Patent Abstract:
Disclosed is an advanced process that relates to the enhanced production of energy using the integration of multiple thermal cycles (Brayton and Rankine) that employ multiple fuels, multiple working fluids, turbines and equipment. The method includes providing a nuclear reactor, reactor working fluid, heat exchangers, compressors, and multiple turbines to drive compressors that pressurize a humidified working fluid that is combusted with fuel fired in at least one gas turbine. The turbine(s) provide for electrical energy, processes or other mechanical loads.

Full Description:
BACKGROUND 
     The present invention relates to a new and improved process that integrates a nuclear closed-system regenerative gas turbine (Brayton) cycle, an open-system regenerative combustion turbine (Brayton) cycle, and Rankine steam cycles. 
     Prior art advanced nuclear power plants employing regenerative Brayton cycles, such as the Modular Helium Reactor (˜600 thermal megawatts nuclear reactor) and the Pebble Bed Reactor (˜265 thermal megawatts nuclear reactor), are designed to provide a high level of safety by employing passive reactor emergency cooling systems. However, in order to achieve this level of safety, the thermal output of the reactor must be limited, which in turn restricts electrical energy production. The relatively high capital cost of the technology causes the installed cost of the power plant to be less competitive relative to more conventional technologies, such as combined cycle gas turbine cycles, in spite of the lower cost of the nuclear fuel. 
     The above advanced nuclear power plants are capable of achieving thermal efficiencies approaching 50 percent and electrical outputs of approaching 270 megawatts. This contrasts with advanced combined cycle power plant cycles, such as those using steam cooled gas turbines, that possess thermal efficiencies approaching 60 percent or more and net outputs beyond 700 megawatts. While the advanced nuclear plant efficiencies are impressive relative to the mid-30-percent efficiencies of conventional light water nuclear reactor power plants, the combined cycle power plants remain the choice of the market place, in spite of the low fuel costs and minimal air pollution associated with advanced and conventional nuclear power plants. 
     Prior art and planned advanced nuclear power plants employ regenerative Brayton cycles that utilize turbines directly coupled to electrical generators. In the event of the sudden loss of the generator&#39;s electrical load, rapid and severe pressure and thermal transients can occur in the reactor systems. Special design features are required in order to avoid damage to the reactor. 
     Prior art gas turbines and combined cycle power plants typically employ electrical generators directly coupled to the gas turbine and compressors that pressurize the working fluid. This arrangement causes the rotating equipment to operate at a constant speed. In order to reduce the electrical output of the generator, the firing temperature of the gas turbine must be reduced and/or air flow restricted by means dampers. Both of these methods adversely impact the thermal efficiency of the power plant, thereby increasing the cost to operate the facility as the electrical load is reduced. The power market is such that wide variations in power plant load requirements are a typical situation. 
     Prior art gas turbines have been proposed to utilize waste heat from the Brayton cycle to add vapor into the turbine working fluid at points downstream from the air compressors, with the added mass of the working fluid used to increase the output of the gas turbine while also decreasing compressor power needs. In effect, these cycles combine a Rankine steam cycle in parallel with the Brayton cycle by evaporating water into the working fluid. In general, Brayton cycles become more efficient at higher working fluid pressures, which lead to corresponding higher compressor discharge temperatures. However, the humidification process is practically more effective at lower pressures. Further, the waste heat utilized by the evaporation process is, by definition, associated with lower temperatures from which useful energy could not otherwise be extracted. 
     Prior art combined cycle power plants can increase steam production (and ultimately, electrical generation) by combusting fuel using duct burners located in a heat recovery steam generator unit. However, the increased generation is at the expense of a reduction in overall thermal cycle efficiency because a single working fluid (water) and thermal cycle (Rankine steam cycle) are used. 
     Prior art advanced combined cycle power plants, while very efficient, still require large quantities of fuel fired in the gas turbines that drive the generators used to produce electrical energy as well as drive the compressors that pressurize the working fluid. The fuel can represent more than 70 percent of the cost to operate the facility. Fuel prices can be volatile, which can cause difficulties in the financial structure of the power plant investment. 
     The power industry is faced with increasingly restrictive regulations concerning all types of emissions as a result of the collective desire for a cleaner environment. These restrictions are becoming progressively more difficult for fossil fuel facilities to achieve. 
     Prior art coal gasification plants are able to achieve relatively clean air emissions when the fuel produced by the gasifier is fired in combustion turbines. However, the capital cost of the integrated gasification combined cycle (IGCC) plant is high, thus causing the cost of energy produced from the facilities to be marginally competitive, at best. In addition, the units can produce hydrogen for possible use as an energy source, but at high costs and with limited production capabilities. 
     Accordingly, there is a need to develop a more integrated solution to the above issues. 
     SUMMARY 
     The present invention demonstrates a process and system for combining a nuclear reactor-based, closed-system, regenerative Brayton thermal cycle with a gas turbine-based, open-system, regenerative Brayton thermal cycle and Rankine or steam cycles to create an integrated, advanced, hybrid facility for producing electric power or mechanical energy or supporting processes. 
     The present invention increases the electrical and/or mechanical capabilities of a nuclear power plant while retaining passive emergency heat removal capabilities of advanced nuclear reactors. In addition, another objective is to provide for emergency cooling of the reactor using power generation equipment, with decay heat removed from the reactor through heat exchangers and/or intercoolers. The present invention enhances the capability of the nuclear reactor to safely accommodate severe disturbances in the electrical grid. 
     In more detail, the present invention involves using a nuclear reactor to heat a compressed working fluid that is expanded by turbines that rotate a reactor plant&#39;s compressors, as well as air compressors of a compressor plant. Heat exchangers are used to transfer low-grade heat, from the working fluid, to the moisture addition equipment located downstream from the air compressor plant. In addition, intercooler heat exchangers are used to further cool the working fluid prior to entry into the compressors that pressurize the working fluid of the reactor plant, thereby reducing compressor power needs. A regenerative heat exchanger is used to pre-heat the working fluid, prior to re-entry into the reactor, by transferring heat from the hot working fluid discharged from the turbines. 
     The compressor plant includes multiple compressors used to pressurize the open-system working fluid to levels suitable for use with the gas turbines of a turbine plant. The working fluid is directed sequentially into low, intermediate and high pressure compressors from which the fluid is discharged into the moisture addition unit. Intercooler heat exchangers are used to cool the working fluid prior to entry into the compressor plant&#39;s intermediate and high pressure compressors, thereby reducing compressor power needs and optimizing the moisture addition process. A portion of this waste energy associated with cooling the air is used to heat water directed to a vapor addition unit, while the remaining waste energy is directed to heat sinks. 
     The vapor addition unit includes a vessel into which hot liquid fluid is sprayed and mixed with the relatively cool working fluid discharged from the compressor plant. Within the vessel, hot fluid is evaporated, thereby adding vapor as well as heat to the working fluid that is subsequently directed to a heat recovery unit. The vapor addition unit allows for the direct integration of a Rankine steam cycle into the Brayton or gas turbine cycle. 
     The heat recovery unit includes a series of heat exchangers past which flow hot combusted vapors discharged from the gas turbine. Included are regenerative heat exchangers that add energy to the moisturized working fluid discharged from the vapor addition unit. The regenerative heat exchanger decreases the fuel requirements of the gas turbine by increasing the temperature of the working fluid prior to combustion. The heated, vapor-laden working fluid is then directed into the gas turbine. Additional heat can also be added to the gas turbine exhaust by firing duct burners located within the heat recovery unit. The heat recovery unit also transfers waste energy into fluid discharged from heat exchangers located in the reactor plant, with the heated fluid then directed to the vapor addition unit. The heat recovery unit also transfers gas turbine exhaust heat to water that is transformed into vapors and subsequently used by a steam turbine. The preceding represents another Rankine cycle, but in this case, the steam cycle is sequentially coupled after the open-system, Brayton cycle. 
     The turbine plant includes a gas turbine and a steam turbine. In the case of the gas turbine, fuel is combined with moisture-laden, pressurized air from the compressor plant, then is ignited and directed into rotating turbine blades. Combustion products exhausted from the gas turbine are directed into the heat recovery unit. A steam turbine provides cooling vapors to the gas turbine, with the vapors created within the heat recovery unit. Vapors exhausted from the steam turbine are typically condensed for re-use. 
