3B2 E2.5 C7 Review
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Questions and Answers

What is another common term used to describe cogeneration?

  • Heat generation
  • Simultaneous energy production
  • Combined heat and power (correct)
  • Electric power generation

    • Which of the following is not a potential initial energy source for cogeneration?

  • Natural gas
  • Biomass
  • Hydropower (correct)
  • Coal

    • What is the primary purpose of cogeneration?

  • To reduce overall thermal efficiency
  • To reduce energy costs by increasing thermal efficiency (correct)
  • To produce electrical power only
  • To increase energy costs

    • Which component drives the electrical generator in most modern cogeneration installations?

    <p>Internal combustion engine</p> Signup and view all the answers

    What is the by-product of combustion that is utilized as heat energy in cogeneration?

    <p>Heat energy</p> Signup and view all the answers

    How does cogeneration help in utilizing exhaust heat in the process?

    <p>By using it to produce steam or hot water</p> Signup and view all the answers

    Which of the following benefits does cogeneration offer compared to conventional plants?

    <p>Reduced load demand on cleaner facilities</p> Signup and view all the answers

    What is the primary advantage of cogeneration at a local level?

    <p>Reduction in total energy bill</p> Signup and view all the answers

    Which industries can benefit from high-temperature energy recovery units in cogeneration systems?

    <p>Pulp and paper mills</p> Signup and view all the answers

    How does cogeneration impact global energy reserves and greenhouse gas emissions?

    <p>Preservation of energy reserves and reduction in greenhouse gas emissions</p> Signup and view all the answers

    Which type of facility generally has shorter start-up times than a conventional plant of similar capacity?

    <p>A cogeneration facility</p> Signup and view all the answers

    What is a disadvantage of remote utility plants compared to local cogeneration facilities?

    <p>Decreased investment in new transmission lines</p> Signup and view all the answers

    What is one of the key advantages that cogeneration offers at the local level?

    <p>Shorter start-up time than conventional plants</p> Signup and view all the answers

    How do local cogeneration facilities contribute to reducing greenhouse gas emissions?

    <p>By using cleaner burning fuels</p> Signup and view all the answers

    What feature of cogeneration facilities helps in the preservation of energy reserves?

    <p>High energy efficiency</p> Signup and view all the answers

    Which sector typically has heating needs that can be satisfied by low temperature heat recovery units in cogeneration systems?

    <p>Institutional or commercial establishments</p> Signup and view all the answers

    Why do cogeneration facilities result in a reduction in transmission line losses?

    <p>Produce electricity on site</p> Signup and view all the answers

    What is a significant difference between cogeneration facilities and conventional plants in terms of start-up time?

    <p>Conventional plants have a much shorter start-up time</p> Signup and view all the answers

    What is the role of a heat recovery boiler in a cogeneration system?

    <p>To utilize the exhaust heat to produce steam or hot water</p> Signup and view all the answers

    Which of the following is the primary purpose of cogeneration, considering its overall effects on the global energy landscape?

    <p>To reduce the overall operational costs of power generation</p> Signup and view all the answers

    Which of the following does not represent a common misconception about cogeneration?

    <p>It increases the overall thermal efficiency of a system</p> Signup and view all the answers

    How does cogeneration address the issue of energy waste in traditional power generation systems?

    <p>By recycling the exhaust heat for industrial processes</p> Signup and view all the answers

    What role does the operation of a steam turbine play in cogeneration, compared to how it is used in traditional power generation plants?

    <p>It is driven by the heat engine to produce steam</p> Signup and view all the answers

    What is the significance of the mutual exclusivity of the energy outputs in cogeneration (heat energy and electrical energy)?

    <p>It allows for the independent optimization of both outputs</p> Signup and view all the answers

    Which of the following is NOT a potential fuel source for cogeneration systems?

    <p>Solar energy</p> Signup and view all the answers

    What is the purpose of the absorption refrigeration system in the gas turbine cogeneration system?

    <p>To provide cooling</p> Signup and view all the answers

    Which of the following is NOT a benefit of cogeneration systems?

    <p>Increasing energy waste</p> Signup and view all the answers

    Which of the following is NOT a use of the heat produced by the gas turbine in the cogeneration system?

    <p>Driving the electrical generator</p> Signup and view all the answers

    What is the main advantage of using a circulating fluid in the heat recovery water heater?

    <p>Efficient heat transfer</p> Signup and view all the answers

    Which of the following is NOT a potential use for cogeneration systems?

    <p>Powering a residential home</p> Signup and view all the answers

    Which type of simple-cycle cogeneration system is illustrated in Figure 1?

