CN110425011A - A kind of optimal control method of power station steam turbine group axle envelope and valve level leakage steam system - Google Patents

Abstract

The invention discloses an optimization control method for the shaft seal and door lever steam leakage system of a steam turbine unit in a power station, comprising: at the initial stage of unit start-up, the shaft seal steam is supplied by auxiliary steam, and the inlet temperature is automatically adjusted and controlled through the shaft seal steam supply electric heater, The shaft seal steam supply regulating valve automatically controls the pressure of the shaft seal main pipe to maintain at 3.5kPa; the first pneumatic door and the fourth pneumatic door are opened, the third electric door is closed, the pneumatic steam trap is opened, and the shaft seal overflow regulating valve automatically tracks the shaft seal Main pipe pressure; when the unit is connected to the grid with a load of 20% THA, and the fifth-stage extraction pressure is greater than 0.04MPa, the third electric door starts to open automatically, while keeping the pneumatic trap fully open; when the unit load gradually increases to When the THA is 70% and above, the shaft seal system is in a sealed state, the shaft seal steam supply regulating valve is automatically closed, and the shaft seal overflow regulating valve is automatically opened. This method can ensure that the shaft seal system and door lever leak steam when the unit is started and grid The whole process of operation and load shedding is safe, reliable and energy-efficient.

Description

An optimal control method for the shaft seal and door lever steam leakage system of a power station steam turbine unit

technical field

The invention belongs to the technical field of steam turbine shaft seal system and door lever steam leakage reconstruction optimization technology, and relates to an optimization control method for a steam turbine unit shaft seal and door lever steam leakage system in a power station.

Background technique

The steam turbine shaft seal and door stem leakage system is an important part of the steam turbine. Its main function is to provide sealing steam to the shaft seal of the steam turbine, the main steam valve, and the stem seal of the control valve. In the high and medium pressure cylinder section of the steam turbine, the function of the shaft sealing system is to prevent the steam from leaking out, so as to ensure the high efficiency of the steam turbine. In the low-pressure cylinder area of the steam turbine, the function of the shaft seal system is to prevent outside air from entering the inside of the steam turbine, so as to ensure the highest possible vacuum degree and high efficiency of the steam turbine. The shaft seal system is mainly composed of sealing device, shaft seal steam main pipe, shaft seal heater and other equipment, as well as corresponding valves and pipeline systems.

For a typical SAIC 660-1000MW ultra-supercritical unit, the shaft seal system imposes strict restrictions on its steam supply parameters (temperature 280-320°C, pressure 0.5-0.8MPa) to ensure that the unit meets the requirements under any working conditions. Design requirements. In the actual operation of the unit, accidental tripping conditions cannot be avoided. After the unit trips, if the temperature of the shaft seal steam supply and the temperature of the rotor deviate too much, it may cause the risk of locking the large shaft. In addition, the existence of the gap between the main steam valve and the door lever of the adjustment valve will inevitably cause some steam to leak out, and if the steam leakage of the door lever is not properly controlled during the recovery process, it will cause the erosion loss of the sealing surface of the door lever packing. Therefore, a new method is proposed. An effective and reliable control strategy of the shaft seal and door lever steam leakage system is very important to realize the safety and reliability of the steam turbine unit in the whole start-up operation stage.

In order to build an effective control loop, the newly modified shaft seal and door lever leakage system has added a high-pressure main steam valve, a high-pressure regulating valve to the shaft seal main pipe pneumatic valve, and a high-pressure main steam valve to the condenser pneumatic valve, From the high-pressure regulating door to the No. 7 low-plus pneumatic door, the air leakage from the high-pressure cylinder chamber to the connecting pipe of the medium-pressure cylinder is increased. The measuring points, pressure measuring points and the temperature measuring points of the drain port increase the matching of the high-pressure cylinder seal and reduce the thermal stress of the seal chamber and rotor.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art, and to provide an optimal control method for the shaft seal and door lever steam leakage system of a steam turbine unit in a power station. Safe, reliable and efficient energy-saving operation in the whole process of grid operation and load shedding.

