A waste heat boiler for recycling high-temperature flue gas from steelmaking electric furnace

Abstract

The utility model discloses a waste heat boiler for recycling high-temperature flue gas from a steelmaking electric furnace, including a boiler flue gas pipeline, wherein a medium-pressure system and a low-pressure system are sequentially distributed along the flue gas pipeline in the boiler flue gas pipeline, wherein the medium-pressure system includes a vaporization flue, a water-cooling channel, a plurality of medium-pressure evaporators and a medium-pressure drum distributed in sequence, wherein the plurality of medium-pressure evaporators are connected to the medium-pressure drum, and the low-pressure system includes a plurality of low-pressure evaporators, a low-pressure drum and an outlet flue, wherein the plurality of low-pressure evaporators are connected to the low-pressure drum, and the low-pressure evaporator is arranged behind the medium-pressure evaporator in the boiler flue gas pipeline. The utility model adopts a dual-pressure system consisting of a medium-pressure system and a low-pressure system, which effectively realizes the step-by-step utilization of the heat of the waste heat flue gas and improves the efficiency of waste heat recovery; the utility model adopts a four-channel membrane water-cooled wall structure to realize an efficient heat exchange system and ensure the stability of heat exchange of the boiler system.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat recovery of high-temperature flue gas from steel plant electric furnaces, in particular to a waste heat boiler for recovering high-temperature flue gas from steelmaking electric furnaces using scrap steel and molten iron as raw materials. Background Art

[0002] As an environmentally friendly method for recycling scrap steel, iron filings, and scrap rebar, electric furnace mini-process steelmaking has been gaining increasing importance in my country's steel industry. It is projected that electric furnaces will account for 30% of production capacity by 2030. As the proportion of electric furnace steelmaking gradually increases, the smelting of scrap steel and hot metal has become the mainstream technology in steel mills. This increase in the proportion of hot metal increases the temperature and volume of flue gas during steelmaking. The high temperature flue gas can cause corrosion, wear, and heat exchange problems in the waste heat boilers at the back end of the process, which require the attention of the steel industry.

[0003] To address these issues, researchers in this field have researched waste heat boilers (WHRBs) for recovering high-temperature flue gas from electric furnace steelmaking. For example, Chinese Patent Publication No. CN212618206U discloses an EHRB that utilizes a multi-stage evaporator, economizer, and membrane water-cooled walls within a horizontal boiler to recover waste heat from flue gas below 850°C generated during steelmaking. However, this technical solution fails to address the corrosion, wear, and heat exchange issues associated with recovering high-temperature flue gas with a periodically fluctuating temperature exceeding 1100°C. Utility Model Content

[0004] In order to solve the above technical problems, the utility model designs a waste heat boiler for recovering and utilizing high-temperature flue gas from a steelmaking electric furnace, which effectively solves the problems of waste heat recovery, corrosion and wear of high-temperature electric furnace flue gas.

[0005] The utility model adopts the following technical solutions:

[0006] A waste heat boiler for recovering high-temperature flue gas from a steelmaking electric furnace comprises a boiler flue gas duct, wherein a medium-pressure system and a low-pressure system are sequentially distributed along the flue gas duct, wherein the medium-pressure system comprises a vaporization flue, a water-cooling channel, a plurality of medium-pressure evaporators and a medium-pressure steam drum which are sequentially distributed, wherein the plurality of medium-pressure evaporators are connected to the medium-pressure steam drum, and the low-pressure system comprises a plurality of low-pressure evaporators, a low-pressure steam drum and an outlet flue, wherein the plurality of low-pressure evaporators are connected to the low-pressure steam drum, and the low-pressure evaporator is arranged behind the medium-pressure evaporator in the boiler flue gas duct.

[0007] Preferably, the water-cooling channel and the boiler flue gas pipe at the bottom of the medium-pressure evaporator are respectively provided with a water-cooled ash hopper, and the boiler flue gas pipe at the bottom of the low-pressure evaporator is respectively provided with an insulated ash hopper.

[0008] Preferably, the water volume of the medium-pressure steam drum is not less than 1.1 times the maximum evaporation capacity of the boiler, and a deaerator is provided on the low-pressure steam drum.

[0009] Preferably, a water-cooled wall is provided outside the water-cooling channel, and the water-cooled wall adopts a four-channel structure, including a water-cooling channel I, a water-cooling channel II, a water-cooling channel III and a membrane water-cooling flue.

[0010] Preferably, the water-cooled wall is installed in the boiler flue gas duct through a plurality of hanging water-cooled walls.