    <p>Back-Pressure Steam Turbine</p> Signup and view all the answers

    What is the primary purpose of the fuel in a back-pressure steam turbine cogeneration system?

    <p>To produce heat and steam for the turbine</p> Signup and view all the answers

    What is a common energy source used in the boiler of a back-pressure steam turbine cogeneration system?

    <p>Fossil fuels</p> Signup and view all the answers

    What component does the LP exhaust steam from the turbine supply mechanical energy to in a back-pressure steam turbine cogeneration system?

    <p>The electrical generator</p> Signup and view all the answers

    Which type of cogeneration system is depicted in Figure 2?

    <p>Waste Heat Cogeneration</p> Signup and view all the answers

    What is the primary purpose of the waste heat from the process in a waste heat cogeneration system?

    <p>To produce steam in the boiler</p> Signup and view all the answers

    What is the primary function of the heat recovery water heater in an internal combustion engine cogeneration system?

    <p>To transfer heat to a circulating fluid for building or process heat</p> Signup and view all the answers

    In a gas turbine cogeneration system, what is the primary purpose of the steam produced by the exhaust heat boiler?

    <p>To power an absorption refrigeration system</p> Signup and view all the answers

    Which fuel source is NOT mentioned as an option for powering an internal combustion engine cogeneration system?

    <p>Wind power</p> Signup and view all the answers

    What is the primary advantage of using a heat engine cogeneration system over traditional power generation systems?

    <p>Utilization of waste heat</p> Signup and view all the answers

    In an internal combustion engine cogeneration system, what is the primary purpose of the generator?

    <p>To generate electricity</p> Signup and view all the answers

    What is the primary advantage of using a gas turbine cogeneration system over an internal combustion engine cogeneration system?

    <p>None of the above</p> Signup and view all the answers

    Which type of simple-cycle cogeneration system would be most suitable for a small-scale industrial process with minimal heat requirements?

    <p>Internal combustion engine cogeneration</p> Signup and view all the answers

    Which type of simple-cycle cogeneration system would be most appropriate for a large-scale industrial process with high heat demands at various pressure levels?

    <p>Back pressure steam turbine cogeneration</p> Signup and view all the answers

    Which simple-cycle cogeneration system would be most suitable for a biomass-powered municipal waste incinerator with low electrical power needs?

    <p>Waste heat cogeneration</p> Signup and view all the answers

    Considering the overall environmental impact, which simple-cycle cogeneration system has the potential to minimize greenhouse gas emissions, while meeting the energy demands of an industrial process?

    <p>Internal combustion engine cogeneration with biogas fuel</p> Signup and view all the answers

    Which simple-cycle cogeneration system typically provides the highest electrical efficiency for a given chemical industrial process requiring steam at a specified pressure?

    <p>Back pressure steam turbine cogeneration</p> Signup and view all the answers

    Which simple-cycle cogeneration system would be most appropriate for an industrial process utilizing a waste product as its primary fuel source?

    <p>Back pressure steam turbine cogeneration</p> Signup and view all the answers

    What is the primary purpose of the exhaust from the gas turbine in the combined-cycle cogeneration system?

    <p>To heat the boiler and produce steam for the steam turbine</p> Signup and view all the answers

    What is the thermodynamic cycle used by the steam system in the combined-cycle cogeneration system?

    <p>Rankine Cycle</p> Signup and view all the answers

    What is the role of the boiler in the combined-cycle cogeneration system?

    <p>To produce steam for the steam turbine</p> Signup and view all the answers

    Which component does not require fans in the combined-cycle cogeneration system?

    <p>The boiler</p> Signup and view all the answers

    What is the primary advantage of using a combined-cycle cogeneration system over traditional power generation systems?

    <p>It utilizes waste heat to produce electricity</p> Signup and view all the answers

    What is the significance of the mutual exclusivity of the energy outputs in the combined-cycle cogeneration system?

    <p>They ensure the efficient use of energy resources</p> Signup and view all the answers

    What is the purpose of the economizer in a combined-cycle steam/gas turbine cogeneration system?

    <p>To heat the incoming feedwater</p> Signup and view all the answers

    What is the primary role of the steam turbine in a combined-cycle steam/gas turbine cogeneration system?

    <p>To drive an electrical generator</p> Signup and view all the answers

    What is the purpose of the heat recovery steam generator (HRSG) in a combined-cycle steam/gas turbine cogeneration system?

    <p>To generate superheated steam from feedwater</p> Signup and view all the answers

    In a combined-cycle steam/gas turbine cogeneration system, what is the primary purpose of the gas turbine?

