 |
Description  |
|
|
FIELD OF THE INVENTION
The invention relates to a fugitive emissions monitoring system including
an integrated fugitive emissions analyzer and source identifier. Fugitive
emissions are the very large number of very low emission rate emissions
from an industrial complex. These fugitive emissions include emissions
from valves, pumps, seals, gaskets, flanges, fittings, hoses, and the
like. Regulatory requirements and sound operating practices require
extensive monitoring and record keeping to identify, track, and correct
fugitive emissions. This extensive monitoring and record keeping takes the
form of (1) unique identification of each potential emission source, for
example, each valve, pump, seal, gasket, flange, fitting, hose, or the
like, and (2) periodic, for example, daily, weekly, or monthly monitoring
of each such potential source.
According to the disclosed invention each potential source has identifying
means capable of providing electronic storage of a source location
identifier substantially simultaneously with sampling and electronic
storage of the sampled data. This identifying means, which may be bar code
label, is read by a detector, which may be a bar code reader, and the gas
in proximity thereto is substantially sampled by a suitable sensor. These
two inputs, the source identifier and the gas chemistry, are stored in an
electronic data logger for subsequent up loading and analysis in a
computer.
BACKGROUND OF THE INVENTION
1. Air Pollution
Air pollution exists when the atmosphere contains an objectionable
concentration of one or more deleterious substances. A substance may be
deleterious because it is an irritant. For example, it may be irritating
to the eyes, nose, skin, or mucus membranes of the respiratory system, or
may even cause difficulties in breathing.
In other cases pollutants may be toxic, causing chronic or acute reversible
or irreversible physiological damage to humankind, animals, or vegetation.
Ultimately this includes serious disease processes, such as black lung
disease, brown lung disease, and malignancies. In some case pollutants may
even lead to extermination of species.
Other effects of air pollution include deterioration of materials of
construction and of structures, or the creation of areas where certain
plant species cannot survive.
The atmosphere has always served as a gaseous and vapor waste dispersion
medium and disposal area. Waste materials, in the form of fogs,
dispersions, particulates, combustion products, and the like, are
introduced into the air, become widely dispersed, diluted, hydrated, and
even photochemically reacted. Some of these products then settle to the
ground or are removed by precipitation. The precipitation and particulates
may themselves be harmful. Other products may stay dispersed in the
atmosphere, building up, and causing further problems.
Human activities, especially industrial activities, have added both new
pollutants to the atmosphere and increased the background concentrations
of pollutants to a very high degree. Synthetics, acidic combustion
products, as SO.sub.2, and photodissociable synthetic molecules, as
chlorofluorocarbons, have been added to the ecological load by human
industrial activities.
2. Ambient Air Quality Standards
Ambient air quality standards are designed to protect the atmosphere from
air pollution.
Air pollution has three components: (1) source emissions, (2) atmospheric
transport and dispersal, and (3) receipt by a receptor. The degree of an
air pollution problem depends upon the interaction of these components.
Time is an important factor in each of the three components of air
pollution. In the case of the source, for example, emissions are
continuous from a power plant but intermittent from a dry cleaning plant.
In the case of atmospheric transport, inversions, stationary fronts, and
atmospheric high pressure systems which remain over a region for several
days all reduce dispersion. This reduced dispersion can produce air
pollution episodes during which pollutant concentrations build up. For
receptors, duration of exposure to pollutants is important. Humans may
survive large dosages of some pollutants and then eliminate the pollutant
from their bodies. However, other pollutants can accumulate in the body
over time, and are only respirated or excreted with great difficulty,
eventually causing illness or death. For these reasons, standards for air
pollutant concentrations specify an averaging period of from minutes to a
year.
In the case of emission standards, as distinguished from time-averaged
concentration standards, some emission standards are also set with time
limitations. For example, plume opacity standards which allow a certain
period of time for start-up and maintenance operations.