In order to achieve the above object, the optimized control method of the shaft seal and door lever steam leakage system of the steam turbine unit of the power station according to the present invention, the steam turbine unit shaft seal and door lever steam leakage system of the power station includes a high pressure cylinder, a medium pressure cylinder, a low pressure cylinder and The shaft seal main pipe is connected, the high pressure cylinder, the medium pressure cylinder and the low pressure cylinder are connected with the shaft seal main pipe, one end of the first pneumatic valve is connected with the condenser, and the other end of the first pneumatic valve is connected with the high pressure main valve. One end is connected with one end of the second pneumatic valve, the other end of the high-pressure main steam valve is connected with one end of the high-pressure regulating valve, and the other end of the high-pressure regulating valve is connected with one end of the third pneumatic valve and one end of the fourth pneumatic valve. The other end of the fourth pneumatic door is connected with No. 7 low pressure heater, the other end of the second pneumatic door, the other end of the third pneumatic door, one end of the shaft seal steam supply regulating valve and one end of the shaft seal overflow regulating valve are connected with The shaft seal main pipe is connected, the other end of the shaft seal steam supply regulating valve is connected with the auxiliary steam seal header through the shaft seal steam supply regulating valve and the shaft seal steam supply electric heater, the other end of the shaft seal overflow regulating valve is connected with the One end of the first electric door is connected with one end of the second electric door, the other end of the first electric door is connected with the condenser, the other end of the second electric door is connected with the No. 8 low-pressure heater, and the high-pressure cylinder shaft seal The chamber is connected with one end of the third electric door and one end of the pneumatic trap, the other end of the third electric door is connected with the medium pressure cylinder, and the other end of the pneumatic trap is connected with the drain expander, including the following steps:

At the initial stage of unit start-up, the shaft seal steam is supplied by auxiliary steam, and the inlet temperature is automatically adjusted and controlled by the shaft seal steam supply electric heater, and the shaft seal steam supply regulating valve automatically controls the pressure of the shaft seal main pipe to maintain at 3.5kPa; the first pneumatic valve and the second The four pneumatic doors are opened, the third electric door is closed, the pneumatic steam trap is opened, and the shaft seal overflow regulating valve automatically tracks the pressure of the shaft seal main pipe, and is closed at the initial stage of start-up to maintain the shaft seal steam supply temperature at 280°C to 320°C ℃, the pressure of the shaft seal main pipe is 3.5kPa;

When the unit is connected to the grid with a load of 20% THA, and the extraction pressure of the fifth stage is greater than 0.04MPa, the third electric door starts to open automatically. Fully open position, to reduce the disturbance of the pressure of the entire shaft seal main pipe when the self-sealing steam flow of the high pressure cylinder chamber enters the low pressure section, and at the same time keep the pneumatic drain valve fully open;

When the load of the unit gradually increases to 70% THA and above, the shaft seal system reaches a self-sealing state, the shaft seal steam supply regulating valve is automatically closed, the shaft seal overflow regulating valve is automatically opened, and the pressure of the shaft seal main pipe is tracked and maintained at 3.5kPa.

In the load stage, when there is an accident trip or load shedding condition, and it is determined that the main steam temperature is higher than 510°C, the second pneumatic door will automatically open after the trip, and the first pneumatic door will be closed in chain at the same time. The three electric doors are interlocked and closed, and the pneumatic trap remains unblocked.

In the start-up stage of the unit, when the steam turbine locks or the second pneumatic door is fully opened and disappears, the first pneumatic door will be opened in chain;

When the second pneumatic door is in place, the first pneumatic door is closed in chain.

In the start-up stage of the unit, when the turbine lock, the No. 7 low-pressure heater water inlet electric door is opened in place, and the No. 7 low-pressure water supply water outlet electric door is opened in place or when the second pneumatic door opening position disappears, the fourth pneumatic door is opened in chain;

When the second pneumatic door is opened in place, the fourth pneumatic door is closed in chain.

During the start-up stage of the unit, when the turbine locks and the No. 7 low-pressure heater water inlet electric door disappears in place, when the No. 7 low-pressure heater outlet water electric door disappears in place, or when the fourth pneumatic door disappears, the No. Four pneumatic doors are interlocked to open;

When the fourth pneumatic door is opened in place, the second pneumatic door is closed in chain.

