The modelling and simulation of flare gas combustion is a crucial area of research in the fields of combustion science and environmental engineering. Flare gas, a waste product from various industrial processes, is commonly burned to reduce environmental pollution and safety hazards. This study aims to perform sensitivity analysis of a burner geometry and combustion parameters to recommend efficient (low emission and high heat) burner geometry and operation parameters. The enclosed burner is preferred for power generation, as it mitigates the wind effect. To improve the flare burner, factors like gas condition (pressure and temperature), flow rate, and gas composition need to be analyzed to determine the burner's appropriate size and the flare stack's height and length. Sensitivity analysis plays a critical role in assessing the geometry variables and operation conditions of the structure. The study's specific objectives are threefold: Firstly, combustion simulations are conducted using ANSYS Fluent software, where the selected burner geometry models the combustion process within an enclosed flare system while considering temperature and pressure factors. Secondly, the results of these simulations are validated by comparing them to experimental or relevant data, ensuring accuracy in representing the real-world combustion process. This validation aids in making informed decisions about system design and operation conditions. Finally, sensitivity analysis of the burner geometry and combustion parameters is performed to understand their impact on the system's efficiency and effectiveness. Various simulations are run with different parameter values, such as fuel-to-air ratio, to identify key factors influencing the system's performance. This thesis provides valuable insights into the optimization of flare gas combustion systems, guiding the design and operation of efficient and improved environmental impact of the flare gas combustion units. The results obtained through the proposed modelling and simulation approach contribute to the advancement of combustion science and environmental engineering, paving the way for sustainable and responsible industrial processes.