Apparatus and process for separating CO2 from a flue gas
An apparatus and a process for separating carbon dioxide from a flue gas of a coal burning power plant. The process includes compressing the flue gas to increase the pressure and temperature, and then passing the flue gas through a cryogenic heat exchanger that decreases the temperature even more prior to passing the cooled carbon dioxide through a turbine that decreases the temperature more and forms liquid and solid forms carbon dioxide. A carbon dioxide separator then separates the carbon dioxide from the flue gas, leaving both liquid and solids forms. A screw compressor compresses the solid carbon dioxide to produce only liquid carbon dioxide at a pressure suitable for sequestration. The liquid carbon dioxide is passed through the heat exchanger to cool the flue gas and to separate out any sulfur dioxide and water from the flue gas and to vaporize the liquid carbon dioxide prior to sequestration of the vapor carbon dioxide.
Latest FLORIDA TURBINE TECHNOLOGIES, INC. Patents:
None.
CROSS-REFERENCE TO RELATED APPLICATIONSThis application claims the benefit to a Provisional Patent Application 61/178,737 filed on May 15, 2009 and entitled APPARATUS AND PROCESS FOR SEPARATING CO2 FROM A FLUE GAS.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates generally to a coal or bio-mass burning power plant, and more specifically to process and apparatus for separating and sequestering CO2 emissions.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
In coal-based or bio-mass power generation, pulverized coal (PC) is bio-mass is the primary generating technology for combustion. PC combustion technology continues to undergo technological improvements that increase efficiency and reduce emissions. Carbon dioxide (CO2) capture and sequestration in coal-based power generation is an important emerging option for managing carbon dioxide emissions while meeting growing electricity demand.
Most of the coal-based generating units in the US are between 25 and 55 years old with an average generating efficiency of about 33% and some of the newer generating units at about 36% efficiency. The fraction of the thermal energy in the fuel that ends up in the net electricity produced is the generating efficiency of the unit. Increased generating efficiency is important, since it translates directly into lower criteria pollutant emissions and lower carbon dioxide emissions per kW-hr of electricity generated.
CO2 removal from the flue gas requires energy, primarily in the form of low-pressure steam for the regeneration of the amine solution. This reduces steam to the turbine and the net power output of the generating plant. Thus, to maintain constant net power generation the coal input must be increased, as well as the size of the boiler, the steam turbine/generator, and the equipment for flue gas clean-up. Absorption solutions that have high CO2 binding energy are required by the low concentration of CO2 in the flue gas, and the energy requirements for regeneration are high.
A sub-critical PC unit with CO2 capture shown in
A coal fired power plant and a process to remove CO2 from the flue gas of a coal fired power plant. The flue gas from the power plant is compressed to increase the pressure and the temperature. The compressed flue gas is then cooled and passing the flue gas through a heat exchanger to separate out any H2O and SO2 from the flue gas. The cooled flue gas is then passed through a turbine that drives an electric generator where the flue gas is further cooled to produce liquid and solid CO2, which is then passed through a separator that separates the liquid and solid CO2 from the flue gas. The separated liquid and solid CO2 is then passed into a screw compressor that liquefies the solid CO2 to produce all liquid CO2 which is then passed through the heat exchanger to cool the flue gas further. The flue gas with little CO2 remaining is then passed through the heat exchanger and discharged to atmosphere. The compressed liquid CO2 that passes
In another embodiment, the carbon dioxide separation occurs in a separate carbon dioxide separator unit located downstream from the turbine and upstream from the heat exchanger. In another embodiment, the carbon dioxide separator is also the heat exchanger. In another embodiment, a second heat exchanger is located between the compressor and the first heat exchanger to cool the compressed flue gas entering the first heat exchanger and heat the flue gas exiting from the first heat exchanger in which the flue gas is then used to drive a second turbine.
To prevent carbon dioxide ice from forming on the turbine, the turbine is heated by passing a heating fluid such as compressed air through the turbine or using electric heating elements.
