Factors affecting the steam output of gas boilers
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What is the impact of using condensate and softened water for making up water in gas boilers on evaporation rate?
Deoxygenated water is usually at 104°C, while the temperature of condensed water is generally lower, which will slightly affect the evaporation rate; the superheating temperature will increase as a result.
You need to look beyond the surface phenomena to understand the essence. In this case, it can be assumed that the amount of gas flowing through is constant; in other words, the heat input to the furnace, Q, is constant. Under normal operating conditions, the enthalpy value of the steam, i”, is also considered constant, while the enthalpy value of the feedwater, i’, is variable. It can be roughly estimated that the evaporation rate D = Q/(i” – i’). Of course, the higher the temperature of the feedwater, the greater the evaporation rate!