A system that uses the waste heat from blast furnace slag flushing water to preheat the feedwater of the converter waste heat boiler deaerator.

Abstract

This utility model discloses a system for preheating the feedwater of the converter waste heat boiler deaerator using waste heat from blast furnace slag flushing. The system includes a slag water tank, a slag water heat exchanger, a hot water storage tank, a demineralized water heater, and a deaerator. The slag water tank holds the blast furnace slag flushing water and is connected to the slag water heat exchanger via a slag water pump. The hot water storage tank is connected to the slag water heat exchanger via a pump, and the circulating water in the storage tank exchanges heat with the blast furnace slag flushing water. The heated circulating water is stored in the storage tank. The hot water outlet of the storage tank is connected to the demineralized water heater for heating the demineralized water, which is then stored in the deaerator. By preheating the demineralized water from the converter waste heat boiler, steam consumption in the deaerator can be reduced, directly optimizing energy consumption in the steelmaking process.

Description

Technical Field

[0001] This utility model relates to the field of deaeration technology for feedwater in steelmaking converter waste heat boilers, and in particular to a system for preheating feedwater in a converter waste heat boiler using waste heat from blast furnace slag flushing water. Background Technology

[0002] The statements herein provide only background information related to this invention and do not necessarily constitute prior art.

[0003] During the operation of a converter waste heat boiler, dissolved oxygen is the main cause of corrosion in thermal equipment such as boilers and turbines. Installing a deaerator removes dissolved oxygen and other gases from the boiler feedwater by heating it, thus preventing corrosion. Simultaneously, heating the feedwater to a certain temperature improves thermal efficiency. Furthermore, the deaerator can also serve as a buffer container for the feedwater system. Currently, the deaerator heats ambient temperature demineralized water, consuming high-quality steam generated by the converter waste heat boiler.

[0004] Blast furnace slag flushing water refers to the water used to cool high-temperature slag during the blast furnace ironmaking process. It mainly involves rapidly cooling and breaking down the high-temperature liquid slag into water slag through water quenching. This process not only consumes a large amount of water resources but also releases a significant amount of heat.

[0005] The technology for utilizing waste heat from blast furnace slag flushing water has been widely applied in centralized heating systems in northern China. However, during the non-heating season or in most southern regions, blast furnace slag flushing water is generally not recycled, resulting in a significant waste of waste heat resources. Utility Model Content

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a system that utilizes the waste heat from blast furnace slag flushing water to preheat the feedwater of the deaerator in a converter waste heat boiler. This system effectively recovers the waste heat from blast furnace slag flushing water for preheating the feedwater in the deaerator of the steelmaking converter waste heat boiler, reducing deaerator steam consumption. The saved steam can then be used for power generation or other processes. This system improves the utilization rate of blast furnace slag flushing water waste heat, enhances steelmaking production efficiency, and boasts high feasibility, a fast payback period, and low implementation difficulty.

[0007] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0008] A system for preheating feedwater to a converter waste heat boiler deaerator using waste heat from blast furnace slag flushing water includes a slag water tank, a slag water heat exchanger, a hot water storage tank, a demineralized water heater, and a deaerator.

[0009] As part of the slag treatment system, the slag water pool contains blast furnace flushing water and is connected to the slag water heat exchanger via a slag water pump. The hot water storage tank is connected to the slag water heat exchanger via a pump, and uses the circulating water in the hot water storage tank to exchange heat with the blast furnace flushing water. The heated circulating water is then stored in the hot water storage tank.

[0010] The hot water outlet of the hot water storage tank is connected to the demineralized water heater to heat the demineralized water, which is then stored in the deaerator.

[0011] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0012] Because the temperature of the blast furnace flushing water fluctuates continuously during blast furnace slag removal, it is higher when slag removal begins and lower during periods when slag removal stops. Without heat storage, the temperature at which the demineralized water is heated decreases when the slag water temperature is low, increasing deaerator steam consumption. However, the heat generated by the slag water during slag removal is far greater than the heat required for demineralized water. Therefore, installing a hot water storage tank to store heat during the slag removal phase and using the high-temperature water in the tank to heat the demineralized water during non-slag removal periods can improve the utilization rate of the slag water.

[0013] Preheating the demineralized water in the converter waste heat boiler can reduce steam consumption in the deaerator and directly optimize energy consumption in the steelmaking process. Attached Figure Description

[0014] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0015] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0016] Figure 2 This is a schematic diagram of the water distributor according to an embodiment of the present invention.

