User Guide to SPILL

7. HFSPILL

User Guide MAIN MENU

General introduction

HFSPILL is the HF-specific counterpart of SPILL. It calculates the time-dependent release rate from a pressure vessel filled with HF and water.
The vessel mixture is assumed to be in one of the following two states:
(1) a subcooled (not saturated or superheated) liquid consisting of HF and water
(2) an equilibrium vapour mixture of HF vapour, water vapour and nitrogen.

HFSPILL can prepare link files for HFPLUME or LPOOL, depending on the release scenario.

Range of applications and limitations

HFSPILL should be used as a utility to estimate the time-dependence of the discharge mass flow rate directly from an orifice in a pressurised vessel resulting in a dispersing jet rather than a pool on the ground. It is not suitable for cases where there is pipework between the reservoir and the discharge orifice.

Contrary to SPILL, in HFSPILL heat exchange of the vessel with the ambient atmosphere is not taken into account.

HFSPILL INPUT FILE PARAMETERS

A description of all the input parameters that can occur in a HFSPILL input file will be given.

The HFSPILL input file has the DOS filename 'casename.HLI' where 'casename' is the user-supplied name of the problem.

In the following, actual keywords are given in capitals and in bold. The descriptions of less important parameters or parameters that need not normally be set by the user, are given in a smaller font.

All parameters, except TITLE, occur in blocks preceded by a specific block keyword. For SPILL these block keywords are: RESERVOIR, LIQUID, VAPOUR, PIPE and AMBIENT.

The TITLE keyword does not occur in a parameter block.

TITLE

The title of the current problem to be run with HFSPILL.
At most 50 alphanumeric characters.
Optional, no default.

The RESERVOIR block contains the parameters which describe the reservoir fluid thermodynamic state.

TRES Initial temperature of the reservoir fluid (Degrees C ).
-50 <= TRES <= 150.
Mandatory.

PRES Initial absolute pressure within the reservoir (atm).
0.7 <= PRES <= 20. Mandatory.

PRES must exceed AIRPRESS in the AMBIENT block.

VRES Reservoir volume (m³)
0.1 <= VRES <= 500.
Mandatory.

HFSPILL checks whether the input data is consistent: VRES should be compatible with the user-specified vessel contents at the given TRES and PRES.

The LIQUID block contains data from which HFSPILL determines the vessel equilibrium state when liquid is present. The user has to specify the mass percentage of water in the vessel, the rest of the mixture is assumed to be (anhydrous) hydrogen fluoride acid HF.
The user should either specify a LIQUID or a VAPOUR input block. If there is liquid present in the vessel, the LIQUID input block should be used, otherwise the VAPOUR block. The user should not specify both blocks in one run.

MFH2O Mass percentage water in the reservoir mixture (%).
0 <= MFH2O <= 100.
Mandatory.

MLRES Total reservoir mass (tonnes, 1 tonne = 1000 kg).
0.1 <= MLRES <= 200.
Mandatory.

The VAPOUR block contains data from which HFSPILL determines the vessel equilibrium state when only vapour is present. The user has to specify the mass percentage of water and HF in the vessel, the rest of the mixture is assumed to be nitrogen.
The user should either specify a LIQUID or a VAPOUR input block. If there is liquid present in the vessel, the LIQUID input block should be used, otherwise the VAPOUR block. The user should not specify both blocks in one run.

MFHF Mass percentage HF vapour in the (gaseous) reservoir mixture (%).
0 <= MFHF <= 100.
Mandatory.

MFH2O Mass percentage water vapour in the (gaseous) reservoir mixture (%).
0 <=MFH2O <= 100.
Mandatory.

Note: Total reservoir mass is calculated by HFSPILL. Phase stability is checked by the program.

The PIPE block contains the release pipe/orifice exit-plane conditions.

DEXIT Effective orifice diameter of the discharge pipe (m).
0.001 <= DEXIT <= 0.5.
Mandatory.

DTLINK Time duration step used in HFSPILL/LPOOL link file (s).
0.0 <= DTLINK <= 10⁸
Optional, default is 200 s.

As LPOOL can deal with up to 5 spill data records SPILDATA, it is important to choose a corect value for DTLINK. DTLINK should be chosen in such a way that the SPILDATA records in the LPOOL input file give a good representation of the release history. For DTLINK too large, not enough SPILDATA records will be used, for DTLINK too small the whole release history might not be covered. The user needs to run HFSPILL at least once to be able to find a good value for DTLINK.

CDG Discharge coefficient for vapour only releases (-).
0.0 <=CDG <= 1.0.
Optional, default is 1.0.

SPILL uses discharge coefficients to calculate values for the mass discharge rate, the user might want to change the default values of these coefficients.

CDL Discharge coefficient for liquid or two-phase releases (-).
0.0 <= CDL <1.0.
Optional, default is 0.61.

See remark above.

The AMBIENT block contains one parameter describing the conditions of the ambient atmosphere.

AIRPRESS Ambient air pressure at release height (atm).
0.7 <= AIRPRESS <= 1.1.
Optional, default is 1.0 atm.

AIRPRESS must be less than PRES in the RESERVOIR block.

TRES	Initial temperature of the reservoir fluid (Degrees C ). -50 <= TRES <= 150. Mandatory.
PRES	Initial absolute pressure within the reservoir (atm). 0.7 <= PRES <= 20. Mandatory.
	PRES must exceed AIRPRESS in the AMBIENT block.
VRES	Reservoir volume (m³) 0.1 <= VRES <= 500. Mandatory.
	HFSPILL checks whether the input data is consistent: VRES should be compatible with the user-specified vessel contents at the given TRES and PRES.

MFH2O	Mass percentage water in the reservoir mixture (%). 0 <= MFH2O <= 100. Mandatory.
MLRES	Total reservoir mass (tonnes, 1 tonne = 1000 kg). 0.1 <= MLRES <= 200. Mandatory.

MFHF	Mass percentage HF vapour in the (gaseous) reservoir mixture (%). 0 <= MFHF <= 100. Mandatory.
MFH2O	Mass percentage water vapour in the (gaseous) reservoir mixture (%). 0 <=MFH2O <= 100. Mandatory.
	Note: Total reservoir mass is calculated by HFSPILL. Phase stability is checked by the program.

DEXIT	Effective orifice diameter of the discharge pipe (m). 0.001 <= DEXIT <= 0.5. Mandatory.
DTLINK	Time duration step used in HFSPILL/LPOOL link file (s). 0.0 <= DTLINK <= 10⁸ Optional, default is 200 s.
	As LPOOL can deal with up to 5 spill data records SPILDATA, it is important to choose a corect value for DTLINK. DTLINK should be chosen in such a way that the SPILDATA records in the LPOOL input file give a good representation of the release history. For DTLINK too large, not enough SPILDATA records will be used, for DTLINK too small the whole release history might not be covered. The user needs to run HFSPILL at least once to be able to find a good value for DTLINK.
CDG	Discharge coefficient for vapour only releases (-). 0.0 <=CDG <= 1.0. Optional, default is 1.0.
	SPILL uses discharge coefficients to calculate values for the mass discharge rate, the user might want to change the default values of these coefficients.
CDL	Discharge coefficient for liquid or two-phase releases (-). 0.0 <= CDL <1.0. Optional, default is 0.61.
	See remark above.

AIRPRESS	Ambient air pressure at release height (atm). 0.7 <= AIRPRESS <= 1.1. Optional, default is 1.0 atm.
	AIRPRESS must be less than PRES in the RESERVOIR block.