[0011] Preferably, a soot blowing device is arranged in the boiler flue gas duct, and the soot blowing device includes a vibrating soot blowing device and a pulse soot blowing device. The vibrating soot blowing device is arranged on the water-cooled wall outside the multiple water-cooling channels, and the pulse soot blowing device is arranged in front of the heating surface of each medium-pressure evaporator and low-pressure evaporator.

[0012] Preferably, the multiple medium-pressure evaporators include medium-pressure evaporator I, medium-pressure evaporator II, medium-pressure evaporator III and medium-pressure evaporator IV, and the multiple low-pressure evaporators include low-pressure evaporator I, low-pressure evaporator II, low-pressure evaporator III and low-pressure evaporator IV. The medium and low-pressure evaporators are arranged vertically, and the flue gas flows horizontally and vertically flushes the heating surface of the evaporator.

[0013] Preferably, the medium-pressure evaporator and the low-pressure evaporator respectively adopt upper and lower headers and a modular structure, four groups of tube sheets form a module, and an anti-wear device is arranged in the first row on the windward side of each evaporator.

[0014] Preferably, a boiler inlet expansion joint is provided at the inlet of the boiler flue gas duct, and is integrally formed by thermal insulation cotton, lightweight castable, refractory castable and asbestos rope.

[0015] Preferably, the headers on the water-cooled wall are evenly distributed with hanging points, and are suspended on the top beam of the steel frame of the boiler flue gas duct through a hanger device.

[0016] The beneficial effects of the present invention are as follows: (1) the present invention adopts a dual-pressure system consisting of a medium-pressure system and a low-pressure system, which effectively realizes the step-by-step utilization of the heat of the waste heat flue gas and improves the efficiency of waste heat recovery; (2) the present invention adopts a four-channel membrane water-cooled wall structure, which effectively recovers the periodically changing high-temperature flue gas with a temperature greater than 1100°C, realizes an efficient heat exchange system, and ensures the stability of the heat exchange of the boiler system; (3) the present invention adopts a combination of mechanical vibration cleaning and pulse soot blowing to timely and effectively clean the accumulated dust on the water-cooled wall and evaporator, avoids the deposition of flue gas fly ash, and effectively reduces the corrosion and wear of the boiler; (4) the present invention adopts a special sealing and absorbing expansion structure at the inlet of the waste heat boiler, which effectively avoids high-temperature corrosion, ensures sealing, and is conducive to the safe and effective recovery of heat energy by the boiler; (5) the utility model adopts a suspension form as a whole, and is suspended on the top of the steel frame through the uniform force of the header on the water-cooled wall. The waste heat boiler expands downward as a whole, and a sway-stop device is provided to ensure the overall stability of the boiler structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the utility model;

[0018] Figure 2 This is a structural diagram of the evaporator in the utility model;

[0019] Figure 3 This is a structural diagram of the anti-wear device in the utility model;

[0020] Figure 4 It is a schematic diagram of the seal of the inlet expansion joint in the utility model;

[0021] Figure 5 It is a schematic diagram of the hanging structure in the utility model;

[0022] In the figure: 001 - medium-pressure system; 002 - low-pressure system; 1 - vaporization flue; 2 - water-cooling channel I; 3 - water-cooling channel II; 4 - water-cooling channel III; 5 - medium-pressure evaporator I; 6 - medium-pressure evaporator II; 7 - medium-pressure evaporator III; 8 - medium-pressure evaporator IV; 9 - low-pressure evaporator I; 10 - low-pressure evaporator II; 11 - low-pressure evaporator III; 12 - low-pressure evaporator IV; 13 - outlet flue; 14 - medium-pressure steam drum; 15 - low-pressure steam drum; 16 - suspension device; 17 - water-cooled ash hopper I; 18 - water-cooled ash hopper II; 19 - water-cooled ash hopper III; 20-Water-cooled ash hopper IV; 21-Water-cooled ash hopper V; 22-Insulated ash hopper I; 23-Insulated ash hopper II; 24-Insulated ash hopper III; 25-Insulated ash hopper IV; 26-Rapping device; 27-Pulse sootblowing; 28-Suspended water-cooled wall I; 29-Suspended water-cooled wall II; 30-Anti-wear device; 31-Boiler inlet expansion joint; 32-Thermal insulation cotton; 33-Lightweight castable; 34-Refractory castable; 35-Asbestos rope; 36-Membrane water-cooled flue. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0024] Example: Figure 1 As shown, a waste heat boiler for recovering high-temperature flue gas from a steelmaking electric furnace includes a medium-pressure system 001 and a low-pressure system 002. The medium-pressure system 001 includes a vaporization flue 1, a water-cooling channel I2, a water-cooling channel II3, a water-cooling channel III4, a medium-pressure evaporator I5, a medium-pressure evaporator II6, a medium-pressure evaporator III7, a medium-pressure evaporator IV8, a medium-pressure steam drum 14, a boom device 16, a water-cooled ash hopper I17, a water-cooled ash hopper II18, a water-cooled ash hopper III19, a water-cooled ash hopper IV20, a water-cooled ash hopper V21, a rapping device 26, a pulse sootblower 27, a hanging water-cooled wall I28, a hanging water-cooled wall II29, an anti-wear device 30, a boiler inlet expansion joint 31, thermal insulation cotton 32, a lightweight castable 33, a refractory castable 34, and an asbestos rope 35. Low-pressure system 002 includes low-pressure evaporators I9, II10, III11, IV12, outlet flue 13, low-pressure steam drum 15, adiabatic ash hoppers I22, II23, III24, and IV25. The waste heat boiler utilizes a dual-pressure system, consisting of a medium-pressure system and a low-pressure system. This achieves cascaded utilization of waste heat flue gas and improves heat recovery efficiency.

