A combined cooling and heating system for blast furnace slag flushing water and exhaust steam waste heat recovery

Abstract

The present invention discloses a blast furnace slag flushing water and exhaust steam waste heat recovery cold and heat supply system, comprising a cooling and heating module and a waste heat recovery module, the heating module is connected to the waste heat recovery module, the waste heat recovery module comprises a slag water recovery module, a slag flushing exhaust steam recovery module, and a generation module, the slag water recovery module is connected to the slag flushing exhaust steam module and the cooling and heating module, the slag flushing exhaust steam module is connected to the generation module, the generation module realizes circulation through a liquid storage tank, is connected to the slag flushing exhaust steam module, and realizes the cyclic output of exhaust steam waste heat; the slag water recovery module is used to realize the filtration of slag flushing water and the heat exchange of slag water, the slag water heat exchanger realizes circulating water heating, the blast furnace slag flushing exhaust steam generated in the slag water recovery module enters the slag flushing exhaust steam recovery module to realize the recovery and storage of waste heat in the slag flushing exhaust steam, and secondary heats the circulating water to realize high-quality output of circulating water, meet the external cooling and heating needs, and can store condensed water to realize the replenishment of circulating water, thereby improving the utilization rate of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat utilization of blast furnace slag flushing water, and in particular to a combined cooling and heating system for recovering waste heat of blast furnace slag flushing water and exhaust steam. Background Art

[0002] Blast furnace ironmaking produces a large amount of high-temperature slag, which carries huge waste heat. Water quenching is often used to cool the blast furnace slag to ensure the normal operation of the blast furnace system. The heat consumed by this method accounts for more than 15% of the total heat consumption of the blast furnace. During the cooling process, heat loss will be generated, mainly including blast furnace slag water and water vapor evaporation. In order to better utilize heat loss and improve resource utilization, the slag water is usually directly or indirectly exchanged for heat and used to heat heating water during the heating season to realize waste heat recovery of the slag water.

[0003] In the patent document with publication number: CN103173581B, two sets of slag water cooling towers with cold water tanks and cooling tower pump slag water systems are connected in parallel with the heat exchange unit to achieve composite heat extraction of slag water and maximize the recovery of slag water preheating. However, it is difficult to achieve waste heat recovery of heat in water vapor, and it is also impossible to recover waste heat during the non-heating season.

[0004] In the patent document with publication number: CN213624212U, a flash tank is used and low-pressure flash evaporation technology is adopted to avoid pollution, blockage, corrosion and scaling problems caused by the slag water during the heat exchange process. The service life of the equipment is mentioned. At the same time, a steam-type lithium bromide refrigerator is used to realize the waste heat utilization of the slag water in summer, but it is impossible to realize the waste heat recovery of water vapor.

[0005] In the patent document with publication number: CN110375557A, the problem of waste heat application of slag flushing water in winter and summer is solved by taking advantage of the fact that the heating pipe network fully covers thousands of households, but the problem of waste heat recovery of water vapor remains unsolved. Summary of the Invention

[0006] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a blast furnace slag flushing water and exhaust steam waste heat recovery combined heat supply system.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: comprising a cooling and heating module and a waste heat recovery module, wherein the cooling and heating module is connected to the waste heat recovery module;

[0008] The waste heat recovery module includes a slag water recovery module, a slag flushing exhaust steam recovery module, and a generation module;

[0009] The slag water recovery module is connected to the slag flushing exhaust steam recovery module and the cooling and heating module, and the slag flushing exhaust steam recovery module is connected to the generating module;

[0010] The generating module is circulated through the liquid storage tank;

[0011] The generating module is connected to the slag flushing exhaust steam module and is used for circulating the exhaust steam waste heat output.

[0012] As a further description of the above technical solution: the slag water recovery module includes a blast furnace slag flushing water pool, a filter and a slag water heat exchanger, the blast furnace slag flushing water pool is connected to the filter and the slag water heat exchanger in sequence, the outlet end of the slag water heat exchanger is connected to the blast furnace slag flushing water pool and the cooling and heating module respectively, and the blast furnace slag flushing water pool is connected to the slag flushing exhaust steam recovery module.

[0013] As a further description of the above technical solution: the slag flushing exhaust steam module includes an absorption tower, a self-circulating heat exchanger, and a first flash tank. The blast furnace slag flushing exhaust steam discharged from the blast furnace slag flushing water pool enters the absorption tower and directly contacts with the low-temperature solution for heat exchange. The low-temperature exhaust steam after the heat is absorbed is discharged from the absorption tower to the system. The recovered slag flushing exhaust steam heat is heated by the self-circulating heat exchanger to condense steam, and then enters the first flash tank, and is finally sent to the refrigeration and heating module in the form of steam. The high-temperature solution after heat exchange returns to the absorption tower for circulation spraying heat exchange and is discharged to the generation module.

