RU2842746C1 - Method and device for granulation of blast-furnace slag and recovery and recycling of waste heat - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to a device and method for granulation of blast-furnace slag and recovery and recycling of waste heat. Proposed device comprises nozzle module for aerosol granulation, guide 7, cyclone separator 8 and waste heat recovery device. Proposed module comprises slag flow controller 2, compressed air flow control valve 3, water volume control valve 4 and aerosol sprayer 5. In guiding device achieving heat exchange during mixing between medium-temperature gas and high-temperature granular slag (6) and hardening of high-temperature granular slag, and medium to high temperature gas and high-temperature granular slag after heat exchange is fed into cyclone separator. Cyclone separator performs separation of gas with temperature from medium to high and high-temperature granulated slag and transports gas with temperature from medium to high and high-temperature granulated slag to waste heat recovery device.

EFFECT: providing granulation of blast-furnace slag and organically combines the recovery of sensible heat of the slag with drying the sludge, obtaining high-temperature steam, generating electric power and obtaining low-temperature hot water, thereby recovering the waste heat of the medium-temperature gas and high-temperature particles in the process of slag granulation and increasing the efficiency of recovery and recycling of waste heat.

14 cl, 4 dwg, 3 ex

Description

Field of technology

The present invention relates to a device and method for processing metallurgical slag, in particular to a device and method for granulating blast furnace slag and recycling waste heat.

State of the art

Blast furnace slag is the main by-product of blast furnace iron production. There are about 350 kg of blast furnace slag per ton of cast iron. The temperature of blast furnace slag at the furnace outlet is 1450 to 1550 °C. The sensible heat ((1260-1880)×10 ³ kJ) transferred by one ton of slag is equivalent to the heat released by 60 kg of standard coal, so the recovery of sensible heat is of great value.

At present, blast furnace slag is mainly recycled by the water quenching process, in which the furnace slag is washed with high-pressure water to form water slag, and accordingly, a large amount of sensible heat is transferred to the water slag and waste water at about 80°C, losing its value for recovery. In addition, 0.4 to 0.5 tons of water are consumed to recycle one ton of slag, and a large amount of exhaust steam rich in _H2S , _SO2 and other pollutants is released. For subsequent use of resources (such as fine grinding), it is necessary to remove 8-15% of the water in the water slag by drying by consuming about 1000 ^m3 of hot air at 500°C per ton of slag, which results in a large loss of resources.

Blast furnace slag is a high-temperature melt formed from gangue in ore, ash in fuel and non-volatile components in solvent ( _usually limestone) in the blast furnace iron making process. The said high temperature is about 1450°C. The main components of blast furnace slag include silicon dioxide ( _SiO2 ), aluminum oxide ( _Al2O3 ), calcium oxide (CaO), magnesium oxide (MgO), manganese oxide (MnO), iron oxide (FeO) and sulfur, etc., and _the mass ratio of silicon dioxide ( _SiO2 ) and aluminum oxide ( _Al2O3 ) to calcium oxide (CaO) and magnesium oxide (MgO) is about 0.8-1.2. Therefore, blast furnace slag is characterized by a low thermal conductivity coefficient and a sharp increase in viscosity with decreasing temperature, which causes slow heat transfer from blast furnace slag and great difficulties with the recovery of waste heat.

Rapid dry granulation of slag particles can provide conditions for heat recovery. At present, the rapid dry granulation of slag mainly includes air granulation and centrifugal granulation. The air granulation process has not been widely applied in the field of blast furnace slag processing due to its high noise and easy formation of slag wool. It is only suitable for processing some steel slags with good fluidity. In centrifugal granulation, a rotating disk or rotating cup is mainly used as a granulator, which uses centrifugal force to disperse and crush the slag into small droplets to facilitate rapid cooling, so that the glass phase content and activity of the cooled slag particles meet the requirements of slag micropowder raw materials. However, there are problems such as the formation of slag crust, non-uniform particle size of the granulated slag, and easy formation of slag wool.

Chinese Invention Patent ZL 201410755689.9 discloses a system and method for recovering waste heat from high-temperature slag. The device includes a slag transporting unit, a slag granulating unit, and a waste heat recovery unit. It can recover the sensible heat of high-temperature slag. However, when recovering waste heat, the slag is transported to the slag receiver for a long distance, and it is easy to cool. Therefore, it is necessary to supply additional heat. The energy consumption is high, and the waste heat recovery efficiency is low.

Chinese Invention Patent ZL 201010566938.1 discloses a system for dry granulation of metallurgical slag and recovery of thermal energy. Liquid slag is dry granulated by centrifugal rotation and pulsed air flow. Air flow nozzles and water spray nozzles are respectively arranged in an annular shape around the rotating shaft of the centrifugal rotating disk under the centrifugal rotating disk. A water-cooled wall is provided on the inner side wall of the dry granulation device. A fluidizing device with an annular conical surface is provided under the water-cooled wall, and an annular fluidized bed is provided at the lower part of the dry granulation device. The utilization of waste heat recovered from the slag according to this invention patent is limited to converting into steam by hot air/nitrogen or generating electricity, and the efficiency is low.

As a kind of solid waste, sludge has become the second largest source of solid waste pollution after urban waste pollution. The traditional sludge treatment methods mainly include burial, incineration, sea discharge and agricultural use. In the field of wastewater treatment, including industrial wastewater, domestic wastewater, etc., sludge treatment is also commonly adopted. With the development of technology, known sludge treatment methods include fermentation, melting, lime addition, carbonation, etc. However, the equipment cost and energy consumption are very high, the treatment efficiency is low, and secondary pollution of air and water sources may occur.

Summary of the invention

One of the objectives of the present invention is to provide a device and method for granulating blast furnace slag and recycling waste heat, by means of which complete granulation of blast furnace slag is achieved, wherein the recovery of sensible heat of slag is organically linked with drying of slag and obtaining steam and hot water, so that waste heat is extracted from gas with a temperature from medium to high and high-temperature granulated slag in the process of granulating slag, which significantly increases the efficiency of recovery and utilization of waste heat.

The above-mentioned object of the present invention is realized as follows.

A device for granulating blast furnace slag and recycling waste heat, which comprises an aerosol granulation nozzle module, a flow guide, a cyclone separator and a waste heat recovery device;

wherein the aerosol granulation nozzle module comprises a slag flow regulator, a compressed air flow regulation valve, a water volume regulation valve and an aerosol atomizer; wherein the slag flow regulator is connected to the slag inlet of the flow guide; the compressed air flow regulation valve is connected to the gas inlet of the aerosol atomizer; the water volume regulation valve is connected to the liquid inlet of the aerosol atomizer; wherein the nozzle of the aerosol atomizer is designed in such a way that it faces the inlet of the flow guide in order to ensure the possibility of collision of the aerosol with the slag flow entering the flow guide through the slag flow regulator, with the formation of a medium-temperature gas and a high-temperature granulated slag having a primarily solidified surface;

wherein the flow guide is designed for complete mixing of the medium-temperature gas and the high-temperature granulated slag having a primarily solidified surface in the flow guide, wherein the outlet of the flow guide is connected to the loading opening of the cyclone separator to ensure that fully solidified high-temperature granulated slag and gas with a temperature from medium to high, formed in the flow guide, enter the cyclone separator;

wherein the cyclone separator is designed to separate high-temperature granulated slag and gas with a temperature from medium to high; wherein the outlet of the cyclone separator is connected to the loading opening of the heat recovery device for feeding gas with a temperature from medium to high and fully solidified high-temperature granulated slag into the heat recovery device.

In some embodiments, the present invention provides a device for granulating blast furnace slag and recycling waste heat, which comprises an aerosol granulation nozzle module, a flow guide, a cyclone separator, and a waste heat recovery device;

wherein the nozzle module of the aerosol granulation comprises a slag flow regulator, a compressed air flow regulation valve, a water volume regulation valve and an aerosol atomizer, wherein the slag flow is regulated by the slag flow regulator, and it flows into the slag inlet of the flow guide; high-pressure gas is directed to the gas inlet of the aerosol atomizer through the compressed air flow regulation valve; water is directed to the liquid inlet of the aerosol atomizer through the water volume regulation valve; wherein the nozzle of the aerosol atomizer is designed so that it faces the inlet of the flow guide in order to ensure the possibility of collision of the aerosol with the slag flow with the formation of a medium-temperature gas and a high-temperature granulated slag having a primarily solidified surface;

wherein the outlet of the flow guide is connected to the feed port of the cyclone separator, the medium-temperature gas and the high-temperature granulated slag having a primarily solidified surface are completely mixed in the flow guide to form a fully solidified high-temperature granulated slag and a gas with a medium to high temperature, which are then fed to the cyclone separator to separate the high-temperature granulated slag and the gas with a medium to high temperature by the cyclone separator; wherein the outlet of the cyclone separator is connected to the feed port of the heat recovery device to supply the gas with a medium to high temperature and the fully solidified high-temperature granulated slag to the heat recovery device.

The medium-temperature gas after formation by collision of an aerosol from the nozzle module of aerosol granulation with the slag flow has a temperature of 200-400°C, and the high-temperature granulated slag with a primarily solidified surface has a temperature of 1000-1200°C; wherein the gas with a temperature from medium to high after mixing in the flow guide has a temperature of 300-500°C, and the fully solidified high-temperature granulated slag has a temperature of 800-1100°C; wherein after separation in the cyclone separator the high-temperature granulated slag has a temperature of 700-950°C, and the gas with a temperature from medium to high has a temperature of 350-550°C.

