阅读说明：本技术 单台100%汽动给水泵可rb的锅炉除氧给水系统及控制方法 (RB-capable boiler deoxygenation water supply system with single 100% steam-driven water supply pump and control method ) 是由 李勇 苏永健 白世雄 解世涛 陈景勇 刘文仓 李雪冰 段新潮 冯培峰 刘琼伟 杨 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种单台100％汽动给水泵可RB的锅炉除氧给水系统及控制方法,涉及火力发电技术领域,包括由除氧器、1号截止阀、电动给水泵前置泵、1号调节阀、2号截止阀、电动给水泵、1号逆止阀、3号截止阀、2号逆止阀、4号截止阀、5号截止阀、2号调节阀、汽动给水泵、6号截止阀、3号逆止阀、7号截止阀、4号逆止阀、8号截止阀等组成的除氧给水系统,同时采用快速启动电动给水泵方法减少锅炉断水时间,保护水冷壁的安全性,大大增加除氧给水系统的安全性、稳定性和可靠性。(The invention discloses a RB-capable boiler deoxygenation water supply system with a single 100% steam-driven water supply pump and a control method, and relates to the technical field of thermal power generation.)

1. The utility model provides a but single unit 100% steam-driven feed water pump RB's boiler deoxidization feed water system, includes oxygen-eliminating device (1), its characterized in that: the system also comprises an electric water supply system with 50% load and a steam-driven water supply system with 100% load;

the electric water supply system comprises a No. 1 stop valve (2), an electric water supply pre-pump (3), an electric water supply pump (6), a No. 2 check valve (9), a No. 4 stop valve (10), a No. 1 regulating valve (4) and a No. 2 stop valve (5); the inlet of the No. 1 stop valve (2) is connected with the outlet of the deaerator (1), and the outlet of the No. 1 stop valve (2) is connected with the electric water feeding pre-pump (3), the electric water feeding pump (6), the No. 2 check valve (9) and the No. 4 stop valve (10) in series and then connected with the boiler; the inlet of the No. 2 stop valve (5) is connected with the outlet of the electric feed pump (6), and the outlet of the No. 2 stop valve (5) is connected with the inlet of the deaerator (1) through the No. 1 regulating valve (4);

the steam-driven water supply system comprises a No. 5 stop valve (11), a steam-driven water supply pump (13), a No. 4 check valve (17), a No. 8 stop valve (18), a No. 2 regulating valve (12) and a No. 6 stop valve (14); the inlet of the No. 5 stop valve (11) is connected with the outlet of the deaerator (1), and the outlet of the No. 5 stop valve (11) is connected with the steam feed pump (13), the No. 4 check valve (17) and the No. 8 stop valve (18) in series in sequence and then connected with the boiler; the inlet of the No. 6 stop valve (14) is connected with the outlet of the steam feed water pump (13), and the outlet of the No. 6 stop valve (14) is connected with the inlet of the deaerator (1) through the No. 2 regulating valve (12).

2. The single 100% steam-fed water pump RB boiler deoxygenated water feed system of claim 1, wherein: the pump head of the electric feed pump (6) is equal to or greater than the pump head of the steam feed pump (13).

3. The single 100% steam-fed water pump RB boiler deoxygenated water feed system of claim 1, wherein: the electric water supply system further comprises a check valve (7) No. 1, an inlet of the check valve (7) No. 1 is connected with the electric water supply pump (6), and an outlet of the check valve (7) No. 1 is connected with the reheater through a stop valve (3) No. 3.

4. The single 100% steam-fed water pump RB boiler deoxygenated water feed system of claim 1, wherein: the steam-driven water supply system further comprises a No. 3 check valve (15), an inlet of the No. 3 check valve (15) is connected with the steam-driven water supply pump (13), and an outlet of the No. 3 check valve (15) is connected with the reheater through a No. 7 stop valve (16).

5. A method for controlling a boiler deoxygenated water supply system according to claim 1, comprising:

when the steam feed pump (13) normally operates, the stop valve (4) is opened, the stop valve (5) is opened, the opening of the regulating valve (4) to the No. 1 is 100 percent, and the opening of the scoop tube of the electric feed pump (6) is 20 percent; the state of the equipment is maintained, the waterway of the electric feed pump (6) is kept smooth, and the electric feed pump (6) can be quickly started when in demand;

when the steam feed water pump (13) breaks down or trips, the electric feed water pump (6) is started immediately, the initial starting current is increased rapidly, and the No. 1 regulating valve (4) is closed after the current of the electric feed water pump (6) returns to normal.

6. The control method according to claim 5, characterized in that: after the electric feed pump (6) is started for 9s, the No. 1 regulating valve (4) starts to be closed.

7. The control method according to claim 5, characterized in that: the duration of closing the No. 1 regulating valve (4) is 32 s.

Technical Field

The invention relates to the technical field of thermal power generation, in particular to a de-aeration water supply system of a boiler with a single 100% steam-driven water supply pump RB and a control method.

Background

When a main auxiliary machine of an operating large thermal power generating unit fails or is manually cut off, so that the boiler output cannot meet the requirement of the unit load, and the real-time power of the unit is limited, in order to adapt to the output of operating equipment, a unit coordination control system automatically and rapidly reduces the unit load to a target load value which can be borne by the operating auxiliary machine, and controls the unit to continuously operate within an allowable parameter range without stopping the furnace, wherein the process is called auxiliary machine failure rapid load Reduction (RUNBACK), and is called RB for short. The RB working condition is the test of the unit on the most severe thermal control, and the mutual coordination and coordination of all subsystems of the unit are required. In order to smoothly complete the RB, the system is indispensable for rationality and compatibility.

The feed pump RB is one of the most important links in the RB test. With the continuous increase of unit parameters, the electric water feeding pump can not meet the boiler water feeding requirement under the condition of large load gradually due to the fact that the electric water feeding pump consumes too much service power, and accordingly the steam-driven water feeding pump is used for replacing the electric water feeding pump, two water feeding systems of a single steam pump with 100% load or 2 steam pumps with 50% load are gradually generated, the steam pump system can be configured with a small-capacity electric pump to be used as a small flow at the initial starting stage of the system under the condition of low flow or no auxiliary steam source under the common condition, and the steam pump is switched back to output when the load is increased to a certain degree. Compared with 2 steam pump systems with 50% capacity, a single steam pump system with 100% capacity is simpler in system arrangement, relatively small in maintenance difficulty and convenient to control system operation; similarly, the defect is clear, namely after a single 100 percent capacity steam pump is tripped due to failure, the water cut of the boiler can be immediately caused, and the boiler and the steam turbine are tripped, so that the safety and the reliability are lower.

The patent document 'a control system and a control method for a high-backpressure steam-driven feed water pump of a large-scale generator set' (patent application number: 201910782958.3) discloses a steam-driven feed water pump control system, which mainly aims at reducing the number of devices, setting an electric feed water pump to meet the requirement of feed water flow in the starting stage and making up the defect that the steam-driven feed water pump cannot be normally used when the flow is low. In addition, the electric pump preposition pump is only set for the electric feed pump inlet water pressure boost, the normal use of the electric feed pump is met, and the electric feed pump cavitation is prevented. However, in the above technical scheme, because the lift of the electric feed pump is insufficient, when the steam feed pump fails, even if the electric feed pump operates again, the requirement of continuously supplying water into a water supply system pipeline cannot be met, so that the boiler is disconnected from water, then the boiler and the steam turbine are tripped, only unplanned shutdown can be caused at the moment, and the safety and reliability are low.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a RB-capable boiler deoxygenation water supply system with a single 100% steam-driven water supply pump and a control method thereof, wherein the control method for rapidly starting the electric water supply pump is adopted, so that even if the single 100% steam-driven water supply pump trips, the power of the water supply system can be continuously maintained by starting the electric water supply pump, and the safety, the stability and the reliability of the boiler system are greatly improved.

In order to achieve the above purposes, the technical scheme adopted by the invention is as follows: a single 100% steam-driven feed pump RB-capable boiler deoxygenation water supply system comprises a deoxygenator, an electric water supply system with 50% load and a steam-driven water supply system with 100% load; the electric water supply system comprises a No. 1 stop valve, an electric water supply pre-pump, an electric water supply pump, a No. 2 check valve, a No. 4 stop valve, a No. 1 regulating valve and a No. 2 stop valve; the inlet of the No. 1 stop valve is connected with the outlet of the deaerator, and the outlet of the No. 1 stop valve is connected with the boiler after being connected with the electric water feeding pre-pump, the electric water feeding pump, the No. 2 check valve and the No. 4 stop valve in series in sequence; the inlet of the No. 2 stop valve is connected with the outlet of the electric water feed pump, and the outlet of the No. 2 stop valve is connected with the inlet of the deaerator through the No. 1 regulating valve; the steam-driven water supply system comprises a No. 5 stop valve, a steam-driven water supply pump, a No. 4 check valve, a No. 8 stop valve, a No. 2 regulating valve and a No. 6 stop valve; the inlet of the No. 5 stop valve is connected with the outlet of the deaerator, and the outlet of the No. 5 stop valve is connected with the boiler after being sequentially connected with the steam feed pump, the No. 4 check valve and the No. 8 stop valve in series; the inlet of No. 6 stop valve and the exit linkage of steam feed pump, the export of No. 6 stop valve is through the access connection of No. 2 governing valves and oxygen-eliminating device.

On the basis of the technical scheme, the pump head of the electric feed pump is equal to or greater than the pump head of the steam feed pump.

On the basis of the technical scheme, the electric water supply system further comprises a No. 1 check valve, an inlet of the No. 1 check valve is connected with the electric water supply pump, and an outlet of the No. 1 check valve is connected with the reheater through a No. 3 stop valve.

On the basis of the technical scheme, the steam-driven water supply system further comprises a No. 3 check valve, an inlet of the No. 3 check valve is connected with the steam-driven water supply pump, and an outlet of the No. 3 check valve is connected with the reheater through a No. 7 check valve.

The invention also provides a control method based on the boiler deoxygenation water supply system, which comprises the following steps: when the steam feed pump normally operates, opening the stop valve No. 4, and opening the stop valve No. 2 until the opening of the regulating valve No. 1 is 100% and the opening of the electric feed pump spoon pipe is 20%; the state of the equipment is maintained, the waterway of the electric feed pump is kept smooth, and the electric feed pump can be quickly started when required; when the steam feed pump breaks down or trips, the electric feed pump is started immediately, the initial starting current is increased rapidly, and after the current of the electric feed pump returns to normal, the No. 1 regulating valve is closed.

On the basis of the technical scheme, after the electric feed water pump is started for 9s, the No. 1 regulating valve is started to be closed.

On the basis of the technical scheme, the duration of closing the No. 1 regulating valve is 32 s.

The invention has the beneficial effects that:

the boiler deoxygenation water supply system is only provided with one steam-driven water supply pump and one electric water supply pump. Compared with a double-air pump system, the system in the disclosure has a simple structure, and the steam feed pump control system is simple to operate and can still adopt the electric feed pump to start the system under the condition of no auxiliary steam source. Compare with traditional single vapor pump and single electric pump system, when the steam-driven feed pump breaks down or manual excision, boiler water supply demand under the high load condition can't be satisfied to traditional deoxidization water supply system charge pump, can only carry out the unplanned shut down, this system can satisfy after setting up leading pump of electronic feed pump and stepping up jointly and continue to supply water to the boiler, can carry out RB this moment and make the coordination system slowly reduce to the running condition of electronic feed pump in exerting oneself, do not shut down when realizing unit steam-driven feed pump tripping operation and continue safe and stable operation.

Drawings

FIG. 1 is a schematic diagram of a single 100% steam-fed water pump RB boiler deoxygenation feedwater system according to an embodiment of the present invention.

FIG. 2 is a graph of the startup current of the electric feed water pump after the steam feed water pump trips in an embodiment of the present invention;

FIG. 3 is a graph of electric feedwater pump current and fluid coupling feedback as a function of electric feedwater pump recirculation valve closing process in an embodiment of the present invention;

FIG. 4 is a graph showing the wall temperature change of different waterwalls after the steam feed pump trips in an embodiment of the present invention.

Reference numerals:

1-a deaerator; stop valve No. 2-1; 3-electric water supply pre-pump; no. 4-1 regulating valve; no. 5-2 stop valve; 6-electric feed water pump; no. 7-1 check valve; no. 8-3 stop valve; no. 9-2 check valve; no. 10-4 stop valve; stop valve No. 11-5; no. 12-2 regulating valve; 13-a steam feed pump; no. 14-6 stop valve; no. 15-3 check valve; stop valve No. 16-7; no. 17-4 check valve; 18-8 stop valve.

Detailed Description

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout.

The technical scheme and the beneficial effects of the invention are clearer and clearer by further describing the specific embodiment of the invention with the accompanying drawings of the specification. The embodiments described below are exemplary and are intended to be illustrative of the invention, but are not to be construed as limiting the invention.

Referring to fig. 1, an embodiment of the present invention provides a single 100% steam-driven feed-water pump RB boiler deoxygenation water supply system, including a deoxygenator 1, further including a 50% load electric water supply system and a 100% load steam-driven water supply system; the steam-driven water supply system can meet the water supply flow demand when the load is 100 percent, and the electric water supply system can meet the water supply flow demand when the load is below 50 percent. In the invention, the main functions of the electric water supply system disclosed by the invention are that after the steam-driven water supply pump under low load (less than 40%) and low load (less than 40%) trips, the electric water supply pump starts to supply main water supply flow and the steam-driven water supply pump under high load (more than 40%) trips, after the electric water supply pump starts, the electric water supply pump quickly rises to the electric pump at the maximum flow rate, and the system stably runs under 40% load after load shedding (RB).

The electric water supply system comprises a No. 1 stop valve 2, an electric water supply pre-pump 3, an electric water supply pump 6, a No. 2 check valve 9, a No. 4 stop valve 10, a No. 1 regulating valve 4 and a No. 2 stop valve 5; the inlet of the No. 1 stop valve 2 is connected with the outlet of the deaerator 1, and the outlet of the No. 1 stop valve 2 is connected with the boiler after being sequentially connected with the electric water feeding pre-pump 3, the electric water feeding pump 6, the No. 2 check valve 9 and the No. 4 stop valve 10 in series; the inlet of the No. 2 stop valve 5 is connected with the outlet of the electric feed pump 6, and the outlet of the No. 2 stop valve 5 is connected with the inlet of the deaerator 1 through the No. 1 regulating valve 4; the main water supply flow of the electric water supply system is that main water flows through a No. 1 stop valve from a deaerator, is boosted through a preposed pump of an electric water supply pump, is output by the electric water supply pump, then flows through a No. 2 check valve and a No. 4 stop valve, and then flows into a boiler through other heat exchange equipment. The small-flow recirculating water flow of the electric water supply system is that the main water supply returns to the deaerator from the outlet of the electric water supply pump after passing through the No. 2 stop valve and the No. 1 regulating valve respectively.

The steam-driven water supply system comprises a No. 5 stop valve 11, a steam-driven water supply pump 13, a No. 4 check valve 17, a No. 8 stop valve 18, a No. 2 regulating valve 12 and a No. 6 stop valve 14; the inlet of the No. 5 stop valve 11 is connected with the outlet of the deaerator 1, and the outlet of the No. 5 stop valve 11 is connected with the boiler after being sequentially connected with the steam feed pump 13, the No. 4 check valve 17 and the No. 8 stop valve 18 in series; the inlet of No. 6 stop valve 14 is connected with the outlet of steam feed pump 13, and the outlet of No. 6 stop valve 14 is connected with the inlet of oxygen-eliminating device 1 through No. 2 governing valve 12. The main water supply flow of the steam-driven water supply system is that main water flows through a No. 5 stop valve from the deaerator, is boosted by the power of the steam-driven water supply pump, then flows through a No. 4 check valve and a No. 8 stop valve, and then enters the boiler through other heat exchange equipment. The small-flow recirculating water flow of the steam feed water system is that main feed water respectively passes through a No. 6 stop valve and a No. 2 regulating valve from the outlet of a steam feed water pump and then returns to the deaerator.

Specifically, the head of the electric feed pump 6 is equal to or greater than the head of the steam feed pump 13, and the head of the electric feed pump 6 is equal to or greater than the head of the electric feed pump 6. The electric feed pump is arranged, the preposed pump and the electric feed pump are used for boosting together, the two pump lifts and the steam feed pump lift which is more than or equal to the pump lift of the steam feed pump are realized, under the condition of high load, when the steam feed pump loses output suddenly, the electric feed pump can still supply water to the boiler continuously after being started, and only the water supply flow is reduced.

Specifically, the electric water supply system further comprises a check valve 7 No. 1, an inlet of the check valve 7 No. 1 is connected with the electric water supply pump 6, and an outlet of the check valve 7 No. 1 is connected with the reheater through a stop valve 3 No. 3. The steam-driven water supply system also comprises a No. 3 check valve 15, the inlet of the No. 3 check valve 15 is connected with the steam-driven water supply pump 13, and the outlet of the No. 3 check valve 15 is connected with the reheater through a No. 7 stop valve 16. The No. 1 check valve and the No. 2 check valve are respectively arranged at the outlets of the electric feed pump and the steam feed pump, and after the steam feed pump trips, the No. 1 check valve and the No. 2 check valve can keep the outlet pressure of the whole feed system, so that the water in a high-position boiler does not flow back; the start-up environment is provided for motor-driven feed pump quick start, opens through 1 number recirculation governing valve, and motor-driven feed pump low discharge starts, reduces motor-driven feed pump start load, realizes motor-driven feed pump quick start.

