阅读说明：本技术 一种锅炉脱硝系统入口烟气温度调节系统及方法 (System and method for regulating temperature of inlet flue gas of boiler denitration system ) 是由 车刚 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种锅炉脱硝系统入口烟气温度调节系统及方法,包括：锅炉尾部垂直烟道、脱硝入口烟道以及连接于两者之间的尾部水平烟道,尾部水平烟道上设置有第一调节挡板；锅炉尾部垂直烟道和脱硝入口烟道之间额外的连接有旁路烟道；旁路烟道的横截面覆盖设置有蒸汽加热器和第二调节挡板,第二调节挡板位于蒸汽加热器的上游。能够灵活调节脱硝系统入口的烟气温度,有效解决由于入口烟气温度低而使脱硝系统不能投入的问题,使锅炉在极低负荷或者点火期间时也能正常投用脱硝系统,不影响水、汽受热面的吸热比例,实现机组的全工况脱硝系统投入,具有较高的社会效益和经济效益。(The invention discloses a system and a method for regulating the temperature of flue gas at an inlet of a boiler denitration system, wherein the method comprises the following steps: the denitration device comprises a boiler tail vertical flue, a denitration inlet flue and a tail horizontal flue connected between the boiler tail vertical flue and the denitration inlet flue, wherein a first adjusting baffle is arranged on the tail horizontal flue; a bypass flue is additionally connected between the vertical flue at the tail part of the boiler and the denitration inlet flue; the cross section of the bypass flue covers and is provided with a steam heater and a second adjusting baffle, and the second adjusting baffle is positioned at the upstream of the steam heater. The denitration system can flexibly adjust the flue gas temperature at the inlet of the denitration system, effectively solves the problem that the denitration system cannot be put into use due to low inlet flue gas temperature, enables the boiler to be normally put into use when the boiler is in an extremely low load or in an ignition period, does not influence the heat absorption proportion of water and steam heating surfaces, realizes the full-working-condition denitration system of the unit, and has higher social benefit and economic benefit.)

1. The utility model provides a boiler deNOx systems entry flue gas temperature governing system which characterized in that: the method comprises the following steps: the denitration device comprises a boiler tail vertical flue, a denitration inlet flue and a tail horizontal flue connected between the boiler tail vertical flue and the denitration inlet flue, wherein a first adjusting baffle is arranged on the tail horizontal flue;

a bypass flue is additionally connected between the vertical flue at the tail part of the boiler and the denitration inlet flue;

the cross section of the bypass flue covers and is provided with a steam heater and a second adjusting baffle, and the second adjusting baffle is positioned at the upstream of the steam heater.

2. The boiler denitration system inlet flue gas temperature regulation system of claim 1, characterized in that: the bypass flue is positioned above the tail horizontal flue.

3. The boiler denitration system inlet flue gas temperature adjusting system of claim 2, characterized in that: the bypass flue is positioned below the tail flue heated assembly.

4. The boiler denitration system inlet flue gas temperature regulation system of claim 1, characterized in that: the steam heater is externally connected with a steam source.

5. The boiler denitration system inlet flue gas temperature regulation system of claim 1, characterized in that: the power source of the first adjusting baffle and the second adjusting baffle is a motor.

6. The boiler denitration system inlet flue gas temperature regulation system of claim 1, characterized in that: the air heater is arranged at the downstream of the denitration system.

7. The boiler denitration system inlet flue gas temperature regulation system of claim 1, characterized in that: still include temperature element, temperature element sets up on denitration entry flue.

8. The boiler denitration system inlet flue gas temperature adjusting system of claim 7, characterized in that: the temperature measuring device further comprises a control system, the control system is respectively connected with the motor and the temperature measuring element, and the motor is connected with the first adjusting baffle and the second adjusting baffle through the driving mechanism.

9. A method for adjusting the temperature of flue gas at an inlet of a boiler denitration system is characterized by comprising the following steps: the method comprises the following steps:

when the flue gas temperature of the flue gas denitration inlet is too low, the opening degree of the first adjusting baffle is reduced, the opening degree of the second adjusting baffle is increased, so that the boiler flue gas flows through all heating surfaces at the tail part, part or all of the boiler flue gas flows through the steam heater in the bypass flue to be heated, and the heated flue gas enters the denitration inlet flue.

10. The method for adjusting the temperature of the flue gas at the inlet of the boiler denitration system according to claim 9, wherein: the heated flue gas flows through an air preheater and a low-temperature economizer after denitration.