    <p>To drive an electrical generator</p> Signup and view all the answers

    What is the benefit of combining the Brayton and Rankine cycles in a combined-cycle steam/gas turbine cogeneration system?

    <p>Production of heat and electrical power</p> Signup and view all the answers

    What is the purpose of the heat recovery steam generator (HRSG) in the combined-cycle steam/gas turbine cogeneration system, specifically in relation to the superheated steam produced?

    <p>To generate superheated steam from feedwater using the exhaust gases from the gas turbine</p> Signup and view all the answers

    In the combined-cycle steam/gas turbine cogeneration system, what is the role of the boiler in relation to the fuel used and blade fouling prevention?

    <p>To utilize the products of combustion as fuel for the gas turbine and avoid blade fouling</p> Signup and view all the answers

    What is the significance of the mutual exclusivity of the energy outputs (heat energy and electrical energy) in the combined-cycle cogeneration system, specifically in terms of thermodynamic efficiency?

    <p>The mutual exclusivity allows for the recycling of waste heat energy for secondary purposes</p> Signup and view all the answers

    In the context of the combined-cycle system depicted in Figure 6, what is the primary role of the exhaust gases from the gas turbine in relation to the incoming feedwater and heat recovery?

    <p>To heat the incoming feedwater in the economizer and recover waste heat</p> Signup and view all the answers

    What is the thermodynamic cycle used by the steam system in the combined-cycle steam/gas turbine cogeneration system, and how does it differ from the Brayton and Rankine cycles?

    <p>The Rankine cycle is used for the steam system, while the Brayton cycle is used for the gas turbine</p> Signup and view all the answers

    What is the primary purpose of the compressor in the combined cycle configuration shown in Figure 6?

    <p>To supply pressurized combustion air to the boiler</p> Signup and view all the answers

    What is the thermodynamic cycle utilized by the gas turbine in the combined-cycle cogeneration system?

    <p>Brayton Cycle</p> Signup and view all the answers

    What is the purpose of bleeding off steam from sections of the steam turbine in the combined-cycle cogeneration system?

    <p>To act as a heat source in the feed heater</p> Signup and view all the answers

    In the combined-cycle cogeneration system, what is the purpose of the boiler fuel combustion?

    <p>To produce steam for the steam turbine</p> Signup and view all the answers

    What is the primary advantage of the combined-cycle cogeneration system compared to traditional power generation systems?

    <p>It has a higher efficiency</p> Signup and view all the answers

    Why are forced draft (FD) and induced draft (ID) fans not required in the combined-cycle cogeneration system?

    <p>Because the boiler is pressurized by the gas turbine exhaust</p> Signup and view all the answers

    What component is used to preheat the feedwater in a fully-fired combined-cycle cogeneration system?

    <p>Gas turbine exhaust gas stream</p> Signup and view all the answers

    Which system allows the boiler to be fired separately at reduced load if the gas turbine is unavailable for service?

    <p>Fully fired steam generator</p> Signup and view all the answers

    What happens to the steam load when the gas turbine is in service in a fully-fired combined-cycle cogeneration system?

    <p>Increases considerably</p> Signup and view all the answers

    What is the primary role of the HRSG in a fully-fired combined-cycle cogeneration system?

    <p>To meet the required steam demand</p> Signup and view all the answers

    Which component receives all the exhaust flow from the gas turbine in a fully-fired combined-cycle cogeneration system?

    <p>Fully-fired steam generator (HRSG)</p> Signup and view all the answers

    What is one application of the fully-fired combined-cycle cogeneration system design?

    <p>Repowering of existing plants</p> Signup and view all the answers

    What is the effect on the steam load when the gas turbine is unavailable for service in a fully-fired combined-cycle cogeneration system with separate firing capability?

    <p>The steam load is reduced</p> Signup and view all the answers

    Which component of the fully-fired combined-cycle cogeneration system provides the initial heat input, excluding the primary fuel used in the gas turbine?

    <p>The heat recovery steam generator (HRSG)</p> Signup and view all the answers

    What is the main purpose of the auxiliary burners in the fully-fired heat recovery steam generator (HRSG) of a combined-cycle cogeneration system?

    <p>To meet the required steam demand</p> Signup and view all the answers

    In the context of cogeneration system applications, what is the purpose of repowering existing plants with the addition of a gas turbine?

    <p>To achieve additional output and efficiency</p> Signup and view all the answers

    Which component in the fully-fired combined-cycle cogeneration system provides heat for the boiler while also allowing separate firing at reduced load?

