Lean Amine Hot Circulation for Faster Sweetening Shutdowns
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Solution Overview
Problem
Existing gas sweetening systems require prolonged shutdown times during maintenance due to the slow removal of acid gases, which is inefficient and costly in terms of time and energy consumption.
Innovation Solution
Increasing the temperature set point of the lean amine cooler from 130° F. to 150° F. in the amine sweetening system to enhance acid gas desorption, thereby reducing the time required to reach target H2S concentrations and lowering steam consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amine loop temperature is maintained at 130°F and steam flow inside the regenerator boilers is increased for faster stripping of acid gases, then the H2S concentration can reach target levels, but the shutdown time takes up to 43 hours and steam consumption is high
Solution Approach 1:
The patent changes the temperature parameter of the lean amine from the conventional 130°F to a higher temperature range of 150-200°F during the hot circulation process. This parameter change accelerates the desorption of acid gases (H2S and CO2) from the amine solution, reducing the shutdown time from 43 hours to approximately 10 hours while still achieving the required H2S concentration target of less than 30 ppm.
Solution Approach 2:
The patent performs preliminary heating of the lean amine to 150-200°F before the actual acid gas stripping process during shutdown. This preliminary action prepares the amine for faster desorption of acid gases, enabling the system to reach target H2S concentrations more quickly without requiring excessive steam consumption during the cleanup phase.
2Productivity
If the steam flow inside the regenerator boilers is increased for faster stripping of acid gases, then the H2S concentration reaches target levels faster, but steam consumption increases significantly
Solution Approach 1:
The patent changes the temperature parameter of the lean amine from 130°F to 150-200°F, which fundamentally alters the equilibrium conditions for acid gas absorption/desorption. This temperature parameter change enables faster acid gas stripping at lower steam consumption because the higher temperature naturally promotes desorption, reducing the reliance on high steam flow rates and thereby lowering energy consumption.
Solution Approach 2:
The patent dynamically adjusts the lean amine temperature to 150-200°F specifically during the shutdown hot circulation process, rather than maintaining the steady-state operating temperature of 130°F. This dynamic temperature adjustment optimizes the desorption kinetics during the critical shutdown period, achieving faster acid gas removal with reduced steam consumption compared to increasing steam flow at lower temperatures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces shutdown duration by up to 75% and decreases steam consumption by 23%, resulting in cost savings and reduced CO2 emissions, enabling earlier startup and increased revenue from gas production.
Implementation Method 1
The sour gas feed is contacted with a lean amine which absorbs hydrogen sulfide and carbon dioxide from the natural gas
Implementation Method 2
The rich amine is passed through a regenerator for reprocessing, which removes the acid gases and regenerates the lean amine
Data Source
AI summary
A method for preparing a gas sweetening system for less shutdown time is provided. The method includes stopping a sour gas feed to a gas sweetening system, and raising the set point for a temperature of a lean amine cooler to about 150° F. The H2S concentration in a lean amine is monitored. The preparation of the gas sweetening system for maintenance is completed when the H2S concentration reaches a target value.