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Dual Laminate Waste Stream Headers
Provided to the Solar Cell Manufacturing Industry
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| Background: |
In the beginning of 2009 one of the world’s leading solar energy businesses and producer of silicon materials for photovoltaic (PV) applications and PV wafers built the world’s largest integrated solar manufacturing plant in Tuas, Singapore.
PV wafers
atea designed, built and installed the waste water treatment system at this plant.
Two custom-designed waste stream headers were part of the treatment system built by atea.
Challenge:
As soon as the waste water leaves the pumps in the waste water treatment system, the pressure starts to drop and the waste stream becomes uneven.
When atea designed the waste water treatment plant for this client there was a desire to avoid this fast pressure drop and uneven flow, therefore waste stream headers were designed to maintain an even
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flow and a high pressure in the plant also after the pumps.
The necessary pressure rating for the headers were 1.75bar above the maximum operating pressure. The operating pressure of the pumps installed in front of the headers is 5bar; hence the headers need to be designed to have a pressure rating of at least PN6.75.
A thermoplastic header DN 350 in PE or PP has an initial pressure rating of PN10, but the actual header rating is only PN6 after the nozzles have been welded in, as extrusion welding reduces the pressure rating by factor 0.6.
A pressure rating of PN6 (10 × 0.6) would be too low in this case; hence a thermoplastic header cannot be used. A more pressure resistant material must be used.
PP Header installed at a waste water treatment plant
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Solution: |
It is common to use pressure resistant but expensive materials such as Hastelloy c22 or Carbon Steel lined with PTFE for this kind of applications. These headers are very costly. Therefore it was decided to use a more economically viable, but still pressure resistant, material: dual laminate for this project.
Dual Laminate consists of a thermoplastic in-liner which is bonded to a FRP outer layer. A wide range of thermoplastic and FRP combinations can be selected.
After careful calculations and engineering it was decided to manufacture the headers for this specific project in PP/ FRP. The FRP reinforcement of the PP liner would ensure a sufficient pressure rating and protection against external damage.
Pressure test of composite header
Two headers were manufactured for this waste water treatment plant:
Header DN200 – For the HF waste stream
Header DN500 – For the Non-HF waste stream
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Header DN200
Header DN500
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Advantages of Dual Laminate Headers: |
Design
Compared to other commonly used
resistant material such as Lined Carbon
Steel and Hastelloy atea’s dual laminate
headers have several advantages when it
comes to the design:
More Modification and repair
possibilities after construction as
FRP is a highly flexible material
Reduction of flanged connections
(as parts are connected through joint
lamination), which contributes to a
more lightweight construction
Stability in vacuum (due to the
adhesive strength between liner and
FRP reinforcement)
Better design flexibility. Below follow
a few example of features which can
be tailored into the design
- Conductivity: For Ex Zones as
there might be explosions and
sparks inside the headers here
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Conductive PPs-el/ FRP Header with 24 branches
- Fire retardant properties
- UV resistance: For outdoor use
- The type of thermoplastic in-liner is
always selected in order to best suit
the prevailing conditions e.g. PVDF
or more resistant thermoplastics are
commonly used as lining in plants
where solvents are present or the
temperature is high.
- etc
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Graph illustrating the temperature resistance of various thermoplastics (commonly used as in-liner in dual laminate
products) in an ethanol solution
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Price: |
When it comes to the cost, as already mentioned dual laminate material is a better choice.
For the above mentioned project the following initial cost savings were made compared to if Lined Carbon Steel or Hastelloy would had been used:
Price Compared to Dual Laminate (DL)
Also the maintenance costs for dual laminate headers are minimal due to that:
FRP do not undergo corrosion
Dual laminate material is easy to clean and maintain
Dual laminate material requires min. environmental protection
Other Applications:
These types of dual laminate headers can be used not only in waste water treatment plants, but also in other water treatment plants and in all other applications where there is a need for waste stream headers.
The use of dual laminate headers is a viable solution when thermoplastic headers cannot be used due to that the required pressure rating is too high and/or there is a risk that external environmental factors might damage the thermoplastic.
atea has provided dual laminate headers to the textile industry, semiconductor industry, solar cell manufacturing industry, chemical industry etc.
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