Technical Data Lambda Transmitter LT 2-Ex Combination Probe KS1-D-Ex Simultaneous measurement of oxygen (O2) and oxidizing components (CO/H2) In preparation Sensors and systems for combustion engineering LAMTEC SYSTEM BUS Combi-Probe KS1-D-Ex O 2 CO/H 2 (Operation, Service) to further LAMTEC devices FMS / VMS / ETAMATIC LT 1 / LT 2 RS 232 Analog inputs and outputs Analog inputs and outputs Digital inputs and outputs Digital inputs and outputs Fieldbus CAN Optional LSB modules Probe Connection Unit PCU Probe connection Lambda- Transmitter LT 2Ex Hazardous area Free hazardous area
24
Embed
Technical Data Lambda Transmitter LT 2-Ex Combination Probe KS1-D-Ex · 2015. 4. 27. · Diagram showing the structure of the combination probe KS1-D-Ex The O2 measuring cell acts
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Technical Data Lambda Transmitter LT 2-Ex Combination Probe KS1-D-Ex
The Lambda transmitter LT 2Ex is a microprocessor-based universal meter for directly measuring the concentration of O2 and the combustible oxidizing components of gas (CO/H2), displayed as CO equivalent (COe), in combustion systems in the leaner than stoichiometric range (l > 1), in conjunction with combination probe KS1-D-Ex. For installation in hazardous area, max. exhaust gas temperature 450 °C / 850 °F.
It has a facility for direct connection to the integrated/combustion management system and the ETAMATIC. This makes it possible to achieve improved control mode to ensure optimized oil and gas combustion and automatic adjustment of combustion to changing combustion conditions.
The Lambda Transmitter LT 2Ex also provides the following functions:
• Measuring the temperature of flue gas and intake air and calculating combustion efficiency
• Calculating and displaying CO2 concentration
• Load-dependent and fuel-specific limit curves / limit values
• O2-Control
• Field bus connection
Advantages
• Direct (in situ) measurement of oxygen (O2) and oxidizing off-gas components (CO/H2) in the crude gas up to 450°C
O2 measurement range 0 to 21% vol. in conjunction with
COe measurement range: 0 to 10,000 ppm LT 2Ex
• No connection with infiltrated air (COe)
• No gas preparation required, measurement direct in the wet flue gas
• Setting time to 60% value (T60) < 10 seconds with standard sampling COe < 2 seconds
• Measuring gas temperature up to 450 °C / 850 °F
• Low calorific output 22 W
• Universal application
• Easy to use probe plugs in
• Low-maintenance
Components required
The measuring system is available in different models.
It consists of the following components:
Explosion-proofed Combination Probe KS1-D-Ex
For max. permissible exhaust gas temperature of 450 °C / 850 °F ATEX 11 2 G based on:
ATEX certification EXAM …. EEx d 11 B + H2 T3 relating to enviroment temperature of 60° C / 140 °F!
Electrically connection
Counter flange DN80 / PN40 or bigger
Head of the probe with sensor and sintered filter
Vent with flame barier
Host connector reference gas Host connector calibration gas
Tube of the probe with temperature sensor
The combi probe KS1-D-Ex records the values measured. It sits directly in the exhaust gas flow. Measurement is carried out directly in the probe.
The electronics are to be installed in an non-explosion area unless they have been installed in a suitable ATEX-approved housing (EEx d or EEx p) by a manufacturer who was authorised to do so and a separate certificate has been provided in connection with this.
The ZrO2 measurement cell sits at the tip of the probe underneath the sintered metal filter. The wiring between the combi probe KS1-D-Ex and the LT 2Ex lambda transmitter is carried out using conventionally shielded cable.
Combi Probe KS1-D-Ex
Immersion depth X Type KS1-D-Ex1 Type KS1-D-Ex2
500 mm
656 R 4000
656 R 4010 860 mm 656 R 4005 656 R 4015
Lambda-Transmitter LT 2Ex
• In wall mounting case IP 66 for installation in free hazardous area
alternatively
• On installation plate for installation in free hazardous area or in
• EEx d-case (optional) for installation in Ex-Area
Lambda-Transmitter LT 2Ex in wall mounting case IP66
Lambda-Transmitter LT 2Ex on installation plate
Lambda-Transmitter LT 2Ex in EEx d-case
Probe connection unit (PCU)
In version EEx-e near at the probe EG-prototype verification certificate according to PTB 00 ATEX 1063
• For connecting the probe at LT 2Ex.
• For connecting the reference gas and the calibration gas.
• For adjustment of the air flow.
• NAMUR limit contactor for monitoring of the flow of the reference air in version EEx-ia IIC according to DMT99 ATEX E 104 X
On installation plate In wall mounting case IP66
Theoretical basis of the principle of measurement
The combination probe KS1-D-Ex consists mainly of a zirconium dioxide electrochemical cell.
