To extract oil from oil seeds in a mechanical pressing operation, the oil seeds may be conditioned and then cooked before being subsequently pressed to release the oil contained in the seeds. In one application, a conditioning vessel is used that includes a shell through which the oil seeds move during operation and multiple heat transfer stages. Downstream of the conditioning vessel, a cooking vessel receives the oil seeds pre-conditioned in the conditioning vessel and cooks the oil seeds, generating a gas-containing stream that includes water vapor. The gas-containing stream is recycled back to one or more of the heat transfer stages of the conditioning vessel, providing direct heat transfer from the cooking vessel to the conditioning vessel. This arrangement can increase the energy efficiency of the operation and improve the performance of the system.
