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
Chapter Nine: Case Study II Industrial
This case study looks at the feasibility of cogeneration at a small industrial facility.
9.1 Site Description
The site consists of a single building that has been expanded on several occasions. The powerhouse includes:
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Two electrical service drops, each supplied by the same utility substation.
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A single natural-gas-fired boiler rated at 15,000 pph (6,810 kg/h) that was installed in the 1980s and produces steam at 15 psig (103 kpa).
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A 400-ton (1,408-kW), single-stage absorption chiller.
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A 200-ton (704-kW), electric-driven chiller.
Purchased power is provided by two electric services, although only one is active at a time; transferring from one service to the other is a manual process. Electric power is billed on a time-of-day rate with seasonally differentiated demand and energy rates applicable to on- and off-peak periods.
Historic Energy Requirements
Purchased power and natural gas billing data are shown in Table 9-1 and Figures 9-1 through 9-4. The electricity usage, load factor, and gas consumption have been adjusted based on differences in the actual billing period and the length of the calendar months; these are the basis of subsequent analyses. Electric utility demands were not adjusted for such variations. In this case, based on historic use and current rates, the average cost of purchased power was $.071/ kWh ($19.74/GJ); the average cost of natural gas was $4.21/MMBtu ($3.99/GJ).
Table 9-1: Historical Purchased Power and Fuel Requirements
| AVE COST | 0.071 S/KWH | TOTAL MEASURED DEMAND | 11,306.0 KW | ||||||
|---|---|---|---|---|---|---|---|---|---|
| FAC | -0.015 $/KWH | TOTAL... |
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