U.S. patent application number 14/680214 was filed with the patent office on 2015-07-30 for smart methane monitor.
This patent application is currently assigned to HEATH CONSULTANTS, INC.. The applicant listed for this patent is HEATH CONSULTANTS, INC.. Invention is credited to Steve Chancey, James Rutherford, Paul Wehnert.
Application Number | 20150211885 14/680214 |
Document ID | / |
Family ID | 44760531 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150211885 |
Kind Code |
A1 |
Rutherford; James ; et
al. |
July 30, 2015 |
SMART METHANE MONITOR
Abstract
A method and apparatus for the detection of methane gas
including a low-cost low-power infrared methane sensor integrated
with a smart energy network endpoint node, a volume corrector, or
an electronic data recorder for transmission of alarm conditions
and detector data between the instrument and a remote gas utility
company. An independent gas calibration/verification cell may be
included in the methane detector for periodically testing the
functioning and calibration of the infrared sensor. An infrared
carbon monoxide sensor aid associated calibration/verification cell
may also be installed with the methane sensor.
Inventors: |
Rutherford; James; (Cypress,
TX) ; Wehnert; Paul; (Kemah, TX) ; Chancey;
Steve; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HEATH CONSULTANTS, INC. |
Houston |
TX |
US |
|
|
Assignee: |
HEATH CONSULTANTS, INC.
Houston
TX
|
Family ID: |
44760531 |
Appl. No.: |
14/680214 |
Filed: |
April 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12758627 |
Apr 12, 2010 |
9030329 |
|
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14680214 |
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Current U.S.
Class: |
340/870.03 |
Current CPC
Class: |
G08B 25/10 20130101;
Y02B 70/34 20130101; G01D 4/002 20130101; H04Q 9/00 20130101; G08B
21/16 20130101; Y04S 20/30 20130101 |
International
Class: |
G01D 4/00 20060101
G01D004/00; H04Q 9/00 20060101 H04Q009/00; G08B 21/16 20060101
G08B021/16 |
Claims
1. A natural gas distribution system comprising gas utility
apparatus of a gas utility company which supplies natural gas to a
plurality of consumer locations via a natural gas distribution
system, said apparatus including a service computer system (80)
which is connected to a communications network, a plurality of
methane detectors (30) disposed so that each of said plurality of
consumer locations has at least one of said plurality of methane
detectors, each of said plurality of methane detectors having a
low-power, low-bandwidth radio transceiver, an infrared light
source (231), an infrared light detector (233) disposed so as to
receive light from said infrared light source, and a sampling
chamber (232) disposed between said infrared light source and said
infrared Sight detector, smart energy communication networks (10)
that link each of said plurality of methane detectors (30) with
said communications network for communication with said service
computer system (80) of said gas utility company, said smart energy
communication networks (10) each including a network coordinator
(20) in communication with said internet (70) for communication
with said service computer system (SO) of said gas utility company,
said plurality of network coordinators (20) placed at one of said
consumer locations so that each of said plurality of methane
detectors (30) is in wireless communication with at least one of
said plurality of network coordinator (20), circuitry disposed in
each of said methane detectors (30) which is arranged and designed
to notify said service computer system (80) of said gas utility
company of high methane gas conditions via said smart energy
communication network (10), and a display device (31) disposed in
one of said consumer locations, said device (31) being in wireless
communication with one of said plurality of network coordinators
(20) via said smart energy wireless network (11), said display
device designed for displaying said methane gas conditions detected
by said at least one of said plurality of methane detectors.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/758,627, filed Apr. 12, 2010, and allowed
Jan. 8, 2015.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to remote monitoring
systems, and in particular to remote methane monitoring systems for
the purpose of detecting the presence of natural gas leaks within
residential, commercial, and industrial facilities.
