阅读说明：本技术 冷态汽轮机高压缸倒流加热系统及其方法 (Backflow heating system and method for high-pressure cylinder of cold-state steam turbine ) 是由 文立斌 吴健旭 于 2019-10-29 设计创作，主要内容包括：本发明公开了一种冷态汽轮机高压缸倒流加热系统,主要包括有射气抽气器、油水分离器、汽水分离器、空气加热器和热空气联箱,热空气联箱与汽轮机的高压缸的排气管相连,射气抽气器的抽吸口与汽轮机的高压缸调节阀和汽轮机主汽阀之间的管道相连。本发明针对一些汽轮机组转子轻、易冲转等特点,采用倒流加热方式,可避免达不到有效加热汽缸的目标,避免影响机组正常启动；采用射气抽气器,能够减少空气加热器电力消耗,减少机组启动运行成本；能够快速提升汽轮机高压缸缸温,且有助于汽轮机机组正常启动。本发明还提供一种冷态汽轮机高压缸倒流加热方法,具有发电机组冷态启动节约成本、减少损耗、快速适应电网功率调节调度等特点。(The invention discloses a backflow heating system for a high-pressure cylinder of a cold-state steam turbine, which mainly comprises an air injection air extractor, an oil-water separator, a steam-water separator, an air heater and a hot air header, wherein the hot air header is connected with an exhaust pipe of the high-pressure cylinder of the steam turbine, and a suction port of the air injection air extractor is connected with a pipeline between a regulating valve of the high-pressure cylinder of the steam turbine and a main steam valve of the steam turbine. The invention aims at the characteristics of light rotor, easy impact and rotation and the like of some steam turbine units, adopts a backflow heating mode, can avoid not reaching the target of effectively heating the cylinder, and avoids influencing the normal start of the unit; the air injection air extractor is adopted, so that the power consumption of the air heater can be reduced, and the starting and running cost of the unit can be reduced; can promote the high-pressure jar temperature of steam turbine fast, and help the normal start of steam turbine unit. The invention also provides a backflow heating method for the high-pressure cylinder of the cold-state steam turbine, which has the characteristics of saving the cost of the cold-state start of the generator set, reducing the loss, quickly adapting to the power regulation and dispatching of the power grid and the like.)

1. The utility model provides a cold state steam turbine high pressure cylinder refluence heating system which characterized in that: the jet nozzle of the jet air ejector is sequentially connected with the oil-water separator, the steam-water separator, the air heater and the hot air header, the hot air header is connected with an exhaust pipe of a high-pressure cylinder of the steam turbine, a high-pressure cylinder hot air inlet adjusting valve is arranged on a pipeline connected with the steam turbine, a suction opening of the jet air ejector is connected with a pipeline between the high-pressure cylinder adjusting valve of the steam turbine and a main steam valve of the steam turbine, and a return air adjusting valve is arranged on a pipeline connected with the steam turbine.

2. The cold state turbine high pressure cylinder reverse flow heating system of claim 1, wherein: the number of the air heaters is more than two, and the air heaters are operated in series or in parallel.

3. The cold state turbine high pressure cylinder reverse flow heating system of claim 1, wherein: the oil-water separator is connected with the steam-water separator in series, an oil-water separator front stop valve is arranged between the oil-water separator and the air injection air extractor, and a steam-water separator rear stop valve is arranged between the steam-water separator and the air heater.

4. The cold state turbine high pressure cylinder reverse flow heating system of claim 3, wherein: the oil-water separator front stop valve, the oil-water separator, the steam-water separator and the steam-water separator rear stop valve which are connected in sequence form an oil-steam-water separation mechanism, and the oil-steam-water separation mechanism is multiple and connected in parallel between the air injection air extractor and the air heater.

5. The cold state turbine high pressure cylinder reverse flow heating system of claim 1, wherein: and the hot air header is provided with a safety valve, an exhaust valve, a pressure measuring device, a temperature measuring device and a blow-down door of the hot air header.

