CN-122015106-A - Whole process SCR denitration system

CN122015106ACN 122015106 ACN122015106 ACN 122015106ACN-122015106-A

Abstract

The invention discloses an overall process SCR denitration system, and relates to the technical field of coal-fired power plant boiler denitration systems. The boiler is connected with the SCR denitration reactor through a flue, a boiler furnace is composed of a water-cooled wall, the whole-process SCR denitration bypass system is further comprised, the whole-process SCR denitration bypass system comprises a bypass pipeline, a bypass ash discharging system and a bypass adjusting system, the bypass pipeline comprises a flue gas bypass interface, a denitration flue gas bypass branch pipe, a denitration flue gas bypass main pipe and a denitration flue gas injection branch pipe, and the bypass adjusting system comprises a shutoff baffle and an adjusting baffle. The invention can realize the whole process investment of the SCR denitration system from the ignition of the boiler to BMCR loads, shortens the investment time of the denitration system, solves the problem of emission of the nitrogen oxide pollutants in the flue gas during the period from the ignition of the boiler to the grid connection of the unit, reduces the emission of the nitrogen oxide, improves the pollutant emission level of a power plant, and has certain social and environmental benefits.

Inventors

HAN LIANG
SUN DONGTING
LI XIN
CHEN QI
WANG XIN
SHI YUHAN

Assignees

中国电力工程顾问集团中南电力设计院有限公司

Dates

Publication Date: 20260512
Application Date: 20260325

Claims (5)

1. The whole-process SCR denitration system comprises a boiler (100) and an SCR denitration reactor (200), wherein the boiler (100) and the SCR denitration reactor (200) are connected through a flue (300), and a boiler (100) hearth consists of a membrane water wall (110), and is characterized by further comprising a whole-process SCR denitration bypass system (400), wherein the whole-process SCR denitration bypass system (400) comprises a bypass pipeline (410), a bypass ash discharge system (420) and a bypass regulation system (430); the bypass pipeline (410) comprises a flue gas bypass interface (411) connected with the water-cooled wall (110), a denitration flue gas bypass branch pipe (412) connected with the flue gas bypass interface (411), a denitration flue gas bypass main pipe (413) connected with the denitration flue gas bypass branch pipe (412), and a denitration flue gas injection branch pipe (414) connected with the denitration flue gas bypass main pipe (413), wherein the denitration flue gas injection branch pipe (414) is connected with a flue (300) close to one side of the SCR denitration reactor (200); the bypass ash discharge system (420) comprises an ash discharge port (421) arranged at the lowest point of the denitration flue gas bypass branch pipe (412), an ash discharge pipeline (422) connected with the ash discharge port (421), an ash discharge shutoff baffle (423) arranged on the ash discharge pipeline (422), and a bin pump ash conveying system (424) connected with the ash discharge pipeline (422); the bypass regulating system (430) comprises a denitration flue gas bypass main pipe (413), a shutoff baffle (431) and a regulating baffle (432), wherein the shutoff baffle (431) and the regulating baffle (432) are arranged between the connection part of the denitration flue gas bypass branch pipe (412) and the denitration flue gas bypass main pipe (413) and the denitration flue gas injection branch pipe (414) in sequence.
2. The whole process SCR denitration system as set forth in claim 1, wherein when the boiler (100) is a pi-type boiler, the flue (300) comprises a horizontal flue (310) connected with the top of the boiler (100), and a tail shaft (320) connected with the horizontal flue (310); The denitration flue gas spraying branch pipe (414) is connected with a flue (300) between the tail vertical shaft (320) and the SCR denitration reactor (200).
3. The whole-process SCR denitration system according to claim 2 is characterized in that a screen superheater (120), a high-temperature superheater (130) and a high-temperature reheater (140) are sequentially arranged between the top of the boiler (100) and a horizontal flue (310), the tail shaft (320) comprises a front shaft (321) and a rear shaft (322), a low-temperature reheater (3211) is arranged in the front shaft (321), a front shaft flue gas baffle (3212) is arranged at an outlet of the front shaft (321), a low-temperature superheater (3221) and an economizer (3222) are sequentially arranged in the rear shaft (322) from top to bottom, and a rear shaft flue gas baffle (3223) is arranged at an outlet of the rear shaft (322); the joint of the flue gas bypass interface (411) and the water cooling wall (110) is positioned below the screen-type superheater (120).
4. The whole process SCR denitration system as claimed in claim 1, wherein when the boiler (100) is a tower type boiler, a heating surface (150) is arranged at the upper part in the boiler (100), and a flue gas baffle (160) is arranged at the top of the boiler (100); The joint of the flue gas bypass interface (411) and the water cooling wall (110) is positioned below the heating surface (150).
5. The whole process SCR denitration system as claimed in claim 1, wherein the left wall (111) and the right wall (112) of the water-cooled wall (110) are connected with a plurality of flue gas bypass interfaces (411), and a plurality of denitration flue gas injection branch pipes (414) are arranged at intervals.