     The electric plant includes two generators driven by the gas and steam turbines. The gas turbine generator is not coupled to the compressor plant during normal operation. However, a clutch is provided to support start-up of the reactor&#39;s turbine and the gas turbine by temporarily using the generator as a motor. The generator/motor mode can also be used for indirectly cooling the reactor by rotating the compressors and removing heat through the reactor plant&#39;s intercoolers and heater exchangers associated with the vapor addition unit. 
     Vapor in the exhaust from the gas turbine is recovered within the heat recovery unit for re-use in the vapor addition unit by employing a water cooled heat exchanger and/or sprays to condense the water vapor. 
     Control of the power generated by the facility is achieved largely within the reactor plant and vapor addition unit by altering the mass flow of the working fluid. The rotating speed of the compressors is thus altered, which subsequently causes the energy output of the gas turbine to change, thereby altering the output of the primary electrical generator. 
     The reactor plant includes an accumulator/receiver vessel located between the discharge of the high-pressure compressor and lower pressure discharge piping from the regenerator heat exchanger. The accumulator/receiver allows for altering the density of the reactor plant&#39;s working fluid, thereby affecting both the mass flow and the pressure of the working fluid. The variable density of the reactor plant&#39;s working fluid allows for altering the speed of the turbine, which in turn varies the speed of the air compressors of the compressor plant which alters the mass flow through the constant speed gas turbine. This arrangement provides for minimal impacts on the efficiency of the overall process, within the operational limits of the compressors. 
     Additional control of the output of the gas turbine&#39;s electrical generator can be achieved by altering the amount of fluid sprayed into the vapor addition unit, thereby altering the flow of moisture laden vapors through the gas turbine. The energy output of the gas turbines is also affected by the quantity of vapor in the working fluid. 
     In the event of a sudden, complete loss of electrical load by the gas turbine&#39;s generator, reactor power is reduced at a controlled rate while the gas turbine&#39;s pressurized open-system working fluid is discharged to the atmosphere from the compressor plant. The compressors are not coupled to the gas turbine&#39;s electrical generator and as such reactor operations can be reduced as safety and design capabilities warrant. Also, an accumulator/receiver is provided between the gas turbine and steam turbine to provide temporary emergency cooling of the gas turbine in the event of the sudden loss of the steam turbine that normally supplies cooling steam to the gas turbine. 
     A variation of the present invention, in more detail relative to coal gasification, the facility described above can be configured to provide steam and compressed air to a coal gasification facility that then produces oxygen from the compressed air, creates a fuel gas by combining the coal, steam and oxygen and then cleans the fuel gas. This gas can be used by the gas turbine of the hybrid nuclear facility. In addition, the gasification plant can provide energy for vapor and steam production within the hybrid nuclear facility. 
     A further adaptation of the nuclear integrated coal gasification process using the hybrid nuclear turbine is to employ an electrolysis plant to provide the oxygen needed by the gasifier, in lieu of compressed air from the hybrid nuclear facility&#39;s air compressor. The electrolysis co-product, hydrogen, would be sold by the integrated energy production facility. Additionally, the nuclear plant can provide heat to the electrolysis plant to increase the efficiency of hydrogen production, thereby decreasing the cost of the product. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall process diagram of the present invention. 
         FIG. 1A  is a process diagram of the reactor plant portion of the present invention and a process diagram of the emergency electrical portion of the present invention. 
         FIG. 1B  is a process diagram of the compressor plant portion of the present invention. 
         FIG. 1C  is a process diagram of the turbine and electrical plants portion of the present invention as well as process diagram of the heat and water recovery portions of the present invention. 
         FIG. 1D  is an overall process diagram of an additional version of the present invention. 
         FIG. 1E  is an overall process diagram of a simple version of the present invention. 
         FIG. 1F  is an overall process diagram of the present invention used with a coal gasification plant. 
         FIG. 2  is a graph of the effect of air evaporative cooling. 
         FIG. 3  is an overall process diagram of prior art typical combined cycle power plant. 
         FIGS. 4A and 4B  are process diagrams of coal gasification applications used with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring initially to  FIG. 1 , a process for producing power is illustrated utilizing a Reactor Plant I, Compressor Plant II, Vapor Addition Unit III, Heat Recovery Unit IV, Turbine Plant V, Electrical Plant VI, and Water Recovery Unit VII. The actual physical sequential alignment and arrangement of the equipment, interconnecting rotating shafts and/or spools, as well as interconnecting ductwork will vary depending on the specific desired configuration of the processes using the rotational energy provided by the invention. In particular, those skilled in the art will recognize that variations of this invention include selectively coupling through spooling and shafting groups of compressors and turbines. For instance, the low-pressure compressors of the closed-system, the compressors of the open-system, and several stages of the closed-system turbine could be mounted on a single shaft with the high-pressure compressor of the closed-system coupled through spooling to the remaining stages of the closed-system turbine, thus allowing the compressor sets to rotate at different but optimized conditions. 
     Referring to  FIGS. 1 and 1A , the Reactor Plant I includes a nuclear reactor  1 , multistage compressors  4  and  5 , multi-stage turbine  2 , interconnecting shafting or spooling A, B, C and K, interconnecting ducting  000  through  011 , and heat exchangers  33 ,  34 ,  65  and  66 . The components include a closed-system gas circulation, regenerative Brayton cycle containing a gas cooled nuclear reactor  1 . The reactor is somewhat similar to a gas turbine-modular helium reactor (GT-MHR) in that the reactor core is graphite and cooled by helium. However, the reactor  1  may be about two-thirds the size of a typical GT-MHR. Additionally, the turbines  2  as well as compressors  4  and  5  of the reactor plant do not operate at a constant speed as is required if the turbines rotate an electrical generator. The compressors  4  and  5  and heat exchangers  33 ,  34 ,  65  and  66  are located within a compact steel vessel for protective purposes. The turbine  2  and compressors  4  and  5  are oriented horizontally instead of the GT-MHR vertically orientation to properly mate with the air compressors and main electrical generator. The reactor  1  is preferably located underground and the reactor plant components are also located in a steel and concrete containment building for further protection. 
     The reactor  1  heats a pressurized gaseous cooling medium, such as helium, serving as the working fluid that is routed through ducting  000  and expanded through multi-stage turbine  2 . Multi-stage turbine  2  is mounted to shafts or spooling B and C that drive compressors  4  and  5 . The turbine  2  is also mounted to a shaft or spooling A and B that drive compressors  11  and  12 . Compressors  11  and  12  pressurize the open-system working fluid of the Compressor Plant II. The closed-system working fluid is expanded through the multi-stage turbine  2  that directs the fluid through ducting  001  to a regenerative heat exchanger or recuperator  3 . The regenerative heat exchanger  3  transfers energy to the closed-system working fluid prior to re-entry to the reactor  1 . 
     The cooled closed-system working fluid is discharged from the regenerative heat exchanger  3  through ducting  002  and directed to a heat exchanger  33  to transfer energy to the liquid fluid of the Vapor Addition Unit III by ducting  307 ,  308 , heat exchanger  36  and ducting  309 . The closed-system working fluid is then directed through ducting  003  to intercooler heat exchanger  65 . Intercooler heat exchanger  65  removes energy from the closed-system working fluid to a heat sink prior to entry of the closed-system working through ducting  004  into a low pressure compressor  4 . 
     Low pressure compressor  4  then directs the pressurized closed-system working fluid through ducting  005  to another heat exchanger  34 . Heat exchanger  34  transfers energy to the liquid fluid directed to the Vapor Addition Unit III by ducting  311 , heat exchanger  37  and ducting  312 . The closed-system working fluid is then directed through ducting  006  to a heat exchanger intercooler  66  to remove energy to a heat sink prior to entry of the closed-system working fluid through ducting  007  to the high-pressure compressor  5 . High-pressure compressor  5  fully pressurizes the closed-system working fluid prior to entry through ducting  008  to the regenerative heat exchanger  3  that pre-heats the closed-system working fluid prior to re-entry through ducting  009  to the reactor  1 . The helium working fluid is cooled between the high  5  and low  4  pressure compressors. A portion of the energy is used to heat water destined for the Vapor Addition Unit III designed to add moisture to the compressed air of the open-system working fluid. 
     The thermodynamic characteristics of an illustrative example of the regenerative, Brayton closed-system are summarized in the table below. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 Typical Thermodynamic Characteristics - Reactor Plant I 
               
             
          
           
               
                   
                 Pressure 
                 Temperature 
                   
               
             
          
           
               
                   
