A protection system and a parameter-adjusting method applicable to the regulation of heat supply parameters by a regulating valve in a thermal power plant

Abstract

The present invention discloses a protection system and a parameter adjustment method for a heat supply parameter improvement by a middle control valve in a thermal power plant. The main steam pipeline is connected to the inlet of a high-pressure cylinder through a high-pressure main steam valve group and a high-pressure regulating valve group. The exhaust port of the high-pressure cylinder is connected to a high-pressure cylinder exhaust pipeline, and the first extraction port of the high-pressure cylinder is connected to a first extraction pipeline. The outlet of the reheater steam pipeline is divided into three paths. The first path is connected to the right inlet of the intermediate-pressure cylinder through a right reheater pipeline, the second path is connected to the left inlet of the intermediate-pressure cylinder through a left reheater pipeline, and the third path is connected to an external heat supply user through a desuperheating and pressure-reducing device. A left intermediate-pressure main steam valve and a left intermediate-pressure regulating valve are arranged on the left reheater pipeline. A right intermediate-pressure main steam valve and a right intermediate-pressure regulating valve are arranged on the right reheater pipeline. The system and the method can ensure the safe and stable operation of a heat supply unit with the middle control valve participating in the regulation.

Description

Technical Field

[0001] The invention belongs to the field of heat supply in the power generation industry, and relates to a protection system and a parameter adjustment method applicable to the adjustment of a medium-pressure regulating valve in a thermal power plant to improve heat supply parameters. Background Art

[0002] In recent years, with the soaring coal prices in recent years, the power generation cost of the thermal power industry has been increasing continuously, and the power generation business has become increasingly difficult, facing an extremely severe operating situation. By means of heat supply transformation, thermal power plants supplying heat to surrounding cities or supplying industrial extraction steam to enterprises have become an important means to increase revenue.

[0003] Generally, the pressure requirement for industrial extraction steam is relatively high. Steam is supplied from the hot reheat pipeline, cold reheat pipeline or the first-stage extraction of the unit. The parameters of these extraction ports are often low under low load, making it difficult to meet the demand for industrial extraction steam. In order to meet the requirements of industrial extraction steam parameters under low load, the medium-pressure regulating valve often needs to participate in the regulation to increase the external steam supply flow and pressure. However, the medium-pressure regulating valve was only designed to control the steam flow into the intermediate-pressure cylinder through the change of its opening during the unit startup stage, and was not considered for use during the normal operation of the unit and external steam supply. The operation mode of the medium-pressure regulating valve participating in the regulation and external heat supply is different from that of a pure condensing unit, which affects the safe operation of the unit. The heat supply method with the medium-pressure regulating valve participating in the regulation may cause an increase in the enthalpy drop of the last-stage blade of the high-pressure cylinder, vibration of the medium-pressure regulating valve and the risk of sudden closing of the medium-pressure regulating valve. At present, the protection system and method for the medium-pressure regulating valve participating in the regulation to improve heat supply are lacking, which affects the safe and stable operation of the heat supply unit. Summary of the Invention

[0004] The purpose of the invention is to overcome the above-mentioned disadvantages of the prior art, and provide a protection system and a parameter adjustment method applicable to the adjustment of a medium-pressure regulating valve in a thermal power plant to improve heat supply parameters, which can ensure the safe and stable operation of the heat supply unit with the medium-pressure regulating valve participating in the regulation.

[0005] To achieve the above purpose, the protection system applicable to the adjustment of a medium-pressure regulating valve in a thermal power plant to improve heat supply parameters of the invention includes a main steam pipeline, a reheater steam pipeline, a high-pressure cylinder, an intermediate-pressure cylinder, a high-pressure main steam valve group, a high-pressure regulating valve group, a left intermediate-pressure main steam valve, a left intermediate-pressure regulating valve, a right intermediate-pressure main steam valve, a right intermediate-pressure regulating valve, a left reheater pipeline, a right reheater pipeline, a high-pressure cylinder exhaust pipeline, a first-stage extraction pipeline and a desuperheating and pressure-reducing device;

[0006] The main steam pipeline is connected to the inlet of the high-pressure cylinder through the high-pressure main steam valve group and the high-pressure regulating valve group. The exhaust port of the high-pressure cylinder is connected to the high-pressure cylinder exhaust pipeline, and the first-stage extraction port of the high-pressure cylinder is connected to the first-stage extraction pipeline;

[0007] The outlet of the reheater steam pipeline is divided into three paths. The first path is connected to the right inlet of the intermediate pressure cylinder through the right reheater pipeline. The second path is connected to the left inlet of the intermediate pressure cylinder through the left reheater pipeline. The third path is connected to the external heating users through the desuperheating and pressure reducing device.

