Fulton Ancillary Equipment SteamPac Unfired Steam Generators - Manual (Page 40)

Fulton Thermal Corp.*SteamPac Unfired Steam Generators Manual* Version 2010-0201
Page 40
3. Steam Pressure Controls
a) The basic controls consist of a thermal fluid control valve which varies the rate of flow of
hot fluid through the heat exchanger. This valve may be modulating type and be either
electric motorized, pneumatic, or solenoid operated. It is this valve’s operations that
controls the steaming rate of the generator. It is operated by means of a steam pressure
switch or control mounted on the control panel which monitors steam pressure.
b) The pressure control, if of the modulating type, will have a set point which it will try to
maintain via an analog output to a three-way control valve (or 2-way modulating valve).
c) When the desired steam pressure has been reached, the pressure switch contacts open
to de-energize the control valve which stops the thermal fluid flow into the generator.
Note
Pneumatic control valves are operated by controlling the air supply to the valve
diaphragm by means of a solenoid valve integral to the actuator body. These
valves have a spring return and will shut off thermal fluid flow in case of control
circuit failure. Minimum 80 PSIG clean, dry instrument air is required. Consult
valve O&M manual for SCFH of air required.
4. Feed Pump Control
a) Water is fed into the base of the steam generator by the feed pump. This pumps a preset
quantity of water into the generator. The quantity is usually just in excess of the steaming
rate to avoid superheat, afford control, and to carry dissolved solids.
b) The feed pump is controlled by means of a high water level probe or float device located
in the water bottle attached to the side of the steam separator (or steampac).
5. High Steam Pressure Control
a) The unit is fitted with an excess steam pressure switch which will shut down both thermal
fluid flow. This is a manual reset switch and must be reset before operation of the unit will
resume.
6. Steam Safety Valve
a) The steam safety valve is fitted to the top of the steam generator shell to prevent excess
steam pressure if the controls were to malfunction. It is set at the maximum design
pressure for the generator. When modifying the operating pressure, do not alter the
safety valve setting.
7. Steam Pressure Gauge