Cryogenic CO Recovery With Supercooled Expansion Streams
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Solution Overview
Problem
Current methods for cryogenic gas separation of hydrogen and carbon monoxide are economically inefficient due to high energy requirements for compression and cooling, particularly in achieving the necessary temperature for partial condensation and product purity.
Innovation Solution
The process involves supercooling the liquid CO from the separating column and splitting it into multiple partial streams, each expanded to different pressure levels for evaporation and heating, with the goal of minimizing gas formation during expansion and optimizing the distribution of CO streams to the CO compressor, thereby reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid CO is expanded to produce cold for cooling the feedstock stream, then the required temperature for partial condensation is achieved, but a large proportion of CO must be evaporated and fed to the compressor in gaseous form, increasing energy consumption
Solution Approach 1:
The liquid CO stream is supercooled against process streams to be heated before expansion. This preliminary cooling action reduces the temperature of liquid CO below its normal condensation point, so that when it is subsequently expanded, less of it evaporates and requires compression, thereby reducing the energy consumption of the CO compressor while still achieving the required cooling effect on the feedstock stream
Solution Approach 2:
The invention changes the temperature parameter of liquid CO by supercooling it against process streams to be heated. This parameter change allows the liquid CO to be divided into partial streams that are expanded to different pressure levels, optimizing the balance between cooling effect and compression energy requirements
2Use of energy by moving object
If liquid CO is supercooled and divided into multiple partial streams for expansion at different pressure levels, then energy efficiency is improved, but the device complexity increases
Solution Approach 1:
The supercooled liquid CO stream serves multiple functions: it cools the feedstock stream to the required temperature for partial condensation, and simultaneously provides cold for the expansion process that drives the CO compressor. By making the liquid CO stream multi-functional through supercooling, the invention reduces the need for separate cooling systems and minimizes the number of partial streams required, thereby improving energy efficiency without proportionally increasing device complexity
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 enhances the economic efficiency of CO recovery by minimizing the energy required for compression and cooling, allowing for higher CO yield and product purity while reducing the number of partial streams needed for cooling and compression.
Implementation Method 1
the liquid CO drawn off from the bottom of the separating column is supercooled against the process streams to be heated
Implementation Method 2
which are each expanded to a different pressure level, evaporated against the process streams to be cooled
Implementation Method 3
Each of the partial flows is expanded to produce cold and, after evaporation and heating, is fed in gaseous form to another section of the compressor on its suction side
Implementation Method 4
the feedstock flow is fed into the cryogenic gas separation unit and is cooled in countercurrent in indirect heat exchange against process flows to be heated
Implementation Method 5
to such an extent that partial condensation occurs, in which a CO-rich liquid fraction and an H2-rich gas fraction form
Implementation Method 6
the liquid CO is taken from the bottom of the separating column and expanded to produce cold. Due to the expansion, during which part of the liquid CO passes into the gas phase, the temperature is lowered
Data Source
AI summary
The production of a gaseous carbon monoxide product stream is carried out by decomposition of a feedstock stream (1) composed of hydrogen and carbon monoxide in a cryogenic gas decomposition unit by cooling through indirect heat exchange against a heating process stream. CO-rich and H 2-containing condensate is formed by a single-step partial condensation. H 2-rich and CO-containing gas fraction (flash gas) is separated by a cryogenic fractioning of the condensate in a separating column (T). A liquid CO (11) with product purity is extracted as a sump product in the separating column. The production of a gaseous carbon monoxide product stream is carried out by decomposition of a feedstock stream (1) composed of hydrogen and carbon monoxide in a cryogenic gas decomposition unit by cooling through indirect heat exchange against a heating process stream. CO-rich and H 2-containing condensate is formed by a single-step partial condensation. H 2-rich and CO-containing gas fraction (flash gas) is separated by a cryogenic fractioning of the condensate in a separating column (T). A liquid CO (11) with product purity is extracted as a sump product in the separating column and evaporated, heated and led into a CO compressor (C1). A gaseous CO is compressed by compressor sections at product pressure and the liquid CO is cooled against the heating process stream and split up into partial streams, which are relaxed at a pressure level against a cooling process stream. The liquid CO partial streams are released at the suction face of another compressor section. The liquid CO from the sump of the separating column is strongly under cooled at the lowest pressure level to form a liquid-gas mixture separated in a separator (D1) during the relaxation. The H 2-rich and CO-containing gas phase is heated through indirect heat exchange against cooling process streams. The feedstock stream for the cryogenic gas-separating unit is produced from a synthetic gas by cleaning in a CO 2washing and an adsorbent station (A). The H2-rich and CO-containing gas fraction is used for the recycling of the adsorbents in the adsorbent station after warming up. The gas fraction is separated into a hydrogen fraction and a CO/H 2mixture in a membrane unit. The hydrogen fraction is used for the recycling of the adsorbents and the CO/H2 mixture is employed for the extraction of carbon monoxide after cooling against heating process streams of the column. An impure gas from adsorbent station used for the recovery of the adsorbent is cleaned in a pressure variable adsorbent station and delivered at a battery limits. A rest gas (37) from the pressure variable adsorption station is led back into the synthesis gas before the CO 2washing. Liquid nitrogen is supplied from beyond the battery limits for cooling process and evaporated in a heat exchanger (E1), which is integrated in the separator and a part of the CO contained in the gas fractioning group is condensed. An independent claim is included for device for production of a gaseous carbon monoxide product stream.