                 Power 
                 (inlet) 
                 in 
                 out 
                 Flow 
                 Working 
                 Pressure 
               
             
          
           
               
                   
                 mW 
                 Psia 
                 ° F. 
                 lbm/sec 
                 Fluid 
                 Ratio 
               
               
                   
                   
               
             
          
           
               
                 Reactor 1 (gross) 
                 429 
                 1030 
                 960 
                 1565 
                 540 
                 Helium 
                   
               
               
                 Turbine 2 
                 389 
                 1015 
                 1560 
                 1015 
                 540 
                 Helium 
                 2.4 
               
               
                 LP Compressor 4 
                 (85) 
                 415 
                 65 
                 190 
                 540 
                 Helium 
                 1.6 
               
               
                 HP Compressor 5 
                 (85) 
                 650 
                 65 
                 190 
                 540 
                 Helium 
                 1.6 
               
               
                 Output subtotal 
                 215 
               
               
                   
               
             
          
         
       
     
     The above summary characteristics are provided for illustrative purposes only and are based on the published capabilities of a Modular Helium Reactor. As will be observed as part of the detailed discussion of the Compressor Plant II, the Reactor Plant I&#39;s power output matches the power requirements of the open-system Brayton cycle portion of the system. 
     Routine control of the Reactor Plant I compressors  4  and  5  (as well as compressors  11 ,  12 , and  13  of the Compressor Plant II) is achieved by altering the density of the closed-system working fluid, which alters the mass flow and pressure. More specifically, an accumulator/receiver vessel  6 , ducting  010  and  011 , as well as control valves  6 A and  6 B, are provided between the discharge ducting  008  of the high-pressure compressor  5  and the discharge ducting  002  from the regenerator  3 . 
     As can be observed in the preceding example, a pressure differential of approximately 600 psia exists between the ducting  002  and  008 . The speed of the compressors is reduced by opening control valve  6 A while control valve  6 B is closed, thereby removing working fluid from the primary circuit. This also reduces the pressure of the system. The process is reversed to increase the speed of the compressors by reintroducing the higher pressure working fluid stored within the accumulator/receiver vessel  6  into ducting  008 . 
     The reactor&#39;s  1  control rods are moved as necessary to maintain stable reactor outlet temperatures, thereby maintaining steady thermal conditions within the reactor  1 . The accumulator/receiver vessel  6  and control components are sized to ensure compressors  4  and  5  operate within their optimum operational limitations. 
     Referring to  FIGS. 1 and 1B , the Compressor Plant II includes compressors  11 ,  12 , and  13  driven by the turbines  2  of the Reactor Plant I, interconnecting shafting or spooling C, D, E, F, and clutch G, interconnecting ducting  100  through  109  and heat exchangers  31 ,  32 ,  63 , and  64 . These components include part of an open-system Brayton cycle with the ambient working fluid directed by ducting  100  into the low-pressure compressor  11 . Low-pressure compressor  11  partially pressurizes the open-system working fluid that is then directed by ducting  101  to a heat exchanger  32 . Heat exchanger  32  transfers energy to the working liquid fluid of the Vapor Addition Unit III. 
     Conventional gas turbine compressors are used to pressurize the open system working fluid (air). Low-pressure, intermediate-pressure and high-pressure air compressors, which are rotated by the helium gas turbines of the reactor plant, are used to sequentially increase the pressure of the air ultimately directed into the gas turbine. In order to increase the efficiency of the power plant, the air temperature is reduced between the compressors. In addition, some low-grade energy is used to heat water subsequently vaporized into the air stream. 
     The open-system working fluid is then directed by ducting  102  to an intercooler heat exchanger  64  to remove energy to the heat sink prior to entry of the open-system working fluid through ducting  103  into an intermediate-pressure compressor  12 . Intermediate-pressure compressor  12  partially pressurizes the open-system working fluid. The open-system working fluid is then directed by ducting  104  to heat exchanger  31  which transfers energy to the liquid fluid of the Vapor Addition Unit III. 
     The open-system working fluid is then directed by ducting  105  to intercooler heat exchanger  63  to remove energy to the heat sink prior to entry of the open-system working fluid through ducting  106  into the high-pressure compressor  13 . The high-pressure compressor  13  fully pressurizes the open-system working fluid that is then directed by ducting  107  to the saturator vessel  35  of the Vapor Addition Unit III. The open-system working fluid is directed by ducting  108  to the heat exchangers  15  of the Heat Recovery Unit IV where the moisture laden working fluid is heated by the exhaust from the gas turbine  17  prior to entry into the Turbine Plant V through ducting  109 . 
     An illustrative example of the thermodynamic characteristics of the Compressor Plant II are summarized below 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 Thermodynamic Characteristics - Compressor Plant II 
               
             
          
           
               
                   
                 Pressure 
                 Temperature 
                   
               
             
          
           
               
                   
                 Power 
                 (inlet) 
                 In 
                 out 
                 Flow 
                 Working 
                 Pressure 
               
             
          
           
               
                   
                 mW 
                 Psia 
                 ° F. 
                 Lbm/sec 
                 Fluid 
                 Ratio 
               
               
                   
                   
               
             
          
           
               
                 LP Compressor 11 
                 (102) 
                 14.7 
                 55 
                 350 
                 1205 
                 Air 
                 4.9 
               
               
                 IP Compressor 12 
                 (106) 
                 62 
                 70 
                 378 
                 1195 
                 Air 
                 4.9 
               
               
                 HP Compressor 13 
                  (7) 
                 288 
                 70 
                 92 
                 1190 
                 Air 
                 1.14 
               
               
                 subtotal 
                 (215) 
               
               
                   
               
             
          
         
       
     
