This system uses two sensors to compute the true temperature of reheat furnace load enabling significant savings in energy costs to be made.
An FTS thermometer operating at 3.9µm measures the target temperature and a secondary sensor (either a type R or S zone thermocouple or an FTS thermometer) measures the hotter background temperature to provide compensation for reflection errors.
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High system accuracy, typically ±20°C/±36°F at 1000°C/1830°F.
The System
The primary channel input to the signal processor is from a Furnace Thermometer System (FTS) which is designed specifically for this measurement. The secondary (background) channel input to the signal processor is obtained either from a second FTS thermometer or from a type R or type S thermocouple, via a transmitter.
The processor corrects for background reflection and load emissivity. It provides a current output, linear with the true load temperature, or a simulated thermocouple type R or S output.
A digital display of the true load temperature is provided on the processor front panel.
The standard Serial Communications facility gives digital RS232C or RS485 outputs and allows access for system parameters adjustments from a remote computer.
The Application
High system measurement accuracy, typically better than +20°C/+68°F at 1000°C/1830°F, is obtained in gas-fired (natural/blast furnace/coke oven) steel reheat furnaces - even in the first heating zone.
Similarily, high accuracy measurements can be achieved in many furnaces fired on light or heavy oil.
Close consultation with LAND is advisable for best results on oil-fired furnaces.
The system is also suitable for use on a wide variety of other furnace applications where background reflections are affecting single sensor system measurements.
System Specification
Primary sensor:
FTS 500/2000C
FTS 900/3600F
Secondary sensor:
FTS 500/2000C
(permits background compensated
measurements to 2000°C)
FTS 900/3600F
(permits background compensated
measurements to 3600°F)
or:
Type R or Type S zone themocouples
(permits background compensated
measurements to 1500°C)
(permits background compensated
measurements to 2732°F)
Measurement range
Primary input:
500 to 2000°C
900 to 3600°F
Secondary input
a) thermometer:
b) thermocouple:
500 to 2000°C
Type R or S, 0 to 1500°C,
via 4-20mA linear transmitter
900 to 3600°F
Type R or S, 32 to 2732°F,
via 4-20mA linear transmitter
Update time:
0.5s (to 95%)
Emissivity range:
0.300 to 1.000 adjustable in 0.001 increments
Outputs:
0 to 20mA, 4 to 20mA or 1mV/°
Out of range warning:
Voltage-free alarm contacts change status when either primary or secondary input is out of measurement range
Signal Processor
Single system:
LMG-M 1100-2 (accepts one primary input and one secondary input)
Dual system:
LMG-M 1111-2 (accepts two primary inputs and two secondary inputs)
FTS Thermometer Specification
Model:
FTS 500/2000C
FTS 900/3600F
Temperature range:
500 to 2000°C
900 to 3600°F
Wavelength:
Narrow band centred on 3.9µm
Response time:
100ms (to 95%)
Field of view:
100:1
Focus range:
0.5m to infinity variable focus
19.5in to infinity variable focus
Min. target diameter:
5mm
0.2in
Target size:
>98% energy within graticule image
Accuracy
Interchangeability:
<2K
Repeatability:
<2K
Absolute:
0.5%K over core range of 800 to 1250°C,
0.5%K over core range of 1500 to 2300°F,
1%K over full range of 500 to 2000°C
1%K over full range of 900 to 3600°F
Stability:
<0.025%T(K)/°C
<0.014%T(K)/°F
Vibration:
3g any axis, 10 to 300Hz
Humidity:
0 to 99% non condensing
Sealing:
To IP65 requirements
To NEMA 4X requirements
Ambient temperature:
0 to 70°C
32 to 158°F
Weight:
1.7kg
3.75lb
CE:
EN 50-082-2 (immunity), EN 50-081-1 (emission), IEC 1010 (safety)
