1. Field of the Invention
This invention relates generally to power generation systems, and more particularly, to an efficient, low polluting, power generation arrangement that operates continuously, can produce a variety of products, and can use a variety of fuels.
2. Description of the Related Art
Prior to the 1980's it was normal and considered good practice to design, build, and operate dedicated manufacturing plants for most every product that was produced on a large scale in the world. Shortly after that period many industries became enlightened to the merit of flexible machining, and flexible manufacturing. Much of this paradigm shift was accomplished on the back of the modern microprocessors. This device allowed more enlightened design, and more importantly complex and precise control of involved processes. Many new inventions were required in the wake of this manufacturing revolution. Instead of an assembly line in the past making only one dedicated product, current best in class assembly lines make up to 100's of different products and models, in batch sizes of one, with no perceived loss of productivity or additional set up time. This clever thought process, and design, has netted many benefits to industries like the automotive world, heavy duty engines, and other hard goods manufacturers.
The energy world has not yet embraced this concept. There is a need to produce energy products in a more efficient and cleaner process than any carbon based process presently in use. One implementation of this concept does not use fossil fuels. In another implementation, the use of fossil fuels (such as coal) is minimized where possible. This is essential in developed countries, such as the United States, that have an elevated need for a “clean coal” electricity generation system, and for the manufacture of other fossil fuel energy dependent products, such as plastics, gaseous fuels, and fertilizers. In the United States and other developed countries, there is an ongoing effort to reduce the dependence on imported oil. It is, therefore, an object of this invention to achieve these goals in an environmentally friendly way.
Current power generation plants have only one primary process; i.e., to produce electricity by burning fuel and consequently emitting pollutants, such as greenhouse gasses. One of the significant disadvantages of conventional power plants is that when they are brought off-line, and then restarted, they are unacceptably inefficient and produce excessive amounts of harmful emissions. Modern power plants do not enable the efficient throttling back of production of electrical power, and therefore they are operated continuously near the designed load limit. Since electrical power cannot be stored, power plants are frequently shut down and restarted in response to the varying demand for electrical power by consumers on a day-to-day basis, and as a result of differences in demand between day and night conditions.
With few exceptions (e.g., hydroelectric, wind, and nuclear power generation systems) power plants burn huge amounts of fossil fuel at relatively low efficiencies. The average efficiency of coal power plants in the United States is approximately 34%. Natural gas plants are slightly more efficient.
The predominant greenhouse gas produced by power plants is CO2. In the present state of the art, coal plants in the United States produce on average approximately 2.01 Lbs of CO2 per KWH of power. Natural gas and petroleum plants produce about 1.6 Lbs of CO2 per KWH. These are “carbon positive” greenhouse gasses, in that they were removed from the ground and released to the atmosphere. In a carbon neutral process no new emissions are released into the atmosphere. In other words, nothing that has been removed from the ground is released into the atmosphere. Only existing carbon and greenhouse gasses that are already in circulation are processed and released.
In a carbon negative process greenhouse gasses are removed on a net basis from the atmosphere into a captured state. An example would be to extract CO2 from the atmosphere and capture it into a hard substance, such as a plastic. A better product would be fertilizer since it could then be used to grow plants and food that continue to capture CO2.
It is, therefore, an object of this invention to provide a power generation system that reclaims heat energy that otherwise would be exhausted into the atmosphere.
It is another object of this invention to provide a power generation system that operates at higher efficiency than conventional power generation systems.
It is also an object of this invention to provide a power generation system that eliminates the need for repeated start up and shut down procedures in response to consumer demand for power.
It is yet another object of this invention to provide a power generation system that greatly reduces emissions of CO2.
The foregoing and other objects are achieved by this invention which provides a system for generating electrical power. In accordance with the invention, the system employs a reactor for producing a product gas in response to the consumption of a feedstock. A heat reclamation arrangement extracts heat from the product gas and forms heated steam. The heated steam is delivered to a turbine that has an input for receiving the heated steam, an outlet for exhausting spent steam, and a rotatory output. An electrical generator is coupled to the rotatory output of the turbine for producing the electrical energy. In addition, a recirculating system returns the spent steam to the heat reclamation arrangement.
