Oxidant-swirled fossil fuel injector for a shaft furnace

a shaft furnace and injector technology, applied in furnaces, combustion types, manufacturing converters, etc., can solve the problems of carbon soot formation, limiting pulverized coal utilization, and irregular charge reduction and charge reduction

Inactive Publication Date: 2007-09-06
AIR PROD & CHEM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0021] The injector may include a converging annular passage for receiving the oxidant from the plurality of spiral-like passages to expand and merge discrete oxidant jets into a rotating vortex for suppressing flame attachment at the tip of the injector. The converging annular passage may extend through a portion or the entire converging nozzle.

Problems solved by technology

Economics favor increased use of pulverized coal thereby reducing the use of coke, but technical problems limit pulverized coal utilization.
Insufficient and / or uneven permeability leads to nonuniform gas flows across the cross section of the furnace, resulting in nonuniform reduction of the charge and irregular decent of the charge.
As pulverized coal injection is increased, inadequate mixing between the injected coal and the blast air results in incomplete combustion of the injected coal, resulting in carbon soot formation.
This problem also exists for other fossil fuels, such as heavy oil.
Soot plugs the pores in the coke, inhibiting the gas flow characteristics, and thereby limits the amount of coal that can be injected to replace coke.
Injection of fossil fuel without industrial oxygen may decrease the temperature in the raceway due to endothermic cracking of the fossil fuel and the thermal capacity of the relatively cold fossil fuel.
Pulverized coal is abrasive and may erode nozzle tips.

Method used

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  • Oxidant-swirled fossil fuel injector for a shaft furnace
  • Oxidant-swirled fossil fuel injector for a shaft furnace
  • Oxidant-swirled fossil fuel injector for a shaft furnace

Examples

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example 1

[0042] An injector according to the present invention was constructed and tested. The injector comprised an inner conduit having a generally circular cross-section for conveying fossil fuel and an outer conduit, also having a generally circular cross-section, surrounding the inner conduit, which formed an annulus for conveying and swirling oxidant. The inner diameter of the inner conduit was about 8.687 mm. The outer diameter of the outer conduit was about 48.26 mm and the inner diameter of the outer conduit was about 29.49 mm. The inner surface of the outer conduit terminated in a converging inner surface having an angle of about 15° relative to the longitudinal axis.

[0043] The means for swirling the oxidant comprised six evenly-spaced spiral-like passages (grooves) machined into the outer surface of the inner conduit and had a rotation of about 180°. The spiral-like passages were generally rectangular, having width and height dimensions of about 2.5 mm by 2.5 mm. The swirl angle ...

example 2

[0050] A second injector according to the present invention was constructed and tested. This second injector was similar to the injector described in Example 1 with the exception that the cross-section of the spiral-like passages, which had a width of about 2.5 mm and a height of about 1.25 mm. The cross-sectional area of the spiral-like passages was therefore halved, resulting in a higher flow velocity for the same flow rate compared to the injector in Example 1.

[0051] Table 2 summarizes process conditions and LOI results for the injector having higher oxidant swirl velocity. The LOI data shows that the samples corresponding to operating conditions with swirl oxidant have a lower percentage loss on ignition, indicating less carbon soot produced for the injector according to the present invention. Exhaust O2 concentrations were not measured for Samples 6-1 and 6-2.

TABLE 2Swirl O2 flowCoal flow raterateExhaust O2LOISample #(kg / h)(Nm3 / h)(vol %)(%)6-125059—36.096-22200—49.29

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Abstract

An injector for injecting a swirling oxidant around a fossil fuel into a shaft furnace has a converging nozzle to improve combustion of the fossil fuel and reduce carbon soot formation. Fossil fuels, for example pulverized coal, may be introduced into the blast passageway and/or raceway cavity of a shaft furnace such as a blast furnace or cupola, to reduce the amount of coke needed for operation. Oxidant, which may be industrial grade oxygen, is swirled around the fossil fuel through a converging nozzle to improve the combustion of the fossil fuel thereby permitting increased substitution of fossil fuel for coke.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates generally to fossil fuel injection into a shaft furnace. More specifically, the present invention relates to a fossil fuel injector where oxidant, which may be industrial grade oxygen, is swirled around the fossil fuel, which may be pulverized coal, to improve the combustion of the fossil fuel thereby permitting increased substitution of fossil fuel for coke. [0002] Generally, in the production of molten iron in a shaft furnace, for example a blast furnace or a cupola, iron ore and / or iron scrap as a raw material and coke as a fuel are fed through the top of the furnace, while (hot) blast air is fed through a tuyere, which is positioned in a lower part of the furnace. The coke provides three main functions: fuel, reductant, and gas flow passage. Coke serves as fuel, reacting with blast air to provide a large part of the heat energy needed for the process. Coke serves as a reductant, both as a carbon constituent in carb...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C21B7/16
CPCC21B5/001C21B5/003C21B7/163F23D1/02Y02E20/344F23D14/32F23L2900/07007F27B1/16F23D14/24Y02E20/34Y02P10/32
Inventor LANYI, MICHAEL DENNISFARMER, LARRY KEITHDUDILL, ROGER
Owner AIR PROD & CHEM INC
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