Industrial process
The industrial steam system at the ALANOD is based on a gas fired steam boiler, a condensate tank and a feed water tank with chemical conditioning. For an average production year, the heat energy of 940 000 m3 gas is used to produce 2000 kg of steam per hour. An ongoing extension of the production facilities with a new aluminium anodizing line will not only increase the steam demand to 4000 kg per hour, but also open opportunities to consider different options for the integration of the solar system. The steam is distributed to the production facility by two steam lines, with 4 bara / 143 °C and 9 bara / 175 °C, respectively.
The 4 bara steam line feeds the heat exchangers of the anodizing bathes (degreasing, brightening, sealing) as well as a hot water storage tank which is used to periodically replace the water content of the sealing bath. The dryers for the aluminium strip drying in the anodizing process are fed from the 9 bara steam line. From the convective and evaporation losses of the different baths and storages their continuous heat demand was estimated (Table 1). In addition, heating of the total storage content after the periodic discharge requires about 8 hours with a thermal power of 390 kW for storage tank 1 and 195 kW for storage tank 2.
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Table 1: Main heat consumers with continuous demand
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Ground space for the solar field is not available at the site. Roof areas of production halls or office buildings could be considered but would require interference with the static of the existing
structures. Therefore, in the context of the present extension, a dedicated platform for the solar field will be erected adjacent to the main production hall.