6. The cold state turbine high pressure cylinder reverse flow heating system of claim 1, wherein: and a drain tank and an air exhaust valve are arranged between the air return regulating valve and the high-pressure cylinder on a pipeline connecting the air jet air ejector and the steam turbine, and an air return pollution discharge door is arranged on the drain tank.

7. The cold state turbine high pressure cylinder reverse flow heating system of claim 1, wherein: and a compressed air joint of the air jet ejector is connected with a compressed air main pipe, and the compressed air main pipe is provided with a compressed air main pipe air supply regulating valve.

8. A method of heating a high pressure cylinder of a cold state steam turbine in reverse flow using the heating system of claim 1, comprising the steps of:

s1, introducing compressed air into the air injection air extractor, enabling the air flow to flow through the oil-water separator and the steam-water separator, and starting an air heater;

s2, adjusting the temperature of the heated air in the air heater, increasing the air temperature, and transmitting the heated air to the high-pressure cylinder for heating through the exhaust pipe of the high-pressure cylinder after the temperature of the heated air in the hot air header reaches a required value and is stable;

s3, opening the air return regulating valve, enabling hot air to enter the air injection air extractor from a pipeline between the high-pressure cylinder regulating valve and the main steam valve of the steam turbine to realize backflow heating, and sucking, recycling and reusing backflow air flowing through the high-pressure cylinder through the air injection air extractor.

9. The method of claim 8, wherein the step of heating the high pressure cylinder of the cold turbine comprises the steps of: before heating, impurities, oil and vapor water in the oil-water separator, the vapor-water separator and the hot air header are emptied.

Technical Field

The invention relates to the technical field of steam turbines, in particular to a backflow heating system and method for a high-pressure cylinder of a cold-state steam turbine.

Background

The steam that needs to adjust through the cylinder at turbo generator set cold starting in-process heats through the governing valve, because the power generation turbine cylinder wall thickness, it is longer to need the heating time, considers simultaneously that the turbine rotor is heated the inflation with the cylinder and is asynchronous, can take place the sound and rub at the unit start high-speed rotatory in-process, therefore the steam turbine admission can not be too big, needs low flow to heat slowly. This makes the unit start-up time overlength, and the boiler that supplies steam for the steam turbine runs for a long time low-load, and the boiler combustion of low-load operation is very unstable, needs to throw oil or throw plasma operation, causes the unit cold starting cost to be high. For some steam turbine units, rotors of the steam turbine units are light and easy to rush and rotate, the rotors rotate at low and medium speeds in the heating process of a high-pressure cylinder, and when an oil film on a shaft of the steam turbine is not formed, through-flow components of the steam turbine are worn, so that the hidden danger influencing the normal starting of the steam turbine units easily exists.

Disclosure of Invention

In order to overcome the defects, the invention provides the backflow heating system for the high-pressure cylinder of the cold-state steam turbine, which can quickly increase the temperature of the high-pressure cylinder of the steam turbine and is beneficial to normal starting of a steam turbine unit.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a cold state steam turbine high pressure cylinder refluence heating system, including penetrating gas aspirator, oil water separator, catch water, air heater and hot-air header, penetrate the jet of gas aspirator in proper order with oil water separator, catch water, air heater and hot-air header link to each other, the hot-air header links to each other with the blast pipe of the high pressure cylinder of steam turbine, be equipped with high-pressure cylinder hot-air inlet regulating valve on the pipeline that hot-air header and steam turbine link to each other, penetrate the pipeline between the suction opening of gas aspirator and the high pressure cylinder governing valve of steam turbine and the steam turbine main steam valve and link to each other, be equipped with back air regulating valve on the pipeline that penetrates gas aspirator and steam turbine and link to each other.

Preferably, the number of the air heaters is more than two, and the more than two air heaters are operated in series or in parallel.

Preferably, the oil-water separator is connected with the steam-water separator in series, an oil-water separator front stop valve is arranged between the oil-water separator and the air injection air extractor, and a steam-water separator rear stop valve is arranged between the steam-water separator and the air heater.

