Supercritical CO2 Pipe Flushing for Wax Removal
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Solution Overview
Problem
Long, narrow pipes in hydraulic systems, such as those used in the offshore industry, face challenges in maintaining cleanliness due to the accumulation of wax or grease, which can lead to reduced operational capacity and risk of contamination, as conventional cleaning methods like turbulent flow are ineffective in achieving sufficient flow speeds to remove particulate contaminants.
Innovation Solution
The method involves using supercritical carbon dioxide (SCCO2) or liquid carbon dioxide (LCO2) to clean and flush long, narrow pipes by adjusting temperature and pressure to achieve turbulent flow, which effectively dissolves and removes wax, grease, and particulate contaminants, even in pipes longer than 500 meters with diameters less than 10 mm, by maintaining a high Reynolds number and ensuring the fluid remains in a supercritical state to minimize pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If turbulent flow is used to clean pipe systems, then contaminants are loosened and flushed away, but pressure drop in long, narrow pipes prevents maintaining sufficient flow speed
Solution Approach 1:
The patent changes the physical parameters of the cleaning fluid by using supercritical carbon dioxide, which has lower viscosity than conventional liquids. This parameter change reduces the pressure drop in long pipes while maintaining turbulent flow conditions necessary for effective contaminant removal
Solution Approach 2:
The patent utilizes the phase transition properties of carbon dioxide, transitioning it to a supercritical state. This phase transition enables the fluid to achieve both liquid-like density for effective cleaning and gas-like low viscosity for reduced pressure drop in long pipe systems
2Speed
If flow speed is increased to maintain turbulent flow in long pipes, then cleaning effectiveness improves, but pressure required exceeds pipe withstand capacity
Solution Approach 1:
The patent changes the viscosity parameter of the cleaning fluid by using supercritical CO2, which has significantly lower viscosity than conventional liquids. This allows maintaining turbulent flow at lower speeds and pressures that do not exceed pipe withstand capacity
3Reliability
If conventional liquid CO2 is used for cleaning, then contaminants are loosened, but pressure drop prevents effective flushing in long pipes
Solution Approach 1:
The patent transitions CO2 from liquid phase to supercritical phase, which fundamentally changes the fluid's viscosity characteristics. This phase transition enables effective contaminant removal while minimizing pressure drop in long pipe systems
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 ensures thorough removal of contaminants, achieving a high level of cleanliness, such as NAS 1638 Class 4, with reduced pressure drop and viscosity, making it more robust and economically viable for long pipes, while maintaining the fluid in a supercritical state to ensure effective flushing.
Implementation Method 1
supercritical carbon dioxide (SCCO2) or liquid carbon dioxide (LCO2) to clean and flush long, narrow pipes by adjusting temperature and pressure to achieve turbulent flow, which effectively dissolves and removes wax, grease, and particulate contaminants
Implementation Method 2
by adjusting temperature and pressure to achieve turbulent flow, which effectively dissolves and removes wax, grease, and particulate contaminants
Data Source
Figure 1
Figure 2
AI summary
Use of supercritical CO2 for cleaning long, narrow pipes with a cross sectional area of less than 1000 square mm and a length of more than 500 meter. Cleaning is performed by adding a fluid to the lumen of the pipe (140); providing the fluid (2) in a supercritical state (6) inside the lumen; and subsequently, as a flushing step, while the fluid is in the supercritical state or in a liquid state, displacing the fluid (2) in the lumen of the pipe (140) and out of lumen of the pipe at a speed that causes a turbulent flow of the fluid, thereby flushing particles out of the lumen.