System overview. Lambda Transmitter LT2 Lambda Probe LS2 (K) for measurement of oxygen (O 2 ) Sensors and Systems for Combustion Engineering

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1 System overview Lambda Transmitter LT2 Lambda Probe LS2 (K) for measurement of oxygen (O 2 ) Sensors and Systems for Combustion Engineering

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3 1 Advantages of the LAMTEC Measuring Principle 1 Advantages of the LAMTEC Measuring Principle The LAMTEC Lambda Transmitter is - in combination with the LS2 Lambda Probes - an universal O 2 measuring instrument for direct measurement of O 2 concentration in exhaust gases in the superstoichiometric range ( >1). It is possible to set up direct coupling with the LAMTEC fuel/air ratio control system VMS4/ VMS5, the LAMTEC combustion management system FMS4/FMS5, the LAMTEC burner control systems ETAMATIC and BT300. This allows the implementation of innovative control procedures for optimising oil and gas combustion plants, and for automatic combustion system tuning to variable combustion conditions. Also possible is the combustion of coal, dust-laden combustion gases and biomass. In addition to O 2 measurement, the Lambda Transmitter offers the following functions: Purging of the preliminary filter of the probe Measurement of flue gas and air temperature intake, and calculation of combustion efficiency Detection of unburned residue (CO/H 2 ), shown as CO equivalent (CO e ) Calculation and display of CO 2 concentration Load-dependent and fuel-specific limit curves / limit values O 2 regulation Field bus connection Advantages: No gas purification necessary, measurement directly in humid flue gas Fast adjustment time to 90% value (T 90 ) < 15 seconds with standard extraction Adjustment time to 90% value (T 90 ) < 20 seconds for probes with attribute "K" and preliminary filter Gas temperature up to 1200 C No temperature measurement of the ZrO 2 measuring cell required Low heating power Watt Universally applicable Simple handling - probe connected via plug Low maintenance 2

4 2 Measuring Principle 2 Measuring Principle Fundamentally, the Lambda Probe consists of a zirconium dioxide-ceramic electrochemical cell. The cell operates as an electrochemical concentration chain, and generates direct voltage that depends on the absolute temperature T and the logarithm of the O 2 concentration or the O 2 partial pressure ratio at the inner and outer electrodes. If the outer electrode is supplied with test gas and the inner electrode is supplied with reference gas with a known O 2 concentration e.g. air (20.96%), then assuming the temperature is held constant, we obtain the logarithmic relationship between probe voltage U O2 and the oxygen concentration of the test gas as shown below. The characteristic curves for two different temperatures T 1 and T 2 show clearly that when using the voltage probe, the temperature affects the measured value in the cell's active part. In addition, the curves show that the probe is preferentially suitable for measuring low oxygen concentrations, since sensitivity and accuracy increase with decreasing O 2 concentration because of the logarithmic relationship. Each Lambda Probe is factory-tested under real-life conditions, in a gas-combustion system with an exhaust temperature of approx. 150 C. The test protocol is enclosed with each probe. The sensor temperature recorded in the protocol should be input into the Lambda Transmitter during commissioning. Calibration with test gases is not required. During operation it is possible to check and compensate for the measured values through counter measurement. Fig. 2-1 Schematic construction of the ZrO 2 oxygen probe Fig. 2-2 The voltage probe's equivalent electric circuit diagram 1 Gas intake 5 Reference electrode (Pt) 2 Working electrode 6 Zirconium oxide ceramic 3 Probe heating 7 Protective layer 4 Housing The curve shown below demonstrates that oxygen measurements require knowledge of the proportionality factor and the probe's temperature. In practice this means adjusting the probe during commissioning with is possible simply through air voltage compensation (offset compensation) and entering the cell temperature which was obtained during final testing in accordance with the test protocol enclosed with the probe (usually approx K). Individual deviations are compensated during commissioning by adjusting the air voltage (offset compensation) and entering the sensor temperature which was obtained during the final testing and recorded in the test protocol. The probe can only be used in a gas temperature up to 1200 C. Probe ageing in long-term operation leads to stretching of the characteristic curve. However, this can be recognised from the fact that the internal resistance increases. The internal resistance is measured and displayed permanently by the Lambda Transmitter and controlled to limit values. NOTICE! For the O 2 measurement the calibration with test gases has been abandoned for the sake of simple handling and low maintenance. The probes are measured in the factory under operational conditions (gas combustion, exhaust gas temperature 150 C). 3 Fig. 2-3 The voltage probe's working principle

5 2 Measuring Principle Individual deviation is taken into account by adjusting the air voltage (offset compensation) and entering the obtained sensor temperature obtained during commissioning. Measurement accuracy is + 10% of reading, at best 0,25 by vol.% O 2. Fig. 2-4 Measurement and calibration diagram of the oxygen probe - the effect of temperature on the probe's characteristic curve. NOTICE! The test gas used for adjustment must be free from oxidizable constituents such as CO or NO. Oxidizable constituents will oxidize at the platinum electrode and corrupt the adjustment. LAMTEC recommends to use test gas for calibration with % by volume O 2 in N 2. 4