[0004] 2. Background Art
[0005] Natural gas utility companies operate approximately 61
million customer gas meters in the United States alone, supplied by
over one million miles of pipeline, 17 hundred transmission
stations and 17 thousand compressors. To help maintains security
and integrity of this vast distribution system, the natural gas
utility industry installs volume correctors and electronic data
recorders at compressor stations, metering stations, step-down
stations and meter vaults, for example, which provide trend data
about the functionality of the distribution system. A volume
corrector is typically installed with a gas meter. The volume
corrector accurately measures the pressure and temperature of the
gas and corrects the volume flow estimation from the gas meter
using ideal gas law calculations. Similarly, an electronic data
recorder accurately measures pressure and temperature and stores
the information. Both types of installments communicate the stored
results to the utility company using proprietary supervisory
control and data acquisition (SCADA) systems modulated over plain
old telephone service (POTS).
[0006] Gas pipelines are also subject to regular inspections to
detect leaks. Routine periodic leak surveys are costly, and it is
estimated that the natural gas distribution and transmission
industry spends over $300 million annually to survey the pipeline
network for leaks. Moreover, because gas leaks may occur at
appliances or within interior distribution piping on the consumer
side of the gas meter, utility pipeline surveys are of limited
effect.
[0007] Gas explosions due to leakage and accumulation of natural
gas in end-user buildings are an unfortunate and too frequent
occurrence. Currently, like smoke detectors, heat detectors, carbon
monoxide detectors and water sensors, there exists several types of
discrete natural gas sensors that may be installed in homes or
commercial buildings that notify occupants when there is a
predetermine minimum concentration natural gas in the atmosphere.
Such natural gas detectors are typically stand-alone alarms that
sound a warning when triggered so that the occupants may safely
evacuate. However, some models include relay contacts so that they
can be wired into a central alarm or home security system. A
security monitoring service may then notify authorities in the
event an alarm is triggered.
[0008] Natural gas detectors may rely on varying detection methods
and principles. For example, combustible gas indicators (CGIs) work
on the principles of catalytic combustion and thermal conductivity
of a gas sample and thus sense virtually all combustible gases.
CGIs arc low-sensitivity devices that are generally unable to
detect gas mixtures much below the lower combustible concentration
limit. A more sensitive leak detector commonly used is the flame
ionization detector (FID). The FID operates on the principle of
measuring the ionic concentration produced in a flame horning
carbon compounds. Like the CGIs, FIDs sense hydrocarbon gases.
While the CGI typically measures gas concentration in percentage,
the FID typically measures gas concentration in parts per million
(ppm). The CGI and FID both typically use an extractive sample or
measurement path. In this method, target gas concentration is
measured by a detector installed in a measurement chamber through
which gases of interest are continually drawn from the immediate
surrounding atmosphere.
[0009] The optical methane detector (OMD.TM.) operates by
absorption of infrared (IR) light by methane. Because natural gas
primarily contains methane gas, detection of methane gas serves for
detection of natural gas. It is a well known spectroscopic
principle that gas molecules absorb energy in narrow bands
(sometimes referred to as absorption lines) surrounding specific
wavelengths in the electromagnetic spectrum. For example, methane
has strong absorption bands at 133 .mu.m, 1.66 .mu.m, 3.3 .mu.m,
and 7.6 .mu.m. At wavelengths falling even slightly outside the
narrow absorption band, there is essentially no absorption. Thus,
an OMD measures the attenuation of an infrared light source passing
through a gas sample at the methane-characteristic absorption
wavelength to determine the presence of methane gas. An OMD is more
selective than either a CGI or a FID, because it measures methane
specifically and not all combustible gases. OMDs generally use a
short open path sample method, which eliminates the sampling time
delay associated with extractive sampling method of CGIs or FIDs.
In a short open path configuration, the light source is transmitted
across a line of sight and is either reflected to an optical
detector by a fixed reflector of known characteristics located only
a short distance from the light source or the light is received
directly by a fixed detector located only a short distance away
from the light source. OMD sensitivity in detecting methane is of
the same order of magnitude as a FID.
