Thursday, December 30, 2010

CrazyEngineers Forum

CrazyEngineers Forum

Feed water pump hydraulic coupling _video

Posted: 30 Dec 2010 02:35 PM PST

FEED WATER PUMP HYDRAULIC COUPLING




Eighty Percentage 80% of thermal power plants has boiler feed pump , that takes the water from the feedwater system ( from the DA) and provide this water to the boiler system , to generate steam which is responsible for rolling the Turbine,Therefore Generate Electricity.

Normally Feed water pumped to the boiler is pumped to the Boiler's Drum where at the top point of the boiler, so we have to provide big pump that can handle big pressure with great flow to the boiler.

That is happened by this huge pump ( Boiler Feed Pump ) , BFP is usually rotate with 5000 rpm ,150 barg and can provide about 300 T/H.









This big pump needs a prime mover with high electrical rating - Power Plants usually use Electrical Induction motor - to rotate this pump, the rating of this prime mover is usually about ( 5 MWatts , 6.6 KVolts , 1600 rpm ). It is very huge rating if you imagin , 5 MWatts can provide Electricity to a small town.




so , as you see in the picture ( left hand is the prime mover_motor) , (Right hand is the pump) and what is it at the middle of the picture??



Hydraulic Coupling


Hydraulic Coupling is used to transmit Power in a wear-free manner from a prime mover (driving machine) to a power consumer(driven machine-pump). the power is transmitted in the following way:-




* by means of a connecting coupling between the driving machine and geared variable speed coupling.

* by means of a step-up gear unit between the input shaft and primary shaft.

* hydro-dynamically by means of the working oil between the primary wheel and the secondary wheel.

* by means of connecting coupling between the driving machine and geared variable speed coupling.









the control at the hydraulic coupling is done by the scoop tube control, it provide infinitely variable adjustment of the driven machine's speed. the power from the driving machine is transmitted to the primary wheel to the working oil, the working oil is accelerated in the primary wheel, and the mechanical energy is converted into the energy of fluid flow. the secondary wheel picks up the flow energy and converts it into mechanical energy. this energy is transmitted to the driven machine.









Speed Control





the speed of the driven machine is infinitely variable. this is accomplished by varying the amount of oil in the coupling during operation with the aid of the adjustable scoope tube.

* Scoop tube advanced as far as possible into the scoop champer of the coupling (0% position):minimum oil ring , minimum speed.

* Scoop tube retracted as far as possible out of the scoop champer of the coupling (100% position): maximum oil ring, maximum output speed.
THESE FILES ARE SO GOOD FOR THIS TOPIC.


Quote:


hydr_couplg.exe
speed control.pdf
Vorecon_applications.pdf

Robogames'11 invitation - techkriti - iit kanpur

Posted: 30 Dec 2010 11:32 AM PST

RoboGames'11
The Annual Robotics Competition in Techkriti, IIT Kanpur

RoboGames is the platform where you can prove that your proficiency and experience in building robots is unparalleled in the nation. History bears testimony of the way in which instigated undergraduates have competed in a manner that has made RoboGames a primary attraction of Techkriti itself.

Undergraduate students of all disciplines are invited and challenged to participate in this competition which will comprise both manual and autonomous robotic events involving playing soccer, navigating different terrains, traversing under and on surface of water and entertaining the audience.

If you have a predilection for robotics, we welcome you to Robogames'11 @ IIT Kanpur, from 17th to 20th Feb 2011.

CASH PRIZES WORTH Rs. 2.5 LAC TO BE WON!!!

For details on the event, do visit

http://www.techkriti.org/#/competitions/robogames/
http://www.techkriti.org/#/competitions/wild-soccer/enterWSC/

Last date for online registration is 15th Jan, 2011.

For any queries, mail us at robogames@techkriti.org or contact any of the Coordinators.

Expecting you in Techkriti'11 participating with full zeal and enthusiasm at RoboGames..!!!

Wishing you a very Happy New Year ahead,

Coordinators,
RoboGames'11

Note : For the benefit of all please forward this invitation to all the Robotics enthusiasts or to the full student body of your college.

mini projet for instrumentation

Posted: 30 Dec 2010 08:39 AM PST

hi everyone.......im 3r year applied electronics and instumentation (aei) student .i need 2 do a mini project dis year,so cn u guyz plz help me wid ideas bot d topics i shld choose..plz

Can Your Boiler Feed Pump Handle a Deaerator Pressure Transient?

