Component 40: Gas Turbine (Macro)

In This Topic

Component 40: Gas turbine (Macro, simple characteristic lines or specification matrices )

Specifications

Line connections
1	Air intake
2	Waste gas outlet
3	Fuel inlet
4	Injection water/steam inlet
5	Generator power

General User Input Values Characteristic Lines Physics Used Displays Example

General

Component 40 does not calculate the individual components of a gas turbine, but instead uses the characteristic fields supplied by the manufacturer of the system. This ensures that the simulation is done exclusively with the data of the manufacturer, so that clear statements can be made for the guarantee conditions.

It is possible to use specification matrices instead of characteristic fields. The switchover is affected via a flag FOFFD.

The composition of the flue gas can be entered, if it is known. If no manufacturer data is available, the program then calculates a composition based on a combustion calculation.

In order to check the energy balance, a control area is set around the gas turbine. An error message is given, if the deviation is more than 5%. The calorific value of the fuel must be determined empirically or the fuel mass flow rate must be adapted.

The check of the energy balance is a helpful tool to ensure that the safety margins are not too large.

Note: For many gas turbines, pre-configured macros are available in the gas turbine macro-library. These macros can be integrated directly in the model. These macros normally do not use component 40, but instead are made up of individual components.

Because for this component the relevant values are not specified by physical laws but via characteristic lines, breaches of the energy balance can occur depending on the specification of the characteristic line. Depending on the severity of the breach, these are reported as a warning or as a fault.

The alarm threshold was fixed (warning threshold 2.5%, error threshold 5%). The fault threshold can be entered by the user as the set value TOL (Release 8). A warning occurs at half the value of the fault threshold.

The NOX concentration at the outlet can be specified via a kernel expression. This is controlled via the flag FNOCON.

In the case of a value of 0, the specification value NOCON is used,
In the case of a value of 1, the kernel expression ENOCON is used for the calculation.

The flag FCON controls whether the concentration is given as a mole fraction or as a standardized mass fraction (mg/Nm³).

Specification of voltage, frequency and type of current in the component:

There is the option of specifying the voltage (VOLT), frequency (FREQ) and type of current (NPHAS) as the default value in the component.

The flags FVOLT and FFREQ are used to set whether the specification is to be made by the new specification values VOLT and FREQ respectively (0) or externally as a measured values on the electrical line (-1).

User Input Values

LOAD	Load factor (1.0 = full load)
FOFFD	Flag for definition of off-design behaviour Like in Parent Profile (Sub profile option only) Expression =0: By char lines =1: By matrices
FVOLT	Flag for the method for specification of voltage Like in Parent Profile (Sub profile option only) Expression =0: Defined by specification value VOLT =-1: Voltage given externally on electrical outlet
VOLT	Voltage (on electric lines)
FFREQ	Flag for the method for specification of frequency Like in Parent Profile (Sub profile option only) Expression =0: Use specification value FREQ =-1: Frequency given externally on electrical outlet
FREQ	Generator frequency
NPHAS	Type of current Like in Parent Profile (Sub profile option only) Expression =0: Direct current =1: One-phase alternating =3: Three-phase alternating
FANA	Flag for the source of flue gas composition Like in Parent Profile (Sub profile option only) Expression =0: Flue gas components are calculated (i.e. the waste gas composition is calculated with the help of a combustion calculation from the known mass flow rates of air, water and fuel.) =1: Input of flue gas components (Input with component 33(pastille), if the manufacturer provides the composition)
TOL	Tolerance in energy balance
FADAPT	Flag for adaptation polynomial ADAPT / adaptation function EADAPT Like in Parent Profile (Sub profile option only) Expression =0: Not used and not evaluated =1: Correction flue gas temperature [T2 = char line factor * polynomial] =2: Correction flue gas flow [M2 = char line factor * polynomial] =3: Correction fuel flow [M3 = char line factor * polynomial] =4: Correction [M4 = char line factor * polynomial] =5: Correction [Q5= char line factor * polynomial] =6: Replacement char line [T2 = polynomial] =7: Replacement char line[M2 = polynomial] =8: Replacement char line[M3 = polynomial] =9: Replacement char line[M4 = polynomial] =10: Replacement char line[Q5 = polynomial] =1000: Not used but ADAPT evaluated as RADAPT (Reduction of the computing time) = -1: Correction flue gas temperature [T2 = char line factor * adaptation function] = -2: Correction flue gas flow [M2 = char line factor * adaptation function] = -3: Correction fuel flow [M3 = char line factor * adaptation function] = -4: Correction [M4 = char line factor * adaptation function] = -5: Correction [Q5= char line factor * adaptation function] = -6: Replacement char line [T2 = adaptation function] = -7: Replacement char line[M2 = adaptation function] = -8: Replacement char line[M3 = adaptation function] = -9: Replacement char line[M4 = adaptation function] = -10: Replacement char line[Q5 = adaptation function] = -1000: Not used but EADAPT evaluated as RADAPT (Reduction of the computing time)
EADAPT	Adaption function: function evalexpr:REAL; begin evalexpr:=1.0; end;
FCON	Flag for interpreting NOCON: Like in Parent Profile (Sub profile option only) Expression =1: NOCON is the mole fraction (related to reference O2 concentration) =2: NOCON is normalized mass ratio at reference O2 concentration The difference between FCON=1 and FCON=2 is the fact that for FCON=2 you have to specify some kind of "density" for the pollutant fraction, i.e. mass of pollutant per volume of flue gas (therefore the dimension mg/Nm³). If you divide this density by the density of the pure pollutant, you get the corresponding mole fraction. In the implementation, the case FCON=2 is traced back to FCON=1, using a constant density of 2.05204 kg/m³ for NOx (independent of NOSPL).
FNOCON	Flag for specifying Calculation of NOx concentration Like in Parent Profile (Sub profile option only) Expression =0: By specification value NOCON =1: By function ENOCON
NOCON	NOx concentration in the exhaust gas (wet molar fraction at reference oxygen concentration) Hint: To reproduce the value NOCON in the exhaust gas pipe, you have to change the reference oxygen concentration in the model settings to the mole fraction of oxygen in the exhaust gas pipe and change the properties of the value cross to display mole fraction. NOCON will be the sum of XNO and XNO2. As this calculation is performed iteratively, the value is reached only approximately.
ENOCON	Function for concentration of NOx in exhaust gas function evalexpr:REAL; // result must be in m³/m³ if FCON=1, in mg/Nm³ if FCON=2 begin evalexpr:=0.0; end;
NOSPL	Distribution of NO and NO2 in NOX. NO-Split (NO/(NO + NO2) (molar fraction))
CALT	Barometric altitude factor (e.g. used for M2 = M20*CALT, see below)

