• Installing Tekleen filters in three lines in Grain Processing Corp.'s Washington, IN, plant eliminated particulate buildup and the need to shut down equipment for maintenance
Boosting plant profitability requires getting every possible use out of raw materials and finding new markets for them. The primary material for Grain Processing Corp. (GPC) is simple -- corn -- but the array of products it produces would make George Washington Carver, the agricultural chemist who found over 300 uses for peanuts, proud.
GPC makes cornstarches for food additives; grain alcohol for beverages and industrial applications; ingredients for pharmaceutical and beauty products; animal feed; super absorbent polymers for aqueous solutions; and deicing products. Recently, it even launched its own line of cat litter. The company has its headquarters, research and development, and main production facility in Muscatine, IA. It also owns a secondary production facility in Washington, IN, which makes grain alcohol, cornstarch and feed byproducts. It uses self-cleaning Tekleen filters from Automatic Filters Inc. to keep those plants running smoothly.
"We use the filters in the feed and milling area where we bring the corn in and do all the separation," says maintenance supervisor Derrick Biggs, who works at the Indiana facility. "Our main goal is to get the corn starch out, convert the starch to sugar and the sugar to alcohol."
Losing Heat
GPC takes corn, extracts the starch, and then converts that starch into sugar and finally alcohol. The process starts by milling the corn and then steeping it in 125ºF water. The starch transfers to the water, forming a thick liquid. Cloth filters are used to separate the bulk of the corn solids from this water/starch mix. To cut plant power costs, the water would pass through heat recovery exchangers, before proceeding though the other plant processes.
Biggs started using the Tekleen filters to address the problem of solids in the process water used for steeping the corn. These solids ran as high as 12%, clogging heat recovery exchangers. The heat exchangers help the plant cut its power costs, but only as long as the water could move freely through them. As the solids built up, the heat exchangers would have to be pulled off line every two to four months for cleaning. The task would take a maintenance crew several days to complete. GPC tried some cartridge filters, but they needed frequent cleaning; so it decided to experiment with self-cleaning filters instead.
"We looked at filters from a couple of manufacturers," says Biggs. "We found we could get better cooperation and service with Tekleen."
Self Cleaning
These filters incorporate a unique self-cleaning mechanism that allows an uninterrupted flow of filtered water even while the cleaning takes place. The procedure also uses a fraction of the water that normal back-flushing requires. They also use stainless steel as the standard.
In this design, dirty water flows in around the outside of a coarse filter that removes the larger particles. This prefiltered water then flows to the other end of the filter housing where it passes from the inside to the outside of the final filter and then through the outlet. Over time, as the filter removes particles from the water, those particles clog the filter, reducing water flow and water pressure. At the outlet is an adjustable pressure differential switch, typically set at five to seven pounds. When that threshold is crossed, it opens a small flush valve which initiates the cleaning procedure.
Rather than taking the full water flow to initiate a complete backwash, the new filters have a number of small cleaning nozzles arrayed around a central shaft. Opening the flush valve lowers the water pressure within the cleaning unit, and the nozzles vacuum the dirt from the inside surface of the filter screen. A hydraulic motor and piston cause the nozzles to rotate and move axially in order to cover the entire screen surface in five to ten seconds. At that point the flush valve closes and the cleaning mechanism returns to its starting position. Other than a small control voltage for the differential pressure sensor and to actuate the flush valve, all actions involved in cleaning the filter are performed using water pressure.
Finding New Uses
Biggs started experimenting with the filters on one of the heat recovery exchangers and, after they had proven their value, installed a filter on a second one.
"They definitely saved us a lot of manpower in cleaning the heat exchangers and replacing gaskets," he says. "The gaskets are extremely, extremely expensive and every time you take the heat exchangers apart, you most likely have to replace them."
From there, he started using them on a cloth wash system, which uses rotary vacuum drum filters. Particulates were clogging the nozzles in the cloth wash, requiring the operators to go in and unplug them. By using these filters, the nozzles stayed open and the cloth wash did a better job, allowing them to get more capacity out of each cloth.
Biggs reports that he now has four filters in use and, based on success at the Indiana facility, GPC also started using them at its main facility in Iowa. And that's just the beginning.
"The Tekleen filters have performed beautifully and we will continue to find new uses for them," says Biggs. IWW
Tekleen filters are manufactured by Automatic Filters Inc., of Los Angeles. Contact: 310-839-2828 or www.tekleen.com.
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