    <p>The gas turbine exhaust gas stream</p> Signup and view all the answers

    Which of the following statements is true about the operation of the hot products of combustion in a fully-fired combined-cycle cogeneration system?

    <p>They provide heat to the boiler, but do not contribute to the auxiliary burners</p> Signup and view all the answers

    What is one of the main disadvantages of placing the generator between the gas turbine and the steam turbine in a single shaft combined-cycle power plant?

    <p>The need to remove the steam turbine for major maintenance on the generator</p> Signup and view all the answers

    What is a benefit of the single shaft design in combined-cycle plants compared to multi-shaft combined cycle plants?

    <p>Faster start-up times</p> Signup and view all the answers

    Which of the following is not a common configuration in a single-shaft combined-cycle power plant?

    <p>Parallel arrangement of the compressor, gas turbine, and generator</p> Signup and view all the answers

    What is a potential issue in a single shaft configuration with the generator located between the gas turbine and the steam turbine?

    <p>The need to remove the steam turbine for major maintenance on the generator</p> Signup and view all the answers

    Which of the following is not a benefit of the single shaft design compared to multi-shaft combined cycle plants?

    <p>Lower thermal efficiency</p> Signup and view all the answers

    Why is the single shaft design of combined cycle plants considered to have the most attractive operating and performance characteristics?

    <p>Higher level of thermal efficiency and operating flexibility</p> Signup and view all the answers

    What is the advantage of the configuration shown in Figure 11?

    <p>The rotor can be removed from the generator without having to remove part of the turbine.</p> Signup and view all the answers

    What is a characteristic of a multi-shaft combined-cycle power plant?

    <p>It has multiple gas turbines or steam turbines on separate shafts.</p> Signup and view all the answers

    Why is the multi-shaft configuration popular when existing plants add cogeneration to their system?

    <p>The gas turbine(s) and heat recovery generator(s) are easily added to supplement the existing steam supply plus increase the power generation capacity of the plant.</p> Signup and view all the answers

    What is the advantage of the multi-shaft configuration in terms of maintenance?

    <p>It allows for more flexibility and convenience for maintenance on the gas turbine or the steam turbine sections.</p> Signup and view all the answers

    What is the purpose of the heat-recovery steam generators in a multi-shaft combined-cycle power plant?

    <p>To produce superheated steam for the turbines.</p> Signup and view all the answers

    What is a characteristic of a single-shaft combined-cycle power plant?

    <p>It has a single shaft connecting the gas turbine to the steam turbine and then to the generator.</p> Signup and view all the answers

    What is the primary disadvantage of the single shaft configuration where the generator is located between the gas turbine and the steam turbine?

    <p>Necessity to remove the steam turbine for generator maintenance</p> Signup and view all the answers

    What is the significant benefit of the single shaft design that is not shared by multi-shaft combined cycle plants?

    <p>Improved ability to supply mechanical energy to several processes</p> Signup and view all the answers

    What component in the fully-fired combined-cycle cogeneration system provides heat for the boiler while also allowing separate firing at reduced load?

    <p>Gas Turbine</p> Signup and view all the answers

    What is the purpose of a heat-recovery steam generator in a multi-shaft combined-cycle power plant?

    <p>To recover heat from the gas turbine exhaust and generate steam</p> Signup and view all the answers

    Which of the following is NOT a benefit of the single shaft design compared to multi-shaft combined cycle plants?

    <p>Improved ability to operate parallel to grid</p> Signup and view all the answers

    Which type of fuel source is NOT mentioned as an option for powering an internal combustion engine cogeneration system?

    <p>Coal</p> Signup and view all the answers

    In a multi-shaft combined-cycle power plant, what is one of the main advantages of having separate generators driven by each turbine?

    <p>The generators can be independently controlled to match varying power and steam loads, increasing plant efficiency.</p> Signup and view all the answers

    Which of the following configurations best preserves the mutual exclusivity of energy outputs in a combined-cycle cogeneration system?

    <p>Decoupling the electrical and thermal energy outputs through separate pipes and electrical connections.</p> Signup and view all the answers

    Why is the multiple-shaft configuration commonly used when integrating cogeneration into existing plants?

    <p>The multi-shaft design allows for greater flexibility in integrating new equipment without disrupting existing infrastructure.</p> Signup and view all the answers

    What is a unique advantage of the configuration shown in Figure 11, where the steam turbine is positioned between the gas turbine and the generator?

