Keeping the noise down

As global populations swell, the world’s cities sprawl outwards towards ports and harbours once isolated from urban areas. Many elements can cause environmental deterioration near these sites. Today, the profound effects of pollution from engine exhaust fumes and cargo dust emissions are being more effectively managed. However, the widespread effect of high noise levels is less well-understood and pressure is mounting to make industrial areas quieter.

“The growth of ports and increasing populations in port towns and cities means that cargo handling equipment is often in operation in very close proximity to residential and business areas,” says Ola Johansson, Technical Project Manager, Siwertell. “To lessen the conflict between ports and their occupied urban space, strict environmental and safety standards must be met.”

One company that has taken this very seriously is Ørsted, formerly known as Denmark Oil and Natural Gas (DONG) Energy. In line with Denmark’s environmental regulations, when Siwertell delivered an ST-790-M high-capacity unloader to the company in 2013 it had to meet unusually strict requirements for noise levels. As a result, the unloader, which serves Ørsted’s Avedøre combined heat and power plant, was delivered with special sound-deadening upgrades fitted.  

Testing the technology

Once operational, Siwertell commissioned a Swedish urban planning consultancy and acoustics specialist to carry out noise-mapping tests at a number of points around the Siwertell unloader at Ørsted’s discharge berth in Copenhagen. 

The engineers measured the degree of noise from a Siwertell machine under a full workload, and the noise level inside the operator’s cab was also measured. Outdoor noise on the walkway between the quay and the operator cab was found to be 76 dBA (mean level), which is quieter than the average food blender and akin to living room music. Meanwhile, inside the operator’s cab, the sound was 50 dBA, only somewhat louder than a bird call or the ambient noise from a city at night. 

    “No unloader can operate silently and so the machine would still require hearing protection at close proximity as a matter of course. But the low frequency means it does not carry over long distances,” explains Mr Johansson. “For nearby populations, the effect is negligible, underlining Ørsted’s commitment to the wellbeing of the Danish people.”