[0008] The left reheater pipeline is provided with a left intermediate pressure main steam valve and a left intermediate pressure regulating valve. The right reheater pipeline is provided with a right intermediate pressure main steam valve and a right intermediate pressure regulating valve.

[0009] It also includes a differential pressure monitoring meter, which is connected to the high-pressure cylinder exhaust steam pipeline and the first-stage extraction steam pipeline.

[0010] It also includes a differential pressure monitoring meter for the left intermediate pressure combined steam valve, which is connected to the inlet and outlet of the left reheater pipeline.

[0011] It also includes a differential pressure monitoring meter for the right intermediate pressure combined steam valve, which is connected to the inlet and outlet of the right reheater pipeline.

[0012] The number of differential pressure monitoring meters is three.

[0013] The measuring ranges of the three differential pressure monitoring meters are all set to 5 MPa.

[0014] The measuring ranges of the differential pressure monitoring meter for the left intermediate pressure combined steam valve and the differential pressure monitoring meter for the right intermediate pressure combined steam valve are both 2 MPa.

[0015] The parameter adjustment method of the protection system applicable to the intermediate pressure regulating valve participating in regulating and improving the heating parameters in a thermal power plant according to the present invention includes the following steps:

[0016] When the measured values of two differential pressure monitoring meters exceed the higher value, an alarm is given, and the opening of the desuperheating and pressure reducing device is prohibited from continuing to increase.

[0017] When the measured values of two differential pressure monitoring meters exceed the second higher value, the high-pressure regulating valve group, the left intermediate pressure regulating valve, and the right intermediate pressure regulating valve are simultaneously closed, and the unit trips and shuts down.

[0018] The parameter adjustment methods of the left intermediate pressure regulating valve and the right intermediate pressure regulating valve are the same. The parameter adjustment method of the left intermediate pressure regulating valve is as follows:

[0019] When the differential pressure detected by the differential pressure monitoring meter for the left intermediate pressure combined steam valve is greater than the preset higher value, the left intermediate pressure regulating valve is prohibited from continuing to close.

[0020] When the exhaust steam temperature of the high-pressure cylinder approaches the alarm value, the left intermediate pressure regulating valve is prohibited from continuing to close.

[0021] When the thrust bearing temperature of the unit reaches the alarm value, the left intermediate pressure regulating valve is prohibited from continuing to close.

[0022] After both the left medium-pressure regulating valve and the right medium-pressure regulating valve are closed, the high-pressure regulating valve group is closed simultaneously, and a turbine trip signal is triggered.

[0023] The medium-pressure regulating valve adopts two parameter adjustment methods: single valve or sequence valve.

[0024] When the medium-pressure regulating valve adopts the sequence valve parameter adjustment method, the method is as follows:

[0025] Conduct valve flow characteristic tests on the left and right medium-pressure regulating valves respectively to determine the relationship between the opening and flow characteristics of the medium-pressure regulating valve;

[0026] Determine the medium-pressure regulating valve that is closed first, set the overlap according to the flow characteristic curve of the medium-pressure regulating valve, and set the minimum opening for the medium-pressure regulating valve that is closed later;

[0027] For the medium-pressure regulating valve that is closed first, when its opening is > 40%, the parameter adjustment step does not exceed 10%; when the opening is < 40%, the parameter adjustment step does not exceed 3%;

[0028] For the medium-pressure regulating valve that is closed later, its parameter adjustment step does not exceed 3%.

[0029] When the medium-pressure regulating valve adopts the single valve parameter adjustment method, the method is as follows:

[0030] The left and right medium-pressure regulating valves are adjusted simultaneously;

[0031] When the opening of the medium-pressure regulating valves on both sides is > 50%, the parameter adjustment step does not exceed 3%;

[0032] When 35% < the opening of the medium-pressure regulating valve ≤ 50%, the parameter adjustment step does not exceed 2%;

[0033] When the minimum opening < the opening of the medium-pressure regulating valve ≤ 35%, the parameter adjustment step does not exceed 1%;

[0034] Set the minimum opening for the medium-pressure regulating valves on both sides.