    <p>The ability to remove the rotor from the generator without disturbing the turbine components.</p> Signup and view all the answers

    In the fully-fired combined-cycle cogeneration system, which component not only provides heat for the boiler but also allows separate firing during reduced load conditions?

    <p>The heat-recovery steam generator (HRSG).</p> Signup and view all the answers

    What is a distinct advantage of using a gas turbine cogeneration system, especially when compared to an internal combustion engine cogeneration system?

    <p>More efficient exhaust heat utilization through the use of heat-recovery steam generators.</p> Signup and view all the answers

    What does a base loaded system do in a cogeneration system connected to the electrical grid?

    <p>Allows for fixed electrical demand from the utility grid</p> Signup and view all the answers

    In thermal load control, what is the primary difference between fixed production and varying requirement strategies?

    <p>Minimum thermal energy needed</p> Signup and view all the answers

    During low thermal requirements in a cogeneration system, what action does the diverter valve take in the control system utilizing a duct burner?

    <p>Vents exhaust gases to the atmosphere</p> Signup and view all the answers

    What is the purpose of the prime mover in a cogeneration system with fixed thermal energy production?

    <p>Supply thermal energy to the process</p> Signup and view all the answers

    What role does the duct burner play if the diverter completely closes off exhaust gases to the atmosphere in a cogeneration system?

    <p>Activates to control further changes in thermal energy needs</p> Signup and view all the answers

    In a cogeneration system, how is the thermal load control strategy different from the diverter and duct burner control?

    <p>Operation at full load compared to modulating output</p> Signup and view all the answers

    Which type of cogeneration system primarily produces high temperature thermal energy and utilizes the heat exhausted from the process to produce electrical energy?

    <p>Bottoming cycle cogeneration</p> Signup and view all the answers

    In a cogeneration system that is not connected to the electrical grid, what happens to waste heat when the heating requirements of the process are less than the heat produced by the system?

    <p>It is lost to the atmosphere</p> Signup and view all the answers

    Which type of facility typically uses a topping cycle cogeneration system, where fuel is first used to produce electrical power with thermal energy as a byproduct?

    <p>Hospitals and universities</p> Signup and view all the answers

    Which component of a fully-fired combined-cycle cogeneration system receives all the exhaust flow from the gas turbine?

    <p>Heat recovery steam generator</p> Signup and view all the answers

    When the electrical production process produces waste heat, which other heating systems may be required if the waste heat produced is less than that required for the process?

    <p>Auxiliary firing or boilers</p> Signup and view all the answers

    What is the primary advantage of utilizing a single shaft configuration in combined cycle plants compared to multi-shaft designs?

    <p>Increased efficiency and simplicity</p> Signup and view all the answers

    What is the primary difference between topping cycle cogeneration and bottoming cycle cogeneration systems?

    <p>The primary fuel in topping cycle systems produces electrical power first, while bottoming cycle systems produce high temperature thermal energy first.</p> Signup and view all the answers

    What is the purpose of being connected to the utility grid in a cogeneration system?

    <p>To supply only the electrical requirements of the site, including that required for emergency backup.</p> Signup and view all the answers

    What may be required if the waste heat produced is less than that required for the process in a cogeneration system?

    <p>Auxiliary firing</p> Signup and view all the answers

    What will happen if the heating requirements of a process are less than the heat produced in a cogeneration system?

    <p>Some waste heat will be lost to the atmosphere.</p> Signup and view all the answers

    In a cogeneration system, what is the primary function of a system that is not connected to the electrical grid?

    <p>To supply all electrical requirements of the site.</p> Signup and view all the answers

    What would be a potential solution if the heat produced by a cogeneration system is less than that required for the process?

    <p>Using auxiliary boilers or firing.</p> Signup and view all the answers

    What is the primary role of a diverter valve in a cogeneration system with a duct burner and HRSG during low thermal requirements?

    <p>To close off the exhaust gases to the HRSG and vent them to the atmosphere</p> Signup and view all the answers

    How does a base loaded system operate in a cogeneration system connected to the electrical grid when changes in electrical requirements need to be met?

    <p>By purchasing or selling power to the electrical utility grid</p> Signup and view all the answers

    What is the purpose of the duct burner (auxiliary firing) in a cogeneration system with a diverter valve and HRSG?

    <p>To fire and modulate to control changes in thermal energy requirements when the diverter is completely closed</p> Signup and view all the answers

    What happens to the exhaust gases when the diverter valve is positioned to close off the HRSG in a cogeneration system with a duct burner and HRSG during low thermal requirements?

