CN223005341U - Flue gas waste heat deep utilization system of multi-state coupling heat storage steelmaking electric furnace - Google Patents
Flue gas waste heat deep utilization system of multi-state coupling heat storage steelmaking electric furnace Download PDFInfo
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Abstract
The utility model discloses a flue gas waste heat deep utilization system of a multi-state coupling heat storage steelmaking electric furnace, which comprises a flue gas system, a low-pressure steam system, a fused salt heat exchange and storage system, a high-pressure steam system and a power generation system. The utility model adds a front flue heat accumulator in the front flue of the settling chamber, adds a settling chamber heat accumulator in the combustion settling chamber, and adds a high-pressure water accumulator on a connecting pipeline between the outlet of the high-pressure economizer and the water inlet of the high-pressure preheater. By arranging the front flue heat accumulator, the sedimentation chamber heat accumulator and the high-pressure water accumulator, the utility model can better stabilize the great fluctuation of the flue gas temperature of the electric furnace, simplify the control of molten salt and water supply flow in the high-pressure steam system, maintain the stable output of the high-pressure steam, increase the stability and safety of the system and further perfect the flue gas waste heat recovery technology of the electric furnace.
Description
Technical Field
The utility model relates to the technical field of flue gas waste heat utilization, in particular to a flue gas waste heat deep utilization system of a polymorphic coupling heat storage steelmaking electric furnace.
Background
Compared with the traditional converter steelmaking with long flow, the electric furnace steelmaking has the outstanding advantages of short process, investment saving, fast construction, good energy saving and emission reduction effects and the like.
In order to meet the requirements of a dust removal system, the flue gas of the electric furnace needs to be cooled to below 180 ℃. According to statistics, the heat taken away by cooling water, smoke and smoke dust during electric furnace smelting accounts for more than 10% of the total input heat of the electric furnace, and the addition amount of molten iron can be even close to 30% when the addition amount of molten iron is large.
After the electric furnace is electrified, primary flue gas is pumped out from a fourth hole through a furnace cover, is cooled step by step through a water-cooling elbow, a water-cooling sliding sleeve, a water-cooling sedimentation chamber and a water-cooling flue, is cooled to about 200 ℃ through an air cooler or a spray cooling tower, is fully mixed with secondary waste gas which is collected by an environment dust hood and is about 45 ℃, and finally is discharged to the atmosphere through a dust removal fan after dust removal by a bag-type dust remover. The water cooling and air cooling mixed mode can effectively reduce the temperature of the flue gas and efficiently capture the flue gas and dust, but a large-scale cooling system is required to be equipped, a large amount of cooling water and electric power are consumed, the operation cost is high, and a large amount of high-quality heat contained in the high-temperature flue gas is not recycled. Part of iron and steel enterprises also adopt the modes of preheating scrap steel, vaporizing flue, heat pipe waste heat boiler, water pipe waste heat boiler and the like to recycle waste heat in flue gas, but the problems of incomplete waste heat recycling, low waste heat recycling rate, low recycling steam parameters and the like of each temperature section exist.
The utility model ZL202322630661.X discloses a deep utilization system of flue gas waste heat of a steelmaking electric furnace, which can stabilize the fluctuation of the temperature and flow of the flue gas to a large extent by arranging a low-pressure steam system, a high-pressure steam system and a fused salt heat exchange and storage system, thereby creating conditions for recycling the flue gas waste heat of the electric furnace in a full-temperature section. However, the great fluctuation of the temperature and flow of the flue gas exists objectively all the time, although the fluctuated flue gas heat can be stored in the fused salt through the fused salt heat exchange and storage system, and then is continuously and stably output in the high-pressure steam system, the fluctuation of the heat absorbed by the tail high-pressure economizer is limited, the water supply flow and the temperature fluctuation entering the high-pressure steam system from the high-pressure economizer are large, the water supply flow and the temperature fluctuation are difficult to be well matched with the fused salt temperature and the flow in the high-pressure steam system in real time, and under the limit, overheat or supercooling phenomena can be generated in a heating surface of the high-pressure steam system, so that the stable generation of the high-pressure steam is not facilitated, and the safe operation of the heating surface and the system is also not facilitated. Therefore, the method further stabilizes the temperature and flow of the flue gas of the electric furnace to greatly fluctuate, keeps the stable molten salt and water supply flow of the high-pressure steam system, further ensures that the high-pressure steam system stably generates high-parameter steam meeting the requirements, ensures the safe and stable operation of the whole system, and has great significance for popularizing the flue gas waste heat utilization system of the electric furnace, reducing the steelmaking cost of the electric furnace and improving the energy-saving and carbon-reducing level of steel enterprises.
Disclosure of utility model
In order to solve the technical problems, the utility model designs a flue gas waste heat deep utilization system of a multi-state coupling heat storage steelmaking electric furnace.
