Compact Co-Current H2S Scavenging System
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Solution Overview
Problem
Current hydrogen sulfide (H2S) scavenging technologies, such as those using triazine, face challenges with high capital and operational costs, weight, and efficiency issues, particularly in compact applications like offshore and subsea processing, and struggle with mercaptan removal and solid formation.
Innovation Solution
A compact co-current contacting system is introduced, featuring a droplet generator and mass transfer section within a pipe, which generates droplets from a liquid scavenger and disperses them into the gas stream, creating a two-phase flow for efficient H2S and mercaptan removal, using triazine or caustic as scavengers, and includes a separation system to isolate the gas and liquid phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional continuous contact systems use large contactors and separators, then H2S scavenging efficiency is improved, but capital costs and equipment weight increase
Solution Approach 1:
The system divides the scavenging process into multiple compact contactors connected in series, each handling a portion of the gas stream. This segmentation allows achieving high scavenging efficiency through multiple stages of contact rather than requiring a single large contactor, thereby reducing overall equipment weight while maintaining productivity.
Solution Approach 2:
The contactors are designed to be nested or modular units that can be compactly arranged. The in-line configuration allows one contactor to be positioned within the flow path of another, creating a space-efficient system that achieves effective H2S removal without requiring large external equipment, thus reducing weight and capital costs.
2Productivity
If conventional systems use large contactors and separators, then H2S scavenging efficiency is improved, but capital expenditures increase
Solution Approach 1:
By segmenting the scavenging function across multiple smaller contactors, the system reduces the capital cost of individual equipment pieces while maintaining high overall efficiency. Smaller units are generally less expensive to manufacture and install than large vessels, and the modular approach allows for easier fabrication and assembly.
Solution Approach 2:
Multiple contactor functions are merged into a single integrated system with common inlet and outlet manifolds. This combining approach reduces the total number of separate equipment items, simplifies installation, and lowers capital expenditures while preserving the high scavenging efficiency achieved through multi-stage contact.
3Ease of manufacture
If direct injection of triazine into pipeline is used, then capital investment is reduced, but contact effectiveness decreases and scale formation increases
Solution Approach 1:
The contactors serve as intermediary devices that facilitate effective contact between the triazine solvent and the gas stream. Rather than direct injection into the pipeline, the contactors provide a dedicated space where the solvent can mix with the gas, enhancing contact effectiveness and preventing scale formation on pipeline walls while maintaining low capital investment.
Solution Approach 2:
The system replaces the mechanical approach of direct injection with a chemical mass transfer approach in controlled contactors. This substitution allows for better control of contact conditions, improving scavenging efficiency and reducing scale formation issues associated with direct pipeline injection.
4Ease of manufacture
If batch contact towers are used, then capital costs are reasonable, but downtime increases due to frequent changes
Solution Approach 1:
The system transitions from static batch operation to dynamic continuous operation. The contactors are designed to handle continuous gas flow with continuous solvent circulation, eliminating the need to shut down and change towers frequently. This dynamic approach maintains reasonable capital costs while significantly reducing downtime and improving operational flexibility.
Solution Approach 2:
The system implements continuous scavenging operation where the contactors process gas continuously without interruption. The solvent circulates continuously through the contactors, maintaining constant H2S removal capability. This continuity eliminates the stop-start nature of batch operations, reducing downtime and improving productivity while keeping capital costs manageable.
5Loss of time
If two towers in lead-lag arrangement are used, then downtime is reduced, but capital costs double
Solution Approach 1:
Multiple contactor units are merged into a single operational train with shared inlet and outlet systems. This unified design allows one contactor to be cleaned or maintained while others continue operating, reducing downtime without requiring duplicate complete tower systems. The merged approach achieves operational flexibility at lower capital cost than having separate lead-lag tower pairs.
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 solution reduces capital expenditures, enhances processing capacity in space-limited areas, and effectively removes H2S and mercaptans with reduced solvent usage and solid formation, suitable for remote and offshore applications.
Implementation Method 1
a droplet generator configured to generate droplets from the liquid scavenger stream and to disperse the droplets into the natural gas stream
Implementation Method 2
the liquid phase includes the liquid scavenger stream with H2S, mercaptans, and/or other sulfur-containing compounds absorbed from the natural gas stream
Implementation Method 3
a separation system configured to separate the vapor phase from the liquid phase
Data Source
AI summary
A hydrogen sulfide (H2S) scavenging system for removing H2S, mercaptans, and/or other sulfur-containing compounds from a natural gas stream. A co-current contacting system is located in-line within a pipe and receives the natural gas stream and a liquid scavenger stream. The co-current contacting system includes a co-current contactor including a droplet generator and a mass transfer section. The droplet generator generates droplets from the liquid scavenger stream and disperses the droplets into the natural gas stream. The mass transfer section provides a mixed, two-phase flow having a vapor phase and a liquid phase. The liquid phase includes the liquid scavenger stream with H2S, mercaptans, and/or other sulfur-containing compounds absorbed from the natural gas stream, and the vapor phase includes the natural gas stream. A separation system separates the vapor phase from the liquid phase.