IMEC cooling and energy recovery systems produce $200,000 rebate.

July 2010
NuWay Tobacco in South Windsor, CT is reaping the financial benefit of working with IMEC's mechanical engineers. The tobacco processing company hired IMEC to design an energy-efficient plant cooling system that ultimately qualified for a $200,000 utility rebate, while producing approximately $53,000 per year in ongoing energy savings.

The chiller and pump package design provides 60 tons of cooling at a 45 degree supply temperature in NuWay’s plant. The water-cooled chilled water system is designed to handle the existing chilled water load.

The cooling tower system is designed to meet the needs of four casting lines, one existing refiner cooling tank, one future refiner tank, a water cooled chiller, and any other future small miscellaneous cooling needs. The tower system will provide 1500 gallons per minute of 85°F process water on an Ashrae 1% design condition of 75°F wet bulb.

Innovative features include a cold water bypass on the cooling skid. This valve remains open and allows the return water from the process to bypass the tower. This allows the water to warm up to the designed temperature assuring that there is precise control of the supply. As the water warms, this valve closes, diverting the return water to the cooling tower for cooling. A variable speed fan maintains the desired temperature. A variable speed pump drive incorporated on the skid adjusts the pressure to the required set point. 

In addition, a new tower water feed and return system were installed. The feeds to each of the lines incorporates a pressure and temperature adjusting valve. Each line has its own temperature and pressure adjusting valves. A float sensor controls the variable speed drive return pump maintaining a constant level.  This eliminates the need for balancing and extra pumps, resulting in less pump horsepower, greater power savings, and automatic level control.

The system allows NuWay facility management to set a precise temperature and pressure to the line.  It also allows the collection pans to drain into the collection tank. This constantly flushes the pan, reducing the build up of algae.

Key benefits of the prepackaged pumping station are:

• Energy Savings – The central VSD tower and VSD pumping system reduce the total fan and pump horsepower needed to provide the necessary cooling. The control system insures that fans and pumps consume the least amount of power possible.  The combination of the tower system and the new high efficiency water-cooled chiller and VSD chiller pump station package save approximately $53,000.00 per year over the previous chiller and tower systems. This system also qualified for a rebate from Northeast Utilities of  between $150,000-200,000.00.

• Improved Cleanliness – The tower water is continuously cleaned by a high efficiency stainless steel side stream filter. The “once through” nature of the design continually feeds the system with clean water. New return systems flush the basin, greatly reducing the growth of algae and bacteria.

• Automatic Temperature, Pressure and Level Control– The design eliminates the need to manually balance the feed and return water to control level, pressure and temperature. Temperature, spray pattern and water level are constant and consistent.

• Back Up – The chiller and tower water pump skid design incorporates automatic back up. In the event of a pump failure the system issues an alarm and automatically switches to a backup pump ensuring continuous flow.

• Integrated Package - The pumping station is a compact, integrated and skid mounted system complete with pump, motor control center, and system monitoring.  It requires a single point electrical connection minimizing installation time and reducing costs. All interconnecting plumbing is provided limiting on site connections to process feed, process return, tower feed, makeup water and drain. 

• Monitoring- The motor control center features a panel mounted main disconnect, and individual circuit breaker protection and motor drivers. The control panel incorporates audible and visual alarms (with remote capabilities) that alerts NuWay to problems in the system before production is affected. There is an adjustable high water temperature alarm that continually monitors the return temperature to the tank and issues an alarm when the water temperature reaches a predetermined set point. The panel also incorporates a low water level alarm and a pump failure alarm.  When any of these conditions occur, an alarm is activated.

For more information, please call 800-888-6554 or e-mail info@imec-us.com.