The utility model adopts the following technical scheme:
A flue gas waste heat deep utilization system of a multi-state coupling heat storage steelmaking electric furnace comprises a flue gas system, a low-pressure steam system, a fused salt heat exchange and storage system, a high-pressure steam system and a power generation system;
The flue gas system comprises an electric furnace, a sedimentation chamber front flue, a combustion sedimentation chamber, a sedimentation chamber rear flue, a fan and a dust removal connecting flue which are connected in sequence;
The low-pressure steam system comprises a deaerator, a heat accumulator, an external steam supply superheater, a low-pressure steam drum, a flue vaporization heat exchanger, a sedimentation chamber vaporization heat exchanger, a low-pressure evaporator, a low-pressure economizer and corresponding connecting pipelines;
The molten salt heat exchange and heat storage system comprises a high-temperature molten salt tank, a medium-temperature molten salt tank, a low-temperature molten salt tank, a high-temperature molten salt heat exchanger, a medium-temperature molten salt heat exchanger and corresponding connecting pipelines;
The high-pressure steam system comprises a high-pressure preheater, a high-pressure evaporator, a high-pressure steam drum, a high-pressure superheater, a high-pressure economizer and corresponding connecting pipelines;
In the low-pressure steam system, an inlet of a deaerator is connected with water supply, an outlet of the deaerator is respectively connected with an inlet of a low-pressure economizer and an inlet of a high-pressure economizer, an outlet of the low-pressure economizer is connected with a water inlet of a low-pressure steam drum, a water outlet of the low-pressure steam drum is respectively connected with an inlet of a flue vaporization heat exchanger, an inlet of a sedimentation chamber vaporization heat exchanger and an inlet of a low-pressure evaporator, an outlet of the flue vaporization heat exchanger, an outlet of the sedimentation chamber vaporization heat exchanger and an outlet of the low-pressure evaporator are connected with a steam-water mixture inlet of the low-pressure steam drum, and a steam outlet of the low-pressure steam drum is connected with an inlet of a heat accumulator;
In the high-pressure steam system, an outlet of a high-pressure economizer is connected with a water inlet of a high-pressure preheater, a water outlet of the high-pressure preheater is connected with a water inlet of a high-pressure steam drum, a water outlet of the high-pressure steam drum is connected with a water inlet of a high-pressure evaporator, an outlet of the high-pressure evaporator is connected with a steam-water mixture inlet of the high-pressure steam drum, a steam outlet of the high-pressure steam drum is connected with a steam inlet of a high-pressure superheater, and a steam outlet of the high-pressure superheater is connected with a power generation system;
In the molten salt heat exchange and storage system, an outlet of a high-temperature molten salt tank is connected with a molten salt inlet of a high-pressure superheater, a molten salt outlet of the high-pressure superheater is connected with a molten salt inlet of a high-pressure evaporator, a molten salt outlet of the high-pressure evaporator is connected with a molten salt inlet of a low-temperature molten salt tank, a molten salt outlet of the low-temperature molten salt tank is connected with an inlet of a medium-temperature molten salt heat exchanger, an outlet of the medium-temperature molten salt heat exchanger is connected with an inlet of the medium-temperature molten salt tank, an outlet of the medium-temperature molten salt tank is connected with an inlet of the high-temperature molten salt heat exchanger, and an outlet of the high-temperature molten salt heat exchanger is connected with an inlet of the high-temperature molten salt tank;
The high-pressure coal economizer is characterized in that a front flue heat accumulator is arranged in the front flue of the settling chamber, a settling chamber heat accumulator is arranged in the combustion settling chamber, and a high-pressure water storage tank is connected to a connecting pipeline between the outlet of the high-pressure coal economizer and the water inlet of the high-pressure preheater.
Preferably, the front flue heat accumulator and the sedimentation chamber heat accumulator are made of porous magnesia bricks, porous ceramics or porous precast concrete and other high-heat-capacity high-temperature-resistant materials.
Preferably, the flue vaporization heat exchanger is arranged in a front flue of the settling chamber, and the settling chamber vaporization heat exchanger is arranged in the combustion settling chamber.
Preferably, the high-temperature molten salt heat exchanger, the medium-temperature molten salt heat exchanger, the low-pressure evaporator, the high-pressure economizer and the low-pressure economizer are sequentially arranged in a rear flue of the settling chamber from front to back.
Preferably, the external steam superheater is installed in the low pressure drum.
Preferably, a low-pressure water supply pump is connected between the deaerator outlet and the low-pressure economizer inlet, and a high-pressure water supply pump is connected between the deaerator outlet and the high-pressure economizer inlet.
Preferably, the high-pressure steam system further comprises a high-temperature molten salt pump, a low-temperature molten salt pump and a medium-temperature molten salt pump, wherein an outlet of the high-temperature molten salt tank is connected with a molten salt inlet of the high-pressure superheater through the high-temperature molten salt pump, a molten salt outlet of the low-temperature molten salt tank is connected with an inlet of the medium-temperature molten salt heat exchanger through the low-temperature molten salt pump, and an outlet of the medium-temperature molten salt tank is connected with an inlet of the high-temperature molten salt heat exchanger through the medium-temperature molten salt pump.
Preferably, the outlet of the high-temperature molten salt heat exchanger is connected with the inlet of the medium-temperature molten salt tank through a bypass.
