Apparatus and method for entraining fluids

An apparatus for entraining a second fluid in a first fluid, the apparatus comprising:

• a fluid processing passage having an inlet connectable to a source of the first fluid, and an outlet;
• a nozzle circumscribing the processing passage and opening into the processing passage intermediate the inlet and the outlet;
• and
• a first port opening into the processing passage downstream of the nozzle;
• wherein the apparatus further comprises an entrainment fluid supply chamber in fluid communication with the nozzle, and a second fluid supply chamber in fluid communication with the first port;
• and wherein the chambers are separated from one another by a wall member which at least partially defines both the entrainment fluid supply chamber and the second fluid supply chamber,
• wherein the entrainment and second fluid supply chambers are annular and located radially outward of the processing passage, and wherein the entrainment fluid supply chamber is located radially outward of the second fluid supply chamber.