Ice Improves Industrial Utility Rates
-- Consulting-Specifying Engineer, 11/1/2000
When Interpolymer Corp. decided to locate its new manufacturing facility near Boston, the maker of polymer dispersions had to find a way to avoid demand charges of $24 per kW on peak and $12 per kW off peak. In developing a suitable mechanical system for the plant, the company found that the use of an ice thermal-storage system would bring electric costs in line with their operational and budgetary needs.
The system design incorporates two thermal-storage units, specially designed cooling towers and two 105-ton low-temperature reciprocating chillers. Ice is produced at night and in the early morning, and cold water is distributed from the storage units to two heat exchangers during the day for process refrigeration and comfort cooling.
The thermal-storage units feature a control mechanism that limits ice thickness and, therefore, the amount of ice generated to the required level for a given day's use. Typically, about 20 percent to 40 percent of capacity is made during winter months, as opposed to as much as 80 percent in the summer.
The company also employs a free-cooling cycle during colder months, allowing warm process water to circulate through the cooling tower to be chilled for use in the process-cooling loop.
For more information on the ice-storage systems employed in this project, circle 100 on page 91.
