Problem 13.6: A plant returns 8000 lbhr of condensate at
From Chapter 13 Problem Set. Level 2: Applied Thinking.
Question
A plant returns 8,000 lb/hr of condensate at 170°F. Cold makeup is 60°F. Boiler efficiency is 82%. Natural gas costs $12/MMBTU. The plant operates 8,000 hours per year. (a) Calculate the hourly energy savings from condensate return. (b) Calculate the annual fuel savings in dollars.
Answer
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(a) Q = 8,000 × 1.0 × (170 − 60) = 880,000 BTU/hr. (b) Annual energy = 880,000 × 8,000 = 7.04 × 10⁹ BTU = 7,040 MMBTU. Adjusted for efficiency: 7,040 / 0.82 = 8,585 MMBTU. Cost: 8,585 × 103,024/yr**.