Preferably, the power generation system comprises a back pressure turbine and a generator, wherein the back pressure turbine is connected with the generator, a steam outlet of the high-pressure superheater is connected with an inlet of the back pressure turbine, and a steam outlet of the back pressure turbine is connected with a heat user.
Preferably, the outlet of the external steam supply superheater is connected with a heat user.
The utility model absorbs part of high-temperature smoke heat at the front end and absorbs low-temperature smoke heat at the rear end through the low-pressure steam system to generate low-pressure steam, so that the low-pressure steam can be used for other steelmaking processes or supplied to heat users. And meanwhile, the high-temperature flue gas heat is absorbed through the fused salt heat exchange and storage system and is stored in the high-temperature fused salt tank, the high-temperature fused salt in the high-temperature fused salt tank releases heat through a high-pressure superheater, a high-pressure evaporator and a high-pressure preheater of the high-pressure steam system, high-temperature high-pressure superheated steam is stably produced and is supplied to a back pressure steam turbine for power generation, and low-pressure steam discharged after power generation can be supplied to other steelmaking processes or heat users. The system is provided with 3 molten salt tanks in total. The medium-temperature molten salt tank is used for storing molten salt in a certain temperature range (such as 350-510 ℃) and providing a heat absorption medium for the waste heat recovery of high-temperature flue gas, when the temperature of the flue gas is not higher than the set temperature (such as 540 ℃), the medium-temperature molten salt circulates between the medium-temperature molten salt tank and the high-temperature molten salt heat exchanger through a bypass, exchanges heat with the flue gas (is heated by the flue gas) and stabilizes the temperature fluctuation of the flue gas, the high-temperature molten salt tank is used for storing the high-temperature molten salt (such as 510 ℃) which reaches a certain temperature, provides a stable heat source for the high-pressure steam system, pumps the medium-temperature molten salt from the medium-temperature molten salt tank to the high-temperature molten salt heat exchanger when the temperature of the flue gas is higher than the set temperature (such as 540 ℃), and then sends the molten salt to the high-temperature molten salt tank for storage after absorbing the waste heat of the flue gas to the set temperature (such as 510 ℃), so that the temperature in the high-temperature molten salt tank can be kept stable.
Compared with the ZL 2023 2 2630681. X, the utility model has the advantages that the front flue heat accumulator and the sedimentation chamber heat accumulator are respectively added in the front flue of the sedimentation chamber and the combustion sedimentation chamber, and the high-pressure water storage tank is additionally arranged between the high-pressure economizer and the high-pressure preheater.
The front flue heat accumulator and the sedimentation chamber heat accumulator are arranged, and the front flue heat accumulator has the functions that when the temperature of the flue gas is high, the heat accumulator absorbs heat in the flue gas and heats up, part of heat of the high-temperature flue gas is stored in the heat accumulator and reduces the temperature of the flue gas, and when the temperature of the flue gas is low, the heat accumulator releases heat to the flue gas and reduces the temperature to increase the temperature of the flue gas.
The high-pressure water storage tank has the effect that in the smelting period of the electric furnace, as the temperature and flow rate of the flue gas flowing through the high-pressure economizer fluctuate greatly, the heat absorbed by the high-pressure water supply in the high-pressure economizer also fluctuates greatly, in order to ensure the safety of a heating surface by making the water supply entering the high-pressure preheater and the high-pressure evaporator have proper temperatures, the water supply flow rate is usually required to be adjusted according to the heat absorption quantity, which leads to the water supply flow rate to fluctuate greatly along with the temperature and flow rate of the flue gas, and is not matched with the stable molten salt flow rate in the high-pressure preheater, the high-pressure evaporator and the high-pressure superheater, and the phenomenon of insufficient cooling of a heat exchange surface or molten salt solidification can occur under the limit condition. After the high-pressure water storage tank is additionally arranged between the high-pressure coal economizer and the high-pressure preheater, the inlet high-pressure water supply flow of the water storage tank is adjusted according to the flue gas temperature and flow fluctuation, so that the water supply temperature is proper, and the outlet flow of the water storage tank can be kept stable and matched with the stable molten salt flow in the high-pressure preheater, the high-pressure evaporator and the high-pressure superheater.
Compared with the existing electric furnace flue gas waste heat utilization technology, the electric furnace flue gas waste heat utilization technology has the advantages that (1) the front flue heat accumulator and the sedimentation chamber heat accumulator are arranged to stabilize the large fluctuation of the flue gas temperature to a certain extent, partial dust in the flue gas is separated, the working conditions of the subsequent heating surfaces at different levels are improved, (2) the high-pressure water storage tank is arranged, the stable matching of water supply and molten salt flow can be realized in the high-pressure steam system, the flow control of molten salt is simplified, the stable output of the high-pressure steam is ensured, meanwhile, the overheating and supercooling phenomena in the heat exchange surface caused by the fluctuation of the water flow are avoided, the risks of dry heating and molten salt solidification of the heating surfaces are avoided, the safe and stable operation of the whole system is further ensured, the electric furnace flue gas heat which fluctuates is converted into different forms such as sensible heat of the heat accumulator, sensible heat of the molten salt, sensible heat of the low-pressure steam, sensible heat of the high-pressure water supply and the like through reasonable arrangement and is then converted into stable output of the low-pressure steam and the high-pressure steam, the waste heat utilization efficiency is improved, the waste heat utilization efficiency is further improved, the influence on the waste heat utilization quality of the waste heat is greatly improved.
