FULTON RBC1250 - Internal Economiser (if Fitted)

RB-RBC-IOMM-2015-1
Fulton Ltd
Page 26
OPERATION - 3
Feedwater from a constantly running modulating pump is passed through the economiser before
entering the boiler.
Heat is extracted from the boiler exhaust gases by the economiser which in turn heats the
feedwater to temperatures that can exceed 100 °C.
Backowispreventedbynon-returnvalveinthefeedwaterpipeworkontheinletofthe
economiser.
The economiser is designed to reduce the boiler exhaust temperature to approximately 140 °C,
ifthetemperaturefallssignicantlybelowthisgurecondensationwilloccurwhichcanleadto
corrosion.
Theeconomiseristtedwithinletandoutlettemperaturegaugesforbothfeedwaterandexhaust
gas. These gauges should be used to monitor the condition and performance of the economiser.
Note: Sudden changes in temperature should be reported immediately as they could indicate a blockage of the
economiser water ways, or a malfunction of the modulating feedwater control valve.
Ingenerala10°Cincreaseinfeedwatertemperaturewillgiveanefciencyimprovementof2%.
Because the boiler feedwater modulating control valve and the burner are both proportioned
tothesteamload,theburnerheatinputandcoolingwaterowratetotheeconomiserarein
balancethroughouttheburnerringrange.
A DN20 spill back line with a pneumatically operated piston valve is installed in the feedwater
pipework in the discharge from the pump, the outlet from this valve must be piped back to the
feedwater tank. The purpose of the spill back line is to prevent the constant running feedwater
pumpfromoverheatingshouldthewaterlevelreachthemaximumworkinglevel.Anorice
plateisttedinthespillbacklineinadditiontothepneumaticallyoperatedpistonvalve,witha
manually operated/adjustable globe valve for making small adjustments to the spill back water
owrate.
3.7 INTERNAL ECONOMISER (IF FITTED)
Figure. 17 - Typical Internal Economiser
Internal economisor
Boiler feedwater inlet
Boiler feedwater
economiser bypass valve
Boiler feedwater
economiser inlet valve
Boiler feedwater
economiser outlet valve