Calculation of thermal efficiency of a three-circuit steam and gas plant Author: Valery Ochkov ([email protected]), Aung Thu Ya Tun ([email protected]), Moscow Power Engineering Institute (MPEI)
Start > > > > Steam turbine cycle Input data: > > > > > > > > > > > > > >
Functions and procedures The specific enthalpy of the steam entering the turbine HPP: >
(2.1)
The specific enthalpy of steam at outlet of the turbine HPP: >
(2.2)
Specific work of HPP steam turbine: >
(2.3)
The temperature of the steam at the outlet of the HPP turbine: > (2.4) The specific enthalpy of steam at the point 10: > (2.5) >
(2.6)
The balance of the mixing streams at points 9 and 10:
>
(2.7)
The temperature of steam at the inlet to the MPP of the turbine: > (2.8) >
(2.8) > (2.9) > Specific enthalpy of water vapor at the inlet to the MPP of the turbine: >
(2.10)
Specific enthalpy of steam at the outlet of the turbine MPP: >
(2.11)
C : >
(2.12)
The temperature of the steam at the outlet of the MPP of the turbine: > (2.13) The specific enthalpy of steam at point 13: > (2.14) >
(2.15)
Balance when mixing streams at points 12 and 13:
>
(2.16)
The temperature of steam at the inlet to the LPP of the turbine: > (2.17) > (2.18) The specific enthalpy of steam at outlet of the turbine LPP: >
(2.19)
Specific LPP operation of a steam turbine: >
(2.8)
>
(2.20)
The degree of dryness of the steam at the outlet of the turbine LPP: > (2.21) Condensate temperature: > (2.22) Specific enthalpy of condensate: >
(2.23)
The specific enthalpy of the feed water high pressure circuit (internal relative pump efficiency of 75%): > (2.24) > (2.25) > (2.26) >
(2.27)
The specific operation of the pump high-pressure circuit >
(2.28)
Specific enthalpy of feed water of medium pressure circuit (internal relative efficiency of the pump is equal to 75%): > (2.29) >
(2.30)
The specific operation of the pump high-pressure circuit: >
(2.31)
Specific enthalpy of feed water of the low pressure circuit (internal relative efficiency of the pump is equal to 73%): >
(2.8)
>
(2.20)
> (2.32) > (2.33) >
(2.34)
Specific work of the low pressure circuit pump: >
(2.35)
Thermal efficiency of the STP cycle: >
(2.36) Gas turbine cycle Input data: > > > > > > Specific enthalpy of fresh air >
(3.1)
Specific entropy of fresh air >
(3.2)
Specific entropy air at the outlet of the compressor: > Air temperature at the outlet of the compressor: > (3.3) The specific enthalpy of the air at the outlet of the compressor: >
(3.4) >
(2.8)
>
(2.20)
> (2.32)
(3.4)
Gas pressure at the inlet to the GT: > Specific entropy of gas at the entrance to the GT: >
(3.5)
Specific enthalpy of gas at the inlet to the GT: >
(3.6)
Gas pressure at the outlet from the gas turbine unit: > Specific entropy of gas at the outlet of GTP: > Gas temperature at the outlet of the GTP: > (3.7) Specific enthalpy of gas at the outlet of GTP: >
(3.8)
Heat supplied in the combustion chamber: >
(3.9)
The specific operation of the gas turbine: >
(3.10)
The specific operation of the compressor: >
(3.11)
Thermal efficiency of the GTP cycle:
>
(3.12)
Combined (binary) cycle >
(2.8)
>
(2.20)
> (2.32)
(3.4)
Specific enthalpy of gas at the outlet of the recovery boiler: > Ratio of gas and steam mass flow of a high-pressure
>
(4.1) Ratio of gas and steam mass flow of a medium-pressure
>
(4.2) Ratio of gas and steam mass flow of a low-pressure
>
(4.3) Ratio of gas and steam mass flow
> (4.4) Specific heat supplied to the combustion chamber: >
(4.5)
Specific work of the gas turbine cycle >
(4.6)
Specific work of the steam turbine cycle >
(4.7)
Hence the thermal efficiency of the combined (binary) cycle is higher than separate steam or gas turbine cycles:
>
(4.8)