[0035] The present invention has the following beneficial effects:

[0036] When the protection system and parameter adjustment method for the medium-pressure regulating valve to participate in regulating and improving the heating parameters in a thermal power plant described in the present invention are specifically operated, by setting the left medium-pressure regulating valve and the right medium-pressure regulating valve, and by adding the monitoring system and necessary logic protection necessary for the parameter adjustment of the left medium-pressure regulating valve and the right medium-pressure regulating valve, it is ensured that the unit operates safely and stably in the mode of the medium-pressure regulating valve participating in regulating heating. Brief Description of the Drawings

[0037] Figure 1 It is a schematic diagram of the present invention.

[0038] Among them, 1 is the high-pressure cylinder, 2 is the intermediate-pressure cylinder, 3 is the high-pressure main steam valve group, 4 is the high-pressure regulating valve group, 5 is the left intermediate-pressure main steam valve, 6 is the left intermediate-pressure regulating valve, 7 is the right intermediate-pressure main steam valve, 8 is the right intermediate-pressure regulating valve, 9 is the differential pressure monitoring meter, 10 is the differential pressure monitoring meter for the left intermediate-pressure combined steam valve, 11 is the differential pressure monitoring meter for the right intermediate-pressure combined steam valve, 12 is the left reheat pipeline, 13 is the right reheat pipeline, 14 is the high-pressure cylinder exhaust pipeline, 15 is the first-stage extraction steam pipeline, and 16 is the desuperheating and pressure-reducing device. Specific implementation manners

[0039] In order to enable those skilled in the art of the present technology to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present invention disclosure. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0040] The structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0041] Refer to Figure 1 , the protection system applicable to the intermediate regulating valve in a thermal power plant to participate in regulating and improving the heating parameters according to the present invention includes a high-pressure cylinder 1, an intermediate-pressure cylinder 2, a high-pressure main steam valve group 3, a high-pressure regulating valve group 4, a left intermediate-pressure main steam valve 5, a left intermediate-pressure regulating valve 6, a right intermediate-pressure main steam valve 7, a right intermediate-pressure regulating valve 8, a differential pressure monitoring meter 9, a differential pressure monitoring meter for the left intermediate-pressure combined steam valve 10, a differential pressure monitoring meter for the right intermediate-pressure combined steam valve 11, a left reheat pipeline 12, a right reheat pipeline 13, a high-pressure cylinder exhaust pipeline 14, a first-stage extraction steam pipeline 15, and a desuperheating and pressure-reducing device 16;

[0042] The main steam pipeline is connected to the inlet of the high-pressure cylinder 1 through the high-pressure main steam valve group 3 and the high-pressure regulating valve group 4. The exhaust port of the high-pressure cylinder 1 is connected to the high-pressure cylinder exhaust pipeline 14, and the first-stage extraction steam port of the high-pressure cylinder 1 is connected to the first-stage extraction steam pipeline 15;

[0043] The outlet of the reheater steam pipeline is divided into three paths. The first path is connected to the right inlet of the intermediate-pressure cylinder 2 through the right reheater pipeline 13. The second path is connected to the left inlet of the intermediate-pressure cylinder 2 through the left reheater pipeline 12. The third path is connected to the external heat supply users through the desuperheating and pressure-reducing device 16.

[0044] The left intermediate-pressure main steam valve 5 and the left intermediate-pressure regulating valve 6 are arranged on the left reheater pipeline 12. The right intermediate-pressure main steam valve 7 and the right intermediate-pressure regulating valve 8 are arranged on the right reheater pipeline 13.

[0045] The differential pressure monitoring table 9 is connected to the high-pressure cylinder exhaust steam pipeline 14 and the first-stage extraction steam pipeline 15. The left intermediate-pressure combined steam valve differential pressure monitoring table 10 is connected to the inlet and outlet of the left reheater pipeline 12.

[0046] The right intermediate-pressure combined steam valve differential pressure monitoring table 11 is connected to the inlet and outlet of the right reheater pipeline 13.

[0047] The number of the differential pressure monitoring tables 9 is three. Among them, the three differential pressure monitoring tables 9 work independently, and the measuring ranges of the differential pressure monitoring tables 9 are all set to 5 MPa.

