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As much as we've all heard about carbon footprints, few of us know about water footprints. In addition to the regular water we associate with food and beverages, there is something called "virtual water." That's the water it actually takes to manufacture or grow something to the point where we use it, eat it, wear it or do something else with it. Check out the blog to read more.
The American Standard, ASTM D 5364, “Standard Guide for Design, Fabrication and Erection of Fiberglass Reinforced Plastics Chimney Liners for Coal Fired Units” requires that the lowest ovalling frequency of a fiberglass reinforced plastic chimney liner shall not be less than 2Hz. From engineering practices and numerical experiments, the authors find that the frequency calculated in accordance with ASTM D 5364 deviates considerably from results using FEA. A modified equation has been proposed in this paper to better evaluate the lowest ovalling frequency for FRP chimney liners.
The major function of an FRP liner is to protect the outer shell from the thermal, chemical and abrasive environment of the hot boiler gases. One of the design concerns is to minimize the ovalling due to pressure fluctuations. Gas turbulence has been observed to cause liner ovalling on at least two occasions1. However, the number of variables influencing modes of vibration and the unknowns associated with gas flow makes it extremely difficult to formulate a precise solution to ensure that ovalling will not occur. To avoid resonance when the frequency of gas turbulence matches the liner’s natural frequency of vibration2, ASTM D 53643 recommends a minimum criteria of 2 Hz for the lowest ovalling frequency. Meanwhile, it also provides two equations to calculate the lowest ovalling frequency for an unstiffened liner in Section 188.8.131.52, and a stiffened liner with ring stiffeners in Section 184.108.40.206. A review has been conducted using Finite Element Analysis (FEA) of 10 chimney liners similar to projects previously completed.
Ovalling due to gas turbulence is a design concern for FRP chimney liners. To avoid liner ovalling vibration which could lead to premature failure, ASTM D 5364 provides a lowest ovalling frequency requirement and two equations to predict the frequencies for unstiffened liners and stiffened liners. However, both equations are based on an idealized liner arrangement. The lowest ovalling frequency prediction in accordance with ASTM D 5364 considerably deviates from the FEA modal analysis results. The unstiffened liner frequency equation in ASTM D 5364 is applicable for liners with no circumferential restraints.
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ECTFE Fluoropolymers in Dual Laminates
Presented by Michael Krauss at the 2nd Annual Plant Engineer’s FRP Forum. Michael is the VP of Concrete Protection and Semi-Finished Products at AGRU America, and his presentation is on ECTFE Fluoropolymers in Dual Laminates.