ORC DEPLOYMENT OPPORTUNITIES IN GAS PLANTS

asme-orc2015 Tracking Number 135

Gas processing plants are characterized by large energy flows. Therefore it is key to maximize energy efficiency and to optimize utility balances. In the gas to liquid (GTL) complexes operated by Shell in Malaysia and Qatar, the highly exothermic Fischer Tropsch process is applied to convert gas into liquid hydrocarbon products. Most of the available thermal energy is used to cogenerate steam and to preheat feed streams, but still substantial additional cooling is required to reduce the temperature of intermediate streams for further processing. In the Qatar GTL plant this duty is in the order of 600 MWth. By a detailed investigation that included simulations and cost evaluation of both commercial ORC systems and dedicated advanced ORC concepts, it could be established that heat recovery by means of low-temperature ORC units is a feasible option. Prerequisite is that the ORC unit is directly coupled to the process, without an intermediate thermal fluid loop. A parallel study focused on application of ORC systems in LNG plants. These plants waste large quantities of thermal energy in the form of high temperature exhaust gas from gas turbines used for power generation and gas compression. A similar evaluation of current ORC technology for the recovery of this high-temperature heat led to the conclusion that ORC systems can be more attractive than steam cycles for waste heat recovery from both mid-range gas turbine installations and for larger systems in remote or arid locations where steam cycles are impractical. This still is a large scope of deployment.