Combined evaporator and heat storage and supply system

Abstract

The utility model discloses a combined type evaporator and a heat storage and supply system, the combined type evaporator comprises a shell and an overheat section shell section arranged on the shell, a gas phase space and a liquid phase space are distributed in the shell up and down, a preheating tube bundle is arranged in the gas phase space, an evaporating tube bundle is arranged in the liquid phase space, an overheat tube bundle is arranged in the overheat section shell section, and the preheating tube bundle is arranged in the liquid phase space. A steam injection pipe used for preheating feed water is further arranged in the liquid phase space. According to the utility model, the evaporator can be preheated without arranging a starting electric heater and a starting circulating pump, and the evaporator does not need to be arranged at a high position, so that the system structure is simplified, the construction cost is reduced, and the heat storage function is also realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of heating, and in particular relates to a combined evaporator and a heat storage heating system. Background Art

[0002] With the large-scale access to the grid of new energy sources, the power grid has put forward more and more stringent load regulation requirements for thermal power plants. The configuration of molten salt heat storage systems in thermal power plants has become one of the options for improving flexibility. The molten salt heat storage system generally includes a heat storage heat exchanger, a molten salt storage tank, and an evaporation system. The heat storage heat exchanger is used to heat the molten salt with steam, the molten salt storage tank is used to store cold and hot molten salt, and the evaporation system is used to release the heat stored in the molten salt to generate steam. The heat storage heat exchanger generally includes several heat exchangers to adapt to the heat exchange of superheated steam, saturated steam, and supercooled water. Since the molten salt used for heat storage in thermal power plants is mostly ternary molten salt, when the temperature reaches 450°C, the molten salt is easy to decompose. Conventional evaporation systems often include equipment such as preheaters, evaporators, steam drums, superheaters, and auxiliary equipment such as external circulation pumps for providing power during preheating and electric heaters for providing heat during preheating. The system structure is complex. The external circulation pump must have a cavitation margin, so the evaporator needs to be arranged at a high position, and the steam drum needs to be higher than the evaporator by a certain height. The platform construction cost is high and the operation and maintenance are inconvenient. The external circulation pump and the start-up electric heater consume electrical energy when running, making the system inefficient. Utility Model Content

[0003] In order to solve the above problems, the utility model provides a combined evaporator, which can realize preheating without setting a starting electric heater and a starting circulation pump, and also has a heat storage function.

[0004] In order to solve the above problems, the utility model also provides a heat storage heating system. The system can preheat the evaporator without setting a starting electric heater and a starting circulation pump, and the evaporator does not need to be arranged at a high position, which simplifies the system structure, reduces the construction cost, and also has a heat storage function.

[0005] The embodiments of the present invention are implemented by the following technical solutions:

[0006] The combined evaporator comprises a shell and a superheating section cylinder section arranged on the shell, wherein gas phase space and liquid phase space are distributed up and down in the shell, a preheating tube bundle is arranged in the gas phase space, an evaporation tube bundle is arranged in the liquid phase space, an superheating tube bundle is arranged in the superheating section cylinder section, and a steam injection pipe for preheating feed water is also arranged in the liquid phase space.

[0007] In an embodiment of the present invention, the steam injection pipe is provided with a plurality of steam injection holes.

[0008] A heat storage heating system, comprising a heat storage heat exchanger, a low-temperature molten salt tank, a high-temperature molten salt tank and the combined evaporator as described above, wherein the heat storage heat exchanger is provided with a boiler steam interface and a turbine steam interface, the molten salt outlet of the heat storage heat exchanger is connected to the molten salt inlet of the high-temperature molten salt tank, the molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the evaporation tube bundle of the combined evaporator, the molten salt outlet of the evaporation tube bundle of the combined evaporator is connected to the molten salt inlet of the low-temperature molten salt tank, and the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the heat storage heat exchanger.

[0009] In one embodiment of the utility model, the pipeline between the high-temperature molten salt tank and the evaporation tube bundle is provided with a first branch pipeline and a second branch pipeline, the first branch pipeline is connected to the molten salt inlet of the superheated tube bundle, the molten salt outlet of the superheated tube bundle is connected to the molten salt inlet of the evaporation tube bundle, and the second branch pipeline is connected to the molten salt inlet of the evaporation tube bundle.

[0010] In one embodiment of the present invention, the heat storage heat exchanger is a vertical multi-stream wound tube heat exchanger.