In one embodiment, there is provided in the recirculating system comprises a condenser arrangement.
The reactor is in certain embodiments of the invention provided with an excitation torch. A portion of the electrical energy produced by the electrical generator is conducted to the excitation torch.
Feedstock is provided to the reactor at a feedstock input. The feedstock may be coal, municipal solid waste, biomass, a non-fossil fuel, or any combination thereof. In addition, the reactor is provided with an additives input that receives additives that serve to neutralize the acid or base content of the product gas. In still further embodiments, the reactor is provided with a coke or other fuel input for receiving coke or other forms of fuel; and an air input for receiving air that in some embodiments may be oxygen enriched.
The heat reclamation arrangement, in some embodiments of the invention, is provided with a first duct having an inlet for receiving the product gas, and an outlet for exhausting the product gas at a reduced temperature. A second duct has an inlet for receiving the spent steam and an outlet for exhausting the heated steam. In addition, a heat transfer arrangement for conducting heat extracted from the product gas in the first duct to the spent steam in the second duct, to form the heated steam. In a further embodiment, the heat transfer arrangement includes at least one sodium heat pipe having a first end for communicating with the product gas in the first duct, and a second end for communicating with the spent steam in the second duct. Other heat transfer media besides sodium may be used. The sodium heat pipe has an envelope formed of stainless steel, Inconel, molybdenum, tungsten, niobium, a selectable combination of carbon and carbon composite; or Hastelloy X. A safety valve ensures safe operation.
In some embodiments of the invention, a heat transfer fin is disposed in the first duct for enhancing the transfer of heat from the product gas to the sodium heat pipe. Additionally, an adiabatic zone is, in some embodiments of the invention, interposed between the first and second ducts.
In still further embodiments of the invention the heat transfer arrangement is provided with a heat transfer loop having a first portion for communicating with the product gas in the first duct, and a second portion for communicating with the spent steam in the second duct. The heat transfer loop is a salt loop, and there is further provided a pump for circulating the salt along the salt loop.
In an alternative heat transfer arrangement, the heat transfer loop is a steam loop having a portion arranged to communicate with the product gas. The steam loop has an inlet for receiving the spent steam and an outlet for issuing the heated steam.
There is provided in some embodiments of the invention a Richardson reactor having an inlet for receiving the product gas at a reduced temperature, and an outlet for issuing selectable ones of C2, C3, C4, and C5. The Richardson reactor may be a Fischer Tropsch style reactor. The Richardson reactor is typically a foam reactor, and more specifically, in some embodiments of the invention is an alpha alumina oxide foam reactor. The foam reactor is, in some embodiments, optimized to provide higher carbon content transportation fuels, such as diesel fuel. In other embodiments there is provided a selectable combination of a Sabatier reactor having an inlet for receiving the product gas at a reduced temperature, and an outlet for issuing CH4, an ammonia reactor having an inlet for receiving the product gas at a reduced temperature, and an outlet for issuing ammonia or NH3, a methanol reactor having an inlet for receiving the product gas at a reduced temperature, and an outlet for issuing CH3OH.
In still further embodiments, there is provided a secondary power generation facility having an inlet for receiving the product gas at a reduced temperature, and an outlet for issuing electrical power. The secondary power generation facility is provided with a compressor having an inlet for receiving the product gas at a reduced temperature, and an outlet for issuing a syngas. A first turbine receives the syngas, the first turbine having a rotatory output and an exhaust outlet. Additionally, a first generator coupled to the rotatory output of the first turbine, the first generator having an output for issuing electrical power. In some embodiments of the invention, a syngas cleaner is interposed between the outlet of the compressor and the first turbine.
In a further embodiment, there is provided a further heat reclamation arrangement that is arranged to communicate with the exhaust of the first turbine, the further heat reclamation arrangement having an outlet for producing a heated steam. A second turbine having a rotatory output is arranged to receive the heated steam from the further heat reclamation arrangement. Then, a second generator coupled to the rotatory output of the second turbine, and produces electrical power at an output thereof.
