Fused salt phase change heat exchange system

Abstract

The invention discloses a molten salt phase change heat exchange system which comprises a movable molten salt heat storage terminal, a heat storage system and a heat release system. The mobile fused salt heat storage terminal adopts low-temperature phase change fused salt as a heat storage medium to connect a heat storage system and a heat release system; the heat storage system is used for transferring low-grade industrial waste heat to the fused salt heat storage unit through heat conduction oil. Through the implementation of the system, the low-temperature phase change fused salt serves as a heat storage medium, remote heat supply is conducted through low-grade industrial waste heat, the problem that the heat utilization requirement cannot be met due to aging or imperfection of a heat supply network is solved, the energy utilization rate of a production enterprise is increased, and the energy utilization rate of the production enterprise is increased. And the energy consumption cost of enterprises is reduced, and certain use value and popularization value are achieved.

Description

Technical Field

[0001] This invention relates to the field of heat exchange system technology, and more particularly to a molten salt phase change heat exchange system. Background Technology

[0002] Currently, urban residents in my country mainly rely on centralized heating for heating. However, due to urban planning leading to the relocation of thermal power plants, aging heating networks resulting in severe heat loss, inflexible heating regulation, and excessively high heating costs, the existing heating network is increasingly unable to meet residents' heating needs.

[0003] Meanwhile, many high-energy-consuming industrial enterprises in my country's urban areas, such as steel and chemical industries, have low-grade industrial waste heat that cannot be utilized and is thus wasted. Therefore, building mobile heat storage vehicles to collect low-grade industrial waste heat for urban residents' heating has high economic value and social benefits.

[0004] Traditional thermal storage vehicles use water, steam, thermal oil, or magnesia bricks as the heat storage medium. Steam thermal storage utilizes the latent heat of the transformer, but the storage tank needs to withstand high pressure, and the transportation process is somewhat dangerous. Thermal oil and magnesia bricks, on the other hand, only utilize the sensible heat of the medium, resulting in low heat storage density, high heat storage and transportation costs, and poor economic efficiency.

[0005] If molten salt is considered as the medium, the heat storage temperature is relatively high. The working temperature range of binary salt is 290-565℃, and that of ternary salt is 200-538℃. It is difficult to utilize low-grade industrial waste heat in this temperature range, and high-temperature steam or electric boilers are required for heating, resulting in high heating costs.

[0006] In summary, a molten salt phase change heat transfer system is needed to address the shortcomings of existing technologies. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a molten salt phase change heat transfer system, aiming to solve the aforementioned problems.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a molten salt phase change heat transfer system, comprising a mobile molten salt heat storage terminal, a heat storage system, and a heat release system;

[0009] The mobile molten salt thermal storage terminal uses low-temperature phase change molten salt as the thermal storage medium to connect the thermal storage system and the heat release system;

[0010] The heat storage system is used to transfer low-grade industrial waste heat to the molten salt heat storage unit via heat transfer oil.

[0011] The heat release system is used to output the heat stored in the mobile molten salt thermal storage terminal for heating.

[0012] Furthermore, the composition and mass percentage of the low-temperature phase change molten salt are as follows:

[0013] It contains 53% potassium nitrate, 40% sodium nitrite, and 7% sodium nitrate, with a melting point of 140-150℃.

[0014] Furthermore, the heat storage system includes:

[0015] Heat source unit, used to provide the industrial waste heat required for mobile molten salt thermal storage terminals;

[0016] Heat exchange flue is used to exhaust flue gas from heat source units at a temperature not exceeding 200°C.

[0017] The first electronic control valve is used to monitor the temperature and flow rate of flue gas in the heat exchange flue and regulate the flue gas entering the heat exchange flue.

[0018] The first heat transfer oil circulation unit is used to connect the heat exchange flue and the mobile molten salt heat storage terminal.

[0019] The heat exchange flue heats the heat transfer oil through the flue gas, and the heated high-temperature heat transfer oil flows into the mobile molten salt heat storage terminal, causing the solid molten salt to change into a liquid state for heat storage.

[0020] Furthermore, the heat source unit includes a boiler body, a superheater, and an economizer. The superheater is located in the high-temperature zone at the furnace outlet of the boiler body, and the economizer is located in the boiler tail flue of the boiler body.

[0021] The heat exchange flue is connected to the boiler body at a location near the economizer front section where the flue gas reaches 200°C.

[0022] Furthermore, the heat dissipation system includes:

[0023] The second heat transfer oil circulation unit is used to connect to the mobile molten salt heat storage terminal, and to pass room temperature heat transfer oil into the mobile molten salt heat storage terminal to be heated by liquid molten salt.

