COMBUSTION IMPROVEMENT OF BOILERS AND INCINERATORS USING ECOTUBE SYSTEM – FIRST US INSTALLATION

摘要

This work presents the main features, advantages and evaluation of applications of the novel Ecotube system, an advanced and effective tool for combustion improvement and emission reduction. The Ecotube system was invented by the Swedish company ECOMB AB in the early 90's and has until now been installed in 15 units in Europe. The Ecotube system represents an innovative cost-effective optimisation tool for all combustion processes and principally comprises retractable lances – Ecotubes – that are equipped with injection nozzles. The main application for this technique is air-staging, whereby high velocity air is injected through the nozzles – an advanced Over-Fire Air system. Various agents, such as ammonia, urea and limestone, can also be mixed into the air jets for additional Nox reduction as well as reduction of Sox, HCl etc in the furnace. The Ecotubes are strategically positioned within the furnace enabling injected air and other agents to create a radically improved mixing of the combustion products, resulting in destruction of laminar gas columns and the formation of completely mixed turbulent flow patterns. CFD and a special in-furnace camera technique are used to examine and confirm the right position of the Ecotubes, injection angels etc as well as to verify the improvements after the system is installed. A major step in the US market was taken in 2004, when 4 Ecotubes were installed in a 50 MW biomass fired boiler in Maine through a successful partnership between ECOMB AB and Synterprise LLC of Chattanooga, TN. The combustion process improvements in this unit – WITH PURE AIR injected via the Ecotubes – can be summarized as; ? over 95% reduction of CO ? up to 40% reduction of Nox ? over 1% increased boiler efficiency ? significant reduction of Station Service Power ? minimum 10% reduction of fly-ash (not verified yet) ? reduced erosion in the SH and convection pass (not verified yet).