Types of generation plant

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Electrical Engineering for NPP Professionals

E14002/Chang C.K.

Prof. Chang ChoongKoo


Generation; Types of Generation Plant

2014. 03. 13

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CONTENTS

1. GENERAL

2. FOSILL POWER PLANTS

3. NUCLEAR POWER PLANTS

4. GEOTHERMAL POWER PLANTS

5. SOLAR REFLECTIVE POWER

6. HYDROELECTRIC POWER PLANTS

7. PUMPED STORAGE HYDRO POWER PLANTS

8. DOMBUSTION TURBINE GENERATION PLANTS

9. COMBINED CYCLE POWER PLANTS

10.WIND TURBINE GENERATORS

11.PHOTOVOLTAIC POWER PLANTS

12.TRENDS OF ENERY MIX

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CHAPTER OBJECTIVES

Discuss the different types of generation plants (i.e., steam, nuclear, wind, etc.)

Describe the different power plant prime-mover types

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Power generation plants produce the electrical energy that is ultimately de-livered to consumers through transmission lines, substations, and distri-bution lines.

Generation plants or power plants consist of three-phase generator(s), the prime mover, energy source, control room, and substation.

To a lesser degree, electrical power is produced from wind, solar, geother-mal, and biomass energy resources.

The more common types of energy resources used to generate electricity and their associated prime movers :

Steam turbines• Fossil fuels (coal, gas, oil)• Nuclear• Geothermal• Solar-heated steam

Hydro turbines• Dams and rivers• Pump storage

1. GENERAL

Combustion turbines• Diesel• Natural gas• Combined cycle

Wind turbinesSolar direct (photovoltaic)

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High-temperature, high-pressure steam is used to turn steam turbines that ultimately turn the generator rotors.

Temperatures on the order of 1,000°F and pressures on the order of 2,000 pounds per square inch (psi) are commonly used in large steam power plants.

Steam at this pressure and temperature is called superheated steam, sometimes referred to as dry steam.

Steam Turbine Power Plants

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The steam’s pressure and temperature drop significantly after it is applied across the first stage turbine blades.

The reduced steam can be routed through a second stage set of turbine blades where additional steam energy is transferred to the turbine shaft.

This second stage equipment is significantly larger than the first stage to al-low for additional expansion and energy transformation.


Blade Inner housingOuter housing

ShaftDiaphragm

http://www.sandvik.coromant.com/en-gb/industrysolutions/condensing_power/steam_turbines/Pages/Turbine-housing.aspx

http://www.sandvik.coromant.com/en-gb/industrysolutions/condensing_power/steam_turbines/Pages/Turbine-housing.aspx

http://www.sandvik.coromant.com/en-gb/industrysolutions/condensing_power/steam_turbines/Pages/Steam-turbine-diaphragm.aspx

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Once the energy of the steam has been transferred to the turbine shaft, the low-temperature and low-pressure steam has basically exhausted its en-ergy and must be fully condensed back to water before it can be recycled.

The overall steam generation plant efficiency in converting fuel heat en-ergy into mechanical rotation energy and then into electrical energy ranges from 25 to 35%.


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Steam turbine power plants can use coal, oil, natural gas, or just about any combustible material as the fuel resource.

However, each fuel type requires a unique set of accessory equipment to in-ject fuel into the boiler, control the burning process.

The coal is burned while on the belt as the belt slowly traverses the bottom of the boiler. Ash falls through the chain conveyor belt.

Scrubbers are used to collect the undesirable gases to improve the quality of the stack output emissions. Bughouses are commonly used to help col-lect fly ash.

Pulverized coal combustion(PCC)PCC is currently the predominant technology for generating electricity from coal.It accounts for more than 97% of the world’s coal-fired capacity. Most existing plants operate at less than SC(Supercritical) steam condi-tions, with the best examples reaching 39% efficiency.