     The Compressor Plant&#39;s II low-pressure compressor  11  and intermediate-pressure compressor  12  may be multistage axial-flow compressors, while the high-pressure compressor  13  may be a centrifugal-flow compressor as the latter type of compressor is less adversely affected by pressure surges that can occur during transients associated with the relatively long ducting lengths to the gas turbine  17 . The high-pressure compressor  13  is also sized (by virtue of a low pressure ratio) in to achieve relatively low temperatures of the open-system working fluid entering the vapor addition unit III, thereby reducing thermodynamic irreversibilities associated with the moisture addition process. 
     In particular, referring to  FIGS. 1 ,  1 B and  2 , as the temperature of the entering open-system working fluid in ducting  107  increases, the evaporative process causes liquid fluid exiting through ducting  300  to also increase. However, the higher exit liquid temperature reduces the quantity of low grade energy that can be removed from the working fluids by heat exchangers  31 ,  32 ,  33  and  34 . As such, optimization of the overall thermal cycle lies more with achieving relatively lower temperatures of the open-system working fluid entering the Vapor Addition Unit III through ducting  107 . 
     Referring to  FIGS. 1 ,  1 A and  1 B, control of the Compressor Plant II is achieved within the Reactor Plant I by varying the density (and mass flow) of the closed-system working fluid. This provides for the varying the speed of compressors  11 ,  12 , and  13 , thus altering the mass flow of the open-system working fluid. Additional control measures include not normally directly coupling compressor  11 ,  12 , and  13  to the turbine  17  or electric generator  50  during power operations. In the event of loss of the gas turbine  17  or electrical generator  50 , open-system working fluid is discharged to ambient through ducting  110  and  111  as well as control valves  13 A and  13 B, with the Reactor Plant I and Compressor Plant II operations reduced as appropriate. This feature allows continued operation of the Reactor Plant I during severe plant transients, thereby minimizing thermally induced stress on the reactor  1 . 
     A clutch G is provided between shaft F of the Compressor Plant II and shaft H of the Turbine Plant V. The clutch G is employed during startup of the Reactor Plant I and Turbine Plant VI to support sequential rotation of turbines  2  and  17  using generator  50  as a motor. Additionally, this same arrangement provides for emergency cooling of the reactor  1 , with reactor decay heat removed through the heat exchangers  33  and  34  to the heat sink or through heat exchangers  65  and  66  (bypassing heat exchangers  36  and  37 ) to ambient by way of saturator vessel  35  and ducting  108  and  111 , using control valve  13 B. The clutch G is positioned between air compressors and main electrical generator. The clutch G is not normally engaged during power operations. 
     As shown on  FIG. 1A , a diesel engine  52 , clutch L and geared speed reducer N coupled to shafts K, M O and P can be used to support reactor emergency cooling by rotating the compressors  4  and  5 , with heat removed through the intercoolers  65  and  66  or through heat exchangers  33  and  34  and then (referring to  FIG. 1B ) to the atmosphere through saturator  35 . The diesel engine  52  could thus serve as a backup to the electrical generator  53  (acting in a motor mode) that would be normally used to support removal of the reactor&#39;s shutdown decay heat. The diesel engine  52  and clutch L would be typically located outside the containment or confinement building  80  to allow ready access to the engine. 
     As depicted on  FIGS. 1 ,  1 A and  1 B, the Vapor Addition Unit III includes a saturator vessel  35 , heat exchangers  31 ,  32 ,  33 , and  34  as well as ducting  300 - 314  and pumps  30  and  38 . These components direct and heat a fluid that is combined with the working fluid of the open-system Brayton cycle, thereby integrating a Rankine cycle with the open-system Brayton cycle. In particular, open-system working fluid is discharged through ducting  107  from high-pressure compressor  13  into the lower portion of saturator vessel  35 . Hot fluid heated by heat exchangers  31 ,  32 ,  33 ,  34 ,  36  and  37  is contacted counter-currently and evaporated in multiple stages in saturator vessel  35  to add moisture and heat to the open-system working fluid. 
     Liquid fluid not vaporized in the saturator vessel  35  is discharged by ducting  300  to saturator pump  30 . Saturator pump  30  directs the fluid to the Compressor Plant II as well as Reactor Plant I and Heat Recovery Unit IV. Make-up fluid obtained from the Water Recovery Unit VI located within the Heat Recovery Unit IV is directed through ducting  313 , pump  38  and ducting  314  into the bottom of the saturator vessel  35 . 
     The fluid vaporization energy obtained from the Compressor Plant II is transferred by directing fluid from saturator pump  30  through ducting  301  to heat exchanger  31  and then to the saturator vessel  35  through ducting  302  and  303 . Fluid is also directed by pump  30  through ducting  304  to heat exchanger  32  and then to saturator vessel  35  through ducting  305 . 
     Heated fluid from the Reactor Plant I and Heat Recovery Unit IV is obtained by directing fluid from saturator pump  30  to ducting  306  to heat exchanger  33 . The fluid is then directed through ducting  308  to heat exchanger  36  located in Heat Recovery Unit IV. The fluid is then directed to the saturator vessel  35  through ducting  309 . The fluid is also directed from pump  30  through ducting  306  and  310  to heat exchanger  34  and then through ducting  311  to heat exchanger  37  located in Heat Recovery Unit IV and then to the saturator vessel  35  through ducting  312 . This process involves separately injecting the heated fluids into the saturator vessel  35 , at appropriately staggered elevations, in order to minimize thermodynamic irreversibilities (mixing, cooling then ultimately re-heating the fluids). However, the hot fluids directed to the saturator vessel  35  could be combined and injected at one point. 
     The Vapor Addition Unit III reclaims low-grade heat that is not ordinarily recoverable through more conventional means, thereby increasing the capabilities of the overall process. The low grade heat is obtained from the general heat exchanger cooler process used to reduce the energy requirements of the compressors and from the Heat Recovery Unit IV energy not otherwise used by the open-system Brayton and Rankine cycles. In general, inter-cooling of the compressors does not typically increase the efficiency of a combined cycle process. However, the humidification process is able to partially overcome this shortfall by utilizing a portion of the pre-cooler, intercooler and after-cooler low grade energy, thus allowing for a reduction in the mass flow of the open-system working fluid pressurized by compressors  11 ,  12 , and  13 , thereby reducing the energy required for compression. 
     The proportion of low-grade energy used to support the humidification process varies depending on the specifics of the design, an example of which is summarized below. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Low Grade Heat Sources - Vapor Addition Unit III 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Reactor Plant I 
                 ~25% 
               
               
                   
                 Compressor Plant II 
                 ~50% 
               
               
                   
                 Heat Recovery Unit IV 
                 ~25% 
               
               
                   
                 Net 
                 100% 
               
               
                   
                   
               
             
          
         
       
     
     Relative to the heat sources that supply energy to the Vapor Addition Unit III, the contribution is further apportioned as illustratively summarized below. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Low Grade Heat Sources - Reactor Plant I (~25% of total) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 LP compressor 4 pre-cooling 
                 ~60% 
               
               
                   
                 heat sink, 66 
                 ~45% 
               
               
                   
                 vapor addition, 34 
                 ~55% 
               
               
                   
                 HP Compressor 5 Inter-cooling 
                 ~40% 
               
               
                   
                 heat sink, 65 
                 ~60% 
               
               
                   
                 vapor addition, 35 
                 ~40% 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Low Grade Heat Sources - Compressor Plant II (~50% of total) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 IP compressor 12 inter-cooling 
                 ~48% 
               
               
                   
                 heat sink, 64 
                 ~15% 
               
               
                   
                 vapor addition, 32 
                 ~85% 
               
               
                   
                 HP compressor 13 after-cooling 
                 ~52% 
               
               
                   
                 heat sink, 63 
                 ~15% 
               
               
                   
                 vapor addition, 31 
                 ~85% 
               
               
                   
                   
               
             
          
         
       
     
     The humidification process of the illustrated example adds approximately 12% by weight of moisture to the open-system working fluid ultimately directed to gas turbine  17 . 
     Control of the Vapor Addition Unit III is achieved by altering and optimizing the flow of the fluid through all of the heat exchangers  31 ,  32 ,  33 ,  34 ,  36 , and  37 . In general, the total mass flow of the liquid fluid establishes the level of moisture that can be added to the open-system working fluid, with the control strategy based on maximizing the energy extracted from the various heat sources while matching the temperature of the liquid fluid exiting the saturator vessel  35  to the temperature associated with the initial evaporation of the working fluid entering the saturator vessel  35 . Additionally, the ability to alter the liquid fluid mass flow to the saturator vessel  35  allows for reducing the mass flow of the working fluid directed through the gas turbine  17 , thereby providing another means to meet load reduction requirements that may be imposed by the electrical grid. Such reductions, however, will reduce the overall efficiency of the facility as more energy will be lost to the heat sink and/or ambient air. 
     As depicted by  FIGS. 1 and 1C , the Heat Recovery Unit IV includes a structure and insulated casing  20  that house groups of heat exchangers  15 ,  42 ,  36 ,  37 , and  26  that recover the energy and moisture associated with the open-system working fluid exhausted from the gas turbine  17  of the Turbine Plant V, as well as housing duct burners  70  and supply ducting  702  used to fire fuel that adds additional energy to the gas turbine  17  exhaust gas. Because the open-system working fluid pressure of the regenerative heat exchangers  15  is relatively low (approximately 300 psia, for the illustrative example), duct firing temperatures may be significantly higher than those associated with conventional heat recovery steam generators (with heat exchanger internal steam pressures approaching 2000 psia) without exceeding acceptable material stress levels. 
     The duct burner  70  allows for higher plant electrical outputs than otherwise achieved, with the additional energy distributed to all the underlying sub-cycles present within the Heat Recovery Unit IV, namely the integrated Brayton/Rankine cycle created by the Vapor Addition Unit III and gas turbine  17 , as well as the Rankine steam cycle created by heat exchangers  42  and steam turbine  40 . In addition, depending on the emission levels obtained by firing the moisture-laden, open-system working fluid in the combustor  17 A of the gas turbine  17 , a selective catalytic regenerative system employing catalyst and ammonia vapor injection equipment may be housed in the Heat Recovery Unit IV to further reduce Nitrogen Oxide emissions. This equipment has not been shown in  FIGS. 1 and 1C  for drawing simplification purposes. 
     The proportion of energy utilized within the Heat Recovery Unit IV varies depending on the specifics of the design. The majority of the energy associated with the Heat Recovery Unit IV is employed with the regenerative process of the open-system, Brayton cycle. The example provided below is a general illustrative summary of the energy use within the Heat Recovery Unit IV. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Energy Utilization Summary - Heat Recovery Unit IV 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Regenerative heat exchangers 15A-15D 
                 ~79% 
               
               
                   
                 Rankine steam cycle heat exchangers 42A-42D 
                  ~6% 
               
               
                   
                 Vapor addition unit III heat exchangers 36 and 37 
                 ~15% 
               
               
                   
                 Net 
                 100% 
               
               
                   
                   
               
             
          
         
       
