Hydrocarbon Purification via Thermal Swing Adsorption
Solution Overview
Problem
Existing methods for removing carbon dioxide from hydrocarbon streams with low concentrations face challenges such as inadequate wetting of packed beds and inefficiencies due to motion in offshore facilities, leading to increased capital and operating expenses, and result in hydrocarbon loss and waste streams.
Innovation Solution
The use of adsorption units with thermal swing adsorption techniques and solvent separation to selectively remove carbon dioxide from hydrocarbon streams, allowing for the recovery of hydrocarbons and minimizing equipment oversizing by separating carbon dioxide from a raffinate stream with higher concentrations, thereby avoiding inefficiencies associated with low carbon dioxide content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If amine solvent is used to remove carbon dioxide from hydrocarbon streams with low carbon dioxide content, then carbon dioxide removal is achieved, but the packed bed experiences inadequate wetting and reduced efficiency
Solution Approach 1:
The patent changes the operational parameters by using a solvent with higher carbon dioxide solubility (such as alkanolamines or carboxylic acids) and operating at elevated temperatures and pressures. This allows effective carbon dioxide removal even when the hydrocarbon stream has low carbon dioxide content, preventing inadequate wetting of the packed bed while maintaining removal efficiency.
Solution Approach 2:
The patent implements dynamic control of the solvent circulation rate and contact time in the packed bed. By adjusting these parameters dynamically based on the actual carbon dioxide concentration in the feed stream, the system maintains optimal wetting conditions and removal efficiency across varying operating conditions, including low carbon dioxide content scenarios.
2Reliability
If packed bed and pumps are oversized to account for offshore facility motion, then adequate wetting is maintained, but capital expense and operating expense increase
Solution Approach 1:
The patent applies preliminary stabilization measures by using a solvent system that maintains adequate wetting even under tilted conditions, and by pre-adjusting operating parameters to compensate for facility motion. This allows the use of properly-sized equipment rather than oversized equipment, reducing both capital and operating expenses while maintaining reliable operation under offshore motion conditions.
3Reliability
If amine solvent circulation rate is increased to maintain adequate wetting under tilted conditions, then packed bed wetting is improved, but operating expense increases
Solution Approach 1:
The patent implements dynamic adjustment of the solvent circulation rate based on actual operating conditions, including facility motion and carbon dioxide concentration. This allows the system to maintain adequate wetting only when and where needed, reducing unnecessary solvent recirculation and associated energy costs during normal operation while ensuring proper wetting under tilted conditions.
Solution Approach 2:
The patent changes the solvent system parameters by using solvents with higher carbon dioxide solubility and adjusted viscosity characteristics, which maintain adequate wetting at lower circulation rates. This reduces the energy required for solvent recirculation while maintaining packed bed performance under offshore facility motion conditions.
4Reliability
If membrane elements are used to separate carbon dioxide from hydrocarbon stream, then facility motion does not affect efficiency, but hydrocarbon loss occurs
Solution Approach 1:
The patent replaces the membrane separation mechanism with a packed bed absorption system using liquid solvent. This substitution allows for effective carbon dioxide removal without the hydrocarbon loss associated with membrane permeation, while maintaining efficiency under offshore facility motion through proper solvent circulation and contact time control.
Solution Approach 2:
The patent changes the separation mechanism from passive membrane permeation to active solvent absorption, utilizing controlled mass transfer parameters in a packed bed. This allows selective carbon dioxide removal with high efficiency and no hydrocarbon loss, while the system can be designed to be insensitive to facility motion through appropriate hydraulic design and solvent selection.
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 effectively reduces carbon dioxide levels in hydrocarbon streams to below 50 ppm, maximizes hydrocarbon yield, and reduces the need for oversized equipment and additional remediation steps, enhancing operational efficiency and minimizing waste.
Implementation Method 1
Carbon dioxide is selectively adsorbed from the hydrocarbon stream to produce a treated hydrocarbon stream that has less than or equal to 50 ppm by mole of carbon dioxide
Implementation Method 2
The adsorbed carbon dioxide is desorbed to produce a raffinate stream that includes the carbon dioxide
Implementation Method 3
The carbon dioxide is separated from the raffinate stream using a solvent separation technique to produce a treated raffinate stream
Data Source
AI summary
Methods and apparatuses for removing impurities from a hydrocarbon stream are provided herein. In an embodiment, a method for removing impurities from a hydrocarbon stream includes providing the hydrocarbon stream that includes carbon dioxide in an amount of greater than about 50 ppm by mole. Carbon dioxide is selectively adsorbed from the hydrocarbon stream to produce a treated hydrocarbon stream that has less than or equal to 50 ppm by mole of carbon dioxide. The adsorbed carbon dioxide is desorbed to produce a raffinate stream that includes the carbon dioxide. The carbon dioxide is separated from the raffinate stream using a solvent separation technique to produce a treated raffinate stream.