FR2459290A1 - METHOD FOR CONDUCTING A TANK OVEN - Google Patents

Abstract

THE INVENTION CONCERNS IN PARTICULAR THE HAUT FOURNEAU, IN WHICH WIND IS BLOWN AT HIGH TEMPERATURE WITHOUT INJECTION OF HYDROCARBONS. THE PROCESS IS CHARACTERIZED IN THAT THE OXYGEN CONTENT OF THE WIND IS REDUCED BY ADDING TO IT A GASEOUS FLUID HAVING AN OXYGEN CONTENT LOWER THAN THAT OF THE SAID WIND, FOR EXAMPLE OF COMBUSTION FUMES AT THE LEVEL OF THE AIR EXTRACTED BY THE WIND. .

Description

 The present invention relates to the operation of tank furnaces, and more particularly, but not exclusively, blast furnaces for producing cast iron.

 For several years, the blast furnace has been injecting ever larger quantities of hydrocarbons, such as fuel oil or natural gas, with a view to reducing the consumption of coke. These injections, however, have a cooling character and high wind temperatures have been used to maintain a sufficient flame temperature.

 In the present circumstances, the price of hydrocarbons continues to increase and it is not excluded that difficulties of supply arise.

 Any reduction in the quantities of hydrocarbons injected into the blast furnace, while maintaining a high wind temperature, would however lead to excessive flaming temperatures and a significant heat deficit at the top.

 From a thermal point of view, it would be possible to replace these hydrocarbon injections with other cooling injections, for example water vapor, in order to maintain high wind temperatures. The latter, however, is very expensive and its production requires the consumption of large amounts of energy. In addition, such an injection leads to an increase in the coking of 25 to 30 kg per tonne of melt.

 The industry therefore needs a process for blast furnace operation which, while maintaining the high wind temperatures currently practiced, minimizes the overall energy consumption of the process.

In the course of his research to develop a process to meet this need, the Applicant has now discovered that it is possible to maintain such high wind temperatures, even in the absence of hydrocarbon injections, by reducing content
Oxygen of the wind.

 The process which is the subject of the present invention is therefore essentially characterized in that the oxygen content of the wind blown into the blast furnace is reduced by adding to said wind a gaseous fluid having an oxygen content that is lower than that of said wind. .

 According to a preferred embodiment of the process of the invention, said gaseous fluid is introduced, without pressure, into the air aspird by the blower.

 A particularly advantageous mode of implementation of the method of the invention is to introduce into the wind nitrogen-rich combustion fumes, for example from cowpers.

 Another interesting mode of implementation of this method is to introduce into the wind of nitrogen from eg an oxygen production plant.

As an example of the implementation of the method of the invention, the table below illustrates the results obtained respectively with injection of fuel, without injection, or with addition of nitrogen or cowpowder smoke. The temperature at the top is kept constant at 1250C.

<tb><SEP> Inj. <SEP> t <SEP> Inj. <SEP> Inj.
<tb><SEP> fuel <SEP> wind <SEP> N2 <SEP> smokes <SEP>
<tb>% o <SEP> coke <SEP> kg / tf <SEP> 404 <SEP> 507 <SEP> 464 <SEP> 488
<tb> Temperature <SEP> wind <SEP> C <SEP> 1250 <SEP> 934 <SEP> 1250 <SEP> 1250
<tb> Injections
<tb><SEP> fuel <SEP> quantity <SEP> kg / tf <SEP> 60 <SEP> - <SEP> - <SEP> -
<tb><SEP> N2 <SEP> quantity <SEP> m3N / tf <SEP> - <SEP> - <SEP> 195 <SEP> -
<tb><SEP> temperature <SEP> OC <SEP> - <SEP> - <SEP> 1250 <SEP> -
<tb><SEP> Smokes <SEP> quantity <SEP> m3N / tf <SEP> - <SEP> - <SEP> - <SEP> 135
<tb><SEP> cowpers <SEP> temperature <SEP> C <SEP> - <SEP> - <SEP> - <SEP> 1250
<tb> Temperature <SEP> blast <SEP> CC <SEP> 125 <SEP> 125 <SEP> 125 <SEP> 125
<Tb>

 This example clearly shows the advantage of the invention, as regards the coke mulling, when eliminating any injection of hydrocarbons into the blast furnace.

Claims (4)

 1. A method of driving a shaft furnace, in particular a blast furnace, wherein said wind blows high temperature wind without injection of hydrocarbons, characterized oxygen content of said wind by adding a gaseous fluid having a lower oxygen content than said wind.  2. The process of claim 1, wherein said gaseous fluid is substantially nitrogen.  3. The process according to claim 1, wherein said gaseous fluid is combustion fumes.  4. A process according to any one of claims 1 to 3, wherein said gaseous fluid is added to the air sucked by the blower.