Posted: 30 Dec 2010 06:37 AM PST

Can Your Boiler Feed Pump Handle a Deaerator Pressure Transient?


"This is part of an article talking about the importance of DA and BFP positions at power plant "


In a typical steam power plant, the boiler feedwater (BFW) pump takes suction from the deaerator (DA) and discharges high-pressure water to the boiler through the feedwater heaters. During normal operation, the DA is supplied with steam turbine extraction steam to mix with and heat the feedwater. Other purposes for the DA are to provide the required net positive suction head (NPSH) for the BFW pump and to serve as a storage tank to ensure a continuous supply of feedwater during rapid changes in BFW demand.
The available net positive suction head provided to a boiler feedwater pump can drop enough during a pressure excursion to cause cavitation and damage to the pump's internal parts. A careful analysis of various operating profiles can ensure that the pump operates safely during the pressure fluctuations that occur after a steam turbine trip or large load change.
How does the plant designer or operator determine the adequacy of the BFW pump selection or the DA and feedwater system design? It's not uncommon to find that the BFW pump was originally specified based on steady-state conditions and did not consider the DA pressure transients that occur during a steam turbine trip (with the boiler remaining in service) or a sudden steam turbine load reduction. If the NPSH available to the BFW pump during the pressure transient drops below that required by the pump for only a short period of time, cavitation and damage to the pump internals often result.
An NPSH deficit in an existing system or a new system under development can be avoided by using some very simple analytic tools.




Find the NPSH margin

The deaerator is installed at some elevation above the BFW pump to provide the NPSH required by the pump. By definition, the NPSHr is the total suction head over and above the vapor pressure of the liquid pumped.
The DA elevation minus the dynamic losses in the BFW suction piping between the DA and the BFW pump equals the NPSH available (NPSHa) to the pump. The difference between the value of the NPSHa and that required (NPSHr) by the pump gives the NPSH margin.
The NPSH margin or the NPSH margin ratio (NPSHa/NPSHr) is an important factor in ensuring adequate service life of the pump and minimizing noise, vibration, cavitation, and seal damage. The NPSH margin requirement increases as the suction energy level (for example, high suction specific speed, high peripheral velocity of impeller, and the like) of the pump increases. In the case of the BFW pump, this ratio could be in the range of 1.8 to 2.5. These margins are typically based on steady-state operation.
In addition, the NPSH margin improves the ability of the BFW pump to handle a DA pressure transient. Once a design is determined to have an adequate NPSH margin, the next step is to determine if the NPSH margin is adequate during a pressure transient.




Expect Deaerator Pressure Decay

Immediately after a steam turbine generator trip, turbine extraction steam is no longer available to the deaerator, resulting in decay of the DA pressure. Also during a sudden steam turbine generator load reduction, the extraction steam pressure decreases until the extraction stage supplying the DA can no longer maintain DA pressure. This also results in DA pressure decay as the lower-temperature condensate continues to enter the DA, cooling the stored feedwater
The decrease in DA pressure causes some of the water in the DA storage tank to flash to steam until saturation pressure is reached at the new DA pressure. The water in the BFW pump suction line has a static head exerted on it by the level in the DA storage tank, preventing it from flashing immediately. Therefore, the water in the suction line can be considered as a slug of hot fluid that must be moved through the pump in some finite amount of time. In other words, the pump will not perceive a decrease in vapor pressure (or a decrease in water temperature) until the entire slug of hot water has passed through the pump.
During the passage of the hot-water slug, the combination of high vapor pressure at the pump suction along with a decrease in pump suction pressure (due to DA pressure decay), results in a "critical point" at which the suction pressure may drop below the minimum required pressure (that is, the vapor pressure of the hot-water slug plus the pressure equivalent of the NPSHr). This low suction pressure could result in cavitation damage to the pump internals due to insufficient net positive suction head




Short Residence Time

The time required for passage of the hot-water slug through the pump suction line is the "residence time." Residence time can be expressed as the suction line volume divided by the volumetric flow rate (or, alternatively, as the mass of liquid in the suction line divided by the mass flow rate)
Note that because the vapor pressure at pump suction is modeled to decay only after the residence time has elapsed, the critical point occurs at the end of the residence time interval. The challenge is to determine the DA pressure at this critical point and thereby the system NPSH margin.