If pollutants are allowed to enter the air, nationwide and worldwide
emissions over a period of years may cause an increase in the background
concentration of that pollutant. This may create a condition in which new
normal concentrations, which are higher then old normal concentrations,
either interfere with normal atmospheric processes, as is the case with
the "Green-house Effect," the polar holes in the ozone layer, and acid
rain, or the new "background" of the pollutant may itself be directly
deleterious to human health. Ambient air quality standards are intended to
limit the concentration of pollutants.
3. Sources
Sources are the pollutant emitters. As a first approximation, sources can
be treated individually as point sources. Point sources include each stack
at a power plant, or petroleum refinery. Alternatively, or additionally,
sources may be treated collectively as area sources, for example, all of
the automobile exhausts in a metropolitan area.
Pollutants can be emitted from sources as gases or aerosols, that is, mist,
smoke, soot, fume, and dust. Once in the atmosphere, the primary pollutant
may undergo transformation into a secondary pollutant, for example, the
oxidation of sulfur dioxide to sulfates or the ultraviolet scission of
chlorofluorocarbons to free radicals.
4. Fugitive Sources
Emissions from a source generally enter the atmosphere from a distinct
stack or exhaust pipe, as an exhaust pipe or stack. While mobile sources,
that is, automobiles, and large stationary sources ranging from power
plant and industrial stacks down to residential chimneys emit most of the
man-made pollutants, pollutants also originate from a very large number of
very small, diverse locations around a building, a piece of equipment, a
dusty road, or a storage pile These are called fugitive emissions.
Fugitive industrial emissions are another source of pollutants. This is
especially true in the case of solvents, halocarbon vapors, cleaning
fluids, refrigerants, and the like, as well as radioactive emissions.
Fugitive emissions may escape into the atmosphere through windows, vents,
and doors rather than through regular exhaust systems. Rosebrook et al.
"The Measurement of Fugitive Hydrocarbon Emissions from Selected Sources
in Petroleum Refineries," Proceedings, Annual Meeting--Air Pollution
Control Association, 1978, 71st, Volume 3, Paper 78-36.4, 15 pp.,
CA:92:168224z, present relative fugitive emission data for hydrocarbon
sources, such as valves, flanges, pump seals, compressor seals, and drains
at four typical petroleum refineries. They report that compressor seals
have the highest average leak rates, while leakage from flanges are
practically insignificant. They also report that because of their large
numbers, the highest total leakage is from valves.
Hanzevack et al, "Fugitive Hydrocarbon Emissions--Measurement and Data
Analysis Methods," U.S. Environmental Protection Agency Office of Research
and Development, EPA 1978, EPA-600/2-78-199, Proceedings:
Symposium/Workshop On Petroleum Refinery Emissions; PB-287 900, 41-54,
CA:93: 172919t, presents data on valve fugitive emissions at a
petrochemical plant. Fugitive emissions are correlated with maintenance,
and is reported to show emission reduction through improved maintenance.
While each individual fugitive emission is likely to be small, the total
outflow from fugitive emissions is likely to be quite large. The
identification and measurement of fugitive emissions is required for both
emission inventorying and subsequent pollution control efforts.
5. Fugitive Sources and the Emission Inventory
An important requirement for any air pollution control program is a
comprehensive emission source inventory. This inventory identifies
sources, source locations, pollutant types, and quantities of emissions
throughout the relevant areas. A further aspect of the emission source
inventory, especially if mathematical modeling of pollutant dispersion is
contemplated, includes such engineering information as source heights,
diameters, capacities, and pollutant stream constituents, exit velocities,
temperatures, and concentrations. These data are used to model the plume
emanating from the source.
Data for the emission inventory may be gathered from plant surveys,
consumption summaries, production information, and stack-sampling reports.
6. Fugitive Halocarbon Emissions
Halocarbon emissions, including fluorocarbon, chlorocarbon, and
chlorofluorocarbon emissions, occur from a number of sources, including,
among others, purification system vents, product-loading vents, hoods,
vents, stacks, joints, seals, fittings, gaskets, and valves, including
relief valves. In practice, fugitive emissions, once identified and
located, are minimized by, among other expedients, repair, replacement, or
even enclosure of the emission sources and collection of the emissions.