[0011] The technical solution of the utility model has at least the following advantages and beneficial effects:

[0012] The utility model sets a steam injection pipe for preheating feed water in the combined evaporator. In the heat storage stage, steam can be introduced into the liquid phase space through the steam injection pipe to realize the preheating of the combined evaporator. Compared with the prior art, the system does not need to set a start-up electric heater and a start-up circulation pump, and the evaporator does not need to be arranged at a high position, which simplifies the system structure and reduces the construction cost. In addition, the combined evaporator of the utility model has a certain heat storage function and has the ability to provide saturated steam to the outside without adding molten salt, so that the heating system has a rapid response capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 It is a schematic diagram of the combined evaporator in the utility model;

[0015] Figure 2 It is a schematic diagram of the heat storage heating system in the utility model.

[0016] Icons: 1-heat storage heat exchanger, 2-low-temperature molten salt tank, 3-high-temperature molten salt tank, 4-combined evaporator, 41-shell, 42-preheating tube bundle, 43-evaporation tube bundle, 44-superheating tube bundle, 45-steam injection pipe, 46-superheating section cylinder. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0020] In the description of the present utility model, it should be noted that if the terms "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the utility model product is usually placed when used. It is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present utility model.

[0021] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "configure", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Example 1

[0023] Please refer to Figure 1This embodiment provides a combined evaporator 4, including a shell 41 and a superheating section cylinder 46 arranged in the shell 41. The shell 41 has gas phase space and liquid phase space distributed up and down. The gas phase space is provided with a preheating tube bundle 42, and the liquid phase space is provided with an evaporation tube bundle 43 for heating feed water. The superheating section cylinder 46 is provided with a superheating tube bundle 44, and the liquid phase space is also provided with a steam injection pipe 45 for preheating feed water. The steam injection pipe 45 is connected to steam from a boiler or a steam turbine, and the steam injection pipe 45 is provided with a plurality of steam injection holes. The gas phase space in the evaporator is provided with a preheating tube bundle 42, and the steam outlet cylinder is provided with a superheating tube bundle 44, so that feed water preheating, evaporation, and superheating are achieved in one device.

[0024] When the combined evaporator 4 is in use, water is injected into the shell 41 to the rated water level through the water inlet, and the water needs to submerge the entire evaporation tube bundle 43. The steam from the boiler or turbine is passed into the steam injection pipe 45, and the steam is sprayed into the liquid phase space in the shell 41 through the various steam injection holes of the steam injection pipe 45, mixed with water and heated water, so as to realize the preheating of the evaporator. When the preheating temperature reaches the specified salt inlet temperature, a high-temperature molten salt from the high-temperature molten salt tank 3 enters the superheating tube bundle 44 with a small flow rate to realize the superheating of saturated steam, and then flows out of the superheating tube bundle 44, and then merges into the evaporation tube bundle 43. Another high-temperature molten salt directly enters the evaporation tube bundle 43, and after heat exchange with water, it flows out of the shell 41 to the low-temperature molten salt tank 2. After the evaporator enters the salt, the water passes through the preheating tube bundle 42, exchanges heat with the steam in the gas phase space, and then enters the lower liquid phase space. When the evaporator reaches the preheating temperature, molten salt is introduced into the evaporator, and the amount of molten salt entering the superheated tube bundle 44 is adjusted by the regulating valve, the external steam flow rate and the molten salt flow rate are adjusted, and the feed water flow rate of the evaporator is adjusted to start the evaporator. The saturated steam in the gas phase space exchanges heat with the molten salt in the superheated tube bundle 44 and is heated into superheated steam, which is then sent to the user through the steam outlet.

[0025] Example 2

[0026] Please refer to Figure 1This embodiment provides a heat storage heating system, which includes a heat storage heat exchanger 1, a low-temperature molten salt tank 2, a high-temperature molten salt tank 3 and a combined evaporator 4 as in Example 1. The heat storage heat exchanger 1 is a vertical multi-stream wound tube heat exchanger, which can be used in the existing way. The tube bundles in the vertical multi-stream wound tube heat exchanger are divided into 2 to 4 groups, which can realize the heat exchange between steam with different parameters on the tube side and molten salt on the shell side. The vertical multi-stream wound tube heat exchanger has a boiler steam interface and a turbine steam interface. The molten salt outlet of the heat storage heat exchanger 1 is connected to the molten salt inlet of the high-temperature molten salt tank 3, and the molten salt outlet of the high-temperature molten salt tank 3 is connected to the molten salt inlet of the evaporation tube bundle 43 of the combined evaporator 4. The molten salt outlet of the evaporation tube bundle 43 of the combined evaporator 4 is connected to the molten salt inlet of the low-temperature molten salt tank 2, and the molten salt outlet of the low-temperature molten salt tank 2 is connected to the molten salt inlet of the heat storage heat exchanger 1. Steam flows from top to bottom in the tube bundle of the vertical multi-stream wound tube heat exchanger, and molten salt flows from bottom to top on the shell side of the vertical multi-stream wound tube heat exchanger. The heat storage heat exchanger 1 uses the main steam from the boiler and the turbine extraction steam with different parameters to exchange heat with the low-temperature molten salt from the cold low-temperature molten salt storage tank. The molten salt is heated and goes to the high-temperature molten salt storage tank. The main steam is condensed after heat exchange and goes to the turbine heat recovery system. The turbine extraction steam is heat exchanged and goes to the boiler reheater or the turbine heat recovery system.

