Comparison of Advantages and Disadvantages of Several Common Heat Exchangers

The heat exchangers commonly used in the chemical industry can be classified in the following ways:

1) By the heat transfer mode: mixed heat exchanger, regenerative heat exchanger, and wall-pass heat exchanger.

2) By the structure: tubular heat exchanger, plate heat exchanger, and heat transfer surface type heat exchanger.

3) By the purpose: heater, preheater, superheater, evaporator, reboiler, cooler, condenser.

4) By the material: metal materials, non-metal materials.

5) By the shape and structure of the heat transfer surface, etc.: fixed tube sheet type heat exchanger, U-tube type heat exchanger, packed vessel type heat exchanger, and kettle type heat exchanger. 

Usually, in daily work, classification based on structure is mainly adopted. The following is a summary of the advantages and disadvantages of several commonly used heat exchangers:

1. Fixed tube sheet heat exchanger:

(1) Large heat exchange area, approximately 20-30%; no internal leakage, fewer forgings, and low cost;

(2) Cannot be mechanically cleaned; short lifespan, not suitable for places with scale formation. 

2. Floating head heat exchanger:

(1) It can be withdrawn for easy cleaning, and the temperature difference of the medium is not restricted;

(2) One section is not connected to the object. When the tubes are heated, the tube bundle along with the floating head can freely expand and contract along the axial direction.

(3) Two tube plates are prone to internal leakage, consuming a large amount of metal and having high costs, and the structure is complex.

(4) The heat exchange effect is better than that of U-tube heat exchangers.

(5) It is suitable for high-temperature, high-pressure and large temperature difference scenarios. 

3. U-tube heat exchanger:

(1) It can be withdrawn and is easy to clean, without being limited by temperature differences;

(2) The shell side is not suitable for transporting media with large structures.

(3) The structure is simple, consisting of only one tube sheet.

(4) It is suitable for scenarios where the requirement for heat exchange efficiency is not particularly high and the budget is limited. 

4. Packed Tube-Type Heat Exchanger

(1) The tubes can freely expand and contract, and there will be no temperature difference stress between the tubes and the shell.

(2) The structure is simple, the manufacturing process is convenient, and maintenance and cleaning are easy.

(3) There is a possibility of leakage of the shell-side fluid, so the operating pressure and temperature are limited.

(4) Toxic, flammable, explosive and volatile media should not be passed through the shell side. 

5. Plate heat exchanger

(1) Large heat exchange area, low material consumption, small volume, and low space occupation.

(2) Easy to disassemble and clean.

(3) Relatively economical in price.

(4) Poor sealing performance, prone to leakage, and requires frequent replacement of gaskets.

(5) Poor pressure resistance effect, prone to blockage. Not suitable for gas-to-gas heat exchange or steam condensation.