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Flow Level Pressure Getting the Measure of the Tames
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Erith Pier Then: (above left) with cranes and ships berthed alongside, Now (above right) the cranes are gone only a hut at the end remains, which contains the measuring and telemetry equipment. A short section of the old train tracks are still visible in the foreground, crossing those for the flood wall gate used at high tides
From its source about a mile north of the village of Kemble, in England’s Cotswolds, the Thames flows 346 km (215 miles), down through London and out to the North Sea. On its journey it covers 896 km2
of floodplains and is tidal from
Teddington, West of London. It is estimated that the Thames carries some 300,000 tonnes of sediment a year and there is a 23-ft (7-m) difference between low and high tide at London Bridge. The Thames Barrier at Greenwich is one of its most recent, yet instantly recognisable landmarks, playing a crucial role in protecting greater London from flooding at high tides.
Close by the barrier in Erith, is the longest pier on the River Thames in London, which was opened in 1957. Previously Erith pier was twice the size it is now, it was built for the loading and unloading of cargo from ships. On the pier there were rail tracks and cranes so the goods could be unloaded directly onto railway trucks. In 1999 the supermarket chain ‘Morrisons’ undertook the task of repairing the pier, to make it accessible for the public, and gain permission to redevelop the riverside and build a supermarket.
The view of the radar path down to the water, up to 8.5m below the radar
Erith pier also provides an ideal site for monitoring the level of the Thames. The information gained is used in combination with other measurement stations along the river, as far out as Southend- on-Sea, to monitor and control the raising of the Thames Barrier and other sluices. Previously, inside the special cabin at the end of the pier, a pressure sensor mounted in a ‘stilling well’ was used, but the large amounts of silt that come down the river blocked it regularly, causing misreads of the river level.
The radar mounted through the hatch over the ladder in previous picture
This meant the bottom of the stilling well had to be cleaned out by divers, an exercise which was both costly and dangerous, working under the pier. It was then replaced with Vega’s (Germany) non-contact Vegapuls 62 radar level transmitter with ranges up to 75m, mounted adjacent to the old stilling well. It looks down to the river surface inside a ‘hooped’ access ladder (see picture) and follows the water level right down, even through a grid at the bottom, with no issues of silt blockage, thus providing reliable data, saving costly maintenance work and reducing risk. The narrow beam angle, false echo learn and intelligent echo processing handle any false reflections from the existing structure. The two-wire loop powered VEGA radar was installed almost two years ago and has worked reliably ever since, providing valuable data, to allow cross referencing of the river levels for traffic, barrier operations, harbour and navigation in the area, including Tilbury Docks. Further units have been purchased since to measure levels at a number of other sites along the Thames, including at the barrier itself.
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StocExpo Ltd. (UK) are very pleased to announce that the next StocExpo Europe exhibition and conference is taking place on 30th
March – 1st April 2010 at the Antwerp Expo.
As Europe’s leading Tank Terminal event, the conference programme during StocExpo Europe attracts some of the industry’s most prominent experts, while presentations from over 25 senior representatives of some of the regions’ key operators and suppliers will facilitate discussion and knowledge-sharing to enable safer, more efficient and more cost-effective management of terminals and tank farms.
A year ago things were looking bleak for the storage
sector. Rapid construction had just raised terminal capacity but demand was widely anticipated to slump as the worldwide recession took effect. In reality, business remained surprisingly buoyant for most and tank occupancy rates and throughputs remained high. And now tank owners stand to make a killing as traders and refiners a like clamour for storage space. With crude inventories in the most industrialised countries at all-time highs, global demand declining for the first time in a quarter of a century and a contango still in place, it seems likely that a significant amount of oil will remain in storage for the time being.
So with tankage demand now being the highest it has been for the past five years, the StocExpo Europe conference will provide government representatives, industry experts and market analysts with a timely opportunity to explore and discuss the region’s tank storage and terminal operations and look ahead to future plans for this buoyant and exhilarating marketing sector.
Some of the key topics to be covered include: Legislation for Strategic Stocks, European Refining in a Low Carbon World, Measuring and Managing Carbon Emissions in European Chemical Transport, Preparing an Underground Cavern for Transit Storage of Crude, REACH – Updates, Implementation and the story so far, Holistic Safety in Terminal Applications and Changing International Crude Oil and Products Trade Flows and the Implications for Storage Requirements.
Reader Reply Card No 103
Europe’s Largest International Event for the Tank Terminal Industry comes to Antwerp
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February/March 2010
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