Technical Field

The invention belongs to the technical field of flue gas treatment, and particularly relates to a system and a method for regulating the temperature of flue gas at an inlet of a boiler denitration system.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

Due to the need of power grid regulation and control and new energy absorption for power generation, the existing thermal generator set is oftenThe deep peak regulation is needed to carry out long-time low-load operation, at the moment, the inlet flue gas temperature of the denitration system becomes lower, the lowest allowable temperature condition of the input of the denitration system cannot be reached, and if the flue gas temperature is not adjusted in time, the nitrogen oxide NO which is withdrawn from the denitration system and discharged is caused_XAnd the environmental protection limit value is triggered due to the exceeding of the standard, so that fine money or shutdown is caused, and the use efficiency and the economical efficiency of the unit are greatly limited. The existing denitration system inlet flue gas temperature adjusting method is single, mainly adopts a flue gas bypass input method, the method sucks flue gas from a high-temperature area and leads the flue gas to a denitration inlet through an additional bypass so as to adjust the temperature of the denitration inlet, but the method influences the heat absorption of other heated surfaces such as a low-temperature reheater, a low-temperature superheater, an economizer and the like, and causes the change of heat distribution, thereby influencing the economical efficiency of a unit (the steam temperature is reduced due to the reduction of the heat absorption of the superheated steam and the reheater, and the water supply temperature is reduced due to the reduction of the heat absorption of the economizer, so the economical efficiency of the unit is reduced). In addition, methods for improving the temperature of the denitration inlet flue gas also comprise economizer classification, flue separation and the like, the heating surface or the boiler structure needs to be greatly changed, the investment is high, the adjustment is not flexible, the effect is poor, and the methods cannot be used after the load of a unit is low to a certain degree.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a system and a method for regulating the inlet flue gas temperature of a boiler denitration system, which can flexibly regulate the inlet flue gas temperature of the denitration system, effectively solve the problem that the denitration system cannot be put into use due to low inlet flue gas temperature, ensure that the boiler can be normally put into use when the boiler is in an extremely low load or in an ignition period, do not influence the heat absorption ratio of a water heating surface and a steam heating surface, realize the full-working-condition denitration system of a unit, and have higher social benefit and economic benefit.

In order to achieve the purpose, the invention is realized by the following technical scheme:

in a first aspect, the present invention provides a system for regulating a temperature of flue gas at an inlet of a boiler denitration system, comprising: the denitration device comprises a boiler tail vertical flue, a denitration inlet flue and a tail horizontal flue connected between the boiler tail vertical flue and the denitration inlet flue, wherein a first adjusting baffle is arranged on the tail horizontal flue;

a bypass flue is additionally connected between the vertical flue at the tail part of the boiler and the denitration inlet flue;

the cross section of the bypass flue covers and is provided with a steam heater and a second adjusting baffle, and the second adjusting baffle is positioned at the upstream of the steam heater.

In some embodiments, the bypass stack is located above the aft horizontal stack.

Further, the bypass flue is located below the heated component of the tail flue. The tail flue heating assembly comprises a low-temperature superheater, a low-temperature reheater, an economizer and the like.

In some embodiments, the steam heater is external to the steam source.

In some embodiments, the power source of the first and second adjusting baffles is a motor.

In some embodiments, an air preheater is disposed downstream of the denitration system.

In some embodiments, the denitration flue gas inlet device further comprises a temperature measuring element, and the temperature measuring element is arranged on the denitration inlet flue gas flue.

Furthermore, the temperature measuring device further comprises a control system, wherein the control system is respectively connected with the motor and the temperature measuring element, and the motor is connected with the first adjusting baffle and the second adjusting baffle through a driving mechanism.

The temperature measuring element measures the flue gas temperature in the denitration inlet flue, and transmits the temperature to the control system, and the control system adjusts the start and stop of the motor according to the temperature signal, and then controls the actions of the first adjusting baffle and the second adjusting baffle respectively.

In a second aspect, the invention provides a method for adjusting the temperature of flue gas at an inlet of a boiler denitration system, which comprises the following steps:

when the flue gas temperature of the flue gas denitration inlet is too low, the opening degree of the first adjusting baffle is reduced, the opening degree of the second adjusting baffle is increased, so that the boiler flue gas flows through all heating surfaces at the tail part, part or all of the boiler flue gas flows through the steam heater in the bypass flue to be heated, and the heated flue gas enters the denitration inlet flue.

In some embodiments, the heated flue gas flows through an air preheater and a low-temperature economizer after denitration.