[0010] A laser methane detector is a prior-art device that operates
on the same absorption spectroscopy principle as an OMD but uses a
rapidly and specifically-tunable wavelength-modulated diode laser
as a light source. By sweeping the laser wavelength between a
non-absorption band and a particular absorption band of a target
gas molecule and monitoring the reflection measurements during the
wavelength sweeps, both the background transmittance over the laser
beam's path and the concentration of target gas molecules
integrated within the laser beam's path can be accurately
determined. A laser methane detector is thus well-suited for
utility company pipeline surveys, because a fixed sample chamber is
not required and accurate measurements can be made over long and
widely-varying path lengths.
[0011] However, CGIs, FIDs, OMDs, and laser detectors are generally
considered to be too expensive to be widely accepted for home use
and thus find limited use, typically in potentially hazardous
industrial locations. Current sensors widely used in home natural
gas detectors are based on electrochemical catalytic
semiconductors, whose electrical properties are altered in the
presence of various hydrocarbon gases. These sensors are
inexpensive, but they have significant performance limitations.
Electrochemical catalytic semiconductors are unstable, prone to
drift, and subject to false alarms due to moisture or household
chemicals. The sensors, which are easily contaminated by household
chemicals, have a relatively short life span. Additionally, there
is no practical way for the home owner to test the calibration and
functioning of the detector. As a result, the homeowner is at risk
that the methane sensor may frequently trigger false alarms or may
not alarm at all when a detectable hazardous condition is
present.
[0012] Although state and federal safety commissions are
increasingly urging the use of natural gas monitors, there is
currently little utility company monitoring of detectable
atmospheric gas levels at the end-user locations. Low cost
electrochemical semiconductor methane sensors are too prone to
false alarms, and more reliable detectors have been too expensive
to deploy. Perhaps a more significant barrier has been the lack of
a low cost reliable infrastructure through which a multitude of
methane detectors can communicate back to the utility company.
[0013] If reliable methane monitors are widely deployed at a gas
utility company's end-user locations and each monitor automatically
notifies the gas utility company of actual pending dangers,
proactive steps may be taken by the utility company to alleviate
the danger before a catastrophe occurs.
3. Identification of Objects of the Invention
[0014] Therefore, a primary object of the invention is to provide a
cost-effective system and method for utility-provider-monitoring of
actual atmospheric gas levels at various distribution system and
end-user locations, including residential, commercial and
industrial buildings.
[0015] Another object of the invention is to provide a methane
detector that uses Smart Energy.TM. communication networks for
compatibility, rapid deployment, and low cost.
[0016] Another object of the invention is to provide a method and
apparatus for monitoring natural gas levels that provides the
ability to monitor the gas level at a remote installation.
[0017] Another object of the invention is to provide a method and
sensor for monitoring natural gas levels in which the functioning
of the sensor can be automatically or remotely tested and
calibrated, and if not working properly, notification can
automatically be provided to the end-user and to the gas
company.
[0018] Another object of the invention is to provide a method and
sensor for monitoring natural gas levels in which the results of
sensor self-tests are further analyzed to project the need for
service.
[0019] Another object of the invention is to provide a method and
sensor for monitoring the atmosphere in remote locations in which
carbon monoxide gas and natural gas levels may be present.
[0020] Another object of the invention is to provide a volume
corrector with integrated methane detector that communicates with a
gas utility company.
[0021] Another object of the invention is to provide an electronic
data recorder with integrated methane detector mat communicates
with a gas utility company.
[0022] Another object of the invention is to provide a tire alarm
with integrated methane detector that communicates with a gas
utility company.
SUMMARY OF THE INVENTION
[0023] The objects described above and other advantages and
features of the invention are incorporated in a first embodiment in
a method and system for the detection of methane gas including a
low-cost low-power infrared methane sensor integrated with a smart
energy network endpoint node for data transmission between die
instrument and a remote gas-utility company.
[0024] In a second embodiment of the invention, a low-cost
low-power infrared methane sensor is integrated with a volume
corrector or an electronic data recorder.
