Gas analysers provide surety of accurate measurement and records of a ship’s emissions, but these systems need to be properly maintained, installed and calibrated
Gas analysers are key to effective compliance, providing ship operators with the surety of accurate emissions’ measurements and records for port state control authorities. That surety can quickly disappear, however, if these continuous emissions monitoring (CEM) systems are improperly maintained, installed or calibrated.
A vital component for exhaust gas cleaning systems (EGCS) – which are fitted on over 4,000 ships that operate on heavy fuel oil – CEM systems are designed to provide direct measurement of SOx, NOx and CO2 emissions using photometer technology to demonstrate compliance to Marpol Annex VI to a port state control authority.
Accurate measurements recorded by CEM systems are absolutely critical, according to Exhaust Gas Cleaning System Association (EGCSA) director Don Gregory.
“A good reading within the regulatory limit is something that’s highly valued by the chief engineers,” said Mr Gregory. “I’ve been on board ships where chief engineers have pointed to the CEMs and said, ‘Look, it’s in value’ and they were really happy. But conversely, a CEMs problem does cause massive stress on board ship. They are worried about getting arrested or visits from port state control.”
Mr Gregory made his comments as a part of a panel of EGCS and CEMs manufacturers at Riviera Maritime Media’s Gas analysers and sensors: just how closely can emissions be analysed and monitored? webinar held in April. The event, produced with the support of premier partner ABB, was held as part of Marine Propulsion Webinar Week.
Speaking to his fellow panellists, Mr Gregory said: “We can’t underestimate how important what you do and what you provide is on board ship in an operational sense.”
Do CEM systems need to be calibrated annually? | ||||||||
Yes | 76% | |||||||
No | 24% | |||||||
Source: Riviera Maritime Media/Gas analysers and sensors: just how closely can emissions be analysed and monitored |
Filtering, calibrating and maintaining
Joining Mr Gregory on the panel, ABB product line continuous gas analysers strategic business development manager Ben Goossens explained accurate readings depend on a sample gas that is properly filtered and dried by removing all water, combined with correctly calibrated gas analysers.
An 18-year veteran of emission monitoring technology at ABB, Mr Goossens elaborated on some of the technical issues that can hinder an accurate reading of a sample gas.
“If you don’t get gas to the analyser, you can’t measure it,” he said. In a typical installation, Mr Goossens said the standard filter at the ship’s funnel must not only be heated but also fitted with a back-purging system. “Blowing compressed air is not sufficient to obtain the best result,” he said. He described a two-stage back-purging system that cleans the filter and evacuates particles.
“In some cases, you can expect a huge amount of soot. This soot is not like a dust particle that can be filtered over ceramic, with a low porosity,” he said. “This soot is a long hydrocarbon chain with a different behaviour than a dust particle.”
Do current CEM systems effectively monitor and report air emissions? | |||||||
Available | 51% | ||||||
Available but quality lacking | 24% | ||||||
Available but too expensive | 24% | ||||||
Not yet available | 0% | ||||||
Percentages may not add to 100% due to rounding | |||||||
Source: Riviera Maritime Media/Gas analysers and sensors: just how closely can emissions be analysed and monitored |
Water, too, has a strong interfering component, which if not fully evacuated from the sample gas can provide a false measurement, he said.
“Our engineered solution puts the condensate detection after the cooler, so we are sure that no water will get into the analyser,” said Mr Goossens.
Measurements must be accurate, and this can only be accomplished with a properly calibrated gas analyser. This responsibility falls to the ship operator. However, Mr Goossens was confident this could easily be handled on board because the gas analyser incorporates a gas-filled calibration cell. These gas-filled calibration cells, said Mr Goossens, offer long periods of stability. There is no need for certified test gas cylinders to make calibration adjustments, he said. “Just think of the effort of having to drag your 50-kilo calibration gas bottle through your ship.” The calibration cells can be set to ‘auto-perform’ a full calibration cycle.
