CN101699163B - Molten salt tube-shell type steam generating device and method - Google Patents

Abstract

The invention provides a molten salt tube-shell type steam generating device and a molten salt tube-shell type steam generating method. The device comprises a tube-shell type heat exchanger, a steam separation output component and a heating and heat preservation component, wherein the steam separation output component is arranged on the top of the tube-shell type heat exchanger, and the heating and heat preservation component is arranged on the outer side of the container wall of the tube-shell type heat exchanger; the tube-shell type heat exchanger is provided with a top tube box, a tube body and a bottom tube box in sequence from top to bottom, wherein the inside of the tube body is provided with tube bundles of which both ends are fixedly connected with the tube body by tube plates, and the gaps between the tube bundles are filled with molten salt; and the outer side of the tube body is provided with a molten salt inlet tube and a molten salt outlet tube, and the bottom tube box is provided with a water inlet tube and a water outlet tube. The method comprises the following steps of: pre-heating the tube body; and orderly performing molten salt filling, hot water filling, and steam separating and outputting. The device has the advantages of big effective heat storage capacity, long-term stable operation, and relatively low manufacturing cost and maintenance cost, and can meet the requirements on large-scale solar mid- and high-temperature heat utilization in industry.

Description

Molten salt shell-and-tube steam generator and method

technical field

The invention relates to solar medium and high temperature heat utilization technology, in particular to a molten salt shell-and-tube steam generating device and method.

Background technique

As a clean energy technology with low cost and large-scale prospects, solar energy medium and high temperature heat utilization technology is a strategic new energy technology for the sustainable development of my country's national economy. The medium and high temperature heat utilization system of solar energy is mainly composed of a concentrating system, a heat absorption system, a heat storage system and a heat utilization device. Since solar energy is intermittent and unstable, it is difficult to meet the requirements of large-scale continuous and stable energy supply in industrialization. Therefore, it is necessary to develop efficient heat storage technology to effectively solve the problems of solar energy conversion, transmission and storage.

Due to the significant advantages of large heat capacity, high stability, and wide operating temperature range, molten salt is currently a widely used heat transfer and heat storage medium in medium and high temperature solar thermal utilization systems. Due to the convenience of steam transportation and use, steam is widely used in power generation, chemical industry, food and other industries. Therefore, how to convert molten salt heat storage into steam has become one of the key technologies for high-temperature heat utilization in solar energy.

Solar steam generation is an important form of large-scale utilization of solar energy. At present, there are a variety of steam generators based on glass vacuum tube heat collection, and steam generators based on molten salt heat transfer and heat storage functions include casing-type steam generators. The solar molten salt casing type steam generator uses a high temperature resistant selective coating on the outer wall of the jacket to absorb solar radiation energy, and transfers the absorbed heat to the molten salt in the molten salt casing, and then to the water in the serpentine inner pipe to form steam. In large-scale solar energy medium and high temperature heat utilization systems such as solar thermal power generation, there are some defects in the molten salt casing steam generator: (1) because the heat energy absorbed by the pipe wall is directly transmitted to the water working medium in the pipe through the molten salt in the casing, The molten salt mainly plays the role of heat transfer, and because the heat storage capacity of the molten salt in the casing is small, the heat storage function of the molten salt working fluid and the molten salt tank has not been fully utilized; (2) due to the real-time changes of the solar radiation outside the casing , the internal energy change of the molten salt in the casing is coupled with the evaporation process, and the parameters of the entire heat transfer process and water vapor of the casing system are not easy to control; (3) Due to the complex structure of the serpentine heat-absorbing tube body, the processing of the casing is difficult , so it is difficult to use on a large scale.

In order to meet the needs of large-scale molten salt steam generation, there is a need for a medium-high temperature molten salt steam generation method and device with large effective heat storage capacity, long-term stability, and lower manufacturing costs and operation and maintenance costs.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a molten salt shell-and-tube steam generating device with large effective heat storage capacity and long-term stability. heat utilization requirements.