It has 3 electrodes
• an O2-sensitive platinum electrode
• a CO/H2-sensitive electrode made from a platinum/noble metal alloy
• a platinum reference electrode
Probe principle - O2 - sensitive electrode
CO/H electrode (Pt / noble metal alloy)
2
Gas inlet Reference electrode (Pt)
Protective coating
Zirconium oxide ceramic
HousingO -selective
reference electrode (Pt)2
US
UH
Diagram showing the structure of the combination probe KS1-D-Ex
The O2 measuring cell acts as an electrochemical concentration cell and generates a d.c. voltage which is dependent upon the absolute temperature T and the logarithm of the O2 concentration ratio or O2 partial pressure ratio at the reference and outer O2 electrode.
If the sample gas is fed to the outer electrode and a reference gas with a known O2 concentration, such as air for example (20.96%), is fed to the inner electrode, if the temperature is kept constant, this will give the logarithmic relationship, shown below, between the probe voltage US and the concentration of oxygen in the sample gas.
120
100
80
60
40
20
00 1 2 3 4 5 6 7 8 9 O (%)2
U (
mV
)S
ens
or
pO2 (G)Us = 0,049 T log
pO2 (L)
O 2 [%] = 20,96 10
U
0,049 T
s
.
Sensor characteristic Us = f (O2 )
Probe principle - CO/H2 - sensitive electrode
Combustible components are adsorbed as oxygen molecules at the electrode and diffuse to the "three-phase limit" formed by measuring gas, electrode and zirconium dioxide. In addition to the Nernst voltage U-O2 determined by the oxygen content, the combustible components present generate an additional d.c. voltage U-CO / H2 through the sensor. The sensor voltage is the sum of the two voltages US = U-O2 + U-CO/H2 (Fig. 1). Even with low concentrations of oxidizing gases such as H2 or CO, the mixture potential is much higher than the O2 signal. The mixture potential forms very quickly, T60 times of less than 2 seconds are achieved.
Sensitivity to O2 and combustible components can be influenced by the temperature of the sensor. Lower sensor temperatures bring about higher sensitivity to CO/H2 and lower sensitivity to O2 (Fig. 2).
The concentration of oxygen also influences the sensor voltage U-COe. With higher O2 content, the sensor voltage in the high CO range drops slightly (Fig. 3).
However, the combination probe KS1-D-Ex may not be used when it is too cold or else the oxidizing components will influence the O2 measurement (falsification of the measurement value to lower values because of oxidation of the non-burned flue gas components on the O2 electrode).
Us
(mV)
CO
Sensor characteristics (measured)
Nernst characteristic (calculated)
O (%)2
incomplete
combustion
complete
combustion Fig. 1: Characteristic at a gas burner
Fig. 2: Sensor voltage U-COe as a function of sensor temperature (heat output)
With higher O2 concentrations, more non-burned residue (CO/H2) oxidizes before it reaches the 3 phase limit. The effect of sensor voltage U-COe as a function of the O2 content is shown in the graph below.
1000
800
600
400
200
00 2000 4000 6000 8000 10000
CO [ppm]
9,5 % O
62
% O2
U [
mV
] C
Oe
at starting point with 0% CO
Fig. 3: Sensor voltage U-COe as a function of O2 content
It is therefore recommended that the characteristic is calibrated specifically for the system with a CO reference measurement.
Another indicator for non-burned residue (CO/H2) on combustion systems is the dynamics of the sensor signal (US). The higher the content of non-burned residue, the higher the dynamics. The following figure traces the rise of the sensor signal over the O2 value measured on a reference system (12 MW SAACKE gas burner) with a small load.
small load
700
400
600
300
500
200
100
00 31 42 5 6
2
40
300
O ref. [%]2
CO
[p
pm
]
U [
mV
]S
enso
r
Signal dynamic
> 100 mV+
Fig. 4: Quick-response O2 measurement combined with the detection of oxidizing flue gas components (non-burned residue) CO/H2.
Technical data of Lambda Transmitter LT 2Ex
Model: Wall mounting case
Installation plate
Case Sheet steel housing, powder-coated
Sheet steel, galvanised
Protection class according to DIN 40050
IP 66 IP 00
Dimension (HxWxD) mm 500 x 300 x 200 400 x 258 x 131,5
Colour grey RAL 7032 -----
Weigth approx. 15kg approx. 7kg
Ambient temperature Operation Transport and storage
-20 °C ... + 60 °C / -36 °F...140 °F -40 °C ... + 85 °C / -70 °F...185 °F
Line voltage 230 V AC und 115 V AC + 10 % / -15 %, 48 Hz...62 Hz CAUTION: To be used only in grounded power line networks!
Power consumption Typ. 50 VA, briefly 150 VA (probe heating-up phase)
Display LCD-Graphic display 100 x 80 mm (H x W)
Resolution O2: 0,1 Vol. % O2 in the range 0...18 Vol. % O2 1 Vol. % O2 in the range 18...30 Vol. % O2
CO: 1ppm in CO-range
Measuring accuracy: (with combi probe KS1-D-Ex)
O2: +/- 5 % of measurement value
Not better then +/- 0,30 Vol.%
In Exhaust gases of natural gas firing after calibration under system conditions with a CO reference measurement
COe: +/- 25 % of measurement value
Not better then +/- 10 ppm after calibration under system conditions with a CO reference measurement Measuring range 0...100 ppm : max. 10 ppm
Setting time (60 % time) O2: T 60 < 10 s
COe: T 60 < 2 s
Time to readiness for operation with KS1-D-Ex (coldstart)