Ceramic Membrane Pretreatment for High-Nitrogen Natural Gas
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Solution Overview
Problem
Existing methods for separating nitrogen from natural gas with high nitrogen content in natural gas networks or liquefaction processes are costly and complex, requiring additional stages and compression, leading to high operating and capital expenses, and are not efficient in meeting product specifications.
Innovation Solution
A process using ceramic membranes for permeative separation of hydrocarbon-rich, nitrogen-containing feed fractions into nitrogen-depleted and nitrogen-enriched streams, optionally combined with ceramic and non-ceramic membranes, followed by cryogenic separation and carbon dioxide removal, to achieve high nitrogen removal efficiency and reduce downstream processing requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional NRU process is used for high nitrogen content feed gas, then nitrogen separation is achieved, but compressor energy costs and capital investment are excessively high
Solution Approach 1:
The process segments the nitrogen separation task into two distinct stages: first, a membrane separation unit that removes a significant portion of nitrogen at lower compression ratios, and second, a cryogenic NRU that handles the remaining nitrogen removal. This segmentation allows each unit to operate in its optimal efficiency range, reducing overall compressor energy requirements while maintaining high nitrogen separation efficiency.
Solution Approach 2:
The membrane separation unit performs preliminary nitrogen removal before the feed gas enters the cryogenic NRU. By removing a substantial portion of nitrogen in advance at lower pressures, the subsequent cryogenic separation operates on a feed with reduced nitrogen content, thereby reducing the energy demand and capital cost of the compressor system.
2Manufacturing precision
If conventional NRU process is used for high nitrogen content feed gas, then nitrogen separation is achieved, but plant complexity and capital investment increase
Solution Approach 1:
The plant is divided into modular units: a membrane separation section and a cryogenic NRU section. This modular segmentation allows for more manageable plant design, operation, and maintenance, reducing overall complexity while achieving the required nitrogen separation efficiency for high nitrogen content feed gases.
3Manufacturing precision
If single-stage rubber membrane process is used for low nitrogen content feed gas, then product purity is achieved, but it becomes insufficient for high nitrogen content feed gas
Solution Approach 1:
The separation process is segmented into a membrane stage followed by a cryogenic stage. The membrane stage handles the bulk nitrogen removal effectively, while the cryogenic stage provides the final polishing to achieve product specifications. This segmented approach enables the system to handle both low and high nitrogen content feed gases adaptively.
Solution Approach 2:
The process employs a composite separation approach combining membrane technology and cryogenic technology. Each technology has its strengths: membranes excel at preliminary separation, while cryogenic processes excel at achieving high purity. By combining these technologies, the system achieves both product purity and adaptability to various feed gas compositions.
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
Reduces compressor energy and investment costs, allows rapid start-up, minimizes flaring, and provides robust operation with lower equipment needs, achieving high methane recovery rates and product purity.
Implementation Method 1
the permeative separation is carried out by means of at least one ceramic membrane
Implementation Method 2
followed by cryogenic separation and carbon dioxide removal
Implementation Method 3
Carbon dioxide is typically removed through an amine scrubber, which includes several different columns... The carbon dioxide is typically removed through an amine scrubber, which includes several different columns, such as a scrubbing and regeneration column. In addition, multiple pumps, heat exchangers, and vessels are required. This process uses a chemical solvent to chemically absorb acidic gas components, such as carbon dioxide, to form a chemical compound that is then separated from the natural gas.
Implementation Method 4
the water is removed using an adsorption process, preferably a TSA process. An adsorption process typically involves two or more adsorption vessels, each containing a bed of solid adsorption material. The natural gas stream is passed through one of the adsorbers, where the water molecules are adsorbed on the surface of the adsorption material.
Data Source
Figure 1~3
AI summary
A process is described for separating a hydrocarbon-rich, nitrogen-containing feed fraction (1), preferably natural gas, in which the feed fraction (1) is permeatively (M, M') separated into a nitrogen-depleted retentate fraction (2) and a nitrogen-enriched permeate fraction (3), wherein the permeative separation is carried out by means of at least one ceramic membrane (M, M').