Methane-C2+ Separation Using Turboexpansion and Internal Refrigeration
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Solution Overview
Problem
Current methods for separating C2+ hydrocarbons from natural gas are inefficient in terms of energy consumption and require external refrigerants, limiting their applicability in economic and space-constrained environments such as floating installations or sensitive security areas.
Innovation Solution
A process that involves dynamic expansion turbines and heat exchangers to optimize the separation of methane and C2+ hydrocarbons without external refrigeration, utilizing internal energy recovery and efficient heat management to enhance ethane extraction yields while reducing installation size and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external refrigeration is used for hydrocarbon separation, then separation efficiency is improved, but energy consumption and installation size increase
Solution Approach 1:
The system uses self-service by utilizing the feed stream itself as the refrigerant source. The expansion turbine expands a portion of the feed stream to generate cold energy, which is then used to cool and condense other portions of the feed stream in heat exchangers, eliminating the need for external refrigeration systems
Solution Approach 2:
The system applies parameter changes by controlling the pressure and temperature of the feed stream through the expansion turbine. By adjusting the expansion ratio and pressure differential, the system generates the appropriate cold temperatures for condensation without external refrigeration, optimizing both energy consumption and separation efficiency
2Manufacturing precision
If external refrigeration is used for hydrocarbon separation, then separation efficiency is improved, but installation size increases
Solution Approach 1:
The system eliminates external refrigeration equipment by using the feed stream itself to provide cooling through the expansion turbine. This self-service approach removes the need for separate refrigeration compressors, condensers, and evaporators, significantly reducing installation footprint
Solution Approach 2:
The system merges the refrigeration function with the separation process by integrating the expansion turbine and heat exchangers directly into the hydrocarbon separation flow. The cooling and condensation functions are combined with the separation operations in a unified process train, reducing overall installation size
3Use of energy by stationary object
If dynamic expansion turbines are used, then energy consumption is reduced, but process complexity increases
Solution Approach 1:
The system recovers energy by capturing the expansion work from the expansion turbine and using it to drive compressors or generate electricity. This energy recovery offsets the additional complexity by providing useful work output, improving overall process efficiency
Solution Approach 2:
The expansion turbine serves multiple functions: it generates cold energy for condensation, produces mechanical work for energy recovery, and controls pressure differential for the separation process. This multi-functionality justifies the added complexity by eliminating the need for separate refrigeration and energy recovery 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
The process achieves significant energy savings and maintains high ethane extraction efficiency, reducing power consumption by up to 13,630 kW compared to prior art, while ensuring the separation of methane and C2+ hydrocarbons in a space-saving and economically viable manner.
Implementation Method 1
a fraction of this feed stream is expanded in a dynamic expansion turbine to a pressure close to the operating pressure of the distillation column to form an expanded fraction having a temperature below -50°C
Implementation Method 2
The expanded fraction is sent to a heat exchanger to be cooled and at least partially condensed by an auxiliary reboiling current taken from the distillation column
Implementation Method 3
The different effluents, after partial condensation, are combined to feed a gas-liquid separator. The light stream obtained at the top of the separator is divided into a first column feed fraction, which is condensed before being sent to the top feed of the distillation column
Data Source
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AI summary
Said method includes cooling the supply stream in a first heat exchanger (20), separating in a first disengager (22) so as to produce a light head stream (44) and a heavy foot stream (45), and dividing the light head stream (44) into a dynamic expansion turbine supply fraction (48) and into a supply fraction (46) for a first distillation column (30). The method includes forming a cooled ebb stream (56) from an effluent (54) of a dynamic expansion turbine (26), the portion of the effluent being cooled and at least partially liquefied in a heat exchanger (28). The method includes placing the cooled ebb stream (56) of the heat exchanger (28) into the first distillation column (30).