Remote CH4 Measurement Final_Presentation[1] s 711

8/6/2019 Remote CH4 Measurement Final_Presentation[1] s 711

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emote Wireless Monitoring ofemote Wireless Monitoring ofethane for Landfills and Septicethane for Landfills and SepticSystemsystemsack Driscollack Driscoll : , ( . )ID Analyzers Sandwich MA 02563 pidguy@aol com: , ( . )ID Analyzers Sandwich MA 02563 pidguy@aol com , , , ,yungsue Han Walter Johnson Jiwoon Kim Francesca Little, , , ,yungsue Han Walter Johnson Jiwoon Kim Francesca Little, ,ol Perov Natalia Perova James Porter, ,ol Perov Natalia Perova James Porter: , (uffolk University Boston MA 02114: , (uffolk University Boston MA 02114 .johnson@suffolk edujohnson@suffolk edu)# -resented at Pittsburgh conference Paper 250 45P 2009# -resented at Pittsburgh conference Paper 250 45P 2009#PittconPittcon
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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ObjectiveOur goal was to develop and test awireless methane detection system for

monitoring of methane production in

.landfills and septic systems Nitrogen inseptic systems is a problem on Cape Codbecause the majority of sewage is handled

.by septic systems We were interested inmeasuring methane levels produced by

septic systems to determine if sufficientquantities were available for capture and

.reuse in the system to remove nitrogen


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PID Analyzers, LLC copyright 2003-2006

-ypes of Sensors CG Two heated catalytic

elements are set in a; ;block one is sealed

the other is incontact with the.sample Each is in a

leg of a Wheatstone.Bridge circuit If thesample contains

hydrocarbons orcombustible inorganic

,compounds they will

burn increasing the

temperature of thesensors and changing

.the resistance Thechange in resistance

is proportional to the.concentration


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Electrical Schematic for

System


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ethane Data MonitoringSystemThe CH4sensor is connected to an amplifier

board which then transfers the signal to a radio

frequency mote for transmission to the base.computer in a nearby building

There is a solar powered battery box thatsupplies poser to the sensor and amplifier

. .circuit The layout is shown in the diagram


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ensor and Amplifier%The sensor head has a range of 0 to 5methane and constitutes half of a

. Wheatstone bridge circuit The output

% .voltage is about 10mV per methaneThe second part of the bridge is part ofthe amplifier board which amplifies the

differential signal by 10 or 100 times

( ).gain controlled by a switch The outputgoes to an input of the analog to digital

converter board MDA300 which is attached.to the Crossbow mote MICA2


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F Crossbow Mote/ ( )The microcomputer RF transmitter mote sendsdata at 433 MHz to a base computer located in.an office about 50m away

-The mote is programmed to operate in a lowpower mode in which it sleeps most of the( )time low power and awakes every 5 minutes

for 30 seconds to take measurements and send

. .data It can run several months on two 1 5 V

.AA batteries

The data packet from the mote contains the, ,mote battery voltage humidity and temperature

.inside the mote box


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ote Box and PowerThe mote and amplifier board are enclosed- (in a weather proof box see yellow box in) .figure sitting outside the septic tank

( )The sensor head inside the tank is at the

.end of a 1 to 2 m 3 wire cable

,The amplifier together with the sensor head, +when activated draw 110 mA from a 6 volt

-battery source but only 7mA from a 6 volt

.source This power is provided by a solarpowered battery box connected to the mote

( )box by a cable see diagram


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elay ControlThe MDA300 board attached to the mote has several

analog inputs and a relay that can be used to.control the sensor circuit When the mote wakes up

to take data it closes this relay and supplies 6. +volts to other relays These relays connect the 6

-v and 6V to the amplifier and the sensor for 30. ( )seconds Response time of the sensor is 10 sec

,At the end of this time the mote measures the,output voltage of the amplifier broadcasts the

,data opens the relays to disconnect the

, .batteries and goes back to sleep

This mode of operation decreases the powerconsumption of the board by about a factor of ten

.compared to continuous supply of power


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olar PanelArrangement, ,Four solar panels 3 x 5 were fixed tothe top of the battery box to maintain the

+ - .6V and the 6V needed by the electronics,In full sun each panel can supply up to

.70mA at 7V The largest consumer was the+6V battery source so this was monitoredby using on e of the analog inputs to the

.MDA300 board attached to the mote

The graphs show that the solar panels aresufficient to keep the batteries charged

.even in harsh winter conditions


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uture plans We will use a temperature controlled box with

( )air no methane to study changes in outputvoltage as a function of temperature and time

.over a period of months This will allow us tocheck the drift of the sensor and determine the

.time intervals needed for recalibration

We will also place a thermocouple at thelocation of the methane sensor as an additional

input to the mote to monitor ambient.temperatures inside the septic tank This will

help in understanding methane productioninside the septic system in different

.environmental conditions


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Conclusion- We have developed and demonstrated a solar

powered wireless methane data collection.system The data are consistent with sewage

flow conditions as stated by the septic test

.facility This device will allow thefacility to determine detailed behavior ofdifferent types of septic systems and test

the viability of collection and reuse of

methane to eliminate nitrogen from septic

.systemsAcknowledgements : We are veryappreciative of the assistance of

personnel at the Barnstable County

Alternative Septic System Test Center

Remote CH4 Measurement Final_Presentation[1] s 711

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