CN111595166A - An efficient recovery system of waste heat from flue gas of AOD furnace - Google Patents

Abstract

The invention discloses an efficient recovery system for flue gas waste heat of an AOD furnace. A flue gas waste heat recovery pipeline and a steam waste heat recovery pipeline are arranged. The high temperature flue gas generated by the AOD furnace and the vaporization flue exchange heat to generate high temperature saturated steam and cooling smoke The cooling flue gas is recycled through the waste heat recovery pipeline of the flue gas, and the high-temperature saturated steam is recovered by the waste heat recovery pipeline of the steam. The technical scheme of the present invention prolongs the life of the boiler, improves the heat exchange efficiency, and finally improves the waste heat recovery rate of the whole process by reducing the dust content of the flue gas entering the boiler, while avoiding the influence of the flue gas temperature reciprocating change on the boiler heat exchange tube.

Description

An efficient recovery system of waste heat from flue gas of AOD furnace

technical field

The invention belongs to the field of flue gas waste heat recovery equipment, and in particular relates to an AOD furnace flue gas waste heat efficient recovery system.

Background technique

AOD furnace is a process device for smelting stainless steel, and its production process is similar to that of converter, both of which are intermittent. Due to the needs of the smelting process, the decarburization rate of the AOD furnace is much slower than that of the converter, resulting in a longer smelting cycle (the smelting cycle of the 120t AOD furnace is 100min, and the converter is 30min), and the temperature and composition of the flue gas produced are larger than those of the converter. The flue gas temperature of the AOD furnace is as high as 1600 °C at the furnace mouth, but with the extension of the smelting time, the decarburization rate gradually decreases, and the flue gas temperature at the furnace mouth will drop to 100 °C. Therefore, the "quality" of the waste heat of the AOD furnace flue gas is much worse than the sensible heat of the converter gas. At present, some companies have partially recovered the waste heat of flue gas from AOD furnaces, and a few companies have still recovered a small amount of waste heat symbolically. How to reduce the energy loss in the flue gas waste heat recovery process and improve the waste heat recovery rate is of great significance to the energy conservation and emission reduction of enterprises.

The existing recovery process firstly passes the high temperature dust-laden flue gas of the AOD furnace through the vaporization flue under negative pressure, and the temperature drops to ~850°C, and at the same time produces ~2.5MPa saturated steam (primary high-pressure saturated steam), and the cooled flue gas then enters For waste heat boilers, the flue gas temperature will drop to ~200℃, and the saturated steam of ~2.5MPa (secondary high-pressure saturated steam) will be generated again; the flue gas is discharged from the boiler and enters the pulse cloth bag for filtering and purification, and then enters the induced draft fan, and the flue gas pressure It becomes positive pressure and is finally discharged into the atmosphere through the chimney; the primary and secondary high-pressure saturated steam generated in the whole smelting process each correspond to one steam drum, and the high-pressure saturated steam drawn from the two steam drums enters the heat accumulator, and the heat accumulator will The intermittent primary and secondary high-pressure saturated steam is converted into continuous low-pressure saturated steam (~1.2MPa); the low-pressure saturated steam will enter the steam turbine as the main steam to drive the generator to generate electricity, and finally realize the waste heat power generation from the high-temperature flue gas of the AOD furnace.

The existing recovery process first converts the sensible heat of the flue gas into the enthalpy of saturated steam and then into electrical energy. The electrical energy is transported to the designated substation through the cable, and then sent to the electricity facilities after secondary distribution. In this process, from waste heat recovery to secondary utilization of electric energy, it involves the loss of multiple transmission and conversion of electric energy, and the recovery efficiency is low.

The high-temperature dust-laden flue gas enters the boiler directly after passing through the vaporization flue, which has a great impact on the life of the boiler heat exchange tube. In order to prolong the life of the heat exchange tube, the flue gas flow rate is greatly restricted, and the boiler volume is designed to be larger. However, when the flow rate is too low, the smoke and dust will adhere to the surface of the heat exchange tube, which will affect the heat exchange effect and ultimately reduce the waste heat recovery rate of the flue gas. At the same time, internal ash removal facilities should be considered, which will eventually lead to an increase in investment and the actual use effect is not ideal.

Since the flue gas parameters of the AOD furnace change drastically, when the flue gas volume is large and the temperature is high, a large amount of saturated steam will be generated. When the flue gas volume is small and the temperature is low, no steam will be generated. The existing process relies on the heat accumulator to iron. The peaks and troughs of the steam are generated to produce continuous main steam. However, due to the complex production process of the AOD furnace and the instantaneous change of flue gas, it is difficult to obtain the appropriate type of regenerator through thermal calculation. In actual production, the regenerator is often too small, resulting in a large amount of steam being released during the peak of steam production; at the same time, the flue gas The reciprocating temperature change reduces the life of the boiler heat exchange tube and is not conducive to improving the waste heat recovery rate.

