System for waste heat recovery and dust removal in blast furnace tapping process

Abstract

The invention discloses a system for waste heat recovery and dust removal in the blast furnace tapping process, which comprises a dust collection cover arranged above a blast furnace tapping hole, an ejector, a condenser, a heat exchanger and a flash tank, and dust-containing steam is collected through the dust collection cover in the blast furnace tapping process and is introduced into the ejector as secondary flow. The high-pressure steam as a primary flow also enters the ejector and provides a secondary flow force. And the mixed dust-containing steam is cooled and condensed by cooling water in the condenser, then is introduced into the flash tank, and is evaporated together with the slag flushing water under low pressure. One part of the generated steam is used for external steam supply or heat supply, and the other part of the generated steam is compressed by a compressor to serve as primary flow of an ejector. Therefore, external steam does not need to be introduced, and the use amount of the steam is saved.

Description

Technical Field

[0001] The invention relates to the field of heat recovery of blast furnace tapping, in particular to a waste heat recovery and dust removal system for a blast furnace tapping process. Background Art

[0002] The energy consumption of blast furnace ironmaking process in my country is high, which is the main source of energy consumption in the steel industry. In recent years, steel enterprises have gradually attached importance to the recycling of high-temperature waste heat and carried out a large number of energy-saving and consumption-reducing technical transformations. However, a large amount of low-quality energy has not been recycled, and this part of energy is discharged into the environment, resulting in energy waste. At present, most domestic steel mills use water quenching slag process as blast furnace iron-making process. The granulated slag water mixture is sent to the slag yard after dehydration and filtration. The dehydrated water enters the hot water pool, producing a large amount of slag-washing hot water with a temperature of about 70°C to 85°C. In addition, a large amount of water is also vaporized during the slag-washing process. These steams have low temperatures, unorganized emissions, and contain dust particles, which brings problems to their recycling. At present, the mainstream way of utilizing the waste heat of blast furnace slag-washing water is to directly use the sensible heat of slag-washing water for winter heating. For example, the invention publication number CN103184299B proposes a method and device for recovering heat energy from slag-washing water in a steel plant, and a steam channel for slag-washing water is set between the slag-washing water heat emitter and the circulating water heat absorber. The steam of the slag flushing water enters the circulating water heat absorber to heat the circulating water for heating. For another example, the invention publication number CN200910097366.4 proposes a method and system for recovering waste heat from blast furnace slag flushing water, including a blast furnace slag flushing system, a sedimentation tank, a cyclone separator, a water pump, a heat exchanger, a steam turbine, a generator, a working fluid condenser, and a working fluid pump. A double-circulation low-temperature hot water power generation system is used to recover the waste heat of blast furnace slag flushing water for power generation. Although the above scheme realizes the heat recovery and utilization of blast furnace slag flushing water, it does not recover the unorganized discharged steam in time. The steam discharged in large quantities during the iron-making process contains latent heat of vaporization. Recycling it can not only reduce the overall energy consumption of blast furnace iron-making, but also realize the dust removal in the workshop, which has significant economic and environmental benefits. Summary of the invention

[0003] The object of the present invention is to solve the above-mentioned problems and to provide a waste heat recovery and dust removal system for the blast furnace iron-tapping process, which can simultaneously realize the waste heat recovery of dusty steam and slag-washing waste water in the blast furnace iron-tapping process and remove the dust generated in the iron-tapping process.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A system for waste heat recovery and coordinated dust removal in a blast furnace tapping process, comprising a dust hood, an ejector, a condenser, a heat exchanger, and a flash tank arranged above the blast furnace tapping port, the dust hood being connected to the secondary flow inlet of the ejector, the water outlet of the ejector being connected to the condenser, the condenser being connected to the water inlet of the flash tank through a pipeline, the high-temperature slag flushing water generated in the blast furnace tapping process entering the heat exchanger, the heat exchanger being connected to the water inlet of the flash tank through a pipeline, and the flash tank being connected to the primary flow inlet of the ejector through a reflux pipeline.

[0006] Furthermore, a vacuum pump is provided at the outlet of the flash tank where it is connected to the reflux pipeline.

[0007] Furthermore, a compressor is provided on the return pipe.

[0008] Furthermore, a membrane filtration device is provided on the water outlet at the lower end of the flash tank.

[0009] Furthermore, a water pump is provided on the water inlet pipe of the heat exchanger.

