A closed-loop PID controller is used to control the % volume of water added to the fuel in real time (PID controller is Proportional-Integral´-Derivative controller). Measured inputs to the PID controller are the flow rates of the fuel flow meter and water flow meter. The controlled output is the opening of a water control valve which will control the water added as the % set point (i.e water flow rate/ fuel flow rate).
A new fuel flow meter may required to be installed to provide the instantaneous flow rate with accuracy of +/-0.5% and with digital output signal of 4-20mA to the PID controller. If the existing flow meter can meet the specifications, then it can be used. The PID controller controls a continuously variable water control valve to control the amount of water (by volume) added to the fuel at the emulsifier unit. The actual amount of water added is measured by a water flow meter with accuracy of +/-1% and with digital output of 4-20mA. If there is not enough water, the PID controller will open the water valve a little more until the correct amount of water is added. If there is too much water, it will reverse the control action and close the water valve.
The “PID” function of the controller ensures stable control. In this way, the emulsified fuel system always ensures that the correct amount of water is accurately added to the fuel in a stable manner in real time, and in response to the actual fuel consumption of the engine.