DE102009053920A1 - Method and device for reducing the metallurgical energy requirement of closed electric melting and / or reduction furnaces - Google Patents

Abstract

In order to use the CO-rich process gas that occurs in the closed electric melting and / or reduction furnace (1) for the production of iron alloys, metals, silicon, for recycling processes and chemical processes, it is used in a gas engine (3) to drive a Burned generator (4) to generate electrical energy. In order to further increase the efficiency of such systems with gas engines, it is proposed according to the invention that the hot combustion gases from the gas engine (3) be used to increase the inlet temperature of the feed material to be introduced into the melting and / or reduction furnace (1).

Description

The invention relates to a method and a device for reducing the metallurgical energy requirement of a closed electric melting and / or reduction furnace for the production of iron alloys, metals, silicon, for recycling processes and chemical processes, wherein the resulting CO-rich process gas of the melting and / or reduction furnace is burned after cooling and subsequent gas cleaning in a gas engine to drive a generator for generating electrical energy.

Electric smelting furnaces are used for the production of alloys, silicon, for recycling processes and chemical processes. If oxidic constituents are reduced, a CO-rich gas is produced. In so-called open furnaces, this strongly CO-containing gas burns directly on the surface of the furnace filled with feed material (Möller) to CO ₂ . The hot exhaust gases are partially collected, cleaned and the thermal energy used in some cases for hot water or steam generation.

For closed furnaces, the electric melting and reduction furnace is equipped with a gas-tight lid. The process gas remains without fresh air supply in a so-called gas space above the feed material in the oven and is supplied via exhaust pipes for cooling and subsequent cleaning. The thus purified exhaust gas can be burned and used for steam generation. This steam is used in chemical companies as process steam, in other cases it is used to generate electricity by means of steam turbines.

From the EP 0139 310 B1 For example, a process for producing liquid carbonaceous iron from sponge iron is known wherein sponge iron is reduced in a rotary kiln, the reduced material is charged after conditioning in the electroreduction furnace, the carbonaceous iron produced is carburized and finally blown into steel in a converter. The process gases arising in the rotary kiln, in the electroreduction furnace and in the converter are each supplied to an electric power generation, consisting of an afterburning, steam generation and power generation. The generated electrical energy is supplied to the electroreduction furnace and used for oxygen generation for the converter.

Another use for the use of process gases from steel and coke production is the use of gas engines. These gas engines then drive without the detour via a previous steam generation by combustion of the process gases generators for generating electrical energy. In order to further increase the efficiency of such systems with gas engines, it is known to guide the exhaust gases of the gas engines sporadically through heat exchangers, in turn, to generate steam and thus electricity.

This described exhaust heat recovery of gas engines, which are used for the combustion of process gases from steel and coke production, have the disadvantage that at least 3 units (heat exchangers, steam turbine and generator) are required at comparatively low power and in particular by the concatenation of these units a convincing moderate electrothermal efficiency of about 35-40% of such recovery plants is achieved.

Based on the above-described disadvantages in the use of gas engines for the combustion of process gases, it is an object of the invention to further develop the exhaust heat recovery of gas engines so that an optimized use of gas engine technology for electric furnaces with high efficiency is obtained.

The object is achieved with the characterizing features of claim 1, characterized in that to reduce the energy required for the running in the electric melting and / or reduction furnace metallurgical / chemical process, the hot combustion gases of the gas engine to specifically increase the inlet temperature of the melt into the and / or reduction furnace to be entered feed material.

An apparatus for carrying out this method is specified by the characterizing features of claim 7.

In contrast to the usual method, the hot exhaust gases of gas engines are not used for the recovery of energy in the form of steam or electrical energy, but to reduce the energy required for the running in the electric melting and / or reduction furnace metallurgical or chemical process an increase in the inlet temperature of the feed material into the electric melting and / or reduction furnace. Since a significant proportion of the energy to be introduced into the electric melting and / or reduction furnace is required for heating and melting the charge material (Möllers), metallurgical energy can be directly saved in this way without energy conversion stages and thus the energy requirement of the furnace becomes clear to reduce.

According to the invention, the heating of the feed material to increase its Inlet temperature in the melting and / or reduction furnace in direct contact with the hot combustion gases of the gas engine performed in a traversed with the combustion gases rotary tube or similar aggregate. The rotary tube or similar unit is arranged above the melting and / or reduction furnace or adjacent to it in the feed line and connected for the supply of hot combustion gases via an insulated gas line to the gas engine. The local proximity of the rotary tube or comparable unit to the melting and / or reduction furnace is important here, since otherwise the heated feed material undesirably cools down again during a long transport path and unnecessary transportation and insulation costs are incurred.

The rotary tube or the comparable unit is designed so that in order to produce an intensive heat exchange between the about 500 ° C hot combustion gases of the gas engine and the feed material, the combustion gases are passed in countercurrent to the feed material through the rotary tube or by the comparable unit. To promote the feed material, the rotary tube or the comparable unit is arranged inclined in the conveying direction, or the interior of the rotary tube or the comparable unit is formed with appropriate means, such as lifting blades.

As a result of the heat exchange of the combustion gases with the feed material taking place in direct contact, the cooled combustion gases contain dust constituents of the feed material which can be removed in a simple manner, for example by means of a bag filter.

Since the gas engine cooling water also contains a small amount of usable heat energy, the gas engine cooling water can be supplied to a company for use of this heat energy.

The inventive process chain of electrical melting and / or reduction furnace, process gas purification, gas engine for power generation by means of generator and rotary tube or similar unit as a heat exchanger for targeted preheating of the feedstock thus represents an optimized use of gas engine technology for electrical melting and / or reduction furnaces with high efficiency ,

In a schematic drawing figure, this process chain will be explained in more detail using an exemplary embodiment.

