2 replies to this topic

[guoyinyanliner]

​This is a natural gas molecular sieve dehydration process, and the red arrow points to a natural gas pre-cooling unit. Could you please specify what exact equipment this is? I haven't used this type of equipment before.

Edited by guoyinyanliner, Yesterday, 08:22 AM.

[Pilesar]

I do not see that you were successful in posting anything but text. But from your text description, a pre-cooling unit before natural gas dehydration is likely to be for the purpose of condensing moisture from the gas and will consist of a heat exchanger and a 2-phase separator. Any water removed from the stream prior to the mole sieve reduces the load on the sieve.

[breizh]

Google search AI mode

A natural gas precooling unit is a piece of process equipment used to lower the temperature of natural gas before it enters a downstream treatment, liquefaction, compression, or separation process.

Why is natural gas precooled?

Precooling helps by:

• Removing heavier hydrocarbons (such as propane, butane, and condensates)
• Reducing water vapor content and preventing hydrate formation
• Lowering compression power requirements
• Improving efficiency of LNG (Liquefied Natural Gas) plants
• Protecting downstream equipment from temperature and phase-change issues

How does it work?

Typically, the incoming gas passes through a heat exchanger where it is cooled by a refrigeration system or another cold process stream.

Common precooling methods include:

1. Propane refrigeration systems

   • Widely used in LNG facilities.
   • Gas may be cooled from ambient temperature to around -30°C to -40°C.

2. Mechanical refrigeration

   • Uses refrigerants such as propane, ethylene, or mixed refrigerants.

3. Heat exchange with cold process streams

   • Recovers cooling from existing plant operations.

Example in an LNG plant

In a typical LNG facility:

Natural Gas Feed
↓
Precooling Unit
↓
Acid Gas Removal
↓
Dehydration
↓
Liquefaction Unit
↓
LNG Storage

Or, in many modern LNG processes:

Feed Gas
↓
Treatment
↓
Propane Precooling
↓
Main Cryogenic Heat Exchanger
↓
Liquefaction (-162°C)

The precooling stage removes heat efficiently before the gas enters the much colder and more energy-intensive liquefaction section.

Main equipment in a precooling unit

• Heat exchangers
• Refrigerant compressors
• Refrigerant condensers
• Refrigerant separators/drums
• Control valves and instrumentation

Industries that use precooling units

• LNG export terminals
• Gas processing plants
• Petrochemical facilities
• Natural gas storage and transportation systems

In short, a natural gas precooling unit is an upstream refrigeration section that cools natural gas before deeper processing or liquefaction, improving efficiency and enabling the removal of unwanted components.