What Is Thermal Fluid?

Heat transfer oil is the former name of "heat carrier oil" in GB / T 4016-1983 "Terms of Petroleum Products". The English name is Heat transfer oil. It is a kind of special oil with good thermal stability for indirect heat transfer. Product. Due to its characteristics of uniform heating, accurate temperature control, high temperature under low steam pressure, good heat transfer effect, energy saving, convenient transportation and operation, etc., it has been widely used in various occasions in recent years. More and more.

Thermal oil

Heat transfer oil is the former name of "heat carrier oil" in GB / T 4016-1983 "Terms of Petroleum Products". The English name is Heat transfer oil. It is a kind of special oil with good thermal stability for indirect heat transfer. Product. Due to its characteristics of uniform heating, accurate temperature control, high temperature under low steam pressure, good heat transfer effect, energy saving, convenient transportation and operation, etc., it has been widely used in various occasions in recent years. More and more.

Chinese name

Thermal oil

Foreign name

Thermal conductive oil.

Also known as

Heat transfer oil

Related characteristics

Belongs to oil

The English name of thermal oil is Thermal conductive oil.

Heat transfer oil has properties of resistance to thermal cracking and chemical oxidation, good heat transfer efficiency, fast heat dissipation, and good thermal stability. Heat transfer oil as an industrial oil heat transfer medium has the following characteristics: under almost atmospheric conditions, a very high operating temperature can be obtained. That can greatly reduce the operating pressure and safety requirements of the high temperature heating system, and improve the reliability of the system and equipment; it can meet the process requirements for heating and cooling at different temperatures in a wider temperature range, or use the same type in the same system The heat transfer oil simultaneously achieves the high-temperature heating and low-temperature cooling process requirements. The complexity of the system and operation can be reduced;

Thermal stability is the most important performance of a heat transfer fluid. Different thermal stability, its heat during use

China's heat transfer oil products implement the GB23971-2009 "heat transfer oil" standard. Users should pay attention to the following issues before purchasing:

Before selecting the heat transfer oil, you should first determine the appropriate heating process, and it is best to entrust a professional department to do the system design. If the system is already coked and oil needs to be selected again, the cause of the coking should be carefully found, the problems in system design, component settings and operation management should be corrected, and the system should be cleaned carefully.

(1) The authenticity of the highest use temperature of the product is determined by the thermal stability test method of the Academy of Stone Sciences, that is, after the test at the highest use temperature, the appearance is transparent, no suspended matter and precipitation, and the total change rate is not more than 10% Corresponding temperature. By comparing with the new standard, the authenticity of the product manual is analyzed. In particular, it is necessary to understand how the specified maximum use temperature is determined, and whether there is an inspection report from an authority. According to the international standard classification, the maximum temperature of the mineral-type heat transfer oil does not exceed 320 ° C. At present, the maximum temperature of most of this oil is 300 ° C.

(2) Investigate product evaporation and safety

Industry: applied industry and device rubber and plastic industry: hot pressing, calendering, extrusion,

According to the composition and manufacturing process, heat transfer oil can be divided into synthetic heat transfer oil and mineral heat transfer oil.

First, there are the following types of heat transfer oil:

1) Alkylbenzene type (benzene ring type) heat transfer oil

This type of heat transfer oil is a benzene ring with a paraffinic branched chain type compound, which is a product of a short branched alkane group (including methyl, ethyl, isopropyl) and a benzene ring. Its boiling point is 170 ~ 180 , and its freezing point is below -80 , so it can be used as an antifreeze. The characteristics of this type of product are that it is not easy to precipitate in the applicable range, and isopropyl chain-linked compounds are particularly preferred.

2) Alkyl naphthalene type heat transfer oil The structure of this type of heat transfer oil is a compound connected to an alkane branch on the benzene ring. The side chains to which it is attached are generally methyl, dimethyl, isopropyl, etc. The type and number of the side chains attached to it determine the properties of the compound. Alkyl naphthalenes whose side chains are mono-linked to methyl are used in gas-phase heating systems in the range of 240 to 280 ° C.

3) Alkyl biphenyl heat transfer oil This type of heat transfer oil is a type of compound with an alkyl branch chain attached to the biphenyl ring. It is composed of a short-chain alkyl group (ethyl, isopropyl) and a biphenyl ring. The type and number of the alkyl group determine its properties. The larger the number of alkane groups, the worse the thermal stability. In this kind of product, the heat transfer oil synthesized from iso-iso, iso-iso (isomeric) and biphenyl has the best quality, its boiling point is> 330 , and its thermal stability is also good. Ideal product for use in the range of 300 ~ 340 .

4) Biphenyl and biphenyl

I. Potential dangers of performance during the use of heat transfer oil

Due to the local overheating of the heating system during the use of thermally stable heat transfer oil, thermal cracking reactions are prone to occur, and volatile polymers with low flash points are formed.

There are seven points for the detection of heat transfer oil, because heat transfer oil (also known as heat transfer fluid) has a series of physical properties, such as viscosity, vapor pressure, boiling range, initial boiling point, flash point, ignition point, and flow point. The purpose of periodic inspection during operation is to understand the changes in the internal quality of the oil, and to discover system design, operation management and quality problems of the heat transfer oil itself, and correct them in time to extend the service life. The following inspection items can explain the deterioration of the heat transfer oil during operation:

 1. Distillation range The change in distillation range indicates the change in the molecular weight of the heat transfer liquid. Gas chromatography is used abroad. After comparing with the distillation range of new oil, the contents of high boiling and low boiling materials indicate the degree of cracking and polymerization of the heat transfer liquid .

 2. Viscosity changes indicate changes in the molecular mass and structure of the heat transfer fluid.  Cracking reduces viscosity, while polymerization and oxidation increase viscosity.  These changes have a small effect on the viscosity in the high temperature range, but have a greater effect on the viscosity at low temperatures. Therefore, for cold regions and operating processes with cooling, the increase in low temperature viscosity should be taken seriously.

 3. Acid value The change of acid value indicates the degree of aging of the heat transfer fluid.  The rise in acid value is usually caused by the oxidation of oil products, and it mainly occurs in the system without nitrogen seal in the expansion tank.  However, when aging to a certain degree, soluble organic acids may further polymerize to form polymer oxidation products, at which time the acid value may decrease.  Therefore, we should pay attention to judging the aging degree of oil products from the change trend of acid value.

 4. Residual carbon Residual carbon is the amount of residual carbon left after the heat-conducting liquid in operation is evaporated and cracked.  In operation, the amount of residual carbon tends to rise continuously with time, which can explain the tendency of the formation of polymer carbon-like deposits and the degree of aging.

 Foreign countries often measure acetone or pentane insolubles, including oil insolubles and resinous materials produced by cracking and polymerization.  Because the method has not been evaporated and pyrolyzed, it can accurately explain the content of insolubles in oil products.

 5. Flash point Flash point is the main safety indicator, indicating the possibility of the formation of highly volatile products and flammable gases.  Excessive drop in flash point may become a hidden danger of an accident.
 Generally, the deterioration of the heat transfer fluid is judged comprehensively through the above inspection items.