Heat Balance Of Marine Diesel Engine Drawing

7,177 lb/hr

Waste Heat Boiler

Boiler

1,109 kW

Feedwaler

T-1500 Gas Turbine

Fig. 26-26 Heat and Material Balance for 1,100 kW Gas Turbine-Driven Electric Cogeneration System. Source: Cogen Designs, Inc.

operation on natural gas. The full load simple-cycle heat rate for this unit is 10,400 Btu/kWh (10,972 kJ/kWh) on an LHV basis. The unit features a five-stage turbine, as well as an eighteen-stage compressor that achieves a pressure ratio of 13.3:1. The exhaust mass flow is 699 lbm/s (317 kg/s) at a temperature of 941°F (505°C).The generator is driven at a shaft speed of 3,600 rpm and produces a nominal output of 137 MVA at 60 Hz with a PF of 0.8, a rated voltage of 13.8 kV, and a rated current of 5,732 amps. The gas turbine module weighs 242,550 lbm (110,000 kg) with dimensions of 25 ft (7.5 m) long by 12 ft (3.5 m) wide by 13 ft (4 m) high. The generator exciter module weighs 277,830 lbm (126,000 kg) with dimensions of 26 ft (8 m) long by 11 ft (3 m) wide by 12 ft (3.5 m)

Heat Balance Diagram
Fig. 26-27 Preliminary Heat Balance Diagram for Gas Turbine Cogeneration System Applied at Industrial Site. Source: United States Turbine Corp.

high. All auxiliaries, control system, and electrical equipment are consolidated into one package. The combined weight of the packaged generator set module is 604,000 lbm (274,000 kg).

Figure 26-26 shows a heat and material balance for 1,100 kW gas turbine-driven cogeneration system, on an HHV basis, featuring a single-pressure HRSG applied in a hospital. In this system, all recovered heat is delivered to the hospital's steam loop in the form of 100 psig (7.9 bar) steam. Deaerator steam would be taken from the 100 psig (7.9 bar) line through a PRV. Figure 26-27 shows a preliminary heat balance diagram for a 3,967 kW gas turbine cogeneration system applied at an industrial site. On an LHV basis, 46.56 MMBtu/h (49,121 MJ/h) is supplied to the turbine's combustor at a pressure of 225 psig (16.5 bar) via the fuel gas compressor.

An additional 48 MMBtu/h (50,640 MJ/h) can be introduced through the duct burner for supplementary firing. This raises the exhaust gas temperature from 1,041 to 2,200°F (561 to 1,204°C). With a final stack exhaust temperature of 310°F (154°C), the total steam production comes up to 60,000 lbm/h (27,200 kg/h) at a condition of650 psig/750°F (45.8 bar/ 399°C). Combustion air requirements and actual site conditions that will impact gas turbine performance are also shown.

Steam Injection-Cycle Systems

Steam and water injection (wet injection) are used to reduce NOX emissions in gas turbines. With the use of steam injection in the simple-cycle gas turbine configuration, power output can be increased by as much as 50% and thermal efficiencies of 45% or more (LHV basis) can be achieved. The trade-off is the decrease in the amount of steam available for thermal processes.

For many stationary turbines, some modifications are required for operation with steam injection rates that are equal to more than a few percent of the total air mass flow.

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