Preferably, the oil-water separator front stop valve, the oil-water separator, the steam-water separator and the steam-water separator rear stop valve which are connected in sequence form an oil-steam-water separation mechanism, and the oil-steam-water separation mechanism is in a plurality and is connected in parallel between the air injection air extractor and the air heater.

Preferably, the hot air header is provided with a safety valve, an exhaust valve, a pressure measuring device, a temperature measuring device and a hot air header blowdown door.

Preferably, a drain tank and an air exhaust valve are arranged between the air return regulating valve and the high-pressure cylinder on a pipeline connecting the air jet air ejector and the steam turbine, and an air return pollution discharge door is arranged on the drain tank.

Preferably, a compressed air joint of the air injection air ejector is connected with a compressed air main pipe, and the compressed air main pipe is provided with a compressed air main pipe air supply regulating valve.

The invention also provides a backflow heating method for the high-pressure cylinder of the cold-state steam turbine, and the backflow heating system for the high-pressure cylinder of the cold-state steam turbine comprises the following steps:

s1, introducing compressed air into the air injection air extractor, enabling the air flow to flow through the oil-water separator and the steam-water separator, and starting an air heater;

s2, adjusting the temperature of the heated air in the air heater, increasing the air temperature, and transmitting the heated air to the high-pressure cylinder for heating through the exhaust pipe of the high-pressure cylinder after the temperature of the heated air in the hot air header reaches a required value and is stable;

s3, opening the air return regulating valve, enabling hot air to enter the air injection air extractor from a pipeline between the high-pressure cylinder regulating valve and the main steam valve of the steam turbine to realize backflow heating, and sucking, recycling and reusing backflow air flowing through the high-pressure cylinder through the air injection air extractor.

Preferably, before heating, impurities, oil and vapor water in the oil-water separator, the vapor-water separator and the hot air header are evacuated.

Compared with the prior art, the invention has the beneficial effects that:

1. aiming at the characteristics of light rotor, easy impact and rotation and the like of some steam turbine units, the invention adopts a backflow heating mode, can prevent the rotor from rotating at low and medium speed in the heating process of a high-pressure cylinder, consumes the energy of heated air, and avoids the situation that the target of effectively heating a cylinder cannot be reached, and the through-flow part of a steam turbine is abraded in the stage that an oil film of a shaft of the steam turbine is not formed, thereby avoiding the influence on the normal starting of the units;

2. according to the invention, the air injection air extractor is adopted, and low-pressure high-temperature air is sucked by high-pressure compressed air, so that on one hand, the consumption of the high-pressure compressed air is reduced, on the other hand, the temperature of the high-pressure compressed air entering the air injection air extractor is raised because the low-pressure high-temperature air is sucked, the temperature of the air in the air heater is also raised, the power consumption of the air heater is reduced, and the starting and operating cost of a unit is reduced;

3. because the heating medium adopted by the high-pressure cylinder of the steam turbine is air which is non-condensable gas, the hidden troubles that the water content of the steam turbine oil exceeds the standard and metal parts are rusted and the like because the steam is heated and condensed into water are overcome;

4. according to the invention, the unit is improved from a cold state to a warm state and a hot state, so that the load can be quickly increased after the turbine is subjected to impact rotation speed increase and is connected to the grid, the time for the turbine to start and lift the high-pressure cylinder warming of the turbine at the cold state is reduced, and the phenomenon that the oil feeding amount of a boiler is greatly increased due to long-time low-load cylinder warming or the service life loss of a cathode and an anode and the large consumption of electric quantity due to the feeding of plasma are avoided;