Another object of the present invention is to provide a molten salt shell-and-tube steam generation method realized by the above device.

The present invention is realized through the following technical solutions: a molten salt shell-and-tube steam generating device, including a shell-and-tube heat exchanger, a steam separation output component and a heating and heat preservation component, the steam separation output component is arranged on the top of the shell-and-tube heat exchanger, The heating and heat preservation components are arranged outside the container wall of the shell-and-tube heat exchanger; the shell-and-tube heat exchanger includes a top tube box, a tube body and a bottom tube box arranged in sequence from top to bottom, and a tube bundle is arranged inside the tube body. The two ends of the tube bundle are fixedly connected to the tube body through the tube plate, and the gap between the tube bundles in the tube body is filled with molten salt; the outer side of the tube body is provided with a molten salt inlet pipe and a molten salt outlet pipe, and the bottom tube box is provided with a water inlet Pipes and water outlet pipes.

The tube body of the shell-and-tube heat exchanger is a cylindrical structure, and the top tube box and the bottom tube box are respectively corresponding oval tube box structures.

The materials of the top tube box, the bottom tube box, the tube body, the tube sheet and the tube bundle are all stainless steel; the spaces between the tube bundle and the tube sheet, and between the tube sheet and the tube body are sealed by welding and fixed to form an integrated structure; the top tube The box and the bottom tube box are respectively fixedly connected with the pipe body through flanges.

The top pipe box is also provided with a liquid level controller for ensuring liquid level stability during steam generation.

The diameter of a single stainless steel tube in the tube bundle is 10-30mm, and the thickness of the tube wall is 1-2mm.

The steam separation and output assembly includes a steam channel and a steam bag sequentially connected to the top tube box; a filter screen is provided in the steam channel, and a safety valve, a steam outlet, a pressure gauge and a steam pressure controller are respectively provided on the steam bag.

The heating and heat preservation component includes an insulation layer and a heating wire, the heating wire is wound on the outside of the tube body of the shell-and-tube heat exchanger, and the insulation layer is wrapped on the outside of the heating wire.

The thermal insulation layer can be made of glass fiber thermal insulation material or other thermal insulation materials, and the thickness of the thermal insulation layer depends on the temperature of the molten salt and heat loss requirements.

In the above molten salt shell-and-tube steam generator, the type of molten salt can be selected according to the actual working temperature range of the steam.

When the molten salt shell-and-tube steam generating device of the present invention works, its working principle is: high-temperature hot water is pumped into the bottom tube box from the water inlet pipe, and enters the top tube box through the tube bundle, and the high-temperature hot water in the tube bundle and the water in the tube body The two-phase flow phenomenon of steam and water is formed during the heat exchange of molten salt. The steam generated in the shell-and-tube heat exchanger enters the steam drum through the steam channel, so that the pressure in the steam drum increases continuously. When the air pressure in the steam drum reaches the set pressure Afterwards, the steam outlet continuously outputs high-temperature and high-pressure steam; during steam generation, the liquid level controller maintains the liquid level in the top tube box, so that the input of high-temperature hot water and steam output can reach a balance; during the steam output process, the pressure controller Keep the pressure of the output steam stable; the heating and insulation components outside the pipe body preheat the pipe body when starting to avoid solidification of the molten salt, and maintain the temperature of the molten salt after shutdown to promote the reflux of the molten salt while reducing heat loss.

