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Geothermal steam venting, Geysers, CA
Courtesy of Calpine |
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Noise Associated with Geothermal Development, Department of Energy |
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In the 1970s, while working on Environmental Impact Reports in the Geysers area of California, we studied noise associated with geothermal development. Some was caused by equipment used for well drilling, but most came from the high pressure steam emitted from an active well. The jet noise is caused in the turbulent mixing region downstream of the pipe opening, where high velocity steam mixes with the quiescent atmosphere. Since a well emits not only steam but also rocks and dirt, normal mufflers are not effective. Part of the drilling process is to remove rocks using a cyclonic separator such as that shown above.
When a sufficient number of wells have been drilled, pipes are constructed to carry the steam to the plant. These large pipes, as much as a mile in length, contain multiple right angle bends to control thermal expansion. Before entering the turbines, rocks and dirt must be removed to prevent damage.
Jet noise occurs not only at the well heads during drilling, but also at the power plant when it has to be shut down for periodic maintenance. While the plant is off line the steam is vented directly to the atmosphere. Since the amount of noise is very dependent on the steam velocity, the most effective way of controlling it is to lower the velocity. |
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