Browsing by Author "Ekwueme, Stanley Toochukwu"

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    Development of optimal gas-to-liquids (GTL) plant using steam/Co2 reforming for synthesis gas production
    (Federal University of Technology, Owerri, 2022-02) Ekwueme, Stanley Toochukwu
    This research work is on method for optimisation of GTL plant using Steam/CO2 reforming for syngas generation. Extensive modeling of GTL plant has been done. Two cases were considered during the simulation of the GTL plant. The first case being the base case was the use of oxygen gas as the feed reactant gas using an auto-thermal reformer for the production of synthesis gas. The alternative case which is the proposed method in this work uses CO2 in lieu of oxygen for the production of synthesis gas. CO2 method was chosen because of its cheap availability and the ability to be recycled from purge gas and reused reducing pollution. Honeywell’s Unisim software was used for the simulation and the Peng-Robinson equation of state was chosen as the fluid property package. The simulation was done unit by unit and integration of all units was made. The synthesis gas unit was simulated in Unisim as a conversion type reactor using two separate reactors while three equilibrium reactors were used to control the water gas shift reaction to maintain favourable H2/CO ratio. The FT reactor was modeled as a multi-tubular bed reactor and simulated as a plug flow reactor (PFR) in Unisim using heterogeneous catalytic reaction type. Technical and economic performances were analyzed for both methods. The technical analyses revealed that the proposed steam/CO2 method gave a H2/CO ratio of 2.17 compared to 2.21 obtained for the autothermal reformer (ATR). Furthermore the carbon efficiency of the two methods revealed 77.68% and 92.17% for base case and the proposed method respectively making the proposed method more efficient. The liquid yield shows that the proposed method has a liquid yield of 5730b/d over the 5430b/d obtained from the base case representing an increase in product yield of 5.5%. The economic analyses show a quicker pay-out time of 4.9 years from the proposed model as against 5.9 years from the base case. Using the proposed method gave an annual cashflow increase of 20.9% and NPV increase of 59.7% at 10% discount rates. Thus the proposed method is more profitable in terms of NPV. This project will be suitable for application in the Niger Delta stranded and remote gas locations which are known for gas flaring leading to environmental pollution.
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    ItemOpen Access
    Mathematical model for time of Leak estimation in natural gas pipeline
    (Science Publishing Group, 2019) Obibuike, Ubanozie Julian; Ekwueme, Stanley Toochukwu; Ohia, Nnaemeka Princewil; Igbojionu, Anthony Chemazu; Igwilo, Kevin Chinwuba; Kerunwa, Anthony
    The ability to detect leak is crucial in pipeline fluid transport operations. Leaks will inevitably occur in pipelines due to wide range of uncertainties. A good leak detection system should not only be able to detect leak but also accurately estimate the actual time of leak occurrence. This will enable proper estimation of the fluid loss, from the pipeline before shut-in of the pipeline or before remedial actions were carried out on the pipeline which ultimately will help quantified the degree of financial or environmental implications resulting from the leak incidence. This paper gives a new model for the estimation of the time of leak in natural gas pipeline. The idea for the model hinges on the notion that the time of response of most pipeline alarm are not necessarily the time actual time the leak occurred. Period of lapse depends on the accuracy, sophistication of the alarm system and volume of leak it is capable of detecting. Most alarm systems respond at later times than the time the leak occurred. Quantification of fluid loss volume demands that the actual time of leak occurrence be determined, this means that the time the leak occurred must be calculated accurately. The model was simulated using the Matlab software. The results show that the model is highly accurate when tested with field data