In the illustrated embodiment, the electric reduction furnace is the basis of the process chain 1 a Submerged Arc Furnace (SAF), the chamber by conveyor with the from an intermediate storage 6 is removed from charged feedstock. The in this reduction furnace 1 arising process gases are via a process gas line 21 a (not shown) cooling and gas cleaning 2 fed and then get over another process gas line 22 to a gas engine 3 in which the cooled and purified process gases are used to drive a generator 4 for generating electrical energy 25 to be burned.

According to the invention is in the feed line between the intermediate storage and the reduction furnace 1 a to the reduction furnace 1 tilted rotary tube 5 arranged for heating the feed material. That from the interim storage 6 initially taken cold feed material is on the funding 11 in the upper end (in the figure on the right) of the inclined rotary tube 5 introduced and there in the conveying direction 12 transported to the bottom discharge end (in the figure on the left).

The combustion of the process gases in the gas engine 3 resulting about 500 ° C hot combustion gases pass through a correspondingly insulated gas line 23 from the gas engine 3 to the rotary tube 5 and are initiated there at the end of the discharge. The combustion gases flow through the rotary tube according to the countercurrent principle 5 in the flow direction 24 opposite to the conveying direction 12 of the feed material. On her opposite way through the rotary tube 5 and the consequent residence time is in direct contact a heat transfer from the combustion gases to the feed material, the latter being heated and the combustion gases are cooled themselves and also absorb some dust of the feed material.

That the rotary tube 5 At the discharge end leaving hot feed material is provided with a heat resistant conveyor 13 to a possibly isolated intermediate storage 7 and from there with another heat-resistant conveyor 14 in the reduction furnace 1 charged.

LIST OF REFERENCE NUMBERS

1

Reduction furnace (Submerged arc furnace)

2

gas cleaning

3

gas engine

4

generator

5

rotary tube

6

Intermediate storage for cold feed material

7

Intermediate storage for heated feed material

11

Conveyor for the cold feed to the rotary tube

12

Transport direction of the feed material in the rotary tube

13

Conveying means for the heated feed material after the rotary tube

14

Conveying means for the heated feed material in the reduction furnace

21

Process gas line from reduction furnace to gas cleaning

22

Process gas line from the gas cleaning to the gas engine

23

Gas line for the hot combustion gases of the gas engine to the rotary tube

24

Flow direction of the hot combustion gases of the gas engine in the rotary tube

25

generated electrical energy

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0139310 B1 [0004]

Claims (9)

Method for reducing the metallurgical energy requirement of a closed electric melting and / or reduction furnace ( 1 ) for the production of iron alloys, metals, silicon, for recycling processes and chemical processes, whereby the resulting CO-rich process gas of the melting and / or reduction furnace ( 1 ) after cooling and subsequent gas cleaning in a gas engine ( 3 ) for driving a generator ( 4 ) is burned to generate electrical energy, characterized in that to reduce the energy required for the in the electric melting and / or reduction furnace ( 1 ) ongoing metallurgical / chemical process the hot combustion gases of the gas engine ( 3 ) for the targeted increase of the inlet temperature of the in the melting and / or reduction furnace ( 1 ) to be entered feed material. A method according to claim 1, characterized in that the heating of the feed material to increase its inlet temperature in the melting and / or reduction furnace ( 1 ) in direct contact with the hot combustion gases of the gas engine ( 3 ) is carried out. A method according to claim 2, characterized in that the heating of the feed material in a through-flow of the combustion gases rotary tube ( 5 ) or similar aggregate is performed. A method according to claim 3, characterized in that for the production of an intense heat exchange between the about 500 ° C hot combustion gases of the gas engine ( 3 ) and the feed material, the combustion gases in countercurrent to the feed material through the rotary tube ( 5 ) or through the comparable unit. A method according to claim 3 or 4, characterized in that in the rotary tube ( 5 ) or in the comparable unit cooled by the heat exchange, but dust fractions of the feed containing combustion gases after flowing through the rotary tube ( 1 ) or the comparable unit in a simple manner, for example by a bag filter, dedusted. Method according to one or more of claims 1 to 5, characterized in that the heat energy of the gas engine cooling water is supplied to an operational use. Device for reducing the metallurgical energy requirement of a closed electric melting and / or reduction furnace ( 1 ) for the production of iron alloys, metals, silicon, for recycling processes and chemical processes, whereby the resulting CO-rich process gas of the melting and / or reduction furnace ( 1 ) after cooling and subsequent gas cleaning in a gas engine ( 3 ) for driving a generator ( 4 ) is burned to generate electrical energy, in particular for carrying out the method of the preceding claims 1 to 6, characterized by a above the melting and / or reduction furnace ( 1 ) or adjacent to it in the feed line arranged rotary tube ( 5 ) or similar unit for the targeted heating of the in the melting and / or reduction furnace ( 1 ) to be entered feed material with about 500 ° C hot combustion gases of the gas engine ( 3 ), to which the rotary tube ( 5 ) or the comparable aggregate via an insulated gas line ( 23 ) with the gas engine ( 3 ) and subsidies ( 13 . 14 ) with the melting and / or reduction furnace ( 1 ) connected is. Apparatus according to claim 7, characterized in that the interior of the rotary tube ( 5 ) or comparable aggregate with means for conveying the feed material, for example with lifting blades is formed. Apparatus according to claim 7 or 8, characterized in that the rotary tube ( 5 ) or the comparable unit is designed for heating the feed material according to the countercurrent principle.

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