Drawings
FIG. 1 is a schematic view of a construction of the present utility model;
In the figure, 1, water supply, 2, a low-pressure water supply pump, 3, a high-pressure water supply pump, 4, a heat user, 100, a flue gas system, 101, an electric furnace, 102, a settling chamber front flue, 103, a combustion settling chamber, 104, a settling chamber rear flue, 105, a fan, 106, a dedusting connection flue, 107, a front flue heat accumulator, 108, a settling chamber heat accumulator, 200, a low-pressure steam system, 201, a deaerator, 202, a heat accumulator, 203, an external steam superheater, 204, a low-pressure steam drum, 205, a flue vaporization heat exchanger, 206, a settling chamber vaporization heat exchanger, 207, a low-pressure evaporator, 208, a low-pressure economizer, 300, a molten salt heat exchange heat storage system, 301, a high-temperature molten salt tank, 302, a high-temperature molten salt pump, 303, a medium-temperature molten salt tank, 304, a low-temperature molten salt tank, 305, a low-temperature molten salt pump, 306, a medium-temperature molten salt pump, 307, a high-temperature molten salt heat exchanger, 308, a medium-temperature molten salt heat exchanger, 400, a high-pressure steam system, 401, a high-pressure preheater, 402, a high-pressure evaporator, 403, a high-pressure evaporator, a high-pressure drum, a 208, a high-pressure generator, a power generator, a high-pressure drum, a power generator, a high-pressure generator, a power generator, a high-pressure drum, and a power generator, and a high-pressure system are shown.
Detailed Description
The technical scheme of the utility model is further specifically described by the following specific embodiments with reference to the accompanying drawings:
Embodiment as shown in fig. 1, the flue gas waste heat deep utilization system of the multi-state coupling heat storage steelmaking electric furnace comprises a flue gas system 100, a low-pressure steam system 200, a fused salt heat exchange and storage system 300, a high-pressure steam system 400 and a power generation system 500.
The flue gas system 100 comprises an electric furnace 101, a settling chamber front flue 102, a front flue heat accumulator 107, a combustion settling chamber 103, a settling chamber heat accumulator 108, a settling chamber rear flue 104, a fan 105 and a dust removal connecting flue 106. The electric furnace 101, the settling chamber front flue 102, the combustion settling chamber 103, the settling chamber rear flue 104, the fan 105 and the dust removal connecting flue 106 are sequentially connected, the front flue heat accumulator 107 is arranged in the settling chamber front flue 102, and the settling chamber heat accumulator 108 is arranged in the combustion settling chamber 103. The front flue heat accumulator 107 and the sedimentation chamber heat accumulator 108 are made of porous magnesia bricks, porous ceramics or porous precast concrete and other high-heat-capacity high-temperature-resistant materials.
The low pressure steam system 200 comprises a deaerator 201, a heat accumulator 202, an external steam supply superheater 203, a low pressure drum 204, a flue vaporization heat exchanger 205, a settling chamber vaporization heat exchanger 206, a low pressure evaporator 207, a low pressure economizer 208 and corresponding connecting piping.
The molten salt heat exchange and storage system 300 comprises a high-temperature molten salt tank 301, a high-temperature molten salt pump 302, a medium-temperature molten salt tank 303, a low-temperature molten salt tank 304, a low-temperature molten salt pump 305, a medium-temperature molten salt pump 306, a high-temperature molten salt heat exchanger 307, a medium-temperature molten salt heat exchanger 308 and corresponding connecting pipelines.
The high pressure steam system 400 comprises a high pressure preheater 401, a high pressure evaporator 402, a high pressure drum 403, a high pressure superheater 404, a high pressure economizer 405, a high pressure water storage tank 406 and corresponding connecting pipes.
The power generation system 500 includes a back pressure turbine 501, a generator 502.
Correspondingly, the flue vaporization heat exchanger 205 is installed in the front flue 102 of the settling chamber, the settling chamber vaporization heat exchanger 206 is installed in the combustion settling chamber 103, and the high-temperature molten salt heat exchanger 307, the medium-temperature molten salt heat exchanger 308, the low-pressure evaporator 207, the high-pressure economizer 405 and the low-pressure economizer 208 are sequentially installed in the rear flue 104 of the settling chamber from front to rear. The external supply steam superheater 203 is mounted in the low pressure steam drum 204.
