Cold-state quick starting system of gas-steam combined cycle unit

Abstract

The invention discloses a gas-steam combined cycle unit cold-state quick starting system which comprises a preheating air source, a generator, a gas turbine and a steam turbine, the steam turbine comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder, and the preheating air source is connected with a preheating steam conveying pipeline leading to the high-pressure cylinder and the low-pressure cylinder; a steam inlet of the high-pressure cylinder is connected with a high-pressure main steam pipeline, a first electric isolating valve is arranged on the high-pressure main steam pipeline, and the high-pressure main steam pipeline is connected with a pre-heating steam conveying pipeline through a high-pressure conveying pipeline and a drain expansion pipeline; a steam exhaust port of the high-pressure cylinder communicates with an inlet of the reheater through a low-pressure reheat steam pipeline, and an outlet of the reheater communicates with a steam inlet of the medium-pressure cylinder through a high-temperature reheat steam pipeline. According to the system, the steam pre-warming of the steam cylinder is realized by utilizing the valve and the structure which are arranged in the steam turbine set, meanwhile, the water vapor loss is not caused, a new valve does not need to be arranged, the cost is saved, and the pre-warming efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of cold start of steam turbines, and in particular to a cold quick start system for a gas-steam combined cycle dual-shaft unit. Background Art

[0002] Steam turbine cold state rapid start system (referred to as "rapid start system" or "quick start system") refers to the cold state rapid start preheating heating system, temperature control system, and corresponding control logic optimization. Before the gas turbine is ignited, the steam turbine cold state rapid start system sends auxiliary steam with a higher temperature than the metal wall temperature of the steam turbine through the pipeline, the high-pressure main steam valve regulating valve, the medium-pressure regulating valve rear valve cover, and the high and medium pressure cylinders of the steam turbine to impulse the steam turbine rotor, and heat the metal parts to achieve the slow heating of the dynamic and static metal parts of the steam turbine body to reach the brittle transition temperature, so that the steam turbine cylinder and rotor expand evenly under the action of heat, avoid the gap reduction and the formation of dynamic and static collision and grinding, save the rapid warm-up node during the cold state impulse process, and shorten the cold state start time by about 180 minutes, thereby saving the power consumption of the plant during the startup process and reducing the natural gas fuel loss caused by the low-load and low-efficiency operation of the gas turbine during startup to slowly heat the steam turbine.

[0003] The design concept of the combined cycle unit preheating system is: before the gas engine is ignited, the steam from the adjacent engine or auxiliary steam is used to preheat the steam turbine. After the unit is heated to a certain temperature, the warm-up steam is cut off. Then the gas engine is ignited and started normally according to the warm start mode. Through the preheating technology, the original cold start can be turned into a warm start, which can greatly improve the peak load response speed of the steam turbine and reduce energy loss and power generation costs. In addition, increasing the start speed through the preheating method will not cause additional life loss, which is conducive to extending the service life of the unit.

[0004] Conventional cylinder warming operation uses auxiliary steam connected to the high-pressure main steam pipeline in front of the high-pressure main steam valve and the high-temperature reheat steam pipeline in front of the medium-pressure main steam valve. The preheating steam is provided by the startup boiler or adjacent units, such as Figure 1 shown. Figure 1 An existing conventional cylinder warming operation system is shown, including components such as a generator 2, a gas turbine 3, a preheating gas source 4, a delivery valve 5, a high-pressure cylinder 8, a medium-pressure cylinder 9, a low-pressure cylinder 10 and a condenser 20, as well as pipelines such as a preheating steam delivery pipeline 100, a high-pressure main steam pipeline 200, and a low-pressure reheat steam pipeline 300. With this system, after the auxiliary steam enters the mother pipe, it will mainly move to the side with low resistance. After the pipeline resistance is greater than the resistance of the high-pressure main steam valve 13, the auxiliary steam airflow will mainly flow into the high-pressure cylinder 8. The time from cold start of the unit to full load is generally 6 to 8 hours. At the same time, at the cold end of the pipeline, due to the drop in temperature, the steam condenses into saturated water, consuming a large amount of heat, causing useless consumption and increasing the startup cost. Summary of the invention

[0005] The present invention provides a cold state rapid start system for a gas-steam combined cycle dual-shaft unit, aiming to solve the problems existing in the prior art of causing steam-water loss, long preheating time and high start-up cost.

