A steam heating system for preventing leakage of nuclear power secondary medium

Abstract

The present invention discloses a steam heating system for preventing leakage of secondary medium of nuclear power, including a secondary medium loop, a high-pressure circulating water loop and a low-pressure medium loop. Heat is transferred between the secondary medium and the high-pressure circulating water, and between the high-pressure circulating water and the low-pressure medium through a heat exchanger. When the system is running, the pressure of the high-pressure circulating water loop is kept higher than the pressure of the secondary medium loop, and the pressure of the low-pressure medium loop is kept lower than the pressure of the secondary medium loop. The present invention establishes a high-pressure circulating water loop between the secondary medium loop and the low-pressure medium loop, and makes the pressure of the high-pressure circulating water loop higher than that of the secondary medium loop regardless of normal operation, start-stop or accident state, thereby effectively preventing leakage of secondary medium, ensuring the safety of low-pressure medium for external heat supply, and making it possible to use nuclear energy for external heat supply. The invention also provides similar solutions for other energy utilization systems that need to prevent leakage of media.

Description

Technical Field

[0001] The invention relates to a steam heating system for preventing leakage of nuclear power secondary medium, and belongs to the field of industrial heating and residential heating using a special method. Background Art

[0002] In recent years, with the increase in industrial heat and residential heating needs, as well as the upgrade and replacement of traditional coal-fired and gas-fired decentralized heating methods, centralized heating technology using low-pressure steam as a heat source has gradually become an important aspect of energy utilization.

[0003] The flexibility transformation of thermal power units is to adapt to the peak load regulation requirements of the power grid, and is also a positive response of conventional coal-fired units to the market demand for heating. Against the backdrop of the continuous improvement of the power auxiliary market, this flexibility transformation not only increases the peak load regulation capacity of the units, but also brings considerable economic benefits to the power plant by participating in deep peak load regulation and external centralized heating.

[0004] Nuclear power units are an important part of my country's non-fossil fuel installed capacity. As of June 2019, my country's nuclear power installed capacity reached 48.6 million kilowatts. Nuclear power units bear the basic load type in my country's power grid, which is determined by the characteristics of nuclear power. If nuclear power can be used to provide external heat, it can not only increase the heat supply revenue of the power station, but also achieve a certain peak load regulation effect. However, nuclear power heat supply must be carried out under the premise of fully ensuring safety.

[0005] At present, the pressurized water reactor technology is mature, reliable and has the highest commercialization rate in the field of nuclear power. The secondary medium of this type of power station is saturated steam with a certain pressure level, which is generated by the steam generation system in the nuclear island and then transported to the steam power system to generate power. Nuclear power external heat supply uses the secondary medium as a heat source to generate low-pressure steam or hot water to meet the external heating needs. Since the low-pressure steam or hot water is an open system transported to industrial or residential areas, it is necessary to fundamentally eliminate the leakage problem that may be caused by the secondary medium to ensure the safety of nuclear power external heat supply.

[0006] If the secondary medium is used to directly generate a low-pressure heating medium (steam or hot water), there is a risk of leakage of the secondary medium to the heating medium because the pressure of the secondary medium is higher than the steam or hot water used for heating. Based on the above situation, the present invention proposes a new heat exchange system, which eliminates the possibility of leakage of the secondary medium from a technical perspective, making it possible for nuclear power to provide external heat. Summary of the invention

[0007] In order to solve the above technical problems, the present invention designs a steam heating system for preventing leakage of nuclear power secondary medium, ensuring that the secondary medium will not leak out, and at the same time generating low-pressure medium (steam or hot water) with required parameters for external heating.

[0008] The present invention adopts the following technical solution:

[0009] A steam heating system for preventing leakage of nuclear power secondary medium comprises a secondary medium loop, a high-pressure circulating water loop and a low-pressure medium loop. Heat is transferred between the secondary medium loop and the high-pressure circulating water loop, and between the high-pressure circulating water loop and the low-pressure medium loop via a heat exchanger. When the system is in operation, the pressure of the high-pressure circulating water loop is kept higher than the pressure of the secondary medium loop, and the pressure of the low-pressure medium loop is kept lower than the pressure of the secondary medium loop.

