-1, year-2, year-3 and year-4) available data of a 180 MW simple cycle gas turbine power plant (Model No.:GT13E2) operating on dry low NOx technology was obtained to determine the plant performance state. Performance parameters of exergy destruction and exergy efficiency (at base loads of 80, 120 and 140 MW), reliability and availability were analysed, yearly. Steady state exergy analysis equation was used to evaluate the plant exergy destruction and exergy efficiency. System adequacy technique was used to evaluate the plant reliability and availability. Two new performance indexes (I and II) based on the IAA were developed and compared with the independent measures in the assessment of the power plant. Exergy efficiency and reliability were combined to formulate Index I, while exergy efficiency and availability were combined to formulate Index II. The indexes ranges between zero and one indicating the minimum and maximum points. Data were analysed using ANOVA at α0.05. Plant exergy destruction at 80, 120 and 140 MW base loads were 0.6640, 0.6290 and 0.5914; 0.6476, 0.6342 and 0.5855; 0.6295, 0.6342 and 0.5926; and 0.6523, 0.6285 and 0.6043 in year-1, year-2, year-3 and year-4, respectively. Exergy efficiencies at 80, 120 and 140 MW were 0.7195, 0.7916 and 0.8691; 0.7510, 0.7854 and 0.8775; 0.7808, 0.7774 and 0.8602; and 0.7389, 0.7875 and 0.8445 in year-1, year-2, year-3 and year-4, respectively, indicating improvement as base load increased. Reliability and availability were 0.8820 and 0.8168; 0.7959 and 0.6734; 0.7604 and 0.7497; and 0.6294 and 0.7238 for year-1, year-2, year-3 and year-4, respectively. At 80, 120 and 140 MW base loads, Index I values were 0.8281, 0.8630 and 0.9289; 0.7919, 0.8098 and 0.9023; 0.7833, 0.7819 and 0.8822; and 0.6538, 0.6860 and 0.8197 in year-1, year-2, year-3 and year-4, 7 respectively. At 80, 120 and 140 MW, Index II values were 0.5877, 0.6466 and 0.7099; 0.5058, 0.5289 and 0.5909; 0.5854, 0.5828 and 0.6449; and 0.5345, 0.5700 and 0.6113 in year-1, year-2, year-3 and year-4, respectively. Index I exhibited higher sensitivity by mimicking the combined behaviour of reliability and exergy efficiency. The best plant state was achieved in year-1 at 140 MW base load. Index II also indicated that the plant performed better in year-1 at 140 MW base load compared to other years. The integrated measures had similar trend with the independent measures but were significantly different. The integrated assessment measures were found suitable in the assessment of gas turbine power plant as they gave a better expression of the actual plant performance state.

CALCINATION AND SYNERGISTIC RATIO OPTIMISATION IN THE PRODUCTION OF HYBRID AGRICULTURAL POZZOLANS FROM AGRICULTURAL WASTES FOR THE CONSTRUCTION INDUSTRY

