System and method for liquefying production gas from a gas source
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Solution Overview
Problem
The costly and inefficient process of recovering and utilizing C1-C12 gases from various gas sources, where valuable natural and petroleum gases are often flared off or left in fluid suspension, due to ineffective separation methods.
Innovation Solution
A method and system involving multiple stages of cryogenic liquefaction, using plate exchangers and phase separators to separate and liquefy C3-C12 petroleum gases and C1-C2 natural gases, with the option of using liquid nitrogen or glycol for cooling, and incorporating scavengers and boosters to manage pressure and re-introduce gases for enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional separation methods are used for C1-C12 gases, then the process is simple, but the recovery efficiency is low and valuable gases are wasted
Solution Approach 1:
The separation process is divided into multiple stages: first phase separation to remove liquids and solids, second phase separation to separate C3-C12 from C1-C2, and optional third phase separation for further purification. Each stage uses different separation mechanisms (gravity settling, cryogenic condensation, molecular sieves) to progressively isolate different gas components, thereby improving overall recovery efficiency while managing complexity through modular design
Solution Approach 2:
The system utilizes temperature as a key parameter to control gas separation. By cooling the gas stream to cryogenic temperatures (below -100°C), C3-C12 hydrocarbons condense into liquid form while C1-C2 remain gaseous, enabling efficient separation. Temperature parameters are precisely controlled at different stages to optimize separation efficiency for different gas components
2Measurement precision
If multiple stages of cryogenic liquefaction are used, then gas separation efficiency is improved, but energy consumption increases
Solution Approach 1:
Before the cryogenic liquefaction stage, a first phase separation process removes liquid and solid contaminants from the gas stream. This preliminary action protects the cryogenic system from fouling and reduces the energy burden on subsequent stages by pre-conditioning the gas stream, thereby improving overall energy efficiency
Solution Approach 2:
Different separation mechanisms are applied to different gas components at different stages: gravity settling for liquid removal, cryogenic condensation for C3-C12 separation, and molecular sieve adsorption for C1-C2 purification. Each stage is optimized for its specific function, avoiding the energy waste of applying a single high-energy process to all separation tasks
3Object-affected harmful factors
If scavengers are injected to entrain H2S, then sulfur reactivity is reduced, but system complexity increases
Solution Approach 1:
A scavenger substance is introduced as an intermediary that selectively binds with H2S in the gas stream to form non-reactive compounds. This intermediary approach neutralizes the harmful effects of sulfur without requiring complex removal systems, as the scavenger-trap complex can be easily separated in the phase separation stages
Solution Approach 2:
The harmful H2S component is extracted from the main gas stream through chemical reaction with the scavenger. This extraction removes the problematic sulfur compounds before they can cause adverse reactions in downstream equipment, while the treated gas stream proceeds to cryogenic separation with minimal contamination
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 liquefies production gases, maximizing the recovery and utilization of valuable gases by efficiently separating and storing C3-C12 petroleum gases and C1-C2 natural gases, reducing waste and optimizing system efficiency through temperature control and gas management.
Implementation Method 1
The gas from the first phase separator is passed through a first stage of cryogenic liquefaction which cools the gas to create a fluid containing liquefied C3-C12 petroleum gas and a gaseous C1-C2 natural gas
Implementation Method 2
The first stage of cryogenic liquefaction cools the gas to between −42 and −126 degrees Celsius to cause liquefaction of the C3-C12 production gases
Implementation Method 3
the second stage of cryogenic liquefaction cools the gaseous C1-C2 natural gas to at least −162 degrees Celsius to create liquefied C1-C2 natural gas
Implementation Method 4
The second stage of cryogenic liquefaction cools the gaseous C1-C2 natural gas to at least −162 degrees Celsius to create liquefied C1-C2 natural gas
Implementation Method 5
liquid nitrogen is used during cryogenic liquefaction. In another embodiment, glycol that has been cooled by liquid nitrogen is used during cryogenic liquefaction
Data Source
AI summary
A method for liquefying production gas from a gas source containing a fluid having C1-C12 entrained gases includes passing the gas through a first stage of cryogenic liquefaction to cool the gas to a temperature between −50 degrees Celsius and −87 degrees Celsius to create a fluid containing a liquefied C3-C12 petroleum gas and a gaseous C1-C2 natural gas. The liquefied C3-C12 petroleum gas and gaseous C1-C2 natural gas are passed through a second phase separator to separate the liquefied C3-C12 petroleum gas from the gaseous C1-C2 natural gas. The liquefied C3-C12 petroleum gas is collected into liquefied petroleum gas storage vessels.