Del Monte In Modesto, Calif. Benefits From Compu-NOx

When a Del Monte Foods plant operating in Modesto, Calif., was required to reduce NOx emissions to less than a limit of 30 parts per million (ppm) in the 1990s, several special considerations had to be made in order to meet the needs of its seasonal production schedule. Specifically, the boiler, with a 10:1 turndown target, would have to operate with a near full load for three months of the year, but less than 20,000 pounds per hour for re-manufacturing during the rest of the year.

One of several unique features included with the initial bid saved the plant from having to purchase and install a new 300-horsepower fan. Instead, Benz Air Engineering installed a 250-horsepower variable speed drive to control an existing combustion air fan. It also added a 5-horsepower flue gas recirculation fan, which was also controlled by a variable speed drive. These solutions better met the needs of the plant. And, since the 250-horsepower fan operated at less than 400 watts of power, it is estimated the variable fan solution saved as much as $7,000 per month.

There were several other breakthroughs provided by Benz Air with its Compu-NOx solution. For example, Del Monte Foods' initial turndown requirement was 10:1, but the Compu-NOx solution delivered a boiler turndown of 15:1 while maintaining very tight and responsive boiler controls. This, combined with a unique feedwater control that eliminated an old pneumatic control, enabled Benz Air to increase boiler efficiency that resulted in an estimated annual savings of $100,000 in natural gas.

Highlights from the Initial Retrofit

• Reduced NOx emissions to 22 ppm, well below the 30 ppm requirement.
• Reduced CO emissions to 50 ppm, well below the 400 ppm requirement.
• Increased efficiency to ensure low NOx and CO levels attained with .8% O2.
• Meet all emission requirements at full capacity, and with a 25:1 turndown.

Since the initial retrofit, Benz has returned to Del Monte Foods several times to help the plant meet new requirements. To date, Benz has assisted in increasing plant efficiency to greater than 93 percent, reducing NOx emissions to less than 6 ppm, and earning more than $265,000 in efficiency rebates.

Recognizing Heat As Energy Can Save Fuel

While most manufacturing operators understand that heat can be recovered from steam boiler blowdown to increase boiler efficiency and reduce fuel consumption, not every operator has considered the significant cost savings. In 2006, the U.S. Department of Energy (DOE) EERE released Steam Tip Sheet #10 to help manufacturers do exactly that.

The tip sheet estimates that a plant — where an 80 percent efficient produces 50,000 pounds per hour (lb/hr) of 150 pounds per square inch gauge (psig) steam, increasing its efficiency to 90 percent with a heat recovery system — could save $68,000 per year (assuming the 2006 fuel cost of $8.00 per million Btu). Benz Air Engineering solutions perform even better.

Case Study: A Condensing Heat Exchanger In Action

After evaluating the boilers at Del Monte Fruit Processing and Packaging Facility in Modesto, California, Benz Air Engineering recommended several improvements to two boilers that were operating at about 82 percent efficiency. One of these recommendations included the installation of a CondiMax Condensing Heat Exchanger, which converts previously wasted heat into energy.

The installation resulted in increased efficiency much higher than the DOE tip sheet. In fact, the heat exchanger reduced stack temperature to less than 100 degrees Fahrenheit while increasing boiler efficiency to greater than 94 percent. The installation also resulted in an energy efficiency rebate, which meant an immediate payback for the plant.

In November, Del Monte also received an award for its energy efficiency management program and sustainability efforts at its Modesto facility during the CMTA/Industrial Environmental Association/Chemical Industry Coalition of California’s Annual Environmental Summit. The two retrofitted boilers were highlighted for their ability to significantly reduce fuel consumption, NOx output, and wasted steam through recycling.

Del Monte Foods is one of the country's largest and most well known producers, distributors and marketers of premium quality, branded food and pet products for the U.S. retail market, generating more than $3.4 billion in net sales in fiscal 2007.

University of California, San Diego Benefits From Compu-NOx

When the University of California, San Diego needed to meet the San Diego Air Pollution District's emission limit of 30 parts per million (ppm) NOx for three identical Erie City "O" type boilers equipped with Erie Ring Burners with 40 hp blowers, it received bids from seven companies.

Benz Air Engineering delivered a winning retrofit bid that was $750,000 less than all other bids, bids which would have required replacing those burners with less efficient Low NOx burners. By awarding the bid to Benz Air Engineering, the Compu-NOx solution reduced fuel consumption as well as NOx and CO emissions with a lower investment. Here's how the Compu-NOx retrofit solution stacked up:

Before Retrofit
Turndown: 3:1
NOx at Full Load: 80 ppm at 3 percent O2
CO at Full Load: 100 ppm at 3 percent O2
O2 at Full Load: 3.5 percent
Horsepower: 30hp

After Retrofit
Turndown: 20:1
NOx at Full Load: 16 ppm at 3 percent O2
CO at Full Load: 10 ppm at 3 percent O2
O2 at Full Load: 0.9 percent
Horsepower: 10hp

The Compu-NOx solution delivered an annual fuel savings of $58,000 per year and an annual electrical savings of $40,000 per year at the time of the retrofit. With the rising costs of fuel, the annual cost savings is now considerably more.

Since, the University of California, San Diego became the first campus on the West Coast to join the Chicago Climate Exchange to reduce emissions of greenhouse gases. It was also the first university in California to have been recognized by the California Climate Action Registry as a "Climate Action Leader."

UC San Diego's goal is to become a living laboratory for climate solutions by being an early adopter of real-world tools and leading-edge technologies for San Diego and the global marketplace for successfully measuring, certifying and reporting its greenhouse gas emissions to the Registry and the public. For more information about its sustainability programs, visit here.