EPA-450/4-88-024
User's Guide for RVD 2.0 —
A Relief Valve Discharge Screening Model
U.S. Environmental Protection A;---
^'^ic:; 5, Library (5PL-16)
r ) ~.. De-irborn Street, Room 16vO
CL-ctgo, IL 60604
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Technical Support Division
Research Triangle Park, NC 27711
January 1989
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This report has been reviewed by the Office of Air Quality Planning and Standards, US EPA, and has been
approved for publication. Mention of trade names or commercial products is not intended to constitute
endorsement or recommendation for use. Copies of this report are available, for a fee, from the National
Technical Services, 5285 Port Royal Road, Springfield VA 22161
ACKNOWLEDGMENTS
This user's guide is the result of major efforts by Dave Guinnup and Ann Quillian of the Office of Air Quality
Planning and Standards, US EPA. Special thanks go to Gary Briggs, John Irwin, David Layland, Robert
Meroney and Ron Peterson for their advice and assistance in the preparation of this document. Appreciation is
also expressed to Jim Didce, Peter Eckhoff, Jerry Mersch, Ned Meyer, Quang Nguyen, Joe Tikvart and Joe
Touma for their review efforts.
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PREFACE
The RVD (Relief Valve Discharge) model is an IBM-compatible
PC model which provides short-term ambient concentration
estimates for screening pollutant sources emitting denser-than-
air gases through vertical releases. The model is based on
empirical equations derived from wind tunnel tests performed by
Hoot, Meroney, and Peterka (1973).
This document describes the bases, features, applicability,
and limitations of the RVD 2.0 model. Input data needed to
utilize the program are identified, and example runs of the model
in batch and interactive mode are provided to illustrate model
application.
It is likely that the RVD program will undergo changes based
on experience gained with applying the model. Comments on the
model or the user's guide should be addressed to Dr. David
Guinnup, Source Receptor Analysis Branch (MD-14), U.S. EPA,
Research Triangle Park, NC 27711.
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TABLE OF CONTENTS
Preface iii
List of Figures v
List of Symbols and Abbreviations vi
1 Introduction 1
2 Technical Description 5
2.1 Determination of Model
Applicability 5
2.2 Concentration Estimates at
Plume Touchdown 9
2.3 Concentration Estimates at
Downwind Distances After Touchdown 11
2.4 Concentration Estimates at
Specific, Averaging .Times 13
3 Model Implementation 17
3.1 Summary 17
3.2 Input Data Description 18
3.3 Notes on Simulation of Aerosol
Releases . / .21
3.4 Model Output 22
3.5 Example Model Runs 23
3.5.1 Interactive 23
3.5.2 Batch ' 36
References 43
Appendix - Program Code .45
iv
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LIST OF FIGURES
Figure Page
3.1 Example Input Data File 20
3.2 Title Frame for the RVD Model 24
3.3 Source Data Input via Keyboard 25
3.4 Source Data Echoed . 26
3.5 Wind Speed Data Input via Keyboard 27
3.6 Receptor Locations, Meteorological
Data Input via Keyboard and
Print/File Options . . 28
3.7 Output as Scrolled to Screen
(a) Echoed Input Data 29
(b) Dense Gas Effects as a Function of
Meteorological Conditions .30
(c) Matrix of Release Richardson
Numbers 31
(d) Plume Touchdown Concentration
Table 32
(e) Receptor Concentration Table
and Print/File Options 33
3.8 Example Input Data 36
3.9 Interactive Procedure for
Example Run .37
3.10 Hard Copy of Example Run Output 38
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LIST OF SYMBOLS AND ABBREVIATIONS
Symbol Definition
c Ambient Concentration at Receptor (ug/m3)
cf Final Concentration at Desired Averaging Time
(ug/m3)
Cj. 1-Hour Steady-State Concentration (ug/m3)
ct Ambient Concentration at Plume Touchdown (ug/m3)
ct. Concentration at Specifed Averaging Time (ug/m3)
d Stack Diameter (m)
Dh Plume Dilution Ratio at Maximum Plume Rise
f Volume Fraction Liquid in Release
Fr Froude Number (vertical densimetric)
FrH • Froude Number (horizontal densimetric)
g Acceleration of Gravity (m/sec2)
h, Stack Height (m)
Ah Maximum Plume Rise Height Above Stack (m)
M0 Molecular Weight of Contaminant or Pollutant
Mg Equivalent Molecular Weight
M, Molecular Weight of Exhaust Gas
Mh Equivalent Molecular Weight of Plume at Maximum
Plume Rise
p Wind Speed Profile Exponent
Q Exhaust Gas Mass Flow Rate (kg/sec)
Qc Pollutant Emission Rate (kg/sec)
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Ria Release Richardson Number
R, . Velocity Ratio
SG Specific•Gravity
t, Averaging Time (seconds)
td Release Duration (seconds)
T, Ambient Temperature (K)
T, Stack Exit Temperature (K)
Th Temperature at Maximum Plume Rise (K)
u Wind Speed at Stack Height (m/sec)
u18 Wind Speed at 10 meters (m/sec)
u. Friction Velocity (m/sec)
v, Exit Velocity (m/sec)
x Downwind Distance of Receptor (m)
xc Downwind Distance of an Ambient Concentration
of 5000 ppm (m)
xt Downwind Distance of Plume Touchdown (m)
xh Downwind Distance of Maximum Plume Rise (m)
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Vlll
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1 INTRODUCTION
Recently/, there has been an increased interest in the short-
term impact of toxic air pollutants. Sources of these pollutants
include denser-than-air releases (e.g., emissions from pressure
relief valves). Conventional dispersion modeling techniques may
not be able to provide a reasonable estimate of ambient
concentrations resulting from such releases. Several complex
dense-gas release and dispersion models have been developed and
are currently being further refined with support from the EPA and
others. The use of one of these models to simulate every
potential dense gas release scenario is generally impractical.
For many cases/ it is desirable to "screen" a particular dense
gas scenario for potential dense gas effects with a simplified
model prior to expending the time and effort involved in
performing a rigorous simulation.
The RVD (Relief Valve Discharge) model has been designed as
a simplified screening technique which is applicable to elevated
releases of denser-than-air gases. The model will estimate the
plume centerline ground-level ambient concentration at plume
touchdown (which corresponds to the maximum ground-level
concentration) and ground-level concentrations for up to 30
downwind centerline receptor locations. Even though the name of
the model would imply that it is only applicable to pressure
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relief valves, this is not the case. In fact, any vertically-
directed gas release which may potentially exhibit denser-than-
air behavior can be modeled using this technique.
The RVD technique is derived empirically from wind tunnel
tests performed by Hoot, Meroney, and Peterka1 simulating
negatively buoyant plumes from vertically-directed point sources.
One characteristic of such an empirical approach is that it may
not provide reliable concentration estimates for atmospheric
conditions other than those under which the experimental data
were obtained. Since the wind tunnel experiments upon which a
portion of the model is based are typically characterized by
either quiescent conditions or a laminar windflow, model
simulation results' most closely represent.those which might be
encountered under stable atmospheric conditions (E or F stability
class). As a result, concentration predictions for unstable or
neutral atmospheric conditions (where atmospheric turbulence may
play a large role in the dilution of a plume) may be
overestimated.
In versions of this model prior to RVD 2.0, the model
multiplied concentration estimates by a factor of 5 prior to
printing them out. This procedure was intended to assure
conservatism of the results. Currently, the model contains no
multiplicative factor, and is therefore an unbiased
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representation of the experimental results from the original work
of Hoot, et al. A comparison of these results to those which
might be obtained under actual atmospheric conditions has never
been realized. To insure that the concentration estimates from
RVD meet the intent for conservatism implicit in a screening
technique, the concentration estimates should be multiplied by a
factor of 2.0 prior to comparing them with significance levels or
health effects thresholds. Given this degree of conservatism, it
is unlikely that the model will underestimate the impact of a
particular release scenario. In this way, a release with a
potentially dangerous impact can be readily identified as the•
subject for more sophisticated modeling efforts.
The. major differences between this version of RVD (2.0) and
previous versions are associated with the - input and output
procedures. Now the capability of storing keyboard-entered data
on a disk file for future use and the ability to incorporate such
stored data directly into an RVD run are included.
A general limitation of the RVD model is that it assumes no
secondary source cloud. That is, RVD would not be applicable to
the evaporation of a pollutant from a liquid spill. In addition,
the plume is assumed to be in a single gaseous phase. Thus, no
liquid entrainment from the release or particle deposition from
the plume is considered. Note however, it is possible that the
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model can be used to simulate aerosol dispersion (see Section
3.3) by providing as input the "equivalent" molecular weight of
the aerosol mixture for the exhaust gas molecular weight, but the
accuracy of such a simulation has not been evaluated. Users are
advised that, in such an application, the velocity check
calculation (described in Section 3.5.1) is not valid and the
printed warning should be ignored.
The RVD model does not attempt to calculate building wake
effects or perform concentration calculations in building cavity
regions. In addition, it does not carry out complex terrain
calculations or crosswind concentration calculations, -and its
results are independent of surface roughness.
The purpose of the remainder of this document is to
familiarize the user with details concerning the features,
applicability, and limitations of RVD and to provide step-by-step
instructions for its use on an IBM-compatible PC.
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2 TECHNICAL DESCRIPTION
The RVD model provides short-term ambient concentration
estimates resulting from vertical dense gas releases. This
section summarizes the technical aspects of the model. If more
detail is needed, the papers cited below should be consulted.1'2
Hoot, T.G., R.N. Meroney, and J.A. Peterka ,1973: Wind
Tunnel Tests of Negatively Buoyant Plumes, EPA-650/3-
74-003, US Environmental Protection Agency,
Research Triangle Park, NC 27711.
