Introduction
CO2 separation has been done for more than 100 years. Flue gas pressure is increased by a compounder. The mechanical energy used for increasing the pressure is recovered (80%) when the pressure is released. In addition, CO2 Capsol has also patented a special method to conserve the heat energy from the process. The CO2 Capsol patents have the following main advantages:
- Operational cost is significant lower
- Can be applied in all known capturing processes
- The capturing plant is compact
A capturing process at atmospheric pressure requires a very reactive absorbent like amin based chemicals (nitrogen). The nitrogen atom reacts in different ways with air resulting in release of harmful substances. CO2 Capsol has therefore concentrated on the hot potassium method which has no negative impact in the environment.
The CO2 Capsol process is applied as a separate module to existing plants – end of pipe (EoP). We estimate that the total time from final investment decision to commissioning will be 2-3 years with a significant cost saving compared to other methods.
CO2 Capsol AS has additional designs where the CO2 capturing process is a part of the power plant itself, both coal and gas fired power plants.
Capsol EoP - End of Pipe CO2 Capture
The process is used in the chemical process industry and there are today over 1000 plants where the well-known process is used and documented.
Capsol End of Pipe - EoP is a post combustion flue gas cleaning module utilizing the Hot Potassium Carbonate (HPC) process.
The EoP-module is connected to the flue gas duct just before the stack on an existing plant. It does not interfere with the plant.
-it just takes care of the pollutions such as CO2, NOx, SOx and mercury and clean the flue gas to a mixture of nitrogen and water vapor.
Capsol EoP is a modularized CO2 capture designed unit utilizing the proven HPC technology. Capsol has improved the heat integration of the HPC process and also how to solve the interface to the existing plant. Capsol also makes a complete survey of the H&M balance of a plant to increase the possibility of utilizing excess energy where it is most efficient.
Background
Chemical reactions are often more efficient when being placed under pressure. The reaction between CO2 and Hot Potassium Carbonate only occurs when it is done under pressure. This CO2 reaction is named the Hot Potassium Carbonate - HPC carbon capture process and it is a mature, cost effective process as well as safe from an environmental point of view. The process is today used in the chemical industry and there are over 1000 plants where the well-known process is used and documented.
Capsol EoP main characteristics
Capsol EoP uses electric energy for driving compressors and pumps. The energy needed for the desorber in the process is internally recuperated by means of electrically driven compressors. Thus, there is no need for any complex heat integration between the plant that supplies the flue gas and the Capsol EoP system. The only interface is the duct channeling off the flue gas flow to the EoP plant.
Thanks to the elevated pressure, the sorbent potassium Carbonate can be used. It is a well-established, very stable and low-cost sorbent.
Additionally, the sorbent consumption is very low and there are no Amine related health hazards. Note: Amines can as well be used in the process.
The interface- Flue Gas Conditioning
Most of the adjustment and efforts in a site-specific case are made on interfacing the existing power plant and the Capsol EoP module. The flue gas can be partially or fully diverted from the plant flue gas duct to the Capsol EoP module.
Each plant has different flue gas composition, properties, dust and emissions. The interface will be equipped with necessary equipment to fit the compressor requirements, such as cooling and flue gas cleaning. This is most preferably made by installing a simple flue gas condensation system. A prefeasibility study will focus on gathering required information which will form the base for the design of the interface.
The EoP module will then further clean the flue gas so that most of the emissions are reduced to far below the stringent regulation limits and finally disposed from the module.
CO2 capture
The CO2 capture unit is conventional with a CO2 absorption and a desorption column. A chemical CO2 absorbent, potassium carbonate is employed. This absorbent has many advantages for flue gas purification such as follows:
- Field proven in large scale industrial systems over 50+ years
- Very low energy requirement for absorbent regeneration
- Oxygen tolerant without solution degradation (very stable solvent)
- High selectivity CO2 / O2 and CO2/ N2
- Non-volatile, cannot degrade to volatile organic compounds or vaporize into the flue gas
- Non-toxic, but some caution is required because the lean solvent has relatively high pH
- Potassium carbonate is a low-cost commodity chemical
- The hot potassium carbonate process, HPC, is simple and reliable (availability for well running units better than 99%)
- CO2 removal rate above 90%
CO2 Compression
Compression of CO2 is normally considered optional and site specific but Capsol designs and offers technical data summary for a compressor.
Implementing the compressor into the EoP module will increase the re-use of waste heat.
Summary
The Capsol - EoP is based on the patented Capsol technology and built on a unique composition of proven technologies minimizing risks and securing safe operation.
The Capsol EoP-capture cost per ton CO2 is lower than for alternative atmospheric post combustion CO2 capture systems indicates.
The HPC process as well as the mechanical components is proven and safe and there are operational references available around the world in many chemical process industries.
The EoP CO2 capture module is a compact standard product with the following data:
- Designed for ~110 kg/s flue gas flow
- Captures ~700 000 tonne/y of CO2 (90%capture)
- Consumes ~20 MWe (W/O CO2 compression), approx. 30MWe incl. compression
- Cooling need of 20-30 MW depending on incoming flue gas temperature
EoP consumes approx. 25% of the electric production from an existing plant (assuming ~40% plant efficiency). The performance data above is related to a relatively high concentration of CO2 in the flue gas, such as from a coal fired plant. A high concentration of CO2 gives a higher overall performance. The modularized design enables a robust design and makes possible for the manufacturers to make longer series of modules which decrease equipment and manufacturing costs. Modularization makes the Capsol EoP a very size flexible product and fits all plant sizes. Note that larger modules are possible.
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