A couple of questions on Gas/Steam turbines.

In summary, gas turbines are placed in open atmosphere while steam turbines are placed under a roof in Combined Cycle Power Plants due to their different operating cycles. Reciprocating compressors are not commonly used with gas turbines due to their integration into the turbine system and the availability of other compressor options. HRSGs and steam generators/boilers are technically similar but have differences in size and geometry.
  • #1
mecheng
12
0
1. Why Gas turbines are placed in open atmosphere while steam turbines under roof in Combined Cycle Power Plant?

2. What are the reasons for not using the reciprocating compressors with Gas turbines other than mass flow rate?

Thanks in advance!
 
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  • #2
mecheng said:
reciprocating compressors

What does it mean? :confused:
 
  • #3
Clausius2 said:
What does it mean? :confused:

In Gas Power Plants, two types of compressors are used.

1. Axial Flow (Rotary)
2. Centrifugal

Is it possible to use a reciprocating compressor in Gas Power Plants?
 
  • #4
My experience is that the compressor is on the same shaft as the gas turbine, and a rotary compressor is integrated into the turbine system. Basically modern gas fired turbines are aeroderivative designs based on jet (aircraft) engines. See GE turbine page:
http://www.gepower.com/prod_serv/products/aero_turbines/en/index.htm - look at the both the LMS and PGT series' performance characteristics.

It may be possible that a reciprocating pump is used in the fuel supply system. But look at GE's Compressor products page for some performance characteristics of different designs.

From GE - http://www.gepower.com/prod_serv/products/compressors/en/index.htm [Broken]

Axial compressors are used for very high flow and low pressure applications. Our product range covers extensive customer requirements, from highly standardized equipment to cutting-edge compression solutions for liquefied natural gas plants.

Performance
• Inlet volume from 100,000 to 600,000 m³/h
• Discharge pressure up to 25 bar-absolute

--------------------------------------------
Vertically split compressors are designed to cover a wide range of applications and pressures. They are used primarily for high pressure applications such as ammonia, urea and methanol synthesis, refinery recycle and natural gas compression and injection.

Performance for High Pressure Applications
• Capacity range: up to 15000 m³/h (3,531,700 ft³/h)
• Pressure: up to 700 bar (10,157 psi)

--------------------------------------------
Horizontally split compressors are used for high flow and low pressure applications. The GE Oil & Gas range of products covers all market needs from standardized equipment to cutting-edge compression solutions such as state-of-the-art compressors for liquefied natural gas plants.

Performance
• Capacity range: up to 500,000 m³/h (17,658,000 ft³/h)
• Pressure: up to 40 bar (580 psi)

--------------------------------------------------------------

Steam turbines are used in a closed (Rankine) cycle where the discharge is condensed and recycle back to the boiler, which in a combined cycle plant can be based on the discharge of the gas turbine. The CO2 cannot be condensed under the same conditions, and is therefore discharge to the atmosphere.

Another factor is that centrifugal pumps operate at lower speeds, e.g. 1200 rpm as compared to >3600 rpm power a gas turbine shaft. Gearing down would just add to capital and maintenance costs.
 
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  • #5
Thanks Astronuc!

Your reply was quiet helpful.

One more question regarding the CCPP.

Q. Is there any technical difference between HRSG (Heat Recovery Steam Generator) and Steam Generator/Boiler (used in Steam Power Plants)?
 
  • #6
HRSG are located downstream in the exhaust of a boiler, so I suspect while they are technically similar to boilers, they operate a lower temperatures. See this site for some examples of HRSG's and boilers. There are differences in size and geometry.

http://www.power-technology.com/contractors/boilers/gallery.html

Hitachi http://www.hitachi.us/Apps/hitachicom/content.jsp?page=powerequipment/PowerGeneration/Boilers/index.html&level=2&section=powerequipment&parent=PowerGeneration&nav=left&path=jsp/hitachi/forbus/powerequipmentsystems/&nId=iD
http://www.hitachi.us/Apps/hitachicom/content.jsp?page=powerequipment/PowerGeneration/HRSG/index.html&level=2&section=powerequipment&parent=PowerGeneration&nav=left&path=jsp/hitachi/forbus/powerequipmentsystems/&nId=iD

Altsom

Also, check out the power industry trade journal Power Engineering published by Pennwell Publishing Co. -http://pepei.pennnet.com/ [Broken]
 
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1. What is a gas/steam turbine?

A gas/steam turbine is a type of engine that converts the energy from the combustion of fuel into mechanical energy. It consists of a compressor, a combustion chamber, and a turbine. The compressor compresses the air, which is then mixed with fuel and ignited in the combustion chamber. The hot gas produced from this process then drives the turbine, which in turn generates power.

2. What are the main differences between gas and steam turbines?

The main difference between gas and steam turbines is the working fluid. Gas turbines use hot gas produced from the combustion of fuel, while steam turbines use high-pressure steam. Gas turbines also operate at higher temperatures and pressures, and are generally more efficient and compact compared to steam turbines.

3. What are the applications of gas/steam turbines?

Gas/steam turbines are commonly used in power generation, such as in power plants and industrial facilities. They are also used in marine propulsion systems, as well as in gas-pumping stations for pipelines. Gas turbines are also used in aircraft engines.

4. How do gas/steam turbines contribute to the environment?

Gas/steam turbines are considered to be more environmentally friendly compared to other types of engines, as they produce lower emissions. Gas turbines, in particular, have lower emissions of nitrogen oxides and particulate matter. Additionally, steam turbines can be powered by renewable energy sources, such as biomass or geothermal energy, making them even more environmentally friendly.

5. What are the maintenance requirements for gas/steam turbines?

Regular maintenance is necessary for gas/steam turbines to ensure optimal performance and to prevent breakdowns. This may include regular inspections, cleaning, and replacement of parts. The frequency and extent of maintenance may vary depending on the type and usage of the turbine. Proper maintenance can also help extend the lifespan of a gas/steam turbine.

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