SS2100 - C2H2 Ethylene Purity (Product or Polymer Feed) Analyzer Solution

Application Note

 Acetylene Control and Reduction
It is not practical to remove Acetylene from Ethylene by distillation. Acetylene reduction is done in an Acetylene Converter Unit. Acetylene Converter Units consists of a series of reactors or a single vessel with multiple beds of catalyst that reacts the Acetylene with hHdrogen to form Ethylene. Reduction of low ppm Acetylene concentrations inevitably reacts some of the Ethylene to Ethane, resulting in a loss of product, so it is critical to keep Acetylene contamination out of Ethylene once the initial Acetylene reduction is complete.

 Traditional Measurement Solutions
On-line gas chromatographs have been the traditional method for monitoring the levels of Acetylene in Polymer Grade Ethylene. Unfortunately, even with the latest in chromatography techniques, the analysis can take 2 - 4 minutes between measurement updates. Due to the very short residence times in Ethylene feed storage vessels and the desired to measure Ethylene in flowing pipelines, this delay in measurements can easily lead to excursions in concentrations before it is detected.

 SpectraSensors’ Solution
The SpectraSensors SS2100 is the ideal solution for Ethylene purity applications. The use of Tunable Diode Laser technology means that analysis results can be updated every second. Furthermore, the high resolution that is inherent to the laser eliminates errors due to interferences that have hampered other spectrometric approaches. Also, the non-contact nature of the measurement with no moving parts in the analyzer means that the analyzer is simple to operate, has no consumable parts and no routine maintenance is needed. See Fig. 3 for typical calibration performance.

In addition to Acetylene, water, another important purity measurement can be made using TDL analysis.

Component	Unit	Typical Concentration	Min. for Application	Max. for Applicaiton
Ethylene (C2H4)	Mole%	99.95	99.9	100
Acetylene (C2H2)	ppmw	<1	0	5
Water	ppmw	<1	0	5
Carbon Monoxide (CO)	ppmw	0.5	0	3
Carbon Dioxide (CO2)	ppmw	< 1.0	0	5
Hydrogen (H2)	ppmw	<1	0	5
“Light Inerts” (C1+C2+N2)	ppmv	100 - 200	0	1000
Propylene (C2H6)+	ppmw	3000	0	10
Total	Mole%	100

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Data Sheet

Performance
Target Components	Acetylene in Pure Ethylene (Product or Feed)
Typical Measurement Ranges	0 – 5 ppm*
Typical Precision	± 0.1 ppm
Measurement Response Time	1 to ~60 sec*
Principle of Measurement	Tunable Diode Laser Absorption Spectroscopy Non-differential
Environmental Temperature Range	-20º to 50ºC (-4º to 122ºF) -10º to 60ºC (14º to 140ºF) optional
Sample Inlet Pressure	70 kPag (10 psig) typical 210 kPag (30 psig) maximum
Cell Temperature	Maintain at 50ºC +/- 0.2ºC
Maximum Cell Pressure	70 kPag (10 PSIg)
Sample Flow Rate	3 - 4 L/min (6.4 to 8.5 scfh)*
Validation	Certified blend of C2H2 in Nitrogen balance
Electrical
Power	100-240 VAC, 50-60 Hz standard
Max Current	Controller: 1 A @ 120 VAC
Controller to Cell Cable Length	1m standard (3m, 5m & 10m available optionally)
Communication	Current Loop Output 4-20 mA Isolated, 1200 ohms @ 24 VDC max load Serial: ASCII Text RS232C standard Modbus RS232C
Digital Outputs	4 ea. 12 VDC for valve operations Scrubber (if required), Process/Val, Val 1, Val 2 5 SPDT (Form C) Dry Contact Alarms Common Fault, Val 1 Active, Val 2 Active, Val Fail, one user-assignable to any alarm
LCD Display	Concentration, Cell Pressure and Temperature, Diagnostic Data
Physical
Controller Enclosure	NEMA 4X - 304 Stainless Steel standard
Controller Dimensions	343mm H x 305mm W x 165mm H (13.5" H x 12" W x 6-7/16" D)*
Weight Approximately	13.1 Kg (28.6 lbs)*
Sample Cell Dimensions	28m cell 559 mm H × 127 mm W (22” H × 5” W)
Sample Cell Construction	316L Series Polished Stainless Steel standard SilcoNert® coated
Number of Sample Cells	1 (single channel SS2100) or 2 (dual channel SS2100)
Area Classification	CSA Certified for Class I, Division 2, Groups ABCD Temp Code T3C  ll 2G Ex d llB+H2 T5; Tamb : -20 ÷ +60 °C
Dimensions with Sample System	1678 mm H x 613 mm W x 427 mm D (66” H x 24-1/8” W x 16-13/16” D)
Weight with Sample System (approx.)	68 kg (150 lbs.)
* Application specific; consult factory

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Drawings

Typical Accessories

Photos

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