Method and system for adjusting and controlling industrial steam supply quality of nuclear power plant

Abstract

The invention relates to the field of nuclear energy heat supply, in particular to a method and system for adjusting and controlling the industrial steam supply quality of a nuclear power plant. The system is characterized in that a heat supply main steam pipeline system is respectively connected with four rows of steam conversion equipment, and each row of steam conversion equipment comprises a superheater, an evaporator, a preheater, a water feeding pump and an industrial water tank which are connected in sequence. According to the method, adjustment control is carried out based on the system, and the adjustment control comprises control under the four conditions of normal operation, starting, normal shutdown and operation under the accident or fault condition. High-quality steam supply is achieved, the quality and reliability of gas supply are improved, and the requirement for industrial gas supply is met.

Description

Technical Field

[0001] The present invention relates to the field of nuclear energy heating, and in particular to a method and system for regulating and controlling the quality of industrial steam supply in a nuclear power plant. Background Art

[0002] Steam energy supply is to use the heat energy of the secondary circuit main steam pipeline of the nuclear power plant to heat the desalted water in the industrial steam system to superheated steam, and then send the superheated steam to local industrial enterprises through the gas supply pipeline. Since there will be heat loss when the steam is directly conducted, it will not meet the use requirements when it reaches the local enterprises, which makes it very important to control the quality of industrial steam supply during transportation. However, in the field of comprehensive utilization of nuclear energy, there is no experience to draw on for using the secondary circuit steam of nuclear power plants as a heat source to produce industrial steam. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for regulating and controlling the quality of industrial steam supply in a nuclear power plant, thereby realizing the supply of high-quality steam, improving the quality and reliability of gas supply, and meeting the requirements of industrial gas supply.

[0004] The present invention provides a regulation and control system for the quality of industrial steam supply in a nuclear power plant, comprising:

[0005] The main steam pipeline system for heating is connected to four trains of steam conversion equipment respectively, and each train of steam conversion equipment includes a superheater, an evaporator, a preheater, a feed water pump and an industrial water tank connected in sequence;

[0006] The main steam pipeline system for heating is connected to four main steam pipeline branches, which are respectively connected to the tube-side inlets of four superheaters;

[0007] The main steam on the hot side of the superheater flows through the tube side, and the saturated industrial steam medium on the cold side flows through the shell side, realizing reverse convection heat exchange between the cold and hot media; the superheated steam output by the superheater is transported to the industrial steam main pipe; the inlet on the tube side of the evaporator is the main steam, and the outlet is supercooled condensed water;

[0008] The main steam flows through the tube side of the superheater to superheat the saturated industrial steam on the shell side, and then enters the tube side of four evaporators through four manual isolation valves and four main steam regulating valves respectively. The main steam flows through the tube side of the four evaporators and heats the shell side feed water to be converted into supercooled condensed water, and enters the tube side of four preheaters respectively. The main steam regulating valve tracks the steam production pressure of the industrial steam main pipe at the superheater outlet and matches the corresponding main steam flow to ensure the steam flow requirements of the heat users.

[0009] In a specific embodiment of the present invention, each row of steam conversion equipment provides a flow rate of 25%, and the maximum operating flow rate of a single channel is 33%.

[0010] In a specific embodiment of the present invention, the evaporator is a horizontal kettle, U-tube, four-pass surface heating evaporator, the main steam on the hot side is condensed and heat exchanged in the first two tube passes, the main steam condensate is reduced in the last two tube passes for heat exchange by subcooling, and the industrial feed water on the cold side is heated and evaporated outside the tube.

[0011] In a specific embodiment of the present invention, the superheater is a horizontal, U-tube, double-flow surface heating heater.

[0012] The present invention also provides a method for regulating and controlling the quality of industrial steam supply to a nuclear power plant, which is based on the regulating and controlling system for the quality of industrial steam supply to a nuclear power plant described in the above technical solution and includes control in four situations: normal operation, startup, normal shutdown, and operation in the event of an accident or failure;

[0013] The control method during normal operation is:

[0014] When the evaporator and preheater are operating normally, the pipe-side isolation valves of the evaporator and superheater are all open, and the main steam regulating valve operates by tracking the industrial steam main pipe pressure at the superheater outlet;

[0015] The control method at startup is:

[0016] The four trains of steam conversion equipment are started simultaneously or one by one;

[0017] First, fill the evaporator with water and monitor the evaporator liquid level. When the liquid level reaches the normal level, open the pipe side isolation valve and start to pass the main steam into the superheater.