5. the backflow heating method for the high-pressure cylinder of the cold-state steam turbine has the advantages of cost saving in cold-state starting of the generator set, rapidness in heating, reduction in loss, rapidness in adaptation to power regulation and scheduling of a power grid and the like.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of the present invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 and 2, a preferred embodiment of the present invention provides a backflow heating system for a high pressure cylinder of a cold steam turbine, which includes an air injection ejector 3, an oil-water separator, a steam-water separator, an air heater, and a hot air header 25, wherein a jet orifice of the air injection ejector 3 is sequentially connected to the oil-water separator, the steam-water separator, the air heater, and the hot air header 25, the hot air header 25 is connected to an exhaust pipe of a high pressure cylinder 47 of the steam turbine, specifically, between the exhaust pipe and a high pressure cylinder exhaust check valve, a high pressure cylinder hot air intake regulating valve 48 is disposed on a pipeline connecting the hot air header 25 and the steam turbine, a suction port of the air injection ejector 3 is connected to a pipeline between a high pressure cylinder regulating valve 38 of the steam turbine and a main steam valve 39 of the steam turbine, and a return regulating valve 52 is disposed on a pipeline connecting the air injection ejector 3 and the steam turbine.

During implementation, the heating air flow enters the high-pressure cylinder 47 from a pipeline between the steam exhaust port of the high-pressure cylinder 47 and the first high-pressure cylinder steam exhaust check valve 41, and enters the high-pressure cylinder 47 from a pipeline between the steam exhaust port of the high-pressure cylinder 47 and the second high-pressure cylinder steam exhaust check valve 45, and the first high-pressure cylinder steam exhaust check valve 41 and the second high-pressure cylinder steam exhaust check valve 45 are in a closed state; therefore, the heating device is a backflow heating mode.

The air ejector 3 adopts a common air ejector structure and mainly comprises a compressed air joint, a jet orifice and a suction port. Compressed air enters from the compressed air joint, return air enters from the suction port and flows out from the jet port together. The air ejector 3 is provided with two air paths, wherein one air path is connected with a compressed air main pipe through a compressed air joint of the air ejector 3, the other end of the compressed air main pipe is connected with a compressed air storage tank (not shown in the figure), the compressed air main pipe is provided with a compressed air main pipe air supply regulating valve 1, the compressed air main pipe air supply regulating valve 1 can be used for regulating the ventilation volume so as to regulate the pressure in the system and the like, and the air path is a main source of compressed air and has high pressure; the other path is connected with a pipeline between a high-pressure cylinder regulating valve 38 of the steam turbine and a main steam valve 39 of the steam turbine through a suction port of the jet air ejector 3, and the pressure is lower for a return air path after heating a high-pressure cylinder 47 of the steam turbine. The air ejector 3 sucks return air with lower pressure after flowing through the high-pressure cylinder 47 by using compressed air with high pressure, and the return air flows out from the jet orifice along with the compressed air, so that on one hand, the consumption of the high-pressure compressed air is reduced, on the other hand, because the sucked air is low-pressure high-temperature air, the temperature of the high-pressure compressed air entering from a compressed air joint of the air ejector 3 is improved, namely, the temperature of the air heater can be improved, the power consumption of the air heater is reduced, and the starting and operating cost of a unit is reduced. The compressed air main pipe is provided with a blowoff valve 2 on a pipeline between the compressed air main pipe air supply regulating valve 1 and the air jet air extractor 3.

An air exhaust valve 51 and a drain tank 49 are arranged on a pipeline between the air return regulating valve 52 and the high-pressure cylinder regulating valve 38, and an air return blow-down valve 50 is arranged on the drain tank 49.

