The waste recovery centre, which includes renewable energy generation from the waste, needed to ensure the reliability and longevity of its power generating assets. Hydrex water treatment chemicals from Veolia Water Technologies UK (VWT UK) have simplified management of the boiler water quality, as well as ensuring overall efficiency and protecting the unit, turbine and pipework.
At the facility, three technologies are brought together to treat household ‘black sack’ waste. Mechanical treatment sorts and separates recyclable items and biodegradable content from the rest of the waste. Anaerobic digestion technology is used to process the food and biodegradable material in order to produce renewable energy as well as a compost material. All remaining waste is then used to fuel an advanced thermal treatment (ATT) plant. The process creates synthesis gas (syngas) through gasification, which is then used to produce high temperature steam to generate renewable electricity in a turbine.
Using the anaerobic digestion and ATT technologies, the site is able to produce enough energy to power around 11,000 local homes. It also diverts 97% of its local area’s waste from landfill, providing a more sustainable solution to waste management and reducing the costs to the local council.
High quality water for the steam generation is an important factor in the operation of the power generating assets on site. The existing water treatment solution consisted of three different chemicals and while it was working when properly dosed, the management of the chemicals, which had to be manually controlled, was complex and time consuming. The chemicals were often overdosed, requiring a blow-down – discharging water from the system and replacing it with feedwater – to correct the imbalance.
David Broster, Business Development Manager at VWT UK explained: “Through meetings with the customer, we ascertained that a robust chemical treatment programme was required to help them comply with boiler water standards and the steam turbine manufacturers specification for steam quality. Specific requirements for the customer were control over pH and conductivity levels within the steam and condensate return, and boiler water.
“We recommended Hydrex 1815, a neutralising amine product that would allow control of the pH of the steam and condensate to support the inhibition of corrosion in the steam and condensate lines. This was complemented by the addition of our oxygen scavenger Hydrex 1316, which is ideal for high pressure boiler water applications.”
The system has been set up to add the chemicals via a measured continual feed, with minor adjustments made by the team on site as and when necessary. By minimising the instances of overdosing, it has reduced the facility’s overall chemical usage and made it more predictable, allowing a cost saving to be made. The customer has also cut the amount of additional water needed by reducing the need for blow-downs – further lowering costs – and minimised the time spent managing the process.
The VWT Hydrex™ range of water treatment chemicals includes both organic and inorganic chemicals formulated to meet specific needs for a wide array of industrial and municipal water applications. This includes boiler and cooling tower water treatment, process water production, legionella management and wastewater treatment.
In addition, VWT has recently been awarded a service and maintenance contract to provide chemical analysis and analytical instrumentation servicing as well as the chemical supply to the site.