Denitration device with economizer re-circulating system and generator unit

Abstract

The invention relates to a denitration technology, and discloses a denitration device with an economizer re-circulating system for a boiler. The temperature of a water side of an economizer is raised by using the economizer re-circulating system, so that the flue gas temperature of an outlet of the economizer can be raised under the low-load working condition, and requirements on lowermost ammonia spraying under the full-load working condition are met; the flow of the water side of the economizer keeps unchanged or is slightly increased under the control of a circulating pump of the re-circulating system, so that the phenomenon of boiling on the water side of the economizer is avoided, and the economizer can operate safely and stably.

Description

technical field [0001] The invention relates to the technical field of denitrification, in particular to a denitrification device equipped with an economizer recirculation system. Background technique [0002] my country's energy is mainly coal-fired, and the flue gas contains a large amount of sulfur dioxide and nitrogen oxides. Direct emission will cause serious pollution to the atmosphere and affect the health of the society. Environmental pollution has become a major social concern in our country. [0003] According to the requirements of GB13223-2011 "Emission Standard of Air Pollutants for Thermal Power Plants", for new units and existing units, boiler units other than "W" type flame combustion need to achieve the NOx emission limit of less than 100mg / Nm3, for " W" type flame combustion boiler units need to achieve the limit of NOx emission below 200mg / Nm3. [0004] At present, the NOx emission concentration at the furnace outlet of bituminous coal and lignite boilers...

AI Technical Summary

Problems solved by technology

There are the following problems in raising the feed water temperature: 1) For new units, it is relatively easy to implement, but it is also affected by coal quality factors. It needs to be calculated by the main engine factory, and the heat exchange area of ​​the air preheater is increased to absorb the economizer and the previous heat 2) For different units, there are still some doubts about whether there is a suitable steam source to further increase the feed water temperature. The scheme of increasing the feed water temperature has certain restrictions and can only be used on some specific units. ;3) After increasing the feed water temperature, the inlet temperature of the denitrification reactor is increased no matter in the low load condition or the full load condition, and the ammonia injection operation can be performed under the low load condition, but under the full load condition, the temperature is higher than that of the denitrification reactor. In the optimal temperature range, the number of catalysts may also need to be increased, which also increases investment and system resistance, resulting in an increase in plant power consumption

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