     
     The actual number, size and location of the heat exchangers and duct burners located within the Heat Recovery Unit IV may vary as optimized for specific process objectives. Those skilled in the art will recognize that additional duct burners may be placed within the Heat Recovery Unit IV at several locations to generate additional steam if so required by specific process needs. 
     As depicted by  FIGS. 1 and 1C , the Turbine Plant V includes a multi-stage gas turbine  17  of the open-system Brayton cycle and a steam turbine  40  of the Rankine steam cycle, with cooling steam supplied to the gas turbine  17  from the steam turbine  40 . The thermodynamic characteristics of the Turbine Plant V are summarized below for an illustrative example. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Summary Output Characteristics -Turbine Plant V 
               
             
          
           
               
                   
                 Gross 
                 Inlet 
                   
               
               
                   
                 Output, 
                 Pressure, 
               
               
                   
                 mW 
                 psia 
                 Working fluid 
               
               
                   
                   
               
             
          
           
               
                   
                 Gas turbine 17 
                 750 
                 305 
                 Air/vapor 
               
               
                   
                 Steam turbine 40 
                 20 
                 2250 
                 Vapor 
               
               
                   
                 Output subtotal 
                 770 
               
               
                   
                 Gas turbine 17 
                 760 
                 — 
                 natural gas 
               
               
                   
                 fuel energy 
               
               
                   
                   
               
             
          
         
       
     
     The gas turbine  17  portion of the Turbine Plant IV may include ducting  109  that directs moisture-laden, open-system working fluid from the Heat Recovery Unit III into the gas turbine&#39;s combustor  17 A. Fuel supplied by ducting  701  is mixed and ignited in the gas turbine&#39;s combustor  17 A prior to being directed into the rotating turbine blades. The turbine  17  drives the shafting I connected to electrical generator  50 . The multi-stage gas turbine  17  may be of an advanced design (such as the steam cooled General Electric “H” series or Mitsubishi “G” gas turbine), wherein steam is used to help cool the internal components of the turbine exposed to high temperatures. Because of the moderate presence of water vapor, the open-system working fluid possesses much better heat removal capabilities than air. As a result, the gas turbine  17  of the Hybrid Integrated Nuclear Turbine system may require less steam cooling than current advanced designs while possessing the capability to more readily achieve higher firing temperatures, with accompanying higher plant efficiencies. 
     Additionally, the combustor  17 A may be of a “can” or diffuser design with the working fluid flowing straight through, unlike those of traditional heavy frame gas turbines where the working fluid must make several nearly 180 degree turns when exiting from the compressor to the combustor. Accordingly, pressure losses may be much lower with the straight through design. In addition, the firing of moisture-laden air by a gas turbine inherently achieves lower pollution levels, such as Nitrogen Oxide, than conventional gas turbines firing dry air. Thus, less complex pollution control equipment may be used to meet environmental regulations. The weight ratio of water vapor to fuel is approximately 5:1. As such, Nitrogen Oxide emission levels in the vicinity of single digits, on a parts-per-million basis, may be expected without the use of selective catalytic removal systems. Such equipment would, however, likely allow for reaching exceptionally low emission levels. 
     The steam turbine cycle of the Turbine Plant IV may include a small steam turbine  40  provided primarily to efficiently supply cooling steam to the gas turbine  17 . The small size of the steam turbine is the result of most of the energy associated with the gas turbine&#39;s  17  exhaust being used for heating the open-system&#39;s moisture-laden working fluid, as opposed to heating the working fluid of a Rankine steam cycle, as is the case for a combined cycle power plant. The Rankine steam cycle of the Turbine Plant IV includes a condenser  62  where steam exhausted from turbine  40  is cooled and then condensed into liquid water using water cooled by the heat sink. 
     The condensed liquid is directed by ducting  400  to pump  41  that pressurize the fluid that is then directed by ducting  401  to the Heat Recovery Unit IV. Within the Heat Recovery Unit IV, heat exchangers  42 A through  42 D heat, vaporize and then superheat the high pressure fluid that is directed by ducting  402  to the steam turbine  40  wherein intermediate pressure steam is extracted and directed by ducting  403  to gas turbine  17  to provide cooling. Lower pressure, re-heated steam is directed from gas turbine  17  by ducting  404  back to steam turbine  40  where the energy of the steam is used to further increase the output of electrical generator  52  driven by steam turbine  40  through shafting J. Low pressure (vacuum) vapor exhausted from steam turbine  40  is directed back into condenser  62 . 
     The condensed liquid is directed by ducting  400  to pump  41  that pressurize the fluid that is then directed by ducting  401  to the Heat Recovery. Unit IV. Within the Heat Recovery Unit IV, heat exchangers  42 A through  42 D heat, vaporize and then superheat the high pressure fluid that is directed by ducting  402  to the steam turbine  40  wherein intermediate pressure steam is extracted and directed by ducting  403  to gas turbine  17  to provide cooling. Lower pressure, re-heated steam is directed from gas turbine  17  by ducting  404  back to steam turbine  40  where the energy of the steam is used to further increase the output of electrical generator  51  driven by steam turbine  40  through shafting J. Low pressure (vacuum) vapor exhausted from steam turbine  40  is directed back into condenser  62 . 
     Those skilled in the art will recognize that this invention also encompasses designs wherein the gas turbine  17  cooling steam is not directed back to the steam turbine  40 , but is rather directly used by the gas turbine  17 , then exhausted into the Heat Recovery Unit IV with the open-system working fluid. 
     As depicted by  FIGS. 1 and 1C , the Electric Plant VI includes electrical generators  50  and  51  connected by shafting I and J to turbines  17  and  40 . Electrical generator  50  is connected by. shafting I to gas turbine  17  and by shafting H to clutch G. During power generation, the clutch G is not normally engaged. However, during initial start-up of the power plant, clutch G is engaged to shaft F in order to rotate the turbines and compressors of the Reactor Plant I and Compressor Plant II. Electrical generator  51  is connected by shafting J to steam turbine  40 . 
     As depicted by  FIG. 1A , also part of the Electric Plant VI are the emergency diesel  52  connected by shafting P to emergency generator  53  that can supply power to the facility in the event of the loss of off-site power. 
     The generator characteristics of the Electric Plant VI are summarized below as an example. 
     
       
         
               
             
               
               
             
               
               
               
             
           
               
                   
               
               
                 Summary Characteristics - Electrical Plant VI 
               
             
          
           
               
                   
                 Output, mW 
               
               
                   
                   
               
             
          
           
               
                   
                 Gas turbine generator 
                 746 
               
               
                   
                 Steam turbine generator 
                 19 
               
               
                   
                 Generators gross output 
                 765 
               
               
                   
                   
               
             
          
         
       
     
     As depicted by  FIGS. 1 and 1C , the Water Recovery Unit VII is housed within the casing structure  20  of the Heat Recovery Unit IV and is provided to re-capture moisture added to the open-system working fluid by the Vapor Addition Unit III and by combustion of the fuel fired by the gas turbine  17  and duct burners  70 . Water cooled by the heat sinks may be used to condense the moisture contained within the exhaust from the gas turbine  17 , with the cooling water circulated by a heat exchanger  26  located the Heat Recovery Unit IV as well as potentially sprayed directly into the exhaust. 
     The condensed moisture is typically acidic due to absorption of carbon dioxide that is present within the open-system working fluid discharged from the gas turbine  17 . However, a neutralizing vapor (such as ammonia used with a selective catalytic reduction system) can be injected into the Heat Recovery Unit IV to reduce the acidity of the condensate. Equipment to further treat the condensate, as well as makeup water, would also be typically required but has not been shown for drawing simplification purposes. Those skilled in the art will recognize that the present invention also includes use of a heat exchanger (not shown for simplification purposes) to transfer energy from the water condensed in the Water Recovery Unit VII to pre-heat the fuel gas directed to combustor  17 A. 
     The Water Recovery Unit VII is one of the larger heat sink loads which are summarized below for an illustrative example. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Heat Sink Energy Distribution 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Helium pre-cooler 65 
                 10% 
               
               
                   
                 Helium inter-cooler 66 
                  6% 
               
               
                   
                 Air after-cooler 31 
                 16% 
               
               
                   
                 Air inter-cooler 32 
                 11% 
               
               
                   
                 Water recovery 26 
                 38% 
               
               
                   
                 Condenser 62 
                  3% 
               
               
                   
                 Stack 27 
                 16% 
               
               
                   
                 Net 
                 100%  
               
               
                   
                   
               
