Improved operation of natural gas liquids stabilizer column
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Solution Overview
Problem
Small-scale LNG plants face inefficiencies and high equipment costs due to the need for top condensers in stabilizer columns, which require additional equipment and complexity, especially when dealing with high heavy hydrocarbon content, and existing solutions without reflux result in saturated vapors that condense prematurely.
Innovation Solution
Introducing a natural gas bypass stream upstream of the cold box and scrubber to an intermediate level of the stabilizer column, where it is cooled via Joule Thompson expansion, reducing the top temperature and adding heat to the column, thereby eliminating the need for a top condenser and reducing reboiler duty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a top condenser is used in the stabilizer column, then the top temperature can be reduced and heavy compounds can be recovered, but additional equipment costs and complexity are introduced
Solution Approach 1:
The patent extracts the condensation function from a separate top condenser device and integrates it into the stabilizer column itself by creating a cold zone at the top through controlled natural gas injection. This eliminates the need for external condensation equipment while maintaining the temperature control and heavy compound recovery functions.
Solution Approach 2:
The stabilizer column is designed to perform multiple functions: separation of heavy hydrocarbons, temperature control, and natural gas condensation. By making the column itself capable of condensing natural gas at the top, the system achieves multi-functionality without requiring separate dedicated equipment for each function.
2Device complexity
If no top condenser is used, then equipment complexity is reduced, but the top vapor temperature remains high causing premature condensation in pipelines
Solution Approach 1:
The system performs preliminary cooling of the top vapor by injecting cold natural gas into the upper section of the column before the vapor exits. This preliminary action reduces the temperature sufficiently to prevent premature condensation in downstream pipelines while avoiding the need for post-column condensation equipment.
3Use of energy by stationary object
If natural gas bypass stream is introduced and cooled via Joule Thompson expansion, then top temperature is reduced and reboiler duty decreases, but additional injection equipment is required
Solution Approach 1:
The system changes the temperature parameter of the injected natural gas by expanding it through a Joule-Thomson valve, transforming it from ambient temperature to a cold state suitable for cooling the column top. This parameter change enables the natural gas to serve as a cooling medium without requiring external refrigeration equipment.
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 effectively lowers the top temperature of the stabilizer column from 60-80°C to 40°C, reduces reboiler duty by 6%, and allows the top gas to be used as fuel without condensation, enhancing operational efficiency and reducing equipment costs.
Implementation Method 1
introducing a natural gas bypass stream upstream of the cold box and scrubber to an intermediate level of the stabilizer column, where it is cooled via Joule Thompson expansion
Data Source
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AI summary
A method for improved operation of a natural gas liquids stabilizer column, particularly a small-scale, is provided. The method can include the steps of: introducing a first feed stream comprising heavy hydrocarbons and natural gas to a stabilizer column to produce a top gas and a bottoms liquid, wherein the top gas has a higher concentration of natural gas as compared to the first feed stream, and the bottoms liquid has a higher concentration of heavy hydrocarbons as compared to the first feed stream; introducing a second feed stream into the stabilizer column, wherein the second feed stream has a higher concentration of natural gas as compared to the first feed stream, wherein the second feed stream is at a warmer temperature than the first feed stream when introduced into the stabilizer column, wherein the second feed stream is a gaseous stream; withdrawing the top gas from a top portion of the stabilizer column; withdrawing the bottoms liquid from a bottom portion of the stabilizer column; and sending at least a portion of the bottoms liquid to a liquid storage tank.