2024-05-23T12:14:08Z

CALCINATION AND SYNERGISTIC RATIO OPTIMISATION IN THE PRODUCTION OF HYBRID AGRICULTURAL POZZOLANS FROM AGRICULTURAL WASTES FOR THE CONSTRUCTION INDUSTRY MAC-ETELI, Happiness Davies Cement is an important material in the construction industry. However, the environmental problems associated with the mining and calcination of limestone for cement production necessitates the search for supplementary cementitious materials with minimal threat to the environment. Periwinkle and clam shells, processed into ash are potential substitutes for cement in concrete. This study was designed to investigate the suitability of Periwinkle Shell Ash (PSA) and Clam Shell Ash (CSA) and a hybrid of both as partial replacements for cement in concrete. Shells were sourced from Amassoma, Bayelsa State, Nigeria, washed, sun dried and calcined at varying temperatures (200, 400, 600 and 800 oC). These were pulverised to pass through 75 µm sieve to produce PSA, CSA, and hybrids of both, mixed at 70:30, 60:40, 50:50, 40:60 and 30:70. Grade M20 concrete specimens were produced at varying Portland limestone cement (PLC) replacement levels (0, 20, 30, 40 and 50%) with 0% as control, and cured for 28 days prior to testing. Specific gravity, flexural strength, compressive strength, Water Absorption Index (WAI), Chloride Induced Strength Loss Index (CISLI), and Sulphate Induced Strength Loss Index (SISLI), were conducted in accordance with British Standards. Combined mixture methodology was used to develop regression models from laboratory data, analysed and optimised at 95% confidence interval to ascertain Optimum Pozzolanic Reactivity (OPR) based on Strength Activity Index (SAI). Emissions of CO2 associated with calcination of samples were analysed and compared to that of PLC using data from energy demand and carbon footprint. Specific gravities were 3.12±0.24, 2.96±0.01, 3.00±0.10, 3.14±0.03, while flexural and compressive strengths were 5.29±0.14, 2.83±0.10, 2.83±0.08, 3.36±0.21 and 27.74±1.41, 18.27±1.10, 19.21±0.25, 21.67±2.29 N/mm2 for PLC, PSA, CSA and 60% PSA:40% CSA, respectively, at 40% cement replacement level, produced at 600 oC. Compressive strengths of 60% PSA:40% CSA, were 78.1% of PLC, 118.6% of PSA and 112.8% of CSA; implying that the hybrid was stronger than PSA or CSA. Also, WAI, CISLI, and SISLI, were 1.98±0.19, 2.84±0.08, 3.25±0.17, 2.75±0.13; 24.56±2.15, 19.34±0.37, 0.44±0.08, 6.10±0.84; and 16.47±1.43, -10.97±1.32, - 16.88±0.68, 4.09±0.62 for PLC, PSA, CSA and 60% PSA:40% CSA. The PLC had the least WAI but diminished more in strength due to chemical attacks and absence of pozzolans compared to PSA and CSA. The OPR based on SAI was 55.5% PSA:44.5% CSA, and cement replacement levels were 19.7, 23.2, and 44.0%, for PSA, CSA and 55.5% PSA:44.5% CSA, respectively, produced at 425, 527, and 607 oC. A uniform compressive strength of 20.8 N/mm2 was obtained for PSA, CSA and 55.5% PSA:44.5% CSA, produced at 425, 527, and 607 oC, respectively, satisfying the SAI criteria. Optimised WAI, CISLI, and SISLI of PSA, CSA and 55.5% PSA:44.5% CSA were 2.46, 2.52, 2.51; 2.10, 3.06, 12.72; and -33.16, -31.48, -0.08%, when produced at 425, 527, and 607 oC. A kilogram of pozzolan emitted 350g of CO2 at calcination, while that of PLC was 490g; providing a 28.60% savings in CO2 emissions. Periwinkle and clam shells enhanced cement replaceability and satisfied the strength activity index pozzolanic criteria, when synergised and ashed optimally. Consequently, environmental pollution associated with excessive limestone harvest and processing was mitigated.

DEVELOPMENT AND OPTIMISATION OF AN INTEGRATED SEMI-AUTOMATED GRADING MACHINE FOR COWPEA (Vigna unguiculata (L.) WALP) SEEDS

2024-05-23T12:11:18Z

DEVELOPMENT AND OPTIMISATION OF AN INTEGRATED SEMI-AUTOMATED GRADING MACHINE FOR COWPEA (Vigna unguiculata (L.) WALP) SEEDS AUDU, John Nigeria is the largest producer of cowpea. Despite this relatively large production, its export has been hindered by poor seed grading and inefficient processing. Existing cowpea grading machines are mostly for unit operations. Integrated grading machine are needed for improved seed grading and efficient processing. Therefore, this study was designed to develop an integrated semi-automated cowpea grading machine. Standard methods were used to determine the optical and electrical parameters of three indigenous cowpea seed varieties (NG/AD/11/08/0033, NG/OA/11/08/063 and NGB/OG/0055) for the automation unit design considerations. This was carried out at seed moisture levels (8.0, 10.0, 12.0, 14.0 and 16.0%), light wavelength (320, 420, 520, 620 and 720 nm) and current frequency (1, 500, 1000, 1500, 2000 kHz). Thereafter, an integrated semi-automated machine with three separating units was developed and automated using machine vision technology. Operational parameters used for evaluation were speed of drum (40, 60 and 80) rpm, bucket conveyor speed (250, 300 and 350) rpm and metering disc (12, 16 and 20) rpm; seed variety and grade (9.8%, 16.0% and 21.0%) of impurity. The total machine system output was evaluated and optimised in terms of efficiency, throughput, maximum capacity, actual utilisation and backlog, using response surface methodology. Prediction interval and multiple regression analysis were used for validation at α 0.05. The optical properties ranged from: 0-1.8%, 0-1.0%, 0-12.0%, ([38-92.2%] [0.7-9.0%] [13.6-27.3%]) for absorbance, reflectance, transmittance and colour (L* a* b*), respectively; while electrical properties ranged from 1.926-15.625 Ω, 0.272-2.209 Ωm, 0.064–0.519 S, 0.453–3.671 S/m, 1.800x10-11–1.380x10-7 F, 0.500-4928.570, 6.020 x107- 9.040x1021 H) and 1.150x106–1.450x107 Ω, for resistance, resistivity, conductance, conductivity, inductance and impedance, respectively. The two separating units (sieve drums) removed impurities > 12 mm and < 2 mm with efficiency of 76.6±9.343% and 85.3±11.1%; throughput of 0.220±0.139kg/hr and 0.144±0.111kg/hr, respectively. The third digital automated sorting unit separated diseased and insect damaged seeds by colour with efficiency of 82.1±7.2% and throughput of 1.386± 0.758kg/hr. Operational parameters were found to have significant effect on all evaluation terms. The efficiency, throughput,vi maximum capacity, actual utilisation and backlog of the total system output ranged from 63.5-80.4%, 0.574–3.732 kg/hr, 6.882-44.778 kg/12hr, 0.083-0.083 (8.3%) and 0.03–0.182 kg, respectively. At 80.4% efficiency, the impurity of grade 3 was reduced to grade 2, and 2 to 1 based on the standard export grade range. The integrated machine system optimisation achieved two best solutions. The first and second having maximum total system impurity separating efficiency of 81.3 and 79.9%, maximum total system throughput of 3.470 and 5.077 kg/hr and minimal total system backlog of 0.064 and 0.07 kg, respectively. The validation data were within 95% low and high prediction intervals. The evaluation terms had coefficient of determinations (R2) values > 0.9 showing no significance between predicted and validation data. The developed integrated semi-automated grading machine for cowpea reduced the impurity in indigenous cowpea varieties to exportable grade.