The molten salt shell-and-tube steam generation method realized by the above-mentioned device comprises the following steps:

(1) Tube body preheating: start the power supply, and the heating wire starts to preheat the tube body of the shell-and-tube heat exchanger until the temperature of the tube body is higher than the freezing point temperature of the molten salt;

(2) Molten salt pouring: pour molten salt into the pipe body from the molten salt inlet pipe, the molten salt fills the entire pipe body and flows out from the molten salt outlet pipe, cut off the power supply when the molten salt fills the pipe body, and stop the heating of the heating wire;

(3) Hot water injection: pour high-temperature hot water into the bottom pipe box from the water inlet pipe. After the high-temperature hot water fills the bottom pipe box, it enters the top pipe box through the tube bundle, and the water level of the high-temperature hot water in the top pipe box reaches the set water level. After that, complete the hot water perfusion;

(4) Steam separation output: The steam generated during hot water filling enters the steam channel, passes through the filter and then enters the steam drum. The pressure gauge detects the steam pressure in the steam drum in real time. When the pressure in the steam drum reaches the set pressure After the value is set, the steam is output from the steam outlet, and the pressure controller keeps the pressure of the output steam stable during the steam output process.

During the steam separation and output process, while the steam is output from the steam outlet, the bottom tube box of the shell-and-tube heat exchanger needs to be continuously filled with high-temperature hot water from the water inlet pipe, and the liquid level controller maintains the temperature in the top tube box. The liquid level is stable.

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

1. The steam generation process and steam parameters are stable. Using the tube body of the shell-and-tube heat exchanger to transfer and store high-temperature molten salt greatly improves the effective heat storage capacity and stabilizes the heat exchange and evaporation process; the pressure gauge and steam pressure controller are used to detect and control the steam pressure in real time, which can ensure Stability of steam drum internal pressure and steam output parameters.

2. Wide working temperature range. Each component of the shell-and-tube heat exchanger is made of stainless steel, which has high temperature and pressure resistance and corrosion resistance. The ideal molten salt working medium can be selected according to the actual working temperature of the steam, which is more conducive to cost control and resource utilization. Reasonable use.

3. Simple structure and easy processing. The molten salt shell-and-tube steam generating device includes a shell-and-tube heat exchanger, a steam separation output component, and a heating and heat preservation component. These components are simple in structure, easy to process, and these components are convenient for large-scale production, which is conducive to the large-scale application of the device.

4. Great potential for promotion and application. The heat source of the molten salt shell-and-tube steam generator comes from high-temperature molten salt, and the heat storage of high-temperature molten salt can come from various methods such as solar energy, industrial waste heat, and chemical process, so the present invention can be popularized and applied in many fields.

Description of drawings

Fig. 1 is a structural schematic diagram of the molten salt shell-and-tube steam generating device of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

In this embodiment, a molten salt shell-and-tube steam generating device has a structure as shown in Figure 1, including a shell-and-tube heat exchanger, a steam separation output assembly and a heating and heat preservation assembly. The steam separation output assembly is located in the shell-and-tube heat exchanger At the top of the heat exchanger, the heating and heat preservation components are arranged on the outside of the container wall of the shell-and-tube heat exchanger; There is a tube bundle 11 inside, and the two ends of the tube bundle 11 are respectively fixedly connected to the tube body 5 through the tube plate 6, and the gap between the tube bundles 11 in the tube body 5 is filled with molten salt 12; The salt outlet pipeline 2 and the bottom pipe box 7 are provided with a water inlet pipeline 9 and a water outlet pipeline 8 .

The tube body 5 of the shell-and-tube heat exchanger is a cylindrical structure, and the top tube box 1 and the bottom tube box 7 are respectively corresponding elliptical tube box structures. The materials of the top tube box 1, the bottom tube box 7, the tube body 5, the tube sheet 6 and the tube bundle 11 are all stainless steel; between the tube bundle 11 and the tube sheet 6, between the tube sheet 6 and the tube body 5 are sealed by welding, Fixed to form an integrated structure; the top pipe box 1 and the bottom pipe box 7 are respectively fixedly connected to the pipe body 5 through flanges. The top tube box 1 is also provided with a liquid level controller 13 for ensuring the stability of the liquid level during steam generation. The diameter of a single stainless steel tube in the tube bundle 11 is 10-30 mm, and the thickness of the tube wall is 1-2 mm.

The steam separation output assembly includes a steam channel 14 and a steam drum 15 connected in sequence with the top pipe box 1; a filter screen 20 is provided in the steam channel 14, and a pressure gauge 16, a steam outlet 17, and a steam pressure controller are respectively provided on the steam drum 15 18 and safety valve 19.

