Petroleum Desalting via Modulated Voltage Field
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Solution Overview
Problem
Bilectric desalters face inefficiencies in handling heavy crude oils due to stable rag layer formation, which reduces dehydration and desalting performance, and limits water content to 10% to prevent electrode shorting.
Innovation Solution
Applying a modulating, high-frequency AC field using one to three power units to optimize electrostatic strength, promoting rag collapse and water droplet coalescence, allowing for effective desalting and dehydration of crude oils with up to 10% BS&W and preventing electrode shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a single-frequency AC voltage is applied to the electrodes, then the electrostatic field is stable, but the rag layer becomes stable and resistant to collapse, reducing desalting performance
Solution Approach 1:
The patent applies a modulating voltage field that dynamically changes in amplitude and/or frequency rather than using a static single-frequency AC voltage. This dynamic modulation prevents the rag layer from achieving stability, causing it to collapse and improving water separation efficiency while maintaining effective electrostatic field action.
Solution Approach 2:
The patent employs periodic modulation of the voltage field where the amplitude and/or frequency varies in a periodic manner. This periodic action disrupts the rag layer stability cycle, preventing the formation of a stable emulsion interface and enhancing the coalescence of water droplets for improved desalting.
2Ease of operation
If the AC voltage is increased to control rag layer formation, then rag layer control improves, but water droplets chain together and short the electrodes
Solution Approach 1:
By using a modulating voltage field with varying amplitude and frequency, the system can adaptively control the electrostatic field strength. This prevents water droplets from achieving stable chaining configurations that lead to shorting, while still maintaining sufficient field strength to control rag layer formation effectively.
Solution Approach 2:
The patent changes the parameters of the electrostatic field by modulating amplitude and frequency rather than using a fixed single-frequency voltage. This parameter modulation allows the system to operate in regimes that prevent water chaining and electrode shorting while maintaining rag layer control capability.
3Reliability
If the water content is limited to 10% to prevent water chaining, then electrode shorting is avoided, but the desalter cannot handle heavier crude oils with higher water cuts
Solution Approach 1:
The modulating voltage field dynamically adjusts the electrostatic forces acting on water droplets, preventing them from chaining together even at higher water contents. This enables the desalter to handle crude oils with water cuts exceeding 10% without experiencing electrode shorting, thereby expanding its adaptability to heavier crude oils.
Solution Approach 2:
By modulating the amplitude and frequency parameters of the applied voltage, the system creates an electrostatic field regime that suppresses water droplet chaining. This allows effective processing of crude oils with higher water content while maintaining reliability and preventing electrode shorting.
4Productivity
If a modulating voltage field is applied to collapse the rag layer, then desalting performance improves, but the power demand on the power unit increases
Solution Approach 1:
The periodic modulation of the voltage field creates cycles of enhanced electrostatic force that efficiently collapse the rag layer. By timing the modulation to coincide with critical moments in the water droplet coalescence process, the system achieves effective rag layer breakdown with optimized power consumption rather than requiring continuously high power levels.
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 modulating voltage field enhances coalescence efficiency, enabling effective removal of entrained salt with minimal water content and handling higher water cuts, improving desalting performance and preventing rag layer formation and electrode shorting.
Implementation Method 1
applying a modulating voltage to one or more horizontally oriented, spaced-apart electrodes housed within an elongated vessel and exposing the inlet crude oil stream entering the vessel to the electric field
Implementation Method 2
coalesces the dispersed water in an intense electrostatic field and has the advantage of achieving rapid and highly efficient droplet coalescence and separation
Implementation Method 3
Applying a modulating, high-frequency AC field using one to three power units to optimize electrostatic strength, promoting rag collapse and water droplet coalescence
Data Source
AI summary
A method of removing entrained salt containing water from an inlet crude oil stream includes the steps of applying an electrical energy to at least one electrode of a plurality of horizontally oriented, spaced-apart electrodes (12, 14, 16) housed within an elongated desalting vessel (10) and distributing an inlet crude oil stream between the electrodes. Each electrode in the plurality of electrodes is housed in an upper portion of the desalting vessel and may be in communication with a first, second and third transformer (42, 44, 46), respectively. The electrical energy may be at a single frequency and voltage or at a modulated voltage. Or, the electrical energy may be a modulated frequency at a single or modulated voltage. Fresh water may be mixed with the inlet crude oil stream either exteriorly or interiorly of the vessel.