Double-heat-source molten salt boiler structure and heat exchange method

Abstract

The invention relates to a double-heat-source fused salt boiler structure and a heat exchange method, and the double-heat-source fused salt boiler structure comprises a steam superheater which is connected with a high-temperature fused salt pipeline, a first pipeline, a saturated steam pipeline and a superheated steam pipeline; a first mixer inlet and a second mixer inlet are respectively used for connecting a first pipeline and a waste heat molten salt pipeline; the evaporator is respectively connected with the mixer outlet, the second pipeline, the first circulating pipeline and the second circulating pipeline; the economizer is used for being connected with a second pipeline, a third pipeline, a water supply pipeline and a secondary saturated water pipeline. And the steam pocket is connected with the first circulating pipeline, the second circulating pipeline, the secondary saturated water pipeline and the saturated steam pipeline. The steam quality can be effectively improved, and gradient utilization of fused salt energy is effectively achieved.

Description

Technical Field

[0001] The invention relates to the field of boilers, and in particular to a dual-heat-source molten salt boiler structure and a heat exchange method. Background Art

[0002] For dual-heat-source molten salt boilers, the molten salts used as heat sources come from different systems, with different temperatures and flow rates. How to efficiently utilize the thermal energy of molten salts, obtain high-quality steam, and improve the system's exergy efficiency is crucial for molten salt boilers. Existing technologies generally use a single channel, and two molten salts used as heat sources enter the boiler system at the same time, and energy is not reasonably utilized in a cascade. Summary of the invention

[0003] The object of the present invention is to provide a dual-heat source molten salt boiler structure and a heat exchange method, which can effectively improve the quality of steam and effectively realize the cascade utilization of molten salt energy.

[0004] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0005] The present invention provides a dual-heat source molten salt boiler structure, comprising:

[0006] The steam superheater has a superheater molten salt inlet, a superheater molten salt outlet, a saturated steam inlet and a superheated steam outlet, which are respectively used to connect the high-temperature molten salt pipeline, the first pipeline, the saturated steam pipeline and the superheated steam pipeline, and the high-temperature molten salt pipeline is used to transport the high-temperature molten salt;

[0007] The molten salt mixer has a first mixer inlet, a second mixer inlet and a mixer outlet, the first mixer inlet and the second mixer inlet are respectively used to connect the first pipeline and the waste heat molten salt pipeline, and the waste heat molten salt pipeline is used to transport the waste heat molten salt;

[0008] The evaporator has an evaporator molten salt inlet, an evaporator molten salt outlet, a circulating liquid inlet and a circulating liquid outlet, and is respectively used to connect the mixer outlet, the second pipeline, the first circulating pipeline and the second circulating pipeline;

[0009] The economizer has an economizer molten salt inlet, an economizer molten salt outlet, a feed water inlet and a sub-saturated water outlet, and is respectively used to connect the second pipeline, the third pipeline, the feed water pipeline and the sub-saturated water pipeline;

[0010] The steam drum is connected to the first circulation pipeline, the second circulation pipeline, the sub-saturated water pipeline and the saturated steam pipeline.

[0011] In a preferred embodiment of the present invention, the molten salt mixer includes a shell having a mixing chamber, a first mixer inlet and a second mixer inlet are arranged on the shell, a horizontally arranged injection pipe is provided at the top of the mixing chamber, a plurality of injection holes are opened on the side wall of the injection pipe, one end of the injection pipe is a closed end, and the other end is connected to the second mixer inlet.

[0012] In a preferred embodiment of the present invention, the mixer outlet is opened at the bottom of the shell, the evaporator molten salt inlet is arranged at the top of the evaporator, the molten salt mixer is installed on the top of the evaporator, and the mixer outlet and the evaporator molten salt inlet are arranged vertically opposite to each other.

[0013] In a preferred embodiment of the present invention, the dual-heat-source molten salt boiler structure further includes a molten salt furnace, and an outlet of the molten salt furnace is connected to a high-temperature molten salt pipeline.

