The Pipeline Contamination Monitor called LineVu from Process Vision is a video-based system designed to detect contamination in high pressure natural gas systems, enable alarm notifications and allow access to live video to both office-based and field-based engineers.
Detection of Pipeline Contamination using Image Processing
When natural gas is processed, liquids are injected to remove water vapour, carbon dioxide and hydrogen sulfide. It is vital that these liquids are completely removed from the gas stream prior to exporting the gas for sale yet, to date, there are no effective methods to determine if liquid separators are working to their stated efficiency 100% of the time. Often operators find out too late that there is a problem with liquid carry over causing $Ms of damage.
If hydrocarbon liquids are allowed to enter dehydration systems, foaming can occur requiring the addition of de-foaming agents. At the exit of the de-hydration system, liquids like glycol (MEG and TEG), crawl down the walls of the pipeline causing further problems.
If the processing plant is fitted with a refrigeration (or dew pointing) system to remove as much, high value, gas condensate as possible, glycol enters the system and freezes at around -6°C, causing problems with the temperature control of the system and further liquids remain in the export gas stream.
What does a Pipeline Contamination Monitor do?
The Pipeline Contamination Monitor LineVu reveals contamination in high pressure natural gas systems that until now has been un-detected. Despite commercial and legal contracts requiring that no liquids or solids should enter a gas network, it is common to find that liquid contamination is the cause of damage to power stations and other plant all over the world.
LineVu is a camera system that can be permanently installed on high pressure natural gas systems. When installed downstream of a gas/liquid separator it provides a live video stream of the gas leaving the separator system. Image processing is used to provide operators with a highly sensitive alarm if there is a break-through that contaminates the gas stream.
By monitoring the efficiency of gas/liquid separation systems LineVu provides game-changing safety and financial benefits.
Improving Foam Management in Gas Treatment
Liquid carryover in gas treatment causes foaming in amine and glycol contactors. Normal practice is to use de-foamer to recover from a foaming event. This often requires a reduction in gas flow rate until the foam is under control. Current practice is to monitor pressure drop across the contactor. Now, with Pipeline Contamination Monitor LineVu reporting a carryover event before foaming starts, de-foamer can be added to prevent foam rather than recover from it, without loss of production.
Improving Condensate Recovery
After gas treatment, it is important to recover as much of the premium condensate from the gas as possible. Processing liquids (usually glycol) can be carried over from gas treatment and freeze in the dew pointing equipment. This causes temperature control problems and can partially block the liquid removal process, and a combination of glycol and condensate are lost down the gas export line. When LineVu reveals liquid carryover from gas treatment, flows can be adjusted to find the optimum flow until the problem is diagnosed and repaired.
Using LineVu at custody transfer points improves accountability for pipeline contamination incidents. Gas is bought and sold at custody transfer points on a dry gas basis. LineVu is revealing glycol and compressor oil carryover that, up to now, passed on-line gas analyzers without tripping an alarm. With the extra knowledge that the gas is wet, flow computers can be corrected, operators can make better decisions regarding the acceptability of gas, and pigging operations can be optimized.
The Camera Can in the Pipeline Contamination Monitor LineVu system is mounted above a pipeline, normally behind a double block and bleed valve, thereby providing a “stand-off”, meaning that any contamination present in the gas flow does not foul the optics of the instrument.
Game Changing Technology for Custody Transfer Points with Pipeline Contamination Monitor LineVu
Natural gas quality is closely monitored at custody transfer points where gas enters a gas network, usually referred to as mid-stream. Gas analyzers continuously monitor to ensure that the gas entering the network complies with both commercial agreements and safety regulations. However, while gas contracts strictly specify that there should be no liquids, there are frequent instances where liquids used in gas processing or compressor oil, have carried over with the gas flow and pass through the monitoring system without triggering an alarm. If contamination is discovered, it results there are associated clean-up costs. In some cases, it is discovered too late, after it has caused corrosion or a dangerous and expensive failure in a gas turbine power station or compressor station.
The new monitoring system from Process Vision, LineVu, is being tested at gas entry points to networks in Europe and North America. LineVu is a high-pressure camera system, permanently installed at a pipeline tapping point and looks down into the gas pipe below. Image processing detects and reports any contamination seen moving down the pipeline. The optical system is recessed from the pipeline to avoid contamination of optics and has a secondary containment system to enable long-term, safe, monitoring.
With the system providing a live video stream to both local and remote engineers, the information gained from Pipeline Contamination Monitor LineVu puts the network in a position to make better operational decisions and improve accountability.
Paul Stockwell, Managing Director of Process Vision Ltd, said: “Contamination of gas pipelines is a global problem that has been overlooked for too long. Apart from the safety and asset integrity improvements, LineVu enabled custody transfer points will prevent contamination entering the network, and significantly improve the uncertainty of fiscal flow measurements, which widen when wet gas is present.”