Duke

Duke's heating needs are supplied by a central steam plant.  The plant burns coal, recycled oil and natural gas.  During the 1990's, the plant's life was extended significantly through a series of upgrades and retrofits that improved the plant's efficiency and reduced its enviromental impact:

• Flue gas re-circulation (FGR) capital cost $781,000 with an average annual fuel savings $135,000/year. This project was completed in 98/99 and has reduced operating cost to date over $540,000 over This project also reduced our NOx 25 - 40%, carbon monoxide reduction 12%, and particulate reduction of 56%. The NOx reduction of up to 40% equals the equivalent of approximately 80 Million-passenger miles/year.

• Modernized the plant control system with off the shelf Sun Work stations reducing equipment down time and improving reliability. This project was done in the 97/98-budget year. Our return on investment is the added reliability and ease of maintenance.

• We added a steam plant central cooling tower in budget year 95/96 with a capital cost of $78,000. The project reduced our potable water use by 33% with a return on investment in 2.7 years. This project saves 10 Million gallons of water/year and reduced our water budget by $30,000 per year with a total savings to date of over $180,000.

• We recycle 7000 thousand tons of Fly ash into concrete block. There was no capital cost involved with this project that was done in 1996 but it has returned $234,000/year to our plant operations. The total savings to date are over 1.4 million-dollar and over 40,000 tons of ash not disposed of in our local landfill.

• Exhaust steam control strategy using low-pressure exhaust steam from turbines minimizing the need to vent LP steam.  LP steam is used in the Deaerator to remove oxygen from the boiler water and to preheat the combustion air for #6 Gas boiler resulting in an $45,000 annual savings. This project was completed in the 96/97-budget year.

• Mechanical Exhauster vacuum system removes ash from the boilers, eliminating the need for a steam energy source and replacing steam with a high efficiency 40HP motor.  There is a $190,000 annual savings in fuel and water cost associated with this project. This project was completed in the 95/96-budget year at a cost of just over $200,000 dollars with a 1.2-year payback.

• Variable frequency drive's (VFD'S) installed on two feedwater pumps and on three boiler ID fan's have produced a $44,286 annual electricity saving's. This project was completed in the 98/99-budget year.

• Installed a new coal car thawing system that prevents the need to use glycol to keep the coal from freezing in the rail cars.  The savings are over $12,000 annually for glycol.  We have also eliminated a safety problem for our work force. This project was completed in the 99/00-budget year.

• Duke Power standby generator program.  We sell a small amount of electric power at peak hours to Duke Power Co.  This program saves the Steam Plant over $14,000 annually.  Campus wide this program saves $132,000 annually.  This program was started in the 1990/91-budget year.

• Plant lighting improvements added light without increasing energy use.  This project was completed in the 99/00-budget year.

• Conversion of 3 boilers to accept No. 2 oil to provide flexibility and cost savings by eliminating the need to preheat #6 oil.  This project saved over $65,000/year in steam and electricity cost. This project was completed in the 96/97-budget year.

• The steam plant has implemented and automated a high-pressure steam trap program that has reduced our trap failure rate.  The use of Palm pilots prevent us from duplicating data input and reduced the time needed to find the traps by having a predetermined route for the mechanic.  About 60 High Pressure Steam Traps were found blowing in 1995.  This was about $45,000 worth of steam.  This was the beginning of our program. Since then, regular trap maintenance has greatly reduced the numbers of blowing traps.  The baseline is the $45,000 lost in 1995.  Since then, the loss has decreased dramatically.  The total savings to date is about $240,000.

• We have installed a preheat, pump and collection system to recover two million gallons of water from vacuum pump seals and HVAC condensers. This project saves FMD $4,652.00/year as well as 2,000,000 gallons of city water/year.  This project was completed in the 01/02 budget year.

• Duke University Steam Plant burns a special blend of recycled oils that is environmentally compatible to virgin #2 oil.  This oil has the same BTU value and sulfur content.  It is burned in two of our boilers that are used primarily for emergency steam recovery and load peaking.  We have up to 150,000 gal. of this oil stored on site at all times.    Annual savings for this project are determined by the amount of fuel oil we burn in any given year. The average annual savings are around $50,000. This project was completed in the 98/99-budget year.