Alternative two column HRU design with rich reflux
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Solution Overview
Problem
Current heavies removal processes in natural gas processing are costly and inflexible due to the need for dual column designs, which are sensitive to feed composition and conditions, leading to increased capital and operating expenses and limited compositional feed range.
Innovation Solution
A single column refluxed absorber design with a condenser and external rich reflux is used, eliminating the need for a reboiler and reducing capital and operating costs, while increasing operational flexibility and separation efficiency by using a rich solvent to enhance heavies removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dual column design is used to separate C6+ species from natural gas, then separation capability is improved, but capital and operating costs increase
Solution Approach 1:
The patent combines the functions of two separate columns (absorber and stabilizer) into a single integrated column with internal stages. This single column design performs both absorption of C6+ species and stabilization operations, eliminating the need for dual column infrastructure while maintaining separation capability. The integration reduces capital costs by removing one column, one reboiler, and associated balance of plant equipment, while also reducing operating costs through simplified operations.
Solution Approach 2:
The single column is designed to perform multiple functions simultaneously: it acts as both an absorber for removing C6+ species and a stabilizer for controlling overhead composition. The column includes rich and lean solvent injection points, reboiler sections, and condenser sections that enable it to execute multiple separation tasks within one vessel, replacing the specialized functions previously requiring two separate columns.
2Manufacturing precision
If a dual column geometry is used, then separation performance is improved, but sensitivity to feed composition increases
Solution Approach 1:
The single column design incorporates dynamic control elements including adjustable rich and lean solvent injection rates, controllable reboiler heat input, and adjustable condenser cooling. These dynamic parameters allow the column to adapt its internal flow patterns and temperature profiles in response to varying feed compositions, maintaining effective separation across a broader range of feed conditions compared to the fixed dual-column geometry.
Solution Approach 2:
The patent utilizes parameter changes within the single column to accommodate different feed compositions. By adjusting operating parameters such as solvent flow rates, reboiler duty, and condenser cooling rates, the column can optimize its performance for different feedstocks. The unified design allows for more flexible parameter adjustment compared to the constrained dual-column system, enabling adaptation to wider compositional ranges.
3Manufacturing precision
If absorber diameters are significantly different due to feed composition, then separation efficiency is improved, but a superstructure is required
Solution Approach 1:
The patent merges the absorption and stabilization functions into a single column with uniform diameter, eliminating the need for superstructure designs that would be required if significantly different column diameters were needed. The unified column maintains appropriate liquid and gas flow distribution throughout its height, achieving effective separation without requiring complex multi-diameter configurations or additional switching 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
The single column design reduces overall expenditures, enhances feed flexibility, minimizes C6+ and solvent loss, and improves heavies separation efficiency, lowering the rich reflux flowrate requirement and eliminating the need for gas compression.
Implementation Method 1
an overhead stream from the stabilizer column is routed through a condenser for partial separation into an overhead stream
Implementation Method 2
A bottoms stream is routed to a first heat exchanger and then to a stabilizer column
Implementation Method 3
the rich reflux is pumped to the single column refluxed absorber to be introduced into the single column refluxed absorber as the external rich reflux gas feed
Data Source
AI summary
The invention relates to a system, method and apparatus for removing heavies from natural gas. Natural gas and an external rich reflux gas feed are processed in a single column refluxed absorber. A bottoms stream is routed to a first heat exchanger and then to a stabilizer column where an overhead stream from the stabilizer column is routed through a condenser for partial separation into an overhead stream. A rich solvent may be introduced to the stabilizer column. The overhead stream is routed through a condenser for partial separation into a stabilizer reflux and a second overhead stream lights. The second overhead stream lights is routed to a heat exchanger and then routed to a partial condenser where the stream is separated into a heavies rich reflux stream, a distillate stream and heavies treated natural gas stream. The rich reflux is routed through a heat exchanger and the rich reflux is pumped to the single column refluxed absorber to be introduced into the single column refluxed absorber as the external rich reflux gas feed.