The heat recovery device is a sludge drying module including a screw mixer, a sludge dryer, a sludge pre-drying module, a slag and sludge extraction module, and a residual gas processing module. The outlet of the cyclone separator is connected to the first loading port of the screw mixer to transport fully solidified high-temperature granulated slag into the screw mixer. The aerosol opening of the cyclone separator is connected to the aerosol opening of the sludge pre-drying module to transport gas with a medium to high temperature into the sludge pre-drying module, so that the gas with a medium to high temperature is mixed with the wet sludge in the sludge pre-drying module to form a semi-dry sludge. The outlet of the sludge pre-drying module is connected to the second loading port of the screw mixer for transporting the semi-dry sludge into the screw mixer, so that the semi-dry sludge and the high-temperature granulated slag are mixed in the screw mixer to form a sludge-sludge mixture. The outlet of the screw mixer is connected to the loading port of the sludge dryer for transporting the sludge-sludge mixture into the sludge dryer. The outlet of the sludge dryer is connected to the loading port of the sludge and sludge extraction module for transporting the dry sludge powder and sludge granules into the sludge and sludge extraction module. The gas inlet of the residual gas treatment module is connected to the gas outlet of the sludge pre-drying module, the gas outlet of the sludge dryer and the gas outlet of the sludge and sludge extraction module, respectively.

The waste heat recovery device is a high-temperature steam module. The high-temperature steam module is connected to a cyclone separator for recovering heat from medium-to-high-temperature gas and high-temperature granulated slag to produce high-temperature steam having a temperature of 200-250°C. The high-temperature steam is fed into the pipeline network for use at the same level or for generating electricity. The outlet for residual gas of the high-temperature steam module is connected to a residual gas processing module.

In some embodiments, the high-temperature steam generation module comprises a slag hopper, a residual gas treatment device, a gas cleaning device, a smoke exhauster, a smoke stack, a high-temperature feed conveyor, a heat exchanger for high-temperature granulated slag, a steam boiler, and an economizer;

wherein the high-temperature feed conveyor is arranged between the outlet of the cyclone separator and the loading port of the heat exchanger for high-temperature granulated slag for transporting the high-temperature granulated slag separated by the cyclone separator to the upper portion of the heat exchanger for high-temperature granulated slag; in the heat exchanger for high-temperature granulated slag, a coil containing circulating water is provided for reverse heat exchange of the high-temperature granulated slag with this coil and a gas flow rising from the bottom up; a slag hopper is arranged under the outlet arranged at the lower portion of the heat exchanger for high-temperature granulated slag for receiving the cooled granulated slag; the upper portion of the heat exchanger for high-temperature granulated slag is provided with a gas opening connected to a steam boiler; the economizer is connected to the steam boiler and the heat exchanger for high-temperature granulated slag, respectively, so that the clean water supplied to the economizer through the external pipeline network is preheated to 80°C or higher by the residual gas discharged from the steam boiler, and divided into two parts, one part is sent to the steam boiler, and the other part enters the coil of the heat exchanger for high-temperature granulated slag to absorb the heat of the high-temperature granulated slag; the gas inlet of the residual gas treatment device is connected to the residual gas outlet of the economizer, the gas outlet of the residual gas treatment device is connected to the gas inlet of the residual gas cleaning device, and the gas outlet of the residual gas cleaning device is connected to the smoke stack through a smoke exhauster for cleaning and discharging the residual gases.

In some embodiments, when the water in the coil evaporates and its temperature rises to approximately 250°C, it enters the steam drum at the top of the steam boiler, where it mixes with steam generated by the steam boiler itself and is fed into the external piping network.

The heat recovery device is a low-temperature hot water module. The low-temperature hot water module is connected to a cyclone separator for heat recovery of gas with a temperature from medium to high and high-temperature granulated slag to obtain low-temperature hot water having a temperature of 70-95°C. The low-temperature hot water is supplied to the consumer for use at the same level or for cooling purposes. The outlet for residual gas of the low-temperature hot water module is connected to a residual gas processing module.

In some embodiments, the low-temperature hot water production module includes a slag hopper, a residual gas treatment device, a gas cleaning device, a smoke exhauster, a smoke stack, a high-temperature feed conveyor, a heat exchanger for high-temperature granulated slag, and a steam boiler;

wherein the high-temperature feed conveyor is arranged between the outlet of the cyclone separator and the loading port of the heat exchanger for high-temperature granulated slag for transporting the high-temperature granulated slag separated by the cyclone separator to the upper portion of the heat exchanger for high-temperature granulated slag; in the heat exchanger for high-temperature granulated slag, a coil containing circulating water is provided for reverse heat exchange of the high-temperature granulated slag with this coil and a gas flow rising from the bottom up; a slag hopper is arranged under the outlet arranged at the lower portion of the heat exchanger for high-temperature granulated slag for receiving the cooled granulated slag; the upper portion of the heat exchanger for high-temperature granulated slag is provided with a gas opening connected to a steam boiler; the steam boiler and the high-temperature granulated slag heat exchanger are connected to an external pipeline network, respectively, to obtain clean water for heat exchange in the steam boiler and the high-temperature granulated slag heat exchanger; the gas inlet of the residual gas treatment device is connected to the residual gas outlet of the steam boiler, the gas outlet of the residual gas treatment device is connected to the gas inlet of the residual gas cleaning device, and the gas outlet of the residual gas cleaning device is connected to a smoke stack through a smoke exhauster for cleaning and discharging the residual gases.

The residual gas treatment module includes a residual gas treatment device, a residual gas cleaning device, a smoke exhauster and a smoke stack. The gas inlet of the residual gas treatment device is connected to the gas outlet of the sludge pre-drying module, the gas outlet of the sludge dryer, the gas outlet of the sludge and sludge extraction module, the residual gas outlet of the steam boiler and the residual gas outlet from the economizer through pipelines, respectively. The gas outlet of the residual gas treatment device is connected to the gas inlet of the residual gas cleaning device, and the gas outlet of the residual gas cleaning device is connected to the smoke stack through the smoke exhauster.

A method for granulating blast furnace slag and recycling waste heat, comprising the following stages:

stage 1: feeding the blast furnace slag separated from the molten iron into the slag trough, where a slag flow is formed and flows into the flow guide after its flow is regulated by the slag flow regulator;

step 2: adjusting the compressed air flow regulating valve and the water volume regulating valve to form a high-pressure aerosol in the aerosol sprayer and spraying the high-pressure aerosol through the nozzle, so that the high-pressure aerosol collides with the slag flow entering the flow guide to form a medium-temperature gas and a high-temperature granulated slag with a pre-solidified surface;

stage 3: mixing and performing heat exchange of the medium-temperature gas and the high-temperature granulated slag with a pre-solidified surface through a flow guide to form a fully solidified high-temperature granulated slag and a gas with a medium to high temperature, which are transported to a cyclone separator in which the high-temperature granulated slag and the gas with a medium to high temperature are separated;

Step 4: transporting the medium to high temperature gas and the high temperature granulated slag to the waste heat recovery device from the cyclone separator, wherein the heat of the medium to high temperature gas and the high temperature granulated slag is recovered by the waste heat recovery device and used for drying the sludge, producing high temperature steam, generating electricity or producing low temperature hot water.

In some embodiments of the method, after formation by collision of an aerosol from the nozzle module of aerosol granulation with a slag flow, the medium-temperature gas has a temperature of 200-400°C, and the high-temperature granulated slag having a pre-solidified surface has a temperature of 1000-1200°C. After mixing in the flow guide, the gas with a temperature from medium to high has a temperature of 300-500°C, and the fully solidified high-temperature granulated slag has a temperature of 800-1100°C. After separation in the cyclone separator, the high-temperature granulated slag has a temperature of 700-950°C, and the gas with a temperature from medium to high has a temperature of 350-550°C.

In some embodiments, the sludge drying step comprises:

Stage 4.1.1: Pumping wet sludge from the sludge tank using a sludge pump to the sludge pre-dryer;

Stage 4.1.2: mixing and reverse heat exchange of the wet sludge with medium to high temperature gas in a sludge pre-dryer to form a semi-dry sludge;

stage 4.1.3: transporting the semi-dry sludge from the sludge pre-drying module to the screw mixer and transporting the high-temperature granulated slag from the cyclone separator to the screw mixer, wherein the semi-dry sludge and the high-temperature granulated slag are mixed in the screw mixer to form a mixture of slag and sludge;

stage 4.1.4: transporting the slag and sludge mixture from the screw mixer to the sludge dryer, wherein the sludge dryer ensures drying of the slag and sludge mixture to obtain dry sludge powder and slag granules, which are transported to the slag and sludge extraction module;

stage 4.1.5: separation of dry sludge powder from slag granules in the slag and sludge separator of the slag and sludge extraction module;

Stage 4.1.6: transporting dry sludge powder from the sludge separator to the dry sludge powder bin for temporary storage;

Stage 4.1.7: Transport of slag granules from the slag separator to the slag bin for temporary storage.

