A method of forming high strength glass fibers in a refractory-lined glass melter, products made there from and batch compositions suited for use in the method are disclosed. The glass composition for use in the method of the present invention is up to about 64-75 weight percent SiO.sub.2, 16-24 weight percent Al.sub.2O.sub.3, 8-12 weight percent MgO and 0.25-3 weight percent R.sub.2O, where R.sub.2O equals the sum of Li.sub.2O and Na.sub.2O, has a fiberizing temperature less than about 2650 F., and a T of at least 80 F. By using oxide-based refractory-lined furnaces the cost of production of glass fibers is substantially reduced in comparison with the cost of fibers produced using a platinum-lined melting furnace. High strength composite articles including the high strength glass fibers are also disclosed.

A system for preheating batch materials in a glass melting furnace includes: a preheater configured to receive unheated batch materials and to deliver heated batch materials, the preheater including an outlet configured to exhaust fluid from the preheater and an inlet configured to receive exhaust fluid from the glass melting furnace and exhaust fluid recirculated from the outlet of the preheater; a fan configured to provide ambient air to a furnace flue; a valve configured to control an amount of the ambient air to the furnace flue; a temperature sensor configured to sense temperature of exhaust gases in the furnace flue; and a temperature controller configured to control the valve and the fan responsive to the temperature sensed by the temperature sensor.

In a melting step (S1) of generating a molten glass (Gm) by heating and melting glass raw materials (Gr) corresponding to raw materials for a glass article in a melting furnace (10), the glass raw materials (Gr) are heated and molten through combustion of fuel (FH) containing hydrogen, and a water vapor partial pressure (Pp) in the melting furnace (10) is set to 80% or less of a total atmospheric pressure (Pt).

The melting method, wherein the unmelted charges form a pile 30 having a free surface 40 that is inclined relative to the vertical in the furnace 10; the unmelted charges are heated by means of flames 51, 52, 53 at a regulated power and momentum and are directed towards the free surface 40 in at least two directions 1, 2, 3 forming various acute angles 1, 2, 3 with the horizontal plane so that the flames 51, 52, 53 define impact zones 41, 42, 43 on the free surface 40 that are located over at least two different vertical levels h1, h2, h3.

The melting method, wherein the unmelted charges form a pile 30 having a free surface 40 that is inclined relative to the vertical in the furnace 10; the unmelted charges are heated by means of flames 51, 52, 53 at a regulated power and momentum and are directed towards the free surface 40 in at least two directions 1, 2, 3 forming various acute angles 1, 2, 3 with the horizontal plane so that the flames 51, 52, 53 define impact zones 41, 42, 43 on the free surface 40 that are located over at least two different vertical levels h1, h2, h3.

The invention relates to a melting method, in which method unmelted charges form a bank 30 resting on one side against the upstream wall 11 of the furnace 10 and having, on the opposite side, a free surface 40; the unmelted charges are heated by means of at least three flames 51, 52, 53 at a regulated power and momentum and are directed towards the free surface 40 so as to define impact zones 41, 42, 43 on this free surface 40 over at least three different distances I1, I2, I3 of one of the side walls 13, 13 of the furnace 10.