[0048] The measuring ranges of the left intermediate-pressure combined steam valve differential pressure monitoring table 10 and the right intermediate-pressure combined steam valve differential pressure monitoring table 11 are both 2 MPa.

[0049] The left intermediate-pressure regulating valve 6 and the right intermediate-pressure regulating valve 8 participate in the regulation of heat supply in a single-valve mode. The regulation targets of the left intermediate-pressure regulating valve 6 and the right intermediate-pressure regulating valve 8 are the hot reheat pressure, ensuring that the hot reheat pressure reaches 2.5 MPa for industrial steam supply. The regulation methods of the left intermediate-pressure regulating valve 6 and the right intermediate-pressure regulating valve 8 are the same. Taking the left intermediate-pressure regulating valve 6 as an example, the specific process is as follows:

[0050] 1) When the opening of the left intermediate-pressure regulating valve 6 > 50%, the regulation step is not more than 3%.

[0051] 2) When 35% < the opening of the left intermediate-pressure regulating valve 6 ≤ 50%, the regulation step is not more than 2%.

[0052] 3) When the minimum opening < the opening of the left intermediate-pressure regulating valve 6 ≤ 35%, the regulation step is not more than 1%.

[0053] The left intermediate-pressure regulating valve 6 and the right intermediate-pressure regulating valve 8 are set with the following logic. Taking the left intermediate-pressure regulating valve 6 as an example:

[0054] When the differential pressure detected by the left intermediate-pressure combined steam valve differential pressure monitoring table 10 is greater than 1 MPa, the left intermediate-pressure regulating valve 6 is prohibited from closing further.

[0055] When the exhaust steam temperature of the high-pressure cylinder 1 approaches the alarm value of 370 °C, the left intermediate-pressure regulating valve 6 is prohibited from closing further.

[0056] When the thrust bearing temperature of the unit reaches 80 °C, it is prohibited to continue closing the left medium-pressure regulating valve 6;

[0057] After both the left medium-pressure regulating valve 6 and the right medium-pressure regulating valve 8 are closed, the high-pressure regulating valve group 4 is simultaneously closed, and a unit regulation signal is triggered.

[0058] The maximum steam flow rate provided externally by the desuperheating and pressure-reducing device 16 is determined by the pressure difference between the newly added three extraction pressures and the high-pressure exhaust pressure, and the following protection logic is set:

[0059] For the three differential pressure monitoring gauges 9, the two-out-of-three principle is adopted;

[0060] When the measured values of two differential pressure monitoring gauges 9 exceed 3.9 MPa, an alarm is given, and it is prohibited to further increase the opening of the desuperheating and pressure-reducing device 16;

[0061] When the measured values of two differential pressure monitoring gauges 9 exceed 4.1 MPa, the high-pressure regulating valve group 4, the left medium-pressure regulating valve 6, and the right medium-pressure regulating valve 8 are simultaneously closed, and the unit trips.