2. FOSSIL FUEL POWER PLANTS

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Fluidized bed combustion(FBC)FBC offers an alternative to PCC for generating electricity from coal. Today it is most often employed in particular or niche applications, for instance where fuel flexibility is required. FBC deals effectively with low-quality coals, biomass and general waste. The plant will burn domestic bitumi-nous coal and has a design efficiency of 43%.

2. FOSSIL FUEL POWER PLANTS(Cont.)

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In nuclear power plants such as the one shown in below, a controlled nu-clear reaction is used to make heat to produce steam needed to drive a steam turbine generator.

All nuclear plants in the United States must conform to the Nuclear Regula-tory Commission’s(NSSC in Korea) rules and regulations.

Extensive documentation is required to establish that the proposed de-sign can be operated safely without undue risk to the public..

Once the Nuclear Regulatory Commission issues a license, the license holder must maintain the license and the reactor in accordance with strict rules, usually called Tech Specs..

3. NUCLEAR POWER PLANTS

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Nuclear reaction is a process in which either two nuclei or a nucleus of an atom with a subatomic particle like a proton, neutron, or high energy electron from outside the atom, collide and produce a new elements.

Nuclear Fission: A large atomic nucleus gets decomposed due to bombardment of some subatomic particle forms one or more than onetype of small nucleus.

Nuclear fusion: The process of fusion of small nuclei to form bigger nuclei is called as nuclear fusion.

Nuclear Fission and Fusion

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In a typical commercial pressurized light-water reactor(1) the core inside the reactor vessel

creates heat, (2) pressurized water in the primary

coolant loop carries the heat to the steam generator,

(3) inside the steam generator, heat from the steam, and

(4) the steam line directs the steam to the main turbine, causing it to turn the turbine generator, which produces electricity.

The unused steam is exhausted in to the condenser where it condensed into water. The resulting water is pumped out of the condenser with a series of pumps, reheated and pumped back to the steam generators.

Pressurized Water Reactors

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Pressurized Water Reactor (PWR). • The basic design of a pressurized water reactor is shown in the figure of

previous slide. The reactor and the primary steam generator are housed inside a containment structure.

• The structure is designed to withstand accidental events such as small airplane crashes. The PWR steam generator separates the radioactive water that exists inside the reactor from the steam that is going to the tur-bine outside the shell..

Advantages and Disadvantages of PWR. • A major design advantage is the fact that fuel leaks, such as ruptured

fuel rods, are isolated in the core and primary loop. That is, radioactive material contained inside the fuel is not allowed to go outside of the con-tainment shell.

• The pressurized water reactor can be operated at higher temperature/ pressure combinations, and this allows an increase in the efficiency of the turbine generator system. Another advantage is that it is believed that a pressurized water reactor is more stable than other designs.

The biggest disadvantage appears to be the fact that the reactor design is more complicated.

Pressurized Water Reactors

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Boiling Water Reactor (BWR). • The reactor housing of the BWR tends to be larger than the PWR and

looks almost like an inverted light bulb.• In a BWR, water boils inside the reactor itself, and the steam goes directly

to the turbine generator to produce electricity. Similar to other steam power plants, the steam is condensed and reused.

• Note that the turbine building is closely coupled to the reactor building, and special constraints exist in entering the turbine building because the water can pick up radioactivity.

Boiling Water Reactors

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• Reactor power is controlled by positioning the control rods from start-up to approximately 70% of rated power. From 70% to 100% of rated power, the reactor power is controlled by changing the flow of water through the core.

Advantages and Disadvantages of BWR. • A major advantage of the BWR is that the overall thermal efficiency is

greater than that of a pressurized water reactor because there is no sepa-rate steam generator or heat exchanger.

• Controlling the reactor is a little easier than in a PWR because it is accom -plished by controlling the flow of water through the core.

The greatest disadvantage of the BWR • The design is much more complex. It requires a larger pressure vessel

than the PWR because of the amount of steam that can be released dur-ing an accident.

• This larger pressure vessel also increases the cost of the BWR. Finally, the design does allow a small amount of radioactive contamination to get into the turbine system.