Maintenance and servicing of the ABB CEM system is supported both locally and remotely through an analyser health status system that can generate QR codes on the analyser display. These QR codes can provide real-time information on the system’s status and health. When there is an event that needs attention, a QR code is generated about the event, explained Mr Goossens. When the ship operator sends their QR code to ABB, it contains information identifying the ship, the system installed, when it was commissioned and last serviced, its measurement range settings and when it was produced in the factory.
“More importantly, it will tell us something about the event that has taken place. In the case of a failure alarm, the QR code will tell us exactly what is going on,” he said. This, in turn, will allow ABB technicians to provide the ship operator with the right instructions to get the system up and running again, said Mr Goossens.
Additionally, ABB offers ‘over the shoulder’ support to vessel technicians that is accessible through smartphones or tablets and incorporates augmented reality capability.
Addressing CEM technology maintenance on the panel, Norsk Analyse sales manager Leif Nydal Abilgaard said the company’s strategy was to make a system that would require “as little input from the crew as possible – but we are realistic.” Said Mr Abilgaard: “The more we can train personnel on board, the better mean time between system failures.” To support the crew, Norske Analyse provides online training, both basic and advanced, which is accessible via a 4G connection.
“A good reading within the regulatory limit is something that’s highly valued by the chief engineers”
Mr Abilgaard said the company’s newer generation systems have self-diagnostics and remote access capability that helps Norske Analyse’s support team find faults more rapidly.
Equipment installation, maintenance and proper crew training were highlighted by panellist Allan Skouboe, Danfoss IXA chief technical officer. He said shipyards at times have ignored manufacturer’s instructions on proper installation of equipment.
Fellow panellist PureteQ chief executive Anders Skibdal agreed with Mr Skouboe. Providing the perspective of a scrubber manufacturer, Mr Skibdal said: “These gas analysers actually work and they are quite robust.” He noted one of the main reasons for malfunctioning systems is “the quality of the installation.”
Mr Skibdal offered some advice on why some systems might malfunction. “Many ships operate in a hot climate, which means you should think about installing air conditioning to cool down the unit,” he said.
One of Mr Skibdal’s big concerns was cost. He said the total cost of ownership over the life of the gas analyser can vary greatly between makers. “It’s the frequent filter replacement,” he said. “On some systems, you have to replace filters very frequently and they’re quite expensive.” He added that filter replacement, along with other maintenance and calibrations, needs to be considered when selecting a system.
What are the most reliable CEM systems? | ||||||||
In-situ | 59% | |||||||
Sample-type | 41% | |||||||
Source: Riviera Maritime Media/Gas analysers and sensors: just how closely can emissions be analysed and monitored |
Meanwhile, interest in NOx sensors in selective catalytic reduction (SCR) applications is increasing among ship operators, according to Mr Skouboe. “It’s not a mandatory equipment sensor right now, like the SO2 or CO2 sensors in scrubber applications, but when our customers are going to US waters – which is a NOx ECA – their attention towards the sensor is certainly increasing.”
To collect data from its onboard sensors, Danfoss IXA uses a system called EmViz – an emission visualisation platform – to collect and provide an overview of the emission performance of a ship or a whole fleet, explained Mr Skouboe.
“You can easily monitor the input from various sensors on board, on your auxiliary engines, main engine and scrubber output,” said Mr Skouboe. A satellite link is used to transfer the data for storage at a data centre on shore. “We offer this system which can analyse and create different reports at the push of a button,” he said.
Simplify systems
Mr Gregory was pleased that CEMs manufacturers are starting to make ‘smart’ use of the data and noted the development of a QR code as a “really clever way of doing fault-finding.” Anticipating the growth of the market for emissions sensors as regulations tighten, however, Mr Gregory challenged CEMs manufacturers to innovate, developing more discreet, simpler and lower-cost options. “We’ve heard about infrared, UV and light, but things can move on,” he said, noting that if an image of an iris from a smartphone can be used to diagnose an illness, then CEMs manufacturers “can be more innovative in looking at what the parameters are in a gas and gas duct and how they might be measured in a different way.”
He noted manufacturers are being smart about managing the data collected from CEMs. Now, they need to be smart about applying new, more sophisticated technologies in use elsewhere to collect that data on board ship.
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