SCA Uses Enviro-Friendly Gas Sponge to Treat Recycling Plant Biogas
SCA Packaging Italia has installed two Whessoe Varec gas purifiers at its paper recycling plant in Lucca. The purifiers treat the biogas produced by the plant's anaerobic digesters to remove hydrogen sulfide, allowing the gas to be used in a new environmentally-friendly energy recovery system. The new system reduces the need for waste gas flare-off, and was selected over other available recovery technologies due to its low operating costs and the lack of hazardous by-products.
The purifiers take biogas produced by anaerobic digesters used to treat wastewater from the process and react with it to eliminate virtually every trace of hydrogen sulfide, a very corrosive chemical. Because of the high sulfur content in pulp and paper waste, the concentrations of hydrogen sulfide in this application are typically 20,000 ppm, a very high level that can significantly shorten the working life of generators.
Two 10-in. (25.4-cm) purifier units provide a treatment capacity of about 2,500 m3 of biogas/day. These feed a new power generation system that continually produces approximately 500 kw/hr. The investment for this new plant is approximately 1 billion Lira ($584,000). Based on a cost of 170 Lira ($0.09) kw/hour, this provides a projected return on investment for the energy recovery system of less than a year and a half.
Whessoe Varec's gas purifiers feature a novel design that eliminates the requirement of conventional iron sponges to be routinely removed and exposed to the atmosphere, by maintaining an injection of air equivalent to around 2.5% of the biogas flow rate. This extends media life by typically three to four times, providing an efficient low-maintenance solution for automated plants. In the purifier model selected for this application (235 Series), hydrated iron oxide impregnated wood shavings serve as the sponge.
The gas purifiers were manufactured in Europe at the company's UK headquarters. The installation is the first in Italy for this innovative purifier technology.
SCA Packaging is Europe's leading manufacturer of corrugated board packaging with a 12% market share, and is part of the integrated paper company SCA Svenska Cellulosa Aktiebolget). SCA is Europe's foremost user of recovered paper. Its products are based on equal quantities of recycled and virgin fibers. In addition to its Porcari (Lucca) facility, the company produces corrugated board in Belgium, France, Germany, Great Britain, Hungary, Ireland, Poland, the Netherlands, and Sweden, and in plants in which SCA has minority holdings in Switzerland, Spain, Portugal, and Turkey.
For more information: Whessoe Varec Ltd, Heighington Lane, Newton Aycliffe, Co. Durham, DL5 6XZ, UK. Tel: 44 (0)1325 301100, Fax: 44 (0)1325 300840.