Options for Adding NPSH to the System

The main BFW pumps are generally large, high-energy pumps needing large amounts of NPSHr. One solution would be to raise the DA to a higher elevation to increase the NPSHa. This solution is normally not practical or cost-effective. Another approach is to install a low-speed, low-NPSH booster pump upstream of the BFW pump. The booster pump discharge pressure then provides the added NPSH required by the BFW pump. In addition, the same NPSH analysis must be made on the booster pump. The only difference is that in the case of the booster pump arrangement, the critical point and the critical point margin need to be evaluated at the booster pump suction as well as the BFW pump suction.






Additional Transient Condition

An additional transient condition that the system designer must consider occurs during a "hot start." In this situation, steam flash (water-steam mixture) can occur at the pump suction and cause cavitation damage to the pump internals. However, the mechanism causing steam flash is slightly different than what was discussed earlier.
On a plant trip, the DA pressure drops and the water temperature inside the DA drops. However, the pump and suction piping near the pump remain at a higher temperature due to the mass of the metal. As a result, when the pump is operated on a hot restart of the plant, steam flash and cavitation are likely to occur at the pump suction






"This article for, Magdy Mahmoud is manager of engineering for PGESCo., Egypt."

Open Feed Water Heater (Deaerator)

Posted: 30 Dec 2010 06:30 AM PST

Open Feed Water Heater (Deaerator)


An open feadwater heater , also called direct-contact and deaerating (DA) heater , is one that heats the feedwater by directly mixing it with bled steam from the turbine. Usually only one DA is used at Power Plant.
Because the pressure in such a heater can't exceed the turbine pressure at the point of extraction, a pump (Main Boiler Feed Water Pump) must follow the heater. The confluence of steam and water flows makes possible the efficient removal of noncondensables as well as the heating of the feedwater.






The DA heater is usually positioned in the feedwater line at a pressure to prevent air inleakage and at a temperature at which Oxygen retention is least likely. Most DA heaters are designed for Oxygen concentration in the outlet feedwater below 0.005Cm3/L
The DA outlet feedwater is at or near saturation. Pumping saturated water results in cavitation because of the pressure drop below saturated pressure, thus causing flashing on the back side of pump vanes. The DA heater is therefore usually positioned in the powerplant steam-generator house high above its pump by perhaps 60 ft. This provides sufficient pump inlet pressure to render the saturated water compressed (or subcooled) and prevents cavitations.


There are three types of DA heaters for industrial and utility use.
1) Spray-Type deaerators .
In this type the feedwater enters the heater through nozzles that spray it into the extraction-steam-filled heater space. The water is heated and scrubbed to release the noncondensables gases. A second agitation of the now-heated feedwater by another steam flow is provided by an internal baffling system.


2) Tray-Type deaerators.
Here the feedwater is directed onto a series of cascading horizontal trays. It falls in sheets or tubes from tray to tray and comes into contact with rising extraction steam admitted from the bottom of the tray system. As scrubbing occurs and noncondensables gases and some steam rise, they come into contact with colder water, resulting in a reduced volume of high concentration of noncondensables to vent into the atmosphere.


3) Combination spray-tray deaerator
In this type, the feedwater is first sprayed into a steam-filled space, then made to cascade down trays. This combination type with horizontal stainless steel trays is currently preferred by utilities.












You noticed that just below the heater, is a relatively large feedwater tank (Storage Tank) which allows sufficient water for rapid load variations.

Hi all there!

Posted: 30 Dec 2010 05:26 AM PST

Hi guys :happy:
This is Mehdi ;)
I'm passing third year of my electrical engineering course...

I'm ready to learn more and more and I also wanna share my little knowledge :D

Geinimi Android Trojan Removal

Posted: 30 Dec 2010 04:49 AM PST

Geinimi - the new Android Trojan is infecting android powered handhelds all over the world. If you are and android phone owner, this news might be important to you. Lookout Mobile security company has discovered this Trojan steals personal data from your mobiles and sends it to a centralized server. This information can include your messages, phonebook addresses and other important data.

