NOVELTY - Generating a synthesis gas involves: introducing a fuel stream within a premixing device; preconditioning the fuel stream through a flow conditioning device; introducing an oxygen stream downstream of the flow conditioning device to facilitate premixing of the fuel stream and oxygen to form a gaseous premix; and forming the synthesis gas in a combustion chamber through partial oxidation of the gaseous premix.    USE - For generating a synthesis gas, such as synthesis gas enriched with carbon monoxide and hydrogen gas (claimed); and for producing at least one product, such as synthetic diesel fuel, synthetic kerosene, ethanol, dimethyl ether, and/or naptha, by Fischer-Tropsch processing, in a a gas to liquid system.    ADVANTAGE - The method enhances conversion efficiency and decrease capital cost of syngas generators and systems, by using a premixed partial oxidation combustion in a syngas generator that operates with a substantially high fuel to oxygen (or oxidizer) ratio, and results in a syngas composition enriched with carbon monoxide (CO) and hydrogen (H2). The method can also be utilized in different applications, such as syngas generators employed in gas to liquid systems. The flow conditioning of the fuel stream and subsequent introduction of oxygen enable fast mixing of the fuel stream and oxygen, and result in substantially shorter premixing residence time. The premixing of the fuel stream and oxygen prevents explosion of premixed natural gas and oxygen by minimizing the residence time and volume of the premixing region. Further, the combustion of substantially premixed reactants in the syngas generator leads to a compact reaction zone that achieves near-equilibrium composition and negligible formation of solid carbon in the reaction zone. The premixing of the reactants prior to combustion along with staging and piloting, optimize the operability, and product composition enables a compact POx syngas generator. The premixed rich partial oxidation combustion substantially reduces the capital cost by reducing the size and complexity of the syngas generator. The POx syngas generator can be developed through modular components and independent of the gas to liquid plant, in which the syngas generator may be employed. The compact size of the syngas generator also makes it desirable for use in gas to liquid (GTL) plants having limited space.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a premixed partial oxidation (POx) syngas generator comprising: a premixing device configured to mix a fuel stream and oxygen in a premixing region to form a gaseous pre-mix, which comprises a fuel inlet configured to introduce the fuel stream within the premixing device; a flow conditioning device configured to pre-condition the fuel stream; and an oxygen inlet configured to introduce oxygen into the fuel stream to facilitate premixing of the fuel stream and oxygen in the premixing region located downstream of the flow conditioning device; and a combustion chamber configured to combust the gaseous pre-mix from the premixing device to produce a synthesis gas enriched with carbon monoxide and hydrogen gas; and    (2) a gas to liquid system comprising: an air separation unit configured to separate oxygen from air; a gas processing unit configured to prepare a fuel stream for combustion; a combustion chamber for reacting oxygen with the fuel stream at an elevated temperature and pressure to produce a synthesis gas enriched with carbon monoxide and hydrogen gas; and a premixing device disposed upstream of the combustion chamber and configured to mix the fuel stream and oxygen, in which the premixing device comprises: a fuel inlet configured to introduce the fuel stream within the premixing device; a flow conditioning device configured to pre-condition the fuel stream; and an oxygen inlet configured to introduce oxygen into the fuel stream to facilitate premixing of fuel stream and oxygen in a premixing region located downstream of the flow conditioning device.