[0017] In the diagram: 1. Deaerator; 2. First valve; 3. Second valve; 4. Third valve; 5. Absorption heat pump; 6. Fourth valve; 7. Fifth valve; 8. Sixth valve; 9. Demineralized water heater; 10. First heat medium water circulation pump; 11. Hot water storage tank; 12. Sludge-water heat exchanger; 13. Siphon tank; 14. Sludge-water pump; 15. Second heat medium water circulation pump; 16. First steam valve; 17. Second steam valve; 18. Sludge-water pool. Detailed Implementation

[0018] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] A system for preheating feedwater to a converter waste heat boiler deaerator using waste heat from blast furnace slag flushing water includes a slag water tank, a slag water heat exchanger, a hot water storage tank, a demineralized water heater, and a deaerator.

[0020] As part of the slag treatment system, the slag water tank contains slag flushing water and is connected to the slag water heat exchanger via a slag water pump. The hot water storage tank is connected to the slag water heat exchanger via a pump, and the circulating water in the hot water storage tank exchanges heat with the blast furnace slag flushing water. The heated circulating water is then stored in the hot water storage tank.

[0021] The hot water outlet of the hot water storage tank is connected to the demineralized water heater to heat the demineralized water, which is then stored in the deaerator.

[0022] The circulating water in the hot water storage tank exchanges heat with the blast furnace slag flushing water, which can effectively recover the waste heat in the blast furnace slag flushing water and store it in the hot water storage tank. When it is necessary to heat the demineralized water, the hot water in the hot water storage tank can be used to heat the demineralized water. On the one hand, this can ensure the stability of the heating temperature of the demineralized water, thereby ensuring the stability of boiler operation and effectively reducing boiler energy consumption. On the other hand, it can also remove dissolved oxygen and gases from the demineralized water to effectively prevent corrosion of thermal equipment.

[0023] Slag slurry passes through a siphon tank and slag slurry pump into a slag slurry heat exchanger to exchange heat with the heat transfer medium. The cooled slag slurry then returns to the original slag slurry pool to mix with the high-temperature water from the blast furnace slag flushing process, and is heated again. Low-temperature heat transfer medium water at the bottom of the hot water storage tank enters the slag slurry heat exchanger via a second heat transfer medium water circulation pump to exchange heat with the slag slurry. The heated high-temperature heat transfer medium water then enters the upper part of the hot water storage tank. The high-temperature heat transfer medium water at the top of the hot water storage tank exchanges heat with the demineralized water in a demineralized water heater. After a first cooling process, the heat transfer medium water enters the absorption heat pump for further cooling before finally entering the lower part of the hot water storage tank. Demineralized water first exchanges heat with the heat transfer medium in the demineralized water heater. After primary heating, the demineralized water enters the absorption heat pump for a second heating process before finally entering the deaerator. Within the absorption heat pump, the heat from the steam and heat transfer medium water is converted to heat the demineralized water.

[0024] In some embodiments, a siphon tank is connected between the sludge tank and the sludge pump. The pump is installed above the sludge level; without a siphon tank, the height difference would exceed the pump's net positive suction head (NPSH), preventing the pump from drawing the sludge.

[0025] In some embodiments, the heat medium outlet of the slag-water heat exchanger is connected to the slag-water tank.

[0026] The heat medium inlet and outlet of the slag water heat exchanger are both connected to the slag water pool, so that the high-temperature blast furnace slag flushing water circulates through the slag water heat exchanger to ensure that the waste heat in the blast furnace slag flushing water is fully recovered and utilized.

[0027] Preferably, the height-to-diameter ratio of the hot water storage tank is greater than 2:1. This can improve the heat storage efficiency of the tank, enabling it to obtain a stable and as thin as possible inclined temperature layer, which divides the hot water storage tank into hot water and cold water areas.

[0028] Preferably, the hot water storage tank is equipped with a water distributor located at the top and bottom of the tank. The water distributor adopts an octagonal water distribution plate structure, which can greatly enhance the stratification of hot and cold water in the tank.

[0029] The designed water head velocity is less than 0.3 m / s, and the designed inclined temperature layer thickness is 0.3-0.8 m.

[0030] Preferably, it also includes an absorption heat pump, wherein the circulating water outlet of the demineralized water heater is connected to the circulating water inlet of the absorption heat pump, and the circulating water outlet of the absorption heat pump is connected to the side wall of the cold water area of ​​the hot water storage tank.

[0031] The demineralized water outlet of the demineralized water heater is connected to the demineralized water inlet of the absorption heat pump, and the demineralized water outlet is connected to the deaerator.

