Résumé -Amélioration des performances des turbines à gaz utilisées dans les conditions sahariennes par injection de vapeur d'eau -Le rôle des turbines à gaz, dans la production d'électricité et l'industrie pétrolière, a pris une dimension particulière ces dernières années. À cet effet différentes méthodes (régénération, refroidissement intermédiaire, préchauffage et injection de vapeur d'eau) ont été utilisées afin d'améliorer les performances des cycles de turbine à gaz. Dans cette optique, la méthode d'injection de vapeur d'eau en amont de la chambre de combustion d'une turbine à gaz a été proposée, étudiée et comparée avec un cycle simple. L'objectif principal de ce travail consiste en l'élaboration d'un programme de calcul de l'influence des conditions ambiantes sur les caractéristiques des différents processus de la turbine à gaz, telles que la compression, la combustion et la détente. Une fois les paramètres de fonctionnement optimaux connus, le calcul des performances de l'installation a été revu en injectant des quantités convenables de vapeur d'eau en amont de la chambre de combustion. Les résultats obtenus sont en accord avec ceux de la littérature et montrent que la méthode d'injection de vapeur d'eau en amont de la chambre de combustion améliore considérablement les performances de la turbine à gaz. Ces résultats sont représentés sous forme de courbes en deux et trois dimensions pour une meilleure illustration des phénomènes physiques. Abstract -Gas Turbine Performances Improvement using Steam Injection in the Combustion Chamber under Sahara Conditions -Gas turbines are generally used for large scale power generation. The basic gas turbine cycle has low thermal efficiency which decreases in the hard climatic conditions of operation, so it is important to look for improved gas turbine based cycles. Among several methods shown their success in increasing the performances, the steam injected gas turbine cycle (STIG) consists to introduce a high amount of steam at various points in the cycle. The objective of the present work is to improve the performances of gas turbine used under

The gas turbines are generally used for large scale power generation. The basic gas turbine cycle has low thermal efficiency, which decreases in the hard climatic conditions of operation, so the cycles with thermodynamic improvement is found to be necessary. Among several methods shown their success in increasing the performances, the steam injected gas turbine cycle (STIG) consists of introducing a high amount of steam at various points in the cycle. The main purpose of the present work is to improve the principal characteristics of gas turbine used under hard condition of temperature in Algerian Sahara by injecting steam in the combustion chamber. The suggested method has been studied and compared to a simple cycle. Efficiency, however, is held constant when the ambient temperature increases from ISO conditions to 50°C. Computer program has been developed for various gas turbine processes including the effects of ambient temperature, pressure ratio, injection parameters, standard temperature, and combustion chamber temperature with and without steam injection. Data from the performance testing of an industrial gas turbine, computer model, and theoretical study are used to check the validity of the proposed model. The comparison of the predicted results to the test data is in good agreement. Starting from the advantages, we recommend the use of this method in the industry of hydrocarbons. This study can be contributed for experimental tests.

In the present work, the overall behavior of a steam boiler is investigated using RELAP5/MOD3.2 system code at three different operating loads. Main thermal-hydraulic parameters are analyzed at steady-states corresponding to 60%, 100% and 110% of the boiler nominal load. RELAP5 system code is widely used in the design and safety analysis of nuclear reactor installations as well as for conventional facilities in recent years. The steam boiler studied herein is a water-tube natural circulation type used in a natural gas liquefaction complex for superheated steam production purposes. A complete model of the steam boiler has been developed for the RELAP5 code. This model, that is also suitable for transient simulation, has been used for the reconstruction of three steady-state tests in order to assess the steam boiler safety features during the operation. The model includes all parts that can eventually influence the safety of the steam boiler particularly the control and regulation system. A qualification process has been undertaken in the aim to verify the capability of the model to reproduce the main parameters of the steam boiler. This process revealed that RELAP5 system code results matches significantly the experimental data of the steam boiler. Finally, it should be mentioned that the results obtained so far are very encouraging for studying the general behavior of the steam boiler in transient operating conditions, as well as for evaluating its safety under hypothetical scenarios. This step will be undertaken in the near future and will allow the check of the code capability to simulate thermal-hydraulic phenomena occurring in the steam boiler during transient operation.

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