PRC valve

To lower the tower pressure, the hot-vapor bypass pressure recorder controller (PRC) valve is closed. This forces more vapor through the condenser, which, in turn, lowers the temperature in the reflux drum. As the liquid in the reflux drum is at its bubble point, reducing the reflux drum temperature will reduce the reflux drum pressure. As the stripper tower pressure floats on the reflux drum pressure, the pressure in the tower will also decline. 

To lower the tower pressure, the hot-vapor bypass pressure recorder controller (PRC) valve is closed. This forces more vapor through the condenser, which, in turn, lowers the temperature in the... 

Prc sure Pressure Relief or Safety Valve Pressure Safety Valve ... 

Regenerator flue gas left the top of regenerator through porous stainless steel filters to pressure control valve PRC-6, to an orifice, and a sample tap. From this point the flue gas could be vented, as shown on the flow sheet for nitrogen-air once-through... 

On inverting equation set (9.23) and introducing the critical pressure ratio limit in the valve throat, Prc(y)/Pi. the corresponding equations for the throat pressure ratio in terms of the valve pressure ratio when the latter is low become ... 

Figure 21.22. Schematic setup for helium pycnometry with an initial pressure in the sample chamber of zero (only the difference in gas pressure between the two chambers is relevant therefore any actual present offset can be subtracted from the pressures in the system). After a difference in helium pressure (prc) is established between the reference and the sample chamber (volume Vrc and Vsc, respectively), the valve between the chambers is opened. At equilibrium the pressure in the two chambers is equal. The setup is kept under thermostated conditions.

When the relief valve nozzle plugged, the PRC (tower pressure control) began to show a lower operating pressure. 

The advantages of locating the high pressure alarm nozzle (PAH) and the pressure controller (PRC) on their own dedicated %-inch connections is that each device can be individually isolated, tested, and its nozzle cleared by the outside operator without interfering with the function of the relief valve. I have discussed these procedures in detail in my book. Troubleshooting Process Plant Control (Wiley, 2009). 

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