SigmaFire Installation Manual, rev. F - Clayton Industries

SECTION III - CLAYTONFEEDWATER SYSTEMS3.1 GENERALClayton steam generator feedwater systems are designed with an open (hotwell), deaerator(DA), or Semi-Closed Receiver (SCR). The selection of the proper feedwater system is determinedby the steam generator’s application, the installation environment, and other factors. Eachsystem is discussed in detail in later paragraphs in this section.The feedwater system’s pipes, as well as the heating coil, are susceptible corrosion ifproper feedwater treatment is neglected. Corrosion in the pipes are due to three fundamental factors—dissolvedoxygen content, low pH, and temperature. Oxygen is required for most forms ofcorrosion. The dissolved oxygen content is a primary factor in determining the severity of the corrosion.Removing oxygen, and carbon dioxide, from the feedwater is essential for proper feedwaterconditioning. Temperature and low pH affects the aggressiveness of the corrosion.Deaerators are designed to remove most of the corrosive gases from the feedwater. Deaerationcan be defined as the mechanical removal of dissolved gases from a fluid. There are manytypes of Deaerators; however, the ones most commonly used for deaerating boiler feedwater arethe open (atmospheric), pressurized jet spray, and tray type. To effectively release dissolved gasesfrom any liquid, the liquid must be kept at a high temperature. Deaerators are pressurized aboveatmospheric pressure (typically 3–15 psig) to maintain the feedwater at a higher boiling point.The increased pressure and temperature releases the dissolved gases from the feedwater and thosegases are vented to atmosphere.There are four skid package options available depending on the feedwater system (alloptions are not available for all models - contact your Clayton Sales Representative). The systems,skid package options, and required customer connections are described below.3.2 SKID PACKAGESA. Individual Components The steam generator unit and all water treatment componentsare furnished separately. Placement of each component and its assemblies and interconnectionsare determined by the installer.B. Feedwater Receiver Skid A separate skid consisting of the feedwater receiver,booster pump(s), and electrical control box mounted on a common frame is provided along withthe steam generator. Interconnecting piping between the feedwater receiver and booster pump(s),if applicable, and feedwater receiver trim component mounting, are included. If applicable (>200bhp), electrical connections between the water level control, makeup water valve, and skid electricalcontrol box are also included. No other water treatment components or interconnections areprovided on this skid.04/22/2015 3-1 Sect03_FeedwtrSys_SF_f.fm