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Application Note: Compact heat exchanger and cooling tower combination stabilizes temperatures

August 10, 2015  

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When you picture the cooling systems used in the process industries, the first image that might come to mind is probably a cluster of massive cooling towers perched atop a refinery or chemical plant.
    But, Carl Pendola, P.E., says there is also a broad range of applications in the process industries that require more compact cooling systems.
 “There are many large processing plants that have remote satellite facilities, pilot plants or research operations that require smaller, independent cooling packages that could be well served by a combination of a compact, factory-assembled cooling tower plus a small-footprint, economical heat exchanger,” Pendola explains.
  A 35-year veteran in servicing the chemical, gas and oil processing industries, Pendola has been involved with equipment design and selection for many diverse applications, with specialties in heat transfer and mixing.
  A recent example is a custom, compact cooling system in which Pendola was involved. The application was a mud tank designed by NRG Manufacturing for R&D of down-hole drilling tools manufactured by a major oil services company. NRG is a manufacturer of custom pressure vessels, mud tanks, and well stimulation solutions, also known as FRAC equipment.
    Most NRG mud systems are mobile systems designed to mechanically remove destructive solids and sediment from drilling mud, resulting in fluid retention, reduced wear on equipment, more efficient mud agitation, efficient cleanout maintenance, and a safer work environment.
    However, this newly designed mud system for testing down-hole tools will accommodate a particularly abrasive mud and runs it through the tools for erosion testing and other wear factors.
    “Because some drilling fluids are very abrasive, heat can build quickly and controlling mud temperature becomes an issue,” explains Chris Post, NRG Director of Engineering and Projects for Pressure Vessels and Drilling Systems. “So, our customer asked us to incorporate a cooling system that would reduce and control the heat levels.”
    The system Post’s team designed was composed of a plate-type heat exchanger manufactured by Tranter plus a compact 265-ton cooling tower from Delta Cooling Towers.
    Tranter is a global supplier of plate, shell & plate and spiral heat exchangers that are well known for their efficiency and small footprint.
    Delta, which also serves international markets, is the manufacturer that first developed the engineered HDPE plastic cooling tower technology.
    As far as the specifications of the cooling system are concerned, Post says he was sure that a Tranter plate-type heat exchanger would do the job without taking up much space. He relied on Pendola’s firm, a Tranter sales agent, to specify the cooling tower.
    Pendola says that a Delta tower was the obvious solution for a number of reasons, including available sizes, an economical price and engineered HDPE (high-density polyethylene) construction. He points out that the dependable performance and minimal maintenance requirements has enabled this line of seamless, factory-assembled cooling towers to gain favor over the galvanized sheet metal models that once dominated the industry.
    “The engineered plastic is relatively impervious to corrosion from the environment, including ozone and the airborne contaminants that may be expelled from plants anywhere near the cooling tower installation,” Pendola says.
    “Areas with a fairly damp climate can lead to corrosion that will damage a galvanized cooling tower,” he adds. “So, many users want to get away from that problem and so they go with an HDPE cooling tower.
    Post adds that ease of installation of a factory-assembled cooling tower is another plus. “The crew that I had install the cooling tower were not experienced cooling tower hands,” he says. “But they were able to get the tower assembled rather easily. So I think this is another factor that bodes well for this model of cooling tower.”
    Integrating advanced resins and molding techniques, engineered-plastic cooling towers are now available in larger sizes and modular configurations that make them ideal for even higher-capacity applications (1,500 to 5,000 cooling tons) that traditionally depended on expensive field-constructed installations.
    He adds that the compact, modular Delta cooling towers save on energy and can give smaller industrial applications the opportunity to use a relatively small cooling tower when their needs are for relatively limited cooling capacity, then add cooling tower modules to the platform in order to boost cooling capacity as their needs grow.