[0014] In a preferred embodiment of the present invention, the dual-heat-source molten salt boiler structure further includes a low-temperature molten salt tank, and the third pipeline is connected to the low-temperature molten salt tank.

[0015] In a preferred embodiment of the present invention, the outlet of the low-temperature molten salt tank is connected to a first return pipeline, which is connected to the molten salt furnace and is used to return at least part of the low-temperature molten salt in the low-temperature molten salt tank to the molten salt furnace.

[0016] In a preferred embodiment of the present invention, the outlet of the low-temperature molten salt tank is also connected to a second return pipeline, and the second return pipeline is used to connect to the steel plant process equipment to return at least part of the low-temperature molten salt to the steel plant process equipment.

[0017] In a preferred embodiment of the present invention, the temperature of the high-temperature molten salt is 500-580°C, the temperature of the waste heat molten salt is 400-500°C, the temperature of the low-temperature molten salt obtained after heat exchange in the economizer is less than 300°C, and the temperature of the high-temperature superheated steam obtained after heat exchange in the steam superheater is greater than 450°C.

[0018] In a preferred embodiment of the present invention, the waste heat molten salt is obtained by heat exchange of molten salt through steel plant process equipment, and the steel plant process equipment includes the converter flue of the steelmaking plant, the waste heat boiler of steel rolling and the steel rolling process cooling equipment.

[0019] The present invention also provides a heat exchange method for a dual-heat-source molten salt boiler, comprising:

[0020] The high-temperature molten salt is transported to the steam superheater and heat-exchanged with the saturated steam transported to the steam superheater by the steam drum to obtain sub-high-temperature molten salt and high-temperature superheated steam;

[0021] The sub-high temperature molten salt and the waste heat molten salt are transported to a molten salt mixer for mixing to obtain a mixed molten salt;

[0022] The mixed molten salt is transported to the evaporator and heat-exchanged with the saturated water transported to the evaporator by the steam drum to obtain a heat-exchange molten salt and steam-water mixture, and the steam-water mixture is returned to the steam drum;

[0023] The heat exchange molten salt is transported into the economizer and heat-exchanged with the feed water transported into the economizer to obtain low-temperature molten salt and sub-saturated water;

[0024] The sub-saturated water is transported to the steam drum as make-up water.

[0025] As described above, the boiler structure and heat exchange method of the present invention use high-temperature molten salt for the steam superheater, which can heat the saturated steam generated by the drum into high-temperature superheated steam, effectively improving the steam quality and value; it also realizes dual-path molten salt heating. In the first path, the high-temperature molten salt flows through the steam superheater, evaporator and economizer in sequence for heat exchange, and the low-temperature molten salt obtained after heat exchange flows out of the economizer; the second path collects the waste heat molten salt into the molten salt mixer, merges with the second-high temperature molten salt obtained in the first path, and then exchanges heat in the evaporator, and then enters the economizer. The low-temperature molten salt obtained after heat release flows out of the economizer; the energy cascade utilization of waste heat molten salt and high-temperature molten salt is effectively realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0027] in:

[0028] Figure 1 This is a structural schematic diagram of the dual heat source molten salt boiler structure provided by the present invention.

[0029] Description of Figure Numbers:

[0030] 1. Steam superheater; 11. High-temperature molten salt pipeline; 12. First pipeline; 13. Saturated steam pipeline; 14. Superheated steam pipeline;

[0031] 2. Molten salt mixer; 21. Waste heat molten salt pipeline; 22. Injection pipe;

[0032] 3. Evaporator; 31. Second pipeline; 32. First circulation pipeline; 33. Second circulation pipeline;

[0033] 4. Economizer; 41. Third pipeline; 42. Feedwater pipeline; 43. Sub-saturated water pipeline;

[0034] 5. Steam drum;