SUMMARY OF THE INVENTION

Aiming at the defects and deficiencies in the prior art, the present invention provides an efficient recovery system for waste heat of AOD furnace flue gas, which avoids the loss of electric energy transmission and conversion in the existing recovery process and improves the recovery rate of waste heat;

In order to achieve the above-mentioned purpose, the technical scheme adopted by the present invention includes:

An efficient recovery system for flue gas waste heat of an AOD furnace, which is provided with a flue gas waste heat recovery pipeline and a steam waste heat recovery pipeline;

The high-temperature flue gas generated by the AOD furnace exchanges heat with the vaporization flue to generate high-temperature saturated steam and cooling flue gas; the cooling flue gas passes through the flue gas waste heat recovery pipeline for waste heat recovery, and the high-temperature saturated steam passes through the steam waste heat recovery pipeline for waste heat recovery;

At least a dust removal device and a heat storage device are sequentially connected to the flue gas waste heat recovery pipeline;

The dedusting device is provided with a dedusting furnace body, a buffer smoke exhaust chamber is semi-embedded at the top of the dedusting furnace body, and an oxygen supply pipeline is connected to the outside of the middle of the dedusting furnace body; The outer diameter gradually increases away from the top of the dust removal furnace;

The heat storage device is provided with at least a heat storage furnace body, and a plurality of heat storage sections are sequentially stacked in the heat storage furnace body at least along the axial direction; heat storage bricks are arranged in the heat storage section, and the heat storage bricks are arranged in the axial direction. Blocks with through-holes; high-temperature flue gas is input from the top of the regenerative furnace body, and then discharged from the bottom of the regenerative furnace body after being stored in multiple regenerative sections; After the heat is stored in the hot section, it is discharged from the top of the heat-storage furnace body.

Optionally, a cavity tube is provided in the buffer smoke exhaust chamber, and a buffer smoke exhaust pipe is arranged in communication with the cavity tube; the buffer smoke exhaust pipe is a pipe body structure with an increasing outer diameter; the height of the buffer smoke exhaust pipe is the height of the furnace body. 1/3 to 3/4 times the height; the outer diameter of the buffer smoke exhaust pipe ranges from 1.5 to 2.5 m; the depth of the buffer smoke exhaust cavity embedded in the furnace body is 1 to 2 m.

Optionally, the buffer smoke exhaust chamber and the dust removal furnace body form an annular gap, and the volume of the annular gap is 80-90 m ³ .

Optionally, the oxygen supply pipeline includes an oxygen supply main pipe and a plurality of oxygen supply branch pipes; the oxygen supply branch pipes are connected in the circumferential direction and are arranged around the outside of the dust removal furnace; the dust removal furnace body is arranged in order along the axial direction. , a buffer combustion section and a sedimentation ash discharge section; the buffer smoke exhaust cavity is embedded along the smoke inlet section and the buffer combustion section; the oxygen supply pipeline is arranged outside the buffer combustion section;

The smoke inlet section has a conical cavity structure, and a smoke inlet pipe is communicated with the smoke inlet section; a smoke exhaust pipe is arranged in communication with the top of the buffer smoke exhaust chamber, and a CO detector is arranged on the smoke exhaust pipe;

The sedimentation ash discharge section has a conical cavity structure, an ash discharge valve is arranged at the bottom of the sedimentation ash discharge section, and an inspection port is arranged on the side wall of the sedimentation ash discharge section.

Optionally, the plurality of thermal storage sections include at least a first thermal storage section, a second thermal storage section and a third thermal storage section; according to the thermal storage temperature, the first thermal storage section and the second thermal storage section are The heat storage temperature or heat storage coefficient of the third heat storage section decreases in turn; the heat storage brick is a polygonal block with holes in cross section, the aperture is 20-25mm, and the number of holes is 7-9.

Optionally, a flue gas diversion section is further arranged under the plurality of heat storage sections; the flue gas diversion section is composed of a plurality of hollow plates;

A refractory support section is also arranged under the flue gas guide section, and the refractory support section is supported by a plurality of evenly distributed pillars; the refractory support section is connected with the outside of the regenerative furnace and is provided with a third thermal insulation pipe and a fourth Insulation pipeline; a third valve is arranged on the third insulation pipeline, and a fourth valve is arranged on the fourth insulation pipeline.

Optionally, a flue gas splitting section is further arranged on the thermal storage furnace body before the plurality of thermal storage sections, and the flue gas splitting section has a cylindrical cavity structure; the flue gas splitting section is communicated with the outside of the thermal storage furnace. A first thermal insulation pipeline and a second thermal insulation pipeline are arranged; a first valve is arranged on the first thermal insulation pipeline, and a second valve is arranged on the second thermal insulation pipeline; a flue gas buffer is also arranged on the regenerative furnace body before the flue gas splitting section The flue gas buffer section is a conical closing structure.

Optionally, the flue gas waste heat recovery pipeline includes an adiabatic flue, a dust removal device, a regenerative furnace, a waste heat boiler, a bag filter, an induced draft fan and a chimney that are connected in sequence.

Optionally, the steam waste heat recovery pipeline includes a steam pipeline, a first steam drum, a steam heat accumulator, a steam turbine, a clutch and a generator that are communicated in sequence; the generator is the smoke of the flue gas waste heat recovery pipeline. Air exhaust power supply.

Optionally, the steam generated by the steam waste heat recovery pipeline is converted into electrical energy, and the electricity is used to supply power for the exhaust of the flue gas from the flue gas waste heat recovery pipeline.

