1 reply to this topic

[fmalik]

Hello, I have Hysys Dynamic Simulation question:

How can I improve my HYSYS dynamic model for an ammonia reforming reactor connected to a combustor?

In my setup, the reforming reactor (modeled as a PFR) converts ammonia into reformate gas (primarily hydrogen and nitrogen), and the combustor burns unreacted ammonia and a portion of the reformate to provide the heat required for the endothermic reaction. An energy stream connects the combustor to the PFR to transfer this heat.

To model this, I use a PID control loop on energy stream to control reactor outlet temperature by manipulating heat value in energy stream. The controller adjusts the heat duty to maintain the reformate temperature setpoint, which in turn causes the combustion exhaust temperature to fluctuate. To stabilize the exhaust temperature, I’ve added a temperature controller (TIC) between the combustion exhaust and the fuel control valve.

However, I’m encountering a limitation in dynamic mode: the heat duty must be either set manually or controlled—it cannot be calculated by directly fixing the exhaust temperature. Is there a better way to model this setup to overcome this limitation and more accurately represent the system’s dynamic behavior? Ideally I would like the energy required to be "calculated" by fixing the combustion exhaust temperature and have the TIC between reformate temperature and fuel flow control valve. But every time i switch to dynamic mode the energy steam heat valve is no longer calculated and turns manual input (blue)

[Pilesar]

I suggest using process control similar to the real plant. I doubt any real firing controller adjusts fuel to control the combustion exhaust temperature. Are you controlling the excess air? Do you have enough mass in the system? Improper controller tuning may be your only problem. The software vendor offers technical support and may be your most efficient option for assistance.