Can anyone help with the control theory for controlling the differential pressure across a Yankee drying cylinder using a thermo compressor valve,steam make up valve, condensate level and flash steam flow.I am using a Honeywell Alcont DCS if anyone can specific if not just some help with the strategy would help.

 

I have used the Allen Bradely PLC to control the Yankee dryer in tissue machine in one of my projects at Manchester.The difrrentail pressure in yankee drying cylinder depends upon the blow through steam, syphon clearance & type of syphon used.
The makeup steam & the falsh steam from the condensate tank can be combined. The flash steam pressure from the flash tank (low pressure) can be
taken thruogh the thermo compressor for boosting the pressure & can fed to the yankee along with the make up steam. Have a split range controller for the yankee cylinder inlet steam pressure controller. The output of the thermo compressor & steam pressure controller to the make up valve & should be split (0-50% % 50 to100%)respectively.
For a desired speed calculate the blow through steam flow-kg/Hr( or get this data from the yankee designer)& as soon as the yankee cylinder reaches the speed send this setpoint to the flow controller. It is safe to have this setpoint at max speed of yankee. With regard to the condensate tnak level , it is just an ordinary level controller. Well if it is your application is tissue yankee machine , I can send you much more info on the controls.