The technical scheme of the present invention prolongs the life of the boiler, improves the heat exchange efficiency, and finally improves the waste heat recovery rate of the whole process by reducing the dust content of the flue gas entering the boiler, while avoiding the influence of the flue gas temperature reciprocating change on the boiler heat exchange tube.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification, and together with the following detailed description, are used to explain the present disclosure, but not to limit the present disclosure. In the attached image:

Fig. 1 is AOD furnace flue gas waste heat efficient recovery system structure schematic diagram of the present invention;

Fig. 2 is the structure schematic diagram of the dust removal device of the present invention;

Fig. 3 is the structure diagram of the heat storage device of the present invention;

Fig. 4 is a schematic diagram of the structure of the heat storage brick in Fig. 3;

The symbols in the figure are indicated as: 1- vaporization flue, 2- adiabatic flue, 3- dust removal device, 4- heat storage device, 5- waste heat boiler, 6- bag filter, 7- induced draft fan, 8- chimney, 9-steam pipeline, 10-first steam drum, 11-second steam drum, 12-steam heat accumulator, 13-steam turbine, 14-clutch, 15-generator, 16-frequency converter;

31-buffer smoke exhaust chamber, 311-buffer smoke exhaust pipe, 32-dust removal furnace body, 321-smoke inlet section, 322-buffer combustion section, 323-settling slag discharge section, 3231-maintenance port, 33-oxygen supply main pipe, 331-oxygen supply branch pipe, 34-smoke inlet pipe, 35-smoke exhaust pipe, 351-CO detector; 3a-oxygen supply main valve, 3b-oxygen supply branch pipe valve, 3c-ash discharge valve.

41- flue gas buffer section, 42- flue gas diversion section, 43- first heat storage section, 44- second heat storage section, 45- third heat storage section, 46- flue gas guide section, 47- refractory material Support section, 471-pillar; 4a-first valve, 4b-second valve, 4c-third valve, 4d-fourth valve, 4e-first insulated pipe, 4f-second insulated pipe, 4g-third insulated Pipes, 4h-4th insulated pipe.

Detailed ways

The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, but not to limit the present disclosure.

The "axial" mentioned in this disclosure refers to the axial direction where the intermediate shaft assembly or the two-shaft assembly is located, and the "upper", "lower", "left" and "right" mentioned in this disclosure are all The orientation in the picture shall prevail, "top", "bottom" and "side" are the top in the picture, "bottom" is "bottom", and the periphery is "side". Unless otherwise specified, the above The provisions apply to all content of this disclosure.

In the smelting process of AOD furnace, first furnace gas is generated in the furnace, and the furnace gas starts to burn after surface of the molten steel, until the furnace mouth still contains a large amount of CO. Since the furnace mouth is semi-open, a large amount of air is mixed with the furnace gas. After encountering, violent combustion occurs, producing high-temperature dust-laden flue gas.

With reference to Figure 1, the AOD furnace flue gas waste heat efficient recovery system of the present invention is provided with a flue gas waste heat recovery pipeline and a steam waste heat recovery pipeline; the high temperature flue gas generated by the AOD furnace and the vaporization flue heat exchange to generate high temperature saturated steam and cooling Flue gas; cooling flue gas is used for waste heat recovery through the flue gas waste heat recovery pipeline, and high-temperature saturated steam is used for waste heat recovery through the steam waste heat recovery pipeline; at least a dust removal device and a heat storage device are connected to the flue gas waste heat recovery pipeline in sequence; dust removal device A dust removal furnace body 32 is provided, a buffer smoke exhaust chamber 31 is half embedded in the top of the dust removal furnace body 32, and an oxygen supply pipeline is connected outside the middle of the dust removal furnace body 32; the outer diameter of the buffer smoke exhaust chamber 31 is away from the top of the furnace body along the outer diameter. The heat storage device is provided with at least a heat storage furnace body, and a plurality of heat storage sections are stacked in sequence in the heat storage furnace body at least along the axial direction; the heat storage section is provided with heat storage bricks, and the heat storage bricks are provided with through holes along the axial direction. The high temperature flue gas is input from the top of the regenerative furnace body, and then discharged from the bottom of the regenerative furnace body after being stored in multiple regenerative sections; After being heated, it is discharged from the top of the regenerative furnace body.

Specifically, the flue gas waste heat recovery pipeline includes an adiabatic flue 2 , a dust removal device 3 , a heat storage device 4 , a waste heat boiler 5 , a bag filter 6 , an induced draft fan 7 and a chimney 8 .

Specifically, the steam waste heat recovery pipeline includes a steam pipeline 9, a first steam drum 10, a steam heat accumulator 12, a steam turbine 13, a clutch 14 and a generator 15 connected in sequence; Air exhaust power supply. For another example, a second steam drum 12 is also connected to the waste heat boiler 5, and the steam of the second steam drum 12 and the steam of the first steam drum 11 are combined and supplied to the steam heat accumulator 12, and the generator can also be controlled by the frequency converter 16. 15 of the power generation efficiency, and then control the working speed of the induced draft fan 7.

