A process in which raw materials are continuously fed and in which processed materials continuously leave at the same rate. As an open system, both material and energy are transferred across the system boundary. In contrast with a batch process, the process equipment volumes are smaller and the operating costs lower. Continuous processes are used for high-quality production. Automated control is necessary to ensure that process conditions of flows, temperatures, and pressures are maintained at all times. A semi-batch process has certain elements within the continuous process that operate as a batch process, such as the removal of moisture by a molecular sieve, but the overall effect is a continuous production.