Claims

1. A parameter adjustment method for a protection system in a thermal power plant where a regulating valve participates in regulating and improving heating parameters, characterized in that, The protection system applicable to the regulation of the extraction steam parameters by the intermediate control valves in a thermal power plant includes a main steam pipeline, a reheater steam pipeline, a high-pressure cylinder (1), an intermediate-pressure cylinder (2), a high-pressure main steam valve group (3), a high-pressure regulating valve group (4), a left intermediate-pressure main steam valve (5), a left intermediate-pressure regulating valve (6), a right intermediate-pressure main steam valve (7), a right intermediate-pressure regulating valve (8), a left reheater pipeline (12), a right reheater pipeline (13), a high-pressure cylinder exhaust steam pipeline (14), a first-stage extraction steam pipeline (15), and a desuperheating and pressure-reducing device (16); The main steam pipeline is connected to the inlet of the high-pressure cylinder (1) through the high-pressure main steam valve group (3) and the high-pressure regulating valve group (4). The exhaust port of the high-pressure cylinder (1) is connected to the high-pressure cylinder exhaust steam pipeline (14), and the first-stage extraction steam port of the high-pressure cylinder (1) is connected to the first-stage extraction steam pipeline (15); The outlet of the reheater steam pipeline is divided into three paths. The first path is connected to the right inlet of the intermediate-pressure cylinder (2) through the right reheater pipeline (13), the second path is connected to the left inlet of the intermediate-pressure cylinder (2) through the left reheater pipeline (12), and the third path is connected to the external heating users through the desuperheating and pressure-reducing device (16); The left reheater pipeline (12) is provided with a left intermediate-pressure main steam valve (5) and a left intermediate-pressure regulating valve (6); the right reheater pipeline (13) is provided with a right intermediate-pressure main steam valve (7) and a right intermediate-pressure regulating valve (8); It also includes three differential pressure monitoring meters (9); the differential pressure monitoring meters (9) are connected to the high-pressure cylinder exhaust steam pipeline (14) and the first-stage extraction steam pipeline (15); It also includes a left intermediate-pressure combined steam valve differential pressure monitoring meter (10), and the left intermediate-pressure combined steam valve differential pressure monitoring meter (10) is connected to the inlet and outlet of the left reheater pipeline (12); It also includes a right intermediate-pressure combined steam valve differential pressure monitoring meter (11), and the right intermediate-pressure combined steam valve differential pressure monitoring meter (11) is connected to the inlet and outlet of the right reheater pipeline (13); It includes the following steps: When the measured values of two differential pressure monitoring meters (9) exceed a high value, an alarm is given, and the opening of the desuperheating and pressure-reducing device (16) is prohibited from continuing to increase; When the measured values of two differential pressure monitoring meters (9) exceed a second high value, the high-pressure regulating valve group (4), the left intermediate-pressure regulating valve (6), and the right intermediate-pressure regulating valve (8) are simultaneously closed, and the unit trips and shuts down; The left intermediate-pressure regulating valve (6) and the right intermediate-pressure regulating valve (8) are set with the following reference adjustment protection logic: When the differential pressure detected by the left intermediate-pressure combined steam valve differential pressure monitoring meter (10) is greater than a high value, the left intermediate-pressure regulating valve (6) and the right intermediate-pressure regulating valve (8) are prohibited from continuing to close; When the exhaust steam temperature of the high-pressure cylinder (1) approaches the alarm value, the left intermediate-pressure regulating valve (6) and the right intermediate-pressure regulating valve (8) are prohibited from continuing to close; When the thrust bearing temperature of the unit reaches the alarm value, the left intermediate-pressure regulating valve (6) and the right intermediate-pressure regulating valve (8) are prohibited from continuing to close; After the left intermediate-pressure regulating valve (6) and the right intermediate-pressure regulating valve (8) are both closed, the high-pressure regulating valve group (4) is simultaneously closed, and a unit adjustment signal is triggered.

2. The parameter adjustment method of the protection system for adjusting and participating in adjusting and improving the heating parameters of the regulating valve in a thermal power plant according to claim 1, characterized in that, The intermediate control valves adopt two reference adjustment methods: single valve or sequence valve.

3. The parameter adjustment method of the protection system for adjusting and participating in adjusting and improving the heating parameters of the regulating valve in a thermal power plant according to claim 1, characterized in that, The method when the intermediate control valve adopts the sequential valve parameter adjustment mode is as follows: Conduct valve flow characteristic tests on the left intermediate control valve (6) and the right intermediate control valve (8) respectively to determine the relationship between the opening degree and the flow characteristic of the intermediate control valve; Determine the intermediate control valve to be closed first, set the overlap according to the flow characteristic curve of the intermediate control valve, and set the minimum opening degree for the intermediate control valve to be closed later; For the intermediate control valve to be closed first, when its opening degree is > 40%, the parameter adjustment step is not more than 10%; When the opening degree is < 40%, the parameter adjustment step is not more than 3%; For the intermediate control valve to be closed later, its parameter adjustment step is not more than 3%.

4. The parameter adjustment method of the protection system for adjusting and participating in adjusting and improving the heating parameters by the regulating valve in a thermal power plant according to claim 1, characterized in that, The method when the intermediate control valve adopts the single valve parameter adjustment mode is as follows: Adjust the left intermediate control valve (6) and the right intermediate control valve (8) simultaneously; When the opening degrees of the intermediate control valves on both sides are > 50%, the parameter adjustment step is not more than 3%; When 35% < the opening degree of the intermediate control valve ≤ 50%, the parameter adjustment step is not more than 2%; When the minimum opening degree < the opening degree of the intermediate control valve ≤ 35%, the parameter adjustment step is not more than 1%; Set the minimum opening degrees for the intermediate control valves on both sides.

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