The overall working process is summarized as follows: the steam generated by the steam waste heat recovery pipeline is converted into electric energy, and the electricity is used to supply power for the flue gas discharge of the flue gas waste heat recovery pipeline. The specific process is as follows: the high-temperature dust-laden flue gas first enters the vaporization flue 1 and exchanges heat with it. The temperature of the flue gas drops to ~850°C, and a small amount of soot is deposited in the vaporization flue; the cooled flue gas passes through the adiabatic flue. The flue 2 enters the primary dust removal device 3, and the flue gas after coarse dust removal enters the regenerative furnace 4 (with regenerative lattice bricks inside, which absorbs excess heat when the flue gas temperature is high, and the surplus heat is absorbed when the flue gas temperature is low. The heat is transferred to the low-temperature flue gas, thereby reducing the flue gas temperature fluctuation, and at the same time, it has a certain effect of purifying the flue gas and dust), and then enters the waste heat boiler 5 to exchange heat with the boiler, and the flue gas temperature drops to ~ 200 ℃; then enter the pulse The bag filter 6 is used for secondary dust removal, and the low-dust flue gas is finally sent to the chimney 8 through the induced draft fan 7 and discharged into the atmosphere.

The 2.5MPa saturated steam generated when the high-temperature flue gas exchanges heat with the vaporizing flue (intermittently generated with the flue gas changes) enters the first steam drum 10 through the steam pipe 9, and the flue gas that has been cooled once enters the waste heat boiler and heat exchange occurs again , the saturated steam of 2.5MPa (intermittently generated with the change of flue gas) enters the second steam drum 11, and the steam discharged from the first steam drum 10 and the second steam drum 11 enters the steam accumulator 12, and is converted into a continuous 1.2MPa steam Saturated steam, the low-pressure saturated steam enters the steam turbine 13 as the main steam, thereby driving the large-scale electricity-consuming facility in this process - the dust removal fan 7 . The steam turbine 13, the clutch 14, the motor generator 15, and the dust removal fan 7 are coaxial. In the present invention, the motor generator 15 (to generate power from the surplus after the main steam is driven by the dust removal fan) is equipped with a frequency converter 16 (to meet the requirements of the dust removal fan). Air volume adjustment function).

Referring to FIG. 2 , the dust removal device of the present disclosure is provided with a dust removal furnace body 32 , a buffer smoke exhaust chamber 31 is semi-embedded at the top of the dust removal furnace body 32 , and an oxygen supply pipeline is connected outside the middle of the dust removal furnace body 32 ; The outer diameter of the cavity 31 gradually increases away from the top of the dedusting furnace body 32 . The device of the present disclosure removes most of the smoke and dust in the flue gas of the semi-hermetic nickel-iron ore arc furnace, burns out the residual CO in the flue gas at the same time, avoids the blockage of the flue gas pipeline, and saves the dedusting and ash cleaning facilities of the subsequent heat exchange equipment. Reduce one-time investment; the structure of the device (inner and outer sleeve type); a multi-layer compressed air ring pipe is set in the straight section of the outer sleeve, and several branch pipes are inserted into the straight section in the circumferential direction to mix air; each layer of the ring pipe is provided with an electric regulating valve , Dynamically adjust and adjust the amount of mixed air according to the flue gas temperature and CO content, and set up an adjustable air mixing device to ensure that the CO in the flue gas burns out, and at the same time avoid mixing excess air to reduce the flue gas temperature, so as to improve the waste heat recovery rate of the flue gas.

In the embodiment of the present disclosure, the buffer smoke exhaust chamber 31 is provided with a cavity tube, and the buffer smoke exhaust pipe 311 is arranged in communication with the cavity tube; the buffer smoke exhaust pipe 311 is a pipe body structure with an increasing outer diameter. The structure of the buffer smoke exhaust pipe 311 ensures that the flue gas flow rate gradually increases on the premise that there is sufficient flue gas operating space.

In the embodiment of the present disclosure, the height of the buffer smoke exhaust pipe 311 is 1/3 to 3/4 times the height of the dust removal furnace body 32. For example, when the height of the conventional dust removal furnace body 32 is 4 m, the buffer smoke exhaust pipe 311 The height can be 1.3 ~ 3m. The height of the buffer smoke exhaust pipe 311 is set to ensure that the flue gas can sink to the bottom to settle the smoke and dust, and at the same time ensure that the flue gas flow rate gradually increases and is discharged from the top smoke exhaust pipe 35 to achieve efficient and fast treatment.

In the embodiment of the present disclosure, the outer diameter of the buffer smoke exhaust pipe 311 ranges from 1.5 to 2.5 m, preferably 2 to 2.5 m, and gradually increases in a tapered shape. The outer diameter is at least half of the outer diameter of the dust removal furnace body 32, so as to ensure that the flue gas has enough operating space after entering, and the smoke and dust are discharged before being discharged.

In the embodiment of the present disclosure, the depth of the buffer smoke exhaust chamber 31 embedded in the dust removal furnace body 32 is 1-2 m, preferably 1.5 m, that is to say, the buffer smoke exhaust chamber 31 is embedded into the dust removal furnace body 32 to a depth of at least 1 to 2 m. The height of the furnace body is 1/2 to 3/4 times, so as to ensure that the buffer smoke exhaust chamber 31 and the dust removal furnace body 32 form a sufficient annular gap, and at the same time, it can also have a sufficient height to discharge the flue gas.

In the embodiment of the present disclosure, the buffer smoke exhaust chamber 31 and the dust removal furnace body 32 form an annular gap, and the volume of the annular gap is 80-90 m ³ , preferably 85 m ³ , which is convenient for the flue gas to stay in the device for a sufficient time, which is conducive to the smoke and dust settlement.

In the embodiment of the present disclosure, the oxygen supply pipeline includes an oxygen supply main pipe 33 and a plurality of oxygen supply branch pipes 331; The air is evenly distributed along the radial direction of the device to ensure that the participating CO is fully burned.