The apparatus and process for separating the CO2 from a flue gas of a coal burning power plant is shown in
The flue gas exiting the heat exchanger 16 at 160 degrees K (−113 C) and at 685 kg/sec flows into a turbine 17 that form liquid and solid CO2 from the flue gas 11. The turbine 17 is used to drive an electric generator and produce electric power. As the flue gas 11 passes through the turbine 17, the temperature of the flue gas drops considerably. To prevent the CO2 solid ice from sticking onto the turbine parts such as the blades and vanes, heat is added to the turbine such as by a compressed air (heated air due to the compression process) that is passed through the turbine components to heat up the parts so that the CO2 ice will not stick to the turbine parts. Thus, the turbine 17 is heated instead of cooled as in the prior art gas turbine engines. The flue gas 11 then exits the turbine 17 at 160 degrees K and enters a CO2 particle separator 18 and then flows into the heat exchanger 16 to receive heat from the first pass-through flue gas 11 that enters the heat exchanger 16 from the compressor 14. As the CO2 turns to ice, it will stick to the turbine parts and walls. If the parts can be heated to above 220 degrees K, then the CO2 will not stick to the parts. The compressed air used to heat the turbine parts can be compressed flue gas. The turbine parts can also be heated using electrical heating elements in which an electric current is passed through the parts to produce the required heat. The turbine 17 is also connected to an electric generator for the production of electrical energy.
The CO2 from the CO2 particle separator 18 is both in a solid and a liquid form and is converted into an all liquid form in a screw compressor 19 to 2200 psi and where the liquid CO2 then flows through the heat exchanger 16 to draw heat from the first and second pass-through flue gas passages within the heat exchanger 16. The CO2 that exits the heat exchanger 16 is at 2200 psi but in a vapor form and flows at a rate of 102 kg/sec and is ready to be discharged into a storage location for sequestration.
In the embodiment of
A second embodiment shown in
If the CO2 particle separator 18 is used, any left-over solid and liquid CO2 from the first pass-through flue gas in the heat exchanger 16 is passed through the turbine 17 to form solid and liquid CO2 is passed into the separator 18. The liquid and solid CO2 from the separator 18 is then merged with the liquid and solid CO2 from the heat exchanger 16 and passed into the screw compressor 19. The screw compressor then liquefies the solid CO2 to form all liquid CO2 with the required pressure for sequestration. The second pass-through flue gas 11 from the turbine 17 is then discharged out to atmosphere as relatively clean flue gas with only about 10% of the original CO2 remaining. The pressurized and liquid CO2 from the screw compressor 19 that is passed through the heat exchanger 16 includes the SO2 and H2O and other impurities as well as the CO2 to be sequestered together. The CO2 containing fluid exiting the heat exchanger is a vapor but still at the high pressure for sequestration.
In the
In each of the three embodiments for separating CO2 from a flue gas described above, a cryogenic air separation process is used to separate most of the CO2 as a liquid (or a gas) that can then be delivered to a storage system such as an in-ground sequestration apparatus. In the cryogenic process to separate the CO2 from the flue gas, the flue gas is cooled to a low enough temperature so that the carbon dioxide will freeze out onto the walls of the heat exchanger air passages.
Claims
1. An apparatus to separate carbon dioxide from a flue gas of a power plant comprising:
- a compressor to increase a pressure and a temperature of the flue gas;
- an air cooler means located downstream from the compressor to cool the flue gas from the compressor;
- a heat exchanger located downstream from the air cooler means to cool the flue gas exiting from the air cooler means and separate sulfur dioxide from the flue gas;
- a turbine located downstream from the heat exchanger to form a liquid and a solid form of carbon dioxide from the flue gas;
- a carbon dioxide separator means located downstream from the turbine to separate carbon dioxide from the flue gas from the turbine;
- a screw compressor to liquefy the solid form of carbon dioxide from the carbon dioxide separator means and pass the liquid carbon dioxide through the heat exchanger to covert the liquid carbon dioxide into a vapor and cool the flue gas passing through the heat exchanger; and,
- the flue gas from the carbon dioxide separator being passed through the heat exchanger to add heat to the liquid carbon dioxide from the screw compressor.
2. The apparatus to separate carbon dioxide from a flue gas of claim 1, and further comprising:
- the air cooler means is an air cooler fan.
3. The apparatus to separate carbon dioxide from a flue gas of claim 1, and further comprising:
- the air cooler means is a feed water heater with an air cooler fan located downstream from the feed water heater.