[0035] 6. Low temperature molten salt tank. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the present application provides a dual-heat source molten salt boiler structure, comprising:

[0038] The steam superheater 1 has a superheater molten salt inlet, a superheater molten salt outlet, a saturated steam inlet and a superheated steam outlet, which are respectively used to connect the high-temperature molten salt pipeline 11, the first pipeline 12, the saturated steam pipeline 13 and the superheated steam pipeline 14. The high-temperature molten salt pipeline 11 is used to transport high-temperature molten salt;

[0039] The molten salt mixer 2 has a first mixer inlet, a second mixer inlet and a mixer outlet, the first mixer inlet and the second mixer inlet are respectively used to connect the first pipeline 12 and the waste heat molten salt pipeline 21, and the waste heat molten salt pipeline 21 is used to transport the waste heat molten salt;

[0040] The evaporator 3 has an evaporator molten salt inlet, an evaporator molten salt outlet, a circulating liquid inlet and a circulating liquid outlet, and is respectively used to connect the mixer outlet, the second pipeline 31, the first circulating pipeline 32 and the second circulating pipeline 33;

[0041] The economizer 4 has an economizer molten salt inlet, an economizer molten salt outlet, a feed water inlet and a sub-saturated water outlet, and is respectively used to connect the second pipeline 31, the third pipeline 41, the feed water pipeline 42 and the sub-saturated water pipeline 43;

[0042] The steam drum 5 is connected to the first circulation pipeline 32 , the second circulation pipeline 33 , the sub-saturated water pipeline 43 and the saturated steam pipeline 13 .

[0043] Therefore, the boiler structure of the present application uses high-temperature molten salt for the steam superheater 1, which can heat the saturated steam generated by the drum 5 into high-temperature superheated steam, effectively improving the steam quality and value; it also realizes dual-path molten salt heating. In the first path, the high-temperature molten salt flows through the steam superheater 1, the evaporator 3 and the economizer 4 in sequence for heat exchange, and the low-temperature molten salt obtained after the heat exchange flows out of the economizer 4; the second path merges the waste heat molten salt into the molten salt mixer 2, merges with the sub-high temperature molten salt obtained in the first path, and then exchanges heat in the evaporator 3, and then enters the economizer 4. The low-temperature molten salt obtained after heat release flows out of the economizer 4; the energy cascade utilization of waste heat molten salt and high-temperature molten salt is effectively realized.

[0044] In a specific implementation, in order to mix the molten salt more evenly, the molten salt mixer 2 includes a shell having a mixing chamber, a first mixer inlet and a second mixer inlet are arranged on the shell, a horizontally arranged injection pipe 22 is provided at the top of the mixing chamber, a plurality of injection holes are opened on the side wall of the injection pipe 22, one end of the injection pipe 22 is a closed end, and the other end is connected to the second mixer inlet.

[0045] Generally, the first mixer inlet is arranged at the top of the shell, and the second mixer inlet is arranged at the side wall of the shell. The aperture of the injection hole is relatively small and evenly distributed. The entire injection pipe 22 constitutes a molten salt injection device, which can disperse the waste heat molten salt to various positions and mix it quickly and evenly with the sub-high temperature molten salt.

[0046] The mixer outlet is opened at the bottom of the shell, the evaporator molten salt inlet is arranged at the top of the evaporator 3, the molten salt mixer 2 is installed on the top of the evaporator 3, and the mixer outlet and the evaporator molten salt inlet are arranged vertically opposite to each other so that the mixed molten salt falls into the evaporator 3 under the action of gravity.

[0047] Furthermore, the dual-heat-source molten salt boiler structure also includes a molten salt furnace, the outlet of which is connected to a high-temperature molten salt pipeline 11 for conveying high-temperature molten salt to the steam superheater 1 .