In the embodiment of the present disclosure, the dust removal furnace body 32 is provided with a smoke inlet section 321 , a buffer combustion section 322 and a sedimentation ash discharge section 323 in sequence along the axial direction; the buffer smoke exhaust chamber 31 is embedded along the smoke inlet section 321 and the buffer combustion section 322 ; The oxygen supply pipeline is arranged outside the buffer combustion section 322. The oxygen supply main pipe 33 and the oxygen supply branch pipe 331 are provided with an oxygen supply main pipe valve 3a and an oxygen supply branch pipe valve 3b. The valves can be electric butterfly valves. To control the combustion degree of CO, it is necessary to ensure that CO is burnt out, and at the same time, too much low-temperature air cannot be introduced, so as not to affect the subsequent recovery of waste heat from flue gas, and to achieve a balance between dust removal and waste heat recovery from flue gas.

In the embodiment of the present disclosure, the smoke inlet section 321 has a conical cavity structure, and the smoke inlet pipe 34 is arranged in communication with the smoke inlet section 321, preferably in lateral communication; The smoke pipe 35 is also preferably arranged in the lateral direction, and a CO detector 51 is arranged on the smoke exhaust pipe 35 to detect whether the CO is completely burned, so as to adjust the oxygen supply.

In the embodiment of the present disclosure, the sedimentation ash discharge section 323 has a conical cavity structure, and an ash discharge valve 3c is arranged at the bottom of the sedimentation ash discharge section 323 ; In the case of the device running for a long time or multiple times, if the sedimentation ash discharge section 323 is blocked, it can be cleaned by manual entry.

In the production process of semi-closed nickel-iron ore furnace, first furnace gas is generated in the furnace, and the furnace gas still contains a large amount of CO when it reaches the furnace mouth. Violent combustion produces high temperature dusty flue gas (temperature: 700～900℃, dusty～35g/NM3). The high-temperature dust-laden flue gas enters the anti-adhesion device of the present disclosure through the flue gas inlet pipe 34 . When the flue gas passes through the device at a low speed (2m/s), the smoke and dust in it are fully settled in the gap between the inner and outer sleeves due to inertia, and the residual CO is fully burnt out (the oxygen supply pipeline is mixed with an appropriate amount of compressed air). The flue gas continues to enter the buffer flue gas exhaust chamber 31 and leaves the device, and is finally sent to the subsequent heat exchange equipment through the flue gas exhaust pipe 35 to complete the recovery of the waste heat of the flue gas.

Fig. 2 shows that the anti-adhesion device of the present disclosure is a sleeve-type structure, and the inner cylinder is in the shape of a "trumpet" mouth (the material is Q235-B), that is, the buffer smoke exhaust chamber 31, and the inner and outer sides are provided with thermal insulation spray paint; The sleeve is the dust removal furnace body 32, which is divided into an upper cone section, a straight section and a lower cone section, followed by a smoke inlet section 321, a buffer combustion section 322 and a sedimentation ash discharge section 323. The straight section of the sleeve is provided with two layers of oxygen supply branch pipes 331 (the number of ring pipes can be increased according to the size of the device, and an electric butterfly valve is provided at the entrance section of each layer of the ring pipe to adjust the amount of mixed air), and the circumferential direction of the ring pipe is arranged. There are several branch pipes inserted into the straight section; the lower cone end of the outer cylinder is provided with an ash discharge pipe, and the ash accumulation in the cone section is regularly discharged through the ash discharge valve c, and an inspection port 231 is provided in the cone section. The opening of the oxygen supply branch pipe valve b (electric butterfly valve) on each layer of oxygen supply branch pipe 331 is adjusted according to the temperature and the parameters fed back by the CO detector 51 to ensure that CO is burnt out while avoiding excess air and reducing the flue gas temperature.

Take a 33MW semi-hermetic nickel-iron ore furnace as an example. The daily nickel discount is 230t/d. If it is blocked once a month, it will take 10 hours to clean up once a time, 6 labors are required each time, and one crane shift is required to clean the pipeline once. The cost is: 1000 (per ton of ferronickel profit) * 230 * (10/24) + 6 * 180 (labor cost) + 2000 (crane shift fee) = 98,913 yuan, which can save nearly 1.2 million yuan in cleaning costs a year; If the subsequent heat exchange equipment omits the dust removal and ash cleaning facilities, the weight can be reduced by 10t, and the one-time investment of 200,000 yuan can be saved; the device can reduce the scouring of the heat exchange equipment by the smoke and dust, and prolong the life of the heat exchange equipment itself.

3 and 4, in the heat storage device of the present disclosure, at least a heat storage furnace body is arranged, and a plurality of heat storage sections are stacked in sequence in the heat storage furnace body at least along the axial direction; It is a block with through holes arranged in the axial direction. The high-temperature flue gas is input from the top of the furnace body, and is discharged from the bottom of the furnace body after being stored in multiple heat storage sections; the low-temperature flue gas is input from the bottom of the furnace body, and is discharged from the top of the furnace body after heat storage by multiple heat storage sections. Adapt to the physical and chemical performance requirements of the heat storage body due to the gradual change of flue gas temperature. In the treatment process of the AOD furnace, the temperature of the exhaust flue gas will decrease in a curve, so there will be flue gas with a higher temperature and flue gas with a lower temperature. In the solution of the present disclosure, the high temperature flue gas refers to the The flue gas discharged from the AOD furnace with a temperature above 500°C, and the low-temperature flue gas refers to the flue gas with a flue gas temperature of 200-500°C. This setting changes the processing paths of the high-temperature flue gas and the low-temperature flue gas, not only It can save the waste heat of the flue gas to the greatest extent, and at the same time, it can improve the processing efficiency of the whole device and increase the service life of the device.

