OPTIMUM GAS QUALITY SPECIFICATIONS - A LABORATORY'S PERSPECTIVE: WHAT SHOULD IT CONTAIN AND WHAT TESTS SHOULD BE CALLED OUT

摘要

As new gas fields are developed in remote sections of the globe, we have witnessed an accelerated development and production of gas fuels and especially the production of green gas fuels such as sour gas and landfill gases. But fuel gas quality is changing and contaminants are increasing. This proves to adversely affect the turbine operation in today's designs of turbines of all sizes throughout the industry. Fuel gas specifications must be defined more stringently. This applies not only to the calorific content of the gas composition but also to minimizing the particulates, liquid hydrocarbons, water vapor, trace metals, and any inorganic material accompanying the gas fuels. Particulates and trace metals can have a deleterious effect on the service life of a turbine. Contaminants in natural gas are different than those in other gas; for example, siloxanes are often found in landfill gases. A comprehensive analysis of gas fuels will not only ensure quality but also will tremendously assist in specifying what type of fuel conditioning systems should be installed. The analysis will help define filtration types (dry/coalescing capacities, pore sizes, etc.). This will address from the beginning, current problems facing many utilities such as undersize filters which result in constant clogging, frequent shut-downs/restarts, which are especially critical for base load turbines and where the utility relies on their constant operation. These are the questions that can be answered using the well-defined gas quality specifications. Detailed recommendations for suitable gas fuel specifications will be presented using and comparing ASTM and European standards of ISO. A complete specification should define characteristics for both natural gas and green gas. Examples will be given of cost-effective analyses that have been performed which have been shown to enhance overall plant performance.