One exemplary embodiment can be an acid alkylation system. The system can include a cooler-reactor and a settler. The settler can have a height and a width. Usually, the height exceeds the width. Generally, the cooler-reactor receives a feed of at least one of a stream including an olefin and a stream including an isobutane. Typically, at least a portion of one of the streams is bypassed around the cooler-reactor to the settler to control the temperature within the settler.