Vigilant against black smoke and emissions

MariNox, which, despite its name, monitors actual NOx, SOx and CO₂ emissions from engines should, according to Martek, prove a useful investment for ship operators who will have the opportunity to quickly recoup the not inconsiderable investment of fitting a monitoring system. With the stricter emissions limits under Marpol Annex VI Regulation 13 coming into force owners will be placed under increasing pressure to prove that their vessels comply. Martek’s marketing director, Steve Coulson, told us that these pressures will not only come from the regulators, but also from environmentally-conscious charterers who themselves need to be able to demonstrate that their good as being moved in a ‘green’ fashion.

Moreover, with some form of carbon trading or carbon taxation certain to be introduced in the future, shipowners who can demonstrate actual, rather than calculated, CO₂ emissions levels will be able to fully benefit – in the same way that MariNox has been saving Norwegian NOx tax for some affected shipowners.

Coulson also pointed out that MariNox can help achieve significant savings in fuel costs by ensuring that engines continue to operate efficiently and in accordance with emissions regulations when running outside their normal operating parameters – for example when slow steaming. Monitoring the CO/CO₂ ratio in exhaust gases provides a key indication of combustion efficiency, and fuel savings of some 3% have been achieved by keeping to the correct ratio, as measured by MariNox. Engines running at part load can be running at below optimum efficiency. Even manufacturer-approved slow steaming modification kits may not provide any guarantee that the engine still meets its NOx compliance status. Martek says that MariNox can measure the actual emissions, allowing adjustments or further modifications to ensure that ships are within Marpol Annex VI requirements at their current operating profile.

Now MariNox has been joined in the Martek range by another monitoring system, known as Vigilant. It may be thought that black smoke from ships’ funnels was visible to the eye, and did not need to be monitored by an electronic device. But therein lies a problem. Stringent rules against ships exhausting black smoke within sight of shore – notably in regions such as Alaska and Hawaii, where cruise ships and tankers are particularly vulnerable – are backed up by ‘spotters’ employed by authorities to report any infringements. The reports from these ‘spotters’ are entirely subjective, if they think they see smoke, they can report it. Martek says that this strategy is becoming more widespread and being introduced elsewhere, with penalties extending from warnings and fines to future banishment of guilty tonnage from the area.

Martek Marine’s Vigilant calibrated funnel smoke monitoring system offers a source of scientific evidence against any such erroneous allegations.

Many boilers have funnel smoke monitoring facilities installed at the newbuilding stage by the boiler OEM. Martek reckons that less than 1% of new tonnage, however, is currently estimated to have installations covering the main and auxiliary engines although the number is expected to rise steadily. Both newbuilding and retrofit markets will be driven by intensifying local legislation as well as pressure from charterers for owners to adopt best environmental practice (and hence avoid involvement in legal disputes).

A funnel smoke monitoring system measures the density of smoke using opacity monitoring techniques based on a transmitter and receiver installed on either side of the funnel. The transmitter sends a beam of light towards the receiver and the obscuration - the amount of light that reaches the receiver - is measured.

The thicker and darker the smoke, the less light received by the transmitter: very dark smoke will result in a very low amount of light or even no light received by the receiver. The readings are sent via serial communications protocol and cabling to the Vigilant control system, where the software converts the signalled values to representation in terms of the Ringelmann Scale, which grades densities of smoke.

Readings can be stored by the system for defence in the event of accusations made by authorities that the ship was exhausting black smoke in contravention of local or international regulations. The values are displayed on a liquid crystal display, and historical data can be recalled and viewed via the menu system.

A range of parameters can be initialised or altered via the menu system, such as alarm levels to alert operators that the smoke densities are approaching illegal levels. Vigilant can also receive signals from oxygen analysers installed in the boiler exhausts to monitor for higher than expected levels of oxygen, which indicate that combustion in the boiler is not as efficient as it should be. Multiple exhausts can be monitored at the same time, a facility of importance in cruise ships that may have ten or more separate engines.

Martek claims that Vigilant offers a number of features that distinguish it from the more simple ‘opacity only’ products.

A single PC controller simplifies installation, provides greater clarity of results for the user and allows monitoring of smoke in terms of the ship’s specific location and recording of this data for production to the authorities. (Other systems use one controller per smoke monitor, making integrated reporting of all engines and boilers difficult, if not impossible.)

Integrated zirconia oxygen analysers allow not only smoke monitoring for environmental reasons but also boiler efficiency monitoring. Higher than normal levels of oxygen in the exhaust mean that the boiler is not performing optimally and therefore too much fuel is being used. This yields a payback benefit against the initial system cost.

A more advanced control system enables all engine smoke, GPS and oxygen data to be shared with the ship’s central control and monitoring systems.

Martek Marine suggests that the Vigilant funnel smoke monitoring system may be attractive to some shipowners as an interim precautionary step that can be expanded later into a full MariNOx emissions monitoring system.