The method further includes cleaning and discharging the wet residual gas using a residual gas processing module, including: collecting and pre-treating the wet residual gases from the sludge pre-dryer, sludge dryer and slag and sludge separator using a residual gas processing device of the residual gas processing module, followed by deep cleaning in a residual gas cleaning device, wherein the residual gas purified to meet the standard is discharged through a smoke stack with a smoke exhauster, and the fine powder collected in the residual gas processing device and in the residual gas cleaning device is extracted into an external tank.

In some embodiments, the step of producing high temperature steam comprises:

Step 4.2.1: transporting the high-temperature granulated slag from the cyclone separator to the high-temperature granulated slag conveyor, which lifts the high-temperature granulated slag and uniformly feeds it into the high-temperature granulated slag heat exchanger through the upper inlet of the high-temperature granulated slag heat exchanger, wherein the high-temperature granulated slag moves from top to bottom, and in the process of descending, it contacts and exchanges heat in a counter-current manner with the cooling water in the coil and the air rising from bottom to top;

Stage 4.2.2: discharging heated steam from the upper part of the heat exchanger for high-temperature granulated slag and directing it to the steam boiler, and discharging cooled granulated slag from the lower part of the heat exchanger for high-temperature granulated slag into the slag bin;

stage 4.2.3: directing clean water from the external pipeline network to the economizer for preheating to 80°C or higher by the residual gas discharged from the steam boiler, wherein one part of the preheated clean water is directed to the steam boiler for further heating and evaporation to produce steam having a temperature of 200-250°C, and the other part is fed to the coil of the heat exchanger for high-temperature granulated slag to absorb the heat of the high-temperature granulated slag;

stage 4.2.4: feeding water from the coil into the steam drum at the top of the steam boiler after it has evaporated and heated to approximately 250°C, where it mixes with the steam generated in the steam boiler itself and then enters the external piping network.

In some embodiments, the step of producing low temperature hot water comprises:

Step 4.3.1: transporting the high-temperature granulated slag from the cyclone separator to the high-temperature granulated slag conveyor, which lifts the high-temperature granulated slag and uniformly feeds it into the high-temperature granulated slag heat exchanger through the upper inlet of the high-temperature granulated slag heat exchanger, in which the high-temperature granulated slag moves from top to bottom, and in the process of descending, it contacts and exchanges heat in a counter-current manner with the cooling water in the coil and the air rising from bottom to top;

stage 4.3.2: discharging heated low-temperature hot water with a temperature of 70-95°C from the top of the heat exchanger for high-temperature granulated slag and directing it to the steam boiler and discharging cooled granulated slag from the bottom of the heat exchanger for high-temperature granulated slag into the slag hopper;

stage 4.3.3: feeding one part of clean water from the external pipeline network into the steam boiler to be heated to 70-95°C by the residual gas passing through the steam boiler, and feeding the other part of it into the coil of the heat exchanger for high-temperature slag granulation to absorb the heat of the high-temperature granulated slag;

Stage 4.3.4: Feeding water from the coil to the steam drum at the top of the steam boiler after it has been heated by heat absorption, mixing with the hot water generated in the steam boiler itself, and then feeding it to the external piping network.

In some embodiments, the method further comprises cleaning and discharging the wet residual gas using a residual gas processing module, including: collecting and pre-treating the wet residual gas from the sludge pre-dryer, the sludge dryer and the sludge and sludge separator using a residual gas processing device of the residual gas processing module, followed by deep cleaning using a residual gas cleaning device, wherein the residual gas purified to meet the standards is discharged through a smoke stack with a smoke exhauster, and the fine powder collected in the residual gas processing device and in the residual gas cleaning device is extracted into an external bin.

Compared with the prior art, the present invention exhibits the following advantageous effects.

1. Using the blast furnace slag granulation and waste heat recycling apparatus according to the present invention, the blast furnace slag encounters an aerosol and undergoes cyclone separation to form a fully solidified high-temperature granulated slag and a gas with a medium to high temperature. The granulated slag has a uniform particle size, and the formation of slag wool is avoided during granulation. The separated high-temperature granulated slag and the gas with a medium to high temperature can be directly used in each stage of sludge drying with high efficiency of waste heat recovery, and can also be used for generating high-temperature steam, generating electricity, extracting hot water, etc.

2. The blast furnace slag granulation and waste heat recycling device according to the present invention organically combines the recovery of sensible heat of slag with the drying of sludge. The blast furnace slag is quickly and safely granulated, and the sludge is effectively dried. This not only greatly improves the efficiency of waste heat recycling, but also reduces the cost of waste heat recovery. The problem of low efficiency and high cost of sludge drying is solved.

3. In the method for granulating blast-furnace slag and recycling waste heat according to the present invention, blast-furnace slag is completely granulated to obtain high-temperature granulated slag suitable for waste heat recovery with high efficiency. By recovering the waste heat of the gas with a medium to high temperature and the high-temperature granulated slag, the sensible heat of the slag is utilized at the same level to the maximum extent, which brings about better economic and social benefits.

Thus, according to the present invention, complete granulation of blast furnace slag is realized and uniform particle size is achieved. Slag sensible heat recovery and slag drying are organically combined, so that waste heat of medium to high temperature gas and high temperature granulated slag is recovered in the slag processing process. The efficiency of waste heat recycling is greatly improved, and good economic and social benefits are achieved. The device and method can be popularized and applied in the field of slag processing for blast furnaces of various sizes and have broad prospects.

Brief description of the drawings

Fig. 1 shows a flow chart of example 1 of a device for granulating blast furnace slag and recycling waste heat in accordance with the present invention;

Fig. 2 shows a flow chart of example 2 of a device for granulating blast furnace slag and recycling waste heat in accordance with the present invention;

Fig. 3 shows a flow chart of example 3 of a device for granulating blast furnace slag and recycling waste heat in accordance with the present invention;

Fig. 4 shows a block diagram of a method for granulating blast furnace slag and recycling waste heat in accordance with the present invention. In the drawings, the dotted line shows the pipeline for transporting the gas flow, and the solid line shows the pipeline for transporting the slag granules.

In the drawings: 1 - slag flow, 2 - slag flow regulator, 3 - compressed air flow control valve, 4 - water volume control valve, 5 - aerosol sprayer, 6 - slag granules, 7 - flow guide, 8 - cyclone separator, 9 - screw mixer, 10 - sludge dryer, 11 - slag hopper, 12 - dry sludge powder hopper, 13 - slag and sludge separator, 14 - sludge pre-dryer, 15 - sludge pump, 16 - sludge tank, 17 - residual gas treatment device, 18 - residual gas cleaning device, 19 - smoke exhauster, 20 - smoke stack, 21 - high-temperature feed conveyor, 22 - heat exchanger for high-temperature granulated slag, 23 - steam boiler, 24 - economizer.

Detailed description of the invention

The invention is further illustrated with reference to the accompanying drawings and specific embodiments.

Fig. 1 shows a device for granulating blast furnace slag and recycling waste heat, including a nozzle module for aerosol granulation, a flow guide 7, a cyclone separator 8 and a waste heat recovery device.

The nozzle module of aerosol granulation comprises a slag flow regulator 2, a compressed air flow regulation valve 3, a water volume regulation valve 4 and an aerosol atomizer 5. The flow of slag flow 1 is regulated by slag flow regulator 2, and then slag flow 1 enters the slag inlet of flow guide 7. High-pressure gas flows through compressed air flow regulation valve 3 and enters the gas inlet of aerosol atomizer 5. A small amount of water passes through water volume regulation valve 4 and enters the inlet of aerosol atomizer 5. The nozzle of aerosol atomizer 5 faces the inlet of flow guide 7, and slag flow 1 collides with the aerosol to form medium-temperature gas and high-temperature granulated slag 6 having a primarily solidified surface. The aerosol granulation nozzle module uses high-pressure gas and a small amount of water to crush, granulate and rapidly cool the blast furnace slag, so that the temperature of the blast furnace slag is rapidly reduced from 1450°C to 1000-1200°C, preferably 1100°C, and the surface of the blast furnace slag is primarily solidified. The granulated slag has a uniform particle size.

The outlet of the flow guide 7 is connected to the loading opening of the cyclone separator 8. The medium-temperature gas and the high-temperature granulated slag 6, which has a predominantly solidified surface, are completely mixed in the flow guide to form a completely solidified high-temperature granulated slag 6 and a gas with a temperature from medium to high, which then enter the cyclone separator 8, in which the high-temperature granulated slag 6 is separated from the gas with a temperature from medium to high. The outlet of the cyclone separator 8 is connected to the loading opening of the heat recovery device, and the gas with a temperature from medium to high and the completely solidified high-temperature granulated slag 6 are transported to the heat recovery device. The high-temperature granulated slag 6, which has a predominantly solidified surface, and the medium-temperature gas are completely mixed in the flow guide 7 and enter the cyclone separator 8 for complete mixing and heat exchange, so that the high-temperature granulated slag 6 is completely solidified and the formation of slag wool is prevented. This is more favorable for heat recovery. At the same time, the gas flow with a medium to high temperature and the high-temperature granulated slag 6 are separated. The temperature of the separated high-temperature granulated slag 6 is reduced to 700-950°C, preferably to 800-850°C, which is favorable for the recycling of waste heat in the heat recovery module.

The temperature of the slag flow 1 is 1450-1550°C. The temperature of the medium-temperature gas formed during the collision of the aerosol from the nozzle module of the aerosol granulation with the slag flow 1 is 200-400°C. The temperature of the high-temperature granulated slag 6 with a pre-hardened surface is 1000-1200°C, preferably 1100°C.