The present invention has the following beneficial effects:

The optimized control method for the shaft seal and door lever steam leakage system of the steam turbine unit of the power station described in the present invention can ensure that the whole process of the unit from start-up to full-load operation can be automatically switched according to the steam supply requirements of the steam seal, effectively realizing The switching sequence of the steam source of the door lever leakage steam can minimize the erosion damage of the packing sealing surface caused by the door lever leakage steam, and at the same time, the opening sequence of the electric door between the high pressure cylinder chamber leakage steam and the medium pressure cylinder is proposed , the switching is stable during the operation of the demonstration unit, and the pressure disturbance to the shaft seal main pipe is very small, thus greatly improving the safety and reliability of the shaft seal system of the steam turbine unit and the leakage operation of the door rod, ensuring the shaft seal system and door Rod steam leakage operates safely, reliably and energy-efficiently during the whole process of unit start-up, grid-connected operation and load shedding.

Description of drawings

Fig. 1 is a structural schematic diagram of the shaft seal and door lever steam leakage system of a steam turbine unit in a power station in the present invention.

Among them, 1 is the shaft seal steam supply electric heater, 2 is the shaft seal steam supply regulating valve, 3 is the shaft seal steam supply regulating valve, 4 is the shaft seal overflow regulating valve, 5 is the first electric door, 6 is the second Electric door, 7 is the high-pressure main steam valve, 8 is the high-pressure regulating door, 9 is the first pneumatic door, 10 is the second pneumatic door, 11 is the third pneumatic door, 12 is the fourth pneumatic door, 13 is the third electric door , 14 are pneumatic steam traps.

Detailed ways

The present invention is described in further detail below in conjunction with accompanying drawing:

Referring to Fig. 1, the shaft seal and door rod steam leakage system of the steam turbine unit of the power station includes a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder and a shaft seal main pipe, and the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are connected with the shaft seal mother The pipes are connected, one end of the first pneumatic valve 9 is connected with the condenser, the other end of the first pneumatic valve 9 is connected with one end of the high-pressure main steam valve 7 and one end of the second pneumatic valve 10, and the high-pressure main steam valve 7 The other end of the high-pressure regulating door 8 is connected to one end, the other end of the high-pressure regulating door 8 is connected to one end of the third pneumatic door 11 and one end of the fourth pneumatic door 12, and the other end of the fourth pneumatic door 12 is connected to the No. 7 The low-pressure heater is connected, and the other end of the second pneumatic door 10, the other end of the third pneumatic door 11, one end of the shaft seal steam supply regulating valve 3 and one end of the shaft seal overflow regulating valve 4 are connected with the shaft seal main pipe , the other end of the shaft seal steam supply regulating valve 3 communicates with the auxiliary steam seal header through the shaft seal steam supply regulating valve 2 and the shaft seal steam supply electric heater 1, and the other end of the shaft seal overflow regulating valve 4 communicates with the first One end of the electric door 5 is connected with one end of the second electric door 6, the other end of the first electric door 5 is connected with the condenser, the other end of the second electric door 6 is connected with the No. 8 low-pressure heater, and the high-pressure cylinder The shaft seal chamber communicates with one end of the third electric door 13 and one end of the pneumatic drain valve 14, the other end of the third electric gate 13 communicates with the medium pressure cylinder, and the other end of the pneumatic drain valve 14 communicates with the drain expander .

The optimization control method of the power station steam turbine unit shaft seal and door lever steam leakage system according to the present invention comprises the following steps:

At the beginning of unit start-up, the shaft seal steam is supplied by auxiliary steam, and the inlet temperature is automatically adjusted and controlled by the shaft seal steam supply electric heater 1, and the shaft seal steam supply regulating valve 2 automatically controls the pressure of the shaft seal main pipe to maintain at 3.5kPa; the first pneumatic valve 9 and the fourth pneumatic door 12 are opened, the third electric door 13 is closed, the pneumatic drain valve 14 is opened, the shaft seal overflow regulating valve 4 automatically tracks the pressure of the shaft seal main pipe, and is in the closed state at the initial stage of starting to maintain the shaft seal supply The steam temperature is between 280°C and 320°C, and the pressure of the shaft seal main pipe is 3.5kPa;

In the start-up stage of the unit, when the steam turbine locks or the second pneumatic door 10 is fully opened and disappears, the first pneumatic door 9 is opened in chain, and when the second pneumatic door 10 is opened in place, the first pneumatic door 9 is closed in chain.