Puttock, J.S., D.R. Blackmore, and G.W. Colenbrander,
1982: "Field Experiments on Dense Gas Dispersion,"in
Dense Gas. Dispersion (R.E. Britter and R.F. Griffiths,
ed.), Elsevier Scientific Publishing Comp., New York.
2.1 Determination of Model Applicability
The RVD model is only applicable when the combined physical
properties of the release and the atmosphere (e.g., the molecular
weight, emission rate,- temperature, wind speed), result in "the
emission of a denser-than-air plume. Since it is not always a
straightforward task to ascertain whether or not a denser-than-
air plume will result from a given hypothetical scenario, the
model performs this assessment for the user. To determine
whether a particular release results in a denser-than-air plume,.
two successive tests are performed by the program. The first
test checks for the dominance of dense gas effects at the point
of release to the atmosphere, while 'the second test checks for
the importance of dense gas effects at the point of maximum plume
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rise (i.e., the top of the plume).
In the first test, the release Richardson number, Ri0, is
calculated using equation (1). The value is calculated for each
atmospheric stability class and wind speed combination being
considered in the analysis.
Rl. » Ig (po/p. - 1) Q]/[u d P0 UM» (u./ulo)2] (1)
where g is the acceleration of gravity (» 9.8 m/sec*), PB is the
plume density (kg/m3), p, is the ambient density (kg/mj), Q is
the exhaust gas mass flow rate (kg/sec), u is the wind velocity
at the top of the stack (m/sec), d is the stack diameter (m),
ulg is the wind velocity at 10m above the ground, and u./uie is the
ratio of friction velocity (m/sec) to the wind speed at 10m
(m/sec) . In this version of RVD, this ratio is assumed to equal
0.06 for all atmospheric stability classes. The value of u is
calculated via the equation:
u - u18(h,/10)p (2)
where h, is the stack height, (m) and p is the wind speed profile
exponent, which varies as a function of atmospheric stability
(see Section 3.2).
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If the value of Ri0 for a particular wind speed/stability
combination is greater than 30, then the plume is considered to
behave as a dense gas at the release point under those
conditions5, and the program continues to the next test. If the
value is less than or equal to 30, then the plume is considered
to be non-dense under those conditions, and no further
calculations are made. Conventional dispersion models for
neutrally-buoyant plumes are applicable for such cases.
Once the first test is passed by a particular release
scenario/ the second test is performed to assess the importance
of atmospheric dilution of the plume resulting from jet
entrainment effects during the rise of the plume to its maximum
height. In this test, the fractional density.ratio, 6, (i.e., the
ratio of the difference between the plume and ambient air density
to the density of the ambient air) is calculated at the top of
the plume. First, the height of the plume at maximum plume rise
is calculated as the minimum of that which would occur in either
a laminar wind or a windless (quiescent) atmosphere. In a
laminar wind/ the height from to the top of the stack to the
middle of the plume at its point of maximum rise, Ah, is:
Ah - 1.32 V3 SG1'3 Fr2'3 d (3)
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where R, is the ratio of the release velocity to the wind
velocity at stack height, SG is the specific gravity of the
exiting plume, and Fr is the vertical densimetric Froude number,
defined by:
Fr - v,/[gd(l - P./P.)]1'2 (4)
In a quiescent atmosphere, Ah is:
Ah * 2.96 Fr d (5)
The lesser of the two calculated values of. A h is used to
estimate the plume dilution ratio at maximum plume rise, Dh, via
the following equation:
Dh - 5.67 X 1CT2 (udVQ) (Ah/d)1'" (M./T.) (6) .
where M, is the molecular weight of the exhaust gas and T. is the
ambient temperature. The equivalent molecular weight of the
plume at the maximum plume rise, M,,, and the temperature at that
point, Th/ are then calculated using mass and energy conservation
equations:
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Mh = [M, + 28.96(Dh - 1)] / Dh (7)
Th - T. - (M./MJ (T, - T.) / Dh (8)
where T, is the stack exit temperature (°K) . The fractional
density ratio at maximum plume rise,
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ct = 6.0 X 109 (Qc/u) [(2Ah + hs)/r2'0 (10)
where Qc is the pollutant emission rate (kg/sec) an,. hs is the
stack height (m).
RVD versions prior to 2.0 included a multiplicative "safety"
factor of 5 which was used to adjust the ambient concentration
predictions to insure conservative results (i.e., to guarantee
that output concentrations were not underestimated). This safety
factor does not appear in version 2.0, and thus the model
predictions are now consistent with the original Hoot, et al.,
correlations. As such, the model predictions should be most
accurate for release scenarios similar to the original wind
tunnel experimental conditions, that is, under stable atmospheric"
conditions with low wind speeds and relatively low surface
roughness. Due to the relatively small database available for
evaluation of this model's performance, however, current guidance
requires that when using this model in a regulatory situation as
a screening tool, output concentrations should be multiplied (by
the user) by a factor of 2 to avoid underestimation, especially
when simulating very stable atmospheric conditions and short (one
hour or less) averaging times. As further model development and
evaluation continue, this guidance will be updated.
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In addition to providing estimates of ambient concentrations
at plume touchdown, the model also estimates the downwind
distance from the source where touchdown occurs. This distance
(as shown in equations .(11) and (12)) is dependent upon the
maximum plume rise, the ratio of release velocity to wind
velocity, stack height and diameter, and the vertical and
horizontal densimetric Froude numbers, Fr and FrH, respectively:
xt = (d Fr2/RJ +0.56 (d FrH/R,,1/2) Ct (11)
where d = {(Ah/d)3 [(2 + h,Mh)3 -1] }1/2 (12)
.and FrH is defined by:
FrH = u/[gd(Pa/P0 - I)]1'2 (13)
The distance to plume touchdown is used in estimating ground
level concentrations at further downwind distances as described
in the next section.
2.3 Concentration Estimates at Downwind Distances after Touchdown
In addition to observing the trajectory behavior of vertical
dense gas releases, Hoot, Meroney, and Peterka1 studied the dense
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gas plume after touchdown. Upon touchdown, the dense gas plume
underwent a .lateral spreading with crosswind concentration
profiles remaining rather flat (the so-called "top hat"
concentration profile). The subsequent downwind decay of
centerline ambient concentrations at ground level was observed to
follow a power law function with an exponent of -0.65. As the
plume approached ambient density, the exponent shifted to -1.7.
This shift, which corresponds to a shift in the dominance of
dense gas effects on dispersion to the dominance of atmospheric
turbulence, was observed to occur at an ambient concentration of
about 5000 ppm.
The RVD model uses these observations to estimate ground-
level centerline concentrations at "different downwind distances
after plume touchdown.. Concentrations within the "dense gas
effects dominated" region are calculated by the equation:
c - ct (x/x,)"-" (14)
where c is the ambient concentration at some user-specified
receptor distance x (m). The distance to the point of transition,
x8/ from the "dense gas effects dominated" regime to the "passive
dispersion dominated" regime is calculated with equation (14) by
substituting the 5000 ppm concentration for c and solving for x.
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The calculation of concentrations at downwind distances beyond xc
is then made using the following equation:
c - ct (xe/xtrfl-"
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averages may be quite realistic.
The RVD model does make concentration adjustments for two
time-oriented factors. The first is a concentration reduction
for releases whose duration is less than the averaging time of
concern. The second is a peak-to-mean correction factor for
averaging times less than 60 minutes. These two independent
adjustments are described in the next two paragraphs..
If the release duration is less than the averaging time of
interest to the user, the RVD model calculates a concentration
reduction based on the ratio of the duration time to the
averaging time:
(16)
where td is the duration of the release (min) , t, .is the
averaging time (min) , cf is the corrected concentration, and cx
is the initial steady-state concentration (which was calcu.ated
via equations (10), (14), or (15). If the release duration is
greater than the averaging time, no concentration reduction is
calculated.
In addition, if the averaging time of interest to the user
is less than 60 minutes, a correction factor is calculated within
the program using the following equation:
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c« = cx (60/t.)°-2 (17)
where cta is the concentration for the desired averaging time.
To insure conservatism in the absence of experimental data on the
subject, no correction factor is calculated for averaging times
greater than 60 minutes.
For screening analyses, all concentrations should b'e
multiplied by a factor of 2 after being printed out by the
program.
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3 MODEL IMPLEMENTATION
3.1 Summary:
The RVD model has been designed for ease of use. It is
written in BASIC programing language and can be run on any IBM-
compatible PC with a BASIC interpreter capability. The model can
be run either interactively or in batch mode. Appendix A
contains a copy of the program code.
To access the program from a hard disk, copy RVD to the hard
disk ("copy a:rvd.* c:"). After the program has been copied,
then type in the command "rvd" at the DOS prompt. This will
begin the interactive session as discussed later (see example
3.4a).
If RVD is to be run from a floppy diskette, invoke the BASIC
interpreter and type in the BASIC command "load A.-RVD.bas".
This will load the program into the current memory. To begin the
program, type in.the command "run".
In section 3.4, two example model runs are presented. One
describes the interactive process and the other describes running
RVD in the batch mode. The source modeled in example 3.4.1 is a
pressurized release from a plugged line. In this example,.
phosgene was emitted for 10 minutes at a rate of 6.26 kg/sec.
The source modeled in example 3.4.1 is a release from a pressure
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relief valve where vinyl chloride was emitted for 3 minutes at
15.12 kg/sec.
3.2 Input Data Description:
The RVD model requires input data on the emission source to
be modeled, meteorological conditions, and receptor locations.