Generally, all inputs that are visible are required. But, often default values are provided.

For more information on colour of the input fields and their descriptions see Edit Component\Specification values

For more information on design vs. off-design and nominal values see General\Accept Nominal values

Characteristic lines

Characteristic line 1,2,3,4: T2-characteristic line: T2=f(T1,Last)

     X-axis          1         T1                               1^st point
                        2          T1                               2^nd point
                        .
                      N         T1                               last point

     Y-axis         1          T2(Load)                     1^st point
                        2          T2(Load)                     2^nd point
                        .
                        N         T2(Load)                     last point

Characteristic line 5,6,7,8: M2-characteristic line connection: M2=f(T1,Last)

     X-axis         1         T1                               1^st point
                        2          T1                               2^nd point
                        .
                      N         T1                               last point

     Y-axis         1          M2(Load)                    1^st point
                        2          M2(Load)                    2^nd point
                        .
                        N         M2(Load)                    last point

Characteristic line 9,10,11,12: M3-characteristic line connection: M3=f(T1,Last)

     X-axis         1         T1                               1^st point
                        2          T1                               2^nd point
                        .
                      N         T1                               last point

     Y-axis          1          M3(Load)                    1^st point
                        2          M3(Load)                    2^nd point
                        .
                        N         M3(Load)                    last point

Characteristic line 13,14,15,16: M4-characteristic connection: M4=f(T1,Last)

     X-axis         1         T1                               1^st point
                        2          T1                               2^nd point
                        .
                      N         T1                               last point

     Y-axis         1          M4(Load)                    1^st. point
                        2          M4(Load)                    2^nd point
                        .
                        N         M4(Load)                    last point

Characteristic line 17,18,19,20: Q5-characteristic line connection: Q5=f(T1,Last)

     X-axis         1         T1                               1^st point
                        2          T1                               2^nd point
                        .
                      N         T1                               last point

     Y-axis        1          M5(Load)                    1^st point
                        2          M5(Load)                    2^nd point
                        .
                        N         M5(Load)                    last point

Specification matrices

X: T1 : Air intake; Y: Load

Matrix 1 MXT2 : (Waste gas temperature) T2= f (T1, Load)

Matrix 2 MXM2 : (Waste gas mass flow) M2= f (T1, Load)

Matrix 3 MXM3 : (Fuel mass flow) M3= f (T1, Load)

Matrix 4 MXM4 : (Injection water/steam inlet) M4= f (T1, Load)

Matrix 5 MXQ5: (Generator power) Q5 = f (T1, Load)

Physics used

Equations

All cases

Default by initial and boundary values:

- all pressures

- composition of mass flow 1,3,4

- composition of mass flow 2 is calculated

- if FANA = 0 from the balance of the mass flows 1,3,4

- if FANA = 1 input as boundary value

M20 from waste gas mass flow characteristic line

M2 = M20*CALT

M30 from fuel characteristic line

M3 = M30*CALT

M40 from injection mass flow characteristic line

M4 = M40*CALT

M1 = M2 - M3 - M4

T2 from waste gas temperature characteristic line

H2 = f(T2)

T1 = T0

H1 = f(T1)

Q50 from generator power characteristic line

Q5 = Q50*CALT

Balance check:

QGIV= M1*H1 + M3*(H3+NCV3) + M4*(H4-HVAP),

whereby HVAP=2500.0

QDEL = M5*H5 + M2*H2

Qdif= |QGIV-QDEL| / QGIV

if 0.050 < Qdif, then error message

if 0.025 < Qdif <= 0.050, then warning

if Qdif <= 0.025, then balance Ok

Component Displays

Display Option 1

Example

Click here >> Component 40 Demo << to load an example.