[0014] As a further description of the above technical solution: the generation module includes a liquid storage tank, a second flash tank, an evaporator, a compressor and the condensate tank. The liquid storage tank is connected to the absorption tower through the self-circulating heat exchanger for the circulation of the high-temperature solution.

[0015] As a further description of the above technical solution: the liquid storage tank is connected to the second flash tank through the evaporator, which is used for concentrating the solution. The concentrated solution formed flows into the liquid storage tank. The compressor is connected to the second flash tank and the evaporator to provide power for the external circulation of the generating module. The evaporator condensate formed by the evaporator enters the condensate tank for storage to provide spray water for the steam module and the compressor.

[0016] As a further description of the above technical solution: the liquid generated in the first flash tank flows back to the self-circulating heat exchanger, and the generated exhaust steam reaches the flash exhaust steam heat exchanger through the steam storage tank and is connected to the cooling and heating module.

[0017] As a further description of the above technical solution: the liquid formed by the flash exhaust steam heat exchanger is connected in parallel with the liquid formed in the steam storage tank and input into the condensate heat exchanger, and the condensate is recovered through the condensate heat exchanger and sent to the slag flushing exhaust steam waste heat recovery module.

[0018] As a further description of the above technical solution: the cooling and heating module includes a diversion device, a refrigeration unit, a cooling tower and hot and cold users. The slag water heat exchanger is connected to the diversion device to realize direct supply of circulating water or re-enter the flash exhaust steam heat exchanger for secondary heating according to the actual needs of hot and cold users. The heated circulating water is directly sent to the hot user for heating. When there is a cooling demand, the circulating water is sent to the refrigeration unit to meet the cooling needs of user 19.

[0019] As a further description of the above technical solution: the cooling tower is separately connected to the refrigeration unit, and the user is connected to the refrigeration unit, the diversion device and the flash exhaust steam heat exchanger respectively through the control system to complete cooling or heating according to the different needs of the user.

[0020] The present invention has the following beneficial effects:

[0021] The present invention realizes the waste heat recovery of slag flushing water and slag flushing exhaust steam through the waste heat recovery module, greatly improves the utilization rate of heat generated when cooling high-temperature molten slag, and also utilizes the heat in the generated water vapor, effectively solving the problems of singleness and inefficiency of existing blast furnace slag flushing waste heat recovery; at the same time, it realizes the thermal energy storage effect, effectively conforms to the characteristics of intermittent slag flushing of blast furnaces, and the waste heat recovery module realizes the secondary heating of the cold source, ensures the stable and efficient output of waste heat resources, and realizes the continuous utilization of waste heat in winter and summer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of a blast furnace slag flushing water and exhaust steam waste heat recovery combined heat and cold supply system proposed by the present invention.

[0023] Legend:

[0024] 1. Blast furnace slag flushing water pool; 2. Filter; 3. Slag-water heat exchanger; 4. Absorption tower; 5. Liquid storage tank; 6. Second flash tank; 7. Evaporator; 8. Compressor; 9. Condensate tank; 10. First flash tank; 11. Self-circulating heat exchanger; 12. Condensate heat exchanger; 13. Steam storage tank; 14. Condensate storage tank; 15. Flash exhaust steam heat exchanger; 16. Diverter; 17. Refrigeration unit; 18. Cooling tower; 19. User. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Reference Figure 1 The blast furnace slag exhaust steam generated in the slag water recovery module passes through the slag washing exhaust steam recovery module and the generating module, and the slag water recovery module is connected with the slag washing exhaust steam recovery module and the refrigeration and heating module, and the slag washing exhaust steam module is connected with the generating module, and the generating module realizes circulation through the liquid storage tank 5, and realizes slag washing exhaust steam circulation heat exchange; the slag washing water is filtered and the slag water is heat exchanged through the slag water recovery module, and the circulating water is heated by the slag water heat exchanger 3, and the blast furnace slag washing exhaust steam generated in the slag water recovery module passes through the slag washing exhaust steam recovery module and the generating module to realize the recovery and storage of the waste heat in the slag washing exhaust steam, and secondary heat the circulating water to realize high-quality output of the circulating water, thereby meeting the external cooling and heating requirements, and at the same time being able to store the condensed water, and realize the replenishment of the circulating water, thereby improving the utilization rate of the unit.

