CSE Pure Power - Fall 2008 - (Page 16)

❯❯ PURE POWER // FALL 2008 16 cover story or other means. The output frequency is exactly proportional to the speed at which the generator is driven. The functional purpose and interconnection issues will determine the generator design. Interconnection: Grid interconnection requirements have certain common characteristics with respect to operations and safety, like compliance with IEEE Standard 1547. However, state and local utility requirements and grid characteristics (radial or network) will vary dramatically. This is an area where minimum commissioning usually is dictated by the utility and site commissioning issues are sometimes missed. Waste heat recovery schemes: This covers the wide variety of means to recover waste heat from generators and/or processes for delivery to thermally activated technologies. The range of systems covers ducting and reclaiming heat from hot air sources (process, engine, turbine, microturbine exhausts) and recovering heat in the form of hot liquids (engine jacket water, oil cooling and exhaust, process streams). Thermal technologies: The most common technologies are heat recovery heat exchangers, heat recovery steam generators, absorption chillers, desiccant dehumidiﬁers, steam turbines, and organic Rankine cycle (ORC) generators. Turning waste heat into hot water or steam generally is the simplest and most cost-effective. Absorption chillers can convert the waste heat to chilled water, but add another level of complexity and cost to the project. Absorbers are either provided as low-temperature single-stage or hightemperature two-stage machines. Desiccant dehumidiﬁers can be coupled to hot air streams in the 250 F range or hot water in the 190 F range. ORCs can absorb 400 to 600 F heat and provide electricity at 10% to 15% cycle efﬁciency. CHP integration: CHP integration focuses on successfully integrating the power generation with the thermal heat recovery and thermally activated technologies. The effectiveness of this effort varies widely depending on the degree of pre-engineering and packaging. Retroﬁt systems require more ﬂexibility and ability to balance the system in the ﬁeld. Building system integration: Integrating a CHP system to building loads and systems is critical and requires knowledge of the buildings’ operation (retroﬁts) or design intent (new buildings). Here, too, ﬂexibility and ability to balance systems are essential. There are more elements that need to be considered in applying and commissioning today’s CHP in buildings. Understanding the components and their integration requirements, along with having the ﬂexibility and means to balance systems, is essential. Finally, having a commissioning plan that tests the system’s capabilities is essential. CHP system performance speciﬁcations Rated performance at 95 F Net power Cooling CHP efﬁciency Rated performance at 59 F Net power Cooling CHP efﬁciency kW Refrigeration ton % 227 142 91 kW Refrigeration ton % 193 124 80 Table 1: The performance speciﬁcations for the CHP system installed were provided by the National Accounts Energy Alliance report to Oak Ridge National Laboratory, Oak Ridge, Tenn. Rated NOx emissions are less than 9 ppm at 15% exhaust oxygen, which met local emission requirements in force at the time of the installation. The exhaust from each microturbine is manifolded together to deliver input energy to a double-effect absorption chiller. The lithium bromide/water chiller consists of an evaporator, absorber, condenser, high- and low-temperature generators, solution heat exchangers, refrigerant and solution pumps, purge, controls, and auxiliaries. The chiller is an adaptation of a direct-ﬁred chiller that increases the heat transfer area of the ﬁrst stage generator to compensate for Upgraded network protector includes electronic relay with adjustable time delay Under power relay trips before network protector 37 C-30 controller trips generator if only one network protector is closed DG Generator circuit breaker trip signal COMMISSIONING A CHP PLANT A CHP system was installed at a deluxe 336-room hotel in downtown San Francisco. The CHP system is a predesigned standard product that contains four microturbines each rated at 60 kW of electrical power at 59 F at sea level conditions. www.purepowermagazine.com Figure 2: Additional equipment for network interconnection. This schematic shows the grid interconnection equipment installed at this site to satisfy the electric utility’s requirements. Note the site has three network feeds, each with a network protector. These network protectors were upgraded to add time delay features and automatic reset capabilities. Source: UTC Power http://www.purepowermagazine.com

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CSE Pure Power - Fall 2008 In the News Commissioning CHP Enhancing Emergency Lighting Data Centers for Uncle Sam Handling a Nuisance Trip Sustainable Projects and Partnerships New Products Ad Index

CSE Pure Power - Fall 2008

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