[0027] It should be noted that, in the existing thermal power plant equipped with a molten salt heat storage system, under low load conditions, the area margin of the heat storage heat exchanger 1 is large and the temperature of the steam is high, which easily leads to over-temperature decomposition of the molten salt. In this embodiment, the main steam and the steam extraction steam of the steam turbine are used to exchange heat with the molten salt at the same time. When the load is low, the area margin of the heat storage heat exchanger 1 is reduced by reducing the steam flow extracted from the intermediate pressure cylinder of the steam turbine, thereby avoiding over-temperature of the molten salt.

[0028] In this embodiment, the pipeline between the high-temperature molten salt tank 3 and the evaporation tube bundle 43 is provided with a first branch pipeline and a second branch pipeline, the first branch pipeline is connected to the molten salt inlet of the superheated tube bundle 44, the molten salt outlet of the superheated tube bundle 44 is connected to the molten salt inlet of the evaporation tube bundle 43, and the second branch pipeline is connected to the molten salt inlet of the evaporation tube bundle 43, so that the high-temperature molten salt flowing out of the high-temperature molten salt tank 3 can be divided into two paths, one path of high-temperature molten salt enters the superheated tube bundle 44 at a small flow rate from the high-temperature molten salt tank 3 to achieve superheating of saturated steam, then flows out of the superheated tube bundle 44, and then merges into the evaporation tube bundle 43. The other path of high-temperature molten salt directly enters the evaporation tube bundle 43, and flows out of the shell 41 to the low-temperature molten salt tank 2 after heat exchange with water.

[0029] It should be noted that, since the evaporator has a large volume and a certain heat storage capacity, when the thermal power unit needs to store heat, part of the steam can be passed into the steam injection pipe 45 to heat the feed water in the evaporator for heat storage, which also serves as a preheating device.

[0030] The utility model sets a steam injection pipe 45 for preheating feed water in the combined evaporator 4. In the heat storage stage, steam can be introduced into the liquid phase space through the steam injection pipe 45 to achieve preheating of the combined evaporator 4. Compared with the prior art, the heating system does not need to be provided with a start-up electric heater and a start-up circulation pump, and the evaporator does not need to be arranged at a high position, which simplifies the system structure and reduces the construction cost. In addition, the combined evaporator 4 of the utility model has a certain heat storage function and has the ability to provide saturated steam to the outside without adding molten salt, so that the heating system has a rapid response capability.

[0031] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A combined evaporator, comprising a shell and a superheating section cylinder section arranged in the shell, wherein the shell has gas phase space and liquid phase space distributed up and down, a preheating tube bundle is arranged in the gas phase space, an evaporation tube bundle is arranged in the liquid phase space, and a superheating tube bundle is arranged in the superheating section cylinder section, characterized in that: A steam injection pipe for preheating feed water is also arranged in the liquid phase space.

2. The combined evaporator according to claim 1, characterized in that: The steam injection pipe is provided with a plurality of steam injection holes.

3. Heat storage heating system, characterized in that It comprises a heat storage heat exchanger, a low-temperature molten salt tank, a high-temperature molten salt tank and the combined evaporator as claimed in claim 1, wherein the heat storage heat exchanger is provided with a boiler steam interface and a turbine steam interface, the molten salt outlet of the heat storage heat exchanger is connected with the molten salt inlet of the high-temperature molten salt tank, the molten salt outlet of the high-temperature molten salt tank is connected with the molten salt inlet of the evaporation tube bundle of the combined evaporator, the molten salt outlet of the evaporation tube bundle of the combined evaporator is connected with the molten salt inlet of the low-temperature molten salt tank, and the molten salt outlet of the low-temperature molten salt tank is connected with the molten salt inlet of the heat storage heat exchanger.

4. The heat storage heating system according to claim 3, characterized in that: The pipeline between the high-temperature molten salt tank and the evaporation tube bundle is provided with a first branch pipeline and a second branch pipeline, the first branch pipeline is connected to the molten salt inlet of the superheated tube bundle, the molten salt outlet of the superheated tube bundle is connected to the molten salt inlet of the evaporation tube bundle, and the second branch pipeline is connected to the molten salt inlet of the evaporation tube bundle.

5. The heat storage heating system according to claim 3, characterized in that: The heat storage heat exchanger is a vertical multi-stream wound tube heat exchanger.

Images