[0027] About the cooling and heating process:

[0028] The heating module includes a diverter 16, a refrigeration unit 17 and a cooling tower 18. The slag water heat exchanger 3 is connected to the refrigeration unit 17 through the diverter 16 and the flash exhaust steam heat exchanger 15. The cooling tower 18 is separately connected to the refrigeration unit 17. The user 19 is separately connected to the refrigeration unit 17, the diverter 16 and the flash exhaust steam heat exchanger 15.

[0029] About heating mode:

[0030] When heating is required in winter, the circulating water is first preheated to temperature T0 through the slag-water heat exchanger 3. According to the actual heat load demand of the heat user 19, if the circulating water temperature T0 can meet the heating demand of the user 19, the diversion device 16 is opened and the circulating water is directly sent to the heat user 19 for heating; if the circulating water temperature T0 cannot meet the heating demand of the user 19, the circulating water after heat exchange in the slag-water heat exchanger 3 enters the flash exhaust steam heat exchanger 15 for secondary heating to temperature T1, thereby realizing a stable and continuous output of the waste heat source and solving the problem of intermittent slag discharge in the blast furnace (it should be noted that the set temperature of temperature T0 and temperature T1 can be changed according to different regions or different needs, so as to better meet different usage needs).

[0031] About cooling mode:

[0032] When cooling is required in summer, the circulating water is first preheated by the slag water heat exchanger 3, and then heated to a higher temperature by the flash exhaust steam heat exchanger 15, and sent to the refrigeration unit 17 as a driving heat source to heat the neutral inorganic salt solution in the generator to achieve solution concentration. The evaporated low-pressure steam is condensed by cooling water in the condenser, and the condensed water is sent to the evaporator of the refrigeration unit 17 to release pressure and vaporize to absorb heat, which is used to cool the refrigerated water. It is then sent to the cold user 19 for refrigeration. The excess heat input by the refrigeration unit 17 is sent to the cooling tower 18 through cooling water for heat dissipation.

[0033] The system can achieve the combined effects of cooling and heating at the same time, and adjust the operating mode according to the needs of users19, which can effectively extend the operating time of the system and greatly reduce the limitations of regional characteristics on the recovery of waste heat from blast furnace slag flushing water, thereby improving the utilization rate of the unit.

[0034] About the waste heat recovery process of slag flushing water:

[0035] The slag water recovery module includes a blast furnace slag flushing water pool 1, a filter 2 and a slag water heat exchanger 3. The blast furnace slag flushing water pool 1 is connected to the filter 2 and the slag water heat exchanger 3 in sequence. The outlet end of the slag water heat exchanger 3 is connected to the blast furnace slag flushing water pool 1 and the heating module respectively. The blast furnace slag flushing water pool 1 is connected to the slag flushing exhaust steam recovery module;

[0036] The slag flushing water is drawn from the blast furnace slag flushing pool 1 and sent to the filter 2 to filter out the slag cotton, water slag and other particulate matter generated in the slag flushing process. The filtered slag flushing water is sent to the slag water heat exchanger 3 for heat exchange with the circulating water. The slag flushing water cooled by heat exchange is then sent back to the blast furnace slag flushing pool 1 to continue cooling the blast furnace slag. The heated slag flushing water is then sent to the filter 2 and the slag water heat exchanger 3 to complete the cycle.

[0037] About the slag flushing exhaust steam recovery system:

[0038] The slag flushing exhaust steam module includes an absorption tower 4. The blast furnace slag flushing exhaust steam discharged from the blast furnace slag flushing water pool 1 enters the absorption tower 4. The low-temperature exhaust steam after heat is absorbed is discharged from the absorption tower 4 to the system. The recovered slag flushing exhaust steam heat is heated by the self-circulating heat exchanger 11 to heat the steam condensate, and then enters the first flash tank 10, and is finally sent to the refrigeration and heating module in the form of steam. The high-temperature solution after heat exchange returns to the absorption tower 4 for circulated spraying heat exchange and is discharged to the generation module.

[0039] The exhaust steam from the slag flushing water enters the absorption tower 4 and conducts heat and mass transfer through direct contact with the spray solution in the tower. The water vapor in the exhaust steam dissolves in the solution and releases latent heat of vaporization. The exhaust steam after treatment is finally discharged in an unsaturated state. A large amount of water vapor and some particulate matter contained in the exhaust steam from the slag flushing water directly contact with the highly hygroscopic solution in the absorption tower 4, so that the moisture and particulate matter are absorbed, and the visual white smoke of the discharged unsaturated exhaust steam is weakened. At the same time, the degree of chimney corrosion by the exhaust steam is reduced, and the exhaust steam is purified.

