Product category:
Testing, analysing and monitoring equipment
News Release from: ABB Automation Tech (Instrumentation + Automation) | Subject: Packaged analytical equipment systems
Edited by the Engineeringtalk Editorial
Team on 25 September 2006
Packaged systems analyse water chemistry
Three ABB packaged analytical equipment systems supplied to npower's 1500MW coal-fired Aberthaw Power Station in Wales are ensuring continuous monitoring of feed and boiler water chemistry.
Three ABB packaged analytical equipment systems supplied to npower's 1500MW coal-fired Aberthaw Power Station in Wales are ensuring continuous monitoring of feed and boiler water chemistry Careful monitoring of boiler conditions is necessary to prevent corrosion and build-up of scale, protecting the plant and making sure it is in good working order
The make-up water is abstracted from a nearby borehole and is de-ionised by the station's on-site water treatment plant.
Ammonia and hydrazine are dosed into the feed system and caustic soda is dosed into the boilers to help regulate the boiler chemistry.
If applied in overly-high quantities, these dosing chemicals can actually accelerate boiler corrosion, potentially resulting in premature boiler or condenser tube failure.
If the de-ionisation plant is not working well, the feed water will also contain high levels of contaminants such as silica and sodium, which could impair efficiency.
ABB's cabins were installed to replace the station's old monitoring laboratory, which had to be demolished as part of an upgrade of the site.
Measuring 3.25 x 1.2 x 2.2m, each cabin is situated adjacent to one of the station's three boilers, allowing shorter sample pipes and quicker problem identification and resolution.
Each of the three packaged systems measure direct and after cation conductivity, sodium, hydrazine, pH, dissolved oxygen and silica and consist of: three conductivity cells plus transmitters; one pH cell plus associated transmitter; one sodium monitor; one hydrazine monitor; one dissolved oxygen monitor; and one three-stream silica monitor.
These parameters were previously being measured in the old laboratory, but with longer sample pipes and older instruments, which had a consequent effect on accuracy.
By installing the cabins, the Aberthaw team expects to see improved accuracy.
The shorter pipe lengths between the boiler and generator plant and the cabins will cut the delay in obtaining samples for analysis.
In addition, the new instruments include alarms for low flow, plus an automatic temperature alarm and shutoff if there is a problem with the cooling system which might damage the equipment.
Together, the cabins will provide a total boiler chemistry control system aimed at optimising the efficiency of the station's boiler and generator plant.
"You can imagine that with the high temperatures and pressures in our boilers, any contaminant ingress can become highly corrosive".
"This could lead to a boiler tube leak, causing us to bring the plant off load, which is incredibly costly", says Richard Powell, npower's Assistant Chemist at Aberthaw Power Station.
"We want to make sure the levels of contamination are as low as possible and that the chemical balance is ideal to prevent corrosion".
ABB was chosen for the project for its consistently high level of support and expertise.
Powell feels that the service aspect is as important as the quality of the product when making a purchasing decision.
"There is no point putting in the best equipment and forgetting about it as it will only fail", says Powell.
"Equipment needs attention to perform at the highest level, that's why we have signed up to a service agreement which means a service engineer comes in once or twice a month to check that everything is working well and to calibrate the equipment where necessary".
"We are very pleased with the level of service we are receiving and feel it is a vital aspect".
ABB has over 25 years experience in building packaged system assemblies and can offer a wide choice of standard designs which can be customised to suit individual applications.
Supplied fully premanufactured and pretested, ABB's packaged analytical systems are delivered ready for operation.
Only connection to samples, cooling water, drains, power supply and signal outputs is necessary on site.
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