In the start-up stage of the unit, when the turbine locks, the No. 7 low-pressure heater water inlet electric door is opened in place, and the No. 7 low-pressure heater outlet water electric door is opened in place, or when the second pneumatic door 10 is opened, the fourth pneumatic door 12 is interlocked. Open, when the second pneumatic door 10 is in place, the fourth pneumatic door 12 will be closed in chain.

In the start-up phase of the unit, when the turbine locks and the No. 7 low-pressure heater water inlet electric door disappears in place, when the No. 7 low-pressure heater outlet water electric door disappears in place, or when the fourth pneumatic door 14 disappears, then The fourth pneumatic door 14 is opened in chain, and when the fourth pneumatic door 14 is opened in place, the second pneumatic door 10 is closed in chain.

When the unit is connected to the grid with a load of 20% THA, and the fifth-stage extraction pressure is greater than 0.04MPa, the third electric door 13 starts to open automatically, and the opening sequence is gradually opened in a cycle of opening for 2 seconds and then stopping for 10 seconds To the fully open position, in order to reduce the disturbance of the pressure of the entire shaft seal main pipe when the self-sealing steam flow of the high pressure cylinder chamber enters the low pressure section, and at the same time keep the pneumatic drain valve 14 fully open;

When the unit load gradually increases to 70% THA and above, the shaft seal system reaches a self-sealing state, the shaft seal steam supply regulating valve 3 is automatically closed, the shaft seal overflow regulating valve 4 is automatically opened, and the pressure of the shaft seal main pipe is tracked and maintained at 3.5kPa .

In the load stage, when there is an accident trip or load shedding condition, and it is determined that the main steam temperature is higher than 510°C, the second pneumatic door 10 will automatically open after the trip, and the first pneumatic door 9 will be closed in chain at the same time, and the turbine will trip. The rear third electric door 13 is chain-closed, and the pneumatic drain valve 14 remains unblocked.

In the actual commissioning of the demonstration unit, after the unit trips, in addition to ensuring the normal feedback of all the above automatic control strategies, it is also necessary to cooperate with closing the main steam pipeline and draining before the high bypass valve, and use the main steam parameters to ensure the leakage of steam through the main steam valve lever. The pressure of the shaft seal steam supply main pipe is stable. At the same time, the steam source of the auxiliary steam header is used in the cold section to be regulated by the shaft seal steam supply electric heater 1 and then supplied to the shaft seal main pipe. The dual steam source ensures the shaft seal system. It is safe and reliable, and at the same time reduces the risk of the large shaft being locked due to the mismatch between the steam supply temperature of the shaft seal and the rotor temperature after the trip. Using this method in the commissioning process, the shaft seal system can guarantee the steam supply to the shaft seal for 6 hours, realize the continuity of the steam supply to the shaft seal before the vacuum reaches zero, ensure the safe shutdown of the equipment, and realize the emergency recovery of the thermal state of the unit. After optimizing the shaft seal and door lever steam leakage system, the reliability guarantee of the shaft seal steam source after the unit trips is improved, the loss of the existing steam source is minimized, and the important steam source is put into use normally, so as to ensure the safety and reliability of the main equipment and Flexibility, to ensure that thermal recovery can be carried out in any situation, so as to ensure the maximum economic benefits under the premise of ensuring the safety of the unit.

The specific embodiments described in this embodiment are only examples to illustrate the spirit of the present invention. Those skilled in the art to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the present invention or go beyond the definition of the appended claims range.

Claims (5)

