Intelligence at Your Fingertips, Keeping You in Control
Utilisation of microprocessor burner controls, flue gas economisers and thermal improvements in boiler lagging have enabled boiler manufacturers to achieve significant improvements in boiler efficiency: heat input minus the sum of the losses. Stated efficiencies are based on ‘IDEAL’ conditions, the reproduction of which under actual operating conditions is entirely dependent on how much care is taken by the boiler operator.
Boiler efficiency calculations are based on the assumption that all the heat transfer surfaces are clean and the boiler is operating at its maximum continuous rating (MCR). In order to ensure that the design efficiency can be maintained throughout the lifetime of the boiler all parts in contact with water must remain clean: scale and corrosion free.
It is one thing designing and building boilers with improved thermal efficiency it is an entirely different matter maintaining that efficiency throughout its operational lifetime.
The responsibility to maintain efficiency over the lifetime of a boiler falls squarely on the shoulders of the owner/end user and how effective their control regimes are. Yet few people fully realise the effect the condition of the feedwater has on the boiler efficiency and operating costs.
For instance, if the furnace and boiler tubes are not kept scale and deposit free then the thermal transfer surfaces will be compromised and you will never achieve the design output irrespective of how good the combustion process is.
The widespread use of natural gas and improvement in burner technology and control has all but eliminated gas side fouling but the water side has largely remained unchanged. Scale formation, a direct result of the inadequate application of water treatment chemicals, retards heat transfer and significantly increases lifecycle costs. Conservative estimates of 2% to 5% are based on the assumption that the scale thickness is approximately 0.75mm (1/32”) thick.
With a Gas fired boiler operating 24Seven the 2% to 5% loss in efficiency equates to between £3000 & £9000 for every 1000kgs @£17.50/T of steam generated. Increasing lifecycle costs between £75,000 & £225,500 per Tonne based on 25 year operation.
The plain truth of the matter is you can’t achieve consistent feedwater quality by testing once a day and manually adjusting dosing pumps based on one daily sample. 72 hour unattended operation simply exacerbates the situation. ‘Aquanet’ has the answer. The ‘Aquanet’ system is based on an analysis of boiler and makeup water and dosing the precise amount of chemicals needed to maintain the optimum feedwater chemistry. It is the only microprocessor
based chemical dosing system offering continuous and consistent water quality control. In brief, ‘Aquanet’ independently samples water optionally from the feed pump discharge, each boiler (up to 3) and the returning condensate in sequence, cooling the sample, testing the pH, conductivity and determining the dissolved oxygen levels. Based on the results the control system fine tunes the chemical dosing pumps and adjusts the surface blow down rate to maintain the correct feedwater chemistry and TDS levels in accordance with the recommendations of BS2486:1997, BS EN12953-10:2003 and the boiler manufacturer: ensuring that the boilers are fully protected 24Seven.
‘Aquanet’ is the only feedwater chemistry control system that enables full compliance with BS EN1295310:2003 and SAFed/CEA BG01 & BG04 with regard 72 hours unattended steam boiler operation. For further information on the ‘Aquanet’ system and how to reduce your boiler plant capital and operating costs Telephone 01254 841769 e-mail info@controls4steam.co.uk or visit www.controls4steam.co.uk
