VACUUM CONVEYING PERKS UP COFFEE PRODUCTION
Café Soluble S.A., Managua, Nicaragua, was founded in 1958 to make and market instant coffee. By 1961, the company was exporting instant coffee and other coffees to markets in neighboring countries, North America, and Europe. Today, Café Soluble is an ISO 9000 company and leads the market for instant coffee in Central America, despite competition from well-known multinational corporations.
The company also supplies clients worldwide with instant coffee, traditional ground and roasted coffee, as well as coffee in bulk. Brands include Presto, Musun, and Café Toro. Café Soluble also processes private-label instant coffee for supermarkets in the UK and elsewhere, and it makes instant cereal drinks under the Presto brand. The company employs 400 people and has annual revenue of about US$34 million.
Record of strong growth
The election of a democratic governmentin 1990 - coupled with a strengthening Central American common marketrestored the companys freedom to grow. The company has since rebounded and has posted strong annual gains. From 1999 to 2000, the companys sales grew more than 23 percent, reaching US$28 million.
Roasted and ground coffee
Since its rebound, Café Soluble has upgraded several processes for making instant coffee, including the material handling and packaging operations. In 1995, the companys managers planned similar changes for making regular coffee. Rapid growth and the introduction of more coffees were making the operations a bit hectic.
Vacuum conveyors add flexibility that was impossible with mechanical conveyors.
We were doing everything by hand, including the batching, blending, and the intermediate steps, said Ernesto Hurtado, plant manager. I had an army of people moving boxes [of coffee] around. We grew so quickly that we couldnt handle all the material handling for doing the different blends of coffee. So we started looking for options.
Choosing the conveying method
Instead, Café Soluble turned to Vac-U-Max, a supplier of pneumatic conveying equipment based in Belleville, NJ USA. We purchased a complete packaging line for our instant coffee in 1992, and the filler was fed by a Vac-U-Max system, Hurtado said. So in 1995, when we had this need to move product quickly, we contacted them.
Compared with screw conveyors and bucket elevators, the suppliers pneumatic conveyors are very easy to move from here to there, Hurtado said. You just plug in your air connection, and youre ready to go. You just need suitable overhead support, and it can be as elegant or as crude as you like. You can even just hang it up with wires from the roof. Its a very flexible system.
The costs of installation and operation also favored pneumatic conveying. [Pneumatic conveying] was a little bit more expensive initially, but we are going to save a lot on installation costs, Hurtado said. We do the conveying and weighing in one operation, whereas if we used separate components, I would have had to buy the screw conveyors or bucket elevators from one source and the weighing equipment and the controllers from another source. Getting it all in one package was a great advantage cost-wise. On the batching system, we realized a big savings compared with a separate system.
The operation begins at the grinder, which discharges the ground coffee into small hoppers, each dedicated to a variety of coffee. As the coffee fills these hoppers, the vacuum receivers over the blenders generate negative pressure and pull the coffee from the various hoppers through conveying lines.
When the coffee reaches the end of the 10-meter conveying line, it fills a vacuum receiver until reaching the target weight. Typically, a vacuum receiver will pull 20 pounds (9 kilograms) of coffee from a hopper before discharging it to the blender below. By repeating the operation 16 times, the batch grows to 320 pounds (145 kilograms). A worker then makes minor additions by hand to finish the recipe, and the blender mixes that batch of coffee. As that blender operates, the other receiver is loading the second blender. This transforms a batch operation into a continuous one. One batching cycle loading, blending, and discharge takes about 15 minutes.
Automation eliminates an army of people moving boxes, says the plant manager.
After blending, the coffee discharges into a screw conveyor that feeds a bucket elevator. The bucket elevator carries the blended coffee to a floor-mounted silo that holds the coffee until its required at the packaging machines. When that time comes, the four vacuum receivers mounted on the packaging feed hoppers work in tandem to withdraw the coffee. It travels 10 meters vertically before discharging into the feed hoppers.
Level switches control the operation of the four vacuum receivers by signaling for more coffee when the level drops below a certain point. The switches also stop the vacuum receivers when the level in the hopper reaches the high set point. The coffee then flows to the vertical form-fill-seal packaging machines, each with four lanes. The machines package about 1,750 pounds (800 kilograms) of coffee an hour.
Better handling with fewer workers
The batching system gives precise control of coffee to the blenders, and the transportation and proportioning of it is all in one package, Hurtado said. Now I have a lot of flexibility. If we need more capacity, I can increase the weight per cycle. As long as I have ground coffee on top for feeding the grinders, [the vacuum receivers] will go on and on and on. We go 24 hours around the clock.
Before overhauling the operation, Café Soluble needed 40 workers over three shifts. It was because of all the handling, Hurtado said. They had to get it from the grinder discharge, then get it up to the blenders, then someone would have to carry that in boxes. Then from the discharge of the blenders, we had to feed the [packaging] machines by hand. So I used to have a lot of people moving boxes. Now Café Soluble needs only 12 workers over three shifts.
Furthermore, conveying the coffee pneumatically did not affect quality, such as from exposure to air. It hasnt been a concern, Hurtado said. We use pneumatic conveyors both for instant coffee and roasted and ground coffee. Ive never had a problem. In fact, Café Soluble strives to process the coffee quickly to minimize exposure to air. All our coffee is very fresh. We dont store more than 6 or 7 hours of freshly roasted coffee before we go to the grinders. Then, from the grinders to the packaging machines, the retention time in the silos and in the system is maybe 20 minutes. We dont store the coffee exposed for any extended period of time.
From a mechanical standpoint, there are no moving parts, except for a blower, which is very basic. I would say, in all confidence, that if you make the choice to use vacuum like we did, you have no worries.
Pneumatic conveyors and batch weighing systems: Vac-U-Max,
Belleville, NJ USA.
Reprinted From JulyAugust 2003 PBE International