Case 13 More Energy for a Phenol Plant

Phenol eompounds are vital ingredients of proeesses that ultimately lead to the produetion of nylon, aspirin, and polyearbonate. EniChem SpA is one of the world s leading produeers of phenol. When the eompany was looking to boost phenol produetion at its plant in Mantova, Italy, they deeided to reeover the energy being used in their proeess. 

EniChem has been produeing this eaustie ehemieal eompound at Mantova sinee the plant opened in the 1960s. Initially, the total annual output was approximately 10,000 tons. This output figure inereased rapidly and, in 1987, a eombined eentrifugal eompressor and expander were installed to boost produetion from about 230,000 to 270,000 tpy. Operating at a flowrate of 23,000 kg/hr (50,715 Ib/hr), the three-stage eompressor raises air pressure from 1 bar (14.5 psia) to 9.5 bar (137.8 psia) and is used to feed the reaetor in the phenol produetion plant. 

The plant reeognized the energy potential of the off gas from the reaetor—a eombination of nitrogen and oxygen at a temperature of 125°C, a pressure of 6.4 bar (92.8 psia), and a flowrate of 19,000 kg/ 

The main power source is a 2,200 kW rated motor, which drives two high-speed pinions through integral gears. The first stage of the compressor operates at 17,900 rpm, while the second and third stages operate at 21,800 rpm. The unit is controlled by a local control system, but operators can also monitor the operating parameters from the plant control room. 

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