阅读说明：本技术 一种提高电站锅炉低负荷给水温度的系统 (System for improving low-load feed water temperature of power station boiler ) 是由 褚晓亮 于帅 郝丽娜 董雅翠 于 2021-09-06 设计创作，主要内容包括：本发明公开了一种提高电站锅炉低负荷给水温度的系统,提高电站锅炉给水温度方法的步骤如下：锅炉低负荷工况下,SCR烟气温度低于催化剂需求的温度窗口,将机组回热系统一号高加的汽源由原来的高压缸换为锅炉过热器系统或主蒸汽管道的抽汽,从而提高进入机组回热系统一号高加的蒸汽压力,机组回热系统一号高加进汽压力的上升使进汽压力对应的饱和蒸汽温度上升,进而使机组回热系统一号高加出口的给水温度上升,从而使进入锅炉省煤器的给水温度上升,最终提高进入SCR反应器的烟气温度,从而达到锅炉低负荷脱硝的目的。本发明提高锅炉低负荷SCR反应器进口的烟气温度,保证了低负荷下SCR催化剂的活性,扩宽了锅炉低负荷脱硝的技术范围。(The invention discloses a system for increasing the low-load feed water temperature of a utility boiler, which comprises the following steps: under the low-load working condition of the boiler, the SCR flue gas temperature is lower than a temperature window required by a catalyst, a steam source of a unit regenerative system with high pressure is replaced by steam extraction of a boiler superheater system or a main steam pipeline from an original high-pressure cylinder, so that the steam pressure entering the unit regenerative system with high pressure is improved, the rising of the steam pressure of the unit regenerative system with high pressure enables the temperature of saturated steam corresponding to the steam pressure to rise, the water supply temperature of a unit regenerative system with high pressure is further increased, the water supply temperature entering a boiler economizer is increased, and the flue gas temperature entering the SCR reactor is finally increased, so that the low-load denitration purpose of the boiler is achieved. The invention improves the flue gas temperature at the inlet of the low-load SCR reactor of the boiler, ensures the activity of the SCR catalyst under low load, and widens the technical range of low-load denitration of the boiler.)

1. The utility model provides a system for improve power plant boiler low-load feedwater temperature which characterized in that: a heating steam source pipeline (16) is added on a section of steam extraction pipeline (12) of a first high-pressure heater (4) of the unit regenerative system, and a steam source is taken from a superheated steam system (3) of a boiler (1) or a main steam pipeline (11) of a superheated steam system (3) to a high-pressure cylinder (2) of a steam turbine.

2. The system for increasing the temperature of utility boiler low load feedwater of claim 1, wherein: a pressure reducing valve (15) is arranged on the heating steam source pipeline (16).

Technical Field

The invention relates to the technical field of low-load denitration of power station boilers, in particular to a system for improving the low-load water supply temperature of the power station boiler.

Background

The energy structure mainly based on coal and the utilization of the energy structure through direct combustion are one of the main reasons for atmospheric pollution in China. In order to guarantee the air quality, China requires that all power station boilers must adopt an advanced pollutant treatment technology to control the total pollutant emission amount of a unit and execute a stricter emission standard.

In the future, new energy needs to be developed vigorously for a long time, and the action of the coal-fired unit is gradually changed from power generation to power grid peak shaving. The change in the action of the coal-fired unit results in the change in the operating parameters of the unit, and the coal-fired unit will be in a half-load or low-load state most of the time.

However, all large coal-fired units in China have been upgraded and modified in denitration technology before, and over 90% of the units are selected by a Selective Catalytic Reduction (SCR) method. In order to meet the temperature window of the SCR catalyst, the inlet flue gas temperature is required to be more than 300 ℃ in the running process of the unit. When the smoke temperature at the SCR inlet is lower than 300 ℃, the SCR cannot normally operate, so that the NOx emission concentration is ultralow, the catalyst is inactivated, the ammonia slip is increased, and the like. Therefore, a low-load denitration technology is required to meet the NOx emission requirement, and the full-load and full-time stable emission requirement above the lowest technical output is realized.

The current low-load denitration technology mainly comprises the following steps: a water side bypass of the economizer, a flue gas bypass of the economizer, feed water recirculation of the economizer, a grading economizer, zero-grade high-pressure feeding, boiler water recirculation and the like. Although the existing low-load denitration technology has more means, the problems of limited arrangement space, limited temperature raising effect, high investment, complex system and the like generally exist.