[0018] The main steam enters the evaporator after passing through the superheater and the main steam isolation valve. The feedwater acoustic wave on the shell side of the evaporator reaches saturation and gradually begins to generate steam;

[0019] As the main steam continues to flow into the evaporator, the steam production on the shell side of the evaporator increases, and the steam production pressure gradually builds up;

[0020] When the pressure of the industrial steam main pipe at the outlet reaches the preset value, the shell side outlet electric valve is opened, and the steam enters the heating network to warm up the pipes. After the heating of the heating network is completed, the pressure of the heating network is gradually established. When the industrial steam load reaches 20%, the main steam regulating valve is changed to track the pressure of the industrial steam main pipe at the superheater outlet, and the system realizes automatic control;

[0021] The control method during normal shutdown is:

[0022] The four trains of steam conversion equipment can be shut down simultaneously or one by one;

[0023] During the load reduction process of the steam energy supply system, the valves in the evaporator and superheater systems are maintained in normal operation; when the load is reduced to 20%, the main steam isolation valves at the tube side inlet are closed one by one, and the four steam conversion equipment are shut down in turn;

[0024] The control method of the accident or failure is:

[0025] When any equipment in a train of steam conversion equipment fails and needs to be shut down, the train of steam conversion equipment needs to be isolated; when isolating a train of steam conversion equipment, first adjust the control of the main steam regulating valve at the evaporator inlet to manual, gradually reduce the valve opening, and the other three trains of steam conversion equipment will automatically increase the load; when the main steam regulating valve of a shut-down train of equipment is fully closed, close all the inlet and outlet isolation valves of the train of equipment, close the electric isolation valve at the shell side outlet of the superheater, and at the same time, the other three trains of equipment share the steam supply load according to their capacity.

[0026] In a specific embodiment of the present invention, the heating rate of the evaporator and the superheater is not higher than 4°C / min, and the cooling rate is not higher than 4°C / min.

[0027] In a specific embodiment of the present invention, the preset value of the industrial steam main pipe pressure is 1.8 MPa.a.

[0028] In a specific embodiment of the present invention, the other three rows of equipment share the steam supply load at 3x33% capacity. Compared with the prior art, the method and system for regulating and controlling the quality of industrial steam supply to a nuclear power plant of the present invention has the following beneficial effects:

[0029] (1) The secondary circuit main steam is heated on the superheater tube side to heat the shell side industrial saturated steam to superheated steam, thereby achieving a stable improvement in steam quality;

[0030] (2) The main steam flow regulating valve is controlled by the outlet header pressure to track the pressure operation of the industrial steam bus pipeline at the superheater outlet, thereby achieving the effect of controlling the superheated steam pressure and temperature;

[0031] (3) Design a multi-channel redundant heating system that can operate simultaneously or column by column to ensure that when a single channel fails, it can be independently repaired and the remaining three channels meet the gas supply reliability requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram showing the structure of the control system for regulating the quality of industrial steam supply to a nuclear power plant;

[0033] In the figure, 1, the first superheater; 2, the second evaporator; 3, the first preheater; 4, the feed water pump 1A; 5, the feed water pump 1B; 6, the first industrial water tank; 7, the first pipe side isolation valve; 8, the first main steam regulating valve; 9, the first shell side outlet electric valve; 10, the outlet industrial steam main pipe pressure gauge 1A; 11, the outlet industrial steam main pipe pressure gauge 1B; 12, the outlet industrial steam main pipe pressure gauge 1C; 13, the superheater liquid level gauge 1A; 14, the superheater liquid level gauge 1B; 15, the superheater liquid level gauge 1C; 16, the first evaporator pipe side pressure gauge; 17, the evaporator liquid level gauge 1A; 18, the evaporator liquid level gauge 1B; 19, the evaporator liquid level gauge 1C;