The oil-water separator and the steam-water separator are connected in series for operation, an oil-water separator front stop valve is arranged between the oil-water separator and the air injection air extractor 3, and a steam-water separator rear stop valve is arranged between the steam-water separator and the air heater. In the preferred embodiment, there are two oil-water separators, namely, the first oil-water separator 6 and the second oil-water separator 11; the number of the steam-water separators is two, the two steam-water separators are respectively a first steam-water separator 8 and a second steam-water separator 13, and the first steam-water separator 8 and the second steam-water separator 13 are both provided with a drier. A first oil-water separator front stop valve 4 is arranged between the first oil-water separator 6 and the gas injection air ejector 3, and a second oil-water separator front stop valve 10 is arranged between the second oil-water separator 11 and the gas injection air ejector 3; a first steam-water separator rear stop valve 9 is arranged between the first steam-water separator 8 and the air heater, and a second steam-water separator rear stop valve 15 is arranged between the second steam-water separator 13 and the air heater. The first oil-water separator front stop valve 4, the first oil-water separator 6, the first steam-water separator 8 and the first steam-water separator rear stop valve 9 form an oil-steam-water separation mechanism, the second oil-water separator front stop valve 10, the second oil-water separator 11, the second steam-water separator 13 and the second steam-water separator rear stop valve 15 form an oil-steam-water separation mechanism, and the two oil-steam-water separation mechanisms are connected in parallel. Each oil-steam-water separation mechanism independently forms a group, and two groups of oil-steam-water separation mechanisms can be used for one by one and can also be used simultaneously, so that the switching or the maintenance in operation is convenient. The first oil-water separator 6 is provided with a first oil-water separator sewage discharging door 5, the second oil-water separator 11 is provided with a second oil-water separator sewage discharging door 12, the first steam-water separator 8 is provided with a first steam-water separator sewage discharging door 7, the second steam-water separator 13 is provided with a second steam-water separator sewage discharging door 14, and the above sewage discharging doors are convenient for discharging impurities, oil and steam water inside the second steam-water separator.

The air heater is divided into two air heaters, namely a first air heater 16 and a second air heater 19, the first air heater 16 and the second air heater 19 can be operated in parallel or in series, specifically, a first air heater rear stop valve 20 is arranged on a pipeline between the first air heater 16 and a hot air header 25, a second air heater front stop valve 17 is arranged on a pipeline between the second air heater 19 and a steam-water separator, and a heater switching stop valve 18 is arranged on a pipeline between the first air heater 16 and the second air heater 19. In practice, according to the requirement of air temperature adjustment, the first air heater 16 and the second air heater 19 are connected in parallel in the low temperature stage, and can be connected in series in the high temperature stage to improve the air temperature adaptability.

The hot air header 25 joins the hot air from the first air heater 16 and the second air heater 19, and the hot air header 25 is provided with an exhaust valve 22, a pressure measuring device 23, a temperature measuring device 24 and a hot air header blowdown door 53. Wherein, pressure measurement device 23 adopts E type thermocouple, tests hot-air header 25 air pressure, and temperature measurement device 24 adopts EJA series pressure transmitter, tests hot-air header 25 interior air temperature, installs relief valve 21 on the hot-air header 25, and relief valve 21 is the one protection of taking precautions against hot-air header 25 pressure and exceeding standard and damaging. The exhaust valve 22 can exhaust air in the hot air header 25, and the hot air header blowdown gate 53 is used to exhaust impurities, oil, and steam water in the hot air header 25.

High-pressure compressed air enters through a compressed air main pipe through the air injection air extractor 3, enters an air heater after being purified by the oil-water separator and the steam-water separator, is heated into dry hot air (called hot air), and then is collected in the hot air header 25, the hot air header 25 is used for storage, temperature mixing and air distribution, and then is guided into the high-pressure cylinder 47 through an exhaust pipe of the high-pressure cylinder 47, so that the purpose of quickly heating and warming the high-pressure cylinder 47 is achieved.

The flow-through part of the high-pressure cylinder 47 is heated and warmed, the hot air enters the flow-through part of the high-pressure cylinder 47 in a reverse flow mode to the flow-through, namely a backflow heating mode, pipelines between a steam outlet of the high-pressure cylinder 47 and the first high-pressure cylinder steam exhaust check valve 41 and between the steam outlet of the high-pressure cylinder 47 and the second high-pressure cylinder steam exhaust check valve 45 are utilized to enter the high-pressure cylinder 47, backflow is utilized to heat a rotor and a corresponding stator part sleeve respectively, partial hot air is exhausted to the atmosphere from a drain pipe on a pipeline between a high-pressure cylinder regulating valve and a main steam valve of a steam turbine while flowing through a dynamic and static part, and is recycled after conditions are met, and partial hot air enters the air ejector 3 again through the pipeline to realize recycling.

