The legionella outbreak in Edinburgh has sent enquiry rates rocketing at cooling tower specialists. But could kneejerk reactions once again overlook the fundamentals of purchasing equipment that can be properly maintained?
Colin Brown from Carter Environmental Engineers cuts to the chase. “There maybe another very unpleasant Edinburgh-type event uncovering a number of cooling towers out there that cannot be maintained properly.
If the cooling tower is designed so that it is impossible to access its internals for inspection, which goes against ACoP L8 regulations, then it may become a breeding ground for bacteria. You may have the best maintenance team in the land, but they can’t look after the tower’s components if they don’t have access to them.
“Reputable water treatment companies will turn contracts like this away because they are unable to carry out their work properly,” he adds.
Mr Brown says that the quick-fix compromise seems to be to an arbitrary overdosing of chemicals, without identifying system and tower design flaws.
Demand to bring existing cooling towers up to ACoP L8 standards has led to Birmingham-based Carter introducing a new refurbishment service, as lack of capital funds in the current economic climate means retrofit is the only option for some companies.
Mr Brown acknowledges that some manufacturers will be able to keep a cooling tower plodding on for a while, but says that the full-scale refurbishment required to make a cooling tower truly compliant is not necessarily their skill set.
He says that many maintenance engineers have become caught up in constant, ultimately losing, battle to keep their cooling towers safe.
He added: “Panic chlorination in the event of a legionella outbreak is not the answer because debris, scale and biofilm still accumulate on the pack.
The Health and Safety Executive won’t be fooled by tower users’ emergency measures because closer internal examination of their water management system will always identify where the code of practice has not been applied.”
One recent Carter customer chose the adiabatic route to remove the risk of legionella. Sertec (Birmingham), which manufactures pressed parts and welded assemblies for automotive giants such as Land Rover, Jaguar and Aston Martin, replaced their open evaporative cooling tower with Carter’s Adiabatic Water Cooler, which negates the need for water treatment.
Following a full risk assessment, Sertec required a safe (ACoP L8 compliant) cost-effective and long-term alternative form of cooling, explains the company’s works and maintenance manager Mike Russell.
“We need to conserve the cooled water used by our spot-welders with a highly efficient re-circulating system. With guidance from our health and safety manager, we wanted to remove the risk of legionella – and with it, the pressure and time-consuming task of maintenance and due diligence monitoring.
With no water treatment and no need for costly chemicals, running costs are around four-fifths less than a traditional cooling tower – or most other adiabatics.”
In addition to helping combat the threat of legionella, Carter is finding that energy savings are also high on the priority list for clients – if, Mr Brown says, those in the purchasing department can look beyond initial capital costs.
“Purchasers are always under pressure to get the best price but it is frustrating when people can’t look further than the bottom line and don’t take future savings or maintenance and repairs into account,” he says.
Mr Brown cites the fitting of fans with inverter speed control (which Carter includes on every new installation) as a simple example.
He says that a control panel with inverters would cost around double that of a standard on/off unit. However, with inverters bringing fans into use only when they are required – compared with having them run flat-out – would reduce energy usage by 80 per cent, giving payback within six to nine months.
According to Mr Brown, Carter insists on one motor per fan, which will always allow others to appear cheaper if they only use one motor for say three fans, but long term, the motor’s bearings and shaft will possibly fail under the strain.
Carter’s cooling towers have proved that they can significantly reduce energy, water and maintenance in this way at NXP Semiconductors in Manchester. Initially, two of Carter’s Forced Draught Towers (running at just 11 kW) were brought in to replace systems with dual-speed motors (running at 30 kW high speed) that would have proved uneconomic to retrofit with energy-saving invertors. After 12 months’ successful operation, a further two Carter Sandringham cooling towers, specified in 304 stainless steel, were installed (as were the first two) by Portobello Engineering.
The old cooling towers had been overflowing and were arduous to maintain, especially as the pack could not be removed easily for inspection – whereas Carter’s ACoP L8-led design, with open troughs and sumps sloping towards the drain will make cleaning and inspection much easier, the firm maintains.
In addition to designing the pipework modifications required, Carter has also made maintenance access much easier by fabricating stainless steel platforms, rails and ladders, along with a removable pack access door for visual inspection and cleaning.
Last but not least on Mr Brown’s recommendations for new cooling towers is environmental control.
“Fans roaring away at full tilt can restrict businesses’ trading hours or planning consent,” he concludes. “When close to residential areas, local authorities will often base their decision on noise levels and what hours fans are running – so if you can’t control them individually because you only have one motor and/or no inverters, then you have no flexibility and are therefore restricting the profitability and potential expansion of your business.”
Source : http://www.racplus.com/