Process and apparatus for producing low-nitrogen synthesis gas from nitrogen-containing natural gas
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Solution Overview
Problem
Current methods for producing low-nitrogen synthesis gas require high energy and economic costs due to the need for additional equipment and regenerating gases, particularly nitrogen, which is costly and inefficiently used in temperature swing adsorption plants for water and carbon dioxide removal.
Innovation Solution
Using low-nitrogen, water-free, and carbon dioxide-free natural gas as the regenerating gas in temperature swing adsorption plants, which eliminates the need for external nitrogen supply and optimizes the regeneration process by limiting temperatures and adjusting gas flows, thereby reducing energy consumption and equipment requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nitrogen is removed from crude syngas downstream of thermochemical conversion, then low-nitrogen synthesis gas is obtained, but high apparatus requirements (cryogenic gas fractionator, PSAP, recycle compressor) and high energy consumption result
Solution Approach 1:
The patent applies preliminary action by removing nitrogen from natural gas before thermochemical conversion in a cryogenic gas fractionator, rather than from crude syngas after conversion. This upstream removal prevents nitrogen from entering the conversion process, eliminating the need for downstream separation equipment like cryogenic gas fractionators and PSAP units, while achieving the same goal of producing low-nitrogen synthesis gas
2Quantity of substance
If nitrogen is removed from crude syngas downstream of thermochemical conversion, then low-nitrogen synthesis gas is obtained, but high energy consumption due to high reflux ratio and multiple separation stages results
Solution Approach 1:
The patent performs nitrogen removal before thermochemical conversion, avoiding the need for energy-intensive downstream separation processes. The cryogenic gas fractionator operates with lower energy requirements because it separates nitrogen from natural gas components with simpler composition, rather than separating nitrogen from complex crude syngas containing hydrogen, carbon monoxide, carbon dioxide, and water
Solution Approach 2:
The patent changes the operating parameters of the cryogenic gas fractionator by operating without reflux or with minimal reflux, and by using a smaller number of separation stages, thereby significantly reducing energy consumption while still achieving effective nitrogen removal from natural gas
3Quantity of substance
If regenerating gas in temperature swing adsorption plants is supplied from external sources, then water and carbon dioxide removal is achieved, but high economic costs due to costly and inefficient nitrogen use results
Solution Approach 1:
The patent applies self-service by using the produced low-nitrogen synthesis gas itself as the regenerating gas for the temperature swing adsorption plants, creating a closed internal loop. This eliminates the need for external nitrogen supply, reduces operational costs, and improves efficiency by utilizing a gas stream already present in the process
Solution Approach 2:
The low-nitrogen synthesis gas serves multiple functions: it is both the product stream and the regenerating gas for water and carbon dioxide removal. This multi-functionality reduces the need for separate utility streams and decreases overall process costs
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 significantly reduces the economic and environmental impact by utilizing the natural gas to meet regenerating gas demands, minimizing the need for additional nitrogen and reducing operational costs, while ensuring efficient water and carbon dioxide removal without affecting synthesis gas composition.
Implementation Method 1
water and carbon dioxide are removed in a first temperature swing adsorption plant
Implementation Method 2
nitrogen is removed in a cryogenic gas fractionator... carbon monoxide and nitrogen are separated in a column by rectification, which can only be achieved with a high reflux ratio and/or many separation stages in the column due to the very similar boiling temperatures of the two substances
Implementation Method 3
low-nitrogen synthesis gas is obtained at least by the removal of water and carbon dioxide in a second temperature swing adsorption plant
Data Source
AI summary
Process and apparatus for producing a low-nitrogen synthesis gas from a natural gas containing nitrogen and carbon dioxide, from which water and carbon dioxide are removed in a first temperature swing adsorption plant and subsequently nitrogen is removed in a cryogenic gas fractionator, to give a low-nitrogen, water-free and carbon dioxide-free natural gas, which is next supplied to a thermochemical conversion, so as to recover a crude syngas comprising hydrogen, carbon monoxide, water and carbon dioxide, from which the low-nitrogen synthesis gas is obtained at least by the removal of water and carbon dioxide in a second temperature swing adsorption plant. The characteristic feature here is that at least a part of the low-nitrogen, water-free and carbon dioxide-free natural gas prior to its thermochemical conversion is used as regenerating gas in the regeneration of the first and/or second temperature swing adsorption plant.