P22
Energy transfer stations In Denmark and Europe, the traditional way of converting an existing in-building oil-/gas-fired boiler installation to district heating is to replace the boiler with a prefabricated energy transfer station (ETS). In North America, the approach is generally to build the installation on-site, buying the individual components separately from different suppliers. In addition to a heat exchanger, the ETS units include all necessary control valves, gauges, filters and controls equipment and heat meters. The design team has specified the use of prefabricated ETS units in all current and future Trafalgar and Davis campus buildings to be connected to the campus heating and cooling systems. The advantage of the prefabricated ETS approach is that all is bought from one supplier, saving time and cost and reducing risk should something need replacing. Outlook Estimates of the size of the US district energy market varies; around 2,500 systems are seen mentioned but there is “only” around 720 known systems. In Canada the figure is around 128. There is no single national legislative policy framework in either the US or Canada impacting district energy, and any growth is managed largely without any policy support, subsidies or favourable legislation as these are more commonly seen directed towards the electricity and the power industry. Although the same focus and support that is given to power infrastructure and Combined Heat and Power (CHP) is not directed towards the district energy industry and the distribution of thermal energy, the district energy industry in North America is expected to continue its small but steady growth.
Figure 4 - Illustration of district heating costs as a function of pipe dimension (source Ramboll).
Piping installation: best of both continents In designing the Sheridan distribution networks, Ramboll applied its extensive experience inDenmark with the installation of pre-insulated district heating and cooling piping, a relatively new product in North America. Installation to European Standards (ENs) while complying with local regulations required the design team to maintain a greater focus on and higher accuracy in such aspects of the installation as welding and pressure testing. Based on Ramboll’s recent experience with another Canadian district energy project also designed to ENs, the team was able to identify some specific European approaches to installation that will stand the Sheridan project in good stead. One example is the more challenging welding alignment required in the EN standards. This requirement is important because the steel casing of the pre-insulated pipe (ca. 2 mm [0.079 inch]) is thinner than that of the steel pipe specified in accordance with ASME standards (ca. 4 mm [0.16 inch]). (See table 1 for a comparison of standards.) Table 1 - Comparison of North American and European standards for installation of pre-insulated district energy piping
For further information please contact:
Ramboll Att.: Pernille M. Overbye M +45 5161 8460 PMO@ramboll.com www.ramboll.com/energy
North American standards Ontario Regulation 220, CSA B51, ASME B31.1, etc.
EN 13941 Design and installation of pre- insulated bonded pipe systems for district heating
X-ray not required
X-ray required on 10% of welds
Alignment to be within 2 mm (approximately 0.079 inch)
Alignment to be within 1 mm (approximately 0.04 inch)
Hydrostatic pressure test to be 1.5 times the design pressure, held for 10 minutes, then reduced to design for leak test
Pressure test is not required, but weld leak tightness test of all welds is required
E N E R G Y A N D E N V I R O N M E N T
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