Contact US

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!

*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

Control Valve transfer functions assistance. Any help is appreciated.

Control Valve transfer functions assistance. Any help is appreciated.

Control Valve transfer functions assistance. Any help is appreciated.

I have an effluent treatment plant that brings pH of effluent to between pH 6-9 through multiple tanks. The flow coming out of the last tank must have a pH of 6-9. It is followed by a pump and then 2 valves figure included). One valve goes to a river, which is why pH must be close to neutral, and the other is a valve to recycle the effluent back to the beginning of the process for further treatment if the pH does not meet spec. I would like to use a on/off controller for the valve that goes to the river to close the valve completely if the pH transmitter at tank 4 outlet reads an unacceptable pH (anything less than 6 or greater than 9). The recycle valve will always be closed, but I would like to use a controller to open it if the flow coming out of the pump is less than 15000 kg/hr (minimum flow to avoid deadheading the pump). This decrease in flow happens as a result of the river valve closing due to pH not being correct. I would like the recycle valve to only open enough to allow a flow of 15000 kg/hr to make sure the pump has enough head to pump it back up to the beginning of the process. I have made a basic block diagram to demonstrate what I mean. I am struggling with the transfer functions for the valves and transmitters. They don't have to be very rigorous models, this is just a uni class project, but our professor struggled with the online teaching and as a result my group is struggling through this. The density of the fluid is assumed constant at 1000 kg/m^3 and the pressure drop across the recycle valve can be no more than 3-4 psi to maintain enough head to pump up the fluid, by my calculations. The valves can be considered linear, I believe. Any help would be appreciated and thank you in advance.

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


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