[0010] The beneficial effects of the present invention are:

[0011] 1. The present invention collects dusty steam through a dust collecting hood during the blast furnace iron-tapping process and introduces it into the ejector as a secondary flow. High-pressure steam also enters the ejector as a primary flow and provides secondary flow power. The mixed dusty steam is cooled and condensed by cooling water in the condenser, and then introduced into the flash tank to evaporate at low pressure together with the slag flushing water. Part of the generated steam is used for external steam supply or heating, and the other part is compressed by a compressor and used as the primary flow of the ejector. In this way, there is no need to introduce external steam, saving steam usage.

[0012] 2. In the present invention, the high-temperature slag flushing water and cooling water are heat-exchanged in the heat exchanger and then enter the flash tank. The cooling water passes through the heat exchanger and condenser in turn, and finally serves as water supply for the heat network. The system achieves dust removal effect on the basis of recycling the heat of steam and slag flushing water generated in the iron-making process, and can replace bag dust collectors, with the integrated advantages of purifying the workshop environment and heat recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 It is a schematic diagram of the present invention.

[0015] In the figure: dust collecting hood 1, ejector 2, condenser 3, water pump 4, heat exchanger 5, flash tank 6, reflux pipe 7, vacuum pump 8, compressor 9, membrane filtration device 10. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0017] like Figure 1 As shown, a system for waste heat recovery and coordinated dust removal in a blast furnace tapping process includes a dust collecting hood 1, an ejector 2, a condenser 3, a heat exchanger 5, and a flash tank 6 arranged above the blast furnace tapping port, the dust collecting hood 1 is connected to the secondary flow inlet of the ejector 2, the water outlet of the ejector 2 is connected to the condenser 3, the condenser 3 is connected to the water inlet of the flash tank 6 through a pipeline, the high-temperature slag flushing water generated in the blast furnace tapping process enters the heat exchanger 5, the heat exchanger 5 is connected to the water inlet of the flash tank 6 through a pipeline, and the flash tank 6 is connected to the primary flow inlet of the ejector 2 through a reflux pipe 7.

[0018] The dust collecting hood 1 is arranged above the iron outlet of the blast furnace, and covers the dust-containing steam generated during the iron outlet of the blast furnace; a steam pipe is arranged on the top of the dust collecting hood, which is connected to the secondary inlet of the ejector 2.

[0019] The primary inlet medium of the ejector 2 is compressed steam. The compressed steam and the dust-containing steam are mixed in the ejector 2 and then discharged from the ejector outlet to the condenser.

[0020] The dusty mixed steam at the outlet of the ejector 2 exchanges heat with cooling water in the condenser 3 , and the cooling water condenses the dusty mixed steam to form dusty waste water, which enters the flash tank 6 .

[0021] The high-temperature slag flushing water generated during the blast furnace iron-making process enters the heat exchanger 5 through the slag flushing water pump 4, exchanges heat with the cooling water, and then enters the flash tank 6 to mix with the dust-containing wastewater.

[0022] Low pressure conditions are formed in the flash tank to promote evaporation of wastewater; part of the steam formed by evaporation is drawn out for steam supply or heating, and the other part enters the ejector 2 as a primary flow high-pressure steam through the reflux pipe 7 to eject the dust-containing steam formed in the iron-making process.

[0023] The ejector is a device that uses a high-speed, high-energy flow (liquid flow, air flow or other material flow) to eject another low-speed, low-energy flow. The jet flows through a contracting nozzle into a mixing chamber surrounded by the ejected flow. Through the mixing effect of the boundary, the ejected flow transfers energy to the ejected flow.

[0024] Flash evaporation is when high-pressure saturated water enters a relatively low-pressure container and the sudden drop in pressure causes the saturated water to become saturated water vapor and saturated water under part of the container pressure.

[0025] During the iron-making process of the blast furnace, dusty steam is collected by the dust collecting hood and introduced into the ejector as a secondary flow. High-pressure steam also enters the ejector as a primary flow and provides secondary flow power. The mixed dusty steam is cooled and condensed by cooling water in the condenser, and then introduced into the flash tank to evaporate at low pressure together with the slag flushing water. Part of the generated steam is used for external steam supply or heating, and the other part is compressed by the compressor and used as the primary flow of the ejector. In this way, there is no need to introduce external steam, saving steam usage.