1. the optimal control method of a kind of power station steam turbine group axle envelope and valve level leakage steam system, the power station steam turbine group axle envelope and Valve level leakage steam system includes that high pressure cylinder, intermediate pressure cylinder, low pressure (LP) cylinder and axle envelope main pipe are connected, high pressure cylinder, intermediate pressure cylinder and low pressure (LP) cylinder with Axle envelope main pipe is connected, and one end of the first pneumatic door (9) is connected with condenser, the other end and high pressure of the first pneumatic door (9) One end of main inlet throttle-stop valve (7) and one end of the second pneumatic door (10) are connected, the other end and high voltage adjusting door of high-pressure main throttle valve (7) (8) one end is connected, the other end of high voltage adjusting door (8) and the one end of third pneumatic door (11) and the 4th pneumatic door (12) One end is connected, and the other end of the 4th pneumatic door (12) is connected with No. 7 low-pressure heaters, the second pneumatic door (10) it is another End, the other end of third pneumatic door (11), one end of shaft seal steam tune valve (3) and shaft seal overflow tune valve (4) one end and axle envelope Main pipe is connected, the other end of shaft seal steam tune valve (3) through shaft seal steam regulating valve (2) and shaft seal steam electric heater (1) with Auxiliary steam seal header is connected, the other end of shaft seal overflow tune valve (4) and one end and the second electrically operated gate of the first electrically operated gate (5) (6) one end is connected, and the other end of the first electrically operated gate (5) is connected with condenser, the other end and 8 of the second electrically operated gate (6) Number low-pressure heater is connected, high pressure cylinder axle envelope chamber and the one end of third electrically operated gate (13) and one end of Pneumatic steam trap valve (14) It is connected, the other end of third electrically operated gate (13) is connected with intermediate pressure cylinder, the other end and dewatering capacity-enlarging of Pneumatic steam trap valve (14) Device is connected, which comprises the following steps:

Unit starting initial stage, gland steam are supplied by auxiliary steam, by shaft seal steam electric heater (1) auto-adjustment control into Mouth temperature, shaft seal steam regulating valve (2) automatically control axle envelope main-piping pressure and maintain 3.5kPa；First pneumatic door (9) and the 4th Pneumatic door (12) is opened, and third electrically operated gate (13) is closed, and Pneumatic steam trap valve (14) is opened, and shaft seal overflow tune valve (4) automatically tracks Axle envelope main-piping pressure, and be in close state in initial start stage, to maintain shaft seal steam temperature between 280 DEG C~320 DEG C, axis Envelope main-piping pressure is 3.5kPa；

When set grid-connection on-load is to 20%THA, and five sections of extraction pressures are greater than 0.04MPa, at this time third electrically operated gate (13) Start to automatically turn on, wherein opening sequence is according to first opening 2s, then stops the mode of 10s gradually partially unrolling is to standard-sized sheet position, to subtract Few high pressure cylinder chamber self-sealing steam flow enters the disturbance during low pressure stage to entire axle envelope main-piping pressure, while keeping pneumatic and dredging Water valve (14) standard-sized sheet；

When unit load steps up 70%THA or more, gland seal system reaches self-sealing state, shaft seal steam tune valve (3) it is automatically closed, shaft seal overflow tune valve (4) automatically turns on, and tracking maintains axle envelope main-piping pressure 3.5kPa.

2. the optimal control method of power station steam turbine group axle envelope according to claim 1 and valve level leakage steam system, feature It is, in the on-load stage, when there is accident chaser or removal of load operating condition, while determining that main steam temperature is higher than 510 DEG C, The second pneumatic door (10) automatically turns on after chaser, while the first pneumatic door of chain closing (9), third electrically operated gate after steam turbine chaser (13) chain closing, Pneumatic steam trap valve (14) are kept unimpeded.

3. the optimal control method of power station steam turbine group axle envelope according to claim 1 and valve level leakage steam system, feature It is, in the unit starting stage, when steam turbine hangs lock or the second pneumatic door (10) reaches position and disappears, then the first pneumatic door (9) Chain unlatching；

When the second pneumatic door (10) reaches, the first pneumatic door of chain closing (9).

4. the optimal control method of power station steam turbine group axle envelope according to claim 1 and valve level leakage steam system, feature It is, in the unit starting stage, when steam turbine hangs lock, No. 7 low-pressure heaters water inlet electrically operated gates reach position and No. 7 low plus water outlet is electronic When door reaches or when the second pneumatic door (10) open position disappears, then the 4th pneumatic door (12) chain unlatching；

When the second pneumatic door (10) reaches, the 4th pneumatic door (12) of chain closing.

5. the optimal control method of power station steam turbine group axle envelope according to claim 1 and valve level leakage steam system, feature It is, in the unit starting stage, when steam turbine hangs lock and No. 7 low-pressure heater water inlet electrically operated gates reach position disappearance, when No. 7 low pressure Heater water outlet electrically operated gate reaches when position disappears or when the 4th pneumatic door (14) open position disappears, then the 4th pneumatic door (14) connects Lock is opened；

When the 4th pneumatic door (14) reaches, the second pneumatic door of chain closing (10).