X
تبلیغات
علم و تكنولوژي (technology weblog)
 
   
     
 
با کلیک روی ستاره یک امتیاز به این مطب بده
 
 

A heat recovery steam generator or HRSG is a heat exchanger that recovers heat from a hot gas stream. It produces steam that can be used in a process or used to drive a steam turbine. A common application for an HRSG is in a combined-cycle power station, where hot exhaust from a gas turbine is fed to an HRSG to generate steam which in turn drives a steam turbine. This combination produces electricity more efficiently than either the gas turbine or steam turbine alone. Another application for an HRSG is in diesel engine combined cycle power plants, where hot exhaust from a diesel engine is fed to an HRSG to generate steam which in turn drives a steam turbine. The HRSG is also an important component in cogeneration plants. Cogeneration plants typically have a higher overall efficiency in comparison to a combined cycle plant. This is due to the loss of energy associated with the steam turbine

Modular HRSG
Modular HRSG GA

HRSGs consist of three major components. They are the Evaporator, Superheater, and Economizer. The different components are put together to meet the operating requirements of the unit. See Modular HRSG GA.

Modular HRSGs can be categorized by number of ways such as direction of exhaust gases flow or number of pressure levels. Based on the flow of exhaust gases, HRSGs are categorized into vertical and horizontal types. In horizontal type HRSGs, exhaust gas flows horizontally over vertical tubes whereas in vertical type HRSGs, exhaust gas flow vertically over horizontal tubes. Based on pressure levels, HRSGs can be categorized into single pressure and multi pressure. Single pressure HRSGs have only one steam drum and steam is generated at single pressure level whereas multi pressure HRSGs employ two (double pressure) or three (triple pressure) steam drums. As such triple pressure HRSGs consist of three sections: an LP (low pressure) section, a reheat/IP (intermediate pressure) section, and an HP (high pressure) section. Each section has a steam drum and an evaporator section where water is converted to steam. This steam then passes through superheaters to raise the temperature and pressure past the saturation point.

Packaged HRSGs are designed to be shipped as a fully assembled unit from the factory. They can be used in waste heat or turbine (usually under 20MW) applications. The packagaged HRSG can have a water cooled furnace which allows for higher supplemental firing and better overall efficiency.

Some HRSGs include supplemental, or duct firing. These additional burners provide additional energy to the HRSG, which produces more steam and hence increases the output of the steam turbine. Generally, duct firing provides electrical output at lower capital cost. It is therefore often utilised for peaking.

HRSGs can also have diverter valves to regulate in the inlet flow into the HRSG. This allows the gas turbine to continue to operate when there is no steam demand or if the HRSG needs to be taken offline.

Emissions controls may also be located in the HRSG. Some may contain a Selective Catalytic Reduction system to reduce nitrogen oxides (a large contributor to the formation of smog and acid rain) and/or a catalyst to remove carbon monoxide. The inclusion of an SCR dramatically effects the layout of the HRSG. NOx catalyst performs best in temperatures between 650°F and 750°F. This usually means that the evaporator section of the HRSG will have to be split and the SCR placed in between the two sections. Some low temperature NOx catalysts have recently come to market that allows for the SCR to be placed between the Evaporator and Economizer sections (350°F-500°F.

Applications

  • Heat recovery can be used extensively in energy projects.
  • In the energy-rich Persian Gulf region, the steam from the HRSG is used for desalination plants.
  • Universities are ideal candidates for HRSG applications. They can use a gas turbine to produce high reliability electricity for campus use. The HRSG can recover the heat from the gas turbine to produce steam/hot water for district heating or cooling.
Block diagram of IGCC power plant, which utilizes the HRSG


Medium (Media) Blog مركز تخصصي طراحي و اجراي قالبهاي وبسايت در ايران دانلود قالب رايگان Digtal Classic (ديجيتال) براي وبلاگ بلاگفا
 
 
   |    نوشته شده توسط سجاد مقصودی
 
با کلیک روی ستاره یک امتیاز به این مطب بده
 
 
Building a Map of Dark Energy

Building a Map of Dark Energy

Understanding dark energy is probably one of the largest mysteries in cosmology right now. Figure this out, and a Nobel Prize in physics is assured. But it won't give up its secrets so easily. Since they can't measure dark energy directly, astronomers can only measure its effects on the large-scale structures of the Universe, and then tease out some of its characteristics.