For better describing the invention, a 135MW stage steam turbine generator set is taken as an example, and the backflow heating process is detailed. The steam turbine is an ultrahigh pressure, single shaft, reaction type, single intermediate reheating, double cylinder double exhaust condensing steam turbine, please refer to fig. 2, the steam turbine mainly comprises a high pressure cylinder 47, an intermediate pressure cylinder 36, a low pressure cylinder I34, a low pressure cylinder II33, a condenser 30, a condensate pump 31, corresponding connecting pipelines, and a deaerating water level regulating valve 26, a condenser vacuum breaking door 31, a low pressure cylinder desuperheating water first regulating valve 27, a low pressure cylinder desuperheating water second regulating valve 29, a high pressure cylinder regulating valve 38, a steam turbine main valve 39, a steam turbine bypass valve 40, a first high pressure cylinder exhaust check valve 41, a second high pressure cylinder exhaust check valve 45, a low pressure cylinder desuperheating water first regulating valve 27, a low pressure cylinder desuperheating water second regulating valve 29, a high pressure cylinder inner cylinder regulating level metal temperature measuring device 42, a shaft eccentricity measuring device 43 are arranged on the high pressure cylinder 47, The device comprises a turbine high-pressure differential expansion measuring device 44 and a turbine high-pressure cylinder upper and lower cylinder temperature difference measuring device 46, wherein a first low-pressure cylinder steam exhaust measuring device 35 is arranged on a low-pressure cylinder I34, and a second low-pressure cylinder steam exhaust measuring device 32 is arranged on a low-pressure cylinder II 33. The first high-pressure cylinder steam exhaust check valve 41 and the second high-pressure cylinder steam exhaust check valve 45 are respectively installed on the exhaust pipes of the high-pressure cylinder 47 (the number of the exhaust pipes of the high-pressure cylinder 47 is two), the hot air header 25 is respectively communicated with the two exhaust pipes, and the connection position is between the high-pressure cylinder 47 and the first high-pressure cylinder steam exhaust check valve 41 and the second high-pressure cylinder steam exhaust check valve 45.

Before heating, the turbine is in a cold state, i.e. the temperature measured by the high-pressure cylinder inner cylinder regulating stage metal temperature measuring device 42 is less than a certain value, such as < 150 ℃ in the preferred embodiment.

The continuous turning of the turbine is normal, and the test value of the shaft eccentricity measuring device 43 is smaller than a certain value, such as < 76um in the preferred embodiment.

The test value of the turbine high pressure differential expansion measuring device 44 is preferably-1.2 mm-6.6 mm.

Accumulated water in each heating pipeline is drained; the turbine body and the extraction pipe are drained and then all the drain valves of the high pressure cylinder 47 of the turbine are closed.

The operation of a compressed air system is ensured, the air source is normally supplied, and the blowoff valve 2 on the compressed air main pipe is opened to drain impurities such as oil, steam and water in the pipe.

The condenser 30 is evacuated to zero and the shaft seal steam is stopped. The condenser 30 of steam turbine leads to the circulating water, and condenser vacuum destroys door 31 and opens, and all other valves are all closed.

Before heating, the backflow heating system is discharged and the heating pipe is operated.

Before the heating system is put into use, a first oil-water separator blowdown door 5, a second oil-water separator blowdown door 12, a first steam-water separator blowdown door 7, a second steam-water separator blowdown door 14, a hot air header blowdown door 53 and a return air blowdown door 50 are opened, and impurities, oil, steam and water are exhausted;

keeping a first oil-water separator blowdown door 5, a second oil-water separator blowdown door 12, a first steam-water separator blowdown door 7, a second steam-water separator blowdown door 14, a hot air header blowdown door 53 and a return air blowdown door 50 open, opening a first oil-water separator front stop valve 4 and a second oil-water separator front stop valve 10, opening a compressed air main pipe air supply regulating valve 1 with the opening degree of 5-30%, and purging a heating system pipeline;

opening a first steam-water separator rear stop valve 9, a second steam-water separator rear stop valve 15, a heater switching stop valve 18 and a hot air header blowdown door 53 for purging; after purging is completed, the pair of air exhaust valves 51 are opened, and the heater switching stop valve 18 is closed; and then closing the first oil-water separator blowdown door 5, the second oil-water separator blowdown door 12, the first steam-water separator blowdown door 7, the second steam-water separator blowdown door 14, the hot air header blowdown door 53 and the return air blowdown door 50, automatically opening and closing according to the liquid level.

