Chemical Processing - July 2008 - (Page 39)

making it work steam projects provide Fast payback Louisiana petrochemical complex significantly cuts energy consumption By Jason W. Gathright, The Dow Chemical Co. An energy assessment at Dow Chemical’s St. Charles Operations in Hahnville, La., has led to a 272,000-million-Btu/yr reduction in natural gas use, providing $1.9 million in annual savings; costs to improve operations were paid back in about six weeks. The U.S. Department of Energy (DOE) has named the site a 2007 Energy Champion Plant, an honor given to the top energy savers in the country. The 2,000-acre St. Charles facility, which has been in operation since 1966, produces more than 40 different products and relies heavily on steam — for electricity generation and process duties. Dow has an active energy-management program which includes a corporate 2015 sustainability goal of reducing energy intensity by 25% from 2005 baseline; therefore we took advantage of a “Save Energy Now” assessment sponsored by DOE’s Industrial Technologies Program to gain insights on potential energy saving opportunities. A specialist qualified on DOE’s Steam System Assessment Tool (SSAT), Riyaz Papar of Hudson Technologies came to the site and worked with an empowered team comprised of plant operators and engineers. Once SSAT was installed on their computers, the team members modeled the facility and investigated a variety of what-if scenarios for energy savings. This led to the identification of both near- and medium-term opportunities, based on payback periods. Implementing all of these could result in a more than $5 million annual savings. neAr-term initiAtives several areas of the steam distribution network lacked sufficient insulation per Dow standards. Using 3EPlus, DOE’s insulation calculation program, the team estimated insulation losses to be about 1%, Reducing such losses to 0.1% promised savings in gas of more than 3,000 million Btu and $25,000 in costs. • Boosting condensate recovery. At the time of the assessment, Dow was recovering about half of the low pressure condensate. The SSAT indicated that a site-wide recovery rate of 75% was possible. This would cut gas use by nearly 88,000 million Btu and costs by almost $650,000. medium-term opportunities With the help of SSAT, the team pinpointed four efforts to undertake first: • Implementing a steam-trap repair project. An audit performed before the assessment had identified all failed steam traps. SSAT enabled us to quantify the value of implementing a repair program — annual savings exceeding 112,000 million Btu of natural gas and $880,000 in costs. • Upgrading the steam-leak management program. Initial estimates proved overly optimistic due to inaccurate measurements during data gathering. However, upon verifying the measurement system and performing quantitative analysis, the revised figures still pointed to savings greater than steam trap repair alone. • Improving insulation. Inspection revealed that The team also identified a number of other worthwhile projects that offered somewhat longer payback: • Adding a blowdown heat-recovery exchanger. Blowdown was going to a flash tank to recover low pressure steam but lots of thermal energy was still being lost. Putting in an exchanger upstream of the tank would enable capture of significant heat that could be used to preheat boiler makeup water. This would save about 31,000 million Btu of gas and $200,000. • Preheating reactor feed with 75-psig steam. Replacing some of the 600-psig steam being used wouldn’t save natural gas but would allow more on-site electricity generation from the higherpressure steam. This would reduce electricity purchases by almost 1,280 M Wh and nearly $80,000. 39 chemicalprocessing.com July 2008 http://chemicalprocessing.com

Table of Contents Feed for the Digital Edition of Chemical Processing - July 2008

Chemical Processing - July 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Who’s a Big Hit? Succeed with Condensate Control Take Some Basic Steps with pH Measurements Steam Projects Provide Fast Payback Process Puzzler Plant InSites Equipment & Services Product Spotlight/Classifieds/Ad-Lits Ad Index End Point

Chemical Processing - July 2008

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