DE29706367U1 - Injector for conveying free-flowing bulk goods, e.g. Coal dust, plastic granules or sand (metering feed injector) - Google Patents

Description

Description:

Injector for introducing free-flowing bulk materials with low or high specific weight into metallurgical melting or combustion units, where the continuously adjustable dosage of the discharge of the dusty or fine-grained products from pneumatically operated transport vessels enables process automation.

State of the art:

The use of pneumatic transport containers for transporting dusty or fine-grained products, which must be introduced into production units as energy sources, additives or alloying materials in other areas of industrial processes, is generally state of the art today. As automation and development of production processes continue to advance, it is necessary to be able to precisely dose the quantities of products to be blown in within narrow limits depending on physical and chemical properties, to be able to change the flow rates during the production process if necessary and to be able to control the course of the production process over time according to predetermined flow plans or using individually recorded, time-varying control variables.

This injector includes the required introduction of bulk materials with low and/or high specific bulk densities of 1.0 to 7.0 g/cm3 into metallurgical units, such as blast furnaces for pig iron production, cupola furnaces for the production of foundry pig iron or electric furnaces, as well as converters for steel production, as well as rotary kilns and combustion furnaces. The bulk materials can have a grain size of 0-20mm, but preferably between 0-4mm.

The bulk materials to be introduced into these metallurgical units include, in particular, processed mixtures of mill scale sludge, filter dust, ash from power plants, coal or coke, residues from shredding plants, plastic or fine dust from direct reduction, whereby the contents of the individual components in the mixture are not fixed but can vary greatly depending on the amount. Typical mixture compositions contain, for example, 40% filter dust, 40% mill scale sludge and 20% coal with a bulk density of approx. 2.6 g/cm3.

Blast furnace and cupola furnace:

For trouble-free operation of a blast furnace, it is necessary to be able to maintain a consistent flow of material over a long period of time. The mixtures are fed in via a lance that is introduced into the blast molds below the hot blast line. Depending on the operator's requirements, the number of lances can be between 3 and 15, usually 4 to 8. It is now crucial that the feed for each lance is regulated individually, since, for example, the counterpressure that prevails on the discharge side within the blast furnace is not constant, but changes spatially and temporally. On the other hand, the amount of mixture that can be blown in per unit of time depends on factors such as gassing of the furnace, energy requirements for melting the mixture or the influence on the melt composition. Depending on the requirements, blowing rates of 10 to max. 100 kg/min are required per wind shape, but usually 20 -50 kg/min, and wind shape.

Electric oven:

In addition to the blast furnace, the electric furnace is the most important metallurgical unit in which the injector is used. The main aim of blowing the mixtures described into the electric furnace is, in addition to the recycling of residual materials from the process itself and from outside the process, the formation of a stable foam slag, with its well-known advantages for the melting process. The addition of the carbon carrier for the formation of foam slag is usually still carried out by hand and at the discretion of the furnace personnel.

The injector ensures that the mixture can be added automatically, whereby the amount that is blown in per unit of time via one or more lances or a hollow electrode is either determined using a predefined operating diagram or is constantly checked and optimized using a new type of control system. To this end, the energy input per electrode is optimized using a new type of electrode regulation system, which also provides control information to the pneumatic injection system, via which the input amount is independently regulated over the course of the melt over time.

The blowing rate is between 10 and 500 kg/min, depending on the size of the furnace and the task; usual blowing rates are between 100 and 250 kg/min. The grain size of the mixture to be blown in is between 0-10 mm; for optimal mass and energy exchange, the optimal grain size is between 0-4 mm.

The injector works with a tubular dosage regulation system, which is attached under the actual pressurized transport vessel by means of a flange.

The material is discharged from the transport vessel after fluidization by means of loosening via a fluid base over a flap through the pipe bend into the injector. The quantity is regulated by a movable piston, which is firmly connected to an actuator by means of a piston rod, through which the transport gas is fed via a central bore. The free cross-section of the opening on the top of the injector pipe as a specific size for the quantity of material discharged per time period, through which the material reaches the horizontal injector, where it is entrained by the transport gas flow and discharged, is changed by moving the piston, whereby the necessary dosing accuracy can be ensured by the inventive design of a counter-rotating recess at the inner end of the piston.

1. Injector tube fixed

2. Dosing piston

3. Plain bearings

4. Air cushion

5. Material to be conveyed

6. Bracket for holding the electric drive control

7. Gunmetal plain bearings

8. Guide groove

Claims (10)

• 1 Claims: 1. Feed injector for the automated, pneumatic introduction of dusty or fine-grained products, in particular coal, silicate sand, filter and grinding dust or other processed residues from technical production processes, such as mill scale sludge, into metallurgical units such as blast furnaces, cupola furnaces, electric furnaces, converters or also into rotary kilns and/or combustion furnaces. Characterized by an injector provided with an adjustable piston with an opening running through the piston for the supply of transport gas and with a servomotor rigidly connected to the piston and to the injector via a piston rod, which can move the piston rod forwards and backwards in a horizontal direction by means of an actuator. 2. The injector is characterized by the fact that on the top of the horizontal injector tube there is an opening that enlarges in the opposite direction to the material flow, through which the material to be conveyed passes from the transport vessel into the injector, where it is discharged from the injector by the transport gas flowing through the movable piston. 3. The injector is characterized in that the movable piston has an opening on the side of the interior of the injector tube facing the direction of material flow, which opening widens towards the front and is in the opposite direction to the opening on the top of the injector tube. 4. The injector is characterized by the fact that a sliding bearing is mounted at the rear end of the injector tube between the wall and the movable piston. 5. The injector is characterized in that additional air is supplied through one or more openings in the casing of the injector tube to seal the injector. 6. The injector is characterized in that the transport gas is supplied through the fixed injector tube by means of a pressure difference control. 7. The injector is characterized in that the material to be conveyed is discharged at the same time from a transport vessel via one or more devices into a corresponding number of conveying lines, whereby any desired conveying quantities can be set for each of the conveying lines used. 8. The injector is characterized in that the actuator of the piston rod, by means of which the movable piston can be moved, is connected to the process system of the production process and is controlled by information provided by this process system. 9. The injector is characterized in that the actuator for the piston rod is controlled by means of time-dependent travel diagrams. 10. The injector is characterized in that the actuator for the piston rod is controlled by means of individual electrical, pneumatic or other process-relevant measured values.