An integrated heat exchange circulation system for low-grade waste heat steam

Abstract

The present invention discloses an integrated heat exchange circulation system for low-grade waste heat steam, comprising a tank body and a steam collecting layer, a molten salt heat exchanger in the middle, and a water collecting layer at the bottom, each of which is respectively arranged above the interior of the tank body. A steam inlet pipe is provided above the tank body, the steam collecting layer and the water collecting layer are connected via a first pipe, and the water collecting layer is connected to the user end via a second pipe; the lower part of the water collecting layer is connected to a plurality of condensate booster pumps connected in parallel via a water outlet pipe, and each condensate booster pump is connected to the heat exchanger via an inlet pipe. The present invention effectively stores low-grade waste heat steam in the steam pipe while integrating multiple devices and equipment into one, taking up little space and reducing costs; at the same time, the integrated system improves the efficiency of heat exchange and energy storage, improves economic benefits, and has promotion value.

Description

Technical Field

[0001] The present invention relates to steam energy storage, and in particular to a low-grade waste heat steam integrated heat exchange circulation system. Background Art

[0002] Existing molten salt heat storage technology stores high-grade steam or electricity as heat sources, but cannot store heat from low-grade steam heat sources. Steam energy storage technology for low-grade heat sources does not currently exist on the market. Many low-grade heat sources are directly discharged because they cannot be effectively utilized, resulting in waste.

[0003] Phase change thermal storage technology, which utilizes the phase change of a medium to absorb and release large amounts of heat, offers advantages over sensible heat storage, such as smaller equipment, higher heat storage density, and lower storage costs. Currently, low-temperature phase change thermal storage technology is widely used to produce hot water for residential and commercial heating purposes. However, medium- and high-temperature phase change thermal storage technology has not been widely adopted due to technical bottlenecks.

[0004] In existing steam heat storage systems, each device and equipment is separate, taking up a large space and increasing costs. In addition, multiple devices and equipment cannot utilize steam heat exchange energy in a timely and efficient manner, resulting in low energy storage efficiency. Summary of the Invention

[0005] The present invention provides an integrated heat exchange circulation system for low-grade waste heat steam, which effectively stores low-grade waste heat steam in the steam pipeline while integrating multiple devices and equipment into one, taking up little space and reducing costs; at the same time, the integrated system improves the efficiency of heat exchange and energy storage, increases economic benefits, and has promotion value.

[0006] The technical solution adopted by the present invention is:

[0007] A low-grade waste heat steam integrated heat exchange circulation system, comprising a tank body and a steam collecting layer, a molten salt heat exchanger in the middle and a water collecting layer at the bottom, respectively arranged on the upper part of the tank body; a steam inlet pipe is arranged on the top of the tank body, the steam collecting layer and the water collecting layer are communicated with each other through a first pipe, and the water collecting layer is connected to the user end through a second pipe; the lower part of the water collecting layer is connected to a plurality of condensate booster pumps connected in parallel through a water outlet pipe, and each condensate booster pump is connected to the heat exchanger through a water inlet pipe; a first electric gate valve and an electric regulating valve are sequentially arranged on the steam inlet pipe, The steam pipe includes a first steam inlet branch and a second steam inlet branch, the first steam inlet branch is provided with a second electric gate valve, and the second steam inlet branch is connected to the tank body; a water collection channel is provided between the bottom of the molten salt heat exchanger and the upper part of the water collection layer, one side of the water collection channel is connected to the molten salt heat exchanger, and the other side is connected to the lower part of the water collection layer through a third pipe, the first pipe, the second pipe, the third pipe, the water outlet pipe and the water inlet pipe are all provided with electric stop valves, the second pipe is connected with a fourth pipe, and the fourth pipe is provided with an exhaust regulating valve.

[0008] Preferably, an electric regulating valve group is connected in parallel to the steam inlet pipe, one end of the electric regulating valve group is connected to the user end, and the electric regulating valve group includes a plurality of regulating valves connected in parallel.

[0009] Preferably, a check valve is provided on the second pipeline.

[0010] Preferably, the molten salt heat exchanger comprises a plurality of heat exchange tubes arranged vertically in parallel, and the space between two heat exchange tubes is filled with molten salt.

[0011] Preferably, the steam collecting layer and the water collecting layer are respectively provided with a first liquid level gauge and a second liquid level gauge, and a safety valve is provided on the outside of the steam collecting layer.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1) The upper part of the tank body is used as a steam collecting layer to replace the steam-water separator, and the lower part is used as a water collecting layer to replace the hot water storage tank, which improves the integration of the device and also facilitates the heat exchange cycle energy storage of low-grade waste heat steam;

[0014] 2) A molten salt heat exchanger is installed in the middle of the tank to convert low-grade waste heat steam into condensate;

[0015] 3) The exhaust regulating valve is set to facilitate the removal of air from the system;

[0016] 4) The electric regulating valve group is set to adjust the pressure at the rear end of the steam inlet pipe according to system needs, ensuring that the steam can enter the rear end of the steam inlet pipe after heat exchange in the molten salt heat exchanger, ensuring the safety of steam supply and facilitating fault switching;

[0017] 5) The safety valve is installed to release the medium when the system is over-pressured to ensure system safety;

[0018] 6) The first level gauge is provided to facilitate measurement and control of the water level of the steam collecting layer during the heat release process; the second level gauge is provided to facilitate monitoring and control of the water level of the water collecting layer during the heat absorption process;

[0019] 7) The electric stop valve installed on the first pipeline is used to control the return of surplus steam directly to the system when the steam at the end of the molten salt heat exchanger cannot be completely converted into water during the heat absorption process; during the heat release process, the high-temperature water in the early stage can be directly flashed into the steam inlet pipe through the electric stop valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0021] Figure 1 This is a schematic diagram of a low-grade waste heat steam molten salt two-phase conversion heat cycle system of the present invention;

[0022] Figure 2 It is a schematic diagram of the heat absorption process of the system of the present invention;

[0023] Figure 3 It is a schematic diagram of the heat release process of the system of the present invention.

[0024] In the figure: 1. Tank body; 101. Steam collecting layer; 102. Molten salt heat exchanger; 103. Water collecting layer; 2. Condensate booster pump; 3. Steam inlet pipe; 4. First pipeline; 5. Second pipeline; 6. Third pipeline; 7. Fourth pipeline; 8. Water outlet pipeline; 9. Water inlet pipeline; 10. First electric gate valve; 11. Electric regulating valve; 12. Second electric gate valve; 13. Electric regulating valve group; 14. Electric stop valve; 15. Exhaust regulating valve; 16. First liquid level gauge; 17. Second liquid level gauge; 18. Check valve; 19. Safety valve. DETAILED DESCRIPTION

[0025] Example

[0026] like Figures 1 to 3As shown, a low-grade waste heat steam integrated heat exchange circulation system includes a tank body 1 and a steam collecting layer 101, a molten salt heat exchanger 102 in the middle and a water collecting layer 103 at the bottom, which are respectively arranged on the upper part of the tank body 1. A steam inlet pipe 3 is provided above the tank body 1. The steam collecting layer 101 and the water collecting layer 103 are connected through a first pipe 4. The water collecting layer 103 is connected to the user end through a second pipe 5; the lower part of the water collecting layer 103 is connected to a plurality of condensate booster pumps 2 connected in parallel through a water outlet pipe 8, and each condensate booster pump 2 is connected to the heat exchanger through a water inlet pipe 9; the steam inlet pipe 3 is sequentially provided with a first electric gate valve 10 and an electric regulating valve 1 1, the steam inlet pipe 3 includes a first steam inlet branch and a second steam inlet branch, the first steam inlet branch is provided with a second electric gate valve 12, and the second steam inlet branch is connected to the tank body 1; a water collection channel is provided between the bottom of the molten salt heat exchanger 102 and the upper part of the water collection layer 103, one side of the water collection channel is connected to the molten salt heat exchanger 102, and the other side is connected to the lower part of the water collection layer 103 through a third pipe 6, the first pipe 4, the second pipe 5, the third pipe 6, the water outlet pipe 8 and the water inlet pipe 9 are all provided with an electric stop valve 14, the second pipe 5 is connected with a fourth pipe 7, and the fourth pipe 7 is provided with an exhaust regulating valve 15.