These data can be entered through a data file (batch mode) or by
answering the questions prompted by the computer (interactive
mode). Both are described in the • examples presented in section
3.4. Batch mode is accomplished using an input data file of
ASCII characters. The data are input in free format, allowing
for separation via spaces, commas, or semi-colons. The creation
of a data file can be most easily accomplished by executing RVD
in the interactive mode and responding affirmatively to the
question regarding storage of the input data to a file.
Subsequent runs with similar scenarios may be easily performed by
making editorial changes to the data file (with available
wordprocessing software) and executing RVD in batch mode.
Below is a summary of the input data necessary to run RVD.
Pollutant Emission Rate (kg/sec): This is the mass emission
rate at the source exit point of the pollutant for
which the ambient concentrations are to be estimated.
Exit Velocity (m/sec): The average linear velocity of the
total plume exiting the source.
Stack Diameter (m): The exit diameter of the point source.
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Exit Temperature (K): The temperature of the plume exiting
the source.
Stack Height (m) : The height above ground level of the
elevated point source.
Pollutant Concentration (volume %): The initial
concentration of the pollutant in the plume (determined
from a pollutant mass balance, process calculation, or
stack measurement).
Exhaust Gas Molecular Weight: The average molecular weight
of the entire exiting plume.
Exhaust Gas Mass Flow Rate (kg/sec) : Rate of total mass
flow from the source at the exit point.
Pollutant Molecular Weight: The molecular weight of the
pollutant for which ambient concentrations are to be
estimated.
Release Duration (sec): The time elapsed from beginning to
end of the emission.
Averaging Time (sec) : The time period over which the
concentration estimates are averaged.
Release Pressure (atm): The absolute pressure just inside
the vessel or pipe • acting as the • source of the
emission. This is used to perform a check on the user-
specified velocity. If the emission is routed from a
pressurized vessel through a stack to the atmosphere,
this pressure should be equal to 1 atm. If. the
pressurized source emits directly to the atmosphere,
this pressure should be equal to the actual vessel
pressure.
Number of Wind Speeds: The number of wind speeds (maximum
number is 21) the user desires to-investigate.
Wind Speed (m/sec): The actual wind speeds being considered
in the analysis. These values must be equal to 1.0
m/sec or greater.
Number of Receptors: The number of downwind distances
(maximum is 30) the model will read into the program.
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Receptor Distances (m): The downwind distances at which the
user desires ambient concentration estimates.
Ambient Temperature (K) : Ambient temperatures are to be
input for all six stability classes (A through F). The
default values are 298 K for all stabilities.
Wind Speed Profile Exponents: The wind speed profile
exponents are fixed according to the user specification
of "rural" or "urban". These are consistent with those
used in the EPA's UNAMAP series models (for example,
see reference 5).
An example listing of an input data file is shown on the
right-hand side of Figure 3.1, with variable descriptors on the
left. This file was generated by the example run depicted in
Section 3.5.1 (referred to by the filename "a:phos.dat").
DESCRIPTORS INPUT FILE
Title
Pollutant Emission Rate (kg/sec)
Exit Velocity (m/sec)
Stack Diameter (m)
Exit Temperature (K)
Stack Height (m)
Pollutant Concentration (volume %)
Exhaust Gas Molecular Weight
Exhaust Gas Mass Flow Rate (kg/sec)
Pollutant Molecular Weight
Release Duration (min)
Averaging Time (min)
Release Pressure (atm)
Number of Wind Speeds
Wind Speeds (m/sec)
Number of Receptors
Receptor Distances (m)
Ambient Temperatures (K)
Urban(0) or Rural(1)
Phosgene Release
6.26
22
.3
293
24
100
99
6.26
99
10
15
1.01
5
1 1.5 .2 2.5 3
2
120 210
298 298 298 298 .298 298
0
Figure 3.1: Input Data File
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3.3 Notes on the Simulation of Aerosol Releases
While the extrapolation of the RVD approach to the
simulation of aerosol cloud dispersion has not been explicitly
evaluated, it has been suggested that the model's utility may
extend into this area. Accordingly, appropriate simulation of
such a release requires a slightly modified approach from that
generally described in this guide. The excess density of the
released cloud owing to the presence of liquid droplets may be
simulated by entering an "equivalent molecular weight", or ME,
for the exhaust gas molecular weight, M,. This can be calculated
if the volume fraction of liquid in the release, f, is known:
P0 - [ fpt + (1 - f)pj. - (17)
(18)
Here, PL is the density of the- liquid at vessel conditions
(kg/m3) , and PV is the density of the vapor (kg/m3) at release
temperature and atmospheric pressure. All other input parameters
remain unchanged.
Since the flowrate of contaminant and of total exhaust gas
will be equal in this type of simulation, and since the user has
entered an "equivalent" molecular weight, a consistency check
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routine (described in Section 3.5) in the interactive input
processor will be violated. The way to get around this problem
is to:
(1) Enter source and meteorological data using the
interactive mode of RVD, but enter the same molecular weight for
the exhaust gas as that of the contaminant gas;
(2) Scroll the results to the screen (ignoring them), and
save the input parameters on a disk file;
(3) Edit the disk file (using any convenient ASCII editing
capability) , changing the exhaust gas molecular weight to the
.equivalent molecular weight of the aerosol, and;
(4) Rerun the program using the edited disk file.
In this way, the consistency check is circumvented, and the
parameters appearing in the data file will be those directly used
in the calculations.
3.4 Model Output:
After the calculations have been performed by the model, the
results can be printed either on the terminal screen or the
printer depending on the specification of the user. Results can
be previewed at the screen prior to being sent to the printer,
and this is the recommended mode of operation.
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The results are presented in five separate tables. The
first table presents the input data used in the model run. The
second table provides a quick summary of wind speed and
atmospheric stability class combinations which result in dense
gas behavior. The release Richardson numbers calculated in the
first dense gas test are presented in the third table. The
ground level concentrations estimated by RVD are presented in the
last two tables. The plume touchdown distance and concentration
and the maximum plume rise are presented with each meteorological
condition in the fourth table and the ground level concentration
for each receptor'location is provided in the last table. If the
receptor is located at a downwind distance shorter than the plume
touchdown, the model does not calculate a concentration at that
receptor.
3.5 Example Model Runs:
3.5.1 Interactive Mode
This example illustrates using the RVD model in the
interactive mode. The source being modeled is a pressurized
release of phosgene from a plugged gas line. The source emits
6.26 kg/sec of phosgene over a 10 minute period. The source is
24 meters high, 0.3 meters in diameter, and the line pressure is
1.01 atm, causing the exhaust gas to exit at a velocity of 22
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m/sec. The exit stream is modeled as 100% phosgene at 293 K.
Five wind speeds are examined ranging from 1.0 to 3.0 m/sec.
The ambient temperature is assumed to be 298 K for all stability
classes and the 15-minute ground level concentrations are to be
estimated at two specified downwind distances, 120 and 210
meters.
-. Relief Valve Discharge (RVD 2.0) Screening Program
December 1988
Based on the Hoot, Meroney, and Peterka equations,
this screening technique will estimate for short term
denser than air gas releases: plume rise, plume
touchdown distance, concentration at touchdown, and the
concentrations at up to 30 user-specifled downwind distances.
Notes:
* 'Pollutant' refers to the chemical in whose concentration
you are specifically interested.
* 'Exhaust gas' refers to the entire gas stream which is
being released.
* This version of RVD includes ho 'safety factors' (see manual).
* Concentration estimates are most appropriate for neutral
to stable atmospheric conditions (see manual).
Press any key to continue
Figure 3.2: Title Frame for the RVD Model
After the RVD model has been loaded into the computer's
memory and the run begins, the title frame (Figure 3.2) will
appear on the terminal screen. Press _ny key as directed to
continue to the next frame.
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DATA INPUT VIA KEYBOARD(O) OR FILE(l)? 0
Enter title (with out commas) -- Phosgene Release
Enter Emission Rate of Specific Pollutant (kg/sec)
Enter Exhaust Gas Exit Velocity (m/sec) --22
Enter Stack Diameter (m) -- .3
Enter Exit Gas Temperature (K) -- 293
Enter Stack Height (m) --24
Enter Pollutant Concentration (vol%) -- 100
Enter Pollutant Molecular Weight --99
You oust choose to enter either:
(1) Exhaust Gas Molecular Weight, or
(2) Exhaust Gas Mass Flow Rate.
Choose (1) or (2) -- 1
Enter Exhaust Gas Molecular Weight --99
Enter duration of release (min) --10
Enter desired averaging time (min) --15
Enter pressure inside vessel (ata) -- 1.01
-- 6.26
Figure 3.3: Source Data Input via Keyboard
Figure 3.3 shows the beginning of the data input procedure.
The user is given an option to input the source and
meteorological data by way of a data file or interactively from
the keyboard. In this example, the user does not have a data
file created and wishes to enter the data at the keyboard. The
response "0" begins the data entry procedure. Values for the
source parameters described in Section 3.2 are requested
sequentially as shown in the above figure.
25
-------
#1. Phosgene Release
#2. Pollutant emission rate (kg/sec) - 6.26
#3. Exit gas velocity (m/sec)- 22
#4. Diameter (m) - .3
#5. Exit Temperature (K)- 293
#6. Stack Height (m) - 24
#7. Pollutant Concentration (volume %) - 100
#8. Pollutant Molecular Weight - 99
#9. Exhaust Gas Molecular Weight - 99
#10. Exhaust Gas Mass Flow Rate (kg/sec) - 6.26
#11. Duration of Release (min) - 10
#12. Averaging Time (min) - 15
#13. Release Pressure (atm, absolute) - 1.01
If a value is incorrect, enter its number.
If all values are OK, enter 0. -- 0
Figure 3.4: Source Data Echoed
After the source data have been entered, the program will
echo or reprint these data to the screen, as shown in Figure 3.4.
