A starting system and method for a wet cooling unit without a starting boiler in a cold region

Abstract

The application discloses a wet cooling unit starting system and method without starting boiler in severe cold regions, wherein the outlet of a main steam pipeline is divided into three paths, wherein the first path is connected with a shaft seal system of a steam turbine, the second path is connected with a cold re-steam pipeline, and the third path is connected with the steam turbine; the outlet of a low bypass pipeline is divided into two paths, wherein one path is connected with a condenser through a low bypass valve, and the other path is connected with an inlet of a steam distributor through a low bypass steam to front pool heating pipeline; the outlet of the steam distributor is connected with the bottom of the front pool; the outlet of a drain tank is connected with the steam distributor; a water intake on one side of the front pool is connected with the other side of the front pool; and a heating pipeline stop valve is arranged on the low bypass steam to front pool heating pipeline. The system and method can eliminate the problem that the unit cannot start due to ice formation in the front pool, and can realize the starting of the unit without relying on a starting boiler to provide auxiliary steam.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of unit starting system and method, specifically relates to a kind of wet cold unit starting system and method of no starting boiler in severe cold region. BACKGROUND

[0002] Starting boiler provides auxiliary steam source for the start of thermal power generating unit, is used to provide shaft seal steam supply and medium preheating, when steam turbine starts, input shaft seal can quickly establish vacuum, make the steam after boiler ignition pass through high, low bypass into condenser, improve steam parameter and improve steam quality.Wet cooling circulating water system removes steam heat through condenser, so that unit maintains vacuum.Currently most of the power plant operating state is one phase double machine, i.e.two units run simultaneously.When one unit is shut down for maintenance and then starts, auxiliary steam source can be used to start normally, two units are alternately shut down for maintenance.This makes the originally designed starting boiler be shut down for a long time even be demolished.Once two units are simultaneously faulted and shut down, starting boiler must be started by auxiliary steam source.Starting boiler is shut down for a long time, is out of repair, failure rate is increased, cannot quickly provide start steam, so that the start time of thermal power generating unit is significantly extended.In addition, the temperature of wet cooling circulating water in severe cold region rapidly decreases after unit is shut down, serious icing phenomenon occurs in circulating water forebay, circulating water pump current fluctuation appears pump body cavitation even completely cannot run, so that unit cannot be started, direct current circulating unit is widely used in the vast northern region of China, so it is necessary to develop a kind of starting system and method suitable for wet cold unit without auxiliary steam source in severe cold region. SUMMARY

[0003] The present application aims at overcoming the above-mentioned shortcomings of the prior art, and provides a wet cold unit starting system and method without starting boiler in severe cold region, which can eliminate the problem of unit failure to start caused by forebay icing, and realize the start of unit without relying on auxiliary steam provided by starting boiler.

[0004] To achieve the above-mentioned purpose, the wet cold unit starting system without starting boiler in severe cold region according to the present application comprises a main steam pipeline, a steam turbine, a cold re-steam pipeline, a low bypass pipeline, a low bypass valve, a condenser, a low bypass steam to forebay heating pipeline, a steam distributor and a forebay.

[0005] The outlet of the main steam pipeline is divided into three routes, wherein the first route is connected with the shaft seal system of the steam turbine, the second route is connected with the cold re-steam pipeline, and the third route is connected with the steam turbine.

[0006] The outlet of the low bypass pipeline is divided into two routes, one of which is connected with the condenser through a low bypass valve, and the other is connected with the inlet of a steam distributor through a low bypass steam to front pool heating pipeline, the outlet of the steam distributor is connected with the bottom of the front pool, the outlet of the drain tank is connected with the steam distributor, the water outlet on one side of the front pool is connected with the other side of the front pool, and the heating pipeline stop valve is arranged on the low bypass steam to front pool heating pipeline.

[0007] The outlet of the drain tank is connected with the steam distributor through a check valve.

[0008] The middle part of the front pool is provided with a temperature sensor.