    <p>The exhaust gases are vented to the atmosphere</p> Signup and view all the answers

    In thermal load control, what is the primary difference between the fixed production and varying requirement strategies concerning the prime mover's operation?

    <p>In fixed production, the prime mover operates at full load all the time, while varying requirement strategy involves the prime mover with varying output</p> Signup and view all the answers

    What is the primary function of exhaust heat boiler in a gas turbine cogeneration system?

    <p>To convert the exhaust gases from the gas turbine into steam for further turbine expansion or process heating</p> Signup and view all the answers

    What is the primary function of the economizer section in the HRSG?

    <p>To preheat the boiler feedwater before it enters the evaporator tubes.</p> Signup and view all the answers

    In the vertical HRSG, what creates the natural circulation of water and steam?

    <p>The header and downcomers</p> Signup and view all the answers

    What is the purpose of the steam drum in the HRSG?

    <p>To separate steam from water</p> Signup and view all the answers

    What type of boiler is described in the text?

    <p>Water tube boiler</p> Signup and view all the answers

    What is the function of the superheater section in the HRSG?

    <p>To superheat the steam before it is sent to the turbine</p> Signup and view all the answers

    What is the main advantage of using a cogeneration system?

    <p>Improved thermal efficiency</p> Signup and view all the answers

    What is the primary heat source for steam generation in a Heat Recovery Steam Generator (HRSG)?

    <p>Gas turbine exhaust</p> Signup and view all the answers

    What is the advantage of the flexibility of HRSG design?

    <p>Meeting specific requirements of each plant site</p> Signup and view all the answers

    What is the purpose of duct burners in HRSG?

    <p>To increase the production of steam</p> Signup and view all the answers

    What type of circulation is most commonly used in horizontal gas flow HRSG boilers?

    <p>Natural circulation</p> Signup and view all the answers

    What is a characteristic of some HRSG boilers?

    <p>High alloy tubes</p> Signup and view all the answers

    What determines the specific design of an HRSG?

    <p>All of the above</p> Signup and view all the answers

    What is the main application of heat recovery steam generators (HRSG)?

    <p>Generating electricity via gas turbine exhaust</p> Signup and view all the answers

    In HRSG design, what factor determines whether the gas flow is horizontal or vertical?

    <p>Electrical requirements of the plant</p> Signup and view all the answers

    What circulation type is most commonly used in HRSG boilers with horizontal gas flow?

    <p>Natural circulation</p> Signup and view all the answers

    What is the purpose of auxiliary burners in HRSG units?

    <p>To increase the gas temperature at the HRSG inlet</p> Signup and view all the answers

    How do HRSG units designed for multiple pressure steam-water loops contribute to heat recovery?

    <p>By optimizing heat recovery based on application requirements</p> Signup and view all the answers

    In what scenario can HRSGs operate without water-flow through the tubes?

    <p>When high alloy tubes are in use</p> Signup and view all the answers

    What is the primary function of the first section of horizontal tubes in the HRSG?

    <p>Superheat the steam to high pressure</p> Signup and view all the answers

    What is the purpose of the lower header in the evaporator tubes section of the HRSG?

    <p>To supply water to the evaporator tubes and create natural circulation</p> Signup and view all the answers

    What is the pressure of the high-pressure steam drum in the large, horizontal, multi-drum HRSG shown in Figure 16?

    <p>7000 kPa</p> Signup and view all the answers

    What is the purpose of the economizer section in the HRSG?

    <p>To preheat the feedwater going to the steam drum</p> Signup and view all the answers

    What is the arrangement of the ducts for gas turbine exhaust in the vertical HRSG shown in Figure 15?

    <p>Two ducts for gas turbine exhaust</p> Signup and view all the answers

    What is the direction of the gas flow in the horizontal HRSG shown in Figure 15?

    <p>Horizontal</p> Signup and view all the answers

    What is the primary purpose of selective catalytic reduction (SCR) in a HRSG?

    <p>To reduce nitrous oxides emissions</p> Signup and view all the answers

    At what temperature range is the optimal operation of selective catalytic reduction (SCR) in a HRSG?

    <p>Between 350°C and 450°C</p> Signup and view all the answers

    What is the effect of cogeneration on carbon dioxide emissions?

    <p>It reduces CO2 emissions by 35%</p> Signup and view all the answers

    Why are condensing heat exchangers not usually used with diesel fuel and biogas?

    <p>Because of the corrosive nature of the condensate</p> Signup and view all the answers

    What is the primary concern in the combustion process?

    <p>Carbon dioxide emissions</p> Signup and view all the answers

    What is the effect of sulphur content in fuel on sulphur dioxide emissions?