[0025] An independent gas calibration ceil may be included in the
methane detector for periodically testing the functionality and
calibration of the infrared sensor. An infrared carbon monoxide
sensor may also be installed with the methane sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The invention is described in detail hereinafter on the
basis of the embodiments represented in the accompanying figures,
in which;
[0027] FIG. 1 is a functional schematic diagram of a smart methane
monitoring system according to a first embodiment of the invention
that is integrated with a wireless smart energy network, which is
in turn linked to a hardwired local area network for communicating
with a gas utility company via the internet;
[0028] FIG. 2 is a functional schematic diagram of the smart
methane monitoring system of FIG. 1 showing an alternate interface
linking the wireless smart energy network to the hardwired local
area network;
[0029] FIG. 3 is a functional schematic diagram of a smart methane
monitoring system according to a second embodiment of the invention
that is integrated with a wireless smart energy network linked to a
wireless local area network for communicating with a gas utility
company via the internet;
[0030] FIG. 4 is a functional schematic diagram of a smart methane
monitoring system according to a third embodiment of the invention
showing a methane detector included as a device within a local area
computer network for communicating with a gas utility company via
the internet;
[0031] FIG. 5 is a perspective view in partial cross-section of a
smart home of a subscriber to a natural gas provider according to a
preferred embodiment of the invention showing a smart energy home
area network implemented according to the embodiment of FIG. 2,
including a smart energy-enabled gas meter, a status indicator, and
a smart methane detector; and
[0032] FIG. 6 is a schematic diagram of a remote volume corrector
or an electronic data recorder integrated with a methane detector
according to a fourth embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
[0033] FIGS. 1-3 illustrate exemplar "Smart Energy.TM." or "Smart
Grid" networks 10 according to a preferred embodiment of the
invention. "Smart Energy" is a relatively new and rapidly
developing technology being embraced by a number of utility
companies. Smart energy offers utility companies secure,
easy-to-use wireless home area networks (HAH) for implementing
energy management programs under anticipated government mandates to
control or ration the distribution of energy. Smart energy allows
utilities to directly communicate with smart meters, thermostats,
load control devices, and other-smart appliances of end users.
Advanced metering is available for multiple energy commodities
including electricity, natural gas and water. Advanced metering,
which allows multiple measurement types such load profile, power
factor, summation, demand and tiers, can provide real-lime
consumption information to both the consumer and the utility.
Demand response and load control is a smart energy technique for
scheduling disconnection, reconnection and/or adjustment of
multiple specific groups of devices including furnaces, heat pumps,
air conditioning units, water heaters, and lighting. For example,
during peak demand periods utilities can automatically adjust set
points on programmable communicating thermostats or can turn off
large appliances such as air conditioning units, swimming pool
pumps, ovens, ranges, and resistance heaters.
[0034] Smart energy network 10 includes a wireless network 11 over
which various locally distributed smart-energy-compliant sensors
and devices communicate. Wireless network 11 ideally complies with
IEEE 802.15.4 wireless and ZigBee.TM. communication protocol
specifications using the Smart Energy.TM. profile. IEEE 802.15.4
wireless specification calls for operation in the unlicensed
industrial, scientific and medical (ISM) radio bands--915 MHz in
the USA and Australia, 868 MHz in Europe, and 2.4 GHz in most other
locations worldwide. Binary phase shift keying (BPSK) modulation is
used in the 915 and 868 MHz bands, and orthogonal quadrature phase
shift keying (QPSK) is used in the 2.4 GHz band to achieve an
uncorrected data rate of 40 kbit/s per channel in the 915 MHz band,
20 kbit's in the 868 MHz band, and 250 kbit's per channel in the
2.4 GHz band, respectively. Transmission range extends up to
between 125 and 250 feet.
