SS2100 - Amine Scrubber Outlet Analyzer Solution

Application Note

Natural Gas Processing Plants
Regardless of the process downstream for Natural Gas Liquids extraction or Liquefied Natural Gas production, one of the first steps in a typical gas plant is acid gas (H2S and CO2) reduction and control. The Natural Gas product will typically have maximum allowable H2S concentrations <5ppm.

 Critical Control of H2S
There are a variety of H2S and CO2 reduction systems, some using liquid scrubbers such as amines or solvents, or fixed adsorbent beds, but the optimal operation of these systems requires an on-line measurement of the acid gas in the outlets of these systems..

 Traditional Measurement Solutions
Lead Acetate Tape devices have been used for on-line H2S analysis, but the on-going cost and maintenance effort of replacing the tapes is high. Moreover, many regard the Lead Acetate tape to be a hazardous material with associated handling and disposal problems. On-line gas chromatographs are another method widely used for monitoring the levels of H2S. Unfortunately, even with the latest in chromatography techniques, the analysis can take 3-6 minutes between measurement updates. Due to rapid changes in the acid gas concentration, this delay may not be acceptable. Gas chromatographs consume carrier and flame fuel cylinder gases, as well as requiring sulfur-free air for flame photometric detectors, so the consumable costs of GC’s are high. Spectroscopic methods using broadband light sources and narrow band pass filters are prone to interferences from changing background concentration.

 SpectraSensors’ Solution
The SpectraSensors SS2100 offers a new solution to this control measurement. There are no cylinder gases or Lead Acetate tapes to replace on a routine basis, so the analyzer is very low maintenance and has a low cost of ownership over the life of the analyzer.

The high resolution that is inherent to TDL technology eliminates errors due to interferences that have hampered other spectrometric approaches. Only SpectraSensors employs Differential Spectroscopy to cope with the changes in background spectrum of the sample caused by changing operating conditions and feedstocks.

The sample gas is passed through a copper nanoparticle scrubber to remove H2S, and the spectrum of the H2S-free sample is measured. The scrubber is then bypassed to measure the raw sample with H2S, and the H2S is measured by spectral subtraction.

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Data Sheet

Performance
Target Components	H2S in Amine Scrubber Outlet
Typical Measurement Ranges	0 – 10ppm*
Typical Precision	±0.5 ppm*
Measurement Response Time	1 to ~60 sec
Principle of Measurement	Differential Tunable Diode Laser Absorption Spectroscopy (H2S Scrubber included)
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 H2S in Methane 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 - 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 Herriot 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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