Geinimi is also been called the most sophisticated and advanced malware on Android powered mobiles."Geinimi is effectively being 'grafted' onto repackaged versions of legitimate applications, primarily games, and distributed in third-party Chinese Android app markets," Lookout said in a blog post. "The affected applications request extensive permissions over and above the set that is requested by their legitimate original versions."

Geinimi can -

* Send location coordinates (fine location)
* Send device identifiers (IMEI and IMSI)
* Download and prompt the user to install an app
* Prompt the user to uninstall an app
* Enumerate and send a list of installed apps to the server.

In order to remove this Trojan from your mobiles, head over to following location and install the following software -

https://www.mylookout.com/download

technical seminar topics

Posted: 30 Dec 2010 04:32 AM PST

I'm a final year student of engg.
Can u suggest some interesting topics for technical seminar related to information science and engg?
wil be waiting for the reply....

How E-Bay Works ?

Posted: 30 Dec 2010 03:55 AM PST

I read the sites too.

Can somebody explain me how e-bay site works ?

What i knw till now is,

the seller process,

1.register/acct creation
2.registration of the product pics/title/photo etc.,
3.Then setting the price,
4.Offering the shipping details

the buyer process,

1.acct creation
2.search for the product and select the product
3.add to cart
4.payment via paypal or credit card or something else
5.Confirmation mail abt payment

My questions,

When seller gets the payment from the seller ? Whether immediately after the buyer done the payment or after sending the product to the customers or after sending the product to the e-bay shipping office or when?

WHo will receive the immediate payment ? Seller or the E-Bay

PS:- No Links Please

Cisco Cius Tablet : Will this tablet work?

Posted: 30 Dec 2010 03:31 AM PST

The innovative Cisco Cius is an ultra-portable, mobile collaboration business tablet that offers access to essential business applications and technologies.

What day is it today?

Posted: 30 Dec 2010 03:29 AM PST

My friend asked me this one today. Try it:

Tom is walking throughout a forest. He wants to know what day of the week it is. So he stops and asks a lion and a tiger. Now, the lion lies all of the time on Monday, Tuesday and Wednesday. The tiger always lies on Thursday, Friday and Saturday. When Tom asked the lion what day it is, he said "Well, yesterday was one of my lying days." Then Tom turns to the tiger and asks what day it is and the tiger replies, "Yesterday was also one of my lying days." What day is it?

Explain your answer:)

Blackberry Playbook : How will it be?

Posted: 30 Dec 2010 02:58 AM PST

Preview of the new professional-grade BlackBerry® PlayBook™ tablet and BlackBerry® Tablet OS.

First Robotics 2011 Competition - how to start a team?

Posted: 30 Dec 2010 02:36 AM PST

"The secret of building a successful team is not to assemble the largest team possible, but rather to assemble a team that can work well together." – Dean Kamen, Founder of FIRST.

We feel it is important that you learn all you can about the FIRST Robotics Competition before committing to forming a team. One way to do this is to find a local team or two, and follow their progress through a competition season. Attending a regional competition will allow you to gauge the impact of the competition for yourself. You can meet with team leaders and students, speak with sponsors, and see robots first-hand.


Once you are ready to start an FRC team, your first step is to form the partnerships you will need with team mentors and sponsors. Local manufacturing and technology companies are ideal candidates for mentors and sponsorship, as are local colleges, universities and technical schools. Many local chapters of professional organizations support FIRST through volunteer help from their engineers, scientists and technologists

Can you give me the ideas for Online Shopping Cart Application

Posted: 30 Dec 2010 02:35 AM PST

Hai CEans

I planned to design the online shopping cart application. I visited the some of the sites like ebay for ideas. Still I am searching for the more requirements / ideas to design my application innovatively.

Why I'm asking here is , more of the buyers or sellers have an idea or feeling that some feature is not available in the ebay or some other popular sites while purchasing the product online.

Please put some ideas over here,

PS:- It does not matter what you want to post is already built in E-Bay..I'm collecting inputs/feedbacks only. :)

Sound Engineer Remembers Michael Jackson

Posted: 30 Dec 2010 02:31 AM PST

Local, Bruce Swedien, worked with Michael Jackson as a sound engineer on albums like "Off The Wall", "Thriller and"Bad"
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