[0035] ZigBee is a specification for a suite of high level
communication protocols for use with small, low-power digital
radios to form wireless personal area networks (WPANs) or home area
networks (HANs). ZigBee is suitable for low-power low-bandwidth
applications. Because ZigBee is an open standard, it supports a
competitive marketplace of multiple vendors, which lowers cost.
ZigBee certified devices ensure interoperability, and its robust
ability for automatic network registration, using either
pre-installed cryptographic keys or standard public keys, provides
a flexible secure network that is simple to use. In addition to
home and industrial automation and control, ZigBee is widely used
for smart energy technology.
[0036] ZigBee radio transceiver chips are commercially available
with integrated microcontrollers, typically up to 256 kBytes of
flash memory, and a prepackaged ZigBee software stack. The ZigBee
protocol enables a general-purpose, self-organizing ad hoc mesh
network of nodes that communicate using a "carrier sense, multiple
access/collision avoidance" scheme. Simply put, the nodes
communicate within the network in the same manner that polite
people converse--before transmitting, each node briefly "listens"
to the network to ensure no other node is actively
transmitting.
[0037] The base of wireless network 11 is a ZigBee network
coordinator 20. Coordinator 20 creates and manages wireless network
11, storing information about each node in the network including
security keys. FIG. 1 shows three ZigBee end devices 30, 31, 32
forming the other nodes of wireless network 11, although a greater
or lesser number of devices may actually be present in any
particular network 11. A ZigBee end device need contain just enough
functionality to communicate with coordinator 20 and need not relay
data from other end devices. This simplicity reduces production
costs and allows an end device 30, 31, 32 to remain in a low-power
dormant mode a significant amount of time, thus enhancing battery
life.
[0038] ZigBee end device 30 is a methane detector that is
integrated with ZigBee interface electronics and implements the
Smart Energy.TM. profile. Methane detector 30 is powered from a
standard household power outlet and has a battery backup, although
other power configurations may be used. Methane detector 30 is
preferably able to detect a level of methane of about 500 ppm,
notify the building occupants of an alarm condition and
concurrently notify the gas utility company via the smart energy
network 10. In a preferred embodiment, methane detector 30 uses an
infrared sensor that operates on well-known spectroscopy
principles. By using IR sensors, high selectivity, stability,
long-life and low false-alarm-rate methane detectors 30 are
obtained. More preferably still, methane detector 30 uses
non-dispersive infrared (NDIR) sensors, although laser-based,
opto-acoustic, LED, or fiber optic sensors may also be used as
appropriate.
[0039] A NDIR methane sensor includes an IR source, a transparent
sample chamber, an optical filter, and an IR detector. All
wavelengths produced by the IR source are directed through the
sample chamber toward the IR detector. The optical filter, which
eliminates all light except for one or more of the characteristic
absorption wavelengths of methane gas and/or carbon monoxide, is
placed directly in front of the IR detector. Recent advancements in
IR detectors and sources have enabled the development of lower cost
NDIR sensors. As IR sensors are understood by routineers in the
art, the topic is not discussed further herein.
[0040] In a preferred embodiment, a independent calibration gas
cell is included in detector 30 and is used to test the
functionality, calibration and alarm verification of the infrared
sensor. A hermetically sealed glass vile is temporarily placed
within the light path of the sensor. This calibration cell contains
a known concentration of methane gas and/or carbon monoxide.
Calibration readings are periodically taken. For example, detector
30 automatically performs routine self-tests. Detector 30 may also
be remotely commanded via network 10 to perform a self-test. The
results of the calibration/verification checks are compared to
internally stored presets. If detector 30 is not working properly,
notification is provided to the homeowner and/or to the gas utility
company. Self-test results may also be transmitted to the gas
utility company for further analysis to project the need for
detector service. In another embodiment using a laser based IR
sensor, a self test and calibration may also include measurement
and adjustment of a laser's wave length.
[0041] An optional infrared-based carbon monoxide sensor may also
installed with-the methane detector 30 for detection of both carbon
monoxide and natural gas. In this configuration, a dedicated carbon
monoxide calibration/verification cell may be included, or a single
calibration/verification cell that includes known concentrations of
both carbon monoxide gas and methane may be used.
