Fused salt electric heating control system

Abstract

The utility model provides a fused salt electric heating control system which can realize accurate control of high temperature of fused salt, prevent over-temperature decomposition of the fused salt and achieve efficient heat storage. The device comprises a molten salt cold tank, a molten salt hot tank, a cold molten salt pipeline, a hot molten salt pipeline, an electric heater array and a PLC (Programmable Logic Controller) system, the fused salt cold tank is connected with an inlet of the electric heater array through a cold fused salt pipeline, and the fused salt hot tank is connected with an outlet of the electric heater array through a hot fused salt pipeline; the electric heater group column comprises multiple stages of electric heater groups which are sequentially connected in series; the PLC system is connected with the electric heater group; the device is characterized in that in the electric heater group array, the electric power of the electric heater group is gradually reduced; the inlet and the outlet of each stage of electric heater group are respectively provided with a temperature sensor, and the PLC system is connected with the temperature sensors.

Description

Technical Field

[0001] The utility model relates to a molten salt electric heating control system, which is used in a heat storage system in the power industry. Background Art

[0002] In recent years, the installed capacity and power generation of renewable energy have grown rapidly. Due to the intermittent and unstable output of renewable energy sources such as wind and solar power, the challenges of accommodating large-scale grid-connected power and flexibly shaving the peak load of existing coal-fired power units have become urgent international challenges. Coupling large-capacity molten salt energy storage technology with heating systems using surplus electricity can address the challenges of accommodating renewable energy power, flexibly shaving peak loads, and intelligently managing and controlling it. This provides a new model for the low-carbon transformation and upgrading of energy supply companies, and is of great significance to the country's timely achievement of carbon peak and carbon neutrality.

[0003] Molten salt is widely used in electric heating and heat storage systems due to its high heat capacity and low corrosiveness. Conventional molten salt electric heating systems use electric heaters of equal power. The flow rate of cold molten salt is controlled by adjusting the opening of the regulating valve at the outlet of the low-temperature molten salt pump, and the outlet temperature of the molten salt is controlled by adjusting the power of the electric heater group. After heating, the high-temperature molten salt is stored in a high-temperature storage tank, achieving a heat-to-electricity energy storage process.

[0004] Molten salt decomposes at high temperatures, resulting in not only salt loss but also toxic and harmful gases, significantly harming system operation. Conventional electric heating, using the same power, lacks precise temperature control due to its simple setup and single control system. Furthermore, it is prone to overheating and decomposition, preventing effective heat storage and posing significant system risks.

[0005] Therefore, it is necessary to design a technology that can achieve accurate control of the high temperature of molten salt to prevent the molten salt from over-temperature decomposition and achieve efficient heat storage. Utility Model Content

[0006] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a molten salt electric heating control system with a rational structural design, which can accurately control the high temperature of the molten salt, prevent the molten salt from overheating and decomposing, and achieve efficient heat storage.

[0007] The technical solution adopted by the utility model to solve the above problems is: a molten salt electric heating control system, including a molten salt cold tank, a molten salt hot tank, a cold molten salt pipeline, a hot molten salt pipeline, an electric heater group and a PLC system; the molten salt cold tank is connected to the inlet of the electric heater group through the cold molten salt pipeline, and the molten salt hot tank is connected to the outlet of the electric heater group through the hot molten salt pipeline; the electric heater group includes a multi-stage electric heater group, and the multi-stage electric heater groups are sequentially connected in series; the PLC system is connected to the electric heater group; it is characterized in that: in the electric heater group, the electric power of the electric heater group is reduced step by step; a temperature sensor is provided at the inlet and outlet of each stage of the electric heater group, and the PLC system is connected to the temperature sensor.

[0008] The utility model provides an on-off valve and a check valve installed on the cold molten salt pipeline.

[0009] The utility model provides an on-off valve installed on the hot molten salt pipeline.

[0010] The electric heater group array described in the utility model is provided with four sets of electric heater groups, and the electric powers of the four sets of electric heater groups are 6MW, 5.5MW, 4MW and 2MW respectively.

[0011] Each level of the electric heater group of the utility model comprises two sets of electric heaters, which are connected in series and arranged vertically up and down.

[0012] Except for the last stage, the temperature control system of the electric heater at the bottom of the electric heater group of the other stages adopts thyristor, and the temperature control system of the electric heater at the top adopts relay; the temperature control system of the electric heater at the top of the last stage electric heater group adopts thyristor, and the temperature control system of the electric heater at the bottom adopts relay; the relay and thyristor are connected to the PLC system.

[0013] The thyristor of the electric heater at the lower part of the last-stage electric heater group of the utility model is arranged close to the outlet of the electric heater group array.

[0014] The utility model provides a temperature sensor between the two sets of electric heaters in the last stage electric heater group.

[0015] The electric heater groups described in the utility model are divided into two or more sets and are arranged in parallel.

[0016] Compared with the prior art, the utility model has the following advantages and effects: a group of electric heaters is divided into multiple levels of electric heaters, so that the front end or the first few levels of the group can quickly heat up with high power, and the back end can heat up slightly with low power, thereby approaching the target temperature, and can achieve accurate control of the high temperature of the molten salt, prevent the molten salt from over-temperature decomposition, and achieve efficient heat storage; through the hierarchical setting, the front end can reduce the equipment material in time, while achieving accurate control of the outlet temperature, saving investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of an embodiment of the present utility model. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are provided to explain the present invention, but the present invention is not limited to the following examples.

[0019] The embodiment of the utility model includes a molten salt cold tank 1, a molten salt hot tank 2, a cold molten salt pipeline 3, a hot molten salt pipeline 4, an electric heater group 5, a PLC system 6, a temperature sensor 7, an on-off valve 8 and a check valve 9.