Other expedients for the control of halocarbon fugitive emissions include:
installation of primary and redundant incineration facilities for both
point-source and collected fugitive emissions; installation of scrubbing
and neutralization or recovery units in conjunction with the incinerators;
installation of closed-process sewers, collection systems and larger or
redundant wastewater strippers; replacement of single mechanical seals on
pumps and agitators with double mechanical seals; leak-detection systems
and portable monitors; enclosed sampling and analytical systems; and
vapor-recovery systems for halocarbon loading, unloading, and equipment
clearing.
7. Measurement of Fugitive Emissions
Pollution measurements are divided into two categories: ambient
measurements and source measurements. Pollution measurements, whether
source measurements or ambient measurements, often require detection and
measurement in the ppmv to ppbv (parts per million by volume to parts per
billion by volume) range. This is especially true to determine trends. As
a general rule source concentrations range from tenths of a percent to a
few hundred ppmv, and ambient concentrations are lower.
In metropolitan areas of high population density and in highly integrated
manufacturing facilities, extensive sampling networks have been
established. These networks use continuous monitors installed at strategic
locations the data transmitted to a common repository or processor.
Ambient air sampling is typically used to:
(1) establish and operate a pollution incident alert network,
(2) locating the source of an undesirable pollutant,
(3) obtaining permanent sampling records for legal action,
(4) monitor a stationary emission source,
(5) model changes in the system, and
(6) establish long term trends.
Source sampling differs markedly from ambient sampling and has unique
problems and techniques which are distinct and different from ambient
sampling. Source gas temperatures may be high and the raw source gas may
contain high concentrations of water vapor or entrained mist, dust, or
other interfering substances. The high temperatures may require
specialized techniques and equipment, while the particulates and gases may
deposit on, or be absorbed in, or otherwise interfere with the sampling
probes before reaching the sensor.
A primary objective of source sampling is to prove compliance with
regulations. Other objectives of source sampling are to provide emission
data and emission data trends, and in this way to determine the need for
maintenance of process or control equipment, and measure product loss. In
the case of large stationary sources continuous sampling is utilized, and
this sampling may be under the control of a central processor. However, in
the case of an industrial complex with miles of process piping with
instrumentation, and many valves, fittings, elbows, and flanges, sampling
is typically infrequent, occasional, or intermittent. This is especially
so in the case of sampling fugitive emissions.
Gaseous fugitive emissions, like all gaseous pollutants, are detected by
their chemical nature. In the case of halocarbon and hydrocarbon gas
fugitive emissions techniques such as gas chromatography, flame
ionization, photo ionization, infrared techniques, and the like are
typically used.
Typically, volatile organic compound detection systems operate on
photoionization and infrared principles in the concentration ranges of
from less then 100 ppmv to more then 10,000 ppmv. Volatile organic
compound detectors are described, for example, by Menzies, K. T. et al,
"Evaluation of Potential VOC Screening Instruments," U.S. Environ. Prot.
Agency, Res. Dev., (Rep), EPA, 1983, EPA-600/9-83-003, Incineration Treat.
Hazard. Waste: Proc. Annual Res. Symp., 8th; PB83-210450, pp. 143-158,
CA:100:161189s. Other volatile organic compound detectors include flame
ionization detectors, as described, for example in Summers, C. H. et al.,
k"Use of Portable Instrumentation For the Monitoring of Fugitive Organic
Emissions from Hazardous Waste Incinerators," Report, 1984,
EPA-600/2-84-103, CA:102:11494q, and Lawes, H., "Detecting, Locating, and
Measuring of Organic Chemical Fugitive Emissions," Int. Env. Saf., 1980
(Apr.), pp. 7-10, CA:93:209408d.
For fugitive emission sampling purposes, the measurement may require the
determination of the temperature, concentration, and characteristics of
the gas contaminants. Adequate data collection also requires the mass
rates of emission of each contaminant. This requires that concentration
and volumetric flow rate data be taken.
