Cryogenic CO Denitrification Reboiling with Variable Pressure Expansion
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Solution Overview
Problem
Current methods for separating carbon monoxide and nitrogen in cryogenic distillation face challenges due to close bubble points, leading to energy losses and inefficiencies in reboiling processes, particularly in denitrogenation columns where medium-pressure carbon monoxide vaporization is limited, resulting in increased energy consumption and compressor gas outlet requirements.
Innovation Solution
A method involving a system with a turbine, methane scrubbing column, stripping column, CO/CH4 column, and denitrogenation column, where high-pressure carbon monoxide is compressed and selectively expanded through a valve to adjust reboiling flow in the denitrogenation column, allowing for variable reboiling without destabilizing the exchange line, and redirecting high-pressure carbon monoxide to reboilers of other columns to optimize vaporization and reduce energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If medium-pressure carbon monoxide is vaporized in the exchange line to provide reboiling for the denitrogenation column, then refrigeration is provided and low-pressure carbon monoxide requirements are limited, but the vaporization capacity is constrained by exchange line limitations and reboiling fraction requirements, leading to energy losses when additional compression is needed
Solution Approach 1:
The invention introduces a dynamic control system with a control valve and flow controller that adjusts the flow of high-pressure carbon monoxide based on temperature measurements. This dynamic adjustment optimizes the balance between vaporization capacity and reboiling requirements, eliminating the need for additional compression and associated energy losses while maintaining efficient refrigeration operation
Solution Approach 2:
The invention changes the pressure parameter of carbon monoxide by introducing a high-pressure outlet that delivers carbon monoxide at pressures between 25-45 bars directly to the denitrogenation column, bypassing the need for medium-pressure vaporization in the exchange line. This parameter change eliminates the vaporization capacity constraint and associated energy losses
2Quantity of substance
If the flow of vaporized medium-pressure carbon monoxide is increased to meet reboiling requirements, then reboiling capacity is improved, but the exchange line becomes destabilized and other process flows are affected
Solution Approach 1:
The invention segments the carbon monoxide supply into two independent paths: a high-pressure path that provides reboiling flow directly to the denitrogenation column, and a medium-pressure path that maintains exchange line stability. This segmentation allows independent control of reboiling capacity and exchange line stability, resolving the contradiction between these two requirements
3Area of stationary object
If the exchange line surface area is increased to vaporize more medium-pressure carbon monoxide, then vaporization capacity is improved, but other process flows become too cold and the system requires reduction of vaporized carbon monoxide
Solution Approach 1:
The invention extracts the reboiling function from the exchange line by providing a separate high-pressure carbon monoxide supply path. This removes the coupling between exchange line surface area and reboiling capacity, allowing the exchange line to be sized appropriately for its primary refrigeration function without being forced to provide excessive vaporization that would over-cool other process flows
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 eliminates the constraint on medium-pressure carbon monoxide vaporization, reduces energy losses, and eliminates the need for medium-pressure gas compression, enhancing the efficiency of carbon monoxide separation and reducing energy consumption in the process.
Implementation Method 1
at least occasionally a variable amount of the other portion of high-pressure carbon monoxide cooled in a valve is expanded before being sent to the bottom of the denitrogenation column
Implementation Method 2
a flow of carbon monoxide originating from the column system is compressed in a compressor to a high pressure, high-pressure carbon monoxide is sent from the compressor to the turbine
Implementation Method 3
another portion of the high-pressure carbon monoxide, optionally between 25 and 45 bars, is cooled before being expanded
Implementation Method 4
Method for separating a mixture of at least hydrogen, nitrogen, and carbon monoxide by cryogenic distillation
Data Source
AI summary
The invention relates to a method and apparatus for separating a mixture containing carbon monoxide, nitrogen and hydrogen by cryogenic distillation in a separation system which includes a denitrification column and at least another column. The method can include separating the mixture in order to obtain a fluid enriched with carbon monoxide and containing nitrogen, separating the fluid in the denitrification column, pressurizing the carbon monoxide flow from the column in a compressor up to a high pressure, collecting a fraction of carbon monoxide flow to be used as a product, expanding an amount of the high-pressure carbon monoxide flow in a valve prior to supplying it to the denitrification column, and varying the flow expanded in the valve according to re-boiling needs of the denitrification column.