Design documentation development and manufacturing of low-NOX 19 MW burners for high-calorific (retort) gas of oil shale processing firing with flue gas recirculation injection into secondary air. Oil shale boiler TP-101 reconstruction for combined firing of oil shale and retort gas. There were additionally installed six gas burners and system of flue gas recirculation. Gas proportion by heat rate – 40% of boiler’s load. ENTEH was responsible for complete design project, supply of gas burners, installation of flue gas recirculation system, commissioning and start-up operations. Customer - EESTI ENERGIA.