[0006] The technical solution provided by the present invention is as follows:

[0007] A cold state rapid start system for a gas-steam combined cycle unit comprises a preheating gas source, and a generator, a gas turbine, and a steam turbine which are coaxially arranged and connected in sequence, wherein the steam turbine comprises a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder, and the preheating gas source is connected to a preheating steam delivery pipeline leading to the high-pressure cylinder and the low-pressure cylinder;

[0008] The steam inlet of the high-pressure cylinder is connected to a high-pressure main steam pipeline, on which a first electric isolation valve is provided, and the high-pressure main steam pipeline is connected to the preheating steam delivery pipeline through a high-pressure delivery pipeline and a drain expansion pipeline;

[0009] The exhaust port of the high-pressure cylinder is connected to the inlet of the reheater through a low-pressure reheat steam pipeline, and the outlet of the reheater is connected to the steam inlet of the medium-pressure cylinder through a high-temperature reheat steam pipeline.

[0010] Further, a condenser is included;

[0011] The condenser is connected to the low-pressure cylinder;

[0012] The low-pressure reheat steam pipeline is connected to the condenser through a first medium-pressure bypass pipeline, and a high-pressure exhaust ventilation valve is provided on the first medium-pressure bypass pipeline;

[0013] The high-temperature reheat steam pipeline is connected to the condenser through a second medium-pressure bypass pipeline, and a medium-pressure bypass valve is provided on the second medium-pressure bypass pipeline.

[0014] Further, a high-pressure main steam valve and a high-pressure regulating valve are sequentially arranged on the high-pressure main steam pipeline, the drain expansion pipeline is arranged between the high-pressure main steam valve and the high-pressure regulating valve, the drain expansion pipeline is connected to the drain expansion container, and a third shut-off valve group is arranged on the drain expansion pipeline;

[0015] The two ends of the high-pressure delivery pipeline are respectively connected to the preheating steam delivery pipeline and the drain expansion pipeline, and a first shut-off valve group is arranged on the high-pressure delivery pipeline.

[0016] Furthermore, the high-temperature reheat steam pipeline is sequentially provided with a second electric isolation valve, a medium-pressure main steam valve and a medium-pressure regulating valve.

[0017] Furthermore, a high-pressure discharge check valve is provided on the low-pressure reheat steam pipeline, and the low-pressure reheat steam pipeline is connected to the high-pressure main steam pipeline through a high-pressure bypass pipeline, and the high-pressure bypass pipeline is provided between the high-pressure discharge check valve and the reheater, and a high-pressure bypass valve is provided on the high-pressure bypass pipeline.

[0018] Furthermore, a delivery valve is provided on the preheating steam delivery pipeline, and a second shut-off valve group is provided on the preheating steam delivery pipeline connected to the low-pressure cylinder.

[0019] Furthermore, the material of the preheating steam delivery pipeline is DN150 steel pipe;

[0020] The material of the high-pressure main steam pipeline is DN250 steel pipe;

[0021] The material of the low-pressure reheat steam pipeline is DN500 steel pipe;

[0022] The high-temperature reheat steam pipeline is made of DN550 steel pipe.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The cold-state rapid start-up system for a gas-steam combined cycle unit provided by the present invention realizes steam preheating of the cylinder without causing water vapor loss by utilizing valves and structures already configured in the steam turbine unit, and does not require the configuration of new valves, thereby saving costs and improving preheating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the preheating system adopted in the prior art;

[0026] Figure 2 It is a structural schematic diagram of a cold-state rapid start-up system for a gas-steam combined cycle unit in an embodiment of the present invention.

[0027] The reference numerals are as follows:

[0028] 2-Generator, 3-Gas turbine, 4-Preheating gas source, 5-Transfer valve, 6-First electric isolation valve, 7-High-pressure bypass valve, 8-High-pressure cylinder, 9-Medium-pressure cylinder, 10-Low-pressure cylinder, 11-First shut-off valve group, 12-Second shut-off valve group, 13-High-pressure main steam valve, 14-High-pressure regulating valve, 15-High-exhaust check valve, 16-High-exhaust ventilation valve, 17-Medium-pressure bypass valve, 18-Medium-pressure regulating valve, 19-Medium-pressure main steam valve, 20-condenser, 21-third shut-off valve group, 22-reheater, 23-second electric isolation valve, 100-preheating steam transmission pipeline, 101-high-pressure transmission pipeline, 200-high-pressure main steam pipeline, 201-drain expansion pipeline, 300-low-pressure reheat steam pipeline, 400-high-temperature reheat steam pipeline, 500-high-pressure bypass pipeline, 600-first medium-pressure bypass pipeline, 700-second medium-pressure bypass pipeline. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described below are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the accompanying drawings is intended to represent only selected embodiments of the present application, and is not intended to limit the scope of protection claimed in the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0031] It should be understood that in the description of the embodiments of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0032] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0033] See also Figure 2 The present invention provides a cold rapid start system for a gas-steam combined cycle unit, comprising a preheating gas source 4, and a generator 2, a gas turbine 3, and a steam turbine that are coaxially arranged and connected in sequence, the steam turbine comprising a high-pressure cylinder 8 and a low-pressure cylinder 10, and the preheating gas source 4 is connected to a preheating steam delivery pipeline 100 leading to the high-pressure cylinder 8, the medium-pressure cylinder 9, and the low-pressure cylinder 10.