This allows the user to make any corrections that may be
necessary. Each time a correction is made, the source parameter
listing is reprinted. It should be noted that the program
performs a calculation to assure that the exhaust gas mass flow
rate and molecular weight are consistent with the reported
contaminant flow rate and volume percent, and that the results of
this calculation are reflected in this table.
Once the source data have been correctly entered, the
program performs a quick check to determine whether the input
26
-------
exit velocity is consistent with the exhaust gas mass flow rate.
If there is substantial disagreement, the program will warn the
user of this problem, and allow continuation or termination of
the model run. As was mentioned before, this message can be
ignored if attempts are being made to model an aerosol release,
but if this is not the case, the user may want to check the
accuracy of the input data.
Enter desired number of wind speeds (maximum-21) --5
Enter 5 wind speed(s) (m/sec) separated by s
? 1? 1.5? 2? 2.5? 3
Here are your wind speeds:
1.0000
1.5000
2.0000
2.5000
3.0000
Is everything OK?
-------
Number of downwind receptor distances (max - 30)? 2
Enter 2 specific distances (m) separated by
? 120? 210 .
Receptor distances are:
120.0000
210.0000
Are values correct? (y or n) •- y
Ambient temperatures (degrees K) default to:
(A) 298 (B) 298 (C) 298 (D) 298 (E) 298 (F) 298
Would you like to enter your own? (y or n) -- n
Wind speed profile exponents are for (0) urban
or (1) rural conditions - choose one:0
OUTPUT -- BARD COPY(l) OR SCROLL TO SCREEN(O)? 0
Figure 3.6: Receptor Locations, Meteorological Data Input
via Keyboard and Print/File Options
Figure 3.6 shows the remaining input steps from the number
of receptors through the wind speed profile exponents.- The user
may use the default values provided for temperatures, wind speed
profile exponents, or u./u values; or the user may choose to
enter site-specific values. At the end of the data input
session, the user may choose to have che model output sent to the
printer or scrolled to the screen. Here, the choice is made to
send it to the screen.
28
-------
Figures 3.7(a) through 3.7(e), shown on the following pages,
illustrate how the program output would look if scrolled to the
screen. After the data have been previewed at the terminal, the
program provides the user with the choice of creating a printed
copy of the output. In addition, the input data just entered via
the keyboard may be optionally saved to a disk file for later use
(see Figure 3.7 (e)).
After all data have been entered, a summary of those data
will be printed on the terminal screen as in Figure 3.7(a) below.
Phosgene Release
07-28-1988
Input Data
Pollutant emission rate (kg/sec) - 6.26
Exit gas velocity (m/sec)- 22
Exit Temperature (K)- 293
Stack Height (m) - 24 Diameter (m) - .3
Pollutant Concentration (volume %) - 100
Exhaust Gas Density (kg/m3) - 4.107433
Exhaust Gas Molecular Weight - 99
Exhaust Gas Mass Flow Rate (kg/sec) - 6.26
Pollutant Molecular Weight - 99
Release duration (min) - 10 Av. Time (min) - 15
Release pressure (atm) - 1.01
Wind Speeds (m/sec) - 1.0 1.5 2.0 2.5 3.0
Distances (m) - 120 210
Ambient Temperature (K) - 298 298 298 298 298 298
Urban Wind Speed Profile Exponents
Press any key to continue
Figure 3'. 7 (a): Echoed Input Data
29
-------
When the user presses a key, the input data summary will be
replaced by a table summarizing the results of the initial
testing performed by the model (Figure 7(b), below). The wind
speed/stability combinations which result in dense gas behavior
are indicated by the number "1", and those which do not are
indicated by the number "0". The "2" represents those
conditions, atmospheric . stability class and wind speed
combinations, which do not occur. These combinations are
determined in accordance with the scheme described by Turner4.
Wind
Speed
1.0
1.5
2.0
2.5
3.0
Stability Class
1 2 34 56
111121
111121
111111
111111
111111
(0-Non- Dense Behavior 1-Dense
2-Combinations that cannot
Press any key
Gas Behavior
occur)
to continue
Figure 3.7(b) :
Dense Gas Effects as a Function of Meteorological
Conditions
30
-------
The next table displayed on the terminal screen (Figure
3.7(c), below) displays the release Richardson numbers calculated
by the program for each meterological combination. The matrix is
set up in the same fashion as in Figure 3.7(b). Numbers with
calculated values above 999999.9 are printed as 999999.9.
Release Richardson
Numbers
Stability Class
Wind
Speed
1.0
1.5
2.0
2.5
3.0
1
29980.0
8883.0
3747.5
1918.7
1110.4
2
29980.0
8883.0
3747.5
1918.7
1110.4
Press any key
3
28696.0
8502.5
3587.0
1836.5
1062.8
4
27466.9
8138.4
3433.4
1757.9
1017.3
5
26290.6
7789.8
3286.3
1682.6
973.7
6
26290.6
7789.8
3286.3
1682.6
973.7
to continue
Figure 3.7(c): Release Richardson Number Matrix
The estimated plume touchdown distances and centerline
ground-level concentrations are displayed on the next page in
Figure 3.7(d) for each combination of wind speed and stability
class for which dense gas behavior was predicted to occur. The
concentrations are given in micrograms per cubic meter and in
parts per million (assuming an ambient temperature of 298 K) .
31
-------
For screening purposes, all concentrations should be multiplied
by a factor of 2.0 prior to comparing them with a significance
level or health effects threshold concentration.
Dense Plume Trajectory
Stability Wind Plume Touchdown Touchdown
Class
1
1
1
1 .
1
2
2
2
2
2
3
3
3
3
3
4
4
4
4
4
5
5
5
6
6
6
6
6
Speed Rise Distance
(m/sec)
1.0
1.5
2.0
2.5
3.0
1.0
1.5
2.0
2.5
3.0
1.0
1.5
2.0
2.5
3.0
1.0
1.5
2.0
2.5
3.0
2.0
2.5
3.0
1.0
1.5
2.0
2.5
3.0
(m)
9.9
8.6
.7.8
7.3
6.8
9.9
8.6
7.8
7.3
6.8
9.7
8.5
7.7
7.2
6.7
9.6
8.4
7.6
7.1
6.6
7.5
7.0
6.6
9.4
8.3
7.5
7.0
6.6
(m)
31.91
53.08
76.49
101.81
128.80
31.91
53.08
76.49
101.81
128.80
33.70
56.10
80.89
107.71
136.31
35.59
59.30
85.55
113.96
144.27
90.48
120.58
152.70
37.60
62.69
90.48
120.58
152.70
Concentration
(ug/m3)
0.12520E+08
0.93584E-f07
0.75725E+07
0.64065E+07
0.55780E+07
0.12520E-I-08
0 . 93584E+07
0.75725E-H)7
0.64065E+07
0.55780E-H)7
0.12138E+08
0 . 90642E+07
0.73296E+07
0.61980E+07
0.53942E+07
0.11766E+08
0 . 87784E+07
0 . 70938E+07
0.59956E+07
0.52160E+07
0 . 68650E+07
0.57993E+07
0.50432E+07
0.11405E+08
0.85007E+07
0.68650E+07
0.57993E+07
0.50432E+07
(ppm)
0 . 30984E+04
0.23160E+04
0.1874QE-M>4
0.15855E+04
0.13804E+04
0 . 30984E+04
0 . 23160E+04
0.18740E+04
0.15855E+04
0 . 13804E+04
0.30038E+04
0.22432E+04
0.18139E+04
0.15338E+04
0.13 349 E+04
0.29118E+04
0.21724E+04
0.17555E+04
0 . 14838E+04
0.12908E+04
0.16989E+04
0.14352E+04
0.12481E+04
0.28223E+04
0.21037E+04
0.16989E+04
0.14352E+04
0.12481E+04
Figure 3.7(d): Plume Touchdown Concentration Table
(For screening, all concentrations should be multiplied by 2.0)
32
-------
The final output scrolled to the screen will be the post-
touchdown ground level centerline concentration estimates at the
user specified receptor locations. In this example/ two
receptors were located at 120 and 210 meters downwind,
respectively (see Figure 3.7(e». Note that ground-level
concentration estimates for receptors upwind of the plume
touchdown point are assumed to be equal to zero and are not
presented in these tables. Again, for screening purposes, all
concentrations should be multiplied by 2.0.
.After all receptor concentration estimates have been
displayed, the user is given printing and filing options. In
this example, the user chooses not to create a printed copy of
the results and to save the source .and meteorological input data
entered at the keyboard in the file "a:phos.dat".
