Leak in the vaccum system result in an increased heat load. WHY?
Articles about thermal fluid systems often start with a variation of the statement that “thermal fluid systems typically require little ongoing maintenance for the first few years of operation” and then go on to extol the various advantages of indirect thermal-fluid process heating over competitive heating methods, such as direct heat, steam and so on. The corollary to that statement, however, is that by the time there is a problem, the operating personnel that were trained on the system have moved on, been excessed or promoted. As a result, when things do go wrong, the guessing begins. And, unless there is an obvious cause like a geyser from the expansion-tank vent or a pump that sounds like it’s moving ball bearings, someone will likely blame the thermal fluid for the problem. There are several problems that seem to occur with some frequency. This article reviews a number of real examples and describes how the symptoms can be misinterpreted. The suspected fluid properties and the testing procedures necessary to determine which of the fluid properties (if any) is responsible for the problem are examined. Finally, recommended corrective actions are proposed.
VACCUM REACTORS TAKING TOO LONG TO HEAT?
The following is an example to find out what resulted in an increased heat load required for distilling the product.
EXAMPLE: A chemical plant requested a sample kit to test its thermal fluid because one of its vacuum
reactors was taking too long to heat.
Even though the fluid had been in the
system for many years and had recently been tested, it was assumed that
the fluid must have gone “bad”. This
situation is probably one of the more
common scenarios for heat transfer
systems. The problem comes to light
when someone realizes that the heater
temperature has to be increased to
keep production on schedule. In this
case, the evidence against the fluid
was further strengthened by the relatively “normal” heater pressure and
temperature readings. This prompted
the request for the sample kit and a
quotation for a complete fluid changeout. While the latter course of action is
appealing to the fluid supplier, it was
unlikely to solve the problem since the
problem wasn’t the fluid.
The overriding evidence in this
specific situation was that there had
been no maintenance required on
the system since the fluid had been
tested. Fluid had not been removed
or added (which eliminates contamination as a suspect) nor had any of
the operating conditions changed. It
turned out that there was a leak in the vacuum system, undetected by a
faulty sensor, which resulted in an
increased heat load required for distilling the product.
Author Jim Oetinger is the director of technology at Paratherm Corp. (4 Portland Rd., West Conshohocken, PA 19428; Phone: 800-222-3611, Fax: 610-941-9191; Website: www. paratherm.com). He has over 30 years experience in the chemical and plastics indus- tries. He has been involved with a wide range of products and processes including pig- ments, refrigerants, consumer plastic recycling, polymer compounding, process instrumentation and spray dried polymers. In addition, Oetinger has over 20 years experience in sales, marketing, and technical support of thermal fluids. He has authored articles on thermal fluid and system troubleshooting for this and other publications. A member of the Delaware Valley Chapter of the AIChE, he holds a B.S.Ch.E. from Clarkson University and a Masters of Management degree from Northwestern University. Oetinger and his family reside in a suburb of Philadelphia, Pa.
content and image courtesy:www.paratherm.com