The embodiment of the invention also discloses a control method based on the boiler deoxygenation water supply system, which comprises the following steps:

when the steam feed pump 13 normally operates, the stop valve No. 4 10 is opened, the stop valve No. 2 is opened, the opening of the regulating valve No. 14 is 100%, and the opening of the electric feed pump 6 is 20% of a spoon pipe; the state of the equipment is maintained, the waterway of the electric feed pump 6 is kept smooth, and the electric feed pump 6 can be quickly started when in demand;

when the steam feed pump 13 breaks down or trips, the electric feed pump 6 is started immediately, the initial starting current is increased rapidly, and the No. 1 regulating valve 4 is closed after the current of the electric feed pump 6 returns to normal. Specifically, after the electric feed pump 6 is started for 9 seconds, the No. 1 regulating valve 4 starts to be closed. The duration of closing the No. 1 regulating valve 4 was 32 s.

Referring to fig. 2, a starting current curve of the electric feed water pump after the steam feed water pump trips is provided according to an embodiment of the present invention;

the trip time of the steam feed pump is 20:33:20, the electric feed pump is started in an interlocking way, the current of the electric feed pump is rapidly increased, when the current returns to normal from the maximum value, the electric pump is started normally, and the trip time is 20:33: 28; therefore, the starting time for closing the No. 1 regulating valve is 9s after the electric feed pump is started.

The valve closing rate is set to close the No. 1 regulator valve. The rate at which the No. 1 regulating valve is closed determines the time for which the boiler is returning feedwater. The closing speed of the No. 1 regulating valve is too fast, so that great impact and burden are caused to an electric water supply system, and the electric water supply pump can be damaged if the closing speed is too fast; the speed of closing the No. 1 regulating valve is too slow, the lower the output of the electric feed water pump is increased, the smaller the load of the electric feed water pump is, but the longer the time for the boiler to recover the feed water, namely the time for the boiler to cut off the water, the dry burning phenomenon of the water cooling wall can occur, and the temperature of the water cooling wall can rapidly rise. Therefore, the closing time of the recirculation valve is required to be compatible with the wall temperature rising process of the water wall and the current change process of the electric feed pump.

Referring to FIG. 3, a graph of motor feed pump current and fluid coupling feedback provided by one embodiment of the present invention is plotted as a function of motor feed pump recirculation valve closing.

And 20:33:29, starting to close the recirculation valve, 20:34:01, closing the recirculation regulating valve to 0.9%, considering that the No. 1 recirculation regulating valve is fully closed, the whole process takes 32 seconds, the current change curve of the electric feed pump is normal, and the electric feed pump operates normally.

Referring to fig. 4, the wall temperature change curves of different water-cooled walls after the steam feed pump according to an embodiment of the present invention trips;

after the steam feed pump trips, the wall temperature of each water cooling wall gradually increases during the water cut-off period, and after the electric feed pump normally operates, the wall temperature gradually decreases to a normal level along with the normal RB process after the temperature of the water cooling walls is reduced in speed; wherein the front wall temperature increases the most, about 45 ℃. The boiler wall temperature is in the withstand stage.

Therefore, when the closing time of the No. 1 regulating valve is 32s, the electric feed pump operates normally, and the wall temperature of the boiler does not exceed the temperature.

The boiler deoxygenation water supply system in the present disclosure is only provided with one steam-driven water supply pump and one electric water supply pump. Compared with a double-air pump system, the system in the disclosure has a simple structure, and the steam feed pump control system is simple to operate and can still adopt the electric feed pump to start the system under the condition of no auxiliary steam source. Compared with the traditional single steam pump and single electric pump system, when the steam-driven feed pump breaks down or is manually cut off, the electric pump of the traditional deoxygenation water supply system cannot meet the boiler water supply requirement under the high-load condition and can only be shut down in an unplanned manner, the system can meet the requirement of continuing to supply water to the boiler after the electric feed pump and the electric feed pump are arranged to boost together, and meanwhile, by the quick start control method for the electric feed pump, RB can be carried out to enable the coordination system to slowly reduce the output power to the operating condition of the electric feed pump, and the continuous safe and stable operation without shutdown when the steam-driven feed pump of the unit is tripped is realized.

In the description of the specification, reference to the description of "one embodiment", "preferably", "an example", "a specific example" or "some examples", etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention, and schematic representations of the terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.