In accordance with a method aspect of the invention, there are provided the steps of:
delivering a feedstock to a reactor to produce a product gas;
reclaiming heat from the product gas in a heat reclamation arrangement to form a super heated steam;
delivering the superheated steam to a turbine;
rotating an electrical generator in response to the step of delivering the superheated steam to the turbine to produce electrical energy for an electrical distribution grid;
extracting spent steam from the turbine; and
recirculating the spent steam to the heat reclamation arrangement.
In one embodiment of this method aspect of the invention, and prior to performing the step of recirculating the spent steam to the heat reclamation arrangement, there is provided the step of subjecting the spent steam to a condensation process.
In some embodiments, there is provided the further step of delivering a portion of the electrical energy obtained during performance of the step of rotating the electrical generator, to a torch in the reactor.
The step of reclaiming heat from the product gas in a heat reclamation arrangement includes, in some embodiments, the further step of transferring heat along a sodium pipe between the product gas and the spent steam. In a different embodiment, the step of reclaiming heat from the product gas in a heat reclamation arrangement includes the further step of circulating the spent steam through a conduit disposed in communication with the product gas. In a still further method embodiment, the step of reclaiming heat from the product gas in a heat reclamation arrangement includes the further step of circulating a salt-based fluid through a conduit disposed in communication with the product gas and with the spent steam. In this still further method embodiment, the step of circulating a salt-based fluid includes the further step of pumping the salt-based fluid through the conduit.
The step of delivering the feedstock to the reactor includes the step of delivering coal, municipal solid waste, biomass, a fossil fuel, a non-fossil fuel, or any combination thereof to the reactor.
In an advantageous embodiment of the invention, the step of delivering the feedstock to the reactor to produce a product gas is performed continuously independently of the demand for electrical power on the electrical distribution grid. Thus, the reactor is not repeatedly started and shut down in response to demand on the electrical distribution grid. The reactor is, in some embodiments of the invention, operated in a pyrolysis mode.
In other embodiments of the method aspect of the invention, there is provided the further step of delivering coke or other fuel to the reactor. In yet other embodiments, there is provided the further step of delivering air to the reactor, the air optionally being enriched with O2. In still further embodiments, there is provided the step of delivering an additive to the reactor, the step of delivering an additive to the reactor being responsive to a chemical characteristic of the product gas.
In an advantageous embodiment of the invention the reactor is a plasma reactor.
In respective embodiments of the invention there are provided the steps of operating:
a Fischer Tropsch style reactor for making a product in response to a decreased demand for electrical power by the electrical distribution grid;
a Richardson reactor for making a product in response to a decreased demand for electrical power by the electrical distribution grid;
a Sabatier reactor for making a product in response to a decreased demand for electrical power by the electrical distribution grid;
an ammonia process for making a product in response to a decreased demand for electrical power by the electrical distribution grid; and
a methanol process for making a product in response to a decreased demand for electrical power by the electrical distribution grid.
In a further advantageous embodiment, there is provided the step of operating a secondary electrical generation arrangement that produces additional electrical power in response to an increased demand for electrical power by the electrical distribution grid. In accordance with the invention, the step of operating a secondary electrical generation arrangement is performed in response to the production of the product gas by the reactor.
Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which:
a and 2b are a simplified schematic representations of a high temperature heat reclamation arrangement constructed in accordance with the principles of the invention;
Direct or indirect acting plasma torches 120 are used in this specific illustrative embodiment of the invention to excite plasma reactor 110. In a preferred mode of operation plasma reactor 110 is operated in a pyrolysis mode with compressed MSW as the feedstock. However, plasma reactor 110 can be operated in a non pyrolysis mode in the practice of the invention. Additives 122 are optionally delivered to plasma reactor 110 to neutralize the acid or base content (not specifically designated) of a product gas 125 that is conducted along an outlet duct 130. Product gas 125 exits the plasma reactor at approximately 1250° C., and approximately 27% of the total energy that is present in product gas 125 from the plasma reactor 110 primarily is in the form of sensible heat. Due to the extreme temperature and composition of product gas 125, most of the heat energy has heretofore usually been wasted. The present invention includes within its scope several methods of utilizing this energy more effectively. In this embodiment, the heat contained in product gas 125 is recovered in a high temperature heat reclamation system 135, that is described in greater detail in
a and 2b are a simplified schematic representations of an illustrative high temperature heat reclamation system 135a constructed in accordance with the principles of the invention. Elements of structure that have previously been discussed are similarly designated. Referring for the moment to
Referring once again to
Referring once again to
In a 2,500 Ton per Day (TPD) MSW plant the net continuous carbon free electrical output from this stage would be approximately 31 MW. Spent steam 215 is returned through a condenser 218, and is recharged through high temperature heat reclamation system 135, as previously described.