[0040] About the solution process of slag flushing exhaust steam:

[0041] Solution external circulation:

[0042] The generating module includes a liquid storage tank 5, a second flash tank 6, an evaporator 7, a compressor 8 and a condensate tank 9. The liquid storage tank 5 is connected to the second flash tank 6 through the evaporator 7 for concentrating the solution. The concentrated solution formed flows into the liquid storage tank 5. The compressor 8 is connected to the second flash tank 6 and the evaporator 7 to pressurize and improve the steam discharged from the second flash tank 6, providing driving force for the external circulation of the generating module. The evaporated condensate formed by the evaporator 7 enters the condensate tank 9 for storage, providing spray water for the steam module and the compressor 8.

[0043] The dilute solution in the liquid storage tank 5 is pumped into the evaporator 7, and the steam pressurized and upgraded by the compressor 8 is used as the driving heat source. The solution absorbs the heat of the driving steam in the evaporator 7 and becomes a gas-liquid mixture, and then enters the second flash tank 6 to concentrate the solution. The concentrated solution after flash evaporation is collected from the bottom of the second flash tank 6 into the liquid storage tank 5, and the exhaust steam from the flash evaporation is discharged from the top of the second flash tank 6.

[0044] Solution self-circulation:

[0045] The liquid storage tank 5 is connected to the absorption tower 4 through a self-circulating heat exchanger 11 for the circulation of high-temperature solution;

[0046] The high-temperature solution after heat exchange with the exhaust steam of slag flushing water falls into the bottom of the absorption tower 4 and then flows into the liquid storage tank 5, and is then sent to the self-circulating heat exchanger 11 for heat exchange. After releasing heat, the solution enters the absorption tower 4 for spraying, contacts with the flue gas in countercurrent, and then falls back to the bottom of the tower to complete the cycle.

[0047] About the circulating water process of slag flushing exhaust steam:

[0048] The liquid formed in the flash exhaust steam heat exchanger 15 is connected in parallel with the liquid formed in the steam storage tank 13 and then input into the condensate heat exchanger 12, which is connected to the generating module;

[0049] The circulating water is first preheated by the slag water heat exchanger 3 and then sent to the flash exhaust steam heat exchanger 15 for secondary heating. The circulating water after secondary heating has two operating modes, winter and summer. In winter, the circulating water is directly sent to the heat user 19 for heating, and returns along the original route after heat dissipation and cooling; in summer, the circulating water is led into the refrigeration unit 17 as a driving heat source, and returns along the original route after cooling (it should be noted that the control system and pipelines used to connect the user 19 and the refrigeration unit 17, the diverter device 16 and the flash exhaust steam heat exchanger 15 are all existing mature technologies and are not the content of improvement of this solution, so they will not be described in detail).

[0050] About the steam process of slag flushing exhaust steam:

[0051] The steam module includes a first flash tank 10, a steam storage tank 13, a flash exhaust steam heat exchanger 15, a condensate storage tank 14 and a condensate heat exchanger 12. The liquid produced in the first flash tank 10 flows back to the self-circulating heat exchanger 11, and the exhaust steam produced passes through the steam storage tank 13 to the flash exhaust steam heat exchanger 15 and is connected to the heating module;

[0052] The flash exhaust steam generated by the first flash tank 10 is first sent to the steam storage tank 13 for energy storage, and then sent to the flash exhaust steam heat exchanger 15 for heat exchange with circulating water for condensation. The flash exhaust steam condensate is first collected in the condensate storage tank 14, and then sent to the condensate heat exchanger 12 for preheating. The preheated steam condensate is sent to the self-circulating heat exchanger 11 for secondary heating and then sent to the first flash tank 10. The flash exhaust steam is sent to the steam storage tank 13 to complete the cycle.

[0053] The flash exhaust steam generated by the second flash tank 6 is heated and pressurized by the compressor 8, and then sprayed with a small amount of condensate to a saturated state, and then becomes driving steam and enters the evaporator 7, where it transfers heat to the solution and is cooled to condensate, which enters the condensate tank 9;

[0054] Through this system, the problems of discontinuous blast furnace slag discharge and band-wave output of waste heat quality in the field of waste heat recovery are solved. An open absorption heat pump is used to absorb the waste heat of the exhaust steam from blast furnace slag discharge, and the absorbed heat is stored in the form of steam. When the waste heat of the front-end slag flushing water cannot meet the heat demand of user 19, the stored exhaust steam heat can be used to secondary heat the cold source to achieve the effect of thermal peak regulation, effectively ensuring the stability and efficiency of the system's output heat (it should be noted that in this solution, the flow direction of water vapor or liquid is indicated by arrows. In the accompanying drawings, the schematic diagrams of pipelines and some valves are omitted. At the same time, a water pump is provided at the liquid storage tank 5 to provide power for the flow of liquid. Since pipelines, valves and open absorption heat pumps are existing mature technologies, they will not be described in detail).

