WO2011036180A1

WO2011036180A1 - Method and device for using waste heat released in granulating a liquid slag

Info

Publication number: WO2011036180A1
Application number: PCT/EP2010/063982
Authority: WO
Inventors: Vladimir Danov; Carsten Graeber; Harald Landes; Martin Tackenberg
Original assignee: Siemens Aktiengesellschaft
Priority date: 2009-09-24
Filing date: 2010-09-22
Publication date: 2011-03-31
Also published as: DE102009042874A1

Abstract

Wet granulation is typically performed for reclaiming liquid slag, in particular blast furnace slag, and the slag is used in grainy consistency, for example for producing cement. The waste heat is thereby disposed of by means of cooling towers or the like. According to the invention, air granulation is performed, the hot air produced thereby by waste heat is discharged into a primary circuit and purified, and a secondary circuit is operated by means of a heat exchanger, wherein a steam turbine (20) is present for generating electrical power. It can be demonstrated that an efficiency of 27% can be achieved for a suitable construction of a device for performing the method according to the invention. The thus-generated electrical power is primarily consumed in operations, or can alternatively be fed into a power grid and serves to significantly lower costs.

Description

description

Process and apparatus for utilizing the waste heat released in the granulation of a liquid slag

The invention relates to a method for using the released during the granulation of liquid slag waste heat. In addition, the invention also relates to the supplied ^¬ hearing device for carrying out the method.

In the older, non-prepublished patent application with the DE-file number 10 2008 058 572.6 (Landes et al.) The on ^¬ detector is a method for the recovery of liquid

Slag using the enthalpy of heat contained in the slag, in which the hot slag is specifically introduced into the manufacturing process for cement clinker. As slag particular blast furnace slag is considered, with other liquid slags, in ^¬ example, steelworks slag or the like, can be used to the same extent.

Conventionally, the majority of the blast furnace ^¬ slag, which is liquid at about 1500 to 1600 ° C, quenched by atomization with large amounts of water, so that an amorphous, sandy product is formed, which is also referred to as blastfurnace slag. Such a blast furnace slag is - as vorste ^¬ starting already mentioned - for example in the Zementherstel ^¬ development application. Deviating from this so-called wet granulation, dry granulation methods have recently been described in the specialist literature, in which case a gas, for example air, is used here as the primary cooling medium. It is advantageous that both an energy-intensive drying of the granulated slag sand and the material and energy costs for a cleaning and continue to account for the transport of large amounts of potentially abrasive and acidic Kreislaufwas- sers. In the case of both granulation procedure, the heat energy from the granulation process is usually disposed of via a cooling tower.

The object of the invention is to specify an energetically improved method and a device for the granulation.

The object is achieved by a method of the type mentioned by the measures of claim 1. An associated device is shown in claim 8. Further developments of the method and the associated device are the subject of the dependent claims.

In the invention, the enthalpy of the liquid slag is suitably utilized. Due to the temperature level of the liquid slag of about 1500 to 1600 ° C one can with this enthalpy air or another gas at high temperature ^¬ temperatures, for example at 700 ° C and more, and warm white ^¬ terverwenden.

The hot air or the hot gas can be used either directly for heating purposes or in particular with in a downstream heat exchanger for steam generation. Among other things, the generated steam can be used to drive a turbine.

With the invention, therefore a considerable IMPROVE ^¬ tion results in that the heat contained in the slag is utilized in a suitable manner. This energy-technically and thus also ecologically significantly improved operation in the related metallurgical processes is possible.

Further details and advantages of the invention will become apparent from the following description of an exemplary embodiment with reference to the drawing in conjunction with the other claims. The single FIGURE shows a schematic representation of a granulation plant for liquid slag the associated media lines for displaying the process flow.

In Figure 1 at 1 is a container for liquid slag, examples game, a watering can, referred to in which is at ^¬ game as blast furnace slag with a temperature of 1500 °. The slag is introduced via an outlet 2 in a container for a dry granulation. Such a container is designated 10 and hermetically sealed to the outside. In the dry granulation container 10, the liquid slag is passed onto a rotating plate 11, where it is tangentially accelerated by adhesion to the plate and entrained by its viscosity and thrown by the centrifugal force almost radially outward and thereby sprayed into smaller particles that jump laterally ^¬ jump , For the rotating plate, a motor drive 12 is provided. Furthermore, in this embodiment, a unit 13 for spraying with water in order to ensure even at short periods of slag flow still sufficient cooling.

A first cooling of the slag droplets takes place during the flight from the plate into the cooling bed 14 whereby the surface of the droplets solidifies, so that they already meet in granular consistency on the cooling bed 14 through which air flows from below. From there they trickle supported by the agitation of the air flow in the cooling bed to the outlet at the lowest Stel ^¬ le of the container 10 and further into a reservoir 15, where the partially cooled, granular slag for further cooling by the air flow passes through and from time to Time can be deducted.