[0034] The steam inlet of the high-pressure cylinder 8 is connected to a high-pressure main steam pipeline 200, which provides steam through a waste heat boiler. A first electric isolation valve 6 is provided on the high-pressure main steam pipeline 200. The high-pressure main steam pipeline 200 is connected to the preheating steam delivery pipeline 100 through a high-pressure delivery pipeline 101 and a drain expansion pipeline 201.

[0035] The exhaust port of the high-pressure cylinder 8 is connected to the inlet of the reheater 22 through the low-pressure reheat steam pipeline 300, and the outlet of the reheater 22 is connected to the steam inlet of the medium-pressure cylinder 9 through the high-temperature reheat steam pipeline 400.

[0036] Optionally, the cold rapid start system of the gas-steam combined cycle unit provided by the present invention also includes a condenser 20, which is connected to the low-pressure cylinder 10, and the low-pressure reheat steam pipe 300 is connected to the condenser 20 through a first medium-pressure bypass pipe 600, and a high-exhaust ventilation valve 16 is provided on the first medium-pressure bypass pipe 600.

[0037] The high-temperature reheat steam pipeline 400 is connected to the condenser 20 through a second medium-pressure bypass pipeline 700 , and a medium-pressure bypass valve 17 is provided on the second medium-pressure bypass pipeline 700 .

[0038] Optionally, a high-pressure main steam valve 13 and a high-pressure regulating valve 14 are sequentially arranged on the high-pressure main steam pipeline 200, a drain port is arranged between the high-pressure main steam valve 13 and the high-pressure regulating valve 14, a drain expansion pipeline 201 is arranged on the drain port between the high-pressure main steam valve 13 and the high-pressure regulating valve 14, the drain expansion pipeline 201 is connected to the drain expansion container, and a third shut-off valve group 21 is arranged on the drain expansion pipeline 201. Through this design, unnecessary circulation pipelines of steam in the high-pressure main steam pipeline 200 are reduced, and steam loss is avoided.

[0039] The two ends of the high-pressure delivery pipeline 101 are respectively connected to the preheating steam delivery pipeline 100 and the drain expansion pipeline 201 , and a first shut-off valve group 11 is provided on the high-pressure delivery pipeline 101 .

[0040] It should be noted that the present invention innovatively proposes an access point for high-pressure preheating steam in the preheating system, and connects the preheating steam delivery pipeline 100 to the drain expansion pipeline 201 directly between the high-pressure main steam valve 13 and the high-pressure main regulating valve 14, without changing the existing design and configuration of the main engine plant.

[0041] Optionally, a second electric isolation valve 23, a medium-pressure main steam valve 19 and a medium-pressure regulating valve 18 are sequentially arranged on the high-temperature reheat steam pipeline 400.

[0042] Optionally, a high-discharge check valve 15 is provided on the low-pressure reheat steam pipe 300, and the low-pressure reheat steam pipe 300 is connected to the high-pressure main steam pipe 200 through a high-pressure bypass pipe 500. The high-pressure bypass pipe 500 is provided between the high-discharge check valve 15 and the reheater 22, and a high-pressure bypass valve 7 is provided on the high-pressure bypass pipe 500.

[0043] Optionally, a delivery valve 5 is provided on the preheating steam delivery pipeline 100 , and a second shut-off valve group 12 is provided on the preheating steam delivery pipeline 100 connected to the low-pressure cylinder 10 .

[0044] Optionally, the preheating steam delivery pipeline 100 is made of DN150 steel pipe.

[0045] The material of the high-pressure main steam pipeline 200 is DN250 steel pipe.

[0046] The material of the low-pressure reheat steam pipe 300 is DN500 steel pipe.

[0047] The material of the high-temperature reheat steam pipe 400 is DN550 steel pipe.

