Articles & Case Studies

Versatility and performance in a tight spot

Posted: Wednesday 13th February 2013

A long History

Shoreham Port on the South Coast of England has a rich history of commerce. It can trace its history back to Roman times, in the middle ages importing wine and exporting wool, as well as undertaking national tasks, such as becoming the Royal Arsenal and shipbuilding for King Edward the III in the 1300’s. In the late 1800’s, the ability to handle coal imports created a major gas works and electricity generating station.

Today it is a thriving commercial Port, with a mission to provide a first class service to customers, to continue to develop an excellent infrastructure and facilities to meet their requirements, in a commercially economic and efficient way. It now hosts a modern gas fired power station, the port operates terminals that handle timber, steel, wood chip, bulk aggregates, grain via conveyors/silos, general and project cargoes and heavy lifts. It handles over 2 million tonnes of cargo every year.

Lock control

The port has two sea-locks; Prince George and Prince Phillip: one for smaller/leisure craft, the other for larger shipping. They ensure the level in the basin is maintained while allowing sea traffic in and out of the port.

To control the locks, they have 3 VEGA ultrasonic level systems fitted to the smaller Prince George lock - the first on the port side, a second inside the leisure lock and a third on the outside (to sea). They are mounted in tubes to protect them from the environment and to ensure they provide a reliable reading. These tubes occasionally need cleaning inside, due to the build-up of marine creatures and debris. The gates on the larger ‘Prince Phillip’ lock are called ‘mitre’ gates, these are designed to be held shut by the water head pressure. Before they open, it is important that the water level is equalised (within 150mm), otherwise the mechanical linkages will be damaged by the hydraulic systems trying to open the gates against too much pressure. They had no level system within the ‘Prince Phillip’ lock and there were occasions when the level between this and the port or the sea was incorrect before attempting an opening.

Application

On receiving an Innovation Mailer for VEGAPULS WL61 water radar, the engineer at Shoreham Port contacted VEGA to look at how they could measure the level inside this larger sea lock. The requirement was to protect the gates, so they would only be opened when the levels either side were the same, to reduce possible future maintenance and damage costs.

They had no stilling tubes mounted in this dock and installing one would be difficult, costly and prone to damage. There is also a risk and cost to personnel working in this area, as well creating further maintenance/cleaning requirements. Limited space to install a tube was also a consideration, as the large ships that pass through do not leave much room, anything protruding into the lock would be very likely to be damaged. A non-contact system would be the best option, but ultrasonic transducers require protection by mounting in a stilling tube system to protect them from weather and wind as this can affect the accuracy and performance in an open water level measurement.

The non-contact VEGAPULS WL 61 has proved an ideal solution, it doesn’t require any stilling tube arrangement, as it is unaffected by environmental conditions such as rain, sun and wind. The unit was sited in a wall recess to accommodate the gates when in the open position, which serves to protect the radar, particularly when ships are passing through. It was mounted with the standard large St.St. bracket. The narrow beam angle of the radar enabled it to work even though it was mounted close to the side wall without creating false signals, which would normally result in incorrect readings. It also maintains excellent accuracy monitoring the level over an 8m range to within a few mm, well within the 150mm differential range required to operate the lock gates safely.

Foam does occasionally occur on the surface, caused by algae in the water, but this does not seem to affect the readings either. Although a reading is not required with the sea lock gates in the open position and very close to the sensor, the WL61 can still take a reading down to the water level!

The Technology

Radars use pulsed microwaves rather than sound waves emitted on ultrasonic devices. Why? this is because the accuracy of microwaves are unaffected by environmental conditions such as wind, temperature, rain and sun, thus providing dependable readings. The VEGAPULS WL 61 is a radar level sensor like no other; designed for use in the water sector, it is a loop powered device for easy connection, it has an IP68 (2bar) housing for excellent environmental protection, 15m range and minimal blocking zone with mm accuracy, to provide maximum application flexibility. This radar is also the first in its class to meet the latest EN standard for use out in the open. As a very cost effective solution, it provides reliable performance and minimal maintenance with a non-contact level measurement.

Future plans and potential

VEGA have supplied radar level sensors across the UK on sea, river and harbour measurements, from the very long Humber Bridge in the North, to the Thames Barrier in the South. This is one of the first WL61 units used in this type of application, but not the last, as the customer is already discussing using a unit on their dry dock level!




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