The heating and heat preservation assembly includes an insulation layer 4 and a heating wire 3 , the heating wire 3 is wound on the outside of the tube body 5 of the shell-and-tube heat exchanger, and the insulation layer 4 is wrapped on the outside of the heating wire 3 . The insulation layer 4 can use glass fiber insulation material or other insulation materials, and the thickness of the insulation layer 4 depends on the temperature of the molten salt 12 and heat loss requirements.

In the above molten salt shell-and-tube steam generator, the type of molten salt 12 can be selected according to the actual working temperature range of the steam.

When the molten salt shell-and-tube steam generating device of the present invention works, its working principle is: high-temperature hot water is pumped into the bottom tube box 7 from the water inlet pipe 9, and enters the top tube box 1 through the tube bundle 11, and the high-temperature heat in the tube bundle 11 The two-phase flow phenomenon of steam and water is formed during the heat exchange between water and the molten salt 12 in the tube body 5, and the steam generated in the shell-and-tube heat exchanger enters the steam drum 15 through the steam channel 14, so that the pressure in the steam drum 15 is continuously increase, when the air pressure in the steam drum 15 reaches the set pressure, the steam outlet 17 continuously outputs high-temperature and high-pressure steam; during the steam generation process, the liquid level controller 13 maintains the liquid level in the top tube box 1, so that the input volume of high-temperature hot water reach a balance with the steam output; during the steam output process, the steam pressure controller 18 above the steam drum 15 keeps the pressure of the output steam at a stable parameter; The salt is solidified, and the temperature of the molten salt is maintained after shutdown to promote the reflux of the molten salt while reducing heat loss.

The molten salt shell-and-tube steam generation method realized by the above-mentioned device comprises the following steps:

(1) Tube body preheating: start the power supply, and the heating wire 3 begins to preheat the tube body 5 of the shell-and-tube heat exchanger until the temperature of the tube body 5 is higher than the freezing point temperature of the molten salt 12;

(2) Molten salt pouring: pour molten salt 12 into the pipe body 5 from the molten salt inlet pipe 10, the molten salt 12 fills the entire pipe body 5 and flows out from the molten salt outlet pipe 2, and cuts off when the molten salt 12 fills the pipe body 5 Power supply, stop the heating of heating wire 3;

(3) Hot water injection: pour high-temperature hot water from the water inlet pipe 9 into the bottom pipe box 7. After the high-temperature hot water fills the bottom pipe box 7, it enters the top pipe box 1 through the tube bundle 11, and the high-temperature hot water in the top pipe box 1 After the water level reaches the set water level, the hot water filling is completed, and the excess high-temperature hot water flows out from the water outlet pipe 8;

(4) Steam separation output: the steam generated in the hot water filling process enters the steam channel 14, and enters the steam bag 15 after being filtered by the filter screen 20. The pressure gauge 16 detects the steam pressure in the steam bag 15 in real time. After the pressure reaches the set pressure value, the steam is output from the steam outlet 17, and the steam pressure controller 18 maintains the stability of the output steam pressure.

During the above-mentioned steam separation and output process, while the steam is output from the steam outlet 17, the bottom tube box 7 of the shell-and-tube heat exchanger needs to be continuously filled with high-temperature hot water from the water inlet pipe 9, which is maintained by the liquid level controller 13. The liquid level in the top tube box 1 is stable.

As mentioned above, the present invention can be better realized. The above-mentioned embodiment is only a preferred embodiment of the present invention, and is not used to limit the scope of the present invention; Covered by the scope of protection required by the claims of the present invention.