4. The apparatus to separate carbon dioxide from a flue gas of claim 1, and further comprising:
- the air cooler means is a second heat exchanger that also heats up the flue gas from the first heat exchanger; and,
- a second turbine to pass the flue gas from the first heat exchanger and drive an electric generator.
5. The apparatus to separate carbon dioxide from a flue gas of claim 1, and further comprising:
- the carbon dioxide separator means includes a carbon dioxide separator located between the turbine and the heat exchanger.
6. The apparatus to separate carbon dioxide from a flue gas of claim 5, and further comprising:
- the turbine located between the heat exchanger and the carbon dioxide separator means includes means to heat the turbine so that solid carbon dioxide does not form on the turbine.
7. The apparatus to separate carbon dioxide from a flue gas of claim 6, and further comprising:
- the means to heat the turbine includes a passage formed within the turbine to pass a heated fluid.
8. The apparatus to separate carbon dioxide from a flue gas of claim 6, and further comprising:
- the means to heat the turbine includes an electric heating element within the turbine.
9. The apparatus to separate carbon dioxide from a flue gas of claim 1, and further comprising:
- the carbon dioxide separator means includes the heat exchanger with solid and liquid carbon dioxide from the heat exchanger passed into the screw compressor; and,
- the liquid carbon dioxide from the screw compressor passed through the heat exchanger to convert the liquid carbon dioxide into a lapor.
10. The apparatus to separate carbon dioxide from a flue gas of claim 1, and further comprising:
- the turbine located between the heat exchanger and the carbon dioxide separator drives an electric generator.
11. The apparatus to separate carbon dioxide from a flue gas of claim 1, and further comprising:
- the heat exchanger is a cryogenic heat exchanger.
12. A process for separating carbon dioxide from a flue gas of a power plant, the process comprising the steps of:
- increasing the pressure and the temperature of the flue gas;
- cooling the flue gas without decreasing the pressure of the flue gas;
- passing the flue gas through a heat exchanger to cool the flue gas and to separate water and sulfur dioxide from the flue gas;
- passing the pressurized flue gas from the heat exchanger through a turbine to produce solid and liquid forms of carbon dioxide;
- separating the solid and liquid forms of carbon dioxide from the flue gas;
- increasing the pressure of the solid and liquid forms of carbon dioxide to eliminate the solid form of carbon dioxide and produce an all liquid form carbon dioxide and to a pressure suitable for sequestration of the carbon dioxide; and,
- passing the pressurized and liquid form of carbon dioxide through the heat exchanger to cool the flue gas and convert the liquid carbon dioxide into a vapor.
13. The process for separating carbon dioxide of claim 12, and further comprising the step of:
- heating the turbine to prevent carbon dioxide ice for forming within the turbine.
14. The process for separating carbon dioxide of claim 12, and further comprising the step of:
- prior to passing the compressed flue gas through the first heat exchanger, passing the compressed flue gas through a second heat exchanger to heat the flue gas exiting from the first heat exchanger and drive a second turbine.
15. The process for separating carbon dioxide of claim 12, and further comprising the step of:
- separating the solid and liquid forms of carbon dioxide from the flue gas exiting from the turbine and increasing the pressure of the solid and liquid forms of carbon dioxide to eliminate the solid carbon dioxide prior to passing the liquid carbon dioxide through the heat exchanger.
16. The process for separating carbon dioxide of claim 12, and further comprising the steps of:
- separating the carbon dioxide from the flue gas in the heat exchanger to form a first flow of carbon dioxide and then in a second carbon dioxide separator after passing the flue gas through the turbine to form a second flow of carbon dioxide; and,
- combining the two flows of carbon dioxide and pressurizing the carbon dioxide to form only liquid carbon dioxide to pass through the heat exchanger at a pressure suitable for sequestration.
Type: Application
Filed: May 12, 2010
Publication Date: Dec 8, 2011
Applicant: FLORIDA TURBINE TECHNOLOGIES, INC. (Jupiter, FL)
Inventor: Joseph D. Brostmeyer (Jupiter, FL)
Application Number: 12/778,514
International Classification: F25J 3/00 (20060101);