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Inditherm recently announced the results of successful trials for heating
sewerage sludge lines at Severn Trent Water's Minworth Sewage Treatment Works,
near Birmingham, England. The trials have conclusively demonstrated that uniform
heating of sewerage sludge pipelines has solved a significant problem with the
accumulation of fatty deposits on the inside of sludge line walls. This is a
major problem for many treatment plants, as the pipes need to be cleaned as many
as 12 times per year, with the associated shutdown, maintenance and clean-up
costs. Health and safety is also an important consideration.
Minworth Sewage Treatment Works (STW) serves a population of over 2.5 million
people. Until now, Severn Trent has experienced problems with the build-up of
fatty deposits in the discharge pipework from the centrifuge thickening plant.
This accumulation is especially acute in bends, valves and pumps where it leads
to a gradual loss in plant performance and, ultimately, the need for regular
maintenance shutdowns.
Mark Vine, a Senior Technician at Minworth, explains: "I like to use the
human body to illustrate the problem and Inditherm's solution. The vital
supplies to our sludge digestion plant were, quite literally, being restricted
by grease and fat deposits, just as cholesterol clogs human arteries. A gradual
thickening of the pipe walls leads to restricted sewage flow, requiring us to
reduce throughput by up to 20% or, in extreme cases resulting in the centrifuge
pumps tripping out. The only remedy to date has been shutting down the
associated plant for time-consuming and expensive jetting."
These maintenance shutdowns are typically required every six weeks, taking up
to two days and costing over £2,000 a time. In addition to these direct costs,
the fatty deposits also have a negative impact on Minworth's energy bills,
firstly because the sludge pumps have to work harder and, secondly, because
restricted flow to the digesters reduces the amount of methane available to
Minworth's award-winning sewage-to-energy plant. During the maintenance
shutdowns, the sludge thickening facility is bypassed, which has led to a
reduction in gas production from the digestion plant. This has a knock-on effect
in terms of loss of revenue, as the site is unable to export surplus electricity
to the national grid, having to import it instead.
Vine continues: "The trial with Inditherm has been extremely impressive to
date, with almost no fatty deposits observed in the two inspections since the
heating jackets were installed in December 2005. In addition to immediate and
quantifiable benefits in the sludge routes, Inditherm's solution is also
contributing to efficiency gains across the whole plant. Further installations
and monitoring will reveal quite how much we stand to gain in the long term.
Since the tests have only been completed on line 1 of 2, we are still having to
jet clean line two every six weeks as before."
Inditherm's solution applies a safe, low voltage across its unique, patented
carbon-based polymer to generate a uniform heat. At Minworth this polymer is
encased in heating pads which are strapped to the pipes and covered with
conventional insulation and metal cladding.
Although Inditherm was confident that they would see a significant reduction
in fatty deposits, the trial results far exceeded even the most optimistic
expectations, showing no build up at all.
This latest application adds to Inditherm's growing range of heating and
insulation products for the utilities sector, including chemical dosing line
heaters and thermal jackets for pipework and storage vessels. As such, Inditherm
is especially well positioned to help water companies respond to the efficiency
challenges posed by the current AMP4 infrastructure programme in the
UK.
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