    <p>It increases sulphur dioxide emissions directly</p> Signup and view all the answers

    Which of the following fuels, when used in a cogeneration system, does not produce nitrous oxides (NOX)?

    <p>None of the above</p> Signup and view all the answers

    In a cogeneration system, which of the following methods is effective for reducing the development of nitrous oxides (NOX)?

    <p>Injecting steam into the combustion region</p> Signup and view all the answers

    What happens to the efficiency of a cogeneration unit when steam is injected into the combustion region to reduce nitrous oxides?

    <p>Unit efficiency decreases</p> Signup and view all the answers

    Which primary mover in a cogeneration system contributes the most to reducing nitrous oxides (NOX)?

    <p>Gas turbine</p> Signup and view all the answers

    What is the main environmental concern associated with using natural gas in a cogeneration system?

    <p>Formation of nitrous oxides</p> Signup and view all the answers

    Which environmental agency typically regulates nitrous oxides (NOX) produced by cogeneration systems?

    <p>Local Environmental Agencies</p> Signup and view all the answers

    At what temperature range is the exhaust gases exiting the gas turbine before going through the selective catalytic reduction (SCR) process?

    <p>550°C</p> Signup and view all the answers

    In what range does the optimal temperature for selective catalytic reduction with SCR fall?

    <p>350°C - 450°C</p> Signup and view all the answers

    How much can the use of selective catalytic reduction with steam injection reduce nitrous oxides from 150 ppm?

    <p>To less than 10 ppm</p> Signup and view all the answers

    Which component allows the ammonia and catalyst to be installed at a precise location in the temperature profile of the exhaust gases in a HRSG?

    <p>Flexibility of the HRSG</p> Signup and view all the answers

    What by-product of the combustion process is particularly noted for its contribution to the greenhouse effect and climatic change?

    <p>Carbon Dioxide</p> Signup and view all the answers

    How much is the primary fuel consumption reduced by when cogeneration replaces separate fossil fuel generation of electricity and heat?

    <p>35%</p> Signup and view all the answers

    What is a key factor that determines the level of NOX emissions in a cogeneration system?

    <p>Combustion conditions</p> Signup and view all the answers

    What is a method to reduce NOX emissions in a gas turbine cogeneration system?

    <p>Injecting steam into the combustion region</p> Signup and view all the answers

    What is a potential drawback of reducing NOX emissions by injecting steam into the combustion region?

    <p>Reduced temperature of the exhaust gases</p> Signup and view all the answers

    What is the primary environmental concern associated with the combustion of natural gas in a cogeneration system?

    <p>Development of nitrous oxides</p> Signup and view all the answers

    What is the effect of burning a fuel in air on the environment?

    <p>Production of nitrous oxides</p> Signup and view all the answers

    Which of the following fuels has a significant impact on the environment due to the formation of sulphur dioxide?

    <p>Coal</p> Signup and view all the answers

    What type of fuel can an internal combustion engine burn in a cogeneration system?

    <p>Natural gas, propane, diesel fuel, or gasoline</p> Signup and view all the answers

    What is a key advantage of using an internal combustion engine in a cogeneration system?

    <p>Capable of intermittent operation and not affected by ambient temperature changes</p> Signup and view all the answers

    What is the purpose of the heat recovery water heater in an internal combustion engine cogeneration system?

    <p>To recover heat from the engine exhaust gases</p> Signup and view all the answers

    What type of system would be suitable for small businesses and institutions with high electrical energy demand?

    <p>Internal combustion engine cogeneration system</p> Signup and view all the answers

    What component is used to cool the process water in the internal combustion engine cogeneration system?

    <p>Water cooler</p> Signup and view all the answers

    What is the advantage of using an internal combustion engine cogeneration system over traditional power generation systems?

    <p>Ability to provide both electrical and thermal energy</p> Signup and view all the answers

    What is the primary advantage of an IC engine cogeneration system over a gas turbine cogeneration system in a small facility context?

    <p>Immune to ambient temperature changes</p> Signup and view all the answers

    In the context of heat recovery, which part of the IC engine cogeneration system allows for more efficient heat recovery compared to a gas turbine cogeneration system?

    <p>The HRWH</p> Signup and view all the answers

    Which type of fuel does not yield high sulfur dioxide emissions when used in an IC engine cogeneration system?

    <p>Natural gas</p> Signup and view all the answers

    What is the primary limitation of an IC engine cogeneration system for small businesses and institutions with high electrical energy demand?