Claims (10)

1. The molten salt shell-and-tube steam generating device is characterized in that it includes a shell-and-tube heat exchanger, a steam separation output assembly and a heating and heat preservation assembly, the steam separation output assembly is arranged on the top of the shell and tube heat exchanger, and the heating and insulation assembly is arranged It is outside the container wall of the shell-and-tube heat exchanger; the shell-and-tube heat exchanger includes a top tube box, a tube body and a bottom tube box arranged in sequence from top to bottom, and a tube bundle is arranged inside the tube body, and the two ends of the tube bundle are respectively The tube plate is fixedly connected to the tube body, and the gap between the tube bundles in the tube body is filled with molten salt; the outer side of the tube body is provided with a molten salt inlet pipe and a molten salt outlet pipe, and the bottom tube box is provided with a water inlet pipe and a water outlet pipeline. 2. The molten salt shell-and-tube steam generating device according to claim 1, wherein the tube body of the shell-and-tube heat exchanger is a cylindrical structure, and the top tube box and the bottom tube box are respectively corresponding oval tubes box structure. 3. The molten salt shell-and-tube steam generating device according to claim 1, wherein the materials of the top tube box, the bottom tube box, the tube body, the tube sheet and the tube bundle are all stainless steel; between the tube bundle and the tube sheet , The tube sheet and the tube body are sealed by welding and fixed to form an integrated structure; the top tube box and the bottom tube box are fixedly connected to the tube body through flanges. 4. The molten salt shell-and-tube steam generator according to claim 1, wherein the top tube box is also provided with a liquid level controller for ensuring stable liquid level during steam generation. 5. The molten salt shell-and-tube steam generating device according to claim 1, characterized in that, the diameter of a single stainless steel tube in the tube bundle is 10-30 mm, and the thickness of the tube wall is 1-2 mm. 6. The molten salt shell-and-tube steam generating device according to claim 1, wherein the steam separation output assembly includes a steam channel and a steam bag sequentially connected to the top tube box; a filter is arranged in the steam channel , the steam drum is equipped with a safety valve, a steam outlet and a pressure gauge, and a steam pressure controller is also installed at the steam outlet. 7. The molten salt shell-and-tube steam generating device according to claim 1, characterized in that, the heating and heat preservation assembly comprises a heat insulation layer and a heating wire, the heating wire is wound on the outside of the tube body of the shell and tube heat exchanger, and the heat insulation layer Wrapped on the outside of the heating wire. 8 . The molten salt shell-and-tube steam generating device according to claim 7 , wherein the thermal insulation layer is made of glass fiber thermal insulation material. 9. The molten salt shell-and-tube steam generation method realized by the device according to any one of claims 1 to 8, characterized in that it comprises the following steps: (1) Tube body preheating: start the power supply, and the heating wire starts to preheat the tube body of the shell-and-tube heat exchanger until the temperature of the tube body is higher than the freezing point temperature of the molten salt; (2) Molten salt pouring: pour molten salt into the pipe body from the molten salt inlet pipe, the molten salt fills the entire pipe body and flows out from the molten salt outlet pipe, cut off the power supply when the molten salt fills the pipe body, and stop the heating of the heating wire; (3) Hot water injection: pour high-temperature hot water into the bottom pipe box from the water inlet pipe. After the high-temperature hot water fills the bottom pipe box, it enters the top pipe box through the tube bundle, and the water level of the high-temperature hot water in the top pipe box reaches the set water level. Finally, the hot water injection is completed, and the excess high-temperature hot water flows out from the water outlet pipe; (4) Steam separation output: The steam generated during hot water filling enters the steam channel, passes through the filter and then enters the steam drum. The pressure gauge detects the steam pressure in the steam drum in real time. When the pressure in the steam drum reaches the set pressure After the value is set, the steam is output from the steam outlet, and the pressure controller keeps the pressure of the output steam stable during the steam output process. 10. The molten salt shell-and-tube steam generation method according to claim 9, characterized in that, during the steam separation and output process, while the steam is output from the steam outlet, the bottom tube box of the shell-and-tube heat exchanger needs to continue The high-temperature hot water is poured from the water inlet pipe, and the liquid level in the top pipe box is kept stable by the liquid level controller.

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