The temperature of the gas with a medium to high temperature mixed in the flow guide 7 is 300-500°C, preferably 400°C. The temperature of the fully solidified high-temperature granulated slag 6 is 800-1100°C, preferably 950°C. After separation in the cyclone separator 8, the temperature of the high-temperature granulated slag 6 is 700-950°C, preferably 800-850°C, and the temperature of the gas with a medium to high temperature is 350-550°C.

The waste heat recovery device is a sludge drying module that can be used directly for drying sludge. The problem of complexity and energy consumption of sludge processing is solved. The sludge drying module includes a screw mixer 9, a sludge dryer 10, a sludge pre-drying module, a slag and sludge extraction module and a residual gas processing module. The outlet of the cyclone separator 8 is connected to the first loading opening of the screw mixer 9 for transporting fully solidified high-temperature granulated slag 6 into the screw mixer 9. The aerosol opening of the cyclone separator 8 is connected to the aerosol opening of the sludge pre-drying module for transporting gas with a medium to high temperature into the sludge pre-drying module, so that the gas with a medium to high temperature is mixed with the wet sludge in the sludge pre-drying module to form a semi-dry sludge. The outlet of the sludge pre-drying module is connected to the second loading opening of the screw mixer 9 for transporting the semi-dry sludge into the screw mixer 9, so that the semi-dry sludge and the fully solidified high-temperature granulated slag 6 are mixed in the screw mixer 9 to form a mixture of slag and sludge. The outlet of the screw mixer 9 is connected to the loading opening of the dryer 10 to feed the sludge and sludge mixture into the sludge dryer 10 to form dry sludge powder and low-temperature slag granules. The outlet of the sludge dryer 10 is connected to the loading opening of the slag and sludge extraction module to transport the dry sludge powder and slag granules into the slag and sludge extraction module. The gas inlet of the residual gas treatment module is connected to the gas outlet of the sludge pre-drying module, the gas outlet of the sludge dryer 10 and the gas outlet of the slag and sludge extraction module.

The sludge pre-drying module includes a sludge pre-dryer 14, a sludge pump 15 and a sludge tank 16. The outlet opening of the sludge tank 16 is connected to the loading opening of the sludge pre-dryer 14 by a pipeline on which the sludge pump 15 is provided, so that the wet sludge from the sludge tank 16 is transported to the sludge pre-dryer 14. The sludge pre-dryer 14 is provided with an aerosol opening, which is connected to the aerosol opening of the cyclone separator 8. The aerosol opening and the loading opening of the sludge pre-dryer 14 are located at two ends of the sludge pre-dryer 14, respectively, so that the gas with a medium to high temperature and the sludge move in opposite directions, and reverse heat exchange occurs between them. The contact area between the gas with a medium to high temperature and the sludge is large, and they are completely mixed with high heat exchange efficiency. The sludge pre-dryer 14 is provided with a gas outlet, which is connected to the gas inlet of the residual gas processing module. The wet sludge from the sludge tank 16 is pumped into the pre-dryer 14 by the sludge pump 15, and heat exchange occurs with the gas with a medium to high temperature in the sludge pre-dryer 14 to form a semi-dry sludge.

The slag and sludge extraction module includes a slag bin 11, a bin 12 for dry sludge powder and a slag and sludge separator 13. The slag and sludge separator 13 is provided with a loading opening, two outlet openings and a gas outlet. The outlet opening of the sludge dryer 10 is connected to the loading opening of the slag and sludge separator 13. Two outlet openings of the slag and sludge separator 13 are connected to the slag bin 11 and the dry sludge powder bin 12, respectively. The gas inlet of the residual gas treatment module is connected to the gas outlet of the slag and sludge separator 13. The mixture of dry sludge powder and slag granules enters the slag and sludge separator 13 and is then separated in the slag and sludge separator 13. The dry sludge powder is temporarily stored in the dry sludge powder bin 12, and the slag granules are temporarily stored in the slag bin 11, which can facilitate subsequent extraction and processing. The wet residual gas from the slag and sludge separator 13 enters the residual gas processing module.

The residual gas processing module comprises a device 17 for processing residual gases, a device 18 for cleaning residual gases, a smoke exhauster 19 and a smoke stack 20. The gas inlet of the device 17 for processing residual gases is connected to the gas outlet of the preliminary sludge dryer 14 in the preliminary sludge drying module, the gas outlet of the sludge dryer 10, the gas outlet of the sludge and sludge separator 13 in the sludge and sludge extraction module, the residual gas outlet of the steam boiler 23 and the residual gas outlet of the economizer 24 via pipelines, respectively. The gas outlet of the device 17 for processing residual gases is connected to the gas inlet of the device 18 for cleaning residual gases. The gas outlet of the device 18 for cleaning residual gases is connected to the smoke stack 20 via the smoke exhauster 19. The device 17 for processing residual gases collects the wet residual gas and provides its primary cleaning. The primary purified residual gas is directed to the device 18 for cleaning residual gases for deep cleaning, and then removed through the smoke pipe 20 by the smoke exhauster 19.

At the bottom of both the residual gas treatment device 17 and the residual gas cleaning device 18, outlet openings are provided. The outlet opening can be connected externally to a tank via a pipe. The external tank can collect a small amount of fine powder filtered from the residual gas treatment device 17 and the residual gas cleaning device 18 to ensure the normal operation of the residual gas treatment device 17 and the residual gas cleaning device 18, and also facilitate the subsequent use and processing of the fine powder.

As shown in Fig. 2, the waste heat recovery device is a high-temperature steam production module, which can be used to produce high-temperature steam for generating electric power. The high-temperature steam production module is connected to the cyclone separator 8 and recovers heat from the gas with a medium to high temperature and the high-temperature granulated slag 6 to produce high-temperature steam with a temperature of 200-250°C. The high-temperature steam is supplied to the pipeline network for use at the same level or for generating electric power. The outlet for residual gases of the economizer 24 of the high-temperature steam production module is connected to the residual gas processing module.

The high-temperature steam production module includes a slag bin 11, a residual gas treatment device 17, a residual gas cleaning device 18, a smoke exhauster 19, a smoke stack 20, a high-temperature feed conveyor 21, a heat exchanger 22 for high-temperature granulated slag, a steam boiler 23 and an economizer 24. The high-temperature feed conveyor 21 is located between the outlet opening of the cyclone separator 8 and the loading opening of the heat exchanger 22 for high-temperature granulated slag. The high-temperature granulated slag 6 separated by the cyclone separator 8 is transported by means of the high-temperature feed conveyor 21 into the upper part of the heat exchanger 22 for high-temperature granulated slag, and it slowly descends. A coil containing circulating water is provided in the heat exchanger 22 for high-temperature granulated slag. The high-temperature granulated slag 6 is subjected to reverse heat exchange with the coil and the gas flow rising from the bottom upwards, and is thus cooled to 100°C. The slag hopper 11 is located under the outlet opening located in the lower part of the heat exchanger 22 for the high-temperature granulated slag. The cooled granulated slag is directed into the slag hopper 11 for subsequent processing. In the upper part of the heat exchanger 22 for the high-temperature granulated slag, a gas opening is provided, connected to the steam boiler 23. The economizer 24 is connected to the steam boiler 23. Clean water is directed from the external pipeline network to the economizer 24 and is preheated with low-temperature residual gas (below 250°C), leaving the steam boiler 23, to 80°C or higher. One portion of the heated clean water is directed to the steam boiler 23 for further heating and evaporation to produce high-temperature steam (200-250°C), and the other portion enters the coil of the heat exchanger 22 for high-temperature granulated slag to absorb the heat of the high-temperature granulated slag 6. When the water in the coil evaporates and heats up to approximately 250°C, it enters the steam drum located in the upper portion of the steam boiler 23, mixes with the steam generated by the steam boiler 23 itself, and then it is fed to the external pipeline network for use at the same level or for generating electric power. The gas inlet of the residual gas treatment device 17 is connected to the residual gas outlet of the economizer 24. The gas outlet of the residual gas treatment device 17 is connected to the gas inlet of the residual gas cleaning device 18. The gas outlet of the device 18 for cleaning residual gases is connected to the smoke pipe 20 through the smoke exhauster 19 for cleaning and discharging residual gases.

As shown in Fig. 3, the waste heat recovery device is a low-temperature hot water production module, which can be used to produce hot water for domestic use. The low-temperature hot water production module is connected to the cyclone separator 8 and recovers heat from the gas with a medium to high temperature and the high-temperature granulated slag 6 to produce low-temperature hot water with a temperature of 70°-95°C. The low-temperature hot water is supplied to the consumer for use at the same level or for cooling purposes. The outlet for residual gases of the steam boiler 23 in the low-temperature hot water production module is connected to the residual gas processing module.