In the embodiment of the present disclosure, the plurality of thermal storage sections include at least a first thermal storage section 43, a second thermal storage section 44 and a third thermal storage section 45; according to the thermal storage temperature, the first thermal storage section 43, The thermal storage temperatures of the second thermal storage section 44 and the third thermal storage section 45 decrease sequentially. For example, when processing high-temperature flue gas, the operation path of high-temperature flue gas is processed by the first heat storage section 43, the second heat storage section 44 and the third heat storage section 45 in turn, so as to exert the appropriate heat storage temperature of each heat storage section, Improve the heat storage efficiency as much as possible, save materials, and improve the service life of the device.

In the embodiment of the present disclosure, for example, the height ratio of the first heat storage section 43 , the second heat storage section 44 and the third heat storage section 45 is 5:2:3, which is divided into high temperature according to the distribution characteristics of flue gas There are three heat exchange sections: medium temperature and low temperature. The material and physical and chemical indicators of the heat storage body in each section are different. At the same time, the setting height of each section is also different. The rational configuration of the heat storage body is to meet the gradual reduction of flue gas temperature/liter. High requirements for high temperature resistance and mechanical properties of regenerators.

In the embodiment of the present disclosure, as shown in FIG. 4 , the heat storage brick is a polygonal block with holes in cross section, the hole diameter is 20-25 mm, and the number of holes is 7-9. The regenerative bricks (checker bricks) in the regenerative furnace are arranged in the third section of the furnace body. Different materials (silica bricks, high alumina bricks, clay bricks, etc.) are used according to the high and low temperature zones of the flue gas. It is polygonal and porous, and the hole diameter can be 20mm or 25mm round holes, and the number can be 7 or 9. The use of different materials can provide different heat storage capacities, and the structure of multiple holes can increase the contact area and improve the heat exchange efficiency.

In the embodiment of the present disclosure, a flue gas guiding section 46 is further provided under the plurality of heat storage sections; the flue gas guiding section 46 is composed of a plurality of hollow plates, for example, the flue gas guiding section 46 is composed of a plurality of Cast iron polygonal units, the size and number of holes of each unit are the same as the heat storage bricks. The low-temperature flue gas from the bottom is correspondingly introduced into the heat storage bricks, and at the same time bears a certain weight of the heat storage bricks to ensure that the flue gas enters the heat storage bricks evenly holes to improve heat transfer efficiency.

In the embodiment of the present disclosure, a refractory support section 47 is further provided under the flue gas guide section 46 , and the refractory support section 47 is supported by the pillars 71 and bears the weight of the heat storage bricks and the flue gas guide section 46 in the furnace For example, it can be a cylindrical pillar made of heat-resistant materials, such as silica brick, high-alumina brick, clay, cast iron, etc., which has a certain heat resistance and a certain gravity bearing capacity.

In the embodiment of the present disclosure, a third thermal insulation pipe 4g and a fourth thermal insulation pipe 4h are arranged outside the furnace to communicate with the refractory support section 47; a third valve 4c is arranged on the third thermal insulation pipeline 4g, and a third thermal insulation pipeline 4h is arranged on the fourth thermal insulation pipeline 4h Four valves 4d. The inlet and outlet channels of flue gas can be adjusted at any time to realize the switching between high temperature flue gas and low temperature flue gas treatment procedures.

In the embodiment of the present disclosure, a flue gas splitting section 42 is further arranged on the furnace body before the plurality of regenerative sections, and the structure of the flue gas splitting section 42 is a cylindrical cavity structure, so as to ensure that the flue gas is in the regenerative furnace diameter. to a uniform distribution. In order to facilitate the uniform entry of the flue gas into the porous heat storage brick. At the same time, the incoming flue gas is given a certain buffer space, and the flue gas flow rate is slightly reduced before heat storage, which is conducive to uniform heat absorption.

In the embodiment of the present disclosure, a first heat insulation pipe 4e and a second heat insulation pipe 4f are arranged outside the furnace to communicate with the flue gas splitting section 42; the first heat insulation pipe 4e is provided with a first valve 4a, and the second heat insulation pipe 4f is provided with a Two valves 4b. The inlet and outlet channels of flue gas can be adjusted at any time to realize the switching between high temperature flue gas and low temperature flue gas treatment procedures.

In the embodiment of the present disclosure, a flue gas buffer section 41 is also provided on the furnace body before the flue gas split section 42. The flue gas buffer section 41 is a conical closing structure, and can also be a closing structure similar to a vault to ensure that There must be headroom to buffer the flue gas.

As shown in Figure 3, the working process of the thermal storage device of the present disclosure is:

The high-temperature flue gas of the AOD furnace enters the first adiabatic pipe 4e after passing through the primary dust removal device. At this time, the first valve 4a is opened and the third valve 4c is closed. The adiabatic pipeline is sent to the waste heat boiler for 4h; when the decarburization speed of the AOD furnace decreases, the flue gas temperature decreases, and the regenerative bricks in the regenerative furnace have been heated at this time, the first valve 4a is closed, the third valve 4c is opened, and the flue gas passes through The third heat insulating pipe 4g passes through the heat storage bricks from bottom to top, and is sent to the waste heat boiler from the second heat insulating pipe 4f.

