Solvent-based co2 capture process incorporating a heat pump
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Solution Overview
Problem
Carbon capture processes require significant heat input and cooling water, leading to increased CO2 emissions and water usage, which is unsustainable and costly.
Innovation Solution
Implementing a thermodynamically efficient all-electric heat pump system to replace process heat duty, utilizing a one- or two-stage heat pump to transfer heat from a low-temperature source, reducing the need for steam boiler-generated heat and cooling water, while maintaining efficient heat transfer through vapor compression cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam is used to provide process heat in the stripping column reboiler or steam heater, then CO2 can be removed from the solvent, but CO2 emissions increase by 0.15-0.2 kg per kg CO2 captured
Solution Approach 1:
The invention captures the CO2 emissions generated by the steam boiler and reintroduces them into the absorber column to be absorbed by the solvent. This converts the harmful CO2 emissions into a useful resource, achieving a closed-loop system where CO2 captured from flue gas is ultimately reused, eliminating net CO2 emissions from the process.
Solution Approach 2:
Instead of discing the CO2 emissions from the steam boiler to the atmosphere, the invention recovers them by routing the boiler exhaust through the absorber column. This allows the solvent to capture the CO2 that would otherwise be wasted, transforming a disposal problem into a resource recovery opportunity.
2Productivity
If a simple stripping column with overhead condenser is used, then CO2 can be removed from the solvent, but all heat from vaporized water is lost
Solution Approach 1:
The invention merges the overhead condenser with the steam heater by routing the condensed water from the overhead condenser directly to the steam heater. This integration allows the condensed water to serve dual purposes: first as condensate, then as feedwater for steam generation, thereby recovering and reuse the heat that would otherwise be lost.
Solution Approach 2:
The invention establishes a continuous cycle where vaporized water is condensed and the condensed water is continuously fed back to the steam heater. This creates an unbroken loop of heat recovery and reuse, ensuring that the heat from vaporized water is continuously captured and put to productive use rather than being lost intermittently.
3Productivity
If flash stripping with steam heater is used, then CO2 can be removed from the solvent without reboiler, but large amounts of cooling water are required
Solution Approach 1:
The invention makes the system self-sufficient regarding cooling water by using the condensed overhead vapor as the cooling medium. The condensed water from the overhead condenser is routed to cool the rich solvent stream, eliminating the need for external cooling water supplies and making the system self-contained.
Solution Approach 2:
The invention introduces condensed overhead vapor as an intermediary cooling medium between the hot rich solvent stream and the environment. Instead of directly using external cooling water, the system uses the condensed vapor itself as the heat sink, mediating the heat transfer process and eliminating external cooling water requirements.
4Temperature
If cooling water is used for process cooling, then heat can be removed from process streams, but water consumption increases significantly
Solution Approach 1:
Instead of discarding the cooling water after it absorbs heat from process streams, the invention recovers it by routing the warmed cooling water to the steam heater as feedwater. This allows the cooling water to be reused, transforming a single-use consumable into a reusable resource and dramatically reducing overall water consumption.
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 solution decreases CO2 emissions by 13-17% and reduces cooling water demand by 30%, lowering operational expenses and environmental impact while maintaining effective CO2 capture efficiency.
Implementation Method 1
Heat is transferred from a low temperature heat source in the process to the steam heater through the use of a one- or two-stage heat pump system
Implementation Method 2
utilizing a one- or two-stage heat pump to transfer heat from a low-temperature source, reducing the need for steam boiler-generated heat and cooling water, while maintaining efficient heat transfer through vapor compression cycles
Data Source
AI summary
Processes for CO2 recovery from flue gas are described. The processes involve the use of a vapor compression heat pump cycle. The heat pump comprises an evaporator, a heat pump compressor, a condenser, and a pressure letdown device. The condenser is a heat exchanger exchanging heat from a working fluid to a CO2 containing solvent in which CO2 is released, and the evaporator is a heat exchanger exchanging heat from a suitable low temperature heat source to the working fluid. The condenser of the heat pump replaces the steam heater for the stripping column, and the evaporator replaces a heat exchanger, such as the quench cooler.