Fugitive industrial emissions are typically sampled in the air space around
fittings, pumps, valves, flanges, hoods, small stacks, and the like. Most
commonly fugitive industrial emissions are non-condensable hydrocarbons
and halocarbons, relatively free of particulates. In the sampling of
noncondensable gases free of particulates, the gases are extracted by a
single-point grab sample, a single-point integrated sample, or a
multipoint integrated sample. Typically, the sampling probe is fabricated
of stainless steel, borosilicate, quartz glass, aluminum, copper, or
Teflon. The sample is drawn into the sample probe by a one-way squeeze
bulb that is attached to the probe. A glass or Pyrex-wool filter may be
inserted in the probe tip to remove any unwanted particulates.
In more elaborate systems a pump first sucks the gas through a cold trap.
This dries the gas. Then the gas is drawn through a rotameter to measure
flow rate, and into the analytical apparatus.
Fugitive emission sampling and monitoring is by its very nature a
laborious, labor intensive, time consuming process. Because of the large
number of sources, that is, every pipe, valve, flange, gasket, hood,
stack, and vent, it is not practical to provide constant, on-line, real
time monitoring, with either scanned data capture or interrupt driven data
capture. To the contrary, it has been necessary to take gas sampling
equipment to each potential fugitive gas emissions source, individually
identify the source, for example by entering the source identifier on a
keyboard or numeric pad, and individually sample the source. Source sample
results would then be manually entered, for example, again using a
keyboard or numeric pad. The possibility of human error is high,
especially in inclement weather or at relatively inaccessible sites in a
factory.
Thus, a need exists for a simple system that can identify a fugitive
emission to a specific source, store the source identifier and the
emission rate, and correlate the collected data.
OBJECTS OF THE INVENTION
It is one object of the invention to provide a simple method and system for
identifying potential fugitive emission sources, measuring and storing the
fugitive emission data, as concentration or radioactivity, and correlating
the fugitive emissions with, for example, previous fugitive emissions data
from the same source or other sources.
It is a further object of the invention to provide a method and system that
allows for comparison of fugitive emission data by commodity, across
commodities, by source, across sources for a given time, or by time series
for a given source.
SUMMARY OF THE INVENTION
According to the invention there is provided a method and system for
monitoring fugitive emissions in a multi-source fugitive emission
environment, for example a complex manufacturing facility.
The method and system integrate (1) machine readable source identification
elements at each fugitive emissions source, with (2) a means of reading
these source identification elements, with (3) a means of sampling
fugitive emissions at the identified source, and with (4) a means of
correlating the source identification with the concentration,
radioactivity, or some other attribute of the sampled fugitive emission.
The machine readable elements are for identifying the source, and may be a
simple as bar code stickers. Alternatively, they may be individual ROMs
with such identification as part number, location, and gas carried.
The system also has a portable monitor that includes a reader, a detector,
and storage. Specifically, the reader reads the machine readable element
and generates a machine storable source identification signal
corresponding to the element.
In a preferred exemplification of the invention the machine readable
identification means at the fugitive emissions source is a bar code. The
reader is responsive to the bar code. That is, it reads the bar code and
generates a machine storable source identification signal corresponding to
the bar code.
The detector generates a second machine storable signal. This signal
represents, for example, the amount or some other attribute of fugitive
emissions from the fugitive emissions source.
The fugitive emissions are generally organic vapor fugitive emissions and
the fugitive emission detection means is a volatile organic compound
detector. Typical volatile organic compound detectors include photo
ionization detectors, flame ionization detectors, infrared absorbtion
detectors, and combinations of these detectors.
Finally, the portable monitor includes storage for storing the source
identification signal and the fugitive emissions signal. The portable
monitor is used in conjunction with or may even include a computer. The
computer stores identification signals and the fugitive emissions signals
and tracks the amount of fugitive emissions by source. The computer is
able to sort the fugitive emission sources by an attribute of the fugitive
emissions, for example, source, time, quantity, or composition.
