Recovery of Energy Through Exhaust Gas Condensation: A Profitable Idea

Abstract

Cimo SA, a company situated on the chemical site of Monthey, Switzerland, runs the thermal power station providing steam and part of the electricity required for the various production buildings of Ciba Specialty Chemicals and Novartis Crop Protection.
The boiler house includes several units; the main ones, Nos. 4 and 5, are used alternately:
– boiler No. 4, nominal capacity of 80 t/h is used mainly in summer;
– boiler No. 5, object of the present project, has a nominal rating of 160 t/h at 115 bar and 525 °C. This unit is used in winter when steam demands vary between 60 and 110 t/h.
The two boilers, equipped with back-pressure turbines, are fitted with burners for natural gas and fuel oil, gas being the main fuel (95%). The low-pressure steam is then used in the various production facilities without any return of condensate to the station. Because of this fact, the feed-water of the boilers is therefore demineralised water, which must be pre-heated by low-pressure steam before being degassed. This pre-heating represents an important part of the total energy consumption.