EBSILON®Professional Online Documentation
The handling of streams of the types
is unified, so that the same substances can be present in each of these streams.
With these stream types also solid (e.g. ash, soot) and liquid substances (e.g. liquid water, liquid NH3, liquid CO2) may also be present.
For the solid fractions, you need to to specify an elementary analysis, so that they are handled correctly in a combustion calculation.
Solids are the following substances: C, H, O, N, S, CL, ASH, LIME, CA, H2OB, ASHG, MG, CACO3, CAO, CASO4, MGCO3 and MGO. The solids are specified/displayed as a partial mass balance, and the remaining substances (if applicable without H2O) are scaled to 100% as a mixture (as mass or mole composition).
Thus, different fuels of these stream types can be mixed, whereby different fuels can be supplied to a combustion chamber in one connection. For this purpose, components 60 (general merging) and 28 (collecting container) can be used.
It must be noted that the reference point for enthalpy in this stream types is different from the one in the water/steam table. In the air/flue gas table, the zero point of enthalpy is fixed at 0°C for gaseous substances (i.e. also for gaseous water). If water is present in the liquid phase in an air/flue gas pipe, then its enthalpy is reduced by the enthalpy of evaporation (2500 kJ/kg). For this reason, negative enthalpy values can also appear in the air and flue gas lines at positive temperatures.
Al these classical fluid types can be used as fuel input for the combustion chamber components.
The following 83 substances are available, solids are marked in colour:
See here for more details of the usable water tables.
The phase equilibrium of water is calculated more precisely since Release 15 Patch 4, both for the liquid/gas transition and for the solid/gas and solid/liquid transitions. For the transition to the solid phase, the previous freezing point of -0.000001°C is retained for pressures below 1.352 bar, where the actual freezing point is above this temperature. The reason for this is to avoid changes in results when T=0°C is specified, as this is generally used in auxiliary designs in which H2O is desired in the liquid phase. As 0°C is also the default reference temperature for the exergy, it should be avoided that the reference point is in the ice phase.
Thanks to the more precise calculation, two-phase states can now also be treated for almost pure water (> 99.999%). Since the pressure dependence is taken into account for the enthalpy at the freezing point, there is also a slight pressure dependence for the enthalpy of liquid water above the freezing point.
The entry ”Composition defined by” allows to switch between different types of composition (proportions related to):
All these options can of course also be used when displaying compositions in value crosses and for calls in EbsScript and EbsOpen.
The ”Sum” always indicates the sum of the compositions specified in the composition field. Note that this value has to be ”1” when you leave the dialog, else you will get a calculation error.
The value fields ”Total Water Fraction” and ”Total Ash Fraction” always indicate the total fraction of water or ash, respectively, in the flow consisting of elementary coal, water and ash. Therefore, these values do not change if you switch from ”Raw” to ”WAF”, ”WF” or ”AF”. In the ”Raw” mode, neither the ”Total Water Fraction” nor the ”Total Ash Fraction” are editable. In ”WAF” and ”WF” modes, the ”Total Water Fraction” is editable, in ”WAF” and ”AF” modes, the ”Total Ash Fraction” is editable.
In the composition list, the substances are listed according to the composition definition (”Raw”, ”WAF”, ”WF” or ”AF”), except ”Ash” and ”Chemical bound water (H20B)”.
In ”RAW” mode, all entries are total fractions. The sum of all entries must be one.
In the ”WAF” mode, the entries ”Ash” and ”Chemical bound water (H20B)” are total fractions and identical to the corresponding entries in the info field. All other entries are relative to the water and ash free fraction of the input medium. The sum of all entries except ”Ash” and ”Chemical bound water (H20B)” must be 1.
In the ”WF” mode, only the entry ”Chemical bound water (H20B)” is a total fraction and identical to the entry ”Total Water Fraction” in the info field. All other entries are relative to the water-free fraction of the input medium. The sum of all entries except ”Chemical bound water (H20B)” must be 1.
In the ”AF” mode, only the entry ”Ash” is a total fraction and identical to the entry ”Ash” in the info field. All other entries are relative to the ash-free fraction of the input medium. The sum of all entries except ”Ash” must be 1.
Only the gaseous components were considered for the calculation of the specific volume (and thus also the density) of gases (air, flue gas, gas, crude gas), because the fraction of the liquid
and solid components to the specific volume is generally negligible due to the higher density.
Generally the specific volume of these components cannot be calculated because usually only the elementary composition or the general specification “ash“ is specified for this.
The option to specify a density for this fraction (liquid and solid parts) in the specification value “Density for fraction defined by elementary analysis“ (RHOELEM) has been created.
Up to Release 10, the density specification (specification value RHO) was only used for oil. For standardization purposes, RHOELEM has to be used for oil, too. RHO is no longer available as a specification value.
As result values on the lines there are both RHO (mean density of the total flow) and RHOELEM (Density for fraction defined by elementary analysis).
If a value of 0 is entered for the density (RHOELEM), the fraction of the substances given as elementary analysis will be neglected when determining the specific volume.
In the case of the non-gaseous components the chemical composition of which is known, the specific volume is determined from the corresponding material data. This applies to liquid
H2O, NH3, and CO2, for which libraries are integrated in Ebsilon, as well as the new substances for the direct desulfurization, for which the following constants are used:
Their data has been taken from a publication of the National Institute of Standards and Technologies (NIST) (http://webbook.nist.gov/chemistry/form-ser.html).
All available functions - Formulation Gas Table): see Material-Properties Calculator ---> Function/Property Call
The following functions are available in the validity range of -30 to 2000 °C and from 0.01 to 30 bar:
The Gas Table Formulation integrated in EBSILON®Professional contains i.a. the following functions :
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h = f(p, t) |
(1001) |
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s = f(p, t) |
(1002) |
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t = f(p, h) |
(1003) |
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t = f(p, s) |
(1004) |
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h = f(p, s) |
(1007) |
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s = f(p, h) |
(1008) |
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cp = f(p, h) |
(1012) |
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v = f(p, t) |
(1013) |
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cp = f(p, t) |
(1017) |
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x_sat = f(p, t) |
(1018) |
water-steam saturation concentration |
|
x_H2OL = f (p, t) |
(1019) |
fraction of liquid water |
|
mg |
(1020) |
Mole weight |
|
ncv |
(1021) |
net calorific value |
Two more functions are also available for doing conversions between mass and mol fractions:
|
Mass fractions --> Mol fractions |
(1023) |
|
Mol fractions --> Mass fractions |
(1022) |
Solid and liquid fractions are not included in this conversion. This also applies to the functions for calculation the specific volume.
Because of the expansion of the CO2 library by solid CO2, a function "phase(p,h)” has been implemented that states in the range of which phase you are. It provides the following values: