Compact Co-Current Fractionation for Offshore Heavy Hydrocarbon Removal
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Solution Overview
Problem
Conventional fractionation columns for removing heavy hydrocarbons from natural gas streams are large, heavy, and costly, limiting their application in space-constrained environments such as offshore LNG processing and requiring significant liquid circulation, which is inefficient for low hydrocarbon concentrations.
Innovation Solution
The use of co-current contacting systems within a pipe, comprising droplet generators and mass transfer sections, allows for efficient separation of heavy hydrocarbons from natural gas streams, reducing the need for large rectification sections and enabling operation at higher fluid velocities, thus minimizing size and weight while maintaining processing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fractionation columns with large rectification sections are used, then heavy hydrocarbons can be effectively removed from natural gas streams, but the system becomes large, heavy, and costly
Solution Approach 1:
The invention extracts and eliminates the large, heavy rectification section from the conventional fractionation column design. By removing this component and replacing it with compact co-current contacting systems, the system achieves the necessary separation function with dramatically reduced weight and size while maintaining heavy hydrocarbon removal efficiency.
Solution Approach 2:
The invention changes the operating parameters and flow patterns from traditional counter-current to co-current contacting. This parameter change enables the use of compact in-line systems with high fluid velocities that achieve equivalent separation performance without requiring the large rectification section, thereby reducing column weight and cost.
2Reliability
If conventional fractionation columns are used, then separation can be achieved, but the system requires significant liquid circulation which is inefficient for low hydrocarbon concentrations
Solution Approach 1:
The invention changes the liquid circulation rate parameter to operate efficiently at low circulation rates. The co-current contacting systems with in-line droplet generators are designed to achieve effective mass transfer and separation with minimal liquid flow, making the system efficient for low hydrocarbon concentration applications where conventional columns would require excessive liquid circulation.
Solution Approach 2:
The invention uses advanced hydraulic principles in the co-current contacting systems, utilizing high-velocity fluid flow and droplet generation mechanisms to enhance mass transfer efficiency. This allows effective separation with reduced liquid circulation requirements compared to conventional tray or packing-based systems.
3Productivity
If traditional scrub columns with large diameters are used, then processing capacity is maintained, but the system size and capital expenditures increase significantly
Solution Approach 1:
The invention changes the velocity parameter to operate at higher fluid velocities in compact in-line systems. By increasing velocity and using co-current contacting with droplet generators, the system achieves the required processing capacity in a much smaller footprint, eliminating the need for large diameter columns while maintaining throughput.
Solution Approach 2:
The invention segments the fractionation function into multiple compact in-line contacting stages rather than using a single large column. The co-current contacting systems can be arranged in series or parallel configurations that provide the necessary separation capacity in a distributed, space-efficient manner, reducing overall system size and capital cost.
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 results in a more compact, cost-effective, and efficient system for removing heavy hydrocarbons, suitable for space-limited applications and low liquid circulation rates, with a significant reduction in capital expenditures and operational flexibility.
Implementation Method 1
Each droplet generator includes an annular support ring securing the droplet generator in-line within the pipe, a plurality of spokes extending from the annular support ring, the annular support ring having a plurality of liquid channels configured to allow a liquid stream to flow through the plurality of spokes and out of injection orifices disposed on the plurality of spokes
Implementation Method 2
The mass transfer section provides a mixed, two-phase flow having a vapor phase and a liquid phase
Implementation Method 3
The separation system separates the vapor phase from the liquid phase
Implementation Method 4
In the rectification section 104, packing 118 is typically used instead of trays because of the low liquid circulation rate. The rectification section 104 includes several theoretical separation stages (typically two to four) where, based on the different boiling points of the components in the stream going to that separation stage, the fractionation/separation of hydrocarbons takes place
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
A fractionation system (400) for removing heavy hydrocarbons in a gas stream. A stripping section (402) receives a predominantly liquid phase of a feed gas stream. First and second co-current contacting systems (421a and 421b) are located in-line within a pipe. The first co-current contacting system (421a) receives a predominantly vapor phase (420) of the feed gas stream. Each co-current contacting system includes a co-current contactor (428) and a separation system (432). Each co-current contactor includes a droplet generator and a mass transfer section (430). The droplet generator generates droplets from a liquid and disperses the droplets into a gas stream. The mass transfer section provides a mixed, two-phase flow having a vapor phase and a liquid phase. The separation system separates the vapor phase from the liquid phase.