Disclosure of Invention

In order to solve the defects of the technology, the invention provides a system for increasing the low-load feed water temperature of a utility boiler.

In order to solve the technical problems, the invention adopts the technical scheme that: the utility model provides a system for improve power plant boiler low-load feedwater temperature, it includes that unit backheat system No. two adds highly, the export that unit backheat system No. two adds highly is through input pipeline intercommunication unit backheat system No. one adds highly, unit backheat system No. one adds highly through drain pipe intercommunication unit backheat system No. two adds highly, unit backheat system No. one adds highly through steam extraction pipeline intercommunication steam turbine high pressure jar, unit backheat system No. one adds highly the export through water supply line intercommunication boiler, the boiler passes through main steam pipeline intercommunication steam turbine high pressure jar, the heating air supply of boiler is through heating steam source pipeline intercommunication steam extraction pipeline.

Furthermore, the steam extraction pipeline is provided with a steam extraction check valve and a steam extraction shutoff valve.

Furthermore, a pressure reducing valve is arranged on the heating steam source pipeline, one end of the heating steam source pipeline is communicated with the main steam pipeline or a superheated steam system of the boiler, and the other end of the heating steam source pipeline is communicated with a pipeline between a steam extraction check valve and a steam extraction shutoff valve on the steam extraction pipeline and a unit regenerative system, wherein the steam extraction check valve and the steam extraction shutoff valve are arranged on the steam extraction pipeline.

The original steam extraction system with the high-pressure steam addition in the unit heat recovery system is closed, and a heating steam source with the high-pressure steam addition in the unit heat recovery system is changed into decompressed superheated steam; as the steam pressure entering the unit heat recovery system with the high pressure at the same number rises, the saturated steam temperature of the steam rises, and the water supply temperature of the unit heat recovery system with the high pressure at the same number rises;

when the steam pressure entering the unit regenerative system with the high pressure at the same number rises, the corresponding saturated steam temperature rises, and the water supply temperature of the unit regenerative system with the high pressure at the same number also rises; the rising of the feed water temperature can finally lead the temperature of the flue gas at the inlet of the SCR reactor to rise, thereby leading the SCR reactor to meet the denitration temperature requirement under the low-load working condition of the boiler;

under the working condition of low load of the boiler, when the temperature of the flue gas at the inlet of the SCR reactor is lower, the opening of the pressure reducing valve is adjusted, so that the steam pressure entering a unit regenerative system with a high pressure is increased, and the water supply temperature of a unit regenerative system with a high pressure outlet is increased;

and regulating repeatedly according to the change condition of the inlet flue gas temperature of the SCR reactor.

The invention discloses a system for improving the low-load water supply temperature of a power station boiler, which improves the flue gas temperature at the inlet of a low-load SCR reactor of the boiler by a method for improving the water supply temperature of the power station boiler, ensures the activity of an SCR catalyst under low load and widens the technical range of low-load denitration of the boiler.

Drawings

Fig. 1 is a conventional thermodynamic flow diagram.

Fig. 2 is a thermodynamic flow diagram of the present invention.

In the figure: 1. a boiler; 2. a high-pressure cylinder of the steam turbine; 3. a superheated steam system; 4. the unit backheating system has a high-grade; 5. a second high pressure heater of a heat regenerative system of the unit; 6. a coal economizer; 7. an SCR reactor; 8. a steam extraction check valve; 9. a steam extraction shutoff valve; 10. a drain pipe; 11. a main steam line; 12. a steam extraction pipeline; 13. a water supply pipe; 14. an input pipe; 15. a pressure reducing valve; 16. heating the steam source pipeline.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

The conventional thermal flow chart shown in fig. 1 includes a unit regenerative system with a second high heater 5, an outlet of the unit regenerative system with the second high heater 5 is communicated with a unit regenerative system with a second high heater 4 through an input pipeline 17, and the unit regenerative system with the second high heater 4 is communicated with the unit regenerative system with the second high heater 5 through a drain pipeline 10. The high 4 that adds of unit backheating system is through steam extraction pipeline 12 intercommunication steam turbine high pressure cylinder 2, the high 4 export that adds of unit backheating system passes through economizer 6 in the water supply pipeline 13 intercommunication boiler 1, boiler 1 includes economizer 6, superheated steam system 3 and SCR reactor 7, water supply pipeline 13 intercommunication economizer 6, the high temperature feedwater after economizer 6 heats gets into superheated steam system 3, the flue gas of boiler 1 gets into SCR reactor 7 after economizer 6 and carries out the denitration treatment of flue gas. The boiler 1 is communicated with the high-pressure turbine cylinder 2 through a main steam pipeline 11, as shown in the thermal flow chart of the invention shown in fig. 1, compared with the conventional thermal flow chart, a heating air source of the boiler 1 is communicated with a steam extraction pipeline 12 through a heating air source pipeline 16. The steam extraction pipeline 12 is provided with a steam extraction check valve 8 and a steam extraction shutoff valve 9.

