Pressure swirl flow injector with reduced flow variability and return flow

An injector for injecting reagent, the injector comprising:

• an upper injector body;
• a lower injector body coupled with the upper injector body;
• a cylindrical pole piece disposed within at least one of the upper injector body and the lower injector body, the cylindrical pole piece defining a pole piece first end, a pole piece second end and a hollow interior extending from the pole piece first end to the pole piece second end;
• a spring located within at least a portion of the hollow interior;
• an electromagnetic coil secured around a bobbin, the electromagnetic coil surrounding an outside diameter of the cylindrical pole piece, wherein the cylindrical pole piece, spring and electromagnetic coil reside within at least one of the upper injector body and the lower injector body;
• a cylindrical inner lower body having an inner lower body first end and an opposing inner lower body second end and a longitudinal central bore extending therebetween, the inner lower body first end having a first end bore with a diameter larger than a diameter of the longitudinal central bore;
• a solid pintle residing within the longitudinal central bore;
• a pintle head surrounding an end of the pintle, the pintle head residing within the first end bore and contacting the spring such that the spring biases the pintle into a closed position;
• an orifice plate coupled to the inner lower body second end;
• and
• the orifice plate and the inner lower body second end define a chamber therebetween,
• wherein the inner lower body defines a return passage that fluidly links the inner lower body central bore and the chamber.