Best practice no.20

Choking or reheating calorimeter (Ellison) . They are because, if the steam is throttled and then expands without doing work or losing heat, the total energy of the steam remains unchanged. Radiation losses must be reduced to a minimum and to do so, the calorimeter and the duct connecting to the steam pipe must be completely thermally insulated. The steam enters through the sampling nozzle and expands as it passes through an orifice, enters the vapor chamber, finally escaping through the upper part. Momentary excess moisture is separated and re-evaporated within the vapor chamber, and the effect is indicated in direct proportion by the superheat thermometer located in the vapor path. To know the initial pressure of the steam, you need to use a manometer.

The expression for the vapor titer can be stated as the total enthalpy of the wet saturated vapor before expansion ( h f + Xh fg ) is equal to the total enthalpy h of the superheated steam after expansion.

Where:

X = steam quality, expressed as a decimal fraction. h = total enthalpy of superheated steam at the absolute pressure of the calorimeter, in kcal/kg or BTU/lb h f = enthalpy of the liquid at the initial pressure, in kcal/kg or BTU/lb h fg = enthalpy of vaporization of dry saturated steam at initial absolute pressure, in kcal/kg or BTU/lb

If we have a boiler that works at 6.5 kg/cm² gauge

Then:

calorimeter mass............................................. : 11.682 kg Calorimeter mass + water ............................... : 22.370 kg Calorimeter mass + water + water vapor......... : 23.218 kg mass of water ( m H2O )....................................... : 10.688 kg steam mass ( m v )............................................. : 0.848 kg Fina Mass l ( m f ).............................................. : 11.536 kg

Enthalpy of water at a temperature of 15°C (ambient): ( U H2O ) 15.04 kcal/kg Final enthalpy of water: ( U f ) 61 kcal/kg

To calculate h have :

h f = 165.6 kcal/kg h fg = 493.9 kcal/kg

calculated X

This means that the titration or quality of the steam will be 96.11% dry steam and 3.89% will be humidity.

FOR-IM-024

REVISION DEL FORMATO: C

FECHA DE EFECTIVIDAD DEL FORMATO:10/03/2022