Component 5: Steam Generator

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Component 5: Steam Generator (Boiler)

Specifications

Line connections
1	Feed water inlet
2	Steam (steam outlet (HD)
3	Intermediate super heater (IH) inlet
4	Intermediate super heater (IH) outlet
5	Heat provided by a connected component 21
6	High pressure injection (without throttling)
7	Intermediate super heater injection (without throttling)
8	Drain / Blow down

General User Input Values Characteristic Lines Physics Used Displays Example

General

Component 5 helps in a balanced modeling of the water/steam side of a steam generator. It is used when a detailed modeling of the individual heating surfaces can be avoided. For a detailed modeling the components 26 or 61 (Economizer/Evaporator/Superheater) can be used in simple cases. If a radiation exchange is to be taken into account with the other heating surfaces, the detailed boiler components must be used from the EbsBoiler module (components 88 to 91), which also map the boiler geometry.

Component 5 can be used be together with the component 21 (combustion chamber), in order also to map the flue gas side. The coupling takes place via a controller with the help of logical outlets: Component 5 provides at line 5 the heat requirement by the water/steam side, while the component 21 provides at line 3 the heat generated by the combustion.

Component 5 can model the main-steam production section as well as an intermediate super heating section, often used to represent a reheater. For both the strands an injection can be taken into account. For the high-pressure injection the injection quantity is entered relative to the feed water quantity in the specification value M6M1. For the super heater injection, on the other hand, a characteristic line CM7M1 is used, in which the super heater injection quantity can be entered relative to the feed water quantity. Alternatively, the injection quantities can also be specified externally, e.g. with a measurement point (Component 46) or a start value (Component 33).

Even the drain can be specified selectively via a specification value (relative to the feed water quantity) or externally.

CAUTION:

While modeling injections and drains care must be taken to use these with the remaining circulation, as otherwise a violation of the mass balance can occur.

The values T2, P2 and T4 could only be specified either all together by means of specification values or all from outside. There are new options for FSPEC (as of Release 10) to switch one or two of these parameters, too.

When setting the main steam pressure in the component the design pressure is entered as the specification value P2N and the off-design pressure is entered in the slide-pressure characteristic line CP2.

The main steam temperature and the super heater temperature can similarly be set either in the component or can be specified from outside. When setting in the component, the corresponding value, however, is used in all the load cases.

User Input Values

P2N	Main steam pressure (nominal)
T2	Main steam temperature
T4	Intermediate super heater (reheat) outlet temperature
DP12N	HP-pressure loss (between ports 1 and 2) (nominal)
DP34N	Intermediate super heater pressure loss (between ports 3 and 4) (nominal)
M6M1	Mass flow ratio of HP injection (always relative to M1)
M8M1	Mass flow ratio of drain relative to M1 (in design case relative to M1, in off-design relative to M1N) If you set the specification value M8M1 to -999, the program expects a definition of the drain mass flow given by component 1 (boundary value), component 33 (start value) or component 46 (control measurement point).
DPECON	Economizer pressure drop (nominal) This value is used to determine the pressure level of the drain.
FSPEC	Flag for specifications Like in Parent Profile (Sub profile option only) Expression = 0: T2 as specified, P2 via P2N, T4 as specified = 1: T2,P2,T4 via component 33 =2: P2 given from outside - T2, T4 internally =3: T2 given from outside - P2, T4 internally =4: T4 given from outside - P2, T2 internally =5: P2, T2 given from outside - T4 internally =6: P2, T4 given from outside - T2 internally =7: T2, T4 given from outside - P2 internally
FVOL	Part-load pressure drop (reheat only) Like in Parent Profile (Sub profile option only) Expression =0: Calculated from mass (approximation for incompressible fluids) =1: depending on mass and volume flow =2: Constant (equal nominal value) =3: Read from char line CDP34
FMODE	Flag for calculation mode =0: GLOBAL =1: Local off-design = -1: Local design
FINJ	Handling of spray and blow down flows Like in Parent Profile (Sub profile option only) Expression =0: M6, M7 and M8 given by internal specification =1: M6, M7 and M8 given from outside
M1N	Feed water mass flow (nominal)
V1N	Specific volume at feed water inlet
M3N	Mass flow intermediate super heater (nominal)
V3N	Specific volume at intermediate super heater inlet

The identification values marked in blue are reference values for off-design mode. These values are referred to for the actual off-design values used in the equations respectively. If these identification values are stream data, then these values are often taken from attached pipes or calculated values.

