Systems for heating fluids

Claim 1

Gas-fired apparatus for the direct firing of an immersion tube for heating liquid in a vat or tank, including in combination, a burner of the nozzle-mixing type having a burner head comprising a gas supply tube closed at its inner end, the closed end of the gas tube being provided with equally spaced gas outlet ports inclined at an angle of between 40° and 50° to the tube axis, an air tube of greater diameter than the gas tube and disposed concentrically about it, and an annular perforate member of conical form substanting an angle of revolution of between 40° and 50° and fixed to said gas tube behind said gas outlet ports with its outer peripheral edge spaced slightly forwardly from the inner cylindrical surface of said air tube so as to project into said combustion chamber, disposed substantially across the annular space defined between the outlet ends of the gas and air tubes with its inner peripheral edge located behind the gas outlet ports, means for supplying air and gas separately to the burner head above atmospheric pressure, means for igniting a combustible gas/air mixture adjacent said burner head, a combustion chamber disposed downstream of the burner external to the vat or tank, the combustion chamber consisting of a hollow cylindrical cavity formed in a block of refractory material, the diameter of the cavity over the greater proportion of its length being greater than the diameter of the air tube and tapering inwardly towards its end which communicates with the immersion tube, and an immersion tube for immersion in a liquid to be heated, said immersion tube being of small bore and of predetermined length and communicating the combustion chamber and an outlet for exhaust gases.