In the low pressure steam system 200, the outlet of the deaerator 201 is connected with the inlet of the low pressure feed pump 2 and the inlet of the high pressure feed pump 3, respectively. The outlet of the low-pressure feed pump 2 is connected with the inlet of the low-pressure economizer 208, and the outlet of the low-pressure economizer 208 is connected with the water inlet of the low-pressure steam drum 204. The water outlet of the low-pressure steam drum 204 is respectively connected with the inlet of the flue vaporization heat exchanger 205, the inlet of the sedimentation chamber vaporization heat exchanger 206 and the inlet of the low-pressure evaporator 207, the outlet of the flue vaporization heat exchanger 205, the outlet of the sedimentation chamber vaporization heat exchanger 206 and the outlet of the low-pressure evaporator 207 are connected with the steam-water mixture inlet of the low-pressure steam drum 204, and the steam outlet of the low-pressure steam drum 204 is connected with the inlet of the heat accumulator 202. The outlet of the heat accumulator 202 is connected with the inlet of the external steam superheater 203, and the outlet of the external steam superheater 203 is connected with the heat consumer 4.
In the high-pressure steam system 400, an outlet of the high-pressure water feed pump 3 is connected with an inlet of the high-pressure economizer 405, an outlet of the high-pressure economizer 405 is connected with an inlet of the high-pressure water storage tank 406, an outlet of the high-pressure water storage tank 406 is connected with a water inlet of the high-pressure preheater 401, a water outlet of the high-pressure preheater 401 is connected with a water inlet of the high-pressure steam drum 403, a water outlet of the high-pressure steam drum 403 is connected with a water inlet of the high-pressure evaporator 402, an outlet of the high-pressure evaporator 402 is connected with a steam-water mixture inlet of the high-pressure steam drum 403, a steam outlet of the high-pressure steam drum 403 is connected with a steam inlet of the high-pressure superheater 404, a steam outlet of the high-pressure superheater 404 is connected with an inlet of the back pressure steam turbine 501, and a steam outlet of the back pressure steam turbine 501 is connected with the heat user 4.
In the molten salt heat exchange and storage system 300, an outlet of a high-temperature molten salt tank 301 is connected with a molten salt inlet of a high-pressure superheater 404 through a high-temperature molten salt pump 302, a molten salt outlet of the high-pressure superheater 404 is connected with a molten salt inlet of a high-pressure evaporator 402, a molten salt outlet of the high-pressure evaporator 402 is connected with a molten salt inlet of a high-pressure preheater 401, a molten salt outlet of the high-pressure preheater 401 is connected with a molten salt inlet of a low-temperature molten salt tank 304, a molten salt outlet of the low-temperature molten salt tank 304 is connected with an inlet of a medium-temperature molten salt heat exchanger 308 through a low-temperature molten salt pump 305, an outlet of the medium-temperature molten salt heat exchanger 308 is connected with an inlet of a medium-temperature molten salt tank 303 through a medium-temperature molten salt pump, an outlet of the high-temperature molten salt heat exchanger 307 is connected with an inlet of the high-temperature molten salt tank 301, and an outlet of the high-temperature molten salt heat exchanger 307 is connected with an inlet of the medium-temperature molten salt tank 303 through a bypass.
The flue gas waste heat recovery flow of the electric furnace based on the utility model is briefly described below.
In the steelmaking process, the flue gas is continuously discharged from the fourth hole of the electric furnace 101, flows through the front flue 102 of the settling chamber, the combustion settling chamber 103 and the rear flue 104 of the settling chamber in sequence, is pumped to the dust removal connecting flue 106 by the fan 105, and goes to a dust removal system. In the pre-settling chamber flue 102 and the combustion settling chamber 103, CO in the flue gas is mixed with the sucked air for combustion, and most of dust is settled and separated in the combustion settling chamber 103. In the front-to-back flow process of the flue gas, the flue gas exchanges heat with the front flue heat accumulator 107, the flue vaporization heat exchanger 205, the settling chamber heat accumulator 108, the settling chamber vaporization heat exchanger 206, the high-temperature molten salt heat exchanger 307, the medium-temperature molten salt heat exchanger 308, the low-pressure evaporator 207, the high-pressure economizer 405 and the low-pressure economizer 208 step by step, the temperature of the flue gas is cooled to below 180 ℃, and then the flue gas enters a dust removal system to complete dust removal.
The external feed water 1 enters the deaerator 201, where deaeration takes place. One path of deoxygenated water enters the low-pressure economizer 208 through the low-pressure feed pump 2, and the other path enters the high-pressure economizer 405 through the high-pressure feed pump.
The deoxygenated water entering the low pressure economizer 208 enters the low pressure drum 204 through the water inlet of the low pressure drum 204 after exchanging heat with the flue gas therein. Saturated water in the low-pressure steam drum 204 respectively enters a flue vaporization heat exchanger 205, a sedimentation chamber vaporization heat exchanger 206 and a low-pressure evaporator 207 through water outlets, absorbs the heat of the flue gas, is vaporized, enters the low-pressure steam drum 204 from a steam-water mixture inlet in the form of a steam-water mixture, and steam in the low-pressure steam drum 204 enters the heat accumulator 202 through a steam outlet after being subjected to steam-water separation. When it is desired to supply steam to the outside, the steam in the regenerator 202 enters an outside-supplied steam superheater 203 installed in the low-pressure drum 204 through an outlet. Since the pressure of the heat accumulator 202 is lower than the pressure of the low-pressure drum 203, the saturated steam temperature in the heat accumulator 202 is lower than the saturated steam temperature of the low-pressure drum 203, and the saturated steam from the heat accumulator 202 becomes low-pressure superheated steam after absorbing heat in the external steam supply superheater 203, and is then supplied to the heat consumer 4. In this example, the low pressure superheated steam pressure was 1.35MPa and the temperature was 205 ℃.
