Something in the air

It may have slipped down ESPO’s ranking, but dust suppression is still important, finds Alex Hughes

Since the European Sea Ports Organisation (ESPO) began compiling its Top 10 Environmental Priorities of Ports in 1996, only dredging and dust have been present in all five surveys.

In the last one, which relates to 2016, concerns about dust had slipped from eighth to ninth place, down from highs of fourth and fifth in 2004 and 1996 respectively.

However, ESPO senior advisor Antonis Michail cautions against reading too much into the slip, given that anything appearing in the top ten of port concerns should still be viewed as a priority consideration. Indeed, with air quality occupying the number one slot in both 2013 and 2016, it could be that some respondents simply preferred to use this much broader category to register priority, rather than simply referring to dust.

Asked whether the weakening position of dust in the survey might also reflect the fact that the war against dust pollution has been won by dry bulk terminals, Mr Michail dismisses this interpretation, pointing out that much still needs to be done. “Of course there is room for improvement when it comes to suppressing dust pollution from dry bulk handling installations in ports,” he says. “However, it all comes down to how much money is available to invest in the necessary means to do so.”

In particular, he points to the Spanish port of La Coruña, where concerns were such that major investment has been made to improve the environment. A leading coal handling port, the presence of residential areas around the port prompted the port authority to encase all its coal handling activities within a pyramid-style structure, preventing dust from escaping into the atmosphere.

Underlining the importance of the issue, the port authority has gone even further, undertaking a entirely new outer harbour development, far removed from the city, where future dry bulk handling will take place.

“Dust is often at the centre of the port-city relationship debate,” Mr Michail says, acknowledging the example of Chennai, in India, which effectively banned dry bulk handling from the local port given the amount of pollution it was causing in the neighbouring city. “In the end, all ports are granted their licence to operate and to grow from their local communities,” he adds.

“In some dry bulk terminals, I think it will be possible to get close to zero dust emissions; it all depends on how much money ports and terminal operators are willing to invest,” says Mr Michail .

Sealed in

As for dust suppression technology, he notes that sealed handling units, which nowadays feature heavily in such areas as conveyor systems, have done much to improve air quality in ports. Many ports, he points out, are still using established sprinkler systems to dampen down dust emissions and these are having a positive effect, although in many cases more needs to be done to further control dust suppression in ports.

In the view of Martin Phillips, sales director of SAMSON Materials Handling, the generation of dust in a dry bulk terminal is very much dependant on the commodity handled and the equipment used.

“Modern handling equipment, using sophisticated dust suppression systems, can eliminate almost all dust from the process. The main issue during handling revolves around where material enters each phase of the transition,” he says.

How effective dust suppression systems are is mainly dependant on the operation of those systems and on maintenance. If these are done correctly then efficiencies can be into the high 90 percents, he says.

“Dust mainly occurs when moving material from a vessel – for example when using grabs – to an ongoing system, or from a transition point between one system and another, by which I mean conveyor-to-conveyor, or conveyor-to-truck. These are the areas where the understanding and initial design makes a huge difference to dust suppression,” says Mr Philllips.

As to whether there is a financial case for ensuring that dust suppression can be almost 100% effective, he says that, if the correct experience and knowledge is applied at the design phase, it is possible to achieve the maximum possible dust suppression within a reasonable fixed budget. After that, the training of operators and the maintenance of equipment as per operating guidelines will ensure these dust suppression levels are consistently realised.

“The cost implications are in the maintenance programmes and this can be calculated accurately at the design phase to provide a clear cost of operation and accurate guide to return on investment,” he says, adding that near total suppression of dust can often be helped by seeking advice in respect of transition points and then ensuring that advice is applied.

“At SAMSON, we work alongside our specialist partners to run a system of continuous improvement. Over 50 years’ experience means our current systems are at the front of innovative design,” he says.

Economic pressures

As to whether the terminals themselves or legislators are driving the need to suppress dust, he notes that the pressures on SAMSON’s customers are economic.

“However, these economics are driven by environmental pressures in areas that are often close to urban conurbations and/or tourism hot spots. The reality that ever more rigorous legislation will be imposed in this area encourages our clients to think long term. Our own products, for example, are designed to be in operation for long life cycles (25+ years), so this makes economic sense.”

In respect of dust suppression technology, Mr Phillips says that this has been radically rethought over the years. Massive steps forward have come from the development of dust filtration systems and how these are integrated into the overall design of the equipment.

“This enables us to offer highly effective and efficient solutions with a very positive return on investment. These radical new designs also enable us to give customers unique performance guarantees that in the past could not have been offered,” he says.

PORT SAFAGA CLEANS UP PHOSPHATE DUST

Not all dust is emited by grain or coal shipments; at the Egyptian Red Sea port of Safaga export phosphate is the culprit.

The facility is owned by the country’s Transport Ministry, which concluded that the original shiploader configuration no longer met current environmental standards, so contracted Dust Control and Loading Systems (DCL) to suggest an alternative.

Up to that point, Port Safaga’s incumbent telescopic loading spout had operated without any dust control systems in place at all; the result was clouds of phosphate dust overhanging the port.

DCL worked with local partner and general contractor Tech Trade to dismantle the existing equipment and provide an alternative capable of delivering load pulverised phosophate rock at 1,000 tph into open vessels.

However, there were financial constraints, which meant having to retain the existing mounting structure in a relatively unmodifed state, allowing the new equipment to be as light as possible. At the same time, DCL’s technology also had to interface with already installed control systems.

Despite the restricted budget, DCL was able to justify the provision of three custom-designed elements for Port Safaga; off-the-shelf elements not meeting requirements.

The first was a pivoting gimbal, which allows the load out equipment to remain vertical during luffing.

The second was an aluminium compact filter module, which was installed directly above the loading spout so that all duct work could be eliminated and any dust that it collects reintroduced back into to the product flow.

The final part was a retractable loading spout, whose design would allow loading at rates of 1,000 tph. In many ways, this was the key element, since it is equipped with a ‘Deadfall’ dust suppressor at the discharge end of the spout. This proprietory technology was developed specifically to enable dusty materials to be loaded directly into open ships and barges.

Typically, this working end of loading equipment is heavy on maintenance; however, in the design supplied to Port Safaga, there are no mechanical or electrical components. Not only does this obviate the need for regular maintenance interventions, but also cuts out potential failure points, thereby improving reliability rates when loading vessels.

Source: Port Strategy