The above one or more embodiments of the invention achieve the following advantageous effects:

through additionally arranging the bypass flue, the bypass steam heater and the adjusting baffle in the boiler tail flue, whether the set DCS is automatically (or manually operated by an operator) judged and the system is controlled to adjust the opening of the flue gas baffle, the flue gas quantity entering the bypass flue for heating is adjusted, and the purpose of adjusting the temperature of the flue gas at the denitration inlet is achieved. The system can flexibly adjust the inlet flue gas temperature of the denitration system, effectively solves the problem that the denitration system cannot be put into use due to low inlet flue gas temperature, enables the boiler to be normally put into use when the boiler is in an extremely low load or in an ignition period, has small change of the original system and low input cost, does not influence the heat absorption proportion of water and steam heating surfaces, realizes the full-working-condition denitration system of the unit, and has high social benefit and economic benefit.

Because the flue gas temperature is improved, the low-temperature corrosion problem of the air preheater and the low-temperature economizer can be effectively solved, and in addition, the hot air temperature at the outlet of the air preheater can be improved, thereby being beneficial to stabilizing the combustion of the boiler when the load is low and improving the operation safety.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic block diagram of a system according to one or more embodiments of the invention.

In the figure: the mutual spacing or size is exaggerated to show the position of each part, and the schematic diagram is only used for illustration;

wherein, 1-tail flue heating surface (low temperature superheater, low temperature reheater, economizer, etc.); 2-a vertical flue at the tail part; 3-a first regulating baffle; 4-a steam heater; 5-horizontal flue at tail; 6-a denitration system reaction zone; 7-denitration inlet flue; 8-bypass steam heater steam line; 9-bypass steam heater drain line; 10-a second regulating baffle; 11-bypass flue.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The invention will be further explained with reference to the drawings.

As shown in fig. 1, a system and a method for regulating the temperature of flue gas at an inlet of a boiler denitration system include: a bypass flue 11 is additionally arranged between the boiler tail vertical flue 2 and the denitration inlet flue 7, the bypass flue 11 is basically parallel to the tail horizontal flue 5, the inlet of the bypass flue 11 is connected with the tail vertical flue 2, the outlet of the bypass flue 11 is connected with the denitration inlet flue 7, and the tail vertical flue 2, the tail horizontal flue 5 and the denitration inlet flue 7 are original channels of the boiler. A bypass steam heater 4 is arranged in a bypass flue 11, and a first adjusting baffle 3 and a second adjusting baffle 10 are respectively and additionally arranged at the inlets of a tail horizontal flue 5 and the bypass flue 11.

The steam heater 4, the first adjusting baffle 3 and the second adjusting baffle 10 are connected with a unit DCS (distributed control system) system through a driving mechanism, a logic control module is added in the DCS and used for comparing the current denitration inlet flue gas temperature with a preset denitration inlet flue gas temperature limit value, if the current denitration inlet flue gas temperature is greater than the preset denitration inlet flue gas temperature limit value, the steam heating system is not put into use, the second adjusting baffle 10 is closed, and the first adjusting baffle 3 is fully opened; if the former is less than or equal to the latter, the steam heating system is automatically put into the denitration system, the opening degree of the second adjusting baffle 10 is correspondingly adjusted to be larger, the opening degree of the first adjusting baffle 3 is correspondingly adjusted to be smaller, the flue gas flow in the bypass flue 11 is increased, and the flue gas is heated by the bypass steam heater 4 until the current denitration inlet flue gas temperature is greater than the preset temperature limit value, so that the denitration system is ensured not to exit.

The flue gas after denitration in the denitration system reaction zone 6 flows through an air preheater and a low-temperature economizer.

The bypass flue 11 is basically parallel to the tail horizontal flue 5, but no special requirement is imposed on the included angle between the two flues, and the adjusting effect is not influenced even if the flues are not parallel.

The flue gas baffle realizes the regulation of its aperture through actuating mechanism, and actuating mechanism can adopt driving motor or other existing drive modes to realize.

The steam heater 4 has a plurality of steam sources, and can be used for auxiliary steam header steam extraction, local or adjacent machine steam extraction, and local or adjacent furnace reheater or superheater steam extraction. Any heat source with a suitable temperature can be used to heat the flue gas.

A thermocouple or temperature sensor for measuring denitration entry flue gas temperature is boiler existing facilities, and the person of ordinary skill in the art can specifically select the model according to actual conditions. The thermocouple or the temperature sensor is used for monitoring the inlet flue gas temperature in real time and transmitting the inlet flue gas temperature to the DCS, and the DCS controls the driving mechanism to adjust the opening degree of the flue gas baffle plate, so that the aim of adjusting the flue gas temperature entering the denitration device is fulfilled.

The preset denitration inlet flue gas temperature limit value is related to specific performance parameters of the denitration system, and the input temperature limit values of different denitration systems are different, for example, the preset denitration inlet flue gas temperature limit value can be set to be the lowest input temperature limit value of the denitration system plus 5-10 ℃.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.