What are the functions of tubular heat exchangers

Source：www.lingjang.com Release date： 2025-06-24

Tube heat exchanger is a device that transfers heat between cold and hot fluids through the wall of the tube bundle, and is widely used in industrial fields such as chemical, petroleum, power, and food. Its core function is to utilize the temperature difference between the fluid inside and outside the pipe to transfer the heat of the high-temperature fluid to the low-temperature fluid, in order to meet the heating, cooling, condensation, or evaporation needs during the process. The following provides a detailed explanation of specific functions, application scenarios, and technological advantages:
1、 Core role and functional classification
1. Heating and warming up
Function: Heat the low-temperature fluid through the high-temperature medium (such as steam, heat transfer oil) on the outside or inside of the tube bundle to reach the required temperature for the process.
Application scenarios:
Preheating raw materials before chemical reactions (such as heating the raw material gas with synthesis gas in ammonia synthesis plants);
Heating before crude oil transportation to reduce viscosity (such as using tube heat exchangers in heating furnaces for oil pipelines).
2. Cooling and cooling
Function: Use low-temperature media such as cooling water and air to remove heat from high-temperature fluids, reducing their temperature to the target value.
Application scenarios:
Compressor outlet gas cooling (such as cooling of compressed air in air separation units);
Cooling after the production of chemical products (such as the cooling of molten materials in the production of polyethylene particles).
3. Condensation and liquefaction
Function: Cool high-temperature gaseous media (such as steam, organic vapor) through low-temperature fluid to condense them into liquid state.
Application scenarios:
Steam condensation at the top of a distillation tower (such as the condensation and recovery of ethanol vapor at the top of the tower during ethanol distillation);
Condensation of refrigerant gas in refrigeration systems (such as air conditioning condensers).
4. Evaporation and vaporization
Function: Use high-temperature fluid to heat liquid medium, causing it to evaporate into gas (such as producing steam or vaporized refrigerant).
Application scenarios:
The water in the boiler evaporates into steam (using a tube heat exchanger as the heating surface of the boiler);
LNG in liquefied natural gas (LNG) gasification stations is vaporized by heating seawater or air.
2、 Typical application areas and scenarios
1. Chemical and petroleum industries
Refinery atmospheric and vacuum distillation unit:
Use a tube heat exchanger to exchange heat between crude oil and high-temperature distillate oil, recover heat and preheat the crude oil, reducing the load on the heating furnace (heat exchange efficiency can reach 70% -80%).
Synthetic ammonia production:
In the transformation process, a tubular heat exchanger is used to exchange heat between the high-temperature transformation gas and the raw material gas, raising the temperature of the raw material gas to the reaction temperature (about 300-400 ℃) while cooling the transformation gas.
2. Power industry

Steam turbine condenser:

As a type of tube heat exchanger, circulating water is used to cool the exhaust steam of the steam turbine, condensing it into water and recovering it to the boiler (with a heat exchange area of up to thousands of square meters).
Waste heat recovery system:
Using flue gas or high-temperature steam to heat feedwater through a tube heat exchanger to improve the thermal efficiency of power plants (such as waste heat boilers in gas steam combined cycle units).
3. Refrigeration and air conditioning
Water cooled chiller unit:
The condenser adopts a shell and tube heat exchanger, which uses cooling water to remove the heat of refrigerant (such as R410A) and condense it into liquid state; The evaporator absorbs heat and cools the chilled water by evaporating the refrigerant.
Cold storage system:
Tube evaporators (such as exhaust tube heat exchangers) are installed in cold storage, where the refrigerant absorbs heat as it flows through, reducing the temperature inside the storage to below -18 ℃.
4. Food and Medicine
Food sterilization and cooling:
In milk pasteurization equipment, a tube heat exchanger is used to heat milk with hot water to 72 ℃ for 15 seconds, and then cooled with cold water to room temperature (with a heat recovery rate of over 90%).
Pharmaceutical solvent recovery:
In the process of drug synthesis, using a tube heat exchanger to condense and recover organic solvents (such as ethanol and acetone) reduces waste and lowers environmental treatment costs.
3、 Technical advantages and structural features
1. Efficient heat transfer mechanism
Structural design:
The arrangement of tube bundles (such as equilateral triangles and squares) and the design of baffles (such as bow shaped baffles) can enhance fluid turbulence, reduce boundary layer thermal resistance, and achieve a heat transfer coefficient of 200-1500 W/(m 2 · K) (depending on the medium and flow velocity).
Scalability:
By increasing the number of tube bundles or shell diameters, the heat transfer area can be flexibly adjusted (from a few square meters to tens of thousands of square meters) to meet large-scale industrial needs.
2. Adapt to complex working conditions
High pressure and high temperature resistance:
The shell and tube bundle of the shell and tube heat exchanger (the most common type of shell and tube heat exchanger) can be made of materials such as stainless steel and titanium alloy, and can withstand pressures of up to 10MPa and temperatures ranging from -200 ℃ to 800 ℃ (such as heat exchangers in high-pressure hydrogenation units).
Corrosion resistance and scaling:
For corrosive media such as sulfuric acid and seawater, graphite pipes, ceramic pipes, or coated pipes (such as PTFE coatings) can be used to extend equipment life.
3. Convenient operation and maintenance
Detachable structure:
The tube bundles of floating head and U-shaped tube heat exchangers can be extracted as a whole for easy cleaning of scale on the inner and outer surfaces of the tubes (such as cleaning with high-pressure water once a year).
Flexible process design:
Multiple heat exchangers can be connected in parallel or series to achieve simultaneous heat exchange of multiple fluids (such as the multi stream heat exchange network in crude oil pretreatment).

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