After the above work is completed, the heating operation is started.

The first oil-water separator front stop valve 4 and the first steam-water separator rear stop valve 9 are closed, the second oil-water separator front stop valve 10 and the second steam-water separator rear stop valve 15 are opened, and the second oil-water separator 11 and the second steam-water separator 13 are put into operation. Of course, the first oil-water separator front stop valve 4 and the first steam-water separator rear stop valve 9 can be opened according to the maintenance or repair requirement, the second oil-water separator front stop valve 10 and the second steam-water separator rear stop valve 15 are closed, the second oil-water separator 11 and the second steam-water separator 13 are cut off, and the first oil-water separator 6 and the first steam-water separator 8 are put into operation;

keeping the opening degree of an air supply regulating valve 1 of a compressed air main pipe at 5-20%, supplying power to a first air heater 16 and a second air heater 19, adjusting the temperature to a zero position, and closing a matched air switch of the control cabinet;

and (3) opening the exhaust valve 22, adjusting the heating air temperature set values of the first air heater 16 and the second air heater 19, increasing the air temperature, when the test value of the hot air header temperature measuring device 23 reaches the required value and is stable, opening the air exhaust valve 51, opening the high-pressure cylinder regulating valve 38, simultaneously closing the exhaust valve 22, gradually opening the high-pressure cylinder hot air inlet regulating valve 48, and allowing hot air to enter the high-pressure cylinder 47 from the exhaust pipe of the high-pressure cylinder 47, namely heating the high-pressure cylinder 47 by supplying hot air in a backflow mode, so that the cylinder temperature of the high-pressure cylinder 47 is increased.

When the steam trap 49 is empty of water, the air return adjusting valve 52 is opened, the air return blowdown valve 50 and the opposite air exhaust valve 51 are closed, hot air enters the air injection air extractor 3 from a pipeline between the high-pressure cylinder adjusting valve 38 and the main steam valve 39 of the steam turbine, and the return air flowing through the high-pressure cylinder 47 is sucked, recovered and reused through the air injection air extractor 3.

The measured value of the hot air header pressure measuring device 24 in heating operation is kept between 0.2 MPa and 0.6MPa, and the pressure can be cooperatively adjusted through the air supply adjusting valve 1 of the compressed air main pipe, the matching of the air exhaust valve 51 and the suction effect of the air ejector 3 on the return air of the high-pressure cylinder 47 according to the cylinder temperature lifting effect.

The first air heater 16 and the second air heater 19 are connected in parallel in the low temperature stage, and can be connected in series in the high temperature stage to improve the air temperature adaptability.

In the gradual rising process of the cylinder temperature, the metal temperature rise rate of the cylinder monitored by the high-pressure cylinder and the medium-pressure cylinder in the rapid heating process is controlled to be less than or equal to 10 ℃/h, and the instant is not more than 18 ℃/h.

The set value of the air outlet temperature of the heating system is adjusted in time along with the rise of the temperature of the cylinder after the heating is put into operation, and the set value is always kept to be higher than the temperature of the cylinder by a certain value. The principle is shown in table 1 below.

TABLE 1 relationship table of heated air temperature and high pressure cylinder in-cylinder temperature

Temperature of heated air	Temperature difference between inner cylinder adjusting metal of high-pressure cylinder and heated air
		＞300℃	＜50℃
＞200℃	＜80℃
		＞150℃	＜100℃

In the process of rapidly heating the steam turbine, the testing values of the first low-pressure cylinder steam exhaust temperature measuring device 35 and the first low-pressure cylinder steam exhaust measuring device 35 are kept at a certain value, if the value is more than or equal to 80 ℃ in the preferred embodiment, a condensate system is put into use, and the low-pressure cylinder steam exhaust water spray temperature reduction is started.

