How do you determine if your heat transfer fluid fails? How to deal with heat transfer oil after a l

Generally, there are the following two types of domestic heat transfer oil testing, and it is recommended (only recommended, there is no mandatory standard) to replace the heat transfer oil.

1) Acid value ;

2) carbon residue ;

3) Flash point change value 20% (compared with the new oil at the beginning of use) 4) Viscosity change value of 15% (compared with the new oil at the beginning of use) Heat transfer oil, used for heat transfer, the key is its own stability, such as viscosity flash point changes can show that the oil itself structure has changed, such as: the flash point becomes low, indicating that the oil cracking produces low boiling matter, and the pressure gauge will be unstable; The flash point becomes higher, the viscosity increases, and the oil is cracked and polymerized into a high boiling substance at high temperature, which causes carbon deposition on the inner wall of the system, resulting in heat that is not easy to transfer, increasing coal consumption, and so on.

The blackening of the heat transfer oil is the reason for the increase of residual carbon, the general mineral heat transfer oil scrap standard, viscosity 15%, lightning change 20%, acid value, residual carbon, it is best to analyze it.

Indicators for judging the failure of heat transfer fluid.

1) Acid value ;

2) carbon residue ;

3) Flash point change value 20% (compared with new oil at the beginning of use) 4) Viscosity change value of 15% (compared with new oil at the beginning of use).

There will be domestic heat transfer oil experts, the first domestic heat transfer oil developer to answer your technical questions.

Beijing Yantong Petrochemical ****.

"Heat transfer oil is an organic chemical product, so the old heat transfer oil replaced by the oil temperature machine may have an impact on the environment and the human body, so it should be treated correctly." When the flash point, viscosity, acid number, residual carbon and other numerical values are detected on the samples of circulating heat transfer oil, and the comprehensive evaluation is carried out to confirm that it is a deteriorated oil, it can be replaced. ”。

For the old heat transfer oil that has been replaced, there are generally two treatment methods, one is the heat transfer oil that can be reused, and the other is the heat transfer oil that cannot be reused. The regenerative heat transfer oil can be properly processed to achieve the index of its original Qingqing product, while the regenerative heat transfer oil must be synthetic, and the aging degree has not been accelerated and more serious. For non-renewable heat transfer fluids, they can generally only be used as fuel oil.

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1.On the surface, there is not much difference between an inferior product and a standard product, but a closer look reveals that the inferior product can change color even at room temperature. This change will gradually change from pale yellow to deep black.

Over time, without entering the system, inferior products will be exposed.

2.From the perspective of product indicators, there are many indicators of heat transfer oil, which can be tested first, and the freezing point test can see whether the oil is counterfeit. Even if it is fake, it can be used to expose the inferior product through simple high-temperature heating, and the heat transfer oil pour point depressant after high temperature will volatilize during the heating process, so that the pour point depressant does not work.

3.From the perspective of volatile characteristics, take the same number of samples for comparison to see the degree of volatilization, under normal circumstances, inferior products due to the low flash point, its volatilization will be larger, and the black smoke will be thick.

4.From the perspective of flash point characteristics, although the flash point of oil is a safety index, it is related to its degree of refinement to some extent, so sometimes the characteristics of a product can be determined by the flash point, because the higher the degree of refining, the relative product quality is more stable.

5.From the perspective of oxygen absorption speed, the slower the oxygen absorption rate, the stronger the oxidation capacity, and vice versa, the worse the oxidation stability index of the heat transfer oil.

6.From the point of view of thermal stability, if there is no condition to test on the bench, the quality of the oil can be judged simply on the crucible, and the general inferior heat conduction oil is heated at high temperature, and it will catch fire if it is not added to a specific temperature, and the carbonization is serious. Although we can't use fire as the only criterion for judging good or bad, at least we can see something that we can't see through simple experiments.

There are many reasons that affect the deterioration of heat transfer fluids, but the main ones are contamination, thermal cracking, and oxidation.

Pollution: The presence of impurities will accelerate the deterioration rate of the heat transfer oil and prevent the heat transfer oil from being polluted by impurities, as long as the furnace is carefully washed before the oil change, and the mechanical impurities, moisture and other impurities can be prevented from mixing in the process of storage, transportation and use.

Oxidation: Air infiltration into the system will cause oxidation of the heat transfer oil, and the oxidized heat transfer oil will form a large amount of solid dirt. Usually the infiltration of air comes from the open expansion tank.

Oxidation of heat transfer oil to a certain exposed area and temperature. Corrosion products and rust are often formed due to the rate at which insoluble matter is formed, and the rate of formation depends on the formation of weak acids produced by the heat transfer fluid in the air oxidation products and moisture entering the expansion tank or other parts. A mixture of fluid deterioration and oxidized fluid insolbidities can be deposited on the surface of the heat exchanger, especially in low flow areas of the system, such as dead corners or lowest spots.

