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Total Sulfur Gas Analyzers

OMA-300 Measuring Total Sulfur Directly in Natural Gas

OMA-300

Measuring Total Sulfur Directly in Natural Gas


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TSA-200 Combustion Style Total Sulfur Analysis

TSA-200

Combustion Style Total Sulfur Analysis


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OMA-300


Measuring Total Sulfur Directly in Natural Gas

OMA-300 Measuring Total Sulfur Directly in Natural Gas

Application Summary: Total Sulfur Direct

  • Measurement: Total Sulfur (up to 5 sulfur compounds)
  • Detector: OMA-300 Process Analyzer
  • Process Stream: hydrocarbon fuels

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Technology: Total Sulfur Direct

The ASTM method for total sulfur analysis calls for oxidation of all present sulfur compounds to sulfur dioxide for straightforward measurement. When a stream contains many different sulfur species, or unknown exotic sulfur compounds, this method is usually the only option.

The OMA-300 Total Sulfur Direct Analyzer takes a different approach, measuring up to 5 sulfur compounds directly in the unaltered sample using powerful multi-component analysis software and a high-resolution UV-Vis spectrophotometer.

The OMA-300 Total Sulfur Direct has compelling benefits for the process operator:

  • Richer data through individual concentration measurement of each constituent sulfur species
  • Decades of proven reliability measuring multiple sulfur compounds simultaneously
  • Highly suitable for natural gas applications (e.g. pipeline gas)

Sulfur Compound Absorbance Curves

Any single photodiode measurement is vulnerable to noise, signal saturation, or unexpected interference. This susceptibility to error makes a lone photodiode data point an unreliable indicator of one chemical’s absorbance.

As accepted in the lab community for decades, the best way to neutralize this type of error is to use collateral data in the form of ‘confirmation wavelengths,’ i.e. many data points at many wavelengths instead of a single wavelength:

total sulfur analyzers total sulfur analyzers

In the figures above, each diamond represents a single photodiode and data point. The OMA measures absorbance at each integer wavelength within the measurement wavelength range and produces analyte absorbance curves. This use of ‘confirmation wavelengths’ instead of simple peak absorbance measurement serves to eradicate the effect of noise at any single photodiode, allowing for much more accurate analysis free from cross-interference with light.

Multi-Component Total Sulfur Analysis

Each photodiode supplies one data point of absorbance information at an integer wavelength. The OMA’s ECLIPSE software continuously solves a matrix of equations from all these data points simultaneously to de-convolute each compound’s absorbance curve from the total sample absorbance:

Multi-Component Total Sulfur Analysis

In the analysis, we use a 4-component equation:

A’(w+x+y+z) = A’w + A’x + A’y + A’z = e’wbcw + e’xbcx + e’ybcy + e’zbcz

where A’ is the absorbance at wavelength ‘, e’ is the molar absorptivity coefficient at wavelength ‘, c is concentration, and b is the path length of the flow cell. In the image above, four such equations (at 216nm, 217nm, 218nm, and 219nm) are shown. In reality, the matrix includes one equation from every single integer wavelength in the measurement wavelength range.

This matrix of data from many wavelengths provides far more accurate multi-component analysis within a spectral region that has heavily overlapping absorbances from each analyte.


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Specifications: Total Sulfur Direct

Note: All performance specifications are subject to the assumption that the sample conditioning system and unit installation are approved by Applied Analytics. For any other arrangement, please inquire directly with Sales.

Measurement Principle Dispersive ultraviolet-visible (UV-Vis) absorbance spectrophotometry
Detector nova II™ UV-Vis diode array spectrophotometer
Spectral Range 200-800 nm
Light Source Pulsed xenon lamp (average 5 year lifespan)
Signal Transmission 600 μm core 1.8 meter fiber optic cables
Other lengths available
Path Length Application-dependent
Sample Conditioning Custom design per application
Analyzer Calibration If possible, analyzer is factory calibrated with certified calibration fluids; no re-calibration required after initial calibration; measurement normalized by Auto Zero
Reading Verification Simple verification with samples and self-check diagnostic
Human Machine Interface Industrial controller with touch-screen LCD display running ECLIPSE™ Software
Data Storage Solid State Drive
OPERATING CONDITIONS
Analyzer Environment Indoor/Outdoor (no shelter required)
Ambient Temperature Standard: 0 to 35 °C (32 to 95 °F)
Optional: -20 to 55 °C (-4 to 131 °F)
To avoid radiational heating, use of a sunshade is recommended for systems installed in direct sunlight.
Sample Temperature Standard: -20 to 70 °C (-4 to 158 °F)
Optional: up to 150 °C (302 °F) with cooling extensions
Contact AAI for temperatures above 150 °C (302°F)
Sample Pressure Using standard flow cell: 206 bar (3000 psi)
Using immersion probe: 100 bar (1470 psig)
UTILITIES
Electrical 85 to 264 VAC 47 to 63 Hz
Power Consumption 45 watts
OUTPUTS
Standard Outputs 1x galvanically isolated 4-20mA analog output per measured analyte(up to 3; additional available by upgrade)
2x digital outputs for fault and SCS control
Optional Outputs Modbus TCP/IP; RS-232; RS-485; Fieldbus; Profibus; HART;
PHYSICAL SPECIFICATIONS
Select analyzer type: OMA-300 Wall-Mounted Analyzer
OMA-206P Portable Analyzer
OMA-406R Rackmount Analyzer

Measurement accuracy for the OMA Process Analyzer depends on the application and stream composition. Select an application for specific accuracy.