The regenerative furnace can stabilize the flue gas temperature and have a certain dust removal effect to prolong the life of the waste heat boiler, reduce or even avoid the emission of steam, and finally improve the waste heat recovery rate of the process. The upper part of the regenerative furnace is a vault type, the middle part is a regenerator (set as high, medium and low temperature zones according to the flue gas temperature distribution), and the lower part is a flue gas guide device and a refractory support column (400 ℃ resistant) ; Reasonable piping structure, the high temperature flue gas is drawn from top to bottom, and the low temperature flue gas is drawn from bottom to top.

The waste heat recovery efficiency and economic benefit of the AOD furnace flue gas waste heat efficient recovery system scheme of the present invention and the existing scheme (the existing scheme introduced in the background technology) are compared as shown in Table 1 below:

Table 1

Note: Take the 3X120t AOD furnace as the benchmark for comparison

Taking 2x120tAOD as an example, the amount of saturated steam generated is ~50t/h. If the dust content of the flue gas is reduced by the primary dust removal device 3 and the regenerative furnace 4, and the flue gas temperature fluctuation is smoothed to achieve a 5% increase in the heat exchange efficiency, more production will be generated. Steam 50*0.05=2.5t/h (equivalent to 312.5 kWh), 1 kWh of 0.5 yuan, can save 312.5*0.5*24*350=1,312,500 yuan.

If two 30t boilers are configured (each boiler is 1.5 million yuan, and the service life is 3 years), and the boiler life is extended by 1 year, 2 sets of devices can save 150/3*2=1 million yuan;

To sum up, if the device of the present invention is used to recover the waste heat of 2 sets of 120tAOD flue gas, an income of 311.8+131.25+100=5,430,500 yuan can be generated.

The whole system of the present invention converts the waste heat of flue gas into the enthalpy of steam, the steam enters the steam turbine 13 to do work, and directly drives the induced draft fan 7 to avoid the multiple transmission and conversion of electric energy and improve the recovery rate of waste heat; Device 3, reduce the dust content of the flue gas entering the boiler, prolong the life of the boiler and heat exchange efficiency; set the heat storage device 4 in front of the waste heat boiler 5, when the decarburization speed of the AOD furnace is severe, the "interference" of the high temperature flue gas will be reduced. The heat is stored; when the decarburization speed of the AOD furnace decreases, the flue gas temperature drops sharply (basically without waste heat recovery), and the heat storage device 4 converts the stored heat energy to the low-temperature flue gas, so as to smooth out the temperature fluctuations for the subsequent waste heat boiler exchange. At the same time, because the heat storage device 4 stabilizes the temperature of the flue gas, it avoids the phenomenon that the subsequent steam heat accumulator 12 cannot recover excess steam and can not be released when the flue gas is high temperature, and also solves the problem of choosing steam storage in actual production. Heater difficult problem. In addition, in FIG. 1 , it is also shown that the flue gas from the secondary and tertiary dust removal in the production process of the workshop is directly connected to the bag filter 6 for subsequent flue gas discharge.

The preferred embodiments of the present disclosure have been described above in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above-mentioned embodiments. Various simple modifications can be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure. These simple modifications all fall within the protection scope of the present disclosure.

In addition, it should be noted that the various specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner unless they are inconsistent. In order to avoid unnecessary repetition, the present disclosure provides The combination method will not be specified otherwise.

In addition, the various embodiments of the present disclosure can also be arbitrarily combined, as long as they do not violate the spirit of the present disclosure, they should also be regarded as the contents disclosed in the present disclosure.

Claims (10)

