The automated cement laboratory at Lehigh Cement Co.'s flagship Union Bridge, Md., plant is part of a recent modernization incorporating the latest technology for cement production, quality control, energy conservation, environmental protection, and worker safety. Owned by Heidelberg Cement of Germany, Allentown, Pa.-based Lehigh is affiliated with some of the world's most advanced cement operations and related construction materials activities. Staying abreast of latest technological developments, the company has served the construction industry in North America for more than 100 years, producing cements widely used by ready-mix concrete suppliers for highway, architectural, industrial and marine applications. In keeping with that tradition, the Union Bridge facility — touted as the largest and most modern in North America — boasts a clinker capacity of 2.0 million metric tons per year.

Busy cement manufacturers require automated cement labs working 24/7 to meet production demands. In addition to the rigors of constant operation, these labs must be able to handle running multiple samples simultaneously to ensure continuous process consistency within close tolerances. Consequently, when a European-made central vacuum system installed at the new Union Bridge cement lab to evacuate excess sample and clean equipment at various sampling locations failed to keep up with Lehigh's uptime requirements, another solution was needed.

A number of factors not fully considered when the dedusting system was originally specified were deemed vital to the upgrade. Vacuuming would have to accommodate as many as four or five stations open simultaneously, different types of materials being tested, and the heavy dust that is a byproduct of constant operation. Under such circumstances, velocity would have to be maintained in the system to prevent settling out of test material in the lab's piping; stations becoming caked; and, cross contamination at various critical points, skewing test results. In addition to reliable test measurements and continual uptime, the new technology would need to address worker safety and maintenance issues.

To meet these demands, Lehigh Cement Quality Control Manager Jeff Hook called on Dick Slechter of Gilro Associates, the Maryland Vac-U-Max representative. Hook explains, “With uptime the key to our cement production, the lab needed a vacuum system enabling it to maintain an unrelenting pace without losing any of its precision and accuracy.”

On site at Union Bridge, Slechter and a Vac-U-Max application engineer performed a thorough audit of the lab's dedusting system. By means of a Vac-U-Max demo truck equipped with a 15-hp portable vacuum unit, pickup points were found to be poorly designed. Along with various modifications recommended by the specialists, increasing air flow with a 20-hp, 700-cu-ft/min unit delivered the desired results. To save plant floor space while providing proper filtration, furthermore, a heavy-duty weather-resistant Vac-U-Max 2120 receiver was installed outside, using a positive displacement pump for greater durability under constant load than that offered by the usual regenerative blower.

The Vac-U-Max system provides direct dedusting and collection of debris into a 55-gal drum. Enabling such activity are a 36-in.-diam receiver with 230 square feet of filter area, comprising a cloth-to-air ratio less than 3:1 to minimize stress on the filters; and, 19 long-lasting PTFE-coated filters, effective to 1 micron, which are relatively inexpensive to replace. Additionally, the system features both continuous-pulse and off-line filter cleaning to accommodate its high-dust application; a severe-duty electric motor for continuous low maintenance and long service life; and, UV-resistant tubing and paint to protect outside parts from the elements.

“Installed in January, after a few minor adjustments, the system has been running problem-free ever since,” Hook reports. “Vac-U-Max has transformed our cement lab into a valuable asset, maximizing uptime and efficiency, while providing improved environmental conditions.”
— This article was adapted from materials supplied by Vac-U-Max, www.vac-u-max.com