Concentrations
Stability
Class
1
1
1
1
1
1
1
1
1
Wind
Speed
(m/sec)
1.0
1.5
2.0
2.5
1.0
1.5
2.0
2.5
3.0
at Specific Receptor Distances
Distance
(o)
120.0
120.0
120.0
120.0
210.0
210.0
210.0
210.0
210.0
Concentration
(ug/m3)
0.13170E+07
0.23386E+07
0.35219E+07
0.48444E+07
0.50866E+06
0.90322E+06
0.13602E+07
0.18710E+07
0.24297E+07
(ppm)
0.3259E+03
0 . 5787E+03
0.8716E+03
0 . 1199E+04
0.1259E+03
0.2235E+03
0.3366E+03
0'.4630E-f03
0.6013E+03
Figure 3.7(e): Receptor Concentration Table
and Print/File Options (For screening, all
concentrations should be multiplied by 2.0)
33
-------
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
5
5
5
5
1.0
1.5
2.0
2.5
1.0
1.5
2.0
2.5
3.0
1.0
1.5
2.0
2.5
1.0
1.5
2.0
2.5
3.0
1.0
1.5
2.0
2.5
1.0
1.5
2.0
2.5
3.0
2.0
2.0
2.5
3.0
120.0
120.0
120.0
120.0
210.0
210.0
210.0
210.0
210.0
120.0
120.0
120.0
120.0
210.0
210.0
210.0
210.0
210.0
120.0
120.0
120.0
120.0
210.0
210.0
210.0
210.0
210.0
120.0
210.0
210.0
210.0
0.13170E+07
0.23386E+07
0.35219E+07
0.48444E+07
0.50866E+06
0.90322E+06
0.13602E+07
0.18710E+07
0.24297E+07
0 . 14010E+07
0.24887E+07
0.37489E+07
0.51576E+07
0.54110E+06
0.96117E+06
0.14479E+07
0.19920E+07
0.25872E+07
0.14904E+07
0.26484E+07
0.39907E+07
0.54914E+07
0.57563E+06
0.10229E+07
0 . 15413E+07
0.21209E+07
0.27551E+07
0.42482E+07
0.16407E+07
0.22582E+07
0.29341E+07
0.3259E+03
0.5787E+03
0.8716E+03
0 . 1199E+04
0.1259E+03
0.2235E+03
0.3366E+03
0.4630E+03
0.6013E+03
0.3467E+03
0.6159E+03
0.9278E+03
0.1276E+04
0.1339E+03
0.2379E+03
0 . 3583E-K)3
0.4930E+03 .
0.6403E+03
0.3688E+03
0.6554E+03
0.9876E+03
0.1359E+04
0 . 1425E+03
0.2531E+03
0.3814E+03
0.5249E+03
0.6818E+03
0.1051E+04
0.4060E-MJ3
0.5589E+03
0.7261E-M)3
Figure 3.7(e), continued: Receptor Concentration Table
and Print/File Options (For screening, all concentrations
should be multiplied by 2.0)
34
-------
6 1.0
6 1.5
6 2.0
6 1.0
6 1.5
6 2.0
6 2.5
6 3.0
Would you like a
Would you like to
(1-yes, 0-no) --
FILENAME? a:phos.
Another RVD run?
120.0 0.15856E+07
120.0 0.28186E+07
120.0 0.42482E+07
210.0 0.61239E+06
210.0 0 . 10886E+07
210.0 0.16407E+07
210.0 0.22582E+07
210.0 0.29341E+07
printed output (yes-1
save your data to a
1
dat
(y or n) •- n
0.3924E+03
0.6975E+03
0.1051E+04
0.1516E+03
0.2694E+03
0.4060E+03
0.5589E+03
0.7261E+03
, no-0)? 0
disk file?
Figure 3.7(e): Receptor Concentration Table and Print/File
Options (For screening, all 'concentrations should be multiplied
by a factor of 2.0)
35
-------
3.5.2 Batch Mode
This example illustrates the use of the RVD model in the
batch mode. The source in question is a vinyl chloride release
from a pressure relief valve that is depressurized through a
stack and routed to the atmosphere. This source emits 15.12
kg/sec of 100 percent vinyl chloride for 3 minutes. The stack
parameters include an exit velocity of 100 m/sec, an exit
diameter of 0.25 m, a stack height of 12 m, and an exit"
temperature of 259 K. Since the release routes through a stack,
the "release pressure" to be used is atmospheric.
Six wind speeds are to be examined ranging from 1.0 to 5.0
m/sec. Two receptors are located at 100 and 500 m downwind.
Figure 3.8 is the data input file for this example run. The data
were saved under the file name "a:vinyl.dat".
Vinyl Chloride
15.12
100
.25
259
12
100
62.5
15.12
62.5
3
15
1
7
1 1.5 2
2
100 500
298 298 298 298 298 298
0
2.5 3.1 3.6 5
Figure 3.8: Input Data File, Example 3.5.2
36
-------
After initiating execution by typing the command "RVD" at
the DOS prompt, the title frame (Figure 3.2) appears on the
terminal screen. As execution continues (Figure 3.9), the user
tells the program to access the input data via the data file
"a:vinyl.dat", the user choosing to have the model output sent
directly to the printer.
DATA INPUT VIA KEYBOARD(O) OR FILE(l)? 1
FILENAME? a:vinyl.dat
OUTPUT -- HARD COPY(l) OR SCROLL TO SCREEN(O)? 1
Figure 3.9: Interactive Procedure for Batch Mode
Figure 3.10 is the resulting hard copy of this model run.
As seen before in Figure 3.7, the resulting output is a series of
tables beginning with the input data and concluding with the
concentration estimates at plume touchdown and specific receptor
locations, as before. To determine the worst-case ambient impact
of the pollutant, the user should compare concentrations keeping
in mind their locations with respect to a specified plant
fenceline. For example, if the fenceline in this case is located
100m downwind, a review of the touchdown concentrations at
touchdown distances in excess of 100m indicates that the maximum
37
-------
concentration is about 2.07 g/m3 (occurring in stability classes
A and B with 1.5 m/sec winds at 104m downwind). A review of the
table giving fenceline (100m) concentrations confirms that this
concentration exceeds any fenceline value. For screening
purposes/ all concentration values should be multiplied by a
factor of 2.0 prior to comparing them with a significance level
or health effects threshold.
Vinyl Chloride
07-28-1988
Input Data
.25
Pollutant emission rate (kg/sec) - 15.12
Exit gas velocity (m/sec)- 100
Exit Temperature (K)- 259
Stack Height (m) - 12 Diameter (m) -
Pollutant Concentration (volume %) •• 100
Exhaust Gas Density (kg/m3) - 2.933481
Exhaust Gas Molecular Weight - 62.5
Exhaust Gas Mass Flow Rate (kg/sec) - 15.12
Pollutant Molecular Weight - 62.5
Release duration .(min) - 3 Av. Time (min)
Release pressure (atm) - 1
Wind Speeds (m/sec) - 1.0 1.5 2.0 2.5
Distances (m) - 100 500
Ambient Temperature (K) - 298 298 298 298 298
Urban Wind Speed Profile Exponents
Dense Gas Behavior
- 15
3.1
298
3.6
5.0
Wind
Speed
1.0
1.5
2.0
2.5
3.1
3.6
5.0
Stability Class
1 2 3 4 56
1
1
1
1
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
2
2
2
(0-Non-Dense Behavior 1-Dense Gas Behavior
2-Combinations that cannot occur)
Figure 3.10: Hard Copy of Example Run Output
38
-------
Release Richardson Numbers
Stability Class
Wind 123456
Speed
1 0 80806.7 80806.7 80073.4 79346.8 78626.8 78626.8
1*5 23942.7 23942.7 23725.5 23510.2 23296.8 23296.8
2 0 10100.8 10100.8 10009.2 9918.3 9828.3 9828.3
2 5 5171.6 5171.6 5124.7 5078.2 5032.1 5032.1
3'l 2712.5 2712.5 2687.8 2663.4 2639.3 2639.3
3 6 1732.0 1732.0 1716.3 1700.7 1685.2 1685.2
5.0 646.5 646.5 640.6 634.8 629.0 629.0
Dense Plume Trajectory
Stability Wind Flume Touchdown Touchdown
Class Speed Rise Distance Concentration
(m/sec) (m) (m) (ug/m3) (ppm)
1
1
. 1
1
2
2
2
2
2
2
2
3
3
3
3
3
3
3
1.0
1.5
2.0
2.5
1.0
1.5
2..0
2.5
3.1
3.6
5.0
1.0
1.5
2.0
2.5
3.1
3.6
5.0
39.0
34.1
30.9
28.7
39.0
34.1
30.9
28.7
26.7
25.4
22.8
38.9
34.0
30.9
28.6
26.7
25.4
22.7
67.70
103 . 94
141.14
179.14
67.70
103 . 94
141.14
179.14
225.63
265.03
378.12
68.35
104.95
142.52
180.89
227.85
267.65
381.88
0.24883E+07
0.20796E+07
0.18261E+07
0.16481E+07
0.24883E+07
0.20796E+07
0.18261E+07
0.16481E+07
0.14909E+07
0.13893E+07
0.11865E+Q7
