OPTIMIZING DRYING SYSTEMS IN COTTON PRODUCTION

Cotton is one of the most commonly used fabrics in the world, and its cultivation dates back almost 7,000 years. It is derived from shrubs of the Gossypium genus—part of the mallow family—and is grown in tropical and subtropical regions of the world. The plant’s seeds are surrounded by white, fluffy “bolls” consisting mainly of cellulose, from which cotton threads are produced after a long and complex process.

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Brazil is the world’s fourth-largest cotton producer, and around seven percent of its planted area belongs to SLC Agrícola. The company is one of the country’s largest agricultural producers and has been growing cotton on the Brazilian savannah for more than 25 years. Its mission statement emphasizes sustainability, and it uses the latest technology to improve efficiency. For example, its cotton harvesting machines are equipped with sensors that record georeferenced productivity data, allowing crop production to be visualized on harvest maps.

Once harvested, the cotton bolls are processed in cotton mills on SLC Agrícola’s farms. Samples are first subjected to fiber quality analysis in a laboratory to ascertain their characteristics, including length and resistance. Then, the bolls are stored in bales before being transported to foreign and domestic markets, where they are spun into yarn.

One key step in the process is drying the cotton bolls after harvest, which is essential for the quality of the final product. At SLC Agrícola’s farms, there were issues around their drying technology, leading the company to call Güntner for help. Thainã Garcia, Güntner’s EPC Sales Manager in Brazil, arranged a technical visit, where he could identify points for improvement and adjustments that could be made to increase the efficiency of the process.

“Their heat exchangers just weren’t giving them the performance they required,” explains Garcia. “One reason was that they hadn’t taken into account the amount of particles in the air, so the heat exchangers were getting blocked, and the team was spending hours cleaning them every week. They also hadn’t properly calculated the total air flow available throughout their ventilation systems, and so hadn’t allowed for the pressure drops the fans experienced.”

Garcia says that at one of the farms, for example, the customer had a heat exchanger that heated 572,098ft³/h of air to 113°F, while in fact, the requirement was for 2,118,880ft³/h of air at 149°F.

“The customer didn’t know how to do the calculations, so I gave him my support. I verified that he needed a new heat exchanger that provided an airflow almost four times greater and that generated air that was 68°F warmer.”
THAINÃ GARCIA EPC SALES MANAGER, GÜNTNER

In addition to resolving efficiency issues, Garcia also proposed a solution to solve the issue of the heat exchangers getting blocked: increasing the spacing between the tubes and the fins, resulting in far less need to clean the equipment.

In total, ten new Güntner Air Cooler Coils were installed across six different farms belonging to SLC Agrícola. All were individually customized with different dimensions and fixing points because each farm had them installed in different ways, some horizontally, some vertically, and others inside boxes. All were designed for maximum efficiency in the drying process. And three years later, that’s exactly what they continue to provide.

“Today, the heat exchangers are still operating perfectly, and the drying process has improved significantly,” says Garcia. And the customer has been impressed by Güntner’s expertise.

“The equipment designed by Güntner has greatly improved our system. Because of its quality and performance, Güntner is the heat exchanger company we want to use for all our needs at SLC from now on.”
JOSÉ VALMIR DE SOUZA REGIONAL COORDINATOR, SLC AGRÍCOLA