[0034] 20. Second superheater; 21. Second evaporator; 22. Preheater; 23. Feedwater pump 2A; 24. Feedwater pump 2B; 25. Second industrial water tank; 26. Second pipe-side isolating valve; 27. Second main steam regulating valve; 28. Shell-side outlet electric valve 2; 29. ​​Export industrial steam main pipe pressure gauge 2A; 30. Export industrial steam main pipe pressure gauge 2B; 31. Export industrial steam main pipe pressure gauge 2C; 32. Superheater liquid level gauge 2A; 33. Superheater liquid level gauge 2B; 34. Superheater liquid level gauge 2C; 35. Second evaporator pipe-side pressure; 36. Evaporator liquid level gauge 2A; 37. Evaporator liquid level gauge 2B; 38. Evaporator liquid level gauge 2C;

[0035] 39. Third superheater; 40. Third evaporator; 41. Third preheater; 42. Feedwater pump 3A; 43. Feedwater pump 3B; 44. Third industrial water tank; 45. Third pipe-side isolating valve; 46. Third main steam regulating valve; 47. Third shell-side outlet electric valve; 48. Export industrial steam main pipe pressure gauge 3A; 49. Export industrial steam main pipe pressure gauge 3B; 50. Export industrial steam main pipe pressure gauge 3C; 51. Superheater liquid level gauge 3A; 52. Superheater liquid level gauge 3B; 53. Superheater liquid level gauge 3C; 54. Third evaporator pipe-side pressure; 55. Evaporator liquid level gauge 3A; 56. Evaporator liquid level gauge 3B; 57. Evaporator liquid level gauge 3C;

[0036] 58. Fourth superheater; 59. Fourth evaporator; 60. Fourth preheater; 61. Feed water pump 4A; 62. Feed water pump 4B; 63. Fourth industrial water tank; 64. Fourth pipe-side isolating valve; 65. Fourth main steam regulating valve; 66. Fourth shell-side outlet electric valve; 67. Export industrial steam main pipe pressure gauge 4A; 68. Export industrial steam main pipe pressure gauge 4B; 69. Export industrial steam main pipe pressure gauge 4C; 70. Superheater liquid level gauge 4A; 71. Superheater liquid level gauge 4B; 72. Superheater liquid level gauge 4C; 73. Fourth evaporator pipe side pressure; 74. Evaporator liquid level gauge 4A; 75. Evaporator liquid level gauge 4B; 76. Evaporator liquid level gauge 4C. DETAILED DESCRIPTION

[0037] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0038] The main process flow of industrial gas supply in nuclear power plants is as follows: the first-level feedwater pump transfers desalted water to the first-level preheater for heating, the first-level preheater heats the desalted water to about 135°C and transmits the water vapor to the industrial deaerator, the industrial deaerator collects and discharges the oxygen and other non-condensable gases contained in the water, and sends the remaining water vapor to the second-level preheater for heating through the second-level feedwater pump, the second-level preheater heats the water vapor to about 195°C and transmits it to the evaporator for heating to saturated steam at 212°C, and then the saturated steam is further heated to superheated steam at 252°C through the superheater and then transported to the outside of the nuclear power plant for gas use. It can be seen from the process flow that the quality of industrial gas supply is mainly controlled by the evaporator and superheater system to control the output steam pressure and temperature.

[0039] The preheater involved in the present invention is a two-stage preheater.

[0040] The embodiment of the present invention discloses a control system for regulating the quality of industrial steam supply in a nuclear power plant, such as Figure 1 As shown, including:

[0041] The main steam pipeline system for heating is connected to four trains of steam conversion equipment respectively, and each train of steam conversion equipment includes a superheater, an evaporator, a preheater, a feed water pump and an industrial water tank connected in sequence;

[0042] The main steam pipeline system for heating is connected to four main steam pipeline branches, which are respectively connected to the tube-side inlets of four superheaters;

[0043] The steam passing through the superheater is transported to the industrial steam main pipe;