[0009] The heating pipeline check door is further arranged on the low bypass steam to front pool heating pipeline.

[0010] The front pool is located at the bottom of the cooling tower.

[0011] The water outlet on one side of the front pool is connected with the other side of the front pool through a heating circulating pump.

[0012] The outlet of the main steam pipeline is divided into three routes, one of which is connected with the shaft seal system of the steam turbine through a main steam shaft seal valve, the second route is connected with the cold re-steam pipeline through a high bypass valve, and the third route is connected with the steam turbine.

[0013] The starting method of the wet cooling unit without starting boiler in severe cold area comprises the following steps:

[0014] When the unit is restarted in a shutdown state, the boiler is filled with water and flushed by an electric pump, and after the boiler is ignited, the drain of the main steam pipeline and the reheated steam pipeline is sent into the drain tank for pipeline preheating, and the drain output by the drain tank is discharged into the steam distributor; when the main steam pipeline and the reheated steam pipeline are pressurized, the heating pipeline stop valve is opened, and the steam output by the low bypass pipeline is uniformly introduced into the front pool through the steam distributor to heat the circulating water and start to eliminate the ice in the front pool;

[0015] When the main steam parameters, the reheated steam parameters and the steam quality are qualified, the main steam shaft seal valve is opened, the shaft seal system of the steam turbine is put into operation, and the vacuum pump is started to establish the system vacuum, when the vacuum reaches the required value, the main steam drain and the reheated steam drain are sent into the condenser, at this time, all the steam enters the condenser, the condenser stops water replenishment, the system is switched to the conventional starting mode, and the steam turbine starts to rotate and increase the speed.

[0016] The present application has the following beneficial effects:

[0017] The wet cooling unit starting system and method without starting boiler in severe cold area provided by the application, in the specific operation, uses the steam after the boiler is ignited to preheat the circulating water in the front pool, eliminates the ice in the front pool, makes the circulating water system normally operate, prevents the circulating water from freezing, realizes that the unit can be safely and quickly started in the cold state and the hot state, reduces the energy consumption and is higher in safety. In addition, after the main steam parameter is qualified, the reheat steam parameter is qualified and the steam quality is qualified, the main steam is put into the shaft seal system of the steam turbine, so that the starting of the shaft seal system is realized. It needs to be explained that the application can quickly eliminate the freezing of the circulating water front pool in the severe cold area, establish the main circulating water system as soon as possible, the unqualified steam in the initial starting period does not enter the condenser and is discharged to the front pool, the time for the steam quality to reach the qualified state is shortened. Since the front pool is connected with the external atmosphere, the water quality requirement is not high, and the required water quality can be achieved by regularly supplementing and discharging water. After the shaft seal system is put into operation when the steam quality is qualified, the shaft seal can be put into operation before the vacuum is extracted, regardless of the cold state or the hot state of the steam turbine, the effect of eliminating freezing, shortening the starting time and being safe and reliable is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a system schematic diagram of the application.

[0019] Among them, 1 is a main steam pipeline, 2 is a main steam supply shaft seal valve, 3 is a high bypass valve, 4 is a low bypass pipeline, 5 is a low bypass valve, 6 is a low bypass steam to front pool heating pipeline, 7 is a heating pipeline stop valve, 8 is a heating pipeline check valve, 9 is a steam distributor, 10 is a heating circulating pump, 11 is a temperature sensor, 12 is a front pool, 13 is a steam turbine, 14 is a condenser, 15 is a drain tank, and 16 is a cooling tower. DETAILED DESCRIPTION

[0020] In order for those skilled in the art to better understand the application, the technical solutions in the embodiments of the application will be described clearly and completely below in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments, and are not intended to limit the scope of the application disclosed. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the application.

