1. Turbine Controls Limited
POSIFLOW
Liquid fuel modulation
for gas turbines
A variable speed motor driving a positive displacement
pump for reliable and accurate control of liquid fuel for
gas turbines.
POSIFLOW

2. POSIFLOW
Liquid fuel modulation for gas turbines
A vital aspect of control of gas turbines is the final flow modulation
device. Traditionally this is a valve with some form of spill flow
control. Wear and drift in the mechanical parts of the fuel valve can
lead to various operational problems:
Inconsistent light off flows, causing failed starts•
Problematic fault finding•
Inconsistent and failed fuel changeovers•
Increased spares inventory•
TCL have developed the Posiflow system to overcome the
problems associated with traditional fuel valve control. The
system operates by using the flow versus speed characteristic
of a positive displacement pump; i.e. fuel delivery rate is directly
proportioned to pump speed.
A liquid fuel system needs an HP fuel pump so why not use this to
control the fuel flow.
There is a wide range of commercially available pumps capable of
pumping the most aggressive fluids. TCL build systems to meet
these specific requirements.
The proven features of positive displacement pumps and variable
speed drives provide reliable, repeatable and accurate control.
Scope of supply option dependant on
application, examples include:
Drive existing motor and pump with PosiFlow Variable Speed•
Drive, remove liquid throttle/spill valve
Replace existing pump and drive with variable speed pump•
and motor assembly. Retain all shut-off valves and flow divider,
remove liquid throttle/spill valve
Remove all fuel control devices such as throttle control unit, HP•
fuel pump, S.O.C Filter, relief valve, replace with PosiFlow Skid.
System installations
UK utilities RWE Npower and E.ON have fitted the Posiflow system
to the majority of their simple cycle gas turbine plant in the UK.
The system has proved ideally suited for the operational
requirements of these gas turbines, i.e. fast starting at short notice
after periods of being shutdown.
Posiflow gave immediate improvements in start reliability
and availability.
The Posiflow system has been installed in many base load units
where operational reliability is key. In these applications the robust
design of the Posiflow has proved itself, being able to cope with
a large range of aggressive fuel types. These range from low
viscosity Naptha to high viscosity heavy fuel oil.
TCL have developed Posiflow systems for a number of gas
turbines including:
Rolls• Royce
Solar•
GE Frame engines•
GE Aero derivative•
Ruston•
Siemens•
Specifications
Flow rates 1 to 500 litres/min
Inlet pressure -0.5 to 10bar
Outlet pressure 5 to 200bar
Nominal supply voltage 300 Vac to 660 Vac
AC and/or DC powered Remote starting from batteries
Hazardous area system available.
An important development in the application
of pump technology and fuel modulation
Features Benefits
Flow modulation through pump
speed control
Remove separate throttle
Lower spares inventory
Throttleless control Reduced component count
resulting in improved reliability
Zero calibration cost
Hydraulically and chemically
engineered for durability
Solutions for Naptha burning
Low total life cost
Accurate and repeatable Reliable engine starting giving
peace of mind and reduced
operating costs
AC and/or DC powered Remote starting from batteries
System configuration option
of tandem Pump
Remove troublesome flow
dividers particularly useful on
GE Frame engines
Pump delivers only the fuel
required by the engine
Energy and pump wear reduction
Fuel demand signal
from governor
From LP fuel
forwarding systems
Variable speed
electric motor drive
Burners
Positive displacement variable speed method of fuel control
Rolls Royce Avon PosiFlow installation
Turbine Controls Limited
52, Kenilworth Drive T +44 (0)116 271 7248
Oadby, Leicester F +44 (0)116 271 7250
LE2 5LG UK sales@tcluk.net
Or visit us at www.tcluk.net