Boiling Water Reactors

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Other Related Topics to NPP

The overall function or design of the nonnuclear portion of a nuclear power plant is of the same order of complexity as a fossil fueled power plant.

The biggest difference is the degree of documentation that must be maintained and submitted to the regulatory authorities for proof that the design and operation are safe.

Roughly speaking, there are about 80 separate systems in a nuclear power plant. The systems that are most critical are those that control the power and/or limit the power output of the plant.

Environmental. • One of the greatest advantages of a nuclear plant, especially with to-

day’s concerns about global warming and generation of carbon dioxide due to burning, is the fact that a nuclear plant essentially adds zero emissions to the atmosphere. There is no smoke stack!

SCRAM. • A reactor SCRAM is an emergency shutdown situation. Basically, all con-

trol rods are driven into the reactor core as rapidly as possible to shut down the reactor to stop heat production. A SCRAM occurs when some protective device or sensor signals the control rod drive system.

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4. GEOTHERMAL POWER PLANTS

Geothermal power plants use hot water and/or steam located underground to produce electrical energy. The hot water and/or steam are brought to the surface where heat exchangers are used to produce clean steam in a sec-ondary system for use with turbines.

Clean steam causes no sediment growth inside pipes and other equipment, thereby minimizing maintenance. The clean steam is converted into electri-cal energy much the same way as in typical fossil fueled steam

Iceland geothermal power plant

http://www.google.co.kr/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&docid=ae2eLxkoULa_XM&tbnid=M1j3tddRYM9ycM:&ved=0CAYQjRw&url=http://www.gtherm.net/geothermal-power-generation/gtherm-geothermal-technology-advancements/&ei=87ceU6DBJ8OgigekoIC4CA&bvm=bv.62788935,d.dGI&psig=AFQjCNGtMMQEI8fcY5c31uLdnzY5HpWBIw&ust=1394608482364379

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5. SOLAR REFLECTIVE(CONCENTRATED) POWER Solar power plants are environmentally friendly as they produce no pollu-

tion. Large-scale solar reflective plants require a substantial amount of area as

well as specific orientation with the sun to capture the maximum energy possible with high efficiency. The mirrors are parabolic-shaped and motor-ized to focus the sun’s energy toward the receiver tubes in the collector area of the elevated boiler.

The fluid in these tubes can reach operating temperatures in excess of 400C. The mirrors are parabolicshaped and motorized to focus the sun’s energy toward the receiver tubesin the collector area of the elevated boiler.

Solar concentrated power plant

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6. HYDROELECTRIC POWER PLANTS

Hydroelectric power plants capture the energy of moving water. There are multiple ways hydro energy can be extracted. Falling water such as in a penstock, flume, or waterwheel can be used to drive a hydro turbine.

Hydroelectric power generation is efficient, cost-effective, and environmen-tally cooperative.

Hydro units have a number of excellent advantages. The hydro unit can be started very quickly and brought up to full load in a matter of minutes. In most cases, little or no start-up power is required. Hydro plants have a rela-tively long life; 50–60 year life spans are common.

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7. PUMPED STORAGE HYDRO POWER PLANTS Pumped storage hydro power production is a means of actually saving elec-

tricity for future use. Power is generated from water falling from a higher lake to a lower lake during peak load periods. The operation is reversed during off-peak conditions by pumping the water from the lower lake back to the upper lake.

Basically, the machine at the lower level is reversible. One of the problems associated with pumped storage units is the process

of getting the pumping motor started. Starting the pumping motor using the system’s power line would usually put a low-voltage sag condition on the power system.

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8. COMBUSTION TURBINE GENERATION PLANTS Combustion turbine (CT) power plants burn fuel in a jet engine and use

the exhaust gasses to spin a turbine generator. Fuel is then injected into the compressed air and ignited, producing high-pressure and high-tempera-ture exhaust gasses. The exhaust is moved though turbine blades much the same way steam is moved through turbine blades in a steam power plant.

