Cost Effectively Increasing the Filtration Area in Fabric Filters for Large Power Plants

Abstract

The market demand for very low outlet particulate emissions from power plants is resulting in the choice of fabric filters (FFs) over electrostatic precipitators (ESPs) in many projects. For the same flue gas volume flow, the higher the required removal efficiency, the choice between ESP or FF tends to favor the FF, due to its lower capital cost. As a result of the increasing demand for FFs, suppliers need to meet the market requirements by providing properly designed, efficient, cost effective FF designs. Many of the projects requesting FFs today are for coal fired boilers. As the size of the boiler increases, the larger the amount of flue gas that needs to be cleaned, and the larger the size of the FF, Increasing the filtration area in each compartment of a FF to meet this need is not a simple process of scale-up. Maintaining low outlet emissions, the same or lower FF pressure losses, and equal or longer bag life are all key factors. As the filtration area in each filter compartment increases, the amount of flue gas and dust entering the compartment increases, and the risk of performance, pressure drop and bag life problems increases if the compartment arrangement is not designed properly. Alstom Power Systems (APS) is currently completing an extensive effort of increasing the amount of filter area that can be installed in each compartment of a FF. This paper presents the key aspects of design to address gas and dust distribution, and pressure drop issues, as well as the pulse cleaning system design and capacity. APS is actively working in the research laboratory as well as in new FF installations to demonstrate the success of the new design.