             
          
         
       
     
     Those skilled in the art will observe that the invention also encompasses the use of refrigeration cooling processes with the intercooler heat sink cooling methods, thereby helping maintain power plant output during conditions of high ambient temperatures. 
     The use of the Vapor Addition Unit III allows a Rankine steam cycle to be directly integrated into the open-system gas turbine cycle. However, the vapor addition process using intercooler waste heat also reduces the temperature of the working fluid discharged from the compressors. Ordinarily, such a condition would require the use of more fuel to achieve the firing temperature of the gas turbine  17 . Additionally, the moisture added to the open-system working fluid also requires the use of more fuel relative to simply firing air and fuel mixture in the combustor  17 A of the gas turbine  17 . However, these detrimental effects on the overall cycle efficiency are overcome by the following: 
     (a) Reducing the energy required for compression of the open-system working fluid by adding moisture into the working fluid downstream of the compressors by way of the evaporative process occurring in the moisture addition vessel. The pressurizing of the liquid used with evaporative process requires significantly less energy than compression of the open-cycle working fluid. 
     (b) Use of highly efficient, gas cooled, nuclear reactor-based, closed-system gas turbines to provide the energy to drive the compressors of the open-system, regenerative, Brayton cycle. The closed-system working fluid is typically Helium which has a more favorable “k” (ratio of heat capacity at constant pressure to heat capacity at constant volume) than air, thus providing for more efficient compression of the open-system working fluid than could be achieved if the turbine employed air as a working fluid. 
     (c) Use of a very high temperature (approaching or exceeding 2600 F) Rankine steam cycle integrated with the Brayton gas turbine open-system. Although the integrated Rankine cycle discharge pressure is at atmospheric conditions (vice at a vacuum as is the case with a conventional Rankine cycle), the net energy associated with the integrated Rankine cycle tends to exceed the energy that could be obtained if a conventional steam cycle were used. The later conventional Rankine steam cycle is typically limited to a temperature of approximately 1060 degrees F. and pressure of approximately 2000 psia due to material limitations. 
     (d) Use of higher gas turbine mass flows than ordinarily achieved at standard temperatures (59 F) if only air and fuel were fired in the gas turbine. The higher mass flow is as a result of the vapor addition process, with the net mass flow though turbine approximately that of the maximum design flow through the turbine (this typically occurs at a temperature of 10 F). The mass flow through the gas turbine is thus held relatively constant by the processes of this invention. 
     (e) Use of duct firing in the Heat Recovery Unit III to achieve very high temperatures for the regenerative portion of the open-system Brayton cycle. 
     (f) Use of multiple working fluids within the Heat Recovery Unit III to maximize heat utilization. 
     The net result of the above is that the process of the present invention is expected to approach or exceed thermal cycle efficiencies of 63 percent. 
     As depicted by  FIG. 1D , a variation on the present invention would involve removal of the high-pressure compressor  13  of  FIG. 1  while using the low-pressure compressor  11  and intermediate-pressure compressor  12  designed to pressurize the open system working fluid to the required levels. All other components would remain as depicted in  FIG. 1 . This simplified design would yield a more efficient and cost effective power plant, provided the compressor designs can accommodate open-system working fluid transient (surge) conditions. 
     As depicted by  FIG. 1E , a simplified version of the present invention would not utilize the Vapor Addition Plant III and open-system regenerative process. Instead, the energy from gas turbine exhaust would be used with a Rankine thermal cycle aligned in series with the open system Brayton cycle, similar in part to prior art combined cycle power plant designs. However, the Reactor Plant turbine A 2  would rotate the closed system&#39;s single compressor A 4  and Compressor Plant&#39;s single compressor A 11 . A pre-cooler A 65  would reduce the temperature of the closed system working fluid prior to being directed to compressor A 4 . Gas turbine A 17  would rotate generator A 50 , with clutch AG used for plant start-up. The Heat Recovery Unit A 20  is a 3 pressure configuration with steam turbine A 40 , consisting of a high-pressure (HP), re-heat (RH) and low-pressure (LP) sections rotating generator A 51 . Pumps A 41 - 1  and A 41 - 2  would pump water from condenser A 62  to Heat Recovery Unit A 20 . This design would be a simplified variant of the present invention. The simplest version of the present invention would omit the steam production (Heat Recovery Unit and steam turbine) portion of the plant and simply direct the open-system working fluid exhausted from the gas turbine A 17  to the atmosphere. 
     The advantages of the present invention become clearer when contrasted against similar and existing technologies. More specifically, comparison are made between: the preferred embodiment of the present invention as depicted by  FIG. 1 ; the simplified variant of the present invention, as depicted by  FIG. 1E ; and a conventional combined cycle power plant, as depicted by  FIG. 3  and consisting of air compressor, gas turbine, electrical generator, heat recovery steam generator and steam turbine. 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Performance and Cost Summary Comparison 
               
             
          
           
               
                   
                   
                 Simple Hybrid 
                 Hybrid 
               
               
                   
                 Combined 
                 Integrated 
                 Integrated 
               
               
                   
                 Cycle, 
                 Nuclear 
                 Nuclear 
               
               
                   
                 2 × 1 
                 Turbine 
                 Turbine 
               
               
                   
                 Plant 
                 Plant 
                 Plant 
               
               
                 Process Summary 
                 FIG. 4 
                 FIG. 3 
                 FIG. 1 
               
               
                   
               
             
          
           
               
                 Net Output, mW 
                 760 
                 660 
                 750 
               
               
                 Gas turbine(s) 
                 528 
                 549 
                 746 
               
               
                 Steam turbine 
                 245 
                 127 
                 19 
               
               
                 Auxiliary load 
                 (23) 
                 (16) 
                 (15) 
               
               
                 Reactor Output, mW 
                 n/a 
                 697 
                 429 
               
               
                 Plant Heat Rate, 
                 6050 
                 6450 
                 5390 
               
               
                 BTU/kWh (LHV) 
               
               
                 Net Plant Efficiency 
                 56% 
                 53% 
                 63% 
               
               
                 (LHV) 
               
               
                 Net Generation, × 
                 6.5 
                 5.5 
                 6.4 
               
               
                 10{circumflex over ( )}6 mWh 
               
               
                 Fuel Gas Usage, 
                 40 
                 20 
                 22 
               
               
                 mmBTU/year × 10{circumflex over ( )}6 
               
               
                 Fissile Fuel Usage, 
                 n/a 
                 20 
                 12 
               
               
                 mmBTU/year × 10{circumflex over ( )}6 
               
               
                 Fuel Gas Cost, 
                 261 
                 131 
                 145 
               
               
                 $(US) × 10{circumflex over ( )}6/year 
               
               
                 Reactor Fuel Cost, 
                 n/a 
                 41 
                 25 
               
               
                 $(US) × 10{circumflex over ( )}6/year 
               
               
                 Net Fuel Cost, 
                 261 
                 172 
                 170 
               
               
                 $(US) × 10{circumflex over ( )}6/year 
               
               
                 Variable Fuel Cost, 
                 41 
                 30 
                 27 
               
               
                 $/mWh/year 
               
               
                 Notes 
                 1, 4, 7 
                 2, 4, 
                 2, 3, 4, 
               
               
                   
                   
                 5, 6, 7 
                 5, 6, 7 
               
               
                   
               
               
                 Notes: 
               
               
                 1. 2 × 1 501 G configuration, 2 gas turbines × 1 steam turbine, Mitsubishi Heavy Industries, per “Gas Turbine World - 2005 GTW Handbook” 
               
               
                 2. 1 × 1 configuration, 1 gas turbine × 1 steam turbine based on 501 G gas turbine. 
               
