Abstract:

A heat recovery steam generator (HRSG) is a fundamental component of all combustion turbine-based combined cycle power plants. While it's primary purpose is to convert exhaust gas heat to steam, an important secondary function is to reduce noise emissions from the combustion turbine exhaust. This source, at about 155 dB (overall) re: 1 pW for a 100-MW turbine, is the highest noise emission source in any combustion turbine plant. Therefore, the residual exhaust noise emissions leaving the HRSG walls and stack exit must be predicted with acceptable accuracy to determine the total plant noise level. The sources involved in this prediction methodology will be discussed. The issues include source power levels, wall and duct transmission loss, and the noise reduction characteristics through the HRSG flow path. Special measurement techniques required to quantify HRSG noise emissions are described. Whereas the HRSG is mainly a passive device that attenuates combustion turbine exhaust noise, two HRSG generated sources, steam venting and supplemental duct firing, will also be discussed. [See NOISE-CON Proceedings for full paper.]