0.24784E+07
0.20712E+07
0.18185E+07
0.16412E+07
0.14845E+07
0.13833E+07
0.118136*07
0.97542E+03
0.81522E+03
0.71582E+03
0.64607E+03
0.97542E+03
0.81522E+03
0.71582E+03
0.64607E+03
0.58443E+03
0.54459E+03
0.46513E+03
0.97154E+03"
0.81189E+03
0.71285E-t-03
0.64335E+03
0.58193E+03
0.54224E+03
0.46307E+03
Figure 3.10, continued: Hard Copy of Example Run Output
(For screening, all concentrations should be multiplied
by a factor of 2.0)
39
-------
4
4
4
4
4
4
4
5
5
5
5
5
6
6
6
6
S
1.0 38.7 69.01 0.24686E+07 0.96767E+03
1.5 33.9 105.97 0.20627E+07 0.80858E+03
2.0. 30.8 143.91 0.18110E+07 0.70989E-K)3
2.5 28.6 182.67 0.16343E+07 0.64064E+03
3.1 26.6 230.10 0.14782E+07 0.57944E+03
3.6 25.3 270.30 0.13773E+07 0.53990E+03
5.0 22.7 385.68 0.11761E+07 0.46102E+03
2.0 30.7 145.32 0.18034E+07 0.70694E+03
2.5 28.5 184.46 0.16274E+07 0.63794E+03
3.1 26.5 232.36 0.14718E+07 0.57696E+03
3.6 25.2 272.97 0.13713E+07 0.53756E+03
5.0 22.6 389.52 0.11709E+07 0.45898E+03
1.0 38.6 69.68 0.24587E+07 0.96382E+03
1.5 33.8 107.00 0.20543E+07 0.80528E-M33
2.0 30.7 145.32 0.18034E+07 0.70694E-f03
2.5 28.5 184.46 0. 16274E+07 0.63794E+03
Concentrations at Specific Receptor Distances
tability Wind Distance Concentration
Class Speed
(m/sec) (m) (ug/m3) (ppm)
1 1.0 100.0 0.12821E-J-07 0.5026E-K)3
1 1.0 500.0 0.83113E+05 0.3258E+02
1 1.5 500.0 0.14398E-MD6 0.5644E+02
1 2.0 500.0 0.21266E+06 0.8336E+02
1 2.5 500.0 0.28785E+06 0.1128E+03
2 1.0 100.0 0.12821E-f07 0.5026E+03
2 1.0 500.0 0.83113E+05 0.3258E+02
2 1.5 500.0 0.14398E+06 0.5644E+02
2 2.0 500.0 0.21266E+06 0.8336E-HJ2
2 2.5 500.0 0.28785E+06 0.1128E+03
2 3.1 500.0 0.38545E+06 0.1511E-K)3
2 3.6 500.0 0.47223E+06 0.1851E-H)3
2 5.0 500.0 0.73793E+06 0.2893E-H33
Figure 3.10, continued: Hard Copy of Example Run Output
(For screening/ all concentrations should be multiplied
by a factor of 2.0)
40
-------
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
5
5
5
5
5
6
6
6
6
6
1.0
1.0
1.5
2.0
2.5
3.1
3.6
5.0
1.0
1.0
1.5
2.0
2.5
3.1
3.6
5.0
2.0
2.5
3.1
3.6
5.0
1.0
1.0
1.5
2.0
2.5
100.0
500.0
500.0
500.0
500.0
500.0
500.0
500.0
100.0
500.0
500.0
500.0
500.0
500.0
500.0
500.0
500.0
500.0
500.0
500.0
500.0
100.0
500.0
500.0
500.0
500.0
0.12980E+07
0 . 84146E+05
0.14577E+06
0.21531E+06
0.29143E+06
0.39025E+06
0.47811E+06
0.74713E+06
0.13141E+07
0.85191E+05
0.14758E+06
0.21799E+06
0.29506E+06
0.39511E-»-06
0.48407E+06
0.75645E+06
0 . 22070E+06
0.29873E+06
0.40003E+06
0.49010E+06
0.76588E+06
0.13305E-f07
0.86250E+05
0 . 14941E+06
0.22070E+06
0.29873E+06
0.5088E+03
0.3299E+02
0.5714E+02
0 . 8440E+02
0.1142E+03
0.1530E+03
0.1874E+03
0.2929E-I-03
0.5151E+03
0.3340E+02
0.5785E+02
0.8545E+02
0.1157E+03
0 . 1549E-M33
0.1898E+03
0.2965E-H33
0.8651E+02
0.1171E+03
0.1568E+03
0 . 1921E+03
0.3002E+03
0.5215E+03
0.3381E-HD2
0.5857E+02
0.8651E+02
0 . 1171E+03
Figure 3.10, continued: Hard Copy of Example Run Output
(For screening, all concentrations should be multiplied
by a factor of 2.0)
41
-------
42
-------
REFERENCES
1. Hoot, T.G., R.N. Meroney, and J.A. Peterka, 1973: Wind
Tunnel Tests of Negatively Buoyant Plumes.
EPA-650/3-74-003, US Environmental Protection Agency,
Research Triangle Park, NC 27711.
2. Puttock, J.S., D.R. Blackmore, and G.W. Colenbrander, 1982:
"Field Experiments on Dense Gas Dispersion,"in Dense
Gas Dispersion (R.E. Britter and R.F. Griffiths, ed.),
Elsevier Scientific Publishing Comp., New York.
3. Environmental Protection Agency, 1988: A Dispersion Model
for Elevated Dense Gas Jet Chemical Releases, Volume I.
EPA-450/2-88-006a, US Environmental Protection Agency,
Research Triangle Park, NC 27711.
4. Turner, D. B., Workbook of Atmospheric Dispersion Estimates.
US Environmental Protection Agency, Research Triangle
Park, NC 27711. -
43
-------
44
-------
APPENDIX
Program Code
-------
-------
Relief Valve Discharge (RVD) Screening Program
Version 2.0
Developed by
(IS EPA Source Receptor Analysis Branch
Model Application Section
Original version Hay. 1986
Version 2.0 created 12/88 by Dave Guinnup
Based on the Hoot, Meroney, and Peterka equations, this screening
technique will estimate for short term denser than air gas releases:
plume rise, plume touchdown distance, concentration at touchdown, and
the concentrations at up to 30 downwind distances specified by the user.
Note:
While the OS EPA does not warrant the use of this program,
the Agency does provide it as a general service.
ALSO NOTE THAT THE CONSERVATIVE -FACTOR OF 5" IS NO LONGER USED
IN THIS VERSION OF RVD ! !
Additional information can be obtained by contacting Dave Guinnup
at (919) 541-5690 or FTS 629-5690.
Citations:
Hoot, T.G., R.N. Meroney, and J.A. Peterka (1973). "Wind Tunnel Tests
of Negatively Buoyant Plumes." EPA-650/3-74-003, U.S. Environmental
Protection Agency, Research Triangle Park, NC, 104 p.
Puttock, J.S., O.K. Blackmore, and G.W. Colenbrander (1982). 'Field
Experiments on Dense Gas Dispersion," Dense Gas Dispersion
(R.E. Britter and R.F. Griffiths, ed.), Elsevier Scientific
Publishing Comp., New York, pp 13-41.
10
20
30
50
51
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
311
320
330 KEY OFF
340 LET FMT» - • MM*.MM MM*.MM *****.*»** ****».»***•
350 FT1J- • t »»*.» IMM.I ».MM»"*— f.!M»A"**"
360 FT3S-"M».» *•»*»*"
370 FT$-" * M*.» M*.» MM.** I.M«*A*A* •.«»»*"•*"•
380 FT2S-"M*I.»"
390 FT4S-" f».* MMM.» MMM.f MMM.t MMM.I Iff***.I
400 '
410
420
430 DIM ARHO(6),DEL(6).RI(21,6),A(21,6),SG(6),TA(6),RV(21.6),FR(6).FRH(21,6)
440 DIM CALH(6),VHS(21,6).CRH(21.6),DRH(21,6),MWH(21,6),TH(21,6)
450 DIM DELTA (21, 6), DISTH (21, 6) , DISTD (21, 6), DISTF (21. 6) , DIST (30)
460 DIM CONCO(21,6),CONC(21,6),P(6),USTAR(6).V(21),HA(21,6),L(6)
470 COLOR 3.1:CLS
480 PRINT • Relief Valve Discharge (RVD 2.0) Screening Program
540 PRINT'• December 1988
550 PRINT ""
560 PRINT
570 PRINT
580 PRINT
590 PRINT
591 PRINT
610 PRINT
750 PRINT
760 PRINT
770 PRINT
780 PRINT
781 PRINT
782 PRINT
783 PRINT
784 PRINT
785 PRINT
790 GOSUB
800 P(l)-.15:P(2)-.15:P(3)-.2:P(4)-.25:P(5)-.3:P(6)-.3
820 FOR 1-1 TO 6:TA(I)-298:USTAR(I)-.06:NEXT I
830 LET DS-DATES
840 INPUT "DATA INPUT VIA KEYBOARD(0) OR FILE(1)";INDAT
IF INDAT-0 GOTO 950
INPUT "FILENAME-;FILS
MMM.I*
INITIALIZE ARRAYS
• Based on toe Hoot, Meroney, and Peterka equations,"
"this screening technique will estimate for short term*
•denser than air gas releases: plume rise, plume"
•touchdown distance, concentration at touchdown, and the"
"concentrations at up to 30 user-specified downwind distances."
• •
" Notes:":PRINT "•
" * 'Pollutant' refers to the chemical in whose concentration"
• you are specifically interested.":PRINT ••
• * 'Exhaust gas' refers to the entire gas stream which is"
• being released."
" * This version of RVD includes no 'safety factors' (see manual)
4350
Concentration estimates are most appropriate for neutral
to stable atmospheric conditions (see manual)."