6 3 Lambda Probes 3 Lambda Probes With the LAMTEC Lambda Probes a measurement of O 2 concentration in exhaust gases in the superstoichiometric range ( >1) is possible in situ (directly in exhaust gas). Fig. 3-1 Lambda Probe LS2 Measurement directly in humid flue gas up to 300 C Protection class IP42 when mounting outside, the probe must bei protected from water, snow, etc. Natural gas, fuel oil EL Fig. 3-2 Lambda Probe LS2 in housing with GED and PIF Measurement directly in humid flue gas up to 300 C Protection class IP42 when mounting outside, the probe must be protected from water, snow, etc. Natural gas, fuel oil EL Fig. 3-3 Lambda Probe LS2, design HT Measurement directly in humid flue gas up to 1200 C Semi automatic calibration during operation with test gas possible Natural gas, fuel oil EL, coal, dust-laden flue gases, with option purge unit Fig. 3-4 Lambda Probe LS2-K/LS2-KV Measurement directly in humid flue gas up to 450 C Connection for reference air provided by the customer (instrument air) Semi automatic calibration (LS2-K) or fully automatic calibration (LS2-KV) during operation with test gas possible Natural gas, fuel oil EL, fuel oil S, biomass, special fuels 5

7 3 Lambda Probes Fig. 3-5 Lambda Probe LS2-KHD Fig. 3-6 Combination Probe LS2-KA Measurement directly in humid flue gas up to 450 C Connection for reference air included (instrument air) Semi automatic calibration during operation with test gas possible High dust protective pipe Natural gas, fuel oil EL, fuel oil S, coal, biomass, dustladen flue gases, special fuels Measurement directly in humid flue gas up to 450 C Connection for reference air provided by the customer (instrument air) Semi automatic calibration during operation with test gas possible High dust protective pipe with purging pre filter Natural gas, fuel oil EL, fuel oil S, coal, biomass, dustladen flue gases, special fuels Fig. 3-7 Lambda Probe LS2-KAF Measurement directly in humid flue gas up to 200 C Connection for reference air provided by the customer (instrument air), alternatively integrated pump unit for reference air Semi automatic calibration during operation with test gas possible High dust protective pipe with purging pre filter incl. additional woven filter medium Natural gas, fuel oil EL, fuel oil S, coal dust combustion, biomass, flue gases with high dust content 6

8 3 Lambda Probes Measurement directly in humid flue gas up to 500 C Connection for reference air provided by the customer (instrument air), alternatively integrated pump unit for reference air Fig. 3-8 Lambda Probe LS2-Ex Semi automatic calibration during operation with test gas possible Atex: II 2G EEx d IIB+H 2 T 3 Natural gas, fuel oil EL, fuel oil S, coal, special fuels Measurement directly in humid flue gas up to 600 C Mountings for manual purging Measurement for extreme high flue gas temperature fuels: natural gas, fuel oil EL, fuel oil S, coal, Biomasse, special fuels Fig. 3-9 Combination probe KS1D for manual purging 7

9 4 LT2 Lambda Transmitter 4 LT2 Lambda Transmitter Four basic types are available: Wall mounting housing made of sheet steel, front lockable door, impact-resistant window Wall mounting housing made of sheet steel, front lockable door, impact-resistant window with integrated reference air pump On mounting plate, for installation in a control cabinet Panel installation housing 3HE 50TE, for mounting in the control cabinet door Lambda Transmitter LT2 in wall mounting housing IP65 Sheet steel H400 x B300 x T150 mm Type 657R102 Display and operation unit as option Lambda Transmitter LT2 on mountig plate IP00 H350 x B258 x T132 mm Type 657R103 Display and operation unit as option Lambda Transmitter LT2 in panel installation housing IP20 front IP40 H172 x B310 x T270 mm (3HE, 50TE) Type 657R104 Display and operation unit (included as standard) 8

10 5 Options and Accessories 5 Options and Accessories Display and operating unit as option for wall mounting housing and mounting plate Remote display software Measurement of flue gas and intake air temperature, and calculation of combustion efficiency Calculation and display of CO 2 concentration, fuel-related calculation of the O 2 value measured and the max. CO 2 value Load-dependent and fuel-specific boundary curves/limit values Integrated PID-O 2 controller 4 Floating analogue outputs (output 1 and 2), max. potential difference 20 V, freely configurable, direct current 0/ ma, burden digital outputs in combination with relay module 657R0857 Field bus interface Housing heating Purge device Options for LAMTEC Lambda Probes Semi automatic calibration unit (available for probes with attribute "K") Fully automatic calibration unit (available for probes with attribute "KV") Reference air pump (available for probes with attribute "K" and "Ex") Purge device in combination with bypass tube (available for probes with attribute "HT") Purging of the preliminary filter (available for LS2-KA and LS2-KAF) Accessories Counter flange Accessories for flange seal GED in various lengths (for LS2, LS2-HT) Probes in various lengths (for LS2-K, LS2-KV, LS2-Ex) 9

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12 DLT aEN-001 Copyright 2013 LAMTEC The information in this publication is subject to technical changes. LAMTEC Meß- und Regeltechnik für Feuerungen GmbH & Co. KG Wiesenstraße 6 D Walldorf Phone: +49 (0) 6227 / Fax: +49 (0) 6227 / info@lamtec.de LAMTEC Leipzig GmbH & Co. KG Portitzer Straße 69 D Taucha Phone: +49 (0) / Fax: +49 (0) / Presented by: Print no. DLT aEN-001 Printed in Germany