Boiler feedwater quality is a critical issue affecting both system performances and boiler reliability. Cannon Bono Energia’s skilled technical staff, thanks to the support of its Sister company Cannon Artes, is able to guide the customer in choosing the best available solutions.
Feed water quality depends on the applications and operating pressure.
The main target of boiler feedwater treatments are:
- avoid corrosive phenomena on the boiler surfaces and tubes
- reduce scaling and maintain high heat transfer efficiency
- maintain the quality of the generated steam in compliance with the requirements of the manufacturers of critical equipment.
The main boiler water treatments are Demineralization, Thermo-Physical deaeration and Condensate Treatment.
Demineralization plant – Very low hardness concentration is required for boiler water feeding together with a low Conductivity (low TDS concentration) necessary to reduce the blow-down (heat loss). Two different types of treatment can be used, membrane based technology (reverse osmosis and electro-deionization) and ionic-exchange solutions (Softener, demineralization and mixed bed). According to the available water source (well, river or sea) dedicated pre-treatments are necessary (filtration, Ultrafiltration, chemical process – in some case in combination).
Deaerators – These are necessary to remove CO2 and O2 in order to prevent corrosion phenomena. The choice could fall on conventional packages composed of tower (where gasses stripping happens) and drum, or the compact –“Smart” unit in which the degassing equipment is realized inside the drum. According to the type of unit installed the achieved performances fall in the range of 7-20 ppb.
Condensate Treatment – Condensate treatment is necessary to purify condensate steams coming from the process. In this way it is possible to reduce water consumption and recover the heat contained in the condensate.
Dosing of chemical products: The main products used within the thermal circuits are the oxygen scavengers used as a protective dosage downstream of the thermo-physical degassers and the alkalizing agents dosed to maintain a high pH inside the boiler.
Not only a technical requirement, the choice of a proper water treatment also represents an energy optimization of the steam generator / water treatment package, and a source of savings both in terms of water extraction and cost of discharge, so it deserves the right attention.