[0021] The structural schematic diagram according to the disclosed embodiment of the present application is shown in the accompanying drawings. The drawings are not drawn to scale, in which some details are exaggerated for the purpose of clarity and some details can be omitted. The shapes of various regions, layers and the relative size and position relationship therebetween shown in the drawings are only exemplary, and in practice, they can be deviated due to manufacturing tolerance or technical limitation, and the regions / layers with different shapes, sizes and relative positions can be additionally designed according to actual needs by those skilled in the art.

[0022] Reference Figure 1 The wet cooling unit starting system without starting boiler in cold region according to the present application comprises a main steam pipeline 1, a main steam supply shaft seal valve 2, a high bypass valve 3, a low bypass pipeline 4, a low bypass valve 5, a low bypass steam to front pool heating pipeline 6, a heating pipeline stop valve 7, a heating pipeline check valve 8, a steam distributor 9, a heating circulating pump 10, a temperature sensor 11, a front pool 12, a steam turbine 13, a condenser 14, a drain tank 15 and a cooling tower 16.

[0023] The outlet of the main steam pipeline 1 is divided into three routes, wherein the first route is connected with the shaft seal system of the steam turbine 13 through the main steam supply shaft seal valve 2, the second route is connected with the cold re-steam pipeline through the high bypass valve 3, and the third route is connected with the steam turbine 13.

[0024] The outlet of the low bypass pipeline 4 is divided into two routes, wherein one route is connected with the condenser 14 through the low bypass valve 5, and the other route is connected with the inlet of the steam distributor 9 through the low bypass steam to front pool heating pipeline 6, the outlet of the steam distributor 9 is connected with the bottom of the front pool 12, the front pool 12 is located at the bottom of the cooling tower 16, the outlet of the drain tank 15 is connected with the steam distributor 9 through a check valve, the middle part of the front pool 12 is provided with the temperature sensor 11, the water outlet at one side of the front pool 12 is connected with the other side of the front pool 12 through the heating circulating pump 10, and the heating pipeline stop valve 7 and the heating pipeline check valve 8 are arranged on the low bypass steam to front pool heating pipeline 6.

[0025] The wet cooling unit starting method without starting boiler in cold region according to the present application comprises the following steps:

[0026] When the unit is restarted in the shutdown state, the boiler is filled with water by the electric pump and is flushed, the micro-oil heating and the air heater can reach the required temperature by the electric heating mode, after the boiler is ignited, the high bypass valve 3 is opened, and the main steam pipeline 1 and the drain of the reheated steam pipeline are input into the drain tank 15 for pipeline preheating, the drain output by the drain tank 15 is discharged into the steam distributor 9; when the main steam pipeline 1 and the reheated steam pipeline are pressurized, the heating pipeline stop valve 7 is opened, and the low bypass valve 5 is kept in the closed state, the steam does not enter the condenser 14, the steam output by the low bypass pipeline 4 is uniformly input into the front pool 12 through the steam distributor 9, so as to heat the circulating water and start to eliminate the ice in the front pool 12, at this time, the heating circulating pump 10 is started, the cold and hot water in the front pool 12 is mixed, so as to accelerate the elimination of the ice, the main steam parameter and the reheated steam parameter and quality are waited for being qualified, during this period, the condenser 14 is normally watered. When the circulating water temperature reaches more than 5℃, the main engine circulating water pump is started, and the circulating water system of the condenser 14 is established. When the main steam and the reheated steam parameter and the steam quality are qualified, the main steam shaft seal valve 2 is opened to input into the shaft seal system, the vacuum pump is started to establish the system vacuum, when the vacuum reaches the required value, the heating pipeline stop valve 7 is closed, and the low bypass valve 5 is opened, the main steam drain and the reheated steam drain are input into the condenser 14, at this time, all the steam enters the condenser 14, the condenser 14 stops watering, the system is switched to the conventional starting mode, and the steam turbine 13 starts to flush and speed up.

[0027] It should be noted that, considering the pipeline thermal stress and the smooth drain, all the steam pipeline valves need to be slowly opened instead of being opened at one time.