At the upper end of the container there is an outlet 16 for discharging the hot air, which has warmed to about 700 ° C when flowing through the closed container 10. The hot air is gerei ^¬ nigt in a unit 17 of soot and dust. Subsequently, the hot air is passed through a Wärmetau ^¬ shear 18 and reaches the input 19 of a Ver dichters and from there back as a cooling medium to the slag bed 14 and the collecting container 15th

By the above elements, a first heat cycle is formed. Through the heat exchanger 18, the heat is transferred to a second circuit, in particular by a steam turbine 20 for driving a subsequent generator 21 is located. The steam for the generator has a pressure of about 60 bar and a temperature of 450 ° C, so that it is suffi ^¬ cient for the steam turbine 20. At the outlet of the steam turbine ^¬ ne 20 is a condenser 22 for cooling and condensation of the exiting vapor, which has a pressure of about 50 mbar at a temperature of 33 ° C. The escaping water is returned by means of a pump 24 to the heat exchanger 18 and evaporated there again.

Simulation calculations were carried out for the case described. It has been shown that due to the high Tem ^¬ peraturniveaus the liquid slag, the air can be heated to high temperatures Tem ^¬, and that this hot air can be used in egg ^¬ nem downstream heat exchanger to generate steam for driving the turbine.

The fact that the liquid slag meets a rapidly rotating plate, it is accelerated so that it is divided into small droplets and thrown radially. On their route to the bottom of the granulation plant, the slag droplets release heat to the surrounding air and to the container walls by radiation. This increases to the droplet a shell of solidified slag and bil ^¬ det from even before hitting the ground a free-flowing grain. The slag grains fall on a sloping hole bottom, in which air is blown from below. As a result of this agitation, the grains, following gravity, reach the funnel-shaped granulation outlet and continue to release heat to the air. It is of advantage that the granulation part is egg ^¬ nes air circuit that directly receives the heat of the slag particles and ^¬ cools the heated by heat radiation of the particle walls.

In a further development it is possible to flow through the walls from the outside in addition to cooling air, on the one hand to the air vorzu ^¬ warm and on the other hand to protect the wall material thermally. Accordingly, the first heat cycle expediently leads the air coming from the compressor first to the outer wall of the dry granulation container 10. There, the air cools this dry granulation container 10 and is then, preheated, introduced into the dry granulation container 10 for use in dry granulation.

The hot air extracted from the top of the granulator is dedusted in a hot gas cyclone and fed to a heat exchanger. Calculations have shown that it cools from 700 ° to 70 °. The following blower serves to maintain the air circulation and generates the slight overpressure of

0.4 bar, which is required to drive the air through cyclone, heat exchangers and in particular through the fluidized granulation onsschüttung. A portion of the recirculated gas is passed into the granulation reservoir and takes there additionally slowly released from the granulated slag residual heat low temperature.

In the figure, the second steam cycle, in addition to the heat exchanger ^¬ at least from a downstream expansion turbine, a condenser and a feedwater pump.

By means of model calculations, it was determined that with the boundary conditions specified above for a blast furnace stream typical for a blast furnace of

17 kg / s results in a net electrical output of 7 MW, which corresponds to an efficiency of 27% based on the enthalpy of the slag. Above could be shown, then, that by the ^¬ He set the wet granulation the enthalpy of the liquid slag can be used by dry in an improved manner. It is advantageous in particular that no chemically aggressive wastewater and steam is formed, the water would also be abrasive due to high stress with ceramic particles. By dry granulation to air a much higher temperature level is erschlos ^¬ sen. There are no acidic exhaust gases and the Granulati ^¬ onsprodukt requires no energy-consuming post-drying.

The particle load is well controlled by the hot gas cyclone, as is known from the coal-based combustion technology. Through the steam cycle, a large part of the enthalpy content of the slag can be used and z. B. by

Operating the steam turbine with a high efficiency

(27%) are converted into electrical energy.

Claims

claims

1. A method for use of in the granulation of liquid slag released waste heat ^¬ steps with the following procedure:

- It is carried out a dry granulation with a gas as Kühlmedi ^¬ order, wherein the gas takes heat from the slag ^¬ , and

- The heat absorbed is used for energy.

2. The method of claim 1, wherein the heat absorbed is used to generate steam.

3. The method of claim 2, wherein the generated steam is used in a steam turbine (20) for generating electricity.

4. The method according to any one of the preceding claims, wherein the gas via a primary circuit with heat exchanger (18) ge ^¬ leads and the heat exchanger transfers the heat to a secondary circuit.

5. The method of claim 4, wherein the primary circuit and / or the secondary circuit are formed as a closed circuit.

6. The method according to any one of the preceding claims, wherein the granulation is carried out continuously.

7. The method according to any one of the preceding claims, wherein the dry granulation in a container (10) is performed and the container (10) is cooled by being flowed from the outside of the gas or at least partially flows around.

8. Device for granulation of liquid slag and the use of the released waste heat, comprising:

a device (10) for dry granulation of the slag,

- means (14) for introducing a gas as a cooling medium into the device (10), - Means (16) for supplying the gas heated in the device or its heat to an energy recovery device (20) for generating energy using the heat of the heated gas.

9. Apparatus according to claim 8 with a steam turbine (20) with an electric generator (21) as an energy recovery device.

10. The device according to claim 8 or 9, wherein the means (10) for dry granulation with a primary circuit for guiding the gas is connected and the primary circuit via a heat exchanger (18) is connected to a secondary circuit for using the cached heat in the gas.

11. The device according to claim 10 with a Staubabtrennungs- device (17) for at least partially cleaning the gas in the primary circuit.

12. The apparatus of claim 10 or 11 with a compressor (19) in the primary circuit.