EP1020696B1 - Process and device to inject solid particles in a shaft furnace - Google Patents

Abstract

Solid particle injection into a shaft furnace uses high pressure gas introduction to increase carrier gas flow velocity and cause particle spiral motion towards a lance outlet. Solid particles are injected into a shaft furnace by entrainment in a carrier gas stream through an injection lance into the hot blast in a tuyere, a higher pressure gaseous medium being introduced into the carrier gas stream, immediately prior to entry into the lance, to increase the flow velocity and cause spiral motion of the particles towards the lance outlet. An Independent claim is also included for equipment for carrying out the above process.

Description

The invention relates to a method and a device for blowing in solid particles in a shaft furnace, in particular a blast furnace, in which the solid particles by means of a gaseous flow into the hot wind stream the wind forms are fed.

It is for operating blast furnaces or other comparable shaft furnaces known, additional fuels via the wind forms the metallurgical process supply. In addition to liquid additional fuels, such as. B. heating oil, too solid energy carriers via suitable pneumatic transport devices Furnace fed. These mostly powdered fuels are thereby Actuation of a carrier gas via pipelines from a storage container via discharge chambers and appropriately trained blowing lances added to the hot wind stream and transported into the furnace interior.

A method for supplying a powdered fuel mixture is for Example described in the publication according to DE 30 50 394. After this The powdered fuel mixture is processed immediately after Discharge from a discharge chamber in each pipe with a gas jet acted on, which is directed against the flow. So that should Eligibility of the fuel particles stored in the conveying gas is ensured become.

US-A-5 070 797 describes the additional injection of compressed air into a flow of solid fuel particles before entering a hot air stream a hot wind lead to a shaft furnace.

In addition to the use of powdered additional fuels in the form of coal or Coke dust is known, plastic granules or waste products from the recycling of used cars, such as B. the shredder light fraction after the corresponding Processing used as additional fuel in a blast furnace. These substances however, they tend to clog more than normal powdered fuels in the pipes and cause malfunctions in the supply of the individual blowing lances with additional fuel. This condition is confirmed by a Countered increasing flow rate of the flow. Despite these measures, there are no disruptions in the operation of such systems to avoid. By increasing the flow rate of the Flow occurs in the pipes, increased wear, which leads to increased maintenance costs for the system. Continue to lead blockages occurring in the pneumatic transport system are increased Failures on the blowing lances because the blowing lances are cooled by the Flow is then no longer given. It also has an unstable Supplying the individual wind forms with additional fuel affects a continuous flow of the metallurgical processes in the blast furnace.

The object of the invention is to find a method and a device with which additional fuels in the form of solid particles, such as. B. granules from the Processing of old plastics, dusts or other powdery substances and their Mixtures by means of a gaseous flow into the hot wind stream Wind forms of a shaft furnace, in particular a blast furnace, are promoted, that while lowering the usual pressure on the Conveyor system after a discharge chamber of a pneumatic transport device Faults in the supply of the stove with these additional fuels avoided the maintenance and repair work for such Plants reduced and more favorable conditions for a combustion of the solid Particles in the melting zone of the furnace can be guaranteed.

According to the invention the object is achieved according to claims 1 to 6.

According to FR-A-2 681 417, Fig. 8, 9, is in a hot wind pipe leading to a shaft furnace a central pipe for a flow of solid auxiliary fuel and gas is arranged. Before the hot wind pipe opens into the furnace and at an angle to it, oxygen supply lines are arranged, which swirl the additional fuel in a spiral. The swirling takes place in Contrary to the invention only in the wind pipe and not before the flow in the wind pipe.

EP-A-44 096 describes the supply of solid fuel particles and their swirling in one Hot wind form of a blast furnace by means of branch lines that open at an angle in the wind form connected by a pipe bend. In contrast to the invention, the supply line does not take place before but in the wind form.

The application of a gaseous medium to the feed stream according to the invention immediately before the solid particles enter a blow-in lance enables the solid particles to be loosened and swirled before entering the hot wind stream of a wind form while increasing the flow rate of the feed stream. The additional introduction of a gaseous medium in the direction of the injection lance with a pressure which is several times higher than that of the conveying medium in this pipe section creates a suction effect in the upstream part of the respective pipe, which considerably reduces the risk of blockages in this previously endangered pipe section , The spiral introduction of the gaseous medium into the flow immediately before entering the blowing lance enables the flow to be formed in a stable manner, as a result of which the solid particles can be transported far into the melting zone of the furnace.
By supplying the flow with an additional gaseous medium in front of an injection lance, it is ensured that if there is a blockage in the pipeline leading to each injection lance, it is no longer possible to burn the lances, since the cooling of the injection lance is ensured with the additional gaseous medium.

