Cleaver-Brooks C1X Series, Operation Manual

Standard Economizers

Part No. 750-266

1-13

7.  The Delay Timer keeps the bypass and steam valve open until the cylinder returns to its original position.
8.  The Damper control and Control Valve then return to the normal heat recovery operating position.
9.  Upon completion of the sootblowing cycle, the Duration Timer resets for the next period.

1.7.3 - Circulating Recovery System

The Circulating Recovery System/Tank assembly is a separate system used as an alternate to
converting on/off boilers to modulating boiler feed water systems for preheating boiler feed water.  The
CRS/Tank assembly is a more economical and safe alternate system to select, primarily because it does
not affect the existing system or require major engineering considerations. 

CRS Operation:

TUBE SIDE: 

 Boiler feedwater normally entering the boiler instead enters the bottom of the vertical

pressurized tank (ASME designed and stamped) or essentially a `bulge in the feedwater flow line'.  Two
spring loaded check valves hold the water in the tank when the boiler feed pumps shut off. The
circulating pump, located within the added closed loop circuit, circulates the colder water from the
bottom of the tank through a flow control valve and a check valve to the economizer to be heated with
recovered BTU's and then back to the top of the tank. When the boiler feed pumping system operates,
the water enters the bottom of the tank and heated water leaves the top of the tank and enters the
boiler.

SHELL SIDE:

  As the temperature at the exhaust outlet of the economizer begins to drop to a safe

operating exit temperature, the flow control valve is adjusted to maintain the proper flow required to
stabilize the minimum desired gas temperature.  The differential pump controller can be installed at
the outlet of the boiler economizer stack. It will shut the pump off if the stack temperature falls below
the preset point (250 deg F on gas, 275 deg F on No. 2 Fuel Oil) and energize the pump at 300 deg
F. This occurs during burner off cycles or low load conditions. The pump controller is also field
adjustable and can be adjusted to a lower or higher point as required. 

Certain applications with continuous water circulation may not require the installation of a differential
pump controller. Consult the factory for suggestions as applicable.

PERFORMANCE:

 The fuel saving net result is that the boiler requires less Btu/hr to raise the now higher

boiler feed temperature to the desired operating steam temperature. During all firing modes and on/off
feed pump operations, all wasted exhaust heat above the 250'F entering the economizer will be
recovered in the boiler feed water with the Circulating Recovery System/Tank Assembly and with no
mechanical or increased temperature effect on the existing boiler feed system.  The difference is the
temperature of the boiler feedwater being elevated significantly with wasted BTU's normally exhausted
out the boiler stack. The firing rate at the boiler is now lower and thus the total Btu/hr input
requirement at the burner is reduced, while still producing the same amount of steam as it had in the
past. Since the firing rate is reduced in terms of Btu/hr required, the fuel bill will now be lower.