|
Nov/Dec 2000
The following was reprinted in its entirety from Colourway Textile Journal, published by The Association of Thai Textile Bleaching Dyeing Printing and Finishing Industries.
Manufacturers are constantly searching for a low-cost alternative to chemically cleaning heat transfer systems containing degraded or contaminated heat transfer fluids. Deposits from these fluids foul the interior system, making cleaning necessary prior to changing the system with new fluid.
Thai Paipan Limited, a 25-year old textile printing business in Samutprakam Providence, Thailand, was using a mineral-based heat transfer fluid, which was changed out twice without cleaning the heat transfer system. Thai Paipan uses heat transfer fluid systems in the textile drying process. Printed fabric must be completely dry before it can be rolled and packed for local sale as well as for export.
Because Thai Paipan changed its heat transfer fluid without cleaning the system, sludge in the piping and degraded fluid began to obstruct the system's heat conductivity and operating efficiency. In addition, the high moisture content in the drain tank fluid was mixing with the fluid in the heat transfer system, thus negatively affecting the system's ability to transfer heat.
Thai Paipan noticed that it was taking longer each day for its system to heat up. Production began to decline; they were losing four working hours on the production line each day. Radiator tubes containing heat transfer fluid were leaking. Yields dropped during the unexpected shutdowns necessary to either repair or replace the tubes, and Quality Control was forced to recheck the textiles for defects.
Thai Paipan was aware of the drop in productivity and knew the problem had to be corrected, so they sent a sample of their heat transfer fluid to Solutia Inc., (St. Louis, Mo.), for a complimentary fluid analysis. Solutia is known as a reliable supplier of synthetic heat transfer fluid in the textile market. However, the company could not analyze the sample because the fluid had become solid at ambient temperatures. Solutia recommended that Thai Paipan replace their current heat transfer fluid immediately.
The issue Thai Paipan faced was how to replace the heat transfer fluid without completely disrupting production. If they choose to cool down the system to replace the fluid, the degraded fluid would likely become solid due to its high viscosity. Mechanical cleaning options would take longer than the five days. Thai Paipan was allowing for the process.
After considerable research, Thai Paipan decided that Solutia's Therminol FF, the first and only flushing fluid for liquid phase heat transfer systems, would shorten their cleaning time. "We knew that any residual Therminol FF in the system would be compatible with our new heat transfer fluid - Therminol 55, Solutia's moderate-temperature synthetic fluid," said Veeranan Chumanechot, Thai Paipan foreign factory manager. "Solutia even advised us how to fabricate the cold seal trap to prevent moisture from entering the system."
Thai Paipan was able to shut down for the flushing process during the five days of the Thai New Year. They first consulted with Solutia to develop a customized system cleaning procedure. This enable them to execute the flushing and refilling procedure without the added expense of outside contractors. The cleaning, refilling and startup process was completed in four days-one day less than Thai Paipan had anticipated.
Thai Paipan started the process by draining 1,200 liters of the degraded fluid out of the system and refilling it with 1,200 liters of Therminol FF to lower extreme viscosity. While the heater was shut down, the new fluid circulated for six hours at 70 degrees Celsius. The viscosity of the fluid mixture made it possible for the fluid to be drained at room temperature.
Using the gear pumps, the company next drained a total of 6,600 liters of fluid out of the heat transfer system. The drain tank then was refilled with 6,600 liters of Therminol FF before it was pumped into the system. The fluid as allowed to gradually heat up from ambient temperature to 180 degrees Celsius. The heater was turned off during the 12-hour circulation period. At 70 degrees Celsius, Thai Paipan began to drain the Therminol FF and drum it for resale as inexpensive fuel.
Thai Paipan also cleaned the expansion tank and the drain tank as well as changed the pump packing and gasket while the system was shut down. Finally, Therminol 55 was added to the system, which was restarted without any leakage.
"In the five months since cleaning our system with Therminol FF and switching to Therminol 55 heat transfer fluid, our production has increased by twenty percent," said Veeranan. "Thanks to Solutia and Therminol, we have not had any unexpected shutdowns."
|