[0010] Preferably, the secondary medium circuit comprises a secondary medium inlet, a steam condenser and a secondary medium outlet which are connected in sequence.

[0011] Preferably, the high-pressure circulating water loop comprises a high-pressure circulating water pump, a steam condenser, a pressure stabilizing device and a low-pressure evaporator which are cyclically connected in sequence.

[0012] Preferably, the low-pressure medium circuit includes a low-pressure evaporator, a steam drum, a low-pressure medium inlet and a low-pressure medium outlet, and the low-pressure evaporator, the low-pressure medium inlet and the low-pressure medium outlet are respectively connected to the steam drum.

[0013] Preferably, the secondary medium loop in the steam condenser passes through the shell side of the steam condenser, and the high-pressure circulating water loop passes through the tube side of the steam condenser.

[0014] Preferably, the high-pressure circulating water loop in the low-pressure evaporator passes through the tube side of the low-pressure evaporator, and the low-pressure medium loop passes through the shell side of the low-pressure evaporator.

[0015] Preferably, the high-pressure circulating water circuit, the secondary medium circuit and the low-pressure medium circuit are all provided with safety valves.

[0016] The steam condenser releases the heat of the secondary medium to the high-pressure circulating water, and the low-pressure evaporator releases the heat of the high-pressure circulating water to the heating medium. The high-pressure circulating water pump is the power device that drives the high-pressure circulating water. The pressure stabilizing device ensures that the high-pressure circulating water loop operates within the required parameter range. The steam drum is the steam-water separation device of the low-pressure medium loop, and the saturated steam generated is transported to external heat users.

[0017] The secondary medium loop can be saturated steam generated by nuclear power, or other media with special properties, such as corrosive, toxic, or polluting media. The above scheme or derivative schemes can be used to protect the system and avoid leakage of the medium.

[0018] The pressure stabilizing device is an important component of the high-pressure circulating water loop. Depending on the energy source, it can be electric heating or steam heating to produce saturated steam at a certain pressure on the top of the pressure stabilizing tank, or it can be directly filled with other gases with adjustable pressure on the top.

[0019] If the system ultimately produces steam, a steam drum is provided in conjunction with the low-pressure evaporator. The low-pressure medium can also be hot water according to different user requirements. If hot water is supplied externally, the steam drum is omitted from the system, and the low-pressure evaporator is replaced by a water-water heat exchanger.

[0020] The beneficial effects of the present invention are: compared with using a secondary medium to directly heat a heating medium (water or water vapor), the present invention innovatively sets a high-pressure circulating water loop between the two medium loops, and maintains the pressure of the high-pressure circulating water loop higher than the pressure of the secondary medium loop under system operation, start-up, shutdown or failure conditions, thereby eliminating the possibility of leakage of the secondary medium and ensuring the safety of the system. At the same time, the steam or hot water generated by the high-pressure circulating water is used for heating. The present invention makes it possible to use nuclear power for industrial heating or residential heating, and also provides a solution for similar energy utilization systems that need to prevent leakage of media. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] In the figure: 1. High-pressure circulating water pump, 2. Steam condenser, 3. Pressure stabilizing device, 4. Steam drum, 5. Low-pressure evaporator. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0024] Example: As attached Figure 1 As shown, a steam heating system for preventing leakage of secondary medium of nuclear power includes a secondary medium circuit, a high-pressure circulating water circuit and a low-pressure medium circuit. Heat is transferred between the secondary medium circuit and the high-pressure circulating water circuit, and between the high-pressure circulating water circuit and the low-pressure medium circuit through a heat exchanger. When the system is running, the pressure of the high-pressure circulating water circuit is kept higher than the pressure of the secondary medium circuit, and the pressure of the low-pressure medium circuit is kept lower than the pressure of the secondary medium circuit. The secondary medium circuit includes a secondary medium inlet, a steam condenser 2 and a secondary medium outlet connected in sequence. The high-pressure circulating water circuit includes a high-pressure circulating water pump 1, a steam condenser 2, a pressure stabilizing device 3 and a low-pressure evaporator 5 that are connected in a circular manner in sequence. The low-pressure medium circuit includes a low-pressure evaporator 5, a steam drum 4, a low-pressure medium inlet and a low-pressure medium outlet. The low-pressure evaporator 5, the low-pressure medium inlet and the low-pressure medium outlet are respectively connected to the steam drum 4.