850
860
-------
870 OPEN "I", 12, FIL$
880 INPUT »2,T$,QC,EXITV,D,TO,HS,VOL,MW,MO.MI«:,TDUR,rAV,PR,NWS
890 FOR J-l TO NKS:INPUTt2.V(J):NEXT J
900 INPOT»2,ISDsrOR J-l TO ISO: INPUM2, DIST (J):NEXT J
910 FOR J-l TO <:INPOT»2,TA(J):MEXT J
920 INPOTI2, mSP
940 CLOSZ»2:COTO 1600
950 INPUT "Enter title (with out comas) — ",TJ:IF II-l GOTO 1100
960 INPUT "Enter Emission Rate of Specific Pollutant (kg/we) — ",QC
961 IF II-l THEN II2-1:GOTO 1030
970 INPUT 'Enter Exhaust Gas Exit Velocity (in/see) — ",EXITV:IF II-l GOTO 1100
980 INPUT "Enter Stack Diameter (m) — «,D:IF II-l GOTO 1100
990 INPUT "Enter Exit GAS Temperature (K) — ",TO:IF II-l GOTO 1100
1000 INPUT "Enter Stack Height (m) — ",HS:IF II-l GOTO 1100
1010 INPUT "Enter Pollutant Concentration (vol%) — ",VOL:IF II-l THEN II2-1.-GOTO 1100
1011 INPUT "Enter Pollutant Molecular Weight — ",MNC:IF II-l THEN II2-1.-GOTO 1100
1012 PRINT "You must choose to enter either:"
1013 PRINT " (1) Exhaust fias Molecular Weight, or"
1014 PRINT • (2) Exhaust Gas Mass Flow Rate."
1015 PRINT ••:INPUT "Choose (1) or (2) — ",ICH
1016 ON ICH GOTO 1020,1080
1020 INPUT "Enter Exhaust Gas Molecular Weight — ",MH
1030 MO-100!*QC"MW/VOI./MWC:IF II2-1 GOTO 1081:IF II-l GOTO 1100
1031 GOTO 1082
1080 INPUT "Enter Exhaust Gas Mass Flow Rate (kg/sec) — ",MO
1081 MN«MO*VOL*MNC/100!/QC:IF II-l GOTO 1100
1082 INPUT "Enter duration of release (mini — ",TOUR:IF II-l GOTO 1100
1083 INPUT "Enter desired averaging time (mini — ",TAV:IF II-l GOTO 1100
1084 INPUT "Enter pressure inside vessel (atm) — ",?R
1100 CLS:PRINT "II. ";TS
1110 PRINT "*2. Pollutant emission rate (kg/sec) - ";QC
1120 PRINT "13. Exit gas velocity (m/sec)- ";EXITV
1130 PRINT "*4. Diameter (m) - ";0
1140 PRINT "«S. Exit Temperature (X)- ";TO
1150 PRINT •*«. Stack. Height (m) - ";HS
1160 PRINT "17. Pollutant Concentration (volume %) - -;VOL
1170 PRINT "»8. Pollutant Molecular Weight - ";MNC
1180 PRINT "19. Exhaust Gas Molecular Weight - ";MH
1190 PRINT **10. Exhaust Gas Mass Flow Rate (kg/see) - ";MO
1191 PRINT "»11. Duration of Release (mini - *;TDUR
1192 PRINT "*12. Averaging Time (rain) - ";TAV
1193 PRINT "*13. Release Pressure (atm, absolute) - ";PR
1200 PRINT •"
1210 PRINT 'If a value is incorrect, enter its number."
1220 INPUT "If all values are OK, enter 0. — ".ICOR
1230 IF ICOR - 0 GOTO 1250
1240 II-1:ON ICOR GOTO 950,960.970,980,990.1000,1010,1011,1020,1080,1082,1083,1084
1250 CLS:INPUT "Enter desired number of wind speeds (maximum-21) ~ ",NWS
1260 PRINT "Enter ";NNS;" wind speed(s) (m/sec) separated by s"
1270 FOR IJ-1 TO NWS
1271 INPUT; V (I J): IF V(IJ»-1! GOTO 1272 ELSE PRINT • No wind speeds less than 1.0 rn/s are
allowed!":GOTO 1271
1272 NEXT IJ
1280 PRINT ""
1290 PRINT "Here afe your wind speeds:"
1300 FOR IJ-1 TO NWS
1310 PRINT USING FMTS;V(IJ):N£XT IJ
1320 INPUT "I* everything OK? (y or n) ~ ".ANS3
1330 IF ANS9 <> "y" AND ANSJ <> "Y- GOTO 1250
1340 CLS-.INPUT "Number of downwind receptor distances (max - 30)";ISD
1350 IF ISD>1 GOTO 1390
1360 INPUT "Enter one specific distance {m) — ".DIST(l)
1370 PRINT USING FM«;DIST(1)
1380 GOTO 1430
1390 PRINT "Enter";ISO;" specific distances (m) separated by "
1400 FOR J-l TO ISO:INPUT;DIST(J) .-NEXT J
1410 PRINT -":PRINT "Receptor distances are:"
1420 FOR J-l TO ISO:PRINT USING FMT$;OIST(J):NEXT J
1430 INPUT "Are values correct? (y or n) — ",ANS$
1440 IF ANS$ <> "Y" AND ANSS <> "y" GOTO 1390
1450 PRINT "Ambient temperatures (degrees X) default to:"
1460 PRINT ""
1470 PRINT "(A) 298 (B) 298 (C) 298 (D) 298 (E) 298 (F) 298"
-------
1480 PRINT "
1490 INPUT "Would you like to enter your own? (y or n) — ",ANSS
1500 IF ANS* <> "Y" AND ANSS <> "y" GOTO 1580
1510 PRINT "Enter the. ambient air temperatures (K) for each stability"
1520 PRINT • separated by s"
1530 FOR I • 1 TO 6:INPUT;TA(I):NEXT I
1540 PRINT •«
1550 PRINT USING FMT»;TA(1) ,TA{2) ,TA(3) ,TA{4) ,TA(5) ,TA(6)
1560 INPUT "Are values correct? (y or n) — *,ANS$
1570 IP ANSS <> "Y" AND ANSS <> "y" GOTO 1510
1580 PRINT "Wind speed profile exponents are for (0) urban"
1590 INPUT * or (1) rural conditions - choose one:",IWSP
1600 IF IWSP - 1 THEN P (1)-.07:P (2)-.07:P(3)-.l:P M)-.15:P (5)-.3S:P <6)-.55
1680 PRINT ""
1808 THAT - TDUR/TAV
1809 IF TOUR > TAV THEN TRAT-1!:IF TAV < 60 THEN TRAT-TRAT*(60/TAV)-0.2
1810 RHO-1.183«MW/29!*298/TO
1811 BXITVC-PR»4*MO/RHO/3.14159/0*2
1820 IF ABS«EXITV-EXITVC)/EXITVC)<.05 GOTO 1837
1831 PRINT "Velocity check calculates:"
1832 PRINT " ";EXITVC;" vs input velocity of •
1833 PRINT " ";EXITV
1834 PRINT ""
1835 INPUT * Would you like to continue the calculation anyway? (y or n) — ",ANS$
1836 IF ANSS 0 "y" AND ANSS <> "Y" GOTO 4320
1837 VN-29!/(1183!)
1838 CFM-EXITV«3.14159*0*2/4!
1840 PRINT ""
1850 INPUT "OUTPUT — HARD COPY(l) OR SCROLL TO SCREEN(0)";ICOP
1860 IF ICOP-0 GOTO 1890
1870 OPEN "0"
1880 GOTO 1920
1890 OPEN "O", II. "SCRN:":COLOR 7,4:CLS
1920 PRINT II,
1940 PRINT II.
1950 PRINT II, " Input Data" .
1960 PRINT II, ""
1970 PRINT II. "Pollutant .mission rate (kg/sec) • ";QC
1980 PRINT II, "Exit gas velocity (m/sec)- *;EXITV
•Exit Temperature (X)- -;TO
•Stack Height (m) - ";HS;" Diameter (ml - ";0
"Pollutant Concentration (volume %) - ";VOL
"Exhaust Gas Density (kg/m3) - ";RHO
•Exhaust Gas Molecular Height - *;MH
•Exhaust Gas Mass Flow Rate (kg/sec) - ";MO
•Pollutant Molecular Weight • ";MWC
•Release duration (min) • *;TDUR;" Av. Time (min) - ";TAV
•Release pressure (atm) - ";PR
•Wind Speeds (m/see) • ";
TO HWS-1:PRINT II. USING •«!.! ";V(IJ;
II. "LPT1:":IPR-I
II.
TS;'
: COLOR 7.
•OS
2000 PRINT II,
2010 PRINT II,
2020 PRINT II,
2030 PRINT II,
2040 PRINT II,
2050 PRINT II,
2060 PRINT II,
2071 PRINT II,
2072 PRINT II.
2080 PRINT II,
2090 FOR I»
2100 NEXT I:PRINT II. USING •|I.I";V(NWS)
2110 IF ISO > 1 GOTO 2140
2120 PRINT II, "Distance (m) - ";DIST(D
2130 GOTO 2160
2140 PRINT II. "Distances (m) • •;
2150 FOR 1-1 TO ISO:PRINT II, DIST(I) ;SPC(2); .-NEXT I:PRINT II,-"
2160 PRINT II, "Ambient Temperature (1C) - ";TA(1);TA(2) ;TA(3) ;TA(4) ;TA(5) ;TA(6)
2170 If IWSP-0 THEN PRINT II, "Urban Wind Speed Profile Exponents":GOTO 2200
2180 PRINT II, 'Rural Wind Speed Profile Exponents"
2200 IF ICALC-1 GOTO 3160
2210 '
2220 ' Acceleration of gravity (m/sec2)
2230 LET G - 9.8
2260 CONCG-5000!*MWC/VM
2270 '
2280 ' Because the ratio (friction velocity)/(wind speed at r-lOm) is used
2290 ' in place of the friction velocity, the "V(I)*2" term is included
2300 ' in the Richardson number calculations.
2310 '
2320 FOR J - 1 TO 6
2330 ' Calculate the ambient air density which is dependent upon temperature.
2340 LET ARHO(J) - 1.183 * 298! / TA(J)
2350 LET DEL(J) • (RHO-ARHO(J) ) /ARHO(J)
-------
2360 IF DEL(J)>0 GOTO 2380
2370 FOR 1-1 TO NWS:A(I,J)-0:NEXT I
2380 NEXT J
2400 FOR J - 1 TO 6
2410 FOR I - 1 TO NWS
2420 ' Richardson number test
2430 ' It RI is less than or equal to 30 than trait as a stack source.
2440 ' Wind speed at stack height.
2450 LET VHS(I.J) - V(I) » (HS/10!) AP (J)
2460 LET RKI.J) • (G»DEL(J)«MO) / (VHS (I. J) *D«RHO« (OSTAR(J) A2!) • (V{I) A2!) )
2470 IF RKI.J) <- 30! THEN GOTO 2SOO
2490 LET A(I.J) - 1
2500 NEXT I
2510 NEXT J
2520 ' The following loop identifies those.wind speed and stability class
2530 ' combinations which do not exist based on the Turner (1964)
2540 ' definitions of stability classes (see the CRSTER User's Manual).