A high-pressure check valve 14 and a pressure reducing valve 15 are arranged on a heating steam source pipeline 16, one end of the heating steam source pipeline 16 is communicated with a main steam pipeline 11 or a superheated steam system 3 of the boiler 1, and the other end of the heating steam source pipeline 16 is communicated with a pipeline between a steam extraction check valve 8 and a steam extraction shutoff valve 9 on a steam extraction pipeline 12 and a unit regenerative system with a high pressure 4.

The invention provides a method for improving the low-load water supply temperature of a power station boiler, which comprises the following steps that water supply at an outlet of a second high-pressure heater 5 of a unit regenerative system enters the unit regenerative system, the first high-pressure heater 4 of the unit regenerative system is heated, a steam extraction shutoff valve 9 on a steam extraction pipeline 12 is closed, a heating steam source pipeline 16 is additionally arranged on the steam extraction pipeline 12, and a heating steam source is taken from a superheated steam system 3 of a boiler 1 or from the superheated steam system 3 to a main steam pipeline 11 of a steam turbine high-pressure cylinder 2; a pressure reducing valve 15 is arranged on the newly added heating steam source pipeline 16, and the heating steam source pipeline 16 is connected with the steam extraction pipeline 12;

the original steam extraction system of the unit heat regeneration system with the number of 4 higher is closed, and the heating steam source of the unit heat regeneration system with the number of 4 higher is changed into decompressed superheated steam; as the steam pressure entering the unit heat recovery system with the high pressure of 4 increases, the saturated steam temperature of the steam increases, and the water supply temperature at the outlet of the unit heat recovery system with the high pressure of 4 increases;

the drainage with the height of 4 higher than the first number of the unit regenerative system returns to the height of 5 higher than the second number of the unit regenerative system through a drainage pipeline 10;

the water supply at the outlet of the unit regenerative system with the high pressure heater 4 after the temperature rise enters the economizer 6 at the tail part of the boiler 1 through the water supply pipeline 13, the high-temperature water supply heated by the economizer 6 continues to enter the superheated steam system 3 of the boiler 1, and the superheated steam generated by the superheated steam system 3 enters the high-pressure cylinder 2 of the steam turbine to do work; flue gas of the boiler 1 passes through the economizer 6 and then enters the SCR reactor 7 for denitration treatment of the flue gas;

because the heat transfer of the unit regenerative system with the high steam pressure of 4 is mainly limited by the water supply end difference and the water drainage end difference, the water supply end difference refers to the difference between the saturated steam temperature corresponding to the steam inlet pressure of the unit regenerative system with the high steam pressure of 4 and the outlet water supply temperature, which means that: the higher the steam saturation temperature is, the higher the water supply temperature of a unit regenerative system with a high-pressure-increasing 4 outlet is.

When the steam pressure entering the unit heat recovery system with the value of 4 added at the high level rises, the corresponding saturated steam temperature rises, and the water supply temperature at the outlet of the unit heat recovery system with the value of 4 added at the high level also rises; the rising of the feed water temperature can finally lead the temperature of the flue gas at the inlet of the SCR reactor 7 to rise, thereby leading the SCR reactor 7 to meet the denitration temperature requirement under the low-load working condition of the boiler 1;

under the working condition of low load of the boiler 1, when the temperature of the flue gas at the inlet of the SCR reactor 7 is lower, the opening of the pressure reducing valve 15 is adjusted, so that the steam pressure entering the unit regenerative system with the high pressure of 4 is increased, and the water supply temperature of the outlet of the unit regenerative system with the high pressure of 4 is increased;

so far, according to the change situation of the inlet flue gas temperature of the SCR reactor 7, the regulation is repeated.

The invention discloses a system for improving the low-load water supply temperature of a power station boiler, which improves the flue gas temperature at the inlet of a low-load SCR reactor of the boiler by a method for improving the water supply temperature of the power station boiler, ensures the activity of an SCR catalyst under low load and widens the technical range of low-load denitration of the boiler.

The above embodiments are not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make variations, modifications, additions or substitutions within the technical scope of the present invention.