[0044] The inlet of the evaporator tube side is main steam, and the outlet is supercooled condensed water; the main steam on the hot side of the superheater flows through the tube side, and the saturated industrial steam medium on the cold side flows through the shell side, realizing reverse convection heat exchange of cold and hot media;

[0045] The main steam flows through the tube side of the superheater to superheat the saturated industrial steam on the shell side, and then enters the tube side of four evaporators through four manual isolation valves and four main steam regulating valves respectively. The main steam flows through the tube side of the four evaporators and heats the shell side feed water to be converted into supercooled condensed water, and enters the tube side of four preheaters respectively. The main steam regulating valve tracks the steam production pressure of the industrial steam main pipe at the superheater outlet and matches the corresponding main steam flow to ensure the steam flow requirements of the heat users.

[0046] like Figure 1As shown in the figure, a steam conversion device is used as an example for explanation:

[0047] The main steam pipeline system for heating is connected to the tube-side inlet of the first superheater 1 through the main steam pipeline branch. The first superheater 1 is provided with three liquid level measuring devices, namely, superheater liquid level gauge 1A13, superheater liquid level gauge 1B14, and superheater liquid level gauge 1C15. During the control process, the liquid level of the first superheater 1 is the average value of the liquid levels measured by the three liquid level measuring devices.

[0048] The first superheater 1 is connected to the second evaporator 2, and the first evaporator tube side pressure gauge 16, the first tube side isolation valve 7, and the first main steam regulating valve 8 are arranged on the tube side; the liquid level of the second evaporator 2 is measured by three liquid level gauges, namely, evaporator liquid level gauge 1A17, evaporator liquid level gauge 1B18, and evaporator liquid level gauge 1C19;

[0049] The second evaporator 2 is connected to the first preheater 3, and the first preheater 3 is connected to the first industrial water tank 6 through two pipelines, and a water supply pump 1A4 and a water supply pump 1B5 are respectively arranged on the pipelines;

[0050] The outlet of the first superheater 1 is connected to the industrial steam main pipe, and the first shell side outlet electric valve 9 is arranged at the outlet. The pressure at the outlet is measured by three outlet industrial steam main pipe pressure gauges, namely, outlet industrial steam main pipe pressure gauge 1A10, outlet industrial steam main pipe pressure gauge 1B11, and outlet industrial steam main pipe pressure gauge 1C12.

[0051] The structures of the other three steam conversion equipment are the same as those of the above steam conversion equipment and are mutually redundant. The four steam conversion equipment can be operated simultaneously or one by one to ensure that when a single channel fails, it can be independently repaired and the remaining three channels meet the gas supply reliability requirements. In the steam conversion equipment, the key measuring point instruments measure synchronously in multiple channels, and the logic is optimized to output reasonable values.

[0052] Each row of steam conversion equipment provides 25% of the flow rate, and the maximum operating flow rate of a single channel is 33%.

[0053] The evaporator is a horizontal kettle, U-tube, four-pass surface heating evaporator. The main steam on the hot side is condensed and heat exchanged in the first two tube passes, the main steam condensate is reduced in the second two tube passes for heat exchange, and the industrial feed water on the cold side is heated and evaporated outside the tube.

[0054] The superheater is a horizontal, U-shaped tube, double-flow surface heating heater.

[0055] The embodiment of the present invention also discloses a method for regulating and controlling the quality of industrial steam supply to a nuclear power plant, which is based on the regulating and controlling system for the quality of industrial steam supply to a nuclear power plant described in the above technical solution and includes: normal operation, startup, normal shutdown, and operation under accident or failure conditions, and control under four conditions;

[0056] The control method during normal operation is:

[0057] When the evaporator and preheater are operating normally, the pipe-side isolation valves of the evaporator and superheater are all open, and the main steam regulating valve operates by tracking the industrial steam main pipe pressure at the superheater outlet;

[0058] The industrial steam main pipe pressure is selected as the average value of the three outlet industrial steam main pipe pressure gauges;

[0059] For example, under normal operating conditions, the steam energy supply system supplies 600t / h of industrial steam, requiring a total of 667t / h of secondary circuit main steam. During normal operation, the steam conversion equipment operates at 4x25% capacity (single column output 150t / h), and the heating main steam comes from the secondary circuit. The main steam of each unit enters two columns of steam conversion equipment, each bearing 50% of the steam supply load.