[0024] The steam-water heat exchange unit is used to connect to the second heat transfer oil circulation unit, and heats the return water of the steam-water heat exchange unit to generate steam by heating the heated high-temperature heat transfer oil.

[0025] The electric heating unit is used to heat the heat transfer oil of the second heat transfer oil circulation unit during off-peak electricity periods to supplement the heating supply.

[0026] Furthermore, both the first and second heat transfer oil circulation units include an oil storage tank and a heat transfer oil pipe, wherein:

[0027] The oil storage tank of the first heat transfer oil circulation unit temporarily stores excess heat for peak shaving.

[0028] The oil storage tank of the second heat transfer oil circulation unit stores heat transfer oil heated by off-peak electricity for supplementary heating.

[0029] Furthermore, the steam-water heat exchange unit includes:

[0030] A steam-water heat exchanger is used to connect the heat transfer oil pipe of the second heat transfer oil circulation unit, and heats the return water to generate steam through the high-temperature heat transfer oil in the heat transfer oil pipe;

[0031] A steam drum is used to receive a steam-water mixture from a steam-water heat exchanger and separate and output pure saturated steam.

[0032] The heat user module is used to receive pure saturated steam from the steam drum for heat use and to recycle the returned heat water to the steam-water heat exchanger for reheating.

[0033] Furthermore, the mobile molten salt thermal storage terminal is a mobile thermal storage vehicle, and its molten salt filling amount is dynamically adjusted according to the residual heat of the heat source and the needs of the heat users.

[0034] The substantial effects of this invention:

[0035] 1. In this invention, low-temperature phase change molten salt is used as the heat storage medium to provide long-distance heating using low-grade industrial waste heat. This solves the problem of heat demand that cannot be met due to aging or imperfection of the heating network, improves the energy utilization rate of production enterprises, and reduces the energy cost of enterprises.

[0036] 2. This invention eliminates the need for constructing large-scale heating networks, avoiding huge upfront investments and heat loss due to aging pipelines. This reduces heating costs and saves energy.

[0037] 3. In this invention, a heat transfer oil heat exchange system, including a small oil storage tank, is installed at both the heat source and the heat user location. At the heat source, the oil storage tank can store a portion of the heat through the heat transfer oil when heating is not being supplied, achieving a flexible peak-shaving effect. At the heat user location, the oil storage tank can utilize an electric heating system to heat the heat transfer oil using inexpensive off-peak electricity, thereby supplementing the heating supply. This invention has certain practical and promotional value. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structural principle of the present invention.

[0040] Figure 2 This is a schematic diagram of the heat storage system structure of the present invention.

[0041] Figure 3 This is a schematic diagram of the heat release system structure of the present invention.

[0042] In the diagram: 100-Heat storage system, 101-Heat source unit, 1011-Boiler body, 1012-Superheater, 1013-Economizer; 102-Heat exchange flue, 103-First electronic control valve, 104-First thermal oil circulation unit; 200-Mobile molten salt heat storage terminal; 300-Heat release system, 301-Second thermal oil circulation unit, 302-Steam-water heat exchange unit, 3021-Steam-water heat exchanger, 3022-Steam drum, 3023-Heat user module, 303-Electric heating unit. Detailed Implementation

[0043] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this specification are for illustrative purposes only.

[0044] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0045] like Figures 1-3 As shown, a molten salt phase change heat transfer system includes:

[0046] Mobile molten salt thermal storage terminal 200, thermal storage system 100 and thermal release system 300;

[0047] The mobile molten salt thermal storage terminal 200 uses low-temperature phase change molten salt as the thermal storage medium to connect the thermal storage system 100 and the heat release system 300.

[0048] The heat storage system 100 is used to transfer low-grade industrial waste heat to the molten salt heat storage unit 20 via heat transfer oil;

[0049] The heat release system 300 is used to output the heat stored in the mobile molten salt thermal storage terminal 200 for heating.

[0050] As one implementation method, the composition and mass percentage of the low-temperature phase change molten salt are as follows:

[0051] It contains 53% potassium nitrate, 40% sodium nitrite, and 7% sodium nitrate, with a melting point of 140-150℃.

[0052] In one embodiment, the heat storage system 100 includes:

[0053] Heat source unit 101 is used to provide the industrial waste heat required by the mobile molten salt thermal storage terminal 200;

[0054] Heat exchange flue 102 is used to exhaust flue gas from heat source unit 101 at a temperature not exceeding 200°C;

[0055] The first electronic control valve 103 is used to monitor the temperature and flow rate of flue gas in the heat exchange flue 102 and regulate the flue gas entering the heat exchange flue 102.