[0055] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A blast furnace slag flushing water and exhaust steam waste heat recovery combined cooling and heating system, characterized by: It includes a cooling and heating module and a waste heat recovery module, and the cooling and heating module is connected to the waste heat recovery module; The waste heat recovery module includes a slag water recovery module, a slag flushing exhaust steam recovery module, and a generation module; The slag water recovery module is connected to the slag flushing exhaust steam recovery module and the cooling and heating module, and the slag flushing exhaust steam recovery module is connected to the generating module; The generating module realizes circulation through the liquid storage tank; The generating module is connected to the slag flushing exhaust steam recovery module to maintain a constant concentration of the system solution, and to realize the cyclic output of the exhaust steam waste heat through direct contact heat exchange between the circulating solution and the slag flushing exhaust steam; The slag water recovery module comprises a blast furnace slag flushing water pool, a filter and a slag water heat exchanger, the blast furnace slag flushing water pool is connected to the filter and the slag water heat exchanger in sequence, the outlet end of the slag water heat exchanger is connected to the blast furnace slag flushing water pool and the cooling and heating module respectively, and the blast furnace slag flushing water pool is connected to the slag flushing exhaust steam recovery module; The slag washing exhaust steam recovery module includes an absorption tower, a self-circulating heat exchanger, a first flash tank and a condensate heat exchanger. The blast furnace slag washing exhaust steam discharged from the blast furnace slag washing water pool enters the absorption tower and directly contacts with the low-temperature solution for heat exchange. The low-temperature exhaust steam after heat absorption is discharged from the absorption tower. The recovered slag washing exhaust steam heats the steam condensate through the self-circulating heat exchanger and then enters the first flash tank. It is finally sent to the cooling and heating module in the form of steam. The high-temperature solution after heat exchange returns to the absorption tower for cyclic spray heat exchange. The generation module comprises a liquid storage tank, a second flash tank, an evaporator, a compressor and a condensate tank, wherein the liquid storage tank is connected to the absorption tower via the self-circulating heat exchanger for the circulation of the high-temperature solution; The liquid storage tank is connected to the second flash tank via the evaporator for concentrating the solution. The concentrated solution is collected in the liquid storage tank. The compressor is connected to the second flash tank and the evaporator to pressurize and improve the quality of the steam discharged from the second flash tank, thereby providing driving force for the external circulation of the generating module. The evaporator condensate formed by the evaporator enters the condensate tank for storage, thereby providing spray water for the steam module and the compressor. The steam module includes a first flash tank, a steam storage tank, a flash exhaust steam heat exchanger, a condensate storage tank and a condensate heat exchanger.

2. A blast furnace slag flushing water and exhaust steam waste heat recovery combined cooling and heating system according to claim 1, characterized in that: The liquid generated in the first flash tank flows back to the self-circulating heat exchanger, and the generated exhaust steam passes through the steam storage tank to reach the flash exhaust steam heat exchanger and is connected to the cooling and heating module.

3. The blast furnace slag flushing water and exhaust steam waste heat recovery and combined cooling and heating system according to claim 1 is characterized in that: The liquid formed by the flash exhaust steam heat exchanger is connected in parallel with the liquid formed in the steam storage tank and then input into the condensate heat exchanger, through which the condensate heat is recovered and connected to the blast furnace slag flushing exhaust steam waste heat recovery module.

4. A blast furnace slag flushing water and exhaust steam waste heat recovery and combined cooling and heating system according to claim 1, characterized in that: The cooling and heating module includes a diversion device, a refrigeration unit, a cooling tower and cold and hot users. The slag water heat exchanger is connected to the diversion device. According to the actual needs of the cold and hot users, the circulating water is directly supplied or re-enters the flash exhaust steam heat exchanger for secondary heating. The heated circulating water is directly sent to the hot user for heating. When there is a cooling demand, the circulating water is sent to the refrigeration unit to meet the user's cooling needs.

5. A blast furnace slag flushing water and exhaust steam waste heat recovery and combined cooling and heating system according to claim 4, characterized in that: The cooling tower is separately connected to the refrigeration unit, and the user is connected to the refrigeration unit, the diversion device and the flash exhaust steam heat exchanger respectively through a control system to complete cooling or heating according to the different needs of the user.

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