To prevent the water entering the high pressure drum from getting too warm, a high pressure preheater is provided between the high pressure economizer 405 and the high pressure drum 403. Deoxygenated water from the high-pressure water feed pump 3 enters the high-pressure economizer 405, enters the high-pressure water storage tank after heat exchange with flue gas, then enters the high-pressure preheater 401 from the outlet of the high-pressure water storage tank 406 at a stable flow rate, exchanges heat with molten salt, enters the high-pressure steam drum 403 after being heated to a proper temperature, saturated water in the high-pressure steam drum 403 enters the high-pressure evaporator 402 through the water outlet, is vaporized and evaporated in the high-pressure evaporator 402 by heat exchange with the molten salt, enters the high-pressure steam drum 403 through the steam-water mixture inlet in the form of a steam-water mixture, steam in the high-pressure steam drum 403 enters the high-pressure superheater 404 through the steam outlet after steam-water separation, exchanges heat with the high-temperature molten salt in the high-pressure superheater 404 to form high-temperature high-pressure superheated steam, and the superheated steam is led out from the steam outlet of the high-pressure superheater 404, enters the back pressure steam turbine 501 to drive the back pressure steam turbine 501 to rotate, and the back pressure steam turbine 501 drives the generator 502 to generate power. The low-pressure superheated steam after power generation is discharged from the back pressure turbine 501 and sent to the heat consumer 4. In this example, the high temperature and high pressure superheated steam used for power generation had a pressure of 9.8MPa and a temperature of 480℃and the low pressure superheated steam had a pressure of 1.35MPa and a temperature of 205 ℃.
In order to stably produce high-temperature and high-pressure superheated steam for power generation, a molten salt heat exchange and storage system 300 including 3 molten salt tanks is provided. In this embodiment, the high-temperature molten salt tank 301 is used for storing high-temperature molten salt with a temperature higher than a set temperature (510 ℃ in this embodiment) to provide a stable heat source for the high-pressure steam system 400, the low-temperature molten salt tank 304 is used for storing cold salt (280 ℃ in this embodiment) which leaves after heat exchange with the high-pressure steam system 400 to provide a heat absorbing medium for waste heat recovery of medium-temperature flue gas, and the medium-temperature molten salt tank 303 is used for storing molten salt with a certain temperature range (350 ℃ to 510 ℃ in this embodiment) to provide a heat absorbing medium for waste heat recovery of high-temperature flue gas. When high-temperature and high-pressure steam is required to be generated for power generation of the power generation system 500, high-temperature molten salt in the high-temperature molten salt tank 301 is pumped into the high-pressure superheater 404 through the high-temperature molten salt pump 302, saturated steam from the high-pressure steam drum 403 is superheated in the high-pressure superheater 404 and then enters the high-pressure evaporator 402, saturated water from the high-pressure steam drum 403 is heated and vaporized in the high-pressure evaporator 402 and then enters the high-pressure preheater 401, unsaturated water from the high-pressure economizer 405 is heated to a proper temperature in the high-pressure preheater 401 so as to be beneficial to entering the high-pressure steam drum 403, and molten salt with a temperature of about 280 ℃ after heat release flows out of the high-pressure preheater 401 and enters the low-temperature molten salt tank 304. Molten salt in the low-temperature molten salt tank 304 is pumped into the medium-temperature molten salt heat exchanger 308 through the low-temperature molten salt pump 305, and enters the medium-temperature molten salt tank 303 after absorbing the waste heat of flue gas in the medium-temperature molten salt heat exchanger 308. According to the difference of the temperature of the flue gas at the inlet of the high-temperature molten salt heat exchanger 307, the molten salt in the medium-temperature molten salt tank 303 has two operation modes, namely when the temperature of the flue gas at the inlet of the high-temperature molten salt heat exchanger 307 is higher than the set temperature (540 ℃ in the embodiment), the medium-temperature molten salt is pumped to the high-temperature molten salt heat exchanger 307 from the medium-temperature molten salt tank 303 through the medium-temperature molten salt pump 306, the flue gas is absorbed, high-temperature waste heat is heated to be higher than the set temperature (510 ℃ in the embodiment) and then is sent to the high-temperature molten salt tank 301 for storage, and when the temperature of the flue gas at the inlet of the high-temperature molten salt heat exchanger 307 is not higher than the set temperature (540 ℃ in the embodiment), the medium-temperature molten salt is pumped to the high-temperature molten salt heat exchanger 307 from the medium-temperature molten salt tank 303, exchanges heat with the flue gas (is heated by the flue gas or the flue gas) and then is sent back to the medium-temperature molten salt tank 303 through a bypass. thus, when the temperature of the flue gas passing through the high-temperature molten salt heat exchanger 307 is not high enough to heat the medium-temperature molten salt to a required temperature (510 ℃ in the embodiment), the medium-temperature molten salt from the medium-temperature molten salt tank 303 flows through the high-temperature molten salt heat exchanger 307 and is not fed into the high-temperature molten salt tank 301, but circulates between the medium-temperature molten salt tank 303 and the high-temperature molten salt heat exchanger 307 through a bypass, so that on one hand, the condition that the molten salt below the set temperature (510 ℃ in the embodiment) is not fed into the high-temperature molten salt tank 301 is avoided, the temperature stability of the molten salt in the high-temperature molten salt tank 301 is ensured, and on the other hand, the purpose of stabilizing the temperature fluctuation of the flue gas is achieved through the circulation of the medium-temperature molten salt between the medium-temperature molten salt tank 303 and the high-temperature molten salt heat exchanger 307, and the stable heat exchange of the subsequent heat exchange surface is facilitated.
