Steam turbine zero high-pressure heater whole-process input drainage system

Abstract

The utility model relates to a zero high-pressure heater whole-process input drainage system of a steam turbine. The zero high-pressure heater whole-process input drainage system comprises a high-pressure heater system, a first drainage flash tank, a deaerator and a second drainage flash tank, the high-pressure heater system is further connected with a second drain flash tank through the deaerator; the high-pressure heating system comprises a zero high-pressure heater, and the zero high-pressure heater is connected with a first drain flash tank through a zero high-pressure heater accident drain regulating valve; and a drainage small bypass is arranged on a connecting pipeline between the zero high-pressure heater and the first drainage flash tank. The utility model has the beneficial effects that the drainage small bypass regulating valve group is additionally arranged beside the accident drainage regulating valve group, so that the accident drainage regulating valve is kept in a fully-closed state when the zero high pressure is withdrawn, and the flushing is prevented.

Description

TECHNICAL FIELD

[0001] The utility model relates to the power generation technical field, more exactly, it relates to a steam turbine zero high pressure heater full range investment drain system. BACKGROUND

[0002] In recent years, the application of ultra-supercritical 1000MW secondary reheat unit is increasing, in order to further improve the benefit of unit, part of secondary reheat unit begins to use zero high pressure heater, further improves the feed water temperature of unit at low load, improves the economic benefit of unit. The secondary reheat unit superhigh pressure cylinder increases zero high pressure heater, usually adopts regulating valve to regulate zero high pressure heater steam supply and steam supply pressure etc. Usually the first adjustable secondary reheat unit is through the newly increased zero high pressure heater extraction port pressure, and then through the regulating valve to adjust to the appropriate zero high pressure heater inlet pressure. In this way, the problem that the newly increased extraction port is too close to the first extraction port without regulating valve and cannot be holed is avoided. Moreover, another benefit brought is that although the zero high pressure heater extraction port position is more forward, that is, the zero high pressure heater extraction pressure is higher than the extraction pressure required by the final feed water temperature under rated condition, needs pressure reduction regulation, will affect the unit thermal efficiency to some extent, but when the load is reduced to about 90%, the regulating valve is fully opened, the zero high pressure heater extraction pressure can still increase the final feed water temperature to the rated feed water temperature, and the regenerative efficiency of steam turbine is obviously improved. Under the partial load condition below 90%, the zero high pressure heater extraction port pressure is improved, so that the final feed water temperature is also improved compared with the conventional regenerative system, which will better improve the regenerative efficiency of steam turbine under partial load condition and reduce the heat consumption of steam turbine under partial load condition. Especially beneficial to the current situation that the average load rate of unit is about 70% throughout the year.

[0003] The zero high pressure heater is added, the feed water temperature is improved, when the boiler load is above 90%THA, the zero high pressure heater is not put into operation, the feed water temperature is unchanged, when running at low load 90%THA, the zero high pressure heater is used at low load, which can reduce the unit heat consumption to some extent, under partial load condition, the heat consumption can be reduced by about 30kJ / kWh, and the energy-saving effect is obvious.

[0004] When the unit is in low load operation, the final feed water temperature will decrease with the decrease of the load, resulting in the increase of the unit heat consumption and the poor economy, and the increase of the zero number high pressure heater can increase the low load boiler feed water temperature, which will directly improve the economy of the unit. The zero number high pressure heater can improve the economy of the unit in low load operation by increasing the feed water temperature to the optimal value. At the same time, when the unit is in low load operation, the main steam temperature and the reheat steam temperature decrease, and after the zero number high pressure heater is added, the main steam temperature and the reheat steam temperature can also be increased. The zero number high pressure heater can not only increase the unit feed water temperature in partial load, improve the combustion performance of the boiler, improve the circulating thermal efficiency and reduce the heat consumption value, but also reduce the heat exchange capacity of the economizer, increase the economizer outlet flue gas temperature, ensure the increase of the SCR temperature in low load and ensure the denitration efficiency.

[0005] However, at present, the zero number high pressure heater is only needed in low load operation, and in high load, the feed water temperature needs to be ensured not to exceed the design limit, and the zero number high pressure heater cannot be put into operation, at this time, the zero number high pressure heater needs to be removed in high load, and after the zero number high pressure heater is removed, the zero number high pressure heater needs to be ensured in a hot standby state so as to be quickly put into operation in low load. The coal-fired power generating unit has been gradually changed into a peak shaving unit, the high and low load of the unit is switched frequently, and the unit is switched many times a day, so that the zero number high pressure heater is frequently switched between the removed state and the put into operation state.

[0006] At present, the main problem is that when the zero number high pressure heater is removed, the zero number high pressure heater needs to be kept in a hot standby state, the zero number high pressure heater steam extraction regulating valve needs to be kept in a small opening or a bypass regulating valve is added. At this time, the zero number high pressure heater has a small steam inlet, when the zero number high pressure heater is in steam, the zero number high pressure heater liquid level continuously increases, when the liquid level increases to a certain value, the zero number high pressure heater accident drainage regulating valve will be slightly opened to release pressure. According to the present situation, the super 7 times per hour needs to be frequently opened, the unit high load is opened for more than 150 times a day, and according to the regulating valve opening logic, each opening is a small opening. Frequent small opening causes serious erosion of the valve core and the valve body, because the medium parameters at this position are high, the pressure is more than 10Mpa, the valve body has been eroded and thinned by nearly 0.7cm after running for only one month, which seriously affects the safe operation of the unit. Practical new type content

[0007] The utility model aims at the shortage of prior art, proposes a steam turbine zero number high pressure heater full range put into operation drainage system, including:

[0008] The high pressure heater system, the first drainage expansion vessel, the deaerator and the second drainage expansion vessel;

[0009] The high-pressure heater system is further connected with a second drain expansion vessel through the deaerator; the high-pressure heating system comprises a zeroth high-pressure heater, and the zeroth high-pressure heater is connected with the first drain expansion vessel through a zeroth high-pressure heater accident drain adjusting valve; a drain small bypass is arranged on a connecting pipeline between the zeroth high-pressure heater and the first drain expansion vessel, and two ends of the drain small bypass are connected to two sides of the zeroth high-pressure heater accident drain adjusting valve; a small bypass adjusting valve group is arranged on the drain small bypass.

[0010] Preferably, the small bypass adjusting valve group comprises a bypass drain adjusting valve, a bypass drain adjusting valve front isolation door and a bypass drain adjusting valve rear isolation door; the bypass drain adjusting valve front isolation door and the bypass drain adjusting valve rear isolation door are arranged on two sides of the bypass drain adjusting valve respectively.

[0011] Preferably, the high-pressure heater system further comprises a first high-pressure heater, a second high-pressure heater, a third high-pressure heater and a fourth high-pressure heater; the first high-pressure heater, the second high-pressure heater, the third high-pressure heater and the fourth high-pressure heater are all connected with the first drain expansion vessel through corresponding accident drain adjusting valves; the zeroth high-pressure heater, the first high-pressure heater, the second high-pressure heater, the third high-pressure heater and the fourth high-pressure heater are sequentially connected.

[0012] Preferably, the second high-pressure heater is connected with a second high-pressure heater steam cooler, and the fourth high-pressure heater is connected with a fourth high-pressure heater steam cooler.

[0013] Preferably, the capacity of the first drain expansion vessel is greater than that of the second drain expansion vessel.

[0014] The utility model discloses a beneficial effect is:

[0015] 1. The utility model discloses a small bypass adjusting valve group is added to the accident drain adjusting valve group, guarantees the accident drain adjusting valve to keep the full close state when the zeroth high-pressure heater is removed, prevents scouring.

[0016] 2. The utility model discloses a five-stage high-pressure heater series connection structure and the collaborative design of steam cooler, and the feedwater temperature is improved through the zeroth high-pressure heater continuous investment under the low load working condition, and then the regenerative efficiency of steam turbine under the low load working condition is improved, and the heat consumption of steam turbine under the low load working condition is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The utility model provides a kind of steam turbine zeroth high-pressure heater full-course investment drain system structure schematic view;

[0018] Explanation of reference numerals in the attached diagram: 1. No. 0 high-pressure heater; 2. No. 0 high-pressure heater emergency drain regulating valve; 3. First drain expansion tank; 4. Small bypass regulating valve group; 401. Bypass drain regulating valve; 402. Isolation door before bypass drain regulating valve; 403. Isolation door after bypass drain regulating valve; 5. No. 1 high-pressure heater; 6. No. 2 high-pressure heater; 7. No. 3 high-pressure heater; 8. No. 4 high-pressure heater; 9. Deaerator; 10. Second drain expansion tank; 11. No. 2 high-pressure heater evaporator; 12. No. 4 high-pressure heater evaporator. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that, for those skilled in the art, several modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0020] Example 1:

[0021] like Figure 1 As shown, Embodiment 1 of this application provides a fully engaged condensate drainage system for the No. 0 high-pressure heater of a steam turbine, comprising:

[0022] High-pressure heater system, first hydrophobic expansion tank 3, deaerator 9, and second hydrophobic expansion tank 10;

[0023] The high-pressure heater system is also connected to the second condensate expansion tank 10 via the deaerator 9, and the deaerator 9 is connected to the nitrogen charging port. The high-pressure heating system includes a zero high-pressure heater 1, which is connected to the first condensate expansion tank 3 via a zero high-pressure heater emergency condensate regulating valve 2. A condensate bypass is provided on the connecting pipeline between the zero high-pressure heater 1 and the first condensate expansion tank 3, and both ends of the condensate bypass are connected to the two sides of the zero high-pressure heater emergency condensate regulating valve 2. A small bypass regulating valve group 4 is provided on the condensate bypass.

[0024] The small bypass regulating valve group 4 includes a bypass drain regulating valve 401, a bypass drain regulating valve front isolation door 402, and a bypass drain regulating valve rear isolation door 403; the bypass drain regulating valve front isolation door 402 and the bypass drain regulating valve rear isolation door 403 are respectively arranged on both sides of the bypass drain regulating valve 401.

[0025] The high-pressure heater system further comprises a first high-pressure heater 5, a second high-pressure heater 6, a third high-pressure heater 7 and a fourth high-pressure heater 8; the first high-pressure heater 5, the second high-pressure heater 6, the third high-pressure heater 7 and the fourth high-pressure heater 8 are all connected with the first drain expansion vessel 3 through corresponding accident drain regulating valves; the zeroth high-pressure heater 1, the first high-pressure heater 5, the second high-pressure heater 6, the third high-pressure heater 7 and the fourth high-pressure heater 8 are sequentially connected.

[0026] The second high-pressure heater 6 is connected with a second high-pressure heater steam cooler 11, and the fourth high-pressure heater 8 is connected with a fourth high-pressure heater steam cooler 12.

[0027] The capacity of the first drain expansion vessel 3 is greater than that of the second drain expansion vessel 10. For example, the first drain expansion vessel 3 is 40m 3 The capacity of the high-pressure drain expansion vessel is 20m 3 The capacity of the high-pressure drain expansion vessel is 20m The first drain expansion vessel 3 is provided with an interface to a low-pressure condenser connection neck and a low-pressure condenser hot well; the second drain expansion vessel 10 is provided with an interface to a high-pressure condenser connection neck and a high-pressure condenser hot well, and the second drain expansion vessel 10 further receives sixth low-pressure heater accident drain, seventh low-pressure heater accident drain, eighth low-pressure heater accident drain and ninth low-pressure heater accident drain.

Claims

1. A drain system for full range admission of a high pressure turbine zero stage, characterized by, The application relates to a high-pressure heater system, a first steam expansion vessel (3), a deaerator (9) and a second steam expansion vessel (10). The high-pressure heater system is connected with the second steam expansion vessel (10) through the deaerator (9); the high-pressure heater system comprises a zeroth high-pressure heater (1), the zeroth high-pressure heater (1) is connected with the first steam expansion vessel (3) through a zeroth high-pressure heater accident steam drainage regulating valve (2); a steam drainage small bypass is arranged on a connecting pipeline between the zeroth high-pressure heater (1) and the first steam expansion vessel (3), both ends of the steam drainage small bypass are connected with both sides of the zeroth high-pressure heater accident steam drainage regulating valve (2); a small bypass regulating valve group (4) is arranged on the steam drainage small bypass. The small bypass regulating valve group (4) comprises a bypass steam drainage regulating valve (401), a bypass steam drainage regulating valve front isolation door (402) and a bypass steam drainage regulating valve rear isolation door (403); the bypass steam drainage regulating valve front isolation door (402) and the bypass steam drainage regulating valve rear isolation door (403) are arranged on both sides of the bypass steam drainage regulating valve (401) respectively.

2. The drain system for full range admission of a high-pressure stage zero in a steam turbine according to claim 1, characterized in that, The high-pressure heater system further comprises a first high-pressure heater (5), a second high-pressure heater (6), a third high-pressure heater (7) and a fourth high-pressure heater (8); the first high-pressure heater (5), the second high-pressure heater (6), the third high-pressure heater (7) and the fourth high-pressure heater (8) are connected with the first steam expansion vessel (3) through corresponding accident steam drainage regulating valves; the zeroth high-pressure heater (1), the first high-pressure heater (5), the second high-pressure heater (6), the third high-pressure heater (7) and the fourth high-pressure heater (8) are sequentially connected.

3. The drain system for full range admission of a high-pressure stage zero in a steam turbine according to claim 2, characterized in that, The second high-pressure heater (6) is connected with a second high-pressure heater steam cooler (11), and the fourth high-pressure heater (8) is connected with a fourth high-pressure heater steam cooler (12).

4. The drain system for full range admission of a high-pressure stage zero in a steam turbine according to claim 3, characterized by The capacity of the first steam expansion vessel (3) is greater than that of the second steam expansion vessel (10).

5. The steam turbine zero high-pressure casing full-lift drain system of claim 4, wherein, ​

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