Low-temperature flue gas cooling system of shutdown combustor and parameter design method thereof

Abstract

The invention discloses a low-temperature flue gas cooling system of a shutdown combustor and a parameter design method of the low-temperature flue gas cooling system. The low-temperature flue gas is led out from an outlet of the boiler induced draft fan, and the primary tuyere and the secondary tuyere of the standby combustor are respectively cooled by the mother pipe, the branch mother pipe, the branch pipe and the branch pipe in sequence. According to the low-temperature flue gas cooling system of the shutdown combustor and the parameter design method thereof, the low-temperature flue gas at the outlet of a boiler induced draft fan cools the shutdown combustor, so that the problems that due to the air cooling, the cooling air volume requirement is large, the boiler ash combustible matter is increased, the NOx concentration of a hearth outlet is increased, the exhaust gas temperature is increased, the fan electricity consumption is high, and a primary air nozzle is prone to burning loss, can be solved.

Description

Technical field: [0001] The invention relates to a low-temperature flue gas cooling system of a burner in standby and a parameter design method thereof. Background technique: [0002] The number of burners and the number of layers of large-scale power plant boilers are designed according to the BMCR working condition, and the actual operating load is mostly lower than the evaporation capacity of the BMCR working condition. Therefore, if the design coal is burned, some burners are always in the state of stop and standby in actual operation. In recent years, due to the adjustment of industrial structure and the construction of a large number of new energy projects for power generation, the annual utilization hours of thermal power units have been greatly reduced, some units are even less than 2,000 hours, a considerable number of units have a load rate of less than 60%, and deep peak regulation is even less than 30%. Therefore, the number of boiler shutdown burners is greatly ...

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Problems solved by technology

[0004] The secondary air nozzle of the existing standby burner is cooled by the hot air of the secondary air box, and the air temperature is mostly between 290°C and 360°C. Compared with low-temperature medium cooling, the cooling effect is poor. In order to ensure that the wall temperature of the standby burner does not exceed the standard, The increase in the input cooling air volume will further aggravate the increase in the ash combustibles and the NOx concentration of the flue gas at the furnace outlet, and the power consumption of the fan will also increase

[0005] The primary air nozzle of the existing idle burner is cooled by the large valve of the primary air duct before the burner or the cold air at the inlet of the coal mill. This part of the cold air directly enters the furnace without passing through the air preheater, which reduces the cooling effect of the air preheater. , leading to an increase in the exhaust gas temperature, the range of increase depends on the number of burners in standby and the cooling air volume, mostly between 2°C and 4°C

[0006] In the existing cooling method of the large air valve of the previous air duct of the burner, since the inlet of the atmospheric air valve is equipped with a relatively fine filter screen, the air floating objects are easy to block the filter screen, and the filter screen has no differential pressure monitoring. If the burner has no wall temperature measuring point, it is easy to cause burner burnout

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