2550 FOR J-l TO 6
2560 IF J-4 GOTO 2710
2570 FOR 1-1 TO NHS
2580 IF J-3 GOTO 2700
2590 IF J > 1 THEN GOTO 2620
2600 IF V(I) >• 3.1 THEN A(I,J)-2
2610 GOTO 2700
2620 IF J - 2 THEN GOTO 2660
2630 IF J - 5 THEN GOTO 2680
2640 IF V(I) >« 3.1 THEN A(I,J)-2
2650 GOTO 2700
2660 IF V(I) >- 5.1 THEN A(I,J)-2
2670 GOTO 2700
2680 IF V(I) < 2.0 THEN A(I,J)-2
2690 IF V(I) > 5.0 THEN A(I,J)-2
2691 GOTO 2700
2692 IF V(I) < 2.0 THEN A(I,J)-2
2700 NEXT I
2710 NEXT J
2720 FOR 3 - 1 TO 6
2730 ' Vertical Densimetric Froude Number
2740 IF OEUJK-0 GOTO 2800
2750 LET FR(J) - EXITV* < «RHO/(RHO-ARHO(J))) / (C*D)) A.S)
2760 ' Specific Gravity
2770 LET SG(J) - RHO/ARHO(J)
2780 ' Plume rise for negatively bouyant jet at calm conditions.
2790 LET CALH(J) - 2. 96*FR(J) «D
2800 FOR I - 1 TO NWS
2810 IF A(I,J) 0 1 THEN GOTO 3120
2820 ' Wind speed at stack height.
2830 LET VHS(I.J) - V(I) » (HS/10!) AP(J)
2840 ' Velocity ratio.
2850 LET RV(I.J) - EXITV/VHS (I, J)
2860 ' Plume rise for negatively bouyant jet with crosswind.
2870 LET CRH(I.J) - 1.32«D» (RV(I, J) A.333) • (SG(J) A.333)» CALH(J) THEN LET H • CALH(J)
2900 LET HA(I,J) - H
2910 ' Dilution Ratio at maximum plume rise.
2920 DRH(I.J)-<
-------
Dense Gas Behavior"
Stability Class"
3100 GOTO 3140
3110 LET A(I,J) - 0
3120 LET CONGO(I,J) - 0!
3130 LET DISTD(I.J) - 0!
3140 NEXT I
3150 NEXT J
3160 GOSOB 4350
3170 PRINT II, CHR3U2)
3180 PRINT II,
3190 PRINT II,
3200 PRINT II,
3210 PRINT II,
3220 PRINT II, Wind 123456"
3230 PRINT II, Speed"
3240 NLI-7
3250 FOR 1-1 TO NWS
3270 FOR J-l TO 6
3280 LET LIJ1-0
3290 IF A(I,J)-1 THEN UJJ-1
3300 IF A(I,J)-2 THEN L(J)-2
3310 NEXT J
3320 PRINT II, USING FT35;V(I) ;L(1) ;L(2) ;L(3) ;L(4) ;L(5) ;L(6)
3330 NLI-NU+1:IF NLI>20 THEN GOSUB 4350
3340 NEXT I
3350 PRINT II
3360 PRINT II, (0-Non-Dense Behavior l-D«n»e Gas Behavior
3370 PRINT II, 2-Combinations that cannot occur)"
3380 PRINT II,
3390 GOSUB 4350
3400 PRINT II,
3410 PRINT II,
3420 PRINT II,
3430 PRINT II,
3440 PRINT II, Wind 1 2 ' 3 4 5
3450 PRINT II, Speed"
3460 NLI"«
3470 POR 1-1 TO NWS
3480 IF ICALC-1 GOTO 3500
3490 FOR J-l TO 6:IF RI(I,J)>1000000! THEN RI(I,J)-999999.9:NEXT J
3500 PRINT II, USING FT4$;V(I) ;RI (1,1) ;RI (1,2) ;RI (1.3) ;RI (I, 4) ;RI (1,5) ;RI (I, 6)
3520 NEXT I
3530 N - 0
3540 FOR I - 1 TO NWS
355.0 FOR J - 1 TO 6
3560 IF A(I.J) <> 1 THEN N-N * 1
3570 NEXT J
3580 NEXT I
3590 IF N - NWS*6 GOTO 4060
3600 GOSOB 4350
3610 PRINT II, CHRSU2)
Dense Plume Trajectory*
Release Richardson Numbers"
Stability Class"
3620 PRINT II,
3630 PRINT II,
3640 PRINT II,
3650 PRINT II,
3660 PRINT II,
3670 NLI-NLI+6
3680 FOR J - 1
3690 PRINT II.
3700 FOR I - 1
3710 IF A(I,J)
Stability Wind Plum* Touchdown
Class Speed Rise Distance
(m/sec) (m) On)
Touchdown "
Concentration"
(ug/m3) (ppm)
TO 6
... . ".-NLI-NLI+l
TO NWS
0 1 GOTO 3740
3720 PRINT II, USING FTS; J;V(I) ;HA(I, J) ;DISTD(I. J) ;CONCD(I, J)*TRAT;CONCD(I, J) •.0245/MWC«TRAT
3730 NLI-NLI+lrlF NLI>19 THEN GOSUB 4350
3740 NEXT I
3750 NEXT J
3760 GOSOB 4350
3770 PRINT II, CHR$U2)
3780 PRINT II, Concentrations at Specific Receptor Distances"
3790 PRINT II
3800 PRINT II
3810 PRINT II
3820 PRINT II, (m/sec) (m) (ug/m3) (ppm)
3830 NLI-6
3840 FOR J - 1 TO 6
Stability Wind Distance Concentration
Class Speed
(m/sec) (m) (ug/m3)
-------
3850 PRINT 11, " ":NLI-NLI+1
38S1 ' Calculation of post-touchdown concentrations
3860 FOR K - 1 TO ISO
3870 PRINT •!, • VNLI-NLI-H
3880 FOR I - 1 TO NWS
3890 IF A(I,J) <> 1 GOTO 4010
3910 LET BIFF - DIST(K) - DISTD(I.J)
3920 IF DIFF < 0! THEN GOTO 4010
3930 IF DISTF(I.J) < DISTD(I.J) THEM DISTF(I.J) - OISTO(I,J)
3940 IF DIST(K) < DISTFd.J) THEN GOTO 3980
3950 LET CONC(I,J)-CONCD19 THEN GOSOB 4350
4010 NEXT I
4020 NEXT K
4030 NEXT J
4040 ICALC-1
4050 GOTO 4070
4060 PRINT tle "•SPRINT »1, "Treat as neutrally-buoyant for all stabilities and wind speeds"
4070 CLOSE»1:IF IPR-1 GOTO 4100
4080 INPUT "Would you like a printed output (yes-1, no-0)";ICOPl
4090 IF ICOP1-1 THEN IPR-I:GOTO 1870
4100 PRINT "Would you like to save your data to a disk file?"
4110 INPUT "(1-yes, 0-no) — ",ISAV
4120 IF ISAV-0 THEN GOTO 4340
4130 INPUT "FILENAME";FILS
4140 OPEN "0", «2, FIL5
4150 PRINT 12,T$
4160 PRINT t2.QC
4170 PRINT I2.EXITV
4180 PRINT 12.0
4190 PRINT 12,TO
4200 PRINT 12.US
4210 PRINT 12,VOL
4220 PRINT »2,MW
4230 PRINT *2,MO
4240 PRINT *2.HWC
4241 PRINT *2,TDUR
4242 PRINT »2,TAV
4243 PRINT »2,PR
4250 PRINT *2,NHS
4260 FOR J-l TO NWS:PRINT»2,V(J);:N£XT J:PRINT »2. "
4270 PRINT02, ISD:FOR J-l TO ISD:PRIN7»2.DIST(J);:NEXT J:PRINT*2,""
4280 FOR J-l TO 6:PRINT»2.TA(J);:NEXT J:PRINT»2.""
4290 PRINT »2.IWSP
4310 CLOSE*2:GOTO 4340
4320 INPUT "Would you like to save these data to a file anyway? (y or n) — ",ANS$
4330 IF ANSS - "y" OR ANSJ - "Y" THEN GOTO 4130
4340 INPUT "Another RVO run? (y of n) — ",ANS$
4341 IF ANS3 - "y" OR ANSS - "Y" THEN COLOR 3.1sCLS:IPR-0sICALC-0:GOTO 800
4342 SYSTEM
4350 IF IPR-1 THEN RETURN
4360 PRINT "":PRINT •":PRINT * Press any key to continue"
4370 AS-INKEY$:IF A4-" THEN 4370
4380 NLI«0:CLS:RETURN
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA 450/4-88-024
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
User's Guide for RVD 2'.0—A Relief Valve Discharge
Screening Model
5. REPORT DATE
December 1988
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U. S. Environmental Protection Agency
Office of Air Quality Planning & Standards
Source Receptor Analysis Branch
Research Triangle Park, N.C. 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME.ANO ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
EPA contact: Dave Guinnup
16. ABSTRACT
This document is the user's guide for RVD 2.0, a personal computer model
which provides estimates of short-term ambient concentrations for screening
pollution sources which emit denser-than-air gases through vertical releases.
The code is based on empirical equations derived from wind tunnel tests. The
user's guide describes the bases, features, applicability and limitations of
the model, and provides two example runs of the model for illustrative purposes
and benchmark testing.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Air pollution
Dense gas
Screening model
Computer model
Dispersion
Elevated sources
18. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (Ttiu Report)
21. NO. OP PAGES
20. SECURITY CLASS (This page I
22. PRICE
EPA Perm 2220-1 (R»». 4-77) PREVIOUS EDITION is OBSOLETE
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