The temperature difference measuring device 46 for the upper cylinder and the lower cylinder of the high-pressure cylinder of the steam turbine is kept to be smaller than a certain value, the test value is less than 56 ℃ in the preferred embodiment, and the temperature difference measuring device can be adjusted by opening the drain valve 54 of the high-pressure cylinder.

The continuous turning of the steam turbine is kept normal, the testing value of the shaft eccentricity measuring device 43 is smaller than a certain value, and the testing value in the preferred embodiment is smaller than 76 um. The high pressure differential expansion measuring device 44 of the steam turbine has a test value of-1.2 mm to 6.6 mm.

When the first air heater 16 and the second air heater 19 are suddenly powered off, the high-pressure cylinder hot air inlet adjusting valve (48) is automatically closed, and cold air is prevented from impacting the high-pressure cylinder 47.

In order to ensure safety, in the rapid heating process, the pressure of the hot air header 25 is set to a certain ratio, when the pressure is greater than 0.9, the safety valve 21 is automatically opened to release the pressure, and the hot air header is reset after normal operation; when the testing value of the heating air pressure measuring device 23 is less than 0.05MPa, the switches of the first air heater 16 and the second air heater 19 are automatically closed, and the power supply is cut off.

Heating the steam turbine from a cold state to a warm state or a hot state according to starting requirements, wherein the warm state or the hot state is divided according to the metal temperature of an inner cylinder adjusting stage of a starting cylinder of the steam turbine:

and (3) cold state: the temperature of the adjusting metal is less than 150 ℃.

Temperature state: the temperature of the adjusting metal is higher than 150 ℃ and lower than 280 ℃.

Thermal state: the temperature of the regulating grade metal is more than 280 ℃ and less than 380 ℃.

When heating is completed, the high pressure cylinder hot air inlet regulating valve 48 is closed, and the exhaust valve 22 on the hot air header 25 is opened; deactivating the first air heater 16 and the second air heater 19; the return air adjustment valve 52 is closed.

After the heating is stopped, the steam turbine has the steam inlet rush rotation starting condition at the same time.

And after the test value of the temperature measuring device 24 of the hot air header 25 is reduced to the ambient temperature, the heating system completely quits the operation.

According to the invention, aiming at the characteristics of light rotor, easy impact and rotation and the like of some steam turbine units, a backflow heating mode is adopted, so that the problems that the rotor rotates at a low speed and a medium speed in the heating process of the high-pressure cylinder 47, the energy of heated air is consumed, the target that the cylinder cannot be effectively heated is avoided, and the through-flow part of the steam turbine is abraded in the stage that an oil film of a shaft of the steam turbine is not formed, and the normal starting of the units is not. According to the invention, the air injection air ejector 3 is adopted, and the low-pressure high-temperature air is sucked by the high-pressure compressed air, so that on one hand, the consumption of the high-pressure compressed air is reduced, on the other hand, the temperature of the high-pressure compressed air entering the air injection air ejector 3 is raised because the low-pressure high-temperature air is sucked, that is, the temperature of the air in the air heater is also raised, the power consumption of the air heater is reduced, and the starting and operating cost of a unit is reduced. Because the heating medium adopted for the high-pressure turbine cylinder 47 is air which is non-condensable gas, the hidden troubles that the water content of the steam turbine oil exceeds the standard and metal parts are rusted and the like because the steam is heated and condensed into water are overcome. The invention improves the unit from cold state to warm state and hot state, so that the load can be quickly increased after the turbine is subjected to the speed increase and grid connection, the time for the turbine to start and lift the high-pressure cylinder of the turbine at cold state is reduced, and the phenomenon that the oil feeding amount of the boiler is greatly increased or the service life of the cathode and the anode is lost and the electric quantity is greatly consumed due to the feeding of plasma due to the long-time low-load cylinder warming is avoided. The backflow heating method for the high-pressure cylinder of the cold-state steam turbine has the advantages of saving cost, reducing loss, being fast suitable for power regulation and dispatching of a power grid and the like when the generator set is started in a cold state.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.