[0056] The first heat transfer oil circulation unit 104 is used to connect the heat exchange flue 102 and the mobile molten salt heat storage terminal 200.

[0057] The heat transfer oil is heated by flue gas in the heat exchange flue 102. The heated high-temperature heat transfer oil flows into the mobile molten salt heat storage terminal 200, causing the solid molten salt to change into a liquid state for heat storage.

[0058] In one embodiment, the heat source unit 101 includes a boiler body 1011, a superheater 1012 and an economizer 1013. The superheater 1012 is located in the high-temperature zone of the furnace outlet of the boiler body 1011, and the economizer 1013 is located in the boiler tail flue area of ​​the boiler body 1011.

[0059] The heat exchange flue 102 is connected to the boiler body 1011 at the position of the 200°C flue gas in front of the economizer 1013.

[0060] As one implementation, the heat dissipation system 300 includes:

[0061] The second heat transfer oil circulation unit 301 is used to connect to the mobile molten salt heat storage terminal 200 and to pass room temperature heat transfer oil into the mobile molten salt heat storage terminal 200 to be heated by liquid molten salt.

[0062] The steam-water heat exchange unit 302 is used to connect to the second heat transfer oil circulation unit 301, and heats the return water of the steam-water heat exchange unit 302 to generate steam by heating the heated high-temperature heat transfer oil.

[0063] The electric heating unit 303 is used to heat the heat transfer oil of the second heat transfer oil circulation unit 301 during off-peak electricity periods to supplement the heat supply.

[0064] In one embodiment, both the first heat transfer oil circulation unit 104 and the second heat transfer oil circulation unit 301 include an oil storage tank and a heat transfer oil pipe, wherein:

[0065] The oil storage tank of the first heat transfer oil circulation unit 104 temporarily stores excess heat for peak shaving.

[0066] The oil storage tank of the second heat transfer oil circulation unit 301 stores heat transfer oil heated by off-peak electricity for supplementary heating.

[0067] In one embodiment, the steam-water heat exchange unit 302 includes:

[0068] The steam-water heat exchanger 3021 is used to connect the heat transfer oil pipe of the second heat transfer oil circulation unit 301, and heats the return water to generate steam through the high temperature heat transfer oil in the heat transfer oil pipe;

[0069] Steam drum 3022 is used to receive the steam-water mixture from steam-water heat exchanger 3021 and separate and output pure saturated steam;

[0070] The heat user module 3023 is used to receive pure saturated steam from the steam drum 3022 for heat use and to circulate the returned heat water to the steam-water heat exchanger 3021 for reheating.

[0071] As one implementation method, the mobile molten salt thermal storage terminal 200 is a mobile thermal storage vehicle, whose molten salt filling amount is dynamically adjusted according to the residual heat of the heat source and the demand of heat users. The mobile thermal storage vehicle has strong flexibility and can adapt to changes in the location and heat load of the heat source and heat users. The number, frequency and scale of the thermal storage vehicles can be adjusted according to the heat usage. If the heat source or heat user is relocated, the route of the thermal storage vehicle can also be adjusted or the thermal storage vehicle can be canceled, avoiding the problem of abandonment due to the relocation of heat users after the investment in the pipeline network.

[0072] In one embodiment, the electric heating unit 303 includes:

[0073] An electric heater is used to convert electrical energy into heat energy to directly heat the heat transfer oil in the oil storage tank of the second heat transfer oil circulation unit 301;

[0074] A temperature sensor is used to monitor the temperature of the heat transfer oil in the oil storage tank of the second heat transfer oil circulation unit 301 in real time.

[0075] A circulating pump is used to drive the heat transfer oil to circulate between the electric heater, the oil storage tank of the second heat transfer oil circulation unit 301, and the steam-water heat exchanger 3021.

[0076] Safety interlock device for automatic power-off when the temperature exceeds 300℃ to prevent thermal oil cracking.

[0077] At the industrial waste heat source (heat source unit 101), the flue gas at the 200°C flue gas position in front of the economizer 1013 is led to the heat exchange flue 102.

[0078] The heat transfer oil is heated by flue gas, and the high-temperature heat transfer oil causes the solid molten salt in the molten salt heat storage unit to change into a liquid state for heat storage.

[0079] The mobile molten salt thermal storage terminal 200 is adjusted to the heat user area (heat release system 300).

