CO2 Compression Above Critical Pressure With Isothermal-Pump Staging
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Solution Overview
Problem
Current methods for compressing carbon dioxide to high pressures for storage require large capacities and are inefficient, especially due to the need for low cooling temperatures that are difficult to achieve naturally, leading to increased energy consumption and plant complexity.
Innovation Solution
A method involving an isothermal compression process using a turbocompressor to reach pressures above the critical point of carbon dioxide, followed by cooling to a temperature around the critical point, allowing subsequent pumping to achieve high discharge pressures with reduced energy expenditure and simplified cooling systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If carbon dioxide is compressed to high pressure using conventional compressors, then the discharge pressure is achieved, but the required compressor capacity becomes excessively large
Solution Approach 1:
The compression process is divided into two distinct stages: first, isothermal compression to intermediate pressure (80-300 bar) using a geared compressor, then pumping to final high pressure (up to 400 bar) using a piston pump. This segmentation allows each device to operate in its optimal range, avoiding the need for excessively large compressor capacity while achieving the required discharge pressure.
Solution Approach 2:
The invention changes the physical state parameters of carbon dioxide during the process. By maintaining isothermal conditions during compression and then cooling the gas below its critical temperature (31°C) after compression, the CO2 transitions to a supercritical state with liquid-like density. This parameter change enables efficient pumping to high pressures with much lower energy consumption compared to direct compression.
2Use of energy by moving object
If carbon dioxide is cooled to low temperatures for condensation, then the compression efficiency is improved, but the cooling system complexity and energy consumption increase
Solution Approach 1:
Instead of cooling CO2 to very low temperatures (around 10°C) for condensation as in conventional methods, the invention cools the compressed gas to a moderate temperature just below the critical point (around 31°C). This parameter change allows the CO2 to achieve a supercritical state with liquid-like density without requiring complex refrigeration systems, thereby reducing both cooling system complexity and energy consumption while maintaining compression efficiency.
3Quantity of substance
If carbon dioxide is compressed to supercritical pressure, then the storage efficiency is improved, but the compression process complexity increases
Solution Approach 1:
The compression process is segmented into two distinct stages with different equipment optimized for each stage: a geared compressor for isothermal compression to intermediate pressure, and a piston pump for final pressurization to supercritical levels. This segmentation achieves high storage capacity by reaching supercritical pressures while managing process complexity through specialized equipment for each stage rather than requiring a single complex system.
Solution Approach 2:
The invention replaces the conventional single-stage mechanical compression system with a hybrid system combining isothermal compression followed by pumping. This substitution leverages the different mechanisms of compression (isothermal process) and pumping (displacement method) to efficiently achieve supercritical pressures, improving storage capacity while keeping the overall process complexity manageable through clear functional separation.
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 method achieves efficient compression with lower capacity requirements, reduced energy use, and simplified cooling systems, enabling effective carbon dioxide storage without the need for additional refrigeration plants, thus enhancing the overall efficiency and reducing the loading rate of storage deposits.
Implementation Method 1
the initially gaseous carbon dioxide being compressed in a compressor by means of an essentially isothermal process to a pressure which lies above the pressure of the critical point of carbon dioxide
Implementation Method 2
the carbon dioxide being cooled in a cooling device to a temperature below the temperature of the critical point
Implementation Method 3
the carbon dioxide then being compressed in a pumping device to a predetermined discharge pressure
Data Source
AI summary
A method is provided where carbon dioxide is compressed in a multi-stage geared compressor using a substantially isothermic process to a pressure which lies above the pressure of the critical point of carbon dioxide. The carbon dioxide is subsequently cooled to ambient temperature in a cooling device and then compressed to a predefined final pressure in a pump device.