[?]: PID controller FB41 to control the dosing of H2SO4

[mohammedhhh]

I'm new in PID controllers
I use siemens continuous PID controller FB41 to control the dosing of H2SO4 to adjust the PH of the water but I can't get the right PH.
and I use same controller also to control the flow by opening and closing control valve and i can't get the right flow.
can you help me with this
thank you all

[Nedjeljko]

...usualy in CIP systems I used dosing for one component two regulators:

once is TonToff controler which is working in Ton time and not working in Toff time, and second controller are SPonSPoff which activate TonToff function if PH is not enough...

So with this controllers I have good regulation, but my dosing pump are impulse pump.

[mohammedhhh]

thanks for reply
but can you give me more details?

[Dreamer76]

where is your problem with the fb41?

[mharmouche]

I'm new in PID controllers
I use siemens continuous PID controller FB41 to control the dosing of H2SO4 to adjust the PH of the water but I can't get the right PH.
and I use same controller also to control the flow by opening and closing control valve and i can't get the right flow.
can you help me with this
thank you all

hi all,
I Think the problem is not in controllors but in studying of system.
as you know the diffusion take time so if you increase the time of integration you get more stability of your process.
concerning the flow , if you have the differential pressure (and the flow ) you can choose the right valve. then the system pressure (close off pressure) emporte you to the right selection of actuator of valve.
finaly you can start programming.

[Nedjeljko]

thanks for reply
but can you give me more details?

..depends which system you use...In my example I have long time to caustic come from object of cleaning, so I used mentioned metod...if you make some drawing of your system it will be easier to see what you exactly need...so please make drawing of your regulation circuit..

[bunglehead]

I think you all are speaking about neutralization (or pH controlling in general). So mentioning PID controllers makes me think about neutralization in flow (without any tank or vat). If so there's nothing to do with circuit filling and related time.
Author should properly adjust regulator, deadbands etc.
Too few information provided so don't expect a reliable answer.

Regards.

[Nedjeljko]

...thats why I ask for technological drawing to see needs of process

[mohammedhhh]

this is the drawing and i want to get the right pH and you must know that the folw is not fixed and the comming water pH also not fixed.
the pH of outlet water is very critical in range (6.5 to 7.2)
thank you all

[Fashao100du]

How about clamping the loop output Hi/Lo limit. It may help

[dsekulic]

Hi,

This is classical example of time lag (time delayed) control system. For that purpose I don't think that PI or PID controller will help You. 'I' action will lead You to oscilation in pH because of time lag between control and measure point. My advice is to use 'P' controller but with variable gain because flow rate vary 6 times. That mean that for gain for 400m3/h will be insuficient for 2400m3/h flow. You should make some experiment to see what is the best gain for wich flow and than adapt gain of P controller to apropriate flow rate. I supose You measure the flow.

regards

[Yu Sek Piau]

i think, the problem at setting for PID parameter isn't Correct about Gain, Integral

Why not to try used PID AutoTune which in Siemens Library

[Nedjeljko]

I agree with dsekulic...you can make changeable Gain depends of flow...make couple test and check range of changing...after that you can make some equation for calculation for gain in flow from 400 up to 2400m3/h..

let us know how it working..or its working..