[0025] The waste heat boiler adopts a dual-pressure system, which utilizes the waste heat of the flue gas in a cascade manner and is equipped with two steam drums, including a medium-pressure steam drum 14 and a low-pressure steam drum 15; the water volume of the medium-pressure steam drum is not less than 1.1 times the maximum evaporation capacity of the boiler, and a deaerator is installed on the low-pressure steam drum.

[0026] The water-cooled wall adopts a four-channel structure, including water-cooling channel I2, water-cooling channel II3, water-cooling channel III4, hanging water-cooled wall I28, hanging water-cooled wall II29, and membrane water-cooled flue 36.

[0027] The evaporators include medium-pressure evaporator I5, medium-pressure evaporator II6, medium-pressure evaporator III7, medium-pressure evaporator IV8, medium-pressure evaporator I9, low-pressure evaporator II10, low-pressure evaporator III11, and low-pressure evaporator IV12.

[0028] The sootblowing system combines a vibrating and pulsed sootblowing system. A vibrating device 26 is installed on the water-cooled walls of the first three channels to remove accumulated soot. A pulsed sootblower 27 is installed in front of each evaporator's heating surface to remove accumulated soot from the hot surfaces of the intermediate-pressure and low-pressure evaporators. Adjustments to the quantity of both sootblower systems fall within the scope of this patent.

[0029] A four-stage evaporator is arranged in the medium-pressure evaporation system, and a four-stage evaporator is arranged in the low-pressure system. Both the medium- and low-pressure evaporators are arranged vertically, and the flue gas flows horizontally and vertically flushes the heating surface of the evaporator.

[0030] like Figure 2-Figure 3 As shown, the evaporator adopts a modular structure with upper and lower headers, and four groups of tube segments form a module, which is convenient for manufacturing and on-site assembly. Anti-wear devices 30 are arranged in the first row on the windward side of the evaporator to reduce the impact of fly ash in the flue gas and the soot blowing device on the heating surface tubes, effectively reducing wear. Figure 4 As shown, a boiler inlet expansion joint 31 is set at the inlet of the boiler flue gas pipe, and is integrally formed by thermal insulation cotton 32, lightweight castable 33, refractory castable 34 and asbestos rope 35 to ensure sealing and prevent high temperature corrosion of the expansion joint by flue gas. Figure 5 As shown, the water-cooled wall adopts a distributed suspension structure, with the boiler load evenly suspended from the top beam of the steel frame. The waste heat boiler adopts an overall suspension structure, suspended from the top beam of the steel frame by a hanger assembly 16 through evenly distributed suspension points on the header of the water-cooled wall, ensuring stable and uniform load distribution on the boiler.

[0031] According to the different flue gas temperatures in the horizontal flue part, water-cooled ash hoppers and insulated ash hoppers are set. Water-cooled ash hopper I17, water-cooled ash hopper II18, water-cooled ash hopper III19, water-cooled ash hopper IV20 and water-cooled ash hopper V21 are respectively set at the lower parts of the water-cooled flue, medium-pressure evaporator I5, medium-pressure evaporator II6, medium-pressure evaporator III7 and medium-pressure evaporator IV8; insulated ash hopper I22, insulated ash hopper II23, insulated ash hopper III24 and insulated ash hopper IV25 are respectively set at the lower parts of the low-pressure evaporator I9, low-pressure evaporator II10, low-pressure evaporator III11 and low-pressure evaporator IV12.

