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Controlling Process Temperature

October 13, 2000

Controlling process temperature ensures product uniformity and integrity. Temperature control systems and chillers are used where tight temperature control of the process is critical. Processes requiring heating and chilling can combine a circulating water temperature control system and a portable chiller to provide single- or multiple-zone control.

Circulating Water Temperature Control

Hydrotherm is designed to provide accurate process temperature control in a 2 ft2 footprint. Standard features include 9 kW heating capacity; 3/4 hp motor; 25 gal/min and up to 40 psi pumping capacity; microprocessor-based controller; and 250°F (121°C) maximum operating temperature. Stainless steel, hydroformed pump is designed to ensure less thinning of material. From Mokon Div., Protective Closures Co. Inc., the temperature control system employs nonferrous construction and has indicating lights for need of operator, suction and discharge gauge.

Space-Saving Chiller Package

Offered in cooling capacities from 810 to 5,045 W, the Merlin Series from Neslab Instruments Inc. provides cooling in a space-saving package. Features include an easy-view fluid reservoir, reservoir drain for quick fluid changes, and integrated fluid pressure reducer/flow controller. Several user interface features are available, including high and low temperature safeties, audible alarm, computer control and stability to I0.1°C.

Temperature Control System

Tri-Temp from Advantage Engineering Inc. can provide up to three independent process water temperatures from 30 to 250°F (0 to 121°C). The portable system has a single chilled water circuit and two heating circuits. The chilled water circuit uses an internal water reservoir. Cooling circuits are available with 1.5 to 40 tons of chilled water capacity and with 0.75 to 5 hp pumps. Heating circuits are available with heaters from 4.5 to 36 kW and with pumps from 0.5 to 7.5 hp.

Chiller Has Communication Protocol

Kodiak recirculating chiller from Lytron contains an ozone-friendly refrigeration system with hot gas bypass. Its RS232 communication protocol allows for remote monitoring and chiller control. OEMs can collect chiller data on a system's host computer and review it remotely to analyze operating trends, troubleshoot or diagnose difficulties. The communication protocol sends and controls chiller parameters. It is available with cooling capacities of 600, 1,100, 2,200 and 4,500 W and with a variety of electrical, pump and controller options.

Rack-Mount Chiller

RK-19 replaces tap water usage in water-cooled equipment. From Tek-Temp Instruments Inc., the chiller provides 2,500 BTU/hr (733 W) of cooling. The air-cooled model utilizes a CFC-free, ozone-protective refrigeration system with hot gas bypass to maintain stability to I0.1°C over the coolant temperature control range of 41 to 95°F (5 to 35°C). Microprocessor-based controller provides simultaneous display of process temperature and setpoint. To facilitate computer control and datalogging, the unit can be equipped with an RS485 communications interface.

Small Footprint Chiller

Chiller's Cool Command microprocessor-controlled refrigeration technology provides energy efficiency and improved compressor life. Chiller from PolyScience offers temperature ranges from 5 to 176°F (-15 to 80°C) and up to 10,000 BTUs. A choice of pumps is available to satisfy a range of applications.

Temperature Application Heater/Chiller

Model PWG-060K-BE27CBC from Affinity Inc. has 1 kW of cooling capacity at a setpoint of -40°F (-40°C) and a heating capacity of 2 kW. Process coolant temperature range is -40 to 248°F (-40 to 120°C). System has hard-plumbed stainless steel coolant loop, sealed stainless steel reservoir with sealed top, and magnetically driven sealless pump for specialty heat transfer fluids. The unit is operated with a non-ozone-depleting HFC refrigerant and is CE marked. Standard features include a digital controller; interlock for flow, temperature and coolant supply level; and coolant pressure gauge.

Hot Oil Control Unit

Thermal VAC negative-pressure temperature control unit provides continuous production even under demanding conditions. From Budzar Industries Inc., the controller has a maximum temperature of 400°F (204°C) and is available in heater sizes up to 24 kW and oil-flow rates to 30 gal/min. A low pressure centrifugal pump delivers oil to the process, and an onboard vacuum pump draws oil through the process under negative pressure. If a leak develops, air is sucked in instead of hot oil being forced out, allowing the process to continue running under negative pressure until an opportune stopping point arises.

Nonferrous Temperature Control Unit

From Cooling Technology Inc., Century Series has a one-touch pad display, PID temperature controller and a10.5 x 19" footprint. The unit maintains temperatures to within +1°F. Features include one-button startup and automatic removal of entrapped air. Its two-tone, powder-coated cabinet drawer design allows access inside the unit while connected to process equipment. Separate electronics bay is removable for additional access.

Water-Cooled Chiller

TXW Series central chiller from Thermal Care Inc. is available from 82 to 127 hp. Chiller incorporates rotary screw compressors, Allen-Bradley PLC with color touch-screen interface, electric water-regulating valves, encapsulated refrigerant safeties, NEMA 4 control panels and PLC control capability of remote pump system.

High Temperature Control Unit

Designed for processes requiring 0 to 550°F (-17 to 288°C), Royal Series is available with 12 to 24 kW heaters and 1 and 2 hp positive-displacement pumps that are capable of reverse to evacuate the process. From Sterlco, a division of Sterling Inc., the midsize system includes the company's M2B fuzzy-logic control; displays setpoint and process temperatures simultaneously; and has half- and full-heat capabilities.