Description

Whole process SCR denitration system Technical Field The invention relates to the technical field of a coal-fired power plant boiler denitration system, in particular to a whole-process SCR denitration system. Background The 5 th requirement of the technical specification of flue gas denitration design of the thermal power plant (DL/T5480-2013) is that a denitration system can continuously and safely operate between the lowest stable combustion load of a boiler and any working condition between BMCR, when the flue gas temperature cannot reach the lowest operation temperature of a catalyst under the working condition of the lowest stable combustion load of the boiler, corresponding measures are taken to improve the inlet temperature of the reactor, and according to the specification, the boiler of the thermal power plant can be put into the denitration system between the lowest stable combustion load (generally 20% -30% of the boiler load) and BMCR. In actual operation, the thermal power plant generally inputs the denitration system from the unit grid connection (zero boiler load) according to the requirements of the local environmental protection department, namely, the denitration system continuously and safely operates according to any working condition from grid connection to BMCR. However, even though the unit is put into the SCR denitration system from grid connection during actual operation, the temperature rising process still needs to be carried out for 8 hours or more between the ignition of the boiler and grid connection of the unit under the limitation of the temperature rising rate of the boiler body, during the period, the flue gas temperature at the inlet of the SCR denitration system does not meet the denitration input requirement, a large amount of flue gas generated by the combustion of the boiler is discharged into the environment atmosphere without being treated by the denitration system, so that a large amount of nitrogen oxide pollutants in the flue gas are discharged, and the environment is influenced to a certain extent. Therefore, it is necessary to develop a whole-process SCR denitration system capable of increasing the inlet smoke temperature of the SCR system and realizing continuous operation of the SCR denitration system from boiler ignition. Disclosure of Invention The invention aims to overcome the defects of the background technology and provide a whole-process SCR denitration system, solves the problem that the existing SCR denitration system of the coal-fired unit boiler cannot be put into operation in the period from boiler ignition to unit grid connection, effectively improves the inlet smoke temperature of the SCR denitration system, shortens the input time of the denitration system, reduces the emission of nitrogen oxides during the starting of the boiler, and realizes the whole-process denitration of the boiler from ignition to BMCR working conditions. In order to achieve the aim, the technical scheme of the invention is that the whole-process SCR denitration system comprises a boiler and an SCR denitration reactor, wherein the boiler and the SCR denitration reactor are connected through a flue, and a boiler hearth consists of a water cooling wall, and the whole-process SCR denitration bypass system is characterized by further comprising a bypass pipeline, a bypass ash discharging system and a bypass adjusting system; The bypass pipeline comprises a flue gas bypass interface connected with the water-cooled wall, a denitration flue gas bypass branch pipe connected with the flue gas bypass interface, a denitration flue gas bypass main pipe connected with the denitration flue gas bypass branch pipe, and a denitration flue gas spraying branch pipe connected with the denitration flue gas bypass main pipe, wherein the denitration flue gas spraying branch pipe is connected with a flue close to one side of the SCR denitration reactor; the bypass ash discharge system comprises an ash discharge port arranged at the lowest point of the denitration flue gas bypass branch pipe, an ash discharge pipeline connected with the ash discharge port, an ash discharge shutoff baffle arranged on the ash discharge pipeline, and a bin pump ash conveying system connected with the ash discharge pipeline; The bypass regulating system comprises a denitration flue gas bypass main pipe, a shutoff baffle and a regulating baffle, wherein the shutoff baffle and the regulating baffle are arranged between the denitration flue gas bypass branch pipe and the denitration flue gas bypass main pipe and between the denitration flue gas spraying branch pipe and the denitration flue gas bypass main pipe. In the technical scheme, when the boiler is a pi-type boiler, the flue comprises a horizontal flue connected with the top of the boiler and a tail vertical shaft connected with the horizontal flue; And the denitration flue gas is sprayed into a flue between the branch pipe and the tail vertical shaft and between