[0060] The evaporator uses the main steam to produce 2.0MPa.a saturated industrial steam, and the superheater uses the main steam to superheat the saturated steam to 1.898MPa.a, 252℃.

[0061] The control method at startup is:

[0062] When the steam energy supply system is started, the four trains of steam conversion equipment are started simultaneously or one by one;

[0063] First, fill the evaporator with water and monitor the evaporator liquid level. When the liquid level reaches the normal level, the tube side isolation valve is opened to start to pass the main steam into the superheater. The evaporator liquid level is the average value of the measurements of the three liquid evaporator level gauges.

[0064] The main steam enters the evaporator after passing through the superheater and the main steam isolation valve. The feedwater acoustic wave on the shell side of the evaporator reaches saturation and gradually begins to generate steam;

[0065] As the main steam continues to flow into the evaporator, the steam production on the shell side of the evaporator increases, and the steam production pressure gradually builds up;

[0066] When the pressure of the industrial steam main pipe at the outlet reaches a preset value, the preset value of the industrial steam main pipe pressure is 1.8 MPa.a; the industrial steam main pipe pressure is the average value of the pressure gauges of the three industrial steam main pipes at the outlet;

[0067] Open the shell side outlet electric valve, steam enters the heating network to warm up the pipes. After the heating of the heating network is completed, the pressure of the heating network is gradually established. When the industrial steam load reaches 20%, the main steam regulating valve is changed to track the pressure of the industrial steam main pipe at the superheater outlet, and the system realizes automatic control;

[0068] The heating rate of the evaporator and the superheater is not higher than 4°C / min, and the cooling rate is not higher than 4°C / min.

[0069] The control method during normal shutdown is:

[0070] When the steam energy supply system is shut down, the four trains of steam conversion equipment can be shut down simultaneously or one by one;

[0071] During the load reduction process of the steam energy supply system, the valves in the evaporator and superheater systems are maintained in normal operation; when the load is reduced to 20%, the main steam isolation valves at the tube side inlet are closed one by one, and the four steam conversion equipment are shut down in turn;

[0072] The control method of the accident or failure is:

[0073] When any equipment in a train of steam conversion equipment fails and needs to be shut down, the train of steam conversion equipment needs to be isolated; when isolating a train of steam conversion equipment, first adjust the control of the main steam regulating valve on the evaporator inlet to manual, and gradually reduce the valve opening. As a result, the liquid level on the shell side of the evaporator rises, the evaporator feed water regulating valve is gradually reduced, the feed water flow rate is reduced, the output of the steam conversion equipment in the train is reduced, and the other three trains of steam conversion equipment automatically increase the load; when the main steam regulating valve of a shut-down train of equipment is fully closed, close all the inlet and outlet isolation valves of the train of equipment, the electric isolation valve on the shell side outlet of the superheater is closed, and at the same time, the other three trains of equipment share the steam supply load according to their capacity.

[0074] The other three trains of equipment share the steam supply load at a capacity of 3x33%.

[0075] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0076] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control system for regulating the quality of industrial steam supply in a nuclear power plant, characterized in that: include: The main steam pipeline system for heating is connected to four trains of steam conversion equipment respectively, and each train of steam conversion equipment includes a superheater, an evaporator, a preheater, a feed water pump and an industrial water tank connected in sequence; The main steam pipeline system for heating is connected to four main steam pipeline branches, which are respectively connected to the tube-side inlets of four superheaters; The main steam on the hot side of the superheater flows through the tube side, and the saturated industrial steam medium on the cold side flows through the shell side, realizing reverse convection heat exchange between the cold and hot media; the superheated steam output by the superheater is transported to the industrial steam main pipe; the inlet on the tube side of the evaporator is the main steam, and the outlet is supercooled condensed water; The main steam flows through the tube side of the superheater to superheat the saturated industrial steam on the shell side, and then enters the tube side of four evaporators through four manual isolation valves and four main steam regulating valves respectively. The main steam flows through the tube side of the four evaporators and heats the shell side feed water to be converted into supercooled condensed water, and enters the tube side of four preheaters respectively. The main steam regulating valve tracks the steam production pressure of the industrial steam main pipe at the superheater outlet and matches the corresponding main steam flow to ensure the steam flow requirements of the heat users.

