The Great Lakes' No. 5 coke-oven battery and by-products plant was recently rehabilitated and substantially modified. The battery consists of 85 ovens with a design coke production level of 890,000 tons/year. It includes a complex heating system, reversing system, quench station, emissions controls and oven machinery to control the charging and pushing of the ovens. The by-products plant handles 48 million cu ft of gas per day, utilizing two primary gas coolers, two exhausters, two electrostatic tar precipitators, secondary gas cooler, ammonia scrubbers, stills and destruction plant, waste heat boilers, boiler water treatment plant, gas blanketing system, gas boosters, water cooling tower, wet surface air cooler and a phenol extraction plant located a quarter mile away. A completely integrated distributed control system has greatly facilitated the operation of a complicated process such as the rehabilitated coke-oven battery and by-products plant. Manpower requirements are reduced, with more information being generated automatically. Operators spend much less time walking the plant and considerably more time monitoring the process. Training of operating and maintenance people was time consuming but once completed, the operation became much easier and less costly to control.