The low-temperature hot water production module includes a slag bin 11, a residual gas treatment device 17, a residual gas cleaning device 18, a smoke exhauster 19, a smoke stack 20, a high-temperature feed conveyor 21, a heat exchanger 22 for high-temperature granulated slag and a steam boiler 23. The high-temperature feed conveyor 21 is located between the outlet opening of the cyclone separator 8 and the loading opening of the heat exchanger 22 for high-temperature granulated slag. The high-temperature granulated slag 6 separated by the cyclone separator 8 is transported by means of the high-temperature feed conveyor 21 into the upper part of the heat exchanger 22 for high-temperature granulated slag, and it slowly descends. A coil containing circulating water is provided in the heat exchanger 22 for high-temperature granulated slag. The high-temperature granulated slag 6 is subjected to reverse heat exchange with the coil and the gas flow rising from the bottom up, and is thus cooled to 200°C or lower. The slag hopper 11 is located under the outlet located at the bottom of the heat exchanger 22 for the high-temperature granulated slag. The cooled granulated slag is directed to the slag hopper 11 for subsequent processing. At the top of the heat exchanger 22 for high-temperature granulated slag, a gas hole is provided, connected to the steam boiler 23. One part of the clean water supplied from the external pipeline network is directed to the steam boiler 23 for heating to 70-95 °C, and the other part enters the coil of the heat exchanger 22 for high-temperature granulated slag to absorb the heat of the high-temperature granulated slag 6. After the water in the coil absorbs heat and thus is heated to a higher temperature, it enters the steam drum located at the top of the steam boiler 23, mixes with hot water generated by the steam boiler 23 itself, and then it is supplied to the external pipeline network for use as water for domestic needs or for cooling purposes. The gas inlet of the residual gas treatment device 17 is connected to the gas outlet of the steam boiler 23. The gas outlet of the residual gas treatment device 17 is connected to the gas inlet of the residual gas cleaning device 18. The gas outlet of the residual gas cleaning device 18 is connected to the smoke stack 20 via the smoke exhauster 19 for cleaning and releasing the residual gases.

In this case, the device 18 for cleaning residual gases may be a fabric bag or an electrostatic dust collector.

As shown in Fig. 1, the cyclone separator 8 is provided with a loading port, an outlet port and an aerosol port. The loading port of the cyclone separator 8 is connected to the outlet port 7 of the flow guide. The outlet port of the cyclone separator 8 is connected to the first loading port of the screw mixer 9, and the aerosol port of the cyclone separator 8 is connected to the aerosol port of the sludge pre-dryer 14 of the sludge pre-drying module. The high-temperature granulated slag 6 and the medium-temperature gas can be effectively separated by the cyclone separation.

As shown in Fig. 4, the method of granulating blast furnace slag and recycling waste heat includes the following steps:

stage 1: feeding blast furnace slag separated from molten iron into a slag trough, where a slag flow 1 is formed, which flows into a flow guide 7 after its flow is regulated by a slag flow regulator 2;

step 2: adjusting the compressed air flow control valve 3 and the water volume control valve 4 to form a high-pressure aerosol in the aerosol sprayer 5 and spraying the high-pressure aerosol through the nozzle, so that the high-pressure aerosol collides with the slag flow 1 entering the flow guide 7, to form a medium-temperature gas and a high-temperature granulated slag 6 with a pre-hardened surface;

stage 3: mixing and heat exchange of medium-temperature gas and high-temperature granulated slag 6 with a pre-hardened surface through a flow guide 7 to form fully hardened high-temperature granulated slag 6 and gas with a medium to high temperature, which are transported to a cyclone separator 8, in which separation of high-temperature granulated slag 6 and gas with a medium to high temperature occurs;

stage 4: transporting the gas with a medium to high temperature and the high-temperature granulated slag 6 to the waste heat recovery device from the cyclone separator 8, wherein the heat of the gas with a medium to high temperature and the high-temperature granulated slag 6 is recovered by means of the waste heat recovery device and used for drying the sludge, producing high-temperature steam, generating electricity or producing low-temperature hot water.

Sludge drying includes the following stages.

Stage 4.1.1: Pumping wet sludge from sludge tank 16 using sludge pump 15 into sludge pre-dryer 14.

Stage 4.1.2: Mixing and reverse heat exchange of wet sludge with medium to high temperature gas in sludge pre-dryer 14 to form semi-dry sludge.

In step 4.1.2, the wet residual gas formed by mixing the wet sludge with the medium and high temperature gas is purified in a residual gas treatment module and then released.

Stage 4.1.3: transporting semi-dry sludge from the sludge pre-drying module to the screw mixer 9 and transporting high-temperature granulated slag 6 from the cyclone separator 8 to the screw mixer 9, wherein the semi-dry sludge and high-temperature granulated slag 6 are mixed in the screw mixer 9 to form a mixture of slag and sludge.

Stage 4.1.4: transporting the slag and sludge mixture from the screw mixer 9 to the sludge dryer 10, wherein the sludge dryer 10 ensures drying of the slag and sludge mixture to obtain dry sludge powder and slag granules, which are transported to the slag and sludge extraction module.

At stage 4.1.4, the temperature of the slag granules is 200°C or lower.

In step 4.1.4, the wet residual gas generated during drying of the slag and sludge mixture in the sludge dryer 10 is purified in a residual gas treatment module and then released.

Stage 4.1.5: separation of dry sludge powder from slag granules in slag and sludge separator 13 of the slag and sludge extraction module.

At stage 4.1.5, the wet residual gas formed during the separation of the dry sludge powder and slag granules in the sludge separator 13 is purified in the residual gas treatment module and then released.

Stage 4.1.6: transporting dry sludge powder from sludge separator 13 to dry sludge powder bin 12 for temporary storage.

Stage 4.1.7: transporting slag granules from slag separator 13 to slag bunker 11 for temporary storage.

A method for cleaning and discharging wet residual gases using a residual gas processing module includes: collecting and pre-treating (such as cyclone processing for removing dust from large millimeter-sized particles) wet residual gases from a preliminary sludge dryer 14, a sludge dryer 10 and a slag and sludge separator 13 using a residual gas processing device 17 of the residual gas processing module, followed by deep cleaning in a residual gas cleaning device 18, wherein the residual gases purified to meet the standard are discharged through a smoke stack 20 by a smoke exhauster 19, and the fine powder collected in the residual gas processing device 17 and in the residual gas cleaning device 18 is extracted into an external bin.

The production of high-temperature steam includes the following stages.

Stage 4.2.1: transporting the high-temperature granulated slag 6 from the cyclone separator 8 to the conveyor 21 for high-temperature granulated slag, which lifts the high-temperature granulated slag 6 and uniformly feeds it into the heat exchanger 22 for high-temperature granulated slag through the upper inlet of the heat exchanger 22 for high-temperature granulated slag, wherein the high-temperature granulated slag 6 moves from top to bottom and in the process of descending it contacts and exchanges heat in a counter-current with the cooling water in the coil and the air rising from bottom to top.

Stage 4.2.2: discharging the heated high-temperature gas (300-600°C) from the upper part of the heat exchanger 22 for high-temperature granulated slag and directing it to the steam boiler 23, and discharging the cooled granulated slag from the lower part of the heat exchanger for high-temperature granulated slag into the slag bin 11. The temperature of the cooled slag is 200°C or lower.

Step 4.2.3: directing clean water from the external pipeline network to the economizer 24 for preheating to 80°C or higher with low to medium temperature residual gas (250°C or lower) discharged from the steam boiler 23, wherein one part of the heated clean water is directed to the steam boiler 23 for further heating and evaporation to produce high-temperature steam (200-250°C), and the other part enters the coil of the heat exchanger 22 for high-temperature granulated slag to absorb heat of the high-temperature granulated slag 6.

Stage 4.2.4: Feeding water from the coil to the steam drum at the top of the steam boiler 23 after it has been evaporated and heated to approximately 250°C, where it mixes with the steam generated in the steam boiler itself and is then fed into the external piping network for use at the same level or for power generation.

The production of low-temperature hot water includes the following stages.

Step 4.3.1: transporting the high-temperature granulated slag 6 from the cyclone separator 8 to the conveyor 21 for high-temperature granulated slag, which lifts the high-temperature granulated slag 6 and uniformly feeds it into the heat exchanger 22 for high-temperature granulated slag through the upper inlet of the heat exchanger 22 for high-temperature granulated slag, in which the high-temperature granulated slag 6 moves from top to bottom, and in the process of descending, it contacts and exchanges heat counter-currently with the cooling water in the coil and the air rising from bottom to top.

Step 4.3.2: discharging heated low-temperature hot water (70-95°C) from the top of the heat exchanger 22 for high-temperature granulated slag and directing it to the steam boiler 23, and discharging cooled granulated slag from the bottom of the heat exchanger for high-temperature granulated slag into the slag bin 11. The temperature of the cooled slag is 200°C or lower.

Stage 4.3.3: feeding one portion of clean water from the external pipeline network to the steam boiler 23 for heating to 70-95°C with gas of medium to high temperature (300-600°C) passing through the steam boiler 23, and directing the other portion to the coil of the heat exchanger 22 for high-temperature granulation of slag to absorb the heat of the high-temperature granulated slag 6.

Stage 4.3.4: directing water from the coil to the steam drum at the top of the steam boiler 23 after it has been heated by absorbing heat, whereby it is mixed with hot water generated in the steam boiler 23 itself, and then it is supplied to the external piping network for use as domestic water or for cooling purposes.

