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Oxygen Measurement Improves Efficiency and Product Quality in Cement and Lime Kilns

Oxygen Measurement Improves Efficiency and Product Quality in Cement and Lime Kilns
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Oxygen Measurement Improves Efficiency and Product Quality in Cement and Lime Kilns - 1

Cement & Lime Manufacturing Application Data Sheet Oxygen Measurement Improves Efficiency and Product Quality in Cement and Lime Kilns The measurement of oxygen (O2) inside a rotating kiln provides a good indication of combustion efficiency. This oxygen measurement can also provide an inferred indication of calcining rates and the production of thermal NOX . Maintaining a consistent oxygen level can prevent variations in product quality. at the end of a long probe, and use passive filters with no educator, sample pump, or other method of inducing flow into the analyzer. The flue gases simply diffuse into the sensing cell on the end of the probe, and the diffusion element filters last for many months. New Design Addresses Application Difficulties Getting an unbiased flue gas stream to measure is another challenge. While kilns will typically utilize “leaf seals” to minimize the amount of ambient air that gets drawn in between the rotating kiln and the stationary feed box, some upwards biasing of the flue gas O2 levels is usually observed, depending on the quality and age of the seals. There are a couple of methods of minimizing this biasing of “tramp air”: The zirconium oxide (ZrO2)measurement technology has become the standard for measuring oxygen in any combustion processes. A measurement accuracy of +/- .05 % O2 is achievable, and the sensing cells are very robust. However, some application difficulties hamper getting a suitable measurement of oxygen in a rotating kiln. Particulate The flue gas exiting from the kiln presents the best opportunity for measuring oxygen, but heavy particulate levels prevent the use of extractive methods without extensive filtering and sample conditioning systems, and the associated high maintenance required of such systems. In Situ O2 probes place the sensing cell 1. Testing with a portable analyzer and long sample probe to discern the “core” of the flue gas flow, ie. area inside the flue gas ductwork exiting the kiln where the oxygen least affected by the tramp air. 2. Utilize a long in situ probe, angled past the rotating seal. See figure 2. Figure 1- Proper installation of an oxygen probe in a rotating cement kiln Limestone Feed Oxygen Probe installation (shown with out protective jacket) Firing Direction Product Flow Rotating Leaf Seal

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Oxygen Measurement Improves Efficiency and Product Quality in Cement and Lime Kilns - 2

Cement & Lime Manufacturing Figure 2 - Rotating Kiln Figure 4 - View from inside of kiln, a long In Situ O2 probe inside an abrasive shield, being supported by the limestone feed tube 12' long in situ probe inside abrasive shield supported by feed tube. Limestone feed tube Leaf Seals Rotating Kiln Figure 3 - Long probe inserted down through feed box Addressing upset conditions Kilns may burn multiple fuels and/or hazardous waste, and the BTU input at the burner may vary from time to time, causing temperature excursions above normal operation. Rosemount Analytical’s Xi electronics permits...

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Oxygen Measurement Improves Efficiency and Product Quality in Cement and Lime Kilns - 3

Cement & Lime Manufacturing Figure 5 - In Situ O2 probe inside a protective “Probe Mounting Jacket”. 1100 °C (2000 °F) maximum flue gas temperature 10'' 150# ANSI Flange 1/4'' Blow Back

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Oxygen Measurement Improves Efficiency and Product Quality in Cement and Lime Kilns - 4

Cement & Lime Manufacturing www.RosemountAnalytical.com www.analyticexpert.com Emerson Process Management Rosemount Analytical Inc. Analytical Center of Excellence 6565P Davis Industrial Parkway Solon, OH 44139 USA T +1 440 914 1261 Toll Free in US and Canada +1 855 724 2638 F +1 440 914 1262 US Response Center 800 654 7768 gas.csc@emerson.com ©2014 Emerson Process Management. All rights reserved. The Emerson logo is a trademark and service mark of Emerson Electric Co. Rosemount Analytical is a mark of one of the Emerson Process Management family of companies. All other marks are the...

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