[0042] ZigBee end device 31 is a display unit that is integrated
with ZigBee interface electronics. Display 31 is programmed to
display the methane gas concentration detected by methane detector
30. Display 31 may indicate gas concentration in ppm or percent of
lower explosive limit, for example.
[0043] ZigBee end device 32 is shown as a generic utility meter,
such as an electricity, gas or water meter, which forms no part of
the present invention but is illustrated as being a node in a
typical smart energy network 10.
[0044] Coordinator 20 bridges the ZigBee wireless network 11 with a
standard computer network 12, which is typically a IEEE 802.3
hardwired Ethernet local area network (LAN) as shown in FIGS. 1 and
2 or a wireless IEEE 802.11 WiFi wireless local area network (WLAN)
as shown in FIG. 3.
[0045] In FIG. 1, coordinator 20 employs a Texas Instruments.RTM.
CC2530 or equivalent ZigBee radio chip. The TI CC2530 offers dual
universal synchronous/asynchronous receiver/transmitter (USART)
interfaces. For this reason, coordinator 20 of FIG. 1 employs a
serial computer interface 21, such as a ES-232, RS-422, RS-485,
IrDA, or USB interface. An Ethernet-to-serial converter 40, such as
one commercially available from Lantronix.RTM. or NetBurner,.RTM.
links coordinator 20 to LAN 12. In FIG. 2, coordinator 20 includes
onboard circuitry to provide an Ethernet interface, such as a
10-Base-T interface, and is thus connected directly to LAN 12. In
FIG. 3, coordinator 20 includes onboard circuitry to provide WiFi
connectivity for bridging to WLAN 12.
[0046] Computer network 12 may include an optional computer 50.
Computer 50 includes a webpage postal or similar software by which
an operator or a homeowner, for example, may view the status of
smart energy network 10, including the real-time status of smart
methane monitor 30. The webpage portal may include password
protection.
[0047] Computer network 12 includes an internet gateway 60 such as
a cable or digital subscriber line (DSL) modem. Internet gateway
preferably includes router functionality for multiple network
connections. As computer and internet networking are well known in
the art, the topic is not discussed in further detail herein.
[0048] Although FIGS. 1-3 each illustrate only one local smart
energy network 10, a large number of individual local smart energy
networks 10 are contemplated--ideally one for each building served
by a gas utility company. The gas utility company provides one or
more server computer systems 80 that are connected to the internet
70 for monitoring the large number of customer smart energy
networks 10. When a smart methane detector 30 in one of the smart
energy networks 10 generates a high-methane-level alarm, the
detector 30 transmits that alarm status to utility server 80. Upon
receiving the alarm, the gas utility company can then respond by
dispatching service technicians to shut off the electric and gas
service and notify local fire departments, etc. Smart methane
detector 30 may also be programmed to contact the customer calls in
an alarm condition, such as by telephone calls to POTS lines, cell
phones, SMS text messaging, email, Twitter.TM., Facebook.TM.,
MySpace.TM., or a Smartphone.TM. application.
[0049] FIG. 1 illustrates a first method for back-up communications
using a POTS modem 90 should the broadband internet connection 71,
gateway 60, or network 12 fail. In the event of an alarm condition,
coordinator 20 establishes a dial-up connection 22 directly with
utility company server 80. Preferably server 80 includes a number
of POTS modems and incoming dial-up lines for supporting a number
of emergency dial-up calls at a time. Modem 90 may be internal to
or external from coordinator 20.
[0050] FIG. 2 illustrates a second method for back-up
communications using a POTS modem 90 should the broadband internet
connection 71 fail. Gateway 60 is configured to automatically
establish a dial-up connection 72 to an internet service provider
using modem 90 whenever it detects a failure of broadband
connection 71. In this manner, the back-up internet connection is
transparent to the ZigBee coordinator 40 and wireless network 11.