Response Time1-5 seconds
Zero Drift±0.1 % after 1hr warm-up, measured over 24hrs (constant ambient temperature)
Sensitivity±0.1 % full scale
Noise±0.004 AU at 220 nm
Standard Design General Purpose
Available Options ATEX, IECEx, EAC
Please inquire with your sales representative for additional certifications (CSA, FM etc.).

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Resources: Total Sulfur Direct

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TSA-200


Combustion Style Total Sulfur Analysis

TSA-200 Combustion Style Total Sulfur Analysis

Applications: Total Sulfur Combustion

Sulfur compounds--particularly hydrogen sulfide--in natural gas carry with them a host of problems and considerations for both producer and consumer. Sulfur content is known to:

  • Cause pipeline corrosion, jeopardizing distribution networks and necessitating complex maintenance regimens
  • Officially reduce the quality of sales gas; natural gas quality assurance involves monitoring of sulfur content, e.g. at custody transfer points
  • Contribute directly to SO2 emissions from gas-burning plants; SO2 is a widely regulated pollutant and a necessary concern for avoiding fines and fulfilling social responsibility
  • Introduce unpleasant odors to gas-dependent industrial and domestic environments; mercaptans are added to natural gas to make leaks noticeable by smell, but uncontrolled sulfur content turns the odor from useful to intolerable

Avoiding these chronic sulfur-related issues requires reliable online monitoring of total sulfur load in gaseous hydrocarbon streams. The only way to verify the efficiency of sulfur removal processes and ensure satisfaction of customer and environmental needs is to proactively analyze stream composition.

The TSA-200 is a fully integrated monitoring solution driven by UV-Vis diode array detection. This solid state instrument is much more practical than the consumable-laden designs that have historically dominated the market.


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Technology: Total Sulfur Combustion

Principle of Operation

The TSA-200 uses an ultraviolet-visibile (UV-Vis) spectrophotometer to measure the resultant SO2 concentration after pyrolysis. This method is known to be highly resistant to false positives; full-spectrum analysis quickly removes erroneous data using averaging algorithms.

Spectrophotometer Principle of Operation

The TSA-200 uses a long-life xenon light source to transmit a signal through the sample fluid in the flow cell. The signal is carried by fiber optic cables from the analyzer to the flow cell, where the chemical mixture of the sample has unique interactions with the light based on its current composition.

TSA-200 Total Sulfur Analyzer Optical Assembly

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Sampling: Total Sulfur Combustion

The TSA-200 sample conditioning system is designed primarily for controlled combustion of the sample.

Upon entering the TSA-200, the sample is split via tee into a bypass loop and a sample loop. In the sample loop, two mass flow controllers are used to accurately mix the sample with air, ensuring an optimal air/fuel ratio for combustion.

The sample/air mixture flows through a pyrolysis furnace, where all present sulfur compounds are converted to sulfur dioxide:

R-S + R-H + O2 > SO2 + CO2 + H2O

The fully oxidized sample then enters the measurement flow cell where SO2 absorbance is monitored (via fiber optic cables). Finally, the sample exits the system as waste.


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Specifications: Total Sulfur Combustion

Note: All performance specifications are subject to the assumption that the sample conditioning system and unit installation are approved by Applied Analytics. For any other arrangement, please inquire directly with Sales.

Measurement PrincipleDispersive ultraviolet-visible (UV-Vis) absorbance spectrophotometry
Light SourcePulsed xenon lamp (average 5 year lifespan)
Signal Transmission600 μm core 1.8 meter fiber optic cables
Other lengths available
Path LengthApplication-dependent
Sample ConditioningThe SCS utilizes mass flow controllers to continuously mix the sample gas with air at a precise fuel:air ratio. The system passes the resultant mixture through a furnace tube. Post-combustion, the stream absorbance is measured.
Analyzer CalibrationIf possible, analyzer is factory calibrated with certified calibration fluids; no re-calibration required after initial calibration; measurement normalized by Auto Zero
Reading VerificationSimple verification with samples and self-check diagnostic
Human Machine InterfaceIndustrial controller with touch-screen LCD display running ECLIPSE™ Software
Data StorageSolid State Drive
OPERATING CONDITIONS
Analyzer EnvironmentIndoor/Outdoor (no shelter required)
Ambient TemperatureStandard: 0 to 35 °C (32 to 95 °F)
Optional: -20 to 55 °C (-4 to 131 °F)
To avoid radiational heating, use of a sunshade is recommended for systems installed in direct sunlight.
UTILITIES
Electrical85 to 264 VAC 47 to 63 Hz
Power ConsumptionPer system
OUTPUTS
Standard Outputs3x galvanically isolated 4-20 mA analog output per measured parameter
1 digital fault alarm
1 digital input
1 k type ungrounded thermocouple input
4x relay outputs
Additional outputs available by upgrade
Optional OutputsModbus TCP/IP; RS-232; RS-485; Fieldbus; Profibus; HART;
PHYSICAL SPECIFICATIONS
SizeAnalyzer: 24" H x 20" W x 8" D (610 x 508 x 203 mm)
SCS: 36”H x 36”W x 12” D (914mm H x 914mm W x 305mm D)
WeightAnalyzer: 32 lbs. (15 kg)
SCS (if included): per system
EnclosureStandard: wall-mounted carbon steel NEMA 4 enclosure
Photometric Accuracy±0.004 AU
Application AccuracyDependent upon application. Please inquire with Sales.
Standard Design General Purpose
Available Options ATEX, IECEx, EAC
Please inquire with your sales representative for additional certifications (CSA, FM etc.).

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Resources: Total Sulfur Combustion

PDF — English

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