    <p>Insufficient electrical energy output</p> Signup and view all the answers

    Which component in an IC engine cogeneration system is responsible for maintaining the engine's temperature and preventing overheating?

    <p>The water cooler</p> Signup and view all the answers

    What is a suitable fuel source for an IC engine cogeneration system that minimizes nitrous oxides (NOx) emissions?

    <p>Natural gas</p> Signup and view all the answers

    What is the primary purpose of the diverter valve during the start-up sequence of a cogeneration system?

    <p>To bypass the HRSG and send exhaust gases directly to the atmosphere</p> Signup and view all the answers

    What is the starting speed of the gas turbine during the start-up sequence of a cogeneration system?

    <p>55% of rated speed</p> Signup and view all the answers

    What is the primary function of the auxiliary burner in a cogeneration system?

    <p>To provide additional heat input when steam demand is high</p> Signup and view all the answers

    What happens to the generated steam during the start-up sequence of a cogeneration system?

    <p>It is used to heat the water in the HRSG</p> Signup and view all the answers

    What is the purpose of the clutch in the gearbox during the start-up sequence of a cogeneration system?

    <p>To keep the starter motor engaged until the torque from the driver is overcome by the torque of the turbine</p> Signup and view all the answers

    What is the primary purpose of using a variable frequency drive electric motor during the start-up sequence of a cogeneration system?

    <p>To adjust the speed of the gas turbine</p> Signup and view all the answers

    What is the role of the PLC in the start-up sequence of the cogeneration system?

    <p>It sends commands to the variable frequency driver (VFD) for starter motor speed control and breaker closure</p> Signup and view all the answers

    What are the commands sent by the PLC to the variable frequency driver (VFD) during the start-up sequence?

    <p>Close Starter Motor A Breaker and Starter Motor B Breaker, Gas Turbine “A” Starter Motor Speed Control and Gas Turbine “B” Starter Motor Speed Control</p> Signup and view all the answers

    Which of the following is the primary role of the operator in the start-up sequence of the cogeneration system?

    <p>Initiating the turbine start up from the control room and letting the PLC direct the starter motor through the speed commands</p> Signup and view all the answers

    What information does the PLC receive from the starter system during the start-up sequence?

    <p>ZSC9002A - Gas Turbine “A” Starter Breaker Closed and ZSC9002B - Gas Turbine “B” Starter Breaker Closed</p> Signup and view all the answers

    Which of the following describes the start-up sequence for a small (under 5 MW) electrical generation plant with the waste heat supplying a steam turbine attached to a generator?

    <p>It involves the operator initiating a turbine start up from the control room, and a programmable logic controller (PLC) directs the starter motor through the start up and speed commands</p> Signup and view all the answers

    What is the role of the variable frequency driver (VFD) in the start-up sequence of the cogeneration system?

    <p>It receives commands from the PLC and controls the starter motor speed and breaker closure</p> Signup and view all the answers

    What is the primary purpose of the diverter valve in the gas turbine startup sequence?

    <p>To direct the exhaust gases to the HRSG</p> Signup and view all the answers

    At what speed is the fuel admitted to the combustor and ignited in the gas turbine startup sequence?

    <p>55% of rated speed</p> Signup and view all the answers

    What is the purpose of the clutch in the gearbox during the gas turbine startup sequence?

    <p>To engage the starter motor</p> Signup and view all the answers

    What happens to the diverter valve once the HRSG is producing steam?

    <p>It is opened to allow hot combustion gases to enter the HRSG</p> Signup and view all the answers

    When is the auxiliary burner started in the gas turbine startup sequence?

    <p>Once the diverter valve is closed</p> Signup and view all the answers

    What is the purpose of the silencer in the gas turbine startup sequence?

    <p>To direct exhaust gases to the atmosphere</p> Signup and view all the answers

    What is the primary function of the PLC during the start-up sequence of a cogeneration system?

    <p>To direct the starter motor through the start-up and speed commands</p> Signup and view all the answers

    What is the purpose of the commands sent by the PLC to the VFD?

    <p>To control the gas turbine speed</p> Signup and view all the answers

    What information does the PLC receive from the starter system during the start-up sequence?

    <p>Starter motor breaker status</p> Signup and view all the answers

    What is the purpose of the starter motor in the cogeneration system?

    <p>To initiate the turbine start-up</p> Signup and view all the answers

    What is the significance of the sequence of commands sent by the PLC during the start-up sequence?

    <p>To prevent equipment damage</p> Signup and view all the answers

    What is the primary purpose of the gas turbine in the cogeneration system?

    <p>To generate electrical power</p> Signup and view all the answers

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