               
                 3. Supplemental duct firing operation in heat recovery unit 
               
               
                 4. Fuel gas cost $6.00/mmBTU (HHV) 
               
               
                 5. Turbine electrical output at generator terminals. 
               
               
                 6. Fissile fuel cost estimated at $2.00/mmBTU 
               
               
                 7. Auxiliary load includes cooling tower and transformer losses. 
               
             
          
         
       
     
     As shown, the Hybrid Integrated Nuclear Turbine system power plant possesses a major competitive advantage with respect to fuel costs. This is offset somewhat by the higher capital cost (and corresponding yearly debt repayments) of the Hybrid Integrated Nuclear Turbine system. 
     Another comparison involves emissions which are summarized for the illustrative example of the present invention relative to conventional power plants. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Power Plant Emissions Summary Comparison (Normalized 
               
               
                 to traditional pulverized coal plant) 
               
             
          
           
               
                   
                   
                   
                   
                 Hybrid 
               
               
                   
                 Traditional 
                   
                 Gas 
                 Integrated 
               
               
                 Typical 
                 Pulverized 
                 Advanced 
                 Combined 
                 Nuclear 
               
               
                 Emissions 1   
                 Coal 2   
                 Coal 3   
                 Cycle 4   
                 Turbine 5   
               
               
                   
               
               
                 Nitrogen Oxides 
                 100% 
                 ~49% 
                 ~6% 
                 ~4% 
               
               
                 Sulfur Oxides 
                 100% 
                 ~14% 
                 ~0.1%   
                 ~0.06%   
               
               
                 Carbon 
                 100% 
                 ~18% 
                 ~1.5%   
                 ~0.9%   
               
               
                 Monoxide 6   
               
               
                 Carbon 
                 100% 
                 ~70% 
                 ~36%  
                 ~21%  
               
               
                 Dioxide 6   
               
               
                 Particulates 
                 100% 
                 ~21% 
                 ~5% 
                 ~3% 
               
               
                 Mercury 7   
                 100% 
                 ~20% 
                 ~0.14%   
                 ~0.07%   
               
               
                   
               
               
                   1 Emission values for conventional technologies obtained from various industry sources. Levels are compared on a pounds per mmBTU basis, converted to tons per year for a normalized 750 mW(e) power plant. 
               
               
                   2 Clean Air Act of 1970, as implemented for facilities constructed after 1978 per Part 40 Code of Federal Regulations 
               
               
                   3 Typical values for Circulating Fluid Bed boilers or similar advanced coal fired facility. 
               
               
                   4 Emission levels for typical facilities licensed in the year 2000. 
               
               
                   5 Excludes any gas cleaning action associated with the Water Recovery Unit VII. 
               
               
                   6 Emission limits not currently specifically regulated by Federal regulations for traditional coal power plants. 
               
               
                   7 Levels not currently specifically regulated for traditional coal power plants. 
               
             
          
         
       
     
     As can be observed, the Hybrid Integrated Nuclear Turbine provides for significantly lower emissions relative to traditional and advance coal technologies. 
     Another comparison involves water make-up requirements. A measure of the water consumption can be inferred from the energy that must be dissipated to the heat sink, with a summary comparison provided below for the illustrative example of the preferred embodiment relative to conventional power plants. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Power Plant Heat Sink Summary Comparison (Normalized 
               
               
                 to traditional nuclear power station) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Conventional Nuclear 
                 100% 
               
               
                   
                 Pulverized Coal 
                 ~85% 
               
               
                   
                 Combined Cycle 
                 ~35% 
               
               
                   
                 Hybrid Integrated Nuclear Turbine 
                 ~25% 
               
               
                   
                   
               
             
          
         
       
     
     As shown, the Hybrid Integrated Nuclear Turbine power plant cooling and make-up water needs are small relative to more conventional technologies. 
     A further adaptation of the present invention lies with the use of coal gasification technology. In summary, a production facility may include a Coal Gasification Plant to supply fuel gas to the Hybrid Integrated Nuclear Turbine plant, with the later providing power as well as steam and compressed air to the gasification process. The gasification plant provides energy to the Hybrid Integrated Nuclear Turbine plant. The overall facility, designated the Nuclear Integrated Gasification Hybrid Turbine plant, employs relatively inexpensive nuclear fuel and coal while retaining the exceptionally low emissions of the hybrid integrated nuclear turbine process. 
       FIGS. 1F and 4A  depict the overall process diagram for the Nuclear Integrated Gasification Hybrid Turbine plant. As illustrated by  FIGS. 4A , the coal gasification plant includes an Air Separation Plant IX to provide oxygen and a Coal Gasification Plant VIII of a stationary/moving bed design. These types of gasification units require low quantities of steam and oxygen relative to other types of gasification designs. Coal is transported by a conveyor  90 - 3  into a coal gasification vessel  90 - 1  into which steam routed from the Heat Recovery Unit IV (or Steam Turbine V by way of extraction) by ducting  403   a . Compressed air is routed by ducting  106   a  from compressor  12  to an Air separation Plant IX consisting of Air Separation Unit  91  cryogenic equipment that separates oxygen from nitrogen. Oxygen created by the air separation unit  91  is directed through ducting  106   b  to compressor  92  and then directed by ducting  106   c  to gasifier  90 - 1 . Hot raw fuel gas is produced within gasifier  90 - 1  and then directed by ducting  700   a ,  700   b  and  700   c  through heat exchangers  38 ,  39  and  42 E to the Gas Cleanup Systems  93  where contaminants are removed in order to create fuel gas of suitable quality for use by gas turbine  17 . The fuel gas is directed to gas turbine  17  through ducting  700 . 
     Feed water from Heat Recovery Unit IV is routed by ducting  402   a  to heat exchanger  42 E and then directed back to Heat Recovery Unit IV by ducting  402   b . Fluid used by saturator  35  is routed from Heat Recovery Unit III by ducting  309   a  and  312   a  to heat exchangers  38  and  39 . The fluid is routed by ducting  309   b  and  312   b  to the saturator vessel  35 . Slag is removed from the coal gasification vessel  90 - 1  by conveyor  90 - 2 . 
     The energy removed from the raw, hot fuel gas by heat exchanger  42 E helps create the additional steam needed by the gasifier  90 - 1 . The additional steam also generates more electrical power from generator  51 . The energy removed from the hot raw fuel gas by heat exchangers  38  and  39  also helps create additional mass flow through turbine  17  by evaporating, in saturator  35 , more water into the open system working fluid. The additional mass flow through the turbine  17  generates more electrical output by generator  50 , in turn, helping provide for the additional auxiliary power required by the Air separation Plant IX and Coal gasification Plant VII. Owing to the noteworthy presence of steam in the open cycle working fluid, gas turbine emissions may be exceptionally low without the need for complicated dry-low NOx combustors typically employed with advanced gas turbines. The nitrogen by-product of the Air Separation Plant IX may be used for assisting gas turbine cooling or as a diluent for NOx emissions control, as is the case in integrated coal gasification combined cycle plants currently being developed. 
     The integration of a coal gasification process and the Hybrid Integrated Nuclear Turbine may lead to dramatic reductions in fuel cost as a result of the relative low cost of coal and nuclear fuel. On a comparative basis, typical fuel cost characteristics are summarized below. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Fuel Characteristics - Integrated Coal Gasification 
               
             
          
           
               
                   
                 Fuel 
                 Typical Characteristics 
               
               
                   
                   
               
               
                   
                 Coal 
                 $30.00 per ton, 
               
               
                   
                   
                 10,000 BTU/lbm (LHV) 
               
               
                   
                   
                 or ~$1.50 per mmBTU 
               
               
                   
                 Fissile Fuel 
                 $2.00 per mmBTU 
               
               
                   
                 Fuel Gas 
                 6.00 per mmBTU 
               
               
                   
                   
               
             
          
         
       
     
     Using the above averages and the inherent capabilities of the Hybrid Integrated Nuclear Turbine, the Nuclear Integrated Gasification Hybrid Turbine production facility may be capable of achieving variable fuel costs in the vicinity of 10 $/mWh, based on a cycle efficiency exceeding 55 percent. Provided below is a further comparative summary 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Coal Gasification Comparisons 1   
               
             
          
           
               
                   
                   
                 Integrated 
                 Nuclear 
                   
               
               
                   
                 Advanced 
                 Gasification 
                 Integrated 
                 Hybrid 
               
               
                   
                 Supercritical 
                 Combined 
                 Gasification 
                 Integrated 
               
               
                   
                 Pulverized 
                 Cycle 
                 Hybrid 
                 Nuclear 
               
               
                   
                 Coal 
                 (IGCC) 2   
                 Turbine 
                 Turbine 3   
               
               
                   
                   
               
             
          
           
               
                 Net output, 
                 750 
                 750 
                 750 
                 750 
               
               
                 mW 
               
               
                 Heat rate, 
                 8650 
                 7900 
                 5600 
                 5350 
               
               
                 BTU/kWh 
               
               
                 Efficiency, % 
                 43% 
                 45% 
                 +55% 
                 63% 
               
               
                 Generation, 
                 6.4 
                 6.4 
                 6.3 
                 6.4 
               
               
                 mW × 10{circumflex over ( )}6 
               
               
                 Variable 
                 14 
                 14 
                 10 
                 27 
               
               
                 Fuel Cost, 
               
               
                 $/mWh 
               
               
                   
               
             
          
         
       
         
         
           
             1. Advance coal and IGCC comparative values based on typical industry data. HINT and NIGHT values calculated. 
             2. IGCC unit includes 2 gas turbines and 1 steam turbine. 
             3. HINT natural gas fired, provided for comparative purposes. 
           