[0025] When the present invention is used, the secondary medium in the state of saturated steam enters the shell side of the steam condenser 2, transfers heat to the high-pressure circulating water flowing through the tube side, and the saturated steam becomes condensed water and returns to the nuclear island to complete the endothermic evaporation process. In the low-pressure evaporator 5, the low-pressure medium absorbs the heat released by the high-pressure circulating water, completes the process of heating and evaporation, and completes the steam-water separation in the steam drum 4, and then outputs it to the outside of the system for heat supply.

[0026] The high-pressure circulating water pump 1 pushes the circulating water to flow through the steam condenser 2 and the low-pressure evaporator 5 in sequence. In addition, the high-pressure circulating water loop also includes a pressure stabilizing device 3, which can enable the high-pressure circulating water to run stably at the required pressure.

[0027] When the system is running, the pressure of the high-pressure circulating water loop is kept higher than the pressure of the secondary medium loop, and the low-pressure medium loop generates hot water or steam with a relatively low pressure level according to user needs. If the steam condenser 2 leaks during operation, first cut off the passage of the secondary medium in and out of the steam condenser 2, and discharge the remaining secondary medium in the steam condenser 2 in time, then release the pressure of the high-pressure circulating water loop, drain the water in the loop, and repair the steam condenser 2.

[0028] When the system is put into operation, it is also necessary to build up the pressure in the high-pressure circulating water loop before putting it into the secondary medium loop; when the system is shut down, first cut off the secondary medium loop, and after the pressure of the secondary medium loop drops, the pressure on the high-pressure circulating water side is lowered.

[0029] In the above processes (operation, commissioning, shutdown, and failure conditions), since the pressure of the high-pressure circulating water loop is always kept higher than the pressure on the secondary medium side, the risk of secondary medium leakage can be eliminated, ensuring that the hot water or steam in the low-pressure medium loop will not be contaminated, ensuring the reliability of heat supply, and making it possible to use nuclear energy to supply heat to the outside. The invention also provides similar solutions for other energy utilization systems that need to prevent medium leakage.

[0030] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A steam heating system for preventing leakage of nuclear power secondary medium, characterized in that: It includes a secondary medium circuit, a high-pressure circulating water circuit and a low-pressure medium circuit. Heat is transferred between the secondary medium circuit and the high-pressure circulating water circuit, and between the high-pressure circulating water circuit and the low-pressure medium circuit through a heat exchanger. When the system is running, the pressure of the high-pressure circulating water circuit is kept higher than the pressure of the secondary medium circuit, and the pressure of the low-pressure medium circuit is kept lower than the pressure of the secondary medium circuit. The secondary medium circuit comprises a secondary medium inlet, a steam condenser and a secondary medium outlet which are connected in sequence; The high-pressure circulating water loop comprises a high-pressure circulating water pump, a steam condenser, a pressure stabilizing device and a low-pressure evaporator which are cyclically connected in sequence; The low-pressure medium circuit comprises a low-pressure evaporator, a steam drum, a low-pressure medium inlet and a low-pressure medium outlet. The low-pressure evaporator, the low-pressure medium inlet and the low-pressure medium outlet are respectively connected to the steam drum.

2. A steam heating system for preventing leakage of secondary medium of nuclear power according to claim 1, characterized in that: The secondary medium loop in the steam condenser passes through the shell side of the steam condenser, and the high-pressure circulating water loop passes through the tube side of the steam condenser.

3. A steam heating system for preventing leakage of secondary medium of nuclear power according to claim 1, characterized in that: The high-pressure circulating water loop in the low-pressure evaporator passes through the tube side of the low-pressure evaporator, and the low-pressure medium loop passes through the shell side of the low-pressure evaporator.

4. A steam heating system for preventing leakage of secondary medium of nuclear power according to claim 1, characterized in that: The high-pressure circulating water circuit, the secondary medium circuit and the low-pressure medium circuit are all provided with safety valves.

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