Jones D.S.J., Pujado P.R. Handbook of Petroleum Processing
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THE REFINERY ENVIRONMENTAL ISSUES 653
(a) Plant noise design targets:
Design criteria should be developed early in the design stage with considerations
given to federal, state and local laws, client standards, proximity and type of
adjacent communities as well as anticipated community growth patterns.
(b) Development of mechanical equipment and control valve noise criteria:
Criteria for individual items of equipment will be developed to meet plant noise
design objectives and will be made part of inquiry specifications for all noise-
generating equipment.
(c) Preparation of preliminary noise contour map:
Noise reception levels will be predicted using the engineering company’s in house
estimate data bank and noise prediction computer programs.
(d) Preparation of noise control budget:
A budget is prepared which identifies funds necessary to implement noise control
measures.
(e) Plot plan assistance:
Equipment location can be optimized based on projected noise levels which will
minimize the need of attenuation treatment.
(f) Noise control recommendations:
Recommendations for noise attenuation are prepared based on the contribution
of all major equipment to the composite noise level, of a given plant area.
(g) Preparation of final noise contour map:
After final noise level data have been obtained, the plot plan has been finalized and
any noise control measures have been implemented, a noise contour map can be
prepared. The noise contour map identifies that the plant noise design objectives
have been met. This contour map is normally prepared using the company’sown
modeling program. Alternatively a proprietary program can be leased from an
appropriate soft ware company.
An effective noise control program requires an analysis in the early stage of plant
design when no equipment has been purchased. The most efficient and economical
approach to nose control is to include noise control features as an integral part of
equipment design through equipment specifications. An optimal plot plan arrange-
ment can also minimize the need for attenuation treatment by strategically locating
noisy equipment or positioning process areas or known noise sources at maximum dis-
tances from sensitive areas. The task of predicting noise levels to be used in the design
phase can be overwhelming without the aid of the computer. A typical project may
involve hundreds of thousands of noise sources, and attempting to do the noise level
predictions by hand computer program to predict community/in-plant noise levels.
This program is discussed below in “a typical community/in-plant noise program”.
A typical community/in-plant noise program
The noise pollution cycle is one of emission, propagation and reception. A computer
program is usually developed to simulate the noise propagation from several types of
654 CHAPTER 14
noise sources with different configurations. This section will describe the capabilities
of such a program and its application to plant design.
(1) Capabilities
The computer program calculates sound pressure levels generated by single or
multiple noise sources at specified grid points or special receptors. This program
should utilize a simple algorithm to simulate the propagation of four different
source models. These models include point, line, discrete points on a line, and
plane sources.
(2) The Mathematical model
The basic equation used in the program is:
SPL = PWL + 10 log [F(R)] + DI + K − AE
where
SPL = sound pressure at any receptor in dB
PWL = source sound power level in dB
10 log[F (R)] = distance attenuation factor for various types of source which
will be defined in the following paragraphs in dB
DI = directivity index in dB
K = Characteristic resistance of air in dB
AE = total excess attenuation factor (molecular absorption, Ground
absorption, screening effect, barrier effect, etc.) in dB.
r
Distance attenuation F(R)
(A) For a point source:
F(R) =
1
R
2
where
R = distance between source and receptor
(B) For a continuous line source:
F(R) =
α
2
− α
1
R
Od
All terms are defined in Figure 14.10.
(C) For discrete sources on a line:
F(R) =
N
r=1
1
R
2
n
where
N = the number of sources on the line
R = the distance between receptor and each source
THE REFINERY ENVIRONMENTAL ISSUES 655
d
R α
1
α
2
Figure 14.10. Continuous line source.
(D) For a plane source:
F(R) = 1/A
L/2
−L/2
L/2
−L/2
Rdxdy
where
R = distance from the receptor to a differential area dxdy on the plane.
All terms are defined on Figure 14.11.
r
Excess attenuation A
Excess attenuation due to ground and molecular absorption can be entered as input
data. When these data are not entered, the default values shown in Table 14.11 should
be used. In-plant shielding corrections may be included in the ground absorption
correction. Corrections due to the effect of wind, temperature gradients, rain, sleet
and barriers will be added at a future date.
L
dx/dy
l
R
Receptor
0
Figure 14.11. Plane source.
656 CHAPTER 14
Table 14.11. Default values for excess attenuation
Molecular absorption,
Frequency, Hz Ground absorption, dB dB/1,000 ft
63 ↑ 0
125 0
250
0.3
500 0 1.0
1,000 2.0
2,000 3.0
4,000 6.0
8,000 ↓
11.0
(i) Input data requirements
The requirements for each noise source are basically the source sound power
spectrum, the source location and the desired noise level prediction model.
Additionally, excess attenuation factors including molecular and ground ab-
sorption data can be input if available.
