Mol. Sieve Dehydration Unit Potential Problems for LNG Plant

 

Mol. Sieve Dehydration unit potential problems for LNG plant.

 

AICHE 2014 spring meeting

 

By J C Kuo and Dr. K H Wang.

University of Houston      

 

 

 

 

Abstract

 

Many dehydration units in based load plant have not been able to operate per design and premature moisture breakthrough has been occurring. From RCA (Root Cause Analysis) indicate the followings potential issues 

1.     Regeneration Gas Flow

The design regeneration gas flow rate is very critical.

2.     Retrograde Condensation

Retrograde condensation can impact the performance of numerous operations including amine absorption, molecular sieve dehydration, and mercury removal.

Liquid hydrocarbons in the amine unit can cause foaming and lead to reduced production. Liquid hydrocarbons can damage the sieve in the dehydration beds resulting in poor performance and lower production.

3.     Liquid Carryover

The design of inlet separator need to offer sufficient separation. Otherwise it carries liquid over with the gas due to the high operating pressures and low surface tension.

4.    Regeneration Gas temperature.

Some base load plant could use 315C high temperature in order to minimize the regeneration gas flow. However for some impurities include heavy hydrocarbon, methanol or Amine solution, lower temperature at 240 C ranges may be required.