Thermal decomposition and aging coking: The thermal decomposition of heat transfer oil is caused by the use temperature of heat transfer oil exceeding its thermal decomposition limit temperature. For example, where excessive heat flux intensity or fluidity is restricted, cracking of heat transfer oil often occurs, and thermal decomposition of heat transfer oil often leads to coking of heat medium furnace tubes.

Coking is more rapid in heat transfer fluids contaminated with decomposed antioxidants and impurities. The formed coke adheres to the tube wall, affecting heat transfer and further accelerating cracking, polycondensation and coking, creating a vicious circle. A large amount of coke accumulates on the furnace tube wall, which directly affects the safety of the furnace body.

The pyrolysis rate of the heat transfer oil increases rapidly with the increase of temperature, and the cracking rate of the heat transfer oil doubles for every 10 times the temperature increases.

There are three main reasons for food spoilage,1Microorganisms, common causes. We live in an ocean of microbes.

Microorganisms multiply in the food force, causing food spoilage. 2.Problems with the composition of the food itself.

It's not as good as potatoes and apples, as long as the skin is broken, it will definitely be bad if you put it in the refrigerator for a while. Just because I said that most of the vegetables have phenolic substances, which are easily oxidized and browned. 3.

Problems with processing methods. Mainly because of the presence of enzymes in food, improper handling will accelerate the reaction and cause food spoilage.

The purpose of regular inspection during operation is to understand the changes in the intrinsic quality of the oil, and to find out the quality problems of the system design, operation management and the heat transfer oil itself, and to correct them in time to prolong the service life. The following inspection items can illustrate the deterioration of thermal transfer fluid during operation:

1. Distillation range. In recent years, gas chromatography has been used in foreign countries, and the high boiling and low boiling content indicate the degree of cracking and polymerization of the heat transfer liquid by comparing it with the distillation range of new oil.

2. Viscosity. A change in viscosity indicates a change in the molecular mass and structure of the heat transfer fluid. Cleavage decreases viscosity, while polymerization and oxidation increase viscosity. These changes have little effect on viscosity in the high-temperature range, but have a large effect on low-temperature viscosity, so low-temperature viscosity growth should be of concern for cold regions and operating processes with cooling.

3. Acid value. The change in acid number indicates the degree of aging of the heat transfer fluid. Increases in acid number are usually caused by oxidation of the oil and occur mainly in systems where the expansion tank does not use blanketing. However, when aging to a certain extent, soluble organic acids may further polymerize to form polymer oxidation products, and the acid value may decrease again.

Therefore, it is necessary to pay attention to the aging degree of the oil from the change trend of the acid value.

4. Carbon residue. Carbon residue is the amount of carbon left behind after evaporation and cracking of the heat transfer fluid in operation. The amount of carbon residue tends to increase with time, which can indicate the tendency of polymer carbon-like sediments to form and the degree of aging.

In recent years, acetone or pentane insoluble substances are often determined abroad, including oil insoluble substances and resinous substances produced by cracking and polymerization. Because this method does not evaporate and pyrolyze, it can accurately state the content of insoluble matter in the oil.

5. Flash point. The flash point is the main safety indicator that illustrates the potential for the formation of highly volatile products and flammable gases. Excessive drop in flash point can be a hidden danger to accidents.

Generally, the above inspection items are used to comprehensively judge the deterioration of the heat conduction liquid.

GB23971-2009 "Organic Heat Carriers" and GB24747-2009 "Safety Technical Conditions for Organic Heat Carriers" are described in detail.

Thermal oil is basically divided into two categories: mineral oil and synthetic thermal oil, the most convenient way to identify the freezing point of thermal oil to identify mineral oil and synthetic thermal oil, mineral oil is currently too chaotic in the market, a lot of it is a charge, take non-standard or enterprise standard oil as national standard oil to sell, ** cheaper than national standard oil, national standard mineral oil can choose some such large enterprises or old enterprises such as the Great Wall, Kunlun, Wuxi Xiaoyang, etc., synthetic heat transfer oil is now a lot of fakes on the market, good to take once, or twice, The three hydrogenated mineral oil pretends to be hydrogenated synthetic heat transfer oil, although the performance is slightly better than the national standard oil, but compared with pure alkylbenzene, hydrogenated terphenyls, biphenyls and diphenyl ether synthetic heat transfer oil, the difference is far, and the synthetic heat transfer oil can refer to well-known brands such as France Total, the United States Solutia (Monsanto Chemical), Wuxi Xiaoyang (Monsanto Chemical), Dow Chemical, etc., with reliable quality.