5 replies to this topic

[Zauberberg]

Is it possible to specify pH value of a given stream within HYSYS flowsheet, in the same way that temperature, pressure, flow and composition are being specified?

I have problems in making a model of refinery wastewater equalisation basin, where all waste streams are routed to - I have pH values of all streams and I want to simulate steady state and dynamic behaviour of this system when individual or multiple changes are made in quality of the streams. But, it is impossible to enter (specify) pH value of a stream - it can be done only by manipulating concentrations of acid and base components, which is long long iteration process. So I was wondering if it is possible to specify pH and wait for HYSYS to back-calculate concentrations of acid and base components, and make the simulations much more faster.

Thanks in advance,

[Steve McGahey]

Is it possible to specify pH value of a given stream within HYSYS flowsheet, in the same way that temperature, pressure, flow and composition are being specified?

I have problems in making a model of refinery wastewater equalisation basin, where all waste streams are routed to - I have pH values of all streams and I want to simulate steady state and dynamic behaviour of this system when individual or multiple changes are made in quality of the streams. But, it is impossible to enter (specify) pH value of a stream - it can be done only by manipulating concentrations of acid and base components, which is long long iteration process. So I was wondering if it is possible to specify pH and wait for HYSYS to back-calculate concentrations of acid and base components, and make the simulations much more faster.

Thanks in advance,

I haven't done it myself, but I suspect you would need to use the electrolyte add-in. This would (logically, but no guarantee) give you access to ion-species. That's the only value I can give on this topic...

Then, as you say, you could set up a pile of adjusts (in SS) or controllers/spreadsheets (in Dynamics) to achieve a given [H+] conc.

As to if HYSYS can do a pH balance to work out the degree of disassociation of each species... I don't know - but this would have to be a step in the right direction.

ACTUALLY, this should count as a pile of reactions... HYSYS should be able to set up reactions in vessels and determine what the equilibrium conc should be. All you need to do is find a way to FIX the pH in the reaction vessel.

No solution, but maybe you can find something in what I've said to set you down a new potential path?

[Zauberberg]

Thanks Steve,

In SS-mode it is possible to use multi-adjuster operation and set the desired pH-value of every individual stream. Also, by using the same electrolyte package, there is a possibility to install Neutralizer unit operation, which allows for an option to specify pH of effluent (product), by manipulating reagent flow to the pH-reactor (if knowing pH and flowrate of incoming wastewater stream - this is very nice for quick evaluation of acid/base demand for achieving targeted pH).

Though, it is very complicated to play with the simulation with more than 10 process streams flowing into the basin. Every process stream can have any pH-value in the practice, so I need to have both acidic/caustic adjusters for each individual stream. I was thinking if there is anything more intuitive and faster to perform simulations.

Regards,

[AA Mishra]

You tabulate feed streams.

You separate.

PH Quantity
3 - 5

5- 9

9-14

3 - 5 quantity, you route at control.

On line cautic addition is better.

5 - 9 no control.

9 - 14 quantity, you route at control.

On line H2SO4 addition is better.

Equalisation basin outlet 8 - 9.

Aerate.

Bio chemical reactions.

At discharge 7

You go home.

Regards

[Zauberberg]

Dear AA Mishra,

Your style of answering is remind me of poetry. It sounds very harmonic and it is absolutely in accordance with process engineering... Though, most other people outside ChEs wouldn't agree that process engineering is nothing more than pure art.



Best regards

[JoeWong]

Another way of "answering"...similar to poetry...everybody said it's great...but i always failed to appreciate

JoeWong