Your economizer raises the temperature of the feedwater by 10 degrees. What is the efficiency rate increase associated with this?

When an economizer raises the temperature of the feedwater by a specific amount, such as 10 degrees, it utilizes waste heat from the flue gas to preheat the water entering the boiler. This process enhances the overall efficiency of the boiler system because the boiler requires less energy to turn the feedwater into steam. The increase in temperature means that the water is closer to the boiling point, which reduces the energy required for heating.

In this particular scenario, the increase in efficiency observed with a 10-degree rise in feedwater temperature is approximately 1%. This is a standard value often referenced in the field of boiler operation — indicating that for every increase of about 10 degrees Fahrenheit in feedwater temperature, there is typically a corresponding increase in efficiency of around 1%.

While an increase of 2% might seem plausible, it is generally considered more conservative to estimate a 1% efficiency gain for every 10-degree rise, making the correct answer consistent with common industry standards. The other options do not accurately reflect the known efficiency changes associated with the increase in feedwater temperature.