2 replies to this topic

[Aiden Choi]

Hello!! Everyone.

I'm korean chemical process engineer.

 

Currently, I'm trying to simulate the medium pressure(15kg/cm2g) steam header using HYSYS Dynamic.

There are 4 steam sources and 10 steam users. In/out steam flow rate is 100 ton/hr.

But additional1 steam user will be add. So we have to consider overall steam balance.

When additional steam user is added, 4 source flow rate will be increase by pressure balance. 

 

I would like to fix the flow rate of specific steam source and user.

Does anyone have a idea on how to fix the flow rate?

Any suggestions are greatly appreciated.

Attached Files

•  HYSYS-Flowsheet.pdf   31.61KB   59 downloads

[Zauberberg]

Use the flow controller.

[Lucian Gomoescu]

Hello Aiden,

As Zauberberg said, in Dynamic Mode you must use controller blocks instead of adjust blocks.

In your situation you have to follow these steps:

i. Decide where this 11th steam user is connected, the pipe size, fittings etc and what controls the flow rate to it (another simple  flow controller, i assume);

ii. Decide upon valve flow coefficient requirements (desired valve pressure loss and flow rate);

iii. Decide which steam source flow controller(s) will have the set point(s) increased in order to permit the required flow rate (be

carefull that the sum of steam sources FC set point increments equalls the set point of this 11th steam user);

iv. Wait for the new steady state to be reached (this will take a very short running time).

I have two observations:

1. I don't see the entire flowsheet but i see that all steam users have FICs. Be carefull, you will never reach steady state if
the set points of sources and users FCs sums are not equal (they will "fight" indefinitely).

2. Mass balances are done for different steady states, therefore my suggestion is to use the Steady Mode for calculating the T,P, F for mass balance and replace FCs with adjust blocks which vary splitters flow ratios in order to have the same pressure in nodes (check the simultaneous solutions box in the ADJ block Parameters tab). I can send you an example, if you want to.

Best regards,
Lucian