How to use shell and tube heat exchangers in the petrochemical industry

Shell and Tube Heat Exchanger is the most common heat exchange equipment in the petrochemical industry, and is widely used in heating, cooling, evaporation, condensation and other process links. Since the petrochemical industry involves high temperature, high pressure and corrosive media, shell and tube heat exchanger is the first choice because of its high temperature and high pressure resistance, strong structure and high heat exchange efficiency.

1. Main application process

1.1. Crude oil preheating and distillation

During the oil refining process, crude oil needs to be preheated before entering the distillation tower for fractionation, which is mainly completed by shell and tube heat exchanger:

1.1.1. Crude oil preheating: Use heat exchanger to recover the heat of heavy oil or other high temperature medium at the bottom of the tower, increase the temperature of crude oil and reduce fuel consumption.

1.1.2. Atmospheric distillation tower and vacuum distillation tower: The top condenser is used to condense the distilled gaseous components, and the heavy oil at the bottom of the tower is heat-exchanged with the feed crude oil through the heat exchanger to improve the utilization rate of thermal energy.

1.2. Cooling of petrochemical products

In the petrochemical production process, many process fluids have high temperatures after reaction and need to be cooled before entering the next process:

1.2.1. Post-reaction cooling: such as cooling of products after catalytic cracking, hydrocracking, hydrodesulfurization and other processes.

1.2.2. Gas cooling: gas products such as ethylene, propylene, butadiene, etc. are condensed into liquid through heat exchangers for storage or further processing.

1.3. Condensation and recovery

1.3.1. Distillation tower condenser: used to condense the gas at the top of the tower and convert it into liquid for separation, such as the recovery of liquefied petroleum gas (LPG) and naphtha.

1.3.2. Solvent recovery: such as aromatics extraction, solvent recovery after esterification reaction, to reduce resource waste.

1.4. Heating and reboiling

1.4.1. Reboiler: At the bottom of the distillation tower or extraction tower, the required steam flow in the tower is maintained by heating. For example, heat exchangers are used in light hydrocarbon recovery units and reforming units to heat the bottom liquid and partially vaporize it to promote separation.

1.4.2. Catalytic cracking: Shell and tube heat exchangers are used to heat heavy oil or vacuum residue oil to enter the catalytic cracking unit to improve reaction efficiency.

1.5. Waste heat recovery

In petrochemical production, high-temperature gases and liquids discharged by many equipment can be recovered through heat exchangers to improve energy efficiency. For example:

1.5.1. Cracking furnace waste heat recovery: High-temperature flue gas is heated by heat exchangers to heat boiler feed water or air to improve thermal energy utilization.

1.5.2. Coking unit: Use high-temperature coking oil gas for heat exchange to reduce energy loss.

2. Application in typical units

2.1. Refinery

2.1.1. Crude oil distillation unit: preheater, reboiler, condenser.

2.1.2. Catalytic cracking unit: reactor cooling, product outflow cooling.

2.1.3. Delayed coking unit: heating at the bottom of the coking tower and gas condensation.

2.2. Ethylene cracking unit

2.2.1. Furnace gas cooling: The high-temperature gas of the cracking furnace is cooled by the heat exchanger to reduce energy consumption.

2.2.2. Ethylene separation distillation tower: condensation at the top of the tower and reboiling at the bottom of the tower.

2.3. Fuel and chemical production

2.3.1. Methanol and ammonia production: reaction gas cooling and product condensation.

2.3.2. Aromatic separation: condensation and solvent recovery.

3. Advantages of shell and tube heat exchangers

3.1. High temperature and high pressure resistance: suitable for high temperature and high pressure process conditions in the petrochemical industry.

3.2. Strong corrosion resistance: stainless steel, titanium alloy and other materials can be used to deal with corrosive media.

3.3. Convenient maintenance: the tube bundle can be disassembled for easy cleaning and maintenance.

3.4. Stable structure: strong vibration resistance, suitable for long-term operation conditions.

 

4. Material selection

4.1. Carbon steel: suitable for common process fluids such as water, oil, steam, etc.

4.2. Stainless steel (304, 316L): strong corrosion resistance, suitable for acidic or sulfur-containing media.

4.3. Titanium alloy: used for seawater cooling and highly corrosive environments.

4.4. Nickel-based alloys (such as Hastelloy): suitable for heat exchange of highly corrosive chemicals.

5. Maintenance and management

5.1. Regular cleaning: prevent scaling from affecting heat exchange efficiency.

5.2. Check for leaks: avoid environmental pollution or equipment damage caused by medium leakage.

5.3. Replace seals: improve long-term operation stability.

 

6. Summary

Shell and tube heat exchangers are widely used in the petrochemical industry, involving multiple links such as preheating, cooling, condensation, evaporation, and waste heat recovery. Its high efficiency and durability make it an indispensable core equipment in the petrochemical industry.

 

Related Links:

How Shell and Tube Heat Exchanger Work