Method and apparatus for injecting liquid fuel into a shaft furnace

Claim 2

In a method for injecting fuel into a shaft furnace, comprising introducing a jet of liquid fuel into a first chamber, atomizing the fuel by means of a jet of compressed gas wherein the gas mixes with the atomized fuel, causing the mixture to converge and then diverge, then subjecting the mixture to the action of a hot oxidizing gaseous fluid, and introducing the mixture of fuel gas and oxidizing fluid into the shaft furnace: the improvement comprising the steps of passing mixture of fuel and compressed gas from said first chamber immediately through at least one secondary chamber; introducing at least one further jet of compressed gas into said secondary chamber to augment the atomization of the fuel; and after causing the mixture to converge and then diverge, introducing the hot oxidizing gaseous fluid into the mixture in such a proportion that substantially all the fuel present in said mixture of fuel and compressed gas is burned before being introduced along with said oxidizing fluid into the furnace.

Claim 3

The method as claimed in claim 1, comprising the further step of preheating at least one of said jets of compressed gas before being introduced into a chamber.

Claim 4

The method as claimed in claim 2, in which said preheating is performed by said hot oxidizing gaseous fluid.

Claim 5

The method as claimed in claim 1, in which the jet of compressed gas introduced into the last chamber through which the fuel and compressed gas mixture passes is substantially richer in oxygen than the jet of compressed gas in the prior chamber.

Claim 6

In an injector for the injection of liquid fuel into a shaft furnace, comprising a first chamber, a fuel line for supplying liquid fuel to said first chamber through at least one orifice, at least one inlet into said first chamber, a channel for injecting a compressed gas into said first chamber through said inlet, a convergent/divergent means through which the liquid fuel and compressed gas pass, and a channel for supplying a hot oxidizing gaseous fluid to the furnace, the convergent/divergent means sealingly opening out into the interior of said channel for hot oxidizing gaseous fluid: the improvement being at least one secondary chamber having an orifice, the secondary chamber communicating with said first chamber through the orifice; at least one injection inlet through which said channel for the compressed gas opens into said secondary chamber; said inlet in said first chamber being orientated such that the compressed gas injected therein mixes with and atomizes the fuel supplied into said first chamber; said inlet in said secondary chamber being orientated such that the compressed gas meets the fuel and compressed gas mixture issuing from said first chamber and augments the atomization of the fuel; said convergent/divergent means being positioned adjacent said secondary chamber so that the fuel and compressed gas mixture can only leave said secondary chamber by passing through the said means.

Claim 7

In an injector for the injection of liquid fuel into a shaft furnace, comprising a first chamber, a fuel line for supplying liquid fuel to said first chamber through at least one orifice, at least one inlet into said first chamber, a channel for injecting a compressed gas into said first chamber through said inlet, a convergent/divergent means through which the liquid fuel and compressed gas pass, and a channel for supplying a hot oxidizing gaseous fluid to the furnace, the convergent/divergent means sealingly opening out into the interior of said channel for hot oxidizing gaseous fluid: the improvement being at least one secondary chamber having an orifice, the secondary chamber communicating with said first chamber through the orifice; at least one injection inlet through which said channel for the compressed gas opens into said secondary chamber; said inlet in said first chamber being orientated such that the compressed gas injected therein mixes with and atomizes the fuel supplied into said first chamber; said inlet in said secondary chamber being orientated such that the compressed gas meets the fuel and compressed gas mixture issuing from said first chamber and augments the atomization of the fuel; said convergent/divergent means being positioned adjacent said secondary chamber so that the fuel and compressed gas mixture can only leave said secondary chamber by passing through the said means.

Claim 8

The injector as claimed in claim 5, further comprising a frustoconical nozzle arranged convergently at the outlet of said convergent/divergent means so as to leave a space between said means and the nozzle, said nozzle being displaceable substantially along the axis of the injector.

Claim 9

The injector as claimed in claim 5, further comprising means for supplying a gas rich in oxygen to the secondary chamber immediately before said convergent/divergent means.

Claim 10

The injector as claimed in claim 5, wherein said fuel line is arranged in the interior of said compressed gas channel, which channel is arranged in the interior of said channel for the hot oxidizing gaseous fluid.

Claim 11

In an injector for the injection of liquid fuel into a shaft furnace, comprising a first chamber, a fuel line for supplying liquid fuel to said first chamber through at least one orifice, at least one inlet into said first chamber, a channel for injecting a compressed gas into said first chamber through the said at least one inlet, a convergent/divergent means through which the liquid fuel and compressed gas pass, and a channel for supplying a hot oxidizing gaseous fluid to the furnace, the convergent/divergent means sealingly opening out into the interior of said channel for hot oxidizing gaseous fluid: the improvement being a series of secondary chambers comprising at least a first secondary chamber and a last secondary chamber, said first secondary chamber communicating with said first chamber through an orifice; further injection inlets through which said compressed gas channel opens into said secondary chambers, said injection inlet into said first chamber being orientated such that the compressed gas injected therein mixes and atomizes the fuel supplied into said first chamber; said further injection inlets being orientated such that the compressed gas injected into each secondary chamber meets the fuel and compressed gas mixture issuing from the previous secondary chamber in the series, whereby the atomization of the fuel is augmented; said convergent/divergent means being arranged adjacent to the last secondary chamber in the series such that the fuel and compressed gas mixture can only leave said last secondary chamber by passing through said means.

Claim 12

In an injector for the injection of liquid fuel into a shaft furnace, comprising a first chamber, a fuel line for supplying liquid fuel to said first chamber through at least one orifice, at least one inlet into said first chamber, a channel for injecting a compressed gas into said first chamber through the said at least one inlet, a convergent/divergent means through which the liquid fuel and compressed gas pass, and a channel for supplying a hot oxidizing gaseous fluid to the furnace, the convergent/divergent means sealingly opening out into the interior of said channel for hot oxidizing gaseous fluid: the improvement being a series of secondary chambers comprising at least a first secondary chamber and a last secondary chamber, said first secondary chamber communicating with said first chamber through an orifice; further injection inlets through which said compressed gas channel opens into said secondary chambers, said injection inlet into said first chamber being orientated such that the compressed gas injected therein mixes and atomizes the fuel supplied into said first chamber; said further injection inlets being orientated such that the compressed gas injected into each secondary chamber meets the fuel and compressed gas mixture issuing from the previous secondary chamber in the series, whereby the atomization of the fuel is augmented; said convergent/divergent means being arranged adjacent to the last secondary chamber in the series such that the fuel and compressed gas mixture can only leave said last secondary chamber by passing through said means.

Claim 13

The injector as claimed in claim 9, further comprising a frustoconical nozzle arranged convergently at the outlet of said convergent/divergent means so as to leave a space between said means and the nozzle, said nozzle being displaceable substantially along the axis of the injector.

Claim 14

The injector as claimed in claim 9, further comprising means for supplying a gas rich in oxygen to said last secondary chamber.

Claim 15

The injector as claimed in claim 9, wherein said fuel line is arranged in the interior of said compressed gas channel which is arranged in the interior of said channel for the hot oxidizing gaseous fluid.

Claim 16

The method as claimed in claim 1 comprising the further step of expanding said liquid fuel as it enters said first chamber by reducing the pressure on the liquid fuel.

Claim 17

The mEthod as claimed in claim 5 wherein said inlets in the first and secondary chambers for compressed gas are tangential to the chamber.