[0032] The higher-temperature circulating water exchanges heat with the demineralized water in the demineralized water heater, heating the demineralized water once before entering the absorption heat pump, where the circulating water exchanges heat with the demineralized water a second time to effectively increase the temperature of the demineralized water.

[0033] The cooled circulating water enters the cold water zone of the hot water storage tank, while the heated demineralized water enters the deaerator.

[0034] Preferably, both the absorption heat pump and the deaerator are connected to a steam pipeline. Steam is used to supplement the heating of the demineralized water.

[0035] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0036] like Figure 1 As shown, a system for preheating boiler deaerator feedwater using waste heat from blast furnace slag flushing water includes a slag water tank 18, a slag water heat exchanger 12, a hot water storage tank 11, a demineralized water heater 9, and a deaerator 1.

[0037] The slag water tank 18 is used to hold the blast furnace flushing slag water. It is connected to the slag water heat exchanger 12 through the slag water pump 14. A siphon tank 13 is connected between the slag water tank 18 and the slag water pump 14. The heat medium outlet of the slag water heat exchanger 12 is connected to the slag water tank 18. The hot water storage tank 11 is connected to the slag water heat exchanger 12 through the second heat medium water circulation pump 15. The circulating water in the hot water storage tank 11 exchanges heat with the blast furnace flushing slag water. The heated circulating water is stored in the hot water storage tank 11.

[0038] The hot water outlet of the hot water storage tank 11 is connected to the demineralized water heater 9 through the first heat medium water circulation pump 10, which is used to heat the demineralized water. The heated demineralized water is stored in the deaerator 1.

[0039] The hot water storage tank 11 is divided into a hot water area and a cold water area by a temperature-sloping layer. The cold medium outlet of the sludge-water heat exchanger is connected to the side wall of the hot water area, and the cold medium inlet is connected to the side wall of the cold water area. The side wall of the hot water storage tank is an insulation board. The height-to-diameter ratio of the hot water storage tank is greater than 2:1.

[0040] The hot water storage tank is equipped with a water distributor located at the top and bottom of the tank. The water distributor has an octagonal water distribution plate with evenly distributed spray holes. Figure 2 As shown.

[0041] It also includes an absorption heat pump, wherein the circulating water outlet of the demineralized water heater is connected to the circulating water inlet of the absorption heat pump, and the circulating water outlet of the absorption heat pump is connected to the side wall of the cold water area of ​​the hot water storage tank.

[0042] The demineralized water outlet of the demineralized water heater is connected to the demineralized water inlet of the absorption heat pump, and the demineralized water outlet is connected to the deaerator. Both the absorption heat pump and the deaerator are connected to a steam pipeline, which is equipped with a first steam valve 16 and a second steam valve 17 to control the steam flow rate and whether steam is introduced.

[0043] The slag water heat exchanger can be one or more units, and can adopt a multi-process heat exchanger for blast furnace slag flushing water with application number 201310067758.2, in order to solve the problems of easy clogging, easy scaling and easy corrosion of blast furnace slag flushing water.

[0044] To achieve heat storage in the hot water storage tank, the heat exchange capacity of the slag-water heat exchanger is designed to be more than twice that of the demineralized water heater, ensuring that the input heat of the hot water storage tank during slag discharge is greater than the output heat, and that the stored heat meets the requirements of the slag flushing interval.

[0045] The demineralized water heater 9 is one or more units used to heat the demineralized water with heat transfer medium. It adopts a detachable plate heat exchanger, which can isolate the corrosive blast furnace slag flushing water from the demineralized water, and avoid direct pollution of the demineralized water quality when the slag water heat exchanger leaks, thus affecting the service life of the waste heat boiler.

[0046] The absorption heat pump 5 is a steam-driven lithium bromide heat pump. It utilizes the waste heat from the primary heat transfer medium water return and the existing heating steam from deaerator 1 to heat the demineralized water to 90-95℃ on top of the primary heating. By leveraging the performance of this heat pump, it can recover heat from the low-temperature heat transfer medium water while consuming steam, further reducing the steam consumption of deaerator 1. The condensate from the heat pump steam is piped to the plant's condensate network for recycling.

[0047] The first steam valve 16 and the second steam valve 17 are electrically adjustable, and their opening degree is adjusted in real time according to the steam demand of the absorption heat pump and deaerator to regulate the steam flow.

[0048] The system is equipped with valves 2 (first valve), 3 (second valve), 4 (third valve), 6 (fourth valve), 7 (fifth valve), and 8 (sixth valve). All of these valves are electrically operated. When the primary heating heat exchanger and the secondary heating heat pump of the demineralized water malfunction, the waste heat return water system can be quickly switched off to restore the original operating mode of the unit, ensuring the safety of converter production.