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 lines CPD12, CPD34: The default characteristic lines have a constant value of 1.0. A calculation based on physical laws should be more accurate than a default characteristic curve in most cases. In particular, a dependence on the volume flow cannot be taken into account at all in the characteristic line. And to regard steam as an incompressible fluid is probably a rather rough approximation.

Characteristic 1 CP2: HP-sliding pressure-characteristic P2/P2N = f(M1/M1N)

     X-Axis     1        M1/M1N                 1^st point
                  2        M1/M1N                 2^nd point
                    .
                  N        M1/M1N                 last point

     Y-Axis     1        P2/P2N                     1^st point
                    2        P2/P2N                    2^nd point
                    .
                    N        P2/P2N                    last point

Characteristic 2 CDP12: HP-pressure loss DP12/DP12N = f(M1/M1N)

     X-Axis   1        M1/M1N                  1^st point
                    2        M1/M1N                 2^nd point
                    .
                    N        M1/M1N                 last point

     Y-Axis     1         DP12/DP12N          1^st point
                    2         DP12/DP12N         2^nd point
                    .
                    N        DP12/DP12N          last point

Characteristic 3 CDP34: -Reheat pressure loss DP34/DP34N= f(M3/M3N)

X-Axis        1        M3/M3N                 1. Point
                    2        M3/M3N                 2. Point
                    .
                    N        M3/M3N                last Point

Y-Axis         1         DP34/DP34N         1. Point
                    2         DP34/DP34N         2. Point
                    .
                    N        DP34/DP34N         last Point

Characteristic 4 CM7M1: IH-injection M7/M1 = f(M1/M1N)

     X-Axis    1        M1/M1N                  1^st point
                    2        M1/M1N                 2^nd point
                    .
                    N        M1/M1N                 last point

     Y-Axis    1         M7/M1                   1^st point
                    2         M7/M1                   2^nd point
                    .
                    N        M7/M1                    last point

Physics Used

Equations

All cases

M1R = M1/M1N

(if GLOBAL = nominal load, then M1R= 1.0)

If FSPEC=0, 3, 4 or 7:

P2 = f(M1R) * P2N (from the characteristic)

otherwise P2 is given from outside

If FSPEC=0, 2, 4 or 6:

H2 = f(P2, T2)

otherwise H2 is given from outside

M2 = M1 + M6 - M8

Q2 = M2 * H2

M4 = M3 + M7

M3R = M3/M3N

If FVOL = 0, then F = (M3R**2)

If FVOL = 1, then F = (M3R**2 *(V3/V3N)

(If GLOBAL= nominal load, then F = 1.0)

DP34 = DP34N * F

P4 = P3 - DP34

If FSPEC=0, 2, 3 or 5:

H4 = f(P4,T4)

otherwise H4 is given from outside

Q4 = M4 * H4

H5 = (M2*Q2 + M4*H4 - M1*H1 - M3*H3 - M6*H6 - M7*H7)/M5

If FINJ=0:

M6 = M6M1 * M1

(M7/M2) = f(M1R) (from characteristic)

M7 = M1*(M7/M1)

M8 = M1N*M8M1

DPHP = f(M1R) * DP12N

(from characteristics)

P1 = P2 + DPHP

P8 = P1 - DPECON * M1R*M1R

H8 = Hs(P8)

Results

Relative mass flow feed water	M1/M1N
Relative mass flow reheat	M3/M3N
Relative live steam pressure	P2/P2N
Relative live steam pressure drop	DP12/DP12N
Relative reheat steam pressure drop	DP34/DP34N

Component Displays

Display Option 1

Display Option 2

Example

Click here >> Component 5 Demo << to load an example.