2. The control system for regulating the quality of industrial steam supply to a nuclear power plant according to claim 1, characterized in that: Each row of steam conversion equipment provides 25% of the flow rate, and the maximum operating flow rate of a single channel is 33%.

3. The control system for regulating and controlling the quality of industrial steam supply to a nuclear power plant according to claim 1, characterized in that: The evaporator is a horizontal kettle, U-tube, four-pass surface heating evaporator. The main steam on the hot side is condensed and heat exchanged in the first two tube passes, the main steam condensate is reduced in the second two tube passes for heat exchange, and the industrial feed water on the cold side is heated and evaporated outside the tube.

4. The control system for regulating the quality of industrial steam supply to a nuclear power plant according to claim 1, characterized in that: The superheater is a horizontal, U-shaped tube, double-flow surface heating heater.

5. A method for regulating and controlling the quality of industrial steam supply in a nuclear power plant, characterized in that: The regulation and control system for the quality of industrial steam supply to a nuclear power plant according to any one of claims 1 to 4 is implemented, including control in four situations: normal operation, startup, normal shutdown, and operation in the event of an accident or failure; The control method during normal operation is: When the evaporator and preheater are operating normally, the pipe-side isolation valves of the evaporator and superheater are all open, and the main steam regulating valve operates by tracking the industrial steam main pipe pressure at the superheater outlet; The control method at startup is: The four trains of steam conversion equipment are started simultaneously or one by one; First, fill the evaporator with water and monitor the evaporator liquid level. When the liquid level reaches the normal level, open the pipe side isolation valve and start to pass the main steam into the superheater. The main steam enters the evaporator after passing through the superheater and the main steam isolation valve. The feedwater acoustic wave on the shell side of the evaporator reaches saturation and gradually begins to generate steam; As the main steam continues to flow into the evaporator, the steam production on the shell side of the evaporator increases, and the steam production pressure gradually builds up; When the pressure of the industrial steam main pipe at the outlet reaches the preset value, the shell side outlet electric valve is opened, and the steam enters the heating network to warm up the pipes. After the heating of the heating network is completed, the pressure of the heating network is gradually established. When the industrial steam load reaches 20%, the main steam regulating valve is changed to track the pressure of the industrial steam main pipe at the superheater outlet, and the system realizes automatic control; The control method during normal shutdown is: The four trains of steam conversion equipment can be shut down simultaneously or one by one; During the load reduction process of the steam energy supply system, the valves in the evaporator and superheater systems are maintained in normal operation; when the load is reduced to 20%, the main steam isolation valves at the tube side inlet are closed one by one, and the four steam conversion equipment are shut down in turn; The control method of the accident or failure is: When any equipment in a train of steam conversion equipment fails and needs to be shut down, the train of steam conversion equipment needs to be isolated; when isolating a train of steam conversion equipment, first adjust the control of the main steam regulating valve at the evaporator inlet to manual, gradually reduce the valve opening, and the other three trains of steam conversion equipment will automatically increase the load; when the main steam regulating valve of a shut-down train of equipment is fully closed, close all the inlet and outlet isolation valves of the train of equipment, close the electric isolation valve at the shell side outlet of the superheater, and at the same time, the other three trains of equipment share the steam supply load according to their capacity.

6. The method for regulating and controlling the quality of industrial steam supply to a nuclear power plant according to claim 5, characterized in that: The heating rate of the evaporator and the superheater is not higher than 4°C / min, and the cooling rate is not higher than 4°C / min.

7. The method for regulating and controlling the quality of industrial steam supply to a nuclear power plant according to claim 5, characterized in that: The preset value of the industrial steam main pipe pressure is 1.8 MPa.a.

8. The method for regulating and controlling the quality of industrial steam supply to a nuclear power plant according to claim 5, characterized in that: The other three trains of equipment share the steam supply load at a capacity of 3x33%.

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