Treatment of scaling problems in heat transfer oil systems
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The heat transfer oil system we are using at present has developed scale throughout the heater within less than half a year, which affects normal production. Heat transfer oil system process: WuLin brand 340 model heat transfer oil is used, with an operating temperature of 220 degrees; integrated control of heating and temperature regulation is employed. The heat transfer oil exits the hot oil tank, enters the hot oil pump, and then goes into the heater; after being used by the user. Back to the hot oil tank, which is equipped with a nitrogen protection system. There are temperature sensors at the heater outlet and inside, which adjust the heater’s operating mode through temperature control. The hot oil supply and return pipeline has a return system. 1 There will be no state of stagnation within the system. In other words, the hot oil does not remain stationary inside the heater, which prevents the hot oil from overheating ； 2 The quality of the heat transfer oil meets the standard requirements after analysis ； 3 The heater manufacturer is a legitimate one; similar heaters have been used in the past. We sought reasonable solutions from various aspects such as processes, equipment, and operations, as well as from design institutes and manufacturers, but were unable to find any. What causes the severe scaling problem?
1. The temperature control system of the heating furnace is inaccurate, resulting in localized overheating; it needs to be repaired. 2. It’s still a problem with the heat transfer oil – although the test results for different types of heat transfer oil are all satisfactory, their performance varies indeed
This post was last edited by netmoth on 2011-8-19 10:24. If scaling has occurred, why are all the test parameters still within the specified limits? This is contradictory~ Whether it’s the equipment, the design of the furnace pipelines or flow rates, or the quality of the heat transfer oil itself, testing the heat transfer oil provides the most direct indicator of the operating condition of the entire system (by examining the oil used in the system)
Reply to 2# a2963008000: It’s still the same even after changing the oil twice.
Reply to 3# netmoth: The analysis was conducted on new oil; old oil, of course, does not meet the standards. However, there is a batch of old oil that, despite having carbon deposits, still meets the specified criteria. It’s unclear whether there is an issue with the standard requirements for heat transfer oil itself.
1) From the perspective of \"heat transfer oil\": It is almost certain that the heat transfer oil used by the poster is a mineral-based heat transfer oil. Mineral-based heat transfer oil – derived from petroleum, a fraction separated in refineries. There are hundreds of components in petroleum, with the main ones being straight-chain alkanes and unsaturated hydrocarbons. The bond energies in their molecular structures are weak, allowing them to undergo cracking and recombination polymerization at high temperatures. This is especially true for unsaturated hydrocarbons (those containing one or more double bonds), which tend to form structural coking. Synthetic oil – artificially synthesized, it is used to produce substances with a stable structure and high bond energy for use as heat transfer fluids; as a result, it remains stable at high temperatures and does not easily undergo depolymerization, granting it a long service life. 2) It is difficult to determine whether the systems and equipment are reasonable and complete based on your brief description; if you wish, you can contact me directly. Perhaps I can help you analyze and find it.
Is it because the nitrogen seal isn’t tight enough, causing air leakage, and has the heat transfer oil been oxidized?
The area of our heater is 120 square meters. The operating temperature can reach up to 250 degrees, and after more than 4 years of use, the heating efficiency declines significantly. After testing, it is still within the normal range. Is there a better way to remove scale? We are using Fuquan SD series heat transfer oil.
There is a problem with the quality of the heat transfer oil; our heat transfer oil has not accumulated much scale after being in use for a year. It’s due to process-related factors – the flow rate of the heat transfer oil in the heating furnace is low, resulting in high local temperatures
The temperature control system is working fine, right!? Who checks the quality? Don’t trust tests easily
This situation is related to high-temperature oxidation; it is recommended to check the height and temperature of the expansion tank.