[0048] The molten salt furnace heats the molten salt by introducing coal gas to obtain high-temperature molten salt. It should be noted that the scheme of this embodiment is mainly applicable to the working condition where the flow rate of high-temperature molten salt is sufficient and saturated steam can be superheated to high-temperature superheated steam alone. Generally, there is surplus coal gas in steel mills. The amount of surplus coal gas determines the amount of high-temperature molten salt that can be obtained using the molten salt furnace. When there is more surplus coal gas in the steel mill, more high-temperature molten salt can be produced by the molten salt furnace, and saturated steam can be heated to high-temperature superheated steam alone.

[0049] Furthermore, the dual-heat source molten salt boiler structure also includes a low-temperature molten salt tank 6 , and the third pipeline 41 is connected to the low-temperature molten salt tank 6 for transporting the low-temperature molten salt obtained after heat exchange in the economizer 4 to the low-temperature molten salt tank 6 .

[0050] Furthermore, in order to realize the recycling of low-temperature molten salt with a relatively low temperature, the outlet of the low-temperature molten salt tank 6 is connected with a first return pipeline, which is connected to the molten salt furnace and is used to return at least part of the low-temperature molten salt in the low-temperature molten salt tank 6 to the molten salt furnace. The outlet of the low-temperature molten salt tank 6 is also connected with a second return pipeline, which is used to connect to the steel plant process equipment to return at least part of the low-temperature molten salt to the steel plant process equipment, so as to heat the low-temperature molten salt again to form waste heat molten salt for recycling.

[0051] In this embodiment, the temperature of the high-temperature molten salt is 500-580° C., the temperature of the waste heat molten salt is 400-500° C., the temperature of the low-temperature molten salt is less than 300° C., and the temperature of the high-temperature superheated steam is greater than 450° C. The waste heat molten salt can also be called medium-temperature molten salt, which can be transported intermittently or continuously according to actual working conditions.

[0052] The waste heat molten salt is obtained by heat exchange of molten salt with steel mill process equipment, and the steel mill process equipment includes the converter flue of the steel mill, the waste heat boiler of steel rolling and the cooling equipment of the steel rolling process. That is, the waste heat molten salt in this embodiment is formed by heat exchange of molten salt with the steel mill process equipment, and the steel mill process equipment transfers the waste heat to the molten salt, so that the molten salt is heated to form a molten salt with waste heat. For example, the steel mill process equipment can be the converter flue of the steel mill, and the molten salt is heat exchanged with the flue gas in the converter flue to obtain the waste heat molten salt; for another example, the steel mill process equipment can also be the waste heat boiler of steel rolling, and the molten salt is heat exchanged with the waste heat of the waste heat boiler to obtain the waste heat molten salt; for another example, the steel mill process equipment can also be the cooling equipment of the steel rolling process, and the molten salt is heat exchanged with the high-temperature material in the equipment to obtain the waste heat molten salt, and at the same time, the cooling effect on the high-temperature material is achieved.

[0053] Generally, the steam superheater 1 and the molten salt mixer 2 are made of high temperature resistant materials, and the evaporator 3 is made of carbon steel pipe. The structure of the steam superheater 1 can be a hairpin type or a shell and tube type.

[0054] In more detail, the working process of the dual heat source molten salt boiler structure in this embodiment is as follows:

[0055] During operation, the high-temperature molten salt obtained at the outlet of the molten salt furnace is transported to the steam superheater 1 through the high-temperature molten salt pipeline 11, heating the saturated steam transported from the steam drum 5 into the steam superheater 1, heating the saturated steam into high-temperature superheated steam, improving the steam quality and After the high temperature molten salt is cooled by heat exchange, it becomes sub-high temperature molten salt.

[0056] The sub-high temperature molten salt is transported to the molten salt mixer 2 through the first pipeline 12, and the waste heat molten salt enters the molten salt mixer 2 through the waste heat molten salt pipeline 21 and the second mixer inlet, and is mixed with the sub-high temperature molten salt. After uniform mixing, a mixed molten salt is obtained, and the mixed molten salt enters the evaporator 3 through the mixer outlet and the evaporator molten salt inlet of the evaporator 3.

