CO/N2 Distillation Column With External Reboiler for CO Purity
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Solution Overview
Problem
In syngas production processes, especially when methane content is low and nitrogen content is not compatible with CO purity, existing methods for CO/N2 separation are inefficient, leading to increased energy consumption and impure CO products.
Innovation Solution
A partial condensation unit with a CO/N2 column incorporating an external reboiler for energy-efficient CO/N2 separation, where the feed gas is cooled and partially condensed, then processed through a series of phase separators and distillation columns to separate nitrogen and carbon monoxide, reducing the energy burden on the compressor by up to 15%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a CO/N2 separation column is added to the cold box, then CO purity is improved, but energy consumption increases
Solution Approach 1:
The patent combines the CO/N2 separation column with the existing cold box unit into an integrated system. The separation column is thermally coupled with the cold box components, allowing heat integration where the cold box provides cooling for the separation column while the separation column's reboiler utilizes process heat. This merging reduces overall energy consumption compared to standalone separation while achieving the required CO purity.
Solution Approach 2:
The patent optimizes operating parameters including temperature, pressure, and flow rates across the separation column and cold box components. By carefully controlling the temperature profile in the separation column and coordinating it with the cold box operating parameters, the system achieves efficient CO/N2 separation with minimized energy input. The reboiler temperature and condenser pressure are specifically tuned to maximize separation efficiency while minimizing compressive work requirements.
2Manufacturing precision
If nitrogen content in syngas is high, then CO purity deteriorates, but adding separation equipment increases device complexity
Solution Approach 1:
The cold box unit is designed to serve multiple functions simultaneously: it provides refrigeration for the CO/N2 separation column, acts as a heat exchanger for process cooling, and integrates the separation column itself. This multi-functionality means that the same equipment infrastructure handles both thermal management and separation tasks, avoiding the need for separate dedicated separation equipment and thus reducing overall device complexity while maintaining high CO purity.
3Productivity
If direct feed of CO at medium pressure is used for reboiling, then separation efficiency is improved, but compressor energy consumption increases
Solution Approach 1:
The system performs preliminary cooling and partial condensation of the syngas feed in the cold box before introducing it to the separation column. This preliminary action prepares the feed at optimal temperature and phase conditions, reducing the subsequent reboiling requirements and minimizing the compressive work needed to achieve the desired separation efficiency. The feed is pre-conditioned to require less energy input in the separation stage.
Solution Approach 2:
The patent introduces an intermediary thermal management system consisting of heat exchangers and a reboiler that mediates between the compressor output and the separation column. Instead of directly feeding compressed CO into the reboiler, the system uses heat exchangers to transfer thermal energy efficiently and a controlled reboiling process that minimizes additional compression requirements. This intermediary approach decouples the compression function from the reboiling function, allowing each to be optimized independently.
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 solution enables energy-efficient CO/N2 separation, reducing the energy required for compressor operation and improving CO product purity by integrating a CO/N2 column with a common cycle for cooling and reboiling, suitable for both standalone and integrated CO/CH4 column configurations.
Implementation Method 1
the feed gas is cooled in a heat exchanger
Implementation Method 2
at least one portion of the feed gas or at least one portion of a gas derived from the feed gas is sent to a bottom reboiler of the distillation column in order to condense it at least partially
Implementation Method 3
The at least partially condensed stream is expanded in a valve
Implementation Method 4
a stream of nitrogen and carbon monoxide is cooled in a heat exchanger. It is at least partially condensed in a reboiler fed by the bottoms liquid from the column
Implementation Method 5
A stream of nitrogen is removed as a purge and is heated in the heat exchanger
Implementation Method 6
The vaporized carbon monoxide is also heated in the heat exchanger and is compressed in the first stage of a compressor
Data Source
AI summary
A method for separating a feed gas, containing nitrogen and carbon monoxide as main components, in a distillation column: the feed gas is cooled in a heat exchanger; at least a portion of the feed gas, or at least a portion of a gas derived from the feed gas, is sent to a reboiler of the distillation column so as to condense the gas while producing a liquid, and optionally a gas; at least a portion of the liquid is sent to the distillation column; a nitrogen gas-rich flow is extracted from the distillation column; a carbon monoxide-rich flow is extracted from the distillation column, heated in the heat exchanger, and compressed so as to provide a carbon monoxide-rich material at production pressure.