Horizontal Gas Flotation Separator for FPSO Oil-Water Separation
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Solution Overview
Problem
Current oil-water separation technologies in the petroleum industry, such as API gravity separation tanks, corrugated plate interceptors, induced gas flotation, and induced static flotation systems, are ineffective in removing oil droplets smaller than 20 microns and face challenges with flow surges and retrofit capabilities, particularly in the context of Floating Production, Storage and Off-loading (FPSO) ships where space and weight constraints are significant.
Innovation Solution
A high-performance gas flotation separator system with a plurality of chambers, featuring a central void for gas bubble injection, vertical riser conduits, and a baffle wall to enhance separation efficiency, allowing for easy integration into existing tank configurations, including FPSO hulls, with minimal modifications and cost-effective solutions for portable use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional gravity separation tanks are used, then larger oil droplets can be removed, but oil droplets smaller than 20 microns cannot be effectively removed and substantial retention times are required
Solution Approach 1:
The patent introduces gas bubbles into the produced water stream to create induced gas flotation. The gas bubbles attach to small oil droplets and carry them to the surface for removal, enabling effective separation of oil droplets smaller than 20 microns without requiring substantial retention times. This pneumatic approach overcomes the limitation of traditional gravity separation.
2Area of stationary object
If corrugated plate interceptors are used, then vessel footprint is reduced, but oil droplets smaller than 50 microns cannot be removed and chemical usage is increased
Solution Approach 1:
The patent uses induced gas flotation with carefully controlled gas bubble sizes and injection rates to remove oil droplets of various sizes, including those smaller than 50 microns. This pneumatic method achieves superior oil droplet removal efficiency compared to corrugated plate interceptors while maintaining a compact vessel footprint and reducing chemical usage.
3Manufacturing precision
If induced gas flotation is used, then oil droplet removal is enhanced, but the system cannot be efficiently employed in retrofit situations
Solution Approach 1:
The patent divides the flotation system into modular components including separate gas injection systems, bubble generation units, and skimming mechanisms. This segmentation enables the system to be retrofitted into existing vessels and tanks by installing modular components without requiring complete system replacement, thus achieving both enhanced oil droplet removal and retrofit capability.
4Use of energy by moving object
If induced static flotation is used, then gas bubbles are generated hydraulically, but the system has difficulty coping with oil concentrations above 300 ppm and flow rate fluctuations
Solution Approach 1:
The patent implements a dynamic gas injection system that can adjust gas flow rates and bubble generation rates in response to varying oil concentrations and flow rates. The system includes adjustable parameters such as gas injection rate, bubble size distribution, and residence time to adapt to different operating conditions, thereby coping effectively with oil concentrations above 300 ppm and flow rate fluctuations.
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 system effectively removes immiscible fluids and solid contaminants from produced water with improved surge capacity, reduced spatial requirements, and flexibility in handling flow fluctuations, enhancing oil skimming methods and accommodating wave motion without major internal modifications.
Implementation Method 1
A high-performance gas flotation separator system with a plurality of chambers, featuring a central void for gas bubble injection
Implementation Method 2
gas bubbles arranged to inject gas bubbles into the injection line... allowing for easy integration into existing tank configurations
Implementation Method 3
liquid purification or separation between a primary aqueous phase and an immiscible contaminant phase by means of flotation affected by the addition of chemical flocculating agents
Implementation Method 4
API and gravity separation tanks, such as a 'skim tank'. This technology is relatively simple and inexpensive, depending on the different densities of oil and water to enable gravity separation
Data Source
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Figure 5
AI summary
A gas flotation separator for use in horizontal tanks, such as those used for oil storage on board Floating Production Storage and Off-loading (FPSQ) vessels, includes dividing the tank into a plurality of chambers operating in series. Prior to entering each chamber, the contaminated aqueous phase is mixed with a stream containing gas bubbles to aid in flocculation and flotation of the immiscible phase contaminant. The gas bubble recycle stream can be generated by injecting a controlled rate of a pressurized gas into a liquid stream of the clean produced water in a process external to the tank or by induction of a gas phase internal to the tank. The mixture flows into the first chamber and impinges on an angled inlet water weir. A portion of the immiscible phase and the gas phase rises to the top of the chamber while the remaining immiscible contaminants flow downward with the aqueous phase to the bottom of the chamber. The aqueous phase makes a 180° turn upward by entering a plurality of parallel flow conduits formed into the wall of the baffle that separates the each series chamber. In each parallel duct a second gas bubble stream is injected to further aid in flocculation and flotation of the immiscible contaminants. The aqueous phase remixes at the top of the second chamber where it impinges on a second angled weir. This process is repeated in each series chamber until the last chamber where the cleaned water is pumped out of the chamber via a liquid pump. Varying the rate of water removal there from controls the water level in last chamber. The flocculated and floating oil contaminant can be removed by either 1) periodic skimming into an over-flow weir by raising the water level in the chamber, or 2) a continuously rotating paddle or brush object that lifts or carries the floating oil layer away from the water surface and transfers it to a collector system.