Seeking advice on the selection of steam pressure for boiler deaeration
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What pressure of steam is suitable for use in boiler thermal deaerators? Upon researching, I found that the enthalpy of saturated steam doesn’t change much with variations in pressure; only the temperature varies significantly. For example: at 2.0 MPa, the enthalpy of saturated steam is 2797.4 and the temperature is 212.37°C; at 1.0 MPa, these values are 2777.0 and 179.88°C respectively; at 0.5 MPa, they are 2748.5 and 151.85°C. Given that the difference in enthalpy is minimal, there should theoretically be little to no difference when heat exchange occurs between the steam and feedwater. Therefore, I would like to ask: which pressure level of steam would be most suitable for use in a deaerator?
Generally, a lower pressure rating is chosen to reduce heat loss; for example, in process units where there is an abundance of low-pressure steam, 0.5 megapascals can be selected. There is no significant difference in the deoxygenation effect.