[0057] The saturated water in the steam drum 5 enters the evaporator 3 through the first circulation pipeline 32 and the saturated water inlet of the evaporator 3. The mixed molten salt heats the saturated water entering the evaporator 3, so that the saturated water becomes a steam-water mixture and enters the steam drum 5 through the second circulation pipeline 33. The steam-water mixture is separated into steam and water in the steam drum 5. The saturated steam generated after the separation enters the steam superheater 1 through the saturated steam pipeline 13. The saturated water generated after the separation drops to the steam drum 5 and then returns to the evaporator 3 through the first circulation pipeline 32 to enter the next cycle.

[0058] After heat exchange, the mixed molten salt obtains heat exchange molten salt with a lower temperature. The heat exchange molten salt enters the economizer 4 through the third pipeline 41, heats the feed water entering the economizer 4, and the heated feed water becomes sub-saturated water. The sub-saturated water enters the steam drum 5 through the fourth pipeline to replenish the steam drum 5. After heat exchange, the heat exchange molten salt becomes low-temperature molten salt with a lower temperature. The low-temperature molten salt enters the low-temperature molten salt tank 6 through the low-temperature molten salt pipeline.

[0059] Furthermore, the present application also provides a dual-heat-source molten salt boiler heat exchange method, comprising:

[0060] The high-temperature molten salt is transported to the steam superheater 1, and is heat-exchanged with the saturated steam transported to the steam superheater 1 by the steam drum 5, so as to obtain a sub-high-temperature molten salt and a high-temperature superheated steam;

[0061] The sub-high temperature molten salt and the waste heat molten salt are transported to the molten salt mixer 2 for mixing to obtain a mixed molten salt;

[0062] The mixed molten salt is transported to the evaporator 3, and heat exchanged with the saturated water transported to the evaporator 3 by the steam drum 5 to obtain a heat exchange molten salt and a steam-water mixture, and the steam-water mixture is returned to the steam drum 5;

[0063] The heat exchange molten salt is transported to the economizer 4 and heat exchanged with the feed water transported to the economizer 4 to obtain low-temperature molten salt and sub-saturated water;

[0064] The sub-saturated water is transported to the steam drum 5 as makeup water.

[0065] The whole method can effectively improve the quality of steam and realize the energy cascade utilization of molten salts at different temperatures. The method adopts the above-mentioned boiler structure for heat exchange and has the same effect, which will not be repeated here.

[0066] Furthermore, in order to realize the recycling of low-temperature molten salt with a relatively low temperature, the heat exchange method of the dual-heat-source molten salt boiler also includes:

[0067] Transporting low-temperature molten salt to the low-temperature molten salt tank 6;

[0068] At least part of the low-temperature molten salt is transported to the molten salt furnace, and at least part of the low-temperature molten salt is transported to the process equipment of the steel plant.

[0069] The above are only exemplary embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A dual heat source molten salt boiler structure, characterized in that: include: The steam superheater (1) has a superheater molten salt inlet, a superheater molten salt outlet, a saturated steam inlet and a superheated steam outlet, which are respectively used to connect a high-temperature molten salt pipeline (11), a first pipeline (12), a saturated steam pipeline (13) and a superheated steam pipeline (14); the high-temperature molten salt pipeline (11) is used to transport high-temperature molten salt; The molten salt mixer (2) has a first mixer inlet, a second mixer inlet and a mixer outlet, the first mixer inlet and the second mixer inlet are respectively used to connect the first pipeline (12) and the waste heat molten salt pipeline (21), and the waste heat molten salt pipeline (21) is used to transport the waste heat molten salt; The evaporator (3) has an evaporator molten salt inlet, an evaporator molten salt outlet, a circulating liquid inlet and a circulating liquid outlet, and is respectively used to connect the mixer outlet, the second pipeline (31), the first circulating pipeline (32) and the second circulating pipeline (33); The economizer (4) has an economizer molten salt inlet, an economizer molten salt outlet, a feed water inlet and a sub-saturated water outlet, and is respectively used to connect the second pipeline (31), the third pipeline (41), the feed water pipeline (42) and the sub-saturated water pipeline (43); The steam drum (5) is connected to the first circulation pipeline (32), the second circulation pipeline (33), the sub-saturated water pipeline (43) and the saturated steam pipeline (13).

