Sensors and systems for combustion technology System ... - lamtec

System overviewLambda Transmitter LT3KS1D combination probefor the simultaneous measurement of oxygen (O 2 )and oxidising components (CO/H 2 )LambdaTransmitter LT3Combination probeKS1D3 5 7 9LSB2 4 6 8NotebookO CO/H 2 2USBLAMTEC SYSTEM BUSOperationserviceto furtherLAMTEC devicesETAMATIC / BT300Digital and analogueinputs and outputsOption:ModbusPROFIBUS DPEthernetWriterRecordingSensors and systemsfor combustion technology

Theoretical foundations of the KS1D measuringprincipleThe basis of the KS1D combination probe is a heatedelectrochemical measuring cell made of zirconiumdioxide ceramic.It has 3 electrodes:• O 2 -sensitive platinum electrode• CO/H 2 -sensitive electrode made from a platinum /gold alloy• Platinum reference electrodeSupplying the external electrode with a sample gas andthe internal electrode with a reference gas of familiar O 2concentration, e.g. air (20.96 %O 2 ), with a continuousconstant temperature, results in the logarithmicassociation between the probe voltage U and the oxygenconcentration on the sample gas, as shown below.1 2 34U S5 6 7Fig. 1 Schematic structure of the KS1D combination probe1 Gas inlet2 Protective coat3 Heating element4 Working electrode (Pt/Au)5 Zirconium dioxide ceramic6 Reference electrode7 HousingThe O 2 measuring cell works as an electrochemicalconcentration change and generates a direct voltagewhich is dependent on the absolute temperature T andthe logarithm of the O 2 concentration ratio or the O 2partial pressure ratio on the reference and O 2 externalelectrode.U HFig. 3 Sensor characteristic U = f (O 2 )Probe principle - CO/H 2 -sensitive electrodeCombustible components will be absorbed like oxygenmolecules on the electrode and diffuse to the "threephaseboundary", formed by sample gas, electrode andzirconium dioxide.Alongside Nernst voltage U O2 which is determined by theoxygen content, the combustible components in thesample gas generate an auxiliary direct voltage U CO/H2 .The sensor voltage is the total of the two voltagesU S = U O2 + U CO/H2 (see fig. 3).Even with low concentrations of oxidable gases, like H 2or CO, the mixed potential is considerably greater thanthat of the O 2 signal.The formation of the mixed potential takes place veryquickly, t 60 -times below 2 sec. have been achieved.CO US (mV)Sensor characteristic(measured)Electrical equivalent circuit diagramNernst characteristic(calculated)U H13V AC/DCU SO U2 SCO/H 2Fig. 2 Electrical equivalent circuit diagramincompletecombustioncompletecombustionFig. 4 Sensor characteristicO (%) 2

Lambda Transmitter LT3Microprocessor-based measuring transducer withdiagnostic functions.Fig. 5 Lambda Transmitter LT3The temperature of the KS1D flue gas probe is controlleddepending on the internal resistance of the sensor. TheKS1D combination probe is permanently monitored forfailures or missing connections. Malfunctions aredetected by the electronics and lead to a fault or warningmessage.LT3 display and operating unitA programming unit, which is connected via the LAMTECSYSTEM BUS or is already integrated in the device, isused to display and operate the LT3.• External programming unit, connection via 5-pin M12plug-in connector• Internal programming unit, built in to the doorFig. 7 LSB modules with 4 analogue outputs, type 663 R 4025(voltage) / 663 R 4029 (current)Several modules can be connected using a strappingplug:• LSB modules with 4 analogue outputs (voltage)• LSB modules with 4 analogue outputs (current)• LSB modules with 4 analogue inputs (voltage /current)• LSB modules with 4 digital outputs• LSB modules with 4 digital inputsKS1D combination probe, type 656 R 2000132Fig. 6 Programming unitLSB modulesLSB modules are external/internal input/output modulesthat are connected with the LT3 via the LAMTECSYSTEM BUS (LSB). They enable a needs-based, userspecificdesign of the LT3 and can be retrofitted at anytime. The distance from the LT3 can be up to 500 m. Thisallows a decentralised location and reduces the amountof wiring.Fig. 8 KS1D combination probe1 KS1D combination probe without housing;Standard cable length 2 m, Teflon, with connectorplug2 Gas extraction device (GED), type 655 R1001...1004 (150...1000 mm)3 KS1D combination probe in housing(incl. Item 1, 2 + 3)

Features of LT3 KS1D measuring system• Direct (in situ) measurement of oxygen (O 2 ) and oxidable exhaust gas components (CO/H 2 ) in gases, preferablyin combustion plants, in the superstoichiometric area (λ>1).• O 2 range of measuring: 0 to 21 vol.%• CO e range of measuring: 0...10.000 ppm• Independent of false air (CO e )• No gas preparation required, measurement directly in the moist flue gas• Setting time to 60 % value (T60) < 10 seconds: CO e < 2 seconds• Low heating power with LT3 15..0.18 Watt, depending on the exhaust gas temperature• Low-maintenance• Type 656 R 2000 in housing for exhaust gas temperatures < 300°C• 5-wire Teflon cable with circular connector, length 2 m• Type 656 R 2000 in housing for exhaust gas temperatures