Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Steam Turbine performance with variation in inlet steam flow rate

Steam Turbine performance with variation in inlet steam flow rate

Steam Turbine performance with variation in inlet steam flow rate

Dear All,

I am estimating a future problem while still in erection phase for 1350KW steam turbine. I need your help to estimate a solution.

Due to some reason, the flow rate of high pressure steam goes to the turbine is decreased at the desired pressure (other parameters are remain same). Therefore I want to know the effect of reduce inlet flow rate in the HP Steam turbine output. What’s the effect of reducing power output on RPM? Can we control this effect by changing output pressure? Is it possible to reduce drop power output by changing in RPM or output pressure of turbine?

The steam parameters are mention below:

1- Current condition

Manufacturer : SHINKO
HP Steam inlet pressure : 30 bar
HP Steam inlet temperature : 236 Degree C
Steam Consumption : 30 (ton/hr)
HP Steam Turbine outlet pressure 3.5 bar
HP Steam Turbine outlet Temperature 148 Degree C

2- New Condition
Steam Consumption : 20 (ton/hr)

There is 1 extraction of LP steam from the turbine to Back Pressure Receiver

Can somebody suggest the role of flow rate in steam turbine. Will steam turbine able to work properly even at low flow rate inlet?

RE: Steam Turbine performance with variation in inlet steam flow rate

It will "work" at the reduced flow of the steam.

It will NOT make your original 1350 KWatt. (Depending on internal flow degradation, and on the heat extraction percent changes) it will probably be close to 20/30 x 1350 KWatt It will also be less efficient that if it were running at design pressure, temperature and steam flow.

Why do you think reducing rpm will somehow increase or negate the effect of cutting off 1/3 of your steam flow?

What effect will reducing RPM have on your load? If a pump or similar centrifugal (fan) load, then the lower rpm means significantly lower pump output. (You're much lower on the pump curve.)

RE: Steam Turbine performance with variation in inlet steam flow rate

Dear racookpe1978;
thanks for your comment.
I just want to know the relationship between power and RPM.

RE: Steam Turbine performance with variation in inlet steam flow rate

Reduced flow ( away from BEP ) usually results in reduced efficiency.

Directionally, decreasing the backpressure on turbine exit should give you more power, but the increased velocity on the last few stages of the turbine may result in sonic flow / blade vibration and fatigue. So dropping the exit pressure down may not be possible. To confirm how far you can decrease exit pressure to attempt to get back to 1350kW at 20t/hr at constant rpm ( ie. constant torque) , the steam turbine vendor should be able to help.

RE: Steam Turbine performance with variation in inlet steam flow rate

The "fan laws" indicate that the flow will vary linearly with rpm, the pressure across the turbine vary by the 2nd power of the rpm, and the power produced vary by the 3rd power of the rpm.

"Nobody expects the Spanish Inquisition!"

RE: Steam Turbine performance with variation in inlet steam flow rate

Back to my original question: What are you driving with the steam turbine?

RE: Steam Turbine performance with variation in inlet steam flow rate

Let me try with the simple view:

Energy (steam) input in the turbine is diverted in three: 1350kw, loss and recovered/diverted energy.

Less energy in = less energy out, equal in percentage or probably a bit larger in percentage of loss as well as same for recovered energy.

RPMs can probably be regulated and will be as is if load (KW) are reduced.

Relationships :see davewitz (?) Linear with rough calculation?

Advice: study the manual for operational and regulation trimming and adjustments.

If the turbine has a regulated bypass and a large amount of steam is diverted at normal operation less input from boiler may not be critical, as more could be directed to turbine.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


eBook - Integrating the Engineering Ecosystem
Aras Innovator provides multiple options for integrating data between systems, depending on the scenario. Utilizing the right approach to meet specific business requirements is vital. These needs range from authoring tools, federating data from various and dissimilar databases, and triggering processes and workflows. Download Now
Research Report - Simulation-Driven Design for SOLIDWORKS Users
In this engineering.com research report, we discuss the rising role of simulation and the paradigm shift commonly called the democratization of simulation. In particular, we focus on how SOLIDWORKS users can take advantage of simulation-driven design through two analysis tools: SOLIDWORKS Simulation and 3DEXPERIENCE WORKS. Download Now
White Paper - Industry 4.0 and the Future of Engineering Education
With industries becoming more automated, more tech-driven and more complex, engineers need to keep their skills and knowledge up to date in order to stay on top of this wave—and to be prepared for the Industry 4.0 future. The University of Cincinnati offers two online Master of Engineering degree programs designed specifically for practicing engineers. Download Now
eBook - The Design Gridlock Manifesto
In this eBook, you’ll learn 6 ways old CAD technology slows your company down and hear how design teams have put those problems to rest. “The Design Gridlock Manifesto” shares first-hand modern CAD experiences from 15 companies around the world. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close