[0020] The molten salt cold tank 1 is connected to the inlet of the electric heater array 5 through a cold molten salt pipeline 3 , on which a switch valve 8 and a check valve 9 are installed.

[0021] The molten salt hot tank 2 is connected to the outlet of the electric heater array 5 through a hot molten salt pipeline 4 , and a switch valve 8 is installed on the hot molten salt pipeline 4 .

[0022] The electric heater group 5 includes a multi-stage electric heater group 5-1, which is connected in series in sequence, and the electric power of these electric heater groups 5-1 is reduced step by step. The first few stages of the electric heater group 5-1 are far from the hot molten salt outlet temperature, so they use high power to heat and heat quickly. The electric power of the last few stages of the electric heater group 5-1 is gradually reduced. By slightly increasing the temperature, precise temperature control is achieved, effectively ensuring that the system does not overheat, and the first few stages of the molten salt outlet temperature is not high. The equipment material selection can be appropriately reduced to reduce the entire investment of the system. In this embodiment, four sets of electric heater groups 5-1 are provided, and the electric power of the four sets of electric heater groups 5-1 is 6MW, 5.5MW, 4MW and 2MW respectively. The first two stages account for more than 65%, and the power of the last stage of the electric heater group 5-1 is significantly low, achieving rapid heating with high power at the front end and precise temperature control with low power at the back end. A temperature sensor 7 is provided at the inlet and outlet of each stage of the electric heater group 5-1, and the PLC system 6 is connected to the temperature sensor 7.

[0023] Each level of electric heater group 5-1 includes two sets of electric heaters 5-2, which are connected in series and arranged vertically, facilitating the draining of molten salt during equipment maintenance. The two sets of electric heaters 5-2 have the same electrical power. Except for the last level, the temperature control system for the lower electric heater 5-2 in each level of electric heater group 5-1 uses a thyristor, while the temperature control system for the upper electric heater 5-2 uses a relay. The relay can only achieve a full on or full off function. The last level of electric heater group 5-1 is set differently from the previous levels. The temperature control system for the upper electric heater 5-2 uses a thyristor, while the temperature control system for the lower electric heater 5-2 uses a relay. The thyristor is preferably placed near the outlet of the electric heater group 5 to facilitate the system's final control of the outlet temperature. When the power is below 50% of the power of a single set of electric heaters 5-2, only the thyristors are adjusted to achieve the power; when the power exceeds 50%, the relay is first turned on to reach 50% of the power, and then the thyristors are adjusted to achieve the required power. This configuration can achieve full power control while reducing the number of thyristors and optimizing investment.

[0024] The PLC system 6 is connected to the relays and thyristors in the electric heater group 5-1, and further connected to the electric heater group 5-1. The operation of the electric heater 5-2 is controlled by the PLC system 6.

[0025] A temperature sensor 7 may be further provided between the two sets of electric heaters 5-2 of the last-stage electric heater group 5-1 to turn on or adjust the temperature according to the outlet temperature of each portion of the electric heaters 5-2, thereby achieving subdivided depth control of the outlet temperature.

[0026] Due to the maximum power limit of a single set of electric heaters, the electric heater group 5 can be more than two sets, which can be set in parallel to achieve system backup and large-capacity heat storage for the project.

[0027] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is merely an example of the structure of the utility model. Any equivalent changes or simple changes made based on the structure, features and principles described in the concept of the utility model patent are included in the scope of protection of the utility model patent. Technicians in the technical field of the utility model can make various modifications or supplements to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should fall within the scope of protection of the utility model.

Claims

1. A molten salt electric heating control system, comprising a molten salt cold tank, a molten salt hot tank, a cold molten salt pipeline, a hot molten salt pipeline, an electric heater group and a PLC system; the molten salt cold tank is connected to the inlet of the electric heater group through the cold molten salt pipeline, and the molten salt hot tank is connected to the outlet of the electric heater group through the hot molten salt pipeline; the electric heater group includes a multi-stage electric heater group, and the multi-stage electric heater groups are sequentially connected in series; the PLC system is connected to the electric heater group; it is characterized in that: In the electric heater group array, the electric power of the electric heater group is reduced step by step; temperature sensors are arranged on the inlet and outlet of each stage of the electric heater group, and the PLC system is connected to the temperature sensors.

2. The molten salt electric heating control system according to claim 1 is characterized in that: A switch valve and a check valve are installed on the cold molten salt pipeline.

3. The molten salt electric heating control system according to claim 1 is characterized in that: An on-off valve is installed on the hot molten salt pipeline.

4. The molten salt electric heating control system according to claim 1 is characterized in that: The electric heater group array is provided with four sets of electric heater groups, and the electric powers of the four sets of electric heater groups are 6MW, 5.5MW, 4MW and 2MW respectively.

5. The molten salt electric heating control system according to claim 1 is characterized in that: Each level of electric heater group includes two sets of electric heaters, which are connected in series and arranged vertically up and down.

6. The molten salt electric heating control system according to claim 5, characterized in that: Except for the last level, the temperature control system of the lower electric heater of the remaining electric heater groups adopts thyristor, and the temperature control system of the upper electric heater adopts relay; the temperature control system of the upper electric heater of the last level electric heater group adopts thyristor, and the temperature control system of the lower electric heater adopts relay; the relay and thyristor are connected to the PLC system.

7. The molten salt electric heating control system according to claim 6, characterized in that: The thyristor of the upper electric heater of the last stage electric heater group is arranged close to the outlet of the electric heater group array.

8. The molten salt electric heating control system according to claim 5, characterized in that: A temperature sensor is additionally provided between the two sets of electric heaters in the last-stage electric heater group.

9. The molten salt electric heating control system according to claim 1, characterized in that: The electric heater groups are divided into two or more sets, which are arranged in parallel.

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