[0048] as follows Figure 2 As shown, for high-pressure preheating, the cold-state rapid start-up system of the gas-steam combined cycle unit provided by the present invention connects the high-pressure preheating steam to the drain port behind the high-pressure main steam valve 13, and uses the drain port to pass the preheating steam into the high-pressure cylinder 8 for cylinder preheating, and during the preheating period, the high-pressure main steam valve 13 is closed to prevent the steam from flowing back to the waste heat boiler, and the preheating steam all enters the high-pressure cylinder 8 for preheating. For medium-pressure preheating, since the medium-pressure cylinder 9 is provided with symmetrical flange ports on both sides, one side is connected to the medium-pressure cylinder 9 by high-temperature reheated steam after passing through the medium-pressure main steam valve 19 and the medium-pressure regulating valve 18, and the other side is closed by the flange cover for standby use. Therefore, the position of the flange cover can be used to open a hole on it to connect the medium-pressure preheating pipeline, and the preheating steam is introduced into the medium-pressure cylinder 9. At this time, the medium-pressure main steam valve 19 and the medium-pressure regulating valve 18 are completely closed, and the preheating steam cannot flow back to the waste heat boiler side. All the preheating steam enters the cylinder for preheating, and the preheating efficiency is greatly improved.

[0049] The present invention utilizes valves and structures already configured in the steam turbine unit to achieve steam preheating of the cylinder without causing water vapor loss, and does not require the configuration of new valves, thereby saving costs and improving preheating efficiency.

[0050] The above is only the best specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application shall be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A cold state rapid start system for a gas-steam combined cycle unit, characterized in that: It includes a preheating air source, and a generator, a gas turbine, and a steam turbine which are coaxially arranged and connected in sequence, wherein the steam turbine includes a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder, and the preheating air source is connected with a preheating steam delivery pipeline leading to the high-pressure cylinder and the low-pressure cylinder; The steam inlet of the high-pressure cylinder is connected to a high-pressure main steam pipeline, on which a first electric isolation valve is provided, and the high-pressure main steam pipeline is connected to the preheating steam delivery pipeline through a high-pressure delivery pipeline and a drain expansion pipeline; The exhaust port of the high-pressure cylinder is connected to the inlet of the reheater through a low-pressure reheat steam pipeline, and the outlet of the reheater is connected to the steam inlet of the medium-pressure cylinder through a high-temperature reheat steam pipeline.

2. The cold state rapid start system of the gas-steam combined cycle unit according to claim 1, characterized in that: It also includes a condenser; The condenser is connected to the low-pressure cylinder; The low-pressure reheat steam pipeline is connected to the condenser through a first medium-pressure bypass pipeline, and a high-pressure exhaust ventilation valve is provided on the first medium-pressure bypass pipeline; The high-temperature reheat steam pipeline is connected to the condenser through a second medium-pressure bypass pipeline, and a medium-pressure bypass valve is provided on the second medium-pressure bypass pipeline.

3. The cold state rapid start system of the gas-steam combined cycle unit according to claim 1, characterized in that: The high-pressure main steam pipeline is provided with a high-pressure main steam valve and a high-pressure regulating valve in sequence, the drain expansion pipeline is provided between the high-pressure main steam valve and the high-pressure regulating valve, the drain expansion pipeline is connected to the drain expansion container, and the drain expansion pipeline is provided with a third shut-off valve group; The two ends of the high-pressure delivery pipeline are respectively connected to the preheating steam delivery pipeline and the drain expansion pipeline, and a first shut-off valve group is arranged on the high-pressure delivery pipeline.

4. The cold state rapid start system of the gas-steam combined cycle unit according to claim 3 is characterized in that: The high-temperature reheat steam pipeline is provided with a second electric isolation valve, a medium-pressure main steam valve and a medium-pressure regulating valve in sequence.

5. The cold state rapid start system of a gas-steam combined cycle unit according to any one of claims 1 to 4, characterized in that: A high-pressure discharge check valve is arranged on the low-pressure reheat steam pipeline, and the low-pressure reheat steam pipeline is connected to the high-pressure main steam pipeline through a high-pressure bypass pipeline, and the high-pressure bypass pipeline is arranged between the high-pressure discharge check valve and the reheater, and a high-pressure bypass valve is arranged on the high-pressure bypass pipeline.

6. The cold state rapid start system of the gas-steam combined cycle unit according to claim 5, characterized in that: A delivery valve is provided on the preheating steam delivery pipeline, and a second shut-off valve group is provided on the preheating steam delivery pipeline connected to the low-pressure cylinder.

7. The cold state rapid start system of the gas-steam combined cycle unit according to claim 5, characterized in that: The material of the preheating steam delivery pipeline is DN150 steel pipe; The material of the high-pressure main steam pipeline is DN250 steel pipe; The material of the low-pressure reheat steam pipeline is DN500 steel pipe; The high-temperature reheat steam pipeline is made of DN550 steel pipe.

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