Understanding dark energy is probably one of the largest mysteries in cosmology right now. Figure this out, and a Nobel Prize in physics is assured. But it won't give up its secrets so easily. Since they can't measure dark energy directly, astronomers can only measure its effects on the large-scale structures of the Universe, and then tease out some of its characteristics.

In a recent survey using the European Southern Observatory's Very Large Telescope, and international team of 51 astronomers from 24 institutions gathered the light from more than 13,000 galaxies. This survey contains galaxies within a 25 million cubic-light years volume.

Using this survey, they were able to map out the large scale structures in the nearby Universe, including clusters of galaxies and filamentary superclusters. By measuring the velocity of the different clusters as they speed away from us, at different times in the past, the astronomers were able to measure the speed distortion contributed by dark energy.

Their conclusions lend evidence to the so-called cosmological constant theory originally introduced by Albert Einstein - there's some constant repulsive force that exists throughout space. But the uncertainties in their calculations doesn't rule out other possibilities.

One of the most popular of these is known as modified gravity. In this situation, gravity just acts differently at large scales than it does in the small scale.

But the researchers feel that a measurement that might cover 10 times the volume of this survey could be able to tell the difference between a dark energy force of exotic origin or an actual modification of theory of gravity.

Medium (Media) Blog مركز تخصصي طراحي و اجراي قالبهاي وبسايت در ايران دانلود قالب رايگان Digtal Classic (ديجيتال) براي وبلاگ بلاگفا
 
 
   |    نوشته شده توسط سجاد مقصودی
 
 
     
 

pictofxt

Digital Classic Template

template id : TBF_007 template name : Digital Classic Template for Blog

rohamgas

سجاد مقصودی

http://rohamgas.blogfa.com

علم و تكنولوژي (technology weblog)

درباره نویسنده: سلام.. اميدورام كه اين مجموعه جمع آوري شده بتواند كمك شاياني در بالا بردن سطح اطلاعات شما كاربران عزيز داشته باشد. فارغ التحصيل در مقطع كارشناسي ارشد رشته مكانيك گرايش طراحي جامدات .. و هم اكنون دانشجوي دكتري مكانيك در گرايش تبديل انرژي هستم..

مقالات ارائه شده:
مديريت زمان
مديريت جلسات
موتورهاي DC
ترجمه كتاب Power Generation Handbook - Selection, Applications, Operation, and
Maintenance
در اين وبلاگ با جديدترين مطالب علمي و تكنولوژي آشنا خواهيد شد..... Professional Web Site Design Center

Template Design Workshop offers professional web templates, flash templates and other web design products available for immediate download. This template also designed by Template Design Workshop design team. You can download free templates for your site, blog, cms or portal. Feel free to contact us about new templates.

tbf_007, TBF_007, digital, Digital Template, template, white template, pictofxt, blog, blogging, dairy, note, يادداشت, زوزانه, خاطرات, وبلاگ, بلاگ, قالب سفيد, ديجيتال كلاسيك, ديجيتال, قالب ديجيتال, قالب كلاسيك Interactive CD Catalogue گروه طراحي چندرسانه اي وبلاگ رسانه گشت و گذار در دنياي رسانه هاي ديجيتال Medium Blog - Digital Media World Site Design Studio Professional site design Template Design Studio Flashmate قالبهاي رايگان سايت و وبلاگ. Advanced Persian Blog Templates. pictofxt Farsi Blog
mohandes چت و گفتگو دانلود نرم افزار





Powered by WebGozar