Example 1

As shown in Fig. 1, when tapped from the blast furnace, the blast furnace slag enters the main trough together with the molten pig iron from the taphole and is blocked by a slag gate. The slag, having a temperature of 1450-1550°C, is separated from the liquid pig iron and enters the slag trough. Then the slag enters the aerosol granulation nozzle module for granulation. In particular, the slag flow 1 flows out after its flow is adjusted by the slag flow regulator 2. After exiting the slag flow regulator 2, the slag flow 1 is blown through, granulated and pre-cooled with high-pressure aerosol sprayed from the aerosol atomizer 5 as it falls to form high-temperature granulated slag 6, having a temperature of 1000-1200°C, and medium-temperature gas, having a temperature of 200-400°C. The flow rate of the high-pressure aerosol is determined by the compressed air flow control valve 3 and the water volume control valve 4, and it is automatically adjusted within a certain range depending on the volume of the slag flow 1. The medium-temperature gas flow carrying away the granulated high-temperature granulated slag 6 is directed along the flow guide 7 into the heat recovery device. The medium-temperature gas and the high-temperature granulated slag 6 are then mixed and exchange heat when passing through the flow guide 7. The gas temperature rises to 300-500°C to form a gas with a medium to high temperature, and the temperature of the high-temperature granulated slag 6 drops to 900-1100°C. The high-temperature granulated slag 6 completely solidifies. The aerosol-based slag granulation technology combines the advantages of the slag granulation technology based on rapid gas cooling and the slag granulation technology based on rapid water cooling. Granulated slag with a high degree of vitrification preserves the resource nature of the slag rapidly cooled with water, and dry granulated slag reduces the cost of fine grinding and the environmental impact of transportation. High-temperature granulated slag and the medium-to-high temperature gas stream generated during the granulation process create favorable conditions for the recycling of thermal energy.

The gas with a medium to high temperature and the high-temperature granulated slag 6 are fed to the cyclone separator 8. The cyclone separator 8 has a highly efficient separation capability and can separate a large portion of the high-temperature granulated slag 6 from the gas with a medium to high temperature. The gas with a medium to high temperature is discharged from the upper portion of the rotary separator 8 and fed to the sludge pre-dryer 14, in which the reverse contact and heat exchange occur between the gas with a medium to high temperature and the wet sludge (converter sludge obtained by wet dedusting and having a water content of 60-90 mass %, i.e., OG sludge) pumped by the sludge pump 15. The water content in the sludge drops to about 50%, and the gas temperature drops to 200°C. The high-temperature granulated slag 6 with a temperature of 800-950°C collected by the cyclone separator 8 and the semi-dry sludge from the preliminary sludge dryer 14 are stirred and mixed by the screw mixer 9. The mixture of slag and sludge is fed directly to the sludge dryer 10. The slag and sludge are in contact and exchange heat directly in the sludge dryer 10. The mixing ratio of slag and sludge is 2:1-3:1. The sludge is dried to a specified moisture content (e.g. 6%). The temperature of the slag granules drops to 200°C or lower. After drying, the dry sludge powder and granulated slag are separated in the slag and sludge separator 13 and sent to temporary storage bunkers, namely, to the slag bunker 11 and the dry sludge powder bunker 12, awaiting transportation outside the enterprise for subsequent use of resources.

The temperature of the wet residual gas obtained in the preliminary sludge dryer 14, the sludge dryer 10 and the sludge and sludge separator 13 is maintained at 200°C or higher. The wet residual gas is subjected to cyclone treatment by means of the residual gas treatment device 17 to remove dust in the form of large millimeter-sized particles. The temperature of the residual gas drops to 150-200°C. After deep cleaning in the residual gas cleaning device 18 to remove at least 95% of various types of fine dust, the residual gas pressure is increased by the smoke exhauster 19 and is discharged through the smoke stack 20 to the standard. The residual gas cleaning device 18 can be a fabric bag or an electrostatic dust collector.

The fine powder collected by the residual gas treatment device 17 and the residual gas cleaning device 18 is regularly extracted into a tank and sent directly to the next unit for use.

Example 2

As shown in Fig. 2, when tapped from the blast furnace, the blast furnace slag enters the main trough together with the molten pig iron from the taphole and is blocked by a slag gate. The slag, having a temperature of 1450-1550°C, is separated from the liquid pig iron and enters the slag trough. Then the slag enters the aerosol granulation nozzle module for granulation. In particular, slag flow 1 flows out after its flow rate is adjusted by slag flow regulator 2. After exiting slag flow regulator 2, slag flow 1 is blown through, granulated and pre-cooled with high-pressure aerosol sprayed from aerosol atomizer 5 as it falls to form high-temperature granulated slag 6 having a temperature of 1000-1200°C and medium-temperature gas having a temperature of 200-400°C. The flow rate of the high-pressure aerosol is determined by the compressed air flow control valve 3 and the water volume control valve 4, and it is automatically adjusted within a certain range depending on the volume of the slag flow 1. The medium-temperature gas flow carrying away the granulated high-temperature granulated slag 6 is directed along the flow guide 7 into the heat recovery device. The medium-temperature gas and the high-temperature granulated slag 6 are then mixed and exchange heat when passing through the flow guide 7. The gas temperature rises to 300-500°C to form a gas with a medium to high temperature, and the temperature of the high-temperature granulated slag 6 drops to 800-1100°C. The high-temperature granulated slag 6 completely solidifies. The aerosol-based slag granulation technology combines the advantages of the slag granulation technology based on rapid gas cooling and the slag granulation technology based on rapid water cooling. Granulated slag with a high degree of vitrification preserves the resource nature of the slag rapidly cooled with water, and dry granulated slag reduces the cost of fine grinding and the environmental impact of transportation. High-temperature granulated slag and the medium-to-high temperature gas stream generated during the granulation process create favorable conditions for the recycling of thermal energy.

The gas with a medium to high temperature and the high-temperature granulated slag 6 are fed into the cyclone separator 8. The cyclone separator 8 has a highly efficient separation capability and can separate a large portion of the high-temperature granulated slag 6 from the gas with a medium to high temperature. The high-temperature granulated slag 6 with a temperature of 700-950°C separated from the cyclone separator 8 is transported to the upper portion of the heat exchanger 22 for high-temperature granulated slag via the high-temperature feed conveyor 21. The high-temperature granulated slag 6 slowly descends into the heat exchanger 22 for high-temperature granulated slag and, as it descends, undergoes reverse heat exchange with the water circulating in the coil and the gas stream rising from the lower portion. The high-temperature granulated slag is cooled to about 200°C and then directed to the slag hopper 11 located below. The rising gas stream is heated to 300-600°C, it is removed from the upper part of the heat exchanger 22 for high-temperature granulated slag, combined with the gas stream with a medium to high temperature exiting the cyclone separator 8, and then sent to the steam boiler 23.

The clean water supplied from the external pipeline network is first passed through the economizer 24 and preheated to a temperature of 80°C or higher by the residual gas with a medium to high temperature discharged from the steam boiler 23. After the clean water is degassed, one part of it is supplied to the steam boiler 23 for heating and evaporation by hot air with a temperature of 300-600°C to produce steam with a temperature of 200-250°C, and the other part enters the coil of the heat exchanger 22 for high-temperature granulated slag. This part of the water absorbs the heat of the high-temperature granulated slag 6 directly. After its temperature rises to about 250°C, it enters the steam drum at the upper part of the steam boiler 23, where it is mixed with the steam generated by the steam boiler itself, and then it is supplied to the external pipeline network for use at the same level or for generating electricity.

The temperature of the wet residual gas discharged from the economizer 24 is maintained at 200°C or higher. The wet residual gas is subjected to cyclone treatment using the residual gas treatment device 17 to remove dust in the form of large millimeter-sized particles. The temperature of the residual gas drops to 150-200°C. After deep cleaning in the residual gas cleaning device 18, the dust content is less than 10 mg. Finally, the residual gas pressure is increased by the smoke exhauster 19 and discharged through the smoke stack 20 to the standard.

A small amount of fine powder collected by the residual gas treatment device 17 and the residual gas cleaning device 18 is regularly extracted into a tank and sent directly to the next installation for use.

Example 3

As shown in Fig. 3, when tapped from the blast furnace, the blast furnace slag enters the main trough together with the molten pig iron from the taphole and is blocked by a slag gate. The slag, having a temperature of 1450-1550°C, is separated from the liquid pig iron and enters the slag trough. Then the slag enters the aerosol granulation nozzle module for granulation. In particular, slag flow 1 flows out after its flow rate is adjusted by slag flow regulator 2. After exiting slag flow regulator 2, slag flow 1 is blown out, granulated and pre-cooled by high-pressure aerosol sprayed from aerosol atomizer 5 as it falls to form high-temperature granulated slag 6, having a temperature of 1000-1200°C, and medium-temperature gas, having a temperature of 200-400°C. The flow rate of the high-pressure aerosol is determined by the compressed air flow control valve 3 and the water volume control valve 4, and it is automatically adjusted within a certain range depending on the volume of the slag flow 1. The medium-temperature gas flow carrying away the granulated high-temperature granulated slag 6 is directed along the flow guide 7 into the heat recovery device. The medium-temperature gas and the high-temperature granulated slag 6 are then mixed and exchange heat when passing through the flow guide 7. The gas temperature rises to 300-500°C to form a gas with a medium to high temperature, and the temperature of the high-temperature granulated slag 6 drops to 800-1100°C, and the high-temperature granulated slag 6 completely solidifies. The aerosol-based slag granulation technology combines the advantages of the slag granulation technology based on rapid gas cooling and the slag granulation technology based on rapid water cooling. Granulated slag with a high degree of vitrification preserves the resource nature of the slag rapidly cooled with water, and dry granulated slag reduces the cost of fine grinding and the environmental impact of transportation. High-temperature granulated slag and the medium-to-high temperature gas stream generated during the granulation process create favorable conditions for the recycling of thermal energy.

