In the past, sophisticated online analysis for hydrocarbons was used only in laboratories – but now they’re widely used online at many upstream, midstream, and downstream hydrocarbon facilities.
Online analyzers help the modern oil and gas industry ensure they’re meeting government regulations for acceptable levels of corrosive O2, CO2, H2S, and H2O, as well as toxic flare emissions.
Analyzers provide the BTU value (quality side) with the volumetric (quantity side) value (MM/BTU) used at all custody transfer locations. In addition, process facilities use analyzers for quality checks on the products to confirm processes are operating efficiently.
When integrated into a complete analytical system that includes sample conditioning, regular maintenance, and calibration, many online analyzers will consistently provide accurate results. However, most technologies will experience false readings and/or complete failures in the presence of contaminants, such as particulates, compressor oils, water, production chemical scavengers, glycols, and methanol.
If the calibration standard is not a quality blend in date, meaning it is thoroughly mixed before use and kept above the dew point, it can also be challenging to calibrate the analyzers for accurate readings.
In addition, the temperature of the sample must be appropriately managed to ensure accurate results.
Maintaining correct analyses ensures you’re producing a high-quality product that prevents costly system shutdowns and maximizes your product’s price.
Accurate online analysis requirements
First, choose the correct analytical technologies for the desired analyses. Then, establish routine calibration and maintenance programs. Finally, a sample conditioning system capable of separating contaminants from the sample stream without affecting the sample is necessary.
Sample conditioning systems aren’t universal in design and should be developed based on the process fluids, potential contaminants, and application. However, there are best practices for developing a sample system in conjunction with analyzers:
- Materials. Materials of construction should be corrosion-resistant and impervious to absorption of contaminants. It’s common to use 316 SS components and elastomers compatible with the potential contaminants and temperatures.
- Pressure. All analyzers require low pressure and a steady sample flow without spikes to produce quality results. As such, most samples will require dual regulation. The resulting Joules Thomson effect must be considered so that chilling the product doesn’t separate components from the sample or eliminate the flow by freezing.
- Temperature. The sample temperature must be corrected so that the chilling created by the regulation and ambient conditions don’t cause heavier components to fall out. This will reduce the temperatures below the hydrocarbon dewpoint and all heavier elements in the stream. Operators should be cautious to avoid any liquids from being collected in the sample system when applying heat to prevent flashing the liquids into a vapor and affecting the analysis.
- Sample Supply. It is ideal to have a slipstream sample supply with a positive flow that closely matches the velocity of the primary process. A sample probe must be used and should extend to the center of the process for the cleanest location to begin the slipstream or sample takeoff. If a slipstream sample supply cannot be achieved, keep the sample line as short as possible. Use ¼” tubing and an uphill slope to prevent any liquids from entering the analyzer.
- Location. The analyzer must be close to the sample takeoff source to prevent any lag in sample delivery to the analyzer. It is essential to avoid excessive bends and low points.
- Power. It’s critical to implement reliable primary and backup power sources as these devices will not work without energy.
- Protection. Make sure the equipment is protected from the environment. Any damage will result in inaccurate measurements or equipment failure.
Learn more about using online analysis with our webinar, Stand Ready: Maximize Your Performance & Bottom Line with Online Analysis.
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