The total organic carbon (TOC) is a measure of by qdw43728

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                       Lowering TOC levels
     Hanoviaʼs medium pressure UV technology has been chosen for TOC reduction in boiler feedwater at the
                      newly constructed Kaeng Khoi 2 power plant in Saraburi, Thailand




T
       he total organic carbon (TOC) is a measure of the            supplied the demineralisation plant decided to use Hanovia UV
       organically oxidisable content of a sample. TOC can          technology because of the companyʼs international reputation
       cause corrosion in the boiler systems of power plants so     for reliability and customer service. Other important factors
its reduction is essential. Most plants set maximum limits for      were the low pressure drop through the UV chambers and
TOC in boiler feedwater, the level depending on the pressure        the systemʼs overall ease of use compared with competitorsʼ
of the boiler – the lower the pressure, the lower the purity        equipment.
requirements. The majority of organic compounds found                   All Hanovia UV units can be easily integrated into plant
naturally in water can be removed by physical processes like        control systems. Maintenance requirements are minimal –
ultrafiltration or by ion exchange. Some organic compounds,          typically the UV lamps only need replacing once a year, an easy
however, require additional steps for their removal or              operation which can be carried out by on-site personnel.
destruction.                                                            Kaeng Khoi 2 is a gas-fired thermal power plant situated
     Hanoviaʼs medium pressure UV systems are specially             in Saraburi province north of Bangkok. The plant has two
designed to achieve extremely high degrees of TOC reduction.        combined cycle power generators with an output of 724MW
They achieve this with special UV lamps that break down TOCs        each.
and other low level organics in two ways: firstly, by dissociating       Based in the United Kingdom, Hanovia is a world leader
their molecular bonds; and secondly, by generating aggressive       in UV disinfection technology for processing applications.
hydroxyl radicals from water molecules, which also break            The company has over 80 yearsʼ experience in the design,
down TOCs.                                                          development, manufacture and distribution of UV systems
     The Hanovia UV system at Kaeng Khoi 2 is integrated            worldwide.
into a demineralisation plant supplying water for the boiler                                                  Enquiry No: 026
feedwater system. Following
softening and clarifying
pre-treatment, the water
passes through fine sand
filters and then undergoes
reverse osmosis to remove
TDS (total dissolved solids)
before passing through
two Hanovia chambers.
Positioned in series, each
chamber contains six
medium pressure UV lamps.
Following UV treatment the
water undergoes polishing in
a mixing bed prior to use.
     The two Hanovia UV
chambers treat a combined
water flow of up to 400m3/.
Actual TOC input to the UV
chambers is 183ppb and
output is 58ppb – a 68%
reduction and well below the
required minimum required
concentration.
     The contractors who




34       Water & Wastewater Asia • May/June 2008

								
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