It is noteworthy that the generated electrical power is actually carbon negative in this application since the typical make up of MSW contains significant amounts of biomass that captures CO2 from the atmosphere prior to being processed in plasma reactor 110. Additional greenhouse gas credits are produced due to the avoidance of escaping gaseous pollution from landfills. Pure biomass will produce greater power with reduced greenhouse gas emissions.
At the other extreme of the feedstock 112 scale is coal with an illustrative BTU content of approximately 14,120 btu/lb. If coal is used as feedstock 112 in a 2,500 TPD plant, the net electrical output 210 of this stage will be approximately 90 MW. This power is carbon free since no exhaust gas is released to the atmosphere in the production of the power. A combination of biomass, MSW, and coal will produce a proportionate amount of net electrical energy 210.
Product gas 125a that has been passed through high temperature heat reclamation system 135 is routed, in this specific illustrative embodiment of the invention, through control valves 230-233 to produce various products. It is to be noted that plant system 100 can employ one or more, in any combination, of reactors 240-243. In this embodiment of the invention, methanol reactor 243 issues CH3OH at an output 262 thereof, which as will be described in connection with
Referring once again to
Each of reactors 240-243 reclaim any heat possible as shown in steam loop 253. The additional steam loops to the balance of the reactors have not been shown for clarity. A Sabatier Reactor 241 produces CH4 as its output product. An ammonia process 242 produces feed stock for fertilizer or munitions, and a methanol reactor 243 produces methanol as its output product, specifically CH3OH, at an output 262.
During peak electrical demand hours reactors 240-243 are bypassed and product gas 125a is directed to secondary power generation system 260. A conventional combined cycle power plant is represented in
A secondary steam turbine 290 is shown in this figure with an associated heat reclamation system 292. The heat reclamation system in this embodiment of the invention has incorporated therewith a condenser 295 that receives the exhaust (not specifically designated) of secondary steam turbine 290. Net carbon neutral or carbon negative electrical energy produced at 2,500 TPD of MSW from combined outputs 282 and 294 is ˜146 MW. When combined with output 210 of carbon free power the plant nets ˜177 MW of peak continuous power in a carbon negative mode of operation.
When operated on coal as the feedstock, the coal carbon positive output 282 and 294 combined is ˜383 MW. This power is produced at about 0.94 lbs CO2 per KWh or 223% cleaner than today's normal coal power plant. When the carbon free plant power 210 is added, the total plant peak continuous electrical output is increased to 473 MW at 0.64 Lbs CO2 per KWh which is approximately 328% cleaner than conventional coal power plants and approximately 205% better than the natural gas power plants in use today. These values are based on the flexible manufacturing assumptions of twelve hours per day of plastic production (or any other product) plus production of the plant's electrical base output from steam turbine 200, (electrical output 210, shown in
Additional benefits of the present flexible manufacturing system include the output of a slag outlet 304 (
Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art may, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the invention described herein. Accordingly, it is to be understood that the drawing and description in this disclosure are proffered to facilitate comprehension of the invention, and should not be construed to limit the scope thereof.
This application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/208,483 filed on Feb. 24, 2009, Confirmation No. 5941 (Foreign Filing License granted). The disclosure in the identified provisional patent application is incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US10/00565 | 2/24/2010 | WO | 00 | 4/13/2012 |
Number | Date | Country | |
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61208483 | Feb 2009 | US |