Fig. 1 :

Seitenansicht der Vorrichtung

Fig. 2 :

Draufsicht der Vorrichtung

Fig. 3 :

Verbindung Rohrbogen mit Rohrabschnitt

Fig. 4 :

Vorrichtung im eingebauten Zustand

The method according to the invention and the associated device are to be explained in more detail below using an exemplary embodiment. Show in the accompanying drawings

Fig. 1:

Side view of the device

Fig. 2:

Top view of the device

Fig. 3:

Connection pipe bend with pipe section

Fig. 4:

Device when installed

The embodiment relates to the injection of solid particles, such as. B. plastic granules or processed components from the shredder light fraction, which are fed to the blast furnace process via the wind molds 5 as part of an environmentally sound recycling. The solid particles are conveyed under pressure from a storage container via pipes to the area of the windmills 5 of the blast furnace.
The usual pressure at the beginning of the conveyor line of 2.2-2.5 bar can be reduced to 1.6-2.0 bar using the method according to the invention and the associated device. Depending on the conveyor line, which can vary depending on the size of the furnace and the number of storage containers, a pressure of 0.2 - 0.5 bar is set at the end of the conveyor line. The solid particles are added to the hot wind stream via blowing lances 6 arranged on the wind molds and are thus fed to the interior of the furnace. For this purpose, the respective pipeline is connected via a valve 4 to the device according to the invention directly in front of a blowing lance 6. The device is arranged between the blowing lance 6 and the valve 4 and is expediently connected to these by means of screw connections on both sides.
It consists of a pipe section 1 and a pipe bend 2 firmly connected to the pipe section 1, which is arranged at an angle of approximately 30 ° to the axis of symmetry of the pipe section 1. On the circumference of the pipe section 1, two openings are arranged offset to one another in the vertical plane to the axis of symmetry of the pipe section 1, the size of which corresponds to the inside diameter of the pipe bend 2. The pipe section 1 and the two ends of the pipe bend 2 are connected to one another in a gas-tight manner in the region of the openings, preferably by a welded connection as shown in FIG. 3. The pipe bend 2 has a connection 3 for a compressed air line. The connection 3 is arranged at the upper vertex of the pipe bend 2, the connection being designed so that compressed air can flow into the pipe section 1 via the connection 3 and the pipe bend 2. The compressed air is taken from the line network installed at the blast furnace at approximately 5 to 6 bar and fed to the device according to the invention via a non-illustrated check valve. The existing pressure difference creates a suction effect in the pipeline for the solid particles, as a result of which deposits or blockages in the rear section of the pipeline are avoided. The staggered arrangement of the pipe bend ends on the pipe section 1 can be seen from FIG. 1. It loosens and swirls the solid particles in the area behind the pipe openings in the pipe section 1. The arrangement of the pipe bend ends at an angle of 80 ° to the axis of symmetry of the pipe section 1 produces a spiral movement of the solid particles directed in the direction of the lance 6. This configuration is shown in Fig. 2. The inner diameter of the pipe section 1 is equal to the inner diameter of the downstream blowing lance 6 in order to avoid negative effects on the flow.

List of the reference numerals used

1

pipe section

2

Elbows

3

Connection

4

Valve

5

Windform

6

injection lance

Claims (6)

1. A process to inject solid particles into a shaft furnace, in particular a blast furnace, wherein solid particles are conveyed into hot blast flow within a blast tyuere (5) by a carrier gas flow through an injection lance (6), the carrier gas flow directly before its entry into the injection lance being impinged on with a gaseous medium which at this point is at a pressure in excess of that existing in the carrier gas flow, characterised in that the gaseous medium is introduced into the carrier gas flow in a manner such that due to increase in the flow velocity the solid particles contained in the carrier gas flow are fluidised and set into a spirallike motion directed towards the injection lance discharge end.
2. A device to carry out the process of claim 1 comprising an injection lance (6) opening into a blast tyuere (5) and intended to conduct a flow of carrier gas containing solid particles and a pipe section (1) upstream of the injection lance (6) having at least two opposite mutually offset pipe junctions for receiving gas, characterised in that said pipe junctions are in communication with each other via an arcuate pipe (2) provided with a connection piece (3) for a gaseous medium.
3. The device of claim 2, characterised in that the arcuate pipe (2) is mounted at an angle of 20° to 40° with respect to the axis of symmetry of the pipe section (1).
4. The device according to claims 2 and 3, characterised in that the pipe junctions of the pipe section (1) are offset equidistantly with respect to the axis of symmetry of the pipe section (1).
5. The device according to claims 2 to 4, characterised in that the pipe junctions are mounted at an angle less than 90°, preferably from 80° to 70°, with respect to the axis of symmetry of the pipe section (1).
6. The device according to claims 2 to 5, characterised in that the inner diameter of the pipe section (1) is equal to that of the injection lance (6).

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