The gas with a medium to high temperature and the high-temperature granulated slag 6 are fed into the cyclone separator 8. The cyclone separator 8 has a highly efficient separation capability and can separate a large portion of the high-temperature granulated slag 6 from the gas with a medium to high temperature. The high-temperature granulated slag 6 with a temperature of 700-950°C separated from the cyclone separator 8 is transported to the upper portion of the heat exchanger 22 for high-temperature granulated slag via the high-temperature feed conveyor 21. The high-temperature granulated slag 6 slowly descends into the heat exchanger 22 for high-temperature granulated slag and, as it descends, undergoes reverse heat exchange with the water circulating in the coil and the gas stream rising from the lower portion. The high-temperature granulated slag is cooled to about 200°C and then directed to the slag hopper 11 located below. The rising gas stream is heated to 300-600°C, is discharged from the top of heat exchanger 22, is combined with a medium to high temperature gas stream discharged from cyclone separator 8, and is then sent to steam boiler 23.

One part of the clean water coming from the external pipeline network is sent to the steam boiler 23 for heating with hot air of 300-600°C to obtain hot water of 70-95°C, and the other part is sent to the heat exchange coil of the heat exchanger 22 for high-temperature granulated slag. This part of the water absorbs the heat of the high-temperature granulated slag 6 directly. After its temperature rises to about 70-95°C, it is sent to the upper part of the steam boiler 23, where it is mixed with hot water generated by the steam boiler itself, and then it is sent to the external pipeline network for use as domestic water or for cooling purposes.

The temperature of the residual gas leaving the steam boiler 23 is maintained at 200°C or higher. The wet residual gas is subjected to cyclone treatment using the residual gas treatment device 17 to remove dust in the form of large millimeter-sized particles. The temperature of the residual gas drops to 150-200°C. After deep cleaning in the residual gas cleaning device 18, the dust content is less than 10 mg. Finally, the residual gas pressure is increased by the smoke exhauster 19 and removed through the smoke stack 20 to the standard.

A small amount of fine powder collected by the residual gas treatment device 17 and the residual gas cleaning device 18 is regularly extracted into a tank and sent directly to the next unit for use.

The above description discloses only some preferred embodiments of the invention without the intention of limiting the scope of protection of the invention. Therefore, all changes, equivalents, modifications within the essence and principles of the invention are included in the scope of protection of the invention.

Claims (39)

