WO2011061261A2 - Method and device for reducing the metallurgical power demand of closed electric smelting and/or reduction furnaces - Google Patents

Abstract

In order to utilize the CO-rich process gas that develops in the closed electric smelting and/or reduction furnace (1) for the generation of iron alloys, metals, and silicon, for recycling processes, and chemical processes, said gas is burned in a gas engine (3) for driving a generator (4) for generating electric energy. In order to further increase the efficiency of such systems comprising gas engines, according to the invention the hot combustion gases of the gas engine (3) are utilized to deliberately raise the inlet temperature of the charge material to be added to the smelting and/or reduction furnace (1).

Description

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

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 CO2. 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 EP 0139 310 B1 a process for the production of liquid, carbonaceous iron from sponge iron is known, wherein sponge iron in reduced rotary kiln, the reduced material charged after a treatment in the electric reduction furnace, the carbonaceous iron produced is carburized and finally blown in a converter to steel. 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 occasionally through heat exchangers, in order 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 the steel and coke production, have the disadvantage that at least 3 units (heat exchangers, steam turbine and generator) are required at relatively low power and in particular by the concatenation of these units not one 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 by increasing the inlet temperature of the feed material in 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 is carried out in a traversed by the combustion gases rotary kiln 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 aggregate to the melting and / or reduction furnace is important in this case, since otherwise during a wide transport weges the heated feed material undesirably cools again and incur unnecessary transport and insulation costs.

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 the 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 basis of the process chain of the electric reduction furnace 1 is a Submerged arc furnace (SAF), which is filled in a chamber by means of conveying with the taken from an intermediate storage 6 feed material. The resulting in this reduction furnace 1 process gases are supplied via a process gas line 21 (not shown) cooling and gas cleaning 2 and then pass through a further process gas line 22 to a gas engine 3, in which the cooled and purified process gases for driving a generator 4 for generating be burned by e- lectric energy 25. According to the invention, in the feed line between the intermediate storage and the reduction furnace 1, a rotary tube 5 inclined towards the reduction furnace 1 is arranged for heating the charge material. The initially still cold feed material taken from the intermediate storage 6 is introduced via the conveying means 11 into the upper end (in the figure on the right) of the tilted rotary tube 5 and transported there in the conveying direction 12 to the lower discharge end (on the left in the drawing figure).

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

The hot feed material leaving the rotary tube 5 at the discharge end becomes as insulated as possible with a heat-resistant conveying means 13 Intermediate storage 7 and from there charged with a further heat-resistant conveyor 14 into the reduction furnace 1.

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

1 1 conveyor for the cold feed material to the rotary tube

 12 transport direction of the feed material in the rotary tube

 13 conveyor 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

Claims

claims 1 . 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 or reduction furnace (1) is burned after cooling and subsequent gas cleaning in a gas engine (3) for driving a generator (4) for generating electrical energy, characterized in that to reduce the required energy demand for in the electric melting and / or reduction furnace (1) ongoing metallurgical / chemical process, the hot combustion gases of the gas engine (3) are used to selectively increase the inlet temperature of the feed material to be introduced into the melting and / or reduction furnace (1). 2. The 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 performed. 3. The method according to claim 2, characterized in that the heating of the feed material is carried out in a through-flow of the combustion gases rotary tube (5) or similar aggregate. 4. The 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 become. 5. The 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 occurred, but containing dust particles of the feed combustion gases after flowing through the rotary tube (1) or the comparable unit in a simple manner For example, by a bag filter, dedusted. 6. The 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. 7. A device for reducing the metallurgical energy demand of a closed electric melting and / or reduction furnace (1) 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 (1) is burned after cooling and subsequent gas cleaning in a gas engine (3) for driving a generator (4) for generating electrical energy, in particular for carrying out the method of the preceding claims 1 to 6, characterized by an above the melting and / or reduction furnace (1) or adjacent thereto in the feed line arranged rotary tube (5) or comparable unit for the targeted heating of the feed into the melting and / or reduction furnace (1) feed material with about 500 ° C hot Combustion gases of the gas engine (3), including the rotary tube (5) or the comparable unit via an insulated gas line (23) with the gas engine (3) and via conveying means (13, 14) with the melting and / or reduction furnace (1 ) connected is. 8. The device according to claim 7, characterized in that the interior of the rotary tube (5) or comparable unit with means for promoting the Charging material, for example, formed with lifting blades. 9. Apparatus according to claim 7 or 8, characterized in that the rotary tube (5) or the comparable unit is designed for heating the Beschi ckungsmaterials on the countercurrent principle.