In order to better stabilize the great fluctuation of the temperature of the flue gas at the high temperature section, a front flue heat accumulator 107 is arranged in the front flue 102 of the settling chamber, and a settling chamber heat accumulator 108 is arranged in the combustion settling chamber 103. The front flue heat accumulator 107 and the sedimentation chamber heat accumulator 108 are made of porous magnesia bricks or porous ceramics, porous precast concrete and other high-heat-capacity high-temperature-resistant materials. When the temperature of the flue gas is high, the heat accumulator absorbs heat in the flue gas and heats up, part of heat of the high-temperature flue gas is stored in the heat accumulator and reduces the temperature of the flue gas, and when the temperature of the flue gas is low, the heat accumulator releases heat to the flue gas and reduces the temperature to increase the temperature of the flue gas. The porous structure of the heat accumulator can separate part of dust in the flue gas, reduce the abrasion of the dust to the subsequent heating surfaces, and improve the running stability and safety of the whole system.
A high-pressure water storage tank 406 is provided between the high-pressure economizer 406 and the high-pressure preheater 401. After the high pressure water storage tank 406 is added, the inlet high pressure water supply flow of the high pressure water storage tank 406 is adjusted according to the flue gas temperature and flow fluctuation. When the flue gas temperature is high and the flow is large, the high-pressure water supply flow is increased by control, and when the flue gas temperature is low and the flow is small, the high-pressure water supply flow is reduced by control. This allows the water temperature entering the high pressure preheater 401 to be controlled at a suitable temperature to facilitate the safety of the subsequent high pressure evaporation and superheating process. Due to the accumulation of the high pressure water storage tank 406, the outlet flow can be stably output with an average value close to the whole smelting period, and is matched with the stable molten salt flow in the high pressure preheater, the high pressure evaporator and the high pressure superheater. The existence of the high-pressure water storage tank 406 enables the water supply/steam flow and the molten salt flow of the high-pressure preheater 401, the high-pressure evaporator 402 and the high-pressure superheater 404 in the high-pressure steam system 400 to realize stable input and output, ensures stable output of high-pressure steam, and simultaneously greatly simplifies control of molten salt and water supply flow in the high-pressure steam system 400.
By arranging the front flue heat accumulator 107, the settling chamber heat accumulator 108 and the high-pressure water storage tank 406, the utility model can better stabilize the great fluctuation of the flue gas temperature of the electric furnace, simplify the control of molten salt and water supply flow in the high-pressure steam system 400, maintain the stable output of high-pressure steam, increase the stability and safety of the system and further perfect the flue gas waste heat recovery technology of the electric furnace.
The above-described embodiment is only a preferred embodiment of the present utility model, and is not limited in any way, and other variations and modifications may be made without departing from the technical aspects set forth in the claims.
