The alkylation of C4 olefins with isobutane to produce high-octane C8 components ("alkylate") is a very important process in many oil refineries. The Kellogg process uses a sulfuric acid catalyst in a series of agitated reactors, which must operate at temperatures that require refrigeration because of undesirable side reactions that are favored by high temperatures. The reactors are cooled by boiling the liquid in the reactor, compressing the vapor, condensing it, and returning the liquid back to the reactor. A large excess of isobutane is used to suppress undesirable reactions, which requires a large recycle stream. Inert components (propane and n-butane) that enter in the fresh feed streams must be purged from the system. Two distillation columns are used, one of which has a vapor sidestream in addition to distillate and bottoms streams. This paper studies a simplified version of the autorefrigerated alkylation process and demonstrates the design trade-offs and interaction among design optimization variables such as reactor size, reactor temperature, compressor work, and isobutane recycle. Large reactors permit lower temperatures for a given olefin conversion, which improves selectivity. However, low reactor temperatures produce a low reactor pressure, which increases compressor work. Higher isobutane recycle improves selectivity but increases energy consumption and equipment sizes in the separation section. So the optimum economic design must balance the capital costs of reactors and distillation columns with the energy costs of compression and reboiler heat inputs. The location where the fresh feed streams enter the process also affects the design. An effective plantwide control structure is also developed that handles large disturbances in throughput and feed compositions. The structure has several uncommon control features: control of two compositions and one temperature in the sidestream column and a proportional-only temperature control in the other column.