The temperature of the heat transfer oil high-level tank is high

Is it in the normal operation phase? If it is running normally, it is possible that the auxiliary exhaust valve is not closed. Also, check whether the oil has been fully boiled and if there are any low-boiling substances left.

It is now operating normally. All auxiliary exhaust valves are closed. The temperature in the high-level tank is below 160°C, with a minimum of around 120°C; it fluctuates within this range

Our heat transfer oil outlet temperature is 240–260, while the return oil temperature is 190–235. The level in the high-level tank is 60–80; sometimes it can reach 100 as well. You must have other problems.

This post was last edited by 955559 on 2018-9-3 at 17:18. The heat transfer oil system is a relatively safe closed system that is quite common abroad. Due to various constraints in China, most heat transfer oil systems in use by enterprises here are of the open type. Since many operators in these enterprises do not have a thorough understanding of this system, improper operation often leads to numerous problems during its operation, such as severe coking within the system, a shortened lifespan for the heat transfer oil, and even fires in the system. These problems are likely caused by the failure to close the forced exhaust valve on the high-level tank; let’s analyze this together. Firstly, as the name implies, a forced exhaust valve is a valve used to release gases from the system. In China, water is used to pressurize new systems, but it’s impossible to completely remove all the water from the system; some water always remains. Therefore, heating is used to drive out this remaining water. When the temperature rises above 80°C, a large amount of water vapor is generated, and at this point it’s necessary to open the forced exhaust valve on the high-level tank in order to release the gases from the system. Additionally, when new oil is dehydrated, a small amount of water vapor along with many hydrogen compounds with low boiling points are produced, and again it’s necessary to use the forced exhaust valve on the high-level tank to quickly remove these gases. Once the system pressure stabilizes, the forced exhaust valve should be closed promptly to prevent the heat transfer oil in the high-level tank from overheating and oxidizing upon contact with air. Many companies do not close this valve after the new oil has been dehydrated; in fact, they think that if gas is generated after the valve is closed, there will be no way to release it. In reality, once the heat transfer oil has been properly dehydrated and dehydrogenated, no gas is produced during normal use. Even if a small amount of gas does appear, it will be discharged into the system’s lower tank through the overflow pipe located in the upper tank. Keeping the forced exhaust valve open for an extended period can lead to the following hazards: 1. It reduces the service life of the heat transfer oil, as air enters the upper tank when the forced exhaust valve is open. High temperatures in the upper tank can cause the heat transfer oil to oxidize at high temperatures, and the sludge present in the system is the result of this oxidation process. 2. The system suffers from severe coking; under the effect of high-temperature oxidation, this leads to the high-temperature cracking and polymerization of the heat transfer oil, resulting in the formation of many hard carbon deposits and cokes that adhere to the walls of the system’s pipes. This, in turn, causes problems such as the failure of the system’s heat-using equipment to reach the required temperatures. 3. Safety hazards: Since the forced exhaust valve is not closed, a sudden increase in the system’s oil temperature can cause the heat transfer oil in the sump to expand. If this expansion occurs too rapidly, the oil may be ejected through the forced exhaust valve. The high-temperature heat transfer oil, when in contact with air, can lead to fires or burns for the operators. From the above points, it can be seen that the forced exhaust valve on the high-level tank must be closed when the system pressure is stable. In closed systems abroad, there is no air in the high-level tank; instead, inert gas such as nitrogen is used for sealing. This not only prevents the high-level tank from overheating but also stops the heat transfer oil in the system from coming into contact with air and undergoing oxidation, thereby better ensuring the safe operation of the equipment. Although open systems are more common in China, proper operation remains key to maintaining the health of the system. Based on insights obtained from various experienced experts, our company has concluded that once the heat transfer oil system is operating stably, the forced exhaust valve on the high-level tank should be closed promptly to avoid unnecessary risks.

This post was last edited by Heat transfer oil on 2018-10-22 at 11:22. It’s a comprehensive issue: 1. What type of heat transfer oil are you using? Some heat transfer oils exist in a gas-liquid two-phase state. 2. Verify whether the system is installed properly. 3. If the oil has been heated according to the proper procedures, check whether the auxiliary exhaust pipe still generates heat after its valve is closed; sometimes the quality of the auxiliary exhaust valve can cause this problem； 4. Have someone calculate the circulation volume to determine whether the equipment setup is appropriate.

Generally, there are two situations that can cause an increase in temperature in the expansion tank (what you refer to as the high-level tank): one is that the exhaust valve is not closed, including issues such as valve leakage or failure to close properly； Second, low-boiling substances such as water that have not been completely removed will continue to be discharged through the expansion tube. Overall, this issue must be resolved; otherwise, it may reduce the service life of the heat transfer oil at the very least, and lead to safety accidents at the worst. Does your heat transfer oil heating equipment require hot/cold switching? In systems that use heat transfer oil for heating or cooling, an important factor affecting thermal efficiency and economic costs is the switching between hot and cold oil during the process of temperature adjustment. When hot oil (or cold oil) is switched to cold oil (or hot oil), the hot oil (or cold oil) remaining in the jacket (or coils, semi-coils) of the reaction vessel is transferred to the cold oil (or hot oil) system, where it must be cooled (or heated) to become cold oil (or hot oil). Each switch causes significant heat loss and cold loss. It is estimated that, for a reactor jacket with a capacity of 5 m3, the heat loss and cold loss associated with each switchover are each around 60,000 kcal (equivalent to 70 kWh), which is undoubtedly a significant amount of loss. Of course, the specific amount depends on the volume of heat transfer oil in the jacket. How can we avoid this energy loss caused by the need to cool hot oil and then reheat cold oil? Creative ideas, excellent designs, and **patents enable you to solve problems easily, significantly reduce energy losses, and effectively cut production costs. Whether heat transfer oil is used for cooling or not, whether it’s the renovation of an existing system or the design of a new one, everything is so simple and easy. Low investment, high returns – why not give it a try? Guided by theory and based on practice, this technology has been implemented in large-scale projects. Welcome to visit! System design plans, control programs, and operating procedures can be provided.

Indeed, after the heating oil has been boiled, the exhaust pipeline should be closed promptly; otherwise, the hot heating oil may flow into the high-level tank and cause its temperature to rise. Additionally, I would like to ask if your high-level tanks are equipped with thermometers for monitoring

We experienced an incident where the heat transfer oil spilled out of the upper oil tank. I didn’t understand what was going on at the time, but after hearing the explanations from the experts, things became much clearer to me. Thank you

Installing a cooling tube in the high-level tank solves the problem for just twenty to thirty thousand yuan