[0028] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that: the specific embodiments of the present application can be modified or replaced by the same, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered in the protection scope of the claims of the present application.

Claims

1. A wet cooling unit starting system without starting boiler in cold region, characterized in that, The main steam pipeline (1), the steam turbine (13), the cold re-steam pipeline, the low bypass pipeline (4), the low bypass valve (5), the condenser (14), the low bypass steam to the front pool heating pipeline (6), the steam distributor (9) and the front pool (12) are included. The outlet of the main steam pipeline (1) is divided into three routes, wherein the first route is communicated with the shaft seal system of the steam turbine (13), the second route is communicated with the cold re-steam pipeline, and the third route is communicated with the steam turbine (13). The outlet of the low bypass pipeline (4) is divided into two routes, wherein one route is communicated with the condenser (14) through the low bypass valve (5), and the other route is communicated with the inlet of the steam distributor (9) through the low bypass steam to the front pool heating pipeline (6), the outlet of the steam distributor (9) is communicated with the bottom of the front pool (12), the outlet of the drain tank (15) is communicated with the steam distributor (9), the water outlet on one side of the front pool (12) is communicated with the other side of the front pool (12), and the heating pipeline stop valve (7) is arranged on the low bypass steam to the front pool heating pipeline (6).

2. The start-up system of a wet cooling unit of a start-up boiler-less boiler in a cold region according to claim 1, characterized in that, The outlet of the drain tank (15) is communicated with the steam distributor (9) through the check valve.

3. The start-up system of a wet cooling unit of a start-up boiler-less boiler in a cold region according to claim 1, characterized in that, The temperature sensor (11) is arranged at the middle part of the front pool (12).

4. The start-up system of a wet cooling unit of a start-up boiler-less boiler in a cold region according to claim 1, characterized in that, The heating pipeline check door (8) is further arranged on the low bypass steam to the front pool heating pipeline (6).

5. The start-up system of a wet cooling unit of a start-up boiler-less boiler in a cold region according to claim 1, characterized in that, The front pool (12) is located at the bottom of the cooling tower (16).

6. The severe cold region wet cooling unit boiler-less start-up system of claim 1, wherein, The water outlet on one side of the front pool (12) is communicated with the other side of the front pool (12) through the heating circulating pump (10).

7. The severe cold region boiler-less wet cooling unit startup system of claim 1, wherein, The outlet of the main steam pipeline (1) is divided into three routes, wherein the first route is communicated with the shaft seal system of the steam turbine (13) through the main steam shaft seal valve (2), the second route is communicated with the cold re-steam pipeline through the high bypass valve (3), and the third route is communicated with the steam turbine (13).

8. A method for starting a wet cooling unit of a boiler without starting in a cold region, characterized by, The starting system of the wet cooling unit without starting boiler in severe cold region based on claim 1 comprises the following steps: When the unit is restarted in the shutdown state, the boiler is filled with water and flushed by the electric pump, and after the boiler is ignited, the drain of the main steam pipeline (1) and the reheated steam pipeline is sent into the drain tank (15) for pipeline preheating, and the drain output by the drain tank (15) is discharged into the steam distributor (9); when the main steam pipeline (1) and the reheated steam pipeline are pressurized, the heating pipeline stop valve (7) is opened, the steam output by the low bypass pipeline (4) is uniformly introduced into the front pool (12) through the steam distributor (9) to heat the circulating water and start to eliminate the ice in the front pool (12); When the main steam parameter, the reheated steam parameter and the steam quality are qualified, the main steam shaft seal valve (2) is opened, the shaft seal system of the steam turbine (13) is put into operation, the vacuum pump is started to establish the system vacuum, when the vacuum reaches the required value, the main steam drain and the reheated steam drain are sent into the condenser (14), at this time, all the steam enters the condenser (14), the condenser (14) stops water supply, the system is switched to the conventional starting mode, and the steam turbine (13) starts to rotate and increase the speed.

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