1. A device for granulating blast furnace slag and recycling waste heat, which comprises an aerosol granulation nozzle module, a flow guide (7), a cyclone separator (8) and a waste heat recovery device; wherein the nozzle module of aerosol granulation comprises a slag flow regulator (2), a compressed air flow regulation valve (3), a water volume regulation valve (4) and an aerosol atomizer (5); wherein the slag flow regulator (2) is connected to the slag inlet of the flow guide (7); the compressed air flow regulation valve (3) is connected to the gas inlet of the aerosol atomizer (5); the water volume regulation valve (4) is connected to the liquid inlet of the aerosol atomizer (5); wherein the nozzle of the aerosol atomizer (5) is designed in such a way that it faces the inlet of the flow guide (7) in order to ensure the possibility of collision of the aerosol with the slag flow entering the flow guide (7) through the slag flow regulator (2), with the formation of gas having a temperature of 200-400°C, and granulated slag (6) having a pre-hardened surface, having a temperature of 1000-1200°C; in this case, the aerosol is formed by compressed air and water; where the flow guide (7) is designed for complete mixing of gas having a temperature of 200-400°C and granulated slag (6) having a pre-hardened surface, having a temperature of 1000-1200°C, in the flow guide with the formation of completely hardened granulated slag (6) having a temperature of 800-1100°C, and gas having a temperature of 300-500°C, wherein the outlet of the flow guide (7) is connected to the loading opening of the cyclone separator (8) to ensure the entry into the cyclone separator (8) of completely hardened granulated slag (6) having a temperature of 800-1100°C and gas having a temperature of 300-500°C, formed in the flow guide (7); where the cyclone separator (8) is designed to separate granulated slag (6) having a temperature of 800-1100°C and gas having a temperature of 300-500°C; where the outlet opening of the cyclone separator (8) is connected to the loading opening of the heat recovery device for feeding gas having a temperature of 350-550°C and fully solidified granulated slag (6) having a temperature of 700-950°C into the heat recovery device. 2. A device for granulating blast furnace slag and recycling waste heat according to claim 1, wherein the slag flow regulator (2) is designed to regulate the slag flow (1) and its entry into the slag inlet of the flow guide (7); the gas inlet of the aerosol sprayer (5) is designed to direct high-pressure gas through a compressed air flow control valve (3); the liquid inlet of the aerosol sprayer (5) is designed to direct water through a water volume control valve (4); wherein the nozzle of the aerosol sprayer (5) is configured to face the inlet of the flow guide (7) to ensure the possibility of a collision of the aerosol with the slag flow (1) to form a gas having a temperature of 200-400°C and granulated slag (6) having a pre-hardened surface, having a temperature of 1000-1200°C. 3. The device for granulating blast furnace slag and recycling waste heat according to claim 1, wherein the heat recovery device is a sludge drying module comprising a screw mixer (9), a sludge dryer (10), a sludge pre-drying module, a slag and sludge extraction module and a residual gas processing module; the outlet opening of the cyclone separator (8) is connected to the first loading opening of the screw mixer (9) for transporting fully solidified granulated slag (6) having a temperature of 700-950°C into the screw mixer (9); an aerosol opening of the cyclone separator (8) is connected to an aerosol opening of the sludge pre-drying module for transporting gas having a temperature of 350-550°C into the sludge pre-drying module, so that the gas having a temperature of 350-550°C is mixed with the wet sludge in the sludge pre-drying module to form a semi-dry sludge; an outlet opening of the sludge pre-drying module is connected to a second loading opening of the screw mixer (9) for transporting the semi-dry sludge into the screw mixer (9), so that the semi-dry sludge and granulated slag (6) having a temperature of 700-950°C are mixed in the screw mixer (9) to form a mixture of slag and sludge; the outlet of the screw mixer (9) is connected to the loading opening of the sludge dryer (10) for transporting the sludge and sludge mixture into the sludge dryer (10); the outlet of the sludge dryer (10) is connected to the loading opening of the sludge and sludge extraction module for transporting dry sludge powder and sludge granules into the sludge and sludge extraction module; the gas inlet of the residual gas treatment module is connected to the gas outlet of the sludge pre-drying module, the gas outlet of the sludge dryer (10) and the gas outlet of the sludge and sludge extraction module. 4. A device for granulating blast furnace slag and recycling waste heat according to claim 1, wherein the heat recovery device is a steam generation module that is connected to a cyclone separator (8) for recovering heat from gas having a temperature of 350-550°C and granulated slag (6) having a temperature of 700-950°C, producing steam having a temperature of 200-250°C; wherein the outlet for residual gas from the steam generation module is connected to a residual gas processing module. 5. A device for granulating blast furnace slag and recycling waste heat according to claim 4, wherein the steam generation module comprises a slag hopper (11), a device (17) for treating residual gases, a device (18) for cleaning gases, a smoke exhauster (19), a smoke stack (20), a feed conveyor (21), a heat exchanger (22) for granulated slag, a steam boiler (23) and an economizer (24); wherein the feed conveyor (21) is arranged between the outlet of the cyclone separator (8) and the loading opening of the heat exchanger (22) for granulated slag for transporting the granulated slag (6) having a temperature of 700-950°C, separated by the cyclone separator (8), to the upper part of the heat exchanger (22) for granulated slag; in the heat exchanger (22) for granulated slag, a coil containing circulating water is provided for reverse heat exchange of the granulated slag (6) having a temperature of 700-950°C with the coil and a gas flow rising from the bottom up; a slag hopper (11) is arranged under the outlet located at the lower part of the heat exchanger (22) for granulated slag, for receiving the granulated slag after cooling; the upper part of the heat exchanger (22) for granulated slag is provided with a gas opening connected to a steam boiler (23); the economizer (24) is connected to the steam boiler (23) and the heat exchanger (22) for granulated slag respectively, so that the water supplied to the economizer (24) through the external pipeline network is preheated to 80°C or higher by the residual gas discharged from the steam boiler (23), and is divided into two parts, one part is sent to the steam boiler (23), and the other part enters the coil of the heat exchanger (22) for granulated slag to absorb the heat of the granulated slag (6) having a temperature of 700-950°C; wherein the gas inlet of the device (17) for treating residual gases is connected to the residual gas outlet of the economizer (24), the gas outlet of the device (17) for treating residual gases is connected to the gas inlet of the device (18) for cleaning residual gases, and the gas outlet of the device (18) for cleaning residual gases is connected to the smoke pipe (20) through the smoke exhauster (19) for cleaning and removing residual gases. 6. A device for granulating blast furnace slag and recycling waste heat according to claim 5, in which the steam drum in the upper part of the steam boiler (23) is designed to receive water when it evaporates in the coil and its temperature rises to 250°C, and the steam drum in the upper part of the steam boiler (23) is designed to mix water with steam generated by the steam boiler (23) itself and feed it into an external pipeline network. 7. A device for granulating blast furnace slag and recycling waste heat according to claim 1, wherein the heat recovery device is a hot water production module that is connected to a cyclone separator (8) for recovering heat from gas having a temperature of 350-550°C and granulated slag (6) having a temperature of 700-950°C, to obtain hot water having a temperature of 70-95°C; wherein the outlet for the residual gas of the hot water production module is connected to the residual gas processing module. 8. A device for granulating blast furnace slag and recycling waste heat according to claim 7, wherein the hot water production module includes a slag hopper (11), a device (17) for treating residual gases, a device (18) for cleaning gases, a smoke exhauster (19), a smoke stack (20), a feed conveyor (21), a heat exchanger (22) for granulated slag and a steam boiler (24); wherein the feed conveyor (21) is arranged between the outlet of the cyclone separator (8) and the loading opening of the heat exchanger (22) for granulated slag for transporting the granulated slag (6) having a temperature of 700-950°C, separated by the cyclone separator (8), to the upper part of the heat exchanger (22) for granulated slag; in the heat exchanger (22) for granulated slag, a coil containing circulating water is provided for reverse heat exchange of the granulated slag having a temperature of 700-950°C with the coil and a gas flow rising from the bottom up; a slag hopper (11) is arranged under the outlet located in the lower part of the heat exchanger (22) for granulated slag, for receiving the granulated slag after cooling; the upper part of the heat exchanger (22) for granulated slag is provided with a gas opening connected to a steam boiler (23); the steam boiler (23) and the heat exchanger (22) for granulated slag are connected to an external pipeline network, respectively, for receiving water for heat exchange in the steam boiler (23) and the heat exchanger (22) for granulated slag; the gas inlet of the device (17) for treating residual gases is connected to the outlet for residual gases of the steam boiler (23), the gas outlet of the device (17) for treating residual gases is connected to the gas inlet of the device (18) for cleaning residual gases, and the gas outlet of the device (18) for cleaning residual gases is connected to the smoke stack (20) through a smoke exhauster (19) for cleaning and removing residual gases. 9. The device for granulating blast furnace slag and recycling waste heat according to claim 3, wherein the residual gas processing module includes a device (17) for processing residual gases, a device (18) for cleaning residual gases, a smoke exhauster (19) and a smoke stack (20), wherein the gas inlet of the device (17) for processing residual gases is connected to the gas outlet of the sludge pre-drying module, the gas outlet of the sludge dryer (10) and the gas outlet of the slag and sludge extraction module through pipelines, respectively, wherein the gas outlet of the device (17) for processing residual gases is connected to the gas inlet of the device (18) for cleaning residual gases, and the gas outlet of the device (18) for cleaning residual gases is connected to the smoke stack (20) through the smoke exhauster (19). 10. A method for granulating blast furnace slag and recycling waste heat using a device for granulating blast furnace slag and recycling waste heat according to claim 1, comprising the following stages: stage 1: feeding the blast furnace slag separated from the molten iron into the slag trough, where a slag flow (1) is formed and flows into a flow guide (7) after its flow is regulated by a slag flow regulator (2); stage 2: adjusting the compressed air flow control valve (3) and the water volume control valve (4) to form a high-pressure aerosol in the aerosol sprayer (5) and spraying the high-pressure aerosol through the nozzle so that the high-pressure aerosol collides with the slag flow (1) entering the flow guide (7), to form a gas having a temperature of 200-400°C and granulated slag (6) with a pre-hardened surface having a temperature of 1000-1200°C; stage 3: mixing and heat exchange of gas having a temperature of 200-400°C and granulated slag (6) with a pre-hardened surface having a temperature of 1000-1200°C through a flow guide (7) with the formation of fully hardened granulated slag having a temperature of 800-1100°C and gas having a temperature of 300-500°C, which are transported to a cyclone separator (8), in which separation of granulated slag having a temperature of 800-1100°C and gas having a temperature of 300-500°C occurs; stage 4: transporting gas having a temperature of 350-550°C and granulated slag (6) having a temperature of 700-950°C to a waste heat recovery device from a cyclone separator (8), wherein the heat of the gas having a temperature of 350-550°C and granulated slag (6) having a temperature of 700-950°C is recovered using a waste heat recovery device. 11. A method for granulating and recycling waste heat using a device for granulating blast furnace slag and recycling waste heat according to claim 10, in which the heat of the gas having a temperature of 350-550°C and the granulated slag having a temperature of 700-950°C, recovered using the waste heat recovery device, is used to dry the sludge, produce steam having a temperature of 200-250°C, generate electricity or produce hot water having a temperature of 70-95°C. 12. A method for granulating and recycling waste heat using a device for granulating blast furnace slag and recycling waste heat according to claim 10, wherein the sludge drying step comprises: stage 4.1.1: pumping wet sludge from the sludge tank (16) using the sludge pump (15) into the sludge pre-dryer (14); stage 4.1.2: mixing and reverse heat exchange of wet sludge with gas having a temperature of 350-550°C in a preliminary sludge dryer (14) to form a semi-dry sludge; stage 4.1.3: transporting semi-dry sludge from the sludge pre-drying module to the screw mixer (9) and transporting granulated slag (6) having a temperature of 700-950°C from the cyclone separator (8) to the screw mixer (9), wherein the semi-dry sludge and granulated slag (6) having a temperature of 700-950°C are mixed in the screw mixer (9) to form a mixture of slag and sludge; stage 4.1.4: transporting the slag and sludge mixture from the screw mixer (9) to the sludge dryer (10), wherein the sludge dryer (10) ensures drying of the slag and sludge mixture to obtain dry sludge powder and slag granules, which are transported to the slag and sludge extraction module; stage 4.1.5: separation of dry sludge powder from slag granules in the slag and sludge separator (13) of the slag and sludge extraction module; stage 4.1.6: transporting dry sludge powder from the sludge separator (13) to the dry sludge powder bin (12) for temporary storage; stage 4.1.7: transporting slag granules from the slag separator (13) to the slag bin (11) for temporary storage; wherein the method further comprises cleaning and discharging the wet residual gas using a residual gas processing module, including: collecting and pre-treating the wet residual gas from the sludge pre-dryer (14), the sludge dryer (10) and the slag and sludge separator (13) using a residual gas processing device (17) of the residual gas processing module, followed by deep cleaning in a residual gas cleaning device (18), wherein the residual gas purified to meet the standard is discharged through a smoke stack (20) by a smoke exhauster (19), and the fine powder collected in the residual gas processing device (17) and in the residual gas cleaning device (18) is extracted into an external tank. 13. A method for granulating and recycling waste heat using a device for granulating blast furnace slag and recycling waste heat according to claim 10, wherein the step of producing steam comprises: stage 4.2.1: transporting granulated slag (6) having a temperature of 700-950°C from the cyclone separator (8) to the conveyor (21) for granulated slag, which lifts the granulated slag (6) having a temperature of 700-950°C and feeds it into the heat exchanger (22) for granulated slag through the upper inlet of the heat exchanger (22) for granulated slag, wherein the granulated slag (6) having a temperature of 700-950°C moves from top to bottom, and in the process of descending it contacts and exchanges heat in a counter-current with the cooling water in the coil and the air rising from bottom to top; stage 4.2.2: discharging heated steam from the upper part of the heat exchanger (22) for granulated slag and directing it into the steam boiler (23), and discharging cooled granulated slag from the lower part of the heat exchanger for granulated slag into the slag hopper (11); stage 4.2.3: directing water from the external pipeline network to the economizer (24) for preheating to 80°C or higher with residual gas released from the steam boiler (23), with one part of the water being directed to the steam boiler (23) for further heating and evaporation to produce steam having a temperature of 200-250°C, and the other part being fed to the coil of the heat exchanger (22) for granulated slag to absorb the heat of the granulated slag (6) having a temperature of 700-950°C; stage 4.2.4: feeding water from the coil into the steam drum at the top of the steam boiler (23) after it has evaporated and heated to 250°C, where it mixes with the steam generated in the steam boiler itself (23) and then enters the external piping network. 14. A method for granulating and recycling waste heat using a device for granulating blast furnace slag and recycling waste heat according to claim 10, wherein the step of obtaining hot water includes: stage 4.3.1: transporting granulated slag (6) having a temperature of 700-950°C from the cyclone separator (8) to the conveyor (21) for granulated slag, which lifts the granulated slag (6) having a temperature of 700-950°C and feeds it into the heat exchanger (22) for granulated slag through the upper inlet of the heat exchanger (22) for granulated slag, in which the granulated slag (6) having a temperature of 700-950°C moves from top to bottom, and in the process of descending it contacts and exchanges heat in a counter-current with the cooling water in the coil and the air rising from bottom to top; stage 4.3.2: discharging heated hot water with a temperature of 70-95°C from the top of the heat exchanger (22) for granulated slag and directing it into the steam boiler (23) and discharging cooled granulated slag from the bottom of the heat exchanger (6) for granulated slag into the slag hopper (11); stage 4.3.3: feeding one part of the water from the external pipeline network into the steam boiler (23) for heating to 70-95°C by gas passing through the steam boiler, and feeding the other part into the coil of the heat exchanger (22) for granulating the slag to absorb the heat of the granulated slag (6), having a temperature of 700-950°C; stage 4.3.4: feeding water from the coil to the steam drum at the top of the steam boiler (23) after it has been heated by heat absorption, mixing it with the hot water generated in the steam boiler (23) itself, and then feeding it to the external piping network.

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