Liquid CO2 Offshore Transfer System Pressure Control
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Solution Overview
Problem
Transporting large quantities of liquid carbon dioxide from industrial sites to offshore injection wells poses challenges due to high pressures required for maintaining the liquid state, which leads to expensive container costs and risks of solid carbon dioxide formation, and existing transfer systems are not suitable for the pressures and risks associated with liquid carbon dioxide.
Innovation Solution
A process and apparatus for transferring liquid carbon dioxide from a water-going transport vessel to an offshore injector well-head using a conduit with a flexible section, multiple pumps, a heater, and an expansion tank to regulate pressure, ensuring the carbon dioxide remains in a sub-critical state and avoiding solid formation, with on-board heating to prevent conduit icing and solid formation, and backflow lines to maintain pressure and flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If liquid CO2 is transported at high pressures (60-70 bar) without refrigeration, then container wall thickness and cost increase significantly, but refrigeration equipment and operating costs are avoided
Solution Approach 1:
The patent changes the temperature parameter from ambient to sub-ambient (refrigerated) conditions, which allows transport at lower pressures (5.5-7.5 bar instead of 60-70 bar). This parameter change resolves the contradiction by reducing pressure requirements while accepting refrigeration costs, making large-scale CO2 transport feasible.
2Stress or pressure
If liquid CO2 is refrigerated to reduce transport pressure, then transport pressure and container cost decrease, but refrigeration equipment cost and operating expense increase
Solution Approach 1:
The patent applies refrigeration to lower the temperature parameter, which enables transport at reduced pressures (5.5-7.5 bar). This resolves the contradiction by accepting increased refrigeration costs in exchange for dramatically reduced pressure requirements and thinner container walls.
3Stress or pressure
If liquid CO2 temperature is lowered to reduce pressure requirements, then transport pressure decreases, but the risk of solid CO2 formation increases
Solution Approach 1:
The patent carefully controls the temperature parameter to be below ambient but above the triple point (−56.6° C.), and maintains pressure above the triple point pressure (5.2 bar). This parameter control strategy resolves the contradiction by reducing pressure requirements while preventing solid CO2 formation through proper positioning on the phase diagram.
Solution Approach 2:
The patent implements monitoring and control systems to maintain temperature and pressure within safe operating ranges, preventing conditions that would lead to solid CO2 formation. This feedback mechanism resolves the contradiction by dynamically adjusting parameters to avoid the harmful phase transition.
4Adaptability or versatility
If existing LPG transfer apparatus are used for LCD transfer, then equipment availability is maintained, but the system is unsuitable due to higher pressures and solid formation risks associated with LCD
Solution Approach 1:
The patent develops transfer apparatus specifically designed for LCD that can handle the higher pressures and temperature control requirements. The system is designed to be adaptable to different liquefied gases while incorporating specific features for LCD safety, resolving the contradiction between equipment availability and suitability.
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
Enables safe and efficient transfer of liquid carbon dioxide, reducing container costs and risks, while maintaining the carbon dioxide in a liquid phase during transport and injection, thus optimizing the transfer process and avoiding environmental release.
Implementation Method 1
using a heater heating the liquid carbon dioxide before it reaches the third pump
Implementation Method 2
using the first pump, pumping liquid carbon dioxide from the container along the conduit to the second pump
Implementation Method 3
using the expansion tank to regulate the pressure in the conduit upstream of the third pump
Data Source
AI summary
A water-going liquefied carbon dioxide (LCD) transport vessel having a pressurized and refrigerated LCD container, a cargo discharge pump within the container for pumping LCD out of] the container along a conduit, a booster pump for pumping LCD along the conduit to a platform, a first backflow line downstream of the cargo pump to the container, a second backflow line from downstream of the booster pump to the container, and optionally a heater arranged to heat LCD flowing from the vessel along the conduit.