Cogeneration & Combined Cycles Mechanical Engineering Department ME332 Operation and Management of Power Plants Cogeneration & Combined Cycles Prof. Osama A El Masry

An Ideal Cogeneration Plant (Fig. 9-21) Prof. O. El Masry

Schematic and T-s Diagram for Cogeneration Cycle (Fig. 9-23) Prof. O. El Masry

Combined Cycles The overall thermal efficiency of a power plant can be increased by using binary cycles or combined cycles. A binary cycle is composed of two separate cycles, one at high temperatures (topping cycle) and the other at relatively low temperatures. The most common combined cycle is the gas-steam combined cycle where a gas-turbine cycle operates at the high-temperature range and a steam-turbine cycle at the low-temperature range. Prof. O. El Masry

Mercury-Water Binary Vapor Cycle (Fig. 9-24) Prof. O. El Masry

Combined Cycles The gas-steam combined cycle uses a gas-turbine cycle operating in a high-temperature range and a steam-turbine cycle in a low-temperature range. Steam is heated by the high-temperature exhaust gases leaving the gas turbine. Combined cycles have a higher thermal efficiency than the steam- or gas-turbine cycles operating alone. Prof. O. El Masry

Combined Gas-Steam Power Plant Prof. O. El Masry

(Heat Recovery Steam Generator) HRSG (Heat Recovery Steam Generator)

Types of HRSG 2 bar  20 bar 1 ton/h  10 ton/h up to 180 bar

Configurations of HRHG Evaporator section

Superheater section :

Economizer section : Economizer designs would normally follow along with the evaporator type that is being used and be similar in design to the superheater. The configurations would be similar to the ones shown above for the superheaters

Preparing a flow schematic for the HRSG : Pinch point . Approach point .

Single pressure :