ESA-152-2 Public Report
Company Plant Product Cemex, Inc. Wampum, PA Cement ESA Dates ESA Type ESA Specialist 9/18/07 – 9/20/07 Compressed Air Kyle Harris
Introduction: CEMEX Inc. is the largest cement and ready mix company in the United States. In the United States alone, CEMEX Inc. has 14 cement plants, close to 50 distribution terminals, over 400 ready-mix plants and approximately 125 construction aggregates quarries. The United States Department of Energy (DOE) “Save Energy Now” program completed an Energy Savings Assessment (ESA) September 20, 2007 at the CEMEX Inc. facility in Wampum, Pennsylvania. The DOE Qualified Specialist/Energy Expert conducting the compressed air system ESA was Kyle Harris of Accurate Air Engineering, Inc., Bakersfield, California. The CEMEX, Wampum compressed air systems include fifteen rotary-screw air compressors operating in “satellite” locations serving a number of different end uses. The air compressors vary in size from 25 horsepower to 125 horsepower. The plant uses compressed air on a 52 week per year, 7 days a week, 24 hours per day schedule. Currently, the compressed air system uses over 9,360,000 kWh/year, accounts for over 8% of the total plant electricity consumption and is near 1% of the total plant energy consumption. Objective of ESA: Identify compressed air system improvement recommendations, train plant personnel how to correctly model the current system and predict potential savings using the DOE AIRMaster+ software tool. Focus of Assessment: Compressed air supply, distribution and end uses. Approach for ESA: Amp data was collected on fifteen air compressors. Together, the DOE ESA Expert and plant personnel used LogTool V2 to interpret the data and format the data for direct import into AIRMaster+. Compressor profiles were developed and a baseline compressed air profile was created within AIRMaster+. A survey of the compressed air supply and demand was completed. As part of the “training assessment” the plant personnel, with direction from the DOE ESA Expert, created a number of energy efficient measures to evaluate the impacts of each measure. Ultimately, these measures were prioritized in order to achieve the best effect of the improvements. A closeout meeting was conducted to present the findings to a number of plant personnel that may be affected by the proposed improvements. General Observations of Potential Opportunities: The following section briefly discusses the projects identified for additional investigation or implementation. A qualifier is assigned to each project – near-term, medium-term or long-term. These descriptors are identified as follows: Near-term opportunities would include actions that could be taken as improvements in operating practices, maintenance of equipment or relatively low cost actions or equipment purchases. Medium-term opportunities would require purchase of additional equipment and/or changes in the system. It would be necessary to carryout further engineering and return on investment analysis. ESA-152-2, Cemex, Inc. – Wampum, PA, Plant Public Report
Long-term opportunities would require testing of new technology and confirmation of performance of these technologies under the plant operating conditions with economic justification to meet the corporate investment criteria.
Near-Term Opportunities
Supply Additional Kiln Atomization Air to Sonic Horn Compressor Currently, the average demand of the four “Kiln Atomization” 125 hp air compressors is 2,000 cfm or 84% of the total “Kiln Atomization” system capacity. The separate, single “Sonic Horn” 60 hp air compressor also operates at 84% of total capacity or 221 cfm. The “Kiln Atomization” is a critical application that requires a minimum of 95 psig. It is possible to add a single control valve and piping to maintain 95 psig for the “Kiln Atomization” and allow any additional compressed air to “spill” over to the “Sonic Horn” system. The “Sonic Horn” air compressor would be set up or modified so that it would start at a predetermined pressure (somewhere below 95 psig) and time out and stop at a predetermined higher pressure. The starting and stopping of the “Sonic Horn” air compressor would be a direct result of the demand on both systems. If, occasionally, the demand in the “Sonic Horn” system required more air than the “Kiln Atomization” system allowed to spill over, the 60 hp air compressor would automatically start, support the demand and when the pressure was satisfied, time out and shut down. All “Kiln Atomization” air compressors would operate at 100% load while the “Sonic Horn” air compressor would run load/no-load and off most of the time. It is also possible that this same solution could be carried over to the “BHA D/C” air compressor if the piping was extended to that portion of the air system. It is estimated that over 330,000 kWh annually could be saved with a payback ranging from 1.3 to 2.0 years. The atomization process and this measure may deserve more time and study in order to determine if an alternative technology is available (i.e. low pressure blowers, high pressure pumps) to effectively atomize the water for the kilns. This additional study alone could potentially save in excess of 3 million kWh annually if an alternative to compressed air was demonstrated.
Medium-Term Opportunities
Automate Air Compressors During the pre-ESA data logging and subsequent modeling in AIRMaster+, most of the air compressors operated in some state of modulation or part-load. Modulation, as discussed during the on-site activities, is the least efficient control method for part-load air compressors. It is recommended that the air compressors be automated so that an air compressor is 100% loaded or off. Any air compressor/s required for “trim” should be installed behind an intermediate control (i.e. demand expander, flow controller), control storage and operated loading and unloading. Preferably, most of the air compressors would be moved to a more central location where automation would be more effective. The new location/s for the “trim” air compressors should carefully planned so that the air compressors are installed in a cleaner environment saving not only energy but maintenance costs as well. Currently, most of the air compressors with exception of the “Kiln Atomization” air compressors are installed in very dirty environments where the life of the air compressor is diminished and energy costs are increased through dirty air filters and oil contamination. Assuming that the “Kiln Atomization” and “Sonic Horn” air compressors were modified, as discussed in the prior measure, the “Kiln Atomization” air compressors could be used as the “base-load” compressors for the new automated arrangement. The “trim” locations would be automated so that they were started and stopped in a logical sequence depending on the total plant compressed air demand. All current assets may be used to keep the initial project cost lower, but with more analysis new “base load” and/or “trim” air compressors may be a viable option. It is estimated by automating the system that over 1 million kWh annually could be saved with a payback ranging from 1.2 years to 2.0 years depending on the final arrangement.
Long-Term Opportunities
Other Opportunities Though air cannons and electric vibrators are currently in use at this plant, there are still opportunities to install the same technologies in other lancing and open-blowing applications. Time did not permit a detailed analysis of these applications. At the end of the ESA, it was recommended that the plant take advantage of
ESA-152-2, Cemex, Inc. – Wampum, PA, Plant Public Report
the current air cannon and electric vibrator application strategies, contact the manufacturers or representative and investigate the possibility of replicating these in other areas. Through the ESA AIRMaster+ training, plant personnel can now evaluate the impact of these potential improvements.
Management Support and Comments: Cemex, Inc. is dedicated to reducing energy consumption throughout its plants worldwide. Kyle Tingle and Jim Cameron provided support prior to the ESA commencing as well as during and after the ESA. They are dedicated to improve the compressed air system at the Wampum plant.
ESA-152-2, Cemex, Inc. – Wampum, PA, Plant Public Report