[0032] The utility model proposes a waste heat boiler for recycling high-temperature flue gas from a steelmaking electric furnace. The overall design is horizontal, natural circulation, outdoor layout, and dual-pressure structure. The safe operating range of the waste heat boiler is 50-110%. The boiler mainly consists of a membrane water-cooled wall arranged at the front flue gas inlet, a medium-pressure evaporator in the middle, and a low-pressure evaporator at the rear. After the high-temperature electric furnace flue gas at 1100°C passes through the vaporization flue, it first enters the settling chamber. Most of the fly ash is separated by gravity in the settling chamber and falls into the ash hopper at the bottom. The settling chamber is a membrane water-cooled wall structure that can perform preliminary cooling on the flue gas, while reducing the temperature of the outer surface of the flue and reducing heat loss. The flue gas separated and cooled in the settling chamber flushes four groups of medium-pressure evaporators and four groups of low-pressure evaporators in turn, and is discharged from the furnace body after heat exchange and cooling to about 200°C. The desalted water enters the deaerator on the top of the low-pressure drum for deoxygenation through the deaerator water pump. The 143℃ deoxygenated water is sent to the medium-pressure drum by the feed water pump and evaporates naturally in the convection tube bundle (evaporator). The steam-water mixture produced is separated by the steam-water separation function of the device inside the boiler drum, and is led out through the saturated steam outlet pipe and sent to the plant steam network.

[0033] The embodiment described above is only a preferred solution of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A waste heat boiler for recycling high-temperature flue gas from a steelmaking electric furnace, comprising a boiler flue gas pipeline, characterized in that: A medium-pressure system and a low-pressure system are sequentially distributed along the flue gas duct of the boiler. The medium-pressure system includes a vaporization flue, a water-cooling channel, a plurality of medium-pressure evaporators and a medium-pressure steam drum that are sequentially distributed, and the plurality of medium-pressure evaporators are connected to the medium-pressure steam drum. The low-pressure system includes a plurality of low-pressure evaporators, a low-pressure steam drum and an outlet flue. The plurality of low-pressure evaporators are connected to the low-pressure steam drum, and the low-pressure evaporator is arranged behind the medium-pressure evaporator in the flue gas duct of the boiler.

2. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 1 is characterized in that: The water-cooling channel and the boiler flue gas pipeline at the bottom of the medium-pressure evaporator are respectively provided with water-cooled ash hoppers, and the boiler flue gas pipeline at the bottom of the low-pressure evaporator is respectively provided with insulated ash hoppers.

3. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 1 is characterized in that: The water volume of the medium-pressure steam drum is not less than 1.1 times of the maximum evaporation capacity of the boiler, and a deaerator is provided on the low-pressure steam drum.

4. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 1 is characterized in that: A water-cooled wall is arranged outside the water-cooled channel, and the water-cooled wall adopts a four-channel structure, including a water-cooled channel I, a water-cooled channel II, a water-cooled channel III and a membrane-type water-cooled flue.

5. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 4 is characterized in that: The water-cooled wall is installed in the boiler flue gas duct through a plurality of hanging water-cooled walls.

6. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 4 is characterized in that: A soot blowing device is arranged in the boiler flue gas duct, and the soot blowing device includes a vibration soot blowing device and a pulse soot blowing device. The vibration soot blowing device is arranged on the water-cooled wall outside the multiple water-cooled channels, and the pulse soot blowing device is arranged in front of the heating surface of each medium-pressure evaporator and low-pressure evaporator.

7. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 1 is characterized in that: The multiple medium-pressure evaporators include medium-pressure evaporator I, medium-pressure evaporator II, medium-pressure evaporator III and medium-pressure evaporator IV, and the multiple low-pressure evaporators include low-pressure evaporator I, low-pressure evaporator II, low-pressure evaporator III and low-pressure evaporator IV. The medium and low-pressure evaporators are arranged vertically, and the flue gas flows horizontally to vertically flush the heating surface of the evaporator.

8. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 1 is characterized in that: The medium-pressure evaporator and the low-pressure evaporator respectively adopt upper and lower headers and a modular structure, four groups of tube sheets form a module, and an anti-wear device is arranged in the first row on the windward side of each evaporator.

9. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 1 is characterized in that: A boiler inlet expansion joint is arranged at the inlet of the boiler flue gas duct.

10. The waste heat boiler for recovering high temperature flue gas from a steelmaking electric furnace according to claim 4, characterized in that: The header on the water-cooled wall is evenly provided with hanging points, and is suspended on the top beam of the steel frame of the boiler flue gas duct through a hanging rod device.

Images