Combined Cycle Gas Turbine Startup Emissions – Quantification Methodology and Permitting Strategies

摘要

Gas turbine (GT) startup (SU) emissions limits are included in nearly all air permits. This was not always the case, but over the past decade or so as nitrogen oxide (NOX), and especially carbon monoxide (CO), analyzers became more accurate at measuring the wide range of emissions during a gas turbine startup (CO can range from < 1 to several thousand parts per million), air regulators have required quantification and imposed limits. Historically, GT combined cycle (CC) SU emissions have been categorized as ‘Cold’, ‘Warm’, and ‘Hot’, based on the number of hours since the previous shutdown, and either steam turbine (ST) rotor and/or heat recovery steam generator (HRSG) drum temperatures. However in reality, these categories have proven themselves to be fluid, vague and a highly inaccurate way of qualifying CC SU emissions. Based on operational data from several large-frame (e.g. ‘F’ and ‘H’) GT in CC, a more logical approach based on oxidation (aka ‘CO’) and SCR catalyst temperatures, which are the true differentiators between startup types, will be discussed. Data supporting the reasoning behind defining GT CC SU as either ‘Cold’ or ‘Non-Cold’ and what these qualifiers mean, will be presented. Permitting strategies related to limitation and estimation of SU emissions will also be presented.