INFLUENCE OF HEAT SOURCE COOLING LIMITATION ON ORC SYSTEM LAYOUT AND WORKING FLUID SELECTION: THE CASE OG ALUMINIUM INDUSTRY

摘要

Energy recovery from the raw gas in aluminium production plant is investigated in this paper. This hot gas contains acid compounds and it should not be cooled below its dew point in order to avoid corrosion problems. This limitation is generally not considered in the published literature Common working fluids were screened, with two heat recovery configurations: Direct and indirect (thermal oil loop) systems. The power production loss for an indirect heat recovery system compared to a direct system was relatively small, about 5%. The acid dew point temperature restriction had less influence on the indirect system, which could utilize fully the low heat sink temperature available on the site. This factor almost fully compensates for the temperature loss induced by a second heat exchanger. Indirect systems can use standard ORC modules which could reduce the cost of the plant.