One of the advantages of combustion turbines is that they can actually be designed to be remotely controlled for unmanned sites.

Combustion turbines can be extremely responsive to power system changes. They can go from no load to full load and vice versa in a matter of seconds or in a matter of minutes.

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9. COMBINED-CYCLE POWER PLANTS

The combined-cycle power plant consists of two means of generation: combustion turbine and steam turbine.

The hot exhaust is then coupled through a heat recovery steam generator (HRSG) that is used to heat water, thus producing steam to drive a sec-ondary steam turbine generator. The combustion turbine typically uses nat-ural gas as the fuel to drive the turbine Blades.

The advantage of a combined-cycle (CC) system is that in addition to the electrical energy produced by the fuel combustion engine, the exhaust from the engine also produces electrical energy.

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10. WIND TURBINE GENERATORS

Wind turbine generators tend to have a high cost per kWh produced. There is also a concern about the availability of wind on a constant basis. Most power companies do not consider wind generators to be base load units. Base load implies that units are readily available and that they are part of a 24 hour generation production schedule.

One interesting characteristic of wind power is the fact that power produced is proportional to the cube of the wind speed.

Wind power is accepted as free energy with no fuel costs. Wind power is also considered renewable energy, since wind really never goes away..

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11. SOLAR DIRECT GENERATION (PHOTOVOLTAIC)

The photovoltaic type of solar power plant converts the sun’s energy directly into electrical energy. This type of production uses various types of films or special materials that convert sunlight into direct current (dc) electrical energy systems. Panels are then connected in series and parallel to obtain the de-sired output voltage and current ratings.

This dc energy is converted to utility ac energy by means of a device called an inverter. Solar plants are environmentally friendly as they produce no pol-lution. The main drawback to these plants is the cost of the panels and con-version equipment.

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Global electricity generation has increased by 67% since 1990, reaching almost 19,800 TWh in 2007. Almost 70% of this electricity generation is from fossil fuels and this share has increased since 1990.

Recent Trends:

12. ENERGY PERSPECTVES

<Source : Energy Technology Perspective 2010, IEA >

Fossil : Coal : 37 % 42% Gas : 15% 21% Oil : 6%

Non Fossil : Nuclear 17% 14% Hydropower : 18% 16% Biomass & Waste :

1% 1.3%

Other Renewables ( wind, geothermal, solar) 0.4% 1.2%

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Electricity production from coal is the main source of CO2 emissions from the sector.

Between 1990 and 2007, CO2 emissions from global electricity produc-tion increased by 59% to reach 12 Gt. Most of the rise in CO2 emissions was driven by increases in electricity generation from coal. In 2007, coal-fired power plants accounted for 73% of total emissions from the sector, up from a share of 66% in 1990.

CO2 Emissions


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Biomass and wind constitute the bulk of new renewables capacity up to 2020. Hydro grows continuously over the whole period, but this growth levels off in later years for lack of suitable new sites. By 2050, hydro, wind and solar each make similar contributions to total electricity produc-tion in the BLUE Map scenario.

Future Scenarios

Variable renewable (wind, PV and ocean) : 19%

Total Renewables ( Hydropower, wind, geothermal, solar) : 18% 48%


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In 2007, renewable energy sources represented 18% of power genera-tion worldwide.

By 2050, all world regions produce at least 50% of their electricity from renewables. (Target) Africa and Central and South America achieve shares of more than 90%. China has the highest generation from both onshore and offshore wind.

Carbon Capture and Storage Technology

Hydro power is currently the most important renewable energy source for elec-tricity generation.


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Electricity generation is currently largely based on fossil fuels in many countries and regions. In the absence of new policies, coal use in elec-tricity generation increases significantly.

By 2050, 44% of the world’s electricity comes from coal, slightly higher than its current share. The contribution from gas increases to 23%, while that from oil dwindles to almost zero.

Share of Fossil Fuel Power Plants


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Thank you!