         
       
    
     While the variable fuel costs for the coal fueled facilities are impressive, the net cost of electricity would be much higher owing to the significant capital investment required for all of the above coal facilities. However, emission levels from the gas turbine based technologies would all be much lower than those of pulverized coal facilities. In particular, the CO2 emissions from the present invention&#39;s coal gasification configuration may be approximately 45 percent of those of comparable IGCC plants and about 45 percent of those from comparable conventional pulverized coal power plants. The IGCC emissions are about 70 percent of those from conventional coal plants. 
     As depicted by  1 F and  FIG. 4   b , an advanced adaptation of the present invention involves co-production of hydrogen and electricity from a coal gasification facility.  FIG. 4   b  provides a simplified illustration of an advanced Nuclear Integrated Gasification Hybrid Turbine where the air Separation Plant IX is replaced by an Electrolysis Plant X. Oxygen and hydrogen are produced by electrolytic cells  97  and stored in vessels  97 A and  97 B, with the oxygen being used with the coal gasification process. The auxiliary load to produce sufficient quantities of oxygen may be high (over half the output of the facility when using conventional electrolytic cells). However, with the advent of more advance electrolytic production methods (for instance, high temperature processes using reactor  1 ), the resulting advanced Nuclear Integrated Gasification Hybrid Turbine plant may become a major source for hydrogen and power. 
     Operationally the hybrid integrated nuclear turbine system behaves quite differently from a conventional combined cycle power plant. Because the gas turbine of a combined cycle plant is connected to a constant speed generator, reducing power levels requires choking back air flow using dampers and/or reducing firing temperatures, both of which degrade efficiency. The hybrid integrated nuclear turbine power plant relies on changing the speed of the nuclear turbine to alter the speed of the air compressors, thus reducing the mass flow of the air stream to the gas turbine. This is accomplished using an accumulator to withdraw helium from the reactor plant. Because temperatures remain relatively constant, efficiency impacts are minimized. Power can also be reduced by altering the flow of hot water to the saturator. Since power output is proportional to the cube of the speed or flow, maneuvering capabilities should be advanced. 
     The output and efficiency of a conventional gas turbine both degrade as ambient temperatures rise because less air flows through the engine; the air becomes less dense. However, the HINT power plant compensates for this effect through the use of the Vapor Addition Unit. As ambient temperatures rise, the water pumped into the saturator becomes hotter, thereby increasing the mass of the water vapor added to the compressed air. 
     Start-up of a combined cycle plant involves spinning up the gas turbine (e.g., using the generator as a motor) and igniting the fuel air mixture at the appropriate speed, with further speed increases occurring by increasing air flow and firing temperatures until the 3600 rpm synchronous speed of the generator is reached. This can occur quite rapidly (half hour or so). Steam turbine operations occur as the HRSG creates sufficient steam to allow for gradual heating the turbine by increasing steam flow. These operations can take several hours from cold conditions. 
     In the case of start-up of the HINT plant, a clutch is engaged to allow the main generator to bring the nuclear turbine and compressors up to operational speeds, with the reactor&#39;s control rods moved outward so nuclear energy can heat-up the helium gas. Pressurized air is simply vented from the Compressor Plant until stable reactor conditions are reached. At this point, the start-up is similar to that of a NGCC, although operation of the steam turbine can occur rapidly owing to the small size of the unit. 
     Shutdown of a NGCC plant can occur quickly, although the process typically occurs in a controlled manner to avoid undue stress on the power plant. In the case of the HINT, the gas turbine load can be similarly reduced, although the reactor would normally be shutdown in a steady controlled fashion using the main generator as a motor. During this period, the compressor plant would discharge air to the atmosphere and gas turbine as the nuclear turbine spins down. 
     Conventional pressurized water nuclear reactors contain a number of defense-in-depth features to provide a high level of safety. However, owing to the large size (3800 mW thermal and 1300 mW electrical output) of these power stations, operator intervention as well electrical power for active operation of cooling pumps and fans is required to insure that the reactor core does not overheat. Additionally, massive steel and concrete structures are required to contain the energy and radioactive materials that could escape from the reactor in the event of a major accident. The net effect is a very high capital cost for these facilities—several billions of dollars. By contrast, the capital cost of combined cycle plants is in the hundreds of millions of dollars range. 
     The unique features of a HINT power plant allow the technology to provide an exceptionally high level of safety at capital costs more consistent with those of NGCC plants. The most significant safety feature is that virtually no actions are necessary to prevent the reactor core from melting. The small size of the reactor coupled with the inherent characteristics of the reactor core allows heat to be conducted into surrounding structures. 
     A key safety feature of the core is the use of refractory coated fuel particles composed of pyrolytic carbon, silicon carbide and uranium oxycarbide. This material has been extensively tested and possesses exceptional resistant to high temperatures. The core has a tremendous heat capacity that allows energy to be dissipated into surrounding structures over time without melting the fuel. In addition, the core has a negative coefficient of reactivity which means that reactor will shut down if temperatures become too high. The Chernoble accident demonstrates the consequences of a positive coefficient of reactivity. 
     While the HINT technology can ultimately rely on completely passive systems for protection, economic considerations suggest a more active approach. To that end, several different measures provide for routine and emergency removal of reactor decay heat:
         Generator/motor. If off-site power is available, the main generator can be used as a motor and the main clutch engaged to rotate the compressors and turbines, with reactor decay heat removed through the inter-coolers to the heat sink or alternatively through the saturators to the atmosphere.   Diesel/generator. If no off-site electrical power is available, the diesel motor/generator can be engaged through a clutch (and reduction gear) to rotate the compressors and turbines as well as supply emergency electrical power. Reactor decay heat would be removed through the intercoolers or saturators.   Reactor Cavity Cooling A passive system, similar to that planned for the GT-MHR would be employed to remove reactor decay heat by conduction using the natural circulation of air through the cavity surrounding the reactor vessel. Although a passive system, dampers must be opened to activate the system.       

     Additional protective measures include:
         Locating the reactor complex underground.   Providing a concrete and steel structure around the reactor plant.   Providing a concrete protective structure around the turbine and compressor plants.   Providing multiple sources of electrical power.       

     These features are aimed primarily at protecting the investment from natural and man-made disasters. 
     A major challenge to a gas cooled reactor can involve the loss of the generator&#39;s electrical load. Severe thermal stresses can occur while dissipating the large quantities of reactor heat that is present. However, the reactor of a HINT technology plant could reduce power in a controlled fashion, with the Compressor Plant simply discharging air to the atmosphere. 
     Environmental Characteristics 
     The HINT technology possesses a number of desirable traits from an air pollution standpoint, in part because approximately 35% of the energy produced is virtually emissions flee. A relative comparison between comparable HINT and NGCC power plants is provided below. 
     HINT and NIGHT technology emissions are small fractions of the air pollution emitted by a comparable coal fired power plant. Nitrogen oxide emissions are expected to be in the single digit range (on a parts-per-million basis), as has been observed with advanced turbine cycles that combust large quantities of steam with the fuel gas and air. When coupled with conventional catalysts used for additional NOx and CO reduction, the HINT technology should achieve low NO x  emissions. 
     The estimated HINT emission levels include no credit for the scrubbing action that will occur in the Water Recovery Unit. Particulates, CO 2 , SO 2  will all be removed from the exhaust gas to varying degrees. As such, the condensate would normally be expected to be quite acidic. However, ammonia (which is used with NOx catalysts) can neutralize the solution, as has been observed in the field. 
     Recovered water will require treatment, including possibly reverse osmosis and demineralization to remove potential gas turbine contaminants. In addition, cooling tower blow-down water will contain impurities. However, the net level of water borne impurities associated with a HINT will be less than comparable NGCC, coal fired and nuclear power plants. This occurs because the overall thermal pollution levels (a measure of water use) are much smaller. 
     It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto, except in so far as such limitations are included in the following claims and allowable equivalents thereof.

Technology Classification (CPC): 8