Claims (10)
1. A flue gas waste heat deep utilization system of a multi-state coupling heat storage steelmaking electric furnace comprises a flue gas system, a low-pressure steam system, a fused salt heat exchange and storage system, a high-pressure steam system and a power generation system;
The flue gas system comprises an electric furnace, a sedimentation chamber front flue, a combustion sedimentation chamber, a sedimentation chamber rear flue, a fan and a dust removal connecting flue which are connected in sequence;
The low-pressure steam system comprises a deaerator, a heat accumulator, an external steam supply superheater, a low-pressure steam drum, a flue vaporization heat exchanger, a sedimentation chamber vaporization heat exchanger, a low-pressure evaporator, a low-pressure economizer and corresponding connecting pipelines;
The molten salt heat exchange and heat storage system comprises a high-temperature molten salt tank, a medium-temperature molten salt tank, a low-temperature molten salt tank, a high-temperature molten salt heat exchanger, a medium-temperature molten salt heat exchanger and corresponding connecting pipelines;
The high-pressure steam system comprises a high-pressure preheater, a high-pressure evaporator, a high-pressure steam drum, a high-pressure superheater, a high-pressure economizer and corresponding connecting pipelines;
In the low-pressure steam system, an inlet of a deaerator is connected with water supply, an outlet of the deaerator is respectively connected with an inlet of a low-pressure economizer and an inlet of a high-pressure economizer, an outlet of the low-pressure economizer is connected with a water inlet of a low-pressure steam drum, a water outlet of the low-pressure steam drum is respectively connected with an inlet of a flue vaporization heat exchanger, an inlet of a sedimentation chamber vaporization heat exchanger and an inlet of a low-pressure evaporator, an outlet of the flue vaporization heat exchanger, an outlet of the sedimentation chamber vaporization heat exchanger and an outlet of the low-pressure evaporator are connected with a steam-water mixture inlet of the low-pressure steam drum, and a steam outlet of the low-pressure steam drum is connected with an inlet of a heat accumulator;
In the high-pressure steam system, an outlet of a high-pressure economizer is connected with a water inlet of a high-pressure preheater, a water outlet of the high-pressure preheater is connected with a water inlet of a high-pressure steam drum, a water outlet of the high-pressure steam drum is connected with a water inlet of a high-pressure evaporator, an outlet of the high-pressure evaporator is connected with a steam-water mixture inlet of the high-pressure steam drum, a steam outlet of the high-pressure steam drum is connected with a steam inlet of a high-pressure superheater, and a steam outlet of the high-pressure superheater is connected with a power generation system;
In the molten salt heat exchange and storage system, an outlet of a high-temperature molten salt tank is connected with a molten salt inlet of a high-pressure superheater, a molten salt outlet of the high-pressure superheater is connected with a molten salt inlet of a high-pressure evaporator, a molten salt outlet of the high-pressure evaporator is connected with a molten salt inlet of a low-temperature molten salt tank, a molten salt outlet of the low-temperature molten salt tank is connected with an inlet of a medium-temperature molten salt heat exchanger, an outlet of the medium-temperature molten salt heat exchanger is connected with an inlet of the medium-temperature molten salt tank, an outlet of the medium-temperature molten salt tank is connected with an inlet of the high-temperature molten salt heat exchanger, and an outlet of the high-temperature molten salt heat exchanger is connected with an inlet of the high-temperature molten salt tank;
The high-pressure coal-saving device is characterized in that a front flue heat accumulator is arranged in a front flue of the settling chamber, a settling chamber heat accumulator is arranged in the combustion settling chamber, and a high-pressure water storage tank is connected to a connecting pipeline between an outlet of the high-pressure coal-saving device and a water inlet of the high-pressure preheater.
2. The flue gas waste heat deep utilization system of the polymorphic coupling heat storage steelmaking electric furnace according to claim 1, wherein the front flue heat storage body and the sedimentation chamber heat storage body are porous magnesia bricks, porous ceramics or porous precast concrete.
3. The flue gas waste heat deep utilization system of the multi-state coupling heat storage steelmaking electric furnace according to claim 1, wherein the flue vaporization heat exchanger is arranged in a front flue of a settling chamber, and the settling chamber vaporization heat exchanger is arranged in a combustion settling chamber.
4. The flue gas waste heat deep utilization system of the polymorphic coupling heat storage steelmaking electric furnace is characterized in that the high-temperature molten salt heat exchanger, the medium-temperature molten salt heat exchanger, the low-pressure evaporator, the high-pressure economizer and the low-pressure economizer are sequentially arranged in a rear flue of the settling chamber from front to back.
5. The flue gas waste heat deep utilization system of the multi-state coupling heat storage steelmaking electric furnace according to claim 1, wherein the external steam supply superheater is arranged in a low-pressure steam drum.
6. The flue gas waste heat deep utilization system of the polymorphic coupling heat storage steelmaking electric furnace according to claim 1 is characterized in that a low-pressure water supply pump is connected between an outlet of the deaerator and an inlet of the low-pressure economizer, and a high-pressure water supply pump is connected between an outlet of the deaerator and an inlet of the high-pressure economizer.
7. The flue gas waste heat deep utilization system of the polymorphic coupling heat storage steelmaking electric furnace according to claim 1, wherein the high-pressure steam system further comprises a high-temperature molten salt pump, a low-temperature molten salt pump and a medium-temperature molten salt pump, an outlet of the high-temperature molten salt tank is connected with a molten salt inlet of the high-pressure superheater through the high-temperature molten salt pump, a molten salt outlet of the low-temperature molten salt tank is connected with an inlet of the medium-temperature molten salt heat exchanger through the low-temperature molten salt pump, and an outlet of the medium-temperature molten salt tank is connected with an inlet of the high-temperature molten salt heat exchanger through the medium-temperature molten salt pump.
8. The flue gas waste heat deep utilization system of the polymorphic coupling heat storage steelmaking electric furnace according to claim 1, wherein the outlet of the high-temperature molten salt heat exchanger is connected with the inlet of the medium-temperature molten salt tank through a bypass.
9. The multi-state coupling heat storage steelmaking electric furnace flue gas waste heat deep utilization system is characterized by comprising a back pressure turbine and a generator, wherein the back pressure turbine is connected with the generator, a steam outlet of a high-pressure superheater is connected with an inlet of the back pressure turbine, and a steam outlet of the back pressure turbine is connected with a heat user.
10. The flue gas waste heat deep utilization system of the multi-state coupling heat storage steelmaking electric furnace according to claim 1, wherein an outlet of the external steam supply superheater is connected with a heat user.
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