Modem 90 may be internal to or external from gateway 60.
[0051] Although the preferred embodiment of the invention is
described as employing a ZigBee-compliant wireless network 12,
WiFi, Bluetooth or other types of wireless networks 12 may also be
used between methane detector 30 and internet 70 as appropriate.
For example, FIG. 4 illustrates an alternate embodiment of a smart
energy network 10' in which methane detector 30' and display 31'
communicate using an IEEE 802.11 wireless WiFi standard. As such,
methane detector 30' and display 31' are linked directly with
gateway/router 60.
[0052] FIG. 5 depicts how the smart energy network 10 of FIG. 2
might be implemented within a typical house 100. Smart methane
detectors 30 are located near gas appliances. For example, a first
methane detector 30A for a carbon monoxide detector, for example)
is located in the basement adjacent to a gas furnace 102 and water
heater 104, and a second methane detector 30B is located in the
kitchen near a gas range 106. Additional methane detectors and/or
carbon monoxide detectors (not shown) may be located in a laundry
room, utility room, attic, or garage, for example. Coordinator 20,
computer 50 and gateway/router 60 are located in a home office,
although a bedroom, library, study, conservatory, home theatre or
any other convenient location may be used, provided coordinator 20
is located within wireless range of all of the smart energy end
devices. Display unit 31 is placed in a prominent location in the
kitchen, although it or additional display units may be located
near a thermostat 120, an alarm panel, intercom station, or other
annunciator device. A smart energy enabled thermostat 120 and smart
energy gas meter 130 are shown.
[0053] FIG. 6 illustrates a methane detector system according to
another embodiment of the invention in which a low power methane
detector 230 is integrated into a flow corrector or electronic data
recorder 200 for use in metering stations, step-down stations and
similar remote locations within a natural gas distribution system.
Volume corrector or electronic data recorder 200 includes one or
more pressure transducers 202 and a temperature probe 204, the
signals from which are conditioned by analog circuitry 206, sampled
by an analog-to-digital converter (ADC) 208, and stored as digital
data in memory 210. Digital pulses from a gas meter 212 are also
collected. A microcontroller or microprocessor 214 coordinates the
collection and transmission of data and may perform volume
correction calculations. A POTS modem 290 is connected to volume
corrector or electronic data recorder 200 for interfacing the
device to the SCADA system of a gas utility company, although other
data transmission methods may be used including a broadband
internet gateway, frame relay service, cellular telephone, text, or
G3 internet service, or other radio communication. Volume corrector
or data recorder 200 typically includes a display 216 and a battery
218.
[0054] Like methane detector 30, 30' of FIGS. 1-5, methane detector
230 is preferably an IR OMD such as an NDIR detector. Detector 230
includes an IR light source 231 (which may be a laser or LED), a
sample chamber 232, and an IR detector 233. In the case of a
non-monochromatic light source 231, detector 230 also includes one
or more optical filters 234. An optional calibration cell 236 may
be included, which may be selectively positioned into the detection
optical path in place of sample chamber 232. Detector 230
interlaces to ADC 208 via analog signal conditioning circuitry 238.
Processor 214 is programmed to record methane levels, to transmit
high-methane-level alarms to the gas utility company, and to
control which gas cell--sample chamber 232 or calibration cell
236--is positioned in the measurement optical light path. Detector
230 may also include a carbon monoxide detector as discussed above
with respect to methane detector 30.
[0055] The Abstract of the disclosure is written solely for
providing the United States Patent and Trademark Office and the
public at large with a way by which to determine quickly from a
cursory reading the nature and gist of the technical disclosure,
and it represents solely a preferred embodiment and is not
indicative of the nature of the invention as a whole.
[0056] While some embodiments of the invention have been
illustrated in detail, the invention is not limited to the
embodiments shown; modifications and adaptations of the above
embodiment may occur to those skilled in the art. Such
modifications and adaptations are in the spirit and scope of the
invention as set forth herein:
* * * * *