[0080] The ambient temperature heat transfer oil inside the second heat transfer oil circulation unit 301 in the heat release system 300 is introduced into the mobile molten salt heat storage terminal 200 to absorb the latent heat of the molten salt. The heated high temperature heat transfer oil flows through the steam-water heat exchanger 3021 of the steam-water heat exchange unit 302 to heat the return water and generate steam for heating.

[0081] During off-peak hours, the heat transfer oil is heated by the electric heating unit 303 and stored in the oil storage tank of the second heat transfer oil circulation unit 301 to supplement peak heating demand.

[0082] It should be noted that while the preferred embodiments of the present invention are provided in the specification and accompanying drawings, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of the present invention; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A molten salt phase change heat transfer system characterized by, The application relates to a mobile molten salt heat storage terminal, a heat storage system and a heat release system. The mobile molten salt heat storage terminal uses low-temperature phase-change molten salt as heat storage medium to connect the heat storage system and the heat release system. The heat storage system is used for transmitting low-grade industrial waste heat to the molten salt heat storage unit through heat conducting oil. The heat release system is used for outputting the heat stored in the mobile molten salt heat storage terminal. The low-temperature phase-change molten salt comprises the following components and mass percentages: 53% of potassium nitrate, 40% of sodium nitrite and 7% of sodium nitrate, and the melting point is 140-150 DEG C.

2. The molten salt phase change thermal transfer system of claim 1, wherein, The heat storage system comprises: A heat source unit is arranged for providing industrial waste heat required by the mobile molten salt heat storage terminal.

3. The molten salt phase change thermal transfer system of claim 1, wherein, A heat exchange flue is arranged for discharging flue gas of the heat source unit which is not higher than 200 DEG C. A first electronic control valve is arranged for monitoring the temperature and flow of the flue gas in the heat exchange flue and regulating the flue gas into the heat exchange flue. A first heat conducting oil circulating unit is arranged for connecting the heat exchange flue and the mobile molten salt heat storage terminal. The flue gas in the heat exchange flue is used for heating the heat conducting oil, and the high-temperature heat conducting oil after being heated flows into the mobile molten salt heat storage terminal to make the solid molten salt change into liquid heat storage. The heat source unit comprises a boiler body, a superheater and an economizer, the superheater is arranged in the high-temperature zone of the furnace outlet of the boiler body, and the economizer is arranged at the tail flue of the boiler body. The heat exchange flue is communicated with the position of the boiler body close to the 200 DEG C flue gas of the front section of the economizer.

4. The molten salt phase change thermal transfer system of claim 3, wherein, The heat release system comprises: A second heat conducting oil circulating unit is arranged for connecting the mobile molten salt heat storage terminal, and normal-temperature heat conducting oil is introduced into the mobile molten salt heat storage terminal to be heated by the liquid molten salt.

5. The molten salt phase change thermal transfer system of claim 4, wherein, A steam-water heat exchange unit is arranged for connecting the second heat conducting oil circulating unit, and the high-temperature heat conducting oil after being heated is used for heating the return water of the steam-water heat exchange unit to generate steam. An electric heating unit is arranged for heating the heat conducting oil of the second heat conducting oil circulating unit in the valley electricity period to supplement heat supply. The first heat conducting oil circulating unit and the second heat conducting oil circulating unit both comprise an oil storage and a heat conducting oil pipe. The oil storage of the first heat conducting oil circulating unit temporarily stores surplus heat for peak regulation; 6. The molten salt phase change thermal transfer system of claim 5, wherein, The oil storage of the second heat conducting oil circulating unit stores the heat conducting oil heated in the valley electricity period for supplementing heat supply. The steam-water heat exchange unit comprises: A steam-water heat exchanger is arranged for connecting the heat conducting oil pipe of the second heat conducting oil circulating unit, and the high-temperature heat conducting oil in the heat conducting oil pipe is used for heating the return water to generate steam.

7. The molten salt phase change thermal transfer system of claim 6, wherein, A steam drum is arranged for receiving the steam-water mixture from the steam-water heat exchanger and separating and outputting pure saturated steam. A heat user module is arranged for receiving the pure saturated steam from the steam drum to be heated and circulating the heated return water to the steam-water heat exchanger to be heated again. The mobile molten salt heat storage terminal is a mobile heat storage vehicle, and the filling amount of the molten salt is dynamically adjusted according to the waste heat amount of the heat source point and the heat user demand. ​ 8. The molten salt phase change thermal transfer system of claim 5, wherein, ​

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