MACHINE PARAMETERS FOR KENAF PELLET PRODUCTION FOR REMEDIATION OF CRUDE OIL POLLUTED WATER BODIES

2024-05-23T12:08:30Z

MACHINE PARAMETERS FOR KENAF PELLET PRODUCTION FOR REMEDIATION OF CRUDE OIL POLLUTED WATER BODIES KADIRI, Azeez Oluwaseun Remediation of crude petroleum polluted water for agricultural activities is a challenge. Kenaf has been found to have potentials for remediation and pelletising it will improve handling and recovery. Literature is sparse on the appropriate operating parameters for kenaf pelleting machine. This study was designed to investigate the effects of Screw Pitch (SP), Speed of Rotation (SR), and Die Diameter (DD), on kenaf pellets properties suitable for crude oil spill remediation. A pelleting machine was designed for kenaf using standard procedures. The machine was evaluated using response surface methodology. The variables were SP (40, 50, 60, 70 and 80 mm), SR (40, 50, 60, 70 and 80 rpm) and DD (27.5, 30.0, 32.5, 35.0 and 37.5 mm). Thirty experimental combinations were generated from the variables to get responses on machine efficiency (Pelleting Efficiency (PE) and Percentage Recovery (PR)), pellets’ mechanical properties (Force, Deflection, Energy, Young modulus and Durability Index, (DI)) and remediation potentials (oil recovered and changes in pH). At different combinations, the machine was used to pelletise samples of kenaf, starch and water (1:1- 2:3) mixture. Machine efficiency and mechanical properties were determined using ASABE and Universal Testing Machine. The oil recovered was determined by comparing oil contents before and after remediation using a spectrophotometer according to AOAC standards, while changes in pH were determined by comparing pH values before and after remediation. The process was simulated and optimised using artificial neural network and its accuracy determined using mean square error (MSE) and coefficient of determination (R2). Data were analysed using ANOVA at α0.05. The PE and PR ranged 82.3-95.8% and 68.4-88.3%, respectively. The PE and PR increased with increase in DD and SR. Forces at peak, yield and break ranged 84-280, 108-342 and 142-504 N, respectively. Deflection at peak and break were 2.01-5.48 and 3.89-10.24 mm, respectively. Minimal Energy to peak, yield and break were 4.93, 6.75 and 9.42 Nmm/s, respectively. The Young’s modulus and DI were 0.03 N/mm2 and 98.9 %, respectively. The SP, DD and SR significantly affected the mechanical properties. Oil recovery ranged between 97.6 % and 99.8 %, while changes in pH ranged 0.01-0.22, signifying the occurrence of remediation. Increase in SP and DD yielded an increment in oil removal and increased changes in pH, while a rise in SR led to a reduction in quantity of oil removed and an increase in the changes in pH. The MSE and R2 of the models varied between 0.0003 and 125545469.3; 0.2589 and 0.9978, respectively. The optimal operating conditions for the production of kenaf pellets for remediation were 54 mm SP, 68 rpm SR and 34 mm DD. Kenaf pellets were good absorbents for remediation of crude oil polluted water bodies. Optimal conditions for the production of durable kenaf pellets for the effective remediation of crude petroleum polluted water bodies were established. An efficient pelleting machine for the production of kenaf pellets was developed.