[0027] As a further technical solution of this embodiment, an electric regulating valve group 13 is connected in parallel to the steam inlet pipe 3 , one end of the electric regulating valve group 13 is connected to the user end, and the electric regulating valve group 13 includes a plurality of regulating valves connected in parallel.

[0028] As a further technical solution of this embodiment, a check valve 18 is provided on the second pipeline 5 .

[0029] According to a further technical solution of this embodiment, the molten salt heat exchanger 102 includes a plurality of heat exchange tubes arranged vertically in parallel, and the space between two heat exchange tubes is filled with molten salt.

[0030] As a further technical solution of this embodiment, the steam collecting layer 101 and the water collecting layer 103 are respectively provided with a first liquid level gauge 16 and a second liquid level gauge 17 , and a safety valve 19 is provided outside the steam collecting layer 101 .

[0031] Working principle of the present invention:

[0032] 1) During the heat absorption process: a. Heat absorption start-up process: First, open the electric stop valve 14 on the third pipeline 6, then open the first electric gate valve 10 and the electric regulating valve 11. When the electric regulating valve 11 is opened, low-grade waste heat steam begins to enter the steam pipe 3; open the exhaust regulating valve 15 to exhaust the air in the molten salt heat exchanger 102 and multiple pipelines in the initial state. When it is ensured that most of the air in the tank body 1 has been exhausted, close the exhaust regulating valve 15, and the system begins to pressurize and store steam and condensate;

[0033] b. Heat exchange process at the end of the heat absorption phase: At the end of the heat exchange phase in the molten salt heat exchanger 102, the molten salt temperature rises close to the steam temperature. At this point, the steam cannot completely convert into water in the molten salt heat exchanger 102. The water temperature in the water collection layer 103 below the tank 1 has also risen to the target temperature. At this point, the electric shut-off valve 14 on the second pipe 5 is opened, and the system continues to inlet steam for heat exchange. The steam that cannot convert into water is directly returned to the steam inlet pipe 3 through the second pipe 5.

[0034] c. Heat absorption stopping process: When the water level of the water collecting layer 103 below the inside of the tank body 1 is measured by the second liquid level gauge 17 and does not change, the system heat storage ends. At this time, the first electric gate valve 10, the electric regulating valve 11, the electric stop valve 14 on the third pipeline 6 and the electric stop valve 14 on the second pipeline 54 are closed in sequence, and the system heat storage ends.

[0035] 2) Heat release process: a. Heat release start process: Directly open the electric stop valve 14 on the second pipeline 5, and the high-temperature saturated water directly enters the steam inlet pipe 3 after flash evaporation. After the flash evaporation pressure and temperature drop to the design allowable minimum value, i.e., 175°C, close the electric stop valve 14 on the second pipeline 5, and heat release starts and ends;

[0036] b. Heat release cycle process: Open the electric stop valve 14 on the outlet pipe 8, the electric stop valve 14 on the inlet pipe 9, and the electric stop valve 14 on the first pipe 4 in sequence, and start the condensate booster pump 2. The condensate in the water collection layer 103 is pressurized by the booster pump and then passes through the inlet pipe 9 into the water collection channel, the molten salt heat storage heat exchanger, and the steam collection layer 101 in sequence. After reaching the highest liquid level in the steam collection layer 101, it returns to the water collection layer 103 through the first pipe 4, eventually forming a new steam-water equilibrium and steam-water cycle. At this time, the water temperature gradually rises when the molten salt and water are exchanging heat. After reaching the design pressure, the second electric gate valve 12 is opened, and the steam flashes into the steam pipe network;

