Cogeneration Design Guide
Including two case studies to help illustrate the entire design process, this guide offers a thorough discussion of the theoretical as well as the practical aspects of a cogeneration system design.
TABLE OF CONTENTS Cogeneration Design Guide
8.2: Walkthrough Analysis
8.2 Walkthrough Analysis
One approach to a walkthrough analysis was described in section 6.5. That procedure is illustrated below, although other approximation techniques are common and acceptable.
Base-Case System
Various assumptions and calculations are reviewed below. These choices were based on the limited amount of information available from a short walkthrough of the facility and historic utility bills. The initial choice of prime mover was based on the apparent need for steam at pressures of 145 psig (999 kPa); a combustion turbine was chosen for the initial analysis.
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Capacity: The initial choice of equipment size was based on a review of the historic demand data. Minimum billing demands have been more than 3,300 kW, with high load factors suggesting that the demands are rather steady. There are a limited number of turbines available in this size range, and the initial choice was a combustion turbine with an ISO rating of approximately 3,270 kW. It is likely that the site loads would drop below 3,000 kW; however, the effect of lower site loads will be examined in more comprehensive analyses at later stages of development. The turbine was derated for an altitude of 500 feet (152.4 m) and inlet and exhaust pressure losses, respectively, of 4 inches (996 kPa) and 8 inches (1,992 kPa). The site rating was determined to be 3,100 kW.
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Fuel Requirements: The fuel requirement was determined from the manufacturer's specification. The value specified by the manufacturer was 42.2 MMBtu/h (12,365 kW), which, when adjusted to...
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