1. an AOD furnace flue gas waste heat efficient recovery system is characterized in that, setting flue gas waste heat recovery pipeline and steam waste heat recovery pipeline; The high-temperature flue gas generated by the AOD furnace exchanges heat with the vaporization flue to generate high-temperature saturated steam and cooling flue gas; the cooling flue gas passes through the flue gas waste heat recovery pipeline for waste heat recovery, and the high-temperature saturated steam passes through the steam waste heat recovery pipeline for waste heat recovery; At least a dust removal device (3) and a heat storage device (4) are connected in sequence on the said flue gas waste heat recovery pipeline; The dedusting device is provided with a dedusting furnace body (32), a buffer smoke exhaust chamber (31) is semi-embedded at the top of the dedusting furnace body (32), and a peripheral supply supply is connected to the outside of the middle of the dedusting furnace body (32). Oxygen pipeline; the outer diameter of the buffer smoke exhaust chamber (31) gradually increases along the distance from the top of the dust removal furnace body (32); The heat storage device (4) is provided with at least a heat storage furnace body, and a plurality of heat storage sections are sequentially stacked in the heat storage furnace body at least along the axial direction; the heat storage section is provided with heat storage bricks, and the heat storage bricks are: Blocks with through-holes arranged along the axial direction; high-temperature flue gas is input from the top of the regenerative furnace body, and is discharged from the bottom of the regenerative furnace body after being stored in multiple regenerative sections; low-temperature flue gas is input from the bottom of the regenerative furnace body, A plurality of heat storage sections are discharged from the top of the heat storage furnace body after heat storage. 2. The high-efficiency recovery system for waste heat of AOD furnace flue gas according to claim 1, characterized in that, the buffer smoke exhaust chamber (31) is provided with a cavity pipe, and a buffer smoke exhaust pipe (311) is arranged in communication with the cavity pipe; The buffer smoke exhaust pipe (311) is a pipe body structure with an increasing outer diameter; The height of the buffer smoke exhaust pipe (311) is 1/3 to 3/4 times the height of the dust removal furnace body (32); The outer diameter of the buffer smoke exhaust pipe (311) ranges from 1.5 to 2.5 m; The depth of the buffer smoke exhaust chamber (31) embedded in the dust removal furnace body (32) is 1-2m. 3. AOD furnace flue gas waste heat efficient recovery system according to claim 1 or 2, characterized in that, the buffer smoke exhaust chamber (31) and the dust removal and dust removal furnace body (32) form an annular gap, and the volume of the annular gap It is 80～90m ³ . 4. AOD furnace flue gas waste heat efficient recovery system according to claim 1 or 2, characterized in that, the oxygen supply pipeline comprises an oxygen supply main pipe (33) and a plurality of oxygen supply branch pipes (331); oxygen supply The branch pipe (331) is connected to the outside of the dedusting and dedusting furnace body (32) in a circumferential direction; The dedusting and dedusting furnace body (32) is provided with a smoke inlet section (321), a buffer combustion section (322) and a sedimentation ash discharge section (323) in sequence along the axial direction; the buffer smoke exhaust chamber (31) is arranged along the smoke inlet section (323). The section (321) and the buffer combustion section (322) are embedded; the oxygen supply pipeline is enclosed outside the buffer combustion section (322); The smoke inlet section (321) has a conical cavity structure, and a smoke inlet pipe (4) is communicated with the smoke inlet section (321), and a smoke exhaust pipe is arranged in communication with the top of the buffer smoke exhaust chamber (31). (35), a CO detector (351) is arranged on the exhaust pipe (35); The sedimentation ash discharge section (323) has a conical cavity structure, an ash discharge valve (3c) is arranged at the bottom of the sedimentation ash discharge section (323), and an inspection port (231) is arranged on the side wall of the sedimentation ash discharge section (323). . 5. The system for efficiently recovering waste heat from flue gas of an AOD furnace according to claim 1 or 2, wherein the plurality of heat storage sections at least include a first heat storage section (43) and a second heat storage section (44). ) and the third thermal storage section (45); according to the thermal storage temperature, the thermal storage temperature or storage temperature of the first thermal storage section (43), the second thermal storage section (44) and the third thermal storage section (45) The thermal coefficient decreases successively; The heat storage brick is a polygonal block with holes in cross section, the hole diameter is 20-25mm, and the number of holes is 7-9. 6. The heat storage device for waste heat recovery of AOD furnace flue gas according to claim 1 or 2, characterized in that, a flue gas guide section (46) is also provided under the plurality of heat storage sections; The diversion section (46) is composed of a plurality of hollow plates; A refractory support section (47) is further provided under the flue gas guide section (46), and the refractory support section (47) is supported by a plurality of evenly distributed pillars (471); A third thermal insulation pipe (4g) and a fourth thermal insulation pipeline (4h) are arranged on the refractory support section (47) in communication with the outside of the regenerative furnace; a third valve (4c) is arranged on the third thermal insulation pipeline (4g), and a fourth thermal insulation pipeline A fourth valve (4d) is provided on the adiabatic pipeline (4h). 7. The heat storage device for the recovery of waste heat from flue gas of AOD furnace according to claim 1 or 2, characterized in that, a flue gas split section is also provided on the heat storage furnace body before the plurality of heat storage sections (42), the flue gas splitting section (42) has a cylindrical cavity structure; the flue gas splitting section (42) communicates with the outside of the regenerative furnace and is provided with a first thermal insulation pipe (4e) and a second thermal insulation pipe (4f); A first valve (4a) is arranged on the first thermal insulation pipeline (4e), and a second valve (4b) is arranged on the second thermal insulation pipeline (4f); A flue gas buffer section (41) is further provided on the regenerative furnace body before the flue gas splitting section (42), and the flue gas buffer section (41) has a conical closing structure. 8. The heat storage device for waste heat recovery of AOD furnace flue gas according to claim 1 or 2, characterized in that, the waste heat recovery pipeline of flue gas comprises an adiabatic flue (2), a dust removal device that are communicated in sequence (3), a heat storage device (4), a waste heat boiler (5), a bag filter (6), an induced draft fan (7) and a chimney (8). 9. The heat storage device for waste heat recovery of AOD furnace flue gas according to claim 1 or 2, wherein the steam waste heat recovery pipeline comprises a steam pipeline (9), a first steam drum that are communicated in sequence (10), a steam regenerator (12), a steam turbine (13), a clutch (14) and a generator (15); The generator (15) provides power for the exhaust of the flue gas from the waste heat recovery pipeline of the flue gas. 10. The heat storage device for waste heat recovery of AOD furnace flue gas according to claim 1 or 2, wherein the steam generated by the steam waste heat recovery pipeline is converted into electric energy, and the electric energy is the waste heat recovery tube of flue gas. The flue gas from the road is discharged for power supply.

Images