[0049] The above system is used to recover waste heat from slag flushing water, including the following steps: After filling the hot water storage tank 11 and the siphon tank 13 with water, the slag water pump 14 and the second heat medium water circulation pump 15 are turned on. The slag water at 75°C enters the slag water heat exchanger 12 and exchanges heat with the heat medium water to reduce the temperature to 60°C. Then it returns to the slag water pool 18, mixes with the high-temperature slag water from slag flushing, and then enters the slag water heat exchanger 12. This cycle is repeated.

[0050] The initial 20°C hot water in the hot water storage tank 11 is heated to 70°C by the slag-water heat exchanger 12 before entering the upper part of the hot water storage tank 11. Once the temperature gradient of the water in the hot water storage tank 11 is in the middle of the tank, the first hot water circulation pump 10 is turned on, and the first valve 2, third valve 4, fourth valve 6, sixth valve 8, and first steam valve 16 are opened. The second valve 3 and fifth valve 7 are closed. The 70°C hot water enters the demineralized water heater 9 and exchanges heat with the demineralized water, reducing its temperature to 40°C. It then enters the absorption heat pump 5 for a second cooling to 30°C, and finally returns to the lower part of the hot water storage tank 11. The 20°C demineralized water first enters the demineralized water heater 9 and is heated to 65°C by the hot water. It then enters the absorption heat pump 5 and is heated to 90°C before entering the deaerator 1, where it is heated to the saturation temperature corresponding to the deaeration pressure.

[0051] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A system for preheating the feedwater of a converter waste heat boiler deaerator by using the blast furnace slag flushing water waste heat, characterized in that: This includes a sludge tank, a sludge heat exchanger, a hot water storage tank, a demineralized water heater, and a deaerator; The slag water tank is used to hold the blast furnace slag flushing water, and it is connected to the slag water heat exchanger through a slag water pump; the hot water storage tank is connected to the slag water heat exchanger through a pump, and the circulating water in the hot water storage tank exchanges heat with the blast furnace slag flushing water, and the heated circulating water is stored in the hot water storage tank. The hot water outlet of the hot water storage tank is connected to the demineralized water heater to heat the demineralized water, which is then stored in the deaerator.

2. The system for preheating the deaerator feedwater of a converter waste heat boiler using waste heat from blast furnace slag flushing water as described in claim 1, characterized in that: A siphon tank connects the slag water tank and the slag water pump.

3. The system for preheating the deaerator feedwater of the converter waste heat boiler by using the blast furnace sludge water waste heat according to claim 1, characterized in that: The heat medium outlet of the slag-water heat exchanger is connected to the slag-water pool.

4. The system for preheating the deaerator feedwater of the converter waste heat boiler by using the blast furnace sludge water waste heat according to claim 1, characterized in that: The side walls of the hot water storage tank are made of insulation board.

5. The system for preheating the deaerator feedwater of the converter waste heat boiler by using the blast furnace sludge flushing water waste heat according to claim 4, characterized in that: The height-to-diameter ratio of the hot water storage tank is greater than 2:

1.

6. The system for preheating the deaerator feedwater of the converter waste heat boiler by using the blast furnace sludge flushing water waste heat according to claim 4, characterized in that: The hot water storage tank is equipped with a water distributor located at the top and bottom of the tank.

7. The system for preheating the deaerator feedwater of a converter waste heat boiler using waste heat from blast furnace slag flushing water as described in claim 6, characterized in that: The water distributor has a water distribution plate with spray holes distributed on it.

8. The system for preheating the deaerator feedwater of the converter waste heat boiler by using the blast furnace sludge water waste heat according to claim 1, characterized in that: It also includes an absorption heat pump, wherein the circulating water outlet of the demineralized water heater is connected to the circulating water inlet of the absorption heat pump, and the circulating water outlet of the absorption heat pump is connected to the side wall of the cold water area of ​​the hot water storage tank.

9. The system for preheating the deaerator feedwater of the converter waste heat boiler by using the blast furnace sludge flushing water waste heat according to claim 8, characterized in that: The demineralized water outlet of the demineralized water heater is connected to the demineralized water inlet of the absorption heat pump, and the demineralized water outlet is connected to the deaerator.

10. The system for preheating the deaerator feedwater of a converter waste heat boiler using waste heat from blast furnace slag flushing water according to claim 9, characterized in that: Both the absorption heat pump and the deaerator are connected to the steam pipeline.

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