[0037] c. Heat release stopping process: When the liquid level in the water collection layer 103 below the tank body 1 stops decreasing, the heat release process ends. At this point, the electric stop valve 14 on the water inlet pipe 9, the condensate booster pump 2, and the electric stop valve 14 on the water outlet pipe 8 are closed in sequence. After the process has completely stopped, the second electric gate valve 12 is closed to cut off the connection with the steam inlet pipe 3. The electric stop valve 14 on the third pipe 6 is opened to drain the water from the upper steam collection layer 101 to the lower water collection layer 103. The electric stop valve 14 on the third pipe 6 and the electric stop valve 14 on the second pipe 5 are then closed, ending the heat release process.

[0038] The system of the present invention uses low-grade steam as the heat transfer medium and molten salt as the heat storage medium. The device and equipment are highly integrated. Whether it is the heat absorption process or the heat release process, the continuous flow of steam is guaranteed, the heat exchange effect is enhanced, and the heat storage capacity of the molten salt is maximized.

[0039] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the principles and essence of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A low-grade waste heat steam integrated heat exchange circulation system, characterized in that: The invention comprises a tank body (1), a steam collecting layer (101) respectively arranged above the interior of the tank body (1), a molten salt heat exchanger (102) in the middle, and a water collecting layer (103) at the bottom. A steam inlet pipe (3) is arranged above the tank body (1). The steam collecting layer (101) and the water collecting layer (103) are communicated through a first pipe (4). The water collecting layer (103) is connected to a user end through a second pipe (5). The lower part of the water collecting layer (103) is connected to a plurality of condensate booster pumps (2) connected in parallel through a water outlet pipe (8). Each condensate booster pump (2) is connected to the heat exchanger through a water inlet pipe (9). An electric regulating valve group (13) is connected in parallel to the steam inlet pipe (3), one end of the electric regulating valve group (13) is connected to the user end, and the electric regulating valve group (13) includes a plurality of regulating valves connected in parallel; The steam inlet pipe (3) is provided with a first electric gate valve (10) and an electric regulating valve (11) in sequence. The steam inlet pipe (3) comprises a first steam inlet branch pipe and a second steam inlet branch pipe. The first steam inlet branch pipe is provided with a second electric gate valve (12). The second steam inlet branch pipe is connected to the tank body (1). During the heat release cycle, the second electric gate valve (12) is opened, and steam flashes into the steam network; after the heat release process completely stops, the second electric gate valve (12) is closed, and the steam inlet pipe (3) is cut off; The molten salt heat exchanger (102) comprises a plurality of heat exchange tubes arranged vertically and in parallel, and the space between two heat exchange tubes is filled with molten salt; The steam collecting layer (101) and the water collecting layer (103) are respectively provided with a first liquid level gauge (16) and a second liquid level gauge (17), and a safety valve (19) is provided outside the steam collecting layer (101); A water collecting channel is provided between the bottom of the molten salt heat exchanger (102) and the upper part of the water collecting layer (103); one side of the water collecting channel is connected to the molten salt heat exchanger (102); the other side of the water collecting channel is connected to the lower part of the water collecting layer (103) through a third pipe (6); the first pipe (4), the second pipe (5), the third pipe (6), the water outlet pipe (8) and the water inlet pipe (9) are all provided with electric stop valves (14); the second pipe (5) is connected to a fourth pipe (7); and the fourth pipe (7) is provided with an exhaust regulating valve (15).

2. The low-grade waste heat steam integrated heat exchange circulation system according to claim 1, characterized in that: A check valve (18) is provided on the second pipeline (5).

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