[0026] The high-temperature slag flushing water and cooling water are heat-exchanged in the heat exchanger and then enter the flash tank. The cooling water passes through the heat exchanger and condenser in turn, and finally serves as water supply for the heat network. The system achieves dust removal effect on the basis of recycling the heat of steam and slag flushing water generated in the iron-making process. It can replace bag dust collectors and has the integrated advantages of purifying the workshop environment and heat recovery.

[0027] A vacuum pump 8 is provided at the outlet of the flash tank 6 where it is connected to the reflux pipe 7. Under the action of the vacuum pump, a low-pressure condition is formed in the flash tank to promote evaporation of wastewater.

[0028] The return pipe 7 is provided with a compressor 9. Part of the steam formed by evaporation in the flash tank is led out for steam supply or heating, and the other part enters the ejector 2 as a primary flow high-pressure steam through the compressor 9 for ejecting the dust-containing steam formed in the iron-making process.

[0029] A membrane filtration device 10 is provided at the water outlet at the lower end of the flash tank 6. After multiple evaporations, high-concentration dust-containing wastewater at the bottom of the flash tank 6 is drawn out, and pollutants such as dust are intercepted by the membrane filtration device 10. The obtained clean water can be reused as slag flushing water in the iron making process.

[0030] A water pump 4 is provided on the water inlet pipe of the heat exchanger 5 .

[0031] The high-pressure steam as the primary flow has a temperature of 80°C and a pressure of 200kPa. The dust-containing steam at the connection with the dust hood is the secondary flow, with a temperature of 50°C and a pressure of 50kPa. The two streams of steam are mixed in the ejector, and the temperature of the dust-containing steam at the ejector outlet is 75°C and the pressure is 120kPa. This part of steam exchanges heat with cooling water in the condenser, and the steam condenses into dust-containing wastewater at a temperature of 60°C. The cooling water temperature is raised from 50°C to 73°C and used as water supply for the heating network.

[0032] At the same time, the 60℃ slag flushing water is introduced into the heat exchanger through the water pump. In the heat exchanger, the cooling water is heated from 25℃ to 50℃, and the slag flushing water is cooled from 60℃ to 55℃. The slag flushing water and dust-containing wastewater are evaporated at low pressure in the flash tank. Under the action of the vacuum pump, the flash pressure is 75kPa, and the steam temperature at the flash tank outlet is 58℃. Part of the steam at the flash tank outlet can be used directly for heating or to heat the cooling water. The remaining steam is adiabatically compressed by the compressor and heated to 80℃, and the pressure is increased from 75kPa to 200kPa, which serves as the high-temperature and high-pressure steam of the ejector primary flow.

[0033] The wastewater concentrate at the bottom of the flash tank is discharged and filtered through a membrane filter device, solid particles are intercepted, and clean water is recycled for secondary circulation.

[0034] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "left", "right", "up", "down", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection, it can be a direct connection, it can be an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A waste heat recovery and dust removal system for blast furnace iron-making process, characterized in that: The invention comprises a dust collecting hood (1), an ejector (2), a condenser (3), a heat exchanger (5), and a flash tank (6) arranged above the blast furnace tapping port. The dust collecting hood (1) is connected to the secondary flow inlet of the ejector (2), the water outlet of the ejector (2) is connected to the condenser (3), the condenser (3) is connected to the water inlet of the flash tank (6) through a pipeline, the high-temperature slag flushing water generated during the blast furnace tapping process enters the heat exchanger (5), the heat exchanger (5) is connected to the water inlet of the flash tank (6) through a pipeline, and the flash tank (6) is connected to the primary flow inlet of the ejector (2) through a reflux pipeline (7).

2. A system for waste heat recovery and dust removal in a blast furnace iron-making process as claimed in claim 1, characterized in that: A vacuum pump (8) is provided at the outlet of the flash tank (6) where it is connected to the reflux pipe (7).

3. The system for waste heat recovery and dust removal in the blast furnace iron-making process according to claim 1, characterized in that: The return pipe (7) is provided with a compressor (9).

4. A system for waste heat recovery and dust removal in a blast furnace iron-making process as claimed in claim 1, characterized in that: A membrane filtering device (10) is provided on the water outlet at the lower end of the flash tank (6).

5. The system for waste heat recovery and dust removal in the blast furnace iron-making process according to claim 1, characterized in that: A water pump (4) is provided on the water inlet pipe of the heat exchanger (5).

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