Does anyone know of a good method to calculate the quality of steam leaving the disengagement space of a waste heat boiler?  The boiler recovers heat from reactor effluent and produces steam to cool the process gas.

In a throttling calorimeter, the steam is throttled to atmospheric pressure.  The throttling process is isenthalphic, meaning that the enthalpy of the steam is the same at the high and low pressure.  Based upon the temperature after the throttling valve(Bellow Seal Valves), the steam quality can be calculated using a steam table.

If the upstream condition is denoted as "1" and the downstream condition is denoted as "2", then

X1 = (h2-hf1) / hfg1,  where

X1 = quality of steam at high pressure
hf1 = enthalpy of saturated liquid at high pressure
hfg1 = enthalpy of vaporization at high pressure
h2 = enthalpy of (superheated) throttled steam at low pressure

h2 is looked up in a steam table based upon the temperature reading from the throttling calorimeter.

You may want to consider installing an inline centrifugal separator on the boiler discharge.  Wright Austin makes a good unit that they claim will remove 99% of entrained liquid.  I believe that they are owned by Hayward now.

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