Steam quality, mass flow rate, temperature and pressure of the steam

In summary, the pressure has to be high enough for the turbine to move at a given torque but there also has to be sufficient volume to produce the speed (rpm) that's necessary. Can you work it from that?
  • #1
candice_84
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How should steam quality, mass flow rate, temperature and pressure of the steam be optimized in order to have the most out of turbine? I mean which ones have be to be higher?
Also when they design turbine, do they design it based on the properties of the steam or they change the properties of the reactor to meet the turbine requirement? (I assume this has to be dependent on the power density of the core as well)
 
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  • #2


I believe most turbines operate on pressure drop.
the pressure has to be high enough for the turbine to move at a given torque but there also has to be sufficient volume to produce the speed (rpm) that's necessary.
Can you work it from that?
 
  • #3


Look at the enthalpy difference across the turbine (inlet to exhaust), multiply by mass flow rate to get energy 'delivered' to the shaft. Though in the real world this is complicated (e.g., extraction steam at various enthalpies).

In general, the turbine is designed based on specified steam conditions, not the other way around. Most nuclear units provide saturated steam (since the SG tubes are covered with liquid in a PWR and the fuel pins are covered in a BWR). An exception would be the 'once through' steam generators in B&W designs - the upper portion of the tubes is above the water level, and therefore produce some superheating of the steam. You could say that this design began with the desire to provide superheat steam to the turbine.

As far as steam quality (in the U-tube SG designs) - it is important to the turbine designers but I think it is a second order effect (whether the steam is 0.1% or 0.2% moisture carry-over has an effect on the power, but it isn't a big effect).
 
  • #4
candice_84 said:
How should steam quality, mass flow rate, temperature and pressure of the steam be optimized in order to have the most out of turbine? I mean which ones have be to be higher?
Also when they design turbine, do they design it based on the properties of the steam or they change the properties of the reactor to meet the turbine requirement? (I assume this has to be dependent on the power density of the core as well)
The output of the plant is pre-determined - that's a basic functional requirement/spec. There is some thermodynamic model, so the thermodynamic efficiency is known to some degree.

Turbines are designed to run at a set speed, usually 1500 rpm in areas using 50 Hz, or 1800 rpm in areas using 60 Hz. This determines the blade tip speed based on the size of the blade, and the blade size is determined by the capacity of the turbine and number of stages. The stages and blade designs are optimized with respect to the properties of the steam. There are also high pressure and low pressure turbines on the same train. There can also be intermediate, but on large power turbine sets, I've seen 1 HP and 3 LP turbines.

ARABELLE™ Steam Turbine for Nuclear Power Plants
http://www.power-technology.com/projects/flamanvillenuclear/flamanvillenuclear4.html
http://www.memagazine.org/backissues/membersonly/aug98/features/reactor/reactor.html [Broken]
http://goliath.ecnext.com/coms2/gi_0199-6648034/Steam-turbines-how-big-can.html [Broken]

http://www.energy.siemens.com/hq/en/power-generation/steam-turbines/
http://aunz.siemens.com/Energy/Generation/FPG/EP/Pages/PG_4058_SteamTurbinesandGenerators.aspx [Broken]

http://www.gepower.com/prod_serv/products/tech_docs/en/steam_turbines.htm

http://www.mhi.co.jp/en/products/category/steam_turbine.html [Broken]

http://www.hitachipowersystems.us/products/steam_turbines/index.html [Broken]
http://www.hitachipowersystems.us/s.../technical_papers/brochures/Steam_Turbine.pdf
http://www.powergenu.com/courses/9/PDF/PGU_9_HitchiNclrTrbns.pdf [Broken]

http://www3.toshiba.co.jp/power/english/thermal/products/turbines/steamidx.htm
 
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  • #5


I can explain that steam quality, mass flow rate, temperature, and pressure are all important factors in optimizing a turbine's performance. Steam quality refers to the amount of vapor in the steam, and it should be as close to 100% as possible for efficient energy conversion. A higher mass flow rate means more steam is flowing through the turbine, which can result in higher power output. Temperature and pressure are also crucial, as they determine the energy content of the steam and the force with which it will drive the turbine.

Ideally, all of these factors should be optimized to achieve the highest efficiency and power output from the turbine. However, there may be trade-offs between these parameters, as increasing one may affect the others. For example, increasing the temperature of the steam may result in a higher mass flow rate, but it could also put more stress on the turbine and decrease its lifespan.

When designing a turbine, engineers consider the properties of the steam as well as the power density of the core. The power density of the core refers to the amount of heat energy produced per unit volume, and it can impact the temperature and pressure of the steam. Therefore, the design of the reactor and the properties of the steam must be carefully coordinated to ensure optimal performance of the turbine.

In conclusion, all of the factors mentioned (steam quality, mass flow rate, temperature, and pressure) play a role in optimizing turbine performance. The design of the turbine must take into account the properties of the steam and the power density of the core to achieve the most efficient and effective operation.
 

1. What is steam quality and why is it important?

Steam quality refers to the amount of water vapor present in steam. It is important because it affects the efficiency and effectiveness of steam processes and equipment. Steam with high quality (low water content) is more energy efficient and can prevent damage to equipment due to water droplets.

2. How is the mass flow rate of steam calculated?

The mass flow rate of steam can be calculated by multiplying the density of steam by the volumetric flow rate. The density of steam is dependent on its pressure and temperature, which can be measured using specialized equipment. The volumetric flow rate can be measured using a flow meter.

3. What factors affect the temperature of steam?

The temperature of steam is affected by its pressure, humidity, and energy content. The higher the pressure, the higher the temperature of the steam. Humidity, or the amount of water vapor present, can also affect the temperature. The energy content of steam is determined by its quality, with higher quality steam having higher temperatures.

4. How does pressure impact the quality of steam?

Pressure has a direct impact on the quality of steam. As pressure increases, the quality of steam decreases. This is because higher pressure allows for more water molecules to be present in the steam, resulting in lower quality steam with a higher water content. Conversely, decreasing pressure results in higher quality steam with a lower water content.

5. What is the relationship between pressure and temperature in steam?

There is a direct relationship between pressure and temperature in steam. As pressure increases, so does the temperature of the steam. This is known as the steam saturation curve. However, once the steam reaches its saturation point, any additional increase in pressure will not result in a temperature increase, but rather a phase change from liquid to vapor.

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