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Popcorn Ash “Plugging” Catalyst Replacement Models

Coal-fired power generating stations are increasingly aware of popcorn ash “plugging” their SCR catalysts, and thus, their catalyst lifecycle replacement models as well. Although experts from SCR catalyst manufacturers rarely predict significant plugging of the catalyst face from LPA or popcorn ash in the design stage of a SCR retrofit project, all too often a mid season inspection reveals an unexpected popcorn ash problem and the need to replace catalyst prematurely. Utility project planners report that the catalyst plugging also “plugs” their economic models designed to predict catalyst life cycles and associated replacement costs. “We never built a catalyst plugging scenario potential into our lifecycle model,” reports a utility vice president. “We were forced to replace a tier of catalyst in half its life expectancy at a 33% cost overrun.” Several coal-fired power generators have attempted to address this problem by installing various derivations of woven wire mesh screens upstream of the AIG system to filter out the LPA. At first, they generally report that their SCR catalyst is operating more effectively; however, over time, the high temperature and erosive properties of the LPA tend to erode the screen mesh, often in less than one ozone season. In order to address this problem, Integrated Global Services designed a patent-pending high temperature erosion resistant material that could greatly extend the life of the filtration system. Moreover, given the limitations of woven wire mesh, IGS introduced an advanced perforated plate material and supportive housing elements that, combined, significantly outlast any other available LPA filtration system in the marketplace today. The resultant system, NoNOx Components™, has emerged as the most trusted, premium quality LPA system in the world. With over 50 successful SCR installations in the U.S. and Europe, IGS offers full scale design, modeling, manufacturing, and installation capabilities, and guarantees system longevity and performance with a long term warranty program. As such, SCR system designers and owners can be reassured of their catalyst lifecycle assumptions. NoNOx Components™ represents yet another example of how IGS has increased the reliability of mission critical equipment.

Automated Pulse-Mig Overlay Protects Boiler Nose Arch

IGS recently performed automated weld overlay on the nose arch of a large power utility’s Units 1 & 2, 640mw Foster Wheeler boilers. Unit 1 was accomplished in the fall. The quality of the work was at a level that we were the preferred vendor for the work on Unit 2 in the spring. The plant identified wastage from soot blower erosion in a 550 sf area within each unit. Tube thickness was between .140 and .200. The material of choice was ER70S-6 carbon steel. With previous vendors, the plant had experienced tube panel warping; thus it was critical for IGS to minimize heat transfer to the tubes. No water was in the tubes at the time of application. Working conditions were difficult at best, with the arch at a 45 degree angle and continuously falling fly ash from overhanging pendants. IGS successfully completed the project with no safety incidents, 90-100 mils of overlay with a single pass, zero blow-throughs, and no leaks upon start-up. For more information on IGS’ services to the Fossil Power market, click here.

Combined On-Site Metalspray and Overlay Protects PC-Fired Boiler

Recently, IGS provided surface protection for a large utility with a 265 MW CE coal-fired boiler with Low Nox Burners and SOFA. The varying wastage rates in the different areas of the boiler, mix of erosion and corrosion issues, and previous poor performance of the existing thermalspray coating lent itself well to an IGS turnkey surface protection project. As a result, we executed automated pulse-mig welding on the boiler floor and provided Metalspray™ on the furnace walls. Previous 888 thermal spray coating applied in the past was spalling on the floor sections. IGS stripped the old coating and applied 800 sf of Inconel 622 weld overlay. Additionally, we provided a Metalspray™ coating to protect the furnace walls from reduced atmosphere corrosion. IGS successfully performed all necessary applications without any safety incidents and reduced the number of contractors with a multidisciplinary approach. For more information on IGS’ services to the Fossil Power market, click here

IGS Mechanical Group Replaces Air Preheater Baskets, Seals, and SCR Catalyst Modules

Recently, IGS’s non-union Mechanical group performed a change-out of the boiler air preheater baskets and the top layer of SCR catalyst at a coal-fired power plant. The company rotated the air preheater, replaced 96 hot end baskets, 144 cold end baskets, and radial seals in a Ljungstrom 26.5 – V152 air preheater. Two 10 man crews were utilized for this project, working two shifts per day, and at the 64 foot elevation. Concurrently, IGS replaced the top 36 module layer of Babcock Hitachi SCR catalyst. The modules weighed 2,700 lbs with dimensions of 6’2” x 3’1” x 4’7”. All work was performed at the 94 foot elevation by two 8 man crews working two shifts per day. IGS employed a dedicated safety manager for each shift. The plant’s engineering manager commented: “All of the work was done in a safe and environmentally sound manner. The SCR catalyst work was accomplished in record time, requiring only six days of around-the-clock effort (versus previous timeframes of at least ten days). We highly recommend IGS for this type of hoisting and rigging work, and we hope to have them return in the near future.”