(ii) Output
In the program described here, all the input data will be summarized and the
calculation results will be printed in the computer print out. The calculated
octave band sound pressure level, overall sound pressure levels, and A-weighted
sound pressure levels will be tabulated for all the special receptors specified.
The calculated A-weighted sound pressure levels for all grid points will also
be listed in the computer printout.
Special routines are available to draw configurations of equipment normally
present in a process plant, such as round-headed vessels, cooling towers, air
coolers, and fired heaters.
(iii) Applications
The community/in-plant noise program described here can be used to perform
the following applications:
r
Estimating the net noise impact due to a prospective industrial activity
r
Checking plant design for compliance with noise regulations
r
Establishing noise emission levels and plant design necessary to comply
with the applicable environmental regulations
As with other computer programs, the accuracy of computer-calculated noise
levels depends on the accuracy of the input data as well as the application of
the model selected for a particular noise source.
THE REFINERY ENVIRONMENTAL ISSUES 657
Appendix 14.1: Partial pressures of H
2
S and NH
3
over aqueous solutions
of H
2
S and NH
3
Refer to Appendix 14.2 for the interpretation and use of these charts
10
3
10
4
10
2
H
2
S in Solution (ppm by wt)
H
2
S in Partial Pressure psia
1234567891234567891
3.0
2.0
1.5
H
2
S in pure water at 200°F
20.0
15.0
10.0
7.0
5.0
4.0
3.0
2.0
1.5
4.0
5.0
7.0
10.0
15.0
234567891
10
−1
10
−2
10
−3
1.0
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
100
10
1
Molar Ratio
of NH
3
/H
2
S
in Solution.
Figure 14.A.1. Partial pressure of H
2
S over aqueous solutions of H
2
S and NH
3
at 200
◦
F.
658 CHAPTER 14
10
4
10
3
10
2
10
−3
10
−2
10
−1
1.0
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
1 2 3 4 5 6 7891 2 3 4 5 6 78 91 2 3
10
1
100
3.0
4.0
1.5
20.0
15.0
10.0
7.0
5.0
4.0
3.0
2.0
1.5
2.0
4567891
H
2
S in Solution (ppm by wt)
H
2
S Partial Pressure psia
Molar Ratio
of NH
3
/H
2
S
in Solution.
Figure 14.A.2. Partial pressure of H
2
S over aqueous solutions of H
2
S and NH
3
at 210
◦
F.
THE REFINERY ENVIRONMENTAL ISSUES 659
Molar Ratio
of NH
3
/H
2
S
in Solution.
100
10
1
1987654321987654321987654321
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
10
−1
10
−2
10
2
10
3
10
4
10
−3
4
5
6
7
8
9
1.0
H
2
S Partial Pressure psia
H
2
S in Solution (ppm by wt)
7.0
5.0
4.0
3.0
2.0
1.5
10.0
15.0
20.0
1.5
2.0
3.0
4.0
5.0
Figure 14.A.3. Partial pressure of H
2
S over aqueous solutions of H
2
S and NH
3
at 220
◦
F.
660 CHAPTER 14
10
100
1.5
2.0
3.0
4.0
5.0
1.5
2.0
3.0
5.0
7.0
10.0
15.0
20.0
4.0
1.0
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
10
−1
10
−2
10
−3
10
2
10
3
10
4
4
2
1
1
1
2
3
5
6
7
8
9
234
567891 2 3 4 567891 2 3 4 567891
1
H
2
S in Solution (ppm by wt)
H
2
S Partial Pressure psia
Molar Ratio
of NH
3
/H
2
S
in Solution.
Figure 14.A.4. Partial pressure of H
2
S over aqueous solutions of H
2
S and NH
3
at 225
◦
F.
THE REFINERY ENVIRONMENTAL ISSUES 661
H
2
S in Solution (ppm by wt)
H
2
S Partial Pressure psia
1.0
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
5
4
3
2
1
1 2 3 4 5 6 7891 2 3 4 5 6 7891 2 3 4 5 6 789 1
1
10
100
1.5
2.0
3.0
4.0
5.0
7.0
10.0
15.0
20.0
1.5
2.0
3.0
4.0
5.0
10
−1
10
−2
10
−3
10
2
10
3
10
4
Molar Ratio
of NH
3
/H
2
S
in Solution.
Figure 14.A.5. Partial pressure of H
2
S over aqueous solutions of H
2
S and NH
3
at 230
◦
F.
662 CHAPTER 14
10.0
8
6
4
3
2
1.0
8
6
4
3
2
0.1
8
6
4
3
2
0.1
1234
10
2
10
3
10
4
681 2
NH
3
in Solution (ppm by wt)
NH
3
Partial Pressure psia
34 681 2 3 4 6 8 1
1.5
2.0
3.0
5.0
10.0
Molar Ratio
of NH
3
/H
2
S
in Solution.
Figure 14.A.6. Partial pressure of NH
3
over aqueous solutions of H
2
S and NH
3
at 200
◦
F.