2. The dual heat source molten salt boiler structure according to claim 1, characterized in that: The molten salt mixer (2) comprises a shell having a mixing chamber, the first mixer inlet and the second mixer inlet are arranged on the shell, a horizontally arranged injection pipe (22) is provided at the top of the mixing chamber, a plurality of injection holes are opened on the side wall of the injection pipe (22), one end of the injection pipe (22) is a closed end, and the other end is connected to the second mixer inlet.

3. The dual heat source molten salt boiler structure according to claim 2, characterized in that: The mixer outlet is opened at the bottom of the shell, the evaporator molten salt inlet is arranged at the top of the evaporator (3), the molten salt mixer (2) is installed on the top of the evaporator (3), and the mixer outlet and the evaporator molten salt inlet are arranged vertically opposite to each other.

4. The dual heat source molten salt boiler structure according to claim 1, characterized in that: The dual-heat-source molten salt boiler structure also includes a molten salt furnace, the outlet of which is connected to the high-temperature molten salt pipeline (11).

5. The dual heat source molten salt boiler structure according to claim 4, characterized in that: The dual-heat-source molten salt boiler structure further comprises a low-temperature molten salt tank (6), and the third pipeline (41) is connected to the low-temperature molten salt tank (6).

6. The dual heat source molten salt boiler structure according to claim 5, characterized in that: The outlet of the low-temperature molten salt tank (6) is connected to a first return pipeline, which is connected to the molten salt furnace and is used to return at least part of the low-temperature molten salt in the low-temperature molten salt tank (6) to the molten salt furnace.

7. The dual heat source molten salt boiler structure according to claim 6, characterized in that: The outlet of the low-temperature molten salt tank (6) is also connected to a second return pipeline, and the second return pipeline is used to connect to the steel plant process equipment to return at least part of the low-temperature molten salt to the steel plant process equipment.

8. The dual heat source molten salt boiler structure according to claim 1, characterized in that: The temperature of the high-temperature molten salt is 500-580°C, the temperature of the waste heat molten salt is 400-500°C, the temperature of the low-temperature molten salt obtained after heat exchange in the economizer (4) is less than 300°C, and the temperature of the high-temperature superheated steam obtained after heat exchange in the steam superheater (1) is greater than 450°C.

9. The dual heat source molten salt boiler structure according to claim 1, characterized in that: The waste heat molten salt is obtained by heat exchange of molten salt through steel plant process equipment, and the steel plant process equipment includes the converter flue of the steelmaking plant, the waste heat boiler of steel rolling and the steel rolling process cooling equipment.

10. A dual-heat-source molten salt boiler heat exchange method, characterized in that: include: The high-temperature molten salt is transported into a steam superheater (1) and heat-exchanged with saturated steam transported from a steam drum (5) into the steam superheater (1) to obtain a sub-high-temperature molten salt and high-temperature superheated steam; The sub-high temperature molten salt and the waste heat molten salt are transported to a molten salt mixer (2) for mixing to obtain a mixed molten salt; The mixed molten salt is transported to the evaporator (3) and heat exchanged with the saturated water transported to the evaporator (3) by the steam drum (5) to obtain a heat exchange molten salt and a steam-water mixture, and the steam-water mixture is returned to the steam drum (5); The heat exchange molten salt is transported into the economizer (4) and heat exchanged with the feed water transported into the economizer (4) to obtain low-temperature molten salt and sub-saturated water; The sub-saturated water is transported to the steam drum (5) as make-up water.

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