Abstract: An improved gas turbine combined cycle system having a diffuser duct between the gas turbine and steam generator. The diffuser duct has boundary layer suction to prevent gas jet separation, thereby reducing pressure loss and improving gas velocity profiles in the duct, while eliminating the need for internal flow controls. The gas turbine combined cycle system can be vertically oriented to reduce the plan area of the system and provide for convenient use of a symmetrical diffuser duct and the use of forced circulation on the water side of the steam generator.

Abstract: A furnace (10) in which pulverized coal is burned in suspension. The coal is introduced along with primary air, tangent to an imaginary circle (42). The auxiliary air is introduced tangent to an imaginary circle (44) directly above the primary air, in a direction of rotation opposite that of the primary air. The auxiliary air is directed tangent to a circle of greater diameter than that of the primary air. There are a plurality of alternating levels within the furnace where primary air (38), and then auxiliary air (40), is introduced.