Technical profile: 20,000 tonne silos

by Teresa Acklin
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   Contributed by suppliers, technical profiles feature new technology, products, specific applications or prioprietary concepts. This article was prepared by Kepler Weber International S.A., Porto Alegre, Brazil.

   In March 1992, work began on a storage capacity expansion project in Merida, Mexico, for Aceitera Del Golfo S.A. de C.V., a company affiliated with a group of major Mexican vegetable oil producers.

   If the expansion were completed in six months, the company would be able to load and store the $60 million worth of soybeans that would be arriving from the United States at the port of Progreso, not far from Aceitera's headquarters in Merida.

   A month into the erection work, 700 people made up the team of assemblers, welders, electricians, ironsmiths and assistants who were involved in the massive project. By the end of August, the soybeans were stored in 11 silos and the 12th was being filled. The U.S.$4 million project executed by Kepler Weber S.A., Porto Alegre, Brazil, included A-200 silos, some of the largest steel silos in the world.

   Developed and built by Kepler Weber, the A-200 silos offer a structural solution for efficient and economical storage. Each A-200 silo at the Merida site is built of galvanized, high-resistance sheet steel and is 28 meters high, 60 meters in diameter and occupies 84,000 square meters of space.

   A-200 silos store any kind of non-cohesive cereals in bulk. Grain can be moved using simple, easily coupled conveying equipment. The silos are large enough that they allow access to the interior for bagged grain, agricultural equipment, large vehicles and trailer trucks through a side door.

   The advanced technology used in manufacturing the silos allows large capacities. In the flat bottom version, 7,000 to 15,000 tonnes can be stored. In the truncated cone, or hopper-bottom option, holding capacity ranges from 11,000 to 22,000 tonnes. Because its roof is at a 30º slant, the A-200 silo withstands winds up to 120 km per hour.

   The “inside tower,” placed in the center of the circle, supports the body and the roof of the silo, allowing an extra load of up to 6 tonnes. It makes a single fully automated loading and unloading element, which means less investment when installing the silos.

   With so large an area and significant load volume, the A-200 silos have an aeration system for maintaining an ideal storage temperature and preserving grain quality. Aeration is segmented; the silo floor is divided into rings that can be fully or partially aerated.

   Since the A-200 silo was introduced several years ago, 33 units have been installed worldwide, including projects in six Brazilian states, Argentina, Bolivia, Mexico and Uruguay.