In a preferred exemplification the system includes a display. This display
displays data for a plurality of fugitive emission sources, and preferably
is capable of selecting individual fugitive emissions sources, and
displaying a signal corresponding to the amount of fugitive emissions
detected at each such selected source.
Various physical configurations of the system are possible. For example,
the portable monitor and the computer may be a single unit. Alternatively,
they may be separate units.
The system and method of the invention provides a simple system for
identifying potential fugitive emission sources, measuring and storing the
fugitive emission rate, and correlating the fugitive emission with, for
example, previous fugitive emissions from the same source or other
sources.
The system and method of the invention also provide a means of comparing
fugitive emission rates by commodity, across commodities, by source,
across sources for a given time, or by time series for a given source.
THE FIGURES
The method and system of the invention may be understood by reference to
the FIGURES appended hereto.
FIG. 1 is a schematic overview of one exemplification of the system and
method of the invention.
FIG. 2 is a schematic overview of an alternative exemplification of the
system and method of the invention.
FIG. 3 is a representation of relational data base tables obtainable from
the system of the invention.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a method and system for
monitoring fugitive emissions in a multi-source fugitive emission
environment, for example a complex manufacturing facility. Such sites are
characterized by thousands of potential fugitive emission sources. These
potential emission sources must be monitored periodically for both
regulatory and maintenance purposes. The system is a complete, automated
package for monitoring fugitive emissions.
The method and system integrate (1) machine readable unique source
identification elements at each fugitive emissions source, with (2) a
means of reading these unique source identification elements, (3) a means
of sampling fugitive emissions at the identified source, and (4) a means
of correlating the source identification with the concentration,
radioactivity, or other attribute of the sampled fugitive emission.
FIG. 1 shows one exemplification of the invention. The system 1 shown in
FIG. 1 is intended to function in a multiple fugitive emission source
environment A having a plurality of potential fugitive emission sources
B', B", B.sup.iii, . . . , B.sup.n. One such fugitive emission source, B,
is a pipeline C, with a control valve D, having a bar code label, E,
associated therewith. The bar code label, E, carries the component
identification number that is unique to the component, D. This unique
identification number is usable for maintenance logging as well as
emissions logging.
The system 1, has an input means to read the identification indicia on the
source, B. This input means is illustrated as a bar code reader 11
intended to co-operate with the bar-code label, E, extending from the
control valve, D. The bar code reader 11 may be a scanner, a wand, or a
non-contact laser, as is well known in the bar code reader art.
The system, 1, further includes a sesnor, as a sub-atomic particle counter
for radioactive emissions, or a "sniffer" system for organic emissions. A
"sniffer" system 21 is shown having an organic vapor analyzer (OVA) tube
25, and an organic vapor analyzer 27. The organic vapor analyzer may be a
Foxboro 108.TM. organic vapor analyzer or equivalent. Vapor analyzers 27
typically have an analog output and require either an analog/digital
convertor (not shown) or a datalogger with analog to digital conversion
means.
The datalogger 31 is capable of receiving a signal from the bar code reader
11 and also a signal from the organic vapor analyzer 21 and converting
these signals into machine storable signals that can be stored for future
reference and analysis. One such datalogger is an OMNIDATA POLYCORDER.TM..
In the system shown in FIG. 1 the data stored in the datalogger 31 maybe
periodically uploaded to a digital computer 41 for storage and analysis.
The data may be stored in a data base or a relational data base, where,
for example, the source identification from the barcode label E provides
the relation between the measured sample attribute and system and stored
sample attributes. Typical stored system attributes include engineering
and construction data relating to the fugitive emission source, for
example, maintenance history, installation history, materials of
construction, gas contained in the system, gas temperature, gas pressure,
and gas flow rate. Typical stored sample data include leakage history over
previous samples from the same source.
In the exemplification shown in FIG. 1 the datalogger 31 is separate and
distinct from digital computer. In the exemplification shown in FIG. 2 the
data logger 31 and the digital computer 41 are contained in a single unit
42.
The machine readable elements E are for identifying the source, and may be
a simple as bar code stickers. Alternatively, they may be individual ROMs
with such identification as part number, location, and gas carried.
The reader 11 reads the machine readable element E and generates a machine
storable source identification signal corresponding to the element E.
In a preferred exemplification of the invention the machine readable
identification element E at the fugitive emissions source D is a bar code
label E. The reader 11 is responsive to the bar code. That is, it reads
the bar code and generates a machine readable or machine readable and
storable source identification signal corresponding to the bar code. This
source identification signal is stored in the datalogger 31, for example,
for direct use or for future uploading to a digital computer 41.
The detector 21, also referred to as a sensor or a "sniffer" generates a
second machine storable signal. This signal represents, for example, the
amount or some other attribute of fugitive emissions from the fugitive
emissions source D.
The fugitive emissions are generally organic vapor fugitive emissions and
the fugitive emission detection means, that is, the sniffer or sensor, 21,
is a volatile organic compound detector, also referred to as an organic
vapor analyzer. Typical volatile organic compound detectors include photo
ionization detectors, flame ionization detectors, infrared absorbtion
detectors, and combinations of these detectors.
Finally, the portable monitor includes a datalogger 31 or other storage
device for storing the source identification signal and the fugitive
emissions signal. The portable monitor is used in conjunction with or may
even include a computer 41. The computer 41 stores identification signals
and the fugitive emissions signals and tracks the amount of fugitive
emissions by source. The computer 41 is able to sort the fugitive emission
sources by an attribute of the fugitive emissions, for example, source,
time, quantity, or composition.
In a preferred exemplification the system includes a display 55. The
display 55 displays data for a plurality of fugitive emission sources, and
preferably is capable of selecting individual fugitive emissions sources,
and displaying a signal corresponding to the amount of fugitive emissions
detected at each such selected source.
Various physical configurations of the system are possible. For example,
they may be separate units as shown in FIG. 1. Alternatively, the portable
monitor and the computer may be a single unit 42 as shown in FIG. 2.
The system and method of the invention provides a simple system for
identifying potential fugitive emission sources, measuring and storing the
fugitive emission rate, and correlating the fugitive emission with, for
example, previous fugitive emissions from the same source or other
sources.
Database software associated with the system eliminates the chances for
error inherent in manual input of the data, and allows for database
management of the emissions data and its integration with construction and
maintenance data. Integration of the databases, as in a relational
database, allows use of "as built" or "up dated" drawings to quickly
locate each source identified by bar code number.
The database management system and method of the invention also provide a
means of comparing fugitive emission rates by commodity, across
commodities, by source, across sources for a given time, or by time series
for a given source.
The database management system is illustrated in FIGURE 3 which shows three
tables. The first table is the SAMPLES Table. The SAMPLES Table allows
recovery of sample data by location (barcode), date, time, and attribute,
as concentration, shown in PPMV (parts per million by volume). The second
table is the SOURCE DESCRIPTER Table. This table allows recovery of system
data by location (barcode), and includes such items as the type of
equipment, and progressively lower level descripters of the system, i.e.,
"Plant 1" and "Solvent Recovery," as well as the contents of the stream,
here CHCl.sub.3, and operating parameters, here the pressure and
temperature.
These tables were used to construct the REPORT Table, here a report for
Valve 11000001, which shows the parts per million by volume of CHCl.sub.3
in the vicinity of the valve. The trends shown by this type of comparison
could be utilized for predictive maintenance or preventive maintenance.
The relational database could be further integrated with a CAD or
engineering database, to relate the barcodes to the locations of the
specific hardware within the industrial complex.
While the invention has been described with respect to certain preferred
embodiments and exemplifications, it is not intended to limit the scope of
the invention thereby, but solely by the claims appended hereto.
* * * * *
|
|
 |
|
 |
Description |
|
