Methane-Rich Fraction Superheating for Stable Nitrogen Removal
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Solution Overview
Problem
Existing methods for separating a nitrogen-rich fraction from a feed fraction containing nitrogen and hydrocarbons face challenges in maintaining the purity and mechanical integrity of heat exchangers due to fluctuations in process conditions, leading to disturbances in the heat balance and potential damage from rapid temperature changes.
Innovation Solution
The method involves feeding the still liquid or partially vaporized methane-rich fraction to a circulation tank, where only the liquid portion is partially evaporated and then superheated, dividing the heat exchanger path into an evaporation section and an overheating section to control the evaporation and superheating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the methane-rich fraction is completely vaporized and superheated in a continuous heat exchanger, then the process efficiency is improved, but the heat balance is disturbed when process conditions change, leading to purity loss and mechanical stress
Solution Approach 1:
The heat exchanger path is divided into two distinct sections: an evaporation section where the liquid methane-rich fraction is vaporized, and a superheating section where the vapor is superheated. This segmentation allows each section to be optimized for its specific function and prevents disturbances in one section from affecting the other, thereby maintaining purity and mechanical integrity while preserving process efficiency.
Solution Approach 2:
A circulation tank is introduced as an intermediary component between the heat exchanger and the process stream. The circulation tank buffers fluctuations in process conditions and maintains a stable heat balance, preventing rapid temperature changes that could damage the heat exchanger or compromise product purity.
2Speed
If the methane-rich fraction is rapidly heated to high temperature, then the evaporation speed is improved, but thermal shock damages the heat exchanger
Solution Approach 1:
The heating process is segmented into two stages: rapid vaporization in the evaporation section, followed by controlled superheating in the superheating section. This staged approach maintains high evaporation speed while preventing thermal shock to the heat exchanger through gradual temperature increase in the second stage.
Solution Approach 2:
The circulation tank serves as a cushioning element that absorbs and dampens rapid temperature changes before they reach the heat exchanger. This beforehand cushioning protects the heat exchanger from thermal shock while still allowing rapid evaporation to occur.
3Use of energy by moving object
If complex heat integration is used to achieve high efficiency, then energy utilization is improved, but the process becomes more sensitive to condition fluctuations
Solution Approach 1:
The circulation tank acts as a buffer that decouples the complex heat integration system from process condition fluctuations. It maintains stable operating conditions for the heat exchanger while allowing the rest of the process to respond to changes, thereby preserving energy efficiency without sacrificing adaptability.
Solution Approach 2:
The system allows for independent optimization of temperature and pressure parameters in the evaporation and superheating sections. By changing parameters in one section without affecting the other, the system maintains energy efficiency while adapting to varying process conditions.
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 stabilizes the evaporation process, maintains the purity of nitrogen-rich and methane-rich fractions, and enhances mechanical robustness while requiring minimal additional energy, even under changing operating conditions.
Implementation Method 1
only the liquid portion is partially evaporated
Implementation Method 2
The completely evaporated methane-rich top product drawn off via line 7 at the top of the circulation tank D is then superheated in the heat exchanger E1
Implementation Method 3
The feedstock fraction... is fed via line 1 to a heat exchanger E1 and fed there against process streams, which will be discussed in more detail below, be received, cooled and partially condensed
Data Source
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AI summary
The invention relates to a method for removing a nitrogen-rich fraction from a feed fraction which substantially contains nitrogen and hydrocarbons. According to said method, the feed fraction is subjected to separation into a nitrogen-rich and a methane-rich fraction by rectification, the methane-rich fraction being evaporated and then superheated at as high a pressure as possible relative to the feed fraction to be cooled for refrigeration. The still liquid or partially evaporated methane-rich fraction